Experimental study on gas permeation characteristics of pressure-bearing crushed anthracite coal in Qinshui coalfield
It is of great significance to understand the gas migration rule in the caving zone in order to improve the extraction efficiency of coalbed methane.In this study,self-designed gas permeability test equipment for crushed coal and rock mass was developed.By virtue of this equipment,we carried out compaction-permeability tests on crushed anthracite of 0.32～0.63 mm particle size.The results show that:The dynamic gas flow process in crushed anthracite can be divided into two representative types(type Ⅰ and type Ⅱ)before the stable adsorption equilibrium is achieved.There is a quasi-threshold pressure gradient of gas migration in the crushed anthracite at low Reynolds number.And the quasi-threshold pressure gradient decreases with the growth of porosity.The permeability of crushed anthracite is logarithmically positively correlated with the gas pressure;the permeability decreases exponentially with the decrease of void ratio.With the increase of axial stress,the crushed anthracite is transformed from elastic deformation to inelastic deformation,and the sensitivity of permeability to axial stress decreases at this time.
NETL
NSTL
万方数据
