Estimation of permeability of porous material using pore scale LBM simulations

Abstract

The aim of the present work is to conduct an evaluation of the ability of Single Relaxation Time (SRT) and Multi Relaxation Time (MRT) formulations of Lattice Boltzmann Method (LBM) to estimate permeability of a porous sample from numerical simulations in the pore scale. Fluid flow is simulated through digitized micro-tomographic images obtained using accurate imaging techniques. The dependence of the permeability calculated on the grid resolution, method used and the variable parameters in the method are studied. The mesoscopic nature of the LBM formulation facilitates the accurate computation of the property values from the pore scale simulation. However, it is observed that use of SRT LBM might not give a viscosity independent prediction of permeability due to numerical errors inherent in the method. Instead, the MRT LBM is found to give accurate predictions which are less dependent on viscosity with appropriately selected relaxation parameter matrix. Moreover, the effect of grid resolution selected on the accuracy of permeability values predicted is closely studied for both SRT and MRT. The conclusions obtained could be of use in predicting permeability for macroscopic flow calculations and realistic reconstruction of the pore geometry making these studies important from academic and industrial viewpoints.