Estimates of Nexen's proved and probable reserves contained in this news release have been prepared in accordance with SEC rules. For reserves estimates calculated in accordance with Canadian National Instrument 51-101, readers are referred to Nexen's Annual Information Form for the year ended December 31, 2011, which has been filed under Nexen's SEDAR profile at www.sedar.com and on Form 40-F filed with the SEC.This news release also contains references to "boe" (barrels of oil equivalent). Boes may be misleading, particularly if used in isolation. Nexen and CNOOC Limited have adopted the standard of six thousand cubic feet of gas to one barrel of oil (6 Mcf: 1 bbl) when converting natural gas to boes. Boes may be misleading, particularly if used in isolation. A boe conversion ratio of 6 Mcf: 1 bbl is based on an energy equivalency conversion method primarily applicable at the burner tip and does not represent a value equivalency at the wellhead. Given that the value ratio based on the current price of crude oil as compared to natural gas is significantly different from the energy equivalency of 6:1, utilizing a conversion on a 6:1 basis may be misleading as an indication of value. SOURCE Nexen Inc.