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Titel |
Regional-scale geomechanical impact assessment of underground coal gasification by coupled 3D thermo-mechanical modeling |
VerfasserIn |
Christopher Otto, Thomas Kempka, Krzysztof Kapusta, Krzysztof Stańczyk |
Konferenz |
EGU General Assembly 2016
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 18 (2016) |
Datensatznummer |
250121984
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Publikation (Nr.) |
EGU/EGU2016-901.pdf |
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Zusammenfassung |
Underground coal gasification (UCG) has the potential to increase the world-wide coal
reserves by utilization of coal deposits not mineable by conventional methods. The UCG
process involves combusting coal in situ to produce a high-calorific synthesis gas, which can
be applied for electricity generation or chemical feedstock production. Apart from its high
economic potentials, UCG may induce site-specific environmental impacts such as fault
reactivation, induced seismicity and ground subsidence, potentially inducing groundwater
pollution. Changes overburden hydraulic conductivity resulting from thermo-mechanical
effects may introduce migration pathways for UCG contaminants. Due to the financial efforts
associated with UCG field trials, numerical modeling has been an important methodology to
study coupled processes considering UCG performance. Almost all previous UCG
studies applied 1D or 2D models for that purpose, that do not allow to predict the
performance of a commercial-scale UCG operation. Considering our previous findings,
demonstrating that far-field models can be run at a higher computational efficiency by using
temperature-independent thermo-mechanical parameters, representative coupled simulations
based on complex 3D regional-scale models were employed in the present study.
For that purpose, a coupled thermo-mechanical 3D model has been developed to
investigate the environmental impacts of UCG based on a regional-scale of the
Polish Wieczorek mine located in the Upper Silesian Coal Basin. The model size is
10 km × 10 km × 5 km with ten dipping lithological layers, a double fault and
25 UCG reactors. Six different numerical simulation scenarios were investigated,
considering the transpressive stress regime present in that part of the Upper Silesian Coal
Basin. Our simulation results demonstrate that the minimum distance between the
UCG reactors is about the six-fold of the coal seam thickness to avoid hydraulic
communication between the single UCG reactors. Fault reactivation resulting from fault shear
and normal displacements is discussed under consideration of potentially induced
seismicity. Here, the coupled simulation results indicate that seismic hazard during
UCG operation remains negligible with a seismic moment magnitude of MW < 3. |
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