U.S. patent application number 15/569923 was filed with the patent office on 2018-05-31 for electrical submersible motor.
The applicant listed for this patent is Coreteq Systems Ltd.. Invention is credited to Philip HEAD, Hassan MANSIR.
Application Number | 20180149173 15/569923 |
Document ID | / |
Family ID | 53488814 |
Filed Date | 2018-05-31 |
United States Patent
Application |
20180149173 |
Kind Code |
A1 |
HEAD; Philip ; et
al. |
May 31, 2018 |
ELECTRICAL SUBMERSIBLE MOTOR
Abstract
A fluid system for a pump, which includes a downhole rotating
shaft and bearings inside a housing, and where a fluid volume
around shaft is circulated from outside housing through a filter,
so that only clean non-abrasive fluid is permitted inside fluid
volume pump to draw fluid around the shaft. A fluid expeller is
included to expel fluid from the accumulated volume of fluid
through the filter to purge the filter.
Inventors: |
HEAD; Philip; (Virginia
Water, Surrey, GB) ; MANSIR; Hassan; (Maidenhead,
GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Coreteq Systems Ltd. |
Lyon Way Frimley, Surrey |
|
GB |
|
|
Family ID: |
53488814 |
Appl. No.: |
15/569923 |
Filed: |
April 28, 2016 |
PCT Filed: |
April 28, 2016 |
PCT NO: |
PCT/GB2016/051225 |
371 Date: |
October 27, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04C 13/008 20130101;
F04D 1/06 20130101; F04D 29/708 20130101; F04D 13/0633 20130101;
F04D 29/061 20130101; E21B 43/128 20130101; F04C 13/005 20130101;
F04D 7/045 20130101; F04D 29/043 20130101; F04D 13/086 20130101;
F04D 13/10 20130101; F04B 47/06 20130101; F04D 13/062 20130101;
F04C 2210/62 20130101 |
International
Class: |
F04D 29/70 20060101
F04D029/70; E21B 43/12 20060101 E21B043/12; F04D 13/08 20060101
F04D013/08; F04D 29/06 20060101 F04D029/06; F04D 13/06 20060101
F04D013/06 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 28, 2015 |
GB |
1507260.6 |
Claims
1. A fluid system for a pump, which includes: a downhole rotating
shaft and bearings inside a housing, a fluid volume around the
shaft, a circulating fluid from outside the housing through a
filter, such that only clean non-abrasive fluid is permitted inside
fluid volume pump to draw fluid around the shaft.
2. A fluid system according to claim 1, further including a fluid
expeller to expel fluid from the accumulated volume of fluid
through the filter to purge the filter.
3. A fluid system according to claim 1, further including a fluid
passage through a bearing or bearings.
4. A fluid system according to claim 1, further including a
protector hood to deflecting falling solids coming out of
suspension.
5. A fluid system according to claim 1, further including a bore
through the shaft.
6. A fluid system according to claim 1, further including a valve
and inlet port a piston and a valve and outlet port to backflush
the system.
7. A fluid system according to claim 6, further including a cam on
the shaft to drive the fluid through the inlet valve.
8. A fluid system according to claim 1, wherein two such systems
are included at each end of a rotor.
9. A fluid system according to claim 1, wherein there is a
continuous fluid flow through rotor
Description
FIELD OF THE INVENTION
[0001] The invention relates to a fluid filter to extend the
protector life or eliminate protector of a canned electrical
submersible motor.
BACKGROUND OF THE INVENTION
[0002] In a variety of wellbore environments, electric submersible
pumping systems are used to lift fluids from a subterranean
location. Although electric submersible pumping systems can utilize
a wide variety of components, examples of basic components comprise
a submersible pump, a submersible motor and a motor protector. The
submersible motor powers the submersible pump, and the motor
protector seals the submersible motor from well fluid.
[0003] The motor protector also balances the internal motor oil
pressure with external pressure. Motor protectors often are
designed with a labyrinth system and/or an elastomeric bag system.
The labyrinth system uses the difference in specific gravity
between the well fluid and internal motor oil to maintain
separation between the fluids. The elastomeric bag system relies on
an elastomeric bag to physically isolate the motor oil from the
well fluid while balancing internal and external pressures.
