ELECTRIC SUBMERSIBLE PUMPING UNIT
An electric submersible pump assembly with integral heat exchanger, high-speed self-aligning bearings, and dual bearing thrust chamber is described. The described pump assembly, modules, and components may be used for operating an electric submersible pump at high speeds as well as over a wide range of speeds and flowrates without replacing downhole equipment. The described pump assembly may be shorter than comparable pump assemblies and may be assembled offsite, thereby leading to faster and easier installation with less down time. By operating over a wide range of speeds, the disclosed pump assembly allows the operator to reduce overall inventory, reduce down time for the well, and avoid other complications associated with replacing a pump assembly or other downhole components.
1 . An electric submersible pump assembly, comprising:
a pump module, wherein the pump module comprises a pump shaft and an impeller, wherein the pump shaft is operably connected to a motor shaft and wherein the impeller is rotationally fixed to the pump shaft by a keyway;
a seal section, wherein the seal section is configured to transmit torque from the motor shaft and absorb thrust from the pump module;
a motor module, wherein the motor module comprises a motor configured to operate at greater than 4,000 rpm, the motor configured to rotate a motor shaft; and
a motor cooling system, wherein the motor cooling system comprises a motor cooling impeller, the motor cooling impeller configured to circulate lubricant through a motor module heat exchanger wherein the motor module heat exchanger comprises a motor module lubricant pathway, the motor module lubricant pathway configured to increase a residence time of the lubricant in the motor module heat exchanger.
2 . The assembly of claim 1 , further comprising a gas separator module wherein the gas separator comprises a gas separator shaft and an inducer, wherein the gas separator shaft is operably connected to the motor shaft and the inducer is rotationally fixed to the gas separator shaft by a keyway.
3 . The assembly of claim 1 , further comprising a fluid in-take.
4 . The assembly of claim 1 , wherein the seal section comprises a port in fluid communication with the exterior environment surrounding the seal section and in fluid communication with an interior chamber, the interior chamber configured to reduce a pressure differential between the pressure from the exterior of the assembly to the interior of the assembly.
5 . The assembly of claim 1 , wherein the seal section comprises a seal section cooling system wherein the seal section cooling system comprises a seal section heat exchanger wherein the seal section heat exchanger comprises a seal section lubricant pathway, the seal section lubricant pathway configured to increase a residence time of the lubricant in the seal section heat exchanger.
6 . The assembly of claim 5 , wherein the seal section lubricant pathway is in fluid communication with the motor module lubricant pathway
7 . The assembly of claim 1 , further comprising a high-speed self-aligning bearing, the high-speed self-aligning bearing comprising a bushing and a sleeve, the bushing having a microhardness of at least about 2,500 MPa and the sleeve having a microhardness of at most about 2,000 MPa
8 . The assembly of claim 1 wherein the motor module heat exchanger comprises a central heat exchanger module and lower heat exchanger module, and wherein the lower heat exchanger module comprises a screen configured to trap non-ferrous particles and a magnetic trap configured to trap ferrous particles.
9 . The assembly of claim 1 , wherein the seal section comprises a thrust chamber wherein the thrust chamber comprises at least two thrust bearings and wherein each thrust bearing is fitted with a spring damper.
10 . The assembly of claim 1 , wherein the motor module comprises a head module, power module, and base module.
11 . The assembly of claim 10 , further comprising at least two power modules disposed between the head module and base module, wherein a flangeless connection is used to connect the two power modules to each other.
12 . The assembly of claim 10 , wherein a flangeless connection is used to connect the head module to a power module and wherein a flangeless connection is used to connect the base module to a power module.
13 . The assembly of claim 1 , wherein the motor module further comprises a stator with a magnetic field and wherein the motor rotor is configured to self-align within the magnetic field of the stator.
14 . The assembly of claim 13 , further comprising an axial seating system comprising a static thrust receiving face and a dynamic thrust transferring face, wherein the dynamic face has a higher microhardness than the static face and the static face has a higher compressive strength than the dynamic face.
15 . The assembly of claim 14 , wherein the dynamic thrust transferring face has a compressive strength of at most about 4,500 Mpa and the static thrust receiving face has a compressive strength of at least about 7,200 Mpa.
16 . The electric submersible pump assembly of claim 1 , wherein the assembly has a total dynamic head in feet to length in feet ratio of between about 80 and about 300.
17 . The electric submersible pump assembly of claim 1 , wherein the assembly has a break horse power to length in feet ratio of between about 4 and about 12.
18 . The electric submersible pump assembly of claim 1 , wherein the assembly is configured to produce between about 400 barrels per day and about 4,000 barrels per day without changing the electric submersible pump.
19 . A process for producing well bore fluid comprising:
deploying an electric submersible pump within a wellbore, wherein the electric submersible pump comprises:
a pump module comprising a pump shaft and an impeller, wherein the pump shaft is operably connected to a motor shaft;
a seal section wherein the seal section is configured to transmit torque from the motor shaft to the gas separator shaft and absorb thrust;
a motor module comprising an electric motor configured to rotate a motor shaft; and
a motor cooling system comprising a motor cooling impeller configured to circulate lubricant through a motor module heat exchanger, the motor module heat exchanger comprising a motor module lubricant pathway, the motor module lubricant pathway configured to increase a residence time of the lubricant in the motor module heat exchanger,
operating the electric submersible pump; and
producing well bore fluid.
20 . The process of claim 19 , wherein the seal section comprises a seal section heat exchanger comprising a seal section lubricant pathway.