The State-owned submerged lands of Texas encompass almost 6,000 mi2 (15,540 km2). They lie below waters of the bay-estuary-lagoon system and the Gulf of Mexico and extend 10.3 mi (16.6 km) seaward from the Gulf shoreline (fig. 1). The importance of these lands and their resources to resident flora and fauna as well as to people is well known and documented; more than one-third of the state's population is concentrated within an area of the Coastal Zone that is only about one-sixteenth of the state's land area.

Pervasively dolomitized, anhydritic carbonates of the upper San Andres Formation in the Emma field of West Texas constitute an upward-shallowing sequence of lithofacies representing four major depositional environments. Open Platform fusulinid packstone/wackestone and burrowed wackestone form the base of the sequence. These deposits, which accumulated in a shallow-water, normal marine setting, contain moldic and intercrystalline porosity and constitute the lower of two major porosity intervals in the reservoir section.

Approximately 2,200 ft (670 m) of principally continental and paralic rocks of late Virgilian, Wolfcampian, and early Leonardian age (late Pennsylvanian and early Permian) are exposed in an area of about 4,950 mi2 (12,800 km2) between the Brazos and Red Rivers in North-Central Texas. The stratigraphic complexity of these strata has impeded internal correlation and mapping ever since the rocks were first described by W. F. Cummins in the late 19th century.

In the Palo Duro Basin, the Wolfcampian Series (lower Permian) overlies Pennsylvanian (primarily Virgilian) strata and underlies the Wichita Group (Leonardian). Tectonic activity from late Pennsylvanian through early Wolfcampian deposition included basement subsidence that resulted in localized basin development.