Note: Descriptions are shown in the official language in which they were submitted.
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PROTECTOR FOR ELECTRICAL SUBMERSIBLE PUMPS
This is a divisional of Application Serial
No. 2,389,419, filed June 6, 2002.
FIELD OF THE INVENTION
The present invention relates generally to motor
protectors for protecting submersible motors, such as those
used in raising fluids from petroleum wells. More
particularly, the present invention relates to a motor
protection system and method comprising one or both of a
protected bellows assembly and a three-dimensional labyrinth
assembly.
BACKGROUND OF THE INVENTION
A variety of production fluids are pumped from
subterranean environments. Different types of submersible
pumping systems may be disposed in production fluid deposits
at subterranean locations to pump the desired fluids to the
surface of the earth.
For example, in producing petroleum and other
useful fluids from production wells, it is generally known
to
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provide a submersible pumping system for raising the fluids
collected in a well. Production fluids, e.g. petroleum,
enter a wellbore drilled adjacent a production formation.
Fluids contained in the formation collect in the wellbore
and are raised by the submersible pumping system to a
collection point at or above the surface of the earth.
A typical submersible pumping system comprises several
components, such as a submersible electric motor that
supplies energy to a submersible pump. The system further
may comprise a variety of additional components, such as a
connector used to connect the submersible pumping system to
a deployment system. Conventional deployment systems
include production tubing, cable and coiled tubing.
Additionally, power is supplied to the submersible electric
motor via a power cable that runs through or along the
deployment system.
Often, the subterranean environment (specifically the
well fluid) and fluids that are injected from the surface
into the wellbore (such as acid treatments) contain
corrosive compounds that may include C02, H2S and brine
water. These corrosive agents can be detrimental to
components of the submersible pumping system, particularly
to internal electric motor components, such as copper
windings and bronze bearings. Moreover, irrespective of
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whether or not the fluid is corrosive, if the fluid enters
the motor and mixes with the motor oil, the fluid can
degrade the dielectric properties of the motor oil and the
insulating materials of the motor components. Accordingly,
it is highly desirable to keep these external fluids out of
the internal motor fluid and components of the motor.
Submersible electric motors are difficult to protect
from corrosive agents and external fluids because of their
design requirements that allow use in the subterranean
environment. A typical submersible motor is internally
filled with a fluid, such as a dielectric oil, that
facilitates cooling and lubrication of the motor during
operation. As the motor operates, however, heat is
generated, which, in turn, heats the internal motor fluid
causing expansion of the oil. Conversely, the motor cools
and the motor fluid contracts when the submersible pumping
system is not being used.
In many applications, submersible electric motors are
subject to considerable temperature variations due to the
subterranean environment, injected fluids, and other
internal and external factors. These temperature variations
may cause undesirable fluid expansion and contraction and
damage to the motor components. For example, the high
temperatures common to subterranean environments may cause
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the motor fluid to expand excessively and cause leakage and
other mechanical damage to the motor components. These high
temperatures also may destroy or weaken the seals,
insulating materials, and other components of the
submersible pumping system. Similarly, undesirable fluid
expansion and motor damage can also result from the
injection of high-temperature fluids, such as steam, into
the submersible pumping system.
Accordingly, this type of submersible motor benefits
from a motor fluid expansion system able to accommodate the
expanding and contracting motor fluid. The internal
pressure of the motor must be allowed to equalize or at
least substantially equalize with the surrounding pressure
found within the wellbore. As a result, it becomes
difficult to prevent the ingress of external fluids into the
motor fluid and internal motor components.
Numerous types of motor protectors have been designed
and used in isolating submersible motors while permitting
expansion and contraction of the internal motor fluid. A
variety of elastomeric bladders alone or in combination with
labyrinth sections have been used as a barrier between the
well fluid and the motor fluid. For example, expandable
elastomeric bags or bladders have been used in series to
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prevent mixing of wellbore fluid with motor fluid while
permitting expansion and contraction of the motor fluid.
In this latter design, the motor protector includes a
pair of chambers each of which have an elastomeric bladder.
The first bladder is disposed in a first chamber of the pair
of chambers and includes an interior in fluid communication
with the motor. This fluid communication permits motor oil
to flow from the motor into the elastomeric bladder during
expansion and to flow from the elastomeric bladder back to
the motor during contraction.
The second chamber also has an expandable bladder,
filled with motor oil, which is in fluid communication with
the first chamber but external to the first elastomeric
bladder. The second chamber is vented or open to the
wellbore environment. This assembly permits fluid to flow
between the second elastomeric bladder and the adjacent
chamber as the first elastomeric bladder expands or
contracts. Simultaneously, wellbore fluid is allowed to
flow in and out of the second chamber, external to the
second elastomeric bladder, to permit equalization of
pressure as the second bladder expands and contracts.
This type of expansion chamber works well in many
environments, but certain of the corrosive agents found in
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at least some wellbore environments comprise corrosive gases
that permeate the elastomeric bags or bladders. These
corrosive agents eventually can work their way into the
motor oil within the first elastomeric bladder and
ultimately corrode and damage internal components of the
electric motor. The wellbore environment also may have an
undesirable temperature (e.g., hot), which may destroy the
elastomeric bag or bladder and the shaft seal materials
throughout the submersible pumping system.
The conventional labyrinth type protector uses the
difference in specific gravity of the well fluid and the
motor fluid to separate the fluids. For example, a typical
labyrinth may embody a chamber having a first passageway to
the motor fluid and a second passageway to an undesirable
fluid, such as fluids in the wellbore. The first and second
passageways are generally oriented on opposite sides of the
chamber to maintain fluid separation in a vertical
orientation. Accordingly, conventional labyrinth type
protectors are generally less effective, or totally useless,
in orientations deviated from the vertical orientation.
Accordingly, the need exists for improved motor
protectors, which are operable in variable temperature
applications and multiple orientations. For example, it
would be advantageous to position a bellows assembly between
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a motor fluid and an external fluid and positively
pressurize the motor fluid relative to the external fluid to
prevent inward leakage of the external fluid into the motor.
It also would be advantageous to provide a relatively
balanced bellows assembly having one or both ends fixed,
rather than using sliding seals. Moreover, it would be
advantageous to provide a multi-orientable labyrinth having
conduits extending in multiple orientations to maintain
fluid paths having peaks and valleys in all potential
orientations.
