[ý ¨ Yes ¨ ý Yes ý ¨ Yes ¨ ý Yes ý ¨ ¨ Large accelerated filer ¨ ý ¨ U.S. GAAP] [Subsidiaries As of December 31, 2015, we owned, directly or indirectly, the following subsidiaries. Name of entity Our interest Jurisdiction of incorporation CNOOC China Limited 100% Tianjin, PRC CNOOC International Limited 100% British Virgin Islands China Offshore Oil (Singapore) International Pte Ltd 100% Singapore CNOOC Finance (2003) Limited 100% British Virgin Islands Malacca Petroleum Limited 100% Bermuda OOGC America LLC] [CNOOC Limited (incorporated under laws of Hong Kong with limited liability) 26 August 2015 I. INTRODUCTION Each of the directors and Senior Officers has the responsibility to obey the law and act honestly and ethically. To that end, this Code of Ethics is a guide intended to assist each of the directors and Senior Officers to decide to perform proper] [CERTIFICATIONS I, Fanrong Li, certify that: 1. I have reviewed this annual report on Form 20-F of CNOOC Limited; 2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made,] [CERTIFICATIONS I, Hua Zhong, certify that: 1. I have reviewed this annual report on Form 20-F of CNOOC Limited; 2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made,] [CERTIFICATIONS Fanrong Li, the Chief Executive Officer and Hua Zhong, the Chief Financial Officer of CNOOC Limited, each certifies that, to the best of his knowledge: 1. the Report fully complies with the requirements of Section 13(a) or 15(d) of the Exchange Act; and 2. the information contained in the Report fairly presents, in all material respects, the financial condition] [CNOOC LIMITED Estimated Future Reserves and Income Attributable to Certain Leasehold Interests and Derived Through Certain Production Sharing Contracts SEC Parameters As of December 31, 2015 \s\ Eric T. Nelson Eric T. Nelson, P.E. TBPE License No. 102286 Managing Senior Vice President [SEAL] RYDER SCOTT COMPANY, L.P. TBPE Firm Registration No. F-1580 RYDER SCOTT COMPANY PETROLEUM CONSULTANTS TBPE REGISTERED ENGINEERING] [Independent Letter The Missan Oil Fields In Eastern Iraq Prepared for CNOOC Limited st As at 31 March, 2016 This summary letter is based on Gaffney, Cline & Associates’ official report and has been provided at the request of CNOOC Limited. www.gaffney-cline.com Gaffney, Cline & Associates (Consultants) Pte. Ltd. 80 Anson Road #31-01C Fuji Xerox Towers Singapore 079907 Telephone: +65] [411 N. Sam Houston Parkway E., Suite 400, Houston, Texas 77060-3545 USA T F W January 31, 2016 CNOOC Limited No. 25, Chaoyangmenbei Dajie Dongcheng District Beijing 100010, P.R. China Gentlemen: CNOOC Limited holds 50% interest in Bridas Corporation and Bridas Corporation holds 40% interests in PAE. Therefore CNOOC Limited, through Bridas Corporation, owns 20% of participating interests in PAE.] [TBPE REGISTERED ENGINEERING FIRM F-1580 FAX (713) 651-0849 1100 LOUISIANA SUITE 4600 HOUSTON, TEXAS 77002-5294 TELEPHONE (713) 651-9191 January 26, 2016 CNOOC Limited c/o Nexen Energy ULC 801-7th Avenue S.W. Calgary, Alberta T2P 3P7 Canada Gentlemen: The properties reviewed by Ryder Scott account for all of OOGC’s total net proved reserves as of December 31, 2015. CNOOC has represented that] [January 20, 2016 CNOOC Limited c/o Nexen Energy ULC th 801 – 7 Calgary, Alberta T2P 3P7 Re: Gentlemen: Reserves included herein are expressed as reserves as represented by CNOOC. Gross reserves are defined as the total estimated petroleum to be produced from these properties after December 31, 2015. Working interest reserves are defined as that portion of the gross] [DeGolyer and MacNaughton 5001 Spring Valley Road Suite 800 East Dallas, Texas 75244 January 19, 2016 CNOOC Limited c/o Nexen Energy ULC 801-7th Avenue S.W. Calgary, AB, T2P 3P7 Canada Ladies and Gentlemen: Estimates of reserves included herein are expressed as reserves as represented by CNOOC. Gross reserves are defined as the total estimated petroleum to be produced from these] [CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM We consent to the incorporation by reference in the Post-Effective Amendment No.2 to the Registration Statement on Form F-3 (File No. 333-188261) of our reports dated March 24, 2016, relating to the consolidated financial statements of CNOOC Limited and its subsidiaries (the "Group"), and the effectiveness of the Group's internal control over financial] [TBPE REGISTERED ENGINEERING FIRM F-1580 FAX (713) 651-0849 1100 LOUISIANA SUITE 4600 HOUSTON, TEXAS 77002-5294 TELEPHONE (713) 651-9191 Consent of Independent Consultant RYDER SCOTT COMPANY, L.P. TBPE Firm Registration No. F-1580 Houston, Texas April 13, 2016 SUITE 600, 1015 4TH STREET, S.W. CALGARY, ALBERTA T2R 1J4 TEL (403) 262-2799 FAX (403) 262-2790 621 17TH STREET, SUITE 1550 DENVER, COLORADO 80293-1501] [Gaffney, Cline & Associates (Consultants) Pte. Ltd. 80 Anson Road #31-01C Fuji Xerox Towers Singapore 079907 Telephone: +65 6225 6951 www.gaffney-cline.com 13th April, 2016 CNOOC Limited No. 25, Chaoyangmenbei Daijie Dongcheng District Beijing 100010, P.R. China Dear Sir Consent of Gaffney, Cline & Associates st “Executive Report for Reserves Estimation of the Missan Oil Fields in Eastern Iraq as at] [411 North Sam Houston Parkway East, Suite 400, Houston, Texas 77060, USA T+1 281 448-6188 F +1 281 448-6189 W www.rpsgroup.com Consent of RPS RPS Houston, Texas April 13, 2016 UK I Ireland I Netherlands I Norway I USA I Canada I Brazil I Russia I UAE I Singapore I Malaysia I Australia RPS Group Plc Registered in England No.] [Consent of Independent Consultant McDANIEL & ASSOCIATES CONSULTANTS LTD. McDaniel & Associates Consultants Ltd. 2200, Bow Valley Square 3, 255 - 5 Avenue S.W. Calgary, Alberta, T2P 3G6 Canada March 31, 2016 2200, Bow Valley Square 3, 255 - 5 Avenue SW, Calgary AB T2P 3G6 Tel: (403) 262-5506 Fax: (403) 233-2744 www.mcdan.com] [DeGolyer and MacNaughton 5001 Spring Valley Road Suite 800 East Dallas, Texas 75244 Consent of DeGolyer and MacNaughton DeGOLYER and MacNAUGHTON Texas Registered Engineering Firm F-716 Dallas, Texas March 31, 2016]