scholarly journals Coulomb Threshold Rate-and-State Model for Fault Reactivation: Application to induced seismicity at Groningen

2021 ◽  
Author(s):  
Elias Heimisson ◽  
Jonathan Smith ◽  
Jean-Philippe Avouac ◽  
Stephen Bourne
Keyword(s):  
Induced Seismicity ◽  
Fault Reactivation ◽  
State Model ◽  
Threshold Rate

scholarly journals Modelling fault reactivation with characteristic stress-drop terms

2019 ◽  
Vol 49 ◽  
pp. 1-7 ◽  
Author(s):  
Martin Beck ◽  
Holger Class
Keyword(s):  
Induced Seismicity ◽  
Shear Failure ◽  
Fault Reactivation ◽  
Mechanical Responses ◽  
Flow Processes ◽  
Failure Event ◽  
Characteristic Values ◽  
Shear Slip ◽  
Stress Drops ◽  
Characteristic Stress

Abstract. Predicting shear failure that leads to the reactivation of faults during the injection of fluids in the subsurface is difficult since it inherently involves an enormous complexity of flow processes interacting with geomechanics. However, understanding and predicting induced seismicity is of great importance. Various approaches to modelling shear failure have been suggested recently. They are all dependent on the prediction of the pressure and stress field, which requires the solution of partial differential equations for flow and for geomechanics. Given a pressure and corresponding mechanical responses, shear slip can be detected using a failure criterion. We propose using characteristic values for stress drops occurring in a failure event as sinks in the geomechanical equation. This approach is discussed in this article and illustrated with an example.

scholarly journals Induced seismicity in geologic carbon storage

Solid Earth ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 871-892 ◽  
Author(s):  
Víctor Vilarrasa ◽  
Jesus Carrera ◽  
Sebastià Olivella ◽  
Jonny Rutqvist ◽  
Lyesse Laloui
Keyword(s):  
Carbon Storage ◽  
Induced Seismicity ◽  
Public Perception ◽  
Fault Reactivation ◽  
Wellbore Stability ◽  
Rock Properties ◽  
Geologic Carbon Storage ◽  
Stress Changes ◽  
The Impact ◽  
Injection Formation

Abstract. Geologic carbon storage, as well as other geo-energy applications, such as geothermal energy, seasonal natural gas storage and subsurface energy storage imply fluid injection and/or extraction that causes changes in rock stress field and may induce (micro)seismicity. If felt, seismicity has a negative effect on public perception and may jeopardize wellbore stability and damage infrastructure. Thus, induced earthquakes should be minimized to successfully deploy geo-energies. However, numerous processes may trigger induced seismicity, which contribute to making it complex and translates into a limited forecast ability of current predictive models. We review the triggering mechanisms of induced seismicity. Specifically, we analyze (1) the impact of pore pressure evolution and the effect that properties of the injected fluid have on fracture and/or fault stability; (2) non-isothermal effects caused by the fact that the injected fluid usually reaches the injection formation at a lower temperature than that of the rock, inducing rock contraction, thermal stress reduction and stress redistribution around the cooled region; (3) local stress changes induced when low-permeability faults cross the injection formation, which may reduce their stability and eventually cause fault reactivation; (4) stress transfer caused by seismic or aseismic slip; and (5) geochemical effects, which may be especially relevant in carbonate-containing formations. We also review characterization techniques developed by the authors to reduce the uncertainty in rock properties and subsurface heterogeneity both for the screening of injection sites and for the operation of projects. Based on the review, we propose a methodology based on proper site characterization, monitoring and pressure management to minimize induced seismicity.

Numerical Modelling of Injection-induced Seismicity at Campi Flegrei Caldera, Southern Italy

2021 ◽  
Author(s):  
Waheed Gbenga Akande ◽  
Quan Gan ◽  
David G. Cornwell ◽  
Luca De Siena
Keyword(s):  
Numerical Modelling ◽  
Induced Seismicity ◽  
Southern Italy ◽  
Rock Physics ◽  
Critical Factor ◽  
Fault Reactivation ◽  
Hot Water ◽  
Campi Flegrei ◽  
Campi Flegrei Caldera ◽  
Seismic Swarms

