Investigation of Rheological Properties of water in crude oil emulsions

Water and oil can make emulsions. Oil in water and water in oil emulsions have the same behavior in general but there are less information about water in oil emulsions. Rheological properties of these systems are very important. In this research we made different samples with different characteristics, some of them had surfactant and others without it. Then we investigated the different rheological properties of such systems. We measure viscosity variation of such systems versus shear rate variations, different water volume fractions and effect of adding surfactants to these systems. It is shown that these systems have a Newtonian viscosity below a certain shear rate and pseudo plastic behavior above that. Relative viscosity increases by increasing water volume fraction but after a certain value it increases sharply until it goes to infinity at a certain value. Our investigations showed that elastic modulus is low in moderate water volume fractions after a certain volume fraction elastic modulus increases sharply that shows there is a phase transition. Moreover, we find loss and storage modulus variations versus shear rate variations. In all cases G' showed a linear behavior and then a nonlinear behavior after that.