Device for restraining vortex-induced vibration of marine riser for offshore drilling and preparation method of device

Abstract

The invention discloses a device for restraining the vortex-induced vibration of a marine riser for offshore drilling. The device comprises a plurality of rotary covers, and each rotary cover is divided into an inner ring and an outer ring, wherein grooves are formed in the outer sides of the inner rings and the inner sides of the outer rings, rolling balls are arranged in the grooves, the inner rings of the rotary covers sleeve the outer side of a marine riser body side by side, and the outer side of each outer ring is provided with 2-4 groups of flow guide blocks. Each group of flow guide blocks spreads in the circumferential direction to form a transverse continuous shape like the Arabic numeral eight, and gaps are formed between the upper group of flow guide blocks and the lower groupof flow guide blocks. By using the bearing type inner and outer ring structures, a buffer layer is arranged in the device, during work, the outer rings rotate but the inner rings keep fixed, and the two functions of restraining the vortex-induced vibration and anti-collision protection are achieved. When the device encounters with ocean current, through drainage of the gaps g and the radian of theouter rings and rotation of the outer rings, vortex release is reduced, the transverse vibration is restrained, and the vortex-induced vibration can be comprehensively restrained, the device is convenient to use, reliable in performance, low in cost, difficult to corrode and long in service life.

Description

technical field [0001] The invention belongs to the technical field of risers, and in particular relates to a device for suppressing vortex-induced vibration of a marine drilling riser and a preparation method thereof. Background technique [0002] The offshore riser is the casing that the offshore drilling platform goes down to the shallow seabed. It is mainly used to isolate seawater, guide drilling tools and casings, and form a channel for mud circulation; at the same time, it serves as a supporting structure for offshore wellheads. The integrity of the riser is critical to the safety of offshore operations. The riser is continuously subjected to compound loads such as waves and currents in the ocean. When the sea current bypasses the riser, pressure difference resistance is formed before and after the riser, and a drag force is formed on its cylindrical surface, thereby causing the riser to vibrate longitudinally; In addition, vortices alternately shed on both sides beh...

AI Technical Summary

Problems solved by technology

The riser is continuously subjected to compound loads such as waves and currents in the ocean. When the sea current bypasses the riser, pressure difference resistance is formed before and after the riser, and a drag force is formed on its cylindrical surface, thereby causing the riser to vibrate longitudinally; In addition, vortices alternately shed on both sides behind the riser, causing the lift force perpendicular to the flow direction to be additionally applied to the riser, and the alternate change of the lift direction causes the riser to vibrate laterally, and this vibration is more severe; when When the vortex shedding frequency is close to a certain natural frequency of the riser vibration, the vibration of the structure will force the vortex shedding frequency to be fixed at a certain natural frequency of the cylinder within a large flow velocity range, and a locking phenomenon occurs, that is, resonance, which causes the riser to fatigue failure

Once the riser fatigue damage occurs, it will not only cause major safety accidents at sea, cause huge economic losses, but also cause catastrophic damage to the marine environment

[0003] The existing riser vortex-induced vibration suppression device has the disadvantages of high cost, complicated manufacturing process, heavy weight, cumbersome installation and inconvenient on-site operation, etc., which needs to be improved

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