WO2015178887A1

WO2015178887A1 - Optimized cooling for electric motor in artificial lift

Info

Publication number: WO2015178887A1
Application number: PCT/US2014/038645
Authority: WO
Inventors: Carlos E. DIAZ; Raul Alejandro OYARZUN; Ricardo Hector TEVES; Charles Collins
Original assignee: Ge Oil Gas Esp, Inc.
Priority date: 2014-05-19
Filing date: 2014-05-19
Publication date: 2015-11-26
Also published as: CN107002688B; RU2016146328A3; CN107002688A; RU2686971C2; RU2016146328A

Abstract

An electric submersible pumping system includes a motor, a production pump driven by the motor, a heat exchanger and an oil circulation pump connected to the motor. The production pump moves fluids from the wellbore through the heat exchanger. The oil circulation pump circulates oil between the motor and the heat exchanger to moderate the operating temperature of the motor. Heat absorbed by the oil moving through the motor is transferred to the produced fluid moving through the heat exchanger.

Description

OPTIMIZED COOLING FOR ELECTRIC MOTOR IN ARTIFICIAL LIFT

Field of the Invention

[001] This invention relates generally to the field of submersible pumping systems, and more particularly, but not by way of limitation, to a submersible pumping system that includes a motor cooling system.

Background

[002] Submersible pumping systems are often deployed into wells to recover petroleum fluids from subterranean reservoirs. Typical submersible pumping systems include a number of components, including one or more fluid filled electric motors coupled to one or more high performance pumps located above the motor. When energized, the motor provides torque to the pump, which pushes wellbore fluids to the surface through production tubing. Each of the components in a submersible pumping system must be engineered to withstand the inhospitable downhole environment.

[003] Most wells include a casing that extends along the inside of the wellbore to maintain the structural integrity of the wellbore and to isolate the introduction of fluids into the well. "Perforations" are formed through the casing at desired locations to permit the ingress of fluids from a producing formation into the casing. In many cases, the submersible pumping system is positioned above the perforations in the wellbore. By positioning the submersible pumping system above the perforations, a cooling effect is achieved as fluid drawn into the pump passes by the motor. In installations where insufficient fluid is available to provide this cooling effect, the electric motor may overheat and fail. [004] There are however, recognized benefits to installing at least a portion of the submersible pumping system below the perforations in what is occasionally referred to as a "sumped" position. By placing at least the intake of the pump below the perforations, the operator is able to maximize wellbore drawdown, which can increase the production of fluids from the well. In certain wells, the placement of the intake below the perforations also decreases the gas content present in the influent to the pump. As two-phase fluids enter the well through the perforations, lighter gaseous components tend to rise as the heavier liquid components fall. Placing the intake of the pump below the perforations enhances gravity separation and decreases the gas content in the pump influent. Reducing the gas content in the influent decreases the risks of gas locking and generally improves the efficiency of the submersible pumping system.

[005] The primary problem associated with placing the submersible pumping system below the perforations is the lack of cooling provided by the movement of fluid over the electric motor. When the submersible pumping system is placed below the perforations, fluid entering the well through the perforations may be drawn into the pump intake without passing over the motor. In this way, the fluid around the motor may become relatively stagnant and unable to provide sufficient heat dissipation.

[006] Manufacturers have used several methods to overcome this problem. The most common method for increasing flow around the electric motor is through the use of a shrouded intake. An intake shroud typically includes a closed end above the pump intake and an open end adjacent the bottom of the motor. As fluids are drawn into the wellbore through perforations, the fluids are conducted around the exterior of the motor by the shroud. While generally effective at providing a fluid flow around the motor, the shroud requires additional space between the submersible pumping system and the well casing and may present an undesirable pressure drop under certain conditions. Furthermore, the cooling effect provided by the shroud is dependent upon the availability of adequate liquid production into the wellbore. In marginal wells or wells with a high gas-fraction, the lack of sufficient quantities of liquid will reduce the cooling effect provided by a shrouded solution. There is, therefore, a need for an improved motor cooling system that overcomes the deficiencies of the prior art. It is to this and other needs that the preferred embodiments are directed.