SUMMARY OF THE INVENTION
The present invention features a system and method for
protecting a motor for a submersible pumping system. A
variety of motor protectors are provided for application in
variable temperature environments and multiple wellbore
orientations. For example, the motor protectors may include
one or more of a positively pressurized bellows, a
relatively balanced pressure bellows free of sliding seals,
and a multi-orientable labyrinth. Each of these motor
protectors also may have various moisture absorbents,
filters, particle shedders and various conventional motor
protector components.
The positively pressurized bellows is provided to
pressurize the motor fluid relative to external fluids for
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repelling the external fluids rather than allowing inward
leakage contaminating the motor fluid. The foregoing
bellows positively pressurizes the motor fluid by placing
the bellows between the motor fluid and the external fluid
and by using the pressure of the external fluid and the
spring force of the bellows assembly to provide a relatively
higher internal pressure of the motor fluid.
The balanced pressure bellows operates without any
sliding seals. Instead, the foregoing bellows couples to
the submersible pumping system at one or both ends. For
example, the balanced pressure bellows may be disposed
between a pump and the motor of the submersible pumping
system. Although it is referred to as a balanced pressure
bellows, it is understood that the foregoing bellows also
may provide a pressure differential between fluids.
The multi-orientable labyrinth is operable in a variety
of wellbore orientations, including vertical, horizontal,
and angled orientations. The multi-orientable labyrinth has
one or more conduits that wind and zigzag in multiple
orientations to ensure peaks and valleys in all orientations
of the labyrinth.
The foregoing motor protectors may be used to protect
motors and other components in any combination. As noted
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above, conventional motor protectors also may be used in
combination with the foregoing motor protectors. The
filters, moisture absorbents, and particle shedders provide
further protection to the motors and to the motor
protectors. In some applications, one or more of the
foregoing motor protectors and devices may be used in series
or in parallel.
According to one aspect of the present invention,
there is provided a motor protector for a submersible
pumping system, comprising: a housing; a motor for driving
a pump accommodated by said housing; an internal motor fluid
accommodated in said motor; a bellows assembly having a
pressurizing region for pressurizing the internal motor
fluid relative to an external fluid; a fluid absorbing
assembly positioned between the bellows assembly and the
motor; and wherein the internal motor fluid is in fluid
communication through the fluid absorbing assembly with the
pressurizing region of said bellows assembly, said fluid
absorbing assembly preventing undesirable contaminants from
entering the motor and contaminating the internal motor
fluid therein.
According to another aspect of the present
invention, there is provided a motor protector for a
submersible pumping system, comprising: a housing; a motor
for driving a pump accommodated by said housing; an internal
motor fluid accommodated in said motor; a bellows assembly
having an accordion-like enclosure forming a pressurizing
region for pressurizing the internal motor fluid relative to
an external fluid and forming a movable fluid separation
interface configured for isolating the internal motor fluid
of the motor, said bellows assembly having an attachment
structure connecting to said housing; a fluid absorbent
assembly positioned between the bellows assembly and the
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motor; and wherein the internal motor fluid is in fluid
communication through the fluid absorbing assembly with the
pressurizing region of said bellows assembly, said fluid
absorbing assembly preventing undesirable contaminants from
entering the motor and contaminating the internal motor
fluid therein.
According to still another aspect of the present
invention, there is provided a submersible pumping system
comprising: a motor having an internal motor fluid; a pump
operatively coupled to the motor; a motor protection
assembly coupled to the motor comprising: a bellows
assembly configured for separating the internal motor fluid
from an external fluid and for pressurizing the internal
fluid to a pressure higher than that of the external fluid;
a fluid absorbent assembly configured for isolating an
undesirable fluid from the internal fluid while allowing
fluid communication between the motor and bellows assembly;
and a particulate filter assembly disposed to filter
particulates proximate the bellows assembly.
According to yet another aspect of the present
invention, there is provided a method for protecting a motor
fluid of a motor from undesirable fluids external to the
motor, comprising: separating the motor fluid from an
external fluid via a bellows assembly; pressurizing the
motor fluid relative to the external fluid; and providing an
absorbing assembly between the motor and bellows assembly
for isolating undesirable elements from the motor fluid in
said motor while allowing fluid communication between the
motor fluid in said motor and said bellows.
According to a further aspect of the present
invention, there is provided a system for protecting a motor
from undesirable fluids external to the motor, comprising:
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a bellows having means for separating a motor fluid of said
motor from an external fluid and having means for
pressurizing the motor fluid to a relatively higher pressure
than the external fluid; fluid filtering means disposed to
filter particulates proximate the bellows; and fluid
absorbing means positioned between the bellows and the motor
for absorbing undesirable fluids in the motor fluid, said
motor fluid being in communication with said motor and said
pressurizing means of said bellows.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will hereafter be described with
reference to the accompanying drawings, wherein like
reference numerals denote like elements, and:
Figure 1 is a front elevational view of an
exemplary pumping system disposed within a wellbore;
Figure 2 is a diagrammatical cross-section of the
pumping system having a bellows assembly to separate well
fluid from motor fluid, which is positively pressurized
within the motor housing;
Figure 3 is a front elevational view of an
exemplary configuration of the pumping system having a seal
section and bellows section disposed about the submersible
motor;
Figure 4 is a cross-sectional view of the seal
section;
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Figures 5A and 5B are cross-sectional views of the
bellows section;
Figure 6 is a diagrammatical cross-section of an
alternate embodiment of the pumping system having multiple
motor protection assemblies disposed about the submersible
motor;
Figures 7 and 8 are front elevational views of
alternate configurations of the pumping system;
Figure 9 is a diagrammatical cross-section of the
pumping system having a bellows assembly with a spring
assembly;
Figure 10 is a diagrammatical cross-section of the
pumping system having a bellows assembly and a hard bearing;
Figures 11 and 12 are cross-sectional views of
alternate embodiments of a bellows section;
Figure 13 is a diagrammatical cross-section of the
pumping system having a multi-orientable labyrinth assembly;
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Figure 14 is a perspective view of the multi-orientable
labyrinth assembly, which is configured for disposal
adjacent the bellows assembly such as illustrated in Figures
2 and 8;
Figure 15 is a perspective view of an alternate
embodiment of the multi-orientable labyrinth assembly, which
has a ring-shape configured to dispose the labyrinth
assembly about the shaft as illustrated in Figure 13;
Figures 16A and 16B are cross-sectional views of the
pumping system illustrating an alternate embodiment having
both the bellows assembly and the multi-orientable labyrinth
assembly; and
Figure 17 is a cross-sectional view of an alternate
bellows section having multiple bellows assemblies.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring generally to Figure 1, an exemplary pumping
system 10, such as a submersible pumping system, is
illustrated. Pumping system 10 may comprise a variety of
components depending on the particular application or
environment in which it is used. Typically, system 10 has
at least a submersible pump 12, a motor 14 and a motor
protector 16. Motor 14 may comprise any electric motor or
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other motor that requires volume compensation based on, for
instance, the thermal expansion and/or contraction of
internal fluid. The submersible pump 12 may be of a variety
of types, e.g. a centrifugal pump, an axial flow pump, or a
mixture thereof. The system 10 may also comprise a gearbox,
as is known in the art.
