What is Oil Shale? 

Oil Shale is fine grained rock which contains significant amounts of Kerogen.  New drilling technology can extract liquid hydrocarbons. Oil shale requires more processing then crude oil, which is more expensive. Most exploitation of oil shale involves mining followed by shipping elsewhere, after which one can burn it directly to generate electricity, or undertake further processing. The most-often used methods of surface mining are open pit mining and strip mining. These procedures remove most of the overlying material to expose the oil shale deposits, and are practical when the deposits are close to the surface.  The world's largest Oil Shale reserve is located in Colorado, Wyoming, and Utah in the Green River Basin Oil Shale Formation.

Full Artice Here - http://en.wikipedia.org/wiki/Oil_shale