Rotordynamic and Erosion Study of Bearings in Electrical Submersible Pumps

Abstract

Electrical Submersible Pumps (ESPs) are widely used for oil production. Reliability studies of ESPs are important to increase their life span, thus improving profits. Experimental data of a 185-hour erosion on a WJE-1000 ESP has been analyzed. The eroded bearings are inspected in micron scale with a certain time interval. It shows that bearings and seals in the ESPs are the main factors causing vibrations and failure of the ESP systems. To better understand the rotordynamic behavior and material fatigue of the bearings/seals in ESPs, a vertical bearing/seal test rig is built. The test rig simulates the motion of rotating components in a WJE-1000 ESP and conducts multi-phase erosion experiments efficiently with water, air and sand. Experiments on plain journal bearings with different radial clearances, mass imbalances, and multi-phase flows are conducted using the bearing/seal test rig.

Computational Fluid Dynamics (CFD) simulations are performed to study the fluid zone in the journal bearings. A Fluid Structure Interaction (FSI) simulation based on Fluent and MATLAB is proposed. It predicts the transient motions of the rotor-bearing system, which provides essential information needed for the design of rotor-bearing systems. In addition, an optimized FSI simulation using pre-built bearing model and Timoshenko beam model is proposed to improve the time efficiency of the FSI simulation further.

This study provides an efficient way to study the bearings/seals in the field of rotordynamics and material, which is important for the reliability study of ESPs. Meanwhile, the FSI simulations predict the transient behaviors of the rotor-bearing system, providing important reference for the design and modification of bearings/seals.