In the illustrated example, pumping system 10 is
designed for deployment in a well 18 within a geological
formation 20 containing desirable production fluids, such as
petroleum. In a typical application, a wellbore 22 is
drilled and lined with a wellbore casing 24. Wellbore
casing 24 typically has a plurality of openings 26, e.g.
perforations, through which production fluids may flow into
wellbore 22.
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 may comprise
tubing 30 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 centrifugal pump 12, which draws
production fluid in through a pump intake 36 and pumps the
production fluid to the surface via tubing 30.
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It should be noted that the illustrated submersible
pumping system 10 is merely an exemplary embodiment. Other
components can be added to the 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
welibore casing 24. In any of these configurations of
submersible pumping system 10, it is desirable to attain
maximum protection and life of the motor fluid, the motor 14
and the motor protector 16 in accordance with the present
invention.
In the present invention, the system 10 may have
multiple sections of the motor protector 16 disposed about
the motor 14. A diagrammatical cross-sectional view of an
exemplary embodiment of the system 10 is provided in Figure
2. As illustrated, the system 10 comprises the pump 12,
motor 14, and various motor protection components disposed
in a housing 38. The pump 12 is rotatably coupled to the
motor 14 via a shaft 40, which extends lengthwise through
the housing 38 (e.g., one or more housing sections coupled
together). The system 10 and the shaft 40 may have multiple
sections, which can be intercoupled via couplings and
flanges. For example, the shaft 40 has couplings 42 and 44
and an intermediate shaft section 46 disposed between the
pump 12 and the motor 14. Various sections and
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configurations are illustrated in detail below, with
reference to Figures 2-3, 6-13, 16 and 17.
A variety of seals, filters, absorbent assemblies and
other protection elements also may be disposed in the
housing 38 to protect the motor 14. A thrust bearing 48 is
disposed about the shaft 40 to accommodate and support the
thrust load from the pump 12. A plurality of shaft seals,
such as shaft seals 50 and 52, are also disposed about the
shaft 40 between the pump 12 and the motor 14 to isolate a
motor fluid 54 in the motor 14 from external fluids, such as
well fluids and particulates. The shaft seals 50 and 52
also may include stationary and rotational components, which
may be disposed about the shaft 40 in a variety of
configurations. The system 10 also has a plurality of
moisture absorbent assemblies, such as moisture absorbent
assemblies 56, 58, and 60, disposed throughout the housing
38 between the pump 12 and the motor 14. These moisture
absorbent assemblies 56-60 absorb and isolate undesirable
fluids (e.g., water, H2S, etc.) that have entered or may
enter the housing 38 through the shaft seals 50 and 52 or
though other locations. For example, the moisture absorbent
assemblies 56 and 58 are disposed about the shaft 40 at a
location between the pump 12 and the motor 14, while the
moisture absorbent assembly 60 is disposed on an opposite
side of the motor 14 adjacent a bellows assembly 64. In
_ _ _ i .<... . . ..~. .~.z ., ._,.r ...,
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addition, the actual protector section above the motor may
include a hard bearing 300 in protector head 302 with
shedder (see Figure 10). Figure 10 also shows bellows
housing 304 having equalizing ports 306 for bellows, and a
bellows chamber 308 which expands to maintain motor oil
pressure. Standard chambers (LSBPB etc.) with shaft seals
are generally designated at 310, and a pressure shaft seal
is shown at 312.
As illustrated in Figure 2, the motor fluid 54 is
in fluid communication with an interior 66 of the bellows
assembly 64, while well fluid 68 is in fluid communication
with an exterior 70 of the bellows assembly 64.
Accordingly, the bellows assembly 64 seals the motor fluid
54 from the well fluid 68, while positively pressurizing the
motor fluid 54 relative to the well fluid 68 (e.g., a 50 psi
pressure differential). The spring force, or resistance, of
the bellows assembly 64 ensures that the motor fluid 54
maintains a higher pressure than that of the well fluid 68.
A separate spring assembly or biasing structure (e.g., as
illustrated by Figure 9 generally) also may be incorporated
in bellows assembly 64 to add to the spring force, or
resistance, which ensures that the motor fluid 54 maintains
a higher pressure than that of the well fluid 68.
The bellows assembly 64 may embody a variety of
structural features, geometries and materials. For example,
the bellows assembly 64 may embody an enclosure having an
annular wall formed by a plurality of symmetrical wall
sections, such as ring-shaped wall sections, which are
foldingly collapsible and expandable with fluid pressure
variations in the system (e.g., an accordion-like
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enclosure). As illustrated by Figures 2, 5A-B, 6, 10 and
17, the bellows assembly 64 provides a direct separation
interface between the motor and well fluids 54 and 68 and
uses the pressure of the well fluid 68 in combination with a
spring force of the bellows assembly 64 to positively
pressurize the motor fluid 54.
The bellows assembly 64 also may be used for pressure
balancing or equalization between the motor and well fluids
54 and 68 or between the motor fluid 54 and another internal
fluid of the system 10, such as illustrated in Figures 11,
12 and 16B. In this pressure balancing embodiment of the
bellows assembly 64, the bellows assembly 64 may embody one
or more collapsible wall sections of varying cross-sections,
such as annular wall sections having different diameters.
As illustrated by Figures 11, 12 and 16B, the foregoing
annular wall sections may be disposed about a motor-to-pump
shaft between the pump 12 and the motor 14 for internal
pressure balancing of the motor and well fluids 54 and 68.
