Role of injection location and injection pressure magnitude in modulating sequence of induced earthquakes and aseismic slip

Md Shumon Mia, Mohamed Abdelmeguid, & Ahmed E. Elbanna

Published August 15, 2021, SCEC Contribution #11446, 2021 SCEC Annual Meeting Poster #149

Mitigation of induced seismicity hazard continues to be a major challenge in several geo-energy applications including fossil fuel extraction, carbon sequestration and waste-water injection. A key to address this challenge is developing tools for modeling the full fault history of earthquakes and aseismic slip in response to pore pressure and poroelastic stress perturbations to understand the interplay among diverse spatio-temporal scales involved with friction, fluid diffusion, and stress transfer. In this study, simulation of earthquake cycles is carried out with evolving pore pressure for an anti-plane fault using a hybrid finite element-spectral boundary integral scheme (FEBE). We employ an alternating quasidynamic and fully dynamic scheme which enables simulating both interseismic deformation with approximation of inertia by radiation damping, and rapid seismic slip with full inertia effects. We consider a vertical fault embedded at depth within a linear elastic half-space and governed by a regularized rate and state friction law. Fluid is assumed to be injected directly to the fault core and pore pressure diffusion is determined analytically constraining it to the fault parallel direction.

We have investigated the effect of injection on seismicity pattern by varying injection location and injection pressure. In absence of injection, the fault generates periodic system spanning events. Pre-injection periodic pattern of seismicity is broken by injection leading to reduced inter seismic event time and accelerated slip accumulation. There is also a delay in recovery to the original pre-injection state after stopping injection. A period of seismic quiescence is observed after injection shut off, followed by a larger seismic event. We observe different seismicity pattern depending on whether the injection is in the velocity strengthening (VS) or the velocity weakening (VW) regions in the fault. Also, higher injection pressure is found to generate more frequent seismic events during injection and longer seismic quiescent time after injection shut-off. These observations are useful for addressing the risk of injection-induced seismicity.

Citation
Mia, M., Abdelmeguid, M., & Elbanna, A. E. (2021, 08). Role of injection location and injection pressure magnitude in modulating sequence of induced earthquakes and aseismic slip. Poster Presentation at 2021 SCEC Annual Meeting.

Related Projects & Working Groups
Fault and Rupture Mechanics (FARM)