ESP (Electrical Submersible Pump) is a type of artificial lift system used primarily in the oil and gas industry to lift fluids—mostly crude oil—from wells where reservoir pressure is insufficient to push the fluids to the surface naturally. ESPs are one of the most commonly used forms of artificial lift and are known for their high efficiency and ability to handle large volumes of fluid.
ESP Works
An ESP is installed downhole, typically several hundred to several thousand feet below the surface, and is powered by electricity from the surface. It consists of a multistage centrifugal pump driven by an electric motor.
Main components:
- Pump:
A multistage centrifugal pump that increases the pressure of the fluid, enabling it to reach the surface. - Motor:
A sealed electric motor that drives the pump. It is located below the pump to keep it cool with the well fluids. - Protector (Seal Section):
Prevents well fluids from entering the motor and balances pressure. - Intake:
Allows well fluids to enter the pump. It may include a gas separator to remove free gas. - Power Cable:
Transmits electric power from the surface to the downhole motor. It is typically armored and insulated for durability.
Challenges and Limitations:
-Gas Handling: Free gas can reduce efficiency or damage the pump.
-Sand and Solids: Abrasive materials can cause wear.
-Temperature Limitations: Typically rated below 250°C (480°F), although high-temp ESPs exist.
-Power Supply and Cable Integrity: Long runs of power cable can degrade or be damaged during installation.
Applications:
-Mature oil wells with declining pressure
-Offshore wells, due to compact and reliable design
-Horizontal and deviated wells
-Water injection wells for reservoir pressure maintenance