Effect Of Micro Properties On Wax Deposition Of Water-in-oil Emulsion

Waxy crude oil is easy to form water-in-oil emulsion and produce wax deposition in the deep multiphase pipeline.The dispersed phase droplets will affect the process of wax molecular diffusion.Therefore,it is really significant to carry out research on the wax deposition of emulsion for ensuring the safe operation of pipeline.This paper studies the micro properties of emulsions in different water cuts and different stirring conditions.The quantitative characterization of dispersed phase droplet size and distribution of emulsions are realized.The results show that the distribution curves of dispersed phase are unimodal in a certain range.And the droplet diameter corresponding to the peak of the curve is in the range of 1.5?m to 2.5?m.With the increase of water cut,the total number of the emulsion droplets increase and the average diameter of droplets decrease.When the water cut increases from 10% to 40%,the polydispersity of emulsion in three different stirring conditions decrease by 3.58%,18.25% and 7.09% respectively.In addition,it is found that the total number of droplets grew with the rise of stirring speeds,while the average diameter of droplets decreases.What is more,the dispersion degree and the homogeneity of emulsion systems are both enhanced.Cold finger experimental apparatus is used to study the effect of water cut,temperature difference and deposition time on wax deposition of emulsion.The Fluent software is used to simulate the distribution of temperature field around cold finger.It is found that the wax deposition rate,temperature gradient and wax molecular diffusivity all decline with the increase of water cut but increase with the growth of temperature difference.With the increase deposition time,the wax deposition rate and temperature gradient are both reduced.And the wax molecular diffusivity is increased.Furthermore,the shorter the deposition time is,the greater will be the effect of water cut and temperature difference.Based on the exploration of the effect of droplet size and distribution on wax deposition,mathematical formula are proposed which reveal the relationship of emulsion wax molecular diffusivity with emulsion viscosity,water cut and polydispersity.The average relative error is 3.40%.