Three-dimensional Reconstruction of Coal Structure and Numerical Simulation of Gas Seepage by CT

The data image of long flame coal slice was obtained by CT scanning, and its xy plane slice was edited to 60 μm×80 μm by Image J. 120 consecutive slices were selected as the target area and imported into Avizo for three-dimensional reconstruction. CFX fluid simulation modeling method was used to simulate the low-pressure gas seepage and quantitatively analyze the law of gas seepage in coal. The results show that the volume fractal dimension of the pore is 2.56, and the fractal dimension of the xy section direction of the coal sample is between 14.2 and 1.56; the equivalent pore network model is more accurate than the bat model; the pore number of pore structure model of coal sample is 1 760 and throat number is 956; the pressure drop velocity along +z is much less than that along -z direction; the seepage velocity along -z direction is much higher than that along +z direction, and the maximum flow velocity is 600 m/s, which is 1.5 times higher than that along +z direction; the majority order of magnitude of the average seepage mass flow in the xy section of the two methods is about 10-10 kg/s; the seepage process shows the transformation between potential energy and kinetic energy.