Abstract

This paper is a case history of a thrust-belt prospect along the leading edge of the Crawford thrust sheet. The prospect originated from surface mapping in the southern part of the Crawford Mountains. Four-way closure at depth was confirmed by seismic data later shot over the prospect. In July, 1980, a test well was spudded in the Mississippian Brazer Dolomite and drilled into the steep east dip on the eastern flank of the fold. After the hole was deviated to the west a normal Paleozoic section was drilled to a final total depth of 3,269 feet in the Ordovician Bighorn Dolomite. The prospect was dependent on the Devonian Three Forks Shale providing an adequate seal for the underlying dolomites. Unfortunately, this was not the case. Some minor gas shows were encountered in the Jefferson Dolomite beneath the Three Forks, but drill-stem tests of the interval recovered no hydrocarbons. As a result the well was plugged and abandoned on October 23, 1980.