Summary of the Invention

[007] Preferred embodiments of the present invention include a closed-loop cooling system for moderating the temperature of an electric motor in a submersible pumping system. The submersible pumping system preferably includes a motor, a production pump driven by the motor, a heat exchanger adjacent to the production pump and an oil circulation pump connected to the motor. The production pump moves fluids from the wellbore through the heat exchanger. The oil circulation pump circulates oil between the motor and the heat exchanger to moderate the operating temperature of the motor. Heat absorbed by the oil moving through the motor is transferred to the produced fluid moving through the heat exchanger.

[008] In another aspect, preferred embodiments include a cooling system for use in a submersible pumping system that includes an oil-filled electric motor and a production pump driven by the oil-filled electric motor. The cooling system includes a heat exchanger that has a central passage in fluid communication with the production pump, heat exchange tubes adjacent the central passage and an oil circulation pump driven by the motor. The oil circulation pump is in fluid communication with the oil- filled electric motor and the heat exchange tubes of the heat exchanger.

[009] In yet another aspect, preferred embodiments include a method for controlling the operational temperature of an electric motor in a submersible pumping system disposed in a wellbore, where the pumping system includes a production pump driven by the electric motor to produce fluids from the wellbore. The method includes the steps of providing an oil circulation pump connected to the electric motor and providing a heat exchanger connected to the production pump. The method continues with the step of activating the oil circulation pump to move motor lubricant at an initial temperature through the electric motor, where the motor lubricant absorbs heat from the operating electric motor. Next, the method continues with the steps of moving the warmed motor lubricant from the electric motor to the heat exchanger and activating the production pump to move produced fluids from the wellbore through the heat exchanger. The warmed motor lubricant transfers heat to the produced fluids in the heat exchanger. Lastly, the method provides for moving the cooled motor lubricant from the heat exchanger back to the operating motor to restart the cycle.

Brief Description of the Drawings

[010] FIG. 1 is an elevational view of the submersible pumping system constructed in accordance with a preferred embodiment.

[011] FIG. 2A is a cross-sectional depiction of the motor of the pumping system of FIG. 1 in a first preferred embodiment.

[012] FIG. 2B is a cross-sectional depiction of the motor and seal section of the pumping system of FIG. 1 in a second preferred embodiment. [013] FIG. 3 is a top cross-sectional view of the motor of FIG. 2A and FIG. 2B.

[014] FIG. 4A is a cross-sectional view of the oil circulation pump of the pumping system of FIG. 1 constructed in accordance with a first preferred embodiment.

[015] FIG. 4B is a cross-sectional view of the oil circulation pump of the pumping system of FIG. 1 constructed in accordance with an alternate preferred embodiment.

[016] FIG. 5 is a cross-sectional view of the heat exchanger module of the pumping system of FIG. 1.

Detailed Description of the Preferred Embodiment

[017] In accordance with a preferred embodiment of the present invention, FIG. 1 shows an elevational view of a pumping system 100 attached to production tubing 102. The pumping system 100 and production tubing 102 are disposed in a cased wellbore 104, which is drilled for the production of a fluid such as water or petroleum. As used herein, the term "petroleum" refers broadly to all mineral hydrocarbons, such as crude oil, gas and combinations of oil and gas. The production tubing 102 connects the pumping system 100 to a wellhead 106 located on the surface.

