Pore-Scale Modeling of the MICP process by using a coupled FEM-LBM-CA Model: With a focus on the heterogeneity of the pore structures

The microbially induced calcite precipitation (MICP) technique holds promising applications in groundwater remediation, soil improvement, and rock fracture sealing. In this study, a two-dimensional pore-scale numerical model is developed to simulate the coupled flow, reactive mass transport, and precipitation processes in MICP. The lattice Boltzmann method (LBM) and finite element method (FEM) are employed to solve the incompressible Navier-Stokes equations and the advection–diffusion-reaction (ADR) equations, respectively. The present model considers the processes of bacterial transport and attachment, ureolysis, and bacterial and calcite detachment. To validate the present model, we compare the results with the experimental data from the literature. We also perform sensitivity analyses of the model parameters, and results indicate that the calcite volume fraction is most sensitive to the parameter γ (the coefficient is used to account for the calcite precipitation away from solid surfaces). We investigate the effect of heterogeneous pore structures on calcite distribution, and the results demonstrate that the pore structures with large pore throats result in more calcite. In cases involving heterogeneous pore structures, such as the asymmetrically distributed pore structures in the upper and lower portions of the computational domain, the distribution of calcite precipitation is mainly influenced by the flow direction.