China Oilfield Services Limited (COSL) is launching a significant five-year fleet modernization program from 2026 to 2030. This initiative aims to capitalize on strong exploration activity in the South China Sea and replace aging assets. The plan is part of a broader effort to expand the company's total offshore service fleet by nearly 300 units, which includes various vessels beyond drilling rigs.

New Rig Construction Plans

The core of the expansion involves a newbuilding program for semi-submersible and jack-up rigs. COSL plans to construct one deepwater semi-submersible with two optional units, and two jack-up rigs with an option for two more. The first two semi-subs are designed for water depths up to 1,000 meters using a spread mooring system. The optional third semi-sub would be capable of operating in 1,500-meter waters and feature a DP3 dynamic positioning system. For the jack-ups, the company is focusing on the CJ50 design, suitable for water depths up to 400 feet.

Engineering and Construction

Engineering work on the new units is already in progress. The semi-submersible designs are being handled by China Offshore Engineering & Technology. For the jack-ups, China Merchants Heavy Industry (CMHI) and the Marine Design and Research Institute of China (Maric) are involved. COSL is expected to use China-built drilling equipment packages, continuing its practice of domestic procurement. The company has a history of building rigs at major Chinese yards and may conduct bilateral negotiations with individual shipyards instead of open tenders.

Fleet Renewal Rationale and Strategic Context

The fleet renewal addresses the aging nature of some assets within COSL's current fleet, which is the world's largest offshore drilling fleet. The program is supported by increased capital spending, with 2026 guidance allocating 8.4 billion yuan for equipment investment, upgrades, technological transformation, R&D, and base construction. This strategic push aligns with national goals to maximize domestic offshore oil and gas output—which accounted for about 21% of China's total production last year—reduce import reliance, and strengthen COSL's position in international drilling markets.