Barrel (unit) continued to use the same size barrels. In the worldwide oil industry, an oil barrel is defined as 42 US gallons, which is about litres or 35 imperial gallons. Oil companies that are listed on American stock exchanges typically report their production in terms of volume and use the units of bbl, Mbbl (one thousand barrels), or MMbbl (one million barrels) and occasionally for widest comprehensive statistics the Gbbl (or sometimes Gbl) denoting a billion. There is a conflict concerning the units for oil barrels (see ). For all other physical quantities, according to the International System of Units, the
History of the oil shale industry in the United States of oil per short ton of shale. Estimated in-place resources are capable of generating 4.2 trillion barrels of oil. Although the Piceance basin of western Colorado has the smallest lateral extent of Green River shale, it contains the greatest amount of high-grade shale. Using a cut-off of 25 gallons per ton, the Piceance has about 352 billion barrels of in-place resource. The Elko Formation of northeastern Nevada is an oil shale, late Eocene to early Oligocene in age. Like the Green River Formation, it contains beds deposited in a lake. Faulting and subsequent erosion have removed most of the original