Note: Descriptions are shown in the official language in which they were submitted.
CA 02226530 1998-01-08
TITLE: FLUID LINE WITH INTEGRAL CONDUCTOR
INVENTOR: WILLIAM EDWARD AESCHBACHER, DAVID G. KORTE,
and LARRY V. DALRYMPLE
FIELD OF THE INVENTION
The field of this invention relates to control lines which can transmit
fluids to remote locations and, more particularly, control lines which can be
used in oil and gas operations, such as subsea, wherein it is also advanta-
geous to transmit electrical, optical, or any other signals to a remote point.
BACKGROUND OF THE INVENTION
In many applications in the oil and gas industry it is desirable to transmit
fluid pressure to a remote location for actuation of equipment, as well as to
run electrical or other types of conductors for either transmission of signals
or
power to or from the surface to a subsurface location or for other reasons.
Typically, a conduit which, if small and sufficiently flexible, can be
unrolled
from a roll is run along side the production tubing or otherwise into a
borehole.
If signals are to be sent from the wellbore to the surface electrically, a
sepa-
rate cable has been used, which many times is bundled to the exterior of the
control tubing such that the hydraulic signals pass through the control tubing
while the electrical, generally low-voltage signals, which record any number
of downhole well conditions or operate low-voltage equipment, use the
adjacent cable for transmission of such signals. It has also been attempted
in the past to run the electrical signal cable into and through a coiled
tubing
unit. In those instances, the signal cable is externally shielded to prevent
any
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signal interference from the surrounding tubing structure. One of the prob-
lems in this type of installation has been that the shielded cable would
develop
flaws or pinholes in its outer protective casing, which would then allow the
fluids to migrate into the cable, damaging the signal conductors therein.
Additionally, another problem encountered with such designs is that the
conductor cable running through the tubing could in many places orient itself
adjacent the tubing wall, particularly if the well was in any way deviated.
The
contact between the electrical cable and the tubing wall could cause two
problems. First, it could cause abrasion of the shield material against the
inside surface of the tubing wall, which ultimately would result in compromis-
ing the integrity of the covering for the conductors. This, as previously de-
scribed, could cause a breakdown in the ability to transmit signals through
the
conductors. Additionally, close proximity to the tubing wall also rendered the
internal cable vulnerable to damage from mechanical impacts on the tubing
in situations where the cable is located up against the inside tubing wall.
Such impacts could cause dents in the tubing wall, which would translate
directly to the cable damaging and perhaps severing the cable. Finally, and
to a lesser extent, close proximity to the inside wall of the tubing also
created
some potential risk of signal interference from the metallic tubing wall.
Space is routinely at a premium in oil and gas installations, particularly
in offshore applications. It is frequently desirable that the external control
tubing have a small diameter as possible, while, at the same time, it must
have the necessary rigidity and internal diameter to allow accommodation of
an intemal conductor. What is desirable and heretofore lacking in the known
equipment is a compact design where a conductor can be effectively isolated
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and located reasonably centrally to the tubing to minimize damage to
the cable from impacts to the tubing. Additionally, with the conductors
positioned within the tubing and their position retained away from the
tubing wall, the spaces around the conductor can be used to allow
fluid flow or, in the alternative, can be filled with a sealing material
which provides further durability to the assembly of conductors,
insulators/centralizers, and void sealant, all disposed within the
tubing.
SUMMARY OF THE INVENTION
Conductors are placed in insulator which acts as a
spacer/centralizer for the conductors, which are in turn mounted
within tubing. The void spaces between the insulator and the tubing
inside wall can be filled with a sealing material. Alternatively, the
voids around the substantially centralized conductors can be used as
flow channels for the transmission of fluid pressure to a remote
location, such as downhole. The conductors are protected because
they are kept away from the tubing wall and can be further protected
by the addition of the sealing material.
Accordingly, in one aspect of the present invention there is
provided an assembly for power or signal transmission between the
surface of a well and a downhole component, comprising:
a continuous metallic cover tube made from at least one sheet
rolled into a tube to create a long seam and being of a sufficient
length to reach, at one end, from a surface of the well to, at another
end, a downhole component without any intermediate connections;
at least one conductor extending continuously through said
cover tube from said surface to said downhole component; and
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a nonmetallic spacer comprising at least one extending
member extending from a core which surrounds said at least one
conductor to space said at least one conductor;
wherein said cover tube is formed by rolling said sheet over
said at least one conductor to create said seam offset from said at
least one extending member so that a weld of said seam is not
damaged by said at least one extending member, as said cover tube
is formed over said spacer.
DETAILED DESCRIPTION OF THE DRAWINGS
An embodiment of the present invention will now be described
more fully with reference to the accompanying drawings in which:
Figure 1 is a sectional view of the tubing, showing the
conductor therein with a filling in between.
Figure 2 is the view of Figure 1 without the filling.
Figure 3 is the view of Figure 2, with a schematic
representation of a combination of a hydraulic and electrical element
showing a typical application of the apparatus of the present
invention.
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Figure 4 is a section showing the wrap of insulation between the con-
ductor and the shaped insulator.