Additionally, motor protectors often have an internal shaft that
transmits power from the submersible motor to the submersible pump.
The shaft is mounted in journal bearings positioned in the motor
protector.
[0004] Such protectors function well in many environments. However,
in abrasive environments, the run life of the motor protector can
be detrimentally affected. The abrasive sand causes wear in motor
protector components, such as the journal bearings. Attempts have
been made to increase run life by populating the motor protector
with journal bearings made from extremely hard materials to reduce
wear caused by the abrasive sand.
[0005] In general, the present invention relates to a motor
protector for use in an electric submersible pumping system, or
potentially the elimination of the protector in the event of a
"canned" motor.
[0006] For non-canned motors, the protector is designed to seal a
submersible motor from well fluid and to keep the motor oil
pressure generally balanced with external pressure.
SUMMARY OF THE INVENTION
[0007] According to the present invention, there is provided a
means for preventing sand/solids from entering the motor rotor
cavity.
[0008] According to further aspect of the invention, there is
provided a means for preventing sand/solids from entering the motor
protector rotor cavity.
[0009] According to a further aspect of the invention, the outer
most bearing is continuously flushed with filtered well bore
fluid.
[0010] According to further aspect of the invention, the motor
rotor cavity is pressure balanced by a filter medium which allows
fluid to both enter and leave the rotor cavity but no solids can
enter the rotor cavity.
[0011] According to a further aspect of the invention positive
fluid flow is promoted at the use of a flow energising device.
[0012] According to a further aspect of the invention any
sand/solid is deflected away from the top of the protector or
output shaft from the motor.
[0013] According to a further aspect of the invention the rotor
cavity will operate with filtered wellbore fluids.
[0014] According to a further aspect of the invention, the rotor
cavity will match the pressure outside of the motor instantaneously
as the filter medium provides direct communication between the
two.
[0015] According to a further aspect of the invention, the pump
bearings will be lubricated with filtered fluid.
[0016] According to a further aspect of the invention the filter is
back flushed.
[0017] This invention protects the outer seal and bearing of the
protector by circulating clean filtered fluid from the inside to
the outside.
[0018] This invention for canned motors ensures only clean filtered
fluid can enter the rotor cavity.
[0019] Clean filtered fluid in the rotor cavity ensures long run
life.
[0020] Canned motor ensures motor windings do not fail because of
protector failure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a front elevation view of an electric submersible
pumping system disclosed in a wellbore, according to an embodiment
of the present invention;
[0022] FIG. 2 is a longitudinal sectional view taken generally
along an axis of a motor protector illustrated in FIG. 1
[0023] FIG. 3 is a longitudinal section side view of the flow
promotion device fitted between the protector and pump inlet.
[0024] FIG. 4 is a more detailed section side view of the flow
promotion device shown in FIG. 3.
[0025] FIG. 5 is a longitudinal section side view of a canned motor
with the filter inlet/outlets fitted at its upper and lower
ends.
[0026] FIG. 6 is a more detailed section side view of output end of
the motor shown in FIG. 5.
[0027] FIG. 7 is a more detailed section side view of the lower end
of the motor shown in FIG. 5.
[0028] FIG. 8 is a similar view to FIG. 3 with the pump section
above the flow promotion device highlighted.
[0029] FIG. 9 is a more detailed section side view of the part
highlighted in FIG. 8.
[0030] FIG. 10 is a section side view of the back flush
mechanism
[0031] FIG. 11 is a similar view to FIG. 9, with the back flush in
operation
[0032] FIG. 12 is a more detailed of the back flush mechanism shown
in the view indicated of FIG. 11
[0033] In the following description, numerous details are set forth
to provide an understanding of the present invention. However, it
will be understood by those of ordinary skill in the art that the
present invention may be practiced
[0034] without these details and that numerous variations or
modifications from the described embodiments may be possible.
