Note: Descriptions are shown in the official language in which they were submitted.
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Cable Clamps
The present invention relates to cable clamps for use in a wellbore.
Cables are often used in a downhole environment to conduct
electricity, in order to power and control downhole tools and to transmit
signals from downhole sensors. When installed with a drill string, the cable
is ~ often closely secured to the exterior of the tubing so that it is not
damaged by the sides of the wellbore as the drill string is lowered. Other
types of cable (conduit), such as hydraulic cable and fibre optic cable, may
also be disposed in a wellbore.
A lmown cable clamp comprises two clamp members separated by a
bridging section. Each clamp member has two arcuate sections joined by a
pivot. The arcuate sections can be opened to accommodate a tubing section
with a cable positioned along the pipe section's length, and then closed
around the pipe section to encircle it, the free ends of the arcuate sections
being joined together by a screw located on the free end of one arcuate
section which co-operates with a threaded hole located on the free end of
the other arcuate section.
Cable clamps must often be applied to the pipe section and cable in
difficult conditions, and it is also important that each clamp can be applied
quickly and reliably. It can be difficult to reliably secure the locking
mechanism of lmown clamps, and the cable clamp may be damaged when
the user attempts to attach it, so that the cable clamp has to be returned for
r econditioning.
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The object of the present invention is to provide a cable clamp which
is convenient to operate. Other advantages will also become clear upon
reading the description.
According to the present invention, there is provided a cable clamp
device for use in a well bore to secure cables to pipes and the like,
including
a relatively flexible fastening member, and a retaining means that accepts
and retains the fastening member, the cable clamp device including a cable
restraining means capable of accepting and constraining at least one cable
as the cable clamp device is attached to a pipe.
Preferably the cable restraining means includes flexible resilient
parts that deform to accept the cable and thereafter hold it in position.
. According to another aspect of the present invention there is
provided a cable clamp device for use in a well bore, including a clamp
member comprising a first arm pivotally joined to a second arm, and a
fastening means disposed at the end of one or both arms that acts to fasten
the arms tightly around a tube, the first arm and the second arm including
opposing concave surfaces in proximity to the point the arms are pivotally
joined, Sllch that a cable may be secured between and directly abutting both
these opposing surfaces as the arms are folded around a pipe section.
The flexible securement member may comprise a loop of wire that is
secured to an anchor hoolc. Alternatively, the flexible securement member
may comprise a strip, which engages the first arm and is constrained by a
ratchet and pawl mechanism.
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According to another aspect of the present invention, a cable clamp
device for use in a well bore, including a clamp member comprising a first
arm pivotally joined to a second arm, and a fastening means disposed at the
end of one or both anus that acts to fasten the arms tightly around a tube,
the first arm and the second arm including opposing concave surfaces in
proximity to the point the arms are pivotally j oined, such that a cable may
be secured between and directly abutting both these opposing surfaces as
the arms are folded around a pipe section.
Preferably the second end is also adapted to fit in series with a
tubing section.
The flexible strapping member may be integral and non integral with
the cable clamp. Preferably the clamping member is able to accommodate
different cable diameters. The clamping member may be reusable,
particularly when used with the wire loop fastener; alternatively, it may be
disposable, particularly when used with a tie wrap or similar fastener. The
retaining strap can be wrapped over the cable or under the cable
Additional items can be distributed along the strap to perform
different functions such as centralising the tubing etc. and allow the same
strap to be used with centralisers on any size tubing.
Cable clamps according to the present invention will now be
described, by way of example, and with reference to- the drawings, of
which;
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Figures 1 to 5 are cross sections of the clamp member securing a cable to a
pipe section;
z Figure 6 is a cross section of another embodiment of a clamp member;
Fi'~ure 7 is a cross section of is the clamp member of figure 6 securing a
cable to a pipe section;
Figure 8 is a cross section of is another embodiment of a clamp member;
Figure 9 is a cross section of is the clamp member of figure 8 securing a
cable to a pipe section;
Figure 10 is a cross section of is another embodiment of a clamp member;
Figure 11 is a cross section of the clamp member of figure 10 securing a
cable to a pipe section;
Figure 12 is a cross section of another embodiment of a clamp member
securing a cable to a pipe section;
Figure 13 is a cross section of another embodiment of a clamp member;
Figures 14, 15 and 16 are cross sections showing a similar embodiment to
that in figure 13 in use.
Figure 17 is a cross section of another embodiment a clamp member;
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Figure 18 is a side elevation of similar embodiment of a clamp member.;
Figure 19 is a longiW dinal sectional view of another embodiment of the
clamp member;
Figure 20 is a view of the underside of another embodiment of the cable
clamp device.
