The Measured Impact Of Erosion On The Rotodynamic And Performance Characteristics Of A Mixed Flow ESP

Abstract

Three stages of a mixed flow electric submersible pump were subjected to 117 hours of erosion using a 2 gram/liter concentration ratio of 100 mesh hydraulic fracture sand to water. The sand passed through the pump one time and is discarded. The wear of flow paths and bearings is presented along with variation in pump performance and vibration as the pump wears. The pump was operated at its Best Efficiency Point (BEP) which is 1150 GPM (30100 BPD) at 3600 RPM with a specific speed of 1600. The hydraulic performance of the pump decreased 6.3% due to wear occurring in the secondary flow paths. Specifically, the bearings and seals were severely worn with bearing orbits up to 50 mils peak to peak. At the end, the bearings had worn more than the seals resulting in the seals carrying the rotordynamic loads of the rotor. Microscopic investigation of the tungsten carbide sleeve bearings showed what are believed to be thermal stress cracks which were revealed after the surface of the bearings were eroded.