However, it is understood that these bellows assemblies 64
also may provide some positive pressurization (e.g., 5 psi)
of the motor fluid 54 relative to the well fluid 68. As
illustrated in Figure 11, the bellows assembly 64 may have
concentric collapsible walls, which form a hollow ring-
shaped enclosure. As illustrated in Figure 12, the
foregoing collapsible walls of the bellows assembly 64 may
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be disposed in a stepped configuration, which has a disk-
shaped wall coupling adjacent collapsible walls. In any of
the foregoing structures and configurations, the bellows
assembly 64 may be coupled to the submersible pumping system
at one or both ends without a sliding seal.
In any of the foregoing positive pressurization or
pressure balancing configurations, the bellows assembly 64
may be constructed from suitable materials that are
resistant (e.g., impermeable) to the hot and corrosive
environment within the wellbore, such as Kalrez, Chemrez, or
Inconel 625. Accordingly, the bellows assembly 64 provides
a relatively strong fluid separation between the motor and
well fluids (or other internal fluid of the system 10) to
prevent leakage into the motor 14, to prevent undesirable
contamination and corrosion of the motor 14, and to prolong
life of the motor 14 and the overall system 10.
Initially, the motor fluid 54 is injected into the
motor 14 and the bellows assembly 64 is pressurized until a
desired positive pressure is obtained within the motor 14.
For example, the system 10 may set an initial pressure, such
as 25-100 psi, prior to submerging the system 10 into the
well. The exterior chamber 70 adjacent the bellows assembly
64 also may be filled with fluid prior to submerging the
system into the well. The well fluid 68 enters the housing
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38 through ports 72 and mixes with this fluid in exterior
chamber 70 as the system 10 is submersed into the well.
Referring now to the operation of the bellows assembly
64 illustrated by Figure 2, the motor fluid 54 expands and
contracts as the motor 14 is activated and deactivated and
as other temperature fluctuations affect the fluid volume.
If the motor fluid 54 expands, then the bellows assembly 64
expands accordingly. If the motor fluid 54 contracts, then
the bellows assembly 64 also contracts. The spring force of
the bellows assembly 64 ensures that the motor fluid 54 is
positively pressurized relative to the well fluid 68,
regardless of whether the motor fluid 54 has expanded or
contracted (e.g., 10 psi, 25 psi, 50 psi or higher pressure
differential).
During or after submerging the system 10, the system 10
may release or inject oil in the motor to maintain the
pressure of the motor fluid 54 within a certain pressure
range. Accordingly, as illustrated by the bellows
configuration of Figures 2, 5A-B, 6, 10 and 17, the external
fluids (i.e., the well fluid 68) are continuously pressured
away from the internal fluids (i.e., the motor fluid 54) of
the motor 14 to prevent undesirable corruption of the
internal fluids and components of the motor 14. The
foregoing pressure ensures that if leakage occurs, the
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leakage is directed outwardly from the motor fluid 54 to the
well fluid 68, rather than inwardly from the well fluid 68
into the motor fluid 54 (i.e., the typical undesirable
leakage/corruption of the motor fluid 54). The positive
internal pressure generally provides a better environment
for the system 10. The positive pressure of the motor fluid
54 provided by the bellows assembly 64 also may be used to
periodically flush fluids through the bearings and seals to
ensure that the bearings and seals are clean and operable.
Throughout the life of the system 10, motor fluid 54
tends to leak outwardly through the shaft seals (such as
shaft seals 50 and 52) and into the external fluids. By
itself, this gradual leakage tends to decrease the pressure
of the motor fluid 54. However, the bellows assembly 64
compensates for the leakage to maintain a certain positive
pressure range within motor fluid 54. In the embodiment
shown in Figure 2, the bellows assembly 64 compensates by
contracting (due to the spring force). In the embodiment
shown in Figures 5A-5B (described below), the bellows
assembly 64 compensates by expanding (also due to the spring
force).
The bellows assembly 64 also may have various
protection elements to extend its life and to ensure
continuous protection of the motor 14. For example, a
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filter 74 may be disposed between the ports 72 and the
exterior 70 of the bellows assembly 64 to filter out
undesirable fluid elements and particulates in the well
fluid 68 prior to fluid communication with the exterior 70.
A filter 76 also may be provided adjacent the interior 66 of
the bellow assembly 64 to filter out motor shavings and
particulates. As illustrated, the filter 76 is positioned
adjacent the moisture absorbent assembly 60 between the
motor cavity 62 and the interior 66 of the bellows assembly
64. Accordingly, the filter 76 prevents solids from
entering or otherwise interfering with the bellows assembly
64, thereby ensuring that the bellows assembly 64 is able to
expand and contract along with volume variations in the
fluids.
A plurality of expansion and contraction stops also may
be disposed about the bellows assembly 64 to prevent over
and under extension and to prolong the life of the bellows
assembly 64. For example, a contraction stop 78 may be
disposed within the interior 66 of the bellows assembly 64
to contact an end section 80 and limit contraction of the
bellows assembly 64. An expansion stop 82 also may be
provided at the exterior 70 of the bellows assembly 64 to
contact the end section 80 and limit expansion of the
bellows assembly. These contraction and expansion stops 78
and 82 can have various configurations depending on the
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material utilized for the bellows assembly 64 and also
depending on the pressures of the motor fluid 54 and the
well fluid 68. A housing 84 also may be disposed about the
exterior 70 to guide the bellows assembly 64 during
contraction and expansion and to provide overall protection
about the exterior 70.
As discussed above, the motor fluid 54 may be
pressurized significantly prior to submersing the system 10.
As the system 10 is submersed and activated in the downhole
environment, the internal pressure of the motor fluid 54 may
rise and/or fall due to temperature changes, such as those
provided by the activation and deactivation of the motor 14.
Accordingly, various valves may be disposed within the
housing 38 to control the pressurization of the motor fluid
54 and to maintain a suitable positive pressure range for
the motor fluid 54. For example, a valve 86 may be provided
to release motor fluid 54 when the pressurization exceeds a
maximum pressure threshold. In addition, another valve may
be provided to input additional motor fluid when the
pressurization falls below a minimum pressure threshold.
Accordingly, the valves maintain the desired pressurization
and undesirable fluid elements are repelled from the motor
cavity 62 at the shaft seals 50 and 52.
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The system 10 also may have a wiring assembly 87
extending through the housing 38 to a component adjacent the
bellows assembly 64. For example, a variety of monitoring
components may be disposed below the bellows assembly 64 to
improve the overall operation of the system 10. Exemplary
monitoring components comprise temperature gauges, pressure
gauges, and various other instruments, as should be
appreciated by those skilled in the art.
