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| Titel |
Experimental investigation of CO2-brine-rock interactions at simulated
\textit{in-situ} conditions |
| VerfasserIn |
Piotr Słomski, Marcin Lutyński, Maria Mastalerz, Jacek Szczepański, Arkadiusz Derkowski, Tomasz Topór |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250146352
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| Publikation (Nr.) |
 EGU/EGU2017-10375.pdf |
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| Zusammenfassung |
| Geological sequestration of carbon dioxide (CO2) in deep formations (e.g. saline aquifers, oil
and gas reservoirs and coalbeds) is one of the most promising options for reducing
concentration of this anthropogenic greenhouse gas in the atmosphere. CO2 injected into the
rock formations can be trapped by several mechanisms including structural and stratigraphic
trapping, capillary CO2 trapping, dissolution trapping and mineral trapping. During
dissolution trapping, CO2 dissolves in the formation brine and sinks in the reservoir as the
CO2-enriched brine has an increased density. In comparison, in mineral trapping, CO2 is
bound by precipitating new carbonate minerals. The latter two mechanisms depend on the
temperature, pressure, and the mineralogy of the reservoir rock and the chemical composition
of the brine.
This study discusses laboratory scale alterations of Ordovician and Silurian shale rocks
from potential CO2 sequestration site B1 in the Baltic Basin. In the reported experiment,
rocks submerged in brine in specially constructed reactors were subjected to CO2 pressure of
30-35 MPa for 30-45 days at temperature of 80 oC. Shale samples were analyzed in terms of
mineral composition and mesopore surface area and volume, before and after experiments, by
means of X-ray diffraction and N2 low-pressure adsorption, respectively, for possible CO2
induced changes. Comparison of mineral composition before and after experiments
demonstrated subtle mineral changes. The most conspicuous was a release of Fe
in the form of Fe-oxyhydroxides, most probably related to the decomposition of
Fe-bearing minerals like pyrite, chlorite and, less frequently, ankerite. With regard
to porosity, interestingly, the most significant increase in mesopore surface area
and mesopore volume was observed in samples with the largest drop of chlorite
amount. The less significant mineral changes were associated with formation of
kaolinite related to breakdown of feldspars and dissolution of carbonate minerals
represented by calcite, dolomite, and ankerite. In the analyzed samples, no new
carbonate minerals were formed during the experiments. An increase of carbonates was
recorded only in three out of 13 samples. However, concentration of carbonates in
these three samples is too low to conclude CO2 mineral trapping in new carbonate
phases.
Acknowledgments: the study was supported from grant SHALESEQ (No PL12-0109)
funded by the National Centre for Research and Development. |
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