Channel Sandstone Oil Reservoirs of Pennsylvanian Age, Northwestern Ness County, Kansas: ABSTRACT

Abstract

Channel sandstones of Pennsylvanian (Desmoinesian, Cherokee) age are unusual oil reservoirs in T17S, R24W, Ness County, Kansas. A thickness map of the interval from an overlying marine marker, the Fort Scott Limestone, to the underlying Mississippian carbonate rocks depicts the topography of a former land surface now buried 4,400 ft (1,340 m) deep. Where the mapped interval exceeds 125 ft (38 m) sandstone deposits fill incised paleovalleys. The sandstones are interpreted as channel-fill sandstones because of: (1) their position filling sinuous valleys; (2) their cross-section shape, convex base, and flat upper surface; (3) their dimensions--to 60 ft (18 m) thick, one-fourth mi (0.4 km) wide, and over 6 mi (9.6 km) long; (4) the coarsening downward from very fine quartz grains to coarse sand and pea gravel at the base; (5) the enhanced permeability (over one darcy) near points of change of valley direction (point-bar deposits?); (6) the common presence of 10 to 20° dips and cross-bedding in cores; (7) the lateral gradational mixing of quartz sand with residual cherts. Greenish clay is present in the upper fine-grained sandstones and glauconite in the lower coarse sandstones. Six wells encountered isolated sandstone lenses (pressure decline on drill-stem tests) and produced only 7,131 bbl of oil per well before abandonment. The other 28 wells produce oil from channel sandstone reservoirs with water drive. Over 100,000 bbl of oil per well (40 acre or 16 ha. spacing) will be recovered from them. It is estimated that the 17 best wells (50% of the wells) will have gross ultimate production of 164,000 bbl of oil per well. Prospecting for channel-sandstone oil reservoirs is hazardous with 43 dry holes surrounding the 34 channel-sandstone oil wells. End_of_Article - Last_Page 2120------------