The Permian Basin of west Texas and New Mexico is the largest petroleum-producing basin in the United States. In this area, multiple episodes of Paleozoic faulting, uplift, and erosion occurred, including those events related to the Marathon-Ouachita orogeny (Hercynian orogenic cycle ∼350–250 Ma). Within Paleozoic rocks in the Permian Basin, the Pennsylvanian succession is the second most oil-productive system, next to the Permian. This succession has been viewed historically as sedimentologically and stratigraphically complex because of the interplay of deposition, coinciding with icehouse climatic conditions during a second-order global transgression, and presumed active tectonism.
New paleodepositional systems maps for the Morrowan, Atokan, Desmoinesian, Missourian, and Virgilian stages of the greater Permian Basin are presented. This study integrates varied data, including outcrop, drill core, geophysical (seismic and gravity), wireline log, biostratigraphic, and reservoir quality. Systems maps depict the spatial and temporal distribution of sediment source areas, shallow-water to basinal carbonates, alluvial to open-marine siliciclastics, shales, and areas of uplift.
A Pennsylvanian reservoir architecture and facies evolution diagram combines data on key reservoir facies and targets, including their dimensions; the relative location of the facies tracts within each depositional system; the overall system architecture; and each stage's potential for diagenetic modification. A unified depositional system model provides continuity between the paleodepositional systems maps and summarizes the entire Pennsylvanian facies proportion evolution within eight provinces of the Permian Basin. The depositional systems information is referenced to second- to fourth-order eustasy curves and tectonic input. The reservoir evolution diagram and paleodepositional maps used in conjunction with the unified systems model provide the reader with the most current and extensive integration of data on the Pennsylvanian geologic history in the greater Permian Basin from a sedimentologic and petroleum reservoir systems perspective. Insights into facies distribution, the overall development of the basin and its subbasins, tectonic episodes, identification of potential new play types and exploration targets, and new depositional and sequence-stratigraphic architectural models are presented in this article.