U.S. patent application number 14/527157 was filed with the patent office on 2015-04-30 for upthrust module for well fluid pump.
The applicant listed for this patent is Baker Hughes Incorporated. Invention is credited to Larry N. Childs, Leslie C. Reid.
Application Number | 20150118067 14/527157 |
Document ID | / |
Family ID | 52995688 |
Filed Date | 2015-04-30 |
United States Patent
Application |
20150118067 |
Kind Code |
A1 |
Childs; Larry N. ; et
al. |
April 30, 2015 |
Upthrust Module for Well Fluid Pump
Abstract
A well fluid pump assembly includes a rotary pump having a
rotatable pump shaft. A motor is cooperatively engaged with the
pump shaft for rotating the pump shaft. An upthrust module has an
upthrust module housing having a lower end secured by a threaded
engagement to an upper end of the pump. An upthrust module shaft is
rotatably mounted in the housing and has a lower end in engagement
with an upper end of the pump shaft for transferring upthrust on
the pump shaft to the upthrust module shaft. An upthrust base is
stationarily mounted in the housing. An upthrust runner is mounted
to the upthrust module shaft for rotation therewith and located
below the upthrust base. The upthrust runner engages the upthrust
base to transfer to the housing upthrust applied to the upthrust
module shaft from the pump shaft.
Inventors: |
Childs; Larry N.; (Tulsa,
OK) ; Reid; Leslie C.; (Coweta, OK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Baker Hughes Incorporated |
Houston |
TX |
US |
|
|
Family ID: |
52995688 |
Appl. No.: |
14/527157 |
Filed: |
October 29, 2014 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61897031 |
Oct 29, 2013 |
|
|
|
Current U.S.
Class: |
417/53 ;
417/365 |
Current CPC
Class: |
F04D 29/588 20130101;
E21B 43/128 20130101; F04D 29/041 20130101; F04D 13/10 20130101;
F04D 29/0413 20130101 |
Class at
Publication: |
417/53 ;
417/365 |
International
Class: |
F04D 29/041 20060101
F04D029/041; E21B 43/12 20060101 E21B043/12; F04D 1/00 20060101
F04D001/00; F04D 29/046 20060101 F04D029/046; F04D 13/10 20060101
F04D013/10; F04D 1/06 20060101 F04D001/06 |
Claims
1. A well fluid pump assembly, comprising: a rotary pump having a
rotatable pump shaft; a motor cooperatively engaged with the pump
shaft for rotating the pump shaft; an upthrust module, comprising:
an upthrust module housing having a lower end secured by a threaded
engagement to an upper end of the pump; an upthrust module shaft
rotatably mounted in the housing and having a lower end in
engagement with an upper end of the pump shaft for transferring
upthrust on the pump shaft to the upthrust module shaft; an
upthrust base stationarily mounted in the housing; and an upthrust
runner mounted to the upthrust module shaft for rotation therewith
and located below the upthrust base, the upthrust runner engaging
the upthrust base to transfer to the housing upthrust applied to
the upthrust module shall from the pump shaft.
2. The assembly according to claim 1, further comprising: a well
fluid discharge adapter on an upper end of the upthrust module for
connection to a string of production tubing.
3. The assembly according to claim 1, further comprising: a well
fluid flow passage extending through the upthrust module for
flowing well from the pump through the upthrust module and to a
wellhead.
4. The assembly according to claim 1, further comprising: a well
fluid flow passage extending through the housing for flowing well
fluid from the pump through the upthrust module; and wherein the
upthrust runner and the upthrust base are positioned in the housing
for immersion in the well fluid flowing through the upthrust
module.
5. The assembly according to claim 1, further comprising: upper and
lower radial support hearings mounted around the upthrust module
shaft in the housing; the upper radial support bearing being
located above the thrust runner and the upthrust base; and the
lower radial support bearing located below the thrust runner and
the upthrust base.
6. The assembly according to claim 1, wherein the upthrust module
shaft is free to move axially a limited extent relative to the
housing.
