Notes on Electric Submersible Pumps (ESP)

Introduction to ESP

• ESP stands for Electric Submersible Pump.
• It is a form of artificial lift utilizing an electric motor to drive a multi-stage centrifugal pump to extract resources from a well.
• ESP systems are used in over 90% of oil wells to enhance production when natural energy is insufficient.
• They also boost early production in new wells.

Benefits of Artificial Lift

• Quiet and Safe: ESP systems operate quietly and safely.
• Small Surface Footprint: They require minimal space on the surface.
• Wide Range of Operations: Can accommodate fluctuations in fluid properties and flow rates.
• Corrosive Environment Adaptability: Suitable for many corrosive settings.

Components of an ESP System

1. Centrifugal Pumps: Multiple stages connected to a submersible electric motor.
2. Electric Motor: Powers the pump, with size and horsepower defined by the number of stages.
3. Heavy-Duty Cables: Connect motor to surface controls.
4. Pump Intake: Where well fluid enters the pump.
5. Submersible Pump Components: Includes motor, shaft, impellers, and seal chamber.
6. Downhole Sensors: Real-time monitoring of system data (pressure, temperature, vibration).
7. SCADA System: Used for monitoring pump performance and alerts for any anomalies.

How ESP Operates

• The electric motor rotates the shaft connected to the pump.
• Spinning impellers draw fluid into the pump, pressurizing it to lift it to the surface.
• Inverted Discharge Design: Pumps fluids into the well formation from the surface, mainly for water injection.

Detailed Components

• Motor:
  • Cooled by passing fluid.
  • Filled with synthetic oil for protection and lubrication.
• Seal Chamber: Protects the motor, equalizes pressure, absorbs axial thrust, and dissipates heat.
• Shaft: Connects motor to pump impellers, designed for strength and minimal diameter.
• Pump Intake Types:
  • Standard Intake: Used for low gas-liquid ratios.
  • Reverse Flow Intake: Allows for natural gas-liquid separation.
  • Rotary Pump Intake: Utilizes centrifugal force for gas separation.

Stages of Centrifugal Pump

• Each stage comprises a rotating impeller and a stationary diffuser to increase fluid pressure.
• Flow through stages increases pressure until desired discharge pressure is achieved.
• Total Developed Head: The increase in pressure from the pump.

Impellers

• Radial Flow Impellers: For lower flow rates (90-degree vane angle).
• Mixed Flow Impellers: For higher flow rates (45-degree vane angle).

Power Delivery

• Power cable delivers electricity to the motor, designed for harsh environments.
• Check valves maintain liquid in the tubing when the pump is off.

Surface Components

• Include electrical supply, communication equipment, and ESP controller.
• ESP Controller: Maintains electricity flow and can be automated to optimize production.
• Variable Speed Drive (VSD): Adjusts motor speed based on downhole data; can be manual or automated.
• Soft Start Controller: Prevents heavy load at start-up, gradually increasing to operational speed.

Advantages and Disadvantages of ESP Systems

• Includes various pros and cons compared to other artificial lift methods.

Further Learning Opportunities

• Videos on other types of artificial lift systems like plunger lift or gas lift systems available.
• For questions or more information, contact a local Kimray store or authorized distributor.