Injection‐Induced Seismic Moment Release and Laboratory Fault Slip: Implications for Fluid‐Induced Seismicity

Lei Wang,Erik Rybacki,Grzegorz Kwiatek,Marco Bohnhoff,Georg Dresen

doi:10.1029/2020gl089576

Abstract

AbstractUnderstanding the relation between injection‐induced seismic moment release and operational parameters is crucial for early identification of possible seismic hazards associated with fluid‐injection projects. We conducted laboratory fluid‐injection experiments on permeable sandstone samples containing a critically stressed fault at different fluid pressurization rates. The observed fluid‐induced fault deformation is dominantly aseismic. Fluid‐induced stick‐slip and fault creep reveal that total seismic moment release of acoustic emission (AE) events is related to total injected volume, independent of respective fault slip behavior. Seismic moment release rate of AE scales with measured fault slip velocity. For injection‐induced fault slip in a homogeneous pressurized region, released moment shows a linear scaling with injected volume for stable slip (steady slip and fault creep), while we find a cubic relation for dynamic slip. Our results highlight that monitoring evolution of seismic moment release with injected volume in some cases may assist in discriminating between stable slip and unstable runaway ruptures.

Highlights

It is widely acknowledged that fluid injection into the subsurface may induce earthquakes, as reported from waste‐water disposal operations (Keranen et al, 2014), hydraulic fracturing in shale formations (Ellsworth, 2013), or in enhanced geothermal system (EGS) projects (Bentz et al, 2020)
For injection‐induced fault slip in a homogeneous pressurized region, released moment shows a linear scaling with injected volume for stable slip, while we find a cubic relation for dynamic slip
It has been suggested that fluid injection into a shallow crustal fault zone (Bhattacharya & Viesca, 2019; De Barros et al, 2016) and during hydraulic fracturing operations (Eyre et al, 2019) may first activate aseismic slip leading to seismic ruptures that extend beyond the pressurized region

Summary

Introduction

It is widely acknowledged that fluid injection into the subsurface may induce earthquakes, as reported from waste‐water disposal operations (Keranen et al, 2014), hydraulic fracturing in shale formations (Ellsworth, 2013), or in enhanced geothermal system (EGS) projects (Bentz et al, 2020). Fluid injection causes seismicity by diffusion of a pore pressure pulse (Shapiro & Dinske, 2009; Shapiro et al, 2002) and through poroelastic coupling to the rock matrix (Goebel et al, 2016, 2017; Segall & Lu, 2015). Rupture propagation has been analyzed using fracture mechanics (Galis et al, 2017; Garagash & Germanovich, 2012; Wang et al, 2016), and the process has been modeled numerically using a rate‐ and state‐friction law (Cappa et al, 2018; Guglielmi et al, 2015).

Methods

Results

Discussion

Conclusion