7. The assembly according to claim 1, wherein: the upper end of the
pump shaft and the lower end of the upthrust module shaft are
splined; and a coupling sleeve with internal splines couples the
upper end of the pump shaft and the lower end of the upthrust
module shaft to each other for rotation therewith.
8. The assembly according to claim 1, further comprising: a radial
support bearing mounted in the housing through which the upthrust
module shaft extends; and wherein the upthrust base is mounted to a
lower side of the radial support bearing.
9. The assembly according to claim 1, further comprising: a below
pump thrust bearing located below the pump and in cooperative
engagement with the pump shaft for accommodating downthrust imposed
on the pump shaft.
10. The assembly according to claim 1, further comprising: a seal
section mounted above the motor and below the pump, the seal
section having a seal section housing containing a movable element
to reduce a pressure differential between well fluid exterior of
the motor and motor lubricant in the motor; a seal section shaft
rotatably mounted in the seal section housing, the seal section
shaft having an upper end in engagement with a lower end of the
pump shaft; and a below-pump thrust bearing located in the seal
section housing in engagement with the seal section shaft for
accommodating downthrust imposed on the pump shaft, the below-pump
thrust bearing being immersed in motor lubricant contained in the
seal section housing.
11. A submersible well pump assembly, comprising: a rotary pump
having a rotatable pump shaft, the pump having a discharge on an
upper end for pumping well fluid up a well; a motor located below
the pump and cooperatively engaged with the pump shaft for rotating
the pump shaft; a lower thrust bearing mounted below the pump and
in cooperative engagement with the pump shaft for absorbing
downthrust applied to the pump shaft, the lower thrust bearing
being immersed in a lubricant that is sealed from well fluid in the
well; and an upper thrust bearing mounted to the discharge of the
pump such that the upper thrust bearing is immersed in well fluid
pumped by the pump out the discharge, the upper thrust bearing
being in cooperative engagement with the pump shaft for absorbing
upthrust on the pump shaft.
12. The assembly according to claim 11, wherein the upper thrust
bearing comprises: an upthrust module housing having a lower end
secured by a threaded engagement to the discharge of the pump; an
upthrust module shaft rotatably mounted in the housing and having a
lower end in engagement with an upper end of the pump shaft for
transferring upthrust on the pump shaft to the upthrust module
shaft; an upthrust base stationarily mounted in the housing; and an
upthrust runner mounted to the upthrust module shaft for rotation
therewith and located below the upthrust base, the upthrust runner
being axially movable with the upthrust module shaft and rotatably
engaging the upthrust base to transfer to the housing upthrust
applied to the upthrust module shaft from the pump shaft.
13. The assembly according to claim 12, further comprising: a well
fluid discharge adapter on an upper end of the upthrust module for
connection to a string of production tubing.
14. The assembly according to claim 12, further comprising: upper
and lower radial support hearings mounted around the upthrust
module shaft in the housing; the upper radial support bearing being
located above the thrust runner and the upthrust base, and the
lower radial support bearing located below the thrust runner and
the upthrust base; and each of the upper and lower radial support
bearings having a well fluid flow passage for flowing well fluid
from the discharge of the pump through the housing.
15. The assembly according to claim 12, further comprising: upper
and lower radial support bearings mounted around the upthrust
module shaft in the housing; the upthrust base being mounted to a
lower side of the upper radial support bearing; the upper and lower
radial support bearings each having a well fluid flow passage; and
wherein annular clearances surround the upthrust base and upthrust
runner within the housing flowing well fluid from the discharge of
the pump through the housing.
16. The assembly according to claim 12, wherein the upthrust module
shaft is free to move axially a limited extent relative to the
housing.
17. A method of pumping well fluid, comprising: (a) cooperatively
coupling a motor to a rotary pump having a rotatable pump shaft and
a discharge end; (b) providing an upthrust module with an upthrust
module housing, an upthrust module shaft rotatably mounted in the
housing, an upthrust base stationarily mounted in the housing, and
an upthrust runner mounted to the upthrust module shaft for
rotation therewith; (c) securing the upthrust module housing to the
discharge end of the pump and coupling the upthrust module shaft to
the pump shaft; (d) operating the pump to pump well fluid out the
discharge end and through the upthrust module housing; and (e)
during upthrust of sufficient magnitude, pushing the upthrust
module shaft upward with the pump shaft, causing the upthrust
runner to engage the upthrust base and transfer upthrust imposed on
the upthrust module shaft to the upthrust runner.
