Integrated Reservoir Interpretation Reservoir management, integrated data interpretation, multidisciplinary asset teams, synergy—these are the buzzwords of modern reservoir engineering. They point to the efficient use of all types of data to better understand reservoirs and to ultimately produce more hydrocarbon less expensively. But is vision outpacing the tools available? We describe how better reservoir understanding is being achieved in practice. Ed Caamano Every field is unique, and not just in its geol- disciplines work together, hopefully in close Ken Dickerman ogy. Size, geographical location, production enough harmony that each individual’s Mick Thornton history, available data, the field’s role in expertise can benefit from insight provided Conoco Indonesia Inc. overall company strategy, the nature of its by others in the team. There is plenty of Jakarta, Indonesia hydrocarbon—all these factors determine motivation for seeking this route, at any how reservoir engineers attempt to maxi- stage of a field’s development. Reservoirs Chip Corbett mize production potential. Perhaps the only are so complex and the art and science of David Douglas commonality is that decisions are ultimately characterizing them still so convoluted, that Phil Schultz based on the best interpretation of data. For the uncertainties in exploitation, from Houston, Texas, USA that task, there is a variability to match the exploration to maturity, are generally higher fields being interpreted. than most would care to admit. Roopa Gir In an oil company with separate geologi- In theory, uncertainty during the life of a Barry Nicholson cal, geophysical and reservoir engineering field goes as follows: During exploration, Jakarta, Indonesia departments, the interpretation of data tends uncertainty is highest. It diminishes as to be sequential. Each discipline contributes appraisal wells are drilled and key financial Dwi Martono and then hands over to the next discipline. decisions have to be made regarding expen- Joko Padmono At the end of the line, the reservoir engineer sive production facilities—for offshore Kiagus Novias attempts to reconcile the cumulative under- fields, these typically account for around Sigit Suroso standing of the reservoir with its actual 40% of the capital outlay during the life of Pertamina Sumbagut behavior. Isolated from the geologist and the field. As the field is developed, uncer- Brandan, North Sumatra, Indonesia geophysicist who have already made their tainty on how to most efficiently exploit it contributions, the reservoir engineer can diminishes further. By the time the field is Gilles Mathieu play with parameters such as porosity, satu- dying, reservoir engineers understand their Clamart, France ration and permeability, but is usually field perfectly. barred, because of practical difficulties, from A realistic scenario may be more like this: Zhao Yan adjusting the underlying reservoir geometry.1 During exploration, uncertainty is high. But China National Petroleum Company This scenario is giving way to the inte- during appraisal, the need for crucial deci- Beijing, China grated asset team, in which all the relevant sions may encourage tighter bounds on the reservoir’s potential than are justifiable. For help in preparation of this article, thanks to Tom In this article, ELAN (Elemental Log Analysis), Finder, Later, as the field is developed, production Bundy, Conoco Indonesia Inc., Jakarta, Indonesia; Gilles Fortress (Formation Reservoir Test System), GeoFrame, fails to match expectations, and more data, Bitoun and Rune Hope, Total Indonesie, Jakarta, Indone- Geopulse, Geoshare, GeoViz, IES (Integrated Exploration sia; Dharmawan Samsu, Arco, Jakarta, Indonesia; Bill System), LogDB, MeshBuilder, ModelBuilder, RFT for example 3D seismic data, have to be Harmony, Gerry Dyer and John Rice of Maxus, Jakarta, (Repeat Formation Tester), RM (Reservoir Modeling) TDT acquired to plug holes in the reservoir Indonesia; Ron Boulter, Beijing, China; John Bradfield, (Thermal Decay Time) and WellTie are marks of Schlum- understanding. Uncertainties begin to Abraham Baktiar and Ron Mobed, GeoQuest, Jakarta, berger; Eclipse is a mark of Intera ECL Petroleum Tech- Indonesia; Hashem Bagherpour, Mustafa Biterge, Gra- nologies; Excel is a mark of Microsoft Corporation; Sig- increase rather than diminish. They may ham Bunn, Andrew Carnegie, Metin Karakas, Bahman maView is a mark of Western Atlas; Zycor is a mark of even remain high as parts of the field Samimi, GeoQuest, Dubai, United Arab Emirates; Ben Landmark Graphics Corp. become unproducible due to water break- Lovell, Simon Robson, Steve Simson and Robert 1. For an overview of reservoir management: Sorensen, GeoQuest, Gatwick, England; Christine through and as reservoir