Upper Cretaceous strata in the Powder River Basin—Formation tops database, structure and thickness contour maps, and associated well data

Upper Cretaceous strata in the Powder River Basin of northeastern Wyoming and southeastern Montana contain some of Wyoming’s most prolific oil and gas reservoirs as well as significant petroleum-generating source rocks. Using geophysical well logs from more than 2,200 oil and gas wells, key horizons within the Upper Cretaceous strata were identified throughout the basin, with the primary goal of a publicly available dataset containing depth-to-formation and assorted well data, including location, depth, datum, well type, and well class, for the Lower Cretaceous Muddy Sandstone through the Upper Cretaceous Fox Hills Sandstone. Compiled data were inspected for accuracy by comparison with primary documents. Contour maps derived from the formation depths illustrate basin-wide trends in formation depth and thickness. Subsurface interpretations and spatial contour data are available on the Wyoming State Geological Survey publications webpage and Interactive Oil and Gas Map of Wyoming.