Note: Descriptions are shown in the official language in which they were submitted.
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1
SEAL ELECTRICAL CONDUCTOR ARRANGEMENT FOR USE WITH
A WELL BORE IN HAZARDOUS AREAS
This is a division of co-pending Canadian Patent
Application Serial Number 2,159,448 which entered the
national phase in Canada on September 28, 1995 and which was
filed as a PCT Application Serial Number PCT/US93/04032 on
April 29, 1993.
STATEMENT OF PRIOR ART
Substantial difficulty has heretofore been encountered
in providing a sealed arrangement for supplying electrical
power to a sealed wellhead over a petroleum producing well
bore in a hazardous area where explosions or fires may occur
due to gases and other substances associated with the
production of petroleum products being ignited by electric
arcs. Also, persc>nnel and the general public are subject to
electrical shock or death by electrocution.
So far as known to applicant, there has not heretofore
been provided a satisfactory and safe method and arrangement
for supplying electrical power through power source
electrical conductor means to electrical conductor means
extending through a sealed barrier associated with a wellhead
associated with a well :bore in a haz<~rdous area to overcome
the above and other problems.
Present commonly employed electrical installations for
supplying electrical. power through the wellhead and into the
well bore for various purposes typically consist of a
flexible corrugated electrical conductor means extending
through the wellhead which are connected externally of the
well bore with tae power source electrical conductor means.
It is substantially difficult, if not impossible, to initiate
and/or maintain an effective seal with the corrugated cable
as
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it passes through the wellhead to prevent discharge of
fluids in the hazardous area. The internal elements of
the electrical cable are also subject to transmitting
well bore liquids and gases therethrough. The gases
and liquids pass through the electrical conductor means
to an electrical enclosure in an adjacent non-hazardous
area which creates another hazardous area. Arcing in
the enclosure can cause an explosive situation. From
this point, the power source electrical conductor means
continues from ground level to the level of the power
transformer. Such outdoor electrical installation is
not in compliance with commonly accepted electrical
practices and requirements, whether such installations
occur in a hazardous or in a non-hazardous location.
Designs previously and currently in use fail to
overcome the problems presented by the above
installations. Both previous and current products
employ the use of an attachment plug and receptacle,
which constitutes a means by which the device being
powered can be disconnected while power continues to be
supplied to the power source electrical conductor
means. The attachment plug and receptacle constitutes
disconnecting means which requires that the attachment
plug and receptacle be rated for the same horsepower as
the device to which power is being supplied. So far as
known to applicant, no such rating is possible,
especially since such plug and receptacle should also
be capable of withstanding an internal explosion
without spreading such explosion.
Inside the wellhead barrier, it is desirable to
provide connectors to connect the power conductors to
the pump cables from a down hole pump. These
connectors allow easy removal in case the well is
pulled. However, problems have arisen where the
connectors have been disconnected and/or damaged due to
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changes in pressure when the pump is turned on or off. It
is known that the :.in.sulation surrounding conductors and.
the rubber typical:~y used for insulation boots are
permeable to fluid::>, such as gas and other liquids in the
well bore. Pressu=°ized and fluid impregnated rubber
tends to fill gaps and exposed seams causing paths for
fluid to escape to undesired areas. A well is typically
pressurized due to pressures exerted by the formation,
and can reach pres.ures at the wel.lhead in excess of
5,000 to :L0,000 poi..nds per square .inch (psi) while the
down hole pump is t:arned nff. such high pressure forces
fluids to saturate any ga:~ per.~meab:le materials such as
rubber and insulat~_on, which would then leak to the
conductors and reach external areas where well fluids are
undesired via the conductors ca~.3.sing a hazardous
situation.
For example, i.r my previous ~Jni~ed States Patent No.
4,614,392, issued ::eptember 30, 1986, it was disclosed
how to seal electrical conductors passing through a
packer within separate steel tubes tc~ provide conduction
from a low pressure.<~rea above the packer to a high
pressure area below flue packer. Steel tubes are inserted
through a penetrator of the packer, where the steel tubes
were terminated on either side of the packer using the
power cable connector:. disclosed. An .insulator stand off
was provided to electrically isolate a connector socket
used to terminate tze conductor and the steel tube. It
has been discovered, however, that well fluids tend to
penetrate the rubber boots surrounding t:he connector
elements and reach the conductive wire, thereby
penetrating the insulator stand off. I'he fluid slowly
escapes to the low pressure area via the conductors. It
is desired, therefove, to provide a more effective fluid.
seal, so that conne:~t.ers placed .in down hole
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pressurized areas will not leak fluids to the low
pressure area.
It has also been discovered that prior connectors
tended to separate when the fluid-impregnated rubber
boots are suddenly depressurized. Depressurization
occurs when the down hole pump is shut off causing a
pressure differential between the fluid-impregnated
boots and the depressurized area surrounding the
connector, since the rubber boots are unable to release
the fluids fast enough. Thus, the rubber boots tended
to expand, forcing apart the mating counterparts of the
connector causing disconnection. An external
protective shield was provided to protect the rubber
and prevent outward expansion, where the outward shield
itself composed two mating parts for allowing the
connection to be disconnected. Even if the two parts
of the protective shield were fastened or otherwise
locked together, the pressurized fluid within the
rubber caused a piston effect, forcing the electrical
connection apart due to the pressure differential. It
is therefore desirable to provide a connector capable
of remaining intnct during pressurization and
depressurization within the well.
The power is typically supplied using three
separate conductors preferably conducting three phase
current. The wellhead generally comprises
ferromagnetic tubing spools and tube hangers to achieve
the necessary strength without undue cost. To meet ~
300-20 of the National Electric Code (NEC), which
concerns induced currents in metal enclosures, the
three conductors carrying alternating three phase
current are typically grouped together to avoid heating
the surrounding ferromagnetic metal by induction. A
single conductor carrying alternating current causes
alternating magnetic flux, which induces electrical
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eddy currents generating heat in the surrounding
ferromagnetic material. Grouping the conductozs
together in a triangular fashion results in
cancellation of a significant amount of the magnetic
5 flux, thereby reducing the electrical eddy currents and
heat by induction. However, grouping the conductors
also creates a larger hole more than twice the diameter
of a single hole, causing an increased radial profile
penetrating the wellhead. A single large hole is more
difficult to seal than several smaller holes. More
significantly, a single large hole forces an off-
centered, or eccentric, main pipe through the wellhead,
usually resulting in a wellhead having a larger
diameter. There is a significant increase in cost
associated with an increase in wellhead diameter.
For example, certain discrete wellhead sizes are
manufactured, where the typical cost between one
wellhead size and the next larger size is approximately
S10,000. It is desirable, therefore, to separate the
conductors to reduce the radial profile of the
electrical connection. Separate conductors are only
allowed under NEC $ 300-20 if slots are cut in the
surrounding metal, or if the conductors are passed
through an insulating wall sufficiently large for all
of the conductors. Neither of these alternatives are
practical or desirable for use in wellheads. Slots
would eliminate the necessary seal, and an insulating
wall so described is not feasible and would also
compromise seal integrity.
3 0 BUI~lIItY OF TAE PR.~SENT IhIYI~NTION
An object of the present invention is to overcome
the problems presented by prior devices and electrical
arrangements used in hazardous areas.
An object of the present invention is to provide a
relatively simple method and arrangement for supplying
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electrical power through power source electrical
conductor means and connecting such electrical
conductor means with the electrical conductor means
associated with a wellhead in a hazardous area for
supplying electrical power into a well bore for various
purposes, by way of example only, such as a down hole
electrical pump, instruments and other down hole
equipment.
Another object of the invention is to provide a
l0 splicing and conduit arrangement which safely conducts
power to electrical conductor means extending through a
sealed barrier in a sealed wellhead that is positioned
in a hazardous area subject to explosions and fires.
Another object of the present invention is to
provide a rigid conduit including a splice fitting
whereby a splice may be formed which separates the
electrical conductor means of a well bore power cable
from the power source electrical conductor means and
seal means in the rigid conduit means between the
splice fitting and the rigid conduit with breather vent
means so as to inhibit the passage of fluids from the
electrical conductor means to the power source
electrical conductor means.
