COAL MINE GAS EMISSION ASSESSMENT FOR SEALED GOAF AREA OR ABANDONED MINE

Throughout Australia, no methodology exists for the estimating gas emission from sealed goaves or abandoned coal mines in relation to local mining, gas and geological conditions. This paper presents the current information in relation to the existing gas emission decline curves, which are used as a standard model of sealed goaves and inactive mine gas emission prediction for specific local conditions. This is commensurate with underground coal mine safety guidelines, including control of methane-air explosive mixtures and coal spontaneous combustion when a high percentage of oxygen is present, as well as with the Australian commitment to control and reduce greenhouse gases from all gas sources. The major application is where justification is needed to support the utilisation of the gas contained in these areas for commercial or environmental gain. Coal mine methane utilisation project capital is not likely to be available unless there is demonstrated confidence in the predicted gas availability over time. From the work conducted to date, a strong correlation exists between gas predicted by existing modelling and that measured in practice at a number of sites. Apart from the gas utilisation aspect, mine operations benefit from predicting gas emissions and relating them to ventilation design to provide adequate dilution. Another outcome is a unique PC software, which provides longwall goaf gas emission decline curves and is applicable for both coal mine gas management projects and coal mine methane utilisation purposes