Electrorheological Characteristic of Heavy Oil Emulsions under High-Frequency/High-Voltage AC Electric Field

Abstract

We experimentally explored the electrostatic demulsification performance of water-in-heavy oil emulsion under a high-frequency/high-voltage AC electric field by considering some factors such as the shearing rate, water content, temperature, electric field strength, pulsatile frequency, demulsifier types, and concentration. Relative viscosity reduction of heavy oil is used as the evaluation index for demulsification performance. The results indicated that the phase inversion point of the heavy oil emulsion is between 40 and 50%. The demulsification performance can be improved by increasing the shearing rate if it is within the limited range. The optimum shearing rate in this experiment is around 100 s–1 with the corresponding relative viscosity reduction of 64.7%. There exist optimum electric field strength (2 kV/cm) and frequency (2 kHz) for the electrostatic demulsification of heavy oil emulsion with water content 30% and temperature 60 °C. The relative viscosity reduction can be up to 67.5% under optimum electric field parameters (2 kV/cm, 2 kHz). Six different types of demulsifiers used in this experiment all contribute to reducing the viscosity of the heavy oil emulsion. Among them, the type C demulsifier shows the best viscosity reduction effect. The relative viscosity reduction could be up to 76.39% with the combination effect of high frequency/high voltage AC electric field. The viscosity reduction effect is proportional to the demulsifier concentration. These findings can help to optimize operating parameters for the crude oil dehydration devices to achieve best separation performance in heavy oil fields.