18. The method according to claim 17, wherein: step (d) comprises
immersing the upthrust base and the upthrust runner in the well
fluid flowing through the upthrust module housing.
19. The method according to claim 17, further comprising: in step
(a), mounting a downthrust bearing between the motor and the pump;
and during downthrust, transferring downthrust imposed on the pump
shaft to the downthrust bearing.
20. The method according to claim 17, wherein: step (d) comprises
lowering the motor and the pump into well fluid within a well; step
(d) further comprises immersing the upthrust base and the upthrust
runner in the well fluid flowing through the upthrust module
housing; and wherein the method further comprises: in step (a),
mounting a downthrust bearing within a lubricated environment
between the motor and the pump that is sealed from the well fluid;
and during downthrust, transferring downthrust imposed on the pump
shaft to the downthrust bearing.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to provisional application
Ser. No. 61/897,031 filed Oct. 29, 2013.
FIELD OF THE DISCLOSURE
[0002] This disclosure relates in general to rotary pumps for
pumping well fluid and in particular to an upthrust module that can
be bolted to an upper end of the pump for severe upthrust
conditions.
BACKGROUND OF THE DISCLOSURE
[0003] Electrical submersible pumps (ESP) are often employed to
pump well fluid from wells. A typical ESP includes a rotary pump
driven by an electrical motor. Normally, the ESP is suspended in
the well on a string of production tubing. A seal section, usually
located between the motor and the pump, has a movable element to
reduce a pressure differential between the well fluid exterior of
the motor and motor lubricant contained in the motor. The pump may
be a centrifugal pump having a plurality of stages, each stage
having an impeller and a diffuser. The pump alternately may be
another type.
[0004] During operation both downthrust and upthrust may occur.
During downthrust, a force is imposed on the pump shaft tending to
push the pump shaft downward, or upstream. During upthrust, a force
is imposed on the pump shaft tending to push the pump shaft upward
or downstream. Centrifugal pumps have thrust bearings associated
with at least some, and sometimes all of the stages. The pump stage
thrust bearings may transfer both upthrust and downthrust to the
diffusers and to the pump housing.
[0005] Also, a separate thrust bearing unit will normally be
located below the pump. The thrust bearing components in the thrust
bearing unit are immersed in motor lubricant and may be located in
a lower part of the seal section. The shaft running through the
thrust bearing unit will experience downthrust imposed on the pump
shaft and will transfer that downthrust to the housing containing
the thrust bearing unit. In some cases, the shaft running through
the thrust bearing unit will also experience upthrust from the pump
shaft thrust bearing unit and will transfer the upthrust to the
housing containing the thrust bearing unit. Even if thrust bearings
as described are contained in the pump assembly, under high
upthrust conditions, the transfer of upthrust can be damaging to
the pump.
SUMMARY
[0006] The well fluid pump assembly of this disclosure includes a
rotary pump having a rotatable pump shaft. A motor is cooperatively
engaged with the pump shaft for rotating the pump shaft. An
upthrust module has an upthrust module housing with a lower end
secured by a threaded engagement to an upper end of the pump. An
upthrust module shaft is rotatably mounted in the housing and has a
lower end in engagement with an upper end of the pump shaft for
transferring upthrust on the pump shaft to the upthrust module
shaft. An upthrust base is stationarily mounted in the housing. An
upthrust runner is mounted to the upthrust module shaft for
rotation therewith and located below the upthrust base. During
upthrust, the upthrust runner engages the upthrust base to transfer
to the housing upthrust applied to the upthrust module shaft from
the pump shaft.
[0007] A well fluid discharge adapter may be located on an upper
end of the upthrust module for connection to a sting of production
tubing. A well fluid flow passage extends through the upthrust
module for flowing well fluid from the pump through the upthrust
module and to the production string. Preferably, the upthrust
runner and the upthrust base are positioned in the housing for
immersion in the well fluid flowing through the housing.
