Below motor equalizer of electrical submersible pump and method for filling

An electrical submersible pump assembly, comprising:

• a pump;
• a motor having a rotatable shaft extending along a longitudinal axis and operatively coupled to the pump for driving the pump, the shaft having a shaft drive member on a lower end;
• a pressure equalizer coupled to a lower end of the motor and having a flexible equalizing element that communicates well fluid pressure exterior of the pressure equalizer to motor lubricant in the motor;
• an adapter at an upper end of the equalizer that connects the equalizer to the lower end of the motor, the adapter having a motor lubricant passage through which motor lubricant in the motor communicates with motor lubricant in the equalizing element;
• a valve element located in the motor lubricant passage, the valve element having an upper position that blocks upward and downward flow of lubricant through the motor lubricant passage and a lower position that allows upward and downward lubricant flow through the motor lubricant passage;
• a valve element drive member on an upper end of the valve element that mates with the shaft drive member while the valve element is in the upper position and disengages from the shaft drive member while the valve element is in the lower position;
• a locking feature between the valve element and the motor lubricant passage that retains the valve element in the upper position, the locking feature being releasable in response to rotation of the motor shaft in a selected direction;
• and
• a spring that biases the valve element in a downward direction.

A method of pumping well fluid from a well with an electrical submersible pump assembly having a pump, a motor with a rotatable shaft extending along a longitudinal axis, and a pressure equalizer with a motor lubricant passage through which motor lubricant in the motor communicates with motor lubricant in the equalizer, the method comprising the following steps:

• (a) providing a valve in the motor lubricant passage;
• (b) dispensing a selected amount of motor lubricant into the equalizer;
• (c) with the valve in a closed position, coupling the equalizer to the motor after step (b) and filling the motor with motor lubricant, the valve while in the closed position blocking flow of motor lubricant from the motor into the equalizer;
• then
• (d) shifting the valve to an open position, allowing motor lubricant in the motor to flow into the pressure equalizer and motor lubricant in the equalizer to flow into the motor;
• (e) connecting the pump to the assembly and lowering the assembly into the well;
• (f) supplying power to the motor to drive the pump;
• wherein:
• step (a) comprises with a spring, urging the valve toward the open position, and with a locking feature, retaining the valve in the closed position;
• step (c) comprises engaging an end of the shaft with the valve;
• and
• step (d) comprises rotating the shaft a selected amount, which causes the valve to rotate, releasing the locking feature and disengaging the valve from the end of the shaft, then moving axially to the open position.