2nd Middle East Geosciences Conference 15-17 April 1996 Bahrain

GEO’96 ABSTRACTS

with Authors' Biographies and Photographs

(A GeoArabia supplement containing a detailed GEO’96 Conference Program is being distributed separately)

Editor’s Note

Abstracts are listed in alphabetical order by surname (family name) of the primary author. Authors whose names appear with more than one paper are identified biographically in one paper, and referenced in the other(s). Speakers are indicated by an asterix. More than one asterix indicates poster presentation by several authors.

Abstracts and biographies were sent to primary authors for proof-reading. They have also been proof- read in part by Ibrahim A. Al-Jallal, Richard D. Chimblo, Ronald B. Clark, Joshua D. Cocker, John Filatoff, Dennis J. Fyfe, Geraint W. Hughes, Panos G. Kelamis, Daniel A. Nietupski, Rex C. Price, Arnold M. Rivett and Hasan S. Talu from Saudi Aramco, and Peter J.R. Nederlof from PDO.

Some authors could not be contacted to provide photographs.

Abstracts should be referenced as:

Author(s) 1996. Title of Abstract. Presented at the 2nd Middle East Geosciences Conference GEO’96. GeoArabia: Middle East Petroleum Geosciences (Abstract), v. 1, no. 1, p. X.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 formation of oil and gas and basin Application of Source Rock Maturity modeling. He is the author of a book Studies in Basin Thermal History. and several papers on these subjects Example: Lower and Middle Cretaceous and has undertaken overseas lecture Formations of Kuwait tours. He has a BSc in Chemistry from Edinburgh University, a BA in Geology from the Open Abdullah, Fowzia H.A.* Kuwait University University and PhD from London and Robert R.F. Kinghorn University. Imperial College, UK Geographical Information System (GIS) A correlation was made between theoretical and and Remote Sensing in the experimental maturity levels to investigate the thermal history of the area. Rock samples of Lower Exploration Environment and Middle Cretaceous age were collected from four well locations in Kuwait. Maturity was measured Abel, Roger D.* and W. Mark Tuttle using the following parameters: thermal alteration Petroleum Development Oman (PDO) index TAI, vitrinite reflectance and pyrolysis thermal Geographical Information System (GIS) technology parameters. A comparison of the different and Remote Sensing have been implemented in parameters indicates that oil generation starts at a Petroleum Development Oman (PDO) within the depth of 3,050 ± 305 meters (10,000 ± 1,000 feet). The Exploration Topographic Department in support of input for the theoretical TTI index calculation were various applications over the previous two years. taken from well logs. The results indicate an This paper discusses the approach adopted by PDO, overestimated maturity level (depth of oil generation the techniques used, and the benefits to the business. = 2,530 ± 90 meters, 8,300 ± 300 feet). This might The primary uses for GIS technology within indicate that the amount of heat received by these exploration are in providing users with simple access sediments was not constant during time and was to corporate attribute data via a uniform map-based lower than present day situation by 5 to 7˚C per interface, in providing the means to carry out data kilometer as indicated by the TTI calculation. This quality control, spatial analysis, and mapping. change in geothermal gradient with time cannot be Initially GIS technology had been implemented with related directly to plate tectonic movement in the applications linking to the corporate well database, area. It might be a result of local geologic changes. to prospect and lead databases for portfolio Many geologists related the anticlines in the area management, and to seismic 2-D and 3-D location around the Gulf to be a result of epirogenic and interpretation data. Particularly for personnel movement. The possible explanation is an upward new to the PDO environment, GIS provides a tool migration of salt rocks with time that formed the for users to become quickly familiar with the broad elongated domes of the studied fields. As the available corporate data and for managers to analyze salt approaches the surface with time the geothermal data in a way not previously possible. This paper gradient increased. will demonstrate how the implementation of GIS in combination with the development of homogenous Fowzia H.A. Abdullah is an corporate databases is leading to an improvement Assistant Professor in the Geology in data quality, in wider use of common datasets, and Department of Kuwait University better decision making. since 1993. She worked as a Since January 1994, PDO has used digital satellite teaching assistant for three years at images of the earth in support of hydrocarbon Kuwait University. Fowzia joined exploration activities. Specific applications of these the Environmental Protection methods to exploration processes include mapping Department in Kuwait as a of surface sedimentation and near-surface geological researcher for two years. She has a features for identification of 3-D seismic velocity BSc in Geology and a MSc in anomalies resulting from incorrect application of Petroleum Geology from Kuwait University. She obtained statics corrections, identification of difficult and her PhD and DIC from Imperial College, London hazardous areas in support of planning seismic University in 1993 in Petroleum Geology. acquisition surveys, and assessment of environmental impact resulting from geophysical Robert R.F. Kinghorn is currently a Lecturer in the prospecting. This paper will review various Geology Department of Imperial College, University of techniques and methods of enhancing multispectral London. He has over 25 years experience in teaching and and multitemporal image data, and show specific research, principally in organic geochemistry, the examples of their application to petroleum exploration.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Roger D. Abel is currently a the impermeable beds in non-cored wells. Porosity Topographer with Shell International and permeability maps based on minimum cut-off Petroleum Company with porosity values, and aerial distribution of the basal assignments in New Zealand, dolomite unit are providing the necessary geologic Holland and Oman. Roger also control for horizontal well placement. This will worked with Gardline Surveys, UK optimize depletion of recoverable hydrocarbon, as Hydrographic Surveyor, using both long- and short-radius horizontal drilling primarily in the North Sea from technology, from the Upper Arab-D reservoir at 1980 to 1982 and with Plowman, Abqaiq Field. Craven and Associates as Land Surveyor between 1978 and 1980. Roger holds a BSc Mahdi A. Abu-Ali has been with (Honors) in Land Surveying Sciences. Saudi Aramco for 11 years in R&D, exploration and recently reservoir W. Mark Tuttle graduated in 1983 development. His areas of interest with a Diploma in Engineering and include reservoir characterization in 1988 received his BSc in Geodetic and modeling, basin analysis, Engineering. He has ten year hydrocarbon generation and cummulative experience in migration, and oil-source rock surveying and mapping within the correlations. Mahdi is affiliated service and oil industries. Mark is with the AAPG, ACS and EAOG. a member of the Association of He holds a BSc in Industrial Chemistry from King Fahd Professional Engineers, Geologists University of Petroleum and Minerals and a MSc in and Geophysicists of Canada and Geochemistry from the Colorado School of Mines, USA. the Association of Canada Land Surveyors. Abdullah S. Al-Shamsi received Characterization of the Upper Arab-D his BSc in Geology from King Fahd University of Petroleum and Reservoir, Abqaiq Field, Saudi Arabia Minerals, Saudi Arabia in 1989. After graduation he joined Saudi Abu-Ali, Mahdi A.*, Abdullah S. Al-Shamsi, Aramco and worked as a carbonate Tarek A. Bin-Afif and George A. Grover Geologist in Ghawar field studying Saudi Aramco the Arab-D reservoir using cores The Upper Arab-D, or Zone-1 reservoir represents a and thin sections. In 1994 he went significant but little produced interval within the to Canada to work with Chevron larger Arab-D reservoir at Abqaiq Field. The Arab-D Canada Resources on a training assignment for nine is divided into 3 main reservoir zones with Zones-2 months. Now Abdullah is working on 3-D seismic and 3 contributing most of the oil production. The interpretation in Abqaiq field. Upper Arab-D is less than 30 feet thick, consists of a basal low-porosity dolomite to dolomitic limestone, Tarek A. Bin-Afif has been a medial high energy skeletal-peloidal grainstone/ employed by Saudi Aramco since packstone reservoir facies, and an upper unit of his graduation from King Fahd interbedded dolomudstones, cryptalgalaminates and University of Petroleum and nodular-to-bedded anhydrites that generally grades Minerals in 1978 with a BSc degree upwards into massive anhydrite. Open hole logs in Geology. For the past four years, indicate high oil saturations, but flow meters reveal he has been involved in updating little to no contribution from Zone-1, regardless of geologic models in northern completion type in vertical wells. This necessitates Ghawar and Abqaiq fields in development of Zone-1 via long-radius (>1,000 feet support of reservoir management lateral section) and short radius (<1,000 feet) and simulation. horizontal wells to deplete recoverable oil, and to avoid contribution of water from Zone-2. George A. Grover is a Reservoir Successful development of the Upper Arab-D Geologist in the Geological Department requires detailed characterization, correlation and at Saudi Aramco. George was mapping of the basal dolomite unit, containing very previously a Research Geologist with thin (1 to 2 feet) impermeable beds within it. These Chevron Petroleum Technology beds are important in preventing cross-flow of water Company, La Habra, California (1985- from Zone-2, but are beyond the resolution level of 1990), and an Exploration Geologist open-hole logs. Porosity-permeability transforms with Gulf Oil Company, Texas (1981- from core analysis data coupled with petrographic 1985). He holds a PhD in Geology data have enhanced the ability to predict and map (1981) from Virginia Tech.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 of Waterloo in 1993. He is a Application of Computer Technology to a member of the AAPG, DGS, and is Geologic Mapping Study in currently a Geologic Specialist Saudi Arabia supporting computerization of mapping, cross sections and 3-D Al-Amer, Abdullah I., Brian E. Gratto* modeling in the Geology and Mohammed A. Waheed Department of Saudi Aramco. Saudi Aramco

Advances in computer applications that facilitate mapping, correlation and cross-sections provide an Mohammed A. Waheed graduated efficient method in studying regional geology. To in Geology from Osmania achieve the goal of providing an accurate geologic University, India in 1963. framework to support field development, drilling Mohammed has 28 years work operations and reservoir studies, this paper describes experience and has worked in the the applications and methods used to re-correlate the Exploration Department of a major Pre-Neogene to Upper Cretaceous interval in some oil company in Canada from 1967 oil fields of Saudi Arabia. The project consisted of to 1981. He joined Saudi Aramco collecting shallow log data and loading it into a cross- in 1982, and since 1985, his work section package (Pre/Mier), which was then used as includes regional geology, a project database to interactively enter new picks stratigraphic modeling, reservoir studies and training of or review and revise the existing picks. Data was Saudi professionals. Mohammed is currently a Senior Staff extracted from Pre/Mier and loaded to a mainframe Geologist working in the northern offshore areas of the database (M204) where existing routines allowed company. He is an active member of the AAPG and DGS. ZMapPlus to provide preliminary isopachs. Pre/ Mier was then utilized to re-examine and correct erroneous data that had been highlighted on these Permo-Carboniferous Glaciogenic isopachs. Changes were then reloaded to the Deposits, Al-Khlata Formation, Oman: mainframe database. The final set of integrated An Outcrop Study isopachs and structure maps was completed using the point gridding algorithm, a True Vertical Al-Belushi, Juma D.*, K.W. Glennie Thickness Macro, two seismic reference maps, and and Brian P.J. Williams the interactive editor in ZMapPlus. Stratamodel/ University of Aberdeen, Scotland GTM was then used to visualize these grids to gain a better understanding of the influence of the Pre- The Al-Khlata Formation is an oil-bearing reservoir Aruma Unconformity and stratigraphic variations in Oman. Its origin during the Late Paleozoic within the interval studied. This approach yielded Gondwana glaciation in the southern part of the some insight into the structural history of the major Arabian Peninsula is demonstrated by the oil fields and met the goals of providing an accurate glaciogenic deposits of the formation in Oman. suite of maps to support drilling operations and as a Outcrops of the Al-Khlata Formation occur in a belt basis for further reservoir studies. parallel to the Huqf fold axis, the best outcrops being found in the two wadis, Al-Khlata North and South. Abdullah I. Al-Amer completed In the southern wadi, glacial deposits rest directly his BSc in Geology (1984) from on northeast-southwest trending striated dolomites King Saud University, Riyadh. He of the Precambrian Khufai Formation. Overlying the is a member of the Dhahran striated dolomites is a 6 meter thick grey, sandy and Geological Society and has worked poorly sorted diamictite (tillite). The basal tillite unit for Saudi Aramco since 1984. His is overlain by a sequence of conglomerates and work included assignments in pebbly sandstones. The paleocurrent of the exploration, hydrology, well-site, conglomeratic unit was towards the northeast. geo-technical services and an In Wadi Al-Khlata North, the Khufai dolomites are overseas project with Texaco in not striated where exposed. The sequence of the Al- 1991. He is currently a Senior Geologist in the Northern Khlata Formation is approximately 10 meters thick Area Reservoir Geology Division, Saudi Aramco. and consists of a mixture of polymict diamictites, conglomerates, pebbly sandstones, sandstones and Brian E. Gratto received his BSc in Geology from Queens siltstones. Detailed correlation between the two University in 1977. He worked for Saudi Aramco from wadis is not possible though the basal tillite unit is 1982 to 1990 and rejoined the company after earning a common to both. MMath (Computer Science) degree from the University Further north, the quality of the outcrops becomes very poor where they form low hills of a deflation surface caused by extensive weathering partly by

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 associated sabkha conditions. The direction of ice is an Honorary Lecturer at Aberdeen University, movement has been interpreted by some workers to spending part of each year since 1990 working on the be from southwest to northeast based mainly on desert of south-eastern Arabia and maintaining his foreset directions in the sands overlying the striated interest in the Oman Mountains. He is a member of the pavement; however, it is stepped down erosionally AAPG and Geological Society of London, Edinburgh, to the southwest, which implies ice flow from Aberdeen and The Netherlands. northeast to southwest. Brian P.J. Williams obtained a Juma D. Al-Belushi is currently BSc (Honors) in Geology and a a final year PhD student at the PhD in Sedimentology from the University of Aberdeen working on University of Wales. From 1964 the HC-producing glaciogenic to 1970 he worked as a Postdoctoral sediments (Permo-Carboniferous) Research Fellow at the University of Oman and Australia. He has of Ottawa, Research Fellow at the been employed by Petroleum University of Wales, and a Senior Development Oman since 1992 as Hydrogeologist for the Water an Exploration Geologist. Juma is Resources board in Reading. From a member of the AAPG and SPE 1970 onwards Brian was a Lecturer, Senior Lecturer and and has participated in many international conferences. Reader in Sedimentology in the Department of Geology, He has a MSc in Petroleum Geology from the University University of Bristol. In 1988, Brian became Professor of Aberdeen and is scheduled to graduate with a PhD in in Petroleum Geology at the University of Aberdeen where October, 1996. he is the director of the MSc course in Petroleum Geology. His current research interests include hydrocarbon K.W. Glennie received his BSc and reservoirs in Australia, Canada, Texas and the North Sea; MSc degrees from Edinburgh non-marine clastic sedimentology and basin analysis. University. He then spent the next Brian is a member of the Institute of Petroleum, SPE, 32 years as an Exploration PESGB, AAPG, Society for Sedimentary Geology, Geologist with Shell, working in International Association of Sedimentologists and the New Zealand, Canada, Nepal, Geological Society of London. Oman, Iran and Turkey before spending 15 years on the North Sea geology based in London. He retired from Shell in 1987, and he

FMI as a Tool to Optimize Horizontal Well Completions in Waterflood Carbonate Reservoirs

Al-Busaidi, Rashid S. Petroleum Development Oman

The intensive horizontal drilling campaign at pyrite nodules have been identified. Based on these Petroleum Development Oman has had significant results it is concluded that the presence of fractures economical and technical merits. However, is the the primary cause of early water breakthrough. drawbacks were also apparent particularly with In general, wells where the FMI results were used to respect to early and unexpected water breakthrough select the completion intervals (i.e. avoidance of i.e. not related to the bottom water sweep. This perforating of fractured intervals) showed better phenomenon was noticed in two of the carbonate production performance (i.e. lower watercut). High fields of north Oman (Yibal and Lekhwair). To study density fractured zones, in most cases, indicate the this behavior, FMI logs were run in over 10 horizontal existence of fault(s). Some of these faults are below wells in each field. The objectives were to identify the seismic resolution. fracture systems and their lateral trends, occurence of fault related fractures, facies variations and Rashid S. Al-Busaidi is currently sedimentary features. a Production Geologist with The FMI logs indicated the presence of open and Petroleum Development Oman. He cemented high density fractured zones with most of has 6 years of petroleum the fractures oriented in line with the patterns of engineering and drilling experience. faults as interpreted from 3-D seismic. The FMI Rashid received a BSc in Geology image pointed out a penetration of different from Yarmouk University. electrofacies boundaries which are due to sedimentological variations; moreover, vugs and

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Waddah T. Al-Hanai holds a BSc Optimization of Horizontal Wells in a in Chemistry from the University of Complex Carbonate Reservoir, Beirut, Lebanon, a MSc in Physics Onshore Abu Dhabi from Marquette University, USA and a PhD in Fluid Mechanics in Al-Deeb, Maged A.A.*, Waddah T. Al-Hanai Porous Media from the University Abu Dhabi Company for Onshore Oil Operations (ADCO) of Bordeaux, France. His work and Mahmood Akbar experiences include reservoir Schlumberger, UAE engineering which involves supervising simulation and study The development of highly heterogeneous carbonate works. His fields of interest are mathematical formulation reservoirs has been a big challenge to the oil industry of the physics of two-phase flow and development of upscaling for years. The problem is further aggravated when methods. it comes to the complex reservoirs of a high API oil. Extensive efforts and planning are required to extract Mahmood Akbar is a Division the oil from these reservoirs. This paper discusses Geologist with Schlumberger Middle how to boost the oil production from a highly East. He joined Schlumberger in heterogeneous reservoir, onshore Abu Dhabi. The 1985 as District Geologist for formation is mainly comprised of dolomitic Pakistan until 1992 when he limestone with matrix and rock porosity distributed became Division Geologist for the randomly in the form of patches of varying sizes. Oman-Pakistan Division. Since The porous areas of the formation are separated from 1993, Mahmood has been with each other either partially or completely by dense Schlumberger Dubai. He received nodules or cemented areas of limestone. BSc and MSc degrees in Applied Due to the erratic production behaviour of the Geology in 1983 and 1985 respectively, from the vertical wells, some horizontal wells were planned. University of Punjab. The first two horizontal wells in this reservoir could not achieve better production rates than the vertical The Challenge of Interpreting wells. Therefore, a strategy was formulated to 3-D Seismic Over Shaybah Field investigate the reason why the first two horizontal wells did not perform as expected and moreover, to Al-Faraj, Mohammed N.*, Michael D. Ferguson design the trajectories for future horizontal wells. and Ibrahim A. Al-Ghamdi The downhole imagery, well logs and cores from five Saudi Aramco vertical and two horizontal wells revealed the occurrence of fractures in the Simsima carbonates. The giant Shaybah Field, situated in the northeast The highest fracture density was observed in one of region of the Rub Al-Khali desert in Saudi Arabia, the vertical wells drilled in the crestal area of the field. was discovered in 1968. 2-D seismic and well control In contrast, the first two horizontal wells, also placed were used at the time to delineate the field. With in the crestal region, intersected just a few small development of the field now likely to commence in fractures. the near future, an ambitious 3-D seismic program The fracture analysis suggested a dominance of was launched in 1993 in order to synthesize a detailed northeast-southwest striking longitudinal fractures picture of the geology encompassing the hydro- in the anticline. Therefore, guided with the findings carbon accumulation in the field. of the study, the locations and kick-off directions and Over 120 million seismic traces, covering an area of trajectories for subsequent horizontal wells were about 1,100 square kilometers were acquired in a accordingly planned. The first horizontal well drilled rough terrain consisting in its entirety of flat sabkhas in light of the study results, produced ten times more and high sand dunes. The mountainous sand dunes, than the previously drilled vertical and horizontal reaching as high as 200 meters at times, posed a wells. severe static problem; up to 180 milliseconds of time corrections were often applied to the seismic traces Maged A.A. Al-Deeb is a Lead in order to resolve sand-related static effects. Reservoir Geologist with ADCO. In addition to complex topography, the 3-D structural He has 20 years of industry interpretation had to overcome sub-surface problems experience, 6 with Gulf of Suez related to lithofacies and biofacies distributions. Petroleum Company, Egypt. His First, the lithology of the gas-capped oil reservoir interests include carbonate reservoir consists predominantly of carbonates, overlain by characterization, fracture reservoir, denser, compacted shale. The decrease in density at core analysis and data integration. the reservoir level relative to that of the sealing shale For the past 7 years, he has been creates an imaging problem: namely, a weak involved in horizontal drilling projects. reflection at the top of the reservoir. Second, and He has a BSc in Geology from Al Azhar University, Cairo, Egypt.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 probably of utmost seriousness, is the mapping of 1981, Michael joined Aramco an undulating reservoir surface resulting from the Overseas Company as an presence of carbonate rudist buildups, which also Exploration Geophysicist based in results in the top of the reservoir not conforming to Croydon. Since 1982, he has been its base. with Saudi Aramco as an Exploration Geophysicist in Mohammed N. Al-Faraj received Interpretation in Dhahran. His a BSc in Electrical Engineering interests include 3-D seismic from the University of Wisconsin- workstation interpretation, seismic Milwaukee in 1983, and MSc and data processing and reservoir PhD in Geophysics from The characterization. Colorado School of Mines in 1987 and 1993, respectively. From 1983 Ibrahim A. Al-Ghamdi is an to 1984 Mohammed worked as a Exploration Geologist working Project Engineer for SCECO in with the Exploration Organization Saudi Arabia. Since 1984, he has in Saudi Aramco since 1985. He been with Saudi Aramco. His interests include seismic has worked in area exploration, data processing, reservoir characterization, and working reservoir geology and wellsite. on multi-disciplinary teams. He is a member of the SEG Ibrahim also worked in special and EAEG. projects including reservoir modeling with EPRCO in 1989. Michael D. Ferguson received his BA in Geology from Most of his work concentrated on the University of South Florida in 1977. From 1977 to carbonates of the Jurassic and the Cretaceous of Arabia. 1981 he worked as a Geophysical Engineer with He is interested in carbonates, artificial intelligence, Geophysical Services International in Saudi Arabia. In sequence stratigraphy, geostatistics and field geology.

Deterministic Versus Stochastic Approaches in Reservoir Characterization: A Review

Al-Fares, Mohammad H.* and Panos G. Kelamis Saudi Aramco

Two distinct approaches in reservoir characterization Mohammad H. Al-Fares has been are identified. The first approach employs with Saudi Aramco as Research "deterministic" methods which rely on theoretical Geophysicist since 1984. He relationships between the reservoir model obtained his PhD from the parameters and the data observed. A deterministic University of Southern California model in this approach is estimated by simulating in 1992. Mohammad is a member its response so that it matches the measured data. of the SEG and EAEG. He is The simulation part requires a physical relation to professionally interested in Inverse be known so that a synthetic response for a given Problem Theory and Reservoir model can be generated. Mapping acoustic Geophysics. He holds a US Patent impedances from post-stack seismic amplitude data for his innovative seismic inversion technique. belongs to this category. This approach, however, can be limited by our understanding of the Panos G. Kelamis holds a BSc underlying physics relating the reservoir model (Honors) in Physics from the parameters to the data observed. The second University of Athens, Greece (1977), approach employs "stochastic" methods, which MSc and DIC in Geophysics from capitalize on the statistical properties of the model/ Imperial College, London and a PhD data directly rather than the theoretical relationship in Geophysics from the University of between the two. They can generate multiple Alberta, Canada (1982). He worked equiprobable realizations of a single parameter along with Western Geophysical in with its uncertainty distribution. Kriging techniques Houston and Dome Petroleum in belong to this category in which a variogram is used Calgary. Panos joined the to quantify spatial correlation and variability of a Geophysical R&D Division of Saudi Aramco in 1985 property as a function of distance and direction. The where he is currently Head of Field Development. He is use of the two approaches of deterministic and a member of the SEG, EAEG and is the SEG stochastic modeling is evaluated with geological, Representative for Africa and the Middle East. geophysical and engineering data and a proposed third approach is investigated by combining the two.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Hydrocarbon Potential Early Evaluation of Potential Hydrocarbon of Iraq Zones in Abu Dhabi Wells by Using Mud Log Data and Gas Ratios Al-Gailani, Mohammad B. GeoDesign Limited, UK Al-Habshi, Abdulrahman S.* Abu Dhabi National Oil Company (ADNOC) Iraq is one of the most exciting oil exploration Michael Redmond* and Philip M. Soar opportunities in the Middle East. Hydrocarbon Gearhart Middle East, UAE reserves are enormous, estimated at around 150-200 billion barrels. The remaining potential is at least as Mud Logs provide total hydrocarbon and large with vast areas of around 150,000 square chromatographic analysis of light hydrocarbons kilometers still waiting to be explored. (Methane to Pentane, C-1 to C-5) released during the There are over 526 known structures delineated and drilling process, measured at the header tank. The only 125 (24%) are known to have been drilled. Out primary requirement is to obtain relative of the 125 drilled structures over 90 are proven field measurements of the gas content of the mud discoveries but only 30 fields have been partially returning from the well. developed. Most of the current developed reservoirs A number of Industry Standard Gas ratios of the light lie in the Tertiary, Upper and Middle Cretaceous. hydrocarbons produced were calculated and New discoveries have been made in the Lower integrated with other relevant parameters such as Cretaceous (Yamama), Jurassic (Najmah and wireline logs, drilling and geological data to locate Sargelu), Triassic (Butmah and Kurra Chine), zones of interest which require further evaluation Permian (Chia Zairi), Carboniferous (Ga'ara), and production testing to determine hydrocarbon Silurian (Akkas) and Ordovician (Khabour) fluids and reservoir boundaries during the drilling reservoirs. There are 47 known reservoirs, ranging of the wells. from Ordovician to Miocene. The most common Previously, zones of interest were analyzed on a reservoir is the Zubair Sandstone which is present point-by-point basis, if at all. Recent advances in in over 27 fields. The majority of the fields consist of computerized acquisition and interpretation of gas stacked reservoirs reaching up to ten pay zones in data has improved the quality of data available so the giant Majnoon field where only the Lower that it is now possible to apply these calculations over Cretaceous has been reached. Deeper prospects are complete intervals, or the well, in near real-time. still awaiting drilling and testing. Over 30 to 40% of In this paper, several examples are shown from Abu proven Iraqi oil reserves lie within a few thousand Dhabi Cretaceous, Jurassic and Upper Permian feet. More than 60% of the remaining discovered reservoir sections to demonstrate successful reserves lie within 10,000 feet. The finding cost of delineation of porosity and fluid content by oil is probably the lowest in the world. The current application of qualitative and semi-quantitative gas cost is estimated at around 50 cents per barrel. The ratios. Further examples are shown from previously drilling success rate is the highest in the world and drilled wells where this technique could aid future varies between 1 in 2 in the Mesopotamian basin and successful evaluation of wells during drilling. up to 1 in 4 in the western and northwestern areas. Abdulrahman S. Al-Habshi is Mohammad B. Al-Gailani is currently Supervisor of OPCOS currently Managing Director of Areas Geology with Abu Dhabi GeoDesign Limited, a consultancy National Oil Company (ADNOC), office based in London specializing Abu Dhabi, UAE. He has 23 years in databases of the Middle East. He of experience in geology of which six graduated from Baghdad and a half years were with the University in 1972 with a BSc in French company BRGM, Jeddah, Geology and worked briefly for the Saudi Arabia, four and a half years Iraqi National Oil Company in with the Petroleum Department, Baghdad. He won a scholarship in Abu Dhabi, UAE and 12 years with ADNOC, Abu Dhabi. 1973 for Post-Graduate studies in Petroleum Geology Abdulrahman is a member of the SEE and SPE societies. where he obtained his MSc in 1974 from the University He obtained his BSc in Geology from Baghdad University of Aberdeen and then a PhD and DIC in January 1979 in 1971. from Imperial College, London. Mohammad worked as an independent Consultant in the Middle East and the Michael Redmond is General Manager of Gearhart Parana Basin in South America. He has published several Middle East Ltd. in Abu Dhabi. He has 15 years papers on diagenesis and reservoir characteristics at experience in the oil industry in northwest Europe and unconformities. He has been an active member of the the Middle East including managerial positions in the AAPG since 1973 and the Petroleum Exploration Society geological and engineering service companies in the of Great Britain. Middle East for the past 10 years. He is a Fellow of the

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Geological Society of London, and Philip M. Soar is the Operations a member of the AAPG, SPE, SEE, Manager with Gearhart Middle IMWDS, and holds a BSc in East Ltd., Abu Dhabi. He has 16 Geology from Imperial College, years experience in the oil industry University of London. in northwest Europe, Australia, North America and North Africa, and has worked on exploration and development drilling projects in the Middle East for the past 9 years. He is a member of the SPE, SEE and IMWDS, and holds a BSc in Geology from the University College of South Wales, Cardiff.

The Occurence of Devonian Sediments in the Eastern Ghawar Area, and their Exploratory and Stratigraphic Implications

Al-Hajri, Sa'id A.*, Lawrence E., Wender, John Filatoff and A. Kent Norton Saudi Aramco

Historically, strata of Latest Devonian age Lawrence E. Wender is a (Famennian) have never been identified in the Geological Consultant with Saudi Kingdom of Saudi Arabia. However, recent deep gas Aramco in Dhahran. He was exploratory drilling at the Harmaliyah structure, previously with Mobil Oil located east of Ghawar oil field has proved for the Corporation and has 17 years of oil first time the existence of strata of this age. This new industry experience. He is phase of exploratory drilling activity in the Eastern currently Team Leader of the Ghawar Area is focused on the early Middle Ghawar Pre-Khuff Gas Project. Devonian Jauf Formation. The Devonian is missing Lawrence holds a MSc in Geology on the crest of Ghawar as a result of uplift and erosion from the University of Utah. associated with the Hercynian Orogeny of Late Carboniferous age. Drilling on the eastern flanks of John Filatoff is a Palynologist Ghawar, as well as low relief structures such as with Saudi Aramco's Geological Harmaliyah, however, has penetrated a fully R&D Division where his activities, preserved Devonian section. since joining in 1992, have focused Based on palynological evidence and the recovery mainly on Tertiary Red Sea and of palynomorphs belonging to the Retispora Paleozoic deep-gas exploration. lepidophyta zone, Late Famennian age is assigned to John has some 25 years of oil- the upper part of the Jubah Formation. Furthermore, industry experience, primarily in high resolution biostratigraphic correlation with the Australia, but also in Iran and standard zonation of south-western Europe indicates Venezuela. He holds BSc and PhD that part of this section belongs to the LE biozone of degrees in Geology from the Universities of Queensland Streel et al. (1987), and the pusilites-lepidophyta and Western Australia, respectively. He is a member of biozone of Richardson and McGregor (1986). The the Dhahran Geological Society, Geological Society of existence of this previously unrecognized section Australia and the Petroleum Exploration Society of further validates the flank play concept and confirms Australia, as well as a number of specialist palynological that Devonian strata are preserved on the flanks of societies, viz. AASP, CIMP and PPAA. high-relief Hercynian structures such as Ghawar. A. Kent Norton is currently an Sa'id A. Al-Hajri is a Biostratigrapher Explorationist for Saudi Aramco's with Saudi Aramco. He holds a BSc in Area Exploration Department Geology from King Fahd University of where he has worked since 1991. He Petroleum and Minerals and MSc in previously worked for Saudi Geosciences from Penn State Aramco's Geophysical and University. In 1992, he received the Geological Departments from 1979 "Highest Technical Contribution to 1985. Kent received a BSc in Award" from Saudi Aramco. Sa'id is Geology from the University of a member of CIMP, AASP, BMS and California, Davis in 1979 and a DGS, and has published several papers MSc in Geology from Northern Arizona University in on geological and palynological subjects. 1990. He is a member of the AAPG and the DGS.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Following his PhD, he was Geological Intepretation of the appointed Visiting Lecturer in Shuttle Imaging Radar SIR-C/X-SAR Data Princeton University for one year. of Saudi Arabia Since then, he joined the academic ranks at KFUPM. Abdallah's Al-Hinai, Khattab G.*, Abdallah E. Dabbagh, primary activity is in the Weston C. Gardner and Muhammad Asif Khan management of research, but he is King Fahd University of Petroleum and Minerals, strongly interested in the transfer, Saudi Arabia application and adaptation of modern technology with specific The Space Shuttle Endeavour, carrying Shuttle emphasis on environmental applications of remote sensing Imaging Radar (SIR-C/X-SAR), imaged selected and utilization of radar imagery. He has received several parts of the Earth during the two missions in April scientific awards including the King Faisal medal in 1985. and October, 1994. The SIR instrument acquired He was on the Board of Directors of Saudi Aramco from remote sensing data in L, C, and X bands. The main 1989 to 1996. He was appointed to three National objective of the experiment was to assess the utility Committees, and has served as a representative of Saudi of radar imagery for multiple mapping and Arabia at numerous international energy and environmental applications. The Research Institute, environmental conferences and panels. King Fahd University of Petroleum and Minerals, participated in the NASA Science Plan to evaluate Weston C. Gardner is a Senior the Shuttle Imaging Radar data for paleo-drainage Research Scientist in the Division and geologic mapping. of Geology and Minerals at the The geologic interpretation of the L-band image Research Institute of KFUPM. strips over the Arabian Peninsula has revealed faults, Most of his professional career was folds, joints, basalt flows (harrats) and stream with Mobil Oil during some 38 drainage patterns which are not clearly visible on years of employment as a Petroleum other remote sensing images (Landsat and SPOT) Explorationist and Research and are not shown on existing geologic maps. By Geologist. In 1971 he received his virtue of its shadowing and shallow sand penetration PhD from Northwestern capability and sensitivity to terrain textural factors, University, USA. He has long been involved in the the radar images complement and enhance other geological interpretation of airphoto and space images. He remote sensing data to provide a new and unique has taught courses in both Remote Sensing and Petroleum view of the Earth's surface. Geology at Trisakti University in Jakarta, Sultan Qaboos University in Oman and KFUPM in Dhahran. He is Khattab G. Al-Hinai is the currently completing a geological interpretation of some Manager of the Remote Sensing 50,000 kilometers of SIR-C radar strips of the Arabian Center, Acting Manager for the Peninsula, recorded in April and October 1994 from the Division of Geology and Minerals NASA space shuttle Endeavor. at the Research Institute and an Associate Professor in the Earth Muhammad Asif Khan is a Science Department of the King Research Specialist in the Remote Fahd University of Petroleum and Sensing Center, Geology and Minerals, Dhahran, Saudi Arabia. Minerals Division. He completed Khattab received a PhD in Remote his BSc and MSc from Punjab Sensing-Geology from Imperial College in 1988 and a MSc University, Pakistan in 1969 and and BSc in Geology and Engineering Geology, 1971, respectively. He obtained respectively, from the American University of Beirut. He another MSc degree in Remote joined the Research Institute in 1980 as a member of the Sensing and Digital Image Division of Geology and Minerals. He has been involved Processing from University of with several funded and in-house projects pertaining to Tennessee, USA in 1981. At KFUPM, he has been sand dynamics, sand control, engineering geology and associated with the establishment of the Remote Sensing remote sensing. Khattab participated in the development Center and has contributed to numerous client funded of laboratories, manpower and research programs in the research projects requiring the utilization of remote sensing division. He is the author of numerous research papers data. He participated in several international programs and has participated in writing and editing many technical to evaluate the applications potential of future generations reports for the Research Institute. of remote sensors (SIR-C/X-SAR, JERS-1, and ADEOS) for earth resources mapping and environmental Abdallah E. Dabbagh is the Director of the Research monitoring. He is the author of numerous research papers Institute, KFUPM. He completed his BSc in Geology in and technical reports. His research interests include remote 1968 from the American University of Beirut and PhD in sensing applications, digital image processing and Geology in 1975 from the University of North Carolina. geographic information systems.

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Al-Husseini, Moujahed I.* Gulf PetroLink, Bahrain Jean Letouzey* and Marie-Christine Cacas* Institut Français du Pétrole, France

The Precambrian Basement of the Arabian Plate Jean Letouzey has been with the consists of a regional system of horsts and grabens Institut Français du Pétrole since which initially formed during the Infracambrian. 1971. He is Deputy Manager of the The horsts are mostly north-south trending basement Geology and Geochemistry blocks while the grabens are filled by Infracambrian Department. He received his MSc evaporites. The major oil fields in the graben regions in Geology and PhD in Geophysics are salt domes, whereas the fields which correspond from the University of Paris in 1969 to the horst blocks are basement-controlled. The and he graduated in Geology and latter group of fields are generally truncated by Geophysics from Ecole Nationale northwest-southeast or northeast-southwest Supérieure des Pétroles et Moteurs trending faults. in 1971. Jean is a member of the AFTP and AAPG and is The structural development of the Gulf fields particularly interested in basin studies and tectonics. occurred during periods when important regional stresses were applied by extended large-scale tectonic Marie-Christine Cacas joined the episodes. These periods are associated with four Institut Français du Pétrole in 1990 major tectonic events: (1) Infracambrian Intra- and is presently in charge of continental Extension; (2) Late Paleozoic Hercynian reservoir fracturation modeling. Orogeny; (3) Triassic Extension associated with the She graduated from Ecole Nationale Zagros Rift System; and (4) Late Cretaceous to Supérieure d'Hydrolique de Present Zagros Orogeny. Grenoble in 1985 and received her Detailed fault and fracture models of reservoirs in PhD from Ecole Nationale the Gulf Region are developed by combining: (1) Supérieure des Mines de Paris in orientation and structural growth history of the fields 1989. She is particularly interested relative to the regional paleo- and current stress in rock fracturation and reservoir modeling. fields; (2) fault interpretations from 2-D and 3-D seismic; (3) micro-fracture analysis from well logs and cores; (4) field studies of fractured outcrops; and (5) analogue modeling. Geo'94 Moujahed I. Al-Husseini founded Gulf PetroLink in 1993, a Middle East Petroleum Geosciences consultancy aimed at transferring technology to the Middle East Edited by Moujahed I. Al-Husseini petroleum industry. Moujahed was previously Exploration Manager 78 papers presented at Geo'94 for Saudi Aramco. He received his BSc in Engineering Science from Conference, Bahrain King Fahd University of Petroleum and Minerals (1971), MSc in April 25-27, 1994. Operations Research from Stanford University (1972), 2 Volumes, 939 pages, PhD in Earth Sciences from Brown University (1975) and Program for Management Development from Harvard color throughout, hardbound University (1987). Moujahed is a member of the AAPG, SEG, EAEG and SPE. He is the Editor-in-Chief of GeoArabia and has published over 20 geoscience papers. Available: AAPG Bookstore P.O. Box 979, Geo'94 Available: Tulsa, OK 74101-0979 Gulf PetroLink USA P.O. Box 20393, Manama, Bahrain Fax: (918) 560 2652 Tel: (973) 214 881 Tel: (918) 584 2555 Fax: (973) 214 475

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 The Development of Improved Reservoir The Role of Hydrogeology Facies Beneath Dolomitizing Tidal Channels/ in Petroleum Development Oman Embayments: A Useful Tool for Reservoir Prediction in the Khuff Formation Al-Lamki, Mohamed S.S.*, Arafa M.A. Al-Harthy and Jos M.J. Terken Al-Jallal, Ibrahim A. Petroleum Development Oman (PDO) Saudi Aramco Hydrogeology has been studied in PDO since the early Recent studies of the Khuff Formation in the Ghawar eighties. Initally, attention was focused on issues related field of Saudi Arabia indicate that most of the to water supply and disposal. Increasingly, however, reservoir facies are diagenetically controlled. The hydrogeology has provided an insight into the effect of primary porosity of grainstones in the Khuff salinity on oil saturation measurements and sub-surface Formation has been affected by dolomitization, temperature variations due to hydrodynamic flow. In cementation or leaching. One of the most interesting south Oman, water is flowing in three main levels: the observations during these studies is that the Cenozoic carbonates of the Umm Er Radhuma Formation dolomitization process preserved, and sometimes and the clastics of the Paleozoic Haushi and Haima enhanced, the primary porosity of the common aquifers. The aquifer flow pattern is from the Qara subtidally deposited carbonate sands. The intensity Mountains in the south to the Umm as Samim sabkha in of dolomitization increases with proximity to the the north. Although impermeable strata are expected to overlying bioclastic wackestone - packstone facies isolate the different aquifer systems, salinity profiles and interpreted to be of tidal channels/embayment radiocarbon age-dating indicate that locally faults may deposits. These channels/embayments acted as breach the strata, thus allowing flow to take place across continuous conduits for Mg-rich fluids sourced formations. As a result, aquifer water has become less mainly by sea water, which were concentrated inland saline and hence more resistive, masking the presence of by evaporation. These fluids percolated downward the overlying oil on electric logs. On the basis of salinity and continuously dolomitized the rock beneath thus data, water resistivities (Rw) have been mapped and the inhibiting the precipitation of anhydrite cements. use of an Rw database has resulted in more accurate This process preserved the original primary measurements of oil saturations. In the Marmul northwest interparticle porosity and sometimes enhanced it field, for example, these corrections led to significant with the addition of intercrysalline porosity between reserve additions as hydrocarbon saturations were crystals within grains. This process resulted in high increased from 30 to 70%. Present-day hydrodynamic porosity and permeability at these localities. cells are also clearly reflected by sub-surface temperature In formations similar to the Khuff where shallowing- variations. Integration of the modeling results with other upward cycles occur, this relationship provides a geological and paleoclimatic information has allowed the potentially useful tool to assist reservoir geologists reconstruction of the thermal history of the South Oman in their search for new reservoirs and additional Salt Basin and the prediction of oil quality for prospect reserves. evaluation.

Ibrahim A. Al-Jallal is currently Mohamed S.S. Al-Lamki is Chief Geologist in the Geological currently working as Hydrogeolgist R&D, Exploration in Saudi with the Regional Studies Team of Aramco. He received his BSc from PDO. He holds a BSc from the University of King Saud, Straffordshire University and a MSc Riyadh in 1973, a MSc from in Hydrogeology from University Western Michigan University, College London. Mohamed has USA in 1979, and PhD in worked in seismic processing, Petroleum Geology from Imperial seismic interpretation and College, University of London in operations geology. 1990. His work experience involved well site operation, reservoir development, prediction and layering and Arafa M.A. Al-Harthy is depositional modeling. Ibrahim is the author of company currently working as Production reports on the Arab D and Khuff formations. His PhD Geologist with PDO. He is dissertation was on the Khuff Formation's deposition, involved with geological and diagenesis and reservoir prediction in Ghawar field, Saudi operational aspects in petroleum Arabia. He recently extended this study regionally to engineering environment. Arafa is include all of the Gulf States. Ibrahim is a member of the also working on a study to Editorial Advisory Board of GeoArabia. formulate Qarn Alam Area Water Management Plan.