[0035] The present invention generally relates to a system and
method for reducing detrimental effects of sand on motor
protectors. The system and method are useful with, for example, a
variety of downhole production systems, such
[0036] as electric submersible pumping systems. However, the
devices and methods of the present invention are not limited to use
in the specific applications that are described herein.
[0037] Referring generally to FIG. 1, an example of a pumping
system 10, such as an electric submersible pumping system, is
illustrated according to an embodiment of the present invention.
Pumping system 10 may comprise a variety of components depending on
the particular application or environment in which it is used. In
this example, however, pumping system 10 includes a submersible
pump 12, a submersible motor 14 and a motor protector 16.
[0038] Pumping system 10 is designed for deployment in a well 18
within a geological formation 20 containing desirable production
fluids, such as water or petroleum. A wellbore 22 typically is
drilled and lined with a wellbore casing 24. Wellbore casing 24
includes a plurality of openings or perforations 26 through which
production fluids flow from formation 20 into wellbore 22.
[0039] Pumping system 10 is deployed in wellbore 22 by a deployment
system 28 that may have a variety of forms and configurations. For
example, deployment system 28 may comprise tubing, such as coil
tubing or production tubing, connected to pump 12 by a connector
32. Power is provided to submersible motor 14 via a power cable 34.
Motor 14, in turn, powers pump 12 which draws production fluid in
through a pump intake 36, and pumps the production fluid to the
surface via tubing 30.
[0040] It should be noted that the illustrated submersible pumping
system 10 is merely an example. Other components can be added to
this system and other deployment systems may be implemented.
Additionally, the production fluids may be pumped to the surface
through tubing 30 or through the annulus formed between deployment
system 28 and wellbore casing 24. In any of the many potential
configurations of submersible pumping system 10, motor protector 16
is used to seal the submersible motor 14 from well fluid in
wellbore 22 and to generally balance the internal pressure within
submersible motor 14 with the external pressure in wellbore 22.
[0041] Referring generally to FIG. 2, an embodiment of motor
protector 16 is illustrated in greater detail. Motor protector 16
comprises an outer housing 38 within which a drive shaft 40 is
rotatably mounted via a plurality of bearings 42, such as journal
bearings. Outer housing 38 may be formed of one or more housing
components. Also, the motor protector 16 is divided into a
plurality of sections, including a head section 44 disposed
generally at an upper end of the protector. An additional section
(or sections) is disposed below head section 44 and functions as a
fluid separation section to separate wellbore fluid that may enter
head section 44 from internal motor oil used to lubricate
submersible motor 14. The sections also facilitate balancing of
internal and external pressures. In the embodiment illustrated, a
labyrinth section 46 is disposed below head section 44, and a pair
of elastomeric bag sections 48 are disposed below labyrinth section
46.
[0042] Labyrinth section 46 comprises a labyrinth 50 that uses the
difference in specific gravity of the well fluid and the internal
motor oil to maintain separation between the internal motor oil and
the well fluid. Each bag section uses an elastomeric bag 52 to
physically isolate the internal motor oil from the well fluid. It
should be noted that the motor protector sections may comprise a
variety of section types. For example, the motor protector may
comprise one or more labyrinth sections, one or more elastomeric
bag sections, combinations of labyrinth and bag sections as well as
other separation systems. A series of fluid ports or channels 54
connect each section with the next sequential section. In the
embodiment illustrated, a port 54 is disposed between head section
44 and labyrinth section 46, between labyrinth section 46 and the
next sequential bag section 48, between bag sections 48 and between
the final bag section 48 and a lower end 56 of motor protector
16.
[0043] Motor protector 16 may comprise a variety of additional
features. For example, a thrust bearing 58 may be deployed
proximate lower end 56 to absorb axial loads placed on shaft 40 by
the pumping action of submersible pump 12. The protector also may
comprise an outward relief mechanism 60, such as an outward relief
valve. The outward relief valve releases excessive internal
pressure that may build up during, for example, the heating cycle
that occurs with start-up of electric submersible pumping system
10. Motor protector 16 also may comprise an inward relief mechanism
62, such as an inward relief valve. The inward relief valve
relieves excessive negative pressure within the motor protector.
