U.S. patent application number 12/893553 was filed with the patent office on 2012-03-29 for pump shaft bearing support.
Invention is credited to MIKEL ERIC JANITZ.
Application Number | 20120073800 12/893553 |
Document ID | / |
Family ID | 45869450 |
Filed Date | 2012-03-29 |
United States Patent
Application |
20120073800 |
Kind Code |
A1 |
JANITZ; MIKEL ERIC |
March 29, 2012 |
PUMP SHAFT BEARING SUPPORT
Abstract
A device and method of tailoring a pump lift capacity of a pump
for an electrical submersible pumping unit (ESP). The pump unit of
the ESP has a plurality of stages, each made up of an impeller and
a diffuser. The ESP has a pump lift capacity, which is ideally
matched with well capacity. The well capacity is, therefore, the
target lift capacity. To facilitate matching of pump lift capacity
and well capacity, one or more stages of the pump unit may be
replaced with a spacer assembly to reduce pump lift capacity by a
desired amount. The spacer assembly may include a shaft bearing
support made up of an outer ring and an inner ring, wherein the
outer and inner ring are connected by webs, which allow oil to flow
through the support. The spacer assembly may be axially located on
the pump shaft via compression tubes.
Inventors: |
JANITZ; MIKEL ERIC;
(Sapulpa, OK) |
Family ID: |
45869450 |
Appl. No.: |
12/893553 |
Filed: |
September 29, 2010 |
Current U.S.
Class: |
166/105 ;
417/410.1 |
Current CPC
Class: |
F04D 13/10 20130101;
F04D 29/0462 20130101; F04D 29/043 20130101; E21B 43/128
20130101 |
Class at
Publication: |
166/105 ;
417/410.1 |
International
Class: |
E21B 43/00 20060101
E21B043/00; F04B 35/04 20060101 F04B035/04 |
Claims
1. A pump unit for an centrifugal pump comprising: a pump unit
having an intake end and an output end, said pump unit including a
housing; a pump shaft extending through said housing; a plurality
of impellers affixed to said pump shaft for rotating with said pump
shaft; a diffuser adjacent to each of said impellers for directing
fluid flow towards a center of said housing; wherein each pair of
said impellers and said diffusers comprises a stage; a spacer
assembly surrounding a portion of said pump shaft within said
housing; a motor in communication with said pump shaft, said motor
for rotating said pump shaft.
2. The pump unit according to claim 1 wherein said spacer assembly
comprises: a shaft bearing support; wherein the shaft bearing
support minimizes deflection of said pump shaft while the pump unit
is in operation.
3. The pump unit according to claim 2 wherein said shaft bearing
support comprises: an outer ring that defines an outside diameter
of said shaft bearing support; an inner ring that defines an inside
diameter of said shaft bearing support; a plurality of webs for
connecting said outer ring to said inner ring, said webs defining a
plurality of voids therebetween; wherein said inner ring is sized
to receive said pump shaft.
4. The pump unit according to claim 2 wherein said spacer assembly
further comprises a first compression tube adjacent to a first side
of said shaft bearing support.
5. The pump unit according to claim 2 wherein said spacer assembly
further comprises: a second compression tube adjacent to a second
side of said shaft bearing support.
6. The pump unit according to claim 3 wherein said webs of said
shaft bearing support are tapered.
7. The pump unit according to claim 3 wherein said webs of said
shaft bearing support are angled.
8. The pump unit according to claim 3 wherein said webs of said
shaft bearing support are twisted.
9. The pump unit according to claim 3 further comprising: a first
compression tube adjacent to a first side of said shaft bearing
support; and wherein said first compression tube has a diameter
approximately equal to said outer ring of said shaft bearing
support.
