Erosion Wear Effect Analysis And Structure Improvement Study Of High Pressure Elbow

In hydraulic fracturing operations,fluids are used to bring proppant into the formation to support fractures.Due to the harsh working environment of hydraulic fracturing,the arrangement and installation of high-pressure manifolds are complex and diverse on the ground,and there are also circuitous and transitional structures.The high-pressure working environment and the conveying liquid composition with solid particles,which will lead to the common erosion wear condition of the high-pressure manifold elbow.The average life of elbow is much lower than that of other hydraulic fracturing members.Thus,the reliability and practicality of all fracturing units are limited.Therefore,it is of great significance to improve the reliability and life of the high-pressure manifold by studying the erosion wear of elbow,its influencing factors,and proposing improvement measures.First of all,according to the investigation,erosion wear is the main reason of elbow failure.The wear theory used by scholars is analyzed and summarized.The scope and application of the conditions considered by each theory are expounded.Various factors affecting of erosion wear are discussed.Secondly,based on the established numerical model of elbow erosion wear,according to the working conditions,the influence of elbow erosion wear was analyzed by using the numerical analysis software.The velocity streamline result diagram,solid particle trajectory diagram and the erosion wear rate on the pipe wall calculated by Finnie model,DNV model,E/CRC model and fluent model are obtained.Thirdly,different fluid velocity,different fluid viscosity,different mass flow rate and solid particle diameter were studied and analyzed by the control variable method.The following conclusions are drawn: with the increase of fluid velocity,the maximum erosion wear rate of the elbow increases gradually,and the increasing trend becomes steeper.The relationship between fluid velocity and maximum erosion wear rate is exponential.The influence of fluid viscosity on the maximum erosion wear rate of elbow has a sudden value.Before the fluid viscosity is 0.014Pa?s,with the increase of fluid viscosity,the maximum erosion wear rate on the inside wall of the elbow is gradually reduced and then gradually increased.When the fluid viscosity is 0.014Pa?s,the maximum erosion wear rate of the elbow wall will suddenly drop sharply.Then with the increase of fluid viscosity,the maximum erosion wear rate on the inside wall of the elbow begins increasing or decrease in a small extent.Therefore,it is recommended to use fracturing fluid with a viscosity greater than 0.014Pa?s to reduce erosion wear on the elbow.The maximum erosion wear rate of the elbow wall will increase according to the increase of mass flow rate,and the rate of increase will gradually increase.Therefore,in order to reduce the maximum erosion wear rate,the mass flow rate should be reduced.The maximum erosion wear rate of the elbow wall will increase according to the increase of the diameter of solid particles.Therefore,solid particles with smaller diameters should be selected.Finally in order to increase the service life of elbow.The maximum equivalent stress of the elbow can be reduced by changing the wall thickness of the elbow and the erosion wear of the elbow can be reduced by selecting the appropriate bending diameter ratio.Based on the theory of fracture mechanics,the total fatigue life,initiation life and propagation life of elbow and the crack evolution mechanism were studied.