[018] The pumping system 100 preferably includes a production pump 108, a motor 110, a seal section 112, a gas separator 114, a heat exchanger 116 and an oil circulation pump 118. In a preferred embodiment, the motor assembly 110 is an electrical motor that receives its power from a surface-based supply through a power cable 120. The motor assembly 110 converts the electrical energy into mechanical energy, which is transmitted to the production pump 108 by one or more shafts 122. The production pump 108 then transfers a portion of this mechanical energy to fluids within the wellbore, causing the wellbore fluids to move through the production tubing 102 to the surface. In a particularly preferred embodiment, the production pump 108 is a turbomachine that uses one or more impellers and diffusers to convert mechanical energy into pressure head. In an alternative embodiment, the production pump 108 is a progressive cavity (PC) or positive displacement pump that moves wellbore fluids with one or more screws or pistons. Although demonstrated in a vertical wellbore 104, it will be appreciated that pumping system 100 may also be implemented in horizontal and non- vertical wellbores. The preferred embodiments of the pumping system 100 may also find utility in surface pumping applications and in the production of energy from geo thermal resources.

[019] The seal section 112 shields the motor 110 from axial thrust loading produced by the production pump 108 and prevent the ingress of wellbore fluids into the motor 110. The seal section 112 may also accommodate expansion and contraction of lubricants within the motor 110. The gas separator 114 is connected to the seal section 112. The gas separator 114 includes an intake 124, a discharge head 126 and gas discharge ports 128. Fluids are drawn into the gas separator 114, where liquids and gases are separated using mechanisms known in the art. Liquids are passed from the gas separator 114 into the heat exchanger 116 and gases are expelled into the wellbore 104 through the gas discharge ports 128. It will be appreciated that the gas separator 114 may not remove all of the gas from the production fluids being processed by the pumping system 100 and that some gas may pass into the heat exchanger 116. Although the seal section 112 is depicted in FIG. 1 above the motor 110, alternate embodiments include the placement of the seal section 112 below the motor 110. If the seal section 112 is placed below the motor 110, it may be desirable to incorporate the thrust chamber from the seal section 112 into the motor 110. In yet additional alternate embodiments, it is desirable to use a dedicated motor oil expansion chamber below the motor 110 in addition to the seal section 112 above the motor 110.

[020] Generally, the heat exchanger 116 and oil circulation pump 118 are configured to cooperatively remove heat from the motor 110. Motor lubricants are pumped by the oil circulation pump 1 18 through the motor 110 and heat exchanger 116 through first and second oil lines 130a, 130b. The motor lubricants absorb heat from the motor 110 and expel heat into production fluids passing through the heat exchanger 116. The use of the heat exchanger 116 and oil circulation pump 118 presents a significant advance in the maintenance of motor temperatures. Because the motor cooling system of the preferred embodiments is not dependent on external convective cooling, the motor 110 can be operated in environments with reduced fluid flow around the motor 110. In particular, the novel motor cooling systems of the preferred embodiments will find particular utility in situations where the motor 110 is placed below the perforations in the wellbore 104 (as illustrated in FIG. 1) or in marginal wells that do not produce sufficient fluid volume for external convective cooling.

[021] Although only one production pump 108, motor 110, seal section 112, gas separator 114, heat exchanger 116 and oil circulation pump 118 are shown in FIG. 1, it will be understood that more than one of each of these components can be utilized within the pumping system 100 when appropriate. Furthermore, the use of the gas separator 114 is optional and may be omitted in certain applications. For example, it may be desirable to omit the gas separator in wells that exhibit a low gas fraction. In those applications in which the gas separator 114 is omitted from the pumping system 100, the intake 124 is use to conduct fluids to the production pump 108 and the heat exchanger 116 can be placed between the production pump 108 and the production tubing 102 (if the intake 124 is integral with the production pump 108) or between the intake 124 and the production pump 108 (if the intake 124 is separated from the production pump 108).

[022] Although the heat exchanger 116 is depicted in FIG. 1 between the production pump 108 and the gas separator 114, additional embodiments contemplate the placement of the heat exchanger 116 in other locations within the pumping system 100. For example, it may be desirable to place the heat exchanger 116 above the intake 124 and below the production pump 108, above the production pump 108 or between adjacent production pumps 108 if multiple production pumps 108 are used.

