Laboratory investigation of gas permeability and its impact on CBM potential

Gas permeability is an important characteristic of coal seam(s) to determine the economic success of CH4 extraction and CO2 sequestration. There exists no comprehensive approach to predict the mechanical behaviour during CH4 extraction, and CO2 sequestration as coal is highly heterogeneous. Exhaustive laboratory experimentation is often the only approach to successfully predict its behaviour. Coal experiences triaxial stress conditions when change of force field occurs. This paper presents the mechanical properties and change in gas permeability at varying confining as well as gas pressures in a triaxial experimental set-up using Darcy's approach. Mutual relations between permeability, in situ confining pressure as well as gas pressure have been established statistically. A reservoir simulation investigation has been carried out to predict the rate of coal bed methane (CBM) production and the cumulative amount of CBM over the 5-year life of production well.