As discussed above, the system 10 may have various
configurations of the bellows assembly 64 and motor
protection components for the motor 14. Figure 3 is a front
elevational view of an exemplary configuration of the system
10, wherein the motor protector 16 comprises a seal section
88 and a bellows section 90. As illustrated, the seal
section 88 is disposed between the pump 12 and the motor 14,
while the bellows section 90 is disposed adjacent the motor
14 on an opposite side of the seal section 88. The system
10 also has an optional monitoring system 92 disposed
adjacent the bellows section 90. If additional sealing and
motor protection is desired in the system 10, then a
plurality of the seal and bellows sections 88 and 90 can be
disposed about the motor 14 in desired locations. For
example, the system 10 may have multiple bellows sections 90
disposed sequentially and/or on opposite sides of the motor
14 (see Figure 17, which illustrates a bellows section 90
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having two bellows assemblies 64 in series). Exemplary
embodiments of the seal and bellows sections 88 and 90 are
illustrated in Figures 4 and 5A-B, respectively.
As illustrated in Figure 4, the seal section 88 of the
motor protector 16 has various seal and protection elements
disposed about the shaft 40 within a housing 94. These
elements are provided to protect the motor 14 from
undesirable fluid elements in the adjacent pump 12 and
wellbore. Accordingly, the seal section 88 has a plurality
of shaft seals, such as shaft seals 96, 98 and 100, disposed
about the shaft 40 to seal and isolate the motor fluid 54
from the undesirable fluids (e.g., the well fluid 68). The
seal section 88 also has the thrust bearing 48 disposed
about the shaft 40 to accommodate and support the thrust
load from the pump 12. A moisture absorbent assembly 102
also may be disposed about the shaft 40 to remove the
undesirable fluids from the internal fluid (i.e., the motor
fluid 54 within the housing 94).
As discussed above, the internal fluid of the system 10
is positively pressurized to prevent in-flow of the
undesirable fluids through the shaft seals 96, 98, and 100.
In a section 106 between the shaft seals 98 and 100, a
relief valve 104 is provided to release internal fluid from
the system 10 when the internal pressure exceeds the maximum
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pressure threshold. Accordingly, the present technique
maintains the internal fluid within a certain positively
pressurized pressure range to prevent in-flow of undesirable
fluids through the shaft seals 96, 98, and 100, while also
allowing a pressure release when the internal pressure
exceeds the maximum pressure threshold. This technique
ensures that fluid is pressurably repelled and ejected
rather than allowing the undesirable fluids to slowly
migrate into the system 10, such as in a pressure balanced
system. However, the present invention also may utilize
various pressure balancing assemblies to complement the seal
and bellows sections 88 and 90, as discussed below with
reference to Figures 6 and 13-16. For example, the seal
section 88 may include a labyrinth or bag assembly between
the shaft seals 96, 98 and 100 (see Figure 6, which
illustrates bag assembly 124 between shaft seals 116 and
118).
As illustrated in Figures 5A and 5B, the bellows
section 90 of the motor protector 16 has the bellows
assembly 64 disposed in a housing 106, which may be coupled
to the motor 14 at a coupling section 108 and to another
component at a coupling section 110. Inside the housing
106, the bellows assembly 64 is oriented such that the
interior 66 is in fluid communication with the well fluid 68
through the ports 72. An external filter assembly 112 is
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disposed about the ports 72 to filter out undesirable
elements within the well fluid 68. The exterior 70 of the
bellows assembly 64 is in fluid communication with the motor
fluid 54. The bellows assembly 64 also has a filter
disposed between the bellows assembly 64 and the motor 14.
For example, a filter assembly 114 may be disposed at the
expansion stop 82 of the housing 84 to filter out motor
shavings and other harmful elements. Accordingly, the
filter assemblies 112 and 114 filter out undesirable
elements from the motor fluid 54 and the well fluid 68 to
protect the bellows assembly 64. In this configuration, the
motor fluid 54 contracts the bellows assembly 64 as it is
injected into the motor 14, while the well fluid 68 acts
against the bellows assembly 64 as the system is submersed
into the well.
As discussed above, the bellows assembly 64 is movably
disposed within the housing 84 between the expansion stop 82
and the contraction stop 78. As the motor fluid 54 expands
and contracts due to temperature changes, the bellows
assembly 64 contracts or expands to a new resting position,
where the internal motor pressure is balanced against the
well pressure plus the spring force of the bellows. If the
motor fluid 54 expands, the bellows of this embodiment
contracts accordingly. If the motor fluid 54 contracts, the
bellows of this embodiment expands accordingly. The motor
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fluid 54 in this embodiment, therefore, remains positively
pressurized in relation to the well fluids 68, regardless of
whether or not it has been expanded or contracted due to
temperature variations.
The bellows assembly 64 also may utilize various spring
assemblies and other biasing structures to facilitate
pressurization of the motor fluid 54. For example, as shown
in Figure 9, a spring assembly 300 may be incorporated into
the bellows assembly 64 to complement the resistance of the
bellows assembly 64 and to increase the stroke of bellows
assembly 64 (thereby increasing the time and range in which
the bellows assembly 64 will maintain a positive pressure on-
motor fluid 54). As illustrated by the contrasting
orientations of the bellows assembly 64 in Figures 2 and 5A-
B, the orientation of the bellows assembly also can be
varied to accommodate a particular pumping system and
application.
Moreover, as discussed in further detail below, the
motor protector devices of the present technique may be used
alone or separate, in duplicate, in series, in parallel, or
in any suitable configuration to provide optimal protection
for the motor 14. For example, as illustrated in Figure 17,
a plurality of bellows assemblies 64 may be disposed in
series within the bellows section 90 of the system. In the
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embodiment of Figure 17, the bellows section 90 comprises
two of the motor protector structures illustrated by Figures
5A-5B. The bellows assemblies 64 are arranged
longitudinally adjacent one another in the bellows section
90, each bellows assembly 64 having a longitudinally
adjacent set of ports 72 and filters 112 for fluid
communication with the well fluid 68. The opposite side of
each bellows assembly 64 is in fluid communication with the
motor fluid 54. The upper bellows assembly 64 is in direct
fluid communication with the motor fluid 54 via the coupling
108. The lower bellows assembly 64 is in fluid
communication with the motor fluid 54 through a conduit 115,
which also may provide passage for the wiring assembly 87.
