Eni’s estimated proved reserves were determined taking into account Eni’s share of proved reserves of equity-accounted entities ⁶
Additions to proved reserves booked in 2009 were 592 mmboe 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

The largest additions were related to following fields/projects: Goliat in Norway, Belayim in Egypt, M’Boundi in Congo, Bahr Essalam in Libya, CAFC and MLE in Algeria and Zubair in Iraq.

(6) Includes a 29.4% stake of the reserves of the three equity-accounted Russian companies participated by the joint-venture OOO SeverEnergia, owned by  Eni (60%) and its Italian partner Enel (40%) which on September 23, 2009 completed the divestment of the 51% stake in the venture to Gazprom in line with the call option arrangement.

Acquisitions related mainly to a 27.5% stake purchased from Quicksilver Resources Inc in the Alliance area, in Texas.
In 2009 Eni achieved an all sources reserve replacement ratio ⁷ of 96% with a reserve life index of 10.2 years (10 years at December 31, 2008). Excluding the price effect, the replacement ratio would be 109%.

(7) As of December 31, 2009 and 2008 Eni’s proved reserves of the Kashagan field were determined based on Eni working interest of 16.81% and 18.52% as of December 31, 2007.