Temperature Gradient Measurements in Hydrothermal Areas of Georgia

Abstract

The project uses results of temperature measurements in shallow boreholes to determine the geothermal gradients for a selected set of wells in Georgia. The hydrothermal flow in the Caucasus region driven by ongoing tectonic activities causes a varying temperature field that impedes determination of stable temperature gradients. Conventional temperature logging provides only a snapshot of the temperature distribution in a well. Therefore, the methodology adopted in this study is based on continuous stationary measurements with up to eight temperature sensors fixed at different depths in the wells. Temperature measurements have been performed in 14 wells using thermometers with resolving power of 0.01 K. The temperature field was recorded during periods ranging from 16 hours to 4 days. This practice of measurements enabled detection of thermal effects of fluid flows within the selected set of boreholes. Considering the 14 wells that were selected for this study, eight showed signs of stability in temperature increase versus depth and the remaining seven wells revealed signs of instability due subsurface fluid flows.