Sedimentation of Some Springer Sandstone (Mississippian-Pennsylvanian) Reservoirs, Southern Oklahoma

Abstract

The major oil reserves found in Springer sandstones have been found in the giant Velma and Sholom Alechem fields and in the adjacent smaller fields of Carter and Stephen counties, Oklahoma. These oil fields occur on prominent high-relief closed structural features, but a considerable part of the control on the oil accumulation is depositional. Thick and prolific reservoir sandstones occur at structurally high positions on these uplifts, but characteristically these sandstones become thin-bedded and shaly downdip. Deposition of the reservoir sandstones in an environment of high energy and normal open marine oxidation and pH level is indicated by good sorting, massive bedding, and the presence of glauconite and a benthonic fauna. In contrast, the adjacent non-reservoir Springer sediments seem to have been deposited in a somewhat stagnant environment. This is indicated by the unwinnowed sands, abundant siderite, absence of a benthonic fauna, and the bituminous shales. Evidence is presented that the structural elements were being developed during sedimentation, and that they had appreciable topographic relief. On the topographic highs an environment was favorable to the deposition of excellent oil reservoirs, and in the lower protected areas the environment resulted in the deposition of a favorable source facies. The conclusion is reached that the chief importance of structure in controlling the oil accumulations is indirect--that is, in the influence of the developing structure on sedimentation. The local sedimentational pattern is considered to be the critical factor in the development of the oil fields.