Jos M.J. Terken (see Loosveld et al., p. 51)

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Reservoir Characterization of the Synthetic Time-Velocity Ahmadi "Ab Zone", Pair Curves Bahrain Field Al-Nahwi, Hashim M.*, Adil A. Al-Khelaiwi Al-Madani, Adel A. and Yahya M. Al-Ansari* James A. Richard, Lloyd W. Long Bahrain National Oil Company (BANOCO) and Arnold M. Rivett Saudi Aramco This study reveals that production of the Middle Saudi Aramco's processing database contains Cretaceous Ahmadi (Ab Zone) in Bahrain field is stacking time-velocity curves for thousands of lines controlled by facies distribution. The Ahmadi (Ab in the Kingdom. In central and eastern Saudi Arabia Zone) sediments are comprised of a decimeter to there are lines spaced 10 kilometers apart or closer meter bedded succession of shale and argillaceous throughout current prospects. The velocity control and clean limestone. Lithofacies identified include, already developed for these neighboring lines can argillaceous bioclastic wackestone/packstone, be used to make processing easier. bioclastic wackestone/packstone and bioclastic A methodology was developed using time slice packstone. The bioclastic lithofacies contain the best velocity mapping, which allows production of time- reservoir characteristics with porosity and velocity data volumes for areas of interest. When permeability ranging up to 22.3% and 3.0 mD new seismic lines are programmed, their survey respectively. coordinates are used to produce synthetic time- The methodology for predicting the bioclastic velocity pair data sets at appropriate locations. packstone facies from uncored wells requires an Newly shot seismic lines are stacked with these integration of wireline logs (both deterministic and synthetic time-velocity curves. probabilistic techniques) and core data. Saudi Aramco's seismic data processing division has Variations in production rates of Ahmadi (Ab Zone) found that using these synthetic time-velocity curves may be attributed to one or more of the following: reduces the effort needed for velocity analysis of infill differences in permeability associated textural seismic lines. This process is helping to produce a variations in the micritic matrix and the degree of better product with less effort. diagenetic leaching of macrofossils, variation in the degree of hydrothermal leaching associated with the Hashim M. Al-Nahwi has worked proximity of faults, proximity to faults and gas for Saudi Aramco for 18 years in injectors that may be providing pressure support exploration. He holds a BSc in through the Ahmadi (Ab Zone). Geophysics from the University of New Mexico. Hashim worked for Adel A. Al-Madani received his several years in the Depthing/ BSc in Geology from Ain Shams Mapping Unit of the Geophysical University in 1976. He joined Technology Division and has BANOCO in April, 1977 as a become concerned with the Trainee Geologist and from 1979 to production and uses of velocity 1990 he worked as Explorationist maps which are used in the depthing in onshore and offshore areas. In of 2-D seismic data. 1991 Adel was assigned to work in the Bahrain field and he is currently Adil A. Al-Khelaiwi, Chief working as Head Development Geophysicist of Geophysical Geologist. Technology Division, Saudi Aramco, has a BSc from the Yahya M. Al-Ansari is a graduate University of Liverpool. He has of Geology from Qatar University held several supervisory positions (1993). He is currently working as in the Geophysical Department. a Development Geologist with These assignments have enriched Bahrain National Oil Company his experience in the seismic method and is involved in reservoir from acquisition to reservoir characterization and formation characterization. Adil is a member evaluation research. of the SEG and DGS.

Arnold M. Rivett (see Rivett et al., p. 184)

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 James A. Richard is currently a Lloyd W. Long is currently a Geophysicist with Saudi Aramco in Geophysical Systems Analyst with the Depthing/Mapping Unit of the Saudi Aramco. He has 17 years Geophysical Technology Division. experience as a systems analyst, 13 He has 18 years of exploration of which are in the petroleum experience: 13 years working in industry. Lloyd also has 7 years North America, and 5 in Saudi field experience working on seismic Arabia. He holds a BSc in Geology crews in North America and Saudi from Colorado State University and Arabia. He holds a BSc degree in is a member of the SEG, RMAG, Geology and Physics from Eastern AAPG, and DGS. Washington University and a MBA from Washington State University.

Completion Optimization of Horizontal Wells New Insights into Regional Correlation and (Effect of Length, Diameter, Well Position Sedimentology, Arab Formation and Perforation Scenario) (Upper Jurassic), Offshore Abu Dhabi

Al-Qahtani, Abdullah M. Al-Silwadi, Mohammad S.*, ADNOC Saudi Aramco Anthony Kirkham, ADCO Michael D. Simmons, University of Aberdeen Due to their high production performance horizontal and Bryan N. Twombley, Ditton Petrographic wells have become an established method for recovering oil and gas. A major uncertainty however, (See paper by Al-Silwadi et al., p. 6-27) is whether the productivity of these wells will increase with increasing horizontal length. In horizontal wells drilled in high permeability reservoirs where a small The Use of Geologic Models in Building the pressure draw-down is needed to initiate flow in the Stratigraphic Framework and Influencing horizontal section, the frictional losses in the horizontal Attribute Interpolation in the Hawtah Trend section may be comparable to the pressure draw-down. As a result, the deliverability of the well is restricted. Al-Sulami, Khalil H.*, Christian J. Heine In this study, the in-flow and out-flow performances and James R. Wilkins of the horizontal well are combined to predict its Saudi Aramco overall performance. That is accomplished by using a computer program that couples a theoretical solution The two important steps in the 3-D geologic of the productivity index to a multi-phase flow model modeling process are: (1) building the stratigraphic in the horizontal section of the well. Different well framework; and (2) attribute interpolation. completion scenarios and lengths were examined. The Improvements in hardware and software have preliminary results of this study are: (1) in a 4-1/2 inch significantly increased our ability to quality control casing horizontal section, the increase of well length both of these steps through visualization. In central and perforation percentage does not yield a substantial Arabia, the stratigraphic framework is built by increase in production; (2) in a well drilled in a high adding re-constructed layer isopach maps up from permeability zone, the frictional losses could be of the a key structure map, as indicated by the geologic same magnitude of the pressure draw-down across the model. This ensures the correct geometry of the perforation rendering the end of the well unproductive; geologic layers is preserved in building the geologic (3) different wells with different completion scenarios framework. The angular unconformity at the Base may perform similarly implying that the completion Khuff is represented by a truncation surface (grid) can be optimized to get the best performance; and (4) which removes the cells or portion of cells above the 2,000 feet of horizontal section length appears to be an truncation surface while maintaining the proper optimum length. depositional geometry for attribute interpolation. These surfaces are built using 2-D mapping software, Abdullah M. Al-Qahtani is a any irregularities in the stratigraphic framework can Production Engineer with Saudi be detected using logical operations. Any corrections Aramco where he has worked in can then be made to the surfaces prior to moving different departments. He has into the 3-D modeling software. conducted his MSc research on the In addition to the stratigraphic framework, sequence evaluation of horizontal wells. specific sand distribution templates were used to Abdullah obtained his BSc and MSc influence the distribution of porosity. Net to gross from King Fahd University of surfaces were converted to porosity surfaces in the Petroleum and Minerals, Saudi 2-D mapping software package using balanced Arabia. translation curves. These porosity templates are now (cont. p. 110)

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 (cont. from p. 109) used to "condition" the porosity interpolation. This detector configurations. The comparison of the can be done within the 3-D modeling software or pseudo VSP with the real VSP and well data outside using a geostatistical routine that accepts improves the integration of surface seismics and well conditioning templates. information. Due to acquisition difference between the real VSP and the surface data, the pseudo VSP Khalil H. Al-Sulami holds a MSc has a lower frequency band than the real VSP. After in Geology from King Fahd proper pre-processing (including a thorough study University of Petroleum and of the sources and detectors used in both situations), Minerals (KFUPM). He has been the pseudo VSP may have a better signal-to-noise with Saudi Aramco for 14 years and ratio. In practical situations both VSPs may enhance has been involved in oil exploration, each other significantly. Now the fundamental seismic interpretation and prospect importance in the pseudo VSP generation technique evaluation for the past 5 years. is that we can walk away from the well with Khalil is currently working on optimally determined matching parameters at the geological modeling. well and extend our geological knowledge in all lateral directions (reservoir characterization). The Christian J. Heine received his absence of tube noise in pseudo VSP data is an added MSc in Geology from the advantage over real VSP data. The presentation of University of Tennessee in 1982 VSP data in one-way time allows a better and a MSc in Petroleum identification of P and S-waves. Using reciprocity, a Engineering from Tulane multi-source pseudo VSP equals a multi-focus University in 1990. Christian was Common Focus Point (CFP) gather. Associate Professor at Tulane University from 1990 to 1991, and Riaz Alá'i received his MSc in worked with Mobil Oil from 1982 Electrical Engineering specializing to 1990. He joined Saudi Aramco in Control Engineering from Delft in 1991. Christian is a member of the AAPG and DGS. University of Technology (DUT) in 1991. He is currently a PhD James R. Wilkins received his BSc candidate at DUT working on a in Geology from the University of PhD research project on the Southern Colorado. He worked as generation of pseudo borehole data a Geologist for Western Geophysical from seismic surface measurements. Company under contract to This project is part of the Aramco between 1981 and 1986. international DELPHI (DELft PHilosophy on Inversion) He is currently working as Consortium at DUT Center for Technical Geoscience Geologist with Saudi Aramco with (CTG), Faculty of Applied Physics, Laboratory of Seismic emphasis on geological computer and Acoustics. He is affiliated with the SEG and EAEG. applications. James' work involves His areas of professional interest include wave theory and 3-D mapping and modeling and reservoir characterization. VSP processing.

C.P.A. Wapenaar received his MSc Pseudo VSP Data Generation: in 1981 and his PhD (cum laude) Field Data Example from the in 1986 from Delft University of Middle East Technology, both in Applied Physics. In 1986 he received the Alá'i, Riaz* and C.P.A. Wapenaar Shell Study Award. From 1987 to Delft University of Technology, The Netherlands 1991 he worked at DUT as a Senior Research Fellow on behalf of the The transformation of surface measurements into Royal Dutch Academy of Sciences pseudo VSP data is a very useful tool in the (KNAW). In that same period he interpretation of seismic data. It adds a depth was Associate Editor for Geophysical Prospecting. From dimension to seismic data and gives insight into the 1987 to 1993 he has been a Consultant for Jason entire wave propagation through the subsurface. Geosystems B.V. and Delft Geophysical B.V. He is In this paper we present the generation of pseudo currently Associate Professor at DUT, where he leads a VSP data from a dataset from the Middle East. One consortium research project on elastic seismic data of the aims is the verification and update of the macro processing (Delphi). His main interests are wave theory sub-surface model, by making use of inconsistencies and seismic processing. He is a member of SEG, EAEG of multi-source and offset pseudo VSPs together with and ASA. the behavior of non-causalities (two-way schemes). Pseudo VSP data is generated for various borehole/

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 3-D Seismic in Transition Areas, A Case History

Ali, Omar S.M., Abu Dhabi Company for Onshore Oil Operations (ADCO) Atef A. Ebed*, Abu Dhabi National Oil Company (ADNOC) Michael Fleming, Western Geophysical, UK and Ismail B. Haggag, Western Geophysical, UAE

Transition zones and tidal belts represent the Omar S.M. Ali received a BSc in toughest prospects for seismic exploration Geology from Cairo University. worldwide. Many prospective hydrocarbon reserves Omar has 30 years experience in crossing these areas between onshore and offshore geophysical prospecting with G.P.C. are still not well defined. Utmost flexibility and Egypt; Sonatrach, Algeria; and versatility of methods and techniques are required ADCO, Abu Dhabi. when the seismic exploration is projected to cross areas with water depth less than 1 meter, small islands, reefs, coastal swamps and beaches. Advances in 3-D seismic acquisition technology and processing methodology have again encouraged activities in these challenging areas. In 1994, ADCO Atef A. Ebed is currently a Senior in collaboration with ADNOC started to acquire one Geophysicist with ADNOC. He has of the largest 3-D shallow marine surveys in the 25 years of experience in seismic world, approximately 2,000 square kilometers, in the exploration, of which 3 years were western area of Abu Dhabi. The survey is being with GPC in Egypt, 12 years as acquired by Western Geophysical. The survey area Seismic Data Analyst with SSC in presents a typical example of the transition zones different processing centers where we have: (1) rapid changes from sand to very worldwide and more than 10 years soft unpredictable sabkha onshore, to a very hard, as Senior Geophysicist with the coral, rocky surface underneath the water; (2) Exploration Division at ADNOC. changes in water depth of about one to two meters Atef received his BSc in Physics and Geology from affected by semi-diurnal tides; (3) large variations in Alexandria University in 1969, Post-Graduate Diploma in sea bottom topography and sediments; (4) the very Geophysics from Alexandria University in 1971 and a PhD high salinity of water; (5) the desire to protect the in Seismic from Bucuresti University in 1978. He is a environment: plant life including Mangrove trees member of the EAGE and SEE. and various species of animal life; and (6) the coastal areas are marked by extensive areas of shallow water Michael Fleming holds a BSc in with some deeper channels, swamps and reefs. Physics from Warwick and a MSc in The objectives of the 3-D sesimic survey are: (1) to Material Physics from Bristol. His detect and define the extent and geometry of subtle work experiences include Processing faults at the reservoir level which might act as fluid Center Manager, Supervisor, Land barriers; and (2) predict and better understand the Technology Group in Western reservoir properties, such as porosity and lithology. Research, Houston, and Resident The 3-D acquisition parameters such as bin size, fold Manager in Saudi Arabia. He is coverage, source parameters and swath geometry currently the Area Geophysicist with were selected in such a way as to achieve the EAME Land, London. following: (1) high resolution seismic data; (2) regular offset distribution within each bin; (3) minimum Ismail B. Haggag received his BSc azimuthal variation; and (4) optimum match in Applied Physics from Ainshams between land, shallow marine and offsore seismic University, Cairo in 1970, MSc in data. 1975 and PhD in Geophysics from This paper involves the planning procedure and Karlsrahe University, Germany. He describes a series of solutions used in 3-D seismic has been working with Western acquisition and processing for such hazardous Geophysical, Abu Dhabi as Area shallow marine areas. Geophysicist since 1985. He started as Acquisition Geophysicist with Western in 1980 and was transferred to the London Processing Centre as Processing Analyst in 1984. Ismail is a member of the SEG, EAEG and the SEE. He is professionally interested in acquisition and processing of shear waves.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Standard 3-D Models Basin Resource Development: to Serve the Industry Forecasting on the Basis of Risk Analysis

Aminzadeh, Fred Anissimov, Leonid A. Unocal, Texas, USA Saratov State University, Russia

This paper gives an update on the results and status The role of risk management in exploration increases of the 3-D SEG/EAEG Modeling (SEM) Project. The in mature hydrocarbon provinces, where numerous project goal has been to design two 3-D models, salt existing fields form the basis for statistical analyses. and overthrust, and simulate realistic 3-D surveys The classification and quantification of basin through numerical calculations. They may be used parameters (earthquakes, booked reserves, for survey design, testing and validating different discoveries, etc.) allows the construction of dynamic processing methods, interpretation of 3-D seismic, models. These models are built on risk analysis and better understanding of wave propagation through on the theory of queues and have been tested in complex media, training and benchmarking several sedimentary basins including the North Sea, computer hardware and software. Indonesia, the Volga-Ural province and West Siberia. So far, about 1,000 terabyte of data has been Analysis of these basins shows that certain statistical generated completing Phase A and Phase B and a relationships exist, which permit the forecasting of portion of the Phase C of the project. "Classic Data undiscovered resources and the evaluation of human Sets" containing subsets of calculations conducted activity on the natural basin parameter distribution. for Phase A and B have been defined. These data Risk management in exploration may be very sets will be made available to the general public. effective for the Middle East basins with their large Plans for additional calculations of about 2 terabyte number of oil and gas fields. are underway. Many groups have already begun using and testing the data sets for various Leonid A. Anissimov is currently applications. These data sets are expected to improve Head of the Hydrogeology and the current 3-D processing methods and help reduce Engineering Geology Department, exploration and production cost. Saratov State University, Russia. Salt and overthrust structures offer two major He has 32 years of petroleum, challenging opportunities in the petroleum industry. geochemistry and environmental The models generated under this project highlight research experience at the the specific complications involved in these types of Volgograd Research Petroleum play, with the capabilities and limitations of the 3-D Institute and Saratov State seismic data in each case. The whole industry and University. Leonid is a member of academic institutions will have access to a common the Ecology and Civil Engineering Academies. He has a data set enabling geoscientists to further fine tune Doctor of Science in Geochemistry and Professorship in their processing and interpretation tools in a Water Problems. consistent manner. These models and their legacies will be with us for many years to come. Targeting Infill Wells in the Fred Aminzadeh is with Unocal's Densely Fractured Geotechnology Group in Sugar Lekhwair Field, Oman Land, Texas and an Adjunct Professor in the Geology/Geo- Arnott, Stuart K.* and John N.M. van Wunnik physics Department of Rice Petroleum Development Oman University. He received his PhD from the University of Southern The oil bearing reservoirs of the Lekhwair field in California in 1979. Fred has done Oman consist of a low-permeability chalky extensive work in seismic modeling, limestone. These have been waterflooded since 1992 reservoir characterization and by a 200 well development project. On the crest, the geophysical signal processing. He serves as Chairman of reservoir is developed by a vertical inverted 9-spot the Society of Exploration Geophysicists' research pattern. On the low relief flanks, horizontal wells committee, and co-chairs the SEG/EAEG 3-D modeling are employed. It soon became apparent that the sub-committee. reservoirs were more faulted and fractured than anticipated and early water breakthrough occurred in many producers (20%). Intensive efforts were successful in improving the mapping of the fault and fracture network and in identifying unswept reserves. Extensive use was made of FMI/S logs in horizontal wells, correlation of production attributes

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 such as water cut, produced water salinity and gross knowledge of directional engineering principles and production rates and production history matching directional engineers become more aware of geological with numerical simulation models. uncertainty. The geological operation for horizontal well To improve future oil recovery further infilling is requires a unique approach, more oriented towards required. However, the above simple evaluation directional engineering aspects. methods are too coarse for reliable well targeting. A This paper considers ZADCO's current standard cost effective method to obtain the required targeting geological practice for horizontal drilling, highlighting refinement is based on horizontal appraisal wells and aspects of both office and site work. The role of well site FMI/S logs in these wells. The resulting data, in geology in development drilling has been revitalized and combination with the "coarse" maps, allow an area enhanced as horizontal wells have become increasingly as large as 1,000 by 500 meters to be mapped complex. sufficiently well to target successful infill vertical wells. The horizontal appraisal well is targeted in Jiro Asada is currently Reservoir the most productive layer and pays for itself. A Geologist with ZADCO. He joined the number of field examples illustrate the success of this petroleum industry with Japan Oil method. Development Company in 1982. Jiro had been involved in horizontal drilling Stuart K. Arnott is currently from the first offshore horizontal well Production Geologist for Petroleum in the region as Operation Geologist in Development Oman, working on ZADCO from 1987 to 1993. He the Lekhwair field. He previously gained a BSc in Geology from Shinshu worked for Shell in Holland and University, Japan in 1982. Britoil in the UK. He has a PhD in Seismology from Durham Walid K. Najia is currently Lead Log University and a BSc in Physics/ Analyst with ZADCO seconded from Geology from the University of Abu Dhabi National Oil Company. He Glasgow. was Lead Operation Geologist with ZADCO from 1988 to 1992. He was John N.M. van Wunnik is involved in planning, supervision and currently Reservoir Engineer with following up of multi-lateral horizontal PDO. He has 14 years of petroleum wells. He has 20 years of various industry experience of which 10 petroleum industry experience in the years were with Shell's Exploration region. He received a BSc in Geology and Production laboratory in The from Punjab University, Pakistan in 1972. He was awarded a Netherlands and 4 years with PDO. MSc in Petroleum and Structural Geology from Punjab He is an SPE member and has University in 1974. published several papers on reservoir engineering subjects. John received Nozomi Fujita is currently Operation his PhD in Physics from the University of Amsterdam. Geologist with ZADCO. His activity is focused on the latest multi-lateral/ multi-layered horizontal drilling. He Aspects of Operation Geology joined the industry with Japan Oil in Horizontal Drilling Development Company in 1985. He received a BSc in Geology from Tokai Asada, Jiro*, Walid K. Najia, Nozomi Fujita University, Japan in 1985. Zakum Development Company (ZADCO), U.A.E. and Philip S. Leighton Topaz Consultants Ltd., Scotland, UK Philip S. Leighton is currently contracted to ARCO QATAR to Horizontal activity in ZADCO's offshore fields of Abu supervise geological operations. He Dhabi started in 1989, and continues to be an integral and was Consulting Geologist with extensive part of ZADCO's drilling program. To date, 70 ZADCO from 1993 to 1995. He horizontal wells including single-lateral multi-layered and gained a BSc in Geology from the multi-lateral multi-layered step profiles have been drilled. University of St. Andrews, Scotland Geological practice in horizontal drilling has become more in 1979 and joined the industry in involved in directional engineering aspects. Geologists 1980. He was awarded a MSc in at site are fully in charge of steering a well, once it has Geology from the University of St. entered a target reservoir. Thus, the integration of geology Andrews in 1985. In 1990 he co-founded TOPAZ and directional engineering concerns have become a Consultants Ltd. as an independent geological/ necessary standard practice in horizontal drilling program. environmental consultancy company. To achieve this, geologists have developed better

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Exploration Applications Developed Inverted Basins in Northeast Egypt: from a Large Geophysical Database, Geology and Hydrocarbon Prospectivities Historical Review 1965-1995 Ayyad, Maher H.* Attewell, Peter* British Gas, Egypt Geophysical Service Inc. Saudi Arabia Ltd. and Adel A. Sehim and Lloyd W. Long Cairo University, Egypt Saudi Aramco Observations of surface geology, integrated with Since the first days of seismic exploration Saudi seismic and well data, in Northern Sinai, revealed Aramco has committed an increasingly large magnificent examples of inverted basins. The volumes of geophysical data to database storage. northern shelf of the Arabo-Nubian Massif These data include seismic survey X-Y coordinates, experienced major extensional deformation seismic time data, stacking velocities, well velocity throughout most of the Mesozoic time. A series of surveys, uphole T-D picks, processing datum and down-to-the-north tilted fault blocks, aligned in residual statics, and the near surface model used for northeast-southwest trending sub-parallel fracture the initial stacked section. Other data kept in lines, have consequently developed. Syntectonic permanent digital form outside the corporate deposition throughout the Triassic, Jurassic and Early database include the "seismic reference datum", near Cretaceous steadily steepened block tilting and surface "frozen velocity models", gravity and formed half graben sub-basins. Basin axes run magnetic measurements, seismic tapes, film and alongside the main active faults where vertical report archives, and results from amplitude versus displacements progressively increase with depth. offset studies and various inversion depthing These sub-basins are on trend with the Palmyra- procedures. Sinjar troughs in Syria and Abul Gharadiq basin in This wealth of information helps geophysicists tackle the Western Desert of Egypt (i.e. Syrian Arc Trend). a variety of problems by providing the data to back- By Mid-Cretaceous, differential movements between up current hypotheses. Generalized "status maps Eurasian and African plates sent compressional and charts" can be periodically updated; flexible forces into the passive margin of Sinai. The program applications can be written to examine the transmitted stresses triggered the older extensional data statistically or in reduced form. This generates fault trends to re-activate in reversed direction. a large "value added" component to be realized from Throughout the Late Cretaceous to Oligocene, the the existing data. Correlating different aspects of basin fills underwent strong inversion uplift along the data can help in cost reduction by targeting the same bounding faults. The inverted basins now additional data acquisition more efficiently. form the huge doubly plunging surface anticlines The historical development of the various database and the large offshore structures. These anticlines sets are described from a user's perspective. Logical are asymmetric in shape and somehow reflect mirror database design with reference to the start-up of 3-D images of the original sub-basins. Such depositional seismic recording are reviewed. Problems and and structuring systems provided unique sites for advantages of transition from a central repository to hydrocarbon generation and accumulation. During today's more fragmented form are discussed together basin development cyclic sedimentation regimes with the issues of physical file maintenance, data (partly restricted, paralic to open shallow-deep integrity and primary data retrieval for use in vendor marine) prevailed and lead to the deposition of applications. Anticipated future developments are organic-rich mature source and reservoir quality reviewed including the planned need for POSC rocks as well as sealing interbeds. Timing of compliance. hydrocarbon generation and expulsion relative to structuring and stratigraphic entrapment is an ideal Peter Attewell is currently with fit. Proven hydrocarbon reserves were established Geophysical Services Inc., Saudi along this structural trend from Abul Gharadiq basin Arabia. He has 25 years of in the Western Desert and offshore north Sinai, Egypt exploration experience including through Palmyra and Sinjar foldbelts in Syria to the work on the southern North Sea gas world class great Arabian basin to the east and fields, and many years of southeast. involvement with Saudi Arabian data. Peter received his BSc in Maher H. Ayyad is the Exploration Technical Supervisor Geology from Imperial College, of British Gas, Egypt. He has 25 years of industry London and is a member of the experience, 23 with Unocal Corporation at various Petroleum Exploration Society of Great Britain and the international locations (Australia, Indonesia, Singapore, SEG. Egypt, Netherlands and Syria) and 2 years with British Gas, Egypt. He is a Certified Petroleum Geologist member Lloyd W. Long (see Al-Nahwi et al., p. 108-109) of the AAPG and has published several papers on

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 geological and geophysical subjects. Adel A. Sehim is Assistant He has a BSc and a MSc in Geology Professor at Cairo University, from Assyut and Ain Shams Egypt. He has 13 years experience Universities and is presently in different fields of geology, preparing his PhD at Cairo particularly the application of University, of which this paper structural geology in industry and represents a part. research. He published 11 papers on structural subjects. He has a PhD from Cairo University.

Sequence Stratigraphic Modeling of Lower Thamama Group in East Onshore Abu Dhabi, U.A.E.

Aziz, Sabah K.* and Mohamed M. Abd El-Sattar Abu Dhabi National Oil Company (ADNOC)

The early Cretaceous Lower Thamama section in East Sabah K. Aziz is a Senior Review Abu Dhabi is deposited during the Berriasian- Geologist with Abu Dhabi National Valanginian time. The section is represented by a Oil Company (ADNOC) in UAE. thick carbonate succession composed dominantly of He has 20 years of experience in the limestone and dolomite reaching more than 1,100 feet field of exploration Geology in in thickness. The section is deposited in a marine UAE. He holds a BSc in Geology setting ranging from shallow peritidal environment from Baghdad University. to relatively deeper shelf basin with well-developed prograding shelfal sediments near the margins. An integrated approach utilizing sequence stratigraphy analysis, bio-lithostratigraphy and Mohamed M. Abd El-Sattar is a electric log data revealed the presence of three Senior Exploration Geologist with sequences (Sequence I, II & III) and two shelf edges Abu Dhabi National Oil Company within the lower Thamama section in East Abu (ADNOC), UAE. He has 21 years Dhabi. These sequences were found to prograde and of petroleum and exploration become progressively younger toward the east experience in the Middle East, of (basinward) with their shelf edges trending in a north which 11 years were with Gulf of northwest-south southeast direction. Suez Petroleum Co., Egypt. He Excellent reservoir development are found to be holds a BSc and MSc in Geology associated with the shelf edges of these sequences, from Ain Shams University, Egypt. particularly within the oblique/sigmoidal types of He is a member of many professional societies and has clinoforms, whereas potential source rocks are published several papers on structural geology and basin expected to be developed basinward. evaluation. Recent exploration activities proved the presence of commercial hydrocarbon accumulation within the Lower Thamama sequences in East Abu Dhabi.

7th ADIPEC Exhibition & Conference 13-16 October 1996 Abu Dhabi International Exhibition Centre P.O. Box 5346, Abu Dhabi, United Arab Emirates Tel: (971-2) 446 900, Fax: (971-2) 446 135

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Qatar, Alkhalij Field: A Diagenetic Trap Fast Pre-stack Migration in the Mishrif Formation Using Equivalent Offsets and Common Scatter Point Gathers Balusseau, Bernard* Elf Petroleum Qatar Bancroft, John C. and Mamdouh Z. El-Demerdash University of Calgary, Canada Qatar General Petroleum Corporation (QGPC) A new method of pre-stack migration is presented Alkhalij oil field is located about 110 kilometers off that runs one hundred times faster than similar the eastern coast of Qatar, on Block 6 granted to Elf methods. The new method includes pre-stack Petroleum Qatar in 1989. The prospect has been migration gathers for accurate velocity analysis. defined as the extent, on a large (130 square Conventional processing requires two time shifting kilometers) but limited tract, of an intra-Mishrif steps of normal moveout (NMO) and post-stack seismic horizon (H2) interpreted as the occurrence migration. These two time-shifting processes may of a porous limestone body at the top of the Mishrif be merged into one process using an NMO-Kirchhoff Formation (Cenomanian). No significant vertical migration operator that combines the source-receiver closure is present in this area which dips gently offset with the migration offset to give a new towards the southeast. This reservoir was assumed equivalent offset. More complex forms of the to be sealed laterally by truncation and/or facies equivalent offset are based on pre-stack migration change and capped by Laffan transgressive shales. principles. The discovery well ALK 1, drilled in 1991, struck a Samples in each input trace are assigned an 41 meter oil column at the top of the Mishrif and equivalent offset then copied into a bin of a common tested 1,600 barrels of oil per day on a 1/2" choke. scatter point (CSP) gather, and repeated for each The extent of the field has been determined by migrated trace. No time shifting of the data is drilling six appraisal and delineation wells together required. The fold in each offset bin may be in the with seismic reprocessing. All of the five wells drilled tens for 2-D and in the thousands for 3-D. Each CSP within the extent of the H2 seismic marker found gather may be scaled and filtered similar to CMP the oil bearing reservoir and thus confirmed the gathers with conventional algorithms. The combined validity of the seismic concept. The reservoir is effects of high fold and large offsets aid in focusing originally composed of inner shelf mudstones to the energy for accurate velocity analysis. Pre-stack packstones strongly weathered during a continental migration is completed by conventional NMO and exposure which took place prior to the Laffan stacking. transgression (Coniacian to Santonian). Weathering The tremendous speed increase is a consequence of dramatically improves the reservoir permeability applying NMO in one operation to all the traces and thus controls the extent of this diagenetic trap. gathered into one bin of the CSP gather. Other advantages allow migration from rugged surface Bernard Balusseau is currently topologies, evaluation of azimuthal velocity Exploration Manager with Elf variations, and the possibility of statics evaluated Petroleum Qatar. He has 16 years before NMO. The presentation includes examples of petroleum and exploration of CSP gathers, velocity analysis panels, and experience. He joined Elf Aquitaine complete pre-stack migrations of modeled and real Group in 1980 and has worked in 2-D and 3-D data. Examples of P-P and P-SV Tunisia, Italy, France and Qatar. converted wave processing will also be included.

John C. Bancroft is Senior Research Geophysicist with the Mamdouh Z. El-Demerdash CREWES project at the University received his BSc in Geology in 1974 of Calgary. He has worked in the from Alexandria University, and in field of signal and seismic the same year joined GUPCO, processing for 24 years and has where he held the head position in specialized in migration for 15 of Geologic Operations, Exploitation, those years. John has developed and North Gulf of Suez Exploration written an extensive range of District Geology and Acting software that includes most Manager and Regional Geology. migration algorithms, modeling, 3-D processing, and basic Mamdouh received his MSc and seismic processing including surface consistent analysis. PhD degrees in Petroleum Geology from Cairo University He is an SEG instructor and has received the Best Paper during his tenure with GUPCO. In 1989 he joined QGPC Awards at CSEG and SEG meetings. He has a BSc and as Senior Exploration Geologist and in July 1993, he was MSc from the University of Calgary and a PhD from appointed as Head of Exploration. Brigham Young University.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Stochastic Modeling of Seeking Low Relief Structures, Subseismic Faults An Original Approach Applied in West Central Oman Belfield, William C. ARCO Exploration and Production Technology, USA Benkara-Mostefa, Cherif, Cyril Saint-Andre*, Eric de Bazelaire and Marc Girard Faults below seismic resolution and fractures can be Elf Aquitaine Production, France important components of a reservoir description because of their potential impacts on primary or Today low relief structures are the main objectives secondary recovery. In attempting to understand the associated with conventional plays in the Middle statistics of these systems, there is a growing East. Up to now the imaging of such structures has concensus that fault and fracture networks exhibit failed because seismic reflections are hampered by statistical similarity over a large range of scale. This strong energy multiples generated by near surface observation implies that power-law statistics are high velocity layers. The result is a reverberating necessary to characterize these systems. In addition seismic environment where it is difficult to separate to results from 3-D seismic interpretation illustrating real events and multiples when processing the data. power-law behavior of fault displacement and Elf has developed a new multiple removal process, length, data from horizontal wellbores in naturally based on inversion, which requires very specific fractured reservoirs clearly indicate scaling acquisition parameters. The success of the technique characteristics of aperture and spacing. There is a is based on the fact that high resolution acquisition general understanding of how to extrapolate allows separation of real events and multiples in a displacement and fault length to smaller scales, but curvature-time domain and then enhances multiple less agreement pertaining to the spatial distribution removal. This original integrated approach has been of subseismic faults. applied with success to the last seismic survey Recent approaches to modeling spatial distribution acquired in the Butabul concession, onshore West of subseismic faults or fractures utilize either ad-hoc Central Oman. assumptions about proximity to seismic faults or attempt to use a spatial characterization based on Cherif Benkara-Mostefa is box-counting. Study of horizontal well fracture data Exploration Manager in Oman indicates that fractures occur over a large range of with Elf. He has 15 years of scale. This observation suggests that fractures are exploration and petroleum industry space-filling (present everywhere) and the exponent experience with the company. measured by box-counting should be an integer. Cherif has a MSc and DEA of Non-integer values reported in the literature reflect Geology from Grenoble University. the inability to measure and record small faults or fractures. Consequently, box-counting provides little useful information. To model subseismic fault spatial distribution, I assume that the scaling characteristics Cyril Saint-Andre is a Processing of fracture spacing, recognized in horizontal wells Geophysicist with Elf. His industry and based on resolution, is also applicable to faults. experience includes 4 years as Geophysicist with Elf where he is William C. Belfield is a Senior in charge of land/marine processing Principal Research Geologist with and supervision. Cyril has an the Reservoir Research and Engineering degree from the Technical Service group at ARCO. Engineer Science Institute of He works primarily in the Clermont II University. His areas description and characterization of of professional interest include natural fracturing and faulting in seismic and signal processing. reservoirs. His degrees in Earth Science are from State University Eric de Bazelaire is Scientific Advisor of New York at Stony Brook. with Elf. He has 15 years of petroleum William is a member of SPE and AGU. and exploration industry experience with Elf, following 11 years of research SEG in optics at the Ecole Polytechnique and GESSY Laboratories. Eric is a member International Exposition of the SEG, EAEG, SFP and SFO. He & 66th Annual Meeting has an Engineering degree from Ecole 10-15 November 1996 Supérieure d'Optique and a PhD in Denver, Colorado Physics. His areas of professional interest include optics, signal processing and geophysics.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Marc Girard is an Acquisition Supervisor with Elf Aquitaine Production. He has 13 years of AAPG INTERNATIONAL exploration experience with Elf CONFERENCE & EXHIBITION where he is involved in the 7-10 September 1997 supervision of 2-D and 3-D land acquisitions worldwide. He has a Vienna MSc in Geophysics from ENSPM. His areas of professional interest "East Meets West" include seismic acquisition and signal analysis.

Petroleum Development Oman Gas Exploration Unlocks Major Reserves

Bichsel, Matthias F.*, Andrew W. Wood and Anthony Mozetic Petroleum Development Oman (PDO)

Since 1985, Petroleum Development Oman has been Matthias F. Bichsel is currently exploring for gas on behalf of the Government of Exploration Director with Oman under a ten-year agreement signed in June Petroleum Development Oman 1984. The aim of the one-rig program was to find (PDO). He has 15 years of additional non-associated gas reserves (3 Trillion industry experience gained with Cubic Feet) to meet domestic energy requirements Shell International. Matthias has for a minimum of 40 years, for which the available worked in various capacities in reserves (5.6 TCF) at that time were insufficient. Bangladesh, Oman, Canada, Initial results of the campaign, which principally Indonesia and The Netherlands. targeted the Permian Khuff Formation, were He holds a PhD in Earth Sciences disappointing, analogues to the major accumulations from the University of Basle, Switzerland and is a member of the Arabian Gulf failing to materialize. During of the AAPG. the second half of the program, therefore, the strategy was revised to address the prospectivity of Andrew W. Wood is currently higher risk/higher reward plays recognized at working with Shell International in greater depths. London as Corporate Adviser. Well Saih Nihayda-24, drilled in 1989, found gas/ Prior to that, he was Exploration condensate-bearing reservoirs in Cambro- Director of Petroleum Development Ordovician sandstones of the Andam Formation Oman from 1992 to 1995. Andrew below 4,000 meters. This discovery, in a seismically has 17 years of industry experience poorly defined anticline, sparked an intensive effort with Shell, gained in various of 2-D, and later 3-D, long cable seismic acquisition. assignments in Europe, Africa and This led in 1991 to additional major gas/condensate the Middle East. He holds a PhD finds in Saih Rawl and Barik, and a dedicated two- from Oxford University and is a member of the AAPG. year two-rig appraisal campaign has since proven up sufficient reserves to support a Liquified Natural Anthony Mozetic is joined Shell Gas export scheme. in 1970. After postings in Holland, The ten-year program has more than tripled Oman's UK, Nigeria and Norway he moved non-associated gas expected reserves to some 22 to Oman in 1989 as Exploration TCF, exceeding the target more than five-fold. Team Leader of Petroleum Significant potential for further gas discoveries Development Oman's gas team. identified in both north and south Oman provides Anthony, who holds a MSc in encouragement for continued successful gas Geology, left PDO in 1995 to take exploration in the future. up an assignment as Chief Geologist with Shell China.

ARABIAN OIL & GAS '96 CONFERENCE: OPPORTUNITIES & TECHNOLOGIES 15-17 September 1996 Oman International Exhibition Centre

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Exploration Data Recovery, Practical Methodology for Interactively Archiving and Workstation Loading Modeling 2-D and 3-D Refraction Statics

Bremkamp, Stephen W.*, Stephen C. Kellogg, Blake, Nicholas* and Charles J.M. Hewlett Cameron M. Luck and Peter C. Green Lynx Information Systems, UK Saudi Aramco This paper focuses on solutions to the access and In the industry's quest for finding new reserves while storage problems faced by seismic interpreters reducing exploration risk, it is often the case that the wishing to use a mixture of both new (perhaps 3-D) extent to which they are able to accurately define the and old (perhaps 2-D) seismic data on a workstation. near surface is directly related to success or failure. Access problems include lack of digital data, The geophysicist must be able to model near surface variations in processing across surveys, and structure and overburden velocity to obtain a seismic inaccurate or missing location data. Such problems section which accurately depicts the sub-surface. can be remedied by the appropriate scanning, We have developed a methodology to model the near vectorizing, reprocessing and data reconciliation surface for large 2-D grids as well as 3-D volumes. methods. Exploration data storage still largely relies We model either the refractor elevation or on warehouses full of magnetic tapes and paper data, overburden velocity: when modeling one, the other with all the attendant problems of maintenance and instantly changes and statics are calculated. access. Both tapes and paper are usually Modeling is now a cooperative effort between the deteriorating rapidly and are always difficult to geologist and the geophysicist, because any near locate. CD-ROMs, D2s and other mass storage surface information can be put into the model. devices can overcome these problems by providing This technique is fast. It is feasible to construct and the facility to store all of this data in a digital form. test an areal model over a prospect in a single day. Once converted it is possible to access this digital Input to the program may be from any refraction archive using universally recognized software analysis package which supplies delay times and standards and inexpensive hardware. Seismic refractor velocities. Graphical 3-D displays and color profiles and well logs for example can be retrieved contours of surface elevation, refractor elevation, from a wide variety of hardware platforms using refractor velocity, overburden velocity, delay times, existing software, reviewed and then extracted statics and seismic data (2-D) are instantly available. quickly and efficiently and converted directly into This technique has been used successfully for workstation-ready format. Four case histories are numerous 2-D and 3-D land surveys acquired over reviewed to show how this integrated approach of several oil fields and prospects in Saudi Arabia. Near data capture, archiving and retrieval can be used surface complexities include solution collapses, sand successfully in a real exploration environment to add dunes and escarpments with as much as three value to any exploration data. hundred feet of vertical relief. Nicholas Blake is currently Stephen W. Bremkamp is a Business Development Manager graduate of Colorado School of with Lynx. He received his BSc in Mines with a BSc in Geophysics. Earth Science from the Open He worked for 10 years with University in 1977. Between 1977 Western Geophysical and has been and 1986 Nicholas worked for SDP with the Saudi Arabian Oil International where he was Vice Company for the last six years. President, Processing. Prior to joining Lynx, he was Consultant Operations Geophysicist in Australasia. He is a member of the PESGB, CSEG and ASEG. Stephen C. Kellogg has a BSc in Physics. He has 16 years experience Charles J.M. Hewlett received his in processing and interpretation. BSc in Natural Science from Oxford Stephen began his career with Mobil in 1967 and a PhD from the Corporation and spent 5 years with University of London, Royal School Placid Oil where most of his work of Mines in 1973. Between 1974- centered on international projects, 1980, Charles was Manager, including Zambia, Thailand, and Technical Support Group with Turkey. He has worked in Algeria Western Geophysical and was and for the past four years has been Geophysical Consultant until 1991. with Saudi Aramco. Charles is presently the Managing Director of Lynx. He has written various papers and is a member of the SEG and PESGB.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Cameron M. Luck graduated from Peter C. Green is currently the University of Calgary with a Processing Geophysicist with Saudi BSc in Geophysics in 1984. Aramco. He received a BSc in Between 1984 and 1991 Cameron Geological Engineering. He worked worked with CGG, Calgary, as a for two years with Digicon Processing Geophysicist. Since Geophysical. Prior to joining Saudi 1991, he has been with Saudi Aramco in 1990, Peter worked with Aramco. Tensor Geophysical for 4 years in Egypt. He is a member of the EAEG and SPE.

Impact of Cemented Zones Associated with Stylolites in Jurassic Carbonate Reservoirs: An Example from the Smackover Formation, Jay Field, Florida

Broomhall, Robert W., Linda W. Corwin*, Ronald M. Saidikowski and J. Noel Wooten Exxon Production Research Company, USA

Stylolites can be an important geologic feature affecting experience in production operations and major pool studies reservoir quality and, consequently, reservoir in three major petroleum basins (Arabian, Permian, Western management, in many large carbonate reservoirs. Canadian). Robert has a BSc in Geology from the University Cemented zones associated with stylolites occuring in the of Florida and a MSc from Northern Arizona University. apparently continuous, high porosity of the Upper Smackover at Jay Field are the probable source of thin Linda W. Corwin is a Senior horizontal barriers/baffles to vertical flow that have been Research Specialist with Exxon suspected since early days of production and supported Production Research Company in by subsequent full-field simulation modeling. These Houston, Texas. Her experience is cemented zones vary from a few millimeters to several in geologic reservoir description and centimeters thick and were often missed during routine construction of geologic 3-D core plug sampling. Mini-permeameter analysis has been numerical models. During the last used to document the decreased permeability adjacent to 15 years, her areas of study have the stylolites. A stochastic 3-D geologic model was included Ghawar and Abqaiq Fields constructed of the distribution of stylolites and cemented in Saudi Arabia, Prudhoe Bay Field in Alaska and, most zones. The model honors: (1) their frequency distribution recently, Jay Field in Florida. Linda has BSc and MSc degrees observed in core both by lithology (limestone and in Geology from Baylor University. dolomite) and by sequence stratigraphic layer, and (2) their location in cored wells. The stylolite/cement model, Ronald M. Saidikowski is a together with geostatistical porosity and permeability Research Associate with Exxon models, provided the reservoir properties required for Production Research Company in input into simulation models. Simulations were run on Houston, Texas, where he has worked models both with and without the cemented zones to: (1) for 20 years as a Reservoir Engineer. determine what impact the cemented zones have on field The majority of that time has been performance, and (2) examine operating strategies for the spent in the area of miscible enhanced miscible nitrogen flood that was initiated in Jay Field in oil recovery, with an emphasis on 1981. Results show that incremental oil recoveries from simulation. He holds a BSc in the miscible flood are higher for cases where the vertical Chemical Engineering from communication is reduced due to the presence of the Northwestern University and a MSc in Computer Science cemented zones. The exact value assumed for the vertical and a PhD in Chemical Engineering from the University of permeability of a cemented zone (0.001 md or 0.01 md) Wisconsin. has minimal impact on the incremental recovery. J. Noel Wooten is an Engineering Robert W. Broomhall is a Senior Technologist with Exxon Production Research Specialist with Exxon Research Company in Houston, Production Research Company in Texas. He has 29 years experience in Houston, Texas. He is currently geological support. He is currently involved in the application of involved in 2-D and 3-D geostatistical as well as classical geostatistical modeling of various geologic methods to the construction fields around the world. of 3-D numerical models of geologic parameters. He has 17 years

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Survey Evaluation and Design Together with Quantified Quality Assurance: An Integrated Approach to Seismic Exploration

Brown, Gordon*, Lloyd G. Peardon and Ian R. Scott Geco-Prakla, UK

Survey Evaluation and Design (SED) of 3-D surveys Lloyd G. Peardon is currently has allowed seismic exploration to proceed with Manager of Geosupport with Geco- added confidence of successful results. By careful Prakla. He began his career as a analysis of survey objectives and the estimation of Research Geophysicist and worked achievable results from existing real data, surveys with Britoil from 1981 to 1988. He are now routinely planned so that a successful joined Seismograph Service (SSL) conclusion can be assured. The backbone to our pre- in 1988 as Research Manager. In survey analysis has been built around methods 1993 he spent a year with designed to quantify data quality. This we term as Schlumberger Cambridge Research the Quantified Quality Assurance (QQA) method. Center as a Research Program In this paper we describe results obtained from a Leader before returning to Geco-Prakla, Gatwick to head number of seismic surveys which benefited from the the Geosupport team. Lloyd holds a BSc in Mathematics combined SED and QQA methods. We demonstrate and a MSc in Digital Signal Analysis from Portsmouth the predictions of data quality prior to data University. acquisition and compare these to results achieved after the final 3-D migrated volume has been Ian R. Scott is currently a produced. Technical Supervisor with Geco- The QQA method involves the statistical separation Prakla's Geosupport Group which of any seismic data into quality attributes combined actively supports all the product with the calibration with borehole data. The lines within Geco-Prakla. Ian has attributes include measures of noise content, wavelet 15 years experience in seismic quality and resolution estimates, while the borehole processing, survey design and calibration includes the confidence of the surface software development. He is a seismic to the underlying reflectivity sequence member of both geophysical and together with phase and amplitude characteristics. geological international professional A derived geophysical model can be used to build societies. He graduated in Geology and Geophysics from an acquisition model in order to predict the QQA Imperial College, London. values for the new acquisition. These predicted values can then be used for Geophysical Acceptance Criteria for monitoring acquisition quality and the VIENNA '97 AAPG same methods can be applied throughout the International Conference processing phase. Thus data quality is monitored continuously up to the delivery of the final product. & Exhibition 7-10 September 1997 Gordon Brown is currently Manager of Survey Evaluation and TWO ORAL SESSIONS Design with Geco-Prakla based in Gatwick, UK and has 20 years on MIDDLE EAST experience in seismic exploration. Prior to joining Geco-Prakla as an Interpreter in 1985, he was Petroleum Geology Headquarters Geophysicist for 5 of the Middle East years with the National Coal Board, ¥ UK. He holds BSc and MSc degrees in Physics and Geophysics, and is a member of the EAEG. Middle East Geosciences Gordon has presented at numerous conferences and has Geo'96 published papers on geological and geophysical topics in "First Break" and "Marine and Petroleum Geology".