[0008] The upthrust module preferably has upper and lower radial
support bearings mounted around the upthrust module shaft in the
housing. The upper radial support bearing is located above the
thrust runner and the upthrust base, and the lower radial support
bearing is located below the thrust runner and the upthrust base.
The upper and lower radial support bearings have well fluid flow
passages. The upthrust base may be mounted to a lower side of the
radial support bearing.
[0009] The upthrust module shaft is free to move axially a limited
extent relative to the housing so as to move upward when pushed by
the pump shaft during upthrust. The upper end of the pump shaft and
the lower end of the upthrust module shaft are splined. A coupling
sleeve with internal splines couples the upper end of the pump
shaft and the lower end of the upthrust module shaft to each other
for rotation therewith. The upper end of the pump shaft moves
upward and abuts the lower end of the upthrust module shaft during
upthrust of sufficient magnitude.
[0010] A lower thrust hearing is located below the pump and in
cooperative engagement with the pump shaft for accommodating
downthrust imposed on the pump shaft. The lower thrust bearing may
be located in the seal section and is immersed in lubricant and
sealed from the well fluid.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] So that the manner in which the features, advantages and
objects of the disclosure, as well as others which will become
apparent, are attained and can be understood in more detail, more
particular description of the disclosure briefly summarized above
may be had by reference to the embodiment thereof which is
illustrated in the appended drawings, which drawings form a part of
this specification. It is to be noted, however, that the drawings
illustrate only a preferred embodiment of the disclosure and is
therefore not to be considered limiting of its scope as the
disclosure may admit to other equally effective embodiments.
[0012] FIG. 1 is a side view of an electrical submersible pump
assembly in accordance with this disclosure.
[0013] FIG. 2 is a sectional view of the upthrust module of the
pump assembly of FIG. 1.
[0014] FIGS. 3A and 3B comprise a sectional view of the seal
section of the pump assembly of FIG. 1.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0015] The methods and systems of the present disclosure will now
be described more fully hereinafter with reference to the
accompanying drawings in which embodiments are shown. The methods
and systems 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.
[0016] 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.
[0017] Referring to FIG. 1, electrical submersible pump assembly
(ESP) 13 is illustrated as being located within a cased well 11.
ESP 13 includes several modules, one of which is a pump 15 that may
be a centrifugal pump having a large number of stages, each stage
being an impeller and a diffuser. Alternately, pump 15 could be
other types that undergo downthrust and upthrust. Pump 15 has an
intake 17 for drawing in well fluid. Another module comprises an
electrical motor 19, which drives pump 15 and is normally a
three-phase AC motor. A third module comprises a protective member
or seal section 21 coupled to motor 19. Seal section 21 has
components to reduce a pressure differential between dielectric
lubricant or oil contained in motor 19 and the pressure of the well
fluid on the exterior of ESP 13. In this example, seal section 21
is located above motor 19 and below intake 17. Intake 17 may be
located in an upper portion of seal section 21 or on a lower end of
pump 15.
[0018] ESP 13 may also include other modules, such as a gas
separator for separating gas from the well fluid prior to the well
fluid flowing into pump 15. If so, intake 17 would be at a lower
end of the gas separator.
[0019] In this disclosure, ESP 13 has an upthrust module 23 mounted
to the upper end of pump 15. The various modules may be shipped to
a well site apart from each other, then assembled with bolts or
other types of fasteners. Upthrust module 23 has an production
tubing adapter 25 on its upper end that secures to a string of
production tubing 27. A power cable 29 extends from motor 19
alongside tubing 27 to a wellhead for supplying power to motor
19.
[0020] Although shown in cased well 11, ESP 13 can alternately be
located on the surface adjacent a wellhead. In that instance, ESP
13 would boost the pressure of well fluid flowing to it such as for
injecting the fluid into a well. If on the surface, ESP 13 would
likely be horizontal rather than vertical as shown in the drawings.
If located on the surface, seal section 21 would not be required.
