Oil and gas resources on University Lands, 2.1 million acres in 19 West Texas counties, constitute a major asset of the University of Texas System. The original oil in place (OOIP) of the 102 major University Lands oil reservoirs is calculated to be 7,520 MMbbl. Components of the calculated OOIP include residual oil (3,761 MMbbl, 49 percent), cumulative production (1,702 MMbbl through 1999, 23 percent), remaining reserves (125 MMbbl, 2 percent), and unrecovered mobile oil (1,932 MMbbl, 26 percent). Ultimate recovery from the 49 major University Lands gas reservoirs is calculated at 2.4 Tcf through 1999. The gas resource base has been divided into cumulative production since 1987 (1.5 Tcf, 62 percent) and remaining reserves (0.9 Tcf, 38 percent).
The major oil and gas reservoirs on University Lands have been delineated into 22 plays. Historically plays of the Silurian-Devonian and San Andres-Grayburg reservoirs have been the major oil plays on University Lands. However, future potential in terms of unrecovered mobile oil is greatest in the Leonardian Restricted Platform Carbonate andSpraberry/Dean Submarine Fan Sandstone plays. Historical gas production and remaining reserves by plays are dominated by the Devonian Thirtyone Deep-Water Chert play. This play has dwarfed all other gas plays on University Lands.
Although most of the major oil and gas reservoirs on University Lands are mature, significant opportunities for incremental recovery exist in terms of unrecovered mobile oil, the volume that is the future target of reserve-growth opportunities. Advanced reservoir characterization and recovery studies conducted by the Bureau of Economic Geology on 16 University Lands oil fields have played a pivotal role in providing a better understanding of production mechanisms and geology, as well as enabling incremental production. The current play analysis of oil and gas resources provides an assessment tool for targeting major fields that have similar opportunities for incremental production. The play-analysis method for assessing University Lands oil and gas resources can be applied more broadly to other areas of the Permian Basin.