| Title | A study on the largest hydraulic fracturing induced earthquake in Canada: numerical modeling and triggering mechanism |
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| Author | Wang, B; Verdecchia, A; Kao, H ; Harrington, R M; Liu, Y; Yu, H |
| Source | Bulletin of the Seismological Society of America 2021 p. 1-13, https://doi.org/10.1785/0120200251 |
| Image |  |
| Year | 2021 |
| Alt Series | Natural Resources Canada, Contribution Series 20200588 |
| Publisher | Seismological Society of America |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf; html |
| Province | British Columbia |
| NTS | 94B/16; 94G/01 |
| Lat/Long WENS | -122.3500 -122.0000 57.0500 56.8500 |
| Subjects | geophysics; fossil fuels; Economics and Industry; Health and Safety; Science and Technology; Nature and Environment; petroleum industry; hydrocarbon recovery; hydraulic fracturing; fluid migration;
seismology; seismicity; seismic risk; earthquake studies; earthquake risk; earthquakes; earthquake mechanisms; modelling; models; computer simulations; pore pressures; deformation; bedrock geology; structural features; faults; 17 August 2015 Mw 4.6
Earthquake |
| Illustrations | location maps; focal mechanisms; geoscientific sketch maps; seismograms; profiles; 3-D models; time series; bar graphs |
| Program | Environmental Geoscience Shale Gas - induced seismicity |
| Released | 2021 02 23 |
| Abstract | The Mw 4.6 earthquake that occurred on 17 August 2015 northwest of Fort St. John, British Columbia, is considered the largest hydraulic-fracturing-induced event in Canada, based on its spatiotemporal
relationship with respect to nearby injection operations. There is a ~5-day delay of this Mw 4.6 mainshock from the onset of fluid injection at the closest well pad (W1). In contrast, other two nearby injection wells (W2 and W3) have almost
instantaneous seismic responses. In this study, we first take a forward numerical approach to investigate the causative mechanisms for the Mw 4.6 event. Specifically, three finite-element 3D poroelastic models of various permeability structures and
presence or absence of hydraulic conduits are constructed, to calculate the coupled evolution of elastic stress and pore pressure caused by multistage fluid injections. Our simulation results suggest that pore pressure increase associated with the
migration of injected fluid is required to accumulate sufficient stress perturbations to trigger this Mw 4.6 earthquake. In contrast, the elastic stress perturbation caused by rock matrix deformation alone is not the main cause. Furthermore,
injection and seismicity at W1 may have altered the local stress field and brought local faults closer to failure at sites W2 and W3. This process could probably shorten the seismic response time and, thus, explain the observed simultaneous
appearance of injection and induced seismicity at W2 and W3. |
| Summary | (Plain Language Summary, not published)
The Mw 4.6 earthquake that occurred on 17 August 2015 northwest of Fort St. John, British Columbia, is considered the largest
hydraulic-fracturing-induced event in Canada based on its spatiotemporal relationship with respect to nearby injection operations. There is a ~5-day delay of this Mw 4.6 mainshock from the onset of fluid injection at the closest well pad. In
contrast, other two nearby injection wells have almost instantaneous seismic responses. In this study, we investigate the causative mechanisms for the Mw 4.6 event. Our simulation indicates that injections can alter the local stress field, but fluid
migration is probably the main physical process leading to sufficient pore-pressure increase and the Mw 4.6 event. |
| GEOSCAN ID | 327842 |
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