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| Titel |
The effect of long-term fluid-rock interactions on the mechanical properties of reservoir rock - a case study of the Werkendam natural CO2 analogue field |
| VerfasserIn |
Suzanne Hangx, Pieter Bertier, Elisenda Bakker, Georg Nover, Andreas Busch |
| 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 |
250104740
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| Publikation (Nr.) |
 EGU/EGU2015-4173.pdf |
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| Zusammenfassung |
| Geological storage of CO2 is one of the most promising technologies to rapidly reduce
anthropogenic emissions of carbon dioxide. During long-term geological storage of CO2,
fluid-rock interactions, induced by the formation of carbonic acid, may affect the
mineralogical composition of the reservoir rock. Commonly expected reactions include the
dissolution of carbonate and/or sulphate cements, as well as the reaction of primary minerals
(feldspars, clays, micas) to form new, secondary phases. In order to ensure storage
integrity, it is important to understand the effect of such fluid-rock interactions
on the mechanical behaviour of a CO2 storage complex. However, most of these
reactions are very slow, which limits the ability to study coupled chemical-mechanical
processes in the lab. A possible way to circumvent long reaction times is to investigate
natural CO2 analogue fields, which experienced CO2-exposure for thousands of
years.
In this study, we looked at the Dutch Werkendam natural CO2 field and its unreacted
counterpart (Röt Fringe Sandstone, Werkendam, the Netherlands). We focussed on
CO2-induced mineralogical and porosity-permeability changes, and their effect on
mechanical behaviour of intact rock. Overall, CO2-exposure did not lead to drastic
mineralogical changes, though markedly different porosity-permeability relationships
were found for the unreacted and exposed material. The limited extent of reaction
was in part the result of bitumen coatings protecting specific mineral phases from
reaction. In local, mm-sized zones displaying significant anhydrite dissolution,
enhanced porosity was observed. For most of the reservoir the long-term mechanical
behaviour after CO2-exposure could be described by the behaviour of the unreacted
sandstone, while these more ‘porous’ zones were significantly weaker. Simple stress path
calculations predict that reservoir failure due to depletion and injection is unlikely. |
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