WATER-IN-CRUDE-OIL EMULSIONS FROM THE NORWEGIAN CONTINENTAL-SHELF .9. A DIELECTRIC SPECTROSCOPIC CHARACTERIZATION OF AUTHENTIC AS WELL AS MODEL SYSTEMS

Properties of water-in-crude oil emulsions and model systems stabilized by interfacially active crude oil fractions or tetraoxyethylene nonylphenyl ether were analyzed using time domain dielectric spectroscopy. The amount of dispersed aqueous phase containing 5% NaCl varied from 10 to 50% by volume. The dielectric spectra were fitted to a Debye function. It was found that models based on heterogeneous mixture models could not explain the static permittivities found without a slight flocculation. In order to interpret the whole dielectric spectrum the Boned-Peyrelasse equation was numerically solved for 80 frequencies between 20 MHz and 5 GHz. A Debye function was fitted to these theoretical spectra and corresponding relaxation times were solved. The shape factors (A) obtained show the necessity of a flocculation (axial ratios 1:10) at lower water concentrations while other more symmetrical structures occur at higher water contents. (C) 1994 Academic Press, Inc.