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Characterization of Fractures in a Lower Cretaceous Carbonate Formation, Onshore Abu Dhabi

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Characterization of Fractures in a Lower Cretaceous Carbonate Formation, Onshore Abu Dhabi GEO 2000 Abstracts authored and co-authored more than 15 papers. Azhari is Characterization of Fractures in a Lower interested in carbonate diagenesis, basin analysis, and deep Cretaceous Carbonate Formation, Onshore sedimentary basin diagenetically induced sealing and Abu Dhabi compartmentation. Azhari Abdalla, Fernando Silva is a Reservoir Abu Dhabi Company for Onshore Oil Operations Geologist and Geomodeller with Fernando Silva, PARTEX, Lisbon Petroprimo S.A., Lisbon, Portugal. Andrew Mann and Gill Scott, Robertson Research, UK. He received a BSc (1990) in Geology from Lisbon University–FCUL, and Integrated diagenetic, structural, lithological and facies a MSc (1998) in Reservoir Evaluation association data were used to assess the distribution and and Management from Heriot-Watt orientation of fractures and their impact on reservoir quality University, Glasgow. He has worked of a Lower Cretaceous carbonate formation in the ‘A field’, on various aspects of reservoir onshore Abu Dhabi. The formation is composed of several, geology in different geological relatively thin porous carbonate reservoirs interbedded settings in the Middle East, Africa, Europe, and Kazakstan. between thicker dense limestone intervals. Most observed His work has included research and development of natural fractures are cemented and their distribution seems fractured reservoir characterization techniques and to be influenced by the type of host lithology and proximity reservoir modeling studies in both carbonate and clastic to fault zones. Fracture density is highest in stylolitised dense settings. Fernando’s interests are focused on reservoir zones in the tight and dense carbonate intervals, and is characterisation and data integration, the application of commonly low in the porous carbonates. Several diagenetic numerical geology and quantitative techniques to the processes such as dissolution, fracture cementation and modeling of reservoirs, and visualization technologies. He cement replacement have played a role in the evolution of is a member of SPE, EAGE, PESGB, and AAPG. fracture networks and their distribution. The major types of fracture cements are anhydrite and calcite (early cements) Andrew Mann is Co-ordinator of the and dolomite and fluorite (late cements). Anhydrite cement Structural Geology Group at in fractures was partially replaced by calcite and later Robertson Research International. dolomite. He has a BSc and PhD from the University of Wales (Cardiff). Andrew Natural fractures in the studied formation can be classified has 18 years petroleum exploration into four main types based primarily on the degree of fracture experience and has been involved in continuity and size observed on the core samples. These are modeling studies of fractured small-scale faults, macro-fractures, meso-fractures, and carbonate and clastic reservoirs micro-fractures. Fracture orientations are predominantly throughout the Middle East. Prior to perpendicular to the field axial trend and vary from west- joining Robertson, he worked as a field geologist northwest to northwest. These trends are sub-parallel to the undertaking a number of mapping projects for petroleum mapped seismic faults located adjacent to several wells exploration in thrust belts (Oman Mountains and Southeast drilled in the field, and parallel to underlying basement Turkey) and in extensional and strike-slip settings (Arctic lineaments interpreted from potential field data. Macro- Region and Europe). He is a member of the Geological fractures and faults may constitute linked, fluid conductive Society of London. systems with some potential for connectivity and communication both within and between reservoir zones. Gill Scott has a PhD from Southampton University, UK in Azhari Abdalla is Lead Geologist Carbonate Sedimentology. She joined with Abu Dhabi Company for Robertson in 1982 and has worked Onshore Oil Operations (ADCO). He extensively on the carbonate has 20 years of experience in the oil reservoirs of the Middle East. Her industry and related research in particular expertise is in Lower Sudan rift basins, in the Anadarko Cretaceous and Upper Jurassic and Gulf Coast basins of Oklahoma reservoirs. She has studied them and Texas, and, currently, in the regionally for new exploration extensive carbonate platform of UAE. opportunities and in detail for reservoir appraisal and He has a MSc in Sedimentary production. Gill is particularly interested in the upscaling Diagenesis. He has presented several papers at the Denver of reservoir geology for reservoir characterization and AAPG Hedberg conference and OGS in Oklahoma, and has reservoir modeling and simulation studies. 