Oil Shale and Shale Oil Analysis

Abstract An oil shale can be defined as a compact rock of sedimentary origin with an ash content of more than 33% and containing organic matter that yields oil when destructively distilled, but not appreciably when extracted with ordinary solvents. This is an operational definition. There is no geological or chemical definition of an oil shale. The term is used mostly in an economic sense so that any shallow rock that yields a commercial amount of oil upon pyrolysis may be considered an oil shale. Oil shale deposits occur in at least 50 countries and the estimated potential world supply of oil from shale is 5 × 1012barrels. The organic matter in an oil shale is mostly in the form of kerogen, which is defined as that fraction of the organic matter in a sedimentary rock that is insoluble in common petroleum solvents. The insolubility of kerogen is the main reason why an oil shale must be heated to produce liquid products. The amount of shale oil that can be produced by heating an oil shale is normally obtained from a Fischer assay. However, the Fischer assay is somewhat time‐consuming and does not provide information about what chemical properties of oil shales are important for producing liquids. Consequently, a number of alternative procedures have been developed to analyze oil shales. These procedures, along with methods of analyzing shale oils, are described in the following sections.