Coupling Analysis Of Pipe Laying Process Of Deepwater S-lay Vessel

Deep sea contains abundant resources,in which oil and gas,as the lifeblood of national economic development and national security,play an important role in the development of marine resources.As a bridge connecting offshore oil and gas with onshore terminal,the laying mode of submarine pipeline has undergone a change from shallow water towed laying to deep water professional engineering ship laying.At present,S-lay is one of the main laying methods.However,due to the complex working environment in deep sea,the coupling effect of pipeline and hull during laying and the interaction between systems,the operation risk is high.This article takes the deep-water S-lay vessel as the research object,and systematically analyzes the pipe-laying operation.The research is carried out around the structural safety of stinger laying,the joint hydrodynamic response of pipe-laying vessel and stinger and the coupling problem of pipe-laying operation.The structural strength of stinger,the influence of stinger on the amplitude of ship motion,and the influence of hull natural period on stinger are analyzed,and the factors affecting the safety of pipe-laying operation are discussed.In order to verify that the stinger can meet the design requirements under extreme laying conditions,a static and dynamic analysis was conducted on the stinger under a 6-inch pipeline laid in 3000 m deep water.The structural strength was checked by the ratio of the maximum stress value to the allowable stress value(UC value)of the rod,and the difference between dynamic analysis and static analysis was compared.The rod at a dangerous position prone to mechanical failure during laying operations was obtained.The hydrodynamic performance analysis of the pipe laying vessel and stinger combination was conducted.During the pipeline laying process,the stinger suspended at the stern of the ship moves with the pipe laying vessel under the action of waves and currents,which is bound to have a certain impact on the hydrodynamic performance of the pipe laying vessel.Taking the pipe laying ship and stinger assembly as the research object,a numerical model was established to analyze the impact of installing stingers on the motion of the pipe laying ship,and the impact of the combined motion of the ship and stinger on the mechanical behavior of the stinger was analyzed.It was found that installing stingers would significantly change the dynamic performance of the ship.When analyzing the overall mechanical behavior of the stinger,the combined motion of the ship and stinger should be considered.Considering the interaction between the laying vessel,stinger,and pipeline during S-lay operations,a numerical analysis model of the laying vessel stinger pipeline was established using finite element method,and dynamic positioning control was added to conduct timedomain coupling analysis of pipeline laying.Obtain the dynamic positioning performance of the hull during the laying operation at a depth of 1600 m,the response of the support forces of each supporting roller,and the internal force along the length direction of the pipeline.By comparing the bending stress estimation formula with the upper bending section of the pipeline,it was found that the established overall numerical model of pipeline laying can effectively simulate the S-lay system,and there is a coupling dynamic amplification situation in the system during deep water laying.Finally,the impact of factors such as laying depth,pipeline diameter,meaningful wave height,tensioner tension,and environmental load direction on the dynamic characteristics of pipeline laying was analyzed,and the internal force response and variation law of the pipeline under different conditions of pipeline laying operation were explored and summarized,providing reference for numerical simulation research of related pipeline laying operations.