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| Titel |
Stable isotope monitoring of ionic trapping of CO2 in deep brines |
| VerfasserIn |
A. Myrttinen, J. A. C. Barth, V. Becker, P. Blum, P. Grathwohl |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250021748
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| Zusammenfassung |
| CO2 injection into a depleted gas-reservoir is used as a combined method for Enhanced Gas
Recovery (EGR) and CO2 storage. In order to safeguard this process, monitoring the
degree of dissolution and potential further precipitation and mineral interactions are a
necessity. Here a method is introduced, in which stable isotope and geochemical
data can be used as a monitoring technique to quantify ionic trapping of injected
CO2.
Isotope and geochemical data of dissolved inorganic carbon (DIC) can be used to
distinguish between already present and to be injected inorganic carbon. Injected CO2, for
instance, is formed during combustion of former plant material and is expected to have a
different isotope ratio (δ13C value) than the baseline data of the aquifer. This is because
combusted CO2 originates from organic material, such as coal and oil with a predominant C3
plant signature. Mixing the injected CO2 with groundwater is therefore expected to change
the isotope, as well as the geochemical composition of the groundwater. Mass balance
calculations with stable isotope ratios can serve to quantify ionic trapping of CO2 as DIC in
groundwater.
However, depending on the composition of the aquifer, weathering of carbonate or
silicates may occur. Enhanced weathering processes due to CO2 injection can also further
influence the isotopic composition. Such interactions between dissolved CO2 and minerals
depend on the temperature and pressure regimes applied. Field data, as well as laboratory
experiments are planned to quantify isotope ratios of dissolved inorganic carbon as well as
oxygen isotope ratios of the water. These are indicative of geochemical processes
before, during and after EGR. The isotope method should therefore provide a new
tool to quantify the efficiency of ionic trapping under various temperatures and
pressures.
Keywords: Enhanced Gas Recovery, monitoring of CO2 dissolution, stable isotopes |
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