Abstract: Reservoir Management Techniques Applied in East Randolph Field, Portage County, Ohio: Final Results

SAFLEY, L. EUGENE

Since 1992, the East Randolph Field has produced over 450,000 stock tank barrels of oil and 1.2 billion cubic feet of gas from the Cambrian Rose Run formation. Declining reservoir pressure and field development alternatives dictated the need for a comprehensive reservoir management strategy to improve operational economics and optimize oil recovery.

Log, core, and petrographic analyses indicate that the reservoir quality of the Rose Run is dependent on sandstone diagenesis and dolomite cementation. Fracturing plays only a minor role in fluid movement. Based on log and fluid analyses, Rose Run zone 2 has a high gas saturation, and a primary gas cap may have been present prior to field development. Special core analyses suggest that production performance, which is affected by paraffin precipitation in the pore spaces, may be enhanced by chemical or microbial treatments. Log analyses and reservoir mapping illustrate the improved interpretation of reservoir heterogeneities and sandstone body distribution.

Volumetric and material balance calculations more than double original oil-in-place reserve estimates for the field from 4.4 to 11 million barrels. Results of full-field pressure history match indicate that the reservoir is in pressure communication between wells and not compartmentalized by faulting. Based on relative permeability measurement and reservoir simulation, waterflooding should not be considered a technically or an economically viable improved recovery process. Instead, gas re-injection will result in stabilization of reservoir pressure and incremental oil recovery of 8% of original oil-in -place.

AAPG Search and Discovery Article #90939©1997 AAPG Eastern Section and TSOP, Lexington, Kentucky