Abstract

Pennsylvanian-Permian Paleogeography of a southern portion of the Eastern Shelf, Tom Green, Irion, and Schleicher Counties

Jessica M. Bernal and Joseph I. Satterfield
Department of Physics and Geosciences, Angelo State University, San Angelo, TX

Pennsylvanian - Permian rocks of the Eastern Shelf in a study area within SW Tom Green County, SE Irion County and northern Schleicher County contain hydrocarbon reserves. Upper Pennsylvanian – mid Permian rocks of the Eastern Shelf consist of several clastic prisms bounded by transgressive carbonate rocks and black shale (Thoma, 1999). The Dove Creek South Field within the study area produces from the Canyon Group at depths of 6,450-6,500 feet and Strawn limestone at depths of 7,236-7,246 (Becker,1990). Traps are a northwest-southeast trending anticline and sandstone pinchouts onto the anticline (Becker, 1990). From 1965 to 1976 the field produced 361,847 BO from the Canyon “B” Sand and 763,611 BO from the Strawn Limestone (Becker, 1990). Thirty-four gamma ray and neutron density logs have been assembled from the study area. An E-W cross-section shows tops and thickness variations of the Wolfcamp Series, Cisco Group, and Canyon Group. Future work will include correlating transgressive limestones, constructing a grid of several cross-sections, and making isopach maps of clastic prisms. Isopach maps and log patterns will be used to interpret depositional environments. Thoma (1999) mapped slope, toe-of-slope, and basin floor environments to the north which may extend into this study area.

AAPG Search and Discovery Article #90164©2013 AAPG Southwest Section Meeting, Fredericksburg, Texas, April 6-10, 2013.