Study On Technologies Of Installation And In-site For Subsea Jumper

With the exploration and development of oil and gas resources gradually moving from shallow seas to deep seas or even ultra-deep seas,the demand for underwater production systems is growing rapidly.The subsea jumper,as a relatively common structure of underwater engineering production systems in marine engineering,is the main equipment connecting the pipeline terminal and the bottom of the mixed riser.Deep-water jumper has complex structure characteristics,and is unavoidably subjected to certain environmental loads during installation and on-site operation.Its safety issues will directly affect the safe and reliable operation of the entire underwater production system.In this paper,the issues of subsea jumper installation,in-situ strength and vortex-induced vibration are analyzed.In the installation analysis,taking into account the joint action of the installation ship’s movement and environmental loads,a non-linear time-domain analysis software Orcaflex was used to establish a deep-water rigid subsea jumper installation analysis model,and the entire installation process was subjected to mechanical analysis,and the strength of the subsea jumper and the minimum requirements for crane lifting capacity during installation was verified.The finite element analysis software Abaqus was used to establish the analysis model of the deep-water jumper structure,focusing on the impact of the displacement,temperature load,and corrosion defects(corrosion length,width,and depth)on the strength of the subsea jumper under the specific seabed static load.The velocity and pressure fields of the subsea jumper at four different flow rates were analyzed with Fluent software.Combined with the natural vibration frequency of the modal analysis,it was analyzed whether the subsea jumper would resonate under disturbed flow condition,using the principle of fluid mechanics.A vortex-induced vibration suppression device for a subsea jumper was designed and the suppression effect of the suppression device was analyzed.The analysis results show that the maximum stress response of the subsea jumper during the installation process occurs at the middle of the subsea jumper and the sling is connected.The lifting and lowering speed and the wave angle of the winch play a key role in the stress response of the subsea jumper and the traction force of the crane.The end displacement load has a significant influence on the strength of the subsea jumper structure,especially high stress concentration at the bend pipe.In contrast,the axial displacement load makes it easier for the subsea jumper to reach the ultimate strength state.The thermal stress caused by the temperature load increases with the increase of the internal temperature of the subsea jumper.When the temperature load is large,the subsea jumper reaches the limit state.The depth of the corrosion defect largely affects the ultimate strength of the jumper;when the corrosion depth is large,the jumper approaches the limit state as the corrosion width or the corrosion length increases.The vortex-induced vibration occurs in the subsea jumper under disturbed flow condition,and the lift coefficient and the amplitude of the rear jumper of the additional suppression device is significantly reduced.The vortex-induced vibration suppression device of the designed subsea jumper has a significant suppression effect.