| The Pennsylvanian Tonkawa Sandstone of the Douglas Group was examined in northwestern Roger Mills County and southwestern Ellis County, Oklahoma. This study incorporates core analysis, cross-sections and mapping, thin section analysis, and x-ray diffraction to investigate the Tonkawa Sandstone.;The Tonkawa Sandstone within the study area is part of a larger deltaic system on the northern flank of the Anadarko basin. The various depositional environments identified within the study include: distributary channel fill, distributary mouth bar, distal bar, prodelta, interdistributary bay, and crevasse splay deposits.;Sandstone bodies have been classified as micaceous very fine to fine grained sublitharenite. Sorting ranges from moderate to well-sorted, while grains appear subrounded to subangular. The dominant constituents include monocrystalline quartz, metamorphic and sedimentary rock fragments, and various feldspars. Burial and diagenesis of the Tonkawa Sandstone has led to the depletion of primary porosity by compaction, cementation, and precipitation of authigenic clays. The remaining porosity largely consists of secondary pores that contribute to oil and gas production of Tonkawa reservoirs.;The Tonkawa Sandstone was first targeted for production during the 1960's and 1970's. Recent developments in horizontal drilling and hydraulic stimulation have led to an explosion of interest in the previously overlooked Tonkawa Sandstone. This study explores the production opportunity and potential of various reservoirs observed in the study area. |
