Effect of Frequency and Temperature on Rock Dielectric Properties.

摘要

The real and imaginary components of dielectric constant were determined for basalt,granite and quartzite in the frequency range 10MHz to 4GHz. The variation of dielectric permittivity with temperature was determined from room temperature to 450C. No dielectric dispersion or rock relaxation was observed in the frequency range investigated. Hence,the rock relative dielectric constant and relative loss showed mild variation with frequency with no discontinuity or sharp peaks as those previously observed in the low frequency range (up to 2KHz). The temperature coefficient of the relative dielectric constant was related to the isobarric thermal expansion coefficient of the rock. The relative dielectric loss of basalt and granite followed an Arrhenius exponential increase with temperature suggesting the loss mechanism to be associated with activated particulate diffusion in the rock lattice. Activation energy for the conductance process depended on the temperature range and appeared to be independent of frequency. Quartzite showed an anomalous temperature variation of its conductivity. (Author)