Electric submersible pump floating ring bearing and method to assemble same

Abstract

A floating ring bearing for an electric submersible pump (ESP) assembly disposable within a cased wellbore and a method to assemble the same are disclosed. The ESP assembly includes a motor, a pump, and a shaft coupling the pump to the pump motor. One or more floating ring bearings are disposed within the motor and the pump, each floating ring bearing circumscribing the shaft to radially support the shaft. A floating ring is disposed within each floating ring bearing. The floating ring circumscribes the shaft so that the floating ring rotates about the shaft in response to rotation of the shaft.

1 . An electric submersible pump (ESP) assembly disposable within a cased wellbore, the ESP assembly comprising:
 a motor;   a pump;   a shaft coupled between the pump and the motor;   an outer bearing surface circumscribing the shaft;   fluid between the shaft and the bearing surface; and   an annular ring floating in the fluid and rotatable with respect to the shaft and the outer bearing surface.   
     
     
         2 . The ESP assembly of  claim 1 , wherein the fluid comprises a lubricant for transferring rotational inertia of the shaft to the ring so that the ring rotates in response to rotation of the shaft. 
     
     
         3 . The ESP assembly of  claim 1 , wherein the outer bearing surface comprises a portion of a housing of the pump. 
     
     
         4 . The ESP assembly of  claim 1 , wherein the ring is disposed in the pump and the fluid comprises wellbore fluid being pressurized by the pump. 
     
     
         5 . The ESP assembly of  claim 1 , wherein ring is disposed in the motor and the fluid comprises dielectric fluid. 
     
     
         6 . The ESP assembly of  claim 1 , wherein the ring rotates at a slower rotation speed than the shaft. 
     
     
         7 . The ESP assembly of  claim 1 , wherein the ring rotates at about one-third to about one-fourth the rotation speed of the shaft. 
     
     
         8 . An electric submersible pump (ESP) assembly disposable within a cased wellbore, the ESP assembly comprising:
 a motor;   a pump;   a shaft coupled between the pump and the motor;   a stationary journal defining a bore through which the shaft extends;   fluid circumscribing the shaft in the stationary journal; and   an annular ring floating in the fluid coaxial with an axis of the shaft and rotatable with respect to the shaft to reduce the rotational inertia of the fluid resulting from rotation of the shaft, the annular ring rotating at a slower speed than the shaft so that fluid between the ring and the shaft has a higher rotational inertia than the fluid between the ring and the stationary journal.   
     
     
         9 . The ESP assembly of  claim 8 , wherein the fluid comprises a lubricant for transferring rotational inertia of the shaft to the ring so that the ring rotates in response to rotation of the shaft. 
     
     
         10 . The ESP assembly of  claim 8 , wherein the stationary journal comprises a portion of a housing of the pump. 
     
     
         11 . The ESP assembly of  claim 8 , wherein the ring is disposed in the pump and the fluid comprises wellbore fluid being pressurized by the pump. 
     
     
         12 . The ESP assembly of  claim 8 , wherein ring is disposed in the motor and the fluid comprises dielectric fluid. 
     
     
         13 . The ESP assembly of  claim 8 , wherein the ring rotates at about one-third to about one-fourth the speed of the shaft. 
     
     
         14 . A method to assemble a floating ring bearing for use in an electric submersible pump (ESP) to radially support one or more rotating shafts coupling a motor of the ESP to a pump portion of the ESP, the method comprising:
 (a) providing a stationary journal defining a bore having an axis, the journal secured to a non-rotating member of the electric submersible pump;   (b) positioning the shaft within the journal coaxial with the bore, the shaft rotatable relative to the journal;   (c) positioning a floating ring coaxial with the bore between the journal and the shaft, the floating ring defining an outer annular cavity between the floating ring and the journal and an inner annular cavity between the floating ring and the shaft; and   (d) filling ESP with a fluid so that the fluid flows through the ESP into the inner and outer cavities, the fluid to transfer rotational inertia of the shaft to the floating ring when the shaft rotates, thereby allowing the floating ring to rotate within the journal.   
     
     
         15 . The method of  claim 14 , further comprising providing the stationary journal in the pump portion of the ESP and the fluid comprising wellbore fluid pressurized by the pump portion. 
     
     
         16 . The method of  claim 14 , further comprising providing the stationary journal in the motor of the ESP and the fluid comprising dielectric fluid filling the motor. 
     
     
         17 . The method of  claim 14 , further comprising providing the stationary journal in a seal section coupled between the motor and the pump portion of the ESP and the fluid comprising dielectric fluid filling the seal section.