U.S. patent application number 14/333090 was filed with the patent office on 2015-01-22 for labyrinth chamber with helical blade for a submersible well pump and method of use.
The applicant listed for this patent is Baker Hughes Incorporated. Invention is credited to Kevin R. Bierig, Steven W. Pyron.
Application Number | 20150023805 14/333090 |
Document ID | / |
Family ID | 52343706 |
Filed Date | 2015-01-22 |
United States Patent
Application |
20150023805 |
Kind Code |
A1 |
Pyron; Steven W. ; et
al. |
January 22, 2015 |
Labyrinth Chamber with Helical Blade for a Submersible Well Pump
and Method of Use
Abstract
An electrical submersible pump assembly has a pump, a motor and
a seal section with a labyrinth chamber. A guide tube surrounds a
drive shaft in the seal section and contains lubricant in fluid
communication with lubricant in the motor. The guide tube has a
guide tube port adjacent the downstream end of the labyrinth
chamber. A. labyrinth tube has an open inlet end in the downstream
end of the labyrinth chamber and an open outlet end near the
upstream end of the labyrinth chamber. The labyrinth communicates
well fluid on the exterior of the seal section into the labyrinth
chamber in contact with the lubricant in the labyrinth chamber. A
non rotating helical blade in the labyrinth chamber encircles the
guide tube, defining a helical flow path between the outlet end of
the labyrinth tube and the guide tube port of the guide tube.
Inventors: |
Pyron; Steven W.; (Tulsa,
OK) ; Bierig; Kevin R.; (Tulsa, OK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Baker Hughes Incorporated |
Houston |
TX |
US |
|
|
Family ID: |
52343706 |
Appl. No.: |
14/333090 |
Filed: |
July 16, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61847382 |
Jul 17, 2013 |
|
|
|
Current U.S.
Class: |
417/53 ;
417/422 |
Current CPC
Class: |
F04D 13/10 20130101;
F04D 29/086 20130101 |
Class at
Publication: |
417/53 ;
417/422 |
International
Class: |
F04D 29/08 20060101
F04D029/08; F04D 3/02 20060101 F04D003/02 |
Claims
1. An electrical submersible pump assembly, comprising: a pump; a
motor cooperatively engaged with the pump for driving the pump; a
seal section having an axis and a labyrinth chamber between
upstream and downstream ends of the seal section; a guide tube
extending along the axis between the upstream and downstream ends
that contains lubricant in fluid communication with lubricant in
the motor, the guide tube having an inlet port adjacent the
downstream end to communicate the lubricant within the guide tube
into the labyrinth chamber; a labyrinth tube within the labyrinth
chamber and having an open inlet end in the downstream end and an
open outlet end within the labyrinth chamber adjacent the upstream
end, the labyrinth tube adapted to communicate well fluid on the
exterior of the seal section into the labyrinth chamber into
contact with the lubricant in the labyrinth chamber to equalize a
pressure of the lubricant with a pressure of the well fluid; and a
non rotating helical blade in the labyrinth chamber encircling the
guide tube, defining a helical flow path between the outlet port of
the labyrinth tube and the inlet port of the guide tube.
2. The assembly according to claim 1, Wherein the labyrinth tube
extends sealingly through turns of the helical blade.
3. The assembly according to claim 1, further comprising: an inner
sleeve surrounding the guide tube; and wherein the helical blade
has an inner diameter edge joined to the inner sleeve.
4. The assembly according to claim 1, further comprising: an outer
sleeve surrounding the helical blade, the outer sleeve having an
outer diameter in contact with an inner diameter of the housing,
the helical blade; and wherein the helical blade has an outer edge
in contact with an inner diameter of the outer sleeve.
5. The assembly according to claim 1, wherein: the seal section has
a housing; and the helical blade has an outer edge in contact with
an inner diameter of the housing.
6. The assembly according to claim 1, further comprising: at least
one baffle along the helical flow path and mounted between adjacent
turns of the blade for retarding flow of well fluid along the
helical flow path,
8. The assembly according to claim 1, further comprising: at least
one baffle along the helical flow path; the baffle having an inner
edge joined, to the guide tube; the baffle having upstream and
downstream edges joined to adjacent turns of the helical blade; and
the baffle having an outer edge located inward from an outer
diameter of the helical blade, defining a gap for well fluid to
pass from an upstream side of the baffle to a downstream side of
the baffle along the helical flow path.
