On April 9, CNOOC Limited announced that the underwater engineering operation of the second phase of the "Shenhai No. 1" project in Hainan waters has made important progress, and all three sets of deepwater underwater central manifolds with the largest weight and most complex structure have been successfully installed in place, which is also the first time that the deepwater underwater multi-functional manifold system independently built by CNOOC has been applied to the development of deepwater high-temperature and high-pressure oil and gas reservoirs, which is of great significance for strengthening the deepwater oil and gas development equipment industry chain in mainland China and improving the development capacity of deepwater complex oil and gas resources.
Offshore operators inspect the deep-water central manifold that is about to be installed in the subwater.
Located in the Qiongdongnan Basin in the western part of the continental shelf in the northern part of the South China Sea, about 132 kilometers away from Sanya City and about 70 kilometers away from the "Shenhai No. 1" energy station, the second phase of the "Shenhai No. 1" project is the first deep-water high-pressure gas field project in mainland China, with proven natural gas geological reserves of more than 50 billion cubic meters, a maximum operating water depth of nearly 1,000 meters, the deployment of 12 underwater gas wells and a new set of deepwater underwater production system.
Qian Jiangwei, chief engineer of the construction of the underwater production facilities of the second phase of the "Shenhai No. 1" project, said that the second phase of the "Shenhai No. 1" pioneered the mode of "underwater production system + shallow water jacket processing platform + deep-water semi-submersible platform remote control system" to develop deep-sea oil and gas resources. Its underwater production system mainly includes a complete set of underwater equipment such as central manifold, serving manifold, suction pile, umbilical cable, etc. After the completion of the second phase of the project, the "Shenhai No. 1" energy station will be remotely controlled by the umbilical cable to achieve the goal of fully relying on the existing oil and gas production equipment to develop deep-sea oil and gas resources economically and efficiently.
According to reports, the underwater central manifold is one of the core technical equipment for the development of deepwater oil and gas fields, distributed between the wellhead groups on the seabed, and plays an important role in bringing together the deep-sea oil and gas to transport to the platform.
The deep-water underwater central manifold used in the second phase of the "Shenhai No. 1" project is being slowly lifted by the operating vessel.
The total weight of all three sets of underwater central pipes in the second phase of "Shenhai No. 1" exceeded 540 tons, and the first and second sets were installed at the end of last year and the beginning of this year respectively. The installation of the third set of underwater central manifold (south manifold) is connected to 7 underwater gas wells, which is the heaviest underwater structure of the project, with a lifting weight of 187 tons, and is installed by the mainland's first 3,000-meter-class deep-water multi-functional engineering vessel "Offshore Oil 286".
Deep-water underwater operations usually face the adverse effects of ultra-high hydrostatic pressure, unstable ocean currents, and dark seabed environment, so it is necessary to accurately monitor the state of the hook head and counterweight of the main crane during the offshore installation and decentralization of the central manifold, and at the same time ensure the stability and accuracy of the central manifold when aligning with the suction pile on the seabed, and the installation difficulty is like the docking of a "manned spacecraft" in space.
The deep-water underwater central pipe used in the second phase of the "Shenhai No. 1" project enters the water at the moment.
Gao Xuanpeng, deputy general manager of the second phase of the "Shenhai No. 1" general contracting project, said that the installation coincided with the offshore monsoon season, and the climate environment and sea conditions were complex and changeable, which brought great challenges to the installation and decentralization operations. To this end, the project team repeatedly optimized the construction plan and successfully overcame technical problems such as wire rope twisting in ultra-deepwater engineering operations, "refreshing the record of the depth of double-rope hoisting operations in mainland marine engineering, reaching 960 meters." ”
In the next step, the CNOOC "Shenhai No. 1" Phase II project team will continue to install umbilical cables, oil and gas transmission hoses, underwater Christmas trees and other facilities on the basis of the existing construction, so as to prepare for the completion of the project on schedule. After the project is put into operation, the overall peak annual output of the "Shenhai No. 1" gas field will be increased from 3 billion cubic meters to 4.5 billion cubic meters, further increasing the proportion of deepwater oil and gas resources in the mainland's oil and gas production, and continuously delivering more clean energy to South China.
Source: Hainan Daily