Summary

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.

Audited Items

  • DIFA’s of the three systems were performed over three days, which included the following components for each string:

    • Pump, Gas Handler, Intake, Seals / Protectors (UT and LT), Motor

  • Daily reports sent to client during the DIFA process

  • Root cause and multiple issues were identified

  • Final reports were generated for each well with along recommendations, and provided to the client

Findings and Recommendations

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:

  1. Utilise Advanced Protector/Seal head on UT protector
  2. Shim tandem protectors/seals to load lower thrust bearing
  3. Consider protector/seal configurations other than BPBSL at high inclinations
  4. Review wells where ESP’s are installed at inclinations > 45 degrees an perform trend analysis against three wells that experienced failures
  5. Consider utilizing mechanism to prevent fallback of debris into pump