An integrated study of the Grayburg/San Andres Reservoir, Foster and South Cowden Fields, Ector County, Texas. Annual report, August 1, 1996--July 31, 1997

The objective of this two-phase study is to demonstrate an integrated methodology for reservoir characterization of shallow shelf carbonate reservoir that is feasible, and cost effective for the independent operator. Furthermore, it will provide one of the first public demonstrations of the enhancement of reservoir characterization using high-resolution three dimensional (3D) seismic data. This particular project is evaluating the Grayburg and San Andres reservoirs in the Foster and South Cowden Fields, Ector County, Texas. This 68 year old field was approaching its economic limit and the leases evaluated would have been abandoned in 10 years. A multidisciplinary approach to waterflood design and implementation, along with the addition of reserves by selective infill drilling and deepening, is being applied to this field. This approach in reservoir development will be applicable to a wide range of shallow shelf carbonate reservoirs throughout the US. The first phase of the project included the design, acquisition, and interpretation of the 3D seismic survey, the collection and evaluation of geologic (core and log) data, and engineering (historical production, well test, injection) data from a variety of sources. From this work, a geologically based production history model was simulated. Based on the recommendations made at the end of Phase One, three new wells were drilled, one existing well was deepened, two wells were worked over, one TA`d well was re-entered, and one well was converted to injection. In addition, the quality of the injection water was greatly improved, a step necessary prior to increasing injection in the project area. The realignment of the waterflood and all additional well work await the completion of the seismic based history match and engineering simulation