A Model for Gas Distribution in Coals of the Lower Hunter, Sydney Basin

The Sydney Basin has a long history of underground coal mining. Coal seam gas has also played a signifi cant role mainly because of safety concerns, and the impost for fast, economic extraction of coal. Major Sydney Basin mine disasters associated with coal seam gas include those at Mount Kembla, 1902, Bellbird, 1923, and more recently, Appin, 1979. Modern mining has controlled the risks associated with coal seam gas mainly by the imposition of gas management techniques that come at a considerable cost. However, these techniques have resulted in an improved understanding of coal seam gas science, and have proved outstandingly successful in managing the gas risk associated with coal mining. There has been no gas related fatalities in Sydney Basin underground mining since 1994. A more recent development has been the growth of the Australian coal seam methane (CSM) industry, which has emerged from being no more than a promising concept in 2000 to become a viable new energy sector. In Queensland, approximately 82% of the gas supplied is now derived from CSM. The fi gure is 23% for the entire eastern Australian gas market (Baker, pers. com. RLMS 2008). In NSW and Queensland, the CSM industry is tipped to grow signifi cantly over the next 25 years, echoing patterns already experienced in the USA. The proposed development of gas to liquids plants in Queensland is likely to ramp up the production of CSM in eastern Australia. In NSW, production occurs in the Sydney Basin in the Camden area, and there are signifi cant exploration efforts underway in the Hunter region. Coal mining also remains as a vitally important contributor to the national economy. An understanding of the distribution of gas within the coal measures helps with both the extraction of coal and the generation of CSM. Coal mining companies are also well aware of their longterm corporate responsibilities to manage greenhouse emissions associated with mining activities. This paper is a direct result of that awareness, and uses data from a study undertaken in the Lower Hunter Valley of NSW for a major coal mining company (see Hennings et al 2007; also see Fig. 1, the ‘Lower Hunter Coal Seam Gas Area’).