Notes on Electrical Submersible Pumping Systems (ESP)
Overview
Focus on Artificial Lift Systems, specifically Electrical Submersible Pumping Systems (ESP)
Commonly used for high-volume oil extraction
Discuss main components, design, selection, and efficiency
What is an ESP?
Type of mechanical assist artificial lift system
Used primarily for high production rates (over 60,000 barrels/day possible)
Utilize multi-stage centrifugal pumps, relying on centrifugal force to move fluids
Types of Artificial Lift Systems
Mechanical Assist
Includes ESP and rod lift systems
Formation Assist
Dynamic Displacement
ESP falls under this category
Positive Displacement
Components of ESP
Downhole Components:
Three-phase electric motor: Drives the pump
Seal sections: Protects motor from produced fluids
Pump intake: Where fluids enter the pump
Multi-stage centrifugal pump: Contains impellers and diffusers
Electric cables: Connects motor to the surface power source
Optional: sensors, motor controllers, etc.
Surface Components:
Junction Box (J-Box): For safety measures, measurement, and gas venting
Transformer: Converts voltage for the motor
Motor controllers: Manage power and operational functions
Operating Principles of ESP
Dynamic Displacement: Uses rotating impellers within the pump to create pressure and lift fluid
Impellers create kinetic energy that is then converted to head pressure in the diffuser.
Stage Composition:
Each stage consists of:
Rotating impeller: Creates velocity in the fluid
Stationary diffuser: Converts velocity into head
Operating efficiency depends heavily on the configuration of the pump stages.
Performance and Efficiency
Efficiency ranges between 35% - 60%, depending on design factors.
To maximize efficiency, keep operations within recommended production ranges.
Performance curves outline head capacity, efficiency vs. flow rate.
Managing Limitations and Challenges:
High power sources are needed for deep wells.
Issues with heat generation in the motor.
Maintenance of the system can be costly and complex if failures occur.
Sensitivity to gas and solid materials can impact efficiency.
Design Considerations
Calculate total dynamic head required to lift fluids, factoring in:
Hydrostatic pressure
Friction losses in the tubing
Desired production rates
Number of stages determined based on total head and head produced by each stage.
Motor sizing needs to account for the lift and estimated efficiency.
Additional Notes
The importance of monitoring parameters and flexible design to adapt to changing well conditions.
Capacity for deploying advanced technologies like variable speed drives for optimized performance.
Understanding operating feedback is crucial for long-term efficiency and performance stability.
Conclusion
ESP systems are critical for efficient oil extraction in modern operations, but require careful design, selection, and real-time monitoring to operate effectively.
Questions to Consider
How does ESP compare with other artificial lift systems in terms of efficiency and costs?
What are the best practices for maintenance of ESP systems?