U.S. patent number 3,677,665 [Application Number 05/141,107] was granted by the patent office on 1972-07-18 for submersible pump assembly.
This patent grant is currently assigned to Husky Oil Ltd.. Invention is credited to John L. Corkill.
United States Patent |
3,677,665 |
Corkill |
July 18, 1972 |
SUBMERSIBLE PUMP ASSEMBLY
Abstract
A submersible pump assembly is disclosed which may be readily
lowered into and raised out of casing and operated downhole in well
fluid in the very confined space of casing of an oil well. The
submersible pump assembly includes a progressive cavity pump of the
Moineau type with a helical stator and a helical rotor. A
submersible electric motor filled with a lubricating fluid is
located below the pump and drives the pump through a speed reducer.
A pressure equalizer is included which provides a pressure
equalizer lubricating fluid reservoir for the electric motor and
the speed reducer and allows for expansion and contraction in the
volume of lubricating fluid. Several embodiments of the submersible
pump assembly are disclosed.
Inventors: |
Corkill; John L. (Calgary,
Alberta, CA) |
Assignee: |
Husky Oil Ltd. (Calgary,
CA)
|
Family
ID: |
22494186 |
Appl.
No.: |
05/141,107 |
Filed: |
May 7, 1971 |
Current U.S.
Class: |
417/410.3;
418/48 |
Current CPC
Class: |
F04C
2/1071 (20130101); F04C 13/008 (20130101); F04D
13/028 (20130101); E21B 43/128 (20130101) |
Current International
Class: |
E21B
43/12 (20060101); F04C 13/00 (20060101); F04D
13/02 (20060101); F04b 017/00 (); F04b 035/04 ();
F01c 001/10 (); F01c 005/00 () |
Field of
Search: |
;417/410,424,372,373,367
;418/48 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Walker; Robert M.
Claims
What is claimed is:
1. A submersible, self-contained pump assembly comprising,
a progressive cavity pump of the Moineau type with a helical rotor
and a helical stator enclosed in an elongate housing with a pump
discharge opening at one end,
the housing having a pump chamber below and in fluid communication
with the pump stator and rotor and having well fluid inlet openings
into the pump chamber,
a pump shaft coupled to the rotor;
a speed reducer in a sealed housing having input and output shafts
at each of its ends;
a pressure equalizer in a sealed housing having a shaft rotatably
disposed therethrough;
an electric motor having an output shaft disposed in a sealed
housing and disposed at the lower end of the pump assembly;
the shaft of the equalizer, the input and output shafts of the
speed reducer, the output shaft of the electric motor and the pump
shaft being coupled together whereby the electric motor drives the
rotor of the pump through the speed reducer at reducer r.p.m.;
the housing of the electric motor, the speed reducer and the
pressure equalizer being connected together to form a unitary
sealed housing for the electric motor, the speed reducer and the
pressure equalizer and being connected to the housing of the
pump;
lubricating fluid reservoir means in the pressure equalizer and in
the electric motor and fluid passageways in fluid communication
with the reservoir means and operating parts of the pressure
equalizer, speed reducer and electric motor for providing
lubricating fluid to the operating parts;
a flexible membrane disposed in the pressure equalizer in one of
said lubricating fluid reservoir means sealing said reservoir means
thereby permitting expansion and contraction of the volume of
lubricating fluid incident to temperature rise and fall caused by
actuation and nonactuation of the motor;
means in the pressure equalizer for flow of well fluid into the one
of said lubricating fluid reservoir means externally of the
membrane providing application of outside pressure against the
membrane thereby equalizing the pressure of the lubricating fluid
with the outside pressure, and
coupling means at the pump discharge means for connection to
tubular fluid conducting means for supporting the pump assembly and
conveying pumped fluid.
2. The submersible, self contained pump assembly of claim 1
where,
the housing of the speed reducer is connected to the housing of the
electric motor and the input shaft of the speed reducer is
connected to the output shaft of the electric motor;
a lower portion of the housing of the pressure equalizer is
connected to an upper portion of the housing of the speed reducer
and input end of the shaft of the speed reducer is connected to and
driven by the output shaft of the speed reducer; and
where an upper portion of the housing of the pressure equalizer is
connected to the pump housing and an output end of the shaft of the
pressure equalizer is connected to and drives the shaft of the
pump.
