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Anti-Polymer Coating on downhole ESP Motor Surface



Challenge Summary

A coating mechanism to prevent the deposition of polymer on the surface of the ESP(Electrical submersible pump) used in oilfields, enabling the pump to be operated at maximum frequency, reduced heating effects in the coil, achieve higher production rates and service life of the pump.

Challenge Scenario

The oil fields after achieving a certain production rate are injected with polymers to extract the oil which cannot be recovered with conventional methods. The Mangala field in RJON - 90/91 is under full field polymer flood since 2015. The polymer used is hydrolysed polyacrylamide. The producer wells are fitted with down hole electrical submersible pumps to lift the hydrocarbons and water to surface. As the injected polymer breaks through from the producer well, it is exposed to the high temperature on the ESP motor surface causing the polymer to melt and stick on to the surface of the motor hardening the surface of the motor, prevents effective cooling of the motor by blocking of heat dissipation produced during the operation of the pump. Hence motor winding's temperature (MWT) under loading conditions often increases with time to more than 160 deg C, causing the loading to be reduced and there is significant production loss. A coating mechanism for the pump which can prevent the deposition of polymers is required.

Profile of the End-User

Oil Extraction Engineers

Oil Extraction Process Supervisors

Functional Requirements of the End-User

  • Operation of ESP at maximum frequency and loading conditions for extended time period.
  • Prevent deposition of polymer on motor
  • Achieve maximum cooling efficiency of the motor.

Functional & Operational Capabilities

  • Operating MWT << rated MWT in polymer affected well.
  • Prevent deposition of polymer on the surface of the motor
  • Achieve efficient cooling of motor in polymer affected wells
  • Coating to be compatible with the motor metallurgy

Operational constraints

  • Coating should be apt for wellbore conditions (Rates or velocity(0.5fps-10fps) /pressure(upto1500psi)/temp(25-170OC/solids content(10lbs/1000bbls)/pH(5-8)/metallurgy(L80, 9Cr, 13Cr etc).
  • Coating should be able to withstand tough downhole operating conditions of pressure (1600 psi), temperature (150 deg C), pH, H2S and flow rates (velocity).
  • The coating should not create any health or hazard to person or environment during storage, handling, installation or disposal.

Expected Tangible Benefits and Measurable Gains

  • An oil production gain of 2000bopd and an opex saving of 4MMUSD.
  • Increased service life of the pump.
  • Maximum frequency operations at optimal loading conditions with efficient cooling mechanism of the pump.

Performance Metrics or Outcomes

  • pressure (1600 psi), temperature (150 deg C).
  • The coating should be durable. It should last the expected ESP run life of about 2 years.
  • MWT @60Hz < 1000C for 1 year operation.

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