Research Of The Viscosity Model For Water-in-oil Emulsions Based On Sauter Mean Diameter

Water-in–crude oil is very common in petroleum industry.Nearly 80% of the oil recovery exists in the way of emulsions.Since crude oil usually contains some natural emulsifiers as asphaltene,resin and small particles,it's easy to form water-in-oil emulsion during drilling facility and transporting process.The viscosity of the formed emulsions may be great higher than the crude oil.This brings a big problem for transportation and processing.As a result,it's essentially important to predict the viscosity of water-in-oil emulsions,which would be the guidance for the management of multiphase pipeline.Water-in-oil emulsions are treated as Newtonian fluid in traditional viscosity prediction models,but water-in-oil emulsions usually express non-Newtonian behaviors at medium and high water cut.Many viscosity prediction models for emulsions are found in the published literature,but for the most part,they haven't considered the influence of drop diameter.When emulsions express non-Newtonian behaviors,the drop diameter is an important factor in the apparent viscosity of each emulsion.Through the experiments of four kinds of water-in-crude-oil emulsions,the influence of temperature,water concentration and stirring speed to drop diameterwereinvestigated.Based on the theory of drop breakage,Sauter mean diameter model is obtained by regression and the parameters in the model are determined.The influence of drop diameter to viscosity of emulsions has been further studied.Based on Richardson viscosity model,an improved viscosity prediction model is proposed,which have considered the effect of shear rate,drop diameter and water fraction.Comparison results show that the improved model can predict the viscosity well at moderate and high fraction.