Note: Descriptions are shown in the official language in which they were submitted.
2~
DEVICE FOR DELIVERING FLOWABLE MATERIAL
BACKGROUND OF rHE INVENTION
Field of the Invention
This invention relates to devices for delivering
~lowable material and more particularly concerns devices
for delivering flowable material from an underground
borehole.
Description of Prior Art
~ .S. Patent No. 4,386,654 to Becker describes a
downhole pump for delivering flowable material which com-
prises a helical screw type rotor mounted within a resil-
ient stator. The pump is connected to drive means whichalso comprises a helical screw type rotor mounted within
a resilient stator, the rotor being driven by pressurised
oil delivered from the ground surface. The drive rneans
is connected to the pump by drive transmission means in-
cluding universal joints and a drive shaft~
An object of the present invention is to provide adevice for delivering Elowable material from an
underground borehole which is simpler in construction and
relatively easy to manufacture.
Another object of the present invention is to pro-
vide a device of the above type which is more reliable
and able to withstand better the extreme operatinq con-
ditions often present in a production borehole.
SUMMARY OF THE INVENTION
According to the pr sent invention there is provided
a device for delivering flowa~le material from an under-
ground borehole comprising.
a source of pressurised medium;
drive means adapted to be driven by said pressurised
medium;
con~luit neans connecting said source of pressurised
medium alld said drive mean~;
drive tr~nsmission means associated with said drive
~2~
--3--
means;
a pump arranged to be driven by said drive trans-
mission means and said transmission means;
a pump inlet and a pump outlet whereby when the pump
is driven it delivers flo~able material from the inlet to
the outlet;
a delivery conduit communicating with the pump out-
let;
the drive and pump both being oE a rotary displace-
ment type comprising a spiral rotor and a spiral stator;
the stator being mounted in a housing;
the rotor being mounted for eccentric rotation with-
in the stator;
the ~Irive transmitting rneans co-nprising a rigid
connection; and
the rotor and stator of both the pump and ~he drive
mea~s having the same eccentricity.
The concept of designing the rotors and stators of
the drive means and pump to have the same eccentricity
enables a rigid drive transmission means to be utilised,
thereby avoiding the provision of universal joints. This
simpler design with its reduced number of moviny parts is
more reliable, has a reduced risk of breakdown and pro-
vides for longer maintenance free operation.
In a preferred embodiment the working ch~nber volume
of the pump is substantially greater than the working
chamber volume of the drive means. This arrangement pro-
vides for the delivery of a greater volume of flowable
material from the borehole than the volume of pressurised
medium which has to be supplied to the drive means.
The ~se of a smaller volume of pressurised fluid
re~uires a proportionate increase iA pressuce and for
this reason it is preferred to use a multistage drive
m~a~s to reduce the pressure drop between stayes and thus
make it relatively easy to seal the working parts of the
.. . . ... ....
2~8
--4--
drive means against leakage.
The relative increase in working chamber volume of
the pump can be achieved by providing the rotor and stator
with a relatively large spiral pitch, by providing a
relatively large cross-sectional area of the working chamber
or by a combination of both.
It is advantageous that the number o~ stages SA of the
drive means, the number of stages Sp of the pump, the working
chamber volume Vp of the pump, the working chamber volume
V~ of the drive means and the overall efficiency )~GA and ~GP
of the drive means and the pump meet the formula
SA Vp
Sp VA ~GA ~GP- This enables the same load to
be achieved on the sealing edges between adjacent working
chamhers, taking into account the drive and pump losses
occurring during operation.
The spiraled rotors of both the drive means and the pump
are designed to rotate together in the same direction. However,
in some embodiments the drive and pump rotors spiral in the
same direction of rotation and consequently the ~low of mate-
rials through both the drive means and the pump is in the
same direction. This tends to balance the axial reaction
forces exerted on the rotors of the drive means and the pump.
Thus if the reaction forces are of the same magnitude, the
resulting forces to be absorbed by the axial bearing is
greatly reduced.
One way of achieving this flow path is to provide an
intermediate space between the stator casing or rotor casing
and a support casing therefor, by which means the existing
available space can be used and an increase in the housing
diameter can be avoided.
A particularly compact embodiment is achieved by arrang-
ing the stators of the pump and the drive means as outer and
inner stators and arranging the rotors to be carried by a
common body mounted for rotation between the stators.
122~
To achieve the smallest possible flow losses of
flowable material to be delivered, the pressurised medium
is preferably conducted through a pressurised medium con-
duit in the ~orm of a standard diameter hollo~ tube in-
serted into the bore, so that the annular space, whichhas a larger cross-section compared with the hollow tube,
is available between the hollow tube and the bore lining
as a delivery conduit for the flowable material. Fur-
thermore this embodiment has the advantage that chemi-
cally aggressive flowable materials are kept away fromthe bore lining.
