Accommodation Space and Distribution of Gas-Bearing Sandstones in the Upper and Lower Skinner Intervals, Anadarko Basin, Oklahoma

Kurtis Boucher. School of Geology, Oklahoma State University, 105 NRC, Stillwater, OK 74078, phone: (405) 744-6358, fax: (405) 744-7841 [email protected]

Sandstones in the Lower and Upper Skinner intervals produce large volumes of natural gas in the western Anadarko basin, Oklahoma. Regional mapping of the Pennsylvanian (Desmoinesian) in western Oklahoma reveals thickness trends that indicate 1) gradual basinward thickening of the interval and a shelf depositional setting for Skinner sandstones, and 2) sediment deposition that was affected by localized depocenters within the larger Anadarko depositional basin. Accumulation of sand and mud in these depocenters affected the distribution of sand bodies in the same and subsequent intervals. The accumulation of sand-rich sediments during Lower Skinner time was focused in an eastern depocenter. This area of accommodation prevented sand transport and the deposition of Lower Skinner sand bodies to the west. The filling of this Lower Skinner depocenter influenced sediment distribution in the superjacent Upper Skinner interval. Lack of accommodation space forced the Upper Skinner sediment dispersal system to the west where Upper Skinner sandstone bodies are abundant. Core-correlated, wireline electrofacies were used to establish depositional patterns for the Skinner sandstones. Incised valley fill, distributary channel, delta front, marginal marine, and prodelta environments were recognized. Hot shales and coals were used to construct the chronostratigraphic framework because they persisted in areas where carbonate markers were undetectable. This framework was used to clarify stratigraphy, interpret depositional settings, and assess the impact of subsidence rates on sediment dispersal. Higher-volume gas wells are completed in valley fill and distributary channel sandstones, whose locations can be predicted once the influence of accommodation space on sand distribution is understood.