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Pressure dynamics in carbon sequestration aquifers
Changing pressure dynamics during geologic CO2 injection for the typical range of values
of properties of the storage aquifer and overlying caprock may make earthquakes an
unlikely consequence of CO2sequestration, according to a study. The prospect of
sequestering CO2 in deep saline aquifers has raised concerns that injection of CO 2 could
increase fluid pressures and possibly trigger seismic activity that could release stored
CO2. Victor Vilarrasa and Jesus Carrera calculated how the stresses on storage aquifers
and overlying caprocks evolve during CO2 injection. The authors report that sedimentary
rocks, in which CO2would likely be stored, are softer than crystalline basement rocks and
are rarely under critical geologic stress. Further, pressure dynamics during CO2 injection
suggest that the least stable state of the aquifer may occur at the beginning of the
injection, making aquifer overpressures manageable. Overpressure will likely decrease
over time as CO2 dissolves into the aquifer brine due to its high solubility. Even if
CO2injection led to reactivation of faults, the high clay content typical of caprocks would
likely seal the fault zone. The results suggest that properly sited and managed geological
CO2 storage sites are unlikely to experience strong induced seismicity, a finding
consistent with the observed behavior of natural CO2reservoirs, according to the authors.
Article #14-13284: “Geologic carbon storage is unlikely to trigger large earthquakes and
reactivate faults through which CO2 could leak,” by Victor Vilarrasa and Jesus Carrera.
MEDIA CONTACTS: Victor Vilarrasa, Earth Sciences Department, Lawrence Berkeley
National Laboratory, CA; tel: +41 76 361 6190; e-mail: <victor.vilarrasa@upc.edu>; Jesus
Carrera, Institute of Environmental Assessment and Water Research, Spanish National
Research Council, Barcelona, SPAIN; tel: +34 690 05 8239; e-mail:
<jesus.carrera.ramirez@gmail.com>
An image accompanying this article is available.
http://www.eurekalert.org/jrnls/pnas/14-13284.htm