Research On Dynamic Response And Reliability Of Subsea Manifold Main Structure Under Impact Load

In recent years,the technology of offshore drilling and oil and gas production has been developing rapidly.The subsea production system has become the key technology for the deep-sea petroleum industry.In this paper,the main research object is the core components of the subsea production system,which is the main structure of the manifold.The work load and the allowable stress check,the static analysis of the main structure,the dynamic response of the manifold with the impact load,the reliability analysis based on the random finite element,the sensitivity analysis of the random variable,the reliability analysis of main structures subjected to impact damage and impact damage are studied in detail.The main contents and conclusions of this paper can be summarized as follows:(1)The problems and advantages of each component in manifold are briefly analyzed.Taking the actual data of a certain oil and gas field in the South China Sea as design parameters,the main structure of the two-header and two-well manifold is designed according to the specifications.The finite element model of the main structure is established,and the static analysis of towing,hoisting and under three working conditions is carried out.(2)The two-header and two-well manifold is taken as the research object.Based on the bilinear follow-up intensified model,the impact finite element analysis model of the manifold is established,and the pipe line and the main structure are taken as a whole to analyze the dynamic response process of the ship anchor falling impact.Based on the LS-DYNA solver,the dynamic response of the subsurface manifold with different thickness of the protective plate and the impact angle was analyzed,and the impact of falling objects on the main structure and pipeline was studied.(3)Stochastic finite element method is used to study the reliability of the main structure.Based on the Monte Carlo method of Latin hypercube sampling,the calculation of different random variables is carried out to study the reliability of the main structure in different working conditions,and the sensitivity analysis of the parameters of each random variable is carried out.The main structure is optimized under the premise of reliability.(4)Based on the initiation criterion of X-W ductility damage,the softening path of the material stress is determined.The stress limit state function and the displacement limit state function of the impact component under the uniform distribution of the ocean current load(working condition one)and the ocean current load under normal distribution(working condition two)are calculated.Finally,based on the reliability calculation results of the main structure with impact damage,the sensitivity of the stress limit state function under the working condition and the working condition two is analyzed.