1995 National Oil and Gas
Assessment and Onshore Federal Lands
Donald L. Gautier, Gordon L. Dolton and Emil D. Attanasi
U. S. Geological Survey Open-File Report
This report summarizes estimated volumes of oil and gas in undiscovered conventional and continuous-type accumulations that occur on onshore Federal Lands. The basis of these estimates is the U.S. Geological Surveys 1995 National Assessment of oil and gas resources (Gautier and others, 1996). Onshore Federal Lands account for about 29 percent of US land area but only 5.1 percent of 1995 US oil production and 8.8 percent of 1995 US gas production. Estimates are as of January 1994. The Minerals Management Service has released a parallel study for Federal offshore areas (1996).
Quantities of technically recoverable oil and gas in conventional undiscovered oil and gas fields; in continuous-type oil and gas accumulations in sandstones, chalks, and shales, and in continuous-type accumulations of coalbed gas that occur on onshore Federal Lands were assessed (Table 1). Estimates of oil in undiscovered conventional fields range from 4.4 to 12.8 billion barrels (BBO) with a mean value of 7.5 BBO. Similarly, estimates of technically recoverable gas in undiscovered conventional fields range from 34.0 to 96.8 trillion cubic feet (TCF), with a mean value of 57.9 TCF. Almost 85 percent of the assessed gas in undiscovered conventional accumulations was non-associated gas, that is, gas in gas fields rather than gas in oil fields. Estimates of technically recoverable resources in continuous-type accumulations for oil are from 0.2 to 0.6 BBO, with a mean value of 0.3 BBO, and for gas, from 72.4 to 202.4 TCF with a mean value of 127.1 TCF. Estimates of technically recoverable coalbed gas range from 13.0 TCF to 19.6 TCF with a mean value of 16.1 TCF. The range of estimates correspond to the 95 percent probability (19 in 20 chance) and 5 percent probability (1 in 20 chance), respectively, of at least those amounts occurring.
The economic evaluation used the mean values of the technically recoverable resources assessed by the geologists. Figures 1A and 1B summarize the aggregate incremental costs of finding, developing, and producing oil and gas from undiscovered conventional fields and from continuous-type and coalbed gas accumulations located in onshore Federal Lands. In the figures, the economic resources in continuous-type accumulations and coalbed gas are depicted as the difference between the undiscovered conventional curve and the curve designated as total. At $30 per barrel or $3.34 per thousand cubic feet (mcf), 3.3 BBO oil and 13.6 TCF gas in undiscovered conventional fields can be found, developed, and produced. In addition, at that cost level, 0.2 BBO oil and 11.4 TCF gas in continuous-type accumulations and 11. 8 TCF of coalbed gas can be developed. For economic oil, Alaska and the Rocky Mountains and Northern Great Plains regions are dominant and for economic gas, the Colorado Plateau and Basin and Range and the Rocky Mountains and Northern Great Plains regions dominate.
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