There are few studies on erosion problems in gas storage environments. High-speed gas-carrying sand in gas storage wells can cause pipeline erosion and subsequent failure. To this end, a numerical model of gas/liquid/solid three-phase erosion under high temperature and high-pressure conditions in gas storage was established. The model combines the laws of conservation of mass, momentum, and energy, as well as the force model of solid particles. Using the established mathematical model of erosion, numerical simulations were performed to study the erosion process of the column under different parameters during gas injection and extraction to find the main factors affecting column erosion. Subsequently, a prediction model was established based on the determined main factors to estimate the maximum erosion rate of the column. The results show that during the extraction process, the maximum erosion rate is exponentially related to the extraction rate, and the erosion intensifies when it is greater than 1 million m³/d. It is linearly related to the particle mass flow rate and the well inclination, and it tends to decrease when the particle size is greater than 3 mm. The erosion law during gas injection is similar to that during extraction, but the erosion during gas injection is more severe. The comprehensive influence of various parameters on the maximum erosion rate was studied by orthogonal experiments, and an erosion prediction model was established by nonlinear regression using the least squares method.

This study addresses the coupled influence of the threshold pressure gradient and stress sensitivity during the seepage process in low-permeability reservoirs. By integrating Laplace transform, perturbation transform, the image principle, and the superposition principle, a non-steady-state seepage model for segmented-fractured horizontal wells considering both effects is established for the first time. The analytical solution of the point source function including the threshold pressure gradient ($\lambda$) and stress sensitivity effect (permeability modulus $\alpha$) is innovatively derived and extended to closed-boundary reservoirs. The model accuracy is verified by CMG numerical simulation (with an error of only 1.02%). Based on this, the seepage process is divided into four stages: I linear flow (pressure derivative slope of 0.5), II fracture radial flow (slope of 0), III dual radial flow (slope of 0.36), and IV pseudo-radial flow (slope of 0). Sensitivity analysis indicates the following: (1) The threshold pressure gradient significantly increases the seepage resistance in the late stage (the pressure curve shows a significant upward curvature when $\lambda$ = 0.1 MPa/m); (2) Stress sensitivity dominates the energy dissipation in the middle and late stages (a closed-boundary-like feature is presented when $\alpha$ > 0.1 MPa⁻¹); (3) The half-length of fractures dominates the early flow (a 100 m fracture reduces the pressure drop by 40% compared to a 20 m fracture). This model resolves the accuracy deficiency of traditional single-effect models and provides theoretical support for the development effect evaluation and well test interpretation of fractured horizontal wells in low-permeability reservoirs.