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| Titel |
An alternative to fully coupled reactive transport simulations for long-term prediction of chemical reactions in complex geological systems |
| VerfasserIn |
Marco De Lucia, Thomas Kempka, Michael Kühn |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250100433
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| Publikation (Nr.) |
 EGU/EGU2014-16398.pdf |
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| Zusammenfassung |
| Fully-coupled reactive transport simulations involving multiphase hydrodynamics and
chemical reactions in heterogeneous settings are extremely challenging from a computational
point of view. This often leads to oversimplification of the investigated system: coarse spatial
discretization, to keep the number of elements in the order of few thousands; simplified
chemistry, disregarding many potentially important reactions. A novel approach
for coupling non-reactive hydrodynamic simulations with the outcome of single
batch geochemical simulations was therefore introduced to assess the potential
long-term mineral trapping at the Ketzin pilot site for underground CO2 storage in
Germany [1],[2]. The advantage of the coupling is the ability to use multi-million grid
non-reactive hydrodynamics simulations on one side and few batch 0D geochemical
simulations on the other, so that the complexity of both systems does not need to be
reduced.
This contribution shows the approach which was taken to validate this simplified coupling
scheme. The procedure involved batch simulations of the reference geochemical model, then
performing both non-reactive and fully coupled 1D and 3D reactive transport simulations
and finally applying the simplified coupling scheme based on the non-reactive and
geochemical batch model. The TOUGHREACT/ECO2N [3] simulator was adopted
for the validation. The degree of refinement of the spatial grid and the complexity
and velocity of the mineral reactions, along with a cut-off value for the minimum
concentration of dissolved CO2 allowed to originate precipitates in the simplified
approach were found out to be the governing parameters for the convergence of the two
schemes. Systematic discrepancies between the approaches are not reducible, simply
because there is no feedback between chemistry and hydrodynamics, and can reach 20
% - 30 % in unfavourable cases. However, even such discrepancy is completely
acceptable, in our opinion, given the amount of uncertainty underlying the geochemical
models.
References
[1] Klein, E., De Lucia, M., Kempka, T. Kühn, M. 2013. Evaluation of longterm mineral
trapping at the Ketzin pilot site for CO2 storage: an integrative approach using geochemical
modelling and reservoir simulation. International Journal of Greenhouse Gas Control 19:
720-730, doi:10.1016/j.ijggc.2013.05.014
[2] Kempka, T., Klein, E., De Lucia, M., Tillner, E. Kühn, M. 2013. Assessment of
Long-term CO2 Trapping Mechanisms at the Ketzin Pilot Site (Germany) by Coupled
Numerical Modelling. Energy Procedia 37: 5419-5426, doi:10.1016/j.egypro.2013.06.460
[3] Xu, T., Spycher, N., Sonnenthal, E., Zhang, G., Zheng, L., Pruess, K. 2010.
TOUGHREACT Version 2.0: A simulator for subsurface reactive transport under
non-isothermal multiphase flow conditions, Computers & Geosciences 37(6),
doi:10.1016/j.cageo.2010.10.007 |
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