Introduction
The figure below shows gas desorption data and rank for 28 cored CSG wells in the Bowen Basin. As can be observed (left image), there is a weak correlation between gas content and depth.
The gas contents of the lower rank coals, such as sub-bituminous and high volatile bituminous do not exceed 10 m3/ton (or the equivalent 353 scf/ton), although the literature does suggest a few exemptions have been found. According to Troup et al (n.d.), the coal seams targetted in the Bowen Basin are generally thick and laterally continious.
Reported analysis of gas samples have suggested that natural gas in these coals are have methane concentrations of 95% or better (in at least 86% of the samples tested). This implies low processing challenges.
Gas contents of the Bandanna Coals in the Fairview Field (right image) are based on gas desorption tests from 27 observation wells drilled across the field. Contrary to the greater Bowen Basin, the general trend of increase in gas content with depth is evident. In Australia, the Bandanna Coal Measures are productive in the Fairview, Spring Gully, Arcadia Valley, and Mahalo projects. Other coal measures of the Bowen basin include the Rangal and and Moranbah coal measures.
Gas Contents for the Bandanna Coals of the Bowen Basin (Salmachi et al, 2021)
References:
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Various Investor and News Presentation, Dension Gas, https://denisongas.com.au/ 2023.
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Alireza Salmachi, Mojtaba Rajabi, Carmine Wainman, Steven Mackie, Peter McCabe, Bronwyn Camac and Christopher Clarkson, History, Geology, In Situ Stress Pattern, Gas Content and Permeability of Coal Seam Gas Basins in Australia: A Review, Energies, 2021
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Alison Troup, Neal Longdon, and Justin Gorton, Petroleum Plays of the Bowen and Surat Basins, CSIRO Publishing, n.d.
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“Bowen Basin Concept Study”, Final Report, Queensland Government - Department of Resources, 2 December 2021