In-place pre-Pennsylvanian petroleum resources now known within the boundaries of the National Petroleum Council's Region 5 (North, Central, and West Texas and eastern New Mexico) total 15 billion bbl of crude oil. Projections suggest that 4.9 billion bbl remains to be found. This estimate indicates that for oil this region is about three fourths developed. The bulk of these resources is in two major zones--pre-Simpson and Silurian-Devonian. Total pre-Pennsylvanian rock volume is 68,500 cu mi (285,440 cu km). Average crude oil resources, therefore, are 290,000 bbl per cubic mile.

Known in-place nonassociated gas resources total 23.4 trillion cu ft, and an estimated 51.94 trillion remains to be found. Therefore, gas production is still in the early stages of development, about one third of the gas resources having been discovered. Discoveries of associated and dissolved gas total 9.57 trillion cu ft, and about 3.22 trillion cu ft remains to be found. This gas is closely associated with oil development and has a similar production history.

Potential calculations of petroleum hydrocarbons disseminated in nonreservoir rocks and of gas dissolved in subsurface waters have been made, although it is realized that they may never rate as reserves.