Thermal conductivity anisotropy of metasedimentary and igneous rocks

Abstract

[1] Thermal conductivity anisotropy was determined for three sets of metasedimentary and igneous rocks from central Utah, USA. Most conductivity measurements were made in transient mode with a half-space, line source instrument oriented in two orthogonal directions on a flat face cut perpendicular to bedding. One orientation of the probe yields thermal conductivity parallel to bedding (k par ) directly, the other orientation of the probe measures a product of conductivities parallel and perpendicular to bedding from which the perpendicular conductivity (k perp ) is calculated. Some direct measurements of k par and k perp were made on oriented cylindrical discs using a conventional divided bar device in steady state mode. Anisotropy is defined as k par /k perp . Precambrian argillites from Big Cottonwood Canyon have anisotropy values from 0.8 to 2.1 with corresponding conductivity perpendicular to bedding of 2.0 to 6.2 W m À1 K À1 . Anisotropy values for Price Canyon sedimentary samples are less than 1.2 with a mean of 1.04 although thermal conductivity perpendicular to bedding for the samples varied from 1.3 to 5.0 W m À1 K À1 . The granitic rocks were found to be essentially isotropic with thermal conductivity perpendicular to bedding having a range of 2.2 to 3.2 W m À1 K À1 and a mean of 2.68 W m À1 K À1. The results confirm the observation by Deming [1994] that anisotropy is negligible for rocks having k perp greater than 4.0 W m À1 K À1 and generally increases for low conductivity metamorphic and clay-rich rocks. There is little evidence, however, for his suggestion that thermal conductivity anisotropy of all rocks increases systematically to about 2.5 for low thermal conductivity rocks.

Anisotropic thermal conductivity of natural Boom Clay

“…This function was used to compare the experimental results with the changes in probe orientation. The data of Davis et al (2007) agree reasonably well with Eq. (8).…”

“…(6) was used by several authors (Davis et al, 2007;Gong, 2005;Munroe and Sass, 1987;Penner, 1963;Popov et al, 1999;Popov et al, 2012;Pribnow et al, 2000;Riche and Schneebeli, 2012) to determine the thermal conductivity in the direction perpendicular to bedding λ ⊥ based on the measurements of λ 90 and λ 0 in different materials (clay sediments, igneous rocks, snow, etc. ).…”

“…(8) was firstly proposed by Pribnow (cited by Davis et al, 2007). This function was used to compare the experimental results with the changes in probe orientation.…”

Evaluation of geothermal gradient and heat flow distribution in Delta State, Nigeria

“…Other reasons are the thermal properties of the drilling fluid, nature of heat exchange between borehole and the well, duration of drilling and non equilibrium temperature at the time of temperature measurements on the formation. Several methods to correct this pit fall have been proposed by many authors such as the correction made by Davies et al [8]. It is a well established fact that temperature increases with depth in the earth.…”

Numerical analysis on thermal conductivity of poly-mineral rock

“…Various geophysical parameters of lithosphere including the state of rock rheology, thermal structure and heat flow are all closely related to the thermal conductivity characteristics of the lithosphere rocks (Abdulagatov et al, 2006). In recent years, the study on the rock's thermal conductivity is one of the important issues to petrophysicist (Liu et al, 2005;Aurangzeb et al, 2006Davis et al, 2007;Jessop, 2007).…”