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Fluid Injection Induced Seismic and Aseismic Slip From a Coupled Poroelastic Stress Change and Rate-State Fault Model

Description: 

Fluid injection in unconventional hydrocarbon resource exploration can introduce poroelastic stress and pore pressure changes, which in some cases may lead to aseismic or seismic slip on pre-existing fractures or faults. In this study, we examine the relative roles of the above processes in triggering earthquakes by coupling poroelastic stress changes with the rate-state friction framework to simulate slip evolution on a pre-existing fault under stress perturbations.

Assuming an injection source of constant rate and finite period at depth, a receiver fault at distance experiences an initial clamping phase (effective normal stress increase) followed by unclamping (effective normal stress decrease) resulting from fluid diffusion. We then introduce the stress perturbation, including pore pressure, normal and shear stresses, onto a fault governed by rate-state friction, and characterize fault response by the maximum rate and timing of the triggered slip event. Our preliminary results show that higher-amplitude perturbations generally trigger events with higher slip rates and earlier occurrences with respect to the unperturbed reference slip cycle. However, seismic slip rate is always reached when the receiver fault is in the unclamping phase, suggesting the importance of pore pressure increase in destabilizing faults. Stress perturbations (tested up to 30% of background normal stress) introduced early or late in the reference cycle result in aseismic slip; only those introduced in the middle of the cycle can trigger seismic slip, which may reflect the interaction between the timescales of stress perturbation and fault frictional processes. Finally, the receiver fault with a larger influenced area can develop into a seismic event, whereas the fault with smaller influenced areas may remain aseismic despite increasing perturbation amplitudes. Our modeling results suggest optimal design of injection parameters could be critical for preventing the onset of seismic slip.

Session: Understanding and Managing Induced Seismicity

Type: Oral

Date: 4/19/2023

Presentation Time: 02:00 PM (local time)

Presenting Author: Yajing Liu

Student Presenter: No

Invited Presentation: Yes

Authors