Phase Transitions in Oil Disperse Systems and their Influence on the Thermochemical Process of Oil Dehydration

Abstract

It is established that within the temperature range of oil dehydration in the fields, a phase transition occurs in oils, accompanied by a multifold change in the particle size of their dispersed phase. The study examines the method of assessing the temperature T* at which this process occurs based on the temperature dependence of oil viscosity. It is found that with T>T*, there are two effects taking place in oils that change the stability of oil-water emulsions in two opposite directions. Specifically, the reduction of oil viscosity facilitates a decrease in emulsion stability. In turn, increased emulsion stability is promoted by a rise in the content of natural emulsifiers in the oil disperse medium at T>T* due to a phase transition with a dramatic change in the particle size of the disperse phase. Therefore, the maximum speed and degree of oil dehydration is achieved at T*, which is confirmed experimentally. As a result, the need for a critical analysis of the oil treatment temperature regime used in the fields considering phase transitions within the particles of its dispersed phase is shown.