(Hong Kong, November 28, 2011) - CNOOC Limited (the "Company", NYSE: CEO, SEHK: 0883) announced today that CNOOC Luxembourg S.¨¤ r.l, an indirect wholly-owned subsidiary of the Company, has completed its acquisition of OPTI Canada Inc. ("OPTI"). The total value of the consideration is approximately US$2.1 billion. An application to delist the OPTI Shares will be filed by OPTI with the TSX Venture Exchange on the completion date to coincide with the completion of the transaction. Subject to approval by the TSX Venture Exchange, the delisting of the OPTI Shares is anticipated to be effective on December 1, 2011. In addition, OPTI will redeem on December 28, 2011 all of its outstanding First Lien Notes at a price equal to 102% of the principal amount of the First Lien Notes plus accrued and unpaid interest to the date of redemption, pursuant to the indentures governing the First Lien Notes. The First Lien Notes consist of US$525 million principal amount of 9% First Lien Notes due 2012 and US$300 million principal amount of 9.75% First Lien Notes due 2013.

Mr. Li Fanrong, newly appointed Chief Executive Officer of the Company commented, "Closing of this acquisition demonstrates that the Company has further stepped into the oil sands business, which has become one of the important assets to the Company’s global portfolio. Through partnership with Nexen, the Company expects to fully exploit the growth potential of the Long Lake Project and the three other jointly owned oil sands leases. We believe that the project will contribute to the Company’s mid to long term reserve and production growth."

The Company’s financial advisors are BMO Capital Markets and CIBC World Markets. The Company’s legal advisor is Gowling Lafleur Henderson LLP.