[023] Alternatively, the heat exchanger 116 can be placed below the motor 110 or below the intake 124 of the production pump 108. Placing the heat exchanger 116 below the motor 110 or intake 124 may find particular utility in applications in which the pumping system 100 is placed above the perforations in the wellbore 104. In this configuration, fluid drawn into the wellbore 104 passes over the exterior of the heat exchanger 116 before it is warmed by the motor 110.

[024] Referring now to FIG. 2 A, shown therein is a side cross-sectional view of the motor 110 and seal section 112. The motor 110 includes a motor housing 132, a shaft 134, a stator assembly 136, and a rotor 138. The motor housing 132 encompasses and protects the internal portions of the motor 110 and is preferably sealed to reduce the entry of wellbore fluids into the motor 110. The bottom of the motor 1 10 is connected to, and in fluid communication with, the oil circulation pump 118. [025] The seal section 112 is attached to the upper end of the motor 110 and provides a system for accommodating the thrust load of the production pump 108. The seal section 112 includes a thrust chamber 200 that houses a thrust bearing assembly 202 and one or more mechanical seals 204. The thrust bearing assembly 202 includes a pair of stationary bearings 206 and a thrust runner 208 attached to the shaft 134. The thrust runner 208 is captured between the stationary bearings 206, which limit the axial displacement of the thrust runner 208 and the shaft 134. The seal section 112 preferably also includes a fluid isolation assembly 210. In the embodiment depicted in FIG. 2B, the fluid isolation assembly 210 includes a bag seal 212. The bag seal 212 isolates the wellbore fluids in the production pump 108 from the clean lubricants in the seal section 212 and motor 110.

[026] The first oil line 130a is connected downstream from the thrust chamber 200 of the seal section 212 and is in fluid communication with the interior of the thrust chamber 200. In many applications, the thrust bearing assembly 202 generates heat as the thrust runner 208 comes into contact with the stationary bearings 206. The placement of the first oil line 130a downstream from the thrust chamber 200 helps to moderate the temperature within the thrust chamber 200. In the alternate embodiment depicted in FIG. 2B, the first oil line 130a is connected directly to the motor 110 and extends through the motor housing 132 into the interior of the motor 110. Although first and second oil lines 130a, 130b are depicted as external to the motor 110, seal section 112 and heat exchanger 116, the lines 130a, 130b can alternatively be configured as internal components within the pumping system 100. [027] Adjacent the interior surface of the motor housing 132 is the stationary stator assembly 136 that remains fixed relative the motor housing 132. The stator assembly 136 surrounds the interior rotor 138. The difference between the interior diameter of the stator assembly 136 and the outer diameter of the rotor 138 defines a stator-rotor gap 140 that extends along the length of the rotor 138.

[028] As depicted in the cross-sectional view of the motor in FIG. 3, the stator assembly 136 includes stator coils 142 extending through a stator core 144. The stator core 144 is formed by stacking and pressing a number of thin laminates 146 to create an effectively solid core. The stator coils 142 are formed by extending magnet wire 148 through slots 150 in each laminate 146 of the stator core 144. The magnet wire 148 is insulated from the laminates 146 by slot liners 152. The slot liners are preferably manufactured from a durable, electrically isolating material, such as perfluoroalkoxy (PFA) polymer. In preferred embodiments, the cross-sectional area of the interior of each of the stator liners 152 is greater than the combined cross-sectional area of the multiple passes of magnet wire 148 within each liner 152. The difference between the cross-sectional area of the stator liner 152 and the aggregate cross-sectional area of the magnet wire defines a stator slot oil passage 154 that is filled with dielectric motor lubricating oil.

