EGU2020-22047
https://doi.org/10.5194/egusphere-egu2020-22047
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Statistical mechanics-based forecasting of induced seismicity within the Groningen gas field

Stephen Bourne and Steve Oates
Stephen Bourne and Steve Oates
  • Shell Global Solutions International, Projects & Technology, Netherlands (stephen.bourne@shell.com)

Geological faults may fail and produce earthquakes due to external stresses induced by hydrocarbon recovery, geothermal extraction, CO2 storage or subsurface energy storage. The associated hazard and risk critically depend on the spatiotemporal and size distribution of any induced seismicity. The observed statistics of induced seismicity within the Groningen gas field evolve as non-linear functions of the poroelastic stresses generated by pore pressure depletion since 1965. The rate of earthquake initiation per unit stress has systematically increased as an exponential-like function of cumulative incremental stress over at least the last 25 years of gas production. The expected size of these earthquakes also increased in a manner consistent with a stress-dependent tapering of the seismic moment power-law distribution. Aftershocks of these induced earthquakes are also observed, although evidence for any stress-dependent aftershock productivity or spatiotemporal clustering is inconclusive.

These observations are consistent with the reactivation of a mechanically disordered fault system characterized by a large, stochastic prestress distribution. If this prestress variability significantly exceeds the induced stress loads, as well as the earthquake stress drops, then the space-time-size distribution of induced earthquakes may be described by mean field theories within statistical fracture mechanics. A probabilistic seismological model based on these theories matches the history of induced seismicity within the Groningen region and correctly forecasts the seismicity response to reduced gas production rates designed to lower the associated seismic hazard and risk.

How to cite: Bourne, S. and Oates, S.: Statistical mechanics-based forecasting of induced seismicity within the Groningen gas field, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22047, https://doi.org/10.5194/egusphere-egu2020-22047, 2020

Comments on the presentation

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Presentation version 1 – uploaded on 01 May 2020
  • CC1: Comment on EGU2020-22047, Angela Stallone, 04 May 2020

    Have you considered different functional forms for stress dependence? If yes, how do they affect your conclusions?

    • AC1: Reply to CC1, Stephen Bourne, 06 May 2020

      Yes. The stress-dependent taper was modelled as either a critical-point inverse power-law or an exponential. The stress-dependent b-value was modelled as either an inverse power-law or a hyperbolic tangent. In both cases the posterior predictive performance was not significantly affected by these alternative parameterizations of the stress-dependence.

      • CC4: Reply to AC1, Angela Stallone, 09 May 2020

        Thank you Stephen

  • CC2: Comment on EGU2020-22047, Jordi Baro, 04 May 2020

    dear Stephen Bourne,
    Again, thanks for your presentation, this work looks really interesting.

    Both the relevance of the cutoff and its dependence in stress is something we predicted in our model, but we are short on empirical evidences.
    Do you have a more extensive report published or openly available? is there anything in a 'citable' state?

    • AC2: Reply to CC2, Stephen Bourne, 06 May 2020

      Thanks. A stress-dependent taper is a common feature for failure size distributions in many different damage models, so it would be interesting to see how your model fits into this landscape and also how it predicts the observed Groningen earthquake magnitudes. We have an open access ESSOAr preprint of our work available at .

      • CC3: Reply to AC2, Jordi Baro, 06 May 2020

        Thank you,

        This is the link: https://www.essoar.org/pdfjs/10.1002/essoar.10502910.1 (hyperlinks don't work here for some reason).

        I especially liked the review on the micromechanical models. It is extensive and really needed. Just as a minor comment, not a critique: I personally think that the hierarchy shown in figure 7 is a little confusing.