3. The pump assembly set forth in claim 1 in which the electric
motor operates at a speed of the order of 3,600 r.p.m., and
the output shaft of the speed reducer rotates at a speed of the
order of not more than 600 r.p.m.
4. A downhole submersible pumping apparatus for pumping oil in a
borehole comprising
a generally tubular and sealed housing having an inlet opening and
an upper discharge opening,
coupling means at the upper discharge opening for connection to
tubular fluid conveying means and for supporting the housing in a
generally vertical position within the borehole with at least the
inlet opening submerged in the well fluid and for conveying oil
pumped by the pump,
an electrical motor disposed within and at the lower end of the
housing,
a speed reducer disposed within the housing and coupled to the
electric motor,
an equalizer unit disposed within the housing above the speed
reducer including a motion transmitting means with an output and
with an input coupled to the speed reducer,
a Moineau type pump disposed in the housing above the equalizer
unit and including both a movable holical rotor and a helical
stator secured to the housing, the rotor and stator affording a
communicating passage between the housing inlet and the tubular
fluid conveying means coupled to the housing outlet,
a wall structure separating the equalizer unit from the portion of
the housing containing the inlet opening and including a bearing
structure,
a drive shaft passing through said bearing structure and coupled at
one end to the pump rotor and at the other end to the output of the
motion transmitting means,
the equalizer unit providing a sealed reservoir for lubricating
fluid completely filling a cavity portion of the sealed housing
bound by the wall structure including the electric motor, the speed
reducer and the equalizer unit,
and means including a leakage path through the wall structure for
affording a limited bidirectional flow of fluids including well
fluid from the housing inlet opening and lubricating fluid from the
sealed reservoir between the reservoir and the portion of the
housing communicating with the inlet to allow for expansion and
contraction in the volume of the lubricating fluid.
5. The pumping apparatus set forth in claim 4 in which
the electric motor operates at a speed of around 3,600 r.p.m.,
and
the speed reducer includes means for driving the rotor of the pump
at a speed of the order of 600 r.p.m. or less.
6. A self-contained and electrically powered submersible pumping
assembly for use with well fluids in a casing comprising
an electric motor having an output shaft and disposed in a sealed
housing with an opening at one end;
a speed reducer in a sealed housing having openings at both ends
and input and output shafts at said ends, the motor housing at its
open end and the speed reducer at one of its open ends being joined
and the motor output shaft being coupled to the reducer input
shaft;
a pressure equalizer in a sealed housing with openings at both ends
and with a motion transmitting means passing therethrough having an
input and an output disposed at opposite end openings in the
equalizer housing, the equalizer housing at one of its open ends
being joined to the reducer housing at its other open end, the
reducer output shaft being coupled to the input of the equalizer;
and
a progressive cavity pump of the Moineau type with a helical rotor
and a helical stator enclosed in an elongated housing with a pump
discharge opening at its upper end, a pump inlet opening to well
fluids intermediate its ends, and a coupling opening at its lower
end, said pump having an operating shaft coupled to the rotor and
extending through a fluid permeable bearing structure carried on
the pump housing to the coupling opening, the other end of the
equalizer housing being joined to said lower end of the pump
housing with the equalizer and coupling opening in communication
and the pump shaft coupled to the equalizer output;
the housing for the electric motor, the speed reducer, the
equalizer, and the portion of the pump housing bound by the pump
shaft and the coupling end forming a sealed expansible and
contractible cavity filled with a fluid lubricant, and in fluid
communication with the permeable bearing structure, charges in the
volume of the lubricant causing a flow of well fluid through the
permeable bearing structure;
the pump outlet opening in the pump housing being adapted to be
coupled to tubing extending in the casing from the surface for
supporting the assembly of the electric motor, speed reducer,
equalizer and pump in a vertical position within the casing and for
conveying pumped well fluid to the surface.
Description
BACKGROUND OF THE INVENTION
In producing oil from oil wells, considerable quantities of
particulate matter from the producing formations are produced, such
as sand and other formation solids, which causes undue wear on the
pumping equipment and further, in some instances the conventional
ball and seat type pump cannot handle the large quantity of sand.
In some oil wells, the crude oil is quite heavy or viscous, and it
is extremely difficult to pump with present pumping equipment. It
has been known for some time that Moineau type pumps are able to
pump viscous liquids at low speeds and are able to pump solids or
abrasives suspended in liquids. Further, the use of Moineau type
pumps, which will pump solids or abrasive materials will eliminate
costly jobs whereby the well bore must be cleaned out i.e., the
sand and other material removed from the well bore. Attempts have
been made to adapt and use Moineau type pumps in pumping oil from
oil wells without any real success either operationally or
economically. For example, Moineau type pumps have been suggested
for downhole pumping in oil wells as disclosed in the Hill U.S.
