Exchange Bulletin

CNOOC Limited (CNU) To Trade On Toronto Stock Exchange

September 16, 2013

CNOOC Limited - (the "Company") – An application has been granted for the original listing in the Oil and Gas category of up to 37,535,099 american depositary receipts ("ADRs") of which up to 8,182,567 ADRs will be issued and outstanding and up to 29,352,532 ADRs will be reserved for issuance.

The ADRs will be listed and posted for trading at the opening on Wednesday, September 18, 2013.

A summary of the attributes of the ADRs appears below.

Stock Symbol: "CNU"
CUSIP: 126132 10 9
Trading Currency: CDN

Temporary Market
Maker:Independent Trading Group

Other Markets:The ADRs are listed on New York Stock Exchange ("NYSE") under the symbol "CEO".

The shares of the Company ("Shares") are listed on the Stock Exchange of Hong Kong Limited under the symbol "0883".

Head Office Address:65/F, Bank of China Tower
1 Garden Road
Hong Kong

Head Office
Telephone Number:(852) 2213 2500

Fax Number:(852) 2525 9322

Investors Relations:Jianchun Ding
Tel.: (8610) 8452 2973

Yingxin Zhong
Tel.: (852) 2213 2502

Chief Financial Officer:Hua Zhong

Corporate Secretary:Hua Zhong and May Sik Yu Tsue

Incorporation:The Company was incorporated with limited liability on August 20, 1999 in Hong Kong under the Companies Ordinance (Chapter 32 of the Laws of Hong Kong).

Fiscal Year End:December 31

Nature of Business:The Company and its subsidiaries are the vehicles through which China National Offshore Oil Corporation engages in oil and gas exploration, development, production and sales activities both in and outside the People's Republic of China.

Transfer Agent &
Registrar of ADRs:JPMorgan Chase Bank, N.A. at its principal office in New York and CST Trust Company, as co-agent at its principal offices in Toronto and Calgary.

Depositary:JPMorgan Chase Bank, N.A.
Four New York Plaza
New York, New York 10004

Dividends:Subject to Hong Kong corporate law, the shareholders at a general meeting may declare dividends to be paid to shareholders in an amount not in excess of that recommended by the Company's board of directors (the "Board"). In addition, the Board may declare and pay to the shareholders interim dividends as deemed justified by the reserves of the Company. The most recent dividend was declared payable on October 17, 2013, to holders of ADRs of record as of September 5, 2013, in the anticipated amount (subject to finalization of foreign exchange rate), net of foreign exchange and withholding amount, of US$2.901353 per ADR. As the ADRs commence trading on Toronto Stock Exchange ("TSX") on September 18, 2013, and September 5, 2013 is the record date to determine holders of ADRs entitled to receive the dividend payable October 17, 2013 (the "October Dividend"), the ADRs trading on TSX will not carry an entitlement to the October Dividend.

The following is a summary of some of the attributes of the ADRs. Reference should be made to the deposit agreement (the "Deposit Agreement") dated January 15, 2001 among the Company and Morgan Guaranty Trust Company of New York (the "Depositary"), as amended March, 2004, for complete attributes of the ADRs.

The ADRs are registered with the United States Securities and Exchange Commission with JPMorgan Chase Bank, N.A. acting as depositary agent through which holders of Shares can exchange their Shares for ADRs (subject to the payment of certain fees to the Depositary) on the basis of one ADR for each one hundred Shares. The Shares are posted for trading on the Stock Exchange of Hong Kong Limited and the ADRs are posted for trading on TSX and NYSE. Shares are exchangeable at any time at the option of the holder on the basis of one ADR for every one hundred Shares exchanged.

Holders of ADRs do not have the same rights as shareholders of the Company. Holders of ADRs will have the rights as set forth in the Deposit Agreement with the Depositary, who will be the holder of the Shares underlying the ADRs. The Deposit Agreement will be available under the Company's SEDAR profile at

As soon as practicable after receipt from the Company of a notice of any meeting or solicitation of consents or proxies of holders of Shares or other deposited securities, the Depositary shall distribute to the holders of ADRs a notice stating (a) such information as is contained in such notice and any solicitation materials, (b) that each holder of ADRs on the record date set by the Depositary therefor will be entitled to instruct the Depositary as to the exercise of the voting rights, if any, pertaining to the Shares underlying the holder's ADRs and (c) the manner in which such instructions may be given, including instructions to give a discretionary proxy to a person designated by the Company. The Depositary will not itself exercise any voting discretion in respect of any Shares.

If any tax or other governmental charge shall become payable by the Depositary with respect to any ADR, a deposited Share underlying the ADRs or any distribution thereon, such tax or charge shall be payable by the owner of the ADR to the Depositary.

Whenever the Depositary shall receive any cash dividend, other cash distribution, or distribution other than a cash distribution, the Depositary shall convert such cash dividend or cash distribution into US dollars and distribute this cash amount, or other distribution other than cash, if lawful and practicable (net of any withholding taxes and expenses of the Depositary) on a pro rata basis to holders of ADRs as at records dates to be appropriately set. Such US dollars available will be distributed by cheques drawn on a bank in the United States for whole dollars and cents. Fractional cents will be withheld without liability and added to future cash distributions.