U.S. patent application number 15/075359 was filed with the patent office on 2016-10-06 for electrical submersible pump with motor winding encapsulated in bonded ceramic.
The applicant listed for this patent is Baker Hughes Incorporated. Invention is credited to Ping Duan.
Application Number | 20160294243 15/075359 |
Document ID | / |
Family ID | 57007253 |
Filed Date | 2016-10-06 |
United States Patent
Application |
20160294243 |
Kind Code |
A1 |
Duan; Ping |
October 6, 2016 |
Electrical Submersible Pump with Motor Winding Encapsulated in
Bonded Ceramic
Abstract
An electrical submersible pump assembly has a motor with a
stator stack of limitations. The stack has slots through which
magnet wires are wound. An encapsulate surrounds and bonds the
magnet wires together within each slot. The encapsulate includes
ceramic particles within a polymer adhesive matrix. The polymer
matrix may be a fluoropolymer adhesive. Each of the magnet wires
may have an electrical insulation layer surrounding a copper core.
The ceramic particles are rounded and much smaller than a
cross-sectional area of each of the magnet wires. At least some of
the magnet wires may be in contact with a perimeter of the slot.
The polymer matrix fills all voids within each of the slots. The
ceramic particles may be porous.
Inventors: |
Duan; Ping; (Cypress,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Baker Hughes Incorporated |
Houston |
TX |
US |
|
|
Family ID: |
57007253 |
Appl. No.: |
15/075359 |
Filed: |
March 21, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62140977 |
Mar 31, 2015 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02K 3/50 20130101; H02K
9/22 20130101; H02K 3/02 20130101; E21B 43/128 20130101; Y10T
29/49009 20150115; H02K 15/105 20130101; H02K 3/30 20130101; H02K
3/345 20130101; E21B 1/00 20130101; F04B 47/06 20130101; H02K 5/132
20130101 |
International
Class: |
H02K 3/34 20060101
H02K003/34; H02K 3/02 20060101 H02K003/02; H02K 5/132 20060101
H02K005/132; H02K 3/30 20060101 H02K003/30 |
Claims
1. An electrical submersible pumping ("ESP") assembly comprising: a
pump driven by an electrical motor; the motor having a stack of
stator laminations, the stator laminations having slots formed
therethrough; magnet wires wound through the slots; and an
encapsulate that bonds the magnet wires within each of the slots
together, the encapsulate comprising ceramic particles bonded
together within a polymer matrix.
2. The ESP assembly of claim 1, wherein the ceramic particles have
a size of 20 mesh to 140 mesh.
3. The ESP assembly of claim 1, wherein the polymer matrix
comprises a fluoropolymer that is selected from a group consisting
of perfluoroalkoxy ("PFA"), fluorinated ethylene propylene ("FEP"),
polytetrafluoroethylene ("PTFE"), and combinations thereof.
4. The ESP assembly of claim 1, wherein each of the magnet wires
comprises an electrical insulation layer surrounding a copper
core.
5. The ESP assembly of claim 1, wherein the ceramic particles are
generally spherical.
6. The ESP assembly of claim 1, wherein each of the ceramic
particles has a cross-sectional area much smaller than a
cross-sectional area of each of the magnet wires.
7. The ESP assembly of claim 1, wherein: each of the slots has a
perimeter; and at least some of the magnet wires are in contact
with the perimeter.
8. The ESP assembly of claim 1, wherein: the polymer matrix fills
all voids within each of the slots.
9. The ESP assembly of claim 1, wherein: the polymer matrix is
formed of an electrical insulation material.
10. The ESP assembly of claim 1, wherein the ceramic particles are
porous.
