UNITED STATES MINERAL RESOURCES 



BITUMEN-BEARING ROCKS 



By W. B. Cashion 



CONTENTS 



Abstract of conclusions 99 



Introduction 99 



Exploitation 100 



Geologic environment 100 



Resources 100 



Prospecting techniques 102 



Problems for research 102 



Selected references 103 



TABLE 



19. Deposits of bitumen-bearing rocks in the United 

 States with resources of at least 1 million 

 barrels 



101 



ABSTRACT OF CONCLUSIONS 



Bitumen-bearing rocks occur in many areas in the United 

 States, but few deposits have been exploited or evaluated for 

 their total energy potential. The evaluated deposits are a 

 relatively small part of North American resources of bitu- 

 men-bearing rocks and probably will not contribute to U.S. 

 energy needs before 1985. Studies of known but unap- 

 praised deposits, especially extensive subsurface tar sands, 

 will greatly increase total resource estimates. Technological 

 advancements are needed in tar-sand processing, especially 

 for in situ recovery methods. 



INTRODUCTION 



Nonfluid petroleum occurs as interstitial deposits 

 in numerous types of rock. These rocks and their 

 associated hydrocarbons are commonly treated as 

 one group, regardless of rock type, and have been 

 referred to as tar sands, oil-impregnated rocks, 

 asphalt-bearing rocks, oil sands, bitumen-bearing 

 rocks, and petroleum-impregnated rocks. As used 

 in this report, the term "bitumen-bearing rocks" 

 is all-inclusive and, on the basis of information 

 drawn from several reports, is defined as follows: 



Consolidated or unconsolidated rocks whose inter- 

 stices contain viscous to semisolid to solid petroleum 

 which in its natural state cannot be recovered by pri- 

 mary petroleum-recovery methods. This definition in- 

 cludes vein, dike, and asphalt-lake deposits as well 

 as disseminated deposits, but it excludes pyrobitu- 

 mens (such as coal and oil shale) and fluid bitumens. 



Nonfluid bitumen occurs principally as dissemi- 

 nated deposits in small pore spaces spread through- 

 out rock material. Bitumen content may be as much 

 as 20-25 percent by weight but is normally much 

 less. Bodies of homogeneous semisolid to solid 

 hydrocarbon, containing very little rock material, 

 occur in vein, pod, and lake deposits. These occur- 

 rences make up a small part of the total resource. 

 Relatively small deposits can be developed, how- 

 ever, because of the purity of the ore. 



Utilization of bitumen-bearing rocks in the 

 United States has been chiefly in road building. Be- 

 cause of competition from refinery asphalt, the de- 

 mand for native asphalt, supplied by bituminous 

 sandstone and bituminous limestone, has not kept 

 pace with the 20th-century surge in road construc- 

 tion. (See section "Exploitation.") Gilsonite is the 

 only solid hydrocarbon produced in appreciable 

 amounts. It is used in ink, paint, battery boxes, and 

 numerous other manufactured items and is refined 

 to produce high-quality coke and gasoline. 



The Athabaska tar sands in Canada are being 

 mined and processed by GCOS (Great Canadian 

 Oil Sands, Ltd.) to produce crude oil. GCOS is pro- 

 ducing about 45,000 barrels of oil per day, and 

 they plan to increase production. Other companies 

 also plan to add new installations. 



In 1967, tar-sand deposits in Albania, Rumania, 

 and Russia and an asphalt-lake deposit on the island 

 of Trinidad were being exploited; in 1964 the La 

 Brea, Trinidad, operation produced 189,246 tons of 

 material (Phizackerley and Scott, 1967, p. 571). 



The United States possesses a rather small part 



U.S. GEOL. SURVEY PROF. PAPER 820 



