CO2 Sequestration effect on outburst in coal mining

Abstract

Coal mass has the potential to store substantial amounts of CO2 in the coal matrix and that CO2 has the ability to move through the coal seam pore and fracture systems, which influences the release of gases during coal mining and the CO2 sequestration process. In addition, the reduction of coal mass strength due to CO2 adsorption greatly affects the outburst process. The sudden and violent failure of coal seam with releasing large amount of gas is called outburst in coal mining. Up to date only few have been conducted to investigate the effect of CO2 adsorption induces strength reduction on the outburst process. The main objective of this study is to investigate the effect of CO2 injection on outburst in coal mining. Uniaxial Compressive Strength (UCS) experiments were therefore conducted on black coal samples, which have been saturated with CO2 and N2 at various pressures at 33 ºC. According to the results CO2 adsorption causes the UCS strength of coal to be reduced by up to 53 % and this higher strength reduction is due to the CO2 adsorption induce coal matrix swelling. However, N2 saturation causes the coal strength to be slightly increased. According to these observations, there is a high risk associated with CO2 sequestration process in coal seam as it significantly reduces the coal seam strength, which has direct influence on outburst process in coal.