Abstract

Low-permeability (“tight”) reservoir sandstones of the Cleveland Formation produced more than 412 Bcf of natural gas through December 1989, mostly from Ochiltree and Lipscomb Counties in the northeastern Texas Panhandle. Although large-scale gas production started in 1956, the regional stratigraphic, depositional and structural (present and syndepositional) setting of the Cleveland are poorly known. This paper summarizes findings of a study conducted in a 5,100-mi², 7-county area in the western Anadarko Basin using log suites from more than 860 evenly spaced wells, 3 cores and numerous sample logs. The Cleveland Formation is well defined by regionally continuous, thin, radioactive, black shale marker beds that bound the unit.

Reservoir facies of the dominantly siliciclastic Cleveland Formation were in part deposited as a series of eastward-prograding, probably wave-dominated, deltas composed of (in ascending sequence) prodelta, distal delta-front and proximal delta-front deposits. An upward-fining fluvial sandstone occurs in one stratigraphic zone in the middle Cleveland throughout most of the study area and also composes reservoir rock. Regional cross sections and net-sandstone patterns indicate four dominant sandstone trends in the producing area: three north-south-oriented, arcuate thicks composed of stacked delta-front facies at stabilized paleoshoreline positions and one east-west trend representing superimposed fluvial-channel incision after a drop in regional base level.

Distinctive trends of thickness variation record elements of the paleophysiography of the Cleveland depositional area and evidence of syndepositional faulting, flexure and marked differential subsidence. The unit thickens eastward toward the deep Anadarko Basin and reaches a maximum thickness of about 590 ft in southwestern Hemphill County. Depositional patterns were controlled by (1) a paleohigh in the western part of the study area (eastern flank of Cimarron Arch) that separates siliciclastic facies from carbonate-dominated Cleveland of the Kansas Shelf, (2) subsidence of two subbasins within a northwest-trending half graben bounded a syndepositional fault on its southern edge and a monoclinal flexure to the north and (3) a two-tiered depositional shelf controlled by differential subsidence of an underlying Oswego Limestone buildup.