Overview

Oil shale is an inorganic, nonporous sedimentary marlstone rock containing various amounts of solid organic material (known as kerogen) that yields hydrocarbons, along with non-hydrocarbons, and a variety of solid products, when subjected to pyrolysis (a treatment that consists of heating the rock at high temperature).

Thus, by definition, kerogen is naturally occurring insoluble organic matter found in shale deposits. However, shale oil is the synthetic fuel produced by the thermal decomposition of kerogen at high temperature [>500 C (>932 F)]. Shale oil is referred to as synthetic crude oil after hydrotreating.

The oil shale deposits in the western United States contain approximately 15 percent organic material by weight. By heating oil shale to high temperatures, kerogen can be released and converted to a liquid that, once upgraded, can be refined into a variety of liquid fuels, gases, and high-value chemical and mineral by-products. The United States has vast known oil shale resources that could translate into as much as 2.2 trillion barrels of known kerogen oil-in-place. Oil shale deposits concentrated in the Green River Formation in the states of Colorado, Wyoming, and Utah account for nearly three-quarters of this potential.

Because of the abundance and geographic concentration of the known resource, oil shale has been recognized as a potentially valuable U.S. energy resource since as early as 1859, the same year Colonel Drake completed his first oil well in Titusville, Pennsylvania (Chap. 1). Early products derived from shale oil included kerosene and lamp oil,...