11. An electrical submersible pumping (ESP) assembly, comprising: a
pump driven by an electrical motor, the motor comprising: a housing
having a longitudinal axis; a slack of stator laminations stacked
on each other within the housing, the stack of stator laminations
having an axial opening and a plurality of slots spaced
circumferentially around the opening; magnet wires wound through
each of the slots in the stack, each of the magnet wires having a
conductive core encased in an electrical insulation layer; a
polymer matrix of an electrical insulation material bonding the
magnet wires within each of the slots together; and ceramic
particles dispersed throughout and bonded within the polymer
matrix.
12. The ESP assembly according to claim 11, wherein: the polymer
matrix comprises a fluoropolymer adhesive.
13. The ESP assembly according to claim 11, wherein: the ceramic
particles have a size of 20 mesh to 140 mesh.
14. The ESP assembly of claim 11, wherein the polymer matrix
comprises a fluoropolymer that is selected from a group consisting
of perfluoroalkoxy ("PFA"), fluorinated ethylene propylene ("FEP"),
polytetrafluoroethylene ("PTFE"), and combinations thereof.
15. The ESP assembly of claim 11, wherein the ceramic particles are
generally spherical.
16. The ESP assembly of claim 11, wherein: each of the slots has a
perimeter; at least some of the magnet wires are in contact with
the perimeter; and a portion of the polymer matrix is in contact
with the perimeter.
17. An electrical submersible pumping (ESP) assembly, comprising: a
pump driven by an electrical motor, the motor comprising: a housing
having a longitudinal axis; a stack of stator laminations stacked
on each other within the housing; the stack of stator laminations
having an axial opening and a plurality of slots spaced
circumferentially around the opening; magnet wires wound through
each of the slots in the stack, each of the magnet wires having a
conductive core encased in an electrical insulation layer; a rotor
extending along the axis through the opening in the stack; a
fluoropolymer adhesive matrix bonding all of the magnet wires
within each of the slots together; and ceramic particles dispersed
throughout and bonded within the fluoropolymer adhesive matrix,
each of the ceramic particles being generally spherical and having
a much smaller cross-sectional than each of the magnet wires.
18. The ESP assembly of claim 17, wherein the fluoropolymer
adhesive matrix comprises a fluoropolymer that is selected from a
group consisting of perfluoroalkoxy ("PFA"), fluorinated ethylene
propylene ("FEP"), polytetrafluoroethylene ("PTFE"), and
combinations thereof.
19. The ESP assembly of claim 17, wherein: each of the slots has a
perimeter; at least some of the magnet wires are in contact with
the perimeter; and the fluoropolymer adhesive matrix is bonded to
the perimeter and fills all voids in each of the slots.
20. The ESP assembly of claim 17, wherein: the ceramic particles
are porous.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to provisional application
Ser. No. 62/140,977, filed Mar. 31, 2015.
FIELD
[0002] The present disclosure relates to downhole pumping systems
submersible in well bore fluids. More specifically, the present
disclosure relates to an electrical submersible pump with motor
windings that are encapsulated in a composition of ceramic and
polymer.
BACKGROUND
[0003] Submersible pumping systems are often used in hydrocarbon
producing wells for pumping fluids from within the well bore to the
surface. These fluids are generally liquids made up of produced
liquid hydrocarbon and often water. One type of system used in this
application employs an electrical submersible pump ("ESP"). ESP's
are typically disposed at the end of a length of production tubing
and have an electrically powered motor. Often, electrical power may
be supplied to the pump motor via an electrical power cable from
the surface that is strapped alongside the tubing.
[0004] ESP motors have stators with axially oriented slots and
insulated magnet wires wound through the slots in a selected
pattern. A sheet of an insulation material is usually wrapped
around each bundle of magnet wires within each of the slots. The
magnet wires extend below a lower end of the stator in loops spaced
around a longitudinal axis of the motor. The magnet wires may be
bonded in the slots with an epoxy resin to resist mechanical
vibration during operation. In one technique, magnet wire leads are
spliced to upper ends of three of the magnet wires. The magnet wire
leads extend from the upper end of the stator to internal contacts
in a motor electrical plug-in receptacle. A dielectric lubricant
fills the motor for lubricating bearings within the motor.
