Pore-scale modeling of effects of multiphase reactive transport on solid dissolution in porous media with structural heterogeneity

Fundamental understanding of the multiphase reactive transport with solid dissolution is crucial for a wide range of scientific and engineering problems. In this study, a pore-scale model is improved to study coupled processes of multiphase flow, mass transport, chemical reaction and solid dissolution in porous media with increasing structural heterogeneity. The results show that with the existence of multiphase flow, under the reactive transport conditions studied (Pe = 5, Da = 10; and Pe = 5, Da = 1), more compact dissolution pattern is generated due to the negative feedback between reactant transport and solid dissolution, while the feedback is positive in single-phase condition leading to wormhole dissolution. Besides, while it is found that the structural heterogeneity amplifies the wormhole dissolution in single-phase reactive transport processes or promotes the formation of fingering for multiphase flow, such heterogeneity effect is homogenized in the multiphase case. Finally, based on the pore-scale results, a new correlation between porosity, saturation and interfacial length is proposed which can be upscaled into the continuum-scale models.