Abstract Significant reserves of oil and gas have been established in the western Kansas—western Nebraska region. The major oil and gas provinces of this region are the Central Kansas uplift and the Hugoton embayment, respectively. Of the known oil reserves, approximately 2.2 billion bbl had been produced to 1968. The Central Kansas uplift alone has produced about 2 billion bbl, and of this amount it is estimated that nearly 70 percent was obtained from the Arbuckle Group. In the Kansas part of the Hugoton embayment Wolfcampian rocks had produced 9.4 trillion cu ft of gas to 1968, which accounts for about 60 percent of the 15.5 trillion cu ft produced in the state. It does not appear, however, that Arbuckle and Wolfcampian rocks will be sources of significant new oil and gas reserves in the western Kansas—western Nebraska region. Both of these units have been explored and developed for more than 40 years, and their productive limits seem to be well defined. Outside the Hugoton embayment, Wolfcampian rocks have been penetrated by many wildcat and development wells which did not find production. Away from the Central Kansas uplift, Arbuckle rocks have been tested on several structures but results have not been encouraging.

Abstract In west-central Kansas the Cherokee Group of early Desmoinesian, Pennsylvanian age is a mixed siliciclastic and carbonate sequence. It was deposited in environments that were transitional from continental to marginal marine as the sea transgressed over the Mississippian unconformity out of the Hugoton Embayment and onto the Central Kansas Uplift. Sandstones of the Cherokee Group are important oil reservoirs in west-central Kansas, but they are highly variable in properties and in aerial distribution; therefore, they are difficult to predict. Core studies and subsurface analysis using wireline logs reveal two persistent and widespread limestone beds that form useful stratigraphic markers within the Cherokee. They provide a framework for facies analysis and regional mapping that may be useful as a predictive tool for oil exploration. Six basic lithofacies are interpreted from lithologies and sedimentary structures observed in cores obtained from four wells in eastern Ness County: (1) basal Pennsylvanian conglomerate, (2) fluvial sands, (3) fine-grained tidal-flat deposits, (4) shallow marine limestones and shales, (5) shoreline sands and tidal-channel sands, and (6) braided-stream sandy conglomerates. Successions of these facies are equivalent to components commonly observed in Kansas cyclothems. Two transgressive-regressive cycles are identified in the Cherokee, and maximum transgression is correlated with the basal portion of the two widespread limestone beds. Following burial of the Mississippian karstic surface, deposition of peritidal sediments occurred on a uniformly shallow platform. Sedimentation was punctuated by episodes of subaerial exposure and weathering. Clastics derived from the eroding Central Kansas Uplift were probably supplied episodically to the coastal plain by braided streams that were reworked by coastal processes.