Experimental Study Of Horizontal Elbow Erosion In Slug Flow

With the development of oil and gas resources,the erosion wear problem of oil and gas field development and pipeline transportation is becoming more and more serious.Elbow is the weak link of erosion due to its special structure,and the research of elbow erosion in multiphase flow is limited,so to conduct the thorough study of elbow erosion in multiphase flow is of great significanceIn this paper,with the erosion experiment loop system,using theoretical analysis,and experimental testing method to study 900 elbow erosion behavior under the condition of different variables in slug flow.By the flow state observation and simulation calculation results,weight-loss method,sample morphology analysis method,the flow regime of slug flow in horizontal straight and bend pipe was studied,the erosion rate and change trend of each location under different working conditions was quantified,the most severe wear position was determined,the micro-erosion mechanism of different elbow parts was analysed,the influence of different variables on elbow erosion behavior was summarizedThe flow regime of slug flow in horizontal straight and bend pipe was studied.The results showed that most of the solid particles were distributed in the liquid film area.In the straight pipe section,the sands of the liquid film area were mainly concentrated in the bottom of the pipe,and the rests was attached to the pipe wall.At the entrance of elbow,liquid and particles mainly gathered in the bottom,gradually moved to elbow lateral and then to the pipe roof,finally covered the entire inner wall,the sloping wave was performed by slug body after middle section,which bring strong impact to lateral central part of elbowThe erosion behavior of 900 bend in slug flow was studied,the results showed that the lateral erosion rate is much bigger than inside,with obvious local severe erosion characteristics,and the most serious erosion position was located in central section of the lateral one times the elbow diameter from export.The surface morphology mainly consisted of scratches caused by particles with a certain velocity in minor impact angle,erosion pits formed during the impact of particles in large attack angle,and the attenuation caused by micro-cutting.The changes of erosion behavior by different gas and liquid velocity were researched,the results showed that the most serious wear place was unaffected in diverse gas or liquid flow rate,which also does not affect the erosion rate variation tendency,the damage caused by increasing gas velocity was much worse than liquid.With the increase of the velocity of the gas liquid phase,the lateral erosion rate of the horizontal elbow saw a sharp increase and the increase extent rises,the erosion pits depth and abrasion loss also increased dramatically.It is indicated that the increase of gas or liquid velocity will greatly aggravate the erosion damage degree of the bent tube.Inversely,the erosion rate of 45°axial section inside wall is slightly reducedThe effects of particle size and the sand concentration were studied,the results indicated that the most serious wear position of horizontal bend was unaffected under different sand size and content.With the increase of particle size,the erosion rate of different parts increased firstly and then decreased,the thinning amount reduced and then increased,the scratches depth increased and the number of erosion pit reduces while the pit depth increased significantly;The erosion rate of lateral elbow increases with the increase of sand content,but the increase extent reduces,and the number of erosion pits added and then the change become mild.