Abstract: Fault instability in response to subsurface wastewater injection is controlled by various operation- and site-dependent parameters. Previous numerical approaches focus on the prediction of the onset of fault reactivation, whereas the subsequent stress redistribution and fault movement are not considered. To better understand the potential correlation between injection activities and fault instability, we develop a hydro-mechanical coupled finite element model and use the May 2012 Timpson earthquake sequence as a case study. Cohesive zone model integrating hyperbolic damage criterion and weakening behaviors is assigned to element interface to represent the nearby fault and capture the resulting fault behaviors under fluid injection. Simulation results indicate that this model is able to reveal the spatiotemporal evolution of pore pressure and geomechanical stress field at the Timpson site. Under continual fluid injection, pore pressure increases and gradually stabilizes, more evident in regions close to the injection layer. Poroelastic stress and pore pressure changes jointly influence the fault stability. Through damage evolution considered in the cohesive zone model, the finite element model can simulate the foreshock and main shock of the Timpson earthquake sequence, associated with fault displacement and stress relaxation. Once the damage criterion is reached, the stress redistribution at the failed fault segment induces further increase of stress on the other domains of the fault, which drives subsequent fault slip. This study brings new insights into the numerical modeling of induced earthquakes and highlights the importance of accounting for fluid injection activities to minimize the potential of fault reactivation and slip. Article Highlights: Hydro-mechanical model simulates pore pressure perturbation under varying injection duration, injection rate, and formation permeability.Progressive damage in cohesive zone elements reflects the effects of stress redistribution on fault reactivation and slip.The triggering of fault instability in Timpson is associated with sudden damage propagation and stress relaxations.
|Original language||English (US)|
|Journal||Geomechanics and Geophysics for Geo-Energy and Geo-Resources|
|State||Published - Aug 2021|
All Science Journal Classification (ASJC) codes
- Geotechnical Engineering and Engineering Geology
- Economic Geology