Interstage difference of pressure pulsation in a three-stage electrical submersible pump

Abstract

Electrical Submersible Pumps (ESPs) are the key equipment for oil exploration. The hydraulic noise and vibration inside ESP are mainly induced by the internal pressure pulsation, which is an important reference index for ESPs' operational stability. The mechanism and characteristics of pressure pulsation in multistage pump is not clear until now, which is more complex and difficult than a single stage pump. In this study, based on numerical simulation and experiment measurement, the inter-stage difference of internal flow field distribution and the pressure pulsation characteristics inside a typical three-stage ESP was investigated. The numerical predictions results show a good agreement with the experiment results. Then a comparative analysis of the flow fields inside the impellers, diffusers and chambers under different flow conditions was performed. The results show that the dynamic and static interference between impeller and diffuser is the direct cause of pressure pulsations within the ESP. It found that although the geometry of the ESP is the same, the pressure pulsations within it are not identical. The pressure pulsation signal has a cascading phenomenon to a certain extent. The amplitude and phase of pressure fluctuations have interstage difference due to the coupling of pressure filed among stages. When the number of stages is high, the pressure pulsations caused by the interference phenomenon can seriously threaten the operational stability of ESP by inducing vibration and noise. This work can enhance the understanding of inter-stage flow field differences inside ESP, and provide useful insight on the subsequent improvements of ESPs’ operational stability.