Particle Migration and Permeability Model during Supercritical CO₂ Injection into Saline Aquifers

Under the background of CCUS, the injection of supercritical CO₂ into saline aquifers is a key technology for achieving long-term geological storage of CO₂. However, prominent problems such as reservoir permeability decline and pore structure evolution occur during the injection process, which is essentially the coupled effect of particle detachment, migration and deposition. At present, there is a lack of systematic research on the dynamic evolution of reservoir physical properties and the damage mechanism under different injection intensities. In this paper, three types of artificial sandstone cores with low, medium and high permeability were used to carry out supercritical CO₂ injection experiments. The influence of flow velocity on reservoir permeability was analyzed, and a hydromechanical coupling mathematical model, including the whole process of particle detachment, migration, and deposition, was established. The experimental results showed that the permeability of the core presented a "first increase and then decrease" trend with the change of injection velocity. The fitting accuracy between the numerical simulation results and the experimental data was higher than 90%, and the model could accurately describe the process of particle migration and pore plugging. The research results can provide a theoretical basis for the optimization of CCUS injection parameters and the prevention of reservoir damage, and also lay a foundation for the safe and efficient geological storage of CO₂.