For example, a variety of situations, such as system cool down, can
create substantial internal pressure drops, i.e. negative pressure,
within the motor protector. Inward relief mechanism 62 alleviates
the excessive negative pressure by, for example, releasing external
fluid into the motor protector to reduce or avoid mechanical damage
to the system caused by this excessive negative pressure.
[0044] Referring to FIGS. 3 and 4 there is shown the output shaft
from the protector 100 passing through the assembly 101, the shaft
100 is supported in bearings 102 and 103, and drives the pump via
splined output 104 via coupling 105. The pump inlet is shown as
passages 106. In the event the pump is stopped and sand particles
fall out of suspension, they will contact the deflector 107 mounted
on the shaft, fall on the sloping surface 108 and fall into the
annulus around the pump.
[0045] When the shaft 100 is rotating, fluid is drawn through ports
109 through a filter medium 110 into a gallery 111 and pressurized
by a screw type pump mechanism 112 back through the bearing 103 and
underneath the deflector 113. This ensures only clean fluid without
any damaging solid particles in it is above the protector,
maximising the protector's life. In addition, because the bearing
103 will not deteriorate due to erosion, no additional vibrations
will be generated.
[0046] Referring to FIGS. 5 to 7, there is shown a canned motor
assembly. This is where the stator 120 is physically isolated from
the rotor cavity 122 by a tube 124. This is particularly
advantageous with this invention, as the protector can be
eliminated. At the output end above the thrust bearing assembly 114
is an identical mechanism 125 described in relation to FIG. 4. At
the motors lower end, the rotor cavity 115 is equalised with the
fluid around the outside of the motor via a filter medium 117 and
ports 118 and 119. The filter medium can be selected to filter any
particle size and have sufficiently volume to have a predicable
long life. The filter medium could be made of different layers with
different filtering capabilities. The bearing inside the rotor
cavity should be capable of running in either oil or water and made
from a suitable material such as tungsten carbide.
[0047] Referring to FIGS. 8 and 9, the flow outlet from the
pressuring pump 112 exits from below the flow outlet protector 107
via a narrower channel 130, and also exits via port 131 into a
centre bore of the pump drive shaft 132. At the coupling 133 there
are o-rings 134 and 135 which seal on respective shafts 136 and
137, so the pressurised filtered fluid is pumped into a centre bore
of the pump shaft 138. Some of the fluid exits the bore of pump
shaft 138 through a port 139. At pump bearings 141 a passage 140
allows filtered fluid to lubricate the pump bearing 141 before
passing into the discharge fluid. Several bearings 141 having such
passages 140 are distributed along the entire pump shaft length.
This feature ensures a long bearing life, and a long endurance of
the pump especially in a production fluid with sand other solid
particles.
[0048] This feature could also be used to supply clear fluids to
drilling assembly bearings, and other systems exposed to abrasive
fluids.
[0049] Referring to FIGS. 10 to 12, there is shown a back flushing
mechanism 220. Referring particularly to FIG. 12, on the main shaft
100 a cam 200 reciprocates a piston 201 in a piston bore 202, clean
fluid is fed into the piston bore 202 via passage 203, on each
stroke of the piston 201 a small volume of fluid is displaced past
the check valve 204 into the chamber 205. The annular piston 206 is
displaced downwards against spring 207. A rod 208 attached to the
piston unseats a valve 209 so that the collet fingers 216 and
pushed out of recess 217 which allows the fluid accumulated in the
chamber 210 to back flush the filter via passage 211 and check
valve 212. After the spring 207 displaces the piston fully back to
the wall 213, it resets the valve 209. The check valve 212, is
returned to non-active position by spring member 214, fluid can the
pass by the valve 212 into passage 215 to be circulated where
required. The charging operation of the back flush mechanism is
then repeated. Typical cycle time for the back flush mechanism will
be 6-12 hours so the filter will have regular back flushes. This
could be changed depending upon the fluid type being filtered.
[0050] In general, any suitable type of pump may be used in
conjunction with this cleaned fluid arrangement; the rotor shaft
may include an additional pumping means, even a simple feature
formed on the rotor shaft which tends to induce a fluid flow.
* * * * *