Patent ID: 7708534
Filing Date: 2010-05-04
Classification: E21B,F04D

Abstract:
1. A well pump assembly, comprising: a rotary pump; an electric motor for rotating the pump, the motor having a motor chamber containing a motor lubricant; a thrust chamber mounted between the motor and the pump, the thrust chamber containing a thrust chamber lubricant; a thrust bearing mounted in the thrust chamber for absorbing thrust imposed by operation of the pump; at least one seal for preventing entry of thrust chamber lubricant into the motor chamber; a pressure equalizing housing mounted to the motor and having a thrust chamber lubricant passage that admits thrust chamber lubricant from the thrust chamber, a motor lubricant passage that admits motor lubricant from the motor, and a well fluid inlet for admitting well fluid; a seal below the thrust bearing that seals between the thrust chamber lubricant and the motor lubricant; a first barrier in the housing having one side in contact with thrust chamber lubricant in the housing and an opposite side adapted to be contacted by well fluid in the housing, the first barrier being movable relative to the housing for reducing a pressure differential between the well fluid in the housing and the thrust chamber lubricant; and a second barrier in the housing having one side in contact with thrust chamber lubricant in the housing and an opposite side in contact with motor lubricant in the housing, the second barrier being movable relative to the housing for reducing a pressure differential between the thrust chamber lubricant and the motor lubricant.