Research on the erosion law of shale gas casing perforation hole during fracturing

Abstract

During the fracturing process of shale gas wells, the high-speed injection of sand-carrying fluid throttles at the perforation casing hole, resulting in erosion at the hole, increasing the geometric parameters of the orifice and even producing cracks, affecting the fracturing construction effect and safety. Therefore, the flow field, the movement trajectory of particles and the erosion law of the perforated holes under different displacement and pump pressure were analyzed by using numerical simulation software and Euler-Lagrangian particle tracking theory, and the simulation analysis results were verified by the full-size physical erosion test of the perforated orifice of the casing. The analysis results show that with the increase of displacement, the erosion rate of the eyelet continues to increase, and the erosion rate of the eyelet in the direction of the liquid inlet is significantly greater than that of the bottom of the casing, and the degree gradually decreases in all directions. Increasing the fracturing construction displacement not only increases the erosion rate and diffusion area at the borehole, but also increases the erosion rate of the pipe wall near the borehole, which will accelerate the thinning of the wall thickness of the casing and affect the service safety of the perforated section casing.