CNOOC Boosts Offshore Oil and Gas Output via Tech Innovation and Facility Upgrades

China National Offshore Oil Corporation continues to strengthen domestic oil and gas reserve expansion and output growth, serving as a core driver of national energy security. The company advances stable production through integrated strategies including mature oilfield potential tapping, new field development, marginal resource utilisation and ageing facility upgrading, consolidating domestic offshore energy reserves and underpinning the development of China’s energy and marine power sectors.

Bohai Oilfield, China’s largest offshore crude oil production base, faces growing challenges in tapping potential reserves after over six decades of exploration and production. To address technical bottlenecks, the oilfield adopts a balanced development model combining mature field optimisation and new field expansion supported by technological innovation.

The Kenli 10-2 Oilfield, commissioned in 2025, is the first 100-million-tonne lithologic oilfield discovered in shallow formations of the Bohai Bay Basin. Its complex dendritic reservoir structure and heavy oil thermal recovery model lack mature global development precedents. Technical teams have adopted innovative reservoir characterisation technologies, lifting the reservoir drilling encounter rate above 90 per cent. Optimised thermal recovery solutions have significantly improved the utilisation efficiency of unconventional heavy oil reserves.

Suizhong 36-1 Oilfield, China’s largest self-operated offshore oilfield with cumulative crude output exceeding 100 million tonnes, confronts high water cut and advanced production maturity after more than 30 years of operation. Targeted improvements focusing on secondary comprehensive adjustment, precise injection-production optimisation and digital empowerment have revitalised the ageing field. Innovative interlayer oil control theories and differentiated extraction strategies have enabled new single wells in high-water zones to achieve a peak daily output of 150 tonnes. Fine flow field regulation and grid-based numerical modelling enhance the accuracy of remaining oil exploitation and intelligent production management.

CNOOC’s Shenzhen branch prioritises stable production and efficiency improvement through technological breakthroughs to unlock hard-to-recover reserves. Two ultra-deep extended-reach wells exceeding 7,000 metres have been successfully drilled at the Xijiang 24-4 Oilfield. Extended-reach wells feature a horizontal-to-vertical depth ratio above two and a total depth over 3,000 metres, posing extreme construction difficulties.

To overcome complex drilling challenges including difficult deflection and poor cuttings carrying capacity, the project team applied optimised reaming technologies and non-standard casing designs to refine wellbore structures. Precise hydraulic parameter adjustment and continuous hole cleaning operations enabled stable drilling across a 3,500-metre inclined section without tripping. The two wells set new daily drilling efficiency records for 7,000-metre extended-reach wells in the eastern South China Sea, converting previously uneconomical marginal reserves into profitable production resources.

Systematic facility upgrades further support sustainable offshore output growth. CNOOC’s equipment technology subsidiary carries out targeted renovation programmes for ageing offshore platforms. Upgrades at the Nanpu 35-2 Oilfield cover comprehensive restoration of walkways, storage tanks, pipelines and auxiliary structures, extending equipment service life. Adaptive transformations across multiple Enping offshore platforms optimise mechanical structural stability, enhance electrical instrument maintainability and anti-interference performance, and implement full-coverage anti-corrosion treatments. These systematic improvements strengthen operational safety stability and overall production efficiency of offshore facilities.

Through synergised technological innovation, marginal resource development and infrastructure optimisation, CNOOC steadily expands exploitable offshore hydrocarbon reserves. Ongoing technical breakthroughs and facility upgrades will sustain high-efficiency, stable offshore energy production to reinforce national energy supply stability.