Temperature dependence of the thermal diffusivity of sandstone

High temperature causes a significant impact on the thermal diffusivity of rocks. The deterioration of the thermal properties of rocks, would seriously threaten many applications in engineering and geosciences, such as petroleum engineering, geothermal energy. This paper emphasizes on the variations of thermal diffusivity of sandstone after high-temperature heating. The results indicate that there are two main reasons for the decrease of thermal diffusivity: the variation of mineralogical composition, the physical and chemical reactions caused by thermal stress. The thermal diffusivity of sandstone decreases with temperature and it tends to be constant once the temperature exceeds a critical value. From 25°C to 300 °C, the decrease is mainly due to the escaping of the adhered water, bound water and structural water. Between 300°C and 600 °C, the thermal response of minerals in sandstone increases the development of microcracks and weakens the thermal diffusivity of sandstone.