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| Titel |
Static and dynamic modeling for assessment of freshwater salinisation by CO2 storage |
| VerfasserIn |
Thomas Kempka, Christoph Jahnke, Egbert Jolie, Inga Moeck, Nicole Schulz, Günter Zimmermann, Mich. Kühn |
| 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 |
250054845
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| Zusammenfassung |
| Present scientific research activities addressing geological CO2 storage highlight upward
brine migration as potential endangerment for freshwater aquifers. The processes at the salt-
and freshwater boundary are in general not well understood. Taking into account the pressure
elevation resulting from a CO2 storage operation, the knowledge of these processes becomes
even more important.
Within the scope of the present study, we implemented a static geological model of a
prospective CO2 storage site located in the Northeastern German Basin. It was
previously explored by a few wells and 2D seismics. Further investigations using
3D seismics as well as additional exploration wells are scheduled. Furthermore,
we applied large-scale coupled numerical multi-phase multi-component (CO2,
water and salt) simulations on a high performance computing cluster system to
identify the impact of pressure elevation on brine migration for a specific CO2 storage
reservoir.
The prospective CO2 storage site is characterized by saline aquifers very likely suitable
for CO2 storage. These are located in a classical anticline structure originating from
salt tectonic processes. In total, three sand stone formations situated in the Middle
Bunter were identified as potential CO2 storage formations at depths between about
1,050 (reservoir top) and 1,500 m (spill point) with a cumulative thickness of about
60 m. In addition to the 180 m thick Upper Bunter cap rock mainly consisting of
anhydrite, salt, clay and silt stones, each of the target storage formations provides a
cap rock composed of clay and silt stones with average thicknesses of 30 to 60 m.
Potentially endangered freshwater reservoirs are located in the Quarternary and
Tertiary, whereas the saline to freshwater boundary is determined at a depth of about
220 m. The area investigated in the numerical simulations has a size of about 41 x
41 km2 and is confined by fault systems in the southwest and northeast. About
1.7 million metric tonnes of CO2 per year are scheduled for injection starting in
2015.
Our first numerical simulation studies aimed at the sensitivities of pressure elevation in
the target CO2 storage formations with regard to the conductivity of the adjacent fault
systems as well as reservoir properties such as porosity, permeability and relative
permeabilities. Furthermore, we investigated the utilization of reservoir pressure
management based on brine production from the target storage formations. For this
purpose, sensitivities of reservoir pressure development based on different brine
production rates applied at two wells situated at the flanks of the anticline (each in a
distance of about 6 to 7 km of the injection well) were evaluated. As a result, we
determined spatial and time-dependent distributions of the displaced brine as well as
reservoir pressure development during the computation of several migration scenarios
involving the identification of brine migration paths such as hydraulic conductivities
in the cap rocks (crack and fissure systems) as well as hydraulic conductive fault
systems.
Further numerical simulations aim at the coupling of our multi-phase multi-component
simulations with a geomechanical simulator to evaluate the generation of cracks
in the cap rocks as well as the reactivation of faults with regard to the reservoir
pressure. Based on these results a sustainable injection strategy will be elaborated. |
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