ABSTRACT

An estimated 43.5 million barrels of oil and 128.8 billion cubic feet of gas have been produced from Knox reservoirs in Ohio since 1959. Of this, approximately 37.7 million barrels were produced from the Morrow Consolidated field since 1959, and 1.4 million barrels were produced from the Birmingham-Erie field since 1966. Since 1989, an additional 4.43 million barrels of produced oil have been reported from Rose Run and Copper Ridge reservoirs outside of the Morrow Consolidated and Birmingham-Erie fields. Producing Knox reservoirs in ascending stratigraphic order include the "B-zone" of the Copper Ridge ("Trempealeau") dolomite, "Krysik" sandstone of the Copper Ridge dolomite, upper Copper Ridge sandstones, Copper Ridge dolomite, Rose Run sandstone, and Beekmantown dolomite.

Historically, secondary recovery operations in Knox reservoirs have been conducted in localized areas of the Morrow Consolidated field in Morrow County and also in the Birmingham-Erie field in Erie County. In 1963, Ashland Oil Company attempted a waterflood operation in the Morrow Consolidated field in the Orrie Meyers lease unit, which resulted in limited success. Pathways created by vuggy porosity and possible fractures in the Copper Ridge dolomite resulted in early breakthrough of injected water to the producing wells. In 1965, gas injection also was conducted by Ashland Oil Company in the Morrow Consolidated field in the W. E. Long lease. Normal decline was arrested in the Copper Ridge dolomite and production increased as a result of gas injection. In 1974, Sun Oil Company initiated a successful waterflood in the "Krysik" sandstone in the Birmingham-Erie field in Erie County, Ohio. A Rose Run waterflood project, partially funded by the Department of Energy, is currently under evaluation by Belden and Blake Corporation and BDM Corporation-Oklahoma in the Randolph field in Portage County.

Based upon reservoir characteristics, cumulative oil production, decline curves, and initial gas-oil ratios, localized areas in Ohio indicate good potential for secondary oil recovery from Knox reservoirs. Oil production and reservoir characteristics of sandstones in the upper Copper Ridge dolomite indicate potential for enhanced oil recovery in the Canaan-Wayne field in Wayne County. The porous and permeable Rose Run sandstone is an attractive target for secondary recovery in oil prone areas which are associated with significant paleotopographic or fault-related structures. Significant oil production from the Copper Ridge dolomites also have potential for secondary recovery. The irregular nature of the vuggy porosity and local fracture orientations need to be better understood to prevent production problems from early breakthrough of injection waters. The successful waterflood of the Birmingham-Erie field may be used as a model for future field discoveries in the localized "Krysik" sandstone in north-central Ohio.