In th i s C3 se, the pressurised medium is fed to the
drive means through the annular space between the hollow
tube and the bore hole lining and the flowable material
is delivered through the hollow tube. The diameter of
the tube will be selected as appropriate to the circum-
stances.
The pressurised medium will usually be a pressurised
working oil and the flowa~le material will be a material
such as crude oil to be extracted from below the surface
of the ground and delivered to the surface.
BRIE~F D~SCRIPTION OF THE DRAWING
The invention will now be further descri~ed with
reference to several embodiments which are shown in the
accompanyin~J drawings, wherein:
~IG. 1 is a diagrammatic broken longitudinal section
through a device according to the invention;
FIGS. 2, 3 and 4 are diagrammatic sections similar
to that of FIG. 1 showing alternativ~ embodiments;
YIGS. 5 and 6 are cross-sections through two altern-
ative einbodirnents of drive means or pump;
~IG. 7 is a diagrammatic broken longitudinal section
of a further embodimellt of the device with a co~on rotor
for the drive means and pump;
FTG. 8 is a diagrarnmatic longi~udinal section of
another embodiment of the invention.
D~SCRIPTION OF THE PREFERRED EMBODIMENT
The device shown in FIG. 1 comprises an aboveground
source 1 of pressurised medium which supplies a fluid
under pressure through a conduit 3. The conduit is in
the form of a hollow tube 32 which extends down to an
assembly 4 including a housing 7, a drive means 5 and a
pump 6 located at the bottom of the bore 2. rrhe bore 2
is provided with a bore hole lining 9.
It ~ill be appreciated that the assernbly 4 can also
he arranged at a pcsition other than at the bottom of the
bore 2 where flowable material 8 penetrates from a depos-
it into the bore 2 through apertures in the bore hole
lining 9.
In detail, the drive means 5 consists of a spiral
rotor 10 which is located in a soiral stator 11. A pump
6 is located beneath the drive means 5, the pump, like
the drive means, comprising a rotor 12 and a stator 13.
The drive me~ns and the pump are enclosed by the housing
7.
The rotor 12 of the pump 6 is rigidly connected to
the rotor 10 of the drive means 5 and the lower end face
of the rotor 12 is supported against an axial bearing 140
As can be seen from FIG. 1, the rotor 10 and the stator
11 have the same eccentricity as the rotor 12 and the
stator 13, so that both rotors 10 and 12 execute tEhe same
eccentric movement during operation.
The cross-sectional areas of the working chambers 18
and 19 of the drive means 5 and the pump 6 are the same
but the p~mp rotor 12 and the pump stato~ 13 have ten
~:imes the pitch oE the drive rotor 13 and the drive stat-
or 11. Consequently, for every rotor revolution, the
pump 6 circulates ten times the vol~ne of the pressurised
me~ rn delive~ed to the drive ineans 5. As a result dur-
ing operation, the volume of material discharged at
~2~
--7--
ground level is made up of one part pressurised medium 30and nine parts of flowable material 8 extracted.
If loss-free conditions are assumed, the drive means
5 would have to he pressurised at ten times the pressure
which the pump 6 provides; however, taking into account the
overall effic.iency of the drive means 5 and the pump 6 and
assuming overall efficiency values of 70% each, a value of
twenty times that of ~Pp is obtained for ~ PA according to
the following formula:
l~PA = Vp ~ Pp
V~ ~GA ~GP
wherein VA: working chamber volume of the drive means,
~p: working chamber volume of the pump,
~PA: pressure difference over the drive means,
~Pp: pressure difference over the pump,
q~GA: overall efficiency of the drive means,
~ GP: overall efficiency of the pump.
To overcome the pressure drop over the drive means 5
through the sealing edges of its working chambers 18, the
drive means 5 has twenty times the number of stages of the
pump 6. The pressure component acting on each sealing edge
thus corresponds to that of the pump 6, so that both the
drive means and the pump operate under the same load.
In the assembly 4 as shown in FIG. 1, the flowable
material 8 flows through the openings 15 into the pump 6
and, together with the pressurised medium 29, through openings
16 into the annular space 34, between the bore hole lining 9
and the hollow tube 32. This annular space services as a
delivery conduit 33. A direct path between the openings
15 and 16 is prevented by the packing 17, which is arranged
between the housing 7 and the bore hole line 9.
In this embodiment it will be seen looking from the
same end location that the spirals of the drive rotor 10
and dxive stator 11 are opposite to and the rev.erse
of the spirals of the pump rotor 12
~2~4~
--8--
and pump stator 13. H0nce upon being simultaneously ro~ated
in the same direction, the axial reaction forces applied to
the rotors and axial bearing 14 are therefore cumulative.
