Resolution Effect: An Error Correction Model for Intrinsic Permeability of Porous Media Estimated from Lattice Boltzmann Method

Abstract

In digital rock physics, the intrinsic permeability of a porous rock sample can be evaluated from its micro-computed tomography ($$\upmu$$-CT) image through lattice Boltzmann method (LBM) simulation. The LBM permeability evaluation has been increasingly adopted by the oil and gas industries, especially when the access to core samples is limited. In order to accurately evaluate the permeability of porous media, this digital approach requires high-quality $$\upmu$$-CT images with sufficient resolution and size. In practice, however, the LBM simulation is often performed using images of reduced resolution, due to limitations in computing power and simulation time. As a result, the permeability results obtained are often compromised with significant errors, known as the resolution effect. In this study, the resolution effect is quantitatively investigated to identify the primary causes of error, based on which an error correction model for the LBM permeability evaluation is proposed. The model uses such geometric attributes as connected porosity, specific surface area and diffusion tortuosity to quantify the resolution effect and achieve error correction. Demonstrated on various types of porous media including sandstone, carbonate rock, sand pack, synthesis silica, etc., the proposed error correction model can effectively correct the errors in LBM permeability evaluation due to the resolution effect. Our error correction model makes image resolution reduction more meaningful and creditable for LBM permeability evaluation of porous media, thereby supporting its adoption in practical applications.