Accordingly, the motor fluid 54 is positively pressurized
relative to the well fluid 68 by the spring-force and well
pressure exerted on both of the bellows assemblies 64. If
additional internal pressure is needed to protect the motor
fluid 54, then additional bellows assemblies 64 can be
incorporated into the bellows section 90.
The system 10 also may comprise a variety of
conventional motor protector components, such as a bag
assembly and a labyrinth assembly. Figure 6 is a
diagrammatical cross-section of an alternate embodiment of
the pumping system having such conventional motor protector
elements. As illustrated, the system 10 has the pump 12,
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the seal section 88, the motor 14 and the bellows section 90
sequentially intercoupled.
The bellows section 90 has the bellows assembly 64
oriented such that the interior 66 is in fluid communication
with the well fluid 68, while the exterior 70 is in fluid
communication with the motor fluid 54. Although Figure 6
does not illustrate the various filters and other protection
elements for the bellows assembly 64, the bellows section 90
may include a variety of filters, seals, moisture absorbent
assemblies, housings, bellow stops, and other desired
bellows protection elements configured to prolong the life
of the bellows assembly 64, as previously described.
The seal section 88 has shaft seals 116 and 118
disposed about chambers 120 and 122, which have a bag
assembly 124 and a labyrinth assembly 126 disposed therein
to provide pressure balancing between the shaft seals 116
and 118. The seal section 88 also may utilize a variety of
other pressure balancing components, such as conventional
bag assemblies, conventional labyrinth assemblies, and
various bellows and labyrinth assemblies of the present
technique. A plurality of pressure check valves, such as
valves 128 and 130, are also disposed in the seal section 88
to control the positively pressurized fluid within the
system 10. For example, the valve 128 is configured to
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monitor the pressure and to trigger a backup oil supply when
the pressure falls below the minimum pressure threshold in
the motor 14 (e.g., 5 psi). For example, if the bellows
section 90 fails to expand or contracted as in normal
operation, then the valve 128 acts as a backup to ensure a
desired pressure range for the motor fluid 54. The valve
130 is configured to monitor the pressure and to release the
positively pressurized motor fluid 54 within the motor 14
when the internal pressure exceeds the maximum pressure
threshold. Accordingly, the valve 130 ensures that the O-
ring seals in the pothead, the joints, and various other
components in the seal section 88 are protected from
excessive pressure differentials.
Figures 7 and 8 illustrate alternate configurations of
the seal and bellow sections of the motor protector 16 of
the system 10. As illustrated in Figure 7, one embodiment
of the system 10 has the seal section 88 and the bellows
section 90 sequentially disposed between the pump 12 and the
motor 14. The system 10 also has the optional monitoring
system 92 disposed adjacent the motor 14 and opposite the
bellows section 90. As illustrated in Figure 8, the
exemplary embodiment of system 10 also has the seal section
88 and the bellows section 90 sequentially disposed between
the pump 12 and the motor 14. However, an additional
bellows section 131 is disposed below the motor 14 to
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complement the bellows section 90 disposed above the motor
14. The system 10 also has the optional monitoring system
92 disposed below the relatively lower bellows section 131.
Accordingly, the seal and bellows sections 88, 90 and 131
may be oriented at various locations relative to the pump 12
and the motor 14, while also including a plurality of such
sections 88, 90 and 131 to improve the effectiveness of the
overall motor protection technique. It also should be noted
that the seal sections 88 illustrated in Figures 7 and 8 may
include conventional motor protection components, such as
those illustrated in Figure 6.
It is expected that the bellows section, as discussed
above and illustrated in Figures 5A-5B, may be reused in the
system 10 with minimal repair costs. There is no shaft
below the motor, so mechanical wear should be at a minimum,
and the metal bellows will operate well down the stress
strain curve, which should reduce fatigue and loss of spring
constant force.
The system 10 also may have a variety of alternate
configurations of the bellows assembly 64 for positioning
the bellows about the shaft 40, as illustrated in Figures 11
and 12. For example, the bellows assembly 64 may embody an
annular or ring-shaped enclosure, which may be fixed at one
or both ends to provide a fixed seal and an
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expandable/contractible volume. Accordingly, the bellows
assembly 64 avoids use of sliding seals, which typically
cause leakage into the motor fluid. In this embodiment, the
fluid pressures on opposite sides of the bellows assembly 64
may be relatively balanced rather than providing a
significant pressure differential between the fluids.
However, it is understood that a slight pressure
differential, such as 5 psi, may be provided in this
pressure-balanced configuration of the bellows assembly 64.
As illustrated in Figures 11 and 12, the bellows
section 90 has the bellows assembly 64 disposed in a housing
132, which may be coupled to the motor 14 at one of sections
134 and 136. For example, in these exemplary embodiments,
the motor 14 is coupled to section 134, while the pump 12 or
another protector component (e.g., a bellows assembly, a bag
assembly, a labyrinth assembly, etc.) is coupled to the
section 136.
Inside the housing 132, the bellows assembly 64 is
oriented such that the interior 66 is in fluid communication
with the well fluid 68 through the port 138. Alternatively,
if a labyrinth assembly, such as illustrated in Figures 13-
16, is coupled to the section 136, then the interior 66 may
be in fluid communication with a desired isolation fluid
configured to facilitate separation from the well fluid 68
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in the labyrinth assembly. In either configuration, a
filter assembly 140 can be disposed adjacent the port 138 to
filter out undesirable elements within the well fluid 68 or
the desired isolation fluid.
The exterior 70 of the bellows assembly 64 is in fluid
communication with the motor fluid 54 via the ports 142 and
144. Alternatively, the exterior 70 may be in fluid
communication with a second isolation fluid for a second
labyrinth assembly, a bag assembly, or any other desired
fluid separation assembly. As described in detail above,
the bellows assembly 64 also can include a variety of
bellows protection elements, such as guides, seals, filters
and absorbent packs (e.g., moisture absorbent packs 146 and
148). The bellows section 90 also may comprise one or more
shaft seals, thrust bearings, and various other seals and
bearings. For example, the bellows section 90 may have
shaft seals 150 and 152 disposed about the shaft 40 on
opposite sides of the bellows assembly 64. A thrust bearing
154 is also disposed about the shaft 40 adjacent the section
134.