10. A well comprising: a wellhead; casing extending below said
wellhead; tubing extending downwardly from said wellhead within
said casing; a pump unit having an intake end and an output end,
said output end affixed to said tubing for delivering fluids to
said tubing, said pump unit including a housing; a pump shaft
extending through said housing; a plurality of impellers affixed to
said pump shaft for rotating with said housing; a diffuser adjacent
to each of said impellers for directing fluid flow towards a center
of said housing; wherein each pair of said impellers and said
diffusers comprises a stage; a spacer assembly surrounding a
portion of said pump shaft within said housing; a motor in
communication with said pump shaft, said motor for rotating said
pump shaft.
11. The well according to claim 10 wherein said spacer assembly
comprises: a shaft bearing support; wherein the shaft bearing
support minimizes deflection of said pump shaft while said pump
unit is in operation.
12. The well according to claim 11 wherein said shaft bearing
support comprises: an outer ring that defines an outside diameter
of said shaft bearing support; an inner ring that defines an inside
diameter of said shaft bearing support, a plurality of webs for
connecting said outer ring to said inner ring, said webs defining a
plurality of voids therebetween; wherein said inner ring is sized
to receive said pump shaft.
13. The well according to claim 11 wherein said spacer assembly
comprises: a first compression tube adjacent to a first side of
said shaft bearing support.
14. The well according to claim 13 wherein said spacer assembly
comprises: a second compression tube adjacent to a second side of
said shaft bearing support.
15. The well according to claim 12 wherein said webs of said shaft
bearing support are tapered.
16. The well according to claim 12 wherein said webs of said shaft
bearing support are angled.
17. The well according to claim 12 wherein said webs of said shaft
bearing support are twisted.
18. The well according to claim 12 further comprising: a first
compression tube adjacent a first side of said shaft bearing
support; and wherein said first compression tube has a diameter
approximately equal to said outer ring of said shaft bearing
support.
19. A method of tailoring a pump lift capacity of a pump for an
electrical submersible pumping unit comprising the steps of:
determining a target pump lift capacity; selecting a pump having a
stage and series sized to have a pump lift capacity greater than
said target pump lift capacity; removing at least one stage from
said pump; replacing said at least one stage with a spacer assembly
for reducing said pump lift capacity to more closely match said
target pump lift capacity.
Description
FIELD OF THE INVENTION
[0001] The invention relates to electrical submersible pumps. More
particularly, the invention relates to replacing one or more pump
stages with a spacer, or pump shaft bearing support, for fine
tuning a pump's lift capacity to more closely match well
capacity.
BACKGROUND OF THE INVENTION
[0002] Electrical submersible pumps (ESP) are used to artificially
lift well fluid from deep underground. Primarily, ESPs are used to
pump oil, typically as part of an oil and water mix, from deep
wells at high pressures. ESPs are driven by long tubular, high
horsepower, electric inductance motors that typically run at speeds
of approximately 3,500 rpm. A common type of pump used in an ESP is
a pump generally known as a centrifugal pump. Centrifugal pumps are
made up of six (6) primary components. The major components are the
housing, shaft, head, base, impeller and diffuser. The impeller and
diffuser, when paired together, are referred to as stages.
[0003] Pumps are designed, manufactured and marketed by stage and
series. The term "stage" reflects stage variation or the number of
stages in a pump. "Stage" is a term used to communicate accurately
the amount of fluid a pump can lift in a day. A common daily rate
of lift is described in barrels per day. For example "D50" refers
to a pump with an impeller and diffuser combination, i.e., stage,
that is able to lift 50 gallons per hour under specific power
requirements, rpm and well fluid levels. Therefore, pump stages are
an important consideration when sizing an ESP for a well.
[0004] "Series" is a term that directly relates to a pump's outside
diameter (O.D.) and indirectly to a well casing inside diameter
(I.D.). Pumps are designed, manufactured and sold in many different
series so that pumps may be easily sized to fit into a well casing
and to allow room for the pump's housing and for power cable
clearance. Common series in the industry are 300, 400, 500, 675 and
so on. A 500 series pump will fit into a well casing I.D of 6.50
inches. An incorrectly sized pump runs the risk of getting stuck in
the casing.
