The SPWLA Permian Basin Chapter

Luncheon and Learn
  Tuesday, June 30th
11:30 AM - 1:00 PM

"Geochemistry for Unconventional: Production Allocation, Reservoir Monitoring, and Hydrocarbon Phase (e.g., API Gravity, GOR) Prediction"
Mohammad "Wahid" Rahman, Ph.D

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Geochemistry data (source rock maturity, and it’s equivalent from oil/gas, bulk molecular compositions (GC) and biomarker (GCMS) ratios) from the extracts of cored or cutting samples vs produced oil from well head samples have been compared to predict oil family types, migration, mixing of hydrocarbon between various reservoired oil and gas, GOR (gas-to-oil ratio), and allocate production contribution to different reservoirs from many US on-shore basins (e.g., Anadarko, Permian, Eagle Ford and Rockies). Furthermore, the predicted GOR (gas-to-oil ratio) values from the same oil chemistry data are well matched with the produced GOR
and estimated GOR from the recombined fluid samples.

Molecular geochemistry data of rock cuttings/cored samples can be a cost-effective way to provide to better understanding of hydrocarbon composition and production contribution within a lateral well. Studies have shown that molecular chemistry data can be used via many statistical techniques to identify the end member contribution from different wells or from whole basin. But molecular chemistry (GC, GCMS) from a single well application to allocate production contribution is relatively less understood because of the failure to pinpoint the end member hydrocarbon from different horizons. A system of machine learning methods is used to evaluate each feature’s (e.g., molecular chemistry data) ability to discriminate samples and determine representative features showing variation between different formations or sublayers. Deep learning regression methods are used to quantify end member contributions to the commingled produced oil.

These case studies highlight many important ways in which geochemistry can be used to better evaluate unconventional reservoirs: 1) by identifying the existence and extent of hydrocarbon migration, 2) by predicting and understanding the quality and type of petroleum fluids stored in tight unconventional source rocks, 3) by explaining high GOR anomalies as the result of multiple charging episodes in certain areas in tight reservoirs and 4) finally to properly identify the host rock end members and allocate the production accordingly.

Dr. Mohammad “Wahid” Rahman is currently working as petroleum geochemist at Geoscience and Petroleum Research Corporation, Houston Texas, USA. Dr. Rahman has previously worked as Chief Geochemist at Paladin Geological Services, Edmond, TX, as Staff Geochemist at Pioneer Natural Resources, Irving, Texas and as Sr Geochemist at Devon Energy, Oklahoma City, OK. Dr Rahman has over 18 years of experience working in industry, academic, and research institutions in the field of geochemistry, geology, and petroleum engineering. Dr Rahman has provided geochemistry services for most of the North American onshore unconventional plays/basins, and conventional petroleum plays, through petroleum systems analysis and basin modeling, predicting behavior of reservoir fluids, PVT properties, production allocation, petrophysical and reservoir engineering model calibration, and reservoir characterization. His research interests include petroleum geochemistry, isotope geochemistry, aqueous geochemistry, mineral chemistry, HC migration pathway analysis, thermal maturity of organic matter (OM) and hydrocarbons (oil and gas), relationship between OM/hydrocarbon maturity versus Gas Oil Ratio (GOR), pressure gradient, kerogen/OM density, formation water geochemistry to better understand reservoir continuity, water resistivity (Rw), oil (So), gas (Sg), and water saturation (Sw). Dr. Rahman has over 45 conference papers, abstracts, and peer-reviewed articles published in various high impact factored journals (e.g., Nature Geoscience) in the field of geochemistry, geology, and fluid chemistry and transport modeling. He received his Ph.D. in Organic Geochemistry from Southern Illinois University, Carbondale, Illinois; M.S. in Geology from Auburn University, Auburn, Alabama; and M.S. and B.S. in Geology from University of Dhaka, Dhaka, Bangladesh.


The Permian Basin Chapter of SPWLA

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