Geologic carbon storage is unlikely to trigger large earthquakes and reactivate faults through which CO<inf>2</inf> could leak
© 2015, National Academy of Sciences. All rights reserved. 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 CO<inf>2</inf> stored deep underground. We argue that felt induced earthquakes due to geologic CO<inf>2</inf> 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) CO<inf>2</inf> dissolution into brine may help in reducing overpressure; and (iv) CO<inf>2</inf> 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 CO<inf>2</inf> injection will dissipate in a moderate time after injection stops, hindering the occurrence of postinjection induced seismicity. Furthermore, even if microseismicity were induced, CO<inf>2</inf> 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.
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| Format: | artículo biblioteca |
| Published: |
2015
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| Online Access: | http://hdl.handle.net/10261/218675 |
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