500 



UNITED STATES MINERAL RESOURCES 



less than 10 gallons of oil per ton. The richest beds 

 — the cannel shales — are thin and of small extent. In 

 the Interior coaJ province, the Pennsylvanian rocks 

 contain numerous marine shales, persistent across 

 thousands of square miles, Swanson (1960, p. 16) 

 reported that about 40 distinct shale units occur in 

 eastern Kansas and northeastern Oklahoma, but 

 most of them are thin and yield 5-10 gallons of oil 

 per ton. In Illinois, the oil yield of 114 samples from 

 30 marine shales ranged from to 40 gallons of oil 

 per ton, but 88 percent yielded less than 15 gallons 

 of oil per ton. 



RESOURCES 



IDENTIFIED AND HYPOTHETICAL RESOURCES 

 OF SHALE OIL 



Identified shale-oil resources are those deposits for 

 which sufficient data are available to establish the 

 magnitude and oil yield vi^ithin reasonable limits. 

 Hypothetical resources are resources in possible ex- 

 tensions of identified deposits or in nearby deposits, 

 in which the approximate magnitude of the oil-shale 

 deposit is known, but whose oil yield is inferred from 

 scant evidence. 



GREEN RIVER FORMATION 



The minimum thickness and grade of oil shale used 

 by the U.S. Geological Survey in classifying public 

 lands as valuable for oil shale of the Green River 

 Formation is about equal to a sequence 15 feet thick, 

 yielding an average of 15 gallons of oil per ton, but 

 sequences yielding as little as 10 gallons per ton are 

 included when computing the average yield of a thick 

 sequence of oil shale. On this basis, the identified 

 resources of the Green River Formation in Colorado, 

 Utah, and Wyoming are estimated to total 1.8 tril- 

 lion barrels of oil (table 95) . Most of these identified 

 resources (1.2 trillion barrels) are contained in the 

 Piceance Creek basin of Colorado (Donnell, 1964; 

 Donnell and Blair, 1970) . The Uinta Basin of Utah 

 is estimated to contain about 0.32 trillion barrels of 

 oil (Cashion, 1964), and recent core data indicate 

 that the Green River and Washakie basins of Wy- 

 oming together contain a similar amount. 



Apparently none of these resources can be con- 

 sidered as economically recoverable now. However, 

 a modest increase in the price of oil may make oil 

 shale yielding an average of 30 or more gallons of oil 

 per ton competitive with crude oil, so resources of 

 this grade were calculated. Resources in high-grade 

 shale, in zones more than 100 feet thick, total 418 

 billion barrels of oil (table 95) , or nearly one-quarter 

 of the identified resources of 1.8 trillion barrels. The 

 major part of these high-grade resources (355 bil- 



Table 95. — Shale-oil resources of the United States, in bil- 

 lioiis of barrels, by grade (oil yield) of oil shale 



[All resource figures except those for the Green River Formation are 

 adapted from Duncan and Swanson, 1965, table 2: Ne, not estimated] 



Identified^ Hypothetical ^ Speculative ^ 



Deposit 25-100 10-25 26-100 10-26 26-100 10-26 



gal/ pal/ gal/ gal/ gal' gral/ 

 ton ton ton ton ton ton 



Green River Formation, 



Colorado, Utah, 



and Wyoming « 418 1,400 60 600 



Chattanooga Shale and 



equivalent formations. 



Central and Eastern 



United States 200 800 



Marine shale, Alaska Small Small 250 200 



Other shale deposits Small Ne Ne 600 23,000 



Total < 418 1,600 300 1,600 600 23,000 



^ Identified resources : Specific, identified mineral deposits that may or 

 may not be evaluated as to extent and grade, and whose contained 

 minerals may or may not be profitably recoverable with existing tech- 

 nology and economic conditions. 



-Hypothetical resources: Undiscovered mineral deposits, whether of 

 recoverable or subeconomic grade, that are geologically predictable as 

 existing in known districts. 



^Speculative resources: Undiscovered mineral deposits, whether of 

 recoverable or subeconomic grade, that may exist in unknown districts 

 or in unrecognized or unconventional form. 



* The 25—100 gal/ton category is considered virtually equivalent to the 

 category "average of 30 or more gallons per ton '* 



lion bbl) is in the Piceance Creek basin of Colorado; 

 the remainder is in the eastern part of the Uinta 

 Basin of Utah (50 billion) and in the southeastern 

 part of the Green River Basin of Wyoming (13 bil- 

 lion). About 80 percent of these resources (325 bil- 

 lion) has been well evaluated by core drilling; the 

 remainder is based on data which are sparse, or less 

 reliable. Because conservative estimates of thickness 

 and grade were used in areas where data were 

 sparse, it is possible that the drilling of more core 

 holes will require an upward revision of these re- 

 source figures. 



The hypothetical resources of the Green River 

 Formation are estimated to total about 650 billion 

 barrels of oil, of which perhaps 50 billion barrels are 

 in oil shales yielding 25-100 gallons of oil per ton. 



The synthetic-gas potential of oil shales of the 

 Green River Formation has been investigated by the 

 Institute of Gas Technology. Their data indicate that 

 by using different processing methods, high-quality 

 synthetic gas could be produced at the rate of 100 

 cubic feet of gas for each gallon of shale oil that 

 could be produced by a conventional retort, or 4,200 

 cubic feet for each barrel of shale oil. Thus, the 

 Green River Formation could be the source of an 

 enormous amount of gas, instead of oil, if so desired. 



CHATTANOOGA SHALE AND EQUIVALENT FORMATIONS 



Most of the marine black shales in the United 

 States yield so little oil by conventional retorting 

 (1-15 gallons of oil per ton) that it is difficult to 

 consider them an economical resource of oil even for 

 the distant future on this basis alone. However, many 

 of the marine black shales have a high organic con- 



