1.2.1.2 Coal seam gas

Two coal-bearing sedimentary sequences in the onshore Gippsland Basin and one in South Gippsland are prospective for natural gas. The Early Cretaceous Strzelecki Group across the Gippsland region is a potential CSG target, as is the overlying Latrobe Group in the onshore Gippsland Basin (Goldie Divko, 2015).

In 2004 Karoon Gas carried out the only gas test to date on the black coals of the Strzelecki Group in the Gippsland Basin bioregion. In the exploration well Megascolides-1, Karoon Gas intersected coal seams that were thin and sparse with a single gas content of 3.37 m³/t recorded (Grosser, 2005). The subsurface geology of the area is largely unknown with very limited data collected to date (Goldie Divko, 2015).

Brown coaIs within the Traralgon Formation of the Latrobe Group are extensive and attain great thicknesses, with some individual seams aggregating up to 150 m (Holdgate, 2003). Although there has been some preliminary exploration targeting these seams (e.g. Gastar Exploration Ltd, 2005), and an estimate of 3.7 trillion cubic feet (TCF) of gas (IER, 2014), no gas content or permeability measurements have been collected from the lignite seams of the Traralgon Formation (Goldie Divko, 2015). Hence, there is significant geological uncertainty associated with the prospectivity of the region for CSG.