[029] Turning to FIG. 4A, shown therein is a cross-sectional depiction of a preferred embodiment of the oil circulation pump 118 and a portion of the motor 110. The oil circulation pump 118 includes a circulation pump housing 156 that is connected to the motor housing 132 and to the second oil line 130b. The oil circulation pump 118 preferably includes one or more pump stages 158 and a motor lubricant reservoir 160. In a particularly preferred embodiment, each of the one or more pump stages 158 is a turbomachine that includes a stationary diffuser 162 and a rotatable impeller 164 that is connected to the motor shaft 134. When rotated by the motor 110, the pump stages 158 push the motor lubricant through the oil circulation pump 118. In alternative embodiments, the oil circulation pump 118 includes rotary or reciprocating positive displacement pump stages.

[030] In the additional alternative embodiment depicted in FIG. 4B, the oil circulation pump 118 is driven by a separate oil circulation pump motor 214. The use of the distinct oil circulation pump motor 214 allows for the independent control of the production pump 108 and oil circulation pump 118. In highly preferred embodiments, the pumping system 100 further includes a control system 216 that measures the temperature of the motor 110 and adjusts the operation of the oil circulation pump motor 214 to increase or decrease the flow of motor lubricant through the oil circulation pump 118 on an as-needed basis. If the system temperature increases, the oil circulation pump 118 can be made to increase the flowrate of the motor lubricant circulating through the motor 110 and heat exchanger 116. Conversely, if the temperature of the motor lubricant decreases, the flow through the oil circulation pump 118 can be reduced without throttling the flow through the production pump 108.

[031] Turning to FIG. 5, shown therein is a cross-sectional depiction of the heat exchanger 116. The heat exchanger 116 includes a heat exchanger housing 166 that is connected to the discharge head 126 of the gas separator 114 and to an intake side of the production pump 108. The heat exchanger 116 includes a central passage 168 that places the production pump 108 in fluid communication with the gas separator 114. Although not illustrated in FIG. 5, the central passage 168 may include baffles or spiraled flights that increase the residence time of fluids passing through the central passage 168. The shaft 122 extends through the central passage 168 and transfers torque from the gas separator 114 to the production pump 108.

[032] The heat exchanger 116 further includes a series of heat exchange tubes 170 within the heat exchanger housing 166. In the preferred embodiment depicted in FIG. 5, the heat exchange tubes 170 are configured in a coiled configuration along the interior of the heat exchanger housing 166. In a particularly preferred embodiment, the heat exchange tubes 170 are located within a thermally conductive jacket 172 that prevents the heat exchange tubes 170 from coming into contact with the produced fluid in the central passage 168. The heat exchange tubes 170 are connected to the first and second oil lines 130a, 130b through the heat exchanger housing 166. In this way, motor lubricant pumped through the first and second oil lines 130a, 130b passes through the heat exchange tubes 170 and exchanges heat through the jacket 172 with the produced fluid moving through the central passage 168. In an alternative preferred embodiment, the heat exchange tubes 170 are configured as one straight tube or a plurality of straight tubes connected by end turns that extend along a length of the heat exchanger housing 166. In yet another alternative embodiment, the pumped process fluid is moved through adjacent tubes within the heat exchanger and the motor lubricant is passed through the void between the adjacent tubes. It will be appreciated that other forms and configurations of heat exchangers may find utility within the preferred embodiments.