8 Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/5/1/8/4553260/geo2000.pdf by guest on 29 September 2021 GEO 2000 Abstracts Seismic Fracture Detection using Multi-Azimuthal Walk-Away and Walk-Around Vertical Seismic Profile (VSP) Data, West Kuwait Salah Abdul Malek, Kuwait Oil Company, Andrew Hill, Colin Slater, BP Kuwait and Frank Wijnands, Schlumberger, Saudi Arabia The Najmah and Sargelu formations in West Kuwait are a on velocity survey, and five years as a Seismic Interpreter Middle Jurassic fractured carbonate source-rock system, (3 years as a Development Geophysicist and 2 as an producing light oil via an extensive fracture network. Exploration Geophysicist). Salah is currently interpreting Existing geological fracture models based on the variable Abduliyah and Dharif 3-D surveys. well data have proven unreliable in predicting open fracture distribution. A joint Kuwait Oil Company/BP study was Andrew Hill is a Senior Geophysicist begun in late 1997 to determine if a reliable fracture currently working with BP Kuwait. distribution model could be derived using estimates of He has 16 years experience gained azimuthal anisotropy from existing compressional P-wave with BP Amoco in a variety of seismic data. To provide calibration of the seismic response development and production to fracturing observed in wells, a multi-azimuth walk-away reservoir description roles in the vertical seismic profile (MAWAVSP) was designed and North Sea, Alaska, and the Middle acquired in a shut-in well. The MAWAVSP used a 5-level East. Major interests include receiver tool at two depth settings; one across the evaporite integration of subsurface and cap rock and the second within the fractured reservoir. dynamic data in the production Vibroseis walk away lines were acquired at each depth environment, geocellular modeling methods, seismic setting at 45° azimuths around the well and up to 4 kilometer attribute and rock property/fluid analysis, and seismic offset from the well-head. Additionally, walk-around data fracture characterization. Andrew received a BSc in Geology were acquired every 9° around the well between 2 kilometer from the University of Southampton in 1982 and a MSc in and 2.5 kilometer offset. The walk-away and walk-around Geophysics from Durham University in 1983. data have been analysed for azimuthal anisotropy variations in P-wave velocity and amplitude (AVO and AVOA). Colin Slater is currently working as a Geophysicist for BP Kuwait. He The velocity analysis indicates that the evaporitic cap rock, has four years industry experience which is dominated by ductile salt, has negligible anisotropy. with BP Amoco Exploration and However, significant velocity anisotropy is observed in the Geco-Prakla working on seismic Najmah/Sargelu reservoir interval. The fast-velocity processing and modeling projects azimuth aligns with the direction of maximum horizontal including surface-seismic and VSP stress and the dominant open fracture orientation from core detection of fractures, 3-D seismic and log data. Azimuthal variations in amplitude measured repeatability, and AVO analysis. His on intra-reservoir reflectors are also seen at offsets present interests include seismic anisotropy, in the existing surface seismic data. Seismic velocity and direct detection of hydrocarbons, and multi-component AVOA modeling studies have been undertaken to assess seismic processing. He has a BSc and PhD in Geophysics whether the level of anisotropy observed in the vertical from the University of Edinburgh. seismic profile (VSP) is detectable on the existing surface seismic data. However, seismic data quality, the number and Frank Wijnands is a Senior spacing of available seismic lines, as well as their azimuthal Geophysicist with Schlumberger distribution, ultimately controls whether anisotropy methods Wireline and Testing in Al Khobar, can reliably predict open fracture distribution in West Saudi Arabia. He has 10 years Kuwait. experience in the oil industry. Previous assignments were with Salah Abdul Malek is a Senior Geco-Prakla and GeoQuest in The Geophysicist with Kuwait Oil Hague and Aberdeen, specializing in Company (KOC). Salah received a surface and borehole seismic BSc in Geology from Kuwait methods. Frank has a MSc in University. He has 10 years Exploration Geophysics from the State University of Utrecht, experience with KOC. He has worked The Netherlands. for three years as a Wellsite Geologist, two years as a Supervisor 9 Downloaded from http://pubs.geoscienceworld.org/geoarabia/article-pdf/5/1/8/4553260/geo2000.pdf by guest on 29 September 2021 GEO 2000 Abstracts Thomas Aigner studied Geology at Epeiric Versus Layer-Cake Stratigraphic the universities of Stuttgart, Models for Middle East Carbonates: Lessons Tübingen, Reading, and Miami, and for Future Exploration from the German received his PhD in 1985. From
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