An experimental investigation on behaviour of coal under fluid saturation, using acoustic emission

Most studies on interaction of CO2 with coal have focused on the permeability and swelling characteristics of coal and fewer investigations have been carried out on its influence on the geomechanical attributes of coal. In this study, bituminous coals from Jharia coalfield in India were investigated for changes in the strength of samples due to saturation with moisture and CO2. It was found that the strength of coal samples reduced in each case of gas and moisture saturation. Maximum reduction in strength and elastic modulus of coal was observed in case of CO2 treatment of moisture saturated samples. The crack initiation occurred early at low stresses in coal while it took place at higher stresses in water saturated samples. The failure behaviour of specimens indicates shearing of coal and CO2 treated coal while the water saturated specimens collapsed along the fractures and cleats during loading. The level of reduction in strength is different in the two types of coal which highlights site specific study of CO2 injection on strength of coal.