Other coal-bearing units

The Epsilon and Daralingie formations within the Permian sequence of the Cooper Basin also contain coal seams of varying thickness and quality. The Epsilon Formation is generally considered as part of the Roseneath – Epsilon – Murteree shale gas target sequence (Goldstein et al., 2012). Coal in the Epsilon Formation is described as black to greyish black, dull to vitreous, moderately hard to firm and variably silty (Beach Energy, 2012a, 2012b; Beach Petroleum Limited, 2004; Santos Limited, 1988; Strike Energy Limited, 2010).

Coal seams are a minor component of the Permian Daralingie Formation, and have been intersected in some petroleum exploration wells. Such coals are described as black, subvitreous to vitreous, hard to brittle and silty (Beach Energy, 2012b; Santos Limited, 1988, 1990, 1993; Senex Energy Limited, 2011). It generally occurs as minor interbeds within siltstone or shale-dominated sequences, with individual seams up to 1 m thick (Santos Limited, 1988). The Tirrawarra Sandstone is reported to contain trace coal intersections (Alexander et al., 1998).

The principal coal-bearing unit in the Eromanga Basin is the Winton Formation, comprising up to 1200 m of non-marine shale and siltstone with minor coal layers. Individual coal seams are thin (1 to 2 m) and not laterally extensive. The Winton Formation coals may be sufficiently mature to generate thermogenic gas in some parts of the subregion, however, the thin, discontinuous nature of the seams and low gas contents are below current commercial thresholds (Goldstein et al., 2012). Coal also occurs in the Birkhead Formation, with seams generally less than 1 m thick. The Birkhead Formation becomes progressively sandy from the north-east to the south and south-west at the expense of coal.

The Eyre Formation includes beds of lignite and clay, with minor root horizons. Carbonaceous lithologies are commonly leached in outcrop. The lignite beds are thin and of low quality (Callen et al., 1995).

Last updated:
5 January 2018