Recently, CNOOC reported that in 2024, China’s total number of offshore drilling rigs exceeded 1,000 for the first time, and more than 10 key technologies achieved breakthroughs.

Offshore drilling and completion operations are characterized by high risk, high cost, and advanced technology. Since the start of the 14th Five-Year Plan, China has continuously achieved breakthroughs in offshore drilling and completion technologies, with the average annual number of offshore wells increasing by more than 60% compared to the 13th Five-Year Plan period. Among the offshore wells drilled in 2024, the Enping 21-4-A1H well set two national records: the deepest offshore well depth and the largest horizontal displacement.

Over a thousand offshore drilling wells have been successfully developed thanks to solid and optimized production capacity design. Guided by the “fewer wells, higher production” philosophy, CNOOC has established a technological portfolio encompassing four key areas—well-type optimization, increased production, long-term stable production, and tapping into remaining oil reserves—and more than ten critical technologies. These efforts actively address the major challenges faced in offshore oil and gas field development, such as ensuring stable production in mature fields and effectively developing low-quality reserves.

“In 2024, CNOOC achieved its best-ever performance in key indicators such as daily drilling efficiency, production uptime, and equipment downtime, paving the way for significant advances in offshore oil and gas exploration and development,” said Li Zhong, Chief Engineer of the China National Offshore Oil Corporation (CNOOC) Research Institute and an expert in drilling and well completion. In 2024, CNOOC completed 13 basic designs for drilling and well completion projects throughout the year, leveraging technological innovation and the commercialization of research findings to promote effective development in complex areas including deepwater, mid-to-deep formations, shallow-water subsea operations, and low-permeability reservoirs.

In the shallow-water sector, CNOOC has taken the lead in developing an underwater production tree system for shallow-water electric submersible pumps, establishing a subsea drilling and completion operation mode conducted below the mudline, and successfully applying it to the Jinzhou 25-1W oilfield. By optimizing installation procedures and tools, the duration of diving operations has been reduced by over 70%, providing an efficient solution for oil and gas development in restricted marine areas.

In the deepwater sector, the blowout prevention operation for Well A12—the second phase of China’s “Deepsea No. 1” project, which boasts the highest offshore gas pressure in China—was successfully completed in August 2024. The test production exceeded expectations, marking the completion of all offshore drilling and well completion operations for the second phase of China’s first deepwater high-pressure gas development project, “Deepsea No. 1.” The total well depth exceeded 60,000 meters, and the operational schedule was shortened by 30% compared to the original design. Moreover, the quality compliance rate for these operations reached 100%. “In terms of exploring digital and intelligent approaches for deepwater gas field development, we have collaborated with relevant institutions and achieved phased results in areas such as digital wellbores, intelligent drilling navigation, and smart wellbore construction. By leveraging innovative technologies, we’ve significantly accelerated and improved the efficiency of on-site operations,” Li Zhong said.

In the field of high temperature and high pressure, CNOOC has tackled challenges in offshore drilling and completion operations involving “narrow pressure windows”—such as deepwater high-temperature and high-pressure as well as ultra-high-temperature and high-pressure environments—by developing advanced technologies for precise pressure control during offshore drilling and pressure-controlled cementing. These technologies achieve precision control within 0.2 megapascal and have been successfully applied to pressure-controlled drilling operations at the Caofeidian 23-6 oilfield.

With over a thousand offshore drilling rigs in operation, the continuous upgrading of digital and intelligent safety management technologies has become indispensable. The “Tianyan Project” deeply integrates advanced machine vision technology with drilling and well-completion operations, pioneering 10 specialized video recognition scenarios for drilling and well completion in China. After this technology was deployed on the “Haiji No. 1” platform, the average daily number of alarms dropped from 1.55 to just 0.1, effectively serving as a deterrent and helping the drilling and well-completion development project achieve its goal of “zero accidents” across 345,000 man-hours.