A crude oil that is obtained from oil shale by heating and distillation. Synthetic crude oil that is extracted from oil shale by pyrolysis, or destructive distillation. The oil obtained from oil shale cannot be refined by the methods that have been developed for crude oil, however, because shale oil is low in hydrogen and contains large amounts of nitrogen and sulfur compounds. To be made usable, shale oil must be hydrogenated and then chemically treated to remove the nitrogen and sulfur, a process too expensive to make shale oil commercially competitive with crude oil. See also kerogen, petroleum
Shale that is rich in hydrocarbon derivatives, In the United States, a significant oil shale is the Green River Formation, in the Rocky Mountain region
A black or dark brown shale containing hydrocarbons that yield petroleum by distillation. Any fine-grained sedimentary rock that contains solid organic matter (kerogen) and yields significant quantities of oil when heated. This shale oil is a potentially valuable fossil fuel, but the present methods of mining and refining it are expensive, damage the land, pollute the water, and produce carcinogenic wastes. Thus, oil shale will probably not be exploited on a wide scale until other petroleum resources have been nearly depleted. Estonia, China, and Brazil have facilities for producing relatively limited quantities, and the U.S. government operates an experimental plant in Colorado