Impact of ionic-electromagnetic field interaction on Maxwell-Wagner polarization in porous medium

Abstract

The brine composition of porous media and its effect on the polarization properties of the sandstone reservoir is important for understanding the mechanism of oil detachment from the grain surfaces and its movement through the reservoir channel. The mechanisms by which aqueous ions interact with the reservoir minerals via interfacial, ionic, dipolar and electronic polarization has been the subject of many researches. Moreover, the differential effects of cations and anions (polarization mechanisms) on fluid mobility under the influence of EM field are not been fully elucidated. Also, the complexity of reservoir response with the presence of oil and saline water to electromagnetic wave is not well understood. This study employs the wide frequency window polarization model to determine the influence of the concentration of adsorbed ions on reservoir rock properties. Berea sandstone was saturated with crude oil and different concentrations of NaCl solutions (3000, 5000, 7000, 9000 and 11,000 ppm). The result reveals that at 11000 ppm, we have a strong wavelength shift with 6.8 nm at 11.2 GHz for Ionic and 6.1 nm at 11.8 GHz for electronic polarization. It was deduced that Impedance is frequency dependent, which indicates a positive effect of electromagnetic field interaction on oil mobility. The increased in concentration of the electrolyte (NaCl), the polarization in the diffuse layer is stronger than that of stern layers due to better ionic distribution, as well as the van der Waals and intramolecular forces of attraction contribute to more adsorption energy in the porous media. The additional negative ions enable better dispersion due to relaxation, resulting from dielectric polarization and electrophoretic mobility with frequency.