Development of Fibre Optic Sensors for Distributed - Rennes, France - Geosciences Rennes (UMR6118)

Geosciences Rennes (UMR6118)
Geosciences Rennes (UMR6118)
Entreprise vérifiée
Rennes, France

il y a 3 semaines

Sophie Dupont

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Sophie Dupont

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Description

Development of fibre optic sensors for distributed measurement of underground flows with high spatial resolution:

  • Réf
    ABG-121486
  • Sujet de Thèse 20/03/2024
  • Contrat doctoral
  • Geosciences Rennes (UMR6118)
  • Lieu de travail
  • Rennes
  • Bretagne
  • France
  • Intitulé du sujet
  • Development of fibre optic sensors for distributed measurement of underground flows with high spatial resolution
  • Champs scientifiques
  • Physique
  • Ecologie, environnement

Description du sujet:

The heterogeneity of underground environments remains a major difficulty in hydrogeology for modelling the transport of contaminants.

The classic approach, which consists of making point measurements of permeability, that are then integrated into models to predict the transport of pollutants, remains very limited due to the difficulty of obtaining exhaustive data that is representative of the heterogeneity of underground environments.

Recently, a highly innovative and promising new approach has been developed and validated experimentally and using numerical simulations to carry out distributed flux measurements (Simon et al., The approach consists of heating an optical fibre cable by passing an electric current through the cable's metal armature.

The resulting rise in temperature depends both on the thermal conduction of the sediments surrounding the cable and on the intensity of the underground flows that dissipate some of the produced heat.

The very promising nature of the method has been demonstrated by carrying out measurements either in riverbed sediments (Simon et al, 2022) or by installing fibre-optic cables in a granular aquifer (Lee et al, in preparation).

One of the limitations of the method remains the spatial resolution of distributed fibre-optic temperature measurements.

Experimental tests have shown that the spatial resolution of conventional tools used to measure temperature by optical fibre (DTS Raman) is only 60 cm to 1 m at best (Simon et al., New interrogation systems based on optical frequency domain reflectometry (OFDR) can significantly improve measurement resolution.

However, one of the major problems remains decoupling the thermal and mechanical behaviour of cables.

One of the first objectives of the thesis will be to experimentally test different types of cable to characterise the cable's thermomechanical response.

The cables selected will then be used in different experimental configurations (Darcy tank, flow in a fractured medium) to evaluate the performance of the new devices developed and optimise their measurement capabilities through advanced data processing.

Part of the work will also involve validating the approach numerically.

One of the challenges of the thesis will also be to propose devices that provide the best coupling with the surrounding environment, particularly for borehole measurements.

Ultimately, the devices developed will be used to carry out experiments on very well documented and instrumented pilot field sites (Valcartier site in Quebec, Ploemeur site, 56).


Nature du financement:


  • Contrat doctoral

Précisions sur le financement:


Présentation établissement et labo d'accueil:


  • Geosciences Rennes (UMR6118)
Géosciences Rennes (GR) is a joint research unit (CNRS + UR1) with 60 permanent researchers. It hosts ~10 foreign researchers/year, and publishes ~ 100 papers/year. The Rennes hydrogeology group is composed of 15 permanent staff and is internationally recognized as one of the leading group in this field. The thesis will be co-supervised by Olivier Bour and Maria Klepikova, Géosciences Rennes and Aghiad Khadour, Université Gustave Eiffel. Part of the work is likely to take place in the laboratories of the COSYS department at Marne La Vallée, as part of the FIFLOW project.


Requirements:

Research Field - Geosciences or Physics or Environmental science

Education Level - Master Degree or equivalent


Skills/Qualifications

  • Experience with computer programming /scripting (Matlab, Python, R)
  • Sound and quantitative understanding of geological fluid flow
  • Applicants must be proficient in both written and oral English
  • Experience in fluid flow modelling in porous media is an advantage
  • Experience with either reservoir modelling or hydrodynamic modelling is an advantage.
  • Applicants must be able to work independently and in a structured manner and demonstrate good collaborative skills.
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