ABSTRACT DEADLINE 15 OCTOBER 1996

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Stratigraphy and Palynofacies Character of Structural Elements of Organic-rich Sediments in Precambrian Onshore Kuwait Sandstone in Southeast Sirte Basin Carman, George J. Bu-Argoub, Fawzi M.* and Bindra Thusu Kuwait Oil Company Arabian Gulf Oil Company, Libya Megasequence boundaries in sediments of the Recent advances in high resolution biostratigraphy Dibdibba Basin (~8,000 meters thick) define regional permit the recognition of four episodes of organic- dip as 0.5˚ to 1.5˚ northeast with individual structural rich shale deposition in several relatively small but elements reflecting northerly and northwesterly tectonically silled basins in Precambrian sandstone trends. The dominant structural element is the north- in the southeast Sirte Basin: (a) a lacustrine-lagoonal south trending Kuwait Arch with Greater Burgan shale (Scythian-Ladinian) interbedded with the Amal oilfields in crestal 100 to 500 km2 anticlinal closures sandstone, is a syn-rift deposit, and contains kerogen and 10 to 50 km2 satellite closures on the western types 2 and 3; (b) a non-marine, lacustrine shale flank and northern axial trace. The Kra-Al Maru and (Neocomian-Barremian) interbedded with the Sarir Dibdibba features (like the Mutriba Structure) trend sandstone was deposited in a half graben (silled northwest and separate the Kuwait Arch from the basin), and is dominantly composed of terrestrial Salmi Platform. kerogen types 2 and 3; (c) a brackish-lagoonal Structure and stratigraphic thinning of late Jurassic variegated shale member (Barremian-Aptian), and younger strata indicates structural growth since interbedded with the Nubian sandstone, was ~155 million years before present (Ma) with Recent deposited in a deep graben and contains kerogen overprints; regional data infers Hercynian structural types 1, 2 and 3; and (d) a highly complex and poorly events. Extension, contraction, inversion and studied Cenomanian-Turonian shale, associated with possibly halokinetic mechanisms occur. The Burgan- the Busat Formation, transgressive and Maragh Magwa Graben has a northwest trend re-activated sandstones deposited in shallow marginal marine during the Cretaceous. The Mishrif Unconformity environment, is composed of kerogen types 1, 2 and 3. removed more than 250 meters of sediment during The development of these organic-rich shales maximum uplift ~90 Ma. Other unconformities are correspond to worldwide sea-level rises. However, likely at less than 5 Ma (top Dibdibba), ~30 Ma (top the abundance of kerogen types 2 and 3 in all these Dammam), ~155 Ma (intra-Najmah) and ~350 Ma shales demonstrates the dominant input of locally (Carboniferous). derived terrestrial plant detritus in the basins. These Subvertical normal faults, some possibly deep organic-shales are rich in total organic matter and crustal, generally throw less than 50 meters and have potential to locally generate waxy oil. occasionally occur in swarms; the majority displace strata below the Mishrif Unconformity whilst rare Fawzi M. Bu-Argoub is currently faults reach near-surface. Reverse faults are Head of the Geological Laboratory at interpreted on seismic (~255 meters throw) and in the Arabian Gulf Oil Company, Libya. one well (~30 meters throw). The Minagish and He has 10 years experience in the Umm Gudair structures occur enechelon between the petroleum industry. He is a member of Burgan and Kra-Al Maru trends. Branching faults several international professional with small throws in the Bahrah-Raudhatain region societies and has published several suggest transverse movements. The principal papers on the palynofacies and maximum stress field orientation is 040˚-050˚ biostratigraphy of the Sirte Basin and consistent with regional trends. Cyrenaica in eastern Libya. He has a BSc from Garyounis University Benghazi, a Diploma in George J. Carman has 12 years Micropaleontology from University College London and a MSc experience with major oil companies in Micropaleontology from the University of London. working on exploration, develop- ment and unitisation projects in the Bindra Thusu is currently Geological North Sea, Alaska, Australasia, Adviser with the Arabian Gulf Oil Kuwait and 10 years with Company, Libya and is Research Fellow independent companies. His PhD at the University College London. He research developed a new play has published 35 papers related to concept in Papua New Guinea. petroleum geology and biostratigraphy George is interested in technological of Libya, Canada, Norway and USA. developments and their applications to petroleum geology He has a MSc from the University of and integrated projects involving multidisciplinary Alberta, Canada and a PhD from the research organizations. He has published over 20 papers University of Bristol, UK. Bindra is a on surveying, stratigraphy, structure and field member of several international professional societies. descriptions.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Geophysical. He has been involved Interactive 3-D Near-Surface Modeling with in a broad range of exploration Uphole Surveys and Refraction Analysis: activities in many areas of the world A Case History and has published a dozen papers on geophysical and petroleum Carvill, Charles V. exploration. Darko has BSc and Western Geophysical, USA MSc degrees in Geophysics and and Darko Tufekcic* Geology from the University of Western Geophysical, UAE Zagreb. Nowhere is the accuracy of static corrections as critical as in the Middle East, where large oil fields Continuous Permeability Determination are associated with subtle structure. The goal of 3-D with Stoneley Waves and Multiprobe near-surface modeling is improved static corrections through construction of a velocity and depth model Wireline Formation Testing that is consistent with all known near-surface information. This paper describes a near-surface Cassell, Bruce R.* and Fikri J. Kuchuk modeling project for a large 3-D survey in the Middle Schlumberger Technical Services, U.A.E. East involving an extensive uphole survey program and refraction analysis of reflection records. The Permeability is crucial for estimating producibility project illustrates an effective use of a general- and simulating reservoir behavior. One of the purpose, interactive program for mapping, methods of obtaining continuous in-situ fluid visualization, and analysis of spatial data. mobility is by using the slowness and energy of For this survey, 1,700 uphole surveys varying in Stoneley waves from the dipole sonic tool (DSI). The depth from 30 to 100 meters were acquired. The first other means of determining mobility is by using the step of the modeling process was the importation multiprobe wireline formation tester (MDT). This and quality control of the interpreted uphole surveys. tool provides the capability of conducting controlled All uphole locations, layer thickness, velocities, and local production and interference tests along the hole depths were checked and, as necessary, openhole wellbore. It can be set repeatedly at corrected. We then constructed an "uphole Earth different locations in a single trip and the formation model" consistent with this uphole data to a depth can be probed in detail through pressure transients of 100 meters, i.e., the depth of the deepest holes. using a multiprobe configuration consisting of a sink Next, delay times for an horizon deeper than the (production) and three observation probes. In uphole control were produced through refraction layered formations, this configuration combined analysis of the Vibroseis first arrival data. Then, with high-resolution wellbore images, permits the using a "delay time stripping" technique, the uphole direct determination of both horizontal and vertical Earth model was extended and integrated with these permeabilities on an individual layer basis. delay times forming a "final Earth model". By However, empirical porosity-permeability incorporating the uphole information, the final Earth transforms using openhole logs as well as wellbore model largely resolves the ambiguity between images may not always suggest the best multiprobe velocity and depth. Finally, static corrections were locations to be tested and the probes could be set computed for the final Earth model and applied to against tight zones which may not flow. the 3-D reflection data. Unsuccessful settings cost money and may compromise a number of possible good test locations Charles V. Carvill received a BSc due to operational limits. By combining the DSI and in Geophysical Engineering from MDT in one logging run we are able to define the Colorado School of Mines in optimum test locations for the MDT by direct analysis 1978. After several years in seismic of the effect of fluid mobility on Stoneley wave processing, he joined the Research energy. To demonstrate the validity of the technique, and Development Group at we compare results from Stoneley wave and MDT Western Geophysical as a Research analyses in a Middle East carbonate reservoir. Geophysicist. Charles currently specializes in statics processing Bruce R. Cassell graduated in issues and is a member of the EAEG Geophysics from the University of and SEG. Karlsruhe in 1979. He holds a PhD in Geophysics from the University Darko Tufekcic is Manager of the Western Geophysical of Cambridge (1982). His work Exploration Technology Center, Abu Dhabi. He has 35 experiences are Research years of exploration and petroleum industry experience of Geophysicist with Western which 5 years were with Zagreb University, 14 years with Geophysical until 1985, Chief INA-Oil Industry, Zagreb, and 16 years with Western Geophysicist for Europe with

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Schlumberger (1985-1987). He was Division Geophysicist Fikri J. Kuchuk has a MSc from for North-Continental Europe until 1990, Wireline Technical University of Istanbul and Marketing Manager for Central and Eastern Europe until a MSc and PhD from Stanford 1993, and then Chief Geophysicist for the Middle East University. Before joining Schlum- and India. Since 1995 he is Wireline Marketing Manager berger in 1982, Fikri worked on for Schlumberger for Oman and Pakistan. He is a member reservoir performance and well testing of the SEG, EAEG, SPE and SPWLA. for Sohio Petroleum Company. Since then he has been assigned to Schlumberger Doll Research and, since 1994, he has been Chief Reservoir Engineer for the Middle East and India. He has published more than fifty papers on fluid flow in porous media.

Production Geology of the Safah Oil Field, Sultanate of Oman

Cleveland, Michael N.*, Gerard J. McGann and Hsiu Kuo Chen Occidental of Oman Inc., Oman

A multi-disciplinary approach involving geology, Michael N. Cleveland is reservoir engineering and geophysics is used to currently Chief Production assess and manage the Shu'aiba reservoir of the Safah Geologist with Occidental of Oman field in Oman. Techniques which are currently in in Muscat. He has 18 years of oil use for field management include 3-D seismic industry experience in Asia, Latin acquisition, "slice" mapping, mapping of production America and the Middle East with and pressure data, borehole image logging and Occidental, Cities Service and reservoir simulation. Dresser Atlas. He has authored a Recently acquired 3-D seismic data suggests that number of geological papers and is faults in the field are few and of small displacement. a member of the AAPG and The irregular surface at the top of the Shu'aiba SPWLA. He holds BSc and MSc degrees in Geology from reservoir, previously considered to reflect faulting, Stanford and Rice Universities, respectively. is now recognized as depositional topography developed on a shallow carbonate shelf with local Gerard J. McGann (see McGann et al., p. 168) rudist build-ups. Slice mapping has been used to better describe the Hsiu Kuo Chen is Senior stratigraphically complicated reservoir. This Engineering Adviser with methodology allows a detailed reservoir description Occidental of Oman in Muscat, including incorporation of horizontal well data and where he works in reservoir core data. These maps permit careful placement of management and field development. new horizontal wells so as to avoid local, Prior to this, he worked with discontinuous tight limestones. They also serve as Occidental Petroleum (Caledonia) input for reservoir simulation. Ltd., Occidental Research Corp., Production and pressure maps show anomalous well Phillips Petroleum Co., and Chinese behavior such as high gas-oil ratios. Borehole image Petroleum Corp. He has 24 years logs in horizontal wells permit evaluation of of oil industry experience. He holds a BSc in Mining reservoir heterogeneities such as fractures and lateral Engineering from Cheng Kung University and MSc and facies changes. Heterogeneities are investigated PhD degrees in Petroleum Engineering from Stanford through analysis of petrophysical and engineering University. data to help understand and avoid future problems. Methods to maximize recovery which are currently under consideration are redistribution of gas injection and infill horizontal drilling.

ARABIAN OIL & GAS '96 CONFERENCE: OPPORTUNITIES & TECHNOLOGIES 15-17 September 1996 Oman International Exhibition Centre

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 1981 to 1991. Gary received his MSc in Geology from An Overview of the Hydrocarbon Potential Southern Illinois University at Carbondale in the US. of the Paleozoic Petroleum System Gary has published numerous scientific papers in the fields of the Middle East of coal geology and petroleum geochemistry and has received several professional awards during his career. Cole, Gary A.* BHP Petroleum, Inc., USA Richard J. Drozd earned his PhD and Richard J. Drozd in Physics from Washington Westport Technology Center International, USA University, St. Louis, in 1974, and a BSc in Physics and Mathematics The Paleozoic petroleum system of the Middle East in 1966 from the University of contains one of the best organic-rich, oil-prone source Wisconsin. Richard has twenty rocks found worldwide, the black clastic marine years experience in research and shales located at the base of the Silurian. These shales management within the petroleum represent a widespread marine transgression, have industry with Gulf Oil, Standard a characteristic hot gamma-ray curve, are organic- Oil, and British Petroleum. He is rich (intervals with >10% TOC and oil-prone), and now with the IIT Research Institute. His specialties are responsible for charging structures from Jordan include interpretation of isotopic analyses of gases, seeps to Oman. Oil-oil and oil-source correlations have and oils; applications of geochemistry to problems in the definitively found that the Silurian basal shales are development and production of petroleum; and statistical the source of these oils. The source rock type is treatment of geochemical data. He is author of nine papers similar throughout the Middle East, and the oils covering exploration geochemistry and basin studies. expelled from the basal Silurian marine shales are sweet, light crudes (low sulfur and metals). Improving Reservoir Management The main controlling factor on oil distribution is the burial history reconstructions across the Middle East. with Complex Well Architectures The geological history and the timing of generation and expulsion are key aspects for understanding the Corlay, Philippe*, Dan Bossie-Codreanu, emplacement of hydrocarbons within the Paleozoic Jean-Claude Sabathier and Eric R. Delamaide petroleum system. In the northern part of the Middle Institut Français du Pétrole, France East, hydrocarbon generation and expulsion After 20 years of research and pilot applications, occurred mostly during Paleozoic time. Due to this horizontal wells are currently widely used, becoming "old expulsion", most of the expelled hydrocarbons more and more a matter of standard procedure. have been lost through time. Those areas that are Furthermore, new developments in deviated drilling prospective contain mostly gas (Iraq to northeastern technology start to strongly modify concepts about Saudi Arabia), and some minor oil (Jordan and well architecture. The new techniques of lateral arms, northwestern Saudi Arabia). The mature source cluster wells or extended reach drilling can improve kitchen was extensive and expelled large volumes reservoir management giving economical access to of hydrocarbons during the Devonian period, but new reserves, optimizing marginal or mature fields. present-day field sizes are relatively small and This paper shows how complex well architecture can potential exploration risk is high. In the central and improve oil production through a judicious southern parts of the Middle East (central Saudi placement accounting for the heterogeneities of the Arabia to Oman), the burial history was more reservoir as well as the drive mechanisms involved. favorable for hydrocarbon expulsion and Production can be optimized by monitoring the entrapment. The regional source kitchens in these different sections within a well architecture thus areas expelled hydrocarbons during the Mesozoic prolonging the life of the well. Potential applications through Tertiary. Because these hydrocarbons were for Middle East reservoir conditions are reviewed. expelled more recently ("young expulsion") and post trap The appealing potential use of complex well formation, large fields have been found recently, architecture for characterization purposes at an early particularly in central Arabia, and exploration risk is lower. stage of development is also introduced. An identification of the types of well architectures which Gary A. Cole is presently the could optimize pertinent data to be used by Principal Geochemist for BHP geostatistical models is presented. Methods of data Petroleum, Inc. in Houston, Texas, acquisition within those complex well architectures following a year as a Consulting are shown and new avenues in this field of research Petroleum Geochemist with investigated. A new characterization methodology Westport Technology Center based on hard data acquisition and geostatistical International. Prior to joining methods is proposed. WTCI, he was employed at Saudi Aramco for 3 years from 1991 to 1994, and at BP Exploration from

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Philippe Corlay is Coordinator of Jean-Claude Sabathier is Associ- Advanced and Integrated Reservoir ate Director of Research at IFP in Studies at IFP with 14 years charge of the coordination of experience in reservoir engineering projects on reservoir characteriza- mainly in the domain of IOR tion. Before joining IFP in 1993, applications and horizontal wells. he was scientific manager of Beicip- Before joining IFP in 1986, he Franlab for 22 years, in charge of worked for 4 years as a Reservoir the supervision of the Reservoir Engineer with Beicip-Franlab. Group. He was also attached to the Philippe holds a MSc degree in Civil Ministry of Industry, France, as an Engineering from HEI, Lille, and a post-graduate degree expert on French oil and gas supplies. Jean-Claude holds in Petroleum Engineering from ENSPM, Rueil, France. a MSc degree in Aeronautical Engineering from ENSAE, Paris and a post graduate degree in Petroleum Engineer- Dan Bossie-Codreanu is a Re- ing from ENSPM, Rueil, France. search Reservoir Engineer at IFP. His main interests are IOR appli- Eric R. Delamaide is a Research cations, reservoir characterization Reservoir Engineer with Institut and reservoir engineering. Before Français du Pétrole (IFP). His joining IFP he worked for Geostock main areas of interest are reservoir and Beicip-Franlab. Dan holds a engineering, EOR and drilling. BSc in Petroleum Engineering Eric holds a BSc in Mining Engi- from Texas Tech. University. neering from the ENSM, St. Erienne and a post graduate degree in Petroleum Engineering from ENSPM, Rueil, France.

The Upper Jurassic Stratigraphic Plays in East Abu Dhabi, U.A.E.

Darwish, Abdel Rahman R.*, Mohamed M. Abd El-Sattar and Sabah K. Aziz Abu Dhabi National Oil Company (ADNOC)

The Upper Jurassic sedimentary section in East Abu The paper will discuss the stratigraphic plays, Dhabi represents a major sequence (about 2,000 feet) entrapment mechanism, reservoir developments and of thick limestone with minor dolomite. hydrocarbon potential of the Upper Jurassic section This sequence, which is dated Oxfordian to Tithonian, in East Abu Dhabi. is unconformably overlain by the Habshan Formation of Lower Cretaceous (Berriasian) and Abdel Rahman R. Darwish is a underlain by the Araej Formation of Middle Jurassic. Senior Geologist with the Abu The Upper Jurassic section was deposited over an Dhabi National Oil Company extensive carbonate ramp platform. Several (ADNOC) in the Exploration depositional environments with different facies were Division. Prior to joining ADNOC recognized. The subsidence, eustatic sea level and in 1980, Abdel Rahman was with tectonic movements in the area created an intrashelf National Oil Corporation (NOC) in basin in west Abu Dhabi, whereas shallow shelfal Libya from 1975 to 1980. Abdel sediments were deposited in the east. Rahman received his BSc in Sequence stratigaphic analysis, lithofacies Geology from the Cairo University description and depositional environments modeling in 1974. He is affiliated with the SEE. revealed the presence of two main stratigraphic plays, the Asab Oolites and Hanifa reservoir within Mohamed M. Abd El-Sattar and Sabah K. Aziz (see the Upper Jurassic section of East Abu Dhabi. Aziz and Abd El-Sattar, p. 115) Commercial hydrocarbons have been discovered in both reservoirs in about seven structures in the area.

7th ADIPEC Exhibition & Conference 13-16 October 1996 Abu Dhabi International Exhibition Centre

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Davis, Darrell W.*, Mike J. Sibley, James V. Bent, Jr. and Ben Wang Texaco, Inc., USA

Over 600 million barrels of oil have been produced Mike J. Sibley holds a MSc in from a carbonate reservoir on the Arabian Peninsula. Geology from the University of The dominant lithologies are grain-rich Lower Georgia. He is a Senior Geoscientist Cretaceous limestones. Primary and secondary at Texaco's Exploration and porosity types are present. A major, post-structural, Production Technology Department stratigraphically cross-cutting, diagenetic barrier to in Houston, Texas. He is currently fluid flow has been identified. By restricting aquifer active in exploration, development, support, significant production induced pressure and reservoir modeling activities for depletion has occurred above this nearly horizontal Saudi Arabian Texaco. barrier, resulting in a pressure differential exceeding 800 pounds per square inch at the field center. The reservoir has been modeled for reservoir management and pressure maintenance purposes. The 3-D model has been subdivided into 25 flow units, which reflect the architecture of the major flow James V. Bent, Jr. holds a MSc in and barrier units. These units reflect both Geology from Stanford University. depositional and diagenetic history, and are defined He is a Senior Reservoir Geologist on the basis of cross-disciplinary data. Among these at Texaco's Exploration and data are core and thin sections, core analyses, seismic, Production Technology Department isotope, open-hole logs, TDTs, RFTs, field pressure in Houston, Texas. He has over 10 surveys, oil and water production data and years experience in reservoir production tests. characterization and reservoir Through reservoir simulation of the geologic model, management. His research interests an excellent production and pressure (lateral and include carbonate sedimentology, vertical) match of the field was obtained. Prediction petrophysics, mapping and flow unit modeling. cases for a variety of reservoir management scenarios were modeled. Reserve estimates have been modified, additional infill drilling opportunities have been identified, extension drilling is planned, and a pressure maintenance program is being developed and optimized. Ben Wang holds a PhD in Petroleum Engineering from the University of Texas at Austin. He Darrell W. Davis holds a BSc in is a Senior Reservoir Engineer at Mechanical Engineering from the Timan Pechora Co. (a joint-venture University of Houston. He is a company of Texaco, Exxon, Amoco Senior Reservoir Engineer at Saudi and Norsk Hydro to develop Arabian Texaco's Al-Zour (Mina Russian oil fields). He has 17 years Saud) office in Kuwait. He has over extensive experience in reservoir 15 years experience in production simulations, reserve evaluations, and reservoir studies, and has EOR, coalbed methane production and horizontal well recently focused upon the design of applications. secondary and tertiary recovery projects. He is currently active in reservoir modeling and field development of reservoirs in the Partitioned Neutral Zone of Saudi Arabia and Kuwait.

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Deflandre, Jean-Pierre D.*, Jean O. Laurent, Pierre-Claude Layotte Institut Français du Pétrole, France Frédéric M. Huguet and François Verdier Gaz de France, France

Downhole geophones have been developed for use land sources. He is now in charge of a borehole seismic tool in a permanent way (several years) in producing oil research project. He is a member of the SEG and EAGE. or gas wells. These geophones were designed to be installed between the casing and the tubing and can Pierre-Claude Layotte received be adapted to different well completions. his licence in Physics from the Such geophones are suitable for two types of University of Paris and a graduate applications: microseismic monitoring and 4-D geophysics engineering degree from seismic measurements. Installing 3-component the Ecole Nationale Supérieure du permanent geophones close to the reservoir level Pétrole in 1957. In 1960, he joined enables the recording of microseismic events of very the experimental land seismic crew small magnitude (less than -1). The data obtained at IFP. Starting in 1963 Pierre- make it possible to locate the mechanically active Claude headed the experimental zones associated with fluid injection or withdrawal. seismic crew for many years, For 4-D seismic measurements, these downhole working on various research assignments dealing with geophones enable the easy setting of multi-azimuthal acquisition techniques improvement, design of land seismic borehole seismic to locate, in a repeatable way, the sources and use of shear waves in VSP and surface seismic. displacement of the gas bubble limits in the He is currently in charge of seismic data processing and instrumented wellbore vicinity. interpretation with IFP and Associate Professor at These two applications have been successfully used ENSPM. He is a member of the SEG and EAGE. in two different background gas storage reservoirs since 1991. Results obtained at the first site were used Frédéric M. Huguet received an to improve the technology of the arrays. At the engineering degree from the Ecole second site, one well has been instrumented for three Nationale Supérieure de Géologie years. Comments concerning the results obtained and a graduate geophysics and for each case will be developed. geology engineering degree from the Ecole Nationale Supérieure du Jean-Pierre D. Deflandre received Pétrole. He joined Gaz de France a degree in Physics from the in 1991 and worked as a Geologist University of Paris in 1979 and a with the Geophysical and graduate engineering degree in Geological Service. He is mainly Physics and Instrumentation from in charge of geological and geophysical studies concerning the Conservatoire National des Arts underground gas storage facilities as a specialist in et Métiers, Paris, in 1987. He reservoir geophysics. He is a member of the EAGE. joined IFP in 1979. Jean-Pierre was first involved in thermal EOR François Verdier received an laboratory measurements. Now, as a Research Scientist, engineering degree from the Ecole he is mainly in charge of microseismic monitoring Nationale Supérieure de Géologie interpretation at the Rock Mechanics Department of the and a graduate geophysics Applied Mechanics Division. He is a member of the SPE, engineering degree from the Ecole SAID (French Chapter of the SPWLA) and AFTP. Nationale Supérieure du Pétrole and the Ecole d'Application des Jean O. Laurent received an Techniques Gazières. He joined Gaz engineering degree from the Ecole de France in 1975 and worked with Centrale de Paris in 1962 and a the Geophysical and Geological graduate geophysics engineering Service. He is now the head of this service. His main degree from the Ecole Nationale expertise concerns geophysical and geological studies on Supérieure du Pétrole in 1963. Jean underground gas storage facilities in France and abroad. joined IFP in 1965 and worked for He is a member of the Association Française des many years on land and marine Techniciens du Pétrole, Association des Techniques seismic equipment projects including Gazières and EAGE. hydrophones, streamers, marine and

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Nile Delta Prospective Province, Economics and Exploration Management

Deibis, Said Y. Western Desert Operating Petroleum Company, Egypt

During the last thirty years, the exploration activities of exploration and potential reserves of this province. The covering the Nile Delta of Egypt have yielded several gas paper also discusses how the development of discoveries discoveries. The estimated recoverable reserves are 15 can be effectively implemented by reducing geological trillion cubic feet of gas and the prospective area, north of and economic risks. the central Neogene hinge line, covers about 100,000 square kilometers. Exploration activities have revealed Said Y. Deibis is presently the that the sedimentary sequence is very thick, of which the Exploration Manager and Board Tertiary rocks may exceed 20,000 feet of clastics. These Director of the Western Desert sediments are characterized by the presence of not only Operating Petroleum Company the generating source rocks but also the reservoir sands at (WEPCO). He has 35 years of appreciable depths to drill, and have remarkably good petroleum operation experience, of petrophysical properties. The integrated tectonics of the which 8 years with Belayim Petroleum area, within the regional tectonic framework of northern Company, Cairo, 3 years with Phillips Egypt, coupled with the contemporaneous depositional Petroleum Company, Alexandria and elements, have created several entrapment conditions for 24 years with WEPCO, Alexandria. gas accumulation. Geographically, the Nile Delta province He is a member of several petroleum exploration and production occupies a strategic place close to a highly gas consuming societies and has published several papers on the Geology, market in the Middle East and southern Europe. In these Petroleum and Economics potential of Gulf of Suez, Western countries the demands are expected to double within the Desert and Nile Delta, Egypt. He has a BSc in Geology and coming decade. This paper elaborates on the economics Chemistry from the Faculty of Science, Alexandria, Egypt.

Geostatistical Model for North Ain Dar Pilot, Ghawar Reservoir, Saudi Arabia: An Improved Reservoir Simulation Model

Douglas, John L.* and Members of Ain Dar - Shedgum Modeling Team Saudi Aramco

The North Ain Dar 3-D geocellular model consists of reasonable flow unit boundaries. Further, model geostatistical models for lithofacies, porosity and permeability and production estimated permeability permeability for a portion of the Jurassic Arab-D are correlated on a Kh basis, in terms of vertical patterns reservoir of Ghawar Field, Saudi Arabia. The reservoir of distribution and cumulative Kh values at well consists of a series of shallow water carbonate shelf locations. This agreement between model and well sediments and is subdivided into 10 time-stratigraphic test Kh improves on previous, deterministic models slices on the basis of core descriptions and gamma/ of the Arab D reservoir and indicates that the modeling porosity log correlations. The North Ain Dar model approach used in North Ain Dar should be applicable includes an electrofacies model and electrofacies- to other portions of the Ghawar reservoir. dependent porosity and permeability models. Sequential Indicator Simulations were used to create the John L. Douglas received a BSc electrofacies and porosity models. Cloud Transform degree from McGill University, Simulations were used to generate permeability models. Canada, and a PhD in Geology from Advantages of the geo-statistical modeling approach Memorial University of New- used here include: (1) porosity and permeability foundland, Canada. Between 1984 and models are constrained by the electrofacies model, i.e., 1991 he worked in Calgary, Alberta for by the distribution of reservoir rock types; (2) patterns the Research Laboratories of Texaco, of spatial correlation and variability present in well Canada Resources, and ESSO Canada log and core data are built into the models; (3) data Resources. John's principal respon- extremes are preserved and are incorporated into the sibility during this time was to provide model. These are critical when it comes to determining geological support in the area of reservoir modeling to reservoir fluid flow patterns in the reservoir. Comparison of engineering and development geology groups. John is currently model permeability (Kh) with production data Kh a member of the Southern Area Reservoir Geology Group of indicates that the stratigraphic boundaries used in the Saudi Aramco. His professional interests include reservoir model generally coincide with shifts in fluid flow description and modeling and the application of geostatistical indicated by flowmeter data and therefore represent methods to the spatial distribution of geological data.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 From Frontier Exploration to LNG: Integrating Regional Studies and Modern Technologies to Formulate Upstream Strategies in Yemen

Duval, Bernard C.*, Jean-François Dervieux Total, France and Thibault de Cizancourt Total, Yemen

The paper illustrates the formulation of exploration Bernard C. Duval graduated from strategies applied to two areas of Yemen, with Ecole Polytechnique, Paris, varying degrees of risk: rank wildcat in the East Universities of Grenoble and Dijon, Shabwa Area1, and intensive exploration in the Marib Ecole Nationale Supérieure du Area2. Commercial oil and gas discoveries were Petrole et des Moteurs (ENSPM). made in Mesozoic grabens of these areas, He was employed by Total between respectively, parts of the Wadi Sarr and Wadi Ain 1958 and 1995 and his assignments Basins and the Marib-Jawf Basin. included Libya, Venezuela, Canada Firstly, the petroleum systems in both areas are (VP Exploration-Production, characterized by Marine Type 2 source rocks of North America). Bernard has been Kimmeridgian age, deposited at the time of Senior Vice President Exploration of Total since 1985, in maximum Late Jurassic transgression, with fairly charge of worldwide exploration programs, strategies and high potential (SPI values: 6 to 13 tons hydrocarbon negotiations. He is currently Associate Professor at per square meter). ENSPM. He is a recipient of AAPG Distinguished Secondly, vertical migration drainage is important Achievement Award (International), 1995, and a 1995 to in both cases, although with some lateral component, 1996 AAPG Distinguished Lecturer. particularly in the Marib Basin. High impedance is characteristic of the latter, due to the presence of thick Jean-François Dervieux Portlandian salt formation on top of the Alif fluvio- graduated from Ecole Spéciale des deltaic sand reservoirs. In contrast, a low impedance Travaux Publics, Paris. He was a system is observed in the Shabwa Area, where the Surveyor Engineer with Total oil is found in Barremian-Aptian sands, making the between 1980 and 1986. During relative timing of migration and faulting critical to this period, Jean-François did field entrapment. The success ratios recorded during the work in Sudan, Gabon, Abu Dhabi different exploration phases reflect the risk levels and Algeria and was seconded to applicable to the various play-types. Zakum Development Company The contribution of modern technologies, among where he carried out radio- which sequence stratigraphy and wireline log positioning and geotechnical surveys. Since 1986 as a imagery (in establishing a reservoir geological Geophysicist, he specialized in satellite imagery, remote model), biomarker source characterization and sensing applications and gravity and magnetic geophysics. maturity histories are described. Particular emphasis is placed on the use of satellite imagery and digital Thibault de Cizancourt elevation models to prepare seismic surveys in graduated from the University of extremely rugged high relief canyonland, correlate Clermont-Ferrand with a Master's shallow and deep structural features and make degree in Physics and Ecole preliminary studies of pipeline routes with minimum Nationale Supérieure du Petrole et field operations. des Moteurs, Rueil, France. He was Appraisal is in progress on East Shabwa, employed with Total since 1974 and development is planned in Jannah, as well as his assignments included UK, participation in an LNG project in the Marib-Jawf Argentina, Tunisia and Egypt as a Province. Geophysicist, then Chief Geophysicist. Thibault has been Exploration Manager 1. TOTAL operator, in association with KUFPEC, of Total Yemen during the last 3 years and is now working UNOCAL and COMPLEX. at the Head Office in the Field Studies Department. 2. TOTAL then HUNT operator, in association with YCIOM (Yemen Company for Investment in Oil and Minerals), EXXON, KUFPEC and TECHNOEXPORT.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 data. However, such minor faults have been 3-D Survey Design: interpreted precisely in one of the Abu Dhabi oil Symmetric vs. Asymmetric Split Spreads fields (Field "A") using borehole imagery and well log data from nineteen wells. The sealing nature of Egan, Mark S. fault planes was determined primarily on the basis Geophysical Service Inc. Saudi Arabia Ltd., Saudi Arabia of visual examination of the downhole images. The findings were later confirmed by reservoir pressure Although the CMP fold coverage in a 3-D survey data. might appear to be adequate, it is not always Minor-scale structural features, like fractures, can play guaranteed that a boundary will be properly imaged a vital role in enhancing the permeability of reservoirs in the final processed section. Imaging routines rely with variable matrix permeability like the Thamama. on summation of the traveltime surfaces associated Therefore, an attempt was made to characterize the with many rays. These surfaces constructively fractures in terms of their morphology and origin. interfere at the location of the reflection thereby Three types of processes were identified as the causes creating the image. The point of caution here is that of stresses: fault, overburden and folding related an improperly designed 3-D survey can be lacking stresses which eventually fractured not only the tight in the specific surfaces required to produce the image. carbonates but also the porous carbonates of the Dangerous dip and azimuth combinations can Thamama in field "A". especially arise in surveys that use asymmetrical split The results of the study are being employed in spreads. This is a pertinent point in the Middle East conjunction with 3-D seismic to refine the structural since issues such as multiples and ground roll, not model of the field. The fault and fracture data have imaging, have dominated the process of 3-D survey helped to explain the anomalies in pressure and design in the past. The realization now that faults production data of the Thamama reservoir in field "A". and fracture systems can play major roles in the development of Middle East fields has led to a more Salah El-Shazly is a Lead Reservoir careful analysis of the recording geometries used Geologist with ADCO. He has 17 there. Specifically this study shows via simple years of experience in exploration and modeling how the results in 3-D DMO sections vary production geology, 13 years of which as a function of spread symmetry, spread width, were with Gulf of Suez Petroleum shooting direction and dip. Company. He holds a BSc and MSc in Petroleum Geology from Ain Mark S. Egan is an Area Shams University, Cairo, Egypt. He Geophysicist for Geophysical has presented and published several Service Inc. Saudi Arabia Ltd. (part technical papers in the EGPC of Geco-Prakla/Schlumberger). He Petroleum Exploration and Production Conference (Cairo, has worked for GSISA and/or its 1990 and 1994) and in the AAPG Conference (Dallas, 1991 parent companies for 20 years. In and Nice, 1995). He is an active member of the AAPG and 1975, Mark received a BSc in Physics SEE (Society of Explorationists in the Emirates). from Duquesne University in Pittsburgh, Pennsylvania. In 1978, Salem Al-Matrooshi is a Lead he received a MSc in Acoustics from Reservoir Geologist with ADCO. He the University of Houston, and in 1988, he received a PhD has 7 years experience in exploration in Geophysics also from the University of Houston. and production geology. He holds a BSc in Geology from UAE University, Al Structural Analysis of Faults, Fractures and Ain. He has participated in multi- In-situ Stress and their Roles in Controlling disciplinary studies on different fields in onshore Abu Dhabi. He is an active Reservoir Dynamics of an Onshore Field, member of the AAPG. Abu Dhabi, UAE Neil Young is currently a Senior El-Shazly, Salah E.*, S. Al-Matrooshi, Neil Young Reservoir Geologist with ADCO on Abu Dhabi Company for Onshore Oil Operations (ADCO) secondment from BP Exploration. Neil and Mahmoud Akbar joined BP in 1980 as a Petroleum Schlumberger, Saudi Arabia Engineer, working on North Sea fields. He was also seconded to QGPC for 3 Development of any hydrocarbon field is very years followed by 7 years in reservoir dependent upon accurate delineation of its structural engineering on the North Sea. He grain both at smaller and larger scales. Reservoir graduated from Heriot-Watt compartmentalization is very much controlled by University with a BSc in Mechanical smaller faults which sometimes are difficult to see Engineering. and interpret correctly from both 2-D and 3-D seismic Mahmoud Akbar (see Al-Deeb et al., p. 100)

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Standard processing sequence up to final DMO stack and Dealiasing DMO: migration including calibration using elastic instead of A Practical Technique to Process Data plane-wave synthetic. The interpretation team generates with Irregular Acquisition Geometry a first macro model of the velocity field. Phase B: Post- stack depth domain: the velocity field is checked and Ferber, Ralf updated using the wavefront method. The new macro Schlumberger-Geco-Prakla, UK model forms the basis for post-stack depth migration, which is reinterpreted by the interpretation team in order Irregular acquisition geometry is inevitable due to to generate the final macro model required for Phase C. obstacles and cable feathering in 3-D marine surveys, Phase C: Pre-stack depth-domain: the pre-stack depth widely spaced ocean bottom cables, and access limitations migration is subject to final interpretation and due to the in 3-D land surveys. Such irregularities degrade the irregular surface of the Shu'aiba Formation, should form fidelity of reflectors' image and wavelet. Reservoir the basis for AVO. Further steps are L1 deconvolution characterization based on seismic attributes, inverted followed by Born inversion, which is essential for acoustic impedance, and AVO analysis, is very sensitive generation of a high resolution lithological model. The to degraded amplitude and phase. The footprint of the procedure is presented using a 2-D seismic line, which acquisition geometry may lead to incorrect interpretation was subjected to detailed interpretation (seismic sequence unless it is properly handled in the processing. Dealiasing and facies analysis) of the Shu'aiba Formation. The final DMO is a constrained inversion method that finds the result is a detailed lithological model which is verified by optimal model to fit given data, using forward and applying elastic forward modeling. The results are to be transpose modeling to iteratively minimize the misfit of used as input in reservoir modeling and geostatistical the model to the data. The method produces high quality evaluations in order to take into account reservoir images even in the presence of considerable geometry heterogeneities being important for prospect evaluation. irregularities that would require in-fill surveys with other processing techniques. Applied in offset ranges the Klaus C. Fischer joined the Seismic method benefits pre-stack analysis such as velocity and Interpretation Service Group of AVO analysis after pre-stack migration. The dealiasing Schlumberger GeoQuest in 1985. Since inversion requires significantly more computing and 1993 he has been the Manager of the I/O resources than DMO processing. However, the Seismic Interpretation Services Group. technique is now practical on modern parallel computers. He studied Geology at the University of Stuttgart and received a Diploma in Ralf Ferber is currently Senior Geology from RWTH Aachen in 1983. Research Geophysicist with Klaus is professionally working in areas Schlumberger-Geco-Prakla, UK. He such as seismic stratigraphy and basin has 10 years work experience in 3-D evaluation. He is affiliated with the EAEG and AAPG. seismic data processing. Ralf is a member of the EAEG. Ulrich Möller joined the Seismic Interpretation Service Group of Schlumberger GeoQuest in 1990. He is currently a Senior Seismic Interpreter. Between 1987 and 1989, Ulrich was an Assistant at the Institute Advanced Seismic Data Interpretation for for Petroleum Geology at the Technical Carbonate Targets Based on University Clausthal. He obtained a Optimized Processing Techniques Diploma in Geology from the Technical University Clausthal in 1987. Ulrich Fischer, Klaus C.*, Ulrich Möller is professionally working in areas such as seismic stratigraphy and basin evaluation. He is affiliated with the AAPG. Schlumberger GeoQuest, Germany and Roland Marschall Schlumberger-Geco-Prakla, Germany Roland Marschall has been with Geco-Prakla since 1967. He is The Shu'aiba Formation represents one of the most prolific currently the Chief Geophysicist Land hydrocarbon reservoirs in Abu Dhabi. The remaining Data Acquisition with Geco-Prakla in potential is believed to be related to subtle structural and Hannover, Germany. Roland stratigraphic traps. New developments in exploration graduated from Montan University geophysics like pre-stack depth migration integrating Leoben with a Diploma in Engineering processing and interpretation form a powerful tool for in 1966 and a PhD in 1975. In 1990 improved development of existing oil fields and for he obtained full Professorship at Ruhr identification of new oil fields. In general the processing University Bochum. He is affiliated is comprised of three phases (depending on the local with the EAEG, SEG and DGG and is interested in seismic validity/violation of the zero-offset-condition): Phase A: data acquisition, processing and interpretation.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Intensive Exploration in the Euphrates Graben, Syria

François, Denis * Elf Hydrocarbures Syrie and Wasif Al Youssef Syrian Petroleum Company, Syria

The combination of extensive 3-D seismic surveys, Wasif Al Youssef is the Director field development, sedimentological and of the Exploration Department, geochemical studies has resulted in an accurate Syrian Petroleum Company, since definition of the petroleum system of the Euphrates 1988. Since 1972 he has held the Graben. This combination of techniques has resulted positions of Director, Service- in the discovery of several hydrocarbon Contract Department; Director, accumulations with a success ratio of 50%. Petroleum Studies Department; and as Chief of Petroleum Reservoir Denis François is the Exploration Engineering. Wasif received his Manager in Elf Hydrocarbures Diploma-Engineering degree in Syrie. He has 15 years of oil Petroleum Geology in 1972, and his Doctorate in exploration experience with Elf in Petroleum Engineering in 1993 from the Institute for Morocco, Angola, Congo, France Geology of Energy and Exploitation of Combustible and Syria. He graduated from the Resources. Wasif has participated in numerous energy- Ecole Nationale Supérieure des related conferences as a speaker. He is a member of the Petroles et des Moteurs of the Renewable Energy Resources Committee at the Read French Petroleum Institute (IFP) University, London. and has a MSc in Geology from Lyon I University.

