ALS was requested by a client to perform a Dismantle, Inspection, Failure Analysis (DIFA) on three ESP systems. The work was performed at the supplier facility in Jakarta, with the goal of identifying the root cause of the failure, and helping the client to mitigate the issues on future ESP installs.
All three ESP systems displayed a common failure mechanism – a broken shaft at the runner in the thrust bearing chamber within the protectors/seals. Two of the three failures occurred in the UT protector/seal, while the other occurred in the LT. The failures were caused by an intrusion of well fluid into the thrust chamber, and a resulting loss of lubricity, which generated enough heat to cause shaft failure.
It was determined that the inclination of ESP installation (45-80 deg), along with the protector/seal configuration (BPBSL) were part of the reason for failure. At higher inclinations, labyrinth chambers are rendered ineffective. Therefore, upon the failure of the mechanical seal, well fluid has a direct path into the thrust chamber. Additionally, the protectors/seals were tandemed so that the UT thrust bearing held the load from the pump. When well fluid entered the UT thrust bearing, the lubricity was lost, and high friction occurred resulting in shaft failure due to excessive heat.
Recommendations provided by ALS to the customer were as follows: