Reserves data were collected from each UKCS operator during February and March 2010. Oil reserves include both oil and the liquids obtained from gas fields. Oil reserves are summed in the Oil Table below at different probability levels to give a range of estimates from proven to the maximum level.
The oil reserves presented are in both sanctioned fields (i.e. fields in production or approved fields under development but not yet producing) and other significant discoveries not yet fully appraised. The latter comprise discoveries for which there is an intended field development and a provisional start date. Proven, probable and possible reserves for a large number of individual fields have simply been summed to give the totals shown. There is, thus, a much smaller likelihood that the true figure for total oil reserves is outside the range of estimates than when considering probabilities for an individual field.
Cumulative oil production to the end of 2009 has been added to (remaining) oil reserves to give the estimated ultimate recovery figures.
Reserves and Estimated Ultimate Recovery in the Oil Table below are presented in metric units (million tonnes) to facilitate comparison with other energy resources and the inclusion of natural gas liquids. The UK Oil Reserves figures are also available in "field units" in Appendix 1 where we have used the approximate conversion factor of 1 tonne of crude oil = 7.5 barrels.
Notes on Oil Table
- Includes onshore as well as offshore fields. All figures include condensate, gas liquids and liquefied products.
- All entries are rounded to the nearest one million tonnes.
- Maximum is the sum of proven, probable and possible reserves.
- The oil reserves include 2 (8) proven, 4 (8) probable and 2 (7) possible million tonnes in approved fields under development but not yet producing.
- Cumulative oil production includes 53 (53) million tonnes from decommissioned oil fields.
Note that there are also "Potential additional resources" (PARs) in fields and drilled prospects for which there are no current plans for development.
Stacked Graph To Show Change in Oil Reserves and Production from 1979 to 2009
The chart shows how cumulative production and estimated ultimate recovery of oil have both grown over time. Proven plus probable reserves have tended to decline since 1994.
Review of UK Oil Reserves
The change in UK oil reserves during 2009 arises from a combination of:
- production during the year;
- reserves additions from new field developments including those resulting from recent exploration success;
- reserves revisions in established fields.
Oil production was 68 million tonnes in 2009.
There was a net reallocation of 2 million tonnes from Potential Additional Resources (PARs) and exploration to probable reserves but a net reallocation of 13 million tonnes of possible reserves back to PARs.
From the Oil Table it can be seen that the central estimate of (remaining) oil reserves based on proven plus probable reserves now stands at 769 million tonnes which is a decrease of 1 million tonnes compared to last year. Taking annual oil production of 68 million tonnes into account this leaves a proven plus probable reserves replacement of 67 million tonnes.
Proven oil reserves at the end of 2009 stand at 378 million tonnes, which is 30 million tonnes less than at the end of 2008. After accounting for production, there has been a net transfer of 38 million tonnes from probable to proven oil reserves. The main contributing factor to this was the reallocation of probable reserves into the proven category in some producing fields, although development approval during 2009 of several new oil fields including Auk North, Bardolino and Burghley also contributed.
Probable oil reserves have increased from 361 to 390 million tonnes. The increase of 29 million tonnes in probable oil reserves reflects a large reallocation of possible reserves to probable reserves in the light of a number of successful appraisal wells during 2009.
Possible oil reserves have decreased by 17 million tonnes. The decrease in possible reserves reflects the reallocation of possible to probable reserves mentioned above, together with some downward revisions in possible reserves in existing fields and the reallocation of possible reserves back to PARs.
Maximum oil reserves (remaining), combining proven plus probable plus possible reserves figures, have decreased by 19 million tonnes to 1,111 million tonnes.
Review of UK Estimated Ultimate Recovery of Oil
(i.e. Oil Reserves plus Cumulative Production)
Estimated ultimate recovery of oil has increased at all three levels this year. At the proven plus probable level, the estimated ultimate recovery of oil has increased by 67 million tonnes and now stands at 4,152 million tonnes. At the proven level it has increased by 38 million tonnes to 3,761 million tonnes. Maximum estimated ultimate recovery of oil, combining proven plus probable plus possible reserves figures, has increased by 50 million tonnes to 4,494 million tonnes.
Cumulative oil production to the end of 2009 stood at 3,383 million tonnes.