1.2.2.2 Coal seam gas

To date, most CSG exploration has focused on a small area, east of Stratford, where up to 11 major (in this context, >2.5 m thick) seams and numerous minor seams (≤2.5 mm thick) occur, with an average total thickness of up to 60 m (Bilston, 2008, p. 7; Ward and Kelly, 2013, p. 57). Most methane is thermogenic although some minor biogenic gas is found at shallow depths (Ward and Kelly, 2013, p. 57). The best known CSG resource in the Gloucester subregion is in the Gloucester Coal Measures (O'Kane, 2013, p.57; Ward and Kelly, 2013). AGL indicated that, as at 30 June 2013, the Gloucester Basin has current proved and probable (2P) reserves of 454 PJ and proved, probable and possible (3P) reserves of 565 PJ (AGL Energy Limited, 2013a, p. 20). Gas content of the coal in the Gloucester Basin sequence increases with depth from less than 10 m³/t at depths of less than 200 m, to 25 m³/t at depths of 600 m (Gurba and Weber, 2001 cited in Ward and Kelly, 2013, p. 56).