oa The Application of Distributed Acoustic Sensing for the Location of Microseismic Events Associated with Longwall Mining

Longwall coal mining involves a section or ‘panel’ of the seam, roughly 300 m wide, being mined continuously by a shearer which moves backwards and forwards across the coal face. The shearer is protected from the roof collapsing above it by supports. As mining progresses the roof collapses behind the supports, forming the ‘Goaf’. Microseismic monitoring of longwall panels, although in no way routine, has been the subject of several studies aimed at improving safety through identification of possible rockburst or coal and/or gas outburst (where rocks/coal/gas are uncontrollable ejected/injected into the mine workings). Another potential issue is periodic (or cyclic) weighting, when strong units in the roof cantilever over the goaf. Usually geophones are placed within the mine workings due to ease of access but also occasionally within boreholes ( Hatherly et al. 1995 , Luo and Hatherly 1998 ). The number of geophones that can be deployed in each hole is limited and therefore Distributed Acoustic Sensing (DAS) is attractive as it offers the ability to sense the full length of the borehole as well as any sections of cable that are deployed on the surface ( Luo and Duan 2021 ).

In this paper we describe a