Safety brake for electrical submersible pumps powered by permanent magnet motors

A system used with tubing in a well, the system comprising:

• an electric submersible pump (ESP) assembly disposed on the tubing and having a pump and an electric motor;
• and
• a safety brake device connected between the tubing and the pump, the safety brake device having an internal bore configured communicate fluid therethrough, the safety brake device comprising:
• a shaft disposed in the internal bore and configured to rotate in response to rotation associated with the ESP assembly;
• a piston disposed in the internal bore and being movable in a longitudinal movement relative to the shaft in response to a pressure differential across the piston;
• and
• a clutch arranged between the piston and the shaft and being configured to engage and disengage between the piston and the shaft in response to the longitudinal movement of the piston, the clutch engaged with the shaft being configured to restrict the rotation of the shaft.

A method used with tubing in a well, the method comprising:

• during a first operation involving an electric submersible pump (ESP) assembly pumping fluid from the well to the tubing, operating a brake device by:
• moving a piston in the brake device away from a shaft in the brake device with a longitudinal movement in response to the fluid pumped by the ESP assembly through the brake device;
• disengaging, in response to the longitudinal movement of the piston, a clutch arranged between the piston and the shaft;
• and
• allowing the shaft to rotate in the brake device with rotation imparted by the ESP assembly;
• and
• during a second operation involving the ESP assembly, operating the brake device by:
• moving the piston in the brake device toward the shaft in the brake device with the longitudinal movement;
• engaging, in response to the movement of the piston, the clutch arranged between the piston and the shaft;
• and
• preventing rotation of the ESP assembly by restricting the rotation of the shaft in the brake device with the engagement of the clutch.