Table 1. Distribution of U.S. Energy Supply, 1950-1990 

 (in Percent of BTU's). (Sources: 1950 Data, Reference 

 2; 1975-1990 Data, Reference 1) 



1.1.2 Status of U.S. Oil and Gas Resources 



Cumulative production of oil in the United States from 1849 through 

 1974 amounted to 106.1 billion barrels, according to the U.S. Geological 

 Survey [3]. The amount of oil remaining has been estimated by USGS, by 

 classifications shown in Figure 1. Identified reserves are estimated to 

 be 68 billion barrels (statistical mean of high and low estimates), or 

 63 percent of the total already produced. USGS has further estimated 

 "undiscovered recoverable resources," those economic resources not yet 

 discovered which are estimated to exist in favorable geological environ- 

 ments, to range between 50 and 127 billion barrels of oil. The statistical 

 mean of these estimates is 86 billion barrels. 



In comparison to the 481 trillion cubic feet of natural gas produced 

 through 1974, there are identified reserves of 439 trillion cubic feet 

 and undiscovered recoverable resources of 484 trillion cubic feet 

 (statistical means). The latter estimate has a range between 322 and 

 655 trillion cubic feet of natural gas [3]. 



While these estimates indicate a supply available for many years, 

 the level of proven reserves--which increased for many years with new 



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