"Refining of the so-called black oils produced in Wyoming and other Rocky Mountain States always has been a troublesome problem, both technically and economically. These low-gravity crudes have high sulphur content, a low gasoline yield, and high asphalt content. The present estimated potential production of black oils in Wyoming is between 36,000 and 46,000 barrels per day for wells already drilled. The actual black-oil production in 1930 was approximately 6,000 barrels a day. This small production is due to the limited market for black oils, which, in turn, is due largely to the almost prohibitive cost of refining these crudes into marketable products by present methods. These conditions indicate the need for further chemical and refining research on black oils to develop more adequate and economical methods of removing their objectionable constituents so that the market for these oils may be increased. Another factor which indicates the need for refining the black oils profitably is the decreasing production of low-sulphur light gravity crude oils in Wyoming. Since 1923 the production of light crudes has been decreasing, until in 1930 it was about equal to the potential production of black oil, and unless new light-oil fields are discovered more and more black oil must be refined to supply the regional demand for petroleum products. This preliminary survey gives brief history of black-oil fields in Wyoming, together with the potential and actual production of each field a Bureau of Mines Hempel analysis of each crude; and a discussion of the different products that may be obtained from these crudes, as indicate by the analyses."