Palynostratigraphic Zonation, Sedimentation History Reconstruction and Hydrocarbon Potential of the Paleozoic Sediments of Northwest Arabian Peninsula and their Equivalent in Algeria and Western Libya

Futyan, Abda R.I.* and Adil H. Jawzi Futyan Jawzi and Associates, UK

Oil and gas deposits were recently discovered in the The main producing reservoirs in Arabia are the Paleozoic basins of Saudi Arabia, western Iraq, Cambrian sandstones, Upper Ordovician and Upper Jordan, Syria and southeast Turkey. These and the Silurian sandstone, Lower Carboniferous carbonates petroliferous Paleozoic basins of North Africa were and sandstones, and Lower Permian sandstones. part of the same Paleozoic mega-basin and shared Major source rocks are present within the Middle similar geological, sedimentation and tectonic Cambrian and several horizons within the history. Ordovician, Silurian and Carboniferous sediments. Detailed palynostratigraphic analysis of a large The main producing reservoirs in North Africa are number of well samples (mainly from Jordan) the Cambrian, Ordovician, Silurian, Devonian, established seven regionally mappable Carboniferous and Triassic sandstones. Major palynological time zones for the Cambrian- source rocks are present within the Ordovician, Ordovician sediments, eight for the Silurian, ten for Silurian and Carboniferous sediments. the Carboniferous and four for the Permian. The In this paper, the stratigraphy, sedimentation history, Devonian sediments are eroded from most of potential reservoirs and source rocks in Algeria and northwest Arabian Peninsula. Paleoenvironmental western Libya and Arabian basins will be illustrated reconstruction, lithofacies, thickness and lateral and correlated. The present day distribution of the distribution maps were produced for the established oil and gas fields and the hydrocarbon potential of 30 palynological zones. Similar analysis of a larger some Paleozoic plays in Jordan will also be discussed number of well samples (mainly from Algeria) and illustrated. established over 50 regionally mappable palynological time zones (Cambrian- Carboniferous).

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Abda R.I. Futyan is currently the Adil H. Jawzi is currently the Managing Director of FJA Inter- Director of FJA International national Petroleum Consultancy Petroleum Consultancy, based in based in Llandudno, Wales. He has Llandudno, Wales. He has 25 years 33 years experience in petroleum experience in petroleum exploration. Abda previously exploration. He previously worked worked for Natural Resources for Iraq National Oil Company and Authority in Jordan, for Saudi Robertson Research between 1978 Aramco, PDO, Oman and and 1989. Adil has a BSc (Hons) between 1973 and 1989 with in Geology from London Robertson Research. He has a PhD in Biostratigraphy University. and a MSc in Petroleum Reservoir Engineering from London University.

Seismic Processing Issues in the Design of 3-D Surveys

Galbraith, James M. Seismic Image Software Ltd., Canada

3-D seismic data are processed through a series of In conclusion, survey geometry affects seismic steps typically; statics, NMO, DMO, Stack and processing. Offset distribution is the major factor in Migration. creating geometry "imprints" on the data, although For refraction statics we must ensure that both azimuth plays a significant role in statics calculations. shallow and deep refractors are adequately sampled. As 3-D designers, we must ensure the most even mix Modeling by bins using typical velocities is of offsets possible - if necessary by moving and/or performed to ensure adequate offset sampling and adding shot points. range for velocity analysis. Straight line geometries are uncoupled for reflection James M. Galbraith received his statics solutions. Statics coupling can be ensured by BSc (Honors) in Mathematical breaking up the regularity of the geometry or by Physics from the University of using smoothers in the structure term leaving long Edinburgh in 1967. He is presently wavelength errors. the President of Seismic Image Weighted DMO fold in each bin can be calculated Software, Canada. Mike served as for a specific time and velocity. In the presence of President of Veritas Software Ltd. dip the DMO response may be calculated for each (1984-1987), Programming bin. Examples of such DMO responses from different Manager of Veritas Seismic Ltd. geometries show severe phase and amplitude (1975-1984), Programming changes indicating that such dipping targets if really Manager of R.B. Cruz and Associates Ltd. (1971-1975), present would show strong geometry imprinting. and Research Assistant of the British Gas Council (1968- Random and coherent noise will be attenuated by 1970). His areas of interest include design of 3-D seismic CMP stacking provided there is a good mix of offsets surveys, computer interfaces for enhanced understanding in each bin. The full fold area must allow for the and productivity in survey design and seismic data migration aperture. Migrating a portion of a processing, front-end seismic processing techniques and diffraction gives some fraction of the correct energy. algorithms and imaging techniques. Mike is a member of Not quite full-fold traces may be acceptable for bins the SEG, EAEG, AAPG, CSEG, DGS, ASEG, PESGB, near the edge of the survey. IEEE and APEGGA.

1996 AAPG ANNUAL CONVENTION 19-22 May San Diego Convention Center

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Block 4, Shabwa Basin, Yemen: The Structural Control on Sedimentation in a Mesozoic Rift Basin and Its Impact on Hydrocarbon Distribution

Gerdes, Keith D.*, Gurdip Sahota and Joseph Brannan Nimir Energy Services Limited, UK Abdullah Hassan and Mohammed Barahim Nimir Ayad, Yemen

Block 4 lies in a central position within the Shabwa from Durham University, UK and a PhD in Geophysics rift and includes a major transfer zone and the from University College Swansea, Wales. He is a member western flank of a central basin high within its of the AAPG, AGU and PESGB. boundaries. Most sediments in such a setting are axially transported and hence the effect of localized Gurdip Sahota (see Sahota et al., p. 186) topography on sedimentation cannot be discerned. The predominance of carbonate lithologies in the Joseph Brannan is an Exploration Jurassic rift sequences in Block 4 illustrate that Geologist with 14 years experience siliciclastic input in the block was restricted to in the oil industry. He joined BP discrete depositional events. Seismic and well data from university in 1982 and spent from Block 4 therefore provide a unique opportunity 10 years working in a number of to map and model the interaction of tectonics and hydrocarbon provinces. His major sedimentation in a central location within the rift. areas of activity included the North Recently, 1,600 kilometers of 80-fold seismic data Sea, North Slope of Alaska, PNG, were acquired in Block 4 and three exploration wells South America and the Middle drilled. The data were augmented by the previously East. He joined Nimir Energy existing well and seismic database. Detailed Services Limited in 1992, and since then his major area of structural and seismostratigraphic mapping of this interest has been Yemen. Currently he is responsible for data reveal the major structural elements and seismic exploration interests in the Middle East and the North sequences within the block. Depth conversion of African region. Joseph holds a BSc from Glasgow surfaces correlated with major sequence boundaries University and a DPhil from Oxford University. He is a provides a suite of maps which demonstrate the fellow of the Geological Society and a member of PESGB. relationship between structure and deposition in Block 4. Transfer zones and sediment entry points Abdullah Hassan is a Geologist are identified and their influence on both structure with the Ministry of Oil and and rift sedimentation illustrated. Mapping of Mineral Resources (MOMR), evaporite sequences show the control of pre-existing Yemen. He is currently on structures on halokinesis. Finally, seismo- secondment to Nimir Petroleum stratigraphic mapping of the Cretaceous sequences Company where he has been demonstrates the channelling of prograding working as a Geologist since 1991. sequences by halokinetic features. The implications Abdullah worked on the West Ayad of this relationship between tectonics and sediment oil field with MOMR between deposition for the generation and distribution of 1984-1991. He graduated from hydrocarbons is discussed. Bucharest University, Romania in 1984 with a MSc in Geology. Keith D. Gerdes has been Geophysical Manager at Nimir Mohammed Barahim is a Energy Services Limited since Geophysicist with the Ministry of 1992. He has 12 years experience Oil and Mineral Resources in the oil industry, initially in (MOMR), Yemen. He is currently production geoscience with Shell on secondment to Nimir Petroleum International. In 1986 he joined BP Company where he has been International and the Basin Studies working as a Geophysicist since Group reviewing new venture 1992. He worked for the Yemen opportunities in Europe, Africa, Company for Investment in Oil and Middle and Far East. He also contributed to and led in- Minerals for 2 years and also for the house courses in seismic stratigraphy and carbonate MOMR for 2 years. He graduated from the Mining exploration. He holds a BSc in Geology and Geophysics Academy in Freiberg, Germany in 1985 with a degree in Geophysics.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Spatial Patterns of Porosity/Permeability Deriving Permeability Transforms for Using Simulated Annealing Method Reservoir Simulation Models: A Practical Example Ghori, Saleem G. King Fahd University of Petroleum and Minerals, Gidman, June* Saudi Arabia Chevron Petroleum Technology Company, USA and Dennis J. Fischer The simulated annealing method (SAM) has been a Cabinda Gulf Oil Company Ltd., Angola successful reservoir characterization tool in geostatistics. This paper presents an application of Simulation is an important tool for reservoir management. SAM to simulate rock properties of carbonate Populating the simulation grid with structure, porosity, reservoirs in Saudi Arabia. permeability, and saturation data is one of its technical The method was applied to a carbonate reservoir in challenges. Of these variables permeability is particularly Saudi Arabia consisting of well log porosity in 131 problematic. Currently there are no logging tools that wells. A two component objective function was provide generally acceptable measures of permeability. minimized. The components of the objective Instead, most often core data are used to derive a function were the experimental variogram and the correlation-based porosity/permeability transform. While pairs involved in at least one conditioning (known) there is commonly some relationship between porosity datum. Several images of the porosity values were and permeability, this relationship is rarely sufficient by generated. These were also compared with the itself to adequately predict permeability. We take various images obtained from the Gaussian sequential approaches to predicting permeability, based on core and simulation method (GSS). Results show that SAM log data. Core and log data must first be quality controlled is superior to the GSS method in the sense that and depth matched. Since porosity is an important experimental variograms are reproduced exactly. component of most transforms, it is essential that porosity The spatial patterns of porosity are more realistic and derived from log interpretation compares well to porosity represent the true variability of the reservoir rock. from core. We find that permeability predictions based The use of the conditioning point in the minimization on a combination of regression and model-based of the objective function reduces the discontinuity techniques most often provide the best results. There is of images near the wellbore with known data. generally some fine tuning to take into account V shale, The simulated annealing method was also applied fluid content (gas, oil, or water), reservoir lithology, and and tested on an exhaustive minipermeameter borehole rugosity. Our assessment of the best transforms measured permeability data set obtained from a rock is made by comparison of core and log data on depth sample. The data from a tracer flow experiment was plots. The calculated data are subsequently input to also used in the SAM. The method was used in the geostatistical modeling, scale-up, history matching, and conditional simulation, assuming some of the known reservoir simulation. The transforms are specific to the permeability data. The conditional fields are then reservoir studied, but the approaches can be applied to used in the simulation of a miscible tracer flow other fields where there are core and log data. through the sample rock and compared with the actual tracer concentration curve. Results show that June Gidman is a Geologist with the exact experimental variogram was reproduced. Chevron. She has 17 years of It is possible to reproduce tracer output curves by experience, with 4 in BP, 3 in Union using it as the objective function in the SAM. Texas, and 10 in Chevron. She is involved with the SCA and has Saleem G. Ghori received his BSc published on core handling, core-to-log in Petroleum Engineering from the data integration and reservoir geology. University of Engineering and June received her BSc in Geology Technology, Lahore, Pakistan. He (Honors) from Leicester University and received his MSc and PhD from the a PhD from Liverpool University. New Mexico Institute of Mining and Technology, USA, both in Dennis J. Fischer is Chief Petroleum Engineering. After Development Geologist with Cabinda. graduation in 1992, he worked as a He has 13 years of petroleum in Research Associate in the Petroleum research, operations, formation Engineering Department of the University of Texas at evaluation, exploration and Austin. Saleem joined the Research Institute at King Fahd development. Dennis is a member of University of Petroleum and Minerals in November, 1993. the AAPG, SPWLA, SPE, and has His research interests are geostatistics, reservoir flow published on formation evaluation and simulation, tracer technology and parallel processing reservoir characterization. He has a BSc computers. He is a member of the SPE. in Geology/Geophysics and a MSc in Mining Engineering, from the University of Wisconsin.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Using Borehole Profiles or Structural Cross-Sections with Geological Images

Gozoren, Tarik I.* and Khaled A. Al-Bassam Saudi Aramco

A geological cross-section or a simple well-borehole profile Tarik I. Gozoren is System Analyst can be significantly improved for better reservoir of the Geologic Application Services characterization when displayed with sub-surface Division of Saudi Aramco. He has 23 geological images. 2-D computer generated geological years experience in geological and images are easily generated and are independently used exploration applications. Tarik received to enhance reservoir interpretation. This study presents a his BSc and MSc degrees in Geological simplified model-overlay procedure and its common Engineering from Istanbul Technical applications for several Saudi Aramco reservoirs. University. Geological images consist of either well-to-well lithofacies distribution, seismic sections or reservoir property distributions. Any one of these, or combination of two Khaled A. Al-Bassam is can be overlaid on a standard structural correlation panel. Administrator of the Geologic Correlation panels are created by applying a scaled well- Application Services Division of Saudi spacing option at the top of the reservoir. Top and bottom Aramco. Khaled has 13 years penetrations are the target boundaries for image overlays. experience in geological and exploration An identical procedure is applied for the simple well- applications. He received his BSc in borehole profile displays. Accuracy should be maintained Civil Engineering from King Fahd by transforming all cross-sections and overlays using a University of Petroleum and Minerals. specified projection system and geodetic datum. This study, however, applies a geometric-N degree polynomial -transformation determined by the Least-Square Fit method.

Three-Dimensional, Carbonate and Siliciclastic, Forward Modeling

Granjeon, Didier H.*, Philippe R. Joseph, Institut Français du Pétrole, France François Guillocheau and Cecile D. Robin, Rennes University, France

A three-dimensional stratigraphic forward model has understanding the carbonate and siliciclastic filling of a been built at IFP to simulate geometries and lithologies of basin. coastal environments, e.g., coastal plain, shoreface and upper offshore in a high-resolution sequence stratigraphic Didier H. Granjeon is a Geologist in framework. The model is based on an improved diffusion the Production Geology Group at equation, result of the coupling of mass conservation with Institut Français du Pétrole (IFP), production and transport relations for carbonate and/or Rueil-Malmaison. His research siliciclastic sediments. The model can be used in two interests are in geosciences and different ways. Firstly, it allows to quantify the relative deterministic approach applied to 3-D influence of key parameters such as eustasy, subsidence basin modeling. He holds a Civil and sediment supply on the basin-infill architecture. Engineer's degree in Geology from Secondly, applied on subsurface studies, an inverse Ecole des Mines de Paris and a PhD in method is used to fit the simulation to the available well Geology from Rennes University, data. When this match is achieved, modeling improves France. and validates the sedimentological correlation scheme and helps to better predict the extension of sedimentary bodies Philippe R. Joseph is a Senior in exploration and appraisal studies when few wells are Geologist in the Production Geology available. The model has been successfully applied on Group in Institut Français du Pétrole two field studies: the Lower Cretaceous mixed carbonate- (IFP), Rueil-Malmaison. His research siliciclastic formation (total simulated duration = 10 million interests are in the combination of years) of Paris Basin, France at a regional scale (160 x 200 deterministic and stochastic techniques square kilometers), and the Campanian siliciclastic for 3-D sedimentological modeling of formation (total simulated duration = 100,000 years) of reservoir bodies. He holds a Civil San Juan Basin, USA at a reservoir scale (10 x 20 square Engineer's degree and a PhD in kilometers). These applications validate the principles Geology from Ecole des Mines de Paris, used in the model and provide a quantitative tool for better France.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 François Guillocheau is Head of Cecile D. Robin is a Geologist in the High Resolution Sequence Sedimentary Group at Rennes Stratigraphic Project at Rennes University, France. Her research University. His research interests are interests are in stratigraphic record of in facies sedimentology, genetic basin deformation and in sedimentary stratigraphy, and comprehension of and tectonic evolution of Paris basin. sedimentary record from a reservoir to She holds a Civil Engineer's degree and a basin scale. He holds a PhD in a MSc in Geosciences from Ecole de Geology from Brest University, France Géologie de Nancy, France and a PhD and a These d'Etat from Strasbourg in Geology from Rennes University, University, France. France.

The Rangefront Fault of Northern Oman and its Effect on the Hydrocarbon Potential of the Gulf of Oman Basin

Hanna, Samir S.*, Sultan Qaboos University, Oman and David W. Rodgers, Idaho State University, USA

The Late Cretaceous period in Oman was dominated by Samir S. Hanna received his BSc and a well-documented thrust tectonic regime which involved MSc from Assyut University, Egypt, the emplacement of the Semail ophiolite. Subsequent post- and a PhD on Tectonics of the Welsh orogenic extension and exhumation created the modern and Irish Hercynian Orogeny from Oman Mountains. Major fault zones which flank the Swansea, UK. He has been actively mountains contain numerous kinematic indicators that pursuing research on Oman since 1982. record a polygenetic movement history. Detailed study He worked in Swansea University, UK of the northern rangefront fault indicates a dominant top- and consulted for Amoco International to-the-north-northeast slip direction, with as much as for about 6 years on the tectonics of several kilometers of slip, along normal and oblique faults. Oman and UAE. Samir is currently Associated volcanic rocks (undersaturated alkali olivine an Associate Professor at Sultan Qaboos University, Oman basalt with fresh mantle nodules) suggest extension was where he has been working for eight years. He has written a deep-seated. The rangefront fault and associated book on the Geology of Oman, published in 1995. structures must have influenced the sedimentation of the offshore hinterland Tertiary basin in the Gulf of Oman. David W. Rodgers received his BSc Shales of the Eocene Rus (Rusayl) Formation are a potential from Carleton College, USA, and a hydrocarbon source and the overlying nummulitic Eocene PhD on Hinterland Tectonics of the limestones of the Dammam (Seeb) Formation and Sevier Orogenic Belt from Stanford Oligocene Mam reefs (Azmari of Iran) form a potential University, USA. He has taught at reservoir. An overlying thick Neogene sequence should Idaho State University since 1985 and be sufficient to locate source rocks in the oil window. A currently serves as Department Head. model involving dip and oblique slip along faults of this His two areas of active research are hinterland basin suggests that potential large-scale traps hinterland tectonics of fold-thrust belts may exist. and crustal extension near hotspots. David received a 1994 Fulbright Scholarship to Sultan Qaboos University, Oman, where he taught classes and conducted research in structure and tectonics.

3-D Seismic Acquisition Experience in Saudi Arabia

Hastings-James, Richard* and Kamal M. Al-Yahya, Saudi Aramco

Saudi Aramco has acquired over 5,000 square kilometers parameter variation on crew production rates will be of land 3-D seismic data over large fields in Saudi Arabia. presented. Acquisition parameters have evolved considerably since Richard Hastings-James is currently the inception of the program as new technology has Geophysical Consultant with Saudi become available and experience has been gained. Aramco. He has 16 years of exploration Currently data is acquired with crews having the industry experience, 12 of which were capability of efficiently recording well in excess of 1,200 with Amoco Production Company in channels per crew at folds ranging up to 288 into 25 x 25 Canada, Houston and various locations meter bins. 3-D seismic data from these fields will be used throughout Africa and the Middle East. to illustrate the sensitivity of the data quality to changes Prior to that, he was an Associate in various acquisition parameters. The impact of (cont. p. 146) 145

Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 (cont. from p. 145) Professor at the Technical University of Nova Scotia, Canada. areas of research are in high-precision kinematic GPS He has been with the Geophysical Operations Division of Saudi positioning as well as in the integration of GPS satellite Aramco since 1992. Richard has a BEng degree in Electrical observations with other sensors like inertial navigation Engineering from the Technical University of Nova Scotia and systems for various applications on land, marine and a PhD from Trinity College, Cambridge. He is a member of the aviation, in particular with respect to navigation, guidance, SEG and Dhahran Geological Society. attitude determination and gravity field recovery.

Kamal M. Al-Yahya has a BSc in Advances in LWD Technology Permit Physics (1980) from King Fahd University of Petroleum and Wireline Replacement in Horizontal Minerals, Dhahran, Saudi Arabia, Development Wells a MSc in Engineering Geosciences (1983) from the University of Heysse, Dale R.* and Charles E. Jackson California, Berkeley, and a PhD in Halliburton Energy Services, USA Geophysics (1987) from Stanford Measurement-while-drilling (MWD) technology has University. Currently he is serving steadily improved during the past 15 years. Early as Chief Geophysicist, Geophysical MWD was limited to gamma ray and directional Operations, Saudi Aramco. His areas of interest include measurements, which provided enough data to signal processing, integrated reservoir studies and data correlate with other wells. Later, resistivity logging- acquisition. He is a member of the SEG, EAEG and while-drilling (LWD) also became accepted as Dhahran Geological Society. equivalent or superior to wireline resistivity. However, complete replacement of wireline logs by LWD has been limited by a number of factors. First, New Possibilities in Airborne Gravimetry: some wells require special formation evaluation State-of-the-Art 1996 methods, including high-resolution borehole imaging and wireline formation sampling (sidewall Hein, Guenter W. cores and formation tests), and these are not yet Institute of Geodesy and Navigation, available as LWD. University FAF Munich, Germany In addition, the acceptance of LWD density and neutron porosity logs has been slow, as many This paper reviews the progress in airborne operators have found the LWD version to be inferior gravimetry. After defining the role of airborne to wireline. The quality of LWD density and neutron gravity measurements in geodesy and exploration logs is primarily limited by the inability to completely geophysics, solved, open and critical problems are press LWD tools against the borehole wall and thus discussed in consideration of the various error eliminate standoff. Modeling, lab tests, and field sources. With the advent of satellite measurements experience show that one inch of standoff can shift to the Global Positioning System (GPS) scalar the neutron porosity by 5 porosity units, and the airborne gravimetry techniques have now reached a density measurement by 0.40 gram per cubic level where under favorable conditions accuracies centimeter (approximately 25 porosity units). Only of 1 to 3 milliGals (mGal) over wavelengths of 3 to 5 lately has the LWD technology improved to the point kilometers can be achieved. The approach as well where the standoff can be measured, and most as available hardware and software are presented. standoff can be prevented from affecting the Prospects are discussed to reach accuracies of 1.0 measurements. mGal over 1.0 kilometer wavelength and better. Finally, many formation evaluation programs require Possible strategies are outlined in detail: (a) using borehole-compensated sonic logs. This is especially modifications and a fine tuning of existing airborne true where advanced 3-D seismic methods are gravity meters; (b) using inertial platform as well as employed in reservoir management. The LWD sonic strapdown system for scalar and vector gravimetry; tool has recently become available to the industry. and (c) to develop a ballistic airborne gravity The development of advanced LWD density-neutron gradiometer. tools and borehole-compensated sonic tools means that more operators can replace wireline logs with Günter W. Hein is currently Full LWD logs without sacrificing measurement quality. Professor and Director of the This is particularly attractive in horizontal Institute of Geodesy and development wells, where wireline tools must be run Navigation at the University FAF on drillpipe or coiled tubing. In many development- Munich. He was President of the drilling situations, the formation evaluation program Special Study Group "Airborne is reduced and special methods, such as borehole Gravimetry" of the International imaging formation sampling, are not required. Thus, Association of Geodesy (IAG) horizontal development wells may be excellent between 1991 and 1995. His major candidates for wireline log replacement by quad-

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 combo LWD logs (resistivity, density, neutron and MOST has successfully identified hydrocarbon sonic). microseepage anomalies for broad reconnaisance This paper will present case histories where wireline surveys covering thousands of square kilometers to logs were partly or completely replaced by LWD, smaller surveys designed for individual exploratory and will include an economic justification for well ranking and evaluation. MOST has successfully wireline replacement. In addition, the paper will predicted commercial production prior to drilling in present LWD resistivity, density, neutron porosity, comprehensive wildcat well surveys. A new and sonic logs which operators judged acceptable production technology known as Microbial Reservoir for wireline log replacement. Characterization (MRC) integrates MOST with development geology and engineering data for an Dale R. Heysse is a LWD Global enhanced identification of subsurface reservoir Advisor for Halliburton at the fabrics. Where a reservoir is in communication with Houston Technology Center. He producing wells, microseepage is altered along has a BSc and MSc in Physics from pressure pathways streaming to production wells. Moorhead State University, In these cases, microseepage is essentially shut down Minnesota and Washington and lower concentrations of gases reach the surface University, Missouri, respectively. environment. Where the reservoir is not in In the past 13 years Dale has held communication with producing wells, microseepage various field engineering, field continues to escape to the surface. For mature operations, and interpretation reservoirs, MRC monitors subsurface fluid development positions in wireline logging and LWD. He withdrawal patterns at the surface by defining is a member of the SPE, SPWLA, and International MWD microseepage signatures which identify by-passed Society. production, reservoir heterogeneity characteristics, and potential offset well locations. Microbial Charles E. Jackson is a LWD microseepage targets the distribution of hydrocarbon Global Advisor for Halliburton at traps, maps the continuity (compartments) of a the Houston Technology Center. In reservoir, and locates areas prone to higher quality his position, he works on a wide reserves. variety of interpretation and petrophysical problems including Daniel C. Hitzman graduated environmental corrections for LWD with a BA in Geology from Carleton and wireline tools, formation College and founded Geo-Microbial evaluation, and new applications Technologies, Inc. (GMT) in 1985. for LWD services. Charles received Daniel coordinates GMT's a BSc in Electrical Engineering from the University of worldwide petroleum exploration Oklahoma in 1975. After graduation, he joined and production services, as well as Schlumberger Well Services, where he worked as a Field petroleum microbiology R&D Engineer and Log Analyst. In 1982, he joined Gearhart programs. He is also a member of Industries and went to work in the Interpretation the AAPG, SEPM, APGE, AEG, Development Group in 1984 where he worked with TGS, SPE and TMS. interpretation methods, and interpretation software. James D. Tucker is the Director of From Exploration to Development: Geosciences for Geo-Microbial Technologies, Inc. (GMT) since Microbial Surveys Target 1991. He previously worked for Hydrocarbon Microseepage various Mobil minerals and oil and gas groups. James holds a MSc in Hitzman, Daniel C.*, James D. Tucker Geochemistry from the Colorado and Brooks A. Rountree School of Mines. He is a member of Geo-Microbial Technologies, Inc., USA the APGE.

The measurement of hydrocarbon microseepage by Brooks A. Rountree is a Geologist microbial surveys targets exploration prospects and for Geo-Microbial Technologies, provides enhanced reservoir characterization. Light Inc. (GMT) since 1991 and has hydrocarbon gases migrate upward from buried worked for Sullivan and Company reservoirs reaching the shallow soil environment and Apache Corporation in Tulsa, along microseepage pathways. The light hydrocarbons Oklahoma. Brooks has a BSc in are utilized by specific suites of micro-organisms which Geology and Psychology from are very sensitive to the presence of hydrocarbon gases. Oklahoma State University. He is The Microbial Oil Survey Technique (MOST) was a member of TGS. developed to identify surface gas microseepage.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Robert J. Hooper has been with The Role of Structural Inversion Conoco in the capacity of Senior in the Development of Diapirs Research Scientist since 1991. His in the Southeast Arabian Gulf primary function is to serve as a consultant to worldwide exploration Hooper, Robert J.*, Ian R. Baron, groups on matters of structural Craig M. Murphy and Shaun Perkins geology, the interpretation of Conoco Inc., USA structures in seismic data, and regional tectonics. He is also Advances in seismic data-processing combined with involved in research into structural new insights into salt tectonics derived from scaled development in a wide variety of tectonic settings, and analog- and numerical-model studies and advances monitors several external research programs. Prior to in computer-aided restoration and visualization, joining Conoco, he was an Assistant Professor at the prompt a re-evaluation of the development of salt- University of South Florida between 1984 and 1991. He related structures in the southeast Arabian Gulf. In received a PhD in Geology from the University of South this paper we discuss a variety of salt-related Carolina in 1986. Robert is a member of GSA and The structures including low amplitude salt-rollers, salt Geological Society of London. walls, and surface piercements. We discuss the origins of the structures, and suggest, by comparison Ian R. Baron is the Regional with experimental data, that though physically very Coordinator for the Middle East different, the structures may have a common origin. Region with Conoco, Inc. Apart Understanding diapir development is a complex 4-D from a brief spell working in the problem because the mode of piercement can change North Sea and Australia, most of not only along trend but also through time. The cause his career has been spent working of the deformation can rarely be determined within on the Middle East and he has the bounds of a local survey area and needs to be worked with Conoco's Mideast viewed from a regional perspective. Widespread New Ventures Group since 1990. diapirism occurred throughout the southeast He obtained a BSc (Honors) in Arabian Gulf in the early Mesozoic. The tectonic Geology from the University of Manchester in 1977. Ian regime at that time was broadly extensional on the is a member of the AAPG and the Geological Society of trailing southern margin of Tethys. This tectonic London. regime changed fundamentally in the late Mesozoic and Tertiary. Data from the southeast Arabian Gulf Craig M. Murphy is a Geological reveal a major period of diapir growth in the late Advisor in Conoco's Advance Mesozoic during the deposition of the Mishrif and Exploration Group, where he is Ilam formations. This event corresponds in time to responsible for basin analysis and contractional events associated with the technical evaluation of new venture emplacement of the allochthons in Oman. A second opportunities. His primary area of major growth period occurred during the Oligo- study since 1991 has been the Miocene following the deposition of the Asmari Middle East. Craig received BSc Formation and corresponds to the Tertiary Zagros and MSc degrees in Geology from orogeny. Northern Illinois University and a We envisage a developmental history where diapiric MBA from Houston Baptist University. He is a member growth was initiated by thin-skinned brittle of the AAPG and SEG. extension during the Paleozoic/early Mesozoic. The salt diapirs represented weak points within the Shaun Perkins is a Geologist in sedimentary cover they intruded. Contractional Conoco's Advance Exploration deformation during the late Mesozoic/Tertiary was Group, based in Houston, where he preferentially partitioned into the diapirs, squeezing is responsible for basin analysis and the diapir-stems and adding "tectonic pressure" to technical evaluation of new venture the natural buoyant pressure within the diapirs. The opportunities. His recent work has net effect was rejuvenation of the diapirs. Salt-related largely focused on the Middle East structures in the southeast Arabian Gulf were not but he has also been involved in driven by salt movement but developed as a simple projects in Venezuela, Russia, and "reaction" to early thin-skinned extension and Southeast Asia. Shaun obtained a subsequent contraction of the overburden. BSc (Honors) from the University of Leicester in 1978. He is a member of the Geological Society of London and the AAPG.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Bitumen in Petroleum Reservoir Detection, Origin and Distribution

Huc, Alain-Yves* and Bernard Y. Carpentier Institut Français du Pétrole (IFP), France

Beside producible oil and gas, petroleum reservoirs prediction will be a function of the constraints often host bitumens. These bitumens, ranging from provided by the diagnosis of the specific type and highly viscous oil to solid organics, can affect the origin of the bitumen occurrences. whole reservoir or discrete intervals referred as "tar mats" (at Oil/Water contacts or within the oil leg and Alain-Yves Huc joined IFP in 1981 the water leg) and occur in many fields in the Middle and is currently head of Organic East. Such bitumen occurrences adversely alter Geochemistry. Alain was educated reservoir properties and can not be produced by at the University of Nancy, France, conventional means. They reduce the porosity/ and received his PhD in Organic permeability of the reservoir bodies, and can act as Geochemistry from the University of specific permeability barriers within the field inducing Strasbourg, France, in 1978. He compartmentalisation, early water cut or interference spent a year and a half as a with the water drive. As a result, the survey and postdoctoral fellow at Woods Hole prediction of bitumens in petroleum reservoirs is of Oceanographic Institution, USA, prime importance for exploration and production. and two years as a CNRS researcher at the Applied Geology The direct detection of bitumen in the reservoir relies Department of the University of Orléans, France. He is a on several available methods. These methods are member of the AAPG, EAOG, EAPG and ALAGO and based on electric logs and sample analysis has published more than 80 papers on geological and (geochemical extraction, Rock-Eval pyrolysis, geochemical subjects. petrophysical data base, microscopical examination, etc.). The pertinence of these methods depends on Bernard Y. Carpentier is a the type of bitumen and lithology. There is a wide Research Engineer at the IFP spectrum of situations controlling the occurrence of Geochemical Department since bitumen in reservoirs; these include thermally 1986 and is currently involved in immature oil, biodegradation, thermosulfate reduction reservoir geochemical studies. He (TSR), waterwashing, thermodynamic disequilibrium graduated form the Pierre and (P/T change, gas de-asphalting, gravitational Marie Curie University, Paris segregation), in-reservoir thermal cracking and where he studied geology and deposition along the migration avenues. Each of these geophysics. Bernard spent four phenomena will promote specific bitumen occurrences years as a Scientific Consultant in terms of quality and distribution. Assessing the with Gaz de France where he served in various fields: core distribution of bitumen accumulation within a field description, log analysis, field and basin synthesis. He requires extrapolation of well-based information to also spent one year with Triton France where he was in the reservoir scale. Such an exercise can be achieved charge of the Villeperdue oil field. He has published more using geostatistical techniques. The quality of the than 25 papers on source rocks sedimentology, evaporitic basin modeling and tar mats.

European Association of Geoscientists & Engineers EAGE 58th Conference and Technical Exhibition 3-7 June 1996

Amsterdam International Exhibition and Congress Centre

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Environmentally-Induced Biofacies Events Geochemistry of Ain El Hummar-2 in the Arab-D Reservoir of Crude Oils, Jordan Saudi Arabia Hughes, William B. Hughes, Geraint Wyn ARCO International Oil and Gas Company, USA Saudi Aramco Three medium gravity (23.3 to 31.1˚ API) and medium Micropaleontological analysis of thin-sections of sulfur (2.14 to 2.65%) crude oils from the Ain El Hummar- closely spaced core-plug samples from the Arab-D 2 well on the eastern shore of the Dead Sea, Jordan, were Formation of the Ain Dar, Shedgum and Uthmaniyah characterized by a variety of geochemical techniques. areas of the Ghawar Field, Saudi Arabia, has revealed Despite residing in shallow reservoirs (327 to 427 meters), an ordered vertical arrangement of microfaunal and a full suite of normal alkanes and high n-alkane/ microfloral events. These events monitor the isoprenoid ratios show the oils are not biodegraded. API response of the biofacies to the episodic changes in gravities and sulfur contents correlate with the ratio of sea level during the Late Jurassic. A fine-scale xylene to n-octane suggesting that water-washing, which biozonation has been attained, for which there is no would preferentially remove light aromatics, is responsible known published equivalent in the region. Events for the variations in gravity and sulfur content. The three are based on the semi-quantitative distribution oils are very similar in their carbon isotopic and biomarker (generic predominance facies) and biometric compositions indicating they are from the same source variations of the benthonic foraminiferal species and of the same thermal maturity. Trocholina spp., Pfenderina salernitana, Mangashtia Detailed GC and GC/MS analyses show the oils have viennoti, Nautiloculina oolithica, Kurnubia palastiniensis, low pristane/phytane, high dibenzothiophene/ Pseudocyclammina/Everticyclammina spp., Lenticulina phenanthrene, high norhopane/hopane, high C35- spp., polymorphinids and the calcareous algae homohopane/C34-homohopane and low diasterane/ Heteroporella jafferezzoi, Clypeina jurassica and sterane ratios indicating generation from a carbonate stromatoporoids including Cladocoropsis mirabilis. source rock containing a sulfur-rich kerogen. Other oils, Within local areas, and certainly between adjacent heavy oils and asphalts from the Dead Sea area are similar wells spaced at less than 10 kilometers, these in these same biomaker characteristics to the Ain El biozones may be considered to be geologically Hummar-2 oils. Comparison of the Ain El Hummar-2 isochronous events and therefore provide a unique oils to oils from the Wadi Sirhan and Hamza areas using tool to assist in correlating depositional layers. published data shows that oils from the three areas are Where these depositional layers coincide with from isotopically distinct source rocks. Age-specific reservoir layers, the scheme provides a more biomarkers (ratio of dinosteranes to the sum of all A-ring definitive tool for correlation than that provided by methylated C30 steranes) indicates the oils were derived wireline logs. The scheme needs careful use, from a source of Triassic or younger age. The ratio of C28/ β,β however, as local modification is likely wherever C29 steranes suggests the oils are derived from a Late progradation of facies is suspected, with the Cretaceous source rock. Several saturated biomarker consequent result that the scheme is probably indicators indicate a thermal maturity of the source rock diachronous over the region, and may not be used at the time of oil expulsion approximately equivalent to a to provide regional time-lines. vitrinite reflectance of 0.8%. The biomarker characteristics of the oils themselves as well as comparison with rock Geraint Wyn Hughes holds PhD, extract data from the literature indicates that the oils are MSc and BSc degrees from the derived from a marine marl/carbonate source, most likely University College of Wales, the Late Cretaceous (Senonian) Ghareb Formation Aberystwyth, and has been a although the Turonian Wadi Essir Formation cannot be Micropaleontologist/Stratigrapher eliminated as a possible minor contributor. with Saudi Aramco for the past 4 years. He has over 20 years William B. Hughes is Staff experience in stratigraphy, of which Geochemist with ARCO. He has 20 10 years were with the Solomon years of experience in geochemical Islands Geological Survey, and 10 research and the application of years of biostratigraphic consultancy of North Africa, the geochemistry to petroleum exploration Middle East, Australasia, the Americas and the North Sea of which 12 were with Phillips and 8 with Robertson Research in Singapore and the United with ARCO. William has published a Kingdom. He is a Fellow of the Cushman Foundation for number of papers on geochemical Foraminiferal Research, and a member of the British subjects. He has a B.A. degree in Micropaleontological Society and the Dhahran Geological Chemistry from Central Methodist Society. College and a PhD in Chemistry from MIT.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Silurian "Hot" Shale Labyrinths in the Middle East and North Africa

Ibrahim, Muhammad W. Target Exploration Consultants, UK

Paleo-environments and fairways of the Afro- Muhammad W. Ibrahim is Arabian Silurian "Hot" source rocks were interpreted currently Petroleum Geologist for by combining the frontier Silurian-Ordovician Europe, Africa and the Middle East geology of northern Arabia with the mature Silurian- with Target. He previously worked Ordovician play models of North Africa. Common for the Iraqi Geological Survey and lop-sided distribution of the early Silurian "Hot" Mineral Exploration, and as Shales in the glacially scarred Cambro-Ordovician Assistant Professor and Head of intracratonic basins invites paleo-environmental Department of Petroleum Geology, models other than the regional basin-wide euxinic King Abdul Aziz University, event. Regional correlations of the Silurian Shale Consultant Geologist with Kuwait across the political borders in the Sirhan-Risha- Institute for Scientific Research, Staff Geologist with Tabuk Basins of northern Arabia led to the Mobil Oil Libya, VEBA Oil, and Lasmo International. recognition of more than one Silurian "Hot" source Muhammad received his BSc in Geology from the rock. This has been suspected to occur in the cratonic University of Baghdad (1969), and MSc (1972) and PhD basins of North Africa but hitherto not published. (1978) in Petroleum Geology from Imperial College, Through this study new Silurian "Hot" source rock London. He is an active member of the Iraqi Geological trends (including those of the basal Silurian "Hot" Society, AAPG, SEPM, SPE, PESGP and COGS. He is Shale) were defined in areas in the Middle East and interested in the petroleum geology of the North Sea, North Africa. Middle East, Africa and the Gulf Coast of the US.

Development of the Multi-Disk Type Downhole Seismic Source

Ishii, Yoshiro* Japan National Oil Corporation, Bahrain Nobusuke Shimada Japan National Oil Corporation, Japan Takeichiro Ohashi and Yasunori Syoji OYO Corporation, Japan

The study of the multi-disk type downhole seismic Yoshiro Ishii is currently the source which is expected to be utilized for crosswell Assistant General Manager of and reverse VSP survey began in 1992. From the JNOC Middle East Representative experimental results, we have concluded that this Office in Bahrain. He received his seismic source is an effective non-explosive BSc from Tokai University and downhole seismic source. The principle of the joined JNOC in 1981. He had been mechanism is such that a hammer, accelerated by working for new project evaluation the force of a spring, collides with an anvil and and implementation of geophysical causes a pressure pulse to propagate throughout the surveys around the world borehole fluid among the disks. We have been able including Oman, Jordan and to prove its advantages of simple operation, good Myanmar. From 1992 to 1995 Yoshiro was Head of reproducibility and small power requirements. Reservoir Geophysics Group at the Technology Research Utilizing this concept, we have continued to improve Center (JNOC/TRC). His current responsibilities are not its efficiency and practicability. We have constructed limited to technologies but include all matters concerning models with larger disk diameters and multi-stories the Middle East. of multi-disks. The expected increase in performance was proven by a recent field test. It Nobusuke Shimada (see Yoshioka et al., p. 212) has an excitation energy of more than 3,000 Joules and the generated seismic wave, propagating through a layer of limestone, can be clearly observed over a distance of more than 600 meters. Considering the attenuation and noise level, an offset distance of more than 1,000 meters could be achieved by the latest model. (cont. p. 152)

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 (cont. from p. 151) Takeichiro Ohashi is currently Yasunori Shoji is currently an the Manager of the R&D Engineer in the R&D Department Department of Instrument of Instrument Division with OYO. Division, OYO. He has 10 years He has 5 years experience in the experience in geotechnical and research of rock mechanics and 7 geophysical research and 9 developing instruments for developing instruments. geotechnical surveys. He is a Takeichiro is a member of many member of SEG Japan, the Mining international associations and has and Materials Processing Institute published several papers on of Japan and the Japanese geophysical and geotechnical subjects. He received his Geotechnical Society. Yasunori holds BSc and MSc BSc in Physics from Saitama University and a MSc in degrees in Mining from Tohoku University. Applied Physics from the University of Electro- Communications.