9. An electrical submersible pump assembly, comprising: a pump; a
motor; a seal section housing, having upstream and downstream
connectors that connect the seal section into the assembly between
the motor and the pump, defining a labyrinth chamber between the
upstream and downstream end connectors; a shaft driven by the motor
and extending through the seal section into cooperative engagement
with the pump; a guide tube surrounding the shaft and extending
between the upstream and downstream connectors, the guide tube
defining an annular clearance between the guide tube and the shaft
that contains lubricant in fluid communication with lubricant in
the motor, the guide tube having a guide tube port adjacent the
downstream connector to communicate the lubricant within the
annular clearance into the labyrinth chamber; a labyrinth tube
within the labyrinth chamber parallel to and spaced outward from
the guide tube and having an open inlet end in the downstream
connector and an open outlet end in the labyrinth chamber near the
upstream end connector, the labyrinth tube adapted to communicate
well fluid on the exterior of the seal section into the labyrinth
chamber into contact with the lubricant in the labyrinth chamber to
equalize a pressure of the lubricant with a pressure of the well
fluid; and a non rotating helical blade in the labyrinth chamber
encircling the guide tube, defining a helical flow path between the
outlet end of the labyrinth tube and the guide tube port of the
guide tube.
10. The assembly according to claim 9, wherein the labyrinth tube
extends sealingly through turns of the helical blade.
11. The assembly according to claim 9 further comprising: an inner
sleeve surrounding the guide tube; an inner sleeve port in registry
with the guide tube port; and wherein the helical blade has an
inner diameter edge joined to the inner sleeve.
12. The assembly according to claim 9, wherein: the labyrinth
chamber has an inner diameter and an outer diameter; and the
helical blade has inner diameter substantially the same as the
inner diameter of the labyrinth chamber and an outer diameter
substantially the same as the outer diameter of the labyrinth
chamber.
13. The assembly according to claim 9, further comprising: an outer
sleeve surrounding the helical blade, the outer sleeve having an
outer diameter in contact with an inner diameter of the
housing.
14. The assembly according to claim 9, wherein the helical blade
has an outer edge in contact with an inner diameter of the
housing.
15. The assembly according to claim 9, further comprising: at least
one baffle along the flow path and mounted between adjacent turns
of the blade for retarding flow of well fluid along the helical
flow path.
16. The assembly according to claim 9, further comprising: a
plurality of baffles spaced along the helical flow path between
adjacent turns of the blade for retarding flow of well fluid. along
the helical flow path.
17. The assembly according to claim 9, further comprising: at least
one baffle along the helical flow path; the baffle having an inner
edge joined to the guide tube; the baffle having upstream and
downstream edges joined to adjacent turns of the helical blade; and
the baffle having an outer edge located inward from an outer
diameter of the helical blade, defining a gap for well fluid to
pass from an upstream side of the baffle to a downstream side of
the baffle along the helical flow path.
18. A method of pumping well fluid from a well with a submersible
pump assembly having a pump, a motor cooperatively engaged with the
pump for driving the pump, and a seal section with a labyrinth
chamber between upstream and downstream ends of the seal section,
the seal section having a guide tube extending between the upstream
and downstream ends that has an inlet port adjacent the downstream
end, the seal section having a labyrinth tube within the labyrinth
chamber and having an open inlet end in the downstream end and an
open outlet end within the labyrinth chamber adjacent the upstream
end, the method comprising: mounting a non rotating helical blade
in the labyrinth chamber around the guide tube, defining a helical
flow path between the outlet port of the labyrinth tube and the
inlet port of the guide tube; flowing lubricant from the motor
through the guide tube out the inlet port of the guide tube into
the helical flow path in the labyrinth fluid chamber; submersing
the submersible pump assembly in well fluid in the well; flowing
well fluid through the labyrinth tube out the open outlet end into
and along the helical flow path in contact with the lubricant to
equalize a pressure of the lubricant within the motor with a
pressure of well fluid exterior of the motor; and driving the pump
with the motor, causing the pump to pump well fluid from the
well.
19. The method according to claim 18, wherein: submersing the
submersible pump assembly comprises installing the assembly within
an inclined section of the well; and flowing well fluid along the
helical flow path requires the well fluid to flow upward above the
guide tube, then back downward below the guide tube with each turn
of the helical flow path.
20. The method according to claim 18, further comprising: placing
at least one baffle along the helical flow path; and flowing well
fluid along the helical flow path requires the well fluid to flow
over the baffle.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to provisional application
61/847,382, filed Jul. 17, 2013.
