The area whose subsurface geology and oil and gas resources are described in this report lies along the southern border of Osage County, Okla., and includes parts of T. 20 N., Rs. 9 and 10 E., and of T. 21 N., Rs. 8 and 9 E., and all of T. 21 N., R. 10 E. The towns of Osage and Prue are within the area; Cleveland, which is a mile south of the Arkansas River, is not far beyond its southwestern limit; and Tulsa is 10 miles east of its southeast corner. The production of oil and gas from the many fields in the five townships began as early as 1905, and drilling has continued up to the present. Oil or gas is produced from 13 zones at depths ranging from 250 to 2,600 feet. Of these zones, one is in the Ordovician system, one is at the contact of the Mississippian and the Pennsylvanian series, and all others are in the Pennsylvanian series. The five townships lie within a region that contains many oil and gas fields in the Bartlesville sand; the Red Fork sand is oil-bearing in a narrow belt in T. 21 N., R. 8 E.; and oil and gas are produced in small areas from the Taneha, Skinner, Squirrel, Cleveland, Jones, and Layton sands, the Mussehem and Peoples sand zone, the Okesa, Torpedo, and Clem Creek sand zone, and the Big lime and Peru sand zone.

The rocks dip westward across the five townships at an average rate of about 38 feet to the mile as measured on the top of the Oswego lime. This regional dip is interrupted, however, by many anticlines, domes, synclines, and structural basins. The subsurface crests of most of the domes and anticlines are not directly under the crests as determined on the exposed rocks, and the dips of the deeper rocks are steeper and the structural closures greater in the buried rocks than in the exposed rocks. The exposed rocks are cut by several faults that trend northwest, but the data are insufficient to determine whether the deeply buried rocks, also, are displaced along the faults.

This investigation has shown that there are a few localities not yet completely tested in this part of Osage County that may produce oil and gas and that a few producing oil fields have areas within or adjacent to them that have not been thoroughly prospected. It is pointed out that yields of oil and gas from limy reservoir rocks may be increased by acid treatment and that additional oil may be produced from some of the reservoir sands by repressuring them with gas or flooding them with water.