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Crustal-Scale Thermal Models: Revisiting the Influence of Deep Boundary Conditions
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  • Denise Degen,
  • Karen Veroy,
  • Magdalena Scheck-Wenderoth,
  • Florian Wellmann
Denise Degen
RWTH Aachen University, RWTH Aachen University

Corresponding Author:[email protected]

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Karen Veroy
Eindhoven University of Technology, Eindhoven University of Technology
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Magdalena Scheck-Wenderoth
Helmholtz Centre Potsdam, GFZ German Research Science for Geosciences, Helmholtz Centre Potsdam, GFZ German Research Science for Geosciences
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Florian Wellmann
RWTH Aachen University, RWTH Aachen University
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The societal importance of geothermal energy is significantly increasing because of its low carbon-dioxide footprint. However, geothermal exploration is also subject to high risks. For a better assessment of these risks, extensive parameter studies are required that improve the understanding of the subsurface. This yields computationally demanding analyses. Often this is compensated by constructing models with a small vertical extent. This paper demonstrates that this leads to entirely boundary-dominated and hence uninformative models. It demonstrates the indispensable requirement to construct models with a large vertical extent to obtain informative models with respect to the model parameters. For this quantitative investigation, global sensitivity studies are essential since they also consider parameter correlations. To compensate for the computationally demanding nature of the analyses, a physics-based machine learning approach is employed, namely the reduced basis method, instead of reducing the physical dimensionality of the model. The reduced basis method yields a significant cost reduction while preserving the physics and a high accuracy, thus providing a more efficient alternative to considering, for instance, a small vertical extent. The reduction of the mathematical instead of physical space leads to less restrictive models and, hence, maintains the model prediction capabilities. The combination of methods is used for a detailed investigation of the influence of model boundary settings in typical regional-scale geothermal simulations and highlights potential problems.
Feb 2022Published in Environmental Earth Sciences volume 81 issue 3. 10.1007/s12665-022-10202-5