FIELD OF THE DISCLOSURE
[0002] This disclosure relates in general to electrical submersible
pumps for wells and in particular to a pressure equalizing seal
section between a pump and a motor that has a labyrinth chamber
containing a non rotating helical blade.
BACKGROUND
[0003] Submersible well pump assemblies (ESP) are frequently used
to pump well fluid. from hydrocarbon wells. A typical ESP has a
pump driven by a motor. A seal section, normally located between
the motor and the pump, has components to equalize pressure of
lubricant contained in the motor with the hydrostatic pressure of
the well fluid on the exterior of the ESP. Those components may be
a flexible diaphragm, a bellows, or a labyrinth chamber.
[0004] A labyrinth chamber has a labyrinth tube extending downward
from a connector or adapter on the upper end of the labyrinth
chamber. The upper end of the labyrinth tube is open as well as the
lower end, which is spaced a short distance above the lower end of
the labyrinth chamber. A guide tube surrounds the drive shaft
extending from the motor. The guide tube has a port near the upper
end of the chamber. Lubricant from the motor flows up an annular
clearance between the shaft and the guide tube and out the guide
tube port into the labyrinth chamber. Well fluid flows down the
labyrinth tube into the labyrinth chamber into contact with the
lubricant. The well fluid applies the hydrostatic pressure on the
exterior of the ESP to the lubricant in the labyrinth chamber,
which communicates that pressure to lubricant in the motor. The
well fluid has a higher specific gravity than the lubricant, thus
is inhibited from flowing upward in the labyrinth chamber into the
guide tube port to reach the guide tube port. It is important to
keep the corrosive well fluid from flowing down the guide tube into
the motor.
[0005] A labyrinth chamber works well in vertical wells and
provides pressure compensation without any additional moving parts.
However, if the pump is installed in a horizontal section of the
well, the path from the outlet of the labyrinth tube to the guide
tube port is approximately horizontal rather than being vertical.
The well fluid entering the labyrinth chamber could more easily
flow along the horizontal flow path than the labyrinth flow path
that exists while the ESP is oriented vertically.
SUMMARY
[0006] The ESP assembly of this disclosure has a seal section with
a labyrinth chamber between upstream and downstream ends of the
seal section. A guide tube extends along the axis between the
upstream and downstream ends. The guide tube contains lubricant in
fluid communication with lubricant in the motor. The guide tube has
an. inlet port adjacent the downstream end to communicate the
lubricant within the guide tube into the labyrinth chamber. A
labyrinth tube within the labyrinth chamber has an open inlet end
in the downstream end and an open outlet end. within the labyrinth
chamber adjacent the upstream end. The labyrinth tube communicates
well fluid on the exterior of the seal section into the labyrinth
chamber into contact with the lubricant in the labyrinth chamber to
equalize a pressure of the lubricant with a pressure of the well
fluid. A non rotating helical blade in the labyrinth chamber
encircles the guide tube, defining a helical flow path between the
outlet port of the labyrinth tube and the inlet port of the guide
tube.
[0007] Preferably, the labyrinth tube extends sealingly through
turns of the helical blade. In the preferred embodiment, an inner
sleeve surrounds the guide tube. The helical blade has an inner
edge joined to the inner sleeve. An optional outer sleeve surrounds
the helical blade. The outer sleeve has an outer diameter in
contact with an inner diameter of the housing. Alternately, rather
than an outer sleeve, the helical blade may have an outer edge in
contact with the inner diameter of the housing.
[0008] In the example disclosed, at least one baffle is placed
along the helical flow path and mounted between adjacent turns of
the blade. The baffle retards the flow of well fluid along the
helical flow path. The baffle has a portion, such an inner edge,
joined to the guide tube. Preferably, the baffle has upstream and
downstream edges joined to adjacent turns of the helical blade. The
baffle has an outer edge located inward from an outer diameter of
the helical blade, defining a gap for well fluid to pass from an
upstream side of the baffle to a downstream side of the baffle
along the helical flow path.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a side view of an electrical submersible pump
assembly in accordance with this disclosure.
[0010] FIG. 2 is a sectional view of part of the seal section of
the pump assembly of FIG. 1.
[0011] FIG. 3 is a sectional view of the seal section of FIG. 2
taken along the line 3-3 of FIG. 2.
[0012] FIG. 4 is an isometric view, partly sectioned, of an
alternate embodiment of the helical blade assembly of the seal
section of FIG. 2 with the guide tube and shaft of the seal section
not shown.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0013] Referring to FIG. 1, electrical submersible pump assembly
(ESP) 11 is illustrated as being supported on production tubing 13
extending into a cased inclined or horizontal section 12 of a well.
