Study of temperature effect on thermal conductivity of Jhiri shale from Upper Vindhyan, India

Abstract

Shale is a very important sedimentary rock that is used as building construction material and found predominantly underground. Shales have been found to contain both oil and gas, which can be extracted only when it is fractured. In this paper, temperature dependent thermal properties of Jhiri shale are presented over a temperature range from air-dried to 900 °C. Porosity, density, and compressional wave velocity measurement have been done as per ISRM standard. Furthermore, internal microstructure is studied using scanning electron microscopy (SEM). In this study, thermal conductivity is predicted using P-wave velocity and porosity of Jhiri shale. The effect of temperature on microstructure, porosity, and mineralogical composition and dependency of thermal conductivity on porosity is discussed. It was found that as temperature increases, porosity of Jhiri shale also increases because of thermal cracking, which acts as a barrier of heat flow, reducing thermal conductivity. Uncertainties of measured quantities are calculated and the total combined expanded uncertainty for thermal conductivity value at 95 % confidence level have been found to be less than 6 %.