Presentation 2021-006
| Author(s) | Date | 2021-09-13 |
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We analyzed the temporal evolution of induced seismicity related to hydraulic fracturing activities in the Duvernay Fm., near Fox Creek, Alberta. For this analysis, we calculated time-dependent earthquake recurrence parameters, a(t)- and b(t)- values, which are the base for the probabilistic seismic hazard analysis. From these earthquake recurrence parameters, we calculated the annual likelihood of earthquakes larger than magnitude M>4 from 2014 until 2019. We found that the seismic hazard in Fox Creek has consistently decreased since 2015, from a 95% probability to have an earthquake M>4 in 2015 to a 4% probability in 2019. This contrasts with the peak in the overall number of earthquakes larger than M>2, which occurred in 2017, and the peak in the total volumes and the number of hydraulic fracturing wells per year in the Duvernay Fm., both occurring in 2019. On the other hand, the b-values rapidly increased after 2016, leading to a steady decrease in the likelihood of moderate events. We think that this trend in decreasing seismic hazard, which contrasts with increasing human activity, could be associated with implementation of regulatory instruments (Alberta Energy Regulator Subs-Surface Order Number No. 2), active mitigation strategies implemented by the operators, and avoidance of areas identified to be susceptible to induced seismicity.