ESP 11 could alternately be installed within a vertical portion of
a well. ESP 11 could be supported by other structure instead of
production tubing 13, such as coiled tubing.
[0014] ESP 11 includes several modules, one of which is a pump 15
that is illustrated as being a centrifugal pump. Pump 15 has an
intake 16 for drawing in well fluid. Alternately, pump 15 could be
other types, such as a progressing cavity pump. Another module
comprises an electrical motor 17, which drives pump 15 and is
normally a three-phase AC motor. A third module comprises a
pressure equalizing or seal section 19 coupled between pump 15 and
motor 17. Seal section 19 has components to reduce a pressure
differential between dielectric lubricant contained in motor 17 and
the pressure of the well fluid on the exterior of ESP 11. Intake 16
may be located in an upper portion of seal section 19 or on a lower
end of pump 15. The terms "upper" and "lower" or used herein for
convenience. While installed in a horizontal well section 12 as
shown, "lower" refers to the upstream direction of well fluid flow,
and "upper" refers to the downstream direction of well fluid flow.
A thrust bearing unit 21 for motor 17 may be in a separate module
or located in seal section 19 or motor 17.
[0015] ESP 11 may also include other modules, such as a gas
separator for separating gas from the well fluid prior to the well
fluid flowing into pump 15. The various modules may be shipped to a
well site apart from each other, then assembled with bolts or other
types of fasteners.
[0016] Referring to FIG. 2, seal section 19 has a cylindrical
housing 23 secured by threads to upper and lower connectors 25, 27.
Upper connector 25 normally bolts to pump 15 (FIG. 1), and lower
connector 27 connects to thrust unit 21, Which may be located
within a lower section (not shown) of seal section 19. One of the
connectors 25 could alternately bolt to another seal section (not
shown) in tandem, Which may have different components than seal
section 19.
[0017] Each of the upper and lower connectors 25, 27 has a bore 29
extending along a longitudinal axis 31. A guide tube 33 extends
along axis 31 from upper connector 25 to lower connector 27. The
lower end of guide tube 33 inserts into and is sealed in bore 29 of
lower connector 27. The upper end of guide tube 33 joins a seal 35
that seals guide tube 33 to upper connector 25. Seal 35 is fastened
to a lower end of upper connector 25.
[0018] In this example, a shaft 37 extends from motor 17 (FIG. 1)
through guide tube 33 of seal section 19 and into pump 15 (FIG. 1)
to rotate pump 15. Normally, shaft 37 has several separate sections
joined by splined couplings. Shaft 37 is radially supported in seal
section 19 by bushings 39 in upper connector 25 and lower connector
27. If seal section 19 is located upstream from or below motor 17,
there would be no shaft extending through it.
[0019] An inlet port 41 extends from the exterior of upper
connector 25 to a lower end of upper connector 25. A labyrinth tube
43 is secured to the lower end of inlet port 41 and extends
downward alongside and parallel to guide tube 33. Inlet port 41
admits well fluid to labyrinth tube 43 and has a check valve (not
shown) to block any flow of fluid from labyrinth tube 43 back out
of inlet port 41.
[0020] Upper and lower connectors 25, 27 and housing 23 define a
labyrinth chamber 45 in seal section 19. Labyrinth tube 43 has a
lower open end or outlet 44 that is a short distance above the
lower end of chamber 45, the lower end 44 being above the upper end
of lower connector 27. Chamber 45 will initially be filled with
motor lubricant, but well fluid will be able to enter chamber 45
via labyrinth tube 43. Chamber 45 has an outlet port 47 extending
through upper connector 25 to the exterior of upper connector 25,
An optional pressure relief valve (not shown) in outlet port 47
allows fluid in chamber 45 to be vented in the event the pressure
within chamber 45 exceeds the hydrostatic pressure of well fluid on
the exterior of seal section 19. The pressure of the lubricant
within motor 17 (FIG. 1) typically increases as the temperature of
motor 17 increases due to operation.
[0021] Guide tube 33 has one or more guide tube ports 49 through
its side wall near its upper end, which joins seal 35. Guide tube
ports 49 communicate fluid in chamber 45 with an annular clearance
or communication passage 51 located between the exterior of shaft
37 and the interior of guide tube 33. Annular clearance 51 is in
fluid communication with lubricant in motor 17 so as to transmit
the pressure in chamber 45 to the lubricant in motor 17. Bushings
39 that radially support shaft 37 do not form a seal, thus allowing
lubricant in motor 19 to flow upward in annular clearance 51 during
the filling procedure, explained below. A mechanical face seal (not
shown) located in upper connector 25 seals around shaft 37 and
retards well fluid from flowing down bore 29 of upper connector 37
into annular clearance 51.
