Washington, D.C. 20549
Report of Foreign Private Issuer
Pursuant to Rule 13a-16 or 15d-16
of the Securities Exchange Act of 1934

For the month of September 2012

Commission File Number 1-14966

CNOOC Limited
(Translation of registrant’s name into English)
65th Floor
Bank of China Tower
One Garden Road
Central, Hong Kong
(Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

Form 20-F      X          Form 40-F ___

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1): ____

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7): ____

Indicate by check mark whether by furnishing the information contained in this Form, the registrant is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.

Yes ___        No     X   

If "Yes" is marked, indicate below the file number assigned to the registrant in connection with Rule 12g3-2(b):  Not applicable



Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

CNOOC Limited
/s/ Hua Zhong
Hua Zhong
Joint Company Secretary
Dated: September 21, 2012




Exhibit No. Description
99.1 Announcement dated September 21, 2012, entitled Announcement on Progress relating to the Proposed Acquisition of Nexen.

Exhibit 99.1

Hong Kong Exchanges and Clearing Limited and The Stock Exchange of Hong Kong Limited take no responsibility for the contents of this announcement, make no representation as to its accuracy or completeness and expressly disclaim any liability whatsoever for any loss howsoever arising from or in reliance upon the whole or any part of the contents of this announcement.

(Incorporated in Hong Kong with limited liability under the Companies Ordinance)
(Stock Code: 00883)


Reference is made to the Company’s announcement dated 23 July 2012 (the “Announcement”) in relation to the Proposed Acquisition by the Company (through its wholly-owned subsidiary, the Purchaser) of the Nexen Shares pursuant to a Plan of Arrangement under the CBCA. Capitalized terms used herein shall have the same meanings as those defined in the Announcement unless the context requires otherwise.

The Board is pleased to announce that, on 20 September 2012 (Canada local time), the Court has granted the Final Order which approved the Plan of Arrangement pursuant to CBCA. The Final Order was granted following a meeting of Nexen shareholders on the same day at which the Plan of Arrangement was approved by approximately 99% of the votes cast by the holders of the Common Shares. As approximately 87% of the votes cast by the holders of Preferred Shares also approved the Plan of Arrangement, the Plan of Arrangement will also include the Preferred Shares.

Further announcement on the progress of the Proposed Acquisition will be made as appropriate.

Shareholders and potential investors should note that the Proposed Acquisition is subject to various conditions which may or may not be fulfilled. There is therefore no assurance that the Proposed Acquisition will proceed and, if it proceeds, on what terms it may proceed. Shareholders and potential investors are reminded to exercise caution when dealing in the Shares of the Company.

By Order of the Board
CNOOC Limited
Zhong Hua
Joint Company Secretary

Hong Kong, 21 September 2012


As at the date of this announcement, the Board comprises the following:

Executive Directors
Independent Non-executive Directors
Li Fanrong
Chiu Sung Hong
Wu Guangqi
Lawrence J. Lau
Tse Hau Yin, Aloysius
Wang Tao
Non-executive Directors
Wang Yilin (Chairman)
Yang Hua (Vice Chairman)
Zhou Shouwei
Wu Zhenfang