COSL maintains three domestic-sited Oil Tools Operation Bases:

Tianjin Tanggu Oil Tools Operation Base containing four workshops and inventories more than 98 complete sets of specialized and specified equipments. The Base is fully complemented by a team of experienced and highly trained professional personnel. Adhering to API SPEC7-1, NS-2 and related standards, COSL can confidently offer its customers high standards of excellence in providing inspection and repairs to oilfield equipments.

On September 29, 2024, Shenzhen Oil Tools Operation Base obtained the official authorization certificate issued by MHWirth Offshore Petroleum Engineering (Shanghai) Co., Ltd. It is authorized to repair well control equipment such as Hydril BOPs, Vetco Gray diverters, and Vetco Gray H-4 Connectors. The original manufacturer COC certificate is issued under the witness of HMH. The Base has carried out many cooperation with internationally renowned manufacturers such as CAMERON and NOV on obtaining the original COC certificate for well control equipment such as BOPs. The Base is responsible for part of the disassembly, overhaul and testing work. The original manufacturer is responsible for repair and quality control and issues the COC certificate. At the same time, the Base is applying for them inspection and maintenance authorization certificate for further in-depth cooperation.

Zhanjiang Oil Tools Operation Base is a professional institution that has been in operation for over 30 years, specializing in inspection and repair of drilling tools. The base has a professional team with the ability to conduct non-destructive testing and repair of various oilfield tubulars (drilling tools, casing and tubing) and workpieces, with complete qualifications and advanced equipment. For many years, it has provided related services for platforms in the Western South China Sea, the Eastern South China Sea, and the East China Sea, both domestically and internationally. The inspection standards are comprehensive, the service is of high quality and prompt, and it enjoys a high reputation in the domestic industry.