[0005] The larger the series number and the larger the stage number
and amount of stages, the more fluid a pump can lift in a given
time period. The amount of fluid that a pump can lift in a given
time period is referred to as lift capacity. However, the lift
capability of a pump is not only dependent on pump diameter, pump
size and number of stages, but it is ultimately tied to the
capability of a well to produce fluid.
[0006] A well will produce only the quantity of fluid that is
released from a well formation under the surface. Wells are logged
and evaluated to determine their ability to produce fluid, known as
capacity. Capacity is important for two reasons. First, lifting
more fluid than the well can produce will run a pump dry and
irreparably damage the pump. Second, to maximize profits,
production and efficiency, a pump needs to lift exactly the amount
of fluid that a well will provide. Therefore, sizing the pump is
critical.
[0007] In the past, pump manufactures were only able to get close
to providing a pump with the amount of stages to exactly match lift
with well capacity. This is due to limitations imposed by commonly
available housing lengths and stage configurations.
[0008] Several methods have been utilized to match pump lift
capacity with well capacity. One way to size a pump is to tie pumps
together, i.e., a tandem pump, so that the stages add up closely to
the requirements. A disadvantage with this solution is that the use
of tandem pumps is a costly solution to the customer.
[0009] Another way to avoid pumping off or under pumping a well is
to control the speed (rpm) of a pump with a variable speed drive
(VSD). The flow rate of the pump can be controlled by a VSD. The
VSD actively monitors the fluid discharge rates to increase or
decrease the pump's speed. A disadvantage associated with the use
of VSDs is that VSDs are relatively expensive and costly to
operate, thus costing the customer more.
SUMMARY OF THE INVENTION
[0010] Therefore, it is desirable to provide a low cost method of
matching pump lift components with well capacity. The pump lift
capacity of a pump can be modified by the replacement of one or
more stages with a shaft bearing support of the invention.
[0011] By adding the shaft bearing support of the invention, a
given housing can be used with the exact number of stages required
to effectively pump fluid out of a well, which allows for a well to
be pumped without running the well dry and without leaving any
fluid below. This invention will maximize profits and efficiency
while minimizing wear and tear on the equipment.
[0012] The shaft bearing support of the invention is made up of
several features. The outside diameter of the shaft bearing support
is an outer ring that fits inside a pump housing. Webs connect the
outer ring to an inner ring, which defines an inside diameter of
the shaft bearing support. Therefore, the inner ring is fixed
relative to the outside diameter ring. Both the outer and inner
rings have a sufficient width and depth to be mechanically sound.
The inner ring of the shaft bearing support has an inner diameter
(ID) that is large enough to allow the pump shaft to pass
therethrough and to accommodate a fluid bearing between the pump
shaft and the ID of the inner ring. The webs of the shaft bearing
support define a volume or void between each web so that pumped
fluid can move through the voids defined by the pump shaft bearing
support with minimal obstruction or frictional loss.
[0013] One or more compression tubes may be located adjacent to the
shaft bearing support. The orientation and configuration of the
compression tubes relative to the shaft bearing support to the
stage can vary. The compression tubes may be located toward the
head, they can be toward the base, or they can be anywhere in
between. A common orientation is to locate a first compression tube
adjacent to the head, then locate a first side of the shaft bearing
support adjacent to the first compression tube. A second
compression tube may then be located adjacent to a second side of
the shaft bearing support.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a schematic representation of a typical ESP
deployed in a well.
[0015] FIG. 2 is an exploded perspective view of a pump section of
the ESP of FIG. 1, equipped with a pump shaft bearing support of
the invention.
