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dc.contributor.author
Hediger, Roman
dc.contributor.supervisor
Shakas, Alexis
dc.contributor.supervisor
Maurer, Hansruedi
dc.contributor.supervisor
Krietsch, Hannes
dc.date.accessioned
2021-01-07T09:23:24Z
dc.date.available
2020-12-07T10:36:50Z
dc.date.available
2020-12-07T11:15:01Z
dc.date.available
2020-12-08T14:29:33Z
dc.date.available
2020-12-18T11:47:38Z
dc.date.available
2021-01-07T09:23:24Z
dc.date.issued
2020-06
dc.identifier.uri
http://hdl.handle.net/20.500.11850/455004
dc.identifier.doi
10.3929/ethz-b-000455004
dc.description.abstract
A considerable amount of research is currently conducted in Switzerland in the field of geothermal energy. That is because the Swiss Energy Strategy 2050 aims to increase the percentage of them in energy production to 7% of projected energy demand. One of these places where research is done is the Bedretto Underground Laboratory for Geoenergies (BULG) in Ticino. The BULG is a research facility in the Bedretto Tunnel surrounded by Rotondo-granite, starting at 2 km (Tunnel Meter TM2000) into the 5 km long tunnel. During three different drillings (boreholes CB1-CB3, lengths: 300m, 220m, 190m) in the southwestern wall, enhanced water outflow from the boreholes was noted, when intersecting a shear zone called Characterization Borehole Shear Zone (CBSZ). This indicates that CBSZ has a high hydraulic permeability. A permeable structure in the subsurface is of high interest concerning geothermal reservoir research. However, before this zone can be examined more precisely, its course in the underground must be determined. In this thesis, firstly, a model of CBSZ is developed; secondly, the intersection of this shear zone with the tunnel is deduced, and thirdly the history of its origin is investigated. The modeling tool used is called Gridfit and approximates a best-fitting surface between all inserted data points. Therefore, optical and acoustic borehole logging data sets and ground-penetrating radar images of all CB boreholes, as well as geological drill core descriptions, are available. From the logging data, the orientation of CBSZ in the boreholes is determined. Whereas from the GPR images, the course of the shear zone further away from the CB’s, is deduced. A combination of these two data sets unites regionally exact logging measurements as well as slightly less accurate GPR data sets of the shear zones’ course in the granite. This data are sequentially transferred to Gridfit, which constructs a more accurate model with each additional information. The resulting model has a slightly curved fracture surface towards the tunnel and is now compared with known fractures from the tunnel. Thus it follows that CBSZ is most likely the structure TM1986 from the Bedretto Tunnel. From the history of its origin, it can be concluded that the shear zone was initially formed under ductile conditions with temperatures over 250-350 C prevailing. These are conditions that are reached in depths of more than 10-15 km. Afterwards, there was an uplift of the Rotondo-granite and an associated cooling of the rock. Later the shear zone was reactivated again but deformed brittle due to the relatively low temperatures. This brittle deformation is very likely to be the origin of the high porosity that CBSZ has today. An important application of these findings is that it is now possible to predict how deep further drillings have to be planned to encounter CBSZ. Furthermore, based on them, more research around this shear zone can now be initiated.
en_US
dc.format
application/pdf
en_US
dc.language.iso
en
en_US
dc.publisher
ETH Zurich
en_US
dc.rights.uri
http://rightsstatements.org/page/InC-NC/1.0/
dc.subject
3D Shear Zone Model
en_US
dc.subject
Bedretto Underground Laboratory for Geoenergies
en_US
dc.subject
Bedretto Tunnel
en_US
dc.subject
Ground penetrating radar (GPR)
en_US
dc.title
3D geological model of a shear zone conditioned on geophysical data and geological observations
en_US
dc.type
Bachelor Thesis
dc.rights.license
In Copyright - Non-Commercial Use Permitted
ethz.size
54 p.
en_US
ethz.publication.place
Zurich
en_US
ethz.publication.status
published
en_US
ethz.leitzahl
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02330 - Dep. Erdwissenschaften / Dep. of Earth Sciences::02282 - SCCER-SoE / SCCER-SoE
en_US
ethz.leitzahl
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02330 - Dep. Erdwissenschaften / Dep. of Earth Sciences::02334 - BULGG - Bedretto Underground Lab / BULGG - Bedretto Underground Lab
en_US
ethz.leitzahl
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02330 - Dep. Erdwissenschaften / Dep. of Earth Sciences::02334 - BULGG - Bedretto Underground Lab / BULGG - Bedretto Underground Lab
en_US
ethz.tag
Bedretto Underground Laboratory for Geoenergies (BULG)
en_US
ethz.tag
Bedretto Underground Laboratory for Geosciences and Geoenergies (BULGG)
en_US
ethz.date.deposited
2020-12-07T10:37:00Z
ethz.source
FORM
ethz.eth
yes
en_US
ethz.availability
Open access
en_US
ethz.rosetta.installDate
2020-12-08T14:30:01Z
ethz.rosetta.lastUpdated
2021-02-15T22:57:56Z
ethz.rosetta.versionExported
true
ethz.COinS
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