Methane seeps in the Condamine River
This fact sheet presents the current state of scientific knowledge on methane seeps in the Condamine River including natural and human causes, and the human and environmental health and safety impacts of methane escaping from underground. This fact sheet has been developed by CSIRO researchers with expertise in the hydrogeology, geology, ecology and biogeochemistry and from multiple sources to summarise what we currently know about
these methane seeps.
Key points
- Depressurisation of the Walloon Coal Measures during CSG production could generate horizontal migration of free methane gas. However, this flux of methane is likely to be small because of the shallow dip of the coal beds and the distance to gas production fields.
- Hydraulic fracturing is unlikely to be the cause of bubbling in the Condamine River because to date there has been no hydraulic fracturing by the CSG industry in these production fields/
- Variation in bubbling of the Condamine River may be caused by:
- An increase in river water flow; moving sand and sediments that previously sat over the seeps and limited their seepage.
- Groundwater receding from the Condamine River alluvium since the 2011 floods has reduced pressure over the Walloon Coal Measures near Chinchilla, allowing trapped gas to expand and rise to the surface.
- CSG industry activity in production fields 5 to 6 km away has reduced pressure in the coal seams leading to possible up-dip flow of gas into the network of fractures and thereby into the Condamine River.
- CSIRO research has found no evidence that these seeps have any adverse environmental impact on the plant or animal life of the river and its surroundings. To date, there is no public health or safety risk caused by the methane concentrations measured in the area of these or any other seeps in the Surat Basin that CSIRO has measured