A Lattice-Boltzmann Based Method Applied to Digital Rock Characterization of Perforation Tunnel Damage

摘要

The lattice-Boltzmann method(LBM)for computational fluid dynamics has received considerable attention as a favorable approach for performing direct numerical simulation of pore-scale flow in porous media,especially for predicting permeability properties of reservoir rocks. The well recognized benefits of LBM as an approach for digital rock flow simulations include parallelizability,reliable convergence,and the opportunity to introduce multi-phase physics at the kinetic theory level. One of the challenges with LBM is to implement a surface boundary condition that avoids near-wall numerical issues,especially when portions of the relevant pore space are resolved with only a small number of grid cells. The present study examines LBM for digital rock using a boundary scheme based on explicit surface elements. A basic academic example of flow around packed spheres is presented,demonstrating the accuracy of the method even for coarse grid resolution. The method is then applied to the study of permeability alteration due to perforation tunnel damage. Using single-phase flow simulations based on micro-CT images of a small plug taken from a Berea sandstone test section,variations in porosity and absolute permeability of the damage zone around a typical perforation tunnel are characterized and visualized.