| Title | Spatiotemporal changes in seismic velocity associated with hydraulic fracturing-induced earthquakes near Fox Creek, Alberta, Canada |
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| Author | Ojo, A O ; Kao,
H; Visser, R; Goerzen, C |
| Source | Journal of Petroleum Science & Engineering vol. 208, pt. A, 109390, 2021 p. 1-9, https://doi.org/10.1016/j.petrol.2021.109390  Open Access |
| Image |  |
| Year | 2021 |
| Alt Series | Natural Resources Canada, Contribution Series 20210223 |
| Publisher | Elsevier |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf; html |
| Province | Alberta |
| NTS | 83K/06 |
| Area | Fox Creek |
| Lat/Long WENS | -117.3000 -117.1750 54.3800 54.3000 |
| Subjects | geophysics; fossil fuels; Economics and Industry; Science and Technology; Nature and Environment; petroleum industry; hydrocarbon recovery; hydraulic fracturing; wells; seismology; seismicity; seismic
risk; earthquakes; earthquake risk; seismic velocities; seismological network; seismic arrays; deformation; pore pressures; reservoir rocks; bedrock geology; basement geology; Western Canadian Sedimentary Basin; Wabamun Formation; Ireton Formation;
Beaverhill Lake Formation |
| Illustrations | location maps; plots; geoscientific sketch maps; time series; profiles; bar graphs |
| Program | Environmental Geoscience Shale Gas - induced seismicity |
| Released | 2021 08 17 |
| Abstract | To characterize the subsurface geomechanical response to hydraulic fracturing (HF) activities, we study the spatiotemporal changes of seismic velocity during the completion of four HF wells in the Fox
Creek area, Alberta, Canada. We estimate temporal velocity changes (dv/v) from ambient seismic noise recorded during the Tony Creek Dual Microseismic Experiment (ToC2ME) by comparing a 5-day stacked noise correlation function with a reference noise
correlation function stacked over the deployment period. In the frequency band (0.1-0.4 Hz) most sensitive to the injection depths (~3.4 km), we observe daily dv/v that revealed alternating gradual velocity decreases and increases with magnitudes in
the range of ±0.9%. We found a strong temporal correlation between the onset of velocity decreases and periods of intense seismicity, suggesting that the observed dv/v reductions are likely caused by stress-induced subsurface deformation due to
elevated pore pressures, increased crack density, and ground shaking. A period of dv/v increase observed between the beginning and end of different well stimulation is attributed to crustal healing. Comparing the dv/v time series with injection
parameters, we observed a 272.66% increase in induced seismicity and 50% more reduction in dv/v during the second injection phase that are correlated with 90.53%, 169.64%, and 4.34% increase in the injection volume, rate, and pressure, respectively.
Our study provides valuable new information on the changes in reservoir elastic properties within the Western Canadian Sedimentary Basin. It also demonstrates that coda wave interferometry using data from dense seismic arrays near injection sites can
be an additional tool for monitoring hydraulic fracturing operations. |
| Summary | (Plain Language Summary, not published)
We study the spatiotemporal changes of seismic velocity during the completion of four hydraulic fracturing (HF) operations in the Fox Creek area,
Alberta, Canada. Temporal velocity changes (dv/v) are estimated from ambient seismic noise recorded by a dense local seismograph array. We observe daily dv/v that revealed alternating gradual velocity decreases and increases with magnitudes in the
range of ±0.9%. We found a strong temporal correlation between the onset of velocity decreases and periods of intense seismicity, suggesting that the observed dv/v reductions are likely caused by stress-induced subsurface deformation due to elevated
pore pressures, increased crack density, and ground shaking. A period of dv/v increase observed between the beginning and end of different well stimulation is attributed to crustal healing. Our study provides valuable new information on the changes
in reservoir elastic properties within the Western Canadian Sedimentary Basin. It also demonstrates that coda wave interferometry using data from dense seismic arrays near injection sites can be an additional tool for monitoring hydraulic fracturing
operations. |
| GEOSCAN ID | 328817 |
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