Design of an axial hydrocyclone for preliminary water separation using CFD, RSM, and SUS

Preliminary water separators can effectively solve the problem of high-water-cut produced fluids in oil wells. In this study, we propose a co-design method for the serialization of an axial inlet preliminary water separator based on the combination of cyclone separation theory, computational fluid dynamics (CFD) simulations, response surface method (RSM) optimization, experimental verification, and a scale-up strategy (SUS). For an inlet water cut ≥ 70%, the water separation rate was ≥ 50% and the oil concentration of heavy phase outlet (HPO) was ≤ 1000 mg/L. The indoor experimental results indicated that the performance of the preliminary water separator could achieve better results obtained through the CFD simulation results were taken as sample points and the optimal structural size was found by machine learning method (MLM). The field pilot test results showed that the Hy similarity criterion based SUS did not affect the separation effect. For water cut in the range of 85.0–92.7%, the water separation rate was ≥ 50% and the HPO oil concentration was < 1321.6 mg/L. Our results can provide reference and guidance for the design and optimization of hydrocyclones for preliminary water separation of oilfield produced fluids.