[0022] A helical blade assembly 53 is shown inserted into chamber
45. In the embodiment of FIG. 2, helical blade assembly 53 has an
optional outer cylindrical sleeve 55 that fits closely within the
inner diameter of seal section housing 23. Optionally, seals (not
shown) could seal between outer sleeve 55 and housing 23. Helical
blade assembly 53 has an inner sleeve 57 that is concentric with
outer sleeve 55 and has approximately the same axial length. Inner
sleeve 57 has an inner diameter that slides over and closely
receives the outer diameter of guide tube 33. Optionally, seals
could be located between the inner diameter of inner sleeve 57 and
the outer diameter of guide tube 33. The lower ends of outer sleeve
55 and inner sleeve 57 abut the upper end of lower connector 27 in
this example. The upper end of outer sleeve 55 is spaced a short
distance below the lower end of upper connector 25. A retainer ring
(not shown) could fit into an annular profile 58 in the inner
diameter of housing 23, if desired, to axially secure helical blade
assembly 53 in housing 23 before securing upper connector 25 to
housing 23. The upper end of inner sleeve 57 is illustrated as
abutting the lower end of seal 35. Inner sleeve 57 has one or more
ports 59 that register with guide tube ports 49.
[0023] A helical ramp, flight, or blade 61 is secured within
helical blade assembly 53. Helical blade 61 extends around inner
sleeve 57 in a spiral or helical pattern from the lower end to the
upper end of inner sleeve 57. The angular degree of the helix is
variable, and in the example shown, helical blade 61 makes several
turns around inner sleeve 57. The thickness of helical blade 61 may
also vary. The inner diameter of helical blade 61 is rigidly and
sealingly joined to the outer diameter of inner sleeve 57. The
outer diameter of helical blade 61 sealingly engages the inner
diameter of outer sleeve 55. In this embodiment, helical blade 61
defines a sealed helical flow path 63 extending from lower
connector 27 to guide tube and inner sleeve ports 49, 59.
[0024] Labyrinth tube 43 is preferably a part of the unitized
helical blade assembly 53. Labyrinth tube 43 extends between outer
sleeve 55 and inner sleeve 57 and sealingly through each turn of
helical blade 61. Labyrinth tube 43 may be joined to a holes
provided in each turn of helical blade 61. The upper end of
labyrinth tube 43 protrudes above outer sleeve 55 and inner sleeve
57 and stabs sealingly into inlet port 41 at the lower end of upper
connector 25.
[0025] In the embodiments shown, at least one baffle 65 is located
within helical flow path 63 to impede the flow of well fluid from
labyrinth tube outlet 44 to guide tube port 49. Several baffles 65
are shown in FIGS. 2-4, spaced along the helical length of flow
path 63. Each baffle 65 comprises a plate with a portion 65a, which
may be an inner edge, bonded or joined to inner sleeve 57. Each
baffle 65 has an outer edge 65b that is spaced inward from outer
sleeve 55, defining a gap 67 between baffle 65 and outer sleeve 55.
Gap 67 allows well fluid to flow along helical path 63, but the
flow rate of the well fluid will be impeded by baffle 65. Each
baffle 65 has upper and lower edges 65c, 65d joined to adjacent
turns of helical blade 61.
[0026] Referring to FIG. 3, baffles 65 are spaced at different
angles relative to each other around axis. The angles between
adjacent baffles 65 need not be the same. Baffles 65 are
illustrated as being on radial lines of axis 31 in the embodiment
of FIG. 3.
[0027] Referring to the alternate embodiment of FIG. 4, baffles 65'
may be oblique to axis 31, rather than on radial lines. Also, as
shown in FIG. 4, outer sleeve 55 (FIG. 2) could be eliminated. The
outer edge of helical blade 65' would be in contact or closely
spaced to the inner diameter of seal section housing 23. So as to
facilitate fabrication, preferably, the outer edge of helical blade
65' would not be bonded to the inner diameter of seal section
housing 23. Although not shown, inner sleeve 57 could also be
omitted; in that instance, the inner diameter of helical blade 65'
would be in contact with guide tube 33. Baffles 65 could be flat or
curved. Whether or not inner and outer sleeves 57, 55 are employed,
the inner diameter of helical blade 63 will be substantially the
same as the inner diameter of labyrinth, chamber 45, and the outer
diameter the same as the outer diameter of labyrinth chamber
45.
