Field test and numerical simulation of TRT equipment applicable to water wells of large diameters

Présentation publique des travaux de recherche en géothermie du professeur Hikari Fujii dans le cadre d’une visite d’une délégation japonaise de l’Université d’Akita à l’INRS.

Date: 27 mars, 15h
Lieu: Local 2405

Détail de la présentation

This research aimed to validate the effectiveness of a novel TRT equipment applicable to large diameter water wells. The equipment consisted of an optical fiber thermometer, a cable heater, and cylindrical electromagnets. The vertical distribution of apparent thermal conductivities of ground (?s) was estimated by applying Kelvin's line source theory to temperature changes during the heating and recovery periods. TRTs were conducted four times with different heating periods using the new TRT equipment in a water well (204.7 mm ID) cased with steel pipes to investigate the necessary length of the heating period. Thereafter, estimated ?s profiles were compared with a reference profile estimated from TRTs using cable heating method in the same test field. The ?s profiles estimated from the heating periods of each test differed significantly from the reference profile due to the natural convection of groundwater. In contrast, the ?s profiles estimated from the recovery period showed good agreement with the reference profile when a heating period over 2 days was applied. Finally, the numerical models were developed and validated to reproduce the TRTs. The heating periods required to estimate the appropriate ?s profile were evaluated for larger well diameters of 300, 400, and 500 mm. The simulation results showed a proportional relationship between the diameter of the wells and the required length of heating period.