Development of A High-Load Capacity Test Rig to Evaluate the Static Performance of Process Fluid-Lubricated Thrust Bearings

Abstract

Electrical submersible pumps (ESPs) are artificial lift devices widely used in the oil and gas industry to increase production. For unconventional wells, which includes subsea applications, installation cost is an order of magnitude higher than the cost of the typical ESP, thus pump reliability is paramount. Contamination of the thrust bearing lubricant oil by process fluid due to seal failures is one of the leading causes of thrust bearing failure. While improving seal reliability can prevent thrust bearing failures, an alternative approach is to develop process-fluid lubricated thrust bearings. This research aims to characterize and study the performance of thrust bearings operating with process fluid lubrication. A component level-level test rig for testing the performance of thrust bearings in any mixture of water, sand, and air is designed, built, and commissioned. Initial tests of the PEEK and Tungsten Carbide (WC) bearings include a load capacity test to determine the hydrodynamic limit of the bearing, a hydrodynamic test to corroborate test rig stability, and a wear test to determine if the bearings can operate feasibly past hydrodynamic limits in a mixed lubrication regime. Initial results show that lubrication starvation can occur in an unpressurized chamber for low viscosity fluids that are not supplied directly to the bearing. Furthermore, the film thickness, temperature rise in the pads, and load capacity all are lower for water lubricated bearings when compared to oil lubricated bearings. Results suggest that liner material affects wear rate but not load capacity; however, operating even the WC bearings past hydrodynamic limits causes substantial wear and is not recommended as an operating mode. Polycrystalline Diamond (PCD) coated mixed lubrication bearings were also tested. These bearings, although requiring higher drive torque, sustained higher loads than the tilting pad bearings without significant wear