[033] In a first preferred embodiment, the dielectric motor lubricant is pumped downward through the seal section 112 into the motor 110, where the lubricant passes through the stator-rotor gap 140 and stator slot oil passages 154. As the motor lubricant passes through the thrust chamber 200 of the seal section and the motor 110, the lubricant absorbs a quantity of heat. Heat transfer is optimized by passing the lubricant in close proximity to the thrust chamber 200 and stator core 144, which are often the hottest parts of the pumping system 100. The oil circulation pump 118 then pushes the hot motor lubricant through the second oil line 130b into the top of the heat exchanger 116. The hot motor lubricant moves downward through the heat exchange tubes in a countercurrent configuration with the flow of produced fluid through the central passage 168. The motor lubricant transfers heat into the produced fluid to cool the motor lubricant. The cooled motor lubricant is returned to the top of the motor 110 through the first oil line 130a and the heat exchange cycle is repeated. In this way, the motor 110, seal section 112, oil circulation pump 118 and heat exchanger 116 cooperate in a closed-loop heat exchange cycle that transfers heat from the seal section 112 and motor 110 to the produced fluid moving through the heat exchanger 116. In addition to controlling the operational temperature of the seal section 112 and motor 110, the cooling systems of the preferred embodiments may also decrease the viscosity of the produced fluid by increasing its temperature. Decreasing the viscosity of the produced fluid may facilitate the pumping operation, particularly for highly viscous petroleum fluids.

[034] In a second preferred embodiment, motor lubricant is pumped up through the motor 110 into the thrust chamber 200 and into the heat exchanger 116 through the first oil line 130a. The hot motor lubricant then enters the bottom of the heat exchanger 116 and passes through the heat exchange tubes 170 in a concurrent configuration with the produced fluid passing through the central passage 168. The cooled motor lubricant is then returned to the oil circulation pump 108 through the second oil line 130b.

[035] It will be appreciated that additional embodiments include the countercurrent and concurrent flow configurations discussed above as further modified by connecting the first oil line 130a to the oil circulation pump 118 and the second oil line 130b to the thrust chamber 200 or top of the motor 110. Application- specific design parameters will inform the decisions about whether to make use of concurrent or countercurrent flow configurations and whether to configure the oil circulation pump 118 to discharge motor lubricant into the thrust chamber 200, motor 110 or into the heat exchanger 116.

[036] Thus, the preferred embodiments disclose an improved system for controlling the operating temperature of the motor 110 used to drive the production pump 108. The use of the oil circulation pump 118 and heat exchanger 116 allow for the removal of heat from the pumping system 100 in the hottest portions of the motor 110, where the heat is actually produced. The heat is transferred in a controlled manner by the motor lubricant acting as a heat transfer fluid. The oil circulation pump 118 can be configured to be driven directly by the motor 110 or through a separate oil circulation pump motor 214. Control systems can be used to adjust the performance of the oil circulation pump 118 in response to changes in the temperature of the motor 110. In preferred embodiments, the heat removed from the motor 110 is expelled in the heat exchanger 116, where the velocity of the pumped process fluid is highest.

[037] It is to be understood that even though numerous characteristics and advantages of various embodiments of the present invention have been set forth in the foregoing description, together with details of the structure and functions of various embodiments of the invention, this disclosure is illustrative only, and changes may be made in detail, especially in matters of structure and arrangement of parts within the principles of the present invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. It will be appreciated by those skilled in the art that the teachings of the present invention can be applied to other systems without departing from the scope and spirit of the present invention.

Claims

What is claimed is:

1. A pumping system deployable in a wellbore, the pumping system comprising:

a motor, wherein the motor is filled with a motor lubricant oil;

a production pump driven by the motor;

a heat exchanger; and

an oil circulation pump connected to the motor.

2. The pumping system of claim 1, wherein the oil circulation pump is driven by the motor.

3. The pumping system of claim 1 further comprising:

a first oil line connected between the oil circulation pump and the heat exchanger; and

a second oil line connected between the motor and the heat exchanger.

4. The pumping system of claim 1 further comprising a seal section containing a thrust chamber, and wherein the pumping system further comprises :

a second oil line connected between the thrust chamber and the heat exchanger.

5. The pumping system of claim 4, wherein the heat exchanger comprises: a heat exchanger housing;

a central passage in fluid communication with the production pump; and heat exchange tubes in fluid communication with the first oil line and the second oil line.

6. The pumping system of claim 5, wherein the heat exchanger further comprises a jacket, and wherein the heat exchange tubes are located within the jacket.

