Measurement of Thermal Conductivity and Diffusivity of Drill Core Samples from the Los Humeros Geothermal Field, Mexico, by a Line-Source Technique

摘要

The thermal conductivity and diffusivity and the specific heat drill core samples from the Los Humeros geothermal field was measured using a technique based on the temperature distribution around an ideal line heat source of constant strength embedded in an infinite medium. The thermal properties can be determined quickly from a relatively simple experiment which requires only the measurement of the temperature history at a point during a short heating period. An experimental system for application of this technique was implemented and procedures for testing and data reduction were developed. Accuracy and reproducibility of the method were evaluated through measurements on standard materials. Tests show that thermal conductivity and diffusivity can be determined with a reproducibility of 2percent within an accuracy of +-3percent. Thermal properties of 15 dry and water-saturated core samples from 13 wells of the Los Humeros geothermal field (LHGF), Mexico were determined. Dry sample thermal conductivity varied from 0.97 to 1.74 W/m-K while thermal diffusivity ranged from 0.40E-02 to 1.00E-02 cm~(2)/s and specific heat from 711.6 to 1046.5 J/kg-K. Saturation increased these properties by 59.0, 21.4 and 27.7 percent, respectively.