Canned Motor Pump Technology for Subsea Boosting Applications

Abstract This paper will present the design, manufacturing, testing and validation of the canned motor pump (CMP) as an alternative to typical electric submersible pump (ESP) systems to produce oil and gas with the goal of developing a robust system to extend the ESP run-life. The CMP technology is a seal-less topology currently employed in demanding applications including highly abrasive radioactive slurry service. This subsea system leveraged knowhow developed in other demanding applications and is adapted for ESP caisson applications. The canned motor ESP development included mockups to validate design features and manufacturing processes. A CMP system was manufactured and tested at the vendor's facility with water and at the end user's test facility with multiphase and viscous fluids. Unit validation included rigorous multiphase testing with fluid viscosities ranging from 2 cP up to 300 cP and varying gas volume factions at different speeds. The typical electric submersible pump has an average run life of approximately 2.5 years in subsea caisson applications. Root Cause Failure Analysis (RCFA) on current ESP systems has revealed that a majority of failures result from the protector seal and motor. The main function of the seal section is to protect the motor and thrust bearings from contamination by the process fluid. The CMP seal-less technology eliminates the need for a protector seal section and dielectric fluid by isolating the wound stator with a corrosion resistant liner and a thrust bearing system that operates in process fluid. This paper will include test data results from thrust bearing testing in varying conditions including multiphase fluid to demonstrate robustness and unit performance test results from testing in water and multiphase fluid with varying viscosities. The canned motor ESP provides a new approach for subsea caisson applications by eliminating the protector seal section and incorporating process lubricated thrust bearings. This paper will share background, learnings, and results that demonstrate that the canned motor pump technology is ready for deployment in a subsea ESP caisson.