Numerical Study of the Influence of Viscosity on the Performance of an Electrical Submersible Pump

Abstract

This work presents a numerical analysis on the influence of viscosity on the performance of a semi-axial electrical submersible pump (ESP) such as the ones used in offshore petroleum production. A single stage composed of an impeller with seven blades and a diffuser with seven vanes is considered. Flow simulations for water and other fluids with viscosities ranging from 60 to 1020 cP were performed with the aid of Computational Fluid Dynamics, and both design and off-design flow rates and impeller speeds were investigated. The numerical model was validated with experimental measurements of the static pressure difference on a given stage of a three-stage ESP system. Results showed good agreement between the computed and the measured pressure difference values. Analyzes of the water flow inside the pump revealed that the flow is blade-oriented at the best efficiency point as expected, while large separation zones are found in the impeller and diffuser channels for part-load conditions. However, flow is not strictly blade-oriented at the best efficiency point for fluids other than the water. Examination of performance for water and fluids with higher viscosities shows that similarity laws are restricted for water, and that the best efficiency point is shifted when considering viscous fluids. Also, head values for viscous fluids are degraded not just due to viscosity and high flow rates, but also with rotor speed. The flow pattern analysis and the results found may provide useful information for engineers concerned with highly viscous fluid pumping and, possibly, shed some light on the understanding of more complex phenomena associated with actual offshore oil production operations such as multiphase pumping of viscous fluids.

Effect of blade number matching of impeller and diffuser in high-speed rescue pump

“…The author also gave an identification of the separation zones. Sirino et al 11 used CFD to study the influence of viscosity on the flow in one-stage submersible pump and found that the head curves calculated coincided with the experimental data for a wide range of viscosities. In addition, Stel et al 12,13 pointed out that CFD simulation with multistage electric submersible pumps (ESP) geometries agreed with the experimental results better than those based on single-stage pump.…”

Numerical investigation of the effect of viscosity in a multistage electric submersible pump

“…Some flow aspects between simulations with water and a more viscous fluid were compared. The authors observed that the head curve instabilities found by Sirino et al (2013) were greatly reduced with the three-stage numerical model. The performance throughout each stage was compared, showing that there are significant differences in the pressure gain provided by each stage.…”

“…The author analyzed a combination of several analytical models to predict the pressure loss in different parts of the centrifugal pump. Sirino, Stel, and Morales (2013) numerically studied the performance of a single stage of an ESP. Large instabilities in the water head curves were observed, which were explained by the authors as a consequence of using only a single stage in the simulations.…”

Research Progress and Prospects of Multi-Stage Centrifugal Pump Capability for Handling Gas–Liquid Multiphase Flow: Comparison and Empirical Model Validation

“…Thus, CFD analysis has also played a significant role in the oil and gas industry for viscosity analysis. Many scholars, such as Shojaeefard [101,102], Sirino [103], Stel [104,105], Zhu [77], Zhang [78], Basaran [106], Ofuchi 2017 [107][108][109][110], Valdes [79], have applied different types of CFD techniques to analyze both single-phase and two-phase flow performance of pumps handling viscous fluids. Using the SST k-ω turbulence model, Shojaeefard et al [101,102] have performed CFD simulations to examine the influence of viscous fluids on working capability of centrifugal pumps.…”