Reservoir Modeling and Simulation of a Middle Eastern Carbonate Reservoir

Michael J. Sibley, James V. Bent Jr., Darrell W. Davis, Ben Wang

Over 600 MMBO has been produced from a carbonate reservoir on the Arabian peninsula. The dominant lithologies are grain rich Lower Cretaceous limestones. Primary and secondary porosity types are present. A major, post-structural, stratigraphically cross-cutting, diagenetic barrier to fluid flow has been identified. By restricting aquifer support, significant production induced pressure depletion has occurred above this nearly horizontal barrier, resulting in a pressure differential exceeding 800 psi 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 and barrier units. These units reflect both depositional and diagenetic history, and are defined on the basis of cross-discipline data. Among these data are core and thin sections, core analyses, seismic, isotope, open-hole logs, TDTs, RFTs, field pressure surveys, oil and water production data, and production tests.

Through reservoir simulation of the geologic model, an excellent production and pressure (lateral and vertical) match of the field was obtained. Prediction 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.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995