Colorado has substantial conventional fossil fuel resources in the Sand Walsh, Piceance, Paradox, and San Juan basins in the west, and the Denver and Raton basins in the east. It ranks seventh among the states in total energy production, ninth in oil production, fifth in natural gas production, and eleventh in coal production. Colorado has enormous potential oil production through its deposits of oil shale rock, which can be processed and converted into refined petroleum products. The Green River Formation, a group of basins in Colorado, Wyoming, and Utah, holds the largest known oil shale deposits in the world, holding about 1 trillion barrels of oil shale.