[0005] Typically, the pumping unit is disposed within the well bore
just above where perforations are made into a hydrocarbon producing
zone. In this position the produced fluids flow past the outer
surface of the pumping motor and absorb heat generated by the
motor. In spite of the heat transfer between the fluid and the
motor, the motor may still overheat. Overheating may be a problem
when the fluid has a high viscosity, a low specific heat or a low
thermal conductivity. This is typical of highly viscous crude oils.
Also, the motor may be forced to operate at an elevated temperature
past its normal operating temperature to steam injection wells.
Elevated well temperatures can reduce motor life. Undesirable
chemicals may be formed when the epoxy resin degrades under high
temperature. These chemicals can damage the insulation layers of
the magnet wires.
SUMMARY
[0006] An electrical submersible pumping ("ESP") assembly has a
pump driven by an electrical motor. The motor has a stack of stator
laminations, the stator laminations having slots formed
therethrough. Magnet wires are wound through the slots. An
encapsulate bonds the magnet wires within each of the slots
together. The encapsulate comprises ceramic particles bonded
together within a polymer matrix.
[0007] The ceramic particles may have a size of 20 mesh to 140
mesh. The ceramic particles may be generally spherical. Each of the
ceramic particles has a cross-sectional area much smaller than a
cross-sectional area of each of the magnet wires. The ceramic
particles may be porous.
[0008] The polymer matrix is an electrical insulation material. The
polymer matrix preferably comprises a fluoropolymer that is
selected from a group consisting of perfluoroalkoxy ("PFA"),
fluorinated ethylene propylene ("FEP"), polytetrafluoroethylene
("PTFE"), and combinations thereof.
[0009] In the embodiment shown, each of the magnet wires comprises
an electrical insulation layer surrounding a copper core. Each of
the slots has a perimeter, and at least some of the magnet wires
may be in contact with the perimeter. The polymer matrix fills all
voids within each of the slots.
BRIEF DESCRIPTION OF DRAWINGS
[0010] Some of the features and benefits of the present invention
having been stated, others will become apparent as the description
proceeds when taken in conjunction with the accompanying drawings,
in which:
[0011] FIG. 1 is a transverse cross sectional view of a motor for
use with an electrical submersible pumping system, the motor being
constructed in accordance with this disclosure.
[0012] FIG. 2 is an enlarged view of one of the stator slots of the
motor of FIG. 1, schematically illustrating an encapsulate in the
slot having ceramic particles dispersed within a polymer
matrix.
[0013] FIG. 3 is a side perspective view of an example of a method
of encapsulating magnet wires in the motor of FIGS. 1 and 2.
[0014] FIG. 4 is a side partial sectional view of the motor of FIG.
1 integrated with an electrical submersible pumping system and
disposed in a wellbore.
[0015] While the invention will be described in connection with the
preferred embodiments, it will be understood that it is not
intended to limit the invention to that embodiment. On the
contrary, it is intended to cover all alternatives, modifications,
and equivalents, as may be included within the spirit and scope of
the invention as defined by the appended claims.
DETAILED DESCRIPTION
[0016] The method and system of the present disclosure will now be
described more fully hereinafter with reference to the accompanying
drawings in which embodiments are shown. The method and system of
the present disclosure may be in many different forms and should
not be construed as limited to the illustrated embodiments set
forth herein; rather, these embodiments are provided so that this
disclosure will be thorough and complete, and will fully convey its
scope to those skilled in the art. Like numbers refer to like
elements throughout. In an embodiment, usage of the term "about"
includes +/-5% of the cited magnitude. In an embodiment, usage of
the term "substantially" includes +/-5% of the cited magnitude.
[0017] It is to be further understood that the scope of the present
disclosure is not limited to the exact details of construction,
operation, exact materials, or embodiments shown and described, as
modifications and equivalents will be apparent to one skilled in
the art. In the drawings and specification, there have been
disclosed illustrative embodiments and, although specific terms are
employed, they are used in a generic and descriptive sense only and
not for the purpose of limitation.
