China National Offshore Oil Corporation (CNOOC) announced on Monday that the country's highest-pressure offshore natural gas well - the No. A12 well of the phase II project of Shenhai Yihao, or Deep Sea No. 1 - has completed its drilling operation, marking the conclusion of all offshore drilling and completion work of the project.
The well has tested a daily production of 830,000 cubic meters.
Deep Sea No. 1 is China's first independently-developed and built ultra-deepwater gas field.
Located in the Lingshui area southeast of Hainan Island, the Phase II project is China's pioneering deep-water high-pressure gas field project, operating at depths approaching 1,000 meters. The project features 12 deep-water gas wells, with an average well depth exceeding 5,000 meters.
Jiang Donglei, project manager for the well completion project at CNOOC, detailed the major challenges faced in their operations.
"The greatest challenge in developing deep-water high-pressure gas fields is well completion operations. We must establish a safe transportation channel for deep-sea oil and gas. The Phase II project includes 12 wells with a total depth exceeding 60,000 meters, equivalent to the height of seven Mount Everest peaks. The formation pressure reaches up to 69 MPa, which is 1,000 times the pressure of a household pressure cooker. The technical difficulty of this project is significantly higher than that of Phase I," he said.
The project faces four major world-class challenges: deep water, deep layers, high temperatures, and high pressures, with no precedents globally.
CNOOC's technical team, in collaboration with domestic research institutions like China University of Petroleum, has conducted systematic research on the complex conditions of deep-water high-pressure wells, focusing on breakthroughs in key technologies.
"Through independent innovation, we have established a core technology system for drilling and completion operations of deep-water high-pressure wells. We have developed five world’s first key technologies for drilling and completion operations of deep-water high-pressure wells, enhancing the project's safety and efficiency. We have also set multiple world records in deep-water drilling and completion operations, improving overall project efficiency by over 30 percent and achieving a 100-percent engineering quality acceptance rate, laying a solid foundation for the smooth commissioning of the gas field," said Ma Chuanhua, deputy project manager of the well completion project at the CNOOC.
Deep Sea No. 1 which began production in June 2021, has proven geological reserves exceeding 100 billion cubic meters.
The Phase II project is located about 70 kilometers from the energy station of the gas field.
Upon full production, it will increase the gas field's reserves from 100 billion cubic meters to 150 billion cubic meters and its annual production from 3 billion cubic meters to 4.5 billion cubic meters.
China's deep sea gas field project achieves milestone in drilling, production
China's deep sea gas field project achieves milestone in drilling, production
