The Happy Springs, Crooks Gap, Kirk, and Sheep Creek oil fields are situated along the Green Mountain-Crooks Mountain trend in southeastern Fremont County, Wyoming.
Structurally, the fields lie within the southwestern part of the Wind River basin, near the western end of the so-called “Sweetwater arch.”
The main structural features of the area were formed by Laramide compressive forces and consist of (1) several easterly trending shear zones, and (2) a series of northwest-trending folds and associated thrust faults. The folds and shear faults formed concomitantly in response to Laramide compressive forces. The shear faults divide the area into several elongate blocks and developed to accommodate different deformational patterns within the blocks.
The Happy Springs and adjacent fields consist of tightly folded, thrust-faulted, northwest-trending anticlines formed en échelon on the south side of an easterly trending shear zone. These folds represent crustal shortening in the block lying south of the shear zone. The features in which crustal shortening is manifested in the block north of the shear zone are located about 10 miles west of the Happy Springs area in the large Mormon Trail anticline and thrust fault. The shear zone is a line of release that developed between the two blocks when they responded differentially to compressive forces.
The main accumulation of oil in the Happy Springs and Kirk fields is in the deformed strata along the foot-wall of the shear zone.