7. The pumping system of claim 5, wherein the pumping system further comprises a gas separator and wherein the heat exchanger is connected between the gas separator and the production pump.

8. The pumping system of claim 1, wherein the motor comprises:

a rotor;

a stator assembly, wherein the stator assembly comprises:

a stator core; and

stator coils extending through the stator core; and

a stator-rotor gap between the rotor and the stator assembly.

9. The pumping system of claim 8, wherein the stator core comprises a plurality of stator laminates and wherein each of the stator laminates comprises:

a plurality of stator slots;

a slot liner in each of the plurality of stator slots;

magnet wire extending through each of the slot liners; and a stator slot oil passage extending through each of the slot liners.

10. The pumping system of claim 1, further comprising an intake, wherein the heat exchanger is connected between the intake and the production pump.

11. A cooling system for use in a submersible pumping system that includes an oil-filled electric motor and a production pump driven by the oil-filled electric motor, the cooling system comprising:

a heat exchanger, wherein the heat exchanger comprises:

a central passage in fluid communication with the production pump; and heat exchange tubes adjacent the central passage; and

an oil circulation pump driven by the motor, wherein the oil circulation pump is in fluid communication with the oil-filled electric motor and the heat exchange tubes of the heat exchanger.

12. The cooling system of claim 11 further comprising:

a first oil line connected between the oil-filled motor and a first end of the heat exchange tubes of the heat exchanger; and

a second oil line connected between the oil circulation pump and a second end of the heat exchange tubes of the heat exchanger.

13. The cooling system of claim 12, wherein the cooling system further comprises a closed-loop fluid circulation system between the oil-filled electric motor and the heat exchange tubes of the heat exchanger.

14. A method for controlling the operational temperature of an electric motor in a submersible pumping system disposed in a well, wherein the pumping system includes a production pump driven by the electric motor to produce fluids from the wellbore, the method comprising the steps of:

providing an oil circulation pump connected to the electric motor;

providing a heat exchanger connected to the production pump;

activating the oil circulation pump to move motor lubricant at an initial temperature through the electric motor, wherein the motor lubricant absorbs heat from the operating electric motor;

moving the warmed motor lubricant from the electric motor to the heat exchanger;

activating the production pump to move produced fluids from the wellbore through the heat exchanger, wherein the warmed motor lubricant transfers heat to the produced fluids; and

moving the cooled motor lubricant from the heat exchanger back to the operating motor.

15. The method of claim 14, wherein the step of activating the oil circulation pump comprises:

energizing the electric motor; and

transferring torque from the electric motor to the oil circulation pump through a motor shaft.

16. The method of claim 14, wherein the step of activating the production pump comprises:

energizing the electric motor; and

transferring torque from the electric motor to the production pump through a series of shafts.

17. The method of claim 14, wherein the step of activating the oil circulation pump to move motor lubricant at an initial temperature through the electric motor further comprises moving the motor lubricant through a stator-rotor gap between a stator assembly and rotor within the electric motor.

18. The method of claim 17, wherein the step of activating the oil circulation pump to move motor lubricant at an initial temperature through the electric motor further comprises moving the motor lubricant through stator slot oil passages within stator slots within the electric motor.

19. The method of claim 14, wherein the step of moving the warmed motor lubricant from the electric motor to the heat exchanger further comprises moving the warmed motor lubricant through the heat exchanger in a countercurrent direction to the flow of produced fluids through the heat exchanger.

20. The method of claim 14, wherein the step of moving the warmed motor lubricant from the electric motor to the heat exchanger further comprises moving the warmed motor lubricant through the heat exchanger in a concurrent direction to the flow of produced fluids through the heat exchanger.

21. The method of claim 14, wherein the step of moving the warmed motor lubricant from the electric motor to the heat exchanger further comprises moving the warmed motor lubricant through heat exchange tubes within the heat exchanger.