The exploration program which resulted in the Bell Creek oil field was initiated by Sam Gary in 1961, with the discovery of the Jewel oil field in Crook County, Wyoming. Although southeast Montana apparently had a structural and stratigraphic history comparable with that of the producing area in Wyoming, early exploration efforts were unsuccessful. However, initial wells drilled on surface and seismic structures found highly porous and permeable sandstones within the Lower Cretaceous that yielded minor shows of oil and gas.

Industry efforts were hampered by lack of communication between district offices in Wyoming and Montana. Prior to the Bell Creek discovery, the Muddy Sandstone, an important producer in the Wyoming part of the Powder River basin, was not considered to have potential as a commercial oil formation in Montana. In order to predict the location of the Bell Creek field, it was essential to relate the surface and subsurface geology in Wyoming to the subsurface control available in Montana.

The Muddy reservoir of Bell Creek field is a group of coalescing barrier-bar sandstones on a homocline. The field has an ultimate recovery of more than 200 million bbl of oil and is an outstanding example of the potential for major production which exists in the Rocky Mountain area. Drilling is the most efficient and conclusive test of evolving economically oriented stratigraphic concepts.