The Depositional and Tectonic Setting of the Early Silurian Hydrocarbon Source Rock Facies of Central Saudi Arabia

Jones, Peter J.*, Thomas E. Stump and Mohammed I. Al-Khan Saudi Aramco The Early Silurian Qalibah Formation consists of two the organic matter resulting in less preservation of organic members: the upper member is termed the Sharawrah matter. and the lower is termed the Qusaiba. The latter member is the main hydrocarbon source rock facies for the known Peter J. Jones is a Laboratory Scientist Paleozoic hydrocarbon accumulations in Central Saudi at the Laboratory Research and Arabia. The Qusaiba Member is composed mostly of Development Center of Saudi Aramco. claystone/shale with minor interbeds of coarse siltstone He received his BA degree in Earth and sandstone. Depositionally, the Qusaiba Member is Sciences from Dartmouth College and interpreted to represent the pro-delta, delta toe clays, while a MSc in Geology from the University the Sharawrah Member was deposited as pro-delta of Oklahoma (1986). Before joining sandstones of an immense delta system that dominated Saudi Aramco in 1991, Peter worked the Silurian-Carboniferous of Arabia. The Qusaiba in exploration and production geology Member in central and south Arabia accumulated in a for Mustang Production, OKC (1982- trough that began subsiding during the Late Ordovician 1986) and Union Pacific, Ft. Worth (1986-1991). His current following the Taconic Uplift of central and southern areas of interest include basin-wide thermal maturity modeling, Arabia. In this trough at least 3,000 meters of Late hydrocarbon migration timing/path assessment, reservoir Ordovician through Early Devonian strata were geochemistry and variations in fluid properties, and petrophysical accumulated. This trough probably resulted from rifting log related issues. produced by the counter clockwise rotation of the Arabian Peninsula during the Late Paleozoic. Thomas E. Stump is a Geological The Qusaiba Member organic-rich facies occurs at the base Specialist with Saudi Aramco. Prior of the unit and has up to 8% total organic carbon content. to joining Saudi Aramco in 1990, he The development of favorable source rock facies in the worked with Unocal between 1980 and Qusaiba is observed along the peripheral edge and 1990 and with Amoco in the late 1970s. extending distally from the depositional thick associated Tom obtained his BSc in 1972 from San with the lower Qusaiba unit. The basal Qusaiba organic Diego State University and received his facies was produced in normally oxygenated bottom PhD from University of California water settings by elevated primary production in a Davis. He is particularly interested in sediment starved setting. The low level of bioturbation the regional geology of Africa, the in the organic facies suggests that while the water column Middle East and Far East. was normally oxygenated, the sediment below the sediment/water interface was anoxic. Geochemical data Mohammed I. Al-Khan is a show that the organic-rich Qusaiba shale closely associated Laboratory Scientist at the Laboratory with the depositional thick, exhibits characteristics Research and Development Center of consistent with a more oxidized sediment column, while Saudi Aramco. He received his BSc in those deposited more distally are more dis-oxic to anoxic Petroleum Geology from King in their characteristics. Apparently the depositional thick Abdulaziz University in 1988. His was produced under conditions which either re-worked current areas of interest include core organic-rich sediments, thereby oxidizing them, or diluted study, SEM, and geochemical evaluation of source rocks, tars and oils.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 A New Stratigraphic Model for the Structural Development of Khuff Formation in the Sub-surface of Jebel Abd Al Aziz, Syria Central and Eastern Arabia: Implications for Reservoir Geology Kent, W. Norman* and Robert G. Hickman UNOCAL, USA Kamal, Rami A.* and Geraint W. Hughes Saudi Aramco Jebel Abd Al Aziz, one of the most prominent topographic features in northeastern Syria, is a large The Khuff Formation carbonates and evaporites in surface anticline. Work done by UNOCAL, from the sub-surface of central and eastern Saudi Arabia 1988 to the present, outlines the following structural are a series of cyclic shallow marine and tidal flat evolution of this structure. Prior to the development carbonate and evaporite deposits which accumulated of the Abd Al Aziz structure, Senonian shelf aggradationally on a broad shelf in Late Permian carbonates prograded southward from Turkey into time. Within the Khuff Formation, carbonates can the Palmyride-Sinjar Trough which extended from develop three important natural-gas bearing west central to northeastern Syria. The shelf edge of reservoirs. A new stratigraphic model, rooted in the carbonate system was south of and subparallel sequence stratigraphy, has been created to be to the Syrian border. In the Abd Al Aziz area, fine- reservoir prediction friendly. Eustatic control was grained basinal mudstones were deposited on a thin, utilized in an attempt to better understand the transgressive, rudistid, bioclastic unit. In Early cyclicity of the intra-carbonate units and the Maastrichtian, an east-west trending graben alternation of evaporites and carbonates. The developed at the present site of Jebel Abd al Aziz. presence or absence of evaporites, dolomites or Structural blocks within the graben were bounded carbonates is considered to be related to catch-up and by reactivated northwest and northeast striking keep-up carbonate depositional regimes, which are in faults. Seismic data indicate that the edges of the direct response to different rates of sea level rise and rift basin were deeply eroded. Channels cut into the fall. Over the years, the Khuff Formation has sides of the basin along the trend of the older cross- developed a reputation for being a difficult formation cutting regional faults, exposed Carboniferous and for reservoir prediction. Recent studies have shown, possibly older strata. Olistostromes formed along however, that this is not the case. Lithostratigraphic the basin bounding fault scarps and turbidite fans intervals that are prone to reservoir development can developed at the channel mouths. Paleocurrent be recognized within predictable stratigraphic direction data from the turbidite sand bodies positions in the model, which in turn are discernible corresponds well with the trends of the channels on wire-line log traces and in rock core. The mapped on seismic data. lithostratigraphy of the Khuff Formation is also Maastrichtian age sediments are largely confined to simplified and standardized, in order to provide a new the graben proper. Early Tertiary sediments filled a practical and functional model for explorationists, wider basin, but there is evidence that minor episodic reservoir geologists, and reservoir engineers. inversion on some northeast and northwest trending Micropaleontological analysis of selected rock cores faults occurred during the Eocene and early Miocene. has also revealed important information on vertical However, the main inversion of the Abd Al Aziz and lateral variations with strong implications to structure occurred in the Late Pliocene and reservoir prediction. Micropaleontology has also Pleistocene. Inversion produced a large fault- enhanced the ability to identify second- and third- propagation fold above east-west trending faults near order depositional cycle breaks. the northern margin of the graben. Smaller folds developed above other graben-bounding faults and the Rami A. Kamal has been a Reservoir northeast and northwest striking faults within the graben Geologist with Saudi Aramco since underwent oblique slip during the deformation. 1984 and specializes in modeling carbonate reservoirs from Miocene to W. Norman Kent is a Senior Permian. Prior to Saudi Aramco, Rami Advising Geologist with UNOCAL worked in the drilling industry in Saudi Corporation in Sugar Land, Texas. Arabia. He received his MSc in Geology Before returning to the United States from King Fahd University of in January, 1995, he was Chief Petroleum and Minerals in 1973, a Geologist for UNOCAL, Syria, Ltd. MSc in Geology from Boston He has 20 years of experience as a University in 1977, and he will be completing his PhD in Geology petroleum exploration geologist. He from the University of London in 1996. Currently, Rami is the is a member of the AAPG, The President of the Dhahran Geological Society, and he is also a Geological Society, Geological member of the AAPG, Sigma Xi, SEPM, IAS and the NY Society of America, and Wyoming Geological Association. ACAD Sci. He has a BSc from the University of Arizona and a MSc from Northern Arizona University. Geraint W. Hughes (see Hughes, p. 150) (cont. p. 156)

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 (cont. from p. 154) Robert G. Hickman is currently Society of America and the International Association of Coordinator of Structural Geology Structural/Tectonic Geologists. He has a BSc from and Sequence Analysis with Stanford University and MSc and PhD degrees from the UNOCAL Corporation in Sugar University of Wisconsin. Land, Texas. He has 21 years of experience with petroleum research and exploration. Robert is a member of the AAPG, American Geophysical Union, Geological

Seismic-While-Drilling in Kuwait: Results and Applications

Khaled, Osman S., Alaa M. Al-Ateeqi Kuwait Oil Company Andrew R. James and Richard J. Meehan* Schlumberger Cambridge Research, UK

During early 1994, Kuwait Oil Company and Alaa M. Al-Ateeqi received his Schlumberger completed an extensive study of the BSc in Geology from Kuwait seismic-while-drilling (SWD) technique in the University in 1993 and joined KOC Raudhatain Field in north Kuwait. This in September of the same year. Alaa unconventional technique promises to provide real- worked as a Well Site Geologist for time well seismic information without interrupting one year and joined the Geophysics drilling and without deploying any downhole Division as a Trainee Geophysicist. hardware. However, to date, this service has been very seldom used in the Middle East. This paper begins with a discussion of the recent developments in the theory and mechanics of Andrew R. James is the resident measurement of drill vibrations for Vertical Seismic Country Manager for Schlumberger Profiling (VSP) and time-depth correlation. Concepts GeoQuest in Kuwait. He has of the SWD data acquisition and data processing seventeen years of oilfield sequence relating to two KOC wells will be experience starting as a Field developed and will lead to favorable comparisons Engineer with Schlumberger with both wireline VSP and surface seismic methods. Wireline and moving to staff The conclusion will be that the SWD technique can positions specializing in borehole work successfully in the Raudhatain Field. geophysics and acoustic operations. The relative merits of the SWD technique will be Andrew joined GeoQuest in 1994. presented in the context of the north Kuwait study He has a BSc (Honors) in Physics from the University of and with reference to future developments. Birmingham, UK and a Professional Degree in Geophysical Engineering from the Colorado School of Osman S. Khaled is Senior Mines, USA. Geophysicist with Kuwait Oil Company. He has twenty years of Richard J. Meehan is a Research geophysical and exploration Scientist with Schlumberger experience including 13 years in Cambridge Research. He has been KOC and 7 years with the Syrian with Schlumberger for 10 years, Petroleum Company. Osman during which time he has received his MSc in Geophysical conducted research into the Engineering from the Geophysical mechanical properties of shales, the Prospecting Institute, Russia. interpretation of drilling vibrations and most recently, the development of the drill bit seismic technique. Richard received his BSc in Engineering from the University of Strathclyde and a MSc in Engineering from Cranfield University.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Semi-arid Distal Alluvial Fan Deposits of Genetic Stratigraphy, Depositional Systems the Permian Unayzah Formation Along the and Reservoir Performance of the Nuayyim Trend, Central Saudi Arabia Burgan Formation, Greater Burgan Field

King, W. Allan Kirby, Robert H. Saudi Aramco Chevron Overseas Petroleum Technology Co., Kuwait and Jamal A. Al-Humoud* Significant reserves of Arabian super-light oil, Kuwait Oil Company, Kuwait condensate and gas occur within the Permian Unayzah Formation of central Saudi Arabia. The Sediments of the Middle Cretaceous Burgan Unayzah unconformity overlies Silurian sediments Formation form the principal oil producing reservoir and infill this variable topographic surface with in Kuwait's Greater Burgan field. The Burgan sands, clastics ranging in thickness from 60 to 850 feet. which were deposited in braided plain, deltaic and Sediment was sourced from highlands to the north shallow marine environments, attain a thickness of and west and transported to lowlands in the south approximately 1,150 feet in the field area. The and east. Magwa, Ahmadi and Burgan domes make-up the Three stages of deposition are recognized. The basal Greater Burgan structural complex. These Stage I is the infilling of a series of northwest- substructures exhibit an intricate pattern of faulting southeast oriented wadis with water-laid sands, that, in many cases, acts to compartmentalize the gravels and mud deposited predominantly by reservoir. gravity flows. The wadis were ultimately infilled as A chronostratigraphic zonation was developed for the highlands retreated and braided channels became the Burgan Formation to provide a comprehensive dominant. framework for correlating and mapping sedimentary Stage II sharply overlies Stage I, and the central strata. The strata components often have portion of the Nuayyim field is composed of fine- characteristic vertical stacking patterns, lateral grained lake-margin sediments that border thin playa continuity and bed geometry, and can be grouped lake deposits. These are replaced laterally in the into progradational, aggradational and retro- south and north of the Nuayyim field plus Abu gradational units. Recognizing these cycles and their Markhah field by extensive stacked aeolian dune associated depositional systems has provided insight sands and interdune silty sands. The wind-laid into fluid movement within the reservoir facies of interval can be up to 200 feet thick and consists of the formation. transverse-type dunes deposited by winds blowing Open hole logs, pulsed neutron logs and production towards the present-day east-northeast to east- performance data were used to interpret water southeast. encroachment patterns in the reservoir, which often Stage III sediments were deposited under a wetter vary due to changes in reservoir continuity and climatic regime. It began with fluvial channels and production procedures. Several areas in the reservoir overbank sediments that reworked the upper portion that exhibit vertical water rise or lateral water of the Stage II sediments. This fluvial sequence is encroachment (i.e. "water fingering") were identified, composed predominantly of overbank sheet sands and the extent of the water movement can be shown and fine-grained floodplain deposits, including field- to correspond to the stratigraphic architecture of the wide paleosols and lacustrine deposits. Burgan Formation. Reservoir quality within Stage I and the very-friable Stage II aeolian sediments is excellent (greater than Robert H. Kirby is a Reservoir 1 Darcy). The inter-dune, playa and lake-margin Geologist with Chevron Overseas sediments are predominantly non-reservoirs. Stage Petroleum Technology Company in III sediments only have good reservoir qualities Ahmadi, Kuwait. Over the past 19 within reworked Stage II sandstones and channel years Bob has worked for A.P. Green deposits. Refractories Co., Trans Ocean Oil, Gulf Oil Corporation, Chevron W. Allan King is currently an Geosciences, Arabian Chevron Exploration Geologist with Saudi (Saudi Aramco) and Chevron USA. Aramco. He has 15 years of He received a degree in Geology exploration and development from Georgia Southwestern College and is affiliated with experience, of which 7 years were the AAPG and SPE. with Home Oil Co. and four years with Novalta Resources, both of Jamal A. Al-Humoud has been with Kuwait Oil Calgary, Canada. He has been with Company since 1992. Jamal received a BSc in Geology Saudi Aramco since 1991. Allan from Kuwait University in 1990. He is affiliated with the has BSc and MSc degrees in AAPG. Geology from the University of Guelph, Ontario, Canada.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Anthony F. Palmer graduated Fluid Saturation Predictions in a from the University of Portsmouth "Transition Zone" in 1989 with a BEng (Hons) in Carbonate Reservoir, Abu Dhabi Engineering Geology and Geotechnics. He then completed an Kirkham, Anthony*, Mohamed Bin Juma MSc in Petroleum Engineering at Abu Dhabi Company for Offshore Oil Operations (ADCO) Imperial College, University of Anthony F. Palmer, Alan H. Thomas, London in 1990. Since joining BP Tilden A.M. McKean, Michael J. Smith Exploration in 1990 he has BP, United Kingdom experience in open-hole log and Bryan N. Twombley evaluation, special core analysis, production logging and Independent, United Kingdom well testing. He has worked on several large projects concerning Abu Dhabi Carbonate reservoirs for the last The field is a low amplitude structure with a chalky 3 years and he has also gained experience in physical Lower Cretaceous reservoir characterized by a large evaluation from various North Sea fields. hydrocarbon transition zone. Porosity generally decreases with depth within the trap although Alan H. Thomas has worked for porosity versus depth trends are skewed by tilting. British Petroleum since 1978 and Porosity and permeability mapping was therefore is currently employed as a Reservoir achieved using templates based on seismic Engineer. He has been involved in amplitudes. many reservoir studies and for the SCAL data were used to construct algorithms of past 6 years was mainly involved Leverett J functions versus saturation for a variety in the analysis of Middle East fields. of lithotypes mapped throughout the 3-D geological Alan holds a BSc in Mechanical model of the field. The templated poroperms were Engineering from the University of then combined with capillary pressures to predict Bristol and a MSc in Fluid fluid saturations from these algorithms. The Mechanics and Thermodynamics from City University, modeling of fluid distributions was therefore London. dependent upon heterogeneities imposed by the rock fabrics. Tilden A.M. McKean graduated Calibrating the model-predicted saturations against from Victoria University of log-derived saturations at the wells, involved Wellington, New Zealand in 1977 regression techniques which were complicated by: with a BSc in Geochemistry (Hon). notional structural tilting of the free water level, He has 16 years wide-ranging imbibition, hysteresis and permeability averaging experience in exploration and procedures. production. His past working Filtered "stick displays" proved useful in assessing experiences are Exploration the quality of the calibrations and were invaluable Review/Operations Geologist (4 tools for highlighting data anomalies. Laterally years), Petrophysicist (5 years), and variable correction factors, based upon "bubble Reservoir Engineer (7 years). He has reservoir engineering templates", were applied to ensure perfect experience in simulation and recent sub-surface field calibrations if desired. development responsibility for Qatar Genral Petroleum Corporation (QGPC). As Reservoir Engineering Manager Anthony Kirkham (see Al-Silwadi et al., p. 27) in BP's Abu Dhabi office, he manages BP studies for ADNOC and OPCO and is BP's member on ADCO/ Mohamed Bin Juma is Head of ADMA-OPCO RSSCs and TCMs. Reservoir Engineering in ADCO, Abu Dhabi. He has been working Michael J. Smith received a BSc for ADCO for the past 15 years as in Mathematics and Mathematical Drilling Engineer, Production Methods from RMCS, UK. He Engineer, Reservoir Engineer and joined BP in 1971 and is currently has held several Reservoir Exploitation Manager, Cusiana for Engineering Supervisory positions. BP Exploration Colombia. He has He holds a BSc in Petroleum worked in numerous operational Engineering from the University of centers for BP including Alaska, Tulsa (1981). North Sea and Abu Dhabi,UAE.

Bryan N. Twombley (see Al-Silwadi et al., p. 27)

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Abdulkader M. Al-Afifi has been Abqaiq Field 3-D Seismic Mapping of the with Saudi Aramco since 1991 Hanifa and Arab-D Reservoirs, where he is presently working on 3- Saudi Arabia D seismic interpretation. He holds a PhD in Geology from the Lawrence, Paul*, Abdulkader M. Al-Afifi, University of Michigan and is a Stephen T. Luthy and George A. Grover member of the AAPG and SPE. Saudi Aramco

The Abqaiq 3-D seismic survey was acquired to map major fracture zones within the Hanifa reservoir and Stephen T. Luthy received a BA in faults responsible for fluid communication between Geology from the University of the Hanifa and Arab-D reservoirs. The Hanifa California, Santa Barbara, and a reservoir is a Type 2 fractured reservoir containing a MSc from the University of stylolitic fracture system identified by high flow rates Montana. After 3 years with the over thin stratigraphic intervals, large disparities US Geological Survey, Steve between well test permeability (Kh) and core Kh, and worked for 4 years with Gulf Oil observations of fractures in vertical/horizontal cores. Corporation, followed by 10 years Interpretation of borehole image data, cross dipole with Chevron Oil Company. Since shear sonic logs, and observations from core suggest 1991, he has been with Saudi that Hanifa and Arab-D reservoir fluid communication Aramco, conducting studies of both the Arab-D and is locally controlled by throughgoing faults and Hanifa reservoirs at Abqaiq Field. associated fractures. The 3-D seismic data has confirmed the existence of George A. Grover (see Abu-Ali et al., p. 97) numerous faults and fracture zones, some of which are responsible for fluid communication between the A Case Study of Mapping Gas Cap two reservoirs. Faults and fracture zones are most readily identified in the Arab-D due to a sharp in a Carbonate Reservoir, acoustic impedance boundary at the top of the Using 3-D Seismic Data reservoir. Major faults were defined from reflector offsets while minor faults and fractures were defined Lee, Jia J., Constantine Tsingas*, from reflector amplitude, dip, and azimuth attributes. and Paul Lawrence Faults and fracture zones form a regional pattern Saudi Aramco generally consistent with anticlinal-domal uplift of the structure during the Late Cretaceous. This An integrated study has been conducted to map the pattern includes a radial system of faults and mobilized gas cap in a carbonate producing field of fractures mapped on the structural flanks and an the Arabian Peninsula, utilizing 3-D seismic data. axial parallel system on the structural crest. Well test Detection of reservoir fluids using any single analyses and reservoir simulation runs confirm the attribute in this field has been found difficult due to existence of a number of the 3-D seismically defined tight rock matrix and small changes of Poisson's ratio. faults and fractures. In this study, we attempted to delineate the boundary of a gas cap by examining attributes from zero-offset Paul Lawrence joined Saudi amplitude mapping, seismic modeling, AVO Aramco, in 1991 as a Geologist, analysis, traveltime anomaly and structural where he has been interpreting 3-D mapping. Due to the high-velocity rock matrix, the seismic data for reservoir oil/gas contact yields small AVO effects and characterization. Prior to joining amplitude signatures in the stacked 3-D seismic Saudi Aramco, Paul was employed volume. Seismic signatures of the reservoir were as a Geophysicist with Marathon found to have largely resulted from the combined Petroleum in Tunisia, Terra effects of porosity and gas accumulation. However, Resources in Denver, and Atlantic detailed traveltime anomalies mapped through the Richfield Co. in Dallas and Denver. field using isopach and isochron attributes were Paul received his BSc in Geology in 1976 from Kent State found useful for decoupling the contributions University and his MSc in Geology/Geophysics in 1978 between these two components. In this paper, from Wright State University. additional results from structurally mapping the depth-migrated seismic volume and other borehole data analyses will be shown to better constrain the lateral extension of the gas cap.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Jia J. Lee is currently a Geophysical Constantine Tsingas is currently Specialist with the Research and a Research Geophysicist with the Development Division in the Research and Development Geophysical Department of Saudi Division in the Geophysical Aramco. He is involved with Department of Saudi Aramco. He special seismic processing and has over 12 years of experience, 6 integrated studies of exploration years of which were in the USA and problems. Before joining Saudi Canada, and 6 in the Middle East. Aramco in 1992, he was with He has a BSc in Physics from the ARCO for nine years engaged in University of Athens, Greece, a seismic exploration and development on worldwide MSc in Geophysics from McGill University, and PhD prospects. He received his MSc in Geophysics from from the University of Alberta, Canada. He is a member Columbia University and a PhD from Penn State of the SEG and EAEG. University. Jia is a member of the SEG. Paul Lawrence (see Lawrence et al., p. 160)

Time to Depth Conversion: Relating Seismic Data to the Real Earth

Littman, Mark* and Alex Litvin Paradigm Geophysical Ltd., UK

This paper discusses the possibility of using stack seismic data thus allowing interpolation interpreted seismic arrivals along with interval between well points. The advantages and pitfalls of velocities (derived from pre-stack seismic data) for the direct use of these seismic velocities for time to time to depth conversion. depth conversion will be shown. The influence of Within the oil and gas industry today the standard anisotropy and shallow velocity variations on seismic work flow for time to depth conversion involves interval velocity analysis and methods of handling vertical stretching of time migrated interpretation these effects are discussed. In particular it will be into depth using the available well velocity demonstrated how a tomographic approach can be information. Pitfalls of such an approach will be used to update and improve static models. discussed using a number of real examples spanning from simple low relief plays to complex subsalt plays. Mark Littman graduated from The reliability of interpreting within the time Royal Holloway College, London migrated domain will be compared with that of with an MSc in Geophysics. He interpreting in depth, showing how lateral variations worked as Interpretation Geophysicist in interval velocity can create structures in time at NOPEC, UK for two and a half which do not exist in depth, as well as creating years before joining Paradigm structures in depth which cannot be seen in time. Geophysical where he has worked in The local velocity variations responsible for these the following roles: Support structures may lie in between available well Geophysicist, Service Manager and information and thus deciding whether structures presently as Pre-sales Support seen in time actually exist in depth is the key to any Manager. drilling project. In such cases pre-stack seismic data can be used in conjunction with well data to derive Alex Litvin graduated from velocities for time to depth conversion. Moscow State University, Russia In structurally complex areas it is often difficult to with a degree in Geophysics. His interpret in the time migrated domain due to the PhD thesis dealt with the modeling assumptions made by the time migration process. It and interpretation of refraction will be shown that in such areas depth migration seismics. Alex has more than 15 must be used in order to understand subsurface years experience in data processing, structure. interpretation and software The second part of this paper will look at the process development. of deriving interval velocity information from pre-

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Eliseo Rodriguez is the Manager Effect of Fault Planes on Breakout of the Interpretation and Geosciences and Drilling Induced Fracture Generation Group of Western Atlas Logging in Boreholes Services in Houston. Over the last 2 decades, he has held various Liu, Xingzhou, Saeed Rafie, Eliseo Rodriguez engineering and managerial Western Atlas Logging Services, USA positions in the logging industry and Joerg E. Mattner* and oil companies. Eliseo received Atlas Geoscience Services, Bahrain his MSc in Electro-mechanical Engineering from San Juan The in-situ stress field of a reservoir has a major University in Argentina. impact on hydrocarbon production. Detailed knowledge of the in-situ stress field can aid, for Joerg E. Mattner is currently the example, the effective placement of infill wells. In Chief Geologist and Manager of practice only regional in-situ stress data is taken into Western Atlas Geoscience Services consideration without including the effect of local in Bahrain. He has 12 years anomalies. These local in-situ stress anomalies are experience in large scale structural known to be caused by structural features such as and sedimentological mapping faults, and can be detected by the rotation of the projects e.g. in the Arctic regions of breakout trend and the attitude change of drilling North America, and the geological induced fractures along wellbores. This paper interpretation of wellbore data for discusses the use of finite element analysis (FEA) to reservoir characterization. Since calculate near wellbore stress in conjunction with 1991 he has been working with Western Atlas Logging regional stress anomalies. Results from the FEA are Services in the Middle East. Joerg holds a PhD from compared with analytical solutions from simple Clausthal University, Germany. models developed for earthquake mechanism studies. The study evaluates the effects of rock elastic Precambrian-Cambrian Basin Evolution properties, such as Young's modulus and Poisson's and Source Rock Development ratio, elastic anisotropy, bedding and fault attitude, borehole deviation, far-field stresses and boundary in South Oman conditions along the fault. The results are used to estimate the in-situ stress field, the rock mechanical Loosveld, Ramon J.H., Andy Bell* strength and their associated uncertainties. The and Peter J.R. Nederlof accuracy of the modeling is tested against field data Petroleum Development Oman from the Middle East. The formations of the Huqf Supergroup in Oman represent the oldest sedimentary rocks in Arabia. Xingzhou Liu is a Research They contain an alternation of clastic and carbonate Scientist with Western Atlas sequences with source rock intervals of varying Logging Services in Houston. His quality. The richness and distribution of these source current project assignments include rocks has been controlled to a large degree by the modeling of in-situ stress and rock tectonic framework of the Huqf basins. mechanical properties in the Initial rifting of the Arabian craton resulted in the borehole environment from well deposition of the lower Huqf in the northeast- logs and core data. From 1987 to southwest trending grabens. These basal sediments 1994, he worked for China's were deposited under glacial conditions and the sea aerospace industry and Amoco level rise resulting from final deglaciation led to Production Research. He has a BSc in Physics, a MSc in discontinuous source rock deposition. Geostatistics and a PhD in Geophysics from Stanford The absence of volcanics and coarse-grained clastics University. in the middle Huqf is indicative of tectonic quiescence during the subsequent thermal relaxation/ Saeed Rafie is a Staff Engineer at subsidence period. A series of carbonate platforms the Mechanical Engineering were deposited, generally with a low average organic Department of Western Atlas carbon content. The source rocks of the middle Huqf Logging Services in Houston. He are laterally extensive and thicker than the lower is responsible for failure and stress Huqf source rocks. analysis, finite element analysis and Renewed rifting in the upper Huqf resulted in the its applications in engineering formation of salt basins parallel to the pre-existing projects. Saeed received his PhD in lower Huqf grabens. These rifts filled with thick Engineering Mechanics from evaporite and source rock sequences. The source Pennsylvania State University, rocks are of exceptional quality and thickness, USA.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 reflecting deposition in a stable euxinic environment. It was a prerequisite to optimize the exploration effort As salt deposition ceased, east-west shortening of the by adopting and implementing modern and Huqf sequence in the southwestern part of south advanced techniques in seismic data acquisition and Oman occurred. Uplift associated with this processing (high resolution 2-D and 3-D), drilling, deformation may have provided clastics for the lower mud logging and gas detection, electric logging, Haima. The Angudan Unconformity marks the end integrated geologic analyses and modeling. Besides of this tectonic event. the intensive use of computer software applications, all had made it possible to discover, to date, Ramon J.H. Loosveld (see Loosveld et al., p. 51) additional 45 new oil and gas fields, ranging in size between giants and small discoveries. In addition Andy Bell (see Loosveld et al., p. 51) to disclosing new oil and gas reservoirs within the old fields, all had added considerable amount of Peter J.R. Nederlof is Team reserves to the State. Leader, Regional Studies in In addition to advances in surface seismic, there were Petroleum Development Oman. also advancements in borehole data acquisition that Before joining PDO in 1992, he was played a critical role in the search for hydrocarbon. employed as a Petroleum These advances include: (1) imaging, that provided Geochemist by Shell Canada in a 3-D aspect to borehole logging; (2) high vertical Calgary and Shell Research in The resolution, that provided better definition of thinner Netherlands. Peter's main interests reservoir layers (in order of 1 foot); and (3) downhole lay in the fields of reservoir sampling and testing that improved reservoir geochemistry and hydrocarbon evaluation and obtaining fast estimate of habitat studies. Peter obtained his MSc and PhD in hydrocarbon potential. Chemistry in 1973 and 1978, respectively, from the Geologic and geophysical review and studies of the University of Amsterdam. He did a Post Doctorate at huge technical data acquired during the last 45 years, Stanford University in 1979. Peter is an active member had enabled explorationists in Abu Dhabi to well of the AAPG and the American Chemical Society and has recognize diversified problems which are currently been a member of the board of the European Association being tackled with the hope to achieve better of Organic Geochemists since 1991. Peter is a member of assessment of the hydrocarbon potential of the the Editorial Advisory Board of GeoArabia. remaining unexplored areas in the country. In this paper, the latest play concepts and modern An Overview of Recent Hydrocarbon exploration techniques adopted during the last 20 years to help define new hydrocarbon accumulations, Exploration Activities, Achievements and in addition to problems tackled with examples for Future Challenges in Abu Dhabi, U.A.E. each, are briefly presented and discussed. Additionally, an overview of the challenges and Loutfi, Galal potential technical problems to be encountered in the Abu Dhabi National Oil Company (ADNOC) future are made. The level of expertise and the range of modern wealth of data to achieve our goals and The first discoveries in Abu Dhabi, up to the early fulfill this task are also analyzed and discussed. 1970s, focused on the giant structures with their large hydrocarbon potential. A total of 25 fields, onshore Galal Loutfi is Superintendent of and offshore Abu Dhabi, were discovered which Exploration Geology with the Abu included the supergiants of Bab, Bu Hasa, Asab on Dhabi National Oil Company land and Zakum and Umm Shaif offshore. The (ADNOC) since 1975. He received emphasis thereafter was on developing this large his BSc in Geology and Chemistry hydrocarbon potential. in 1959 from Cairo University and By the mid-seventies, and following the MSc in Petroleum Geology in 1965 establishment of ADNOC which acquired 60% of the from Ain Shams University, Egypt. assets of the major oil concessionaires in the country, He has also received an additional in addition to concession areas, which were MSc in 1971 on Carbonate relinquished by ex-concessionaires, covering about Sedimentology in Kuwait. Galal has over 36 years 30% of the total area of Abu Dhabi, reactivation of experience as a Petroleum Geologist with oil companies the exploration efforts were adopted and in the Middle East (Egypt, Syria, Kuwait, Kuwait-Saudi implemented. The challenge was that available Arabia Neutral Zone and the United Arab Emirates) criteria indicated that the remaining potential oil and mainly in evaluation of hydrocarbon potential and play gas accumulations were in relatively small, shallow- concepts of frontier/under-explored areas, planning, relief and subtle traps. This was a different task directing and monitoring exploration programs. He is an altogether, and far removed from the early active member of the AAPG, SEE and EGS. exploration days in Abu Dhabi.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Karen M. Love has been a Predicting Reservoir Quality Using Geologist with Exxon Production Integrated Geological and Statistical Research Company in Houston, Models: Examples from Carbonate and Texas for four years. She has worked Siliciclastic Reservoirs in carbonate and siliciclastic reservoir quality, and has published papers on a variety of topics, Love, Karen M.* including carbonate diagenesis, Exxon Production Research Company, USA reservoir quality prediction and Christian J. Strohmenger, Konrad Rockenbauch statistics. She holds a BSc in Beb Erdgas und Erdöl GmbH, Germany and Alex Woronow Geology from the University of Oklahoma, and a MSc University of Houston, USA and PhD in Geology from the University of Houston.

A unique method for predicting the three- Christian J. Strohmenger joined dimensional distribution of reservoir attributes has BEB Erdgas und Erdoel GmbH in been developed that integrates geological and 1990 and is currently working as a statistical models. The integrated method, applicable team Geologist/Seismic Interpreter to carbonate and siliciclastic reservoirs, has been in the gas exploration and successfully applied to the prediction of the development department. From distribution of dolomite, calcitized dolomite, 1989 to 1990 he worked as a porosity, and permeability in a carbonate reservoir Research Assistant in carbonate and to the distribution of halite cement in a sedimentology and sequence siliciclastic reservoir. stratigraphy at the University of The Permian Zechstein 2 Carbonate of northern Geneva, Switzerland. He holds a diploma in Geology from Germany provides an example where the the University of Giessen, and a PhD in Mineralogy/ methodology has been successfully applied. In this Sedimentology from the University of Heidelberg, reservoir, mineralogy serves as a strong control on Germany. reservoir quality because dolomites are generally porous whereas calcitized dolomites (dedolomites) Konrad Rockenbauch is are generally non-porous. First, multivariate linear Geological Technical Expert with regression models were used to help develop a BEB Erdgas and Erdoel GmbH in geologic model explaining the calcitization of the Hannover, Germany. He has 3 dolomite and the resulting calcite distribution. This years of university research practice model suggested that paleo-faults controlled the and 11 years of petroleum and distribution of calcite. Although the geologic model exploration industry experience. elucidated the cause-and-effect relationship With BEB, he was involved in the regarding the mineralogy distribution, it was development of oil and sour gas ineffectual in predicting the distribution of fields and in research application mineralogy because the distribution of paleo-faults projects. Konrad has published several papers on was unknown. For this reason, location variables structural and reservoir quality subjects. He holds a MSc (latitude, longitude, and depth) were used as proxies and PhD from the University of Stuttgart, Germany. for the unattainable paleo-fault information. Linear regression modeling using the location variables Alex Woronow is an Associate along with facies and general structural style Professor of Geology at the provided the best predictions of mineralogy. In University of Houston. He has addition to predicting mineralogy, models were more than 20 years of experience in generated to directly predict porosity and computer, statistical, and artificial- permeability. Because the spatial distributions of intelligence applications to the porosity and permeability are typically complex, a geosciences and holds membership nonparametric predictive technique (neural in both geological and statistical network) was implemented, producing more reliable societies. Alex has more than 50 models than linear regression. These predictive publications in international models were used to generate maps, cross-sections, journals and has more than 70 published abstracts. His and three-dimensional representations of degrees are an AB in Astronomy from the University of mineralogy, porosity, and permeability throughout California, a MSc in Geology from the University of the reservoir. Houston, and a PhD in Geology from Harvard University.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Seismic Modeling of Shallow Gas Anomalies in the Yibal Field, Oman

MacDonald, Calum Petroleum Development Oman (PDO)

The 1993 Yibal field 3-D survey showed a brightening saturation. In the most porous sections, the density of shallow reflection events within the Umm Er at 100% gas saturation is 0.2 gram per cubic Radhuma (UER) limestone sequence and at the centimeter lower than at 0% saturation. When interfaces with the overlying Rus (dolomite and combined with the velocity change, the resulting anhydrite) and underlying Fiqa shale formations. impedance variations show that gas in the UER will Amplitude maps show the large amplitudes to be give 50% to 100% increases in reflection amplitude. concentrated in the highly faulted crestal zone and Where amplitude anomalies correlate with pull the effect may indicate that gas has leaked along downs we have a strong indication of regions where faults from the Natih A Formation and filled the UER gas has leaked up into the UER. Formation. Where the UER has been filled with gas it poses a significant drilling risk and it may cause Calum MacDonald received a premature casing corosion in existing wells. BSc in Geophysics from Edinburgh A modeling study was initiated to evaluate the effect University and a MSc and PhD in of gas on reflection amplitudes at UER levels. Geophysics from the University of Gassmann replacement indicates that the velocity in California, Los Angeles. After the UER Formation is very sensitive to gas saturation. several years at the Geophysical Even 1% gas saturation causes a velocity decrease of Institute, University of Karlsruhe, up to 500 meters per second (m/s). At 10% gas he joined Shell Research in 1989 saturation the velocity has decreased by as much as and worked at the E&P Lab in The 900 m/s from the initial value (a 20% decrease). Such Netherlands. Since 1993 Calum large velocity reductions give rise to significant pull has been working with PDO's Quantitative Interpretation down effects - more than 30 milliseconds at 10% gas Group.

An Innovative Technique Resolves Apparent Anomalies in Detection of Gas Zones Based on Density-Neutron Logs

Mallick, Ravi K.*, Biswajit Choudhury Oil India Limited, India and Pradeep Vishunavat Schlumberger-Geoquest, India

Cross-over effect on Density-Neutron logs has been percentage of silt in the reservoirs approaches a one of the most accepted techniques in the oil certain upper limit no cross-over may be seen against industry for identification of gas-bearing sands. gas- bearing sands on the Density-Neutron log. An However, two contrary situations have been equation has been developed to correct the encountered where the inference on the presence of magnitude of Density-Neutron cross-over for the gas based on Density-Neutron cross-over can be presence of silt before inferring the presence of gas. misleading. Many formations which do not exhibit On the other hand, false gas effects can be seen on significant or any Density-Neutron cross-over the Density-Neutron log if the reservoir matrix subsequently produced gas on testing while many density is considerably lower than the clean sand other formations which exhibit appreciable Density- matrix density. In these cases, the matrix density Neutron cross-over have been proved to be oil- needs to be determined from integration of cross- bearing. plots and laboratory measurements and a modified This paper discusses the reasons for these anomalies compatible scale needs to be fixed on the Density- and concludes that quicklook interpretation of gas Neutron log for locating gas zones. This paper from cross-over effect on Density-Neutron log on a illustrates these points by means of field case compatible scale is restricted to clean sandstone examples from wells of two newly discovered oil formations. It further concludes that when the fields in Upper Assam, India.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Ravi K. Mallick is a Biswajit Choudhury is a Superintending Geologist with Oil Superintending Reservoir India Limited based at its field head Engineer with Oil India Limited. quarters, Assam, India. In his 14- He obtained his BSc and MSc year career with the company, he degrees in Petroleum Engineering has held various positions in the from the Indian School of Mines, fields of petroleum exploration and Dhanbad, India. Biswajit has been development. Ravi's fields of associated with Oil India Limited specialization include formation since 1984 and has worked in evaluation and application of well diverse areas of reservoir log data to various aspects of petroleum geological studies. engineering including reservoir simulation, well testing, He obtained his MSc in Applied Geology from the Indian open and cased hole log interpretation and development Institute of Technology, Kharagpur. Ravi is author of a of gas fields. number of international publications, and is a member of the Society of Professional Well Log Analysts and the Pradeep Vishunavat received his International MWD Society. MSc in Applied Geology from Roorkee University, India in 1988. He joined Schlumberger Asia Services in 1989 and is currently working as a Log Analyst in Bombay. Pradeep is a member of the Society of Professional Well Log Analysts.

Reservoir Filling is Controlled by Petroleum Expulsion - What Controls Petroleum Expulsion?

Mann, Ulrich Institute for Petroleum and Organic Geochemistry, Germany

The rate of reservoir filling is controlled by the petrophysical measurements; (3) determination of velocity of the advancing petroleum front during expulsion stage, of expulsion process, and of expulsion secondary migration. This velocity is controlled by efficiency by organic-geochemical analyses; and (4) the oil saturation of the carrier rock; hence, reservoir reconstruction of migration processes within the filling is largely controlled by source rock release geologic framework by numerical modeling. rates. However, there are several petroleum expulsion Ulrich Mann has more than 15 mechanisms, and the pathways and efficiencies of years experience as Coordinator of individual mechanisms vary from case history to Petroleum Geochemistry Analytical case history due to the variable abundance of Services at the Research Center, macropores and fractures in source rocks as well as Jülich, Germany. He is author of different mechanisms for the build-up of a pressure about 100 petroleum geochemistry gradient. reports for oil companies world- In order to collect information about petroleum wide, and he has published more expulsion that is as complete as possible, the than 40 papers on sedimentological, investigation of primary petroleum migration petrophysical and organic- requires a correct integration of all information. The geochemical subjects. Ulrich gained his PhD as a volume of information and its relative importance will Sedimentologist from the University of Heidelberg, vary from case to case, but four specific tasks will Germany. He is an AAPG certified Geologist, a member always represent key elements for the quantification of the ACS, ALAGO, EAPG, SEPM, member of Executive of petroleum expulsion: (1) identification of migration Board of the GV, and a lecturer at the University of pathways by applying the principles of sedimentary Erlangen-Nürnberg, Germany. His current research petrography; (2) evaluation of transport-related interest is a multi-disciplinary approach to petroleum properties of rocks from migration pathways by migration.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Forecasting Undefined Prospectivity The History and Geology of the in Oman Safah Oil Field, Sultanate of Oman

McCoss, Angus M. McGann, Gerard J.*, Michael N. Cleveland Petroleum Development Oman and Hsiu Kuo chen Occidental of Oman, Oman Two parallel approaches are used to constrain the undefined potential of the exploration portfolio of The Safah field is the most northerly onshore oil field Petroleum Development Oman. One is statistical and in Oman and was discovered in 1983. Located on the the other is geological. Lekhwair Arch, the field is dip closed to the west The statistical approach is based on the observation and east, with northern dip closure into the foreland that prospects, like faults, often have fractal or self- basin. Critical updip trapping to the south is similar geometries, which when sorted have power stratigraphic, with reservoir degradation from shelf law distributions. Using this technique, a population carbonates to deeper water shales and marls. of prospect volumes is sorted by size and a power Production is from the Lower Cretaceous Shu'aiba law fit is made through the largest, and extrapolated Formation, a predominantly shelfal carbonate with into the smaller volumes. This conservatively isolated areas of rudist biohermal accumulations. assumes that the largest volumes have been Reservoir quality is generally poor to moderate, with identified, and that the undefined portion of the play average permeability of five millidarcies. Vertical lies in smaller prospects, below the current seal is the overlying Nahr Umr shale. A gas cap is exploration resolution (a function of seismic and well present in the eastern part of the field, with at least spacing, and the current status of geological two separate gas-oil contacts. intuition). The significant stratigraphic component of the trap The geological approach is the more traditional. It disguised the real size of the accumulation for a utilizes the knowledge and skills of teams of number of years. The first three wells were drilled geologists and seismic interpreters, through on an apparent structural closure, and only when the interviews, to arrive at estimates of the undefined hydrocarbon column was greater than the mapped potential. Various type-prospects are identified in a closure was a stratigraphic component recognized. given play, and a discussion develops as to how The small size of the field dictated the installation of many more of them there could be in a given domain. "second hand", short-term production facilities for a Although a less objective and less auditable method, number of years. With increased drilling, the true it utilizes very many more dimensions of reasoning size of the field became apparent, and daily than the cold statistical approach. production has increased every year since discovery, However, the true power of the two approaches with average production in 1994 of 33,000 barrels of comes when they are combined and reconciled. A oil per day. The history of this change of perception balanced population of geo-statistically risked is discussed with full field statistics. Initial oil in place volumes can then be assigned to the undefined is about 750 million barrels with cumulative oil portion of a given play. production of about 70 million barrels. The changes in development philosophy of the field Angus M. McCoss is currently a are discussed with particular emphasis on the gas Senior Geologist with Petroleum re-injection program, and horizontal open hole Development Oman based in completions. Some aspects of geophysics and Muscat. He has nine years of production geology are discussed. exploration industry experience and has been employed in Shell's central Gerard J. McGann is currently office and research laboratory in The Exploration Manager with Hague, and with Shell China Ltd. Occidental in Muscat. He has 25 in Beijing before assuming his years of petroleum and exploration responsibilities in Oman. He has experience and has worked in more published several papers on structural geology and has a than 10 countries, from Japan to BSc in Geology from the University of Dundee and a PhD, Pakistan. He is a member of many sponsored by BP, in Structural Geology from the Queen's international societies including University of Belfast. AAPG, SPE and SPWLA, where he is past President of three chapters and on the editorial board. He has a BSc (Honors) from the University of Western Australia.

