Structure optimization and performance evaluation of downhole oil-water separation tools: a novel hydrocyclone

Abstract Based on the principle of cyclone separation and 3D printing technology, a novel variable pitch hydrocyclone structure was proposed for the axial flow hydrocyclone separators of oil wells. The structural parameters of this variable pitch hydrocyclone were optimized via a combined approach of the Plackett-Burman design, response surface design and computational fluid dynamics. A quadratic polynomial mathematical relationship between significant structural parameters and separation efficiency was established. The effects of the inlet flow rate, split ratio and oil phase volume fraction on oil-water separation performance were systematically analyzed. A laboratory test system for oil-water swirl separation was constructed to verify the accuracy of numerical simulation results and the efficiency of the optimized structure. The optimal overflow split ratio, inlet flow rate and oil concentration for the hydrocyclone are 30%,96 m3/d and 2%, respectively. The combination of these optimal parameters results in an experimental separation efficiency of 99.38%, which is higher than that of the conventional structure. The experimental results are in good agreement with the simulation results.