[0028] To retrofit a seal section 19 having a labyrinth chamber 45
and labyrinth tube 43, the operator removes one of the connectors
25, 27, then the existing labyrinth tube 43. The operator then
inserts helical blade assembly 53 into chamber 45 and stabs
labyrinth tube 43 into inlet port 41. If a retainer ring (not
shown) is employed, the operator installs the retainer ring to
secure helical blade assembly 53 to housing 23.
[0029] After securing seal section 19 to motor 17, the operator
will pump lubricant into a till port near the lower end of motor 17
before installing the check valve in inlet port 41 and pressure
relief valve in outlet port 47. The lubricant flows upward past
bushings 39 in lower connector 27 and into annular clearance 51.
Continuing to pump the lubricant causes the lubricant to flow out
guide tube and inner sleeve ports 49, 59 and down helical flow path
63. The lubricant will flow up labyrinth tube 43 out inlet port 41.
The lubricant will also flow out outlet port 47, indicating to the
operator that motor 17 and chamber 45 have been completely
filled.
[0030] The operator lowers ESP 11 into horizontal well section 12,
which will contain a well fluid that is often a mixture of oil and
water. Well fluid flows into labyrinth tube 43 and into chamber 45
in contact with motor lubricant. The hydrostatic pressure of the
well fluid at inlet port 41 causes the pressure of the lubricant in
chamber 45 and motor 17 to increase and equalize with the well
fluid pressure.
[0031] As motor 17 begins to operate, it generates heat, which
causes the lubricant to expand if the pressure within chamber 45
exceeds the pressure of the well fluid on the exterior of seal
section 19 by a sufficient amount, the pressure relief valve in
outlet port 47 allows some of the lubricant to be expelled. When
motor 17 is shut down, the lubricant will cool, causing the
pressure to drop and possibly some entry of well fluid down
labyrinth tube 43 into chamber 45. Also, leakage of the seals of
shaft 37 over time may tend to allow the encroachment of well fluid
into chamber 45. Thus, eventually, well fluid will be in contact
with the lubricant in chamber 45.
[0032] Normally, the well fluid has a greater specific gravity than
the motor lubricant, resulting in the well fluid migrating
downward. If installed within horizontal section 12 of a well, the
migrating well fluid from labyrinth tube 43 has to flow upward to
some extent along helical flow path 63 from the outlet of labyrinth
tube 43 to guide tube and inner sleeve ports 49, 59. For example,
if axis 31 is substantially horizontal, each time helical flow path
63 encircles axis 31, the well fluid would have to migrate upward,
then downward. At each baffle 65 located above axis 31, the
migrating well fluid has to build up to a sufficient height to flow
over baffle 65 through gap 67. Well fluid can flow through gaps 67
more freely for the baffles 65 on the lower side of axis 31 than
the baffles 65 located above axis 31. When installing ESP 11, the
operator will not know which baffles 65 end up on the lower side of
axis 31 and which on the upper side of axis 31. Without helical
blade assembly 53, the flow path for encroaching well fluid would
be horizontal if ESP 11 is oriented horizontally, thus much more
direct when ESP 11 is inclined.
[0033] If ESP 11 is oriented vertically, in order for the well
fluid to migrate down annular clearance 51 in lower connector 27,
the well fluid must first pass upward through helical flow path 63
from the lower end of chamber 45 to guide tube and inner sleeve
ports 49, 59. The well fluid collecting in the lower end of chamber
45 has to flow back upward in order to reach ports 49, 59 , which
is more difficult because of the heavier gravity of the well fluid
than the lubricant,
[0034] Helical blade assembly 53 may be formed of a variety of
materials, such as carbon steel, stainless steel, Inconel,
aluminum, or thermal plastic. The construction could vary from
casting, machining, molding or other techniques. In addition, water
absorbing materials could be inserted between the turns of helical
blade 61 to remove water contamination from the clean motor
lubricant.
[0035] While the disclosure has been shown in only one of its
forms, it should be apparent to those skilled in the art that
various modifications may be made. For example, having a unitized
blade assembly 53 with an inner sleeve 57 allows a conventional
seal section with a labyrinth chamber to be quickly converted, as
discussed above. If desired, seal section 19 could have a bag or
diaphragm type chamber in tandem with labyrinth chamber 45. Also,
more than one labyrinth chambers 45 could be mounted in tandem.
* * * * *