[0018] FIG. 1 shows an axial partial sectional view of an upper end
of a motor 10 for use with an electrical submersible pumping system
("ESP"). The motor 10 is equipped with a generally cylindrical
housing 12 which covers and protects components of the motor 10
against harsh downhole conditions, and provides an external support
in which the components are contained. Motor 10 will typically be
filled with a liquid dielectric motor lubricant. Illustrated within
housing 12 is a stator assembly 14, which includes a stator stack
16 made up of a series of laminations that are coaxially stacked
together. Each lamination is a typically a thin, steel disc. The
laminations of stator stack 16 have central openings 17 that define
a bore of stator assembly 14. An annular ring 18 shown set on an
upper surface of stator slack 16 has an inner diameter less than an
outer diameter of stator stack 16 and retains stack 16 within
housing 12.
[0019] A series of slots 20 are formed axially through each of the
laminations in stack 16 and which extend along a length of stack
16. Slots 20 as shown are formed equidistant apart from one
another, extending circumferentially around the bore of the stator
slack 16. Referring to FIG. 2, each slot 20 has a perimeter 21 that
may be generally trapezoidal in shape, as shown. An opening (not
shown) may lead from each slot 20 to central opening 17.
Alternately, each slot 20 may be completely enclosed by its
perimeter 21.
[0020] A number of motor or magnet wires 22 are wound along the
length of each of the slots 20. Normally, motor 10 (FIG. 1) is a
three-phase motor and will have three separate magnet wires 22.
Each magnet wire 22 extends the length of stator assembly 14 and
has multiple turns within each slot 20. Preferably, each magnet
wire 22 has a metal core 22a, normally copper, that is encased in a
high temperature electrical insulation layer 22b.
[0021] An encapsulate 24 surrounds and rigidly bonds the magnet
wires 22 together within each slot 20 and forms a protective
coating around the magnet wires 22. In this embodiment, there is no
liner surrounding the bundle of magnet wires 22 in each slot 20;
rather encapsulate 24 and magnet wires 22 completely fill each slot
20. Part of encapsulate 24 will be bonded to and in contact with
perimeter 21 of each slot 20. Also, some of the magnet wires 22
will be in contact with slot perimeter 21.
[0022] Encapsulate 24 is made up of a mixture of ceramic particles
25 bonded together by a polymer matrix 27. Ceramic particles 25 are
dispersed throughout polymer matrix 27. Ceramic particles 25 are
formed of a hard material with high electrical insulation
properties. Ceramic particles 25 may be porous to the dielectric
motor lubricant contained within motor 10 so as to increase the
rate of heat transfer from motor 10.
[0023] Ceramic particles 25 have cross-sectional dimensions much
smaller than the cross-sectional dimension of each magnet wire 22.
For example, ceramic particles 25 may be in a particle range size
from about 20 mesh to about 140 mesh. In one optional embodiment,
ceramic particles 25 are generally rounded or spherical and do not
have sharp edges. The rounded shape of the ceramic particles 25
reduces the chances for damaging magnet wire insulation layers
22b.
[0024] Ceramic particles 25 may comprise proppants or
micro-spheres, such as those used for downhole gravel packing
having a trade name of Carboaccucast.RTM., and which may be
commercially available from the Carbo Corporation, 575 N. Dairy
Ashford Rd, Suite 300, Houston, Tex., 77079, (281) 921 6400. In a
non-limiting example, ceramic particles 25 may comprise
Carboaccucast.RTM. ID50 having a particle size of from about 50
mesh to about 100 mesh. Alternate embodiments exist wherein ceramic
particles 25 comprise alumina (99.9% Al2O3), aluminum silicate,
Al2SiO5, berillia (99% BeO), boron nitride, BN, cordierite,
Mg2Al4Si5O18, forsterite, mg2SiO4, porcelain, steatite,
Mg3Si4O11.H2O, titanates of Mg, Ca, Sr, Ba, and Pb, barium
titanate, glass bonded, zirconia, ZrO2, fused silica, SiO2, micas,
muscovite, ruby, natural, phlogopite, amber, natural,
fluorophlogopite, synthetic, glass-bonded mica, and combinations
thereof.