Pat. Nos. 2,737,119; 2,739,650; and 2,976,807. The constructions
illustrated in the Hill patents, however, are not entirely
satisfactory since in these constructions the motor is mounted
above the pump thus requiring the provision of bypass passageways
around the motor housing in order for the pump discharge to reach
the outlet pipe or tubing extending to the surface with its
attendant disadvantages. U.S. Pats. Nos. 2,267,459 and 3,347,169
illustrate Moineau type pumps which are driven from the surface by
means of a rod extending from the surface to the pump with all the
problems and disadvantages involved in rotating a shaft extending
the depth of the casing to drive a pump. Similarly, the Canadian
Pat., No. 458,798 to Wade discloses a Moineau pump which is driven
by a flexible coupling from a prime mover located at the surface
rather than downhole, with similar problems and disadvantages.
For downhole pumping of crude oil, the Moineau pump should be
operated at the relatively slow speed of about 600 r.p.m. or less.
The construction of a submersible electric motor which would fit
into the very confined space of casing in an oil well which would
operate at these relatively low speeds requires an excessive number
of pole structures and would be unduly long with the result that
the cost of the pumping unit as well as the weight to be supported
by the tubing would be substantially increased. None of the patents
suggest or disclose a submersible pump assembly which utilizes
readily available electric motors, which are relatively light
weight and inexpensive, downhole to drive a Moineau type pump at no
greater than 600 r.p.m. nor do they suggest the desirability of
providing a pressure equalizer which provides a pressure equalized
lubricating fluid reservoir for the electric motor and the speed
reducer and allows for expansion and contraction in the volume of
lubricating fluid.
There are, of course, submersible centrifugal pumps manufactured
and sold for downhole pumping of crude oil. For example, Oil
Dynamics, Inc. of Tulsa, Okla., U.S.A., manufactures and sells
centrifugal pumps in which the centrifugal pump is the upper most
stage of the pumping assembly, with a pressure equalizer interposed
between the drive input of the pump and an electric motor which is
the lowermost component of the pumping assembly. These pumps,
however, are high speed centrifugal pumps and are not particularly
well suited for pumping heavy crude oil and oil including any
substantial quantities of particulate material, such as sand. These
prior centrifugal pumping arrangements do not include or provide
any indication of the desirability of the use of Moineau pumps, nor
do they recognize the need for operating them at the order of 600
r.p.m. or less, nor is there any recognition that available
relatively high speed motors can be utilized with a speed reducer
and a pressure equalizer which proves a pressure equalizer
reservoir of lubricating fluid for both the electric motor and the
speed reducer unit. Accordingly, there is a need for a submersible
pump assembly which is relatively simple and inexpensive, which may
be readily lowered into and raised out of casing in an oil well and
operated downhole to satisfactorily pump crude oil containing
particulate matter, such as sand, and heavy or viscous crude oil.
The present invention satisfies this need and provides such a pump
assembly.
Accordingly, the present invention is directed to a submersible
pumping arrangement which advantageously utilizes a Moineau type
pump driven by a relatively high speed electric motor located below
the pump through a speed reducer so that the pump can be driven at
relatively low and optimum r.p.m., for example, of the order of 600
r.p.m. or less, without providing specially designed electric
motors for this purpose, and includes an equalizer which provides a
pressure equalized reservoir for lubricating fluid for both the
electric motor and the speed reducer units, thus resulting in a
pumping assembly which can be readily submerged in a well, which
does not require any bypass passages for the crude oil being
pumped, and which can pump heavy crude and crude oil with
particulate matter in it, such as sand, without excessive wear.
SUMMARY
The present invention relates to a submersible pump assembly
particularly adapted for downhole pumping of heavy crude oil and
crude oil including particulate matter, such as sand and other
solids from the oil-bearing formation, although it may be utilized
for other purposes. More particularly, the present invention
relates to such a submersible pump assembly which utilizes a
Moineau type pump driven by an electric motor located below the
pump, thereby avoiding bypasses for the pumped fluid, through a
gear or speed reducer so that the Moineau pump is driven at optimum
r.p.m. by relatively inexpensive and lightweight electric motors
readily available and which will fit within the very confined space
of casing in a well bore, and which includes an equalizer which
provides a pressure equalized reservoir of lubricating fluid for
both the electric motor and the speed reducing unit.
