Combining crosshole and reflection borehole ground-penetrating radar (GPR) for imaging controlled freezing in shallow aquifers
<p>During test operation of a geological latent heat storage system as a potential option in the context of heat supply for heating and cooling demand, part of a shallow Quaternary glacial aquifer was frozen at the TestUM test site. In order to evaluate the current thermal state in the subsurf...
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Copernicus Publications
2024-12-01
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| Series: | Solid Earth |
| Online Access: | https://se.copernicus.org/articles/15/1465/2024/se-15-1465-2024.pdf |
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| author | P. Jung G. Hornbruch G. Hornbruch A. Dahmke A. Dahmke P. Dietrich U. Werban |
| author_facet | P. Jung G. Hornbruch G. Hornbruch A. Dahmke A. Dahmke P. Dietrich U. Werban |
| author_sort | P. Jung |
| collection | DOAJ |
| description | <p>During test operation of a geological latent heat storage system as a potential option in the context of heat supply for heating and cooling demand, part of a shallow Quaternary glacial aquifer was frozen at the TestUM test site. In order to evaluate the current thermal state in the subsurface, the dimension of the frozen volume has to be known. As the target is too deep for high-resolution imaging from the surface, the use of borehole ground-penetrating radar (GPR) is being investigated. For imaging and monitoring of a vertical freeze–thaw boundary, crosshole zero-offset and reflection borehole GPR measurements are applied. The freezing can be imaged in the zero-offset profiles (ZOPs), but the determination of ice body size is ambiguous because of the lack of velocity information in the frozen sediment. Reflection borehole GPR measurements are able to accurately image the position of the freezing boundary through repeated measurements of <span class="inline-formula">±0.1</span> m, relying on the velocity information from ZOPs. We have found that the complementary use of ZOPs and reflection measurements provides a fast and simple method to image freezing in geological latent heat storage systems. The presence of superimposed reflections from other observation wells and the low signal-to-noise ratio are problematic. The use in multiple observation wells allows an estimation of ice body size. A velocity model derived from multiple ZOPs enabled us to extrapolate geological information from direct-push-based logging and sediment cores to a refined subsurface model.</p> |
| format | Article |
| id | doaj-art-2077bdc2eb0d4ce8ab47ce2daf06c1ba |
| institution | Kabale University |
| issn | 1869-9510 1869-9529 |
| language | English |
| publishDate | 2024-12-01 |
| publisher | Copernicus Publications |
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| series | Solid Earth |
| spelling | doaj-art-2077bdc2eb0d4ce8ab47ce2daf06c1ba2024-12-11T08:57:07ZengCopernicus PublicationsSolid Earth1869-95101869-95292024-12-01151465147710.5194/se-15-1465-2024Combining crosshole and reflection borehole ground-penetrating radar (GPR) for imaging controlled freezing in shallow aquifersP. Jung0G. Hornbruch1G. Hornbruch2A. Dahmke3A. Dahmke4P. Dietrich5U. Werban6Department Monitoring and Exploration Technologies, Helmholtz-Centre for Environmental Research – UFZ, 04318 Leipzig, GermanyApplied Geosciences – Aquatic Geochemistry and Hydrogeology, Institute of Geosciences, Kiel University, 24118 Kiel, GermanyCompetence Centre for Geoenergy, Kiel University, 24118 Kiel, GermanyApplied Geosciences – Aquatic Geochemistry and Hydrogeology, Institute of Geosciences, Kiel University, 24118 Kiel, GermanyCompetence Centre for Geoenergy, Kiel University, 24118 Kiel, GermanyDepartment Monitoring and Exploration Technologies, Helmholtz-Centre for Environmental Research – UFZ, 04318 Leipzig, GermanyDepartment Monitoring and Exploration Technologies, Helmholtz-Centre for Environmental Research – UFZ, 04318 Leipzig, Germany<p>During test operation of a geological latent heat storage system as a potential option in the context of heat supply for heating and cooling demand, part of a shallow Quaternary glacial aquifer was frozen at the TestUM test site. In order to evaluate the current thermal state in the subsurface, the dimension of the frozen volume has to be known. As the target is too deep for high-resolution imaging from the surface, the use of borehole ground-penetrating radar (GPR) is being investigated. For imaging and monitoring of a vertical freeze–thaw boundary, crosshole zero-offset and reflection borehole GPR measurements are applied. The freezing can be imaged in the zero-offset profiles (ZOPs), but the determination of ice body size is ambiguous because of the lack of velocity information in the frozen sediment. Reflection borehole GPR measurements are able to accurately image the position of the freezing boundary through repeated measurements of <span class="inline-formula">±0.1</span> m, relying on the velocity information from ZOPs. We have found that the complementary use of ZOPs and reflection measurements provides a fast and simple method to image freezing in geological latent heat storage systems. The presence of superimposed reflections from other observation wells and the low signal-to-noise ratio are problematic. The use in multiple observation wells allows an estimation of ice body size. A velocity model derived from multiple ZOPs enabled us to extrapolate geological information from direct-push-based logging and sediment cores to a refined subsurface model.</p>https://se.copernicus.org/articles/15/1465/2024/se-15-1465-2024.pdf |
| spellingShingle | P. Jung G. Hornbruch G. Hornbruch A. Dahmke A. Dahmke P. Dietrich U. Werban Combining crosshole and reflection borehole ground-penetrating radar (GPR) for imaging controlled freezing in shallow aquifers Solid Earth |
| title | Combining crosshole and reflection borehole ground-penetrating radar (GPR) for imaging controlled freezing in shallow aquifers |
| title_full | Combining crosshole and reflection borehole ground-penetrating radar (GPR) for imaging controlled freezing in shallow aquifers |
| title_fullStr | Combining crosshole and reflection borehole ground-penetrating radar (GPR) for imaging controlled freezing in shallow aquifers |
| title_full_unstemmed | Combining crosshole and reflection borehole ground-penetrating radar (GPR) for imaging controlled freezing in shallow aquifers |
| title_short | Combining crosshole and reflection borehole ground-penetrating radar (GPR) for imaging controlled freezing in shallow aquifers |
| title_sort | combining crosshole and reflection borehole ground penetrating radar gpr for imaging controlled freezing in shallow aquifers |
| url | https://se.copernicus.org/articles/15/1465/2024/se-15-1465-2024.pdf |
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