Variations in Rangal Formation coal deposition (age: upper Late Permian) at Comet Ridge, Southern Bowen Basin, Queensland, Australia, as a function of depositional environment
James H Butler
2000 - 2009
Faculty of Science and Technology
Aspro David Gust, Dr Gary Huftile
The aim of the thesis is to determine the key factors that control the production and release of coal seam methane (CSM). It will relate depositional environment and geological history to CSM productivity. This will involve testing the following hypotheses:
CSM is related to coal quality in that the mineral content of the coal will affect cleat filling during diagenesis. Associated strata may also promote cleat infilling during diagenesis (e.g. tuff layers). The coal depositional environment will control the amount of ash in the coal.
CSM is related to coal quality in that the coal type will control the way the coal fractures. Bright coal should produce more cleats than dull coal. Furthermore, some macerals will carry different quantities and types of minerals compared with others.
CSM is related to geological history in that cleats form at certain ranks and time and may fill or heal depending on diagenesis, the thermal regime and the structural regime.
CSM is controlled largely by cleat development in coal and this is controlled by coal type, coal diagenesis, stress fields, timing of structures and basin dynamics.
CSM production is hampered by cleat infilling. Occurrence of cleat infilling depends on when the cleats fanned with respect to coal diagenesis. So the distribution of cleat infillings is critical to CSM production. The history of the cleat infillings will form a major part to the study. This involves timing of cleat formation in relation to stress fields and to infilling mineralogy.