Sequence stratigraphic framework and reservoir quality of the Red Fork Sandstone, Clinton-Weatherford channel, Anadarko Basin, Oklahoma: Evaluating horizontal exploration potential in former conventional plays

Abstract

The Pennsylvanian Red Fork Sandstone has a long history of conventional oil and gas production in western Oklahoma, particularly in an elongate trend called the Clinton-Weatherford channel. This study focuses on this trend in four counties, Blaine, Caddo, Custer, and Washita to establish a depositional framework based on a sequence stratigraphic interpretation of the Red Fork Sandstone interval. The Red Fork Sandstone is becoming a target for horizontal completion in the western Anadarko basin and understanding the Red Fork Sandstone and determining its position in the sediment dispersal system within a sequence stratigraphic framework is essential to locating reservoirs suitable for horizontal development. In this study area, the Red Fork Sandstone is subdivided into upper and lower subunits, which are separated by a shale marker bed that is recognized with consistence on wireline logs. Within the study area, the Red Fork Sandstone interval thickens from the northeast to southwest. The east-west trending Clinton-Weatherford channel has been interpreted as a shelf fluvial channel and submarine slope channel that supplied sediment to basin floor fans to the west. By reinterpreting and examining the key stratigraphic surfaces in core and core calibrated wireline logs, depositional sequences were established that allow delineation of thickness trends and facies distribution patterns, facilitating an overall interpretation of the sediment fill within this channel and the surrounding areas. This improves our ability to predict bypassed reservoir distribution within and outside channel-fills and as a result, contribute to exploration success. The results of this study could impact interpretation of other Pennsylvanian sandstone reservoirs in the western Anadarko basin including the Upper Skinner Sandstone, which displays a similar east-west trending elongate channel morphology.