Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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DOWNHOLE PUMP
1 BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTIOM: The invention relates
to a motor and pump construction preferably dimensioned to
permit the insertion of the motor and pump unit through a
previously installed tubing string in a subterranean well. The
pump is utilized to pump well fluids for the operation or a
downhole tool, such as an inflatable packer.
2. SU~ RY OF THE PRIOR ART: Inflatable pac~ers
which are operable by well fluids pressurized by a downhole
motor driven ~ump have been previously disclosed. See, for ,
/G(/I. /
exam~le, U.S. patent ~2,681~706 to POTTORF and patent ~2,839,142
to dUBE~. While each of these patents disclose a motor and
pump unit which is insertable into a well through a previously
installed casing and operates to pump well fluids to expand an
inflatable ?ac~er, these prior art references furnish no infor-
mation as to the electrical and mechanical charac'eristics o
the motor that are reauired to effect an efficient operation or
the downhole pump.
Conventional motors available in the market place are
20 , not designed to withstand the high temperature - high pressure
environment encountered in subterranean wells at depths in
excess of 10,000 ft. Such motors must be able to drive pumps
to supply well fluids as the activating ~luid for a down hole
i well tool, such as an inflatable packer. Such motors must be
25 ! able to generate sufficient power to drive the pump means to
produce a desired flow rate and overcome pressure differentials
encountered in such well operations.
It is, accordingly, an object of this invention to
provide an electric motor driven pumping unit preferably capa-
ble of being inserted through a previously installed tubing
~ ~ ~
1 string which will function to efficiently pressurize well
1uids for the operation of a downhole tool, such as an inflat-
able packer.
SUMMARY OF T~E INVENTION
In accordance with this invention motor means are
employed, preferably in series, and are both mechanically and
electrically connected in series. The energy requirements of
the pump, in terms of both torque and speed, are matched by the
mechanical output of the motor means yet at the same time, the
~otor means are freely insertable through the well, hence are
of substantially smaller size than that which could be e~pected
to produce the total torque required by the pump. Further~ore,
the total current drawn through the electric wireline is mini-
mized bv the electrical series connection.
Additionally, the motors are sealably mounted in axi-
ally stacked relationship within a housing c~ntair.ing both the
pump means and the motor means. The motors are surrounded by a
clean fluid, such as kerosene or water, which is applied at the
surface and which is maintained at well hydrostatic pressure by
a compensating piston arrangement. A single mounting bracket
supports the lowermost motor or the lower end of the motor, if
only one is used, within the housing and the stators of the
motors are keyed to each other to prevent stator rotation. A
~l heavy spring secures the stac~ in assembly.
25 ' Further objects and advantages of the invention will
be readily apparent to those skilled in the art from the fol-
lowing detailed description, taken in conjunction with the an-
nexed sheets of drawings, on which is shown a preferred embodi-
ment of the invention.
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1 BRIEF DESCRIPTION OF DRAWI~GS
.
Figs. lA, lB, lC and lD collectively constitute a
vertical quarter sectional view of a combined motor and pump
unit suitable for insertion through for example, a pre-existing
tubing string to pump well fluids to a downhole tool, such as
an infl~table pac'~er.
DESCRIPTION OF PREFERRED EMBODIMENT
Referring to the drawings, a downhole apparatus 1
embodying this invention-eomprises a housing assemblage 10
which is connec~ed in conventional fashion at its lower end to
a well tool reauiring pressured fluid, such as an inflatable
pac~er 2, (Fig. lD) which is only shown schematically since it
is of entirely conventional construction.
Housing assemblage 10 comprises an upper sub 12 havins
wireline connec_able means 12a for~ed on its upper end and de-
fininc a relatively small internal bore 12b. U~per sub 12 is
securea by threads l~c to a counterbored portion 14a of an up-
per sleeve element 14. ~le threaded connection is sealed by O-
rings 12d.
The medial portion 14b of the upper sleeve element 14
is provided with a radial port 14c which functions as a filling
opening and communicates with the bore 14d of the upper sleeve
portion. Additionally, immediately below the fill opening 14c,
external threads 14e are provided which are connected to the
top end of a coupling sleeve 16. Coupling sleeve 16 is provided
with internal threads 16a at its lower end which threadably en-
gage the upper end of an intermediate sleeve element 18 of hous-
ing 10 and these threads are sealed by an O-ring 18a. The
lower end of the intermediate sleeve element 18 of the housing
10 is provided with internal threads 18b which are engaged with
1 external threads provided on a coupling sub 20. Threads 18b
are sealed by an O-ring 20a. The lower end of coupling sub 20
is provided with internal threads 20b which are secured to a
bottom sleeve ele~ent 22 of the housing 10. Internal threads
22a in the botto~ of the lower housing sleeve 22 provide a
connection to a we~1 tool requiring pressured fluid, such as
the inflatable pac~er 2.
