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| Titel |
Fault reactivation and ground uplift assessment at a prospective German CO2 storage site |
| VerfasserIn |
Lina Röhmann, Elena Tillner, Thomas Kempka, Fabien Magri, Mich. Kühn |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250077332
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| Zusammenfassung |
| The geological storage of CO2 in deep saline aquifers is seen as a promising measure for
reducing anthropogenic greenhouse gas emissions into the atmosphere. However, generally
large-scale pressure build-up as a result of CO2 injection may impact the mechanical
behaviour of reservoir, caprock and existing faults. Caprock fracturing, ground uplift,
reactivation of faults or induced seismicity are inherent risks that may pose potential health,
security and environmental hazards.
Within the frame of the present study we investigated the geomechanical response of a
deep saline aquifer and the surrounding rocks to CO2 storage at a prospective German CO2
storage site by coupled hydromechanical simulations. Changes in the initial stress field due to
pressure build-up as a result of CO2 injection allow assessment of potential fault reactivation
and magnitude of ground uplift.
For this purpose, a 3D geological structural model covering an area of about 100 km x
100 km in the southeastern part of the State of Brandenburg was implemented. In a first step,
stratigraphic contour lines and major fault lines were digitised based on the GeotIS online
cartography of the Northeast German Basin as well as geological maps of the German State
of Brandenburg, using the Petrel software package [1-3]. The 3D regional-scale model
comprises several stratigraphic units down to the Zechstein. Afterwards, a stratigraphic
correlation, depth adjustment and thickness correction of the different units were performed
based on existing borehole data from the study area. Borehole and literature data were further
used for model parameterisation.
Subsequently, the model was gridded in Petrel and transferred into the reservoir simulator
TOUGH2-MP to perform large-scale numerical multi-phase multi-component (CO2, NaCl,
H2O) flow simulations. Furthermore, the gridded model was applied in the geomechanical
simulator FLAC3D to identify changes in the recent stress field and deformation resulting
from the pressure elevation during CO2 injection [4-5]. In the present modelling study 1.7 Mt
CO2/year were injected into the top of an anticline structure of the 23 m thick sandstone
formation of the Middle Bunter for 20 years of simulation time. A one-way coupling between
both simulators was undertaken by transferring the pore pressure distribution from
the dynamic flow simulations into the geomechanical simulator for selected time
steps.
The results show that detailed knowledge on geomechanical processes during CO2
injection is of uttermost importance for the assessment of fault reactivation and ground uplift
and associated risks.
References
[1] Schulz R, Agemar T, Alten AJ, Kühne K, Maul AA, Pester S et al. Implementation of
a Geothermal Information System for Germany. - Erdöl Erdgas Kohle 2007, 123(2): 76-81 (in
German).
[2] Beer H, Stackebrandt W. Geological Map of the State of Brandenburg 1:300.000.
Contour Map of the Zechstein Formation Top, 2000. Cottbus: Landesamtes für Bergbau,
Geologie und Rohstoffe Brandenburg (in German).
[3] Schlumberger. Petrel Seismic-to-Evaluation Software, Version 2010.2.2.,
2012.
[4] Zhang K, Wu YS, Pruess K. User’s Guide for TOUGH2-MP – A Massively Parallel
Version of the TOUGH2 Code. Report LBNL-315E, 2008, Earth Sciences Division,
Lawrence Berkeley National Laboratory, Berkeley, California.
[5] Itasca. FLAC3D Software Version 5.0, Advanced Three Dimensional Continuum
Modelling for Geotechnical Analysis of Rock, Soil and Structural Support, 2012. |
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