Geology of Eola Area, Garvin County, Oklahoma

Abstract

The Eola field is in T. 1 N., R. 2 W., southern Garvin County, Oklahoma, just north of the exposed Arbuckle Mountains. It is on the subsurface extension of these mountains and is remarkable in the structural complexities revealed by the drill. Ten wells have been drilled, of which seven have been producers. These tests indicate the major structural feature of the area to be a west-northwest striking fault, with the magnitude of the stratigraphic displacement measurable in miles. Highly folded and faulted pre-Deese strata north of the fault form an overturned syncline whose axial plane dips southward. Oil and gas accumulation is controlled by local closure along secondary faults on the north and normal flank of the syncline. The attitude of identifiable formations and sequence geometry as observed in the bore-holes show that the major faulting be interpreted as thrusting. Thus, for the first time it is demonstrable from subsurface data that Dott's premise of major thrusting in the Arbuckle Mountains is tenable. In interpreting the data the writers use minor thrust and reverse faults to account for stratigraphic discontinuities in the bore-hole in an attempt to explain the structure as homogenous in fault type, thus avoiding the indiscriminate use of mixed fault types. In an area so complex it is understood that there is no unique solution; however, the interpretation presented is logical and in no instance are the data violated. The interpretation of these data indicates two major periods of diastrophism: post-Springer--pre-Deese and post-Hoxbar--pre-Pontotoc. Evidence concerning the relative importance and intensities of these orogenies is discussed. Cross sections are presented as an aid to deciphering the geological structure and history. Oil is produced from the basal Bromide sand of Ordovician age at depths 10,000-11,000 feet. The accumulative pipe-line runs from January, 1947, through April, 1950, total 941,609 barrels, the discovery well contributing 424,402 barrels of this amount.