Although cased well 11 is shown as a vertical well, it could have
an inclined or horizontal section in which ESP 11 locates. The
terms "upper", "lower", "upthrust", and "downthrust" are used
herein only for convenience and not in a limiting manner.
[0021] FIG. 2 illustrates one example of the components of upthrust
module 23. A tubular base 31 is at the lower end of upthrust module
23. Base 31 may connect by a threaded engagement to the upper end
of pump 15 in a variety of manners. FIG. 2 illustrates an external
flange 33 on base 31 through which bolts 35 extend into threaded
holes in pump discharge end 37.
[0022] A lower radial support hearing 39 is stationarily mounted in
base 31. Lower radial bearing 39 has a central opening or journal
that is in sliding engagement with a lower shaft sleeve 41. Lower
shaft sleeve 41 is secured to an upthrust module shaft 43 for
rotation therewith. Lower radial bearing 39 has flow passages 45
extending axially through. It for the passage of well fluid, as
indicated by the arrows. Upthrust module shaft 43 has a splined
lower end 46 that is approximately flush with the lower end of
upthrust module base 31.
[0023] A cylindrical housing 47 secures by internal threads to
external threads on the upper end of base 31. An internal,
cylindrical spacer 49 is closely received, in the inner diameter of
housing 47 and has a lower end in abutment with an upper end of
lower radial bearing 39. An upper radial support bearing 51 is
located in the inner diameter of housing 47 and has a lower end in
abutment with spacer 49. Upper radial bearing 51 has a central
opening or journal that slidingly receives an upper shaft sleeve 53
keyed to shaft 43 for rotation therewith. Upper radial bearing 51
also has axial flow passages 55 for the passage of well fluid.
Upper and lower retaining rings 57, 58 retain shaft 43 within upper
and lower radial bearings 51, 39. Upper retaining ring 57 is
located, above upper radial bearing 51 and lower retaining ring 58
below lower radial bearing 39. The distance between upper and lower
retaining rings 57, 58 is greater than the distance from the lower
side of lower radial bearing 39 to the upper side of upper radial
bearing 51 to as to allow some axial play of shaft 43 relative to
upper and lower radial bearings 51, 39 and to housing 47. The upper
end of shaft 43 terminates within housing 47 a short distance above
upper radial bearing 51.
[0024] An upthrust runner 59 is mounted to shaft 43 between lower
radial bearing 39 and upper radial bearing 51. A retaining ring 61
supports upthrust runner 59 axially on shaft 43, and a key (not
shown) causes upthrust runner 59 to rotate in unison with shaft 43.
Upthrust runner 59 has an upper surface that will slidingly engage
a thrust base or pads 63 secured to the lower side of upper radial
bearing 51 during upthrust. Alternately, thrust pads could be
mounted to upthrust runner 59. The engagement of runner 59 with
thrust base 63 occurs during upthrust conditions on shaft 43. The
outer diameters of thrust runner 59 and thrust base 63 are much
smaller than the inner diameter of housing 47, creating an annular
clearance for the flow of well fluid.
[0025] A discharge head 67 with an upward converging bore 68 has
external threads that engage internal threads in housing 47 above
upper radial bearing 51. The lower end of discharge head 67 bears
against the upper side of upper radial bearing 51, stationarily
securing upper radial bearing 51 in housing 47. The downward force
of the threaded engagement of discharge head 67 transfers through
upper radial bearing 51 and spacer 49 to lower radial bearing 39 to
tightly secure both upper and lower radial bearings 51, 39 in
housing 47. Discharge head 67 secures by a threaded engagement to
production tubing adapter 25. In this example, bolts 69 extend
through holes in production tubing adapter 25 into threaded holes
in discharge head 67.
[0026] The lower end of upthrust module shaft 43 has axially
extending splines that mesh with internal splines in a splined
coupling 70. The upper end of a pump shaft 71 is also splined and
in meshing engagement with the internal splines in splined coupling
70. The upper end of pump shaft 71 is in contact with the lower end
of upthrust module shaft 43 when upthrust occurs on pump shaft 71.
