海上油井用井下水力旋流器数值仿真研究

Research on Offshore Downhole Hydrocyclone Based on Numerical Simulation

在海上油井旋流器结构优化设计问题的研究中,由于海上油井产液量大,需要配置能适应高产液量的井下水力旋流器,提高油水分离效果。针对传统方法无法指导高流量旋流器设计选型的问题,应用流体力学原理,进行数值仿真方法研究。针对井下水力旋流器的结构形式,提出一种结构化网格划分方案,在满足网格质量要求的前提下降低了计算时间。通过分析仿真结果,得到旋流器内流场速度分布、压力分布以及油相体积浓度分布规律,揭示了油水两相流的分离特性,并且在高流量范围内,计算出了底流含油浓度-流量、能耗-流量的关系曲线,计算结果与实验数据吻合较好,说明了数值仿真的可靠性,同时也为进一步研究海上油井用高流量井下水力旋流器的内流场特性及结构优化设计提供了一条有效途径,为井下油水分离技术在海上油井的应用打下了基础。

High output is a significant feature of offshore oilfield, which drives new requirements for the configura- tion of downhole hydrocyclone. However, design theoretical model related to high feed flow-rate hydrocyclone is not perfect and the lack of semi-empirical model is another constraint. In this paper, Computational Fluid Dynamic （CFD） was used to conduct the research. According to the structural features of hydrocyclone, structured grid was applied to discrete calculation domain which meets quality requirements and reduces computing time simultaneously. Simulation results reveal distributing characteristics of velocity, pressure and volume fraction inside the hydrocyclone. Curves of flow rate against separation efficiency and against energy dissipation were obtained through simulation. This research shows that the simulation results fit the experimental datas very well. This will establish the basis for the off- shore use of DOWS.