The Aylesworth oil field in eastern Marshall County and western Bryan County, Oklahoma, is located south of the Arbuckle Mountains, approximately 30 miles east of Ardmore. The structure is a northwest-southeast trending, normally faulted anticline about 10 miles long and as much as ¾ mile wide, with about 1,600 feet of closure proven by drilling. It is of late Pennsylvanian, probably Virgilian age.
Cretaceous rocks of the Comanchean series, found at the surface and to a depth of approximately 650 feet, rest unconformably on Pennsylvanian rocks of the Springeran Series and do not accurately reflect the deeper structure. Pre-Pennsylvanian beds are essentially parallel and, except where missing because of faulting, are present over the entire structure.
Production is almost entirely from the 2d and 3d Bromide sands of the Simpson group of Ordovician age. The oil trap is structural rather than stratigraphic, although stratigraphic variations in thickness, and variations in the degree of cementation of the producing sands may determine the size of individual wells. The reservoir has a solution-gas/gas-expansion drive. There is no effective water drive. Cumulative oil production as of October 1, 1953, was 4,636,833 barrels.