Re~erring to Fig. lC, a conventional wobble plate
pump 30 is mounted within_the interior of housing 10 by a sup-
port ring 21 which is mounted on the upper end of an internallyprojec-ing shoulder of the connecting sub 20. The wobble plate
pu~p 30 is of conventional constrùction comprising a plurality
of peripherally spaced, plunger type pumping units 32 which are
successively activated by an inclined wobble plate 40a carried
on the bottom end of a motor driven shaft 40 which extends
upwardly in the housing 10 for connection to the drivino motors
.. . . .
in a ~anner that will be hereinafter described. Rotation of
shaft 40 effects the oDeration of the pumping plungers 32.
Well fluids are supplied to the inlet side of the
20 '~ pumping plungers 32 through a radial port 20c provided in the
lower end of the connecting sub 20. Well fluids then pass
¦ through a cylindrical filtering sleeve or screen 36 which has
its upper end mounted in a counterbore 20d ~ormed in the bottom
end of connecting sub 20 and sealed thereto by an O-ring 20e.
The bottom end 36b of filter sleeve 36 is sealably mounted in a
counterbore 22b in the top end of sleeve element 22 and sealed
I by 0-ring 22c. The medial portion 36c is preforated or formed
of a screen. The filtered well fluids then pass upwardly
through an annular passage 25 defined between the exterior of a
downwar.~ly projecting mandrel 24 and the internal ~ore surface
1 20f of the connecting sub 20. Mandrel 24 is provided at its
upper end with external threads 24a for securement to the bot-
to~ end of ~he pump 30. The well fluids then pass upwardly
through a plurality of peripherally spaced, fluid passages 18c
provided in the medial portion of the intermediate housing
sleeve e;ement 1~ ~o where the fluids enter the pump unit 30 in
conventional fashion. Fluids discharged from pump unit 30 pass
downwardly through the bore 24a of the depending mandrel 24 and
thus into the inlet end o~ the well tool 2 for which pressured
fluid is required. 0-rings 24b and 24c prevent fluid leakage
f-om the bore 24a of mandrel 24. ~11 or the apparatus hereto-
fore described is entirely conventional, hence fur_her detailec
description thereof is deemed unnecessary.
Near the upper end of the intermediate housing slee~e
18, internal threads 18d are provided whic~ ~oun. an annuLar
seal and motor mounting brac~et 42. Brac~et 42 ;~as an lnter-
nally projecting ledge cor.ion 42a on which a convent-onal
thrust bearing unit 43 and face seal unit 44 is suppor~ed. The
face seal 46 engages the top end of a ring 48 which is sealably
mounted in the bore 42b of the bracket 42 by an O-ring 44a.
. . .
I The face seal 46 thus functions as a bottom end seal for a
!j chamber 50 which extends upwardly through the remaining por-
tions of connecting sleeve 16 and upper housing sleeve por-
1l tion 14 to terminate by a conventional electric wireline con-
25 l~ nector plug 52 sold under the trademark "Remlon". Connectorplug ~2 is sealably inserted in the upper end of the reduced
diameter bore portion 14d of the upper housing portion 14.
Plug 52 is secured by internal threads 14g and sealed by an
0-ring 52a. The electric wire.portion 4 of an electric wire-
line (not shown) extends upwardly to the well surface and down-
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1 wardly to the top motor 60d. The entire chamber 50 may then be
filled at the well surface with a clean lubricious fluid, such
as kerosene, through the fill port 14c which is sealed by con-
ventional chec~ valve 15.
Within the chamber 50, a plurality of substantially
identical D.C. mators are moLnted in axially stac~ed relatiQn-
ship and respectively designated in the illustrated embodiment
as motors 60a, 60b, 60c and 60d. The lowermost motor 60a is
connected to the top end of the pump driving shaft 40 by a con-
ventional mechanical coupling 70, which is only shown schemati-
cally. The bottom motor 60a is connec_ed to the nex' upper
motor 60b by a conventional coupling 72 which is of the type
that effects a mechanical connection. Connector 66d effects a
series connec~ion of the electrical power supplied to the
various motors. Similarily, mechanical couplings 72 are con-
nectea be~een ~he mo~ors 6uo ana 6~c, and Delween ~olors 6uc
and 60d.
It is, of course, necessary that the stator elements
or outer housings 62a, 62b, 62c and 62d of the respective motors
20 il be secured against counter-rotating forces when the respective
motor is energized. To effect such securement, the lowermost
¦I motor 62a is connected to a support ring 64 which in turn is se-
cured against rotation by downwardly extending pins or keys
64a. The lowermost pins 64a engage appropriate slots or holes
provided in the upper end of the motor mounting bracket 42.
Similar anti-rotation and supporting rings 66b are respectively
provided between motor stators 62a, 62b, 62c and 62d. The only
difference in the support rings 66b, and the lower support ring
64a is that the center portions of the upper rings 66D are pro-
vided with annular internal recesses 66d. Pins 64a are employed
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1 to non-rotatively couple each of the motors through the sup-
porting rings 64 and 66b.
