Study On Characteristics And Mixture Viscosity Model Of Oil-Water Two Phase Flow

Oil-water two-phase flow is commonly encountered in the petroleum and chemical industries.Due to the turbulent action and shearing action,it is easier to form stable water-in-crude oil emulsion.Oil and water two-phase flow is studied in a horizontal flow loop with 25.8 mm inner diameter and overall length of 30.8 m.The main contents and conclusions of research are followingIn this study,flow patterns are identified with the methods of visualization shooting,optical microphotograph,local sampling,and pressure gradient testing.According to the pressure drop characteristics of each flow pattern,the flow patterns can be classified into oil dominated flow and water dominated flow.The oil viscosity can determine the type of flow pattern.As for the oil dominated flow,the flow patterns of three different oil are the same,which including E w/o flow and E w/o&w intermittent flow.Besides,the pressure gradient of intermittent flow exhibit periodic characteristics with severe fluctuation.In addition,there is a difference in the flow pattern of the water dominated region.Oil-in-water emulsified flow,which commonly appeared in low-viscosity oil-water two-phase flow,is not observed in medium&high-viscosity oil-water two-phase flow.Instead,D(E w/o)/w flow and E w/o&w core-annular flow are encountered.Moreover,the oil viscosity would also affect the flow pattern transition.The critical water fraction decrease with the increase of oil viscosityBased on the flow patterns and their transition characteristics,the effect of different oil-water two-phase flow parameters and oil viscosity on pressure gradient,inversion characteristics and water droplet size are analyzed.The essence of the effect on pressure gradient and inversion characteristics is that the parameters and oil viscosity could influence the flow patterns and their transition characteristics.When flow pattern transition occurs,the critical water fraction can be reduced with the increase of mixture velocity and oil viscosity,which is conducive to promote the phase inversion.Compared with oil dominated flow,the pressure gradient of water dominated flow is smaller.The water fraction and temperature have little effect on the pressure gradient of water dominated flow,particularly in annular flow.Thus the water dominated flow should be given priority to when it comes to the transportation of crude oil and water.The essence of the effect on water droplet size is that the parameters and oil viscosity could influence the breakup and coalescence of water droplets Rising temperature and water fraction weaken the shearing action of continuous phase and promote the collision and coalescence of water droplets.Then the Sauter mean diameter of water droplets becomes larger.The shearing action imposed on the dispersed phase is intensified as the mixture velocity increased.Then the water droplet size becomes smaller When the continuous phase is oil phase,the water droplet size is smaller with the higher oil viscosityA method for modeling the viscosity of water in oil emulsion with simple application and applicability is proposed,with which three factors,such as multiphase flow,micro particles and non-Newtonian behavior,are related.The viscosity of oil and water mixture in pipes can be accurately acquired according to some simple variables,including water fraction,oil viscosity and water droplet size.The realization of this goal is not only of great engineering significance,but also of great importance to the development and improvement of multiphase flow theory and rheology of crude oil.