One nonconventional target for increased oil recovery in Texas is oil that remains in abandoned reservoirs, defined as reservoirs that produced no oil or gas in 1977 and 1982.

Statistical analysis of chemical data on Texas Eocene coals revealed startigraphic and geographic trends in lignite quality. Chemical data on near-surface coals wre obtained from various private and public sources. Seams from deep-basin coals were compared.

Oil and gas production in Texas peaked in 1972, but the state still contributed 28 percent of oil production and 33 percent of gas production in the United States in 1984.

Fractures and veins in strata of the Palo Duro Basin area, Texas Panhandle and eastern New Mexico, are characterized using data from outcrop and core studies and from fracture identification log analysis.

Subsidence at salt domes results from man-induced and natural removal of salt, cap rock, minerals within the cap rock, and supradomal fluids. In the Houston diaper province, Frasch sulfur mining as caused subsidence bowls and collapse sinkholes at 12 of the 14 sulfur productive domes.

Cretaceous rocks in the Southern High Plains, traditionally considered to be part of the High Plains aquifer and recharged by the overlying Ogallala aquifer, actually contain three aquifers with different recharge sources.

A comprehensive review of Texas earthquakes from 1847 to 1986 has revealed 106 earthquakes of magnitude 3 or greater; of these, 24 are earthquakes for which reports of damage are available, and 1 was responsible for a human fatality.

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.

Horizontal drilling in a mature hydrocarbon province such as Texas can increase recovery from reservoirs in which a significant proportion of oil or gas in place remains unrecovered by conventional means.