Shale oil is used for fuel and as an alternative for conventional oil. It has been used this way in small amounts for a long time. Only a few countries produce shale oil on a commercial level.
The term shale oil denotes any oil that contains any bituminous materials (also referred to as kerogen). These materials are released when the rock is heated during pyrolisis, which releases the petroleum-like liquids from the solid rock. Shale oil formed millions of years ago when silt was deposited at the bottom of different bodies of water. These materials then transformed into shale oil under intense heat and pressure applied over long periods of time.
Mining shale oil is much more expensive and complex than mining conventional oil because the oil substances in shale oil are solids, so they are unable to be extracted directly from the earth. Shale oil must first be mined and heated to a high temperature, and then the oil must be separated from the mixture. Shale oil is found worldwide, although the largest amounts of shale oil are found in the United States in the Green River Formation, which covers parts of Colorado, Utah and Wyoming. The majority of shale oil is contained under lands owned and operated by the federal government.