Derrrick Chambers, Alexander Ankamah, Ahmad Tourei , Eileen Martin, Tim Dean, Jeffrey Shragge, John A Hole, Rafal Czarny, Gareth Goldswain, Jako du Toit, Shawn Boltz, James McGuiness

Seismic monitoring of underground longwall mines can provide valuable information for managing coal burst risks and understanding the ground response to extraction. However, the underground longwall mine environment poses major challenges for traditional in-mine microseismic sensors including the restricted use of electronics due to potentially explosive atmospheres, the need to frequently and quickly relocate sensors as rapid mining progresses, and source parameter errors associated with complex time-dependent velocity structure. Distributed acoustic sensing (DAS), a technology that uses rapid laser pulses to measure strain along fiber optic cables, shows the potential to alleviate these shortcomings and improve seismic monitoring in coal mines. This work demonstrates several DAS deployment strategies such as deploying fiber on the mine floor, in boreholes drilled from the surface and from mine level, on the longwall mining equipment, and wrapped around secondary support cans. This paper also discusses some of the data processing and deployment improvements that could help DAS-based monitoring become routine in underground longwall mines. Because DAS applications in coal mines are just now emerging, the findings presented here will aid decision makers in assessing the potential of DAS to meet their needs and help guide future DAS deployment designs in underground coal mines.