Mechanical Analysis And Risk Assessment Of Injection Production String In Gas Storage

At present,natural gas usage is increasing year by year,and the construction of gas storage is also ushering in a period of rapid development.As a key part to communicate between surface facilities and underground facilities,gas storage pipe strings are receiving more and more attention.Generally,the gas storage pipe string is thousands of meters long,and the force is complicated and difficult to replace.When damaged,it is easy to cause very serious accidents and endanger the lives of people.Therefore,the mechanical analysis and risk assessment is on environmental conditions for gas storage column.First,through the gas storage accident investigation,summarize the types of accidents,and conduct further research on the string failure accidents with the highest proportion.By studying the load and failure mode of the pipe string,the risk factors are summarized,and the failure risk factors of the gas storage pipe string are divided into 4 modules,8 categories and 24 sub-factors.Secondly,establish the gas storage string dynamics model and compile the calculation module,based on the field feedback working condition data,calculate the stress value of the string at each well depth,each gas injection volume,and each injection pressure from a theoretical perspective;with the help of ANSYS Workbench,the transient dynamics analysis of the pipe string is carried out to study the mechanical influence of the bending section angle,the radius of curvature of the bending section and the alternating load on the pipe string.Furthermore,the fatigue life of the gas storage pipe string is studied,combined with the stress output results of the dynamic calculation module,the fatigue life of the pipe string is calculated,and the influence of daily gas injection volume,injection pressure,crack size,etc.on the fatigue life of the pipe string is studied.Based on the simulation results of the development of surface cracks,detection and monitoring measures are proposed for different types of cracks,and energy and resources are allocated reasonably to ensure the safe operation of the pipe string.Finally,based on the risk factors of pipe string failure,the fault tree model and fuzzy analytic hierarchy process risk assessment are carried out,and preventive measures are proposed for key factors to ensure the normal operation of the gas storage;formulate the fuzzy analytic hierarchy process weight calculation module to simplify the calculation steps and facilitate field application.