Numerical simulation and experimental analysis of separate layer fracturing string erosion properties

About hydraulic separate layer fracturing technology, due to its large operational discharge capacity and sand carrying ability, and long downhole working time of the string tools, the components of the fracturing string tools erode seriously.In order to research on the erosion rules of the downhole fracturing tools, three types of erodible structures of the downhole fracturing components were analyzed pertinently, including axial bond structure, radially holed structure and variable diameter structure.By adopting CFX flow field analog simulation software, the flow field distribution of sand-carrying fluid in the erodible structure position was studied and the erosion wear rule of sand-carrying fluid to the erodible structure was summarized.Moreover, the finite element calculation results were verified by the experiment of the downhole erodible components.The research shows that the bond sharp erosion rate changes with the shapes of the axial bond sharps in a descendant order as the following: bond sharp angle 60°, 90°, 45°, 180°(round bond sharp)and 30°, and the erosion rate of the bond sharps is obviously higher than that of the bond tail; square sand-out holes have stronger antierosion ability than round sand-out holes; the smaller the variable diameter ratio of the reducing diameter structure is, the more obvious the erosion effect is; the erosion effect of expanding diameter structure can be neglected; the maximum relative error between laboratory experimental results and finite element calculation results is 10.9%, which indicates the accuracy of the numerical simulation results.The research results provide the theoretical and operational basis for the separate layer fracturing tool structure and string combination design.