Another object of the present invention is to
provide an arrangement for securing a power source
electrical conductor means adjacent a wellhead f or
supplying power to electrical conductor means that
extend into a sealed barrier associated with the
wellhead which inhibits explosions and fires in the
hazardous area.
A further abject of the present invention is to
provide an arrangement for supplying electrical power
from a power source electrical conductor means in a
rigid conduit which may be secured adjacent the
wellhead and which is arranged so that the rigid
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conduit and electrical conductor means therein may be
disconnected from the wellhead and removed from the
wellhead outside the hazardous area.
A connector within the well is provided, which
includes an outer shell attached to a top stop and a
bottom stop confining rubber boots surrounding the
electrical connection. During depressurization near
the wellhead when the down hole pump is turned on or
the casing annulus pressure is bled off, the rubber
l0 boots are prevented from expanding due to the outer
shell and top and bottom stops, so that the connection
remains intact.
The conductors pass through the wellhead through
rigid tubes and into corresponding connectors according
to the present invention. The conductor extends beyond
the rigid tube and is terminated with a first connector
means, such as a female connector socket, which is
adapted to electrically engage a second conductor
means, such as a corresponding male connection pin. A
stand off is provided around the conductor between the
rigid tube and the first connector means to prevent
electrical conduction to the rigid tube. The standoff
includes an extension lip counter bored to tightly fit
around the rigid tube, and an internal shoulder
abutting the end of the rigid tube. In this manner,
the stand off is forced against the rigid tube forming
an effective fluid seal.
The conductors providing three-phase current
penetrating the wellhead are aligned to achieve a
3o narrower radial profile than that previously possible.
The conductors are preferably arranged side-by-side,
although not limited to this configuration, along an
arc of a circle having its center the same as the
center of the wellhead. Each conductor is surrounded
by a rigid tube comprising a non-ferromagnetic,
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electrically conductive material, where the rigid tube
acts as an eddy current shunt for electrical eddy
currents induced by the magnetic fields generated by
the alternating current flowing through the conductors.
In this manner, electrical eddy currents do not flow in
the wellhead, which would otherwise consume valuable
energy and create undesired heat.
A rigid seal means sealably secures the rigid
tubes penetrating the wellhead to protect the
conductors. A ferrule-type fitting is provided on the
outside of the barrier or wellhead, which includes a
ferrule according to the present invention allowing the
fitting to be removed without destroying the rigid
tubes. The ferrule comprises a resilient material,
such as, but not limited to, hard plastic rated for
high temperature, and more preferably a polyimide
resin. The ferrule is softer than the rigid tube so
that it does not permanently bite into the rigid tube.
Thus, the ferrule is not permanently attached to the
rigid tube, and may be readily removed when the well is
pulled.
A protective metal sheath according to the present
invention protects the insulation of the down hole
cable conductors in the well and provides axial column
strength for the conductors. The triskelion surrounds
and protects the insulation of the cable conductors by
preventing sudden expansion during decompression when
the down hole pump is turned on, or when the casing
annulus pressure is bled off, where the insulation
would otherwise txpand and possibly break causing
electrical failure. The triskelxon is axially fixed in
position to the production tubing to provide the column
strength. The triskelion also provides a protective
transition between a single 3-wire cable extending from
down hole to three single wire conduits.
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An alternative form. of splice fitting includes a
breather boot with a breather passage sealed with silicone
compound to protect the electrical connection between the
power electrical conductor and the electrical conductor
extending through the wellhead barrier from water or
moisture. The breather passage extends into the breather
boot to the exposed conductor wire of the electrical
conductor extending through the wellhead barrier. Thus, if
the seal in the wellhead barrier should fail allowing well
fluids to reach the splice fitting via the electrical
conductor, the silicone compound is displaced with the well
fluids at a lower pressure than the pressure required to
reach the power electrical conductor. This allows the well
fluids to escape the breather boat into the splice fitting.
Thus, the well fluids are prevented from reaching a non
hazardous area via the power electrical conductor.
In accordance with one aspect of the present invention
there is provided an apparatus far conducting alternating
current through a well barrier made :>ubstantially entirely of
ferromagnetic material, said apparatus comprising: at least
one non-ferromagnetic a:Lectrically conductive rigid tube
extending through its own separate passageway in the well
barrier; and a single e:Lectrical conductor carrying the
alternating current extending through the well barrier
enclosed by each rigid tube, said electrical conductor
including insulation electrically isolating said rigid tube
from said conductor.
In accordance with another aspect of the present
invention there is provided an appar<~tus for conducting
multiphase alternating current throw<~h a well barrier made
substantially entirely of ferromagne!~ic material, said
apparatus comprising: a plurality of conductors for
conducting the multiphase alternating current, said
conductors extending through the well barrier; and a
plurality of non--ferromagnetic electrically conductive rigid
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tubes extending through its own separate passageway in the
well barrier, each one of said plurality of rigid tubes
enclosing a corresponding one of said plurality of
canductars.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention, taken in conjunction with the
inventian disclosed in co-pending Canadian Patent Application
Serial Number 2,159,448 which entered the national phase in
Canada on September 28, 1995, will now be described in detail
with the aid of the accompanying drawings, in which:
Fig. 1 is a side view of one preferred form of the
present invention;
Fig. 2 is a top plan view looking down on Fig. 1;
Fig. 3 is a sectional side view partly in elevation on
the line 3-3 of Fig. 1;
Fig. 4 is a top plan view of one form of splice fitting,
with the cover removed, which may be employed to receive a
formed splice which connects power source electrical
conductor means with electrical conductor means in a
hazardous area where the present invEntion is employed;
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Fig. 5 is a side sectional v_~ew, partly in
elevation, showing a splice completed in the splice
fitting of Fig. 4 with a cover thereon;
Fig. 6 is a side sectional view similar to Fig. 5
with the cap or cover of the splice fitting removed and
illustrating the position of the splice before it is
completed and positioned as illustrated in Figs. 4 and
5;
Fig. 7 is a view similar to k~ig. 6 showing an
alternate form barrier for the wellhead;
Fig. 8 is a front view of electrical connection
apparatus according to the present invention within the
well bore of a well;
Fig. 9 is an enlarged view o~ connector within the
well shown in Fig. 3;
Fig. l0 is an exploded side view of the connector
of Fig. 9;
Fig. 11 is a partial sectional view illustrating a
stand off according to the present invention within the
connector of Fig. 9;
Fig. 12 is a partial sectional front view of a
wellhead illustrating relative positioning according to
the present invention of electrical conductors
penetrating the wellhead;
Fig. 13 is a partial sectional view of a rigid
seal means for sealably securing the rigid tube within
the wellhead;
Figs. 14 and 14A are sectional views of a
triskelion according to the present invention for
protecting down hole cables; and
Figs. 15 and 15A are sectional views of an
alternative embodiment of the triskelion of Fig. 14;
Fig. 16 is a top plan view o:~ another form of a
splice fitting according to the present invention, with
the cover removed, for connecting a power source
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electrical conductor means with .3 electrical conductor
means in a hazardous area where the present invention
is employed;
Fig. 17 is a sectional side view showing a splice
completed in the splice fitting of Fig. 16 with a cover
thereon;
Fig. 18 is a sectional side view similar to Fig.
17, with the cap or cover of the splice fitting
removed, to illustrate the position of the splice
before it is completed and positioned as illustrated in
Figs. 1b and 17;
Fig. 19 is a more detailed partial cross-sectional
and reversed view of the electrical connection of Fig.
17; and
Figs. 20A-20F are cross-sectional views of the
electrical connection within the breather boots of
Figs. 16-18 looking along lines 20A-20A, 20B-20B, 20C-
20C, 20D-20D, 20E-20E and 20F-20F, respectively, of
Fig. 19.
