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Offshore Oil Engineering Master The Installation Technology of Kilometers-deep Underwater Suction Piles

Date:2020-09-03

Recently, news came from the site of Lingshui 17-2 gas field development project that the company has independently completed the underwater installation of three kilometers-deep suction piles, which marks the first time that Offshore Oil Engineering has mastered the installation technology of kilometer deep underwater suction piles.

The installation depths of the three suction piles are more than one kilometer, of which 1486m is the deepest depth installed independently by Offshore Oil Engineering. The suction pile is large in size, high in lifting requirements and heavy in quality. It is the largest deep-water suction pile installed in China so far, which has higher requirements on installation design, field operation and equipment performance.

In the early stage, the project group of the company spent three months to carefully design and formulate three sets of emergency plans, and organize personnel to conduct key step tests on land. In the process of offshore construction, the barge transporting suction piles needs to berth to the main working vessel, and the minimum distance between the two vessels is less than 3 meters. In order to ensure the safety of berthing offshore, the project group held risk analysis meetings for many times, communicated with the ship owner repeatedly, discussed the safest berthing scheme, and finally realized the safe berthing and hoisting. At the same time, according to the change of sea conditions, the project group also timely optimized the construction procedures and adjusted the scheme, so that the installation time of each suction pile was saved by 5 hours compared with the plan, which greatly improved the construction efficiency and economic benefits.

Suction pile is a kind of steel bucket structure with closed upper end and open bottom, which is used to fix large seabed structures. In the process of installation, it is first lowered to the seafloor by using its own weight, and then pumped out water through the upper hole to reduce the water pressure inside the bucket and make it slowly enter into the seabed. When the suction pile is used up, it can be recycled by injecting water into the bucket, so it has high economic value. In addition, compared with the traditional gravity pile, anchor pile, chain pile and so on, the suction pile has small self weight, is easy to build, install and transport, and is suitable for soft soil in deep water, so it is widely used in marine engineering.

The company continues to breakthrough in deep-water suction pile installation capacity, which provides important technical support for the subsequent ultra-deep water suction pile installation of Lingshui 17-2 project, and also lays a solid foundation for the operation of the project.

Figure: Suction pile launching