On May 13, 2023, in the eastern part of the South China Sea, the Enping 20.4 drilling and production platform with a weight of more than 15,000 tons was installed. It fills the gap in China's dynamic positioning floatover independent design and installation technology, and is of great significance to safeguarding national security and building a powerful ocean country.

The Enping 20-4 platform, the largest dynamic positioning floating platform in China, is entering the ship

According to Liu Huaxiang, general manager of the Deepwater Engineering Construction Center of CNOOC Shenzhen Branch, the Enping 20.4 platform is independently designed, built and installed by China, which can realize drilling and workover, intelligent oil production, comprehensive treatment of oil, gas and water, and recovery and utilization of associated gas. Multiple functions. The platform consists of two parts, the upper block and the jacket. The single-deck area of the upper block is equivalent to 9 basketball courts and weighs 15,463 tons. The jacket is 104 meters high and weighs nearly 12,000 tons. It has been installed on the seabed nearly 100 meters deep in advance. In order to fix the jacket on the seabed, the project team drove 12 steel piles with a length of nearly 145 meters and a diameter of 2.4 meters into the seabed at a depth of 120 meters to ensure that the combined steel giant with a total weight of more than 27,000 tons can Under the super typhoon, it is as stable as Mount Tai.

China's largest dynamic positioning floating platform upper module and jacket completed docking

Since the weight of the upper part of the platform exceeds the capacity limit of the domestic offshore floating crane, the power floating technology is adopted for offshore installation. Floatover installation skillfully utilizes the natural force of sea tides and the combination of precise load adjustment of the ship to complete the installation in a way similar to that of a weightlifter. Dynamic positioning floatover is a new type of installation technology. Taking the installation of Enping 20.4 platform as an example, this method can double the transportation speed of the platform, and the climate window required for offshore installation operations can be shortened from 48 hours to 24 hours. The efficiency is greatly improved, and the construction speed of offshore oil fields is accelerated.

The moment when the upper part of the platform is docked with the jacket

It is understood that the dynamic positioning floatover installation process is equivalent to driving a super truck with a length of more than 220 meters, a width of more than 40 meters, and a load of 10,000 cars. It is reversed into the warehouse on rough seas, and the gap between the two sides is only 10 cm. , The accuracy of the docking of the block insert tip and the catheter is required to reach the millimeter level, which poses great challenges to the accuracy of design calculations, the reliability of the dynamic positioning system, and the technical level of operators.

According to Sheng Xiangming, general contracting project manager of COOEC Enping Oilfield Group Development, the project team independently conducted technical research and successfully broke through many key technologies such as dynamic positioning floatover design analysis and calculation, 3D simulation, and precise positioning operation, and carried out a large number of virtual projects. Model training and key operation rehearsal, fully identify operational risks and formulate countermeasures. In order to ensure nothing goes wrong, the technicians set up two independent positioning systems on the main work vessel Haiyang Shiyou 278 to provide stable and accurate reversing collision avoidance radar for the floatover, and independently designed a new guard string system and pile leg coupling buffer device, In case of damage caused by accidental collision.

Aerial photography of my country's largest dynamic positioning floating platform offshore installation

During the floatover installation, the sea conditions were relatively harsh, which added difficulties to the implementation of the installation work. During the construction process, the project team monitored the wind, waves and ship movement in real time. When the ship was about to enter the jacket slot, the ship control mode was adjusted from automatic to manual mode, and the ship was precisely controlled by experienced dynamic positioning operators. For reversing, the maximum error is only 5 mm, and the precision control has reached the international advanced level.

It is reported that the Enping 20.4 drilling and production platform is the platform with the highest output in the CNOOC Enping 15.1 oilfield group. After the oilfield group is fully put into production, the peak annual crude oil output will exceed 3.6 million tons. Development injected new impetus.Editor/ZhangHui