Thermal conductivity and diffusivity of fine-grained sedimentary rocks

Thermal conductivity is an important thermophysical rock property, needed for heat flow determination, deep thermal regime determination, and reconstruction of thermal history of sedimentary basin. It is generally accepted that the thermal conductivity of rocks decreases with increasing temperature and increases with increasing pressure, and the effects of temperature and pressure counteract each other. Although many measurements of thermal conductivity of the igneous and metamorphic rocks have been taken, little attention has been paid to sedimentary rocks and heat flow in sedimentary basins. Samples selected for the investigation, representing sedimentary rocks of aleuritic structure, were collected from boreholes (from deep formation, approx. 3000 m) and outcrops. The mineral composition was determined with the use of TG/DSC analysis, under inert and oxidizing atmosphere. Thermal conductivity measurements were taken with the use of C-Therm analyser, in directions parallel and perpendicular to the bedding in rock. Thermal conductivity of the examined rocks ranges from 0.96 to 6.06 W m−1 K−1 and is strongly dependent on mineral content and bedding direction.