Thermal conductivity of sedimentary rocks in two exploratory wells drilled in the Paipa geothermal area, Colombia

Abstract

The Paipa geothermal area, located in the Eastern Cordillera of the Colombian Andes, is a sedimentary basin with promising potential for future geothermal energy development due to its favorable geological conditions. Over the last years, multiple geophysical, geological, and geochemical studies have highlighted the area's subsurface thermal anomalies and structural features. As a result of this growing body of evidence, the Colombian Geological Survey (SGC) selected the Paipa region for exploratory drilling and drilled two wells to investigate its geothermal potential. This study has two main objectives: first, to present the thermal conductivity results obtained from laboratory measurements on core samples and demonstrate how well log data can be used to correct these values to reflect in situ conditions; and second, to assess the use of well-logging data (gamma ray, neutron porosity, and temperature) as a practical method to estimate rock thermal conductivity in geothermal wells. For validating these estimates against 58 measured rock samples using four mixing models (harmonic, arithmetic, geometric, and root mean) within a shale-sand-fluid framework. Temperature corrections were applied separately to the solid and fluid phases. For the well AGT-01, the geometric mean model provided the best agreement with the measured thermal conductivity, yielding a value of 0.11 $W/mK$. In contrast, for the well AGT-02, the harmonic mean model showed the best fit, with a conductivity value of 0.18 $W/mK$.