Thermogeology in the Oslo region and Kristiansand - Results from thermal response tests (TRT) with and without artificially induced groundwater flow

NGU Rapport 2009.069

Thermal response tests (TRT) are widely used to measure the effective thermal conductivity and borehole resistance in a well. The gained data serve as the basis for the dimensioning of larger ground-source heat-pump installations with closed loop systems. The influence of groundwater flow on a TRT in fractured aquifers is not well understood. An attempt to quantify the influence of groundwater was done by pumping of groundwater from a nearby well during the TRT. The results were compared to a TRT in the same well without pumping. The effect of the groundwater flow is shown indirectly by the higher measured thermal conductivity and directly through the comparison of temperature profiles before and four hours after the TRT.