--> --> Assessing Sealing Capacity by Integrating Core-Measured Mercury Injection Capillary Pressure Data and Well Logs

AAPG Middle East Region, Second EAGE/AAPG Hydrocarbon Seals of the Middle East Workshop

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Assessing Sealing Capacity by Integrating Core-Measured Mercury Injection Capillary Pressure Data and Well Logs

Abstract

Seal integrity becomes increasingly important and is one of the key risks for exploring subtle and stratigraphic traps. This article focuses on assessing sealing capacity by integrating core-based rock types, core-measured mercury injection capillary pressure (MICP) data, and well-logs of Jurassic carbonate reservoir and seal rocks. A total of 1892 core plugs representing Jurassic rock facies (e.g., sealing and reservoir rocks) were acquired for thin-section petrographic analysis and MICP data. Additionally, calibrated seismic facies modeling using 3-D seismic volumes was conducted for identifying potential stratigraphic traps. The workflow involves four parts: (1) Core-based rock typing for selected Jurassic carbonate reservoir and seal facies by integrating core descriptions, thin-section petrography, core plug porosity/permeability, and MICP data; (2) Processing core-derived MICP data, and calibration with well-log responses using electrofacies prediction technique, allowing the prediction of Pore-throat Size Distribution (PSD) and Critical Pore Aperture; (3) Computing a continuous log quantifying the “Maximum Allowable Hydrocarbon Column” (MAHC), i.e. the seal efficiency threshold index; and (4) Upscaling the derived electrofacies and MAHC log into coarser-scaled facies assemblages that are seismically detectable, which are used as inputs for calibrated seismic facies classification modeling. The calibrated seismic facies, rock types and porosity models resulted in much more accurate prediction of lateral and vertical facies changes of reservoirs and seals within 3D volumes. Petrographic and diagenetic examinations provided further insights for seal integrity assessment. Well-to-well correlation and mapping of the PSD and MAHC logs for a given stratigraphic play are performed to locate the major vertical barriers of regional extent. This integrated approach resulted in identifying potential stratigraphic traps such as the Upper Fadhili and Arab-D plays. The outcome of this case study has also provided valuable insights for mitigating risks for new stratigraphic trap opportunities within the Jurassic stratigraphic intervals throughout the Kingdom of Saudi Arabia.