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 95-75-N
January 1998

CONCLUSIONS

At their mean values the technically recoverable undiscovered conventional oil and gas resources on Federal Lands amounted to about 7.5 BBO and 57.9 TCF. Technically recoverable gas in continuous-type (unconventional) accumulations amounted to about 127 TCF or more than twice the amount assessed in undiscovered conventional accumulations. Although the undiscovered conventional oil and gas on Federal Lands could not be characterized as the lowest cost resources assessed in the 1995 National Assessment, the quantities allocated to Federal Lands are significant. Some of the gas assessed in continuous-type accumulations on Federal Lands, particularly in the Uinta-Piceance and San Juan Basins were characterized by very low costs. Most of the 92 TCF assessed in continuous-type gas accumulations on Federal Lands in the Southwest Wyoming province (37) was characterized as having relatively high costs. However, this large gas resource provides an attractive incentive for development of cost reducing technologies to convert it to an economic resource.

The 1989 US Geological Survey’s national oil and gas assessment (Mast and others, 1989) evaluated only conventional resources. Furthermore, the economic analysis did not include finding costs. The 1995 assessment revised downward by more than 40 percent the assessed technically recoverable conventional oil in the Northern Alaska province. This revision resulted from new drilling information and an alternative interpretation of the thermal history of the province (Gautier and others, 1996) that reduced the perceived maximum depths where oil was thought to occur. For undiscovered conventional fields in the lower 48 States, the 1989 Assessment assigned 3.6 BBO oil and 26.9 TCF gas to onshore Federal Lands (Dolton and others, 1990) whereas the 1995 Assessment assigned 3.8 BBO crude oil and 24.0 TCF gas to onshore Federal Lands. Where comparable, the assessment valuations are quite similar.

The inferred reserves component of the 1995 Assessment is not included in this assessment of Federal Lands. The 1995 National Assessment projected during the next 80 years that 60 BBO of oil and 322 TCF of gas could be added to reserves in conventional oil and gas fields discovered before 1992. This is significantly greater than the approximately 30 BBO of oil and 259 TCF gas assessed for undiscovered conventional resources in all onshore and State offshore areas in the 1995 National Assessment. In 1995, oil production of onshore Federal Lands represented 6.6 percent of total US onshore oil production and gas production from Federal Lands was 12.3 percent of total US onshore gas production. More detailed information about production units on Federal Lands, that is, conventional versus unconventional continuous-type accumulations, and discovery dates of fields, are needed to allocate the 1995 National Assessment inferred reserve estimates to onshore Federal Lands.

The economic analysis could also have been prepared using distributions associated with the 5th and 95th fractiles of the assessment rather than the mean values reported in the geologic assessment. It is appropriate to use this point estimate in the computations and for ease of communicating results; however, such a point estimate may convey a misguided sense of precision in the results. Indeed, uncertainty exists in the costs and technical relationships used in the economic analysis as well.

For a National perspective, the resources estimated by the Minerals Management Service (1996) in undiscovered conventional oil and gas for the Federal Outer Continental Shelf (OCS) should be added to the estimates presented here. At $18 per barrel ($2 per mcf dry gas) the Minerals Management Service assessed a total of 14.4 BBO and 72.5 TCFG for the total US OCS. At $30 per barrel ($3.34 per mcf dry gas), economic resources were estimated at about 21 BBO and 100 TCFG. For the lower 48 OCS alone, at $18 per barrel economic undiscovered conventional oil was estimated to be 10.6 BBO and at $30 per barrel economic undiscovered conventional oil was estimated to be 11.4 BBO (MMS, 1996). Amounts of economic gas assigned to Alaska were very small.

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