Study On Initial Deposition Of Bubble-Water-Crude Oil Mixed Flow

At present,most oilfields in China have entered the late stage of development.The water cut of produced fluid rises sharply with some produced gas.The mixed flow of bubble-water-crude oil in the pipeline makes the flow pattern more disorder than singlephase flow and two-phase flow.The complexity of the mixed flow makes the initial deposition process of crude oil more complex when mixed flow occurs.In order to improve the production economy and maintain the safety of oil gathering pipeline,the initial deposition process of bubble-water-crude oil mixed flow is systematically studied in this paper.Based on the complexity of three-phase mixed flow of bubbles-water-crude oil,the initial deposition process of two-phase mixed flow of ultra-high water cut crude oil and the growth law of bubble in horizontal pipeline are studied separately firstly.The effects of experimental temperature,mixing velocity and volumetric water content on the initial deposition process of ultra-high water cut crude oil were investigated.According to the crude oil’s movement pattern,initial deposition mode and pressure drop curve obtained,the initial deposition process is divided into two processes and three stages,and the law of the initial deposition is obtained too.The diameter and formation time of bubble under different conditions are obtained by changing the gas flow discharge,water flow discharge and injection pore diameter.Through the analysis of the external forces on the formation process of bubble,the force balance equation of bubble is obtained.Based on this,the prediction equation of bubble detachment diameter is established and obtained which the relationship between bubble detachment diameter and experimental parameters can be explained theoretically.The prediction equation of bubble detachment diameter shows that the characteristics of liquid and gas,gas flow discharge,water flow discharge and injection pore diameter have a very important influence on bubble formation time and detachment diameter.Based on the above researches,the dynamic process of initial deposition process of bubbles-water-crude oil mixed flow is established through theoretical analysis and experimental images.At the same time,the initial deposition law of bubble-water-crude oil mixed flow is obtained by changing the key factors affecting the gathering and transportation process,such as gas flow discharge,water flow discharge and temperature,and which provides a reference for further study the multi-phase flow of gas-water-crude oil and economical efficiency of the gathering and transportation of oilfields in high water cut period.