[CNOOC Limited]

[CNOOC Limited]

[THIS REPORT ON FORM 6-K SHALL BE DEEMED TO BE INCORPORATED BY REFERENCE IN THE REGISTRATION STATEMENT ON FORM F-3 (FILE NOS. 333-188261 AND 333-188261-02) OF CNOOC LIMITED AND CNOOC NEXEN FINANCE (2014) ULC TO BE A PART THEREOF FROM THE DATE ON WHICH THIS REPORT IS FILED, TO THE EXTENT NOT SUPERSEDED BY DOCUMENTS OR REPORTS SUBSEQUENTLY FILED OR]

[CNOOC Limited Hua Zhong Joint Company Secretary Dated: April 28, 2014 Description 99.1 This announcement is not an offer to sell or a solicitation of any offer to buy the securities of CNOOC Limited (the “ Company ”) or any of its subsidiaries (the “ Securities SEC NOTICE OF LISTING ON]

[CNOOC Limited Hua Zhong Joint Company Secretary Dated: April 23, 2014 Description 99.1 Press Release dated April 24, 2014. CNOOC Limited Announces Pricing of Guaranteed Notes Offering (Hong Kong, April 24, 2014) - CNOOC Limited (the “Company”, NYSE: CEO, SEHK: 00883, TSX: CNU) announced on April 23, 2014 (New York time) the pricing of its offering of US$4,000 million aggregate]