D'~SCRIPTION OF 'f8E PREFERRED EI~ODIXEpT
Attention is first directed to Fig. 3 of the
drawings wherein a wellhead arrangement is referred to
generally by the letters WH. Wellheads may assume
various forms and configurations but generally include
some type of member such as by way of example a tubing
spool 7 secured by suitable means such as bolts as
shown to the casing C which projects upward from the
earth E which creates a hazardous area. A tubing
3o hanger 8 may be positioned within the bore of the
tubing spool 7 as shown in the drawings for supporting
a tubing (not shown) which extends downwardly into the
well bore through which the well fluids are conducted
from the producing f ormation(s) in the well bore to the
earth's surface. An adapter spool 9 is illustrated as
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positioned on top of the tubing spool and is adapted to
receive a master control valve (not shown) on the top
thereof for use in a manner well known in the art.
It can be appreciated that the wellhead
configuration and components may change from that
illustrated in Fig. 3 which is given by way of example
only. Regardless of the configuration and components
of a wellhead, the present invention may be employed to
connect power source electrical conductor means with
electrical conductor means which sealably extends
through the wellhead.
The tubing hanger forms a barrier in the wellhead
through which electrical conductor means must extend
for connection with an external power source to supply
power as may be desired to an instrument, down hole
pump or other device.
The power source electrical conductor means and
the electrical conductor means may be of any well known
type, such as by way of example only, each may comprise
multiple separate electrical conductors where each
electrical conductor is insulated and all the multiple
electrical conductors enclosed or encased in a sheath
or outer protective jacket. The power source and
electrical conductor means may each consist of a single
conductor in a sheath or ather protective cover.
The present invention will be described in detail
as employing separate multiple electrical conductor
means, but as noted this is by way of example only.
As illustrated in Fig. 3, the electrical conductor
means f or a well bore cable is shown as having separate
electrical conductor means 10, 11 and 12. As shown in
Fig. 3, these separate electrical conductor means
extend through the tubing hanger, and each is enclosed
within a separate rigid tube means each of which tube
means may be designated 15 which rigid tube means
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sealably extends through the tubing hanger and the
lower annular flange 16 of adapter spool 9 which forms
one type of sealed barrier for the wellhead WH.
Each of the rigid tube means 15 is preferably
formed of material considered to be non-ferromagnetic
such as by way of example only stainless steel, which
is resistant to attack by fluids in the well bore or in
the surrounding hazardous zone. Each tube means 15 is
sealably secured by suitable rigid seal means 20, 20'
in the wellhead. The rigid seal means 20', 26 may be
any suitable well known rigid seal means such as
Swagelok~ or the like which are available over the
counter and which are corrosive resistant and
considered to be non-ferromagnetic may be employed.
Upper rigid seal means designated 20 sealably
secures said rigid tube means 15 with the flange 16 and
also sealably secure one end of the conduit portion 25
with the wellhead WH and/or the rigid tube means 15.
Rigid seal means 26 secure the other end of the conduit
portion 25 with the splice fitting 42. Additional or
lower rigid seal means 20' sealabiy secures the rigid
tube means 15 in the tubing hanger 8 and preferably
adjacent the lower end thereof, but this position may
be changed, if desired.-
The barrier is illustrated in Fig. 3 as comprising
the tubing hanger 8 and flange 16. It may be varied by
the way of example, to comprise only the tubing hanger
8 or flange 16.
Where the barrier in the wellhead consists of only
the tubing hanger 8 as shown in Fig. 7, a single rigid
seal means may be employed under some conditions to
secure rigid tube means 15 with the hanger 8 but it is
preferred that the upper and lower rigid seal means 20,
20' each be positioned as shown in Fig. 7 to sealably
secure said rigid tube means 15 with the hanger.
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Should the annular flange 16 be employed as the
barrier then the rigid seal means 20 may be connected
at a single location to sealably secure the rigid tube
means 15 passing therethrough, or to same double rigid
seal means 20, 20' arrangement described above when the
tubing hanger serves as the barrier may be employed to
sealably secure with the flange 15. and the rigid tube
means 15. It can be appreciated that the location of
the rigid seal means 20, 20' in any situation may be
varied to accomplish the desired sealing effect with
the hanger 8 and/or the flange 16.
Regardless of the form of barrier, the conduit
portion 25 is sealably secured therewith as described
above.
In the embodiment illustrated in Fig. 3, the
electrical conductor means l0, 11, 12 are each further
protected by the rigid tubes 15 which surround each of
the electrical conductor means from the sealing tube
fitting 20' at the lower end of the tubing hanger 8 and
2o each rigid tube means extends to a separate connector
represented generally by the numeral 23 wherein the
three down hole separate electrical conductor means of
the well bore power cable are each connected with one
of the separate connectors 23. Suitable protection
means such as flexible or rigid tube means forming
conductor extensions 24 separately surround each of the
electrical conductor means and depend or extend
downwardly in the well bore to terminate adjacent the
protective jacket on the power cable which jacket
receives and encloses all three electrical conductor
means therein. The rigid means 20', 26 employed
provide a metal to metal seal between the components.
It can be appreciated that the wellhead and tubing
hanger are provided with suitable seals as illustrated
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in Fig. 3 for inhibiting the flow of fluid therefrom in
a undesired manner.
Where the electrical conductor means comprise
separate insulated electrical conductor means l0, 11,
5 12 as shown in Fig. 3 each may be received in a
separate conduit portion 25, which as previously noted,
is sealably secured at one end by the rigid seal means
to the wellhead WH and at its other end by the rigid
seal means 26. Where the electrical conductor means
10 consists of a plurality of separate insulated
electrical conductor means enclosed in a sheath or a
single electrical conductor means in a sheath which
extends through the wellhead, then there is only a
single conduit portion 25 sealably secured adjacent the
15 barrier and adjacent splice fitting 42 by rigid seal
means 26. The rigid means 26 is preferably a swivel
nut Swagelok~ fitting to enable the arrangement of the
present invention to be more readily disconnected from
the wellhead as will be described herein. The conduit
20 portions) 25 may be flexible or rigid of any suitable
type to withstand the conditions under which they will
be employed and to safely supply the power from the
power source electrical conductor means to the
electrical conductor means of the power cable extending
downwardly in the well bore (not shown). The conduit
portions) 25 should be capable of withstanding a
minimum of 600 psi internal test pressure and are
preferably formed of Monel 400 which is considered to
be non-ferromagnetic and which will withstand the
corrosive conditions to which the flexible electrical
conduits may be subjected. Any other suitable flexible
or rigid material which is corrosive resistant and
considered non-ferromagnetic and capable of
withstanding 600 psi internal test pressure may be
used. The conduit portions) may be obtained from any
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suitable source and is an over the counter type of the
product with one form including a metal internal
bellows surrounded by wire braid. The rigid seal means
26 which connects the flexible conduits and the single
electrical conductor in each of said flexible conduits
may be of any suitable type available on the market
such as Swagelok~ as previously noted. The rigid seal
means 20 is described more fully below.
Rigid conduit means' or pipe formed of suitable
l0 material, preferably metal is illustrated at 40 in Fig.
1 for receiving power source electrical conductor means
which extend from a suitable power source (not shown)
to adjacent the wellhead in what means be termed a
hazardous area adjacent the well on which the wellhead
is positioned. It can be appreciated that the rigid
conduit or tubular member 40 extends from what may be
termed a non-hazardous area where the power source is
located into the area designated hazardous adjacent or
around the wellhead. The end of the rigid conduit 40
immediately adjacent the wellhead is provided with a
splice fitting 42 provided with a removable cap or
cover 43 for gaining access thereto to splice the
electrical conductor means with the power source
electrical conductor means. Where the electrical
conductor means is as illustrated at 10, 11 and 12 they
each will be spliced with one of the power electrical
conductor means 10a, lla and 12a extending from the
rigid conduit 40 to the splice fitting 42. The splice
fitting 42 may be of any suitable well known and
accepted type Which is sold over the counter, such as
the Crouse-Hinds Catalog No. LBH70.
Means for forming a splice is provided for
positioning within the splice fitting 42 as shown in
Figs. 4-6 inclusive. Such means includes an insulating
member 46 of any suitable electrical insulating
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material which provides as much and preferably more
electrical insulation than that of the electrical
insulation of the conductors to be spliced, such as
delrin. Where the power source and electrical
conductor means consist of separate electric conductor
means, then separate passages of the same number as the
electrical conductor means will be provided in
insulating member 46. In the embodiment shown in Figs.