Accordingly, it is an object of the present invention to provide a
submersible pump assembly which can be readily lowered into and
raised out of casing in an oil well and which can be efficiently
operated downhole to pump oil including substantial amounts of
particulate matter, such as sand and other formation solids, and to
pump heavy or viscous oil.
A further object of the present invention is the provision of an
effective and efficient submersible pump assembly including a
Moineau type pump.
It is a further object of the present invention to provide a
submersible pump assembly utilizing a Moineau type pump which is
driven at optimum r.p.m. with relatively inexpensive and readily
available electric motors located below the pump.
A further object of the present invention is the provision of an
improved submersible pump assembly advantageously utilizing a
Moineau type pump driven through a speed reducer by an electric
motor below the pump, thereby avoiding the necessity of providing
bypasses for the pump fluid around the motor, and which is provided
with a pressure equalizer having a pressure equalized reservoir of
lubricating fluid for both the electric motor and the speed
reducer.
A still further object of the present invention is the provision of
a submersible pump assembly which may be lowered into the very
confined space of casing in a well bore and operated downhole to
pump heavy crude oil or crude oil containing particulate matter,
such as sand, and which includes a Moineau type pumping unit at its
upper end, an electric motor at its lower end, a gear or speed
reducer for reducing the r.p.m. of the electric motor to a
relatively slow r.p.m. for driving the Moineau type pump, and a
pressure equalizer which coacts with and provides a pressure
equalized lubricating fluid reservoir for both the electric motor
and the gear reducer.
A further object of the present invention is the provision of a
submersible pump assembly which is relatively inexpensive and light
weight, which may be lowered into, raised out of and operated
downhole in the confined spaces of well casing in a well bore, and
which effectively and efficiently pumps heavy crude oil or crude
oil including particulate matter, such as sand and other formation
solids.
Other and further objects, features and advantages of the invention
will be apparent from the following description of
presently-preferred embodiments of the invention, given for the
purpose of disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an elevational view, in section, illustrating the
submersible pump assembly in place in well casing in a well
bore;
FIGS. 2A and 2B are taken along the line 2A, 2B of FIG. 1, FIG. 2B
being a continuation of FIG. 2A, which figures illustrate a Moineau
type pump;
FIG. 3 is taken along the line 3--3 of FIG. 1 and illustrates a
pressure equalizer;
FIG. 4 is a view taken along the line 4--4 of FIG. 1 and
illustrates a speed reducer;
FIGS. 5A, 5B are taken along the lines 5A and 5B of FIG. 1 and
illustrate an electric motor, FIG. 5B being a continuation of FIG.
5A; and
FIG. 6 is an assembly view illustrating another embodiment of the
submersible pump assembly in place downhole in casing in which the
speed reducer is located above the pressure equalizer rather than
below it as in FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, and particularly to FIG. 1, the
submersible pump assembly is generally indicated by the reference
numeral 10 and is shown downhole and in place in the casing C of an
oil well for pumping crude oil from the formation F. The
submersible pump assembly 10 is secured at its upper end to and
supported by the tubing 12 extending through the well head 14 from
the surface S, the tubing 12 being connected to the valved line 15
for flowing oil pumped to suitable tanks or other destination as
desired. Also, as shown, gauge 16 is provided for measuring the
pressure of the flow of oil in the tubing 12 and into the flow line
14 to destination. A suitable electrical control panel 18 is
disposed at the surface S and controls the application of
electrical energy through the electric conductor 20 extending from
the surface downhole to the electric motor M for providing
electrical energy to the motor. The casing C is perforated, as at
22, adjacent the formation F, or a suitable screen or the like may
be utilized for permitting the flow of oil from the formation F
into the lower end of the casing C.
The casing C, means 22 for permitting flow from the formation F
into the casing C, well head connection 14, the flow line 15,
pressure gauge 16, control panel 18, an electrical conductor 20 are
all conventional and no detailed description thereof is deemed
necessary or given.
