Global total proved oil reserves in 2015 fell by 2.4 billion barrels (-0.1%) to 1697.6 billion barrels, just the second annual decline in our data set (along with 1998)
Reserves have nonetheless increased by 24%, or 320 billion barrels, over the past decade; and are sufficient to meet 50.7 years of global production. Brazil recorded the largest decline, with proved reserves falling by 3.2 billion barrels, while Norwegian proved reserves grew by 1.5 billion barrels. OPEC countries continue to hold the largest share (71.4%) of global proved reserves. On a regional basis, South & Central American reserves have the highest R/P ratio, 117 years. Lags in reporting official data mean that 2015 figures for many countries are not yet available.
Reserves to production (R/P) ratios 2015 by region (years)
Reserves to production (R/P) ratios history (years)
Total proved reserves of oil are generally taken to be those quantities that geological and engineering information indicates with reasonable certainty can be recovered in the future from known reservoirs under existing economic and geological conditions.
The data series for proved oil reserves in this year’s Review does not necessarily meet the definitions, guidelines and practices used for determining proved reserves at company level, for instance as published by the US Securities and Exchange Commission nor does it necessarily represent BP's view of proved reserves by country. Rather the data series has been compiled using a combination of primary official sources and third-party data.
Oil reserves include field condensate and natural gas liquids as well as crude oil. This inclusive approach helps to develop consistency with the oil production numbers published in the Review, which also include these categories of oil.
Liquid hydrocarbon fuels from non-hydrocarbon sources, such as ethanol from corn or sugar or synthetic oil derived from natural gas (so-called GTL or gas-to-liquids), are not included in either the reserves or production series.
Although every effort is made to come up with a consistent series for reserves based on a common definition, in reality different countries use different methodologies and the data have varying levels of reliability. Caution therefore needs to be exercised in attempting precise comparisons between nations or analyses of time series.
We have provided a detailed explanatory note on reserves clarifying current definitions and terminology.
R/P ratios represent the length of time that those remaining reserves would last if production were to continue at the previous year's rate. They are calculated by dividing remaining reserves at the end of the year by the production in that year.
Reserves-to-production (R/P) ratios are available by country and feature in the table of oil reserves. R/P ratios for the region and the world are depicted in the chart above and the Energy charting tool and World Energy app.
In the absence of replenishment by successful exploration or reserves growth, so-called 'reserves replacement', proved reserves would tend to decline over time as production depleted the existing reserve base. However, the tendency has been for proved reserves at the aggregate level to increase over time as reported discoveries, extensions and improved recovery have exceeded production.
Global oil reserves declined by 2.4 billion barrels in 2015 to 1,697.6 billion barrels. Globally, that represents an increase of 24% over the 2005 figure, despite cumulative production of 340 billion barrels during the past ten years. Global reserves are about 323 billion barrels higher than a decade ago. Lags in reporting official data mean that 2015 figures for many countries are not yet available.
There is a time series of crude oil reserves, which can be found in the Excel workbook. Data are measured in thousand million barrels.
The estimates have been compiled using a combination of primary official sources, third-party data from the OPEC Secretariat, World Oil, Oil & Gas Journal and independent estimates of Russian reserves based on official data and Chinese reserves based on information in the public domain. Canadian oil sands 'under active development' are an official estimate. Venezuelan Orinoco Belt reserves are based on the OPEC Secretariat and government announcements.