4-6, three separate passages 47, 48 and 49-extend
through the member 46 to receive 10, 11, 12 and 10a,
11a, 12a as shown in Fig. 4. The passages 47, 48 and
49 which extend from the one end 40 and into the member
46 are of less lateral extent than the portion of each
passage which extends inwardly from the other end 51 of
the member 46 as shown in Fig. 5. The junction of the
enlarged passage portions extending from the end 51
with the smaller passages extending from the end 50 of
the member 46 provide a shoulder 53 as shown. The
passages 47, 48 and 49 communicating with the end 50
each receive therein one of the power source electrical
conductor means 10a, 11a, 12a extending through rigid
conduit means 40 from the cable that encloses them and
connects with a suitable power source (not shown) as
illustrated in Fig. 4. The conductor element or
portion of each of the power source electrical
conducting means is exposed as shown at 10a', 11a' and
12a' respectively. Separate splice connectors 55 are
shown, each of which has a passage which extends
partially from one end of each connector for receiving
the exposed portions 10a', 11a' and 12a' of each of the
power source electrical conducting means and each
splice connector 55 is provided with suitable means
such as a screw 58 for securing each of the exposed
elements of each of the electrical conductor means in
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one end of the electrical conductor splice connector
55.
Similarly, the exposed conductor element portion
10', i1' and 12' of each of the electrical conductor
means 10, 11 and 12 is exposed as shown in Figs. 4 and
5 and each extends into a passage extending into the
other end of each electrical conductor splice connector
55 and is secured therewith by a screw 58' or the like.
The member 46 may then be moved to a desired
to position within the splice fitting 42 and the cables
10, 11, 12 and 10a, 11a, 12a positioned so that if
desired one end of the member 46 may abut the shoulder
53 as shown in Fig. 5. An insulating screw 60 formed
of plastic or the like may be positioned between the
two longitudinally spaced screws 58 and 58' on the
center member 55 to retain the splice connectors 55 in
position as desired within the insulating member 46.
If desired, additional insulating screws may be
positioned in member 46 to abut the end of each splice
connector 55 which is adjacent the outer splice
connector 55 nearest the end 51 of member 46.
To assure that the present invention will function
within the hazardous area as desired, it is preferable
in most instances, that a seal means represented by the
numeral 65 be provided in the conduit~downstream of the
splice fitting 42 adjacent the wellhead in which the
plural electrical conductors of the power source are
spliced with the multiple electrical conductors of the
down hole power cable as previously described.
The seal means 65 is downstream from the wellhead
and comprises a seal fitting 66 with a sealant 67
therein. The sealant 67 is preferably and should be
obtained from the manufacturer of the seal fitting.
For example, in the present instance the seal fitting
is catalogue No. EYD6, used as one off the shelf
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WO 94!?~726 PCTIUS93I04032
19
example of a suitable fitting which may be employed and
is manufactured by Grouse-Hinds and the seal compound
or sealing means of Grouse-Hinds should be employed
with that fitting. Where a seal fitting of another
manufacturer is employed, then that manufacturer's seal
means including its sealant compound is employed.
Particular means of Grouse-Hinds for the specific
seal fitting above designated, comprises a compound and
a fiber. Grouse-Hinds refers to its sealant comaound
l0 as Chico A and the fiber is referred to as Chico X. To
form the seal means 65, the seal fitting 66 may be
provided with the sealing 67 prior to or after its
connection with the nipple 31 which is connected to the
end 42a of splice fitting 42. In either situation the
Chico X fiber is stuffed in the fitting 66 and then
Chico A compound is mixed with water in accordance with
the manufacturer's instructions and then poured into
the seal fitting on top of the fiber. The thickness,
or longitudinal extent of the sealant 67 formed within
a seal fitting must at least be equal in longitudinal
length to the diameter of the fitting member in which
it is positioned. It is recommended that the minimum
diameter of the conduit or tubular member for receiving
the plural electrical power conductors from the power
source and various fittings employed herein have a
minimum diameter of 2 inches, then the minimum
longitudinal extent of the seal fitting 66 should be
not less than 2 inches. As better seen in Figs. 5 and
6, a nipple 31 is connected between the seal fitting 66
and the end 42a of splice fitting 42. Where the seal
fitting 66 is secured in position between nipple 31 and
conduit 40, the sealant 67 is formed therein by
inserting Chico X and Chico A and then adding Chico A
compound as described above. The seal fitting 66
includes the plug 68 and breather 69 as best
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WO 94125726 PCTIUS93104032
illustrated in Figs. 1 and 3 with another seal fitting
66' shown connected in the downward extension of
conduit 40 outside the hazardous area as shown in Fig.
1, and the sealant may be formed by removing plug 68
5 and then repositioning the plug ir. the seal fitting
after the sealant is formed in the fitting. The
sealant 67 is formed within the seal fitting 66 and is
within 18 inches from the adjacent splice fitting 42.
In the preferred embodiment illustrated, such
10 female seal fitting 66 is for sealing in a vertical or
a horizontal position and is preferably by way of
example only, the EYD6 of Grouse-Hinds, as previously
noted. It can be appreciated that other conduit seal
fittings, vertical or horizontal, male and female,
15 elbow seal, female hubs, male and female hub may be
employed in certain situations.
The seal fitting 66 shown in Fig. 3 is connected
at its end 66b to the conduit 40, and also includes a
plug 68. A breather or vent 69 in the seal fitting 66
20 is between the sealant and the wellhead in the
drawings. Seal fittings 66 and 6~' are preferably the
same. Seal fitting 66 is connected in the conduit 40
and then connects with splice fitting 42 which in the
preferred embodiment is adjacent the wellhead in the
hazardous area. Seal fitting 66' is connected in
conduit 40 outside the hazardous area.
The seal. means 65 including seal fitting 66,
sealant 67 and breather tube or vent means 69 are for
allowing an internal explosion to occur therein and in
the arrangement in a hazardous situation without
conveying the explosion internally of the conduit 40 or
externally thereof. Also, it accommodates a flame or
fire within such confinement, without permitting or
conveying the flame externally. The breather vent is
constructed in a well known mannea to contain internal
CA 02246400 1998-10-06
VfO 94125726 PCT/US93I04032
21
explosions and first or flames within the arrangement.
In addition to the foregoing the breather tube 69 aids
in discharging fluids, liquids and gases from the seal
fitting 66. Ln this regard, it should be noted also
that the sealing compound used in Conduit seal fittings
is somewhat porous so that gases, particularly those
under slight pressure with small molecules such as
hydrogen may pass slowly through the sealing compound.
Also, it should be noted that there is no gasket
l0 between the splice fitting 42 and the cover 43 to
permit the discharge of fluids from the splice fitting
42 to the surrounding atmosphere. If any gas or fluid
should migrate through the insulation of the electrical
conductors 10, 11 and 12 between the wellhead and the
splice fitting, gas is permitted to escape through the
conduit seal fitting 66 through the breather 69, as
noted previously.
Also, the arrangement and configuration of the
splice within the splice fitting 42 does not directly
connect or join the two sets of cables in engagement
together and thereby isolates the multiple conductors
of the power cable from the plural conductors of the
power source to further inhibit movement of gas and/or
liquids from the well bore through the conduit 40 and
the electrical conductors.
The rigid conduit means 40 may extend from the
wellhead in an elevated relationship as illustrated and
then the portion thereof as shown in Fig. 1 depends
downwardly into the earth represented by the letter E
at a location as illustrated at 40r in Figs. 1 and 3
beyond the portion or area classified as hazardous.
Another splice fitting 42' may be provided and a splice
formed therein in the manner as described and
illustrated with regard to Figs. 4, 5 and 6 herein to
connect electrical conductors from a power source with
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CVO 94125726
PCTlUS93104032
22
the plural electrical conductors in rigid conduit means
40. In this situation a union 88 may be threadedly
connected with the end of the splice fitting 66' as
indicated and also connected with the seal fitting 66'
therebeneath. The seal fitting 66' is connected in
turn to an elbow 71 that extends into the ground at the
location outside the hazardous area. The splice
fitting 42' is also preferably provided within 18
inches of splice fitting 42' as previously described
with regard to splice fitting 42.
