Perpustakaan Digital ITB

Optimizing oil recovery requires a fundamental understanding of multiphase flow mechanisms at the pore scale. In conventional waterflooding, the dominance of capillary forces over viscous forces at low capillary numbers Nc causes a portion of the oil to remain trapped as residual oil saturation (Sor). This study presents a numerical investigation of oil displacement at the pore scale using artificial and real-structure micromodels, focusing on the characteristics of the Capillary Desaturation Curve (CDC), pressure response, and oil ganglia dynamics. Numerical simulations were conducted using COMSOL Multiphysics with the Two-Phase Flow, Phase Field study to analyze changes in residual oil saturation and pressure response with increasing injection rate. The size distribution of oil ganglia was subsequently analyzed through MATLABbased image processing using equivalent radius as the characterization parameter. The results show that the numerical model successfully reproduces the primary displacement mechanisms and flow patterns observed experimentally. Both micromodels exhibit characteristic CDC behavior, with a plateau at low Nc followed by a sharp decrease in Sor beyond the critical capillary number. Increasing the injection rate causes the fragmentation of large oil ganglia into smaller ganglia. It also increases the differential pressure required to maintain flow through the porous medium. Overall, the numerical model successfully reproduces the main trends observed experimentally in residual oil desaturation and mobilization. These results demonstrate that pore-scale modeling can be used to investigate the effects of capillary and viscous forces on pressure response and oil ganglia dynamics during oil displacement by water.