The Rheology of Light Crude Oil and Water-In-Oil-Emulsion

Abstract

Research on rheological behavior of crude oil emulsion is vital due to complex behavior of crude oil. Usually, crude oil emulsion is found in mixed state with solid particles, organic additives and emulsifying agents. Crude oil emulsion can be encountered during oil production, transporting or processing. The production of emulsion is a costly problem both in terms of chemicals usage to overcome the problem and production loses. In order to get a better understanding on rheological behaviour of crude oil emulsion, the rheological study of water in oil emulsion was investigated. The present paper deals with the rheological study of light crude oil from Bintulu, Sarawak and its mixture with water. This rheological study includes viscosity dependence vs. shear rate, temperature and volume water ratio. Water in oil emulsions were prepared by mixing light crude oil with different water volume fractions (20%, 30% and 40%). Rheological measurements were carried out by Antoon Paar MCR 301 rheometer operated at pressure of 2.5bar. The results showed that emulsion exhibit non-Newtonian flow behavior at low shear rate and Newtonian flow behaviour at high shear rate. Besides that, viscosity of water in oil emulsion was strongly augmented by increasing volume of water and decreased the temperature. It was noted that a large discontinuity in the viscosity occurs at volume water ratio of 30 to 40%. In the case of 100% light crude oil, the study demonstrated Newtonian behavior. However, for emulsion with different volume water ratios, the rheological studies follow non-Newtonian shear thinning behavior and were described in better way by Ostwald de Waele and Herschel-Bulkley models. As a conclusion, rheological study shows that temperature, shear rate and volume water ratio have great impacts on the viscosity of water in oil emulsion and it is important to understand these factors to avoid various costly problems.