| 1.   | I                have reviewed this annual report on Form 20-F of CNOOC                Limited; |
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| 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, not misleading with respect to the period covered by this                report; |
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| 3.   | Based                on my knowledge, the financial statements, and other financial information                included in this report, fairly present in all material respects                the                financial condition, results of operations and cash flows of the                company                as of, and for, the periods presented in this                report; |
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| 4.   | The                company’s other certifying officer(s) and I are responsible for                establishing and maintaining disclosure controls and procedures (as                defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal                control over financial reporting (as defined in Exchange Act Rules                13a-15(f) and 15d-15(f)) for the company and                have: |
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| (a)   | Designed                such disclosure controls and procedures, or caused such disclosure                controls and procedures to be designed under our supervision, to                ensure                that material information relating to the company, including its                consolidated subsidiaries, is made known to us by others within those                entities, particularly during the period in which this report is                being                prepared; |
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| (b)   | Designed                such internal control over financial reporting, or caused such internal                control over financial reporting to be designed under our supervision,                to                provide reasonable assurance regarding the reliability of financial                reporting and the preparation of financial statements for external                purposes in accordance with generally accepted accounting                principles; |
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| (c)   | Evaluated                the effectiveness of the company’s disclosure controls and procedures and                presented in this report our conclusions about the effectiveness                of the                disclosure controls and procedures, as of the end of the period covered                by                this report based on such evaluation;                and |
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| (d)   | Disclosed                in this report any change in the company’s internal control over financial                reporting that occurred during the period covered by the annual report                that has materially affected, or is reasonably likely to materially                affect, the company’s internal control over financial reporting;                and |
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| 5.   | The                company’s other certifying officer(s) and I have disclosed, based on our                most recent evaluation of internal control over financial reporting,                to                the company’s auditors and the audit committee of the company’s board of                directors (or persons performing the equivalent                functions): |
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| (a)   | All                significant deficiencies and material weaknesses in the design or                operation of internal control over financial reporting which are                reasonably likely to adversely affect the company’s ability to record,                process, summarize and report financial information;                and |
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| (b)   | Any                fraud, whether or not material, that involves management or other                employees who have a significant role in the company’s internal control                over financial reporting. |
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|   |                                                                                                                                                                                                                                                                                                                                                                                                                                          |
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|   | By: /s/                Hua                Yang                                                                |
|   | Name:                Hua Yang                                                                                                                                                                                                                                                                                                                                                                                                                 |
|   | Title:                Executive Director, Executive Vice President and Chief Financial                Officer                                                                                                                                                                                                                                                                                                                                 |