The study of coal microstructure based on 3D reconstruction is of great practical significance for CBM extraction, thermal convection in situ pyrolysis, and oil and gas transport in coal seams. In this paper, oil-rich coal is scanned by CT, and then, 3D reconstruction is performed by using 3D visualization software AVIZO to establish a 3D pore structure model of oil-rich coal. Finally, COMSOL Multiphysics software is used to simulate the changes of seepage velocity and seepage path during the seepage of nitrogen in the pore space. The results show that Oil-rich coal has anisotropy; the permeability in X, Y, and Z directions is very low and shows a great difference, with the increase of N2 temperature, the effective permeability in all three directions increases; with the increase of pressure gradient, methane seepage velocity increases gradually, and the curve shows the obvious non-linear relationship.
Keywords Oil-rich coal, porous media, nitrogen, seepage