CNOOC : Notification Letter and Request Form For Non-Registered Holders

（根據公司條例在香港註冊成立的有限責任公司）

( Incorporated in Hong Kong with limited liability under the Companies Ordinance)

（股份代碼：00883）

C N O OC Li mi t e d (t he " C ompa ny " )

- N ot ic e of publ i c a ti on of C i rc ul ar, N ot ic e of E xt ra or di na r y Ge ne ra l Me et i ng and P roxy F or m ( "C ur re nt C or por a te Co mmu ni c a t i ons " )

16 November 2016

The English and Chinese versions of the Company's Current Corporate Communications are available on the Company's website at w w w. cn oo c lt d.c o m and the HKEXnews' website at ww w. h ke xn ew s. h k. You may access the Current Corporate Communications by clicking "Investor Relations" on the home page of our website, then selecting "Name of document" under "Announcement" and viewing them through Adobe® Reader® or browsing through the HKEXnews' website.

If you want to receive a printed version of the Current Corporate Communications, please complete the Request Form on the reverse side and return it to the Company c/o Hong Kong Registrars Limited (the "Hong Kong Share Registrar") by using the mailing label at the bottom of the Request Form (no need to affix a stamp if posted in Hong Kong; otherwise, please affix an appropriate stamp). The address of the Hong Kong Share Registrar is 17M Floor, Hopewell Centre, 183 Queen's Road East, Wanchai, Hong Kong. The Request Form may also be downloaded from the Company's website at w w w.c n oo cl td .c o m or the HKEXnews' website at w w w. h ke xn ew s. h k.

Should you have any queries relating to any of the above matters, please call the Company's telephone hotline at (852) 2862 8688 during business hours from 9:00 a.m. to 6:00 p.m. Monday to Friday, excluding public holidays or send an email to C n oo c. ec o m@c o mp ut er sh a re. co m. h k.

Yours faithfully, By order of the Board

CNOOC Limited Li Jiewen

Joint Company Secretary

Note: (1) This letter is addressed to Non- registered holders ("Non- registered holder" means such person or company whose shares are held in The Central Clearing and Settlement System (CCASS) and who has notified the Company from time to time through Hong Kong Securities Clearing Company Limited to receive Corporate Communications). If you have sold or transferred your shares in the Company, please disregard this letter and the Request Form on the reverse side.