Building upon the previous modelling work on coalbed methane reservoirs by the authors, recently reported experimental horizontal stress data for two coal samples tested under uniaxial strain conditions have been analysed. As well as CH₄, non-adsorbing Helium has also been used in the experiments. Deviation between the model and the experimental CH₄ stress data at low pore pressures (< 3 MPa) are observed, which, as in the previous study, may be attributed to the onset of shear failure experienced by the coal samples. In addition, CO₂ was also used on one of the samples after the CH₄ experiment. The post-failure CO₂ stress data could be matched using a combination of a reduced Young's Modulus and an increased Poisson's ratio. The results of this study have provided further evidence for the validity of the equation for computing the changes in the effective horizontal stress in producing coalbed reservoirs, which forms an integral part of the Shi and Durucan permeability model.