Geology of Puryear Member of Upper Morrow Formation at Cheyenne Field, Roger Mills County, Oklahoma: ABSTRACT

Abstract

The Puryear member of the Pennsylvanian upper Morrow formation is the most prolific gas-producing unit in the deep Anadarko basin. The Puryear sandstone, a quartz sandstone and chert conglomerate, is the major depositional cycle in an overall regressive upper Morrow sandstone-shale sequence. At Cheyenne field, the Puryear trends northwest-southeast, subparallel to the Amarillo-Wichita uplift, which is about 25 mi to the southwest. The unit pinches out to the north and northeast and is water-bearing to the south and southwest in the local area. Productive sandstone thickness ranges from 10 to 45 ft, with porosities of 14 to 18% and permeabilities averaging 0.5 to 1.5 md at drilling depths of 14,800 to 16,000 ft. Textural interpretations of the cored Puryear sandstone at El Paso's 1-6 Berry (Sec. 6, T13N, R24W) show a coarsening-upward, poorly sorted, matrix-supported conglomerate consisting of fine to coarse-grained quartz sandstone with pebble to cobble-sized, angular and subrounded chert clasts. The Puryear member at Cheyenne field is interpreted as a delta-front deposit associated with a fan-delta system sourced from the Amarillo-Wichita uplift. End_of_Article - Last_Page 1320------------