Darcy velocity and Pèclet number analysis from underground thermal data

We propose a geophysical technique for the analysis of underground thermal data, which can help in the study of shallow aquifers with low velocity flows due to hydraulic gradient. The Darcy velocity and quantitative information on the dominant process of heat transport (Pèclet number) can be extracted from thermal logs in boreholes. Examples of application are given for a set of field data, recorded within porosity permeable horizons affected by groundwater flow. Hydrothermal parameters are determined by matching temperature and thermal gradient data with analytical models incorporating both heat and water transfer. As isotherms and equipotential lines are neither purely horizontal nor purely vertical, the technique, based on constant heat and water flow, also assumes that the temperature varies linearly along the horizontal.