Impedance spectroscopy in asphaltene-toluene and maltene-toluene solutions of crude oils from the Orinoco Belt

Abstract

In this investigation, an impedance and dielectric spectroscopy study was carried out on Asphaltene-Toluene and Maltene-Toluene solutions, prepared from two oil samples from the Orinoco Oil Belt that presented low resistivity at the depths of the oil well where petrophysical logs were taken. The purpose of this work is to investigate whether the asphaltenes and maltenes would be responsible for the low resistivities found in the logs. A Lock-In amplifier, an impedance analyzer, and a coaxial cylindrical cell were used to obtain the impedance measurements. From the plotting of the impedance and phase angle parameters, it was confirmed Asphaltene-Toluene solutions were the least resistive. A fit of the experimental data based on an electrical circuit was realized, finding good correspondence between the experimental data and the fit line. The AC conductivity values were plotted using the fitting data, and it was observed that the Asphaltene-Toluene solution is more conductive. A remarkable difference in the electrical behavior was found between the maltene solutions of both crude oil samples .