Suitable support means are provided for securing
or locking the splice fitting 42 and conduit means 40
in position adjacent the wellhead and such means
includes a bracket represented by the letter B with a
portion 70 secured to the wellhead in any suitable
manner such as by the bolt and nut means as illustrated
in Fig. 3 of the drawings. The bracket B has a lower
upwardly extending portion 71 and a separate upper
portion 72 for connection with the lower upwardly
20. extending portion ?1. The top edge of lower portion 71
and the bottom edge of the upper portion 72 are each
provided with matching semi-circular recess 71a', 72a'
to receive the end 42c of splice fitting 42 there
through as shown in Fig. 3 of the drawings. Suitable
bolts (nat shown) may then be secured through the upper
portion 72 to extend into the lower 71 to secure the
bracket in position with the splice connected as shown
in Fig. 3.
In the embodiment illustrated, suitable means as
provided to lock the splice fitting 42 to or adjacent
the bracket H and to the wellhead. Such means may
assume any form and as illustrated includes the semi-
circular rings 74 and 75 on the lower and upper
upwardly extending portions 71, 72 respectively which
rings project beyond the semi-circular recess defined
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1W0 94125726 PCTIUS93104032
23
by the mating lower and upper bracket portions 71, 72.
The rings 74, 75 extend into a groove 42d formed in the
splice fitting and thereby lock the splice fitting and
bracket to the wellhead.
In another form, the securing means may be in the
form of a nipple that is threaded into the end 42c of
the splice fitting 42 and is provided with an end that
is threaded externally and which projects through a
circular opening in a bracket portion which extends
upwardly from the portion 70 to receive the end 42c of
the fitting therethrough. The threaded nipple end
projects through the opening in the upstanding bracket
portion receives a threaded ring thereon that abuts the
upstanding bracket portion to secure the splice fitting
42 in position adjacent the wellhead.
In Fig. 6 any suitable instrument such as a
screwdriver 81 may be employed to secure the screws 58,
58' of each of the splice connectors 55 with the
respective conduit exposed ends of the plural
conductors of the power cable and the multiple
conductors of the down hole cable.
A suitable housing H is provided to enclose the
splice fitting 42 adjacent the wellhead to inhibit
fluid such as water and the like from entering
thereinto. Such housing as shown in Fig. 3 includes a
top wall 82, side walls 83 and an end wall 84 as shown.
It will be noted that the top cove> 82 of the housing H
is provided with a cut away portion represented at 86
in Fig. 3 so that the housing fits snugly adjacent a
portion of the spool 9 as illustrated. One of the side
walls such as the wall 83 is provided with an opening
85 to enable the splice connector 42 to extend
therethrough for communication with the conduit 40.
The housing H is secured to the bracket B by non-tamper
screws or nuts represented at 87 in dotted line.
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24
Similarly, the covers 43 for the splice fittings 42,
42' are maintained in position by non-tamper means 87
well known in the art to inhibit access, except with
special tools. This effectively locks the housing H
and caps 43, 43' in place so that access can be gained
only by authorized personnel. The splice fitting 42'
outside the hazardous area connects the horizontal
portion of the conduit means 40 with the vertical
portion thereof as shown, and as previously noted, a
l0 splice is farmed therein in the manner as described
with regard to the splice fitting 42.
The present invention is advantageous in that it
provides an arrangement so that the power source
electrical conducting means which supply power to the
wellhead are maintained in a conduit, Which conduit can
be easily moved out of the way or disconnected from the
wellhead when desired.
To effect such disconnection and/or removal, the
splice in the splice fitting 42 immediately adjacent
the wellhead is disconnected by reversing the splicing
procedure previously described and the splice fitting
42 is unlocked from the bracket B. The union 88 may be
rotated whereupon the conduit means 40 with the power
cable therein can be rotated sufficiently to displace
it from the wellhead. At the same tijne as the splice
in fitting 42 is disconnected or thereafter, the splice
in the splice fitting 42 may be disconnected and the
union disconnected from the splice fitting so that the
entire horizontally extending rigid conduit means 40
may be removed to a remote location while wellhead
operations are conducted.
In the preferred embodiment the conduit means 40
extends from its connection with the wellhead in
horizontal elevated plane or position above the earth
as shown.
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Where the electrical conductor means is a single
large member, an offset tubing hanger may be required
to accommodate passage of such conductor therethrough.
Alsa, it can be appreciated that the conduit portion 25
5 may be formed by extending rigid tube means 15, or by a
separate conduit portion connecting directly into the
passages) in the barrier for communicating with the
rigid tube means sealably secured therein. It can be
further understood that the connector arrangement 24
10 can be modified to provide a single connector where the
electrical conductor means is a single member.
Preferably the outer jacket and any other coverings of
the power source electrical conductor means should be
removed so that the sealing compound, or sealant 67, in
15 the seal fitting 66 will surround each individual
insulated conductor and the outer jacket.
Referring now to Figure 8, a front view is shown
of apparatus according to the present invention within
the well bore below the barrier or wellhead WH. In the
20 preferred embodiment, three similar rigid tubes 15
enclosing the electrical conductor means 10, 1l, 12
connect to three similar connectors 23. The connectors
23 connect the electrical conductor means 10, 11, 12 to
three separate and similar down hole cable conductors
25 118 (Fig. 9) extending from down hole from a pump or
similar electrical apparatus requiring power. The
connectors 23 connect to a triskelion 150, which is
used to protect the down hole cable conductors 118, to
provide column support and to provide a transition from
a 3-wire cable 155 containing the three down hole cable
conductors 118 to the three single cable conductor
extensions 24. The triskelion 150 and the 3 wire cable
155 are banded or otherwise clamped using clamp means
160 to production tubing 162.
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26
Referring now to Figure 9, an enlarged view of one
of the connectors 23 is shown. Only the connection for
the electrical conductor means 11 is shown and its
corresponding rigid tube 15, it being understood that
similar connections and apparatus are used for the
electrical conductor means 10, 12, if included. The
rigid tube 15 is inserted and passes through a top
fitting 100 and a top stop 102. The top fitting 100
and top stop 102 are preferably made of a non-
l0 ferromagnetic, electrically conductive material, such
as stainless steel, for example, or the like. The top
fitting 100 is preferably a ferrule-type fitting, such
as, for example, Swagelok~ or the like, so that the top
fitting 100 is fixedly attached to the rigid tube 15.
The top fitting 100 preferably includes four parts,
including an upper fitting 100x, a lower fitting 100b
and a two-piece ferrule (not shown) for securing the
top fitting 100 to the rigid tube 15. The lower
fitting 100b includes a threaded extension 100c for
interfacing a threaded hole 102a of the top stop 102,
so that the top fitting 100 is screwed into the top
stop 102. Alternatively, the lower fitting 100b of the
top fitting 100 may be integrally formed with the top
stop 102 for convenience and reduced cost.
The top fitting 100 is preferably a close fit
having a relatively tight tolerance around the rigid
tube 15. The top fitting 100 is preferably tightened
to crimp the rigid tube 15 to preferably form a fluid
seal. This choking effect of the rigid tube l5 by the
3o top fitting 100 further prevents fluid flow from the
well bore to an external low pressure area 132 through
the rigid tube 15.
An outer sleeve 104, preferably comprising a
hollow cylindrical tube, preferably made of a non-
ferromagnetic electrically conductive material, such as
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WO 94J~5726 PCTlUS93J04032
27
stainless steel, for example, or the like, fonas a
protective shield circumscribing the connector 23. The
outer sleeve 104 includes an upper hole 104a (Figure
10) for receiving a set screw 106. The top stop 102
includes a corresponding threaded hole 102b for
receiving the screw 106. In this manner, the outer
sleeve 104 is slid around the top stop 102 so that the
holes 104a and 102b are aligned, and the screw 106 is
screwed into the threaded hole 102b through the hole
104a of the outer sleeve 104 and tightened to the rigid
tube 15. The outer sleeve 104 is thus fixedly attached
to the top stop 102, which is attached to or integrally
formed with the top fitting 100.
Figure 10 is an exploded side view of the
connector 23, included for purposes of clarity.