Figure 5 is another section illustrating the notch feature on the fins of
the shaped insulator.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Figure 1 illustrates the apparatus A of the present invention. It com-
prises an external housing or tube 10 which can be made in a variety of
corrosion-resistant materials, including metals such as 316 Stainless Steel,
Inconel, as well as rigid plastic materials. Inside the housing 10 is a spacer
12. Inside the spacer 12 is conductor or conductors 14. Conductors 14 can
be one or more strands which collectively can transmit a signal. A strand or
groups of strands can be separately bundled and shielded before being
mounted to the spacer 12. In this manner, the tubing 10 carries a plurality of
potential signal or power transmission avenues within the same spacer 12.
In the preferred embodiment, the spacer 12 has a plurality of radial
projections
16, which are spaced at 120 intervals, and which extend radially from a hub
17, to create three parallel flowpaths 18, 20, and 22. The flowpaths can be
used as such or can in the alternative, as shown in Figure 1, be filled with
an
epoxy 24. By adding the epoxy 24, additional protection for the conductors
14 is provided. The radially extending members 16 also help to centralize the
conductors 14 and keep them away from the outer housing 10. By centraliz-
ing the conductors 14, they are less prone to be damaged. Furthermore, the
control signals passing therethrough are less likely to suffer interference
from
adjacent metal components, such as housing 10. When the assembly is put
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together, as shown in Figure 1, with the flowpaths 18, 20, and 22 further
filled
with epoxy, the assembly becomes more durable in withstanding mechanical
shocks but yet remains sufficiently flexible to allow coiling of the housing
10
onto a roll (not shown) for easy storage and dispensing when needed. While
the preferred embodiment indicates the conductors to be centralized, an offset
location, but removed from the housing or tubing 10, is still within the
purview
of the invention. While three radial extensions 16 are shown in the preferred
embodiment, different configurations can be employed to accomplish the
positioning feature of getting the conductors 14 away from the tubing wall 10.
For example, a fewer or greater number of radially extending fins, such as 16,
can be used. Different geometric shapes that extend from a hub that encir-
cles the conductors 14 can be used, such as a single helix or a multiple
helix,
as long as their spacing is not so great or radial extension too small so as
to
allow the hub that surrounds the conductors to engage the inner wall of the
housing or tubing 10. The conductors 14 can be further wrapped with a
signal-insulating material prior to being inserted into the spacer 12. The
insulating material is illustratively shown in Figure 4 as item 32. As shown
in
Figure 4, it wraps around the conductor 14 such that the hub 17 is applied
over the signal-insulating material 32. The insulation 32 can be in a single
or
multiple layers applied to the conductor 14 before application of the hub 17
and the extending member 16. The insulation 32 can be made from a variety
of materials, including but not limited to varnish composites, bonded or
unbonded tapes applied either longitudinally or spirally with overlap,
sintered
powders or extruded compounds. The insulation 32 can also be extruded
over the conductors 14. Co-extrusion of the insulation 32 with the hub 17 and
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extending member 16 can be accomplished if the appropriate materials are
selected. Altemafively, mufti-pass extrusion techniques can be used. Layer-
to-layer bonding may be desirable but not required for the composite con-
struction; thus, the insulation 32 can be selectively bonded to the conductors
14 or the hub 17, depending on the application. Dissimilar materials can be
used as between the hub 17 and the insulator 32. The insulator 32 can be
made from polyimide tape, with the hub 17 made of ETFE or PVDF (polyvinyl
difluoride). The addition of the insulator 32 enhances the electrical
integrity
of the conductors 14, particularly if the outer tube 10 is damaged in any way.
The filler material 24 also aids the retention of electrical integrity to the
con-
ductor 14. The insulating material 32 can also include high-temperature
compounds which contain fluoride compounds and silicones or, in the alter-
native, mineral insulation. Use of these materials, in combination with the
epoxy 24 in the flowpaths 18, 20, and 22, adds crush resistance to minimize
insulation compromise. Additionally, the presence of the insulating layer 32
facilitates the making of end connections. When the hub 17 and extending
member 16 are bent at a termination.to deliberately expose the conductor 14
for making connections, the presence of the insulating layer 32 promotes
cracking of the hub 17 in reaction to bending so that a portion of the hub 17
and the extending member 16 can be removed easily from the end of the
conductor 14. The addition of the insulating layer 32 minimizes the risk of
damaging the conductors 14 in the bending process that is used to remove
the last segment of the hub 17 from an end of the finished assembly to facili-
tate the making of a connection. Without the insulating layer 32, the degree
of bending that may be necessary to break the hub 17 to get it off of the
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conductor 14 may also result in damage to the conductors 14, which would be
undesirable. The insulating layer 32 remains intact after the hub 17 is scored
and snapped off.
In the preferred embodiment, the spacer assembly 12 is extruded onto
the insulator 32 which is mounted over conductors 14 while the tubing, which
originally comes in a flat sheet, is rolled into a tubing form and the seam is
welded around the spacer 12. The assembly is so oriented so that the seam
which forms the tubing 10 is not aligned with any one of the radially
extending
members 16 to avoid any damage to them during the welding or brazing
process. In this manner, a continuous-length segment of the apparatus A
can be assembled and rolled onto a reel as it is put together. The length can
vary depending on the distances from the surface to the downhole compo-
nents in a typical application. The connections are at e'ither end of the
contin-
uous length, with one connection at the downhole equipment and the other at
the surface.
