Water produced from oil, gas, and geothermal reservoirs contains natural radioactivity that ranges from background levels to levels found in uranium mill tailings.

Texas has large resources of oil and natural gas that remain unrecovered.

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.

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.

Characterization of 500 of the largest Texas oil reservoirs permits grouping into plays of similar geology and common engineering and production attributes.

Characterization of 500 of the largest Texas oil reservoirs permits grouping into plays of similar geology and common engineering and production attributes.

The search for oil, its development, production, and marketing have, for the better part of a century, been a fundamental part of the Texas economy. The history of Texas oil finders, from the self-educated wildcatter to the highly trained explorationist, is a part of Texas lore.

Texas has long been a major oil province, accounting for nearly 40 percent of the historic production of crude oil in the United States. Texas now holds less than 30 percent of the Nation's proven reserves and less than 15 percent of its estimated as-yet-undiscovered oil.