8. Thermal Conductivity of Rocks and Minerals

Abstract

This chapter reviews methods of thermal conductivity measurement at various conditions under which the lattice vibration is the principal mode of thermal conduction. Thermal conductivity measurements at zero pressure are essential to the study of terrestrial heat flow. To determine heat flow from underground temperature profiles, the thermal conductivity representative of rock samples obtained along the temperature profile must be measured at pressures at or only slightly above ordinary (atmospheric) pressure of 1.03 bars. The chapter describes techniques suitable for this purpose. Divided-bar method is a standard technique for thermal conductivity measurement. The basis of this measure is the continuity of a steady linear flow of heat through a bar. A rock sample is cut into a flat circular cylinder and sandwiched between metal cylindrical bars of the same diameter. The divided-bar method can also be used to measure thermal conductivity of soft sediment samples. Thermal stack method is another successfully applied method at higher temperatures. In the divided-bar and thermal stack methods, a steady-state temperature distribution is employed to obtain thermal conductivity. However, time-varying temperatures are also useful for determining thermal properties.