--> ABSTRACT: Estimates of Undiscovered Recoverable Oil and Gas Resources for Onshore and State Offshore Areas of United States, by R. F. Mast, G. L. Dolton, R. A. Crovelli, R. B. Powers, R. R. Charpentier, D. H. Root, and E. D. Attanasi; #91030 (2010)

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Estimates of Undiscovered Recoverable Oil and Gas Resources for Onshore and State Offshore Areas of United States

R. F. Mast, G. L. Dolton, R. A. Crovelli, R. B. Powers, R. R. Charpentier, D. H. Root, E. D. Attanasi

From 1859 when oil was first discovered at Titusville, Pennsylvania, through 1985, over 180 billion bbl of recoverable oil and natural gas liquids and 760 trillion ft3 of recoverable natural gas have been discovered onshore in the United States. How much remains to be discovered in the United States is an important question. This paper presents the details of a new assessment. Estimates of undiscovered recoverable conventional oil and gas resources were made for more than 240 geologically defined plays from 80 petroleum provinces and basins covering the onshore and the state offshore areas of the conterminous 48 states and Alaska.

Resource estimates for undiscovered accumulations with recoveries larger than 1 million bbl of oil or 6 billion ft3 of gas were made using a play analysis method requiring estimation of play and accumulation favorability or risk, the size distribution of undiscovered recoverable accumulations, and the distribution of the number of undiscovered accumulations. Undiscovered recoverable resources in fields smaller than the 1 million bbl and 6 billion ft3 minimum sizes were estimated for each province as a whole. Statistical extrapolations of the numbers of fields in field-size classes greater than the minimum size produced estimates of the ultimate numbers of fields in field size classes below the minimums. The number of small fields already discovered and the volume of oil and gas in these fields were also used to estimate the undiscovered resources in small fields.

The resources estimates are smaller than those published by the U.S. Geological Survey in 1981. However, the 1981 data were somewhat different because the method employed was different. Some of the resources classified as undiscovered in 1981 are now classified as identified, unconventional, or inferred resources, and the resources discovered from 1981 to 1986, especially in some onshore frontier areas, were disappointing in view of the very large exploration drilling effort.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.