When downthrust occurs on pump shaft 71, a small clearance between
upthrust module shaft 43 and pump shaft 71 may exist, unless pump
shaft 71 and thrust module shaft 43 are fixed to each other for
axial movement in both upthrust and downthrust conditions.
[0027] In this embodiment, upthrust module 23 transfers only
upthrust on pump shaft 71 to housing 47 and not downthrust. ESP 13
has a lower thrust bearing unit assembly that handles downthrust on
pump shaft 73. The thrust bearing assembly could be in a lower
portion of seal section 21, an upper portion of motor 19, or in a
separate module coupled between seal section 21 and motor 19 (FIG.
1). FIGS. 3A and 3B provide an example of a thrust bearing assembly
located within the lower portion of seal section 21. A variety of
thrust bearing assemblies other than the one shown are also
feasible.
[0028] Seal section 21 has an axially extending shaft 72 that
transmits rotation from a motor shaft (not shown) to pump shaft 71
(FIG. 2). A flexible bag or bellows 73 is normally located, in a
seal section housing 75. Well fluid is admitted to housing 75 on
the exterior of bag 73, and lubricant from motor 19 is in fluid
communication with the interior of bag 73. A lower chamber 77
filled with motor lubricant may be within housing 75 below bag
73.
[0029] The lower thrust bearing assembly includes a runner 79
rigidly mounted to seal section shaft 72 and which has a lower side
located above a stationary downthrust base 81 mounted in seal
section housing 75. Downthrust base 81 is supported on a lower
adapter 83 of seal section 21. Lower adapter 83 bolts to the upper
end of motor 19 (FIG. 1). Downthrust imposed on pump shaft 71 (FIG.
2) transfers to seal section shaft 72, and from there through
downthrust runner 79 to downthrust base 81.
[0030] It is not necessary for the thrust bearing assembly in seal
section 21 to handle upthrust, but optionally it may. Unless the
lower end of pump shaft 71 is secured or latched axially to the
upper end of seal section shaft 72, any upthrust imposed on pump
shaft 71 by the pump stages will not transfer to seal section shaft
72. Consequently, the thrust bearing assembly in seal section 21
may be configured to handle only downthrust.
[0031] It is known to axially latch a pump shaft to a seal section
shaft to transfer upthrust to a thrust bearing assembly below the
pump. Also, it is known to configure a thrust bearing assembly
below the pump so as to transfer both upthrust and downthrust. The
thrust bearing assembly shown in FIG. 3B optionally has features to
transfer both downthrust and upthrust. This arrangement allows the
operator to employ ESP 13 without upthrust module 23 for conditions
in which the upthrust is not expected to be severe enough to merit
upthrust module 23. In FIG. 3B, the thrust bearing assembly in seal
section 21 has an upthrust base 85 mounted above thrust runner 79.
Upthrust base 85 is stationarily mounted in seal section housing
75, such as by a retaining ring 87. During upthrust conditions,
thrust runner 79 engages and transfers upthrust to upthrust base 85
if seal section shaft 72 is latched axially to pump shaft 71. At
the same time, if upthrust module 23 is employed, it too will
receive and absorb upthrust from pump shaft 71.
[0032] Thrust runner 79, downthrust base 81 and upthrust base 85
are located in a portion of seal section housing 75 that contains
motor lubricant in fluid communication with the motor lubricant in
motor 19 (FIG. 1). Thus thrust runner 79, downthrust base 81 and
upthrust base 85 are immersed in the motor lubricant. The lubricant
is sealed from well fluid on the exterior of seal section 21.
[0033] Each impeller (not shown) within pump 15 will transmit
upthrust to the next upper diffuser because the impellers are
normally allowed to float axially a limited amount on pump shaft
71. The transfer of some of the upthrust from impellers to
diffusers may occur whether or not upthrust module 23 is utilized.
Thus, if the upthrust is not expected to be high, an operator may
chose to not use upthrust module 23. However, in extreme
conditions, excessive damage to the pump stages can occur unless
upthrust module 23 is employed.
[0034] While the disclosure has been shown in only one of its
forms, it should be apparently to those skilled in the art that it
is susceptible to various modifications.
* * * * *