EGU2020-5245
https://doi.org/10.5194/egusphere-egu2020-5245
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Large-Scale Migration Patterns of Wastewater-Induced Earthquakes in the Central U.S.

Lisa Johann and Serge A. Shapiro
Lisa Johann and Serge A. Shapiro
  • Freie Universität Berlin, Geophysics, Earth Sciences, Berlin, Germany (lisa.johann@geophysik.fu-berlin.de)

It is understood that the recent acceleration of seismic event occurrences in Kansas and Oklahoma, U.S., can be connected to the large-volume disposal of wastewater. These highly saline fluids are co-produced with oil and gas and are re-injected under gravity into the highly porous Arbuckle aquifer. Since 2015, injection rates have been decreasing. However, the seismic hazard in that region remains elevated. Furthermore, it has been noticed that some events in Kansas occur far from disposal wells.

To analyse spatio-temporal patterns between the fluid injection and earthquake locations, we applied a time-dependent 2D cross-correlation technique. This reveals a vectorial migration pattern of the seismic events. Whereas early events occur towards the east-sourtheast, later events are located preferably in northeastern direction of large volume injectors. With time, event locations migrate further in that direction. We explain this observation as well as measured Arbuckle pore pressures by a directional pore-fluid pressure diffusion and poroelastic stress propagation. This also follows from our principal two-dimension poroelastic finite element model which is of predictive power and identifies controlling parameters of the observations. These are mainly the permeability of the target injection formation and the seismogenic basement as well as the anisotropic permeability and the critical fault strength distribution. Our results lead to the conclusion that remote locations are destabilised also when injection rates are declining.

Thus, volume reductions may only provide a direct effect to lower earthquake rates locally. However, a state-wide decrease of the seismicity may require longer times such that the seismic hazard due to wastewater disposal induced seismicity may remain for decades. 

How to cite: Johann, L. and Shapiro, S. A.: Large-Scale Migration Patterns of Wastewater-Induced Earthquakes in the Central U.S., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5245, https://doi.org/10.5194/egusphere-egu2020-5245, 2020

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Presentation version 1 – uploaded on 30 Apr 2020
  • CC1: Comment on EGU2020-5245, Ryan Haagenson, 06 May 2020

    Thank you for sharing your work - I enjoyed reading over the presentation. I am curious what played a larger role in chagnes to FCS in your model: poroelastic stressing (i.e. delta-sigma_d and delta-sigma_m) or pore fluid perturbations (i.e. delta-p)? Also, do you have an idea of how using a 3D anisotropic poroelastic model instead of a 2D plane-strain model would alter your estimates of FCS? 

    Thank you again.

    • AC1: Reply to CC1, Lisa Johann, 06 May 2020

      Dear Ryan,

      thank you for your comment and your questions.

      Regarding the first one, it is delta-p which contributes most to delta-FCS. However, delta-p is dependent on the permeability of the seismogenic basement and the injection formation (Arbuckle). In turn, the magnitude of stress changes strongly depends on the poroelastic coupling parameter n_S (see e.g. Shapiro, 2015). 

      To your second question: That is indeed a really interesting question which should be part of future research. I guess that delta-FCS will be affected by a different model geometry. But again, magnitudes of delta-FCS might be strongly dependent on the permeability and in this case especially also the anisotropy. 

      Cheers, Lisa

      • CC2: Reply to AC1, Ryan Haagenson, 06 May 2020

        Thank you for your thoughtful response. I agree that it would be interesting to see how results would differ using a 3D anisotropic model. However, I suspect that the correlation between seismic activity and delta-FCS would still hold in some form, like you've said. 

        Thank you again for sharing your work.