Figure 21 is a sectional view of the clamp member of Figure 19 in use.
Figure 22 is a sectional view of another embodiment in use.
Figure 23 is a longitudinal sectional view of another embodiment of the
clamp member;
Figures 24 and 25 show sectional views of the clamp member of Figure 23
m use.
Referring to figure l, the cable clamp comprises a first arcuate ann
24, joined to a second arcuate arm 12 by a hinge 18. A locking arm 13 is
pivotally joined by a hinge 15 to the second arcuate arm 12. A flexible
wire loop is attached to the locking arm 13 by means of the apertzues 23
present in the loclcing arm. The first and second arcuate arms have a
cmvattue approximately the same as the curvaW re of the W bing they are
intended to attach to.
To clamp the cable to the pipe section (or other similar downhole
W bular stnictLUe), the first arcuate arm is placed upon the exterior of a
pipe
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section 20, subtended nearly 180° of the pipe pipe's circumference. The
first arcuate arm includes a slightly curved surface 22 against which a cable
30 is placed. The curved surface 22 has approximately the same curvattue
as the largest cable that is intended to be clamped. The second arcuate ann
12 includes a U-shaped cut out portion 25. The second arcuate arm 12 is
pivoted about the hinge 18 so that the U-shaped cut out portion 25 captures
the cable 30, as shown in figure 2.
Referring to figure 3, when the second arcuate ann 12 abuts the
exterior of the pipe section, the cable is frilly constrained by the U-shaped
cut Ollt p01't1011 25 and the curved surface 25 of the first arcuate arm 24,
in a
position slightly above the tubing exterior. Alternatively, the cable 30 may
be constrained by these two surfaces against the exterior of the pipe section.
Referring to figure 4, the wire loop is bent around the exterior of the
pipe section and hooked over the anchor point 24 on the first arcuate ann.
The locking arm is then drawn round its hinge 15 until it lies against the
second arcuate arm (the locking ann having a channel section to
accommodate the second arcuate arm). The wire loop is drawn taught by
the locking arm, so that the clamp member is tightly secured to the pipe
section. As tile locking arm 13 pivots around the hinge 15, the surface of
the locking am co-operates with the surface of the second arcuate arm in a
caromed manner, so that the locking ann is biased towards either extending
away from the second arcuate arm in a substantially co-axial direction as
shown in figure 2, or lying against the second arcuate ann as shown in
figures 4 and 5. The loclcing arm therefore cannot disengage without
deliberate manipulation; further, as the locking ann over-centres, the force
exerted by the wire loop under tension acts to keep the loclcing arm closed.
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When it is necessary to release the cable, the tension arm can be
lifted, overcoming the biasing, and so de-tensioning the loop wire. The
wire loop can then be disengaged from the first arm and the clamp member
and cable released.
Referring to figure 6, another embodiment of the clamp member 40
comprises first and second arms 42, 43 joined by a flexible hinge 47. Each
arm features a gently concave surface 48 of similar cmvatZUe to the exterior
of the pipe section, and a more highly curved surface 49 having a similar
curvaW re to the cable intended to be clamped. A standard tie wrap 46
comprises a strip of material having head at one. end through which the
other end can be introduced to form a loop, the head having a pawl and the
strap having a toothed surface. Referring to figure 6, to clamp a cable to a
pipe section, the arms 42, 43 of the clamp member are folded together with
the cable 30 held against one of the curved surface's 49, until both curved ,
surfaces grip the cable. The surfaces 48 of the clamp member are placed ,
against the exterior of the pipe section, and the tie wrap is placed over v:'.
channel members (not here visible) extending from each arm the clamp
member (and threaded beneath the cable) and rests against the exterior of
the pipe section. The free end of the tie wrap is introduced to the head and
the strap is pulled through until the tie wrap is tight and both arms of the
clamp member are secured against the pipe section, thus securing the cable
in position. The channel for the tie wrap may be internal to the clamp
member.
Referring to figure 8, one of the ax-ms 52 of the clamp member 50
includes a strap extending from it. Cable is inserted in the clamp member
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as in previous examples, and the strap is passed through a channel in the
anrl 53, before being threaded under the cable and inserted in a channel in
the arm 52, as shown in figure 9. The end of the strap, which is toothed in
the same manner as the tie wrap described above; ~co-operates with a pawl
55 in the ann 52 to tightly secure the clamp member to the pipe section and
the cable in the clamp member.
