Seismic Expression and Sedimentologic Characteristics of a Permian (Wolfcampian) Carbonate Submarine Fan, Midland Basin, West Texas

Seismically mounded and channeled allochthonous carbonates of Late Wolfcamp age form small stratigraphic traps in the eastern Midland Basin, Texas. These reservoirs occur in three areally restricted seismic-facies packages confined to the lower slope and basin and were deposited during a lowstand in relative sea level. The producing reservoir is interpreted to be a carbonate lowstand submarine fan, based on external and internal mounded seismic signature, channeled seismic character, scoured lower boundary, allochthonous carbonate conglomerates, breccias and grainstones derived from the shelf edge, and deposition on a regional (extrabasinal) sequence boundary with well-documented subaerial exposure. The well-log response in the fan interval shows the unit to be thickly bedded, with a sharp base and low API gamma signature. Petroleum production comes mainly from primary and solution-enhanced primary porosity in carbonate grain-rich matrix and clasts.