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.

Four clastic depositional sequences compose the lower part of the Triassic Dockum Formation in the Palo Duro Basin. Each sequence consists of a basal interbedded mudstone and interbedded siltstone succession overlain by an upper succession of sandstone containing minor conglomerate, siltstone, and mudstone beds. Regional cross sections indicate that the lower parts of sequences typically thicken basinward, whereas the upper sandy partsnbecome more discontinuous basinward and upsection.

This study is a product of ongoing Bureau of Economic Geology investigations, by means of geologic and petrophysical modeling, into the nature of reservoir compartmentalization or heterogeneity. The model has been designed to provide a basis for subsequent infill drilling in the reservoirs in question along trends of greatest geologic potential, rather than according to geometrically defined well spacings.The Lower Ordovician Ellenburger Group was the site of the investigations from which more than 10,000 ft (3,050 m) of core from 63 wells was logged.

Organic petrological, organic geochemical, and chemical analyses of Tertiary (Paleocene to Eocene) coals (to a 2,000-ft [610-m] depth) from the Wilcox, Claiborne, and Jackson Groups of Texas reveal characteristic properties of these coals. Most of the Wilcox, Claiborne (one sample), and Jackson coals contain greater amounts of liptinite (especially fine-grained liptodetrinite) than do average humic coals. These liptinites can be identified only by blue-light excitation in reflected-light microscopy.

Reservoirs in the Permian Basin of Texas are estimated to have contained a total of 105.7 billion barrels (Bbbl) of oil at discovery. As of January 1985, these reservoirs had produced a cumulative volume of 25.3 Bbbl of oil, and proved reserves were calculated at 5.9 Bbbl. Thus, of original oil in place, and given a projected recovery efficiency of less than 30 percent at current development and technology, 74.5 Bbbl of oil will remain in Permian Basin reservoirs at depletion. Eighty-eight percent of this unrecovered oil lies at depths of less than 8,000 ft.