Content

The main objective of the Geo-OPT project was to transfer knowledge about the use of optical fibres in hydrogeology and geothermal energy from Canada to Slovenia for the thermolithological characterisation of strata and the evaluation of heat and flow transfer effects in the subsurface. This international collaboration and knowledge transfer is an extension of the collaboration within the UNESCO IGCP 636 project Geothermal Resources for the Energy Transition.

Guest researcher Fiona M. Chapman is a PhD student at the INRS – Institut national de la recherche scientifique, Quebec City, Canada. During her 3-month research stay, she shared her knowledge about the use of DTS optical fibres in hydrogeology and geothermal energy with our young researcher Karlo Borko and the rest of the project team.

During the Geo-OPT project, we conducted distributed temperature measurements (DTS) in two experimental setups in boreholes with different effects of groundwater flow velocities, which has not been done in Slovenia before. One of them was our newly established geothermal natural laboratory – a 100 m deep research geoprobe drilled in November 2024 in the Krško Basin with funding from the MKGP-ARIS CRP project V1-2213 GeoCOOL-FOOD. The second one was a borehole in a highly saturated and fissured rock with evident groundwater flow effect in the dolomite. Research papers on the experimental results have been prepared but are yet to be published.

• Project phases and realization 

We planned and conducted four activities (A) and several results (R):

A1: Setting up the equipment and transfer of existing experience

R1.1.: Equipment is complete and working

R1.2.: Presentation of experience at Geominuta and similar lectures (SGD/SKIAH, international geothermal summer school)

A2: Field work

R2.1.: Measurements at two different sites (boreholes) with different geological settings

A3: Data processing

A4: Preparation of a joint journal article

R4: Joint journal article submitted for review

In July 2025, the Geo-OPT project was successfully completed.

• Bibliography

BORKO, Karlo, CHAPMAN, Fiona, RMAN, Nina, RAYMOND, Jasmin. Estimating groundwater velocity across multiple porosity regimes with fiber-optic heating tests. V: RMAN, Nina (ur.). Coupling and integration of energy piles with other geothermal technologies : COST action CA21156 european network for FOstering Large-scale ImplementAtion of energy GEostructure (FOLIAGE) : The 3rd international summer school in Thermogeology in Slovenia : International geothermal summer school : 30th June-5th July 2025 : book of abstracts of the student conference of the training school. Ljubljana: Geological Survey of Slovenia, 2025. Str. 11. ISBN 978-961-6498-82-1. [COBISS.SI-ID 242589443]