Bestimmung thermischer Eigenschaften der Gesteine des Unteren und Mittleren Buntsandsteins

For accurate planning of vertical borehole heat exchanger systems, knowledge of thermo-physical ground parameters is critical. This study reports laboratory-measured thermal conductivity and diffusivity values of Mesozoic sandstones (Lower and Middle Buntsandstein) from four wells. The measurements were made on drill core using an optical scanning method. The mean thermal conductivities of the sandstones range between 2.6?±?0.3 W?/?(m?·?K) and 3.1?±?0.4 W?/?(m?·?K) for dry conditions and between 3.6?±?0.3 W?/?(m?·?K) and 4.1?±?0.6 W?/?(m?·?K) after saturation with water. The mean thermal diffusivity values range between (1.6?±?0.2)?·?10??6 m²?/?s for dry and (2.0?±?0.6)?·?10??6 m²?/?s for water-saturated sandstones. Thermal properties are closely related to the petrography and lithostratigraphy of the sandstones. Additionally, three temperature correction methods were applied for the purpose of evaluating the comparative accuracy and the correction schemes with respect to local in-situ conditions. The results show that the temperature corrections proposed by Somerton (Thermal properties on temperature-related behavior of rock/fluid systems, Elsevier, New York, S 257, 1992) and Sass et al. (J Geophys Res, 97:5017–5030, 1992) are most suited for the respective sandstone data set.