Successful Appraisal of Qinhuangdao 29-2

Qinhuangdao 29-2 is located in the central north of Bohai, with an average water depth of about 27 meters. These two successful appraisal wells expanded the reserve base of Qinghuangdao 29-2. Qinghuangdao 29-2E-4 drilled in the middle formation of the Qinghuangdao 29-2 east structure represented a significant breakthrough by encountering 218.4 meter thick of oil pay zones, including a 133.7 meter thick single oil pay zone. This well was tested to produce approximately 6,600 barrels and 4.5 million cubic feet of natural gas per day, creating the highest capacity of clastic rocks in Bohai.

Mr. Li Fanrong, CEO of the Company commented, "I am very pleased that the Company has realized another large discovery through these successful appraisals. I believe Qinghuangdao 29-2 will provide firm support to the Company's reserve and production growth in the near future."

Notes to Editors:

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

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 "believe", "intend", "expect", "anticipate", "project", "estimate", "plan", "predict" and similar expressions are intended to identify such forward-looking statements. These statements are based on assumptions and analysis made by the Company in light of its experience and perception of historical trends, current conditions and expected future developments, as well as other factors that the Company believes reasonable under the circumstances. However, whether actual results and developments will meet the Company's expectations and predictions depends on a number of risks and uncertainties which could cause the actual results, performance and financial conditions to differ materially from the Company's expectations, including those associated with fluctuations in crude oil and natural gas prices, the exploration or development activities, the capital expenditure requirements, the business strategy, the highly competitive nature of the oil and natural gas industries, the foreign operations, environmental liabilities and compliance requirements, and economic and political conditions in the People's Republic of China. For a description of these and other risks and uncertainties, please see the documents the Company has filed from time to time with the United States Securities and Exchange Commission, including 2011 Annual Report on Form 20-F filed on April 20, 2012.

Consequently, all of the forward-looking statements made in this press release are qualified by these cautionary statements. The Company cannot assure that the actual results or developments anticipated will be realized or, even if substantially realized, that they will have the expected effect on the Company, its business or operations.

For further enquiries, please contact:

Ms. Michelle Zhang
Deputy Manager, Media / Public Relations
CNOOC Limited
Tel: +86-10-8452-6642
Fax: +86-10-8452-1441
E-mail: MR@cnooc.com.cn

Ms. Angela Hui
Ketchum Newscan Public Relations Ltd
Tel: +852-3141-8091
Fax: +852-2510-8199
E-mail: angela.hui@knprhk.com