Induced Earthquake Forecasting in Oklahoma Using Models of Fluid Diffusion and Earthquake Nucleation

Guang Zhai, & Manoochehr Shirzaei

Submitted August 14, 2018, SCEC Contribution #8511, 2018 SCEC Annual Meeting Poster #035

There is a growing body of evidence suggesting that the recent 900-fold increase in the number of earthquakes in the eastern and central USA is linked to deep waste fluid disposal, co-produced with oil and gas productions. The current efforts to evaluate and mitigate induced seismic hazard are often informed by the empirical relation established between seismic response and injection volume and rates. Therefore, it is not a surprise that such efforts yield a limited success, as the empirical relations do not capture the entire physics governing processes of induced earthquake due to fluid injection. To this end, we devise a physics-based forecasting scheme considering the underlying process governing fluid diffusion and a rate-and-state earthquake nucleation model. This method evaluates the changes in the crustal stress and seismicity due to fluid diffusion, which, in combination with a statistical framework, can be used for assessment of induced earthquake hazard. Here, we investigate the seismic, hydrogeologic, and injection data spanning the period of 1995 – 2017 in northern-central Oklahoma. The magnitude-time distribution of the observed M3+ earthquakes for the period of 2008 – 2017 is accurately reproducible. In response to injection rate reduction in 2016, Western Oklahoma shows larger decrease in the earthquake magnitude exceedance probability than that of Central Oklahoma, primarily due to faster fluid diffusion rate and larger injection reduction in Western Oklahoma. Our model predicts that the earthquake probability will approach to its historical background level by 2025 at both Central and Western Oklahoma after a hypothetical injection shut-in in April 2017, highlighting the importance of the time-dependent nature of fluid diffusion in understanding induced seismic hazard. Also, this information is of great importance for regulation agency to minimize fluid injection induced seismic hazard through designing various injection scenarios. In conclusion, an effective induced earthquake forecasting effort requires accounting for the physics of fluid diffusion and earthquake nucleation. Employing such physics-based models for assessing time-dependent induced earthquake hazard are useful with extensive potential for operational induced earthquake forecasting.

Key Words
Induced Seismicity; Fluid Injection; Poroelasticity; Seismicity Rate

Citation
Zhai, G., & Shirzaei, M. (2018, 08). Induced Earthquake Forecasting in Oklahoma Using Models of Fluid Diffusion and Earthquake Nucleation. Poster Presentation at 2018 SCEC Annual Meeting.


Related Projects & Working Groups
Earthquake Forecasting and Predictability (EFP)