engineers still Briggs P, Corrigan T, Fetkovich M, Gouilloud M, Lo T- Economides, Schlumberger, Houston, Texas, USA; Dou- w, Paulsson B, Saleri N, Warrender J and Weber K: struggle to fathom the field’s intricacies. glas Gray-Stephens, Schlumberger Cambridge Research, “Trends in Reservoir Management,” Oilfield Review 4, Cambridge, England. no. 1 (January 1992): 8-24. Oilfield Review 50 Lake Baikal MONGOLIA KAZAKHSTAN Karamay Zger basin Urumqi XINJIANG Kashgar Tarim basin GANSU ery, to simply estimating the reserves in a new discovery about to be exploited. QUINGHAI Whatever the scenario, the tactic of string- ing together diverse packages creates several 500 km problems. First is data compatibility. Since 0 500 Miles the industry has yet to firm up a definitive geoscience data model, each package is nXinjiang province in western China, where the RM Reservoir Modeling package has likely to accept and output data in slightly been selected for several oil fields. Since the early 1990s, China National Petroleum different ways (see “Managing Oilfield Data Company (CNPC) has placed increased emphasis on reservoir characterization to bet- Management,” page 32). This forces a cer- ter estimate field reserves and to optimize development drilling. Xinjiang province is best known for the Tarim basin, the largest basin in the world tain amount of data translation as the inter- still awaiting significant exploration. The RM package is being deployed farther north pretation moves forward—indeed, a small in the Zger basin that contains the large Karamay oil field. Three new fields have been industry has emerged to perform such trans- recently discovered here and the RM package coupled with GeoQuest seismic interpre- lation. Second, the data management system tation software played a key part in their discovery. Two of these fields are currently undergoing development drilling, and the drilling success rate has exceeded 90%. supporting this fragmented activity must somehow keep track of the interpretation as Asset teams go a long way toward maxi- For example, this could be the worksta- it evolves. Ideally, the reservoir manager mizing understanding of the reservoir and tion/package lineup for XYZ Oil Company: needs to know the history of the project, placing a realistic uncertainty on reservoir • GeoQuest’s IES Integrated Exploration who made what changes, and if necessary behavior. They are the best bet for making System for seismic interpretation how to backtrack. Third, and most impor- most sense of the available data. What they • Landmark Graphics Corp.’s Zycor map- tant, the tactic of stringing together frag- may lack, however, are the right tools. ping package for mapping mented packages discourages integrated Today, interpretation is mainly performed on • Western Atlas’ SigmaView package for interpretation. Crudely put, as the interpreta- workstations with the raw and interpreted seismic inversion tion progresses, putting things into reverse is data paraded in its full multidimensionality • Stratamodel Inc.’s package for geological always more of a hassle than continuing to on the monitor. Occasionally, hard-copy model building and 3D visualization move forward. It takes an iron will to accept output is still the preferred medium—for • GeoQuest’s GeoFrame platform for petro- that anomalous production data may mean example, logs taped to walls for correlating physical log interpretation going back to the beginning and rethinking large numbers of wells. • Intera’s PVT analysis, gridding and Eclipse the basic reservoir description. There are workstation packages for 3D simulation packages for reservoir engi- The answer to all these problems is a fully seismic interpretation, for mapping, for neering integrated package that performs most, if viewing different parts of the reservoir in • GeoQuest’s Finder package for database not all, the functionality listed above for three-dimensions, for petrophysical interpre- management XYZ Corporation, a package that is easy to tation in wells (see “Beating the Exploration • Microsoft Corporation’s Excel spreadsheet load with data and that keeps the data Schedule with Integrated Data Interpreta- program for collating data and making together in a unified format, a package that tion: Cam Oil’s Experience,” page 10), for reserve estimates. tracks the progress of the interpretation, a performing geostatistical modeling in Any number of combinations is possible. package that is easy to use, and, finally, a unsampled areas of the reservoir, for creat- The choice depends on oil company prefer- package that in its construction draws geol- ing a grid for simulation, for simulating ences, the history of the field and the prob- ogist, geophysicist, petrophysicist and reser- reservoir behavior,