Survey of Energy Resources Interim Update 2009
Crude Oil and Natural Gas Liquids update
Compared with coal, oil (and gas) reserves tend to be more subject to change from year to year, but fundamental restatements are fairly infrequent, as the principal sedimentary basins have been identified and, in most cases, explored, at least to some extent.
Figure 2 shows that the end-2007 proved recoverable reserves of crude oil and NGLs compiled for the present review are 31.9 billion barrels (just over 4 billion tonnes) higher than the end-2005 total quoted in the 2007 SER. Thirteen countries account for the bulk of the 2.6% global increase. The chief quantitative increases in reserves are seen in Venezuela, the Russian Federation and Canada, while proved reserves in Mexico, Norway and Iran have each decreased by between 1.3 and 1.5 billion barrels. After allowing for the 13 countries specified in Fig. 2, the remainder of the 98 countries listed as possessing proved oil reserves in Table 2.1 effectively balance each other off.
Proved recoverable reserves of crude oil and NGLs are listed in Table 2.1, with the 2007 level of oil production shown in Table 2.2 . The levels of NGL production are often at least partially estimated.