Deformable gel particles (DGPs) possess the capability of deep profile control and flooding. However, the deep migration behavior and plugging mechanism along their path remain unclear. Breakage, an inevitable phenomenon during particle migration, significantly impacts the deep plugging effect. Due to the complexity of the process, few studies have been conducted on this subject. In this paper, we conducted DGP flow experiments using a physical model of a multi-point sandpack under various injection rates and particle sizes. Particle size and concentration tests were performed at each measurement point to investigate the transportation behavior of particles in the deep part of the reservoir. The residual resistance coefficient and concentration changes along the porous media were combined to analyze the plugging performance of DGPs. Furthermore, the particle breakage along their path was revealed by analyzing the changes in particle size along the way. A mathematical model of breakage and concentration changes along the path was established. The results showed that the passage after breakage is a significant migration behavior of particles in porous media. The particles were reduced to less than half of their initial size at the front of the porous media. Breakage is an essential reason for the continuous decreases in particle concentration, size, and residual resistance coefficient. However, the particles can remain in porous media after breakage and play a significant role in deep plugging. Higher injection rates or larger particle sizes resulted in faster breakage along the injection direction, higher degrees of breakage, and faster decreases in residual resistance coefficient along the path. These conditions also led to a weaker deep plugging ability. Smaller particles were more evenly retained along the path, but more particles flowed out of the porous media, resulting in a poor deep plugging effect. The particle size is a function of particle size before injection, transport distance, and different injection parameters (injection rate or the diameter ratio of DGP to throat). Likewise, the particle concentration is a function of initial concentration, transport distance, and different injection parameters. These models can be utilized to optimize particle injection parameters, thereby achieving the goal of fine-tuning oil displacement.

"Carbon peaking and carbon neutrality" is an essential national strategy, and the geological storage and utilization of CO₂ is a hot issue today. However, due to the scarcity of pure CO₂ gas sources in China and the high cost of CO₂ capture, CO₂-rich industrial waste gas (CO₂-rich IWG) is gradually emerging into the public's gaze. CO₂ has good adsorption properties on shale surfaces, but acidic gases can react with shale, so the mechanism of the CO₂-rich IWG–water–shale reaction and the change in reservoir properties will determine the stability of geological storage. Therefore, based on the mineral composition of the Longmaxi Formation shale, this study constructs a thermodynamic equilibrium model of water–rock reactions and simulates the regularity of reactions between CO₂-rich IWG and shale minerals. The results indicate that CO₂ consumed 12% after reaction, and impurity gases in the CO₂-rich IWG can be dissolved entirely, thus demonstrating the feasibility of treating IWG through water–rock reactions. Since IWG inhibits the dissolution of CO₂, the optimal composition of CO₂-rich IWG is 95% CO₂ and 5% IWG when CO₂ geological storage is the main goal. In contrast, when the main goal is the geological storage of total CO₂-rich IWG or impurity gas, the optimal CO₂-rich IWG composition is 50% CO₂ and 50% IWG. In the CO₂-rich IWG–water–shale reaction, temperature has less influence on the water–rock reaction, while pressure is the most important parameter. SO₂ has the greatest impact on water–rock reaction in gas. For minerals, clay minerals such as illite and montmorillonite had a significant effect on water–rock reaction. The overall reaction is dominated by precipitation and the volume of the rock skeleton has increased by 0.74 cm³, resulting in a decrease in shale porosity, which enhances the stability of CO₂ geological storage to some extent. During the reaction between CO₂-rich IWG–water–shale at simulated temperatures and pressures, precipitation is the main reaction, and shale porosity decreases. However, as the reservoir water content increases, the reaction will first dissolve and then precipitate before dissolving again. When the water content is less than 0.0005 kg or greater than 0.4 kg, it will lead to an increase in reservoir porosity, which ultimately reduces the long-term geological storage stability of CO₂-rich IWG.