The rigid tube 15 extends past the connector 23 to
a lower end 110, which engages a stand off X12. The
electrical conductor means 1l extends beyond the lower
end 110 of the rigid tube 15 through the stand off 112
to the upper end 114a of a female connector socket 114.
The insulation 113 (Figure 1l) of the electrical
conductor means 11 is stripped off exposing the
conductor element portion 11', which is crimped and/or
soldered to electrically and mechanically connect it to
the female connector socket 114, as known to those
skilled in the art.
The female connector socket X114 includes a socket
portion 114b at its opposing end for receiving a male
connector pin 116. It is noted that the particular
male and female connectors described herein could be
reversed, or otherwise replaced with other slidable
connector means as known, so that the present invention
is not limited by any particular connector means. The
male connector pin 116 and the female connector socket
114 are formed of any suitable electric conducting
CA 02246400 2003-04-15
GH
material such as copper, or the like, and each is formed
by a plurality of .Longitudinally extending portions which
are configured to ax;i_ally align and mate. A similar
connection configuration is more fully described in the
IJ.S. Patent No. 4,614,392. In this :manner, the male
connector: pin 116 and the ferr;ale connector socket 114 are
coupled together for electrically connecting one of the
down hole cable conductors 118 to the electrical
conductor means 11.
There are preferably three similar dawn hole cable
conductors 118, although only one is referenced. The
cable 118 extends upwards from the down hole pump to
penetrate the connE~ctor 2:3, whet:e the cable 118 is
electrica:Lly and mc:~chanically connected to the ale
connector pin 116 _i.n a similar manner_ as described for
the electrical concxuctor means 11 and the female
connector socket 1~4.
A female boot 120, preferably comprising rubber, is
formed to surround -.he rigid tube .LS, the stand off 113
and the female connector socket 114 for electrically
isolating the condi.zcting portions from the outer sleeve
104. The female boot 120 preferably includes a
longitudinal passage :L20a and an arcuate grove 120b for
receiving a projecting end portion 122a including an
arcuate, annular r_i.b 122b of a male boot 122. The male
boot 122 i.s inserted into the female boot 120 and locked
as shown, where thE;~ projecting end portion 122a fills the
longitudir..al passaaa 12()a so that t:he arcuate, annular
rib 122b interfaces t:he arcuat:e groove :120b. The male
boot 122 also comprises rubber, and is formed to surround
the cable 118 and ttue male connectc>r pin 116 for
electrical isolation from the outer sleeve 1i~4. The male
and female boots 12~, 122 have outer surfaces 120c, 122c,
respectively, which
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WO 94125726 PCTIUS93l04032
29
are preferably formed to fill the outer sleeve 104.
The outer sleeve 104 is thus electrically isolated from
the conductive portions of the connector 23.
The cable 118 extends through and past the end of
the conductor extension 24 and through a bottom stop
124. The bottom stop 124 includes an opening or
counter bore 124a for terminating the conductor
extension 24. The conductor extension 24 fits
reasonably tight into the counter bore 124a to create a
l0 relatively rigid connection between the connector 23
and the conductor extension 24. This prevents bending
which could otherwise cut the insulation of the cable
118. The cable 118 extends past the bottom stop 124 to
the male connector pin 116 within the connector 23.
The bottom stop 124 includes a threaded hole 124b for
receiving a threaded set screw 126. The outer sleeve
104 includes a lower hole 104b aligning with the
threaded hole 124b for receiving the screw 126. In
this manner, the screw 126 fastens the outer sleeve 104
to the bottom stop 124.
Although not clearly shown, a bushing is
preferably inserted into the counter bore 124a to a
position between the cable 118 and the bottom stop 124.
In practice, there are about 200 different sizes of
down hole cable conductors 118, although the bottom
stop 124 is preferably only one size. For convenience,
therefore, field personnel carry a plurality of ring-
shaped bushings having a fixed external diameter to fit
within the bottom stop 124, and different incremental
sizes of the internal diameter to match the size of the
cable 118. After insertion of the proper sized
bushing, the screw 126 is tightened against the bushing
to complete the connection.
In operation, the formation exerts a significant
amount of pressure which may be applied against the
CA 02246400 1998-10-06
WO 94!25726 PCT/US93104032
barrier or wellhead WH. The fluid within the well bare
forms a fluid column which rises and falls depending
upon the formation pressure and whether the down hole
pump is turned on or off. When the pump is turned off,
5 the fluid column typically rises causing a high
pressure area 130 surrounding the connector 23. This
high pressure can reach the pressure rating of the
wellhead WH, which could be 5,000 to 10,000 psi or
more. In contrast, the surrounding air 132 outside the
10 wellhead WH is at relatively low pressure.
Due to the high pressure, the male and female
boots 120, 122 typically become saturated With well
fluids. When the down hole pump is turned on, it pumps
fluid up the production tubing 162 typically causing
15 the fluid column to fall, so that the area 130 becomes
relatively depressurized. The fluid impregnated male
and female boots 120, 122 can not release the fluid
fast enough, so that a pressure differential exists
between the inside of the connector 23 and the
20 surrounding depretsurized area 130. The rubber of the
male and female boots 120, 122 tends to expand to force
the male and female boots 120, 122 apart, which would
otherwise separate the male connector pin 116 from the
female connector socket 114. Due to the top stop 102,
25 the bottom stop 124 and the outer sleeve 104, the
rubber boots 120, 122 are confined and can not readily
expand sa that the connector 23 remains intact.
Further, since the top fitting 100 is fixedly attached
to the rigid tube 15 and attached to or integrally
30 formed with the top stop 102, the rigid tube 15 is not
forced out of the connector 23, so that the cannector
23 remains intact.
Referring now to Figure 11, a partial sectional
view of the connector 23 is shown illustrating the
stand off 112. As shown, the stand off 112 preferably
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W,O 94125726 FCTIUS93104032
31
has a larger diameter than the female connector socket
114 for proper placement of the rubber female boot 120.
When the dawn hole pump is turned off, any fluid
existing in the high pressure area 130 seeps inside the
connector 23 and impregnates the mile and female boots
120, 122. A low pressure area exists inside the rigid
tube 15 relative to the area 130 and the boots 120,
122. The pressurized fluid impregnated rubber of the
boots 120, 122 tends to expand within the connector 23,
l0 thereby forming a tighter seal on all passages through
which well fluids might flow. It :is undesirable f or
fluid to escape through the rigid tube 15 via the
electrical conductive means 1l comprising the conductor
element portion 11' and the insulation 113.
The stand off 112 preferably fonaed of a
reenforced, high voltage, high strength insulator
material. The material is preferably a glass-filled
material, such as Westinghouse G-10, for example. The
stand off 112 has a hole 112a with a diameter for
2o surrounding the insulation 113 of the electrical
conductive means 11, and a second, larger diameter hole
112b on one end extending part way into the stand off
112. The second hole 112b is carefully counter bored
to receive the rigid tube 15 to preferably create a
tight fit. The second hole 112b also forms an
extension lip 112c f or circumscribing the rigid tube
15, and a shoulder 112d engaging the lower end 110 of
the rigid tube 15. In spite of the high pressure, the
rubber of the female boot i20 may extend slightly
between the extension lip 112c and the rigid tube 15,
but will not penetrate all the way to the shoulder
112d. In fact, due to the pressure applied by the
surrounding rubber, and the low pressure within the
rigid tube 15, the lower end 110 of the rigid tube 15
is forced into the shoulder 112d of the
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WO 94125726 PCTlUS93104032
32
forming an effective fluid seal. The stand off 112 has
a relatively wide flat face at a lower end 112e
engaging the upper end 114a, which is also relatively
wide and flat, forming a fluid seal. The pressure also
forces the female connector socket. 114 against the
lower end 112e of the stand off 11.2. Thus, fluid will
not escape past the stand off 1I2, allowing for a
greater seal.
It is now appreciated that each of the connectors
23 for connecting the electrical conductor means 10,
11, 12 provides an effective seal preventing fluid from
escaping through the rigid tubes 15, and remain intact
during pressurization and depressurization occurrences
in the well. The top and bottom stops 102, 124
attached to the outer sleeve 104 confines the rubber
boots 120, 122 and prevents them from expanding. The
stand off 112 includes a shoulder 1124 formed around
the rigid tube 15 to prevent a fluid leak.
