Definitions, Sources and Explanatory Notes

 Category:   Crude Reserves & Production
 Topic:   Crude Oil Production


Key Terms Definition
Barrel A unit of volume equal to 42 U.S. gallons.
Crude Oil A mixture of hydrocarbons that exists in liquid phase in natural underground reservoirs and remains liquid at atmospheric pressure after passing through surface separating facilities. Depending upon the characteristics of the crude stream, it may also include:
  • Small amounts of hydrocarbons that exist in gaseous phase in natural underground reservoirs but are liquid at atmospheric pressure after being recovered from oil well (casinghead) gas in lease separators and are subsequently commingled with the crude stream without being separately measured. Lease condensate recovered as a liquid from natural gas wells in lease or field separation facilities and later mixed into the crude stream is also included;
  • Small amounts of nonhydrocarbons produced with the oil, such as sulfur and various metals;
  • Drip gases, and liquid hydrocarbons produced from tar sands, oil sands, gilsonite, and oil shale.

  • Liquids produced at natural gas processing plants are excluded. Crude oil is refined to produce a wide array of petroleum products, including heating oils; gasoline, diesel and jet fuels; lubricants; asphalt; ethane, propane, and butane; and many other products used for their energy or chemical content.
    Crude Production The volume of crude oil produced from oil reservoirs during given periods of time. The amount of such production for a given period is measured as volumes delivered from lease storage tanks (i.e., the point of custody transfer) to pipelines, trucks, or other media for transport to refineries or terminals with adjustments for (1) net differences between opening and closing lease inventories, and (2) basic sediment and water (BS&W).
    Petroleum Administration for Defense (PAD) Districts Geographic aggregations of the 50 States and the District of Columbia into five districts by the Petroleum Administration for Defense in 1950. These districts were originally defined during World War II for purposes of administering oil allocation. Description and maps of PAD Districts and Refining Districts.

    For definitions of related energy terms, refer to the EIA Energy Glossary.


  • 1859-1919 (annual only): U.S. Dept. of Commerce, Bureau of the Census, Historical Statistics of the United States, Colonial Times to 1970, Part 1, Series M 138-142.

  • 1920-1975: Bureau of Mines, Mineral Industry Surveys.

  • 1976-1980: Energy Information Administration, Energy Data Reports.

  • 1981-Current: Energy Information Administration estimates published in the Petroleum Supply Annual and Petroleum Supply Monthly reports, based on crude oil production data from State Government agencies and the Department of the Interior, Bureau of Safety and Environmental Enforcement (and predecessor agencies), and first purchase data reported on Form EIA-182,"Domestic Crude Oil First Purchase Report", and Form EIA-914, "Monthly Crude Oil, Lease Condensate, and Natural Gas Production Report".

  •   Explanatory Notes

  • Totals may not equal sum of components due to independent rounding.
  • All PAD District totals and the U.S. total are estimates. In addition, reported production of most States are estimates.
  • Description and maps of PAD Districts and Refining Districts from the Petroleum Supply Monthly.