A stac~ of Bellville spring washers 68 are provided
to urge a force transmitting ring 69 downwardly against the
stator portion 62d of the uppermost motor 60d. The Bellville
springs 68 are upwardly a~utted by a spring anc;lor 17 whic;l~is
secured to external threads 14h provided on the extreme lower
portion 14k of the upper housing sleeve 14.
Those skilled un the art will understand that the
aforedescribed mounting arrangement for a plurality of D.C.
motors within the limited confines the bore of the housing 10
provides a minimum of supporting structure for the stack of
motors, yet insures that the stack is maintained in intimate
mechanical contact.
The o eration of the aforedescribed pump will be
readi~y apDaLent ~o tnose skiiie~ in tne ar~ ~rom tne loregoing
description. As previously mentioned, the chamber 50 of the
housing 10 is filLed with a clean lubricious fluid, such as
;, kerosene, at the well surface through the check valve 15 and
20 ~l the fill port 14c. This insures that the motors 50 are com-
l¦ pletely isolated from contact with well fluids. It is, however,
¦ highly desirable that the chamber 50 containing the kerosene be
¦ maintained at a pressure substantially equal to the hydrostatic
¦ pressure of the well fluids surrounding the pump 1 so as to
25 I prevent any undesirable contraction of the housing assemblage
10. To provide this feature, a reduced diameter, downwardly
depending portion 14k is formed on the upper housing sleeve 14.
This depending portion 14k cooperates with the inner wall 16c
of the connecting sleeve 16 to define an annular fluid pressure
chamber 45 within which an annular piston 57 is sealably mounted
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1 by seals 57a. A radial port 16d is provided in the wall of the
upper portion of the chamber 55 to expose the upper end of the
piston 5? to the hydrostatic pressure of well fluids surround-
ing the tool 1. The lower face of piston 57 is in communica-
tion with the cha~ber 50 by virtue of axially extending fluidpassages 17b provided in the spring anchor 17. The piston 47
thus comprises a compensating piston and its position in the
c~amber 50 will vary with the external hydrostatic well pres-
sure, effectively transmitting such well pressure to the trapped
~erosene contained within chamber 50.
The selection of the plurality of motors depends, of
course, u~on the input speed and toraue requirements of the
wobble plate pump unit 30. The motors 60a, 60b, 60c and 60d
which may have D.C. voltage characteristics, must be of re-
stric~ed diameter in order to fit within the bore of the hous-
ing asse~lase 10 wh ch, in tu--, m~s_ be carable 5f ~e3d-i
passage through previously installed production tubing in the
well or through casing. This diameter restriction means that
conventional motors may have a limited torque output. For this
reason, a plurality of such motors may be mechanically connected
', in series to multiply the torque outputs by a factor represent-
ing the total number of motors employed. At the same time, the
motors may be electrically connected in series so that the
l applied voltage is distributed substantially equally across
25 1 each of the plurality of motors. This reduction in voltage
effects a substantial reduction in speed of the output shaft of
the motors, hence eliminates the need for speed reduction
gearing which has heretofore been necessary for the successful
utilization of the motors In restricted diameter, downhole
applications. Of course, the invention is not limited to use
1 of motors insertable through production or other tubing, but,
preferably such motors and pumps are anticipated to be used in
such applications.
~n a preferred example of this invention, each of the
D.C. motors have a normal applied D.C. voltage of 0-120 volts
and at such voltage have a rated spe æ of rpm and develop a
torque of 25 in. lbs.. In the utilization of such motors in a
pump of a character heretofore described, and assuming the four
of such motors are emplQy d, the applied voltage across each
10 motor is on the order of 0-120 volts, the output speed is 2,000
rpm and the total torque developed is 100 in. lbs.. These
c~aracteristics closely match the desired torque and speed
in~ut for the wobble type pu~p 30.
The motors may incorporate either a samarium cobolt
magnet or a neodymium maqnet. The use of such magnets is
be'ieved to corr;ibute substantia~ly t_ the energ~ available
to drive the motors, defined as high inch pounds torque at a
given rpm.
By use of the phrase "well fluids" herein it is
20 ~ intended to refer to those fluids which surround the well bore,
! either as naturally occurring fluids, and/or as components of
il drilling, completion or workover fluids introduced into the
~! well for drilling, completion and/or workover applications.
jl Their various contents and applications are well known to those
25 , skilled in the art.
Although the invention has been described in terms of
specified embodiments which are set forth in detail, it should
be understood that this is by illustration only and that the
invention is not necessarily limited thereto, since alternative
embodi~ents and operating techniques will become apparent to
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t those skilled in the art in view of the disclosure. Accordingly,
modifications are contemplated which can be made without depart-
ing from the spirit of the described invention.
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