Analysis Of Erosion Characteristics Of Coiled Tubing Considering Multi-attribute Coupling

Coiled tubing hydraulic jet fracturing technology is widely used in the stimulation of oil and gas wells.However,in the process of hydraulic jet fracturing,high-speed sand-carrying fracturing fluid will cause erosion of the coiled tubing.The erosion of the coiled tubing section winding on the drum of coiled tubing operation equipment is the most serious.Severe erosion and abrasion may cause puncture,leakage and fracture of the coiled tubing.Therefore,it is necessary to study the erosion characteristics of the coiled tubing section in the hydraulic jet fracturing process.Applying with UG software and ANSYS WORKBENCH software’s MESH and FLUENT sub-modules,based on computational fluid dynamics and erosion wear theory,selected discrete phase model and combined with hydraulic jet fracturing process parameters,and taking 2.375 " coiled tubing as an example,the finite element calculation and analysis method of the erosion wear characteristics of coiled tubing was studied and the maximum erosion wear rate and distribution cloud map of it were obtained.With this method the erosion and abrasion characteristics of 2.375",2.875 " and 3.5" coiled tubings are respectively analyzed on the condition of various sand-carrying fracturing liquid properties and drum parameters.The effects of multi-attribute parameters coupling of the sand-carrying fluid on the erosion characteristics of the three coiled tubings are analyzed by using the DESIGN EXPLORATION sub-module of ANSYS WORKBENCH software based on the erosion wear characteristics analysis method of coiled tubing for the single attribute parameters,which takes the sand-carrying liquid flow rate,the sand-carrying particle diameter and the sand-carrying particle mass flow as the optimal parameters and the minimum erosion wear rate as the optimal goal according to the optimization design theory and the sequential quadratic programming algorithm.Thus the three-parameter optimal configuration values and contour maps of erosion wear rate are gained for the three coiled tubings.The research results can gain certain conclusions.The outer sides of the coiled tubing wound on the drum is more severely eroded.Increasing the sand-carrying liquid flow rate and the sand-carrying particle mass flow will lead to the increasment of the maximum erosion and abrasion rate of the coiled tubing.Increasing the sand-carrying particle diameter and sand particle shape factor,drum diameter and coiled tubing size can reduce the maximum erosion wear rate of coiled tubing.The optimal configuration values of the three attribute parameters of sand-carrying particle diameter,sand-carrying particle mass flow and sand-carrying liquid flow rate of different specifications of coiled tubing are different.For 2.375" coiled tubing,the optimal configuration values are 0.45 mm and 0.25kg/s,25m/s.For 2.875" coiled tubing,the optimal configuration values are 0.15 mm,0.45kg/s,10m/s.For 3.5" coiled tubing,the optimal configuration values are 0.55 mm,0.55kg/s,18m/s.The optimal values of sand-carrying particle mass flow and sand-carrying particle diameter are more affected by tubing specifications,and the optimal value of sand-carrying fluid flow rate is less affected by the coiled tubing.The research results of the thesis provide a theoretical reference for the parameter configuration of the sand-carrying liquid properties of the coiled tubing hydraulic jet fracturing operation,the selection of coiled tubing specifications and the size of the drum,and have great engineering application value.