Bottom hole hollow core electric submersible pumping system

Abstract

An electric submersible pumping system includes a motor comprising an inner hollow core rotor and an outer stator, a gearbox comprising a hollow core input shaft connected to the motor rotor, and a hollow core output shaft, and a pump driven by the gearbox output shaft, the pump having an intake, and wherein the pump output is directed through the hollow core output shaft and into the hollow core motor rotor. The motor section is disposed above the gearbox and pump.

1 . An electric submersible pumping system comprising:
 (a) a motor comprising an inner hollow core rotor and an outer stator;   (b) a gearbox comprising a hollow core input shaft connected to the motor rotor, and a hollow core output shaft;   (c) a pump driven by the gearbox output shaft, the pump having an intake, and wherein the pump output is directed through the hollow core output shaft and into the hollow core motor rotor;   
     wherein the motor section is disposed above the gearbox and pump. 
   
   
       2 . The system of  claim 1  wherein the gearbox section comprises a thrust bearing comprising a hydraulic force chamber. 
   
   
       3 . The system of  claim 2  further comprising a closed lubricating oil circulation system including a low-pressure pump, and pressure equalization means for equalizing pump pressure and the lubricating oil circulation system pressure. 
   
   
       4 . The system of  claim 1  wherein the motor comprises a brushless DC motor or a synchronous AC motor. 
   
   
       5 . The system of  claim 3  wherein the gearbox comprises eccentric rotating components and the low pressure pump acts as a counterbalance to the gearbox. 
   
   
       6 . The system of  claim 1  or  5  wherein the gearbox comprises an epicyclic planetary gear set comprising a stationary outer gear, a rotating input shaft, an eccentric pinion gear engaging the input shaft and the outer gear, and an output shaft connected to the pinion gear by means of elongate coupling members. 
   
   
       7 . The system of  claim 2  wherein the hydraulic force chamber is pressurized by means of a hydraulic pump comprising a swash plate and a rotating barrel comprising reciprocating pistons bearing on the swash plate. 
   
   
       8 . The system of  claim 1  further comprising a motor control section, which houses a motor controller operatively connected to a surface power source and the motor.