Mechanism of High Stability of Water-in-Oil Emulsions at High Temperature

Abstract

Thermal flooding by steam injection was a traditional method for exploiting heavy oil. The produced liquid was a highly stable water-in-oil or oil-in-water emulsion in several oilfields. In this work, we focused on studying the effect of high temperature on the stability of an emulsion system involving two typical crude oils (heavy crude oil and light crude oil) and brine. It was impossible to directly measure the interfacial viscoelastic modulus because of the high viscosity of the heavy oil. In order to solve this problem and analyze the contribution of those fractions to the formation of stable emulsions, the heavy crude oil was divided into three cuts: remaining fraction, resin, and asphaltene. The model oils were prepared from the mixture of several heavy crude oil fractions with kerosene:xylene (1:1 v/v) to investigate the high-temperature behaviors of their emulsions. The stability was evaluated through a high-temperature–high-pressure (HTHP) visual pressure–volume–temperature cell, and a temperatu...