Monitoring and management of subsidence induced by coal seam gas extraction

About this Document

This report examines the monitoring and mitigation of subsidence induced by coal seam gas (CSG) extraction. It provides a synthesis of experiences relating to CSG subsidence in Australia and overseas, the assessment approaches being used to predict the scale and extent of subsidence, and monitoring and management options for subsidence induced by CSG extraction. A review of publicly available literature identified no reference to adverse impacts of subsidence due to CSG production. The review process also found that:

• predictive subsidence modelling provides estimates of both compaction of hydrogeological units due to changes in groundwater pressure and compaction of the coal seam due to degassing
• model predictions can be used to inform subsidence monitoring schemes and the management or mitigation of potential impacts on assets
• the collation of subsidence monitoring data across Australian coal seam gas developments would be useful to review critical conditions and improve subsidence prediction models.

It is recommended that subsidence monitoring be undertaken in areas of CSG development, noting that:

• monitoring can provide an early warning of subsidence that may pose a risk to infrastructure and the environment
• determining the potential impact of subsidence on sensitive assets such as infrastructure, water resources and ecosystems should include impact criteria specific to that asset type.