Verification of the Use of Completion-Location Analysis for Initial Assessment of Reservoir Heterogeneity

Ronald R. McDowell, Katherine Lee Avary, Michael E. Hohn, and David L. Matchen

In 1991, a technique (completion-location analysis) was developed for a U.S. DOE-funded study to give a preliminary assessment of field-scale reservoir heterogeneity in two West Virginia oil fields (Granny Greek and Rock Creek). The study's conclusions regarding heterogeneity agreed with initial predictions. However, as these fields were investigated specifically because they were thought to be heterogeneous, this test of the analysis was biased.

In 1995, as part of a proposal to study siliciclastic strandplain reservoirs, the Jacksonburg-Stringtown field in West Virginia, was selected because it met the depositional criterion and was still being actively produced. Completion- location analysis was undertaken on 214 producing oil wells from the field. Analysis indicated that drilling in the field is clustered into eight time periods (1890-1903, 1904-1911, 1912-1916, 1917-1934, 1935-1953, 1954-1975, 1976-1985, 1986-1995). Mapping of the locations of wells for each time period indicated that from 1890-1903 approximately 50% of the current geographic extent of the field was defined. Drilling in the periods 1935-1953, 1954-1975, 1975-1985, and 1986-1995 added significantly to the extent of the field - these episodes, especially 19 6-1995, represent the discovery of new production. On this basis, a preliminary prediction was made that Jacksonburg-Stringtown field should exhibit a relatively high degree of reservoir heterogeneity.

Subsequent discussions with the producer revealed that the reservoir varies considerably in pay thickness and quality across the field, has localized areas with high water injection rates and early water breakthrough, and has areas of anomalously high production. This suggests significant reservoir heterogeneity and appears to verify the utility of completion-location analysis.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California