Spatiotemporal evolution of ground movement in coal seam gas regions: Insights from InSAR

The exploration and production of coal seam gas (CSG) are growing worldwide. The expanding CSG industry in Australia has raised concerns about land subsidence and its potential environmental impact. Comprehensive monitoring and analysis are required to understand ground movement in CSG regions to support sustainable environmental management. This study employs Interferometric Synthetic Aperture Radar (InSAR) data from 2015 to 2023 to investigate the spatiotemporal ground movement patterns in the Surat Basin. We confirmed the spatial overlap of land subsidence and CSG footprints. Group-based analysis based on distances to CSG wells was conducted to understand the driving factors of ground movement. For the non-CSG area, high-clay soil coincides with more extreme ground movement; no consistent correlation can be identified between rainfall and ground movement; cropping lands show higher movement variation; the correlation between ground movement and water levels in the alluvium is not statistically significant. For the CSG region, a general linear function between subsidence and the cubic root of water and gas production is observed; the influence of coal thickness on subsidence variation is not obvious; bridging is unlikely to happen beyond a few months in the study area; a subsidence time series is derived allowing an estimate of expected subsidence over 17 years. Our findings provide valuable knowledge to support sustainable CSG management and regulatory decision-making. The research contributes to the broader understanding of anthropogenic impacts on ground movement in subsurface resource extraction regions.