Referring still to FIG. 1, and the embodiment shown therein, the
pump assembly 10 of the present invention includes a Moineau type
pump P which is secured to and supported by the tubing 12, a
pressure equalizer E connected to the lower end of the pump P, a
speed reducer connected to the lower end of the pressure equalizer,
and the electric motor connected as the lower most component of the
pump assembly which, as will be described in more detail later
herein, drives the pump P through the speed reducer R and pressure
equalizer E to provide relatively slow but optimum r.p.m. of the
Moineau type pump P for the pumping operation desired for the crude
oil being pumped.
FIGS. 2A through 5B show considerable detail of the Moineau type
pump P, the pressure equalizer E, the speed reducer R and the motor
M. In the following description of these components, description of
certain structural details, such as couplings, seals and the like
are omitted in order to shorten and clarify the disclosure, and are
not deemed necessary as they are readily ascertainable from the
drawings.
Referring now to FIGS. 2A and 2B, the Moineau type pump P is
illustrated and it includes a generally elongated tubular body 24
which is connected to a generally tubular and inwardly tapered
discharge member 26, which in turn is threaded at its upper end to
the tubing 12 for discharge and flow of oil to the surface as well
as for supporting the submersible pump assembly 10 in the casing
C.
Disposed within the elongated tubular housing or body 24 is a
helical stator 28 and a helical rotor 30, the lower end of which is
connected to the driven pump shaft 32 for driving the helical rotor
30.
A plurality of pump inlet openings 34 are provided
circumferentially around the lower portion of the elongated tubular
pump housing 24 for entry of well fluid into the chamber 36 within
the housing 24 of the pump P, which chamber 36 is in fluid
communication with the stator 28 and rotor 30. The pump P
illustrated is of the progressive cavity type pump and known
commercially as the Moineau pump. The outer helical stator 28 and
the inner helical rotor 30 of the pump P are so arranged in shape
that every thread of the rotor is constantly in contact with the
stator of any transverse section through the pump. This relation of
the rotor 28 and stator 30 is such that a plurality of closed
spaces or cavities are defined between the two members because of
the difference in the number of threads on each member. When the
rotor 30 is rotated relative to the stator 28, the cavities or
spaces between the members are displaced in a longitudinal
direction with the result that fluid material is axially
transported between these two members to obtain the desired pumping
effect. For a detailed consideration of the theory of operation of
a progressive cavity type of pump, reference is made to U. S. Pat.
Nos. 1,892,217 and 2,028,407. Since any progressive cavity type
pump may be utilized as the pump, no more description of the
Moineau type pump P is given or deemed necessary.
Thus, in operation well fluid entering the inlet ports 34 is pumped
as the rotor 30 turns within the stator 28, which forms cavities
which progress toward the discharge end 26 carrying the well fluid,
including any entrained solids, to the discharge end much in the
manner of a screw conveyor.
The lower end of the elongate tubular pump housing 24 is connected
by the coupling 38 to the upper end of the elongated tubular body
or housing 40 of the pressure equalizer E. Similarly, the lower end
of the pump shaft 32 is connected to the input pump shaft 42 at the
lower end of the elongate tubular pump housing 24 which, in turn,
is connected by the splined coupling member 44 to the rotatable
drive shaft 46 of the pressure equalizer E.
While considerable detail of the connections between the pump shaft
32, input pump shaft 42, splined connection 44, coupling member 38
coupling the lower end of the pump housing 36 to the upper end of
the pressure equalizing housing 40 is shown and illustrated,
details thereof are not deemed necessary or given in order to
simplify the disclosure since these various components may be
connected together in any desired manner.
Referring now to FIG. 3, the pressure equalizer E is shown in
detail, and includes a generally elongate tubular housing 48
connected at its upper end to the coupling 40, which in turn is
connected to the coupling 38 (FIG. 2B) connected to the lower end
of the pump body 24. The lower end of the elongate tubular body 48
of the pressure equalizer E is connected by the coupling member 50
forming the upper end of the body 52 of the speed reducer R, as
best seen in FIG. 4.
Referring again to FIG. 3, the pressure equalizer E is provided
with a series of compartments 49, 51 and 53, which are provided by
means of making the outer body or housing 48 in parts connected by
the coupling members 47 and 52.
