Characterization of Coal Micro-Pore Structure and Simulation on the Seepage Rules of Low-Pressure Water Based on CT Scanning Data

Abstract

This paper used the X-ray three-dimensional (3D) microscope and acquired, through CT scanning, the 3D data of the long-frame coal sample from the Daliuta Coal Mine. Then, the 3D datacube reconstructed from the coal's CT scanning data was visualized with the use of Avizo, an advanced visualization software (FEI, Hillsboro, OR, USA). By means of a gray-scale segmentation technique, the model of the coal's micro-pore structure was extracted from the object region, and the precise characterization was then conducted. Finally, the numerical simulation on the water seepage characteristics in the coal micro-pores model under the pressure of 3 MPa was performed on the CFX platform. Results show that the seepage of low-pressure water exhibited preference to the channels with large pore radii, short paths, and short distance from the outlet. The seepage pressure of low-pressure water decreased gradually along the seepage direction, while the seepage velocity of low-pressure water decreased gradually along the direction from the pore center to the wall. Regarding the single-channel seepage behaviors, the seepage velocity and mass flow rate of water seepage in the X direction were the largest, followed by the values of the seepage in the Y direction, and the seepage velocity and mass flow rate of water seepage in the Z direction were the smallest. Compared with the results in single-channel seepage, the dual-channel seepage in the direction of (X + Y) and the multi-channel seepage in the direction of (X + Y + Z) exhibited significant increases in the overall seepage velocity. The present study extends the application of 3D CT scanning data and provides a new idea and approach for exploring the seepage rules in coal micro-pore structures.

Simulation Analysis on Water’s Micro Seepage Laws under Different Pressure Gradients Using Computed Tomography Method

“…e seepage characteristics were then analyzed from a microscopic perspective, based on the simulation results. e present study could provide a new way of gaining insights into the nature of water injections in coal seams and contribute to the improvement of water injection efficiency [39].…”

Three-dimensional spatial structure of the macro-pores and flow simulation in anthracite coal based on X-ray μ-CT scanning data

“…It is generally known that the higher the image processing accuracy is, the better the 3D reconstruction effect of the pore structure will be (Zhou et al 2016). The original 2D CT slices obtained based on the X-ray μ-CT scanning are more or less affected by noise, so there are scatter dots noise in the CT slices ( Fig.…”

“…The visualization analysis of the gas flow with the interconnected pores as the carrier and the discussion of the pressure field and velocity field are of important engineering value for the development of low-permeability reservoirs (Zhou et al 2016;Ni et al 2017). Based on the 2D CT slices of the sandstone, Ju et al (2014) have simulated the gas flow with the interconnected pores in sandstone as the carrier through using the Lattice Boltzmann method, but this method will take a long time and consume a lot of manpower (Li et al 2017;Yang et al 2018).…”

Numerical Simulation Analysis of Water Injection Seepage Law in Micro Porous Structure of Coal

“…In addition, there are very few reports on the highprecision micro-pore structure of coal to investigate the rules of seepage during water injection. Zhou et al [30,31] take long flame coal as an example, using CT technology to characterize the real pore in coal, and a low-pressure water seepage simulation was carried out. The variation rule of water pressure and velocity in seepage process was analyzed.…”