China Oilfield Services Ltd. is an investment holding company, which engages in the provision of offshore oilfield services. It operates through the following segments: Drilling Services, Well Services, Marine Support Services, and Geophysical Acquisition and Surveying Services. The Drilling Services segment provides oilfield drilling services. The Well Services segment includes the logging and downhole services, such as drilling fluids, directional drilling, cementing and well completion, and the sale of well chemical materials and well workovers. The Marine Support Services segment is composed of the transportation of materials, supplies and personnel to offshore facilities, moving and positioning drilling structures, the transportation of crude oil and refined products. The Geophysical and Surveying Services segment deals with offshore seismic data collection, marine surveying, and data processing services. The company was founded on February 15, 1982 and is headquartered in Langfang, China.