Disposed in the upper chamber 49 is a flexible collapsible membrane
54 which is sealed to the upper 56 and lower 58 extremities of the
chamber 49. Thus, an expandable and contractable reservoir 55 is
provided within the upper chamber 49. A port 55 extending to the
outside of the pressure equalizer E, through the coupling 40
communicated with the passage 57 in the coupling 40 to the upper
chamber 49. If desired, the bearing structure for the pump shaft
may be permeable to permit outside well pressure to communicate
with the passage 57. Thus, well fluid in the casing is permitted to
enter the port 55 and passage 57 and to exert hydrostatic pressure
of the fluid in the casing C where the pump assembly is located
against the expandable and contractable membrane or bellows 54.
The fluid reservoir 55 formed interiorly of the flexible membrane
54 is in fluid communication with the reservoir chamber 51 by means
of the port 59 at its upper end and by the annular passageway
between the rotating shaft 46 and the annular body member 60, the
communicating fluid passageway 63 in the body coupling member 47,
the annular passageway 65 provided between the outer cylindrical
body member 62 forming the chamber 51 with the annular body member
64 and the outer cylindrical body member 66 of the elongate tubular
housing 48, and through the ports 67 leading to the interior of the
fluid reservoir chamber 51.
Similarly, the reservoir chamber 51 is in fluid communication with
the fluid reservoir 53 by means of the fluid passages 69 in the
annular body member 68 disposed within the body coupling member 47,
the annular passageway 71 disposed between the rotating shaft 46
and the annular inner body member 64 of the fluid reservoir chamber
51, which annular passageway 71 extends through the coupling member
52 to the fluid reservoir chamber 53.
The fluid reservoir chamber 53 is in fluid communication with the
interior of the speed reducer R by means of the radial ports 73 in
the upper thrust ring 70, which fluid passages 73 are in fluid
communication with the annular passageway 75 disposed about shoe
bearing 72 and lower thrust disc 74, which is in fluid
communication with the fluid passage 75 through the annular filter
element 76. The fluid communicating ports 77 are provided in the
annular bearing member 78 surrounding the shaft 46.
As best seen in FIG. 4, a communicating annular fluid passage 79 is
provided about the splined coupling 80 disposed within the coupling
member 50 so that there is fluid communication between the interior
of the speed reducer R and the pressure equalizer E.
Referring again to FIG. 3, a lubricant filler port 81 is provided
in the body coupling member 52 closed by the threaded closure
member 82 for filling with lubricating fluid the lubricating fluid
reservoir chambers of the pressure equalizer E and hence the speed
reducer R and the motor M.
The bearing shoe 72 is secured to the rotatable shaft 46 by the
split ring 82 and the upper 70 and lower 75 thrust discs and
bearing shoe 72 form a thrust bearing assembly for eliminating
thrust from the shaft 46.
A pressure relief valve 84 is disposed within the body coupling
member 50 and is in fluid communication with the reservoir chamber
55 within the flexible member 54 and normally maintains the
communicating fluid port 81 closed, which port 81 communicates with
the fluid passage 83 communicating with the upper reservoir chamber
54 open to the outside through the fluid passage 57 and port 55 so
that excessive pressures within the fluid reservoirs may be
relieved at predetermined pressures, when desired.
As may be readily seen from the drawing of FIG. 3 there are a
plurality of fluid lubricant reservoirs which may expand and
contract and there is fluid communication between there reservoirs
and with the various moving parts of the pressure equalizer E for
lubricating purposes.
While the pressure equalizer is illustrated in some detail in FIG.
3, as previously mentioned, no more description of the various
seals, coupling members, and the like are given or deemed necessary
for an understanding of the present invention. For a more detailed
description of the pressure equalizer, reference is made to U.S.
Pat. No. 3,571,636, granted Mar. 23, 1971, which discloses and
describes substantially this same pressure equalizer.
Referring now to FIG. 4, the speed reducer R is illustrated in
detail. The splined coupling 80 connects the output shaft 84 of the
speed reducer R to the shaft 46 of the pressure equalizer E. The
reducer R includes a generally elongate tubular housing 86 which
contains a planetary gear 88 secured to the input shaft 90 which is
connected by the spline coupling 92 to the output shaft 94 of the
motor M. The planetary gear 88 driven by the input shaft 90 meshes
with and drives the planetary gears 96, which in turn drive the
gears 98 meshing with the gear 100 on the output shaft 84. In the
present embodiment the speed reduction is about 6-1, the motor M
driving its output shaft 94 at approximately 3,600 r.p.m. which, in
turn, through the planetary gear arrangement drives the output
shaft 84 of the speed reducer R at an r.p.m. of about 600.