[0016] FIG. 3 is an enlarged perspective view of the pump shaft
bearing support of FIG. 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0017] Referring now to FIG. 1, shown is a well designated
generally 10. The well consists of casing 12. Tubing 14 extends
downwardly into casing 12 from wellhead 16. An electrical
submersible pump (ESP) unit, designated generally 18, is suspended
from tubing 14. ESP unit 18 has a centrifugal pump unit 20. Pump
unit 20 has an intake end 22 and an output end 24. Output end 24 is
affixed to tubing 14 for delivering fluids to tubing 14.
[0018] Pump unit 20 further includes a housing 26. A pump base 28
(FIG. 2) is affixed to intake end 22 of housing 26. Pump head 30 is
affixed to output end 24 of housing 26. Pump shaft 32 extends
through housing 26. A plurality of impellers 34 are affixed to pump
shaft 32 for rotating with pump shaft 32. A plurality of diffusers
36 are located adjacent to each of impellers 34 for directing fluid
flow toward a center of an adjacent impeller 34. As shown in FIG.
2, each of said impellers 34 and diffusers 36 comprise a stage
38.
[0019] ESP unit 18 additionally may be provided with gas separator
40 (FIG. 1), which is typically affixed to pump base 30. Seal
section 42 is affixed to lower end of gas separator 40. Motor 44 is
affixed to a lower end of seal section 42. Motor 44 is used to
rotate pump shaft 32.
[0020] Referring now to FIGS. 2, 3, pump unit 20 may be provided
with a spacer assembly 46 that surrounds a portion of pump shaft 32
within pump housing 26. Spacer assembly 46 preferably includes a
shaft bearing support 48. Shaft bearing support 48 has an outer
ring 50 that defines an outside diameter of pump shaft bearing
support 48. Pump shaft bearing support 48 additionally has an inner
ring 52 that defines an inside diameter of pump shaft bearing
support 48. Inner ring 52 is for receiving pump shaft 32. A
plurality of webs 54 define a plurality of voids therebetween.
[0021] In a preferred embodiment, shaft bearing support 48 is
preferably a cast part made from Ni-resist and then machined to
exact specifications. Webs 54 may be oriented perpendicularly to a
central axis 53 of shaft bearing support 48, e.g., webs 54a.
Alternatively, webs 54 may be tapered, e.g., 54b (FIG. 3B), angled,
e.g., 54c (FIG. 3C), or twisted, e.g., 54d (FIG. 3D) to affect
fluid flow passing over shaft bearing support 48.
[0022] Referring back to FIG. 2, spacer assembly 46 is made up of a
first compression tube 55 (FIG. 2) located adjacent to a first side
of shaft bearing support 48 and may include a second compression
tube 58 located adjacent to a second side of shaft bearing support
48. Compression tubes 55 and 58 axially locate shaft bearing
support 48 within housing 26 of pump unit 20. First and second
compression tubes 55, 58, preferably have a diameter that is
approximately equal to outer ring 50 of shaft bearing support 40.
Compression tubes 55, 58 and shaft bearing support 48 preferably do
not rotate.
[0023] In use, a lift capacity of ESP unit 18 may be modified by
replacing one or more stages 38, preferably 8 to 10 stages 38, of
pump unit 20 with spacer assembly 46, such as a spacer assembly
made up of shaft bearing support 48, first compression tube 55, and
possibly second compression tube 58. Multiple spacer assemblies 46
can be located within housing 26, e.g., multiple spacer assemblies
46 may be placed end to end. Other spacer assembly configurations
may also be utilized that support pump shaft 32 and occupy space
surrounding a length of pump shaft 32. By fine tuning the lift
capacity of ESP unit 18 in this manner, the lift capacity may be
made to more closely match the well capacity of well 10.
[0024] Thus, the present invention is well adapted to carry out the
objectives and attain the ends and advantages mentioned above as
well as those inherent therein. While presently preferred
embodiments have been described for purposes of this disclosure,
numerous changes and modifications will be apparent to those of
ordinary skill in the art. Such changes and modifications are
encompassed within the spirit of this invention as defined by the
claims.
* * * * *