Data Mining Microseismicity Associated to the Blue Mountain Geothermal Site
Description:
Induced seismicity in geothermal sites seems to be strongly correlated to changes in energy production rates. Interestingly, evidence of increasing microseismicity during geothermal power plant outages has been observed worldwide. Seismic studies in these areas provide several hypotheses mostly based on fault slip induction by changes in pore pressure. However, geological dissimilarities between regions halt assumptions of a unique stress mechanism for this phenomenon. Past methods like microearthquake location mapping have proved useful in delineating subsurface structure in these systems and understanding pathways for injection flow. Nevertheless, the stress changes triggering these events remain unclear in some cases. We apply PageRank, a data mining technique, to assess microseismic event connectivity and evolution at the Blue Mountain geothermal site during the 2017 and 2018 stimulations to understand the origin of increased seismicity on-site during annual power plant shutdowns (September 2017 and May 2018) and other power plant operations. We use directly (CC >= 0.67) and indirectly (CC < 0.67, linkage stations >= 6) links events to a reference event, a high PageRank event leading a seismic cluster. Cluster characterization from 2017 resulted in six unique families comprised of three or more microseismic events with similar waveform topology, with one of these families related to the September outage. For 2018, six unique families were identified comprised of two or more events. Four of these families are related to the May outage. In addition, for both years, indirectly links events within our identified unique families show a similar waveform pattern, confirming their belonging to the cluster. Event relocation within clusters will show a more clear picture of stimulation changes, and will help understand why large numbers of events are happening during the power plant shutdowns.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-843429
Session: Understanding and Managing Induced Seismicity [Poster]
Type: Poster
Date: 4/19/2023
Presentation Time: 08:00 AM (local time)
Presenting Author: Lucia F. Gonzalez
Student Presenter: Yes
Invited Presentation:
Authors
Lucia Gonzalez Presenting Author Corresponding Author lfgonzalez5@miners.utep.edu University of Texas at El Paso |
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Data Mining Microseismicity Associated to the Blue Mountain Geothermal Site
Category
Understanding and Managing Induced Seismicity