A thrust bearing assembly generally indicated by the reference
numeral 102 is provided in the reducer body 86 to absorb thrust,
and fluid passageway 81 is provided about the upper end of the
output shaft 84 and outer body member 104 which is in fluid
communication with the port 83 within the output shaft 84. The port
83 is in fluid communication with the fluid passageway 85 in the
input shaft 90, which in turn is in fluid communication through the
ports 87 with the annular fluid passageway 89 in the coupling
member 106 connecting the lower end of the housing of the speed
reducer R to the upper end of the motor M.
A fluid reservoir chamber 91 is provided in the lower end of the
body of the speed reducer R formed by the upper end of the coupling
member 109, in which is provided the filter 108. Thus, lubricating
fluid within the annular fluid chamber 89 is in fluid communication
with the lubricating reservoir chamber 91 and flows through the
filter 108 and provides lubricant for the planetary gear
arrangement previously described. Similarly, lubricating fluid
within the passageway 85 of the driving gear 90 passes in part into
the fluid lubricating chamber 93 for supplying lubricant to the
thrust bearing assembly 102.
No more details of the speed reducer are given since any desired
speed reducer may be utilized which will reduce the speed of the
output shaft of the motor to the relatively slow optimum speed
desired and which is provided with suitable communicating passages
for lubricating fluid to the pressure equalizer and to the various
parts of the speed reducer R which require lubrication. However,
the speed reducer as shown did require special design and
consideration to construct a speed reducer with small enough
diameter to permit entry into and out of the well casing.
Referring now to FIGS. 5A and 5B, certain details of the motor M
are illustrated. The motor M includes the generally elongate
tubular housing 110 closed at its lower end by the motor base 112
and closed at its upper end by the motor head 114 which is
connected to the coupling member 106 closing the lower end of the
speed reducer body 86, as best seen in FIG. 4.
Referring again to FIGS. 5A and 5B, the motor head 114 has the
terminal block assembly 116 for the conductors 112 extending from
the surface so that electrical energy is supplied to the motor in
the usual manner, not shown.
Disposed within the central portion of the tubular housing 10 of
the motor is the wound stator 118 in which is disposed the rotor
120, here shown as two spaced apart rotors secured to the output
shaft 94 and separated by the thrust bearing assembly, generally
indicated by the reference numeral 124.
Disposed in the motor base 112 is an upstanding bearing sleeve 126
which rotatably receives the lower end of the motor shaft 94 and
stablizes it.
A plurality of fluid lubricant reservoirs are provided in the motor
M which include the upper fluid lubricant reservoir 95 and lower
fluid lubricant reservoir 97. The upper fluid reservoir 95 has a
communicating fluid passageway 99 extending upwardly through the
motor head 114 and into the annular fluid passageways 101 and 103
in fluid communication with the annular passageways 89 for
bidirectional flow of lubricating fluid during operation. The fluid
passageway 99 is provided with a filler valve assembly 128 for
filling the reservoirs 95 and 97 of the pump M as well as the
communicating fluid lubricant passageways.
The output shaft 95 from the motor M is provided with a central
passageway 105 which extends substantially throughout its length
and communicates with the fluid passage 107 in the thrust bearing
member 126 housing the ports 109 for flow of fluid lubricant into
the lower reservoir 97 through the filter element 111.
The thrust bearing assembly 124 disposed between the rotors 120 and
122 has the ports 113 for flow of lubricating fluid between the
rotors 120 and 122 and the stator 118.
No more details of the motor M are given or deemed necessary as
electric motors of this type are readily available on the
commercial market.
From the foregoing description and details shown in the drawings,
lubricating fluid within the lubricating fluid reservoirs 95 and 97
in the motor M are in fluid communication with the various moving
parts of the motor M, the speed reducer R, and the moving parts and
fluid reservoirs 51, 53 and 55 of the pressure equalizer E thereby
providing lubricating fluid for the various components and allowing
for expansion and contraction of the volume of lubricating fluid
incident to operation.
In operation, when it is desired to pump oil from the formation F
through the perforations 22 in the casing C (FIG. 1), a suitable
switch on the control panel 18 is actuated to provide electrical
energy through the conductor 20 to the motor M. This causes the
motor M to rotate its output shaft 94 (FIG. 5A) which in turn
drives the input shaft 90 of the speed reducer, which, through the
planetary gear assembly drives the output shaft 84 of the speed
reducer at substantially reduced speed. For example, utilizing a 20
hp motor having an output of about 3,600 r.p.m., the speed reducer
R should be such as to reduce the speed in a ratio of 6-1 so that
the output shaft 84 has an r.p.m. of not greater than about
600.
