Experimental determination of frequency- and temperature-dependent electrical properties of water-saturated clays using spectral induced polarization and network analyzer technique.

• Electrical properties of two saturated clays were investigated in the temperature range 25 °C down to 0 °C. • Impedance analyser measurements (mHz to kHz range) were combined with Vector Network Analyzer measurements (MHz to GHz range). • Temperature effect on typical geophysical quantities was modelled with a mixture approach. Impedance and vector network analyzer measurements are combined in order to measure frequency dependent conductivity and permittivity of two different saturated clays: montmorillonite and illite chlorite. In the low frequency range, the complex conductivity is determined over the 10 mHz to 45 kHz frequency range using a complex impedance analyzer with a 4-electrodes cell. In the high frequency range (50 MHz to 5 GHz), the complex permittivity is obtained from measured reflection factor of an open-ended probe. The ultrabroadband constitutive properties of the saturated clays were investigated in the temperature range 25 °C down to 0 °C. A mixture equation, based on a volume average approach, was applied to model the low and high frequency electrical properties based on the formation factor. The temperature dependency was considered in the following petrophysical quantities: low frequency conductivity, chargeability and high frequency permittivity. The modeled results are in reasonable agreement with measurements. [ABSTRACT FROM AUTHOR]