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| Titel |
Gas monitoring during the CO2 back production field test at the Ketzin pilot site |
| VerfasserIn |
Alexandra Szizybalski, Martin Zimmer, Christian Kujawa, Jörg Erzinger |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250106037
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| Publikation (Nr.) |
 EGU/EGU2015-5673.pdf |
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| Zusammenfassung |
| The GFZ German Research Centre for Geosciences operates Europe’s first on-shore CO2
storage site in Ketzin, a small town near Berlin. From June 2008 until August 2013
about 67 kt of CO2 were injected into Upper Triassic sandstones in 630 to 650 m
depth.
The injection phase ended with an experiment to evaluate the influence of additives on
CO2 storage. During this experiment 32Ât N2 and 613Ât CO2 were co-injected into the
borehole over a period of 25 days followed by the final injection of 66Ât pure CO2. At the
beginning of the experiment 10,000 l (10 Nm3) Kr were pumped into the borehole, to
separate the previous pure CO2 and the CO2-N2 mixture. For the same reason, CO2 with a
different isotopic composition (δ13C = -3.4±0.2‰ instead of δ13CÂ=Â-30.6±0.4) was used
for the first 548 t of the total 613Ât.
To demonstrate that the stored CO2 is retrievable a field test was carried out in October
2014 during a period of two weeks. Of interest, in this context, is the composition of the
back-produced gas which delivers key information on possible interactions between the CO2,
formation fluid and rocks.
In total 240 t of gas were produced via the former injection well. The flow rates ranged
between 800 and 3,200 kg gas/h. The gas was sampled after the gas/water separator
and continuously analysed using a mass spectrometer, a gas chromatograph and
a photoacoustic sensor, thus covering all gas components and concentrations. In
addition, gas samples were collected for stable carbon isotopes investigations in the
laboratory.
Preliminary results show that the produced gas consists of > 97% CO2 plus mainly N2.
The N2 was detected from the beginning, although the injection in 2013 ended with pure
CO2. The N2 concentration decreased from about 3% to 1% during the two weeks of
the experiment. In addition to these major components CH4, CO and H2 (up to
0.01%) as well as Kr and SF6 (up to 0.001%, both were used as tracers in 2013) were
detected.
The gas composition of natural fluids before the injection of CO2 showed that CH4, CO2,
H2 and N2 are present in the original formation fluid (0.17 mg/l, 0.08 mg/l, 0.14 mg/l, 17.9
mg/l fluid; Morozova et al., 2010).
The observed N2 concentrations in the back-produced gas may, therefore, result
from the field tests and from injection management or from the original formation
fluid.
Results of the isotopic measurements are in preparation.
Morozova, D., Wandrey, M., Alawi, M., Zimmer, M., Vieth, A., Zettlitzer, M.,
Wuerdemann, H. (2010): Monitoring of the microbial community composition in saline
aquifers during CO2 storage by fluorescence in situ hybridisation. International Journal of
Greenhouse Gas Control, Volume 4, Pages 981-989. doi:10.1016/j.ijggc.2009.11.014. |
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