Eni's estimated proved reserves were determined taking into account Eni's share of proved reserves of equity-accounted entities. The 2008 year end amounts comprised 30% of proved reserves of the three equity-accounted Russian companies purchased in 2007 as part of a bid procedure for assets of bankrupt Russian company Yukos and participated by Eni with a 60% interest, considering that Gazprom exercises a call option to acquire a 51% interest in these companies.Additions to proved reserves booked in 2008 were 856 million boe and derived from:

• revisions of previous estimates were 751 million boe, partly related to higher entitlements reported in certain PSAs (up 342 million boe) resulting from lower year end oil prices from a year ago (Brent price was $36.55 per barrel at December 31, 2008 compared to $96.02 per barrel at December 31, 2007), net of downward revisions associated with marginal productions in certain mature fields. These revisions were reported in Angola, Kazakhstan and Libya;
• extensions and discoveries were 71 million boe, with major increases booked in Angola, Egypt, Nigeria, Norway and United States;
• improved recovery were 34 million boe mainly reported in Algeria, Angola, Congo and Libya

Acquisitions amounted to 91 million boe reflecting the contribution of the acquired Burren assets in Congo, Turkmenistan and India. Sales of reserves in place (59 million boe) related to the divestment of a 1.71% stake in the Kashagan project following the finalization of the agreements implementing the new contractual and governance framework of the project effective January 1, 2008.

In 2008 Eni achieved an all sources reserve replacement ratio¹ of 135% (136% under SEC reporting standards, based on reserve additions from Eni's consolidated subsidiaries). The average reserve life index is 10 years (10 years at December 31, 2007). Excluding the price effect, the replacement ratio would be 83%.
Eni's estimated proved reserves would be 6,908 mmboe including the proved reserves of thee Russian gas companies on the basis of Eni's current interest 60%. The average reserve life index is 10.5 years.

(1) Ratio of changes in proved reserves for the year resulting from revisions of previously reported reserves, improved recovery, extensions, discoveries and sales or purchases of minerals in place, to production for the year. A ratio higher than 100% indicates that more proved reserves were added than produced in a year. The Reserve Replacement Ratio is a measure used by management to indicate the extent to which production is replaced by proved oil and gas reserves. The Reserve Replacement Ratio is not an indicator of future production because the ultimate development and production of reserves is subject to a number of risks and uncertainties. These include the risks associated with the successful completion of large-scale projects, including addressing ongoing regulatory issues and completion of infrastructure, as well as changes in oil and gas prices, political risks and geological and other environmental risks.