arXiv subjects

Dieter Werthmüller

Publications and source records attributed to Dieter Werthmüller.

3 recordsLinked to original sources

arXiv2025

Introducing GeoHEAT: Georadar-aided High-resolution Exploration for Advancing geoThermal energy usage

We present a novel geothermal exploration approach that integrates innovations at three spatial scale. At the regional scale (~100 km) we create LCOE heat maps using a techno-economic and metamodel analysis. This allows us to choose several potential sites to perform a reservoir scale (~10 km) assessment with passive seismics and gravity. By integrating the latter with probabilistic geological and geomechanical modeling we propose locations to drill exploration boreholes. Then follows a high-resolution borehole characterization incorporating various analyses, the central one being a georadar probe that allows to illuminate permeable structures. Within this project, we also design and build a geothermal grade georadar. Here, we present the approach and result from the application of our methodology to the Swiss canton of Thurgau, with the purpose of large-scale geothermal exploration.

physics.geo-ph↗

arXiv2021

Time-Domain Modeling of Three-Dimensional Earth's and Planetary Electromagnetic Induction Effect in Ground and Satellite Observations

Electric currents induced in conductive planetary interiors by time-varying magnetospheric and ionospheric current systems have a significant effect on electromagnetic (EM) field observations. Complete characterization of EM induction effects is difficult owing to non-linear interactions between the three-dimensional (3-D) electrical structure of a planet and spatial complexity of inducing current systems. We present a general framework for time-domain modeling of 3-D EM induction effects in heterogeneous conducting planets. Our approach does not assume that the magnetic field is potential, allows for an arbitrary distribution of electrical conductivity within a planet, and can deal with spatially complex time-varying current systems. The method is applicable to both data measured at stationary observation sites and satellite platforms, and enables the calculation of 3-D EM induction effects in near real-time settings.

physics.geo-ph↗

arXiv2021

Towards an open-source landscape for 3D CSEM modelling

Large-scale modelling of three-dimensional controlled-source electromagnetic (CSEM) surveys used to be feasible only for large companies and research consortia. This has changed over the last few years, and today there exists a selection of different open-source codes available to everyone. Using four different codes in the Python ecosystem, we perform simulations for increasingly complex models in a shallow marine setting. We first verify the computed fields with semi-analytical solutions for a simple layered model. Then we validate the responses of a more complex block model by comparing results obtained from each code. Finally we compare the responses of a real world model with results from the industry. On the one hand, these validations show that the open-source codes are able to compute comparable CSEM responses for challenging, large-scale models. On the other hand, they show many general and method-dependent problems that need to be faced for obtaining accurate results. Our comparison includes finite-element and finite-volume codes using structured rectilinear and octree meshes as well as unstructured tetrahedral meshes. Accurate responses can be obtained independently of the chosen method and the chosen mesh type. The runtime and memory requirements vary greatly based on the choice of iterative or direct solvers. However, we have found that much more time was spent on designing the mesh and setting up the simulations than running the actual computation. The challenging task is, irrespective of the chosen code, to appropriately discretize the model. We provide three models, each with their corresponding discretization and responses of four codes, which can be used for validation of new and existing codes.

physics.geo-ph↗