Analysis method of deepwater jack tension riser bending vibration

Abstract

The invention relates to research methods of sea deepwater risers, and specifically relates to an analysis method of deepwater jack tension riser bending vibration. According to the method, an influence of cross section rotation due to a large-scale displacement on riser bending rigidity is considered. Tension force direction variation caused by cross section rotation is converted into part of the riser bending rigidity. The method is more complete than geometric stiffness provided by prior methods, and accords with actual bearing and deforming statuses of deepwater risers. Also, the method takes the influence of shearing deformation on the riser bending rigidity into consideration. A ratio of the tension force to shearing rigidity is introduced into the bending rigidity. Unreasonable assumptions in prior methods are rectified, and the analysis of the deepwater jack tension riser bending vibration is more practical.

Description

technical field [0001] The invention relates to a research method for marine deep-water risers, in particular to a bending vibration analysis method for deep-water top-tensioned risers. Background technique [0002] Deepwater top tension riser is a main type of deepwater marine riser. The lower end of the riser is connected to the wellhead on the seabed. The tension of the pipe wall directly acts on the wellhead, and the fluid in the pipe continuously flows from the seabed through the riser to the floating platform. . Bending vibration is the main vibration form of deepwater top-tensioned risers under marine environmental loads, and it is also the main factor causing fatigue damage of risers. Therefore, the bending vibration response analysis is an important content in the design of deep water top tension risers, and it is also the basis of fatigue analysis. Currently, the bending vibration analysis method for deepwater risers is based on the pure bending theory of Eular-B...

AI Technical Summary

Problems solved by technology

[0018] 1. The influence of the cross-section rotation caused by the large displacement of the bending vibration of the deep-water top-tensioned riser on the bending stiffness is not considered

[0019] The existing technology is based on pure bending theory and small deformation assumptions, therefore, only the geometric stiffness part of the tension is considered, and the influence of the change in the direction of tension action due to the rotation of the section on the bending stiffness of the riser is not considered

[0020] 2. The influence of shear deformation on the bending vibration of deepwater risers is not considered

However, the standpipe is a tubular structure, and the shear stiffness of its section is small, so its shear deformation has a greater impact, especially the ratio of tension to section shear stiffness is large, which has a greater impact on the bending stiffness

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