A restraining device for heaving motion of semi-submersible platform

Abstract

A device for suppressing the heaving motion of a semi-submersible platform, comprising an upper platform structure, a lower floating body is connected to the lower part of the upper platform structure through a column, and the feature is that the column is equipped with a device that lowers the platform by changing the surrounding flow field. A heave suppression mechanism that produces a heave motion. A heave suppression mechanism of the present invention, the heave suppression mechanism is an extendable annular heave plate and an electric rope winch arranged on a column and forming a certain angle with the column, and the electric rope winch is provided with a steel wire rope and a Extended ring heave plate connection. It has an active control function. By adjusting the vibration frequency of the mass body, its vibration frequency is always kept near the frequency of the semi-submersible platform structure to achieve better vibration suppression.

Description

technical field [0001] The invention relates to a control device for suppressing heave motion of a semi-submersible platform, belonging to the technical field of marine technical equipment. Background technique [0002] As offshore oil development continues to move towards deep water, semi-submersible platforms have become the main platform type for offshore oil and gas development due to their advantages such as good maneuverability, large working water depth, and strong adaptability to harsh sea conditions. Its main structure includes platform body, column and lower body (or buoyancy tank), is provided with support member between platform and column and increases overall rigidity. The inherent vibration period of its structure is relatively large, and the movement period in all directions is also relatively large. The period of roll and pitch is about 30-60 seconds, and the period of surge, sway and yaw is generally greater than 100 seconds, which can effectively prevent t...

AI Technical Summary

Problems solved by technology

However, due to the shallow draft, the response of the heave motion of the semi-submersible platform is large, and the fatigue damage to the riser is relatively large. At the same time, the natural period of the heave response motion is close to the energy period of the wave, so the response of the heave motion is lower than that of other degrees of freedom. Resonance is more likely to occur under normal sea conditions, which puts forward higher requirements for the selection of production platform riser and Christmas tree system, drilling platform heave compensation device, etc., which increases the operation and maintenance costs

[0003] At present, there are not many achievements in the application of heave control technology and devices for semi-submersible platforms. Some researchers have explored the use of fixed heave plates to suppress the heave motion. The adaptability is poor, and the added additional mass is small, and the suppression effect is limited

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