[0025] Polymer matrix 27 is formed of a polymer adhesive that heat
cures after filling each slot 20. Example polymer adhesives for
polymer matrix 27 include fluoropolymers. Example fluoropolymers
for polymer matrix 27 include perfluoroalkoxy alkanes ("PFA"),
fluorinated ethylene propylene ("FEP"), and polytetrafluoroethylene
("PTFE"). Preferably, polymer matrix 27 has good chemical
resistance properties at elevated temperatures. Elevated
temperatures are those that can typically occur downhole, and may
be those that exceed about 150.degree. F.
[0026] One method of manufacturing polymer matrix 27 employs a
fluoropolymer supplied as a powder that has a particle size ranging
from about 20 micron to about 200 micron. In a non-limiting
example, polymer matrix 27 may include a fluoro-polymer powdered
binder NC-1500 available from Daikin Chemicals, 20 Olympic Drive
Orangeburg, N.Y. 10962, http://ww.daikin-america.com/, and which is
a thermal-fusible FEP based fine powder having a particle size of
from about 30 microns to about 60 microns.
[0027] Referring again to FIG. 1, a rotor assembly 26 is shown
circumscribed by stator assembly 14, where the rotor assembly 26
rotates with respect to stator assembly 14. Rotor assembly 26
includes several rotor stacks 28 (only one shown) axially separated
from each other by radial bearings. Rotor stack 28, similar to
stator slack 16, is made up of a number of rotor laminations or
steel discs that are stacked on top of one another in a coaxial
arrangement. Slots 30 are formed axially through each of the rotor
laminations, so that when the laminations are stacked, the slots 30
extend through the entire length of the rotor stack 28. Slots 30
are shown substantially equidistant apart from one another at
multiple angular locations around the rotor stack 28. Elongate
rotor bars 32 are set in slots 30, wherein in one example the rotor
bars 32 include a magnetic material. Thus, in one example,
energizing the magnet wires 22 with an electrical current creates
an alternating electromagnetic field (not shown). The rotor bars 32
are responsive to the electromagnetic field thereby causing
rotation of the rotor assembly 26. Coaxial within the rotor
assembly 26 is an elongate shall 34 that couples to and rotates
with the rotor assembly 26.
[0028] In one non-limiting example, the mixture of ceramic
particles 23 and polymer powder for polymer matrix 27 includes
about 100 parts of ceramic particles 25 and about 30 parts of
polymer matrix 27 powder. Ceramic particles 25 may have a size of
about 50 mesh to about 100 mesh, and the powder for polymer matrix
27 may have a particle size of about 30 microns to about 60
microns. Yet further optionally, the polymer matrix 27 may include
a chemical resistant fluoro-polymeric powder, such as FEP. Further
optionally in this example, new stainless steel components are
installed in the stator and end attachments, and the slots 20 in
the stator stack 16 are filled with the mixture of ceramic
particles 25 and powder for polymer matrix 27.
[0029] Schematically illustrated in FIG. 3 is one example of how
the encapsulate 24 of FIGS. 1 and 2 can be formed within slots 20.
As shown, a mixture 38 of ceramic particles 25 and powdered polymer
matrix 27 is combined within a container 36 having an outlet 37.
