This excerpt taken from the PBR 6-K filed Jan 16, 2009.
According to the SPE criteria:
On December 31st, 2008 Proved Reserves of oil, condensate and natural gas, abroad were 0.992 billion boe, representing a decrease of 9.0% in relation to 2007.
During 2008, the increase of proved reserves can be attributed to improving recovery factors in Argentina and Peru oil fields and the addition of Cascade field reserves in the United States. However this increase was offset by production activity, a decrease of assets in Ecuador and the revaluation of Nigeria reserves, resulting in a 98 million boe reduction of 2008 proven reserves, as shown below:
According to SPE criteria, international Reserve/Production (R/P) ratio was 12.1 years.