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.

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.

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.