Definition of 'Oil Reserves'
An estimate of the amount of crude oil located in a particular economic region. Oil reserves must have the potential of being extracted under current technological constraints. For example, if oil pools are located at unattainable depths, they would not be considered part of the nation's reserves.
Reserves are calculated based on a proven/probably basis.
Investopedia explains 'Oil Reserves'
Saudi Arabia, Kuwait, Iran, Iraq, Venezuela, Russia, Mexico and Canada are some of the world leaders in oil reserves. Canada has over 150 billion barrels of oil reserves, a large portion of which is concentrated in the Alberta oil sands. If the rate of technological improvement exceeds the rate of extraction, national oil reserves will increase.