Crude oil means 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.
- Small amounts of hydrocarbons that exist in gaseous phase in natural underground reservoirs but are liquid at atmospheric conditions (temperature and pressure) after being recovered from oil well (casing-head) 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, such as sulfur and various metals.
- Drip gases, and liquid hydrocarbons produced from tar sands, oil sands, gilsonite, and oil shale.
- Petroleum products that are received or produced at a refinery and subsequently injected into a crude supply or reservoir by the same refinery owner or operator.
Petroleum refineries convert crude oil and other liquids into many petroleum products that people use every day. Most refineries focus on producing transportation fuels.
About 100 countries produce crude oil. However, in 2021, five countries accounted for about 51% of the world’s total crude oil production.