In this paper a laboratory investigation into the effect of confining
stress, water content and gas desorption on coal permeability is presented. Of
major significance is the effect of coal permeability on outburst occurrence and
methane production, which is influenced by changes in stress. Test results
indicated that the shrinkage of the coal matrix associated with desorption is
greater than the coal matrix compressibility which will cause a reduction in the
effective stress, hence increasing coal permeability.