Time varying current through a conductive wire
typically generates a magnetic field circumscribing the
wire. The barrier comprising the tubing hanger 8 and
flange 16 typically comprise ferromagnetic materials to
achieve the required strength without excessive
expense. The varying current through the electrical
conductor means 10, 1l, 12 would typically induce
electrical eddy currents in the tubing hanger 8 and the
flange 16, which is undesirable because the electrical
eddy currents cause a significant loss of energy due to
heating of the wellhead WH. To reduce the electrical
eddy currents, multiphase conductors are typically
grouped together in an attempt to cancel the induced
magnetic flux from each conductor with the opposing
magnetic flux from the other conductors. This grouping
of the conductors, however, increases the radial
CA 02246400 1998-10-06
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33
profile of the electrical penetration of the wellhead
WFi .
Referring now to Figure 12, a partial sectional
front view of the wellhead WH is shown, illustrating
the preferred positions of the electrical conduction
means 10, 11, 12 penetrating the wellhead WH. From
Figures 12 and 2, it is seen that the three rigid tubes
passing through the flange 16 and the tubing hanger
8 are preferably aligned side-by-side defining an arc
10 on a circle preferably having its center located at the
center of the wellhead WH, although the present
invention is not limited to this particular
configuration. Figure 3 shows that the profile of all
of the rigid tubes 15 are approximately that of a
15 single rigid tube 15, which is desirable since it
allows for a reduced radial profile of multiphase
conductors penetrating the wellhead WH. Nonetheless,
the present invention is not limited to any particular
configuration of the rigid tubes 15, so that a single
2o rigid tube 15 could be used or multiple rigid tubes 15
could be arranged in any fashion.
In spite of the fact that the electrical conductor
means l0, 11, 12 are operated at high voltage to reduce
amperage and consequent power losses, significant
amounts of sinusoidally varying current flows through
the electrical conductor means 10, 11, 12 in three
phase fashion. Without the present invention, high
current conductors arranged in this fashion would not
cancel the magnetic flux of the conductors, causing
heating of the wellhead WH and loss of energy. There
has been, however, no measurable rise in the
temperature of the wellhead WH, even with power demands
up to 200 horsepower or more using apparatus according
to the present invention. The rigid tubes 15 are
preferably formed of a non-ferromagnetic electrically
CA 02246400 1998-10-06
WO 9~I25726 PCTIUS93104032
34
conductive material, such as for example, stainless
steel, which effectively act as eddy current shunts, so
that electrical eddy currents only flow in the rigid
tubes 15. Since the currents flowing in the rigid
tubes 15 do not produce any significant heat, the
wellhead WH does not absorb energy nor does it generate
heat. Thus, the use of the non-ferromagnetic rigid
tube 15 saves energy and eliminates undesirable heating
of the wellhead WH.
l0 Referring now to Figure 13" a partial sectional
view of the rigid seal means 2o is shown for sealably
securing the rigid tube 15 to the barrier of the
wellhead WH. The conduit portian 25 is preferably
connected to a ferrule-type fitting 140, such as a
Swagelok~ or the like, used to connect the conduit
portion 25 to the wellhead WH and to the rigid tubes
15. The ferrule-type fitting 140 comprises a body
fitting 142 having a threaded portion 142a for
interfacing a threaded hole 16a of the tubing spool 16,
thus providing a metal to metal explosion-proof
connection. The body fitting 142 slides over the rigid
tube 15 and is screwed into the threaded hole 16a. The
body fitting 142 has an upper threaded projecting
member 142b having a conical counter bored upper end
142c creating a gap between the threaded projecting
member 142b and the rigid tube 15.
A ferrule 144, preferably comprising a ring-shaped
conical bushing, has a center hole for fitting around
the rigid tube 15 to rest on top of the body fitting
142. The cross-section of the ferrule 144 is
preferably wedged-shaped, having a wide flat portion
144b at one end, and an opposing narrow end 144a
fitting into the gap between the rigid tube 15 and the
body fitting 142. The ferrule 144 preferably comprises
a hard moldable or machinable plastic type material,
CA 02246400 1998-10-06
WO 94125726 PCTIUS93J04032
and more preferably comprises a polyimide resin, such
as Vespel~ by Dupont Co., which has some flexibility to
retain its original shape after being deformed. Other
heat resistant polymers or moldable powders could be
5 used. Also, polystheretherketones (PEEK), such as, for
example, XYTREX~ series 450 by E.G.C., Corp., could be
molded or machined to form an appropriate ferrule 144.
A nut fitting 146 preferably has a threaded opening
146a for interfacing the threaded projecting member
10 142b. The nut fitting 146 has an upper opening 146b
for slidably fitting around the rigid tube 15. The
upper opening 146b is narrower than the threaded
opening 146a, forming an inner shoulder 146c, for
contacting or intsrfacing with the flat portion 144b of
15 the ferrule 144.
Thus, when the nut fitting 146 is screwed onto the
body fitting 142 and over the ferrule 144, the shoulder
146c presses against the ferrule 144, wedging the
ferrule 144 further into the gap. Due to the cross-
20 sectional wedge shape of the ferrule 144, it slides
against the counter bored upper end 142c, deforming to
press against the rigid tube 15. The ferrule 144 is
preferably deformed slightly as the nut fitting 146 is
tightened, causing a slight deformation or crimp 148 in
25 the rigid tube 15. The ferrule 144 thus preferably
allows a tight connection between the body and nut
fittings 142, 146. However, the ferrule 144 is made of
a softer material than the material of the rigid tube
15, so that the ferrule 144 does not "bite" into the
3o rigid tube 15. The czimp 148 in the rigid tube 15
pinches or chokes the electrical conductor means Z1 to
form a fluid seal f or preventing any fluid from leaking
from the high pressure area 13o inside the wellhead WH
through the rigid tube 15.
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When the nut and body fittings 142, 146 are
subsequently removed, the ferrule 144 retains its
original shape and can thus be easily removed from the
rigid tube 15. In prior designs, a metal ferrule was
used, which permanently bit and clamped to the rigid
tube 15 when the fitting was screwed together. When
the well was pulled, the metal ferrule had to be sawed
off or otherwise removed, thereby destroying the rigid
tube 15. The ferrule 144 according to the present
l0 invention, on the other hand, allows easy removal when
the well is pulled. Recall that a similar rigid seal
means 20' is provided on the opposite end of the tubing
hanger 8, forming a seal on either end of the wellhead
WH. As shown in Fig. 12, however, the lower rigid seal
means preferably includes a standard two-piece metal
ferrule to lock the rigid tube 15 in place, preventing
axial movement. A ring-shaped ferrule 21a is forced
against a conical shaped ferrule 21b to form a metal to
metal contact as known to those skilled in the art.
The upper rigid seal means 20 using the single ferrule
144 does not necessarily function as an axial stop.
Referring now to Figure 14, a partial sectional
view is shown of a protective cover or sheath,
otherwise referred to as the triskelion 150, which
protects and separates the individual~conductors and
also covers the end of the insulation of the down hole
cable conductors 118. The triskelion 150 is preferably
formed from a non-ferromagnetic electrically conductive
material, such as nickel-plated brass or stainless
steel, for example, although other similar materials
may be used. As described previously, three down hole
cable conductors 118 are extended within corresponding
rigid tube means forming conductor extensions 24. The
conductor extension 24 f its relatively snugly around
the down hole cable conductors 11B forming a relatively
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small annular clearance to prevent excessive expansion
of the insulation of the down hole cable conductors 118
during depressuritation. The upper ends of the
conductor extensions 24 are terminated at the counter
bores I24a as described previously.
The conductor extensions 24 are separated near the
top of the triskelion 150, but are integrally formed at
a mid-point 152 with a single, larger protective
sheathing 154, so that the down hole cable conductors
118 extend into the sheathing 154. The down hole cable
conductors 118 are grouped together within the
sheathing 154 forming the 3-wire.cable 155 bound by
protective armor 156, which preferably comprises
corrugated, steel armor surrounding the down hole cable
conductors 118. The 3-wire cable 155 and the
protective armor 1~6 extends all the way down the bore
hole to protect the down hole cable conductors 118.
