Located in east-central Campbell County on the eastern flank of the Powder River basin, Wyoming, the Dillinger Ranch field produces oil from the "B" Sand section of the Permian part of the Minnelusa Formation. The field is defined by 17 wells and 5 dry holes. Total field reserves are estimated to be 5-10 million barrels of oil. The trap is formed by the intersection of a structural nose with an updip truncation of reservoir sandstone in a shale-filled channel.

Post-Minnelusa streams cut deeply into the formation and removed substantial portions of the alternating sandstone, carbonate, and anhydrite sequence. The Opeche Shale was then deposited over the entire basin flank, filling in the drainage valleys. Much later, the Laramide orogeny tilted the eastern flank of the basin toward the southwest. Migrating hydrocarbons were unable to move updip at those places where the reservoir sandstones encountered the impermeable shale seal in the channels. It is anticipated that many more fields will be discovered in the Minnelusa in similar stratigraphic traps along the eastern flank of the Powder River basin.

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