Effect Of Erosion Wear On Fatigue Life Of High Pressure Pipe Manifold

In unconventional oil and gas production operations,the service life of high-pressure manifolds and other consumables severely limits the reliability of the entire fracturing unit.In order to meet the requirements for ultra-high-power fracturing equipment for deep shale gas development,the high-pressure manifold sink life needs to be further studied to increase its service life,extend its service life,and ensure its operational safety.In this dissertation,the high-pressure right-angle elbow is studied,and systematic researches are carried out from the aspects of failure reason,erosion wear,erosion defect,inner wall stress and manifold fatigue life.First of all,according to the field failure samples and relevant domestic and foreign references,this paper concludes that the main failure mode of high-pressure manifolds is bursting and spalling of manifolds,and the main cause of failure is erosion wear.Secondly,combined with the erosion wear theory,the main factors affecting the erosion of the high-pressure manifold are simulated and the influence of various factors on the erosion of the manifold is obtained.Then,based on erosion simulation results and on-site samples,the typical types of erosion defects are summarized and represented by one of the most common erosion defects.Erosion defects are obtained by data analysis and equation fitting of erosion simulation results.Pit location and structural parameters.According to the relevant parameters,a new model of the elbow with erosion defect is established,and finite element analysis is performed to obtain the force condition of the inner wall of the manifold.Finally,fatigue life analysis software is used to estimate the remaining life of manifolds by combining manifold stress conditions,material characteristics,and manifold load spectra.Through erosion simulation analysis,the erosive wear rules of high pressure manifolds in the fracturing process,such as flow velocity,viscosity,mass flow rate,particle size,and bend ratio,are obtained.The increase in flow velocity and mass flow rate will cause erosion.The increase in the rate,and there is no upper limit,so the two types of factors should be limited to a certain extent.However,the viscosity,particle diameter and radius ratio have a critical value influencing the erosion rate.In the fracturing operation,relevant parameters should be reasonably selected to minimize the erosion rate.Through analysis and conclusion,it is determined that the largest cross-section of the eroded pit studied in this paper is a parabola type,and the crater is located in the central symmetry plane of the elbow through the central angle of the maximum erosion rate and the central parallel cross section.The elbow is in the range of 60°-70°.Inside.Through the finite element analysis,the maximum stress concentration point of the non-defective elbow is the inner arc wall surface,and the maximum stress concentration point of the elbow with the erosion defect is the erosion pit.By analyzing the fatigue life of the two sets of manifolds with or without defects,itis found that the position of the manifold susceptible to fatigue failure is located on the inner arc wall of the elbow,but after pit defects,the pit is the most dangerous part and its service life is far.Below the design life of the high-pressure manifold.