Shale is a fine-grained detrital sedimentary rock, formed by the compaction of clay, silt, or mud. The organic matter, often called kerogen, is largely insoluble in petroleum solvents, but decomposes to yield oil when heated. Shale Energy can be found all over the world, including large deposits located within the United States. There are an estimated 2.9 to 3.3 trillion barrels worth of recoverable oil according to estimated global deposits of Oil Shale Energy.
Oil Shale Energy resources can be found in many different countries, but only approximately thirty-three different countries possess shale energy deposits with any real economic value. The United States is actually accountable for around sixty percent of the world's resources for oil shale energy, and together with Russia and Brazil, more than eighty-six percent of shale oil content is accounted for. There are several oil shale energy deposits that have not yet been explored, however, so these figures are simply estimations at the current time.