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| Titel |
Multiphysics in time and space for the simulation of CO2 storage in deep saline aquifers |
| VerfasserIn |
Melanie Darcis, Holger Class, Bernd Flemisch, Rainer Helmig |
| 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 |
250054312
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| Zusammenfassung |
| One of the currently investigated options to mitigate greenhouse gas emissions is Carbon
Capture and Storage (CCS). A crucial step for the application of this technology is finding
suitable and safe storage sites. Apart from the constraint of technical and economical
feasibility, the CO2 storage project needs to gain public acceptance. Comprehensive site
investigations and a reliable risk assessment are therefore key points for the realisation of a
CO2 storage project. To meet these requirements detailed numerical simulations are
essential.
Numerical simulations that accompany a CO2 storage project need to cover the whole
complexity of relevant physical processes. Apart from nonisothermal multiphase flow and
transport processes, geomechanical and geochemical processes might need to be taken into
account. Moreover, large scale effects like regional pressure build up and induced brine
migration might play a role. Finally, the long-term fate of the CO2 plume and the
ultimate trapping of the injected CO2 need to be determined. Tools that are capable
of describing the whole complexity of relevant physical and chemical processes
are rare and the required temporal and spatial scales lead to high computational
costs.
One way to increase model capability and efficiency is to couple models of
different complexity. On the one hand, model coupling can be applied to include the
description of processes that are not covered by a standard multiphase flow and
transport simulator. On the other hand, coupling models of different complexity
increases model efficiency since it allows to apply the models according to the
temporal and spatial changes of dominating physical processes, instead of using
a full complexity model for the whole simulation time and for the entire model
domain.
Here the focus lies on model coupling as a measure to increase model efficiency. Two
types of model coupling will be presented, namely, sequential model coupling (multiphysics
in time) and spatial model coupling (multiphysics in space).
An example for multiphysics in time is the application of a nonisothermal two-phase
model that neglects compositional processes during the injection period and the switch to a
nonisothermal two-phase, two-component model in the post injection period. The
application of the model with reduced complexity on the short timescale is motivated by
the fact that during the injection period nonisothermal, advection and buoyancy
driven processes dominate, while compositional processes like CO2 dissolution
and diffusion gain importance in the post-injection period. Another application
for sequential model coupling, which will also be presented, is the switch to an
isothermal model on the large timescale, when nonisothermal effects do not play a
role anymore. Multiphysics in space means that the model domain is split up into
two or more subdomains, where different models are applied. Thus, a subdomain
close to the injection well, where the pressure build up reaches a certain threshold
value and geomechanical processes might play a role, can be coupled to a second
subdomain farther away from the injection well, where only two-phase or even
single-phase flow and transport processes (brine migration) need to be taken into
account.
For an efficient application of these coupling schemes, it is important to find suitable
coupling conditions for the model interfaces in time and space. Moreover, coupling
criteria need to be determined for an optimal realisation of the presented coupling
schemes. |
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