Insights on the Criticality of Faults From Dense Monitoring of Induced Seismicity from Moment Tensor Based Stress Inversion
Session: Mechanisms of Induced Seismicity: Pressure Diffusion, Elastic Stressing and Aseismic Slip III
Type: Oral
Date: 4/20/2021
Presentation Time: 03:00 PM Pacific
Description:
Seismic monitoring of waste-water injection, hydraulic fracturing, and other processes has increased across North America. With the increased injection concerns about induced seismicity have risen, and traffic-light systems (TLS) have become a model for managing the risk of shutting down operations. While locations and magnitudes are necessary input for these TLS, seismic monitoring can yield more products providing a detailed level of understanding of the geological and geomechanical setting of the array, allowing for proactive versus reactive reservoir management.
In this paper, I detail how the advanced products of a monitoring system -- high-precision locations, moment tensors, and stress inversions derived therefrom -- can be used to answer questions on the criticality of the faults, that gives insight into the triggering mechanisms. I look at an example in North America where sequences of large events have been detected over a number of hydraulic fracture completions. Large events, characterized by magnitude above ML2, are selected for moment tensor inversion. By selecting the moment tensors for events within 20km of a grid point, I obtain a relatively high-resolution stress map using a stochastic stress inversion (if at least 10 mechanisms are within that radius). Simultaneously, cross-correlation-based repicking and double difference relocation is used to define lineations associated with faults. By clustering the high-precision locations, these faults can be identified and imaged. Frequently, especially in strike-slip stress regimes in sedimentary basins, this workflow results in the first discovery of such faults as other geophysical means are not amenable. Finally,I assess how critically stressed these faults are in the moment-tensor determined stress regime by calculating the shear and normal stresses on these faults.
Presenting Author: Adam Baig
Student Presenter: No
Authors
Adam Baig Presenting Author Corresponding Author adambaig@nanometrics.ca Nanometrics |
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Insights on the Criticality of Faults From Dense Monitoring of Induced Seismicity from Moment Tensor Based Stress Inversion
Category
Mechanisms of Induced Seismicity: Pressure Diffusion, Elastic Stressing and Aseismic Slip