Design And Analysis Of Two-stage Series Hydraulic Cyclone Oil-water Separation Oil Production System For Mechanical Pumping

After the oilfield enters the high water cut production period,the economic benefit of oil production becomes lower and lower due to the lifting and treatment of a large amount of produced water.The emergence of downhole oil-water separation technology creatively solves the problem of"water control".Downhole oil-water separation system(DOWS)is an organic combination of the existing oil well lifting system and downhole oil-water separation technology to form the same well injection-production system.Because of foreign businessmen keep the secret of downhole oil-water separation technology,and at present our oilfields have entered the middle and high water cut stage,the self-study of this new technology has important practical significance.Based on the shortcomings of downhole oil-water separation system of electric submersible pump and gravity pump,the two-stage downhole oil-water separation and production system for pumping in combination with the actual situation of oil fields in China are proposed.The following aspects are studied for downhole oil-water separation and production system:1)The research results and development status of downhole oil-water separation system at home and abroad are comprehensively analyzed.Reference basis is provided for the design and installation of domestic high water cut oil well implementation system.Combining with the actual situation of oil wells in China,a two-stage tandem oil-water separation production system is proposed.2)Study on the theory of droplet breakage in the operation of liquid-liquid oil-water separator,deduce the critical flow formula of liquid-liquid oil-water separator under certain geometric parameters,and provide a reliable theoretical basis for the output analysis of system wells and the structure design of oil-water separator.3)The coordinated relationship of various parameters of two-stage series oil-water separation production system in downhole pumping unit is analyzed by nodal method,and an integrated injection-production pump is designed.The pump connects a production pump and a water injection pump in series.At the same time,the separated oil-phase flow channel and the separated water-phase flow channel of the separated oil production system are designed in detail.According to the classical Colman-Thew cyclone model,a two-stage series oil-water ion system is designed,and the two-dimensional connection diagram of the injection-production integrated pump and the two-stage series oil-water separator subsystem are given.4)Combining with the actual working conditions,the movement law of the plunger in the upper stroke of the pump is studied.The flow rate corresponding to five special positions is selected as the boundary condition of the inlet velocity of the separator subsystem,and the separating efficiency of the separator is studied when the pump works.5)Through FLUENT software,the structure parameters of the designed single stage separator are simulated and analyzed,including the length of the tail pipe section,the shape of the inlet,the inner diameter of the overflow orifice,the length of the cylinder section,the size of the cone angle,as well as the operating parameters of the separator,such as the inlet velocity of the separator and the water content of the well fluid,etc.The separation efficiency of the separator and the oil concentration of the underflow orifice are taken as important parameters.Optimization.6)Flow field of two-stage series oil-water separator is simulated and analyzed by using the validated numerical simulation method.Flow field distribution in two-stage series oil-water separator is studied,and the influence of well water content and separator inlet velocity on separation performance of two-stage series oil-water separator is analyzed.Through the research,a new type of high water cut well production and injection system is put forward.The oil-water separation and production system of two-stage tandem downhole pumping is designed and analyzed in depth,which provides theoretical basis for further research,and also provides certain reference and guidance for other types of production and injection system research.