The complexity of identifying and quantifying natural and anthropogenic influences on surface movement in coal seam gas producing regions within the Surat Basin, Queensland

Abstract

Coal seam gas (CSG) production can cause surface movement through the compaction of coal seams and adjacent geological units and may cause subtle changes in the topographic gradients that have been alleged to cause impacts on agriculture. Since surface movement can result from both natural and anthropogenic processes, the determination of which processes, and the magnitudes of their contributions, are important challenges in the management of impacts. Differential interferometric synthetic aperture radar (D-InSAR) is a proven remote sensing technique used to monitor large-scale surface movement via radar satellite imagery. It is currently used by major CSG producers to conduct monitoring over their tenements. As D-InSAR can only deduce total observed movement, integration with other datasets is required to deconvolve the influences within observations. This paper provides an overview of the range of processes that influence surface movement. A case study using a D-InSAR time-series dataset (2016–2022) reveals the surface movement in the Surat Basin. Velocity measurements show that surface movement in the vicinity of CSG wells ranges between −18 and +9 mm/year. Analysis of any correlations between landscape characteristics and surface movement is provided, along with preliminary findings on some key observations. This work aids in refining calculations on what proportion of surface movement may be attributable to gas extraction.