Improved Oil Recovery from Upper Jurassic Smackover Carbonates through the Application of Advanced Technologies at Womack Hill Oil Field, Choctaw and Clarke Counties, Eastern Gulf Costal Plain

Pruet Production Co. and the Center for Sedimentary Basin Studies at the University of Alabama, in cooperation with Texas A&M University, Mississippi State University, University of Mississippi, and Wayne Stafford and Associates proposed a three-phase, focused, comprehensive, integrated and multidisciplinary study of Upper Jurassic Smackover carbonates (Class II Reservoir), involving reservoir characterization and 3-D modeling (Phase I) and a field demonstration project (Phases II and III) at Womack Hill Field Unit, Choctaw and Clarke Counties, Alabama, eastern Gulf Coastal Plain. Phase I of the project has been completed. The principal objectives of the project are: increasing the productivity and profitability of the Womack Hill Field Unit, thereby extending the economic life of this Class II Reservoir and transferring effectively and in a timely manner the knowledge gained and technology developed from this project to producers who are operating other domestic fields with Class II Reservoirs. The major tasks of the project included reservoir characterization, recovery technology analysis, recovery technology evaluation, and the decision to implement a demonstration project. Reservoir characterization consisted of geoscientific reservoir characterization, petrophysical and engineering property characterization, microbial characterization, and integration of the characterization data. Recovery technology analysis included 3-D geologic modeling, reservoir simulation, and microbial core experiments. Recovery technology evaluation consisted of acquiring and evaluating new high quality 2-D seismic data, evaluating the existing pressure maintenance project in the Womack Hill Field Unit, and evaluating the concept of an immobilized enzyme technology project for the Womack Hill Field Unit. The decision to implement a demonstration project essentially resulted in the decision on whether to conduct an infill drilling project in Womack Hill Field. Reservoir performance, multiwell productivity analysis, and reservoir simulation studies indicate that water injection continues to provide stable support to maintain production from wells in the western unitized area of the field and that the strong water drive present in the eastern area of the field is adequate to sustain production from this part of the field. Although the results from the microbial characterization and microbial core experiments are very promising, it is recommended that an immobilized enzyme technology project not be implemented in the Womack Hill Field Unit until live (freshly taken and properly preserved) cores from the Smackover reservoir in the field are acquired to confirm the microbial core experiments to date. From 3-D geologic modeling, reservoir performance analysis, and reservoir simulation, four areas in the Womack Hill Field were identified as prospective infill drilling sites to recover undrained oil from the field. It was determined that the two areas in the unit area probably can be effectively drained by perforating higher zones in the Smackover reservoir in currently producing wells. The two areas in the eastern (non-unitized) part of the field require the drilling of new wells. The successful drilling and testing of a well in 2003 by J. R. Pounds, Inc. has proven the oil potential of the easternmost site in the non-unitized part of the field. Pruet Production Co. acquired new 2-D seismic data to evaluate the oil potential of the westernmost site. Because of the effects of a fault shadow from the major fault bounding the southern border of the Womack Hill Field, it is difficult to evaluate conclusively this potential drill site. Pruet Production Co. has decided not to drill this new well at this time and to further evaluate the new 2-D seismic profiles after these data have been processed using a pre-stack migration technique. Pruet Production Co. has elected not to continue into Phase II of this project because they are not prepared to make a proposal to the other mineral interest owners regarding the drilling of new wells as part of an infill drilling program at this time. Pruet is integrating the reservoir characterization, 3-D geologic modeling, reservoir performance analysis, and reservoir simulation results of the project into their field-scale reservoir management strategy for the Womack Hill Field to improve field operations