Determination of coal burst risk zones using CT scanning of coal microstructure

The Australian Coal Association Research Program (ACARP) sponsored a research project (C28012 Extension) investigating the role of microfracture propagation contributing to the mechanism of gas related coal bursts. The research project used Computed Tomography (CT) scanning to identify microfracture networks and the spatial and statistic relationship of microfracture networks adjacent to known burst prone structures. An NSW coal mine was used as the case study mine for this assessment. The case study mine has experienced coal bursts and outbursts in relation to various geological structures consisting of dykes and a thrust fault. This paper defines the burst risk zone adjacent to structures at the case study mine and supports the theory of microfracture propagation to increase the microfracture frequency, in turn increasing gas desorption volumes. The research also highlighted that variability in microfracture networks was a key feature adjacent to structure, where low microfracture density or low permeability zones were observed that could act to restrict gas drainage into roadways. This paper presents the mechanics of gas desorption and gas flow during coal mine development drivage that can lead to gas related coal bursts and compares this with gas flow in areas of typical coal.