Crude Oil Reserves

The amount of technically and economically recoverable crude oil is known as crude oil reserves. This may be reserve for an oil well, an oil reservoir, an oil field, a nation or for the world. Hence we refer to a particular oil well reserve, a field’s crude oil reserve, a country’s crude oil reserve and world crude oil reserve. The actual recoverable oil from crude oil reserves are more or less related to their degree of certainty. I mean… considering limitations in extraction techniques, only a fraction of crude oil reserves can be brought to surface.

Now, let’s look at different terms associated with crude oil reserves:

Crude oil proven reserve

Proven crude oil reserves are those crude reserves with reasonable certainty… at least 90% confidence of being recoverable under available economical, political and existing technological conditions. Proven reserves can further be classified as proven developed and proven undeveloped reserves. Proven developed reserves… as the name suggest are reserves that can be produced with existing wells and perforations, or from additional reservoirs where minimal operating expense is required while proven undeveloped reserves require additional capital investment to bring the oil to the surface.

Crude oil unproven reserves

Crude oil unproven reserves are those crude reserves with technical, contractual or regulatory uncertainties. Usually, unproven reserves are used internally by oil companies and government agencies for future planning purposes but are not routinely complied. Like proven reserves, unproven reserves also can be classified as probable and possible. Probable reserves are attributed to known accumulations and claim a 50% confidence level of recovery while possible reserves are attributed to known accumulations that have a less likely chance of being recovered than probable reserves. This term is often used for reserves which are claimed to have at least a 10% certainty of being produced.

Strategic Crude Oil Reserve

Strategic crude oil reserves are generally not counted when computing a nation’s crude oil reserve. It refers to government-controlled crude oil reserves for both economic and national security reasons. For example, United States Energy Information Administration states that approximately 4.1 billion barrels (650,000,000 m³) of oil are held in strategic reserves, of which 1.4 billion is government-controlled (m³=cubic meters).

Crude Oil Reserve Recovery Factor

Crude oil reserve recovery factor is the ratio of producible oil reserves to total oil in place for a given field. It varies greatly among oil fields and the recovery factor of any particular field may change over time based on operating history and in response to changes in technology and economics. The recovery factor may also rise over time if additional investment is made in enhanced oil recovery techniques such as gas injection, surfactants injection, water-flooding, or microbial enhanced oil recovery.

Crude Oil Reserve Growth

Crude oil reserve growth is a situation where most early estimates of the reserves of an oil field are conservative and tend to grow with time. This is because the geology of the subsurface cannot be examined directly and as such indirect techniques must be used to estimate the size and recoverability of the resource and while new technologies have increased the accuracy of these techniques, significant uncertainties still remain.

Estimated world crude oil reserves

Summary of Top 17 Proven World Crude Oil Reserve Data 2012

Country	Reserves 109 bbl
Venezuela	296.5
Saudi Arabia	265.4
Canada	175
Iran	151.2
Iraq	143.1
Kuwait	101.5
United Arab Emirates	136.7
Russia	74.2
Kazakhstan	49
Libya	47
Nigeria	37
Qatar	25.41
China	20.35
United States	20.35
Angola	13.5
Algeria	13.42
Brazil	13.2