Determination of the effective thermal conductivity of the porous media based on digital rock physics

Abstract

The thermal properties of a porous medium have been emphasized for its essential value in rock thermal engineering. Traditional theoretical and experimental methods on thermal conductivity studies of porous media usually contain homogeneous and isotropic assumptions with subjective idealization. Starting from the Digital Rock Physics (DRP), this paper establishes a digital internal structure model of a homogeneous rock through the processes of noise reduction, threshold segmentation, algorithmic process and three-dimensional (3D) reconstruction based on a series of micro-CT (computer tomography) images of the rock. With high quality meshes compatible with the Computational Fluid Dynamics (CFD) software, the Effective Thermal Conductivity (ETC) values are numerically obtained in three Representative Element Volume (REV) blocks with consistent porosity property. The results show that there is a 5% variation between the highest and lowest ETC data along different heat conduction directions. In addition, the simulation results satisfactorily fit with the empirical self-consistent model for ETC prediction of porous media. It is expected the innovative method reported in the present work can provide a feasible and reliable alternative for analyzing the rock thermal and other physical properties based on the accurate description of the internal microscale structures of the porous media.