Diagnostic and predictive analysis of production and injection‐induced fault activation

Abstract

Mitigating the hazard of fault reactivation during CO2$_2$ injection and oil production is important for ensuring environmental sustainability of geologic carbon sequestration and hydrocarbon recovery. Currently, we do not know how the Coulomb Failure Stress (CFS), which is a commonly used metric to assess the potential of inducing slip on a fault, evolves differently for gas injection and oil production scenarios. Using high‐resolution simulations of CO2$_2$ injection‐induced and oil production‐induced fault slip and theories of Coulomb failure and poroelasticity, we address this gap in knowledge. We analyze the fault tractions, slip, and reservoir pressure to understand how a fault is destabilized in successive steps, how hypocenter locations are selected, and how these processes differ between injection and production. We extract and summarize the characteristic features of induced fault activation in terms of the dependence of CFS and the Fault Stress Ratio (FSR) on the dimensionless reservoir pressure perturbation caused by injection or production. We apply the framework to the Farnsworth oilfield in Texas, which is undergoing CO2$_2$ injection and oil production, to disambiguate observations related to fault stability. Finally, we discuss how our framework can inform models that aim to forecast fluid flow‐induced slip and mitigate the induced seismicity hazard in oilfields and gas storage sites.

A coupled finite difference‐spectral boundary integral method with applications to fluid diffusion in fault structures

“…The migration of fluids in geological systems containing fractures/faults has drawn much attention during past decades due to its crucial role in the development and utilization of various applications in fluid injection activities. [1][2][3] In recent years, there is a significant interest in flow in permeable fault structures in geomechanics as such structures play an important role in fault reactivation induced by CO 2 injection Zhao and Jha, 4 the subsurface fluid leakage quantification Meguerdijian and Jha 5 and fault rupture dynamics Liu and Borja. 6 Due to the large-scale properties of geological systems, heterogeneity, and apparatus limitations, it is challenging to observe the fluid propagation along rock structures in the field.…”