Electrical images in boreholes are becoming increasingly important in interpreting the rock record.

The Leonardian Spraberry Formation is a major oil-producing formation of the Permian Basin, accounting for more than 700 million barrels of oil produced from heterogeneous submarine-fan reservoirs.

Chert reservoirs of the Lower Devonian Thirtyone Formation represent a substantial part of the hydrocarbon resource in the Permian Basin. More than 700 million barrels of oil has been produced from these rocks, and an equivalent amount of mobile oil remains.

Silurian and Devonian carbonate and chert rocks in the Permian Basin constitute a prolific hydrocarbon-bearing succession in West Texas and New Mexico.

The Upper Devonian Woodford Formation is an organic-rich petroleum source rock that extends throughout West Texas and southeastern New Mexico and currently is generating oil or gas in the subsurface.

Unrecovered mobile oil is oil that is movable at reservoir conditions but is prevented from migrating to existing we1 l bores because of geologic complexities or heterogeneities.

The Ogallala aquifer, which underlies the Southern High Plains, consists of the saturated sediments of the Neogene Ogallala Formation. The aquifer is the main source of water for the High Plains of Texas and New Mexico and is being severely depleted by extensive pumpage for irrigation.

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.

This folded transparent map is at the same scale as its corresponding Geologic Atlas of Texas (GAT) sheet and can be superimposed on it to compare gravity information with surface geology.