Measurement of the coefficient of seepage characteristics in pore-crushed coal bodies around gas extraction boreholes

Gas extraction is a form of energy extraction. The seepage and transport of gas during extraction is complex. The accurate determination of its permeation parameters is an important technical parameter. A tri-axial permeation test of the crushed grain media was designed to determine the permeation pattern of gas fuels within the crushed coal around the borehole. The resistance to gas fuel seepage was explored. The results show that: the pore structure formed by the crushed coal grains will be compressed and closed again under three-dimensional stress. The process of deformation and destruction of crushed coal grains can be divided into three stages: when the grains are subjected to a force of 1.2 kN-1.4 kN, the grains may compress each other to form a colloid. The coefficient of resistance is dependent on the permeability of the crushed coal sample, and the non-Darcian phenomenon caused by inertial loss during permeation can be characterized by the distribution of Re values f 1/4 149.1/Re thorn 1.5. The two coefficients of the quadratic term in the Forchheimer equation change dynamically as the flow regime changes. This result can provide a theoretical basis for the efficient extraction of gas resources. (c) 2022 Elsevier Ltd. All rights reserved.