Red Fork and Lower Skinner Sandstones in Northwest Tecumseh Field, Pottawatomie County, Oklahoma: ABSTRACT

Abstract

The Northwest Tecumseh field, discovered in 1978, produces from the Pennsylvanian Skinner and Red Fork sandstones at 4800 ft. The 50 wells had produced 6.4 million bbl of oil and 20.8 bcf of gas through 1986. The field is 4.5 mi long, 3/4 mi wide, and the vertical section contains up to 132 ft of sandstone with greater than 10% porosity. These stacked, interconnected north-northeast-trending, channel-fill sandstones are part of a much larger fluvial/distributary system. These channels flowed to the north and cut down into underlying, fossiliferous, carbonate-bearing marine shale. A pre-Pennsylvanian structural low, trending north-northeast, existed in the southern half of the field and created a predisposition for the channel trend which continued through Red Fork and Skinner deposition. The north-northeast-trending sandstone complex, parallel with present-day regional structural strike, provides the excellent configuration for this efficient stratigraphic trap. The northern end of the field is marked by bifurcation of the channel complex and by the crosscutting of a younger clay-filled channel. Despite the lenticularity of the sandstone sequence, there appears to be a uniform gas-oil contact and minor southwestward tilt of the oil-water contact in the south part of the pool. The primary reservoir energy is provided by amore » dissolved gas drive, with some assistance from the 60-ft gas cap. The vertical oil column is 80 ft. These reservoir sandstones are fine-grained quartzarenites, and the dissolution of ferrodolomite has increased porosities up to 21%. Kaolinite is the predominant clay mineral and has a tendency to migrate and reduce permeability during production.« less