ABSTRACT

The Skinner sandstones, Desmoinesian, are included in the prolific Cherokee Group reservoir sandstones of the Northeast Oklahoma Platform. This study examines the geologic setting and emphasizes depositional environments, petrology, and diagenetic features of Skinner sandstones.

Depositional environments were interpreted from cores and outcrops, supplemented by stratigraphic cross-sections and spontaneous-potential curve patterns. Petrologic and diagenetic features of the Skinner sandstones were evaluated by means of routine thin-section examination, clay extraction and x-ray diffraction procedures, and SEM/EDXA methods.

The Skinner sandstones represent deposition during regressive phases of the overall transgression of the Cherokee Sea during Desmoinesian time. They were deposited from a major drainage system with a predominantly northern sediment source and were represented by four major sedimentary environments: upper deltaic plain; lower deltaic plain; marginal marine terrain; and prodeltaic terrain. Important Skinner sandstone reservoir facies include: point-bar deposits; distributary channel-fill; channel-mouth-bars; and delta-fringe sands.

Skinner sandstones are classified as sublitharenite, due to the relative abundance of rock fragments and lack of feldspar. Grain size varies from silt to very-coarse grained sand, but the sand predominantly is very-fine to fine-grained.

Four types of diagenetic features were documented in Skinner sandstones: dissolution features, precipitates, alteration products, and replacement features. Authigenic constituents include authigenic cements such as syntaxial quartz overgrowths, dolomite, calcite, siderite, hematite, and limonite; authigenic clays include kaolinite, illite, and chlorite.

Primary intergranular porosity plays a minor role in the Skinner sandstones. Secondary porosity is predominant; it averages six percent and ranges from a trace amount to 14 percent, as measured in thin sections. The largest porosity is in coarse-grained sands with small amounts of matrix, feldspar and cement. Dissolution porosity accounts for the majority of secondary porosity; it resulted from removal of detrital grains, detrital matrix, and to a minor extent, authigenic cement.