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The Permian Basin is one of the most prolific, and currently one of the most active, oil and gas basins in the USA. The Lower Permian strata in the Permian Basin have produced more than 14 billion barrels of oil (BBO), making it the largest volume of hydrocarbon in the basin. Sedimentation in the Midland Basin during late Leonardian through early Guadalupian (ca. 272e269 Ma) resulted in progradation of shelf edge and ultimately closure of the basin by Middle Permian time. We analyzed a merged seismic survey covering parts of the Permian Basin (i.e., Central Basin Platform and Midland Basin) in Andrews, Ector, and Midland Counties, Texas. The seismic survey and well logs show the presence of gently dipping (ca. 1°) clinoforms in the Upper San Andres and Grayburg Formations on the eastern edge of the Central Basin Platform and western Midland Basin. The seismic attributes, curvature, and spectral decomposition identify low sinuosity slope channels oriented north-south, but such channels do not appear beyond the slope. The shelf edge shifts from north to south during deposition of the Upper San Andres and Grayburg Formations. We identify five basinward shifts noted by the migration of the shelf edge toward the basin center and the presence of channel features along the depositional slope. The petrophysical analysis indicates that channels cut into carbonate rocks and are filled by siliciclastic sediments; this interpretation is supported by the most negative curvature anomalies along the channel axes caused by the differential compaction between the carbonate and siliciclastic rocks. There are a few channels with a northwest-southeast strike, which matches the direction of the Concho Lineament observed by satellite data. Such observations are consistent with previous interpretations of the northern Midland Basin closure during Middle-Late Permian time. [ABSTRACT FROM AUTHOR]

The Pennsylvanian unconformity, which is a detrital surface, separates the beds of the Permian-aged strata from the Lower Paleozoic in the Central Basin Platform. Seismic data interpretation indicates that the unconformity is an angular unconformity, overlying multiple normal faults, and accompanied with a thrust fault which maximizes the region's structural complexity. Additionally, the Pennsylvanian angular unconformity creates pinch-outs between the beds above and below. We computed the spectral decomposition and reflector convergence attributes and analyzed them to characterize the angular unconformity and faults. The spectral decomposition attribute divides the broadband seismic data into different spectral bands to resolve thin beds and show thickness variations. In contrast, the reflector convergence attribute highlights the location and direction of the pinch-outs as they dip south at angles between 2° and 6°. After reviewing findings from RGB blending of the spectrally decomposed frequencies along the Pennsylvanian unconformity, we observed channel-like features and multiple linear bands in addition to the faults and pinch-outs. It can be inferred that the identified linear bands could be the result of different lithologies associated with the tilting of the beds, and the faults may possibly influence hydrocarbon migration or act as a flow barrier to entrap hydrocarbon accumulation. The identification of this angular unconformity and the associated features in the study area are vital for the following reasons: 1) the unconformity surface represents a natural stratigraphic boundary; 2) the stratigraphic pinch-outs act as fluid flow connectivity boundaries; 3) the areal extent of compartmentalized reservoirs' boundaries created by the angular unconformity are better defined; and 4) fault displacements are better understood when planning well locations as faults can be flow barriers, or permeability conduits, depending on facies heterogeneity and/or seal effectiveness of a fault, which can affect hydrocarbon production. The methodology utilized in this study is a further step in the characterization of reservoirs and can be used to expand our knowledge and obtain more information about the Goldsmith Field. [ABSTRACT FROM AUTHOR]