Mixture 38 exits the outlet 37 and enters a shroud 40 that is set
over the upper end of motor 10. At the opposite end of motor 10 is
a vacuum system 41 that draws air from within the motor 10, and
thus the slots 20 (FIGS. 1 and 2), thereby drawing in mixture 38 to
fill all voids and interstices that may exist between the magnet
wires 22 in the slots 20 (FIGS. 1 and 2). Optionally, a filter 42
may be within vacuum system 41 for blocking ceramic particles 27 or
the powders of polymer matrix 27 from exiting the lower end of
vacuum system 41. In one embodiment filter 42 comprises a 100 mesh
steel screen for capturing ceramic particles 25 and polymer matrix
27 powders that may make their way through the entire length of
motor 10. In one alternative, a vacuum pump 44 is included on the
lower end of vacuum system 41, wherein a hose connects vacuum pump
44 to the lower end of pump 10 so that the vacuum pump 44 can apply
suction to the lower end of the slots 20. A mechanical shaker (not
shown), can be used to further ensure mixture 38 fills any
remaining voids in the slots 20.
[0030] After mixture 38 of ceramic particles 25 and polymer matrix
27 powders fill slots 20 around magnet wires 22, mixture 38 can be
heated. The heating may be done either by heating the entire motor
10 or by conducting electricity through magnet wires 22 for heating
the mixture 38. In one example, a melting point of the powders of
polymer matrix 27 is about 260.degree. C. to about 350.degree. C.;
thus the mixture 38 is heated to at feast this temperature, thereby
melting the powders of polymer matrix 27. The heating and
subsequent cooling causes bonding of ceramic particles 25 within
polymer matrix 27 to magnet wires 22, forming a solid, rigid
encapsulate 24 within slots 20 for projecting wires 22. The heating
does not affect ceramic particles 25.
[0031] Optionally, heating of the entire motor 10 can take place
within a high temperature tubular oven 43. In a non-limiting
example, the motor 10 is heated for a period of time up to about 5
hours, and the upper and lower openings of slots 20 are plugged to
retain mixture 38 in the slots 20. Yet further optionally, a
nitrogen blanket is applied to the motor 10 to remove volatiles
released during heating. Melting, then cooling the polymer matrix
27 powders forms an integrated tough structural bonding material
that secures the magnet wires 22 in place within slots 20. As
indicated above, the presence of ceramic particles 25 within the
encapsulate 24 creates a porosity for encapsulate 24, which
increases heat transfer away from motor.
[0032] Shown in partial side sectional view in FIG. 4 is one
example of the motor 10 used in conjunction with an electrical
submersible pump (ESP) system or assembly 45. Here the ESP system
45 is disposed in a wellbore 46 on a lower end of a suing of
production tubing 48. An upper end of production tubing 48 connects
to a wellhead assembly 50, shown capping an upper end of wellbore
46. Motor 10 couples to a pump 58, which is shown provided on an
upper end of ESP system 45. Shaft 34 connects to impellers 54
(shown in phantom view) within pump 58. Pump 58 pumps well fluid
from within wellbore 46 so it may be discharged to the production
tubing 48 and pumped to the wellhead assembly 50. A seal section 56
is provided between the pump 52 and motor 10 for equalizing
pressure within the ESP system 45 with the hydrostatic pressure of
well fluid in wellbore 46. An intake 58 is shown formed through a
housing of the pump 52 so that fluid within wellbore 46 can make
its way to the impellers 54 for pressurization and delivery to
production tubing 48. In this example, the fluids pressurized by
the ESP system 45 are produced from a formation 60 that is
intersected by the wellbore 46.
[0033] The present invention described herein is well adapted to
carry out the objects and attain the ends and advantages mentioned,
as well as others inherent therein. The chemically inert
encapsulation of the motor wires replaces chemically instable epoxy
resin. While a presently preferred embodiment of the invention has
been given for purposes of disclosure, numerous changes exist in
the details of procedures for accomplishing the desired results.
These and other similar modifications will readily suggest
themselves to those skilled in the art, and are intended to be
encompassed within the spirit of the present invention disclosed
herein and the scope of the appended claims.
* * * * *
References