News Release

Another Mid-to-large Sized Natural Gas Discovery Made on Independent Deepwater Exploration

(Hong Kong, January 6, 2015) - CNOOC Limited (the “Company”, NYSE: CEO, SEHK: 00883, TSX: CNU) today announced that the Company has successfully made a new mid-to-large sized natural gas discovery Lingshui 25-1 on the independent deepwater exploration.

The Lingshui 25-1 structure is located in the northeast of Ledong Sag in Qiongdongnan Basin of South China Sea, with an average water depth of about 980 meters. The discovery well Lingshui 25-1-1 was drilled and completed at a depth of about 4,000 meters and encountered the oil and gas pay zone with a total thickness of about 73 meters. The well was tested to produce about 35.6 million cubic feet of natural gas and 395 barrels of oil per day.

Lingshui 25-1 is another mid-to-large sized natural gas discovery following Lingshui 17-2 that the Company made on independent deepwater exploration. The new discovery has not only opened up a new exploration chapter in deepwater area of northern South China Sea, but also further proven the good exploration prospects in deepwater area of Qiongdongnan Basin.

—End —

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 "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 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 those associated with fluctuations in crude oil and natural gas prices, the exploration or development activities, the capital expenditure requirements, the business strategy, whether the transactions entered into by the Group can complete on schedule pursuant to its terms and timetable or at all, 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 files from time to time with the United States Securities and Exchange Commission, including the 2013 Annual Report on Form 20-F filed on 17 April 2014.

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.

*** *** *** ***

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. Cathy Zhang
Hill+Knowlton Strategies Asia
Tel: +852-2894 6211
Fax: +852-2576 1990
E-mail: cathy.zhang@hkstrategies.com