The sheathing 154 is preferably flared below the mid
point 152 at a location 158, to increase the diameter
of the sheathing 154 to cover the grouped down hole
cable conductors 118 and the protective cover 156. The
triskelion 150, therefore, covers the end of the cable
insulation of the cable 118 and separates the
individual down hole cable conductors 118.
It is known that the insulation surrounding the
cable conductors 118 saturates with fluid, so that the
insulation tends to expand and contract during
compression and decompression when the down hole pump
is turned on and off. In this manner, the triskelion
150 prevents damage of the conductors and surrounding
insulation of the down hole cable conductors 118, by
preventing the insulation from expanding after
decompression. Such expansion could destroy the
insulation around the conductors, possibly causing an
electrical short. The triskelion 150 further provides
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a transition from the 3-wire cable 155 down hole
surrounded by the protective armour 156 to the three
single cable conductor extensions 24. The triskelion
150 is axially fixed in position by the clamp means 160
to provide axial column strength to the conductors to
maintain vertical elevation of the male connector pin
116 inside the female connector socket 114.
Figure 14A is a cross-sectional view of the
triskelion 150 looking along line 14A-14A of Figure 14.
Figures 15 and i5A illustrate an alternative triskelion
150', where the down hole cable conductors 118 are
preferably aligned side-by-side. Analogous parts are
indicated using identical reference numerals followed
by an apostrophe symbol ""'. One advantage of the
triskelion 150' over the triskelion 150 is that the
triskelion 150' has a narrower profile for flat cables.
Referring now to Figure 16, a top plan view of an
alternate form of splice fitting, referred to as the
splice fitting 200, is shown with a similar removable
2o cap or cover 202 (Fig. 17) removed. The splice fitting
200 and its corresponding cover 202 are similar and
used for similar purposes as the splice fitting 42 and
cover 43. It has been discovered that an appreciable
amount of water collects within the splice fittings 42
or 200 due to condensation or other means, so that it
is desirable to protect the electrical connection from
water. However, if the seal through the barrier of the
wellhead WH should fail for any reason, such that well
fluids travel from the well bore through the electrical
3o conductor means 10, 1l, 12 to the splice fitting 200,
it is desired to prevent the fluids from reaching and
penetrating the power electrical conductor means 10a,
lla and 12a. If this were to occur, there is an
increased likelihood that the well fluids could reach a
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non-hazardous area via the power electrical conductor
means 10a, 11a, 12a.
The electrical conductor means I0, 11, i2 enter
the splice fitting 200 from the wellhead WH into
openings 204 of breather boots 206. The splice fitting
200 includes one or more similar electrical connections
depending on the number of electrical conductor
connections required, where there are three connections
in the preferred embodiment. The conductor element
portions 10', 11' and 12' are exposed within the
openings 204, and are inserted through gas block seal
passages 208 and into corresponding passages 210 of
separate splice connectors 212. The splice connectors
212 preferably comprise an electrically conductive
material such as copper or the like. The breather
boots 206 include cavities 214 for placement of the
splice connectors 212. The power electrical conductor
means 10a, 11a, 12a enter the opposing or power side
end of the splice fitting 200 into power conductor
2o passages 216 of the breather boots 206. The power
conductor element portions 10a', 11a' and 12a' of the
power electrical conductor means 10a, 11a and 12a,
respectively, are exposed and inserted into
corresponding passages 218 on the opposite side of the
splice connectors 212.
Referring now to Fig. 17, a sectional side view of
the splice fitting 200 is shown with the cover 202
attached. Only the connection for the electrical
conductor means 10a and 10 is shown, it being
understood that the connections for the other
electrical conductor means 11a, 12a and 1l, 12 are made
in a similar manner. Two threaded holes 220 and
corresponding screws 222, preferably allen-type screws,
are provided f or securing the conductor element portion
10' to the splice connector 212. In a similar manner,
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two threaded holes 224 and corresponding screws 226,
preferably allen-type screws, are provided for securing
the power conductor element .portion 10a~ to the splice
connector 212.
5 The breather boot 206 preferably comprises rubber,
or any other suitable material far providing electrical
insulation and to seal the electrical connection from
penetration by water. The breather passage 204,
however, includes a breather passage 205 along the
10 electrical conductor means 10, which would otherwise
allow fluid communication within the breather boot 206.
Furthermore, the insulation 113 of the electrical
conductor means l0 does not extend into the opening 204
all the way to the gas block seal passage 208, leaving
15 a header space 228 between the insulation of the
electrical conductor means to and the gas block seal
passage 208. The purpose of the breather passage 205
and the gas block seal passage 208 will be described
below.
20 Referring now to Fig. 18, a sectional side view of
the splice fitting 200 is shown illustrating the
position of the splice fitting 200 to make the
electrical connection. The breather boot 206 is
preferably slid onto the electrical conductor means 10,
25 exposing the splice connector 212. Any suitable
instrument, such as an allen wrench or driver 230, may
be employed to secure the screws 222, 226 of the splice
connector 212 to complete the electrical connection.
The breather boot 206 is slid back into place as shown
30 in Figs. 16 and 17, and the breather passage 204, as
well as the header space 228, are filled with a
silicone compound or the like, to seal the connection
from water penetration. The silicone compound
preferably has a grease-like viscosity to protect
35 against water vapor. Furthermore, the silicone
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compound preferably has a relatively low viscosity for
silicone, but high temperature viscosity stability to
remain at a relatively low to medium viscosity at
temperatures of about 200°F. Also, the silicone
compound preferably has a high dielectric strength to
achieve good electrical insulation.
Under normal conditions, the silicone compound
remains in the header space 228 and the breather
passage 205 until the electrical connection is removed
or otherwise taken apart. However, if the seal within
the bore hole should fail, so that well fluids escape
through the electrical conductor mean 10 to the splice
fitting 200, down hole pressure is exerted to remove
the silicone compound from the header space 228 and the
breather passage 205. The silicone compound
functionally cooperates with the breather boot 206, so
that the silicone compound is displaced by well fluids
from the well via the electrical conductive means l0 at
a lower pressure than that required to penetrate the
gas block seal passage 208 to, and around the splice
connector 212, and to the power electrical conductor
means 10a within the breather boot 206. This allows
the well fluid to escape into the splice fitting 200.
As described for the splice fitting 42, there is no
gasket between the splice fitting 200 and the cover 202
to permit the discharge of well fluids to the
surrounding atmosphere. Thus, the well fluids are not
communicated to the power electrical conductor means
10a, which could otherwise communicate the well fluids
to a non-hazardous area.
Figure 19 is a more detailed partial cross-
sectional and reversed view of an electrical connection
within a breather boot 206.
Figs. 20A-20F are cross-sectional views of the
electrical connection of Fig. 19, looking along lines
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20A-20A, 20B-208, 20C-20C, 20D-20D, 20E-20E and 20F-
20F, respectively. Fig. 20A illustrates the breather
passage 205 more clearly. Fig. 20H illustrates the
header space 228. Fig. 20C illustrates that the gas
block seal passage 208 surrounds and seals the
electrical conductor portion 10'. Fig. 20D illustrates
the physical isolation between the power conductor
element portion 10a' and the conductor element portion
10' within the splice connector 212. Fig. 20E
illustrates the screws 226 screwed into the splice
connector 212 to secure the power conductor element
portion 10a'. In a similar manner, the screws 222 are
used to secure the conductor element portion 10' to the
splice connectors 212. Figure 20E illustrates the
power electrical conductor means 10a entering and
sealed by the breather boot 206. It is noted that the
power electrical conductor means 10a is preferably a
Underwriter's Laboratories (UZaj listed 5 RV stranded
wire with insulation 240 circumscribed by a jacket 242,
although it is not limited to any particular type of
conductor.
The foregoing disclosure and description of the
invention are illustrative and explanatory thereof, and
various changes in size, shape and materials as well as
in the details of the illustrated construction may be
made without departing from the spirit of the
invention.
