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| Titel |
Geochemical and microbial monitoring during CO2 storage in deep subsurface saline aquifers in Ketzin pilot site, Germany |
| VerfasserIn |
Hilke Würdemann, Daria Morozova, Maren Wandrey, Michael Zettlitzer |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250057942
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| Zusammenfassung |
| The development of strategies for sustainable and secure technologies to reduce substantially
emission of greenhouse gases to the atmosphere is one of the major challenges of the next
decades. Geological CO2 storage is a promising technology to reduce effectively
anthropogenic greenhouse gas emissions to the atmosphere. In the frames of the EU Project
CO2SINK a field laboratory was established to develop efficient monitoring procedures for
assessing the processes that are triggered by CO2injection into a saline aquifer (Würdemann
et al. 2010).
Our studies aim at monitoring of microbiological and geochemical processes and their
impact on the technical effectiveness of CO2 storage technique. Investigation on subsurface
saline aquifers has shown an active biosphere composed of diverse groups of microorganisms
in the subsurface. Since microorganisms represent very effective geochemical catalysts, they
may influence the process of CO2 storage significantly. The interactions between
microorganisms, the fluids and the minerals of both the reservoir and the cap rock may cause
changes to the structure and chemical composition of the rock formations, which may
influence the reservoir permeability locally. In addition, precipitation and corrosion may be
induced around the well affecting the casing and the casing cement. Therefore, analyses
of the composition of microbial communities and its changes should contribute
to an evaluation of the effectiveness and reliability of the long-term CO2 storage
technique.
This study comprises an interpretation of changes in the fluid chemistry and the
microbiology of laboratory experiments and downhole samples after CO2 exposure.
Although the saline aquifer could be characterised as an extreme habitat for microorganisms
due to reduced conditions, high pressure (62 to 78 bar) and salinity (235 g/l), a high number
of diverse groups of microorganisms were detected with downhole sampling in the injection
and observation wells at a depth of about 650m depth.
By using Fluorescence in situ Hybridisation (FISH) and molecular fingerprinting such as
Single-Strand-Conformation Polymorphism (SSCP) and Denaturing Gradient Gel
Electrophoresis (DGGE), we have shown that the microbial community was influenced
by the CO2 injection. Before CO2 arrival, up to 106 cells ml-1 were detected by
DAPI-staining of downhole samples. The microbial community was dominated by the
domain Bacteria, with Proteobacteria and Firmicutes as the most abundant phyla.
Representatives of the sulphate-reducing bacteria, extremophilic and fermenting bacteria
were identified. After CO2 injection, our study revealed temporal outcompetition of
sulphate-reducing bacteria by methanogenic archaea (Morozova et al. 2010a) and
increasing numbers of microorganisms after one year of CO2 exposure (Morozova et al.
2010b).
In order to investigate processes in the rock substrate long term CO2 exposure
experiments on freshly drilled, pristine Ketzin reservoir core samples were accomplished for
about three years months using sterile synthetic brine (181 g/l) under in situ pressure and
temperature conditions. The composition of the microbial community was dominated by
chemoorganotrophic bacteria and hydrogen oxidizing bacteria. The mineralogical changes
(dissolution of plagioclase, K-Feldspar and anhydrite, see Fischer et al., EGU 2011) are
consistent with changes in fluid composition during the course of the experiments that
indicate notably increased K+, Ca2+, Mg2+, and SO4 2- concentrations. K+, Ca2+, Mg2+
concentrations exceeded the reservoir brine composition significantly and can be
attributed to the CO2 exposure (Wandrey et al., 2011). The increase of SO4 2-
concentration can already be explained by equilibrium reactions between rock and synthetic
brine.
Fischer, S. et al. Mineralogical and petrophysical results of long-term CO2-exposure
experiments on reservoir sandstone from the Ketzin pilot site, Germany EGU General
Assembly 2011 ERE2.1
Morozova, D. et al. (2010a online first). "Monitoring of the microbial community
composition in saline aquifers during CO2 storage by fluorescence in situ hybridisation."
International Journal of Greenhouse Gas Control. doi: 10.1016/j.ijggc.2009.11.014.
Morozova, et al. (2010b). Monitoring of the microbial community composition in deep
subsurface saline aquifers during CO2 storage in Ketzin, Germany. Energy Procedia 10, in
press.Energy Procedia, GHGT-10, in press
Wandrey, et al. (2011). Monitoring petrophysical, mineralogical, geochemical and
microbiological effects of CO2 exposure – Results of long-term experiments under in situ
condition. Energy Procedia, GHGT-10, in press.
Würdemann, H. et al. (2010 online first). " CO2SINK – From Site Characterisation and
Risk Assessment to Monitoring and Verification: One Year of Operational Experience with
the Field Laboratory for CO2 Storage at Ketzin, Germany." International Journal of
Greenhouse Gas Control. doi:10.1016/j.ijggc.2010.08.010. |
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