An in-situ thermo-hydraulic experiment at the URL

This paper is concerned with an in situ thermo-hydraulic experiment carried out at the Underground Research Laboratory of Atomic Energy of Canada Limited. The thermo-hydraulic experiment was designed to determine a hydro-thermal coupling parameter as well as the permeability and the thermal and hydraulic diffusivities of the Lac du Bonnet granite. Several water injection and heater tests were conducted during this experiment. In an injection test, a given volume of water is pumped quasi instantaneously in a sealed-off interval of the borehole, while in a heater test, heat is produced at a constant rate over a certain period (ranging from about one day to several weeks). The experimental set-up involves a heater installed in a sub-horizontal borehole drilled from an underground gallery, and piezometers and thermistors located at different distances from the heater, in auxiliary boreholes drilled from an adjacent gallery. Determination of the material parameters relies on matching the measured pore pressure and temperature responses with the theoretical predictions based on singular solutions of thermoporoelasticity.