CNOOC Limited Announces Bozhong 19-4 Oilfield Comprehensive Adjustment Project Commences Production

HONG KONG,Sept. 24,2021 --CNOOC Limited (the "Company",SEHK: 00883,NYSE: CEO,TSX: CNU) today announced that Bozhong 19-4 oilfield comprehensiveadjustment project has commenced production.

Bozhong 19-4 oilfield comprehensiveadjustment project is located in the south of Bohai Sea,with average water depth of about 21 meters. In addition to fully utilizing the existing processing facilitiesof Bozhong 25-1 oilfield,the project has built a neweight-legged central equipment platform. A total of 25 development wells are planned,including 18 production wells,7 water injection wells. The project is expected to reach its peak production of approximately 11,000 barrels of crude oil per day in 2022.

CNOOC Limited holds 100% interest in Bozhong 19-4 oilfield comprehensiveadjustment project and acts as the operator.

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Notes to Editors:

More information about the Company is available at http://www.cnoocltd.com.

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This press release includes "forward-looking statements" within the meaning of the United States Private Securities Litigation Reform Act of 1995,including statements regarding expected future events,business prospectus or financial results. The words "expect","anticipate","continue","estimate","objective","ongoing","may","will","project","should","believe","plans","intends" and similar expressions are intended to identify such forward-looking statements.

These statements are based on assumptions and analyses made by the Company in light of its experience and its perception of historical trends,current conditions and expected future developments,as well as other factors that the Company believes are appropriate under the circumstances. However,whether actual results and developments will meet the expectations and predictions of the Company depends on a number of risks and uncertainties which could cause the actual results,performance and financial condition to differ materially from the Company's expectations,including but not limited to the Company and its controlling shareholder being listed in the list of the U.S. for sanction against companies with alleged ties to the Chinese military,those associated with fluctuations in crude oil and natural gas prices,macro-political and economic factors,changes in the tax and fiscal regimes of the host countries in which we operate,the highly competitive nature of the oil and natural gas industry,environmental responsibility and compliance requirements,the Company's price forecast,the exploration and development activities,mergers,acquisitions and divestments activities,HSSE and insurance policies and changes in anti-corruption,anti-fraud,anti-money laundering and corporate governance laws. For a description of these and other risks and uncertainties,please see the documents the Company files from time to time with the United States Securities and Exchange Commission,including the Annual Report on Form 20-F filed in April of the latest fiscal year. Consequently,all of the forward-looking statements made in this press release are qualified by these cautionary statements. The Company cannot assure that the results or developments anticipated will be realised or,even if substantially realised,that they will have the expected effect on the Company,its business or operations.

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For further enquiries,please contact:

Ms. Jing Liu

Manager,Media & Public Relations

CNOOC Limited

Tel: +86-10-8452-3404

Fax: +86-10-8452-1441

E-mail: mr@cnooc.com.cn

Bunny Lee

Porda Havas International Finance Communications Group

Tel: +852 3150 6707

Fax: +852 3150 6728

E-mail: cnooc.hk@pordahavas.com