Electrical spectroscopy of porous rocks: a review-II. Experimental results and interpretation

Abstract

In the frequency range from millihertz to hundreds of megahertz, many different physical and physico‐chemical processes contribute to the electrical polarization of porous water‐bearing rocks. This makes the interpretation of their electrical spectra a complicated problem and requires both elaborate theories and model experiments. At high frequencies, the Maxwell–Wagner–Bruggeman–Hanai (MWBH) theory of effective media, which takes into account only bulk properties, shape and partial volume of components, is very appropriate. At low frequencies, surface films, polarization of the electrical double layer (EDL) and clustering of conductive components can produce very strong polarization; corresponding theoretical models are considered in a companion paper (Chelidze & Gueguen 1999, hereafter referred to as Paper I). This paper is devoted to the review of experimental data and their comparison with theoretical models. Experiments on saturated mineral powders and rocks with various surface areas and surface chemistries confirm the existence of significant surface contributions to the electrical spectra of conductivity and polarization of water‐bearing rocks and the dominance of this contribution over MWBH values at low frequencies. The effective dielectric constant of porous saturated rocks increases with the surface‐to‐volume ratio of the system and strongly depends on the surface charge (ζ potential). At ζ potential, equal to zero, the low‐frequency dielectric permittivity (DP) is minimal. The experimental data on relaxation times and the magnitude of the surface polarization of water‐bearing porous systems can be satisfactorily explained by theories of film polarization, diffusional polarization generated by deformation of an ‘open’ electrical double layer (EDL) and percolation.

Frequency-Dependent Electrical Characterization of Rock Types from Ewekoro, Eastern Dahomey Basin, Nigeria

“…This is reflected in the upward shift in the frequency that separates the plateau and dispersion regions, which is 1.73-129 kHz for sandstone; 2.03-129 kHz for limestone, 103-139 kHz for glauconite, and 61.6-174 kHz for shale. The increase in r   is related to interfacial polarization and electrochemical processes developed at the interfaces between rock mineral and electrolytic solutions 25,26 . Also, water itself has a high dielectric permittivity.…”

“…As a result of their sensitivity to ionic content and surface texture, dielectric measurements of saturated rocks exhibit frequency dispersions of dielectric properties 23,24 . In addition, surface contributions due to solid-liquid interface and clustering effects have to be taken into consideration for the determination of electrical properties [25][26][27] . Frequency-dependent properties of materials result from different mechanisms of charge transport and charge storage.…”

Induced Polarization with Electromagnetic Coupling: 3D Spectral Imaging Theory EMSP Project No. 73836

“…It appears that at an interm range of between 35% and 85% saturation, polarization response are kept near the peak, while outside this range polarization is severely attenuated by saturation. There are a number of studies of the effects of saturation on polarization response (Vinegar and Waxman, 1984;Chelidze et al, 1999b; Ulrich and Slater, 2004) and it appears that th effect is related to both the effective electrical properties of the EDL ions and the pore/pore-throat distribution. , 1997a) and large wall counterion charg density, 0.5-1.0 Coulombs/ m 2 , suggest that they might impact directly on polarization behavior of contaminated rocks/soils.…”

Electrical impedance spectroscopy measurements to estimate the uniaxial compressive strength of a fault breccia

“…Numerous researchers, especially those working in geophysics area, have investigated the electrical conductivity or resistivity of rocks in the laboratory for many years (Archie 1942;Brace et al 1965;Collett and Katsube 1973;Vinegar and Waxman 1984;Schmeling 1986;Jodicke 1990;Shankland and Waff 1997;Chelidze et al 1999;Shogenova et al 2001;Ara et al 2004;Kaselov and Shapiro 2004). However, a few researchers have attempted to correlate resistivity with rock properties.…”