Understanding coupled thermo-hydro-mechanical behavior in fault zones and naturally fractured reservoirs is crucial for both fundamental research and applied sciences, particularly in assessing the safety of radioactive waste disposal. The CHENILLE project aims to investigate the physical processes induced by thermal and hydraulic loading in a small fault zone within a highly consolidated shale formation. To achieve this, a thermally controlled in-situ fluid injection experiment will be conducted on a strike-slip fault at the Tournemire Underground Research Laboratory (URL) in France.
A heating system has been installed around the injection site to allow precise, incremental thermal loading. Various monitoring systems will track seismic and aseismic deformation due to thermal and hydraulic loading. The seismic monitoring setup includes Acoustic Emission (AE) and broadband sensors to capture seismic fracturing at sub-decimeter scales and slow deformation processes. Additionally, an injection chamber is being installed for controlled gas injection, and fiber optics will be integrated into the injection borehole for distributed temperature measurements.
Time-lapse active seismic surveys are planned before and after the experiment to image the structural network, detect new structures triggered by hydro-thermal pressurization, and assess velocity field changes.