China Oilfield Services Limited（''COSL''）is the leading integrated oilfield services provider in the offshore China market. Its services cover each phase of offshore oil and gas exploration, development and production. Its four core business segments are geophysical services, drilling services, well services, marine support and transportation services. COSL has listed its H shares on the Main Board of the Stock Exchange of Hong Kong Limited “HKSE” since 20 November 2002 under the ticker 2883. Since 26 March 2004, COSL’s stocks can be traded by means of Level I unlisted American Depositary Receipts at OTC over-the-counter market in the United States. The ticker symbol is CHOLY. COSL has listed its A shares on Shanghai Stock Exchange “SSE” under the ticker 601808 since 28 September 2007.

COSL possesses the largest fleet of offshore oilfield services facilities in China. To date, COSL operated 34 drilling rigs of which 27 are jack-up drilling rigs and 7 are semi-submersible drilling rigs, 2 accommodation rigs, 4 module rigs and 8 land drilling rigs. In addition, COSL also owns and operates the largest and most diverse fleets in offshore China, including 75 working vessels and 3 oil tankers, 5 chemical carriers, 8 seismic vessels, 5 surveying vessels, and a vast array of modern facilities and equipment for logging, drilling fluids, directional drilling, cementing and well work-over services, including FCT （Formation Characteristic Tool）, FET（Formation Evaluation Tool）, LWD （Logging-While-Drilling） and ERSC （ELIS Rotary Sidewall Coring Tool）, etc.

As the largest listed offshore oilfield services company in China, COSL not only provides services of single operations for the customers, but also offers integrated package and turnkey services; COSL’s business activities are conducted not only in offshore China, but also extended to different regions of the world including North and South America, the Middle East, Africa, Europe, South East Asia and Australia. COSL and its employees are dedicated to provide premier quality services, while adhering to the highest health, safety and environmental standards.

In 2011, COSL’s DOC Document of Compliance was approved by the Maritime Safety Administration of the People’s Republic of China for renewal of certificate. COSL maintained the certificates issued by DNV Det Norske Veritas through the annual review in compliance with ISO9001, ISO14001 and OHSAS18001 standards.

With the drive of “ALWAYS DO BETTER”, COSL will endeavor to provide domestic and international clients with safe, quality, productive and environmental protection services. COSL commits itself to realize win-win situation for shareholders, clients, employees and partners. It is steadily making headway toward being one of the world’s top class oilfield services companies.