Simulation study on particle transport and retention of water injection in carbonate rocks

The transport and retention of injected particles in carbonate reservoirs critically affect permeability evolution and oil recovery during waterflooding. Unlike previous studies that relied on homogeneous porous media or simplified particle systems, this work introduces a novel cast-based digital model reconstructed from real carbonate rock thin sections, integrated with a Discrete Element Method–Computational Fluid Dynamics (DEM–CFD) coupled multiphysics simulation approach. This combined approach enables the first quantitative characterization of cooperative particle retention mechanisms in heterogeneous pore networks. Results reveal a nonlinear increase in particle retention from 22.30% at 20 s to 62.88% at 80 s, with progressively slower growth indicating self-regulated flow redistribution induced by pore clogging. Particle migration initiates with rapid transport through dominant flow channels, followed by localized bridging and redistribution into less permeable regions. Eventually, the system stabilizes into a dynamic equilibrium between flow and retention. This study provides new quantitative insights into how particle–pore interactions control permeability evolution in carbonate reservoirs and contributes to the broader understanding of particle transport mechanisms relevant to enhanced oil recovery, geothermal systems, and CO2 sequestration.