THE PERMIAN BASIN OF WEST TEXAS AND SOUTHEAST NEW MEXICO: A WORLD-CLASS PETROLEUM PROVINCE

The Permian Basin of west Texas and SE New Mexico is a prolific hydrocarbon producing province. More than 29 billion barrels of oil and 75 trillion cubic feet of natural gas have been produced from conventional Paleozoic-age reservoirs, making it the seventh largest oil and gas producing region in the world. Five individual conventional oil fields within the basin have each produced greater than one billion barrels, and an additional 51 fields qualify as “giants,” each having produced 100 million barrels or greater. Petroleum reservoirs and organic-rich hydrocarbon source rocks occur at numerous stratigraphic levels ranging from Lower Ordovician to Upper Permian, with Permian reservoirs hosting the majority of conventional reserves. Recent horizontal drilling within the region is proving the existence of vast recoverable unconventional reserves, primarily housed in Late Pennsylvanian to Middle Permian shales. The amount of oil and gas ultimately produced from these shales will likely eclipse conventional reserves.

The Permian Basin has a complex geologic history that includes an Early Paleozoic precursor basin (Tobosa Basin). Beginning in latest Mississippian and Early Pennsylvanian time, the Tobosa Basin was tectonically differentiated into a series of basement-involved uplifts and high-standing shelves separated by rapidly-subsiding depressions (Delaware, Val Verde, and Midland basins). Structural differentiation was driven by the assembly of Pangea and development of the Ancestral Rocky Mountain complex as the Permian Basin was located at the SW nexus of Gondwana – Laurentia collision (Marathon – Ouachita fold and thrust belt) and Pacific subduction along the western margin of Laurentia, which drove Ancestral Rocky deformation. Rapid subsidence of the Delaware and Midland basins occurred during the Early Permian as the evolving foredeep was loaded with 10 km or more of sediment. This period of subsidence set in motion the thermal maturation of many of the deeper source rock intervals beginning in Late Permian time. The basin was sealed by Late Permian evaporites and remained relatively stable throughout most of the Mesozoic. Varying amounts of uplift associated with Laramide and Basin and Range tectonism have differentially affected the Permian Basin petroleum systems, more adversely to the west.