Design And Research Of Large Flow Downhole Oil-Water Separator Unit

The two-stage tandem cyclone oil-water separation device is widely used in the oil-wells on land.This kind cyclone is limited to its own structure so that it?s not suitable for high oil yield of offshore wells.According to diameter of the casing with 9 5/8 inch and combining the offshore oil wells production,it primarily designs the oil-water separation structure of the two-stage tandem cyclone.The first stage of this structure adopts the large diameter cyclone which is 100 mm and the second stage adopts six parallel small diameter cyclones which is 40 mm.The second stage cyclone is designed in the external chamber of the first stage tail pipe.The author designs and draws the structural CAD map of the system.It uses the nodal analysis method to analyze the relationship of pressure and flow rate at the system each nodes.The passage introduces the advantages of the Les model in Fluent.Combining the Fluent,it optimizes the structure design,including the cylinder diameter,structural parameters and inlet structure of cyclone.After optimizing the cylinder diameter is 100 mm.It combines the orthogonal test method to optimize the structural parameters.And it separately studies the cyclone performance of the three different inlet structure to get results that double straight line type is better than other shape structure.The author establishes the oil-water separation system model and analyzes internal flow trajectories and the concentration distribution of oil phase in the cyclones.By modifying the operation parameters including split ratio,inlet velocity and inlet flow rate,it studies the influence to the system performance.Making sure that the total split ratio is constant and changing the first ratio,meanwhile the second ratio is also changed,it studies the relationship between the inlet flow rate and the system performance.By varying the inlet velocity and keeping the inlet flow rate not changed,it studies the relationship between the inlet velocity and the system performance.It introduces the using process and method.It uses UDF to control the inlet velocity which makes the inlet velocity into variable function.By using the optimized system model,the inlet velocity function is imported into the Fluent to be carried out,which studies the influence to the oil-water separation efficiency when the input condition is non-steady velocity.When the inlet velocity appears fluctuations,that is to say sine curve,it studies the influence to the system performance by varying frequency and amplitude of the sine curve.It also studies the effect to the system performance when inlet velocity is changed abruptly.