Pore-scale Heterogeneity Assessed by the Lattice-boltzmann Method

A digital imaging technique is used to characterize pore-scale structures and to predict fluid flow at the scale. Heterogeneity at the pore-scale can be assessed by the micro-Computed Tomography (micro-CT), which provides complicated boundary conditions of porous media, and it can also be identified by the numerical flow simulation using the lattice-Boltzmann method (LBM) on the digital image. Both the LBM and the digital image are used to estimate the Representative Element Volume (REV) of the rock. Different types and sizes of pore-scale structures are evaluated in terms of the effects of heterogeneity and the porosity–permeability correlations. Numerical simulation on the digital image of porous media is useful to understand its heterogeneity and such digital experiments can add value to the laboratory measurements. INTRODUCTION Representative microscopic model of porous media is frequently employed to predict petrophysical properties of reservoir rocks. The microtomography has been used to characterize pore-scale structures and to simulate fluid flow at the scale [1]. Petrophysical analysis including in-situ saturation monitoring by conventional X-ray CT during a coreflood experiment can indicate the heterogeneity within a rock sample [2]; however, it is often difficult to understand the heterogeneity at the smaller-scale using only a core-scale measurement and its numerical simulation. Pore-scale heterogeneity can be assessed by the digital image and the numerical simulation using the LBM. The LBM provides a good approximation to solutions of the Navier-Stokes equations, using a parallel and efficient algorithm that readily accommodates complex boundaries such as porous media [3, 4]. These complicated boundary conditions are provided using the microtomography. Fluid flow at the pore-scale is simulated by the LBM in order to assess