From Wikipedia, the free encyclopedia.
Crude oil is a limited resource. It is estimated that there is a total of 2,390 billion barels (380 km³) of crude oil on Earth. Estimates of undiscovered reserves range from 275 to 1,469 billion barrels (44 to 234 km³).
About 77% of crude oil has already been discovered, and 30% of it has been used so far. Between 1859 and 1968, 200 billion barrels (31 km³) of oil were used, and since then oil production has stabilized to 22 billion barrels (3.5 km³) per year. It is estimated that oil reserves will become scarce by 2050s.
Most of oil is concentrated in the Near East — around 41%. North America, Russia, and Antarctica are also rich in crude oil.
See also: List of oil fields, Petroleum
