Characterization of pore-fracture structure and seepage simulation based on micro-CT scanning

Abstract

Taking the non-stick coal from Yangchangwan Coal Mine as the research object, based on the micro-CT scanning experiment and Avizo processing software, the pore-fracture, minerals and coal matrix of the coal are accurately extracted and segmented. Through the three-dimensional reconstruction technology, the connected pores and fracture models are obtained. On this basis, an equivalent pore network model（PNM）with the morphological topological structure of pores and fractures was further established, and the pore-throat structure parameters in the coal were statistically analyzed, including pore radius, pore volume, throat radius, throat length, and coordination number. Based on the pore-scale seepage simulation, the visualization seepage of single-phase water in the pore-fracture space was realized, and the absolute permeability in three directions was calculated. The results show that the Yangchangwan non-stick coal is dominated by flaky pore clusters and large-scale vertical fractures. The average pore radius and throat radius is 106 μm and 27.79 μm, respectively, and the average coordination number is 3.45. In the process of single-phase water seepage, the seepage velocity in the pore-fracture space is higher than that of the outlet and inlet, and the permeability in the three directions shows obvious anisotropy. Among them, the absolute permeability value in the y direction is the largest, and in the x direction is the smallest.

Keywords

• micro structure
• equivalent pore network model
• pore-scale
• pore-throat structure parameters
• absolute permeability
• anisotropy