Red beds, evaporites, and carbonates of the upper Clear Fork and Glorieta Formations (Permian) of the Texas Panhandle form an association of facies deposited in nearshore and supratidal environments along an arid coastline.

San Andres oil constitutes more than 80 percent of the total production from the Northern Shelf of the Midland Basin, Texas.

The San Andres evaporitic sequence in the Palo Duro Basin comprises several thick carbonate units in its lower part and many thin units in its upperpart. To the south, across the Northern Shelf of the Midland Basin, evaporites pinch out and carbonates predominate.

The Palo Duro Basin seemingly has all the elements necessary for hydrocarbon generation and accumulation: reservoirs, traps, source rocks, and sufficient thermal maturity. Porous facies in pre-Pennsylvanian, Pennsylvanian, and Permian strata are potential hydrocarbon reservoirs.

The San Andres Formation on the Northern and Northwestern Shelves of the Midland Basin is a progradational stratigraphic unit consisting predominantly of carbonate facies. Lithofacies include dolomite, laminated anhydrite and dolomite, massive bedded anhydrite, limestone, salt, and red beds.

Regional cross sections of Middle and Upper Permian rocks in the Texas Panhandle illustrate the lithology, depositional systems, and structure of these salt-bearing strata.

The Salado-Tansill and Alibates Formations are the youngest evaporite and carbonate facies within a thick Permian sequence of evaporites, carbonates, and red beds in the Texas Panhandle.

A broad zone of salt dissolution that affects parts of the Permian Salado, Seven Rivers, San Andres, Glorieta, and upper Clear Fork Formations occurs beneath the Canadian River Valley from New Mexico eastward toward Amarillo, Texas, and southeastward parallel to the eastern Caprock Escarpment.

Pennsylvanian clastic and carbonate strata were deposited in a variety of environments within the Palo Duro Basin. Maximum accumulation (totaling 750 m or 2,400 ft) occurred along a northwest-southeast axis.

Samples collected from 20 geographically widespread wells in the sparsely drilled Palo Duro Basin were analyzed for total organic carbon content (TOC). Highest values of TOC, up to 6.9 percent, occur in Upper Permian San Andres dolomite in the southern part of the basin.