Insights on the Robustness of Event Locations from Analysis of Acoustic Emissions Observed in a Triaxial Experiment
I. A. Vera Rodriguez, S. Stanchits and J. Burghardt
Event name: 78th EAGE Conference and Exhibition 2016
Session: Microseismic - Event Localization on Micro and Macro Scale
Publication date: 31 May 2016
Info: Extended abstract, PDF ( 1.91Mb )
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This work compares acoustic emission raw-location results for a hydraulic fracture experiment performed under triaxial stress conditions. The observed acoustic emissions were located using two different homogeneous velocity models. One of the models considers only compressional velocities derived from the measurement of transmission signals. The second model uses the same velocity for compressional waves but also incorporates an estimation of shear wave velocity. Both, compressional and shear wave velocities, present errors that in the case of compressional waves are known to be in the range from 1.5% to 5%. The acoustic emission raw-clouds obtained with both models are compared with the surface of the created hydraulic fracture, which was laser-scanned over the open rock sample. The raw-location results highlight robustness in the location algorithms to the errors in the velocity models and place more importance in the incorporation of shear wave information for the determination of accurate hypocentre locations.