Michael N. Cleveland and Hsiu Kuo Chen (see Cleveland et al., p. 125)

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 he returned to Scotland in 1991 to establish IAS. Euan is Correlation and Connectivity of Carbonate a member of The Geological Society and Petroleum Reservoirs Based on Strontium Isotopes: Exploration Society of Great Britain. A Case Study of the Sidi El Kilani Chalk Field, Tunisia Mark G. Bramwell is currently Senior Geologist with the Kuwait Mearns, Euan W.* Foreign Petroleum Exploration Isotopic Analytical Services Ltd., Scotland Company (KUFPEC) in Kuwait. Mark G. Bramwell He has 10 years development and KUFPEC, Kuwait exploration experience of which 5 and John J. McBride were with Shell (UK) in London IAS Ltd., Scotland and Aberdeen, and 2 as an independent consultant. He Oil is produced primarily from open fracture received his BSc (Honors) and PhD porosity in Upper Cretaceous chalk in the Sidi El in Geology from Queen's University, Belfast. Mark is a Kilani oil field. One of the challenges in developing member of several professional societies. this field has been understanding the distribution of open fractures within the structure. Strontium John J. McBride is Senior Isotope isotope analysis (87Sr/86Sr) is one of several Geochemist with IAS Ltd., techniques that has been applied to this problem. Aberdeen working on the Strontium stratigraphy analyses of primary, applications of isotope techniques to unaltered matrix chalk has allowed chrono- reservoir correlation, connectivity, stratigraphic dating of the reservoir with a resolution stratigraphy and diagenesis. He of ± 1 million years. This has facilitated correlation received his BSc in Geology from of the reservoir, allowed estimates to be made of Edinburgh University in 1985 and depositional rates and has indicated where section a PhD in Diagenesis from Aberdeen is missing due to faulting. University in 1992. Prior to Isotopic analyses (87Sr/86Sr, δ18O, δ13C) of fracture- joining IAS in 1992, he worked on reservoir diagenesis with SPT and the Geochem Group. fill authigenic carbonate cements has confirmed the presence of at least two generations of cemented fractures. An early generation of calcite cement may The Upper Cretaceous Sedimentary

have formed by redistribution of CaCO3 from the Environments and Oil Leads of Central chalk at relatively low temperatures in the region of Saharan Atlas and the Hodna 35 to 55˚centigrade (C). A later generation of dolomite and barite cements have Sr-O-C isotope Merabet, Souhir*, Hamza Tourqui composition consistent with their precipitation from and Fadhila Braik fluids circulating at the time of hydrocarbon charge Sonatrach Exploration, Algeria at temperatures close to current reservoir conditions of 70 to 75˚C. The study area (which includes two distinct Strontium isotope analyses of residual salts extracted geomorphological groups: the Hodna Basin and the from core provide information on the formation central Saharan Atlas) is located in the northern part water chemistry and on reservoir connectivity at the of Algeria. It is bounded northward by the Tell Range time of oil filling. These data have been used to and the Saharan Platform in the south. clarify both vertical and lateral connectivity in the The Cenomanian is constituted, in the central Sidi El Kilani field. A link between dolomite/barite Saharan Atlas, by an anhydritic facies in the south cementation and waters circulating in the reservoir which is related to the lagoonal environment, and a at the time of hydrocarbon charge has also been marly-calcareous facies related to the supratidal to confirmed. Prediction of the distribution of dolomite intertidal conditions. It is represented northward in cemented fractures has thus helped guide the the Hodna Basin by benthic foraminifers limestones development strategy of the field. which correspond to the subtidal domain, and bio- constructions and finally with Globigerines marls of Euan W. Mearns is the founder the open marine area. and Managing Director of Isotopic The same sedimentary process has been repeated Analytical Services Ltd. (IAS) in during the Turonian and Senonian therefore with a Aberdeen. He received a BSc in more extensive supratidal to lagoonal domain in the Geology in 1979 and a PhD in Saharan Atlas. A paleogeographical evolution is Isotope Geochemistry in 1984 from displayed with euxinic deposits in the south and an the University of Aberdeen. open marine in the north. Following 6 years at the University Considering the facies distribution, the main of Oslo, and 2 years at IFE, Norway, reservoir objectives are the Upper Albian-Vraconian,

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 the Upper Cenomanian and the Middle to Upper Turonian. The main caprocks are represented by marls of Cenomanian age and Campanian shales. The zone of interest for oil exploration is located in the Hodna (the region of Sidi-Aissa) and the south- Hamza Tourqui graduated from east area (Barika district). Algiers University. He has 14 years exploration experience and is currently a Senior Research Geologist on sedimentary basins.

Souhir Merabet is a graduate of Algiers University. She is an Engineer Sedimentologist and has been working for Sonatrach Fadhila Braik graduated from Exploration since 1991. Algiers University. She has 12 years exploration experience. She is currently a Senior Research Geologist on sedimentary basins.

Outcropping Strata Equivalent to Arab-D Reservoir, Wadi Nisah, Saudi Arabia

Meyer, Franz O.*, Rex C. Price, Ibrahim A. Al-Ghamdi, Ibrahim M. Al-Goba, Saleh M. Al-Raimi and John C. Cole Saudi Aramco

Two short outcropping sections in Wadi Nisah of relationships and potential fluid-flow pathways. This central Saudi Arabia expose sedimentary successions study demonstrates that outcropping cycles and their of the Jubaila and Arab formations which are lithofacies components have several important stratigraphic equivalents to the Arab-D reservoir implications for ongoing subsurface reservoir rocks of Ghawar field. Additionally, these carbonate characterization and modeling of the Arab-D. exposures consist of lithofacies and stacking patterns Firstly, cycle definition forms envelopes for the similar to the succession found in Arab-D reservoir interwell distribution of lithofacies. Secondly, the strata. Outcropping sections are punctuated by lithofacies define geometries for the interwell disconformities that subdivide the stratigraphic distribution of petrophysical characteristics. Thirdly, succession into three depositional cycle types: (1) the understanding of lateral relationships of these stromatoporoid, (2) skeletal bank, and (3) thinning carbonates aid in reservoir simulation modeling. upward and laminated mud. Depositional cycle types can be repetitive and define five successive Franz O. Meyer is currently a Staff sedimentary episodes within the outcrop. Geologist with Saudi Aramco. He The lateral distribution of lithofacies within these has 17 years experience in cycles show that capping stromatoporoid grainstones exploration and production of form organic buildups that locally exhibit thickness carbonate reservoirs. His experience increases of more than 50 percent of the cycle includes a 13 years with Shell, thickness over a horizontal distance of 500 meters. USA, during which he spent the Conversely, the capping five foot-thick skeletal last 7 teaching applied carbonate grainstone of the skeletal bank cycle forms a geology. As a member of numerous continuous sheet exceeding 2 kilometers in width. professional societies, Franz published Other carbonate sand units that are thinly bedded on a diverse range of topics that include stratigraphy, petrography, exhibit pronounced lateral discontinuity over paleontology, and reef ecology. He has a BSc in Geology from distances of less than a hundred meters. SUNY College at New Paltz, and holds MSc and PhD degrees Results of the outcropping stratigraphic analysis enable in Paleontology from the University of Michigan. visualization of lateral and vertical stratigraphic (cont. p. 172)

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 (cont. from p. 171) Rex C. Price is currently a Staff Ibrahim M. Al-Goba is a graduate Geologist on loan from Chevron to of Petroleum Geology from King Saudi Aramco. He has university Abdul Aziz University in 1988. He teaching experience and has spent worked with Southern Area the last 14 years in the oil industry. Reservoir Geology for 1 year, and Rex has worked in research, with the wellsite unit for 2 years. exploration, production, and Since 1991, he has been working on geophysics. As a member of the Ain Dar Field. numerous professional societies, he has published on stratigraphic, paleontologic and petrographic topics. He has BSc and MSc degrees in Geology from the University of Alabama, Saleh M. Al-Raimi is a Carbonate and holds a PhD in Geology from the University of Iowa. Sedimentologist with Southern Area Reservoir Geology since 1992. Ibrahim A. Al-Ghamdi is an He joined Saudi Aramco in 1980 Exploration Geologist working with and since then has worked in the Exploration Organization in wellsite, hydrology, exploration and Saudi Aramco since 1985. He has reservoir geology. Saleh obtained worked in area exploration, his BSc in 1980 from King Abdul- reservoir geology and wellsite, and Aziz University. Saleh is a member in special projects including of the AAPG, SPE and Dhahran reservoir modeling with Exxon in Geological Society. His interests are reservoir 1989. Most of his work concentrated characterization, modeling and computer geology. on carbonates of the Jurassic and the Cretaceous of Saudi Arabia. Ibrahim is interested in carbonates, sequence stratigraphy, artificial intelligence, geostatistics and field geology.

A Multi-disciplinary Approach to Evaluate the Continuity of Complex Carbonate Reservoirs: Example from Onshore Abu Dhabi

Mohammed, Awad A.*, Salah E. El-Shazly, and Neil Young Abu Dhabi Company for Onshore Oil Operations (ADCO)

The "S" field produces oil from multiple Lower sealing nature indicated by other techniques. Cretaceous reservoirs separated by dense limestone However, log and stress analyses indicate the seal intervals. The field anticline structure is dissected effectiveness of at least one fault zone in the south, by many short sub-vertical normal faults and and confirm the results indicated by the pressure subordinate wrench faults. The multi-stacked data, strontium isotopes and the molecular reservoirs show a great deal of heterogeneity in composition of the hydrocarbons. reservoir quality and facies thickness which affects vertical and lateral continuity. Awad A. Mohammed is a Staff Strontium isotopes ratios of residual salts analyses Geologist with Abu Dhabi Company indicate appreciable differences between the for Onshore Oil Operations southern and the central parts of the field with a (ADCO). Prior to joining ADCO slight increase towards the north. Vertically, the in 1991, Mohammed was with UAE consistent profile that increases slightly with depth University and with the Chevron attests to the gradual filling of the reservoir with companies from 1979 to 1989. He hydrocarbons without any significant interruptions. has a BSc (Honors) in Geology from Similarly, the long-range gas chromatography Sudan and received his MSc and (Carbon 34+) and the pressure data analyses indicate DIC in Petroleum Geology from vertical continuity in the reservoirs but with sharp Imperial College, London in 1983. Mohammed is a former lateral discontinuity in the southern part of the field. Assistant Secretary of the Society of Explorationists in A gradual change in the various characteristics the Emirates (SEE) and is a member of the AAPG. toward the north indicates the presence of a semi- barrier due to deterioration in the reservoir quality Salah E. El-Shazly and Neil Young and the incurred capillary pressure differentials. (see El-Shazly et al., p. 135) Initially, the classical analysis of the fault displacements/juxtapositions does not support the

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 True 3-D Post-Stack Amplitude Inversion for Improving Reservoir Characterization

Mougenot, Denis and Claude A. Vuillermoz* Compagnie Générale de Géophysique, France

To meet the requirement for more efficient reservoir multi-channel 2-D algorithms, this program provides characterization, a new true 3-D seismic amplitude a complete spatial coherency in both the in-line and inversion program has been implemented. cross-line directions which is not obtainable with the The program uses a sophisticated algorithm (global 2-D approach. optimization) to fit an impedance model to the migrated zero-phase 3-D seismic data. The result is Denis Mougenot is currently an impedance volume consisting of spatially Head of the Seismic Imaging coherent layers as opposed to seismic reflections Department with Compagnie corresponding to the boundaries between layers. The Générale de Géophysique, France. depth, thickness and impedance variations for each He has 22 years of seismic layer can easily be output and mapped, and using processing and interpretation well information, can be linked to changes in the experience, 16 years of which were lithological properties. In this way, the geologist can as Marine Geologist with the use 3-D seismic data to build an accurate model, not University of Paris and 6 years as only of the structure, but also of the stratigraphy of Reservoir Geophysicist with CGG. the reservoir. Denis is a member of the AAPG and the French Geological This 3-D inversion program uses a multi-channel Society and has published many papers in several process which is better able to cope with the noise international publications on the geodynamics of the that is present on most seismic data than existing continental margin and reservoir studies. He is a single-channel 1-D algorithms. Comparison of the graduate of Ecole Normale Supérieure and has a PhD two methods, on a 3-D block, shows that the 3-D from the University of Paris. approach gives improved vertical resolution, layer visualization, and spatial coherency. With respect to Claude A. Vuillermoz (see Vuillermoz et al., p. 207)

Sequence Stratigraphic Controls on Porosity/Permeability Relationships in Thamama Group Reservoir Zone C (Kharaib Formation, Barremian, Cretaceous), Abu Dhabi

Mueller, III, Harry W. Abu Dhabi Company for Onshore Oil Operations (ADCO)

In the Thamama Zone C reservoir in one of ADCO's instances where the rock type is different in one well major fields, the relationship between porosity and from that in the other wells over the field. Note that, permeability is strongly controlled by sequence given the lack of porosity expression of the stratigraphic position. Description of 450 feet of core parasequences, correlation of the parasequences into from five wells through Thamama Reservoir Zone C uncored wells will be imprecise. However, the (upper Kharaib Formation, Barremian, Cretaceous) led thickness can be predicted based on neighboring wells, to the delineation of five texture-based parasequences so the permeability footage, and therefore the ability within the reservoir; four in the Highstand System to simulate flow in the reservoir, should be essentially Tract below the top C sequence boundary and one in correct even if the detailed correlation is imprecise. the Transgressive System Tract above. Comparison of descriptions with porosity and permeability Harry W. Mueller, III is currently distribution demonstrates that there is no apparent a Senior Reservoir Geologist with relationship between porosity and depositional facies, Abu Dhabi Company for Onshore sequence stratigraphic position or depth below the top Oil Operations (ADCO). Since of the zone. However, a plot of permeability versus receiving his PhD in Geology from depth below the top of the zone shows strong the University of Texas, he has spent correlation between higher permeability intervals and 20 years in the oil industry, mostly the upper parts of the parasequences. When the at Exxon Production Research porosity and permeability data are cross-plotted for Company, where he has been involved the upper and lower parts of each parasequence, the in service work and training in the data cluster much more tightly around trend lines than application of carbonate sedimentology and sequence stratigraphy they do when plotted by other breakdowns. The only to exploration and production problems. Harry is a member of deviations from this distribution occur in those rare the AAPG, SEPM, SPWLA, SPE, SEE and HGS.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Improving Wara Sand Reservoir Mapping with Seismic Data

Mukhtar, A. Nabi The Bahrain National Oil Company

The Ac pay zone is the sandstone facies of the Wara out during 1983-1984. The conventional processed seismic Formation of the Wasia Group (Middle Cretaceous). In data is not to the standards usually required for the Bahrain field the Wara varies from 60 to 100 feet in stratigraphic or reservoir analysis. However, by close thickness and the sand interval from 0 to a maximum of integration of well data and seismic attributes, a new Ac 60 feet. The Ac sandstone is one of the main Bahrain oil map was prepared enhancing its distribution in the field reservoirs but unlike others, its distribution is very erratic. area and predicting prospective areas for further testing The risk to locate new Ac reservoirs has always been high. outside the field limit. Most of the good Ac sand was found by drilling for other objectives. In view of the erratic and random distribution A. Nabi Mukhtar has been with The of Ac sand in the field area where close well control exists, Bahrain National Oil Company it was concluded by previous work on the Ac sand that (Banoco) since 1986 as Senior any attempt to predict the occurence of this sand in an Geophysicist. He received his BSc in undeveloped area would be very risky. An attempt was Geological Engineering/Petroleum made to use the available 2-D seismic data to improve the from the University of Texas at Austin. Ac sand mapping and possibly to delineate new areas for He has worked for the past 10 years further testing. Since the seismic data covers Bahrain field mainly in exploration and development and the areas outside the well control, integration of these geophysics. He is professionally data should give some light to the areal distribution of interested in structural geology and the Ac sand. The onshore 2-D seismic survey was carried reservoir characterization using seismic information.

Drilling the Flanks of Fields, Satellite Structures and Complicated Horizontal Wells with Advanced Geosteering Technology and Extended Reach Wells

Murphy, Eugene*, Hussein S. El-Sayed, Schlumberger Anadrill, UAE and Roy D. Nurmi, Schlumberger, UAE Drilling has rapidly evolved to where there are now a Eugene Murphy is Sales and variety of horizontal well types including some long and/ Marketing Manager for Anadrill in the or complicated well trajectories. Gulf of Suez fault block Middle East and India. He began his reservoirs, which are now being probed with both hook career in seismic and later well log and horizontal wells, will soon have 'extended reach' wells acquisition. Eugene joined Anadrill in as are being used in the North Sea and Gulf of Mexico. 1984 working in mud logging, Horizontal wells allow the probing of the areas between directional drilling, MWD and LWD reservoir wells and are being used to also assess newly in the North Sea, South America and discovered structures. 'Extended reach' wells provide the Nigeria before coming to Dubai. chance to effectively reach, evaluate and test the flanks of reservoirs, marginal compartments and pinchouts and Hussein S. El-Sayed received his BSc even satellite structures too far for standard deviated well in Mechanical Engineering from Ain drilling. Drilling the edges and satellite structures around Shams University, Cairo. He joined producing fields has shown that structure and isochron Schlumberger Technical Services in maps and general reservoir characterization are poorly 1982 as Field Engineer. His field controlled at the edges of the seismic and well data. This assignments took him to Oman, greater uncertainty at the edge requires the use of Pakistan, India and Kuwait. In 1989, advanced geosteering system with which to steer and he became the Field Service Manager maintain a trajectory which has just become available. The for Wireline Operations in Islamabad. abundance of faulting in Cretaceous reservoirs and also In 1990, he joined the newly formed the erosional irregularities of unconformities both cause Logging While Drilling Group to become the LWD Operation difficulty in keeping a horizontal well within the reservoir. Coordinator for the Middle East. In 1993, he became Anadrill Fortunately, measurements of the formation at the bit, Marketing Manager for the Gulf Area. Hussein is Manager for together with computer modeling allow one to take proper Anadrill Operations in the UAE since 1995. corrective action if unexpected changes are encountered. In addition, azimuthal formation resistivity measurements Roy D. Nurmi (see Nurmi, p. 178-179) allow definition of structure and, thus, permit changes of the trajectory in response to structural changes.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Integrated Methods for Geochemical Prospecting of Oil and Gas Fields

Muslimov, Renat Kh., Rasim N. Diyashev*, Rimma P. Gottikh and Irina A. Larochkina* TatNIPIneft Institute, Russia

Regional studies in the Republic of Tartarstan (Russia) than 290 papers and 79 inventions (one of which has been have shown that hydrocarbon accumulations are formed patented abroad). mainly through vertical migration of oil and gas. A clear relationship exists between the tectonic structure of Rasim N. Diyashev is the Deputy crystalline basement and the presence of hydrocarbon Director of Geology and Development accumulations in the overlying sedimentary column. The of oil and gas fields with TatNIPIneft vertically migrating fluids will eventually reach the Petroleum Institute. He has 34 years surface, where they can be detected by physical and of petroleum exploration and chemical methods such as aero-gamma spectrometry, production experience. He was a magnetometry, hydrocarbon and radon measurements. visiting professor of Moscow and Ufa Maps of uranium, thorium, potassium and their Petroleum Institutes. Rasim is a derivatives enable the study of sub-surface fluid member of the SPE and the AAPG and movements. Zones of increased conductivity are apparent has published more than 150 papers on from mapping methane, radon and radio element well tests, oil reservoir management, heavy crude and bitumen concentrations. The integration of these chemical production. He received his Doctoral of Science in 1983 from anomalies with geological data allows the location of oil the Russian Academy of Natural Science. and gas accumulations. Exploration drilling has proved the efficiency of these Rimma P. Gottikh is the main scientific worker of the All- techniques and allowed the optimization and integration Russian Scientific Research Institute of geological, geophysical of methods. The applications of the studies will be and geochemical systems. She has more than 30 years of discussed. experience in petroleum geochemistry and nuclear physics, and has published more than 150 papers on geology, geochemistry Renat Kh. Muslimov is currently the and geophysics. Rimma is a Doctor of Science (1977). Deputy General Director, Chief Geologist of JSC Tatneft. He has been Irina A. Larochkina is currently Head involved in oil propecting works, field of the Exploration Geology Department geology, improvement of oil fields at TatNIPIneft Petroleum Institute. She development processes with this has 23 years of oil and gas fields company for more than 35 years. He is exploration experience. Irina has an honorary member of the Houston published more than 50 papers on the Geological Society, member of the exploration of oil and gas fields. Scientific Council of RAS Nuclear Physics Affiliation, elected corresponding member of Academy of Natural Sciences in the Russian Federation, member of the academy of Mining Sciences, and a member of the Academy of Sciences in the Repubic of Tatarstan. Renat has published more

Shabwa - Lithostratigraphy and Structural Evolution

Nani, Abdul Sattar O., MOMR, Yemen

The Shabwa area of Yemen encompasses the south-eastern Abdul Sattar O. Nani received his part of the rather narrow northwest-southeast trending MSc (Honors) and PhD (Honors) in Marib-Shabwa Graben. This formed part of an extensive Exploration from Baku University in rift system developed across much of Yemen and northern 1978 and 1985, respectively. He Somalia during the late Jurassic. Bounded by two major completed his PhD Equivalency from normal faults, the graben has a complex block faulted floor the University of Karachi in 1986. He rising up from two marginal sub-basins towards a central has worked for the Ministry of Oil and axial basement high. The entire area is blanketed by Mineral Resources, Yemen since 1978. Cretaceous clastics, 300 to 1,500 meters thick within the Abdul Sattar has published a number graben itself and thinning onto the flanking rift shoulders of scientific articles. to the north and south with shallow and sometimes outcropping basement.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Scott A. Runnestrand is a High Resolution Mapping of graduate of Colorado School of Carbonate Porosity Using Seismic Mines with a BSc in Geophysical Lithology Inversion Engineering. He has worked for Phillips Petroleum Company since Neff, Dennis B., Scott A. Runnestrand 1979 doing seismic processing, and David W. Burge* interpretation and applied research Phillips Petroleum Company, USA in signal processing and lithologic inversion. Enhanced mapping of carbonate porosity distribution has been accomplished by using a new David W. Burge is currently a method of seismic lithology inversion. This method Staff Geophysicist with Phillips has been applied to reservoirs worldwide for high Petroleum Company, Bartlesville, resolution structural mapping, horizontal well and Oklahoma. He has 7 years in-fill well placement, in-place reserve estimation, 3-D experience in 2-D and 3-D seismic lithology estimation for reservoir simulation, and data processing, and in seismic prediction of downdip field limits. lithology inversion. He has a BSc The poster will illustrate Phillip's proprietary degree in geophysics from the Incremental Pay Thickness and Non-Unique University of Oklahoma and a MSc Inversion (IPT/NUI) process as applied to several degree in Geophysics from the carbonate porosity mapping projects. Field University of Houston. He is a member of the SEG, examples will be used to illustrate how the AAPG, and AGU. methodology improved drilling success and initial well performance. Geological Characterization and Modeling of The IPT/NUI inversion scheme differs from other Middle East Carbonate Reservoirs Through techniques in that thousands of synthetic seismic Multidisciplinary Integration, Advanced traces are generated using petrophysical logs (porosity, water saturation, shale volume), geologic Technology and New Techniques models, and other apriori information. Comparison of these model traces to the seismic traces during Nurmi, Roy D. the NUI inversion process creates maps for Schlumberger, UAE predefined geologic layers and produces three- dimensional pseudo log volumes, which are used Geological reservoir analyses continue to improve for trend mapping, as input for reservoir simulation, with advances in technology, integration, and for volumetric calculations. multidisciplinary efforts and geostatistical insights. This method has been successfully used for Particularly important are new reservoir insights horizontal well placement in North Sea Cretaceous coming from the integration of geological data, well carbonate reservoirs, resulting in initial production logs, and well testing from horizontal well data. rates of over 11,000 barrels of oil per day. New Geologically guided pressure sampling and drilling locations in a Permian carbonate field have pressure-transient testing is quantifying the also been defined with this method. A reservoir connectivity and production potential of a variety of characterization of a 15 year old field benefited from heterogeneous pore systems and, thus, helping to the petrophysical maps with reduced simulator define by-passed oil and also the multiple origins of model preparation time and improved production early water production. Leached sub-aerially history matching. exposed surface and biostromal zones often act as conduits for lateral water flow, whereas open faults Dennis B. Neff is a graduate of allow water flow both vertically and along their Emporia State University in strike. Such high permeability zones can be used to Kansas, with BSc and MSc degrees enhance production if they do not extend to the oil/ in Physical Science and water or gas/oil contacts. Mathematics. He has worked for Careful integration of multi-disciplinary data is Phillips Petroleum Company since critical to bringing together measurements and data 1977 doing seismic processing, of different disciplines, especially with a variety of seismic stratgraphic interpretation scales - Scanning Electron Microscope (SEM) to and applied research. Dennis holds seismic - technologies. Pores and heterogeneities too patents for seismic processing, large to be defined by core and/or borehole imagery lithology inversion, and direct hydrocarbon mapping alone, are present in Arab and Mishrif biostromes schemes. He is a member of the SEG, AAPG, and is an and Tertiary coral/algal reef facies. These are best SPE distinguished lecturer. defined by the integration of geoscience and logging data with fluid and/or pressure data. Although microporosity is generally examined in very small

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 samples with a SEM, the continuous vertical processes are accounted for via an incremental stress distribution of microporosity and its variation rheology and simulator. Fluid migration is described around the wellbore is being mapped by integrating via Darcy's law with permeability that reflects of high resolution Neutron Magnetic Resonance changes in mineral deposition and fluid density and (NMR) well logging measurements and electrical viscosity that changes with composition and borehole imagery. These recent investigations show temperature. Aqueous fluid composition is micropores can be important in the evaluation of high calculated in a way that rigorously accounts for permeability Jurassic grainstones in addition to the aqueous phase and mineral reactions and exchanges well known pervasive microporosity in Tertiary with non-aqueous phases. Multi-phase fluid reservoirs of Egypt and India and also Cretaceous migration is accounted for via a model incorporating (Thamama) reservoir zones of Arabia. the effects of capillarity and relative permeability and differences in fluid densities and viscosity. All the Roy D. Nurmi is Chief Geologist underlying reaction, transport and mechanical for Schlumberger's Middle East equations are solved consistently in that any one Organization based in Dubai. He process can affect all the others. formerly headed the Geological Reservoir Characterization Group Peter J. Ortoleva has worked since in Tokyo and earlier was the Leader 1970 on reaction-transport of the Production Geological phenomena. Since 1978 this work Research Effort in the USA starting has emphasized the coupling of in 1975. Roy started his industry mechanics, reaction and transport career in 1968 with Texaco in in geological media. He has exploration and reservoir development in Texas and New developed a number of coupled Mexico. Roy received his PhD in 1975 in Geology from mechanochemical and reaction- Rensselaer Polytechnic Institute, New York. He is a transport codes that are presently member of the SPE and Northern Emirates SPE Chapter, used in his and other academic where he is currently serving on the Horizontal Well Mini- research organizations and in the petroleum and Forum Committee as well as a SPE Regional environmental industries. Peter is a Professor of Distinguished Lecturer for the Middle East. He is also a Chemistry and Geological Sciences, and has been the member of the AAPG, SEG and SEE and an Associate Director of the Laboratory for Computational Editor for both the AAPG Bulletin and the Log Analyst Geochemistry at Indiana University since 1988. He magazine of the Society of Professional Well Log Analysts. received his PhD in Applied Physics from Cornell University in 1970 and was post-doctoral Research Basin Hydrologic, Chemical and Mechanical Associate in Physical Chemistry at MIT between 1969 and 1975. Peter is a member of the AAPG. He has Modeling for Integrated Water, Mineral and published 142 papers, 2 books and 3 edited volumes. Petroleum Resource Assessment

Ortoleva, Peter J. A Strategy for Near-Surface Model Indiana University, USA Construction and Subsurface Structural Discrimination A unique three-dimensional model that accounts for the hydrology, mineral, aqueous and organic Pecholcs, Peter I.* and Costas G. Macrides reactions and stress, thermal and sedimentological Saudi Aramco history is presented. Application of the model to assess the resources of a sedimentary basin are In Saudi Arabia, a wide range of near-surface seismic discussed. velocities caused by sand dunes, karst topography, buried The compositional state and producibility of deep- channels, etc. overlay deeper structures of higher velocities. lying aquifers is strongly affected by the mineralogy A reliable estimation of long and medium wavelength and hydrologic properties of the constituting static components of the near-surface velocity-depth formations. These are affected by the long time model is crucial for accurate mapping of these time mechanical, thermal and sedimentological history of structures which in some cases can have closures as small the basin. In turn, the distribution of minerals and as 10 to 20 milliseconds (ms). petroleum are affected by the motion of the aqueous One of the difficulties in testing the reliability of time fluids. In short, in basins the mineral, petroleum and structures in stacked sections lies in separating the effects water resource assessments and exploitation can of the near-surface irregularities from structural changes most effectively be carried out by a fully integrated in the deeper part of the section. We propose a strategy modeling approach. for the estimation and verification of the velocity-depth Such a model (named CIRF.B) has been developed models by using both midpoint and depthpoint oriented by us. Stresses and rock deformation, fracturing and estimation techniques. First we construct an initial multi- compaction due to tectonic history and chemical (cont. p. 180)

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 (cont. from p. 179) layer near-surface model and compute static corrections stratigraphy (reservoir zonation) of these successions using uphole measurements, shallow refraction/reflection is based strictly on wireline log signatures. There arrival times and optimum offset refraction stacks with exists a need for a chronostratigraphic methodology geologic constraints. An initial interpretation of deeper that is independent of biostratigraphy and applicable reflection events is made from the resulting brute stack. to both carbonates (limestone and dolomite) and This initial interpretation and near-surface model are used evaporites. Chemostratigraphy uses the results of in a depthpoint oriented interval velocity estimation isotopic and elemental analyses to characterize a scheme operating from the surface to build a deeper stratigraphic succession and can provide high velocity-depth macro model in a top-down approach. Pre- resolution reservoir zonation, correlation and dating. stack depth migration and forward modeling with We have developed chemostratigraphic frameworks iterative ray tracing are used to verify and update the near- for the Upper Jurassic Arab formations (A-C) and surface and subsurface velocity-depth models. A real data the Miocene Gachsaran Formation. Samples from example is shown to illustrate how this strategy of these carbonate-evaporite successions were analyzed integrating geologic and geophysical data with midpoint for carbon, oxygen, sulfur, and strontium isotope and depthpoint oriented schemes can improve the ratios as well as for trace element composition. interpreter's ability to reliably map subsurface structures. Sample material included limestones, dolostones, and evaporites (anhydrite and gypsum) representing Peter I. Pecholcs received a BSc in a full suite of arid coastal depositional and diagenetic Geology from StonyBrook University facies. Modern sediments and waters from the Abu in 1980 and a MSc in Geophysics from Dhabi coastal zone were also analyzed for Columbia University in 1982. His comparison and correlation with the ancient career has included positions with Sohio material. Petroleum Geophysical R&D, In addition to correlation and dating, our University of Hawaii, and United chemostratigraphic frameworks aided in the States Geological Survey. He has been identification of sequence and parasequence a Research Geophysicist with the boundaries, condensed sections, and in the location Geophysical Research & Development of paleo-watertable horizons that influenced Division of Saudi Aramco since 1992. His current interests are diagenesis. near-surface modeling and inversion. Ross G. Peebles is Senior Costas G. Macrides received a BSc Geoscientist with Halliburton in Physics from the University of Energy Services. He is currently on Athens in 1980, a MSc in Geophysics leave of absence from Halliburton's in 1983, and a PhD also in Geophysics Reservoir Description Group in 1987 from the University of Alberta. working with the Abu Dhabi Marine He has been an Assistant Professor in Operating Company as a Consultant Geophysics at the University of Geologist. Ross previously worked Manitoba and a Senior Research with Halliburton Reservoir Geophysicist with Seis-Pro and Description Services in Abu Dhabi Consultants in Calgary. He joined the from 1991 to 1993. He received his BSc in Geological Geophysical Research and Development Division of Saudi Oceanography from the Florida Institute of Technology in Aramco in 1993. His interests include seismic tomography, 1985 and a MSc in Geoscience from the University of Texas refraction statics, AVO and multi-component seismology in oil at Dallas. Ross is currently investigating the deposition exploration. He is a member of SEG. and diagenesis of carbonate-evaporite successions within a sequence stratigraphic framework as part of PhD research Chemostratigraphy of at the University of Durham, UK. Carbonate-Evaporite Successions John J. McBride (see Mearns et al., p. 170) from the Arabian Gulf Muriel Shaner has been an Peebles, Ross G.* independent consultant since 1993. Halliburton Energy Services, USA Prior to this, she worked with John J. McBride Halliburton Reservoir Description Isotopic Analytical Services, UK Services in Abu Dhabi (1991-1993). and Muriel Shaner Consultant, USA She has also worked for the American Petroleum Institute, ARCO Oil and Stratigraphic correlation and age dating of the Gas, and Standard Oil. Muriel carbonate-evaporite successions of the Upper received a BSc in Geoscience from the Jurassic of the Arabian Gulf have been problematic University of Texas at Dallas in 1987. due to a paucity of stratigraphically significant Muriel is interested in the deposition and diagenesis of modern fossils. As a result, much of the high-resolution arid coastal systems and in strontium isotope stratigraphy.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Victor H. Vega is currently a Exploration Difficulty, Petroleum Geophysicist with Undiscovered Reserves, Amoco Exploration and Production and the Middle East Company. He has been with Amoco since 1993. During the last 2 years, Pierce, Walter H.* and Victor H. Vega Victor has been working in the Amoco, USA Strategic Regional Studies group doing analysis of the Hydrocarbon The result of this paper is a graphical display that Systems for several basins in the aids undiscovered reserve estimation. This paper Central Asia and Middle East areas. presents a new methodology for analysis of He received his BSc from the Universidad Nacional de undiscovered reserves in the Middle East. We Colombia in 1989 and his MSc from the University of concentrate on ways of extrapolating historical South Carolina in 1993. discovered reserves to estimate Historical Undiscovered Reserves (HUR). We propose that Total Undiscovered Reserves (TUR) be divided into Three-Dimensional Analysis of three components: (a) HUR, (b) Analogue Direct Hydrocarbon Indicators Undiscovered Reserves (AUR), and (c) Unexplored Undiscovered Reserves (UUR). We subdivide the Poelen, Hugo J., basin or area of interest into fractions that can best Shell Expro, UK (formerly Shell Research BV) be estimated by one or more of these components. Richard M. Dalley and Ronald C. Hoogenboom* We emphasize that the HUR results improve Shell Research BV, The Netherlands estimates of AUR and UUR. Understanding Middle In the late 1970s data from three-dimensional (3-D) East hindrance exploration difficulty is critical to total seismic surveys were interpreted using paper undiscovered reserve estimates. sections. In the late 1980s computer-aided trace The methodology uses extrapolation of cumulative interpretation systems (TISs) helped make discovered reserves against a parameter we call interpretation easier. With the recent advent of 3-D hindrance exploration difficulty. We divide visualization hardware and software, seismic data exploration difficulty into scarcity exploration and interpretation results can now be displayed and difficulty and hindrance exploration difficulty. We analyzed interactively in true 3-D perspective. To create a parameter that attempts to quantify the fully explore the added value of 3-D visualization change in hindrance exploration difficulty by using technology in 3-D seismic interpretation, 3-D volume the ratio through time of exploration well sequence description techniques have been developed and at maximum oil discovered in million barrels per implemented in the 3-D visualization environment exploration well to exploration well sequence. This to capture, manipulate, store and visualize selected parameter ranges from One, hindrance exploration (sub) volumes in 3-D. Prior to the analysis, the entire difficulty at the beginning of exploration, and Zero, 3-D seismic survey is pre-processed to enhance the hindrance exploration difficulty at an imaginary detectability of seismic events associated with the point when everything is understood about the presence of hydrocarbons. Reservoir geometries can Basin. The difference between the cumulative then be extracted directly from the processed 3-D discovered reserves and the extrapolated cumulative data set, for use in reservoir geological modeling and reserves at Zero hindrance exploration difficulty is reservoir engineering studies. After calibration with HUR. well data and time-to-depth conversion, first Graphs and maps show the variation of historical estimates of gross rock volume for individual bodies undiscovered reserves, and hindrance exploration can be obtained. Field examples have proven the difficulty of the Middle East. added value of these new techniques to the interpretation and analysis of 3-D seismic data sets. Walter H. Pierce is currently Associate Geologist with Amoco's Hugo J. Poelen graduated from the Strategic Regional Studies Group. State University of Utrecht, The He has 14 years of international Netherlands, in 1973 with a MSc in exploration experience with Amoco Mathematics and Physics, with a and 8 years of University teaching specialization in Applied Geophysics experience. His current exploration and Numerical Analysis. Since 1974 interests include the Middle East, he has served the Shell Group in Oman exploration statistics, and hydro- (PDO), The Netherlands (NAM), carbon systems. He has a BA from Denmark (Maersk) and The DePauw University and MSc and PhD degrees from The Netherlands (Shell Research). His Colorado School of Mines. current posting is as a Senior Seismic Interpreter in Shell Expro, Aberdeen. He has a special interest in using new technologies in multi-disciplinary subsurface interpretations teams. (cont. p. 182) 181

Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 (cont. from p. 181) Richard M. Dalley graduated from Ronald C. Hoogenboom joined Shell St. Andrews University, Scotland in in 1978 after obtaining a MSc in 1967 with a degree in Physics and Applied Physics from the University of Mathematics. He joined Seismograph Technology in Delft, The Netherlands. Service Ltd. and served in Mozambique He worked in seismic acquisition and and in Oman as Party Chief during the reservoir characterization research until period of transition from analogue to 1985 when he was transferred to digital recording equipment. In 1977 Sarawak, Malaysia. During his he joined Shell, first as a Seismic assignment to Sarawak Shell he worked Interpreter, later as Head of In-house as an Exploration/Production Seismic Processing in NAM, Shell's operating company in The Interpreter, and as Head Seismic Acquisition, Geophysical Netherlands. Since 1984 he has been involved with the use and Studies and Support. In 1991 he returned to Shell Research as development of workstations for the interpretation of 3-D data Head Prospect/Field Interpretation Research. Ronald is a member sets. Richard is a member of the SEG and the EAEG and in of the SEG and AAPG. 1989 received (with co-authors) the Hagedoorn Award from the EAEG for his work on Dip and Azimuth Displays of seismic horizons.

Degradation of Reservoir Quality by Clay Content, Unayzah Formation, Central Saudi Arabia

Polkowski, George R. Saudi Aramco

Reservoirs in central Saudi Arabia are important new and to maximize production. The distribution of the sources of light sulfur-free crude oil. Development clay minerals within different fields, a new method to work on these wells has shown the adverse effect of determine the pore volume they affect with their clay minerals on their productivity or injectivity. The associated absorbed water, and non-damaging fluids clay minerals may be affected during drilling of the will be discussed. well, during completion, during production, and/or injection. Kaolinite, chlorite, illite, and ordered and George R. Polkowski is currently random mixed layer illite/smectite are commonly a Senior Laboratory Scientist in the occuring clay minerals within the Unayzah reservoir Laboratory R&D Center, Saudi rock. As little as 2% clay causes permeability to be Aramco, Dhahran, Saudi Arabia. He drastically reduced. Clays cause problems due to the has 30 years of geological and 15 swelling of smectite caused by injection water or years of petroleum industry drilling fluids of low salinity; clay mineral migration experience. This includes 7 years and subsequent pore blockage; precipitation of with Saudi Aramco and 8 with gelatinous pore-blocking iron hydroxides caused by Western Company of North the dissolution of chlorite by acid; high water America's R&D Center in Fort saturations; and disaggregation of the formation into Worth, Texas. He is a member of the AAPG and GSA and its component sand grains if the weak clay cements has published many papers concerned with geology and the are disturbed. It is therefore important to characterize petroleum industry. He has a BSc (1966) in Geology from the clay minerals present in the Unayzah Formation Purdue University and a MSc (1967) from Stanford in order to lessen the likelihood of formation damage University.

Generation of Carbon Dioxide/Methane Accumulations During Metagenesis

Polutranko, Alexander J. Ukrainian State Geological Research Institute, Ukraine

During metagenesis, formation waters generally carbon dioxide predominance is equal to that of have low salinities and low densities (below 1,000 water, gas will not flow to the surface but instead kg/m3). The amount of gas dissolved in the water remain in the pore space. This is caused by the fact

reaches a maximum, with methane being generated that the density of CO2 at a temperature of 238 ˚C from organic-rich formations and carbon dioxide and a pressure of 70 MPa is 1,400 kg/m3 (T.P. Shuze,

from the decomposition of carbonate rocks. 1981). In this case, the CO2 will move in a downward Carbon dioxide will form a separate phase as soon direction displacing the water. When the carbon as the gas saturation of the formation water is dioxide content in gas mixtures is low, its separation reached. When the density of gas mixtures with the will take place only under extreme pressure

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 conditions. The generation of methane will decrease Alexander J. Polutranko is Senior the density of the gas mixtures. The depth of Scientist with the Ukraine State formation of CO2 /CH4 accumulations will thus Geological Research Institute, where depend on the density of the water, the gas he has been working since 1975, after composition and the thermobaric conditions. In graduating from Ivano-Frankivsk 1967, V.I. Nikolin et al. established the swelling of Oil and Gas Institute, Ukraine. sandstones from the Donbas coal beds at methane Alexander holds a PhD in Geology. saturation. When methane migrates from the deep He is the author and co-author of accumulations, it might fill traps at shallower levels more than 30 publications devoted to in the sedimentary column. thermobaric oil and gas fields conditions and geochemistry of the Ukrainian sedimentary basins. He is a member of the AAPG.

TEEMS: Texaco Energy and Environmental Multispectral Imaging Spectrometer

Prelat, Alfredo E. Texaco Inc., USA

A Hyperspectral Airborne Imaging Spectrometer has links to the imaging spectrometer controller been contracted by Texaco. The system is designated workstation. The radar system still have an on-board by the acronym TEEMS (Texaco Energy and real-time quick look capability for real-time Environmental Multispectral Imaging Spectrometer). reconnaissance for oil spill monitoring. For The system, which will become operational in the exploration and other applications, the data are first quarter of 1996, will have the unique capability recorded and processed later on a ground processing of acquiring information with an optical imaging computer. spectrometer and synthetic aperture radar simultaneously from the same platform. Data Alfredo E. Prelat, Texaco acquisition with geo-referencing and co-registering Honorary Fellow and Senior of UV, VIS, NIR, SWIR, TIR and SAR channels will Scientist at Texaco Inc., holds MSc be achieved in one flight path. and PhD degrees in Geology from The imaging spectrometer system will have a state- Stanford University. His doctoral of-the-art optical scanner and multiple spectrometers dissertation on oil exploration to cover UV, VIS, NIR, SWIR and TIR. Spectrometers decision-making systems focused on are designed to meet the application requirements designing methods to estimate oil of Texaco. All spectrometer band centers, band discovery probabilities. Alfredo widths and S/N are selected by Texaco for specific spent two years in Norway as a applications. The spectral data will be fully Research Fellow for the Royal Norwegian Scientific and calibrated. The system control uses a state-of-the- Industrial Research Academy and six years at Stanford art on-board real-time workstation. Real-time data University. He worked as a Technical Advisor for the monitoring and geo-referencing are standard. The United Nations in Asia and South America. He also imaging spectrometer is mounted on a fully worked for Bechtel and Unocal Corporation. Alfredo joined stabilized platform. The recording system is flexible Texaco in December 1989. He has set up a remote sensing and expandable. laboratory primarily designed to define prospecting areas The Synthetic Aperture Radar is built as an and environmental assessment for various exploration independent system connected via communication groups in the company.

