Structure contour and overburden maps of the Niobrara interval of the Upper Cretaceous Cody Shale in the Bighorn Basin, Wyoming and Montana

The Bighorn Basin is a large intermontane sedimentary and structural basin that formed during the Laramide orogeny. The first commercial hydrocarbon production in the Bighorn Basin was established in 1906 from Cretaceous reservoirs at Garland field followed by the discovery of Greybull field in 1907.  Since then, many important conventional oil and gas resources have been discovered from reservoirs ranging in age from Cambrian to Tertiary.  In addition, a potential continuous (unconventional) basin-centered gas accumulation may be present in Cretaceous reservoirs in the deeper parts of the basin.  The maps presented in this report were constructed as part of a project carried out by the U.S. Geological Survey to better characterize the geologic framework of potential undiscovered continuous (unconventional) oil and gas resources of the Niobrara interval of the Upper Cretaceous Cody Shale in the Bighorn Basin in north-central Wyoming and south-central Montana.