15 February 1982 China National Offshore Oil Corporation (CNOOC), PRC State-owned Enterprise Established

25 December 2001 CNOOC Incorporated CNOOCS as the Operating Company
Prior to December 2001, CNOOC provided drilling, well and geophysical services primarily through five PRC wholly owned subsidiaries, namely, China Offshore Oil Southern Drilling Company, China Offshore Oil Northern Drilling Company, China Offshore Geophysical Company Limited, China Offshore Logging Company Limited and CNOOC Petrotech Services Company. On December 25, 2001, CNOOC incorporated these five companies as the operating company CNOOCS for the business operations that perform drilling, well and geophysical services.

29 December 2001 CNOOC Incorporated Two Shipping Companies into One
CNOOC combined two marine support and transportation subsidiaries, CHina Offshore Oil Southern Shipping Company and China Offshore Oil Northern Shipping Company, into one entity.

26 September 2002 Our Company Was Restructured into a Joint Stock Limited Liability Company
With the approval of the PRC Government, COSL was officially chartered with State Administration for Industry and Commerce.

20 November 2002 China Oilfield Services Limited was successfully listed on mainboard of HongKong stock market.
China Oilfield Services Limited was successfully listed on mainboard of HongKong stock market.

26 March 2004  The stocks of China Oilfield Services Limited can be traded by means of levelⅠunlisted American Depositary Receipts ("ADRs") at OTC (over-the-counter) market in the United States. The ticker symbol is CHOLY.

28 October 2007 China Oilfield Services Limited was successfully listed on Shanghai stock exchange.

29 September 2008 China Oilfield Services Limited completed the acquisition of Awilco Offshore ASA successfully