3-D Interval Velocity Inversion: A Case History from the Middle East

Richardson, Timothy M., Alfonso Gonzalez and Darko Tufekcic* Western Geophysical, USA

Lateral velocity variations in the overburden distort strong facies changes between evaporites, calcareous seismically derived stacking velocities, introducing and argillaceous lithologies, and their alterations uncertainty when converting seismic data to depth. produce lateral velocity variations. This complex This two-part study shows a method to remove overburden raises considerable doubt when distortions so that a more certain depth image can be conventional depth interpretation of deeper subtle obtained. This is particularly important in many oil structures is attempted. In the first part of this work, producing provinces of the Middle East, where we use synthetic 3-D seismic data to illustrate the complex depositional environments associated with impact of lateral velocity variations in seismic stacking (cont. p. 184) 183

Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 (cont. from p. 183) velocities. The effect depends on the size and depth of Development Group. He has conducted research in the areas lateral velocity variations, the depth of the of velocity analysis, multiple attenuation, and signal measurements, and survey design properties such as processing. He is a member of the SEG. azimuth, offset, and fold distribution. In the second part, we introduce a 3-D interval velocity inversion Alfonso Gonzales received a BSc method to estimate a geologically meaningful interval in Oceanography from the velocity field. Experience so far with synthetic and University of Baja California in field data has shown that resolution of our method Mexico (1977), MSc (1979) and PhD depends on the quality of the interpreted stacking (1982) degrees in Geophysics from velocity field and its sampling. Our results show that Stanford University, and an MBA definition of geological structures in the transitional (1988) from the University of zone at the shelf margin is significantly improved with Houston. While at Stanford, he was this technique, when compared with the conventional a member of the Stanford Exploration approach using Dix's equation. In addition, we are Project where he did research in wave able to identify a new prospective play in the target equation velocity estimation. Between 1982 and 1988, zones previously masked by the effect of a shallow Alfonso worked in research and development for Geosource low velocity overburden. Inc. In 1988, he joined the staff of Western Atlas International as Senior Research Geophysicist where he has Timothy M. Richardson received been responsible for research in 3-D seismic data processing, his BSc in Geology in 1986 from the in particular 3-D velocity estimation. He has been granted University of New Mexico and his two patents. Alfonso was an instructor of the 3-D Seismic MSc in Geophysics in 1989 from the Exploration SEG course and is a member of the SEG, EAEG, New Mexico Institute of Mining and IEEE, and SEG of Houston. Technology. He joined Western Geophysical in 1989, where he is Darko Tufekcic (see Carvill and Tufekcic, p. 124) currently in the Research and

The Production and Interpretation of Time Slice Velocity Maps

Rivett, Arnold M.*, James A. Richard, Hashim M. Al-Nahwi and Adil A. Al-Khelaiwi Saudi Aramco

Velocity maps were generated from stacking velocity maps produced can indicate areas where seismic data. The intent was to produce velocity data could be reprocessed for new exploration objectives. volumes which could serve as the starting point for This can produce new results from old data and processing of 3-D data. reduce the effort needed in large areas by defining Once the velocity volume was prepared, the analysis problems which need to be solved. planes were mapped. These were seen to be velocities on time slices which could be spatially Arnold M. Rivett received a BSc filtered and used for stacking 3-D data. It was seen in Geophysics and Physics from the that the unfiltered maps contained useful University of British Colombia in information about seismic data which were used in 1968. He has been employed by a making these maps. variety of petroleum producing One example shows that two lines in a survey may companies and has worked in not be optimumly stacked. A second example shows Canada, USA, Iran and Libya an area where three surveys had been combined. The before coming to Saudi Aramco in boundaries between surveys illustrate that the 1991. Arnold's primary interest is stacking velocities were quite different for the three seismic interpretation and he is areas. A third example is an area where we wished currently the Supervisor of the Depthing/Mapping unit to prospect for deeper targets. The velocity maps of the Geophysical Technology Division of Saudi Aramco. show good consistency to 1.40 seconds. At times He is a member of the SEG and the DGS. greater than 1.40 seconds the maps begin to break up. This indicates that the earlier processing James A. Richard, Hashim M. Al-Nahwi, and Adil concentrated on shallow targets. To make these lines A. Al-Khelaiwi (see Al-Nahwi et al., p. 108-109) useful for deeper targets the seismic data must be reprocessed to improve velocities used to stack deeper events. Time slice velocity mapping can be done routinely from a data base. Interpretation of

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Russell, Steven D.*, Richard F. Hulstrand, Harry W. Mueller, III ADCO, UAE Colin P. North and Gordon M. Walkden University of Aberdeen, UK

The Lower Cretaceous Shu'aiba Formation of Wadis Richard F. Hulstrand is a Reservoir Muaydin, Bani Kharus and Kamah was measured to Geologist with ADCO. Prior to resolve small-scale vertical heterogeneity in lithofacies rejoining ADCO in 1990, he worked and biostratigraphic assemblages. The thickness of with Mobil in Nigeria, Iran, USA comparable depositional packages is considerably less Mid Continent and the Gulf of than in the adjacent sub-surface areas, primarily as a Mexico. He received his BSc and result of intense stylolitization produced by Hawasina MSc in Geology from the University nappe overburden. Ongoing research suggests that of Michigan. His 18 years of Middle the shallow-water shelf and shelf-margin sediments East experience have covered field, of the Shu'aiba Formation in all three wadis were regional, exploration and deposited during a second-order sea-level late development aspects. Richard's interests include combining highstand with associated third-order systems tracts. outcrop and sub-surface information, regional mapping and Thick, typical inner-shelf algal platform lithofacies rigsite operations. (Bacinella sp. and Lithocodium sp.) characterize the lower Shu'aiba Formation. Differentiation of the shelf and Harry W. Mueller, III (see Mueller, p. 175) shelf-margin during mid-upper Shu'aiba deposition is evidenced by rudistid biostromes, rudistid debris Colin P. North is a Lecturer in deposits, and associated back-biostrome lagoonal Petroleum Geology at Aberdeen shoals. Lithofacies of the fore-biostrome environment University. After 8 years with BP, and intrashelf basin are not evident. Lower Cretaceous where his last assignment was Senior carbonates are disconformably overlain by thin, Geologist on coal reserves restricted transgressive sediments of the basal Nahr assessments, he had a year as Umr Formation which is characterized by highly Research Fellow jointly with Shell argillaceous, Orbitolina-rich wackestones and Research Lab and Delft University, packstones. There is no clear evidence of subaerial then joined Aberdeen University in exposure in the upper Shu'aiba Formation. The 1989. Colin researches and publishes establishment of a litho-biofacies architecture allows on two complimentary themes: methods of sub-surface interpretation of established reservoir units and geological prediction and modeling, and arid-region depositional environments from producing fields. continental sedimentology. He is a Chartered Geologist and The cement sequence stratigraphy of large syntaxial holds a BSc in Geology from London University and a PhD overgrowths of echinoderms was interpreted using from Bristol University. Colin is also a member of the AAPG, cathodoluminescence petrography. Four distinct SPE, and several other international professional societies. phases of syntaxial cement development reflect precipitation within an evolving diagenetic Gordon M. Walkden is currently environment from shallow meteoric/phreatic to deep the Head of the Department of burial phreatic with pressure solution. Geology and Petroleum Geology at the University of Aberdeen, Steven D. Russell is currently a Scotland. After receiving a degree Senior Geologist with ADCO. After from Quintin School in 1970 in receiving his BSc in Geology from London, he obtained his PhD from North Carolina State University and Manchester University in Carbonate MSc in Geology from Duke Sedimentology in 1970. He was University, he spent over 16 years as appointed Lecturer in the a Geologist in various exploration Department of Geology and Petroleum Geology and Senior and producing assignments with Lecturer in 1988, and became Department Head in 1993. Mobil Oil Corporation and as a He has extensive field experience and supervision in research Geophysicist at Amoco Production in Britain, Europe, North America and the Middle East. Company. He is currently preparing his PhD at the Gordon is the author of numerous scientific publications on University of Aberdeen in Carbonate Sedimentology. Steven carbonate stratigraphy, diagenesis, geochemistry, is a member of the AAPG, SEPM, SEE and SPE. cathodoluminescence, vertebrate paleontology and speleothem deposits.

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Russell, Timothy S.* and Robert B. Lathon Saudi Aramco

3-D seismic attributes were used to investigate the Texas and the last three years with Saudi Aramco. He has a BSc apparent reservoir heterogeneity and depositional in Geology with a Geophysics option from Michigan State complexity associated with a central Arabian field and University. Timothy is also an Armed Service veteran. recommend drilling locations. This field has an unambiguous structural closure; however, two factors, Robert B. Lathon graduated in 1969 rapidly changing lithology and sparse well control, put a from the University of California with critical dependence on the seismic data. Seismic attribute a BSc in Geophysics. He worked as an analysis is an extremely sensitive job that requires careful Interpreter for Gulf Oil's West Coast/ data preparation and detailed analysis of the seismic Alaska Division from 1969 to 1974. He information. By integrating the geophysical, geological then worked as an Exploration and and engineering information, four well locations were Production Seismologist for Sarawak selected. The results were accurate well prognoses, Shell from 1974 to 1979 and as increased reserves and validation of a method of Consultant in Houston from 1979 to interpretation. 1987. Robert is currently a Geophysical Consultant with Saudi Aramco working on geophysical reservoir Timothy S. Russell is currently a description. Geophysical Descriptor working on reservoir characterization for Saudi Aramco. He has 12 years of broad based industry experience of which 2 years were with Woods Geophysical in Mt. Pleasant, Michigan, 5 years with PetroStar Energy, Michigan, 2 years with GeoQuest Systems in Houston,

The Impact of Sequence Mapping and Detailed Depth Conversion on Field Development, an Example from Block 4, Shabwa Basin, Yemen

Sahota, Gurdip*, Keith D. Gerdes, Leslie S. Peterkin, Nimir Energy Services Limited, UK and Tony F. Corrigan, Corrigan Associates, UK

The stratigraphy and tectonic evolution of Block 4, Yemen depth conversion methodology in the absence of is complex. The basin architecture has evolved through quantitative well to seismic ties are discussed fully. Salt multi-phase rifting and salt tectonics. Drilled stratigraphy tectonics in Block 4 cause further complications for depth contains clastic, evaporatic and carbonate sediments that mapping of sub-salt targets. The impact of blockwide reflect depositional environments ranging from deep depth maps on the understanding of producing and non- marine to continental. Several fields and, as yet, undrilled producing accumulations identified in Block 4 is discussed plays exist within this complex setting. An evaluation of in detail. the hydrocarbon potential in Block 4 requires a suite of depth maps that accurately tie drilled sequence Gurdip Sahota is a Senior stratigraphic horizons to seismic data. Eighty Geophysicist with Nimir Energy development and exploration wells and approximately Services Limited. He has 11 years 6,000 kilometers of seismic data were available for this experience in petroleum exploration and study. Wireline log data were used to establish a sequence development. Prior to this position, he stratigraphic framework for Block 4. Well imaged seismic worked for British Petroleum for 9 years data allowed qualitative sequence correlation between in several site offices and head office. He wells. The critical well to seismic ties, however, could not has BSc and PhD degrees in Geophysics be achieved using standard well calibration techniques from Newcastle University, UK and as many wells had limited sonic coverage and none had Swansea University, Wales. Gurdip checkshot information. Velocity information for depth is a member of the PESGB and RAS. converting time maps was derived from a cross-plot study of sonic logs. Limitations imposed on seismic wavelet Keith D. Gerdes (see Gerdes et al., p. 140) information are discussed. Velocity fields estimation and (cont. p. 188)

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 (cont. from p. 186) Leslie S. Peterkin is Petroleum Tony F. Corrigan is a Reservoir Engineering Manager with Nimir Geologist with 20 years experience in Energy Services Limited. Prior to the oil industry. After university, he joining Nimir in 1994 , he worked for joined the Shell Research Laboratory in 11 years with Shell International in The Hague, and this was followed by a various operating companies outside of period with the UK Department of the UK as a Reservoir Engineer and Energy. For the last 13 years he has Petroleum Economist. This was consulted, initially with Intercomp and followed by 3 years working for Sun IPEC, and with his own company, International as Reservoir Engineer Corrigan Associates for the last 8 years. Advisor. He received a First Class BSc in Physics from St. Tony has a BSc from Imperial College, London University and Andrews University in 1975 and followed this with a PhD in a PhD from the University of Calgary. He is a member of the 1979. PESGB, SPE, and SPWLA. The Precambrian Basement: An Additional Reservoir in the Rifted Basins, North Africa

Salah, Mohamed G.* and Abdulrahman S. Al Sharhan Desert and Marine Research Center, UAE

The instruction from the exploration manager to stop Precambrian basement has been greatly underestimated. drilling and abandon the well as the bit hit the Precambrian basement, no longer applies. The fractured and altered Mohamed G. Salah received a MSc Precambrian basement rocks are the most prolific in 1989 and a PhD in 1995 in reservoirs in the southern Gulf of Suez and the northern Petroleum Geology and Basin Analysis Red Sea rifts where hydrocarbons are produced from 7 from Cairo University, Egypt. He fields, with porosity and permeability values up to 13% joined BP Petroleum Development in and 300 millidarcy, respectively. This work provides a 1984 and moved to Norsk Hydro in comprehensive study on the reservoir characteristics of 1990. He has also worked with Gulf the Precambrian basement in these rift basins, including Canada Resources Ltd., Egypt as composition, nature and genesis of pore spaces, fracture Senior Geologist in 1990. Mohamed pattern analysis and factors controlling production. The is currently Research Associate with the surface and sub-surface Precambrian basement rocks are Desert and Marine Environment Research Center, UAE related to the final stage of the tectonic-magmatic cycle of University. He has presented and published numerous papers. the Arabo-Nubian Shield, and composed of quartz-diorite, His research interests include petroleum geology, basin modeling andesite porphyry, syenogranite and alkali granites and computer applications in geology. dissected by dykes, fractures and joints. Three main directions of fractures, northwest-southeast, northeast- Abdulrahman S. Al Sharhan southwest and east northeast-west southwest have been received his MSc (1983) and PhD detected in the study area. The porosity and production (1985) in Geology from the University rate of this reservoir, as well as the oil-water contact of South Carolina. He is currently Dean movement, depends mainly on the age, intensity and of the Faculty of Science at United Arab direction of the fractures, the diagenetic processes and the Emirates University. His current dip and direction of the dykes and brecciated zones. The research interests include Holocene alteration processes reach their maximum intensity in the Coastal Sabkha of the UAE, and geology top-most section known as the basement cover, where and hydrocarbon habitat in the Arabian the solution and leaching led to the enlargement of the Gulf and adjacent areas. He is currently fractures and vertical communications. The underlying working on his first book with A.E.M. Narin entitled "Petroleum fracture zone has been affected by differential alteration Geology of the Middle East" to be published in 1996 by Elsevier. processes, creating zones of high and low vertical porosity Professor Al Sharhan is a member of the Editorial Advisory and permeability. Thus the reservoir potential of the Board of GeoArabia.

3-D Seismic Survey in Ashrafi Area, Gulf of Suez Egypt: A Case History of Challenging the Seismic Acquisition in a Hostile Environment

Sakr, Mohammed E.* and Samir Sanad, Agiba Petroleum Company, Egypt

Ashrafi field produces oil from four reservoirs, trapped deterioration of data quality. Some wells were drilled in compartments formed by a complex pattern of two during exploration and field development were dry due intersecting sets of faults. This pattern is mantled by thick to very poor 2-D seismic. Feasibility studies concluded evaporites of Middle Miocene age which form salt plugs that a 3-D seismic approach is the only solution to field with steep walls in some areas, causing severe mapping problems. Acquiring the 3-D data in Ashrafi (cont. p. 190) 188

Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 (cont. from p. 188) area was not an easy task. The area represents one of the (1981) and PhD (1985) degrees from most difficult environments for seismic data acquisition. Cairo University. Prior to joining Abrupt change in water depth, dense reefs (sometimes Agiba Petroleum, Mohammed worked exposed forming large shallow lagoons or deep narrow for Suez Oil Company as Head of the channels) and strong currents, made it very difficult for Geophysics Department and then at conventional marine seismic surveys. An attempt to EGPC as Exploration Operations acquire Ocean Bottom Cable data over the area, in 1993, Sector Manager. He is an active failed due to operational problems related to those member of EPEX and EGS. environmental conditions. The survey was executed utilizing two modes for acquisition appropriate to the area: (1) deep water multivessel multistreamer, operation in Samir I. Sanad is currently the accessible areas in water depth more than 20 meters Exploration General Manager and (covering 100 square kilometers), and (2) Ocean Bottom member of the board of Agiba Petroleum Cable in reefal areas, less than 20 meters, which are not Co., Egypt since 1992. He received his suitable for streamer towing operations (covering 35 BSc in Geology and Physics in 1966 square kilometers). The survey was successfully from Ain Shams University. Prior to concluded in 77 days, over 95% of the proposed areas joining Agiba in February 1985 as Chief and covering about 135 square kilometers. Geophysicist he worked for General Petroleum Co. until 1983 as Senior Mohammed E. Sakr is currently Chief Geophysicist with Agiba Geophysicist and for Mediterranian Oil Petroleum Company, Egypt. He received his BSc (1970), MSc and Gas from 1983 to 1985.

Geological Analysis of Early Water Production in Oil Reservoirs and Horizontal Wells in the Middle East, Egypt and India

Sapru, Ajay K.*, Schlumberger, Oman, Elliott W. Wiltse, Schlumberger, Saudi Arabia and Eric Standen, Schlumberger, France Water coning in producing horizons is an important reason moving to Muscat in April 1993. He is a member of the AAPG, for drilling horizontal wells. However, early water SPE and a life member of the Geological Society of India (GSI). production from horizontal wells is now recognized to He holds MSc and PhD degrees from the University of Jammu, be a surprisingly common phenomenon even in fields India. where water production was not anticipated. Analysis of many of these horizontal wells suggests that open, Elliott W. Wiltse has been with permeable faults are commonly the actual cause of early Schlumberger since 1985 and is water and/or gas production. Often there are more of currently a Division Geologist with the these faults present than had been originally mapped. company. Prior to joining Schlum- Horizontal wells and 3-D seismic are revealing both high- berger, Elliott worked with Pennzoil angle normal and strike-slip faults which had not been (1980-1985) and AMOCO Inter- mapped or penetrated by previously drilled vertical wells. national (1978-1980). He obtained a Geological characterization of the fracture/fault systems BA and MSc from the University of in horizontal wells is critical to the completion design to Oklahoma in 1969 and 1978, prevent early water or unwanted gas production. respectively. Elliott is aafiliated with Generally open faults must be isolated before they are the AAPG and the SPE and is interested in structural geology. allowed to flow water or gas into either in the oil zone or in the horizontal wellbore itself. This characterization must Eric J.W. Standen graduated from be included into an integrated, multidisciplinary effort to UBC in 1971 with a BASc in test the points of water and unwanted gas entry. This Geological Engineering. He worked for multidisciplinary integration approach of geology, several years in mineral exploration petrophysics and pressure test analysis of these zones before joining Schlumberger in 1975. might be called "geotesting". His career took him from Field Engineer through Sales and Applications Ajay K. Sapru is a Division Geologist Development in Canada, after which, for the Oman and Pakistan Division in 1989, he moved to Cairo as a Division with Schlumberger Overseas, based in Geologist with Schlumberger's East Muscat. Ajay has been involved in Mediterranean Division. In 1993 he was transferred to Unit various geological studies and his Geologist's position for Europe-Africa, based in Paris and experience with Schlumberger includes presently is Log Analyst for the Platform Express group in geological application development. S.R.P.C. Engineering. Eric has written numerous papers on a Ajay worked in India and Jakarta before wide range of well logging subjects and is a member of the GAC and APEGGA.

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Scott, Gill*, Rob Crossley, Paul R. Marshall, Thomas H.A. Slater and Dennis R. Clowser Robertson Research, UK

In order to maximize the economic benefits of Rob Crossley joined Robertson horizontal wells it is critical that well placement is Research in 1986 and is currently optimized. The high resolution now achievable in the Manager of Reservoir Geology geometrical steering in 3-D space is highlighted. The and Sedimentology. He has a BSc difficulties of seismic depth conversion and sub- from Reading in 1972 and a PhD seismic resolution for predicting geology, even with from the University of Lancaster in the best 3-D seismic surveys, are illustrated. It is 1976. Before joining Robertson therefore clear that geological steering, not Research, for 9 years Rob undertook geometrical steering, is the key to economic success rift valley research while lecturing in these wells. for the University of Malawi. He The practicalities and limitations of geological is a member of the International Association of steering by mechanical "bouncing" techniques are Sedimentologists. His current interests are assisting the discussed. The theory, practicalities and development of digital core description software and the uncertainties with logging-while-drilling tools evaluation of reservoir uncertainty. (gamma and resistivity) are examined for geological steering. It is concluded that some form of cuttings Paul R. Marshall joined analysis is critical for reducing interpretational Robertson Research in 1979 and is uncertainty. currently Senior Stratigrapher. The circumstances in which conventional cuttings Prior to joining Robertson analysis can be used successfully in geological Research, he worked with the Oil steering are shown to be limited, and the case made Service Company of Iran (OSCO) that specialist cuttings analysis is necessary in many between 1977 and 1979 as a Senior scenarios. The type of specialist analysis, Micropaleontologist. He obtained biostratigraphic or reservoir geological, is a BSc from the University of determined by the geology, and stress is placed on Newcastle-upon-Tyne in 1971, a the need for adequate planning studies in advance MSc from University College, London in 1972 and a PhD of horizontal drilling. in 1976. He is a member of the British The practicalities of specialist ditch cuttings analysis Micropaleontological Society and Paleontological at well site are explained, and performance to date Association. He is particularly interested in Foraminiferal illustrated with results from the Middle East area, Ecology and Paleoecology. including successive world record horizontal wells. The particular problems of geological analysis of Thomas H.A. Slater joined wireline logs, image logs and core from horizontal Robertson Research in 1980 after wells are examined. We stress that the enormous obtaining a BSc from the University successes achieved are the results of team efforts of Liverpool. He is currently Senior involving not only Robertson Research specialists, Reservoir Geologist, specializing in but also dialogue between the drillers, loggers and Middle East sedimentology. His client company geologists. particular interests are problems associated with production from low Gill Scott joined Robertson permeability reservoirs. Research in 1982 and is currently a Senior Reservoir Geologist. She Dennis R. Clowser is currently a received a BSc in 1979 and a PhD Senior Stratigrapher and has been in Carbonate Sedimentology in working with Robertson Research 1985 from the University of since 1970. He received his BSc Southampton, UK. She is a member from the University College of of AAPG. Her particular Wales in 1970. Dennis is a member professional interests are Middle of the Geological Society and the East Mesozoic carbonate AAPG. His areas of professional sedimentology and reservoir geology and their applications interests include Mesozoic and to exploration, appraisal, field development and reservoir Tertiary stratigraphy worldwide simulation. and wellsite biostratigraphy.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 at the Mineral Research and Stratigraphy and Sedimentology of the Exploration Institute of Turkey Storm and Tide-Dominated Shallow Marine until 1981. He obtained his BSc in Siliciclastic Members of the Qasim Geology in 1965 from the Formation, Qasim Region, Saudi Arabia University of Istanbul, a MSc in 1970 and PhD in 1974 from the Senalp, Muhittin and Abdulaziz A. Al-Duaiji* Imperial College of Science and Saudi Aramco Technology in London. He is a member of the AAPG, SPE and the Detailed measured stratigraphic and sedimentologic Dhahran Geological Society. sections from the Qasim Region indicated that the Muhittin has a professional interest in reservoir Ordovician Qasim Formation was deposited as two characterization, sequence stratigraphy and clastic distinctly different progradational coarsening depositional environments. upward shallow marine sequences. The Hanadir and Kahfah members which are middle Abdulaziz A. Al-Duaiji joined Ordovician in age form the lower progradational Saudi Aramco in 1984 as a Wellsite sequence. The Hanadir Member overlies the Saq Geologist. In 1985 he became Formation. It is entirely composed of greenish-gray, Northern Area Exploration laminated, fissile shale, and occasional silt laminae Geologist and since 1992 has been which were deposited in an offshore marine Research and Development environment. The overlying Kahfah Member is Geologist. He received his BSc in composed of alternations of greenish-gray shale and Geology from the University of sandstone. The sand/shale ratio, grain size, and bed Petroleum and Minerals in 1984 thickness of the sandstones increase upward. Five and a MSc in Geology from Texas parasequences were identified. They are composed A & M University in 1991. The regional geology of central of offshore shales and followed by hummocky cross- Saudi Arabia and its environment of deposition is an area bedded strongly storm-dominated lower shoreface of particular interest to Abdulaziz. sandstones. Each parasequence ranges in thickness from 3.70 to 7.45 m and is separated from the other Stratigraphy and Age by a flooding surface. The uppermost part of the Kahfah Member has one complete parasequence of the Glacial Deposits in consisting of offshore, lower shoreface, upper Qasim Region, Central Arabia shoreface and foreshore facies. Eastward the shales gradually pinch out, sandstone beds become thicker Senalp, Muhittin and Abdulaziz Al-Laboun* and the entire unit changes into Tigillite burrowed Saudi Aramco foreshore sandstone facies. The Ra'an and Quwarah members (Upper The stratigraphy and depositional environments of the Ordovician) together form the upper progradational Sarah and Zarqa formations have created significant sequence. The Ra'an Member is a dark gray, confusion and controversy among geologists since they homogeneous fissile shale with occasional siltstone were first introduced. The two formations are laminae. Its upper contact is transitional. The generally used together and have been interpreted as Quwarah Member is composed of sandstone with Late Ordovician-Early Silurian glacial deposits. minor amount of shale. Tidal bundles, reactivation Detailed stratigraphic and sedimentologic sections surfaces, bidirectional cross-bedding, and double were measured from the Qasim, between the towns mud layers are very common in the sandstones. of Unayzah and Tabuk to understand the type of Flaser, lenticular, and wavy bedding were observed glaciation and its effect on deposition during Late in the shaly parts. They were deposited in a tide- Ordovician time. The Sarah Formation of Williams dominated shallow marine environment. and others (1986) cuts deeply into the Saq and Qasim The Qasim Formation is cut sharply by the Sarah formations indicating a substantial drop in sea-level Formation which is middle Ashgillian in age and was and formation of an incised-valley system. It is filled deposited as braided stream and braided-delta with sandstone and conglomerate of a braided changing into storm-dominated shelf facies stream facies. Therefore the conglomerates are fluvial eastward. The rapid facies variation of these lag deposits rather than tillite. Towards the east, this formations indicate clearly the importance of finding fluvial system has deposited a braid-delta. During paleoshorelines for hydrocarbon exploration. our studies, no evidence of glaciation was found in the Sarah Formation which is overlain by the offshore Muhittin Senalp is a Geological Consultant with Saudi marine shales of the Qusaiba Member of the Qaliba Aramco in the Research and Development Division. He Formation. has worked on the geologic modeling of the Khafji reservoir, The Zarqa Formation of Vaslet and others (1989) Unayzah and basal Khuff Sandstones. Prior to joining creates a real problem. Our field work at Jal Az Zarqa Saudi Aramco, Muhittin was employed as Chief Geologist indicated that this section conformably overlies the

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 tigillite burrowed, hummocky cross-bedded presents a number of new, sophisticated techniques sandstone facies of the Kahfah Member. It is developed for the characterization of very complex, composed of olive-green shale, siltstone, and very heterogeneous geological models of clastic and mixed fine-grained, wave rippled sandstone forming a carbonate/siliciclastic reservoirs worldwide as input to coarsening upward sequence due to shoreline full field flow simulation studies. The paper includes progradation. This sequence is identical to the Ra'an detailed examples of 3-D framework modeling, statistical Member of the Qasim Formation. Large, faceted, analysis functionalities, stochastic structural modeling, striated and polished granite boulders and other object-based, grid-based and combined stochastic facies basement-derived materials (dropstones) of distant simulations of clastic, mixed, and transitional depositional provenance occur in the shales. There are slumpings environments, stochastic simulations of the corresponding around the boulders indicating their impact on the petrophysical properties, ranking of static and dynamic sea-bottom. In addition to basement-derived boulders realizations, and upscaling to flow simulation grids. (glaciomarine drift), till, polished glacial pavements and large-scale striations strongly support that marine Gordy G. Shanor is Advisor, Geology, glaciation occurred during the Ra'an and Quwara for Geomatic AS, based in Stavanger, deposition which is Middle-Upper Caradocian time. Norway. Gordy has 20 years of international exploration and reservoir Muhittin Senalp (see Senalp and Al-Duaiji, p. 192) geoscience experience. He worked for eight years with major oil companies Abdulaziz Al-Laboun is a in the USA, Europe and Southeast Geological Specialist with Saudi Asia, followed by 10 years in Asia and Aramco in the Research and the Middle East with Schlumberger Development Division. He obtained his where he specialized in the development BSc in Geology/Chemistry from Riyadh of borehole interpretation techniques and their applications to University, Saudi Arabia in 1973, and integrated field studies. Prior to joining ODIN (now Geomatic) MSc in Petroleum Geology from in 1994, he headed up the geology for Schlumberger's Reservoir University of Tulsa, USA. He obtained Characterization team established in Dubai for major stochastic his PhD from King Abdulaziz reservoir simulation studies of giant fields in the Middle East. University, Saudi Arabia. Abdulaziz Gordy holds a BSc in Geology from the University of Oklahoma, is interested in field geology. He is a member of many geological and is a member of the AAPG, SPE and numerous international and scientific societies and also a member of the board of Saudi geological societies. Society for Earth Sciences. He has published many papers on the Geology of Arabia mainly on Paleozoic. He also published Lars E. Kjellesvik holds a MSc in Part I of Lexicon of Arabia: Lexicon of the Paleozoic and Lower statistics, with diploma work on Mesozoic of Arabia. geostatistics at the Norwegian Institute of Technology (1993). Lars has been Advances in Integrated 3-D employed with Geomatic AS as Geostatistician since completing his Stochastic Reservoir Modeling degree. He has been involved with several case studies utilizing Shanor, Gordy G.*, Lars E. Kjellesvik geostatistical techniques and stochastic and Reider B. Bratvold modeling, provides theoretical Geomatic AS geostatistics courses and Geomatic's STORM software user courses and has been involved in the development of new Application of geostatistical analysis and stochastic modeling techniques within STORM. modeling techniques within accurate 3-D stratigraphic framework models is now recognized as a powerful Reider B. Bratvold is the Director of Research and Development approach to the characterization of known reservoir with Geomatic AS. He was instrumental in the establishment heterogeneity, spanning all scales of description, from of ODIN (now Geomatic) and in the specification of STORM special core analysis to flow simulation grid scales. software and ODIN's other products. From 1983 through 1987 Integration of multi-source data into the building of Reider worked with Statoil and Rogaland Research. In 1989, he multiple, equiprobable stochastic reservoir models enable joined IBM's European Petroleum Application Center and was interdisciplinary teams to simulate quantifiable, detailed responsible for reservoir related activities at the center. Reider heterogeneous models of depositional facies (channels, holds an undergraduate degree from Rogaland University, a deltas, porosity facies, etc.) and their corresponding MSc in Petroleum Engineering from the University of Tulsa, petrophysical distributions as direct input to the flow MSc in Mathematics and a PhD in Petroleum Engineering simulator via the upscaling process. Based on ranking from Standord University. procedures applied to both the detailed and upscaled stochastic realizations, key reservoir management risk analysis can be performed more objectively and intelligently, with significant potential savings. This paper

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Tórtola Fluvial System; A Modern Analogue for the Upper Gharif of the Sultanate of Oman

Silva, Fernando P.T.* and António Costa Silva Partex, Portugal Allard W. Martinius and Koenraad J. Weber T.U. Delft, The Netherlands

The Early Permian Gharif Formation is the most António Costa Silva obtained his important siliciclastic oil reservoir in the hydrocarbon MSc in Petroleum Engineering in province of Oman. The fluvial sediments were 1984 from Imperial College and a deposited in a broad alluvial plain, by rivers shed from PhD in 1993, from the Technical peripheral highs to the East, at the end of Gondwana University of Lisbon with a work on glaciation (Westphalian-Sakmarian) and the initiation mathematical modeling of oil of rifting that led to the development of Tethys Ocean. reservoirs. He joined PARTEX-CPS The Gharif Formation is usually sub-divided into three in 1984 and has conducted reservoir units. The Lower Gharif consists of a basal unit of cross- studies for several fields in the Middle bedded quartz sandstones that locally contain crinoid East and Africa. António also debris and brachiopods. The Middle Gharif consists developed a number of research and development projects of quartz feldspar-rich, cross-stratified sandstone with related to the application of mathematical models for trough-shaped sets inter-bedded in red-brown shales improving the estimation of reservoir properties. He is a and siltstones of fluvial origin. The Upper Gharif member of the Imperial College of Science and Technology, shows more abundant cross-stratified channel Portuguese Order of Engineers and SPE. He has published sandstones inter-bedded with varicoloured shales about 20 papers on reservoir characterization and modeling. deposited in an alluvial environment. Each of the sandy intervals probably represent deposition during Allard W. Martinius received his "wet" pluvial periods, intercalated within the overall MSc in Geology from the University semi-arid environment. Exploitation of this formation of Utrecht. In 1995, he obtained a is particularly challenging given the rapid lateral PhD in Geology from the University variation of facies imprinted by the sedimentological of Technology at Delft, The environment of deposition. Present knowledge of the Netherlands. His PhD research Gharif Formation comes mainly from cores and log focused on the sedimentology data, and only a minor part is derived from small characterization of labyrinthine outcrops in the basin margin. This is clearly insufficient fluvial sediments as a tool for to describe reservoir internal architecture and reservoir modeling. He has published characteristics of discrete sandstone bodies in order to papers on topics related to reservoir characterization, fluvial perform reservoir modeling with a reasonable degree of and shallow-marine sedimentology and paleoecology of confidence. Thus, there is an urgent need to obtain both marine macro invertebrates. qualitative and numerical information from equivalent modern analogues. This paper presents a detailed Koenraad J. Weber graduated in comparison between the Omani Upper Gharif member 1960 from Delft University of and the distal deposits of the Tertiary Tórtola fluvial system Technology with a MSc in Mining of the Loranca Basin in the central Iberian Peninsula. The and Petroleum Engineering. He outcrops of this system have also a labyrinthine reservoir retired in 1993 as Senior Consultant architecture, characterized by a poor lateral and vertical Reservoir Geology from Shell Inter- interconnectedness and low net-gross ratio. national Petroleum Maatschappij having worked 33 years in Shell Fernando P.T. Silva graduated in research operations in many Geology from Lisbon University in countries. Since 1985 Koenraad was 1990. Since then he has been working Professor in Production Geology at the Delft University of with PARTEX-CPS as a Reservoir Technology and in 1993 he was nominated Associate Geologist in several projects in the Professor at the Ecole National Supérieure du Pétrole et des Middle East and Africa. Parallel to this Moteurs. He was a distinguished lecturer for the SPE in activity, he also participated in a 1980 and the AAPG in 1993 and in the same year he received number of research and development the Distinguished Achievement Award from the AAPG. He projects related with the application of is an Honorary Member of the Nigerian Association of fractal geometry to the characterization Petroleum Explorationists and has published some 40 papers and modeling of naturally fractured reservoirs. Fernando is on reservoir characterization topics. currently a member of the Portuguese Geologists Association.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 The Middle Jurassic-Early Cretaceous Geological Evolution of the Republic of Yemen

Simmons, Michael D. University of Aberdeen, UK (previously British Petroleum)

The upsurge in hydrocarbon exploration activity in from outcrops and wells. A number of sequences Yemen, coupled with renewed academic study of are recognized, each representing a distinct phase in outcrops, has led to much new stratigraphic data the evolution of the basin. The biostratigraphic being made available. Of particular interest is the criteria used to recognize and define each sequence hydrocarbon bearing Middle Jurassic - Early will be discussed. It is concluded that use of the Cretaceous succession of southern Yemen and the proposed sequence nomenclature permits a clearer equivalent succession of northern Yemen. understanding of basin evolution than does the Biostratigraphy has proved to be an invaluable tool current complex lithostratigraphy. for correlating these sediments and developing a chronostratigraphic framework on which a sequence Michael D. Simmons is Senior stratigraphy model can be developed. It also assists Lecturer in Petroleum Geoscience at in refining the complicated lithostratigraphy which the University of Aberdeen. From exists in this region. 1985 to early 1996 he worked for In this paper a biostratigraphically controlled BP Exploration. He has a BSc and correlation is presented extending from the Sana'a PhD from Plymouth Polytechnic. region in the north-west of the Republic to Ras He is interested in applied Sharwayn in the south-east. This incorporates data biostratigraphy and the geology of the Tethyan region.

Geo-Steering of Horizontal Wells in Thin Oil Bearing Formations in Block 5, Offshore Qatar

Sonderskov, Carsten* and Morten W. Jeppesen Maersk Oil Qatar AS, Qatar

Maersk Oil Qatar AS operates the Al-Shaheen field Carsten Sonderskov is currently in Block 5 offshore Qatar. In the past the field has Chief Geologist with Maersk Oil been penetrated by several vertical wells because it Qatar AS, Qatar. He received a is situated above the North Field, the giant gas field MSc in Geology from the in the Arabian Gulf. However, until recently the thin University of Copenhagen. Prior Cretaceous reservoirs were considered non- to joining Maersk Oil Qatar AS in commercial. Maersk Oil commenced an appraisal 1994, Carsten worked with the program of the oil bearing reservoirs in 1992 and Geological Survey of Denmark, The since then drilled 7 horizontal wells in the Kharaib Danish Energy Agency and Maersk B, Shu'aiba and Nahr Umr formations. The Kharaib Olie og Gas AS in Denmark. B wells have been drilled as very long (up to 13,000 Carsten is a member of the SPE and DGF. feet) horizontal sections in a limestone reservoir which does not exceed 30 feet in thickness. The Nahr Morten W. Jeppesen joined Umr wells have been drilled as 6,000 to 7,000 foot Maersk Olie og Gas AS in sections in an unconsolidated sandstone reservoir Denmark as a Geologist in 1991. In which is only 10 to 15 feet thick. Recently, a well 1994 he transferred to Maersk Oil was drilled in the Shu'aiba with 16,410 foot (more Qatar AS where he has been than 5 kilometers) long horizontal section within a working as a well-site Geologist and 30 foot thick limestone reservoir. These achievements Petrophysicist. He received a MSc have only been possible due to geo-steering of the in Geology from the University of wells using 3-D seismic, biostratigraphy, Logging Copenhagen in 1991. Morten is a While Drilling and rigorous show description. member of the AAPG and SPE and Examples are shown from the horizontal wells drilled is particularly interested in production and development in the Kharaib B and Shu'aiba limestones and in the geology. Nahr Umr sand.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Stratigraphic Interpretation of Magnetotelluric Data in Central Saudi Arabia

Stewart, Ian C.F.*, Thomas C. Connally, Saudi Aramco and Jeffrey H. Copley, Arnold Orange Associates, USA

(See paper by Stewart et al., p. 52-63)

Measurement of Formation Resistivity Through a Metal Casing

Strack, Kurt M.*, Otto Fanini, Hans-Martin Maurer, Bentsion S. Singer and Lev A. Tabarovsky Western Atlas Logging Services, USA

Over the last 60 years, numerous attempts have been Otto Fanini is currently Project made to measure the earth formation resistivity Manager with Western Atlas behind a steel casing. The knowledge of the Logging Services. He received his formation resisitivity is important because it is one MSc in electrical Engineering from of the prime indicators of water saturation. The scope Texas A&M University in 1982. of applications for the Through Casing Resistivity Otto worked for Texas Instruments (TCR) technology includes controlling water floods, as Design Engineer from 1982 to monitoring producing zones, and searching for 1986, in telecommunications from hydrocarbons by-passed in open-hole logging 1986 to 1990, and in operations. This has inspired a number of authors instrumentation electronics area to investigate opportunities and limitations of the from 1990 to 1992. TCR measurement. In this presentation, we discuss the results of the feasibility study carried out by Hans-Martin Maurer is currently Western Atlas Logging Services. The study was co- Scientist with Western Atlas funded by the Gas Research Institute. Results of a Logging Services. He received his field test of the prototype tool developed by MSc in Physics in 1986 and his ParaMagnetic Logging Inc. confirmed the theory. PhD in Geophysics in 1993 from the Our numerical feasibility study addressed a wide University of Braunschweig, range of issues important for the development of the Germany. Hans-Martin had a tool. This included evaluation of the signal levels, research stipend at Uppsala operating frequency, vertical resolution, etc. University, Sweden in 1994. Distortions due to the presence of the cement sheath around the casing, proximity to the casing bottom, Bentsion S. Singer is currently and casing imperfections were addressed as well. with Macquarie University, The field test confirmed the conclusions of the Australia. Bentsion received his feasibility study. The TCR logs were found in good MSc in Physics from Moscow State correlation with the open-hole resistivity University and his PhD in Physics measurements made more than a decade ago. and Mathematics from the USSR Academy of Sciences. He was Kurt M. Strack is currently Senior Scientist with Western Atlas Research Manager with Western Services from 1993 to 1995. Atlas Logging Services. He received his MSc in Geophysics Lev A. Tabarovsky is a Scientist from Colorado School of Mines in in a senior position with Western 1981 and PhD in Geophysics from Atlas Logging Services. He has a the University of Cologne, MSc in Nuclear Physics from Germany. Kurt worked for Group Novosibirsk University, a PhD in Seven Inc., Denver as Geophysicist Geophysics and a Doctoral Degree from 1981 to 1982, Assistant in Technical Applications from the Professor at the University of Cologne from 1983 to 1992 Russian Academy of Sciences. and President of Harbour Dom Consulting from 1989 to From 1968 to 1989 Lev was 1992. working in different positions for the Institute of Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Stratigraphy and Facies Definition of the Delineation of Organic Richness and Lower Cretaceous Minagish Oolite, Thermal History of Thamama Group in Umm-Gudair Field, West Kuwait Eastern Abu Dhabi: A Modeling Approach

Sungur, Dogan Taher, Ahmed A. Kuwait Oil Company, Kuwait Abu Dhabi National Oil Company (ADNOC)

The Umm-Gudair Field produced oil from the The source rock potential of the Thamama Group in middle "Oolitic" member of the Lower Cretaceous eastern Abu Dhabi was assessed by a new efficient Minagish Formation. This bioclastic limestone technique which uses wireline logs. This technique reservoir has produced over 310 million barrels of models the areal extent of organic richness and oil since the discovery of Umm-Gudair in 1954. thermal maturity of source rocks. The Thamama The Minagish reservoir was deposited in shallow Group has rich petroleum resources and possibly subtidal to supratidal conditions resulting from multiple source rock layers associated with various deposition on gently sloping carbonate banks. Sonic depositional setting. The source rock screening log correlations identified fifty consistent proved the presence of an excellent source through stratigraphic layers with differing porosities. Minor good to moderate source layers within Thamama oscillations in sea level are indicated by numerous basinal facies. abrupt vertical changes of facies. Lateral facies The scarcity of vitrinites in the predominantly variations also occurred within these layers. carbonate environment of the Thamama Group has Descriptions of selected cores determined 13 major forced researchers to use thermal history modeling lithofacies. Grainstone and packstones dominate to delineate mature kitchens. The modeling resulted some layers, while wackestones are characteristics from reconstruction of maturity and temperature of the less permeable layers. histories based on Lopatin's Algorithm and Facies interpretations and mapping provide evidence Arrheneous Equation. The modeling indicated that that the stratigraphic layers can be combined into the Thamama mature kitchens are mainly located in seven distinctive genetic groups. Each group has a the central part of the study area adjacent to the characteristic assemblage of facies, reservoir foredeep basin. Migration from these kitchens is properties and well productivities. Productive mainly lateral westwards updip toward the main reservoir intervals are dominantly grain-supported, Thamama producing fields in east Abu Dhabi. high-energy limestones. They are of field-wide The modeling results are compared with available extent, vertically stacked and separated from each observation and analytical data to serve as a basis other by relatively low permeability and less for modeling calibration and gave confidence in the productive wackestones. applicability of these methods in areas where rock This geological model will assist reservoir samples are very limited or even not available. simulation, as well as improve primary recovery and analysis of water performance. Selective perforation Ahmed A. Taher is a Geologist of the more productive zone will optimize primary with the Abu Dhabi National Oil recovery and water flood design by assuring Company (ADNOC) since 1982 continuity of fluid flow between injection and and has worked as an Explorationist production wells. for the ADNOC Concession areas. He received his BSc in Geology from Dogan Sungur is a Senior UAE University. He is a member Geologist at Kuwait Oil Company. of the Society of Explorationists in He has 21 years of petroleum and the Emirates (SEE). Ahmed is exploration experience including 2 particularly interested in the years in Kuwait Oil Company, 7 statistical modeling of source rocks and its maturation regime. years in AGOCO, Libya, 5 years in Norcen Oil, Calgary, Canada, 2 Modifying Near-surface Velocities Using years in Husky Oil Operation Ltd., Calgary and 5 years in the Turkish Pre-Stack Reflection Tomography Petroleum Corporation, Ankara, Teemull, Franklin A. Turkey. He has BSc and MSc degrees in Geology from Saudi Aramco Hacettepe University of Ankara, Turkey. There are some areas where fast velocity material outcrops, and little near-surface velocity information is available. In these environments, the near-surface velocities which focus the stacked sections from some seismic datum may be incorrect. Under certain conditions, it is possible to isolate the velocity