Figure 3 illustrates the application of the apparatus A in a schematic
manner to allow for operation of a hydraulically actuated component, as well
as at least one electrically actuated component. The hydraulically actuated
component is schematically illustrated as a valve 26, but could in an actual
application could be any one of a number of different components. The
electrical segment is illustrated as box 28. In a particular application, the
hydraulically actuated component can be a downhole valve which is operated
by a shifting sleeve or some other hydraulically-actuated operator, and the
box 28 can be a sensor or sensors which can respond to indicate whether a
shaft has tumed, or a sleeve has shifted, or the like. Separate signal- carry-
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ing capacity can be provided within hub 17 if conductors are separately
bundled and insulated as a group prior to having hub 17 extruded over them.
In this way, multiple signal or error transmission functions can be simulta-
neously serviced.
Many potential applications are possible for the apparatus A of the
present invention. For example, the apparatus A can be used to operate a
solonoid-operated safety valve with hydraulic communication capability for an
insert valve. The apparatus A can also be used for proximity indicators or
position sensors to indicate if a valve is full open or full closed. An
electrically
operated mechanism to lock a flapper on a subsurface safety valve in the
open position can be operated with the apparatus A of the present invention.
Other applications include: (1) downhole control line pump and reservoir to
eliminate hydrostatic head on deep-set valves, (2) a solenoid to operate the
flapper on a subsurface safety valve without stroking the flow tube, (3) an
electrical assist mechanism for stuck flow tubes, (4) electrical communication
for wireline tools, (5) electrical/hydraulic shutde valve operation for ultra
deep-
set applications, (6) electrically operated equalizing devices, (7)
electrically
controlled adjustable orifices or chokes, (8) flowing pressure and temperature
transducers at subsurface safety valves, (9) electrically operated communica-
tion features for insert valves, (10) control line pressure transducers,
(11) backup electrical actuators in case of hydraulic failure, (12) pH sensors
at a valve to monitor control line or tubing fluids, (13) load cell
communication
to determine valve position, packing element, or a slip load, (14) constant
power source for an electromagnetic valve, (15) proximity sensors for subsea
actuators, (16) electrically operated lock-open devices for a subsea actuator,
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(17) electrically operated lock-close devices for a subsea actuator, (18)
electrical permanent lock-open device for subsurface safety valves, (19)
electrical override for subsea actuator to open gate valve, and (20)
electrical
release mechanism for subsea actuator to release connection between the
actuator and the valve stem during removal. These are some of the applica-
tions, although many others can be employed without departing from the spirit
of the invention.
To the extent the passages 18,20, and 22 can be isolated from each
other separate pressure signals in each path can be transmitted to a remote
point such as subsea.
In the preferred embodiment, the spacer is made from extruded
TEFZELO, which is a PTFE fluorocarbon material available from E.I. Dupont.
In the preferred embodiment, if encapsulation of the spacer 12 is desired, an
epoxy resin, which is a mixture of a plasticizer, a resin, and a curing agent,
provides an effective gas/fluid block if the outer jacket 10 is compromised.
Other materials can be used in lieu of the epoxy resin if they are pumpable
and can provide the shock protection and gas/fluid blocking protection for the
conductor 14. An alternative embodiment can be the provision of the outer
jacket 10 in a material called SANTOPREMEO, which is available from
Monsanto Company, St. Louis, Missouri.
One of the advantages of the construction of the apparatus A is that the
outer jacket 10 can be stripped off, as required, without damaging the inner
conductor 14. In the preferred embodiment, a bundle of 18 gauge copper
conductor forms the main conductor 14 running through the spacer 12. The
use of the epoxy material, which acts as an incompressible fluid,
significantly
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increases the compressive and collapse strength up to four times that of an
unfilled tube. Under compression, the epoxy material acts as a fluid cushion
and provides additional protection that is now not available with other types
of downhole cable. The exterior housing or jacket 10 also shields against
electrical noise, while the entire assembly is economical and permits multiple
reruns. The filler totally fills the flowpaths 18, 20, and 22, but partial
filling is
also within the scope of the invention.
In the preferred embodiment, the housing 10 has a seam which is
electron-beam welded. The spoke-like profile of the preferred spacer 12
allows the insulation of the conductors 14 to be oriented during the welding
process to put a seam between the two spokes, thereby reducing the possi-
bility of contaminating the well with insulation material and reducing the
heat
transfer from the insulation to the newly formed weld. The method of assem-
bly thus improves the quality of the finished product. With the epoxy resin
filler, or other equivalent materials, the compressive strength of up to
30,000
psi is obtained.
The foregoing disclosure and description of the invention are illustrative
and explanatory thereof, and various changes in the size, shape and materi-
als, as well as in the details of the illustrated construction, may be made
without departing from the spirit of the invention.
bakerlpatents\474 elec. condudor (328).wpd ss
