Research On Solid-liquid Flow Character In Downhole Hydrocyclone Desander

When oilfield enters high water-cut stage, long-term water-flooding development hasdestroyed formation cementation. Simultaneously, applications of new technologies, such asfracturing with sand propping agent, polymer flooding and ternary compound flooding, etc.,increase the carrying-sand ability of produced liquid. Sand production phenomenon hasbecome severer than before, which makes the oil layer buried or p?mps stuck. Sand of fluidproducing has become one of the important issues that affect oilfield stable production. Thehydrocyclone separation and settlement separation influence each other which changes theflow field distribution and working state of hydrocyclone because the bottom flow outlet ofdownhole hydrocyclone desander immerses in the downhole liquid. Downhole hydrocyclonedesanding has some characteristics, such as large medi?m viscosity, narrow radial work spaceand hard to adjust split ratio. It would be difficult to obtain satisfactory separation effect if weuse the existing solid-liquid hydrocyclone structure for downhole desanding directly.Therefore structure design and separation performance study of downhole hydrocyclonedesander were carried out for this problem in this paper.Thinking of the hydrocyclone separation and sedimentation separation in downholehydrocyclone desander research, a new type of downhole hydrocyclone desander wasdesigned which had a closed bottom flow and single exit. The desander combines doublespiral diversions with cone separation and can achieve spiral flow in a narrow radial space,and provide symmetrical and stable intense-rotating flow field for centrifugal separation.The numerical simulation research of downhole hydrocyclone desander flowcharacteristics has been carried out basing on Euler-Euler method and RSM turbulence model.In Euler-Euler method, the liquid phase and solid phase were treated as continuumsthroughout each other and calculated the interaction influence of solid-liquid and solid-solidof downhole hydrocyclone desander. High precision discrete format were useded for controlequation discretization. By the numerical simulation, influence laws were studied andobtained of structural parameters, inlet velocity, produced liquid viscosity, sand phase size andconcentration on internal flow field characteristics and separation performance of two phasemedium. The best structure parameters of the desander was optimized and the suitable working conditions and appropriate operating parameters of desnader were finally defined.According to the actual application conditions in the field and the result of thenumerical simulation, an LDV test and separation performance test equipment of downholehydrocyclone desander were set up and took the velocity measurement with single outlethydrocyclone and ordinary double outlet hydrocyclone at different flow rate. Compared theflow field test results with numerical simulation results,it showed that they shared the samediscipline basically although there were some deviations. So the numerical calculation modelbuilded was available for numerical simulation research of downhole hydrocyclone desanderinternal flow law.The indoor separation property test research of downhole hydrocyclone desander hadbeen carried out according to the orthogonal experiment method. The primary and secondaryfactors and relationship which affected the separation of hydrocyclone were determined. Onthis basis, analyzed the influence law of different physical parameters and operatingparameters on hydrocyclone separation property.The comparative analysis on numericalsimulation and the test results were conducted. The separation efficiency and pressure droptrend of measured values were similar to the numerical simulation. Both of the errors waswithin20%, which proved that the established numerical simulation method can be used forthe prediction of downhole hydrocyclone desander separation performance.