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 components which can distort low relief depth optimize E & P strategies. Our model and E & P imaging. Offset dependent reflection traveltimes are optimization is calibrated and tested using examples used in a 2-D generalized linear inversion modeling from the US Gulf Coast. procedure to capture and update the near-surface velocities. A typical example of the problem and a Faical Tounsi is a post-doctoral demonstration of one methodology to resolve near- fellow at the Laboratory for surface effects is discussed in this paper. Computational Geochemistry, Indiana University. He has seven Franklin A. Teemull is a years experience in modeling Geophysicist with Saudi Aramco. geophysical systems and 2 years in He has been with the company for basin modeling. Faical received his 15 years. Previously, he worked as MSc and PhD degrees from the a consultant for Monenco, Alberta, University of Michigan, Ann Canada. He has a BSc in Arbor. Mathematics and Physics from the University of the West Indies, St. Julie Boyd received her BSc in Augustine and a MSc in Geophysics Geology (1993) from Texas A&M from McGill University, Canada. University and MSc in Geology from Indiana University (1995). Her MSc thesis focused on E & P Optimization for Salt-Associated metamorphic petrology. She also Reservoirs Using a 3-D Stress, Hydrology worked on pressure solution - and Diagenesis Salt Tectonics Simulator mediated compaction at the Laboratory for Computational Tounsi, Faical*, Julie Boyd, Changxin Qin, Geochemistry. Currently she's Miles Maxwell, Khaireddine Sakrani working as a Geologist at Philips Petroleum Co., dealing and Peter J. Ortoleva with offshore prospects in the US Gulf of Mexico. Indiana University, USA Changxin Qin received a BSc in Diapirism and other salt tectonics are involved in Geology from Northwestern many aspects of salt-associated reservoirs. We have University in China (1982), and a developed a fully three-dimensional simulator for MSc in Economic Geology from these phenomena to predict the evolution in time of China University of Geoscience. He salt layers into swells, massifs, diapirs, overhangs did research on mineral deposits, and other salt formation morphological features that fractal characterization of geological make the exploration of salt-associated reserves phenomena and geological systems. difficult. Our simulator can also be used to predict Changxin is presently working on the velocity of salt motion given its present a PhD thesis at Indiana University. topography (as determined from 3-D seismic or other data). In this way one may optimize exploration Miles Maxwell received his BSc strategies and also plan well and pipeline placement in Chemistry from Spring Hill to avoid damage from salt motion by avoiding areas College in Alabama (1987). He is of huge salt flow velocity. The quantitative predictive currently working toward his PhD capability of our simulator arises from the fact that in Physical Chemistry at Indiana it fully integrates all relevant processes in three University. His current research spatial dimensional simulations. Processes interests are non-linear phenomena accounted for are rock and salt deformation by an in geology and overpressuring incremental stress (poroelastic, viscous, pressure mechanisms and episodic fluid solution, fracturing) model, pore fluid flow, grain and release in sedimentary basins. pore fluid diagenetic reactions, energy balance (to calculate the temperature) and sediment and Khaireddine Sakrani received his (possible) underlying fault motion. Input to the BSc in Civil Engineering (1988), simulator is seismic and well data gathered during University of Annaba, Algeria, MSc usual E & P activities. The output is the evolution in Geotechnical Engineering (1991), over geological or engineering timescale of the spatial University of Montreal. He is currently distribution of rock and salt deformation, fluid working on his PhD in Geochemistry pressure and composition, temperature, diagenetic at Indiana University. Khaireddine's mineralization and, in particular, reservoir location, main interest is rock mechanics and extent and characteristics. Our simulator naturally basin stress analysis. integrates seismic and well data with data on rheology, chemical kinetics and thermodynamics to Peter J. Ortoleva (see Ortoleva, p. 179)

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 An Integrated Methodology Based on 3-D Seismic Amplitude Inversion in Support of Reservoir Characterization

Triebwasser, Harold L.*, Jung J. Kim, Charles H. Wagner III, Gary C. Robinson, Ming-Ren Hong and James P. Tung Saudi Aramco

In this paper, we detail a modeling methodology Charles H. Wagner III is using seismic amplitudes inverted to acoustic currently a Senior Petroleum impedance calibrated with log, core, and lab data, Engineering Systems Analyst with and geologic, geophysical and engineering Saudi Aramco. Prior to joining interpretations. Results from this methodology are Saudi Aramco in 1992, he spent 12 shown for studies in a clastic and carbonate years (8 on loan to Saudi Aramco) environment using geostatistics to produce porosity with Chevron as a Mining models. This is a multi-disciplinary approach for Technician, Well Log Analyst, and impacting reservoir characterization efforts at the Programming Analyst. He has a early delineation or field production stage based on BA in Geology from the University the following four-step approach: (a) petrophysical of Tennessee at Knoxville. study to establish a relationship between seismic/ geophysical attributes and some reservoir rock Gary C. Robinson is currently property; (b) build an initial acoustic impedance Team Leader of the Borehole/Marine model in time referenced to the depth model from Modeling and Inversion Team in sonic and density logs evaluated to be the Geophysical Technology petrophysically reasonable and areally consistent; (c) Division of Saudi Aramco. He has extract relevant geophysical attributes; and (d) relate 17 years of experience in the geophysical attributes to reservoir properties. The petroleum industry with Mobil, methodology allows for alternative tools to be CGG and Elf Aquitaine. Gary is a brought to bear depending on the particular geologic member of the SEG, EAPG, AAPG, scenario involved. and the SPE. He has a BSc in Geology from Stanford University and a MSc in Harold L. Triebwasser is Geophysics from the University of Houston. currently a Geophysicist working as a modeler in the Geophysical Ming-Ren Hong is a Geophysicist Technology Division of Saudi working on 3-D modeling and Aramco. He has 21 years of reservoir characterization using exploration experience of which 13 seismic inversion in Saudi Aramco. were with Teledyne Exploration as Before joining Saudi Aramco, a Seismic Crew Geophysicist, Party Ming-Ren worked for Arco Oil and Chief, Land Field Supervisor, and Gas Company in the Exploration Land and Marine Data Processor. and Petroleum Research Center Harold has a BSc in Physics and Mathematics. from 1984 to 1991. He graduated from the University of Texas with a Jung J. Kim is currently a Research PhD in Geophysics in 1982. Geophysicist with Saudi Aramco. He has 14 years of petroleum and James P. Tung is currently a exploration experience beginning Geophysicist working as a Modeler with Petro-Canada Resources, in the Geophysical Technology Texaco Canada Resources and Esso Division of Saudi Aramco. He has Resources Canada. He has been 22 years of exploration experience with Saudi Aramco since 1991 of which 17 were with Shell Oil where he is principally involved Company as a Seismic Crew with interactive applications Geophysicist, Party Chief, and programming and reservoir geophysics. Jung has a BSc Seismic Interpreter. James has BSc in Geology from Seoul National University and a PhD in and MSc degrees in Geology and a Geophysics from Texas University, USA. PhD in Geophysics from the University of Southern California.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Philip F. Johnston received a BSc Prediction of Reflectors Below Drill Bit from Occidental College (1977) and by Seismic While Drilling: a MSc from Colorade School of Application for Carbonate Rocks Mines (1979), both in Geophysics. at South West Andrews Oil Field He has been a Research Associate with Unocal in Brea, California Tsuru, Tetsuro*, Takeshi Kozawa since 1989, working on reservoir Japan National Oil Corporation characterization projects. He also and Philip F. Johnston worked on exploration and Unocal Corporation, California development projects in the Santa Maria, Sacramento and San Joaquin basins. Philip is a Seismic While Drilling (SWD) is a real-time technique member of the SEG, SEP and AGU. to estimate sub-surface structures while drilling and uses seismic waves generated by a working drill bit Description and Characterization of a as a seismic source. Since each source and receiver Fractured Carbonate Reservoir: location in SWD is the opposite configuration of VSP, SWD is considered a reverse VSP technique. Southeast Turkey Generally, this technique is used in normal sedimentary basins in Southeast Asia. However, it Ulu, Murat*, Alaattin Sayili and Haki Naz is rarely applied to high velocity carbonates because Turkish Petroleum Corp., Turkey of the presence of dominant conical waves that In Güney Karakus field, located in the northeast of radiate from the drillstring into the earth. In the SWD Adiyaman town, southeast Turkey, the main experiment at the South West Andrews oil field in reservoir rocks are Upper Cretaceous carbonates. USA, the conical waves were attentuated by stacking This study focuses on a 45 meter thick, Campanian multi-channel data. As a result, some reflectors shallow to deep marine, organic-rich, carbonate below the bit were identified and the effectiveness reservoir. The carbonate is analyzed in terms of of SWD in carbonate rocks was demonstrated. sedimentary facies, diagenetic characteristics, reservoir facies and petrophysical properties and Tetsuro Tsuru received a B.E. degree interpreted via statistical techniques in ten wells. (1981) and a M.E. (1983) in Earth Fracture evaluation has been done by detailed core Resources Engineering from Kyoto and well log analysis. University. Since 1992 he has been As a result of the study, three units: two reservoir a Research Associate with the units and one non-reservoir unit were differentiated. Technology Research Center of Japan The main reservoir unit, forming the lower portion National Oil Corporation in Chiba, of the studied section, is characterized by bioclastic, Japan, working on reservoir partially dolomitic limestones with matrix, intra- characterization projects. From 1984 intergranular, vuggy, stylolitic and fissure-type to 1991 he worked on exploration porosities ranging between 2 to 8%. Permeability projects in China, Myanmar and Akita in Japan. Tetsuro values of this unit range between 0.05 to 0.7 is a member of the SEG and SEG Japan. millidarcy (mD). This unit is described as a fractured diagenetic reservoir and is observed in 9 wells, 3 of Takeshi Kozawa received a which are already producing from this unit. The B.Eng. (1987) and a M.Eng. second one overlying the main unit is characterized degrees from from Kyoto University by cherty, dolomitic limestones with matrix, stylolitic both in Earth Resources and fracture type porosities ranging between 2 to 4%. Engineering. He joined Japan Matrix permeabilites of this unit range between 0.04 Petroleum Exploration Co. Ltd. in to 0.05 mD and interval permeability values are 1989 and worked for Japex expected to be higher due to fractures in areas close Geoscience Institute from 1989 to to faults. This unit is described as a fractured, low 1992. He has been working with porosity, potential reservoir and is observed in 2 wells Technology Research Center of that have not been tested yet. Above these two Japan National Oil Corporatio (JNOC) since 1992. His reservoirs, a non-reservoir unit, serving as a cap rock area of professional interest is borehole geophysics and with extremely low porosity and permeability values seismic data processing. Takeshi is a member of SEG, SEG is differentiated and extends all over the field. Japan and the Japanese Association for Petroleum Technology. (cont. p. 204)

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 (cont. from p. 203) Murat Ulu is currently a Geologist with the Turkish Petroleum Sidi El Kilani Field, Tunisia: Corporation, Turkey. He has 3 Fracture Prediction Through Detailed years of petroleum exploration and 3-D Seismic Attribute Studies research industry experience and is specialized in reservoir geology, well Van Derck, Richard W.* logs and geostatistics. Murat Kuwait Foreign Petroleum Exploration Co., Kuwait received his BSc from Middle East Cameron W. Davis and Chris Tyson Technical University, Turkey. He Landmark Graphics, UK is a member of the Turkish Association of Petroleum Geologists and has published The Sidi El Kilani field is located onshore Tunisia in papers on carbonate reservoirs. the southern area of the North Kairouan Permit. The discovery well, SLK-1, was drilled in 1989 and tested Alaattin Sayili is currently a Staff oil at 3,360 barrels of oil per day from fractured chalky Geologist with the Turkish limestones of the Upper Cretaceous Abiod Petroleum Corporation. He has 10 Formation. A further four wells were drilled on the years experience in carbonate structure in the next three years with a 50% success petrology and oil exploration with rate. All wells encountered Abiod Formation with Turkish Petroleum. Alaattin holds significant fracturation, but only two of the four wells a BSc in Geology from the Technical encountered open fractures capable of flowing oil. University of Istanbul and a MSc Although fractures have been generated episodically from the University of Colorado at since the Maastrichian, only those fractures which Boulder, USA. Alaattin is a developed coincident with oil migration have member of the Turkish Association of Petroleum Geologists remained open and capable of oil production. The and has published several papers on sedimentology and problem was to identify areas of open fractures. diagenesis of carbonates and sandstones. During 1993-1994, a 3-D seismic survey was acquired and studies were undertaken to determine both the Haki Naz is Senior Staff Geologist mechanisms and the distribution of open currently working in the Research fracturation. Maps were made of "probability of open Center of the Turkish Petroleum fracturation" based upon empirical observations and Corporation, Ankara. He has 12 correlations between (a) seismic attributes, years experience in the petroleum particularly reflection amplitude, reflection and research industry. Haki coherence and acoustic impedance, (b) formation- received his MSc in Geological imaging log results for open and closed fractures, Science from the University of and (c) structural models for field development. Tusla, USA. He is a member of the SLK-6 was drilled and successfully encountered AAPG, Chamber of Geological more open fractures than had previous wells. Engineers of Türkiye and Turkish Association of Petroleum In 1995, additional studies were undertaken to refine Geolgists. He has published several papers on geological and quantify the magnitude and distribution of open subjects especially on deep-marine clastics and shallow- fracturation across the field using Landmark's marine carbonates. Reservoir Attribute Visualization and Extrapolation (RAVE) package. This allowed multi-dimensional cross-plotting of seismic and well attributes to be High Resolution Sequence Stratigraphy of identified and statistically significant reservoir the Natih Formation (Cenomanian/Turonian) relationships to be mapped interactively on the 3-D in Oman: Distribution of Source Rocks and seismic workstation. Reservoir Facies The combination of 3-D data visualization, parameter analysis and geostatistics has been effective in Frans S.P. Van Buchem* (IFP), Philippe Razin highlighting fracture "sweet-spots" for future drilling. (BRGM), Peter W. Homewood (Elf Aquitaine), The use of 3-D seismic attributes and modern Jean M. Philip (Université de Provence), Gregor P. analytical software allows the interpreter to search Eberli (University of Miami), Jean-Pierre Platel for the subtle relationships between seismic (BRGM), Jack Roger (Elf Aquitaine), Rémi variations and significant reservoir information Eschard, Guy M.J. Desaubliaux (IFP), Thierry which may be the key to successful field Boisseau, Jean-Pierre Leduc, Richard Labourdette development. and Solange Cantaloube (Elf Aquitaine) Richard W. Van Derck is currently Chief Geophysicist (See paper by van Buchem et al., p.65-91) and Far East Exploration Coordinator with Kuwait Foreign Petroleum Exploration Company (KUFPEC), Kuwait. He has 26 years of diverse international experience in petroleum exploration and development,

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 having worked 9 years for Gulf Oil Corporation in various research and 3-D Symmetric Sampling operations positions, 2 years with in Land Data Acquisition UNOCAL in Ventura, California followed by 12 years as an Vermeer, Gijs J.O. independent consultant specializing Shell Research BV, The Netherlands in seismic interpretation, direct hydrocarbon detection, project In the course of time numerous different geometries management and prospect have been devised for acquisition of 3-D seismic data. generation. He has a BSc from Utah Many of these geometries can be classified as either University and is a member of SEG. patch or line geometries. Patch geometries use shots or receivers in an areal arrangement, whereas line Cameron W. Davis is currently geometries deploy shots and receivers along separate employed by Landmark Graphics acquisition lines. The various geometries can be EAME as a Sales Geophysicist. subdivided into single-fold 3-D subsets. The spatial Cameron started in the oil and gas continuity provided by these subsets can be exploited exploration industry as Marine optimally, if the subsets are properly sampled, and Gravity Geophysicist before if their extent is maximized. These requirements lead becoming a Field Geophysicist for to an extension of the 2-D symmetric sampling Western Geophysical based in the criteria to 3-D. The 2-D symmetric sampling criteria Middle East providing contract are based on the properties of the seismic wavefield services to Saudi Aramco. During in the common-shot gather, combined with the the past four years Cameron has been working for Advance reciprocity principle. For 3-D symmetric sampling, Geophysical which merged with Landmark Graphics. the 2-D criteria - equal shot and receiver intervals, Cameron graduated with a BSc (Honors) in Geophysics and equal shot and receiver patterns - apply with Geology from Liverpool University. similarly, but have to be extended with additional criteria dependent on the type of line geometry. The Chris Tyson is currently employed additional criterion for the orthogonal geometry is as a Technical Consultant with to acquire as many shots in the common-receiver Landmark Graphics EAME. In the gathers as receivers in the common-shot gathers. 3- 16 years Chris has been working in D symmetric sampling provides a starting point for the oil and gas exploration industry, the design of 3-D acquisition geometries. It strips he spent 14 years with Seismograph the design of nominal 3-D surveys from its apparent Services Ltd. working in Peru, Libya, complexity. Pre-stack seismic processing, such as Oman and Norway. Chris has a very dual-domain fk-filtering, benefits from the better broad understanding of the seismic spatial continuity offered by 3-D symmetric exploration business having worked sampling. under contract for companies such as Shell, BP, Elf Aquitaine and a number of small independents. Chris graduated with Gijs J.O. Vermeer received his a BSc (Honors) in Geophysics at Southampton University. MSc in Applied Mathematics from the Technology University of Delft in 1965. After military service he Investigation of Hydrocarbon Productivity joined Shell, where he worked in Variations in Ilam Reservoir of the Sirri Fields seismic processing and seismic inter-pretation, both in research and Vasseghi, Behrooz operations. Since 1991 he has been National Iranian Offshore Oil Company, Iran (previously) in research working on seismic data acquisition techniques. Gijs is the Through ten years of exploration in the Sirri region author of "Seismic Wavefield Sampling" published by SEG of the Gulf, the Ilam horizon (Santonian-Campanian) in its Geophysical Reference Series. His main interest is of the Upper Cretaceous was found to be oil-bearing the interrelationship between seismic data acquisition and in shallow marine chalky limestone of Sirri A, C, D, seismic data processing. He is a member of the EAEG, E and North Fateh (Nosrat) fields. Whereas SEG and CSEG. production is from only one well in Sirri A, recognition of this anomaly is vital to explorers in the Gulf. The reasons for this phenomenon which depends on lithostratigraphic positions, salt Behrooz Vasseghi has 28 years of experience with the oil diapirism, lateral migration of the structure industry of the Iranian Government. He is currently paleotops, differential erosions, will be demonstrated completing his PhD in Geology with the University of in this paper. Tehran, Iran.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Preserved Amplitudes in 3-D Seismic Distribution of Porosity and Permeability Acquisition and Processing for in a Complex Carbonate Reservoir: Stratigraphic Interpretation Application of Permeability Prediction Techniques at Southwest Andrews Vuillermoz, Claude A.*, Denis Mougenot Oil Field, Permian Basin, West Texas Compagnie Générale de Géophysique, France and Philippe Lamant Walden, Skip F.* Compagnie Générale de Géophysique, Bahrain Unocal Corporation, USA and Yoshiro Ishii For 3-D land surveys using cross-spread acquisition, the Japan National Oil Corporation, Bahrain azimuth and offset distribution have significant variations from one bin to the next. This heterogeneity will have an Comprehensive wireline logging suites were undesired effect on final amplitudes. It is therefore acquired in 3 wells at Southwest Andrews oil field mandatory to study the trace distribution derived from a in the Permian Basin of West Texas. Each well near optimum set of 3-D grids suggested by geological penetrated approximately 335 meters (1,100 feet) of and economic criteria. The effect of the geometry may be Permian age Wolfcamp Formation and tested as a whole or in a bin-to-bin mode. For near regular Pennsylvanian age Cisco, Canyon, and Strawn types of acquisition, it is possible to define an elementary formations. This predominantly limestone interval generating pattern, representative of the whole 3-D grid: has a complicated porosity and permeability the smaller this generating pattern, the less heterogeneous distribution, with approximately 10% of the total the geometrical distribution of the traces. Taking into section being producible reservoir (porosity is greater account the real offset distribution, it is then advantageous than 4%; permeability is greater than 1 millidarcy). to use well sampled 2-D data to simulate a 3-D stack section For a given porosity, permeability values can range to observe the effect of the acquisition irregularities at the over 3 orders of magnitude. Estimating the porosity target level. During acquisition, variable attenuation in and permeability distribution from wireline logs is the weathering zone and coupling changes of the source critical to the successful development of this and receivers may impact the amount of energy recorded. reservoir. Each of these wells has a complete core The relative amplitudes are no longer representative of through the reservoir section, allowing wireline the sub-surface reflectivity. A 3-D PAM processing logging results to be compared to known porosity sequence is designed to correct these surface related and permeability distributions. Seven wireline variations: (1) an amplitude decomposition in source and logging techniques were evaluated: (1) Porosity- receiver modes compensates for surface effects; (2) a Permeability Regression, (2) Multivariate Histogram, surface consistent deconvolution compensates for (3) Flow Zone Indicator, (4) Principal Component differential attenuation in the frequency domain. After Regression, (5) NML Logging, (6) Acoustic Stoneley final processing, the seismic depicts the true reflectivity to Wave Attenuation, and (7) Neural Network. be used for a meaningful stratigraphic interpretation. Permeability estimates from the Multivariate Histogram and the Neural Network techniques have Claude A. Vuillermoz is currently the the closest match to the core measurements. Chief Geophysicist Corporate Technical Advisor with CGG. He has spent over Skip F. Walden is a Geophysicist 30 years with CGG. Claude was Party in the Reservoir Technologies Group Chief in Europe, Indonesia, Africa, of Unocal. His responsibilities Canada, and a member of technical include specialized log analysis, management. Claude holds a Doc- borehole geophysics, and 3-D torate in Geology from the University reservoir models. Skip has worked of Grenoble, a degree in Engineering for Unocal 14 years in the areas from ENSPM, and a MSc from the of seismic attribute analysis, University of Lyon. He has contributed to numerous publications fracture and porosity prediction and is a member of the SEG, EAEG, AAPG DGS and HGS. using seismic shear waves, and Denis Mougenot (see Mougenot et al., p. 175) permeability prediction from wireline logs. He has a BSc in Earth Science from the University of California, Philippe Lamant is currently Fullerton, with minors in Math and Physics. Manager of the CGG Processing Center, Bahrain. He has spent his entire Yoshiro Ishii (see Ishii et al., p. 151) 15-years career with CGG. His experience includes operations in Europe, China and Turkey, in acquisition and processing. Philippe holds an Engineering degree from the Geology School of Nancy, France.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Recent Developments in 3-D Seismic Rift Basin Sequence Stratigraphy: Acquisition Techniques in Oman Some Examples from the Gulf of Suez

Wams, Jan* and Justus Rozemond Wescott, William A.* and William N. Krebs Petroleum Development Oman Amoco Production Company, USA John C. Dolson and Salah A. Karamat Acquisition of 3-D seismic surveys in Oman commenced GUPCO, Egypt in 1984 (Suwaihat). The results were disappointing, Dag Nummedal probably due to the acquisition technique and low fold. Louisiana State University, USA Continuous acquisition of 3-D surveys was not started until 1987, with a total of some 20,000 square kilometers Unconformity-bounded sequences within the recorded to date. Improvements have been made over Miocene strata of the Suez Rift reflect a complex the years in small steps. The maximum offset increased interplay between tectonism and sea level from 1,600 to (standard) 4,400 meters, the fold from 16 to fluctuations. Analyses of Miocene outcrops along (standard) 60, a much improved stack operator due to the Sinai margin of the Gulf of Suez have provided the double zig-zag technique and most recently the some new insights into the sequence stratigraphy of introduction of shifted double zig-zag for better ground this basin. The Miocene strata can be subdivided roll suppression. In early 1994 a study was carried out to into seven major sequences separated by try and further improve data quality and efficiency. The biostratigraphically defined time breaks. These approach to find alternatives to the current acquisition lacunae represent depositional sequence boundaries, techniques was two fold: (1) try to find improvements to transgressive surfaces, and condensed sections. the double zig-zag technique which satisfy the above Formation of these basin-wide time breaks was constraints; and (2) try to find different acquisition related to major tectonic events in the evolutionary geometries which give better and/or cheaper data. A history of the basin from rift initiation through rift number of possible improvements, both geophysically climax, and post-rift stages. These events include and economically, on the current double zig-zag were regional sag and fault initiation, fault linkage, identified and evaluated on cost. Of the alternative footwall uplift, and thermal subsidence. acquisition geometries a number of possibilities were Superimposed on this complex structural evolution identified which were either attractive in cost or could were Miocene sea level fluctuations of a magnitude provide higher resolution. A number of these proposals of several tens of meters to a hundred meters. The have been the subject of PDO's yearly Eid tests. Sinai outcrops expose the four oldest Miocene biostratigraphic sequences. In general, they Jan Wams graduated in 1975 from the represent the following depositional history: within University of Delft in Medical the overall transgressive Nukhul Formation, the Acoustics. He was drafted into the lower order events are recorded as local erosional Dutch Army in early 1976 where he surfaces, flooding surfaces, and ravinements. The researched laser- and night-vision Mheiherrat Formation was deposited during a equipment. Jan joined Shell in 1978 relative high stand followed by low stand deposition and shortly after was transferred to the of the Asl Formation. Another high stand resulted UK to take up a position in seismic data in the progradational Ras Budran Formation. processing, followed by postings in Thailand and Brunei as a Seismic William A. Wescott received his Interpreter. Jan was transferred back to Holland in 1988 to head undergraduate degree from the Land Acquisition group, followed by a posting to Yemen as Franklin and Marshall College in Chief Geophysicist. After a further year in Holland as an advisor 1972. After serving in the U.S. on acquisition matters, he joined PDO in 1993 to head the Army he received a MSc from geophysical operations department. Southern Illinois University- Carbondale in 1976 and a PhD from Justus Rozemond graduated in 1988 Colorado State University in 1979. from the University of Utrecht in He joined Amoco Production Geophysics. He completed his Company in Houston in 1979 education in Hydrocarbon Exploration where he has worked on a variety of domestic and at the IFP (1990). In the same year international assignments. His present assignment is with Justus joined Shell Internationale Amoco's Egypt Exploration Team. Research Maatschappij. He worked on seismic acquisition in the Shell EP William N. Krebs has a BSc in Geology from the Research Laboratory in Holland until University of California in Los Angeles and a PhD from 1994, after which he was posted to the University of California in Davis. He joined Amoco Oman, where he now works as an Operations Geophysicist for Production Company in Denver, Colorado in 1978 where Petroleum Development Oman. he worked as a micropaleontologist/stratigrapher in

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 domestic exploration. Since 1987, Salah A. Karamat received his he has worked for Amoco in BSc in 1975 and MSc in 1987 in Houston, Texas in a similar capacity Geology from Cairo University. In for international exploration. His 1995 he completed the requirements specialty is siliceous microfossils, for a PhD in Geology from the same and he is particularly interested in institution. He has been employed fossil continental diatoms and as an Exploration Geologist with applications of graphic correlation the Gulf of Suez Petroleum to exploration. Corporation in Cairo, Egypt since 1977. John C. Dolson received his undergraduate degree from Dag Nummendal was born in Colorado College and has a MSc in Norway and educated at the Geology from Colorado State Universities of Oslo and Illinois. University. He joined Amoco in Since 1978, he has been a Professor 1980 and has worked on a variety of Geology at Louisiana State of domestic and international University, Baton Rouge, where he exploration projects in Denver and specializes in rift basin tectonics Houston. John is presently an and sedimentation, sequence Exploration Geologist with the Gulf stratigraphy, and shallow marine of Suez Petroleum Company in Cairo, Egypt. and lacustrine depositional systems. His current rift basin research focuses on the Paleogene rifts of Eastern China and the Miocene of the Gulf of Suez.

Resolution of Water Influx Patterns Through Application of Multi-disciplinary 3-D Reservoir Modeling

Wigley, Paula L.*, David Masson, Jerry C.W. Hadwin* and Richard W.A. Keech Petroleum Development Oman (PDO)

The Sayyala field is located in Oman, some 530 of remaining reserves in complex fluviatile kilometers southwest of Muscat. The oil reservoirs. A plan for further field activity will be accumulation lies in the fluvial sediments of the compiled based on the results of the 3-D modeling, Permian Upper Gharif Formation, at a depth of simulation study and the test well. around 1,200 meters. The penultimate primary grid location was drilled as a horizontal well in 1993 and Paula L. Wigley is a Production produced only water when tested, despite continued Geologist with Petroleum oil production from nearby vertical wells. A field Development Oman. She has 12 review and multi-disciplinary 3-D reservoir years of operational and research modeling project was therefore started in late 1993, experience with Shell, located in primarily to resolve the incoming water pattern and Turkey and Holland prior to to assess the possibility of locating bypassed oil moving to Oman. She is a member through infill drilling. of the AAPG and holds a BSc in A number of 3-D geological realizations were built Geology from Exeter University. using a probabilistic modeling package and subsequently 3-D reservoir property models were David Masson is a Senior Reservoir constructed based on revised petrophysical Engineer with Petroleum Development parameters for each of the modeled facies. The Oman. He has 16 years of production resultant geological and property models led to a re- and exploration experience with Shell, evaluation of oil in place distribution in the field. A variously located in The Netherlands, number of reservoir simulations were carried out Malaysia and Denmark prior to using the 3-D geological and property models as moving to Oman. He is a member of input. A "simulation prover" will be drilled in 1996 the SPE and holds a MEng degree in in order to test the integrity of the models and the Petroleum Engineering from Heriot- applicability of probabilistic modeling for location Watt University.

(cont. p. 210)

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 (cont. from p. 209) Jerry C.W. Hadwin is a Reservoir Richard W.A. Keech is a Senior Engineer with Petroleum Petrophysicist with Petroleum Development Oman. He has 12 Development Oman. He has 15 years of production and exploration years of production and exploration experience with Shell, located in experience with Shell, located in Aberdeen and North Holland prior Oman, United Kingdom and The to moving to Oman. He is a Netherlands, prior to returning to member of the SPE and holds a Oman. He is a member of the SPE MEng degree in Petroleum and holds a BSc in Geology/ Engineering from Heriot-Watt Geophysics from the University of University. Durham.

Separation of In Plane Multiples from Out of Plane Primaries Using 3-D Pre-stack Time Migration

Williams, Richard G.* and Nicholas J. Cooper Digicon Geophysical Limited, UK

In a V(z) medium where velocity increases with Richard G. Williams received his depth, out of plane primaries can easily be confused PhD from Southampton University with in plane multiples on CDP gathers. Depending in 1979. He has worked for Digicon on the velocity gradient and their dip, out of plane since 1981 as a Research primaries may be either over corrected, flat or under Geophysicist. From 1985 to 1987 corrected after NMO with the RMS velocity of the he was Research Manager for medium. This anomalous behavior makes them very Digicon's Far East Division and is hard to identify and interpret on velocity analyses. currently Research and Marketing Application of constant velocity DMO removes the Manager for Europe, Africa and dip component of the stacking velocity in the shot- Middle East division of Digicon. receiver direction and, in general, leaves the out of plane primary under corrected at all in-line dips. Nicholas J. Cooper received a BSc Thus, its behavior on a velocity analysis is very (Honors) in Geophysics from similar to that of a multiple. Application of 3-D pre- Leicester University in 1981. Since stack (zero-offset) time migration after DMO then he has worked in seismic data collapses the out of plane energy to its true location. processing in a number of locations The confusing out of plane energy is removed from worldwide, most recently as CDP gathers for velocity analysis, thus allowing Technical Supervisor in Digicon's clearer identification and separation of primaries and Jakarta processing center. He is multiples. This separation of primaries and multiples currently a member of Digicon's has been analyzed on 3-D synthetic data. It has been UK-based Research Group. applied successfully to real data from a 3-D marine survey in an area where low relief carbonates generate strong multiples.

Data Management: The Key Enabler For IT In Exploration and Production

Wilson, Hamish Paras, UK

Computer applications and database software have The implementation of computer technology advanced considerably over these last few years. A occurred at a time of significant cost reduction in the complete range of tools is available to help the industry. The increasing use of digital data is part of explorer be more effective. But the industry is still the reason to reduce the staffing in hard copy data having problems making use of computer management. There is still a great need to provide technology. The root of the problem is data and manage the digital data used and generated by management. Current industry practices are geared interpretation software. These facilities have not to dealing with hard copy and paper data. We have been provided for. Hence most companies are not designed the systems to cope with digital data. wasting significant parts of their investments in IT This paper explores the problems and presents some as the interpretation systems are not being used due approaches to implementing solutions. to lack of data.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 A data management infrastructure is needed to application suite. Without the mechanisms to deliver deliver data and manage interpreted data. This must data to workstations and manage the resultant involve the following: (1) the definition of user interpretations, a company is wasting the investment responsibility for digital data; (2) the definition of in computer technology. roles and responsibilities for data management services; and (3) the provision of technology to allow Hamish Wilson is Director of project and interpretive data to be captured and Paras Limited, a consultancy retrieved. A service supplier and user relationship founded in 1994 which specializes should be established between exploration users and in strategic technology manage- their data management support staff. In doing the ment. Hamish worked for 10 years analysis for setting up this relationship, it may be with BP in exploration and appropriate to consider outsourcing data production geology and corporate management. It is a non-core activity and the database development. In 1989 company may not have the skills in-house to provide following an MBA from IMD in an effective service in the changing environment. Switzerland, he became a Data management is a fundamental requirement to consultant in the field of information management. enable the effective use of a company's software

Through-Tubing Well Seismic: A Mast Campaign Across an Offshore Producing Field

Yamaguchi, Kaoru, Arabian Oil Company, Saudi Arabia and Bernard G. Frignet*, Schlumberger Middle East, Saudi Arabia

3-D seismic is gaining popularity in the Gulf region dependent on the Tubing-Casing contact, and tube for fault delineation and the goal of improving wave is present at all 9 wells, but overall 80% of the ultimate recovery of mature reservoirs. Valuable levels were selected by VSP processing. In 5 wells integration of the 3-D with other reservoir data where sonic had been logged, synthetic seismograms requires well seismic data (VSP's or Check Shots) to were generated and confirmed the validity of VSP establish a good tie at key wells. When little well reflections. The data is now integrated in a 3-D seismic data is available, it is possible to acquire VSP's velocity model. in newly drilled and worked-over wells. This paper demonstrates the feasibility of another strategy, by Kaoru Yamaguchi is currently recording well seismic Through-Tubing. Geophysicist with Arabian Oil Well seismic Through-Tubing had been proven Company, Saudi Arabia. He feasible in the Gulf region on a single well basis. In received his BSc and MSc degrees this paper we describe a VSP-through tubing in Geophysics from Hokkaido campaign with an objective to survey two University, Japan. Kaoru started neighboring mature fields totaling more than 200 his career with AOC in 1988, and wells. Following a close cooperation between held various assignments in the Far reservoir engineers and geophysicists, 9 candidate East before coming to the Middle key wells were selected on the basis of: (1) spatial East in 1994. He is a member of distribution; (2) previous well data availability; and the SEG, EAEG and SEG Japan. (3) completion type. At the planning stage and excluding night work for safety, it was estimated that Bernard G. Frignet is 3 days would be required per well (1 day to rig-up Interpretation-Development mast, 1 day to acquire seismic data, 1 day to rig- Geophysicist with Schlumberger down). Local experience indicated that a single Wireline and Testing in Al-Khobar, airgun would be a convenient surface source. A slim Saudi Arabia. He graduated from hole monocable single axis geophone sonde was Ecole des Mines de Paris in 1975 selected as the downhole seismic tool. The zero-offset and has a degree in Geophysics from VSP configuration, with 80 foot level spacing from IFP. He started his career with bottom-hole to surface was adopted. A supply boat Bureau de Recherches Geologiques was dedicated for the duration of the campaign. et Minières in Orleans, France and The actual operation was completed in 24 days, 3 joined Schlumberger in 1982. Bernard has held various days earlier than planned. An average of 90% of the assignments in North Africa and the Far East before VSP levels were found suitable for first break coming to the Middle East in 1990. Bernard is a member detection, which provided accurate time-depth of the SPE and SEG and has published several papers in curves at all 9 wells. Geophone coupling quality is the field of VSP and sonic interpretation.

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Application of Neural Networks and Geostatistical Approach for Reservoir Characterization

Yoshioka, Katsuhei*, Nobusuke Shimada Technology Research Center of Japan National Oil Corporation, Japan and Yoshiro Ishii Middle East Representative Office of Japan National Oil Corporation, Bahrain

Geostatistics is recognized as the most powerful tool We also discuss validation and problems of the for reservoir characterization, integrating geological, approach, which is the combination of neural geophysical and reservoir engineering data. In networks and geostatistics, using blind tests by general, the information derived from well data is hiding some well data. precise but sparsely located for reservoir characterization. In such cases, seismic data are Katsuhei Yoshioka has 4 years of useful because they are uniformly distributed. exploration experience of which one However, it is a disadvantage of seismic data that its year was with JAPEX Geoscience relationships to reservoir properties are still not clear Institute Ltd. and 3 years with because of its limitation of frequency band width, Japan Petroleum Exploration Co. low S/N ratio, and ambiguous physical relationships Ltd. He has been working at the to reservoir properties. Thus, the relationships vary Technology Research Center of with region and with depth. Japan National Oil Corporation In order to deal with such an ambiguous relation, since 1993. Katsuhei has a BSc in geostatistical techniques, such as cokriging and co- Geophysics and a MSc in simulation, can integrate well data and seismic data Seismology from Kyoto University. in order to estimate the spatial distribution of reservoir properties. Especially, the co-simulation Nobusuke Shimada received his technique reproduces the equi-probable multi- BSc (1983) and MSc (1985) in realizations of the distribution. Geophysics from Tohoku This paper introduces the case study of reservoir University, Japan. Since joining characterization in an actual oil field. More than 20 Japan National Oil Company in attributes were extracted from 3-D seismic data. 1985, he has been working in project Since each of these attributes has only weak evaluations and geophysical correlation to reservoir parameters, the approach of surveys for Japanese and overseas neural networks was considered for application in projects. Nobusuke is currently an order to obtain a strong relationship between seismic Assistant Director of Geophysical Laboratory in Technical attributes and reservoir parameters from the well log Research Center of JNOC. His current interests are data. After which, we estimated the spatial reservoir geophysics and reservoir characterization. distributions and their uncertainties using geostatistical methods. Yoshiro Ishii (see Ishii et al., p. 151)

Identifying Hidden Reserves Through Visualization Technology Application

Zeitlin, Michael J. Texaco Exploration and Production, USA

Most oil fields have reserves which are "hidden" from difficult. Data examined in cross section often misses the well drilled to produce them. These untapped subtle oil containing compartments. 3-D volume compartments could yield upwards of 50% rendering, however, allows for very quick additional reserves throughout an oil field's examination of all the data collected. Pattern commercial life. 3-D seismic and 3-D visualization recognition programs help the eye see compartments technology can help identify these additional zones in 3-D data. Using 3-D visualization techniques, these by providing data at a much finer scale than was patterns can be revealed and related to the geologic possible using 2-D technology. model necessary for efficient production. 3-D seismic Conventional approaches to seismic data analysis analysis normally taking 6 weeks to complete is involved seismic line by seismic line examination of routinely done in less than a few days and with structural detail. Using 3-D seismic volumes, such higher accuracy. 2-D examination of data is very time consuming and

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Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/1/1/95/5406881/geo96.pdf by guest on 02 October 2021 Michael J. Zeitlin has been a units. He led the effort to develop the first commercial Portfolio Manager at Texaco since installation of a global standards database tied to 1994 in Integrated Reservoir visualization and reservoir characterization. He has Information and Visualization received Texaco's Outstanding Contributor Award in Technology. He has held previous 1993 and again in 1995 and has received other Texaco leadership positions with Texaco awards for bottom-line contribution. Before joining since 1980 in expert systems design, Texaco, Michael received a BSc and MSc degrees in Earth computer aided exploration and Science and Marine Science from the State University of hydrogeology. Over the past 6 New York at StonyBrook. He is an active member of the years, Michael has been the driving AAPG and the Institute of Electrical Engineers' Computer force behind Texaco's effort to acquire, develop and deploy Society. visualization technology throughout Texaco's business

Silurian-sourced Oils from the Arabian Plate

Zumberge, John E.* and Folke C. Johansson GeoMark Research, Inc., USA

Crude oils from the Arabian Plate generated from Silurian oil. Some eastern Turkey fields also contain Silurian source rocks were identified using stable oils of mixed Cretaceous carbonates and Silurian carbon isotope composition and distributions of shale origin. sterane and terpane biomarkers. Principal component and cluster analyses aided in John E. Zumberge received his BSc distinguishing oils sourced from Silurian shales in Chemistry from the University versus various Mesozoic carbonate-sourced oils and of Michigan and his PhD in crudes from Eocene marine shales. Silurian-sourced Geosciences from the University of oils from Saudi Arabia (reservoired mostly in Arizona in 1976. He was a Permian clastics) are isotopically light (-30 to -31‰; Research Associate in the C15+ saturate hydrocarbon fractions) while Upper Laboratory of Organic Geo- Jurassic carbonate oils are 2 to 3‰ more positive. chemistry at the University of Eastern Turkey Silurian oils (reservoired in Turonian Arizona from 1976 to 1979. From carbonates) are about 0.5‰ more positive than Saudi 1979 to 1985 he was employed by Arabian Silurian oils. Although Silurian oils contain Cities Service/Occidental Oil Company where he served low concentrations of biomarkers due to age and as Research Geochemist, Manager of Geochemical thermal maturity, their marine shale origin is Research, and Manager of Geological Research. In 1986 demonstrated by high rearranged to regular sterane he joined Ruska Laboratories in Houston as Vice President ratios, tricyclic terpane distributions typical of marine and General Manager. He was Director of Geochemistry shales, and relatively high diahopane to hopane for Core Laboratories until 1991 when he co-founded ratios. Turkish Silurian-sourced oils are less GeoMark Research, a company specializing in regional thermally mature than the Saudi oils as illustrated crude oil studies. by both absolute biomarker concentrations and maturity-sensitive terpane ratios. Permian- Folke C. Johansson received a reservoired condensates from Bahrain appear to have BSc, MSc and PhD in Geology from been derived from very mature Silurian sources the University of Wisconsin - based primarily on carbon isotope composition since Madison. After several years with biomarkers have been thermally degraded. Some Texaco working in the US Gulf oils from west central Oman and eastern Jordan also Coast he transferred to Aramco were generated from Silurian shales. A few Saudi where he spent 17 years in various Arabian fields such as Abu-Jifan, Qirdi, and Ghawar exploration positions including contain both Silurian oils in deeper reservoirs and Chief Geologist and Manager of Jurassic carbonate oils in shallower reservoirs. It is Geology. In 1982 he formed likely that Sharar and Faridah fields contain oils of Arabian Gulf Exploration Consultants, Inc. (AGECON) mixed Silurian shale and Upper Jurassic carbonate and has since been involved in numerous studies and origin in Middle Jurassic reservoirs. Other Upper exploration activities covering the entire Arabian Plate. Jurassic fields may contain a small percentage of

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