Is composed of platform structure, pile legs and lifting mechanism. The main hull part of the jack-up drilling platform is a watertight structure, which is used to carry machinery and realize the function of drilling and oil production. When it floats on the sea, the buoyancy generated by the main hull is used to balance the gravity of the legs, machinery, and structure.
Jack-up drilling platform includes many common structures. The biggest difference lies in the leg structure, lifting system, and load transfer system between the leg and the hull.
Cushioned pile boots
The cushion type fixes all the legs of the jack-up drilling platform on a pile foundation system. The sunken pile structure has two main advantages: First, the area is larger, so the axial pressure on it is smaller than that of the pile shoe structure, which is particularly important when the soil cannot withstand large axial pressure. Second, in the floating towing mode, the sunken pile foundation provides greater buoyancy, which correspondingly increases the loading capacity of the drilling platform.
The main disadvantage of cushion pile structure is that it is not suitable for uneven seabeds or large slopes.
The number of pile shoes for pile foundation structure with independent pile shoes is the same as the number of pile legs. The biggest advantage of the pile shoe type pile foundation structure is that it can adapt to different seabed terrain. In addition, there is no strict sequence requirement for the ballast of pile shoes.
At present, the mainstream jack-up platform mostly adopts the pile shoe pile foundation system, which avoids the impact of the long insertion of the pile leg in the soft soil area, and also improves the safety during pile insertion and extraction operations. The bottom of the pile shoe will be made into a protruding transition shape, like a small cone-shaped head, which facilitates the function of entering the mud. The pile shoe generally has its own piling system.
All jack-up drilling platforms have leg structures. The function of the leg structure is to ensure that the hull rises from the water to a certain height without having to bear the wave load. There are two main types of leg structures: cylindrical and truss.
Cylindrical leg is suitable for operating water depth less than 300 feet, when the water depth is greater than 300 feet, truss leg structure is usually used.
The advantage of the large cylindrical leg structure is that it is smaller in size and occupies less deck area, so the construction process is relatively simple. The truss leg structure is composed of chords and bracing tubes.
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