Temperature dependence of thermal diffusivity and conductivity for sandstone and carbonate rocks

Abstract

Thermal diffusivity and conductivity of sandstone and carbonate rocks are essential parameters for modeling surface heat flow and thermal regimes in sedimentary basins. The temperature dependence of the thermal diffusivity (D) of dolomite, limestone, Carrara marble, and four types of sandstone was studied using the laser flash technique, which is accurate (±2%) and isolates the lattice component from the direct radiative transfer, at temperatures up to 973 K. At room temperature, D was 2.62, 1.34, 1.22, and 1.30–2.22 mm2 s−1 for the dolomite, limestone, Carrara marble, and sandstone samples, respectively. The sandstone D correlated strongly with the quartz content of the samples. D of all the samples decreased monotonically to 0.30–0.62 mm2 s−1 at 973 K. The results were compared with laser flash analysis data from previous studies. Combining these results with the heat capacity derived from modal mineralogy and the measured density, we obtained the thermal conductivity (k). The measured k was near or lower than that calculated from the rock’s mineral components using structural models. This suggests that thermal conduction is more complicated than that represented in the models, and that in situ measurement is essential to accurately obtain the thermal conductivity of rocks. Finally, the calculated temperature-dependent k value was used in the heat flow calculation for the sampled rock.