1.2.1.2.2 Newcastle Coalfield

In comparison with the Hunter Coalfield, information on the Newcastle Coalfield is relatively sparse as the CSG resources of the Newcastle Coalfield have not been widely investigated. According to Creech (1992), regional gas distribution in the Newcastle Coalfield appears to be a relict feature of gas migration during coalification, and in-seam tuff layers, faulting and igneous dykes impede the migration process. Creech (1994) showed that it is highly likely that gas distribution in the coalfield is controlled by the Macquarie Syncline, and that there is no overall increase in the gas content with increasing depth. Burra et al. (2014, p. 448) stated that gas in the eastern part of the basin, such as areas of the Newcastle Coalfield, is generally dominated by biogenic and thermogenic hydrocarbons with elevated wet gas contents at depth.

Areas down-dip of the (Hunter and) Newcastle Coalfield (and in the extreme north of the Western Coalfield) have been identified as being prospective for CSG by Ward and Kelly (2013). Vitrinite reflectance increases to over 1% at depths of around 70 m indicating thermogenic gas generation from the deeper parts of the basin may be possible (Ward and Kelly, 2013, p. 40).