Hydrocarbon production from the Casper Formation in the Laramie and Shirley basins of southeastern Wyoming is exclusively from sandstones on closed Laramie structures. Total recoverable reserves are approximately 8 million bbl, half of which is found in the Quealy Dome structure of the southern Laramie basin. The presence of closed structures which are barren of Casper oil suggests that factors other than the present structural configuration are important in controlling the oil distribution in the Casper Formation.

Subsurface data from 137 wells indicate that the present distribution of Casper oil and oil shows is a complex function involving pre-Laramide structural growth, the configuration of the post-Casper unconformity, sandstone porosity (and permeability) patterns in the upper part of the Casper Formation, and the development of Laramide structure. The relative paucity of Casper oil may be related to an extreme distance of migration from the source rock and the presence of major permeability barriers in the upper Casper Formation along the paths of early migration.

Prospects for major accumulations of Casper oil do not appear to be good although stratigraphic traps similar to those found in the eastern Powder River basin are possible.

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