The Laramie-Hanna-Shirley basins are three contiguous intermontane basins between the Laramie (Front Range) Mountains and the Sierra Madre and Rawlins uplifts. All of the current major production was discovered prior to 1960. In the last 4 years only 20 wildcats have been drilled in the area, which includes approximately 5,000 sq mi (13,000 sq km).

Hydrocarbon production in these basins is primarily from the Muddy, Cloverly, Sundance, and Tensleep. Lesser amounts of production have been indicated from the Lewis, Mesa Verde, Steele, and Frontier. All of the production in the area, with the exception of one field, is associated with surface and subsurface anomalies. In areas where the Cretaceous and Jurassic are productive, stratigraphic traps are usually associated with these anomalies.

Subsurface and outcrop data indicate that the Laramie-Hanna-Shirley basins have potential for purely stratigraphic entrapment in Cretaceous and Jurassic units. Delineation of facies for these units has indicated areas of best potential for stratigraphic entrapment. In addition, potential exists in the Laramie-Hanna-Shirley basins for entrapment on structural anomalies which have not been tested to deeper objectives.

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