Victor Vilarrasa

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

Significance Geologic carbon storage remains a safe option to mitigate anthropogenic climate change. Properly sited and managed storage sites are unlikely to induce felt seismicity 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 will dissolve into brine at a significant rate, reducing overpressure; and (iv) CO2 will not flow across the caprock because of capillarity, but brine will, which will reduce overpressure further. Furthermore, CO2 leakage through fault reactivation is unlikely because the high clay content of caprocks ensures a reduced permeability and increased entry pressure along localized deformation zones. 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.

Semianalytical Solution for CO2 Plume Shape and Pressure Evolution During CO2 Injection in Deep Saline Formations

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Use of a dual-structure constitutive model for predicting the long-term behavior of an expansive clay buffer in a nuclear waste repository

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Strength Evolution of Geomaterials in the Octahedral Plane under Nonisothermal and Unsaturated Conditions

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GEOLOGICAL STORAGE OF CO2 IN DEEP SALINE FORMATIONS

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Dissolved CO2 Injection to Eliminate the Risk of CO2 Leakage in Geologic Carbon Storage

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