Microseismic Event Discrimination with Full-waveform Correlations
K. Van Wijk, D. Fagan, P. Shrestha and J. Rutledge
Event name: 76th EAGE Conference and Exhibition 2014
Session: Microseismic Instrumentation and Detection
Publication date: 16 June 2014
Info: Extended abstract, PDF ( 766.26Kb )
Price: € 20
Microseismicity provides valuable information in a host of different reservoir types. Applications include hydrocarbon and geothermal reservoirs, as well as subsurface carbon sequestration. The hypocenters of microseismic activity help identify individual faults, fault systems, and associated structures. In energy extraction this info aids siting production wells, increasing the odds that fluid-conducting faults are tapped. Full-waveform correlations help further discriminate events in clusters obtained from coherent phases only. The detail in the coda is what distinguishes small differences in location and/or source signatures; detail that cannot be extracted from (travel times of) coherent phases alone. We illustrate these approaches with data from a permanent vertical borehole array that recorded over 3800~microseismic events in 2008 and 2009 at the Aneth field, Utah (USA). Differences in the power spectra of individual microseismic events from a cluster are small, but consistent in terms of their spatial distribution. Also, these results were consistent with re-clustering based on correlations of the full waveforms. As a result, we suggest these events should be sub-clustered before further relocation with more advanced techniques, such as double difference tomography.