Depositional History and Distribution of Reservoir Rocks in Chesterian Incised Valley Fill Pools: Examples from Shuck and Eubank Fields in Southwestern Kansas

John Youle and Martin Dubois

Estuarine sandstone reservoirs up to 140' thick have produced approximately 6.5 million and 7.8 million barrels of oil from both primary and secondary methods in the Eubank and Shuck pools, and are currently being investigated for their CO2 recovery potential. The reservoirs are housed within a valley that averages less than ½ mile in width, but has incised up to 220' into underlying Ste. Genevieve and St. Louis limestones and extends from south of the Oklahoma border northward for over 100 miles. The valley was filled with a variety of fluvial, salt marsh, tidal flat, and tidally dominated estuarine sediments during a cyclic sea-level rise. Traps in both pools are partially stratigraphic as reservoirs onlap and pinchout against valley walls; however, Oauchita folding completed the trap at Eubank, whereas the Shuck pool trap was sprung by karst collapse into Ordovician carbonates during the lower Middle Pennsylvanian. Core data from the pools were used to: 1) identify rock types and depositional environments, 2) identify sequence stratigraphic surfaces, 3) characterize suites of lithofacies by their physical attributes (k, phi, Sw, etc.) and by unique wireline log signatures (petrofacies), and 4) provide necessary calibration for facies mapping and reconstructing the depositional history of incised valley fill rocks in the pools. Although mostly minor in their impact upon production, stratigraphic, structural, and even diagenetic compartments have been identified within these pools. 

AAPG Search and Discovery Article #90176©AAPG Mid-Continent Meeting, Wichita, Kansas, October 12-15, 2013