<p>Modelling volcanic processes at active volcanoes often requires a multidisciplinary approach, which adequately describes the complex and ever-dynamic nature of volcanic unrests. Campi Flegrei caldera (southern Italy) is an ideal laboratory where numerical modelling of injection-induced seismicity could be tested to match the observed seismicity. In the current study, thermal-hydraulic-mechanical (THM) effects of hot-water (fluid) injections were investigated to ascertain whether the observed seismicity (past and ongoing seismic swarms) could be quantitatively reproduced and modelled in isothermal or non-isothermal approximations. Fluid-flow modelling was carried out using a coupled TOUGHREACT-FLAC<sup>3D</sup> approach to simulate THM effects of fluid injections in a capped reservoir, where the sealing formation serves as a geological interface between supercritical reservoir and fractured shallow layers of the caldera. Results from previous seismic, deformation, tomographic and rock physics studies were used to constrain the model for realistic volcano modelling. The results indicated that fluid injections generated overpressure beneath the caprock and subjected it to different stress regimes at its top and bottom, and this prompted deformation. Thus, caprock deformation, triggered by injection-induced basal compressional forces and top extensional fractures, is a critical factor determining the required timing for pressure build-up and fault reactivation, and magnitudes of seismicity. Higher fluid injection rates and temperature contrasts, heterogeneity due to fault and its contrast with the host rock, and caprock hydraulic properties were among the identified secondary factors modulating fault reactivation and seismicity. Simulation results revealed that seismicity can be better modelled in isothermal (HM) approximations. A comparative study of the THM-modelled seismicity and 4-month-long (August 5<sup>th</sup> to December 5<sup>th</sup>, 2019) seismic monitoring data recorded at the Osservatorio Vesuviano showed that our model reproduced the magnitudes and depths (~2.5 Ms within 2 km) at the onset of the ongoing unrests on October 5<sup>th</sup>, 2019. However, the model could not adequately reproduce the highest magnitude (3.3 Ms at 2.57 km) seismicity on April 26<sup>th</sup>, 2020 observed since 1984 major unrests.</p><p> </p>

scholarly journals Geologic carbon storage is unlikely to trigger large earthquakes and reactivate faults through which CO2 could leak

2015 ◽  
Vol 112 (19) ◽  
pp. 5938-5943 ◽  
Author(s):  
Victor Vilarrasa ◽  
Jesus Carrera
Keyword(s):  
Carbon Storage ◽  
Induced Seismicity ◽  
Clay Content ◽  
Fault Reactivation ◽  
Induced Earthquakes ◽  
Localized Deformation ◽  
Geologic Carbon Storage ◽  
Entry Pressure ◽  
Deep Underground ◽  
Large Earthquakes

Zoback and Gorelick [(2012) Proc Natl Acad Sci USA 109(26):10164–10168] have claimed that geologic carbon storage in deep saline formations is very likely to trigger large induced seismicity, which may damage the caprock and ruin the objective of keeping CO2 stored deep underground. We argue that felt induced earthquakes due to geologic CO2 storage are unlikely because (i) sedimentary formations, which are softer than the crystalline basement, are rarely critically stressed; (ii) the least stable situation occurs at the beginning of injection, which makes it easy to control; (iii) CO2 dissolution into brine may help in reducing overpressure; and (iv) CO2 will not flow across the caprock because of capillarity, but brine will, which will reduce overpressure further. The latter two mechanisms ensure that overpressures caused by CO2 injection will dissipate in a moderate time after injection stops, hindering the occurrence of postinjection induced seismicity. Furthermore, even if microseismicity were induced, CO2 leakage through fault reactivation would be unlikely because the high clay content of caprocks ensures a reduced permeability and increased entry pressure along the localized deformation zone. For these reasons, we contend that properly sited and managed geologic carbon storage in deep saline formations remains a safe option to mitigate anthropogenic climate change.

scholarly journals Mathematical Modelling of Fault Reactivation Induced by Water Injection

Minerals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 282 ◽  
Author(s):  
Thanh Son Nguyen ◽  
Yves Guglielmi ◽  
Bastian Graupner ◽  
Jonny Rutqvist
Keyword(s):  
Induced Seismicity ◽  
Water Injection ◽  
In Situ Stress ◽  
Fault Reactivation ◽  
Shear Strength Parameters ◽  
Radionuclide Migration ◽  
Strength Parameters ◽  
Mont Terri ◽  
Underground Research Laboratory

Faults in the host rock that might exist in the vicinity of deep geological repositories for radioactive waste, constitute potential enhanced pathways for radionuclide migration. Several processes might trigger pore pressure increases in the faults leading to fault failure and induced seismicity, and increase the faults’ permeability. In this research, we developed a mathematical model to simulate fault activation during an experiment of controlled water injection in a fault at the Mont-Terri Underground Research Laboratory in Switzerland. The effects of in-situ stress, fault shear strength parameters and heterogeneity are assessed. It was shown that the above factors are critical and need to be adequately characterized in order to predict the faults’ hydro-mechanical behaviour.

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