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| Titel |
The CO2 Vadose Project - Buffering capacity of a carbonate vadose zone on induced CO2 leakage. Part 1: monitoring in a natural pilot experimental field |
| VerfasserIn |
Grégory Cohen, Corinne Loisy, Olivier Le Roux, Bruno Garcia, Virgile Rouchon, Philippe Delaplace, Adrian Cerepi |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250078685
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| Zusammenfassung |
| The Intergovernmental Panel on Climate Change Special Report on Carbon Capture and
Storage identified various knowledge gaps that need to be resolved before the large-scale
implementation of CO2 geological storage to become possible. One of them is to determine
what would be the impact of a CO2 leakage from a geological storage on vadose zone and
near surface environment.
The CO2-Vadose project aims at i) understanding the behavior of CO2 in the near surface
carbonate environment during an induced CO2 leakage, ii) assessing numerical simulations
associated with CO2 release experiments and iii) developing integrated field methodologies to
detect and quantify a potential CO2 leakage. A gas mixture of CO2 and tracers (He and
Kr) was released in a cavity (9 m3, 7 m deep) located in an abandoned limestone
quarry in Gironde (France). More than forty gas probes were set up (in the near
surface and all around the cavity in limestone) for following CO2 concentrations
before, during and after injection thanks to micro-GC and Li-Cor analyzers. The
meteorological parameters were recorded at the site surface as well as around the injection
room. Experimental observations of variations of electrical resistivity were also
carried out in order to investigate the evolution of limestone geophysical property
in response to possible leakages of geologically sequestered CO2. The dynamic
evolution of electrical resistivity was measured thanks to time-lapse electrical resistivity
tomography.
Natural ground and limestone CO2 concentrations were monitored during a year before CO2
injection. Natural CO2 concentrations variations were observed in order to plot a natural
baseline and so to determine the best period for the injection and to distinguish biogenic
from injected CO2. These concentrations varied between about 400 ppm to more
than 20,000 ppm, following cycles of about six weeks. Initial electrical resistivity
tomography was also carried out just before the injection in order to have reference values
and to characterize the heterogeneity of the limestone massif around the injection
room.
The diffusion of CO2 was followed thanks to CO2 gas concentration measurements and
resistive tomography. The numerical simulations done with COORES-¢ code were in good
agreement with experimental results near the source. The results of this study show that CO2
subsurface leakage can be anticipated thanks to inert gases used as tracers, like He and Kr. As
part of a monitoring plan, the detection of noble gas increase could lead to the surveillance of
the monitored area with accuracy, permitting to discriminate leakage CO2 from natural
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