The output shaft 84 of the speed reducer R then drives the
equalizer shaft 46 extending through the pressure equalizer E (FIG.
3), which, in turn, drives the helical stator 30 of the Moineau
type pump P. The pump is submerged in well fluid in the casing C
above the inlet ports 34 and the oil is pumped or conveyed much in
the manner of a screw conveyor by the pump P into the discharge 26
and on up the tubing 12 to the surface and out the line 15 to
destination, such as tankage, not shown.
During operation, the motor heats the lubricating fluid in the
chambers 95 and 97, causing it to expand, and it expands through
the passageways described ultimately to reservoir 55 within the
flexible membrane 54 disposed in the upper chamber 49, which is
open to the pressures of fluids within the casing C. This
accomodates the expansion of the oil caused by heating the motor
and also contraction of the oil due to cooling when the motor is
not operating. Also, the hydrostatic pressure in the casing C at
the location of the pump assembly 10 bears on the flexible membrane
54 to equalize the pressure of the lubricating fluid within the
pump assembly 10 with the pressure on the outside of the pump
assembly 10 to insure ease and reliability of operation.
Also, as previously mentioned, the various passageways in the
pressure equalizer E, the speed reducer R and the Motor M provide
for flow of the lubricating fluid from the various lubricating
fluid reservoirs and provide lubrication of the moving parts of
these assemblies.
The pump assembly of the present invention may be readily placed in
the casing C by simply lowering it on the tubing 12, which serves
to support it during operation and during lowering into place in
the casing C. If it is desired to remove the pump assembly for
repairs, the tubing 12 is simply raised out of the casing C, the
pump unit is serviced or repaired, as desired, and the pump
assembly 10 may be lowered into position by lowering tubing 12 in
the casing C by a suitable workover rig or other means.
In practice, the complete assembly, pump, equalizer, speed reducer
and motor may be centralized and stabilized inside the casing C by
use of a commercially available rubber centralizer 11. Directly
above the pump P the centralizer 11 may be placed about the tubing
12 whereas below the motor M the centralizer 11 may be placed about
a short length of tubing 13 connected to the motor by a swage 15.
Further stabilizing and centralizing may be accomplished by placing
centralizers 11 around the tubing 12 at various intervals from the
top of the pump P to the surface S.
Reference is now made to FIG. 6 which illustrates an alternate
embodiment in that the speed reducer R is located above the
pressure equalizer E rather than below it as in the embodiment
illustrated in FIG. 1. In this embodiment, the shaft 46 extending
through the pressure equalizer E is connected to and driven by the
output shaft of the motor M (not shown) and the input shaft of the
speed reducer R is driven by the output shaft 46 of the pressure
equalizer E. The construction of the individual components, that is
the motor M, the equalizer E, speed reducer R, and the pump P is
the same as illustrated in FIGS. 2A through 5B, the same fluid
reservoirs, communicating fluid passages and the like for the
lubricating fluid are provided. The difference is that the speed
reducer R is located above the pressure equalizer E rather than
below it. Accordingly, no more detail of this embodiment is deemed
necessary or given.
The manner of operation of the embodiment of FIG. 6 is the same as
that of FIG. 1, and this embodiment may be lowered into, positioned
and raised out of the well the same as the embodiment of FIG.
1.
In both embodiments, the Moineau type pump P is driven at
relatively slow r.p.m., of the order of 600 or less, by a
conventional and readily available commercial motor, which drives
its output shaft at about 3,600 r.p.m., without the added expense
and weight of a special motor which would drive its output shaft at
about 600 r.p.m. Also, fluid lubricating reservoir means is
provided which equalizes the pressures inside and outside the pump
assembly, which permits expansion and contraction of the
lubricating fluid and provides lubrication of the various moving
parts of the components of the pump assembly by a relatively simple
and inexpensive, yet effective and reliable pump assembly.
The present invention, therefore, is well suited and adapted to
attain the objects and ends and has the advantages and features
mentioned as well as others inherent therein.
While presently-preferred embodiments of the invention have been
described for purposes of disclosure, changes in construction,
details and arrangement of parts and components may be made within
the spirit of the invention as defined by the scope of the appended
claims.
* * * * *