Tanmay Sanjiv Tatu (Master of Science in Petroleum Engineering)
Experiments and CFD simulations of sand erosion and impact on performance of Electrical Submersible Pump (ESP)
Conclusions and Recommendations
Artificial lifting is the process of providing external energy to producing wells when the natural drive of the reservoir is insufficient to produce fluids by itself. Among different lifting methods, Electrical Submersible Pumps (ESPs) are one of the most widely used in the oil and gas industry. However, ESPs are very susceptible to the presence of gases or solid particles like sand, which heavily affect the pump performance and run life. The maintenance and overhauling of an ESP in a producing well are not economical, thus extending or maintaining its operational life is important. Predicting the degradation in the pump performance is crucial in estimating the workability and overall life of an ESP.
To evaluate the sand effect on ESPs, sand erosion testing was performed at the Tulsa University Artificial Lift Projects (TUALP) experimental site on two multi-stage mixed flow (14-stage ESPI and 8-stage ESP2).
The testing was carried out at their individual Best Efficiency Points (BEPs) at 1750 BPD and 6000 BPD, respectively, for a total of 64 hours/per pump in intervals of 8, 8, 16, and 32 hours. The sand was replaced every two hours, and the flow loop was flushed with water to get rid of any residual sand, dust, rust, or unwanted particles before starting the next test.
The performance parameters such as head, efficiency, and horsepower were measured before and after each test interval to observe the change in hydraulic performance. After each test interval, the pump was removed and opened to observe the dimensional changes and weight loss of its internal parts.
It was observed that over the entire 64-hour test period, the head of both pumps reduced by 15%, and the efficiency decreased by 7-15%. The geometry also showed a clear trend of change over the testing. The seal clearances increased by almost 10 times the original value. The weight loss in the stages ofESP2 was much more than the stages in ESPI , possibly due to the much higher operational flow rate in the former. The results of testing such as the dimensional changes and performance parameter deterioration are presented in detail in this paper. The results are comparable with previous similar experiments. This study validates the previous experiments and the data presented help better understand the wear and process of erosion in ESPs and predict the change in performance over a set period of operation of the ESPs under a sandy flow environment.