The Research And Design Of ESP Downhole Oil-water Separation With Fixed String And Adjustable Underflow

Downhole oil-water separation technology is an efficient, environmental friendly, energy-efficient technology,but its device structure is complex, unadaptable, cost higher problem has always restricts the development of this technology. To solve these problems this paper puts forward several new type of design scheme of downhole oil-water separation system, which include the use of electric submersible or ground drive mode with centrifugal pump or screw pump. These new schemes promote the further development of downhole oil-water separation.First, this paper conduct node analysis of the downhole water-oil separation system, relying on each code,the coordination of the various parts of the system to achieve the desired workflow.On this basis,it introduces some schemes ,which include the electric submersible pump,electric submersible screw pump and the surface driving screw downhole oil-water separation system,and introduces the major downhole oil-water separation system components,including pump units in series and dual-stage hydrocyclone.Secondly,the introduction of the downhole oil-water separation string structure and related technology are described.This focuses on the desgin scheme of adjusting underflow mechanism,and introduced the working principle of each part of the underflow control structure.Third,basing on computational fluid dynamics software FLUENT,this paper simulates the flow field of the downhole dual-stage hydrocyclone.Through the simulation of single-phase flow field,it obtains the regular pattern of velocity and pressure distribution with single-conic and double conic hydrocyclone respectly.The pressure drop correlation of dual-stage hydrocyclone is also obtained.Through comparision of simulation results with different split ratio and flow rate,it is to be known that operating parameters influence the flow field pattern notably.Through adding multiphase model,two-stage flow field is simulated,and the separation performance of dual-stage hydrocyclone is evaluated.At last,through the ground test and the analysis of split ratio,flow rate on oil content of the underflow,useful cinclusions are obtained.As the last step before the application,downhole oil-water separation system ground test is necessary.