Coalbed Methane System, Exploitable Control Factors, Coalbed Methane Fields Characteristics, and Reserves in Bowen Basin

Coalbed Methane system is a natural system that encompasses coal seams and Coalbed Methane in them including all the geologic elements and processes. In Bowen Basin, Permian-Permian Coalbed Methane system is developed, it mainly contains Bandanna, Baralaba, Mantuan, Moranbah and Reids Dome Coalbed Methane plays. The Bandanna play was substantial resource, it accounted for 69% of Bowen Basin Coalbed Methane 2P reserves, and the Baralaba play accounted for 25% (December 2019). The controlling factors for exploitable Coalbed Methane filed are structure, permeability, deposition, coal distribution, gas content, coal rank, vitrinite content, and field geological characteristics. The characteristics of Coalbed Methane fields in Bowen Basin vary widely. At Dawson Valley, there are up to 10 seams in Baralaba Coal Measures with an aggregate coal thickness of up to 30 m at depths ranging from 300 to 1,000 m. At Fairview, the high gas content Bandanna Formation are characterised by having low structural stress along the crest of the Comet Ridge anticline. Average depth range from 550 to 950 mGL. Permeabilities are generally in excess of 50 mD. At Spring Gully, the coals targeted are Bandanna Formation. Aggregate coal thickness is between 5 and 9 m with the seams having both good gas contents and permeabilities. Average gas content is 12.5 m3/t. Average permeability is 100 mD.