3D acoustic and microseismic location of collapse events in complex, 3D geological structures

Abstract : Passive microseismics is a well developed technique that has gained importance in petroleum exploration operations as well as in geohazard assessment. When applied in complex geological environments, it requires advanced processing capabilities to ensure useful accuracy in the source location and characterization. Here we investigate a fast marching method to determine the travel-time field, rays and ray take-off angles in complex 3D media, for application with a direct-search event location method. We then illustrate and discuss the potential of the chosen methodology in the mining context. This methodology allows improvements in acoustic monitoring of large-scale underground mines by taking into account the intrinsic characteristics of propagation of the acoustic waves. Ongoing work on a dataset collected during the monitoring of a large-scale salt cavern collapse is also discussed. We expect that the use of an evolving 3D model will help to reduce the location errors and improve the dataset analysis, improving risk management for time-varying collapse events.