On the other hand, the alternative embodiment shown
in FIG. 2 comprises a drive 5 and a pump 6 having spirals
extendiny in the same direction of rotation. Whereas the
pump 6 is identical to that shown in FIG. 1, pressurised
medium 29 is arranged to flow through the drive means 5 in
the reverse direction, that is, from the bottom upwards.
To achieve this, the pressurised medium conduit 3 is routed
past and parallel to the working chamber lB of the drive
means 5 and is directed into it from below.
The use of the same direction of ~low in the drive
means 5 and the pump 6 lead to opposed axial reaction forces
being applied to the rotors 10 and 12. Consequently the
axial reaction forces on rotors 10 and 12 compensate one
another and considera~ly reduce the load on the axial bearing
14. This embodiment, however, still requires a seal 20 to
separate the working chamber 18 of the drive means 5 from the
working chamber 19 of the pump 6.
In the embodiment shown in FIG. 3 the pressurised
medium 29 is fed to the drive means 5 from below as in the
embodiment shown in FIG. 2. In this embodiment however the
arrangement of the drive means 5 and pump 6 is reversed in
the housing 7, by which means a seal between the working
chamber 18 of the drive means 5 and the working chamber 19
of the pump 6 can be dispensed with. In this embodiment
the flowable material 8 enters the bore hole lining 9 through
apertures at a higher level than in the embodiment of FIG 2.
Another embodimen~ of the invention is shown in FIG.
4. In this embodiment the arrangement of the drive means
5, the pump 6 and the conduit for pressurised medium are
the same as the embodiment shown in FIG 1. However, the
4~3
spiral rotor and stator of the pump 6 are designed in the
same direction of rotation as in the drive means 5, so
that flowable Material 8 flows through the pump 6 rom
top to bottom and, after reversal of direction, is
delivered upwardly through a conduit 21 which extends
parallel to the working chamber l9 of the pump 6 and
between the stator thereof and the housing.
F`IGS. 5 and 6 are cross-sections of alternative
arrangements of rotor and stator which can be utilised in
a pump or drive means. In the description of these FIGS.
the reference nu~nerals of similar parts are the same as
those used in FIGS. l to 4.
In FIG. 5, the stator ll, 13 is in the form of a
shaped casing 22 disposed ~ithin the housing 7. The in-
termediate space between the ~alls of the shaped casing22 and the housing 7 are used as a conduit such as the
conduits 3 and 2l which extend parallel to the working
chambers lR and l9. As indicated by the symbols 23 and
24, pressurised medium 29 or flowahle material 8 flows
through the working chambers 18 and 19 in a direction
into the plane of the drawing, whereas they flow through
the conduit 2l and 3 in a direction out of the plane of
~he drawing.
As shown in FIG. 6, it is also possible, either add-
itionally or alternatively, to design the rotors lO and12 as a casing 31 fixed to a support casing 30 and to use
the intermediate space between the casirJg 31 and the
support 30 as a conduit 3 or 21, or to design the rotors
10 and 12 with a hollow section and to use the space so
defined for this purpose.
In the e~bodiment shown in FIG. 7, a more compact
col-struction is achieved by arranging the drive means 5
and the pump 6 to nest inside one another. In this case,
the drive medns is formed by the inner stator ll and the
inner area 26 of a coxrunon rotor 25. The outer stator 13
--10--
and the outer area 27 of the common rotor 25 comprise the
pump.
In ad~ition, an axial seal 28 is provided for the
axial bearing 14. The pressurised medium 29 i5 fed to
the drive means 5 via the hollow inner stator 11 a~d
flows through the associated working chamber 18~ The
flowable mat.erial 8, which in the lower area enters into
the working chamber 19 of the pump 6, also flows upwards
through the working chamber 19. The pressurised medium
29 and the flowable material 8 leaves the housing 7 vla
com~on outlet openings 16. As can be seen from the draw-
ing, an especially short compact construction can be ach-
ieved by this arrangement.
FIG. 8 shows yet a further embodiment of the inven-
t.ion in which the pressurised medium 29, instea~ of beingcondlJcted through the hollow tube 32~ is forced through
the annu1ar space 34 between the hollow tube 32 and the
bore hole lining 9, and the flowable mater.ial ~ is deliv-
ered through the hollow tuhe ~'2. The arrangement of the
drive means 5 and the pump 6 as shown are as shown in~
FIG. 3 but each of the other arrangements shown could
also be adapted for use, in this embodiment~ This alt-
ernative has the advantage that it protects the bore hole
lining 9 in the case of chemically aggressive flowable
ma~eria1s. It is easier and ~heaper to make the hollow
tube 32 ~rom a more cQrrosion or wear-resistant material
and also it is easier to replace the hollow tube 32 in
the event of wear, damag2 or corrosion~
. , ,, . ,, ,~ .... . . ..
