Study On The Flow Characteristics Of Water In Intermediate&light Oil Emulsion

In oil and gas industry,oil-water emulsion is very common which is formed in the process of oil production,transportation and processing.Rheologic characteristic of emulsion is very important for transport processes optimization,parameters design and operating conditions analysis.Therefore,this paper examines the factors that affect the rheologic characteristic of emulsion under a pipeline flow.And models for calculating viscousity and phase inversion point are established.In this paper,oil-water emulisons were tested in a circulated pipeline.The diameter of the pipeline is 25.4mm,and it is 38 m long.Three oil samples are tested.The crude oil from NO.2 and NO.6 oil production plants are intermediate crude oils,the other one is light oil.The range of experiments: flow rate ranges frome 0.5m/s to 1.2m/s,temperature ranges from 45℃ to 60℃.Following conclusions are obtained by analyzing the experimental data.The viscousity of emulsions increases with the water content before phase inversion occurs.Once phase inversion occurs,the viscousity decrease dramaticly,and it is approaching the viscousity of prue water.The viscousity of emulsions increases with the temperature.However,mixture velocity has little effect on emulsion viscosity.In addition,both temperature and mixture velocity has little effect on the phase inversion point.The data from circulated pipeline and data from rheometer were compared.The viscousity data from circulated pipeline is larger than that of rheometer.However the phase inversion point obtained from the two experiments are very different.Phase inversion occurs in pipeline is much earlier than in mixer.The average errors between two experiments for viscousity and phase inversion point are 7.53% and 57.14% respectively.Six models for calculating viscousity and five models for calculating phase inversion point were varadation with the experimental data from pipeline.It turns out that Vand correlation and Brinkman correlation are most accurate for calculating viscousity of water in oil emulsions.The errors of all models for calculating the phase inversion are large.All the calculated data are larger than experimental data.Among these models Decarre & Fabre model is most accurate,but the average error is still large.New emulsion viscosity model fully considers the influence of the temperature,and phase inversion point model takes full account of the emulsion viscosity’s influence on the droplet diameter.The oil samples of experimental verification were intermediate crude oil from Daqing and light crude oil from Dagang.The results show that new models are more accurate;the average relative error is lower than 10%.