Recent work on the St. Louis Limestone in southwestern Kansas has demonstrated that these units contain a significant eolian facies component (up to 80-90% of total unit thickness). Reservoir intervals within the St. Louis are confined to relatively thin subtidal grainstones that, in turn, are capped by a muddy carbonate and shale facies. Critical to exploration and development of these grain-shoal reservoirs is an understanding of their spatial and stratigraphic distribution. Core through the St. Louis and St. Genevieve limestones has been examined and features have been recognized at the top of the eolianites. These surfaces are interpreted as long-term exposure surfaces. The contact between the subtidal grainstone shoals and the overlying muddy carbonate and shale facies is relatively sharp and is interpreted as representing a flooding surface separating shoal from muddy-open shelf facies. In the St. Louis Limestone, the subtidal carbonate grainstone reservoir intervals consist of primary interparticle porosity. Initial geologic models have viewed the reservoir zone as a single blanket-like layer with small structures and relatively random changes in facies thickness. However, a detailed integrated analysis of facies, well logs, and reservoir data within the framework of high-resolution sequence stratigraphy has resulted in a new model of St.more » Louis reservoir geometry. Development and exploration concentrates on recognizing and mapping the updip pinch outs of porous grainstone facies related to maximum landward extent of paleoshorelines caused by relatively major fluctuations in relative sea level. These shoal facies build-ups and pinch outs should form viable exploration targets as they cross structural elements formed or reactivated during the Pennsylvanian.« less