Temperature-dependent thermophysical properties of Ganurgarh shales from Bhander group, India

Abstract

Thermal conductivity is a very important property of rocks which determines the rate of heat transfer between two adjacent layers of rock. Temperature-dependent thermal properties of Ganurgarh shale are analyzed and presented over a temperature range from air dried to 900 °C. Physico-mechanical properties, porosity, density and P-wave velocity are determined as per ISRM standards. In addition, changes in internal microstructure are studied using scanning electron microscopy (SEM). Thermal conductivity is predicted using P-wave velocity and porosity of Ganurgarh shale. The effect of temperature on the microstructure, porosity, and mineralogical composition of shale and dependency of thermal conductivity on porosity of shale is discussed. It has also been found that as temperature increases, porosity of Ganurgarh shale increases up to 2.3 times of its initial porosity because of thermal cracking which also acts as barrier of heat flow and hence thermal conductivity decreases. Uncertainties of measured quantities are calculated and the total combined expanded uncertainty for thermal conductivity value of Ganurgarh shale at 95 % confidence level is less than 6 %. All the results obtained using a state-of-the-art single hot guarded parallel plate apparatus.