1. Field of Invention
The present disclosure relates in general to submersible well pumps, and in particular to seal assemblies used in combination with the motors that drive submersible well pumps. More specifically, the present invention relates to stacked chambers that form an elongated labyrinth.
2. Description of Prior Art
A variety of fluid lifting systems are in use to pump fluids from a wellbore to surface handling and processing facilities. It is common to employ various types of downhole pumping systems to pump the subterranean formation fluids to surface collection equipment for transport to processing locations. One such conventional pumping system is a submersible pumping assembly which is immersed in the fluids in the wellbore. The submersible pumping assembly includes a pump and a motor to drive the pump to pressurize and pass the fluid through production tubing to a surface location. A typical electrical submersible pump assembly (“ESP”) includes a submersible pump, an electric motor, and a seal section between the pump and the motor.
Generally, when an ESP is being inserted into a wellbore, pressure in the ESP is generally at about atmospheric. Wellbore pressure often significantly exceeds atmospheric pressure, thus unless the pressure inside the ESP is equalized to its surroundings, seals, especially in the motor section, can become compromised and leak. Because wellbore fluids are often electrically conductive, leaking wellbore fluid can create electrical shorts in the ESP and damage the motor. The seal section equalizes pressure in the ESP with the ambient pressure by communicating wellbore fluid pressure to the motor fluid. The communication though is limited to pressure, because as indicated above, wellbore fluid can damage the motor and/or introduce contaminates into the ESP.