Effects of temperature and stress on permeability of standard coal briquette specimen.

The standard coal briquette specimens from Huaxing Mine, in Jilin, were made. The permeability test was performed in ZYS-1 equipment for the measurement of permeability to study the effects of confining stress, axial stress and temperature on permeability of coal briquette specimens. The results show that with the increasing confined stress, the permeability of coal briquette specimen decreases. The permeability of coal is greatly effected by differential stress. Under the condition of confined stress, with increasing differential stress (axial stress) the permeability of the specimen decreases due to the elastic contraction. When the specimen failed due to increasing differential stress their porosity volumes increase due to dilation, and the permeability also increases. Therefore the permeability of samples takes on "V" curve under low confined stress. However the permeability decreases under high confining stress. The flow of methane in coal is greatly effected by temperature. When the temperature increases, on one hand the kinematic viscosity of methane increases. On the other hand the grains of coal swell and lead to contraction of flow space and reduction of permeability. [ABSTRACT FROM AUTHOR]