The permittivity of different microporous systems, including sintered glass filters, Berea sandstones and reservoir rocks, was measured in the frequency range 10(2)-10(10) Hz. For each system, the natural pore wettability was modified to get two different sets of samples: those strongly oil-wet and those water-wet. The samples were saturated with a hydrocarbon oil and water at different degrees of water content. Dielectric spectra showed a conductivity contribution due to ionic carriers in addition to a Maxwell-Wagner-Sillars relaxation, active up to high frequencies. Because of the dominant role that wettability plays in the electrical response of partially saturated microporous solids, water-wet and oil-wet samples showed remarkable differences in the loss tangent spectra, as well as different times and strengths of the Maxwell-Wagner-Sillars relaxation. The dielectric spectra were analysed by using some standard models for extracting valuable information about the pore wettability. Moreover, the use of impedance measurements for in situ determination of the wettability of reservoir rocks was evaluated.
Influence of the wettability on the electrical response of microporous systems
CAPACCIOLI, SIMONE;LUCCHESI, MAURO;ROLLA, PIERANGELO;
2000-01-01
Abstract
The permittivity of different microporous systems, including sintered glass filters, Berea sandstones and reservoir rocks, was measured in the frequency range 10(2)-10(10) Hz. For each system, the natural pore wettability was modified to get two different sets of samples: those strongly oil-wet and those water-wet. The samples were saturated with a hydrocarbon oil and water at different degrees of water content. Dielectric spectra showed a conductivity contribution due to ionic carriers in addition to a Maxwell-Wagner-Sillars relaxation, active up to high frequencies. Because of the dominant role that wettability plays in the electrical response of partially saturated microporous solids, water-wet and oil-wet samples showed remarkable differences in the loss tangent spectra, as well as different times and strengths of the Maxwell-Wagner-Sillars relaxation. The dielectric spectra were analysed by using some standard models for extracting valuable information about the pore wettability. Moreover, the use of impedance measurements for in situ determination of the wettability of reservoir rocks was evaluated.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