As discussed above, the bellows assemblies 64 of
Figures 11 and 12 are balanced pressure bellows rather than
a positively pressurized bellows, which is illustrated by
Figures 2, 5A-B, 6, and 9. In operation of the bellows
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assemblies illustrated by Figures 11 and 12, injection and
expansion of the motor fluid 54 in the motor 14 (or other
isolation fluid) and the exterior 70 causes the bellows
assembly 64 to contract. In contrast, the pressure of the
well fluid 68 (or other isolation fluid) causes the bellows
assembly to expand. As the motor fluid 54 expands and
contracts due to temperature changes, the bellows assembly
64 contracts or expands to a new resting position, where the
internal motor pressure is balanced against the well
pressure plus any resistance of the bellows. If the motor
fluid 54 (or other isolation fluid) expands, the bellows of
this embodiment contracts accordingly. If the motor fluid
54 (or other isolation fluid) contracts, the bellows of this
embodiment expands accordingly. Accordingly, bellows
assembly 64 substantially balances the pressures between the
motor fluid 54 and the well fluid 68 under a wide range of
operating conditions, which include both expansion and
contraction of the motor fluid 54. If a positive pressure
differential is desired in the bellows assemblies 64 of
Figures 11 and 12, then a spring assembly, such as
illustrated in Figure 9, can be incorporated into the
bellows assemblies 64 to prevent inward leakage of
undesirable elements such as the well fluid 68.
As noted above, the bellows assemblies 64 of Figures 11
and 12 may be fixed at one or both ends. The embodiment
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illustrated in Figure 11 has the bellows assembly 64 fixed
to a member 156 at an end 158, while an opposite end 160 is
free to expand and contract within the housing 132. As
illustrated, the bellows assembly 64 has a generally annular
or ring-shaped geometry, which has inner and outer wall
sections 162 and 164 extending along inner and outer walls
166 and 168 of the bellows section 90 from the member 156 to
an opposite wall section 170 at the end 160. Accordingly,
the opposite wall section 170 foldingly moves inwardly and
outwardly as the pressure changes between the motor and well
fluids 54 and 68. The bellows assembly 64 also may include
a stop, such as illustrated in Figures 5A and 5B, to prevent
over extension of the bellows assembly 64. The internal
components of the bellows section (e.g., component 172) also
may act as a stop for the bellows assembly 64. The
particular length and spring stiffness of the bellows
assembly 64 may be configured for any desired operating
conditions and well environments. Additional bellows
assemblies 64 also may be incorporated into the bellows
section 90 to provide additional protection for the motor
14.
As illustrated by Figure 12, the bellows assembly 64
also may have one or more stepped sections, such as stepped
section 174. The stepped section 174 provides a fluid
interface to facilitate expansion and contraction of the
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bellows assembly 64. In this exemplary embodiment, the
bellows assembly 64 is fixed at both ends to members 156 and
172, while the stepped section 174 is movable as the well
and motor fluids 54 and 68 expand and contract in the
interior 66 and exterior 70 of the bellows assembly 64,
respectively. The stepped section 174 acts as a fluid
interface between large diameter and small diameter bellows
sections 176 and 178, which are configured to move along the
outer and inner walls 168 and 166, respectively. The
particular lengths and spring stiffness of the bellows
sections 176 and 178 may be configured for any desired
operating conditions and well environments. Additional
bellows assemblies 64 also may be incorporated into the
bellows section 90 to provide additional protection for the
motor 14.
The system 10 also can include one or more labyrinth
assemblies, bag or bladder assemblies, or other conventional
motor protector assemblies to protect both the motor 14 and
the bellows assembly 64. Moreover, the system 10 can
comprise the positively pressured bellows assembly 64 shown
in Figure 2 (for example) along with the balanced pressure
bellows assembly 64 shown in Figures 11, 12, and 16B.
Additionally, as illustrated in Figures 13-16, the
motor protector 16 of the system 10 may comprise a multi-
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orientable labyrinth assembly 180 (i.e., operable in
multiple orientations), which may be used alone or in
combination with the bellows assembly 64 or other
components. As discussed in detail below, the multi-
orientable labyrinth assembly 180 has one or more conduits
that extend in multiple directions to ensure fluid paths
having peaks and valleys in multiple orientations of the
multi-orientable labyrinth assembly 180. Accordingly, the
peaks and valleys in these various orientations ensure
continuous fluid separation in all orientations of the
multi-orientable labyrinth assembly 180 based on differences
in specific gravity. In the embodiment illustrated in Figure
13, the system 10 has the multi-orientable labyrinth
assembly 180 disposed between the pump 12 and the motor 14.
As described in other embodiments of the system 10, a
variety of seals, couplings, bearings, filters, absorbents,
and protection devices may be provided to protect and
prolong the life of the motor 14. Accordingly, the system
10 may include couplings 182 and 184, a thrust bearing 186,
and a solids processor 188. The exemplary solids processor
188 is disposed in a chamber 189 between the pump 12 and the
motor protector 16 to prevent solids from entering the
multi-orientable labyrinth assembly 180 and from generally
corrupting the motor projection devices in the motor
protector 16. As illustrated, the solids processor 188
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includes a variety of solids separators, such as shedder 190
and shroud 194, which prevent solids from settling on and
damaging bearings and seals such as shaft seal 192. The
solids separator 190 throws or sheds solids outwardly from
the shaft 40 and shaft seal 192. The shroud 194, which may
embody an extended length shedder in a deviated orientation,
also prevents solids from settling near the shaft 40 and
damaging the shaft seal 192. The solids processor 188 also
includes one or more flow ports 196 that allow solids to
escape into the wellbore.
The multi-orientable labyrinth assembly 180 comprises a
multi-directional winding of tubing, which is fluidly
coupled to the motor and well fluids 54 and 68 (or other
isolation fluids) at ends 198 and 200, respectively. As
illustrated, the ends 198 and 200 are positioned in
respective opposite ends 202 and 204 of the motor protector
16. The end 198 is coupled to a port 206 extending to the
motor 14, while the end 200 is positioned openly within the
motor protector 16. The end 200 also includes a filter 208
to prevent solids and other undesirable elements from
entering the multi-orientable labyrinth assembly 180. The
well fluid 68 enters the motor protector 16 via conduit 210,
which extends from the chamber 189 to the end 202 of the
motor protector 202. The conduit 210 also can include one
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or more filters, such as filter 212, to prevent the inflow
of solids into the motor protector 16.
