A computer-balanced regional cross section allows several new interpretations for the structural development of Wilburton gas field. The gas-productive deep Arbuckle structure is interpreted to be in the hanging wall of a high-angle, south-dipping reverse fault. This fault may be a reactivated normal fault based on Pennsylvanian lower Atokan thickness changes and by analogy to comparable extensional faults to the north. Overlying the Arbuckle fault block is an imbricated thrust sheet containing Pennsylvanian Spiro and Cromwell sandstone reservoirs where gas production has been established from both the hanging wall and footwall fault blocks. The main thrust originates from a detachment zone within Mississippian shales to the south and ramps over the deeper Arbuckle fault block along the southern margin of the field. Minimum horizontal displacement of the hanging wall Spiro cutoff is 3.5 miles (5.6 km). This estimate is significantly smaller than that shown by previously published sections through the area, yet is still too large to be adequately accommodated by blind thrusting north of Wilburton field. Well and surface data indicate that much of the displacement instead may have been accommodated by north-dipping backthrusts. Although poorly constrained, at least some fault movement on the Arbuckle reverse fault appears to postdate the overlying thrust-faulted structures.

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