OREANDA-NEWS. April 07, 2014. This announcement is made pursuant to the Inside Information Provisions under Part XIVA of the Securities and Futures Ordinance (Chapter 571 of the laws of Hong Kong) and Rule 13.09 of the Rules Governing the Listing of Securities on The Stock Exchange of Hong Kong Limited (the “Listing Rules”).

The board of directors (the “Board”) of CNOOC Limited (the “Company”) hereby announces that the Company has made a new exploration discovery of Ningbo 22-1 at the East China Sea in
a cooperation project with Sinopec.

The Company has 50% participating interests in such project. Concrete information in relation to the reserve of such discovery has not yet been determined. In accordance with the applicable PRC laws and regulations, the aforesaid discovery is subject to the regulatory approvals before any further work can be carried out.

Further announcement on such discovery will be made in accordance with the Inside Information Provisions under Part XIVA of the Securities and Futures Ordinance (Chapter 571 of the laws of Hong Kong) and Rule 13.09 of the Listing Rules as appropriate.

In the meanwhile, shareholders and potential investors should exercise caution in dealing in the Company’s shares.