In operation, the multi-directional winding of the
multi-orientable labyrinth assembly 180 maintains fluid
separation of the motor and well fluids 54 and 68 by using
the differences in specific gravity of the fluids and multi-
directional windings. As illustrated in Figures 14 and 15,
the multi-orientable labyrinth assembly 180 has a plurality
of crisscrossing and zigzagging tubing paths, which extend
in multiple orientations (e.g., 2-D, 3-D, or any number of
directions) to ensure that the fluids go through upward and
downward movement regardless of the orientation of the
system 10. For example, the multi-orientable labyrinth
assembly 180 may be operable in a vertical wellbore, a
horizontal wellbore, or any angled wellbore. The multi-
orientable labyrinth assembly 180 also can be disposed in a
variety of submersible pumping systems 10, including those
illustrated in Figures 1-13 and 16. Moreover, a plurality
of the multi-orientable labyrinth assemblies 180 may be
disposed in series or in parallel in various locations
within the system 10.
In one system configuration, such as illustrated by
Figures 2, 5A-B, 6, 9 and 10, the embodiment illustrated in
Figure 14 may be disposed in a chamber between the bellows
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assembly 64 and the well fluid 68 to protect the bellows
assembly 64. In the foregoing system configuration, the
pump 12 and the motor 14 can be positioned side by side,
while the bellows assembly 64 and the multi-orientable
labyrinth assembly 180 are disposed adjacent the motor 14.
In contrast, the embodiment illustrated in Figure 15 is
configured for positioning about the shaft 40 in a central
protector configuration, such as illustrated by Figures 11-
13 and 16. In this central configuration, the multi-
orientable labyrinth assembly 180 has an annular or ring-
shaped geometry, which provides an inner conduit 214 for the
shaft 40. In both embodiments of Figures 14 and 15, the
multi-orientable labyrinth assembly 180 may include one or
more continuous tubes, which are interwoven in zigzagging
and multi-directional patterns terminating at opposite ends
of the labyrinth assembly 180. Moreover, the dimensions of
the tubing, the density of the windings, and other
geometrical features may be tailored to the specific system
10 and downhole environment.
The multi-orientable labyrinth assembly 180 also has an
additional feature, as compared to conventional two-
dimensional labyrinths. In two-dimensional labyrinths, the
oil/well fluid interface occurs within the labyrinth chamber
and not within one of the labyrinth tubes. In the multi-
orientable labyrinth assembly 180, the interface may occur
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in the relevant chamber, but it may also occur within the
multi-oriented tube 180 thereby enabling the assembly 180 to
be used in any orientation (as previously discussed).
In an exemplary embodiment of the system 10, a
plurality of the foregoing motor protector and seal devices
may be disposed in parallel or in series within the system
10. Figures 16A and 16B, which are broken along line 215-
215 for illustrative purposes, are cross-sectional views of
an exemplary embodiment of the motor protector 16 having a
plurality of motor protecting and sealing assemblies
disposed between the pump 12 and the motor 14. As
illustrated, the motor protector 16 includes a solids
processing section 216 adjacent the pump 12, a sand shield
or seal protection section 218 adjacent section 216, a
multi-orientable labyrinth section 220 adjacent section 218,
a bellows section 222 adjacent section 220, a conventional
labyrinth section 224 adjacent section 222, and a thrust
bearing section 226 adjacent section 224.
The solids processing section 216 can include a variety
of shrouds to shield the seals, and various shedders and
ports to shed and eject the solids into the wellbore, as
discussed above. For example, the section 216 includes
outer and inner shedders 228 and 230, respectively. The
sand shield section 216 may comprise a variety of filters
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and shields, such as shroud 232, which prevent sand and
other particulate matter from corrupting the system 10
(e.g., seal body 234).
The labyrinth section 220 comprises one or more of the
multi-orientable labyrinth assemblies 180, such as
illustrated in Figures 13 and 15, which may be coupled in
series or in parallel within the section 220. The labyrinth
section 220 also may comprise a conventional labyrinth or
elastomeric. bag assembly, such as illustrated in the
labyrinth section 224 (see also Figure 6, which illustrates
conventional bag and labyrinth assemblies 124 and 130,
respectively).
The bellows section 222 comprises one or more of the
above-described bellows assemblies 64, which will typically
be a balanced pressure bellows, but may also be a positively
pressurized bellows. In the exemplary embodiment of Figures
16A and 16B, the bellows assembly 64 is a balanced pressure
bellows, such as illustrated in Figures 11 and 12.
Accordingly, the bellows assembly 64 is fixed at one or both
ends of the bellows section 222.
The foregoing sections 218, 220, 222, 224 and 226 are
intercoupled and sealed via seal bodies 234, 242, 244 and
246, each of which comprises a shaft seal 236, a bearing
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238, and a conduit 240 for fluidly intercoupling the
adjacent sections. The seal bodies 234, 242, 244 and 246
also can include a variety of other seals, bearings and
conduits. The thrust bearing section 226 also comprises a
thrust bearing 248 and other desired seals, bearings and
conduit structures.
In addition to those components illustrated in Figures
16A and 16B, the system 10 may also comprise a positively
pressured bellows assembly 64 located below the motor 14, as
shown in Figures 2 and 6 for example.
Accordingly, the present invention may embody a variety
of system configurations and motor protectors 16 and
corresponding devices, such as the bellows assembly 64 and
the multi-orientable labyrinth assembly 180. As described
above, the bellows assembly 64 may embody either a
positively pressurized system or a balanced pressure system.
The foregoing motor protectors 16 and corresponding devices
may be used alone or together in any configuration,
including multiples of each device and conventional motor
protectors. Moreover, one or more of the motor protectors
16 can be disposed above, between or below the pump 12 and
the motor 14. For example, if a balanced pressure bellows
is disposed above the motor 14 or between the pump 12 and
the motor 14, then a positively pressurized bellows may be
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disposed below the motor 14 in fluid communication with the
well fluid. Moreover, any of the foregoing motor protectors
16 and corresponding devices may be functionally combined in
series or in parallel, or any combination thereof.
It will be understood that the foregoing description is
of preferred exemplary embodiments of this invention, and
that the invention is not limited to the specific forms
shown. These and other modifications may be made in the
design and arrangement of the elements without departing
from the scope of the invention as expressed in the appended
claims. For example, the bellows assembly may be replaced
or complemented by any suitable pressure inducing assembly,
such as a hydraulic piston assembly or a spring-assisted
piston assembly.
44
