The Effect of Additives and Temperature on the Rheological Behavior of Invert (W/O) Emulsions

The main aim of this research is to study the effect of temperature on the rheological properties (yield point, plastic viscosity and apparent viscosity) of emulsions by using different additives to obtain the best rheological properties.Twenty seven emulsion samples were prepared; all emulsions in this investigation are direct emulsions when water droplets are dispersed in diesel oil, the resulting emulsion is called water-inoil emulsion (W/O)invert emulsions.These emulsions including three different volume percentages of barite with three different volume percentages of emulsifier and three different concentrations of asphaltic material under temperatures (77,122 and 167) °F. The rheological properties of these emulsions were investigated using a couett coaxial cylinder rotational viscometer (Fann-VG model 35 A), by measuring shear stress versus shear rate. By using the Solver Add in Microsoft Excel®, the Bingham plastic model was found to be the best fits the experimental results. It was found that when the temperature increased, it causes a decrease in the rheological properties (yield point, plastic viscosity and apparent viscosity) of emulsions which due to the change in the viscosity of continuous phase of emulsion which is
diesel oil. Also it was found that the effect of additives on rheological properties of emulsions as follow: the increase in the concentration of asphaltic material tends to increase the rheological properties of emulsions, the increase in the volume percentage of barite tends to increase the rheological properties of emulsions and the increase in the volume percentage of emulsifier has a little effect on the value of rheological properties, but it increased the stability  of emulsions with temperature because it surrounded water droplets.