Evaluation of thermal conductivity estimation models with laboratory-measured thermal conductivities of sediments

摘要

Thermal conductivity is one of the key parameters for estimating low-temperature geothermal potential. In addition to field techniques, it can be determined based on physical parameters of the sediment measured in the laboratory. Following the methodology for cohesive and non-cohesive sample preparation, laboratory measurements were carried out on 30 samples of sediments. Density, porosity and water content of samples were measured and used in thermal conductivity estimation models (TCEM). The bulk thermal conductivity (λ_b) calculated with six TCEMs was compared with the measured λ_b to evaluate the predictive capacity of the analytical methods used. The results show that the empirical TCEMs are suitable to predict the λ_b of the analysed sediment types, with the standard deviation of the residuals (RMSE) ranging from 0.11 to 0.35 Wm~(-1) K~(-1). To improve the fit, this study provides a new modified parameterisation of two empirical TCEMs (Kersten and CoteKonrad model) and, therefore, suggests the most suitable TCEMs for specific sample conditions. The RMSE ranges from 0.11 to 0.29 Wm~(-1) K~(-1). Mixing TCEM showed an RMSE of up to 2.00 Wm~(-1) K~(-1), meaning they are not suitable for predicting sediment λ_b. The study provides an insight into the analytical determination of thermal conductivity based on the physical properties of sediments. The results can help to estimate the low-temperature geothermal potential more quickly and easily and promote the sustainable use of this renewable energy source, which has applications in environmental and engineering science.