The clamp member in this example is preferably manufactured from
a plastics material that is sufficiently deformable that the two arms can be
integrally moulded, but flex at the thin hinge point between the arms.
When it is necessary to release the cable from the drill string, the tie
wrap is severed by sufficiently strong cutters, thereby releasing the clamp
member and the cable. After pulling the cut end of the tie wrap past the
pawl, the clamp member may be re-used. Alternatively, tile clamp member
may be discarded, and it can conveniently be manufactured cheaply from
plastic, and the flexible hinge described in this embodiment may not be
suitable for repeated use.
Referring to figure 10, the clamp member 60 may have internal
channels (not shown) and a pawl 60 located near the outer surfaces 67, 68
~,~
Of the ar111S 63, 64 Of C1a111p 1ne111ber 60. 111 LlSe, the strip 66 extending
from
the arm 53 is introduced into a channel in alnl 63, and continue through
clamp member into ann 62, co-operating with pawl 65 to secure the cable
to the pipe section.
Referring to figure 12, centralising members 47, 48, 49 may be
attached to the pipe section in the vicinity of the clamp member, the
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centralising members being secured by the tie wrap. The centralising
members together with the clamp member assist in pipe stand off from the
sell bore 100, and distribute support for the tie wrap. It will be seen that
the
clamp member itself can offer good protection from damage of the cable
against the casing or wellbore surface. Conveniently, the tie wrap is
threaded through the centralisers. In this way, differently sized centralisers
may be attached to the clamping member, and so one size of clamping
member may be used with various sized centralisers depending upon the
diameter of the casing, and the diameter of the pipe section (the
accommodation of different pipe section diameters is discussed below).
Referring to figure 13, the arms 75, 73 of the clamp member 70 may
feature notches 76 on the exterior surfaces. This improves the flexibility of
the arms, so that the curvature of the surfaces 78, 79 which abuts the pipe
section may be varied when the clamp member is folded as shown in figure
14, and so the clamp member 70 may be used to secure cables 30 to pipe
sections 20, 18 having different radius, as shown in figures 15 and 16. The
tie wrap can of course be tightened to a wide variety of diameters.
Referring again to figure 13, the surfaces 74, 75 for engaging the
cable may feaW re flexible ribs 71. These ribs will secure cables of
relatively small section, but deform to accommodate larger cables. Notches
77 could be included in the clamp member to further improve flexibility.
It will be appreciated that the notches 76 which allow variation in
pipe diameter, and the ribs which allow variation in cable diameter, may be
implemented independently.
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Referring to figure 17, the tie wrap 91 may be attached to the second
arias 92 by inserting a shaped head 94 of the into a co-operating shaped
cavity 96 of the second arm 92. Referring also to figure 18, the apertiue
could be open at one side of the clamping member, to allow the head to be
slid into the shaped cavity 96. The tie wrap is then introduced into an
apert~.ire 98 in the first ann 93, and pushed along a channel which extends
through the first arm and the second ann to emerge at a longitudinal mouth
95. The tie wrap has saw-tooth shaped surface, the teeth of which engage a
indentation 96 in a ratchet fashion to allow the tie wrap to be easily pulled
tight but not to be slackened. When the tie wrap has been tightened
sufficiently to secure the cable to the pipe section, the excess tie wrap is
cut,
the mouth 95 ensuring that the knife used does not slid along the surface of
the second arm 92.
Ideally, as for all the embodiments described above, the first and
second arms encompass only a small portion of the pipe section, typically
between 45° and 270°; however, the principles of securement
described
above could be where the arms encompass or somewhat exceed and overlap
the entire circumference of the pipe section.
Cable may be attached to a tube by a number of individual cable
clamps each comprising a single clamp member. The cable clamp could
also be formed from two clamp members joined by one or more
longitudinal bridging members, or the cable clamp may be extended so that
it ,forms a partial W be, so that the cable clamp offers greater mechanical
protection to the cable in that region.
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In all the embodiments described, the cable has been captured by the
folding motion of the pivoted arms of the cable member, and held
somewhat from the pipe section. Although this configuration is
advantageous, cable could alternatively or additionally also be held a
concave surface present on a single arm, pressed directly against the pipe
section. Further, because the arms do not have to encompass the entire
circumference of the pipe section, they need not be pivotally joined at all,
but simply partially accommodate the cable in a concavity and press it to
the pipe section.
Referring to figures 19-25, there is shown a flat strap construction
for a cable clamp in which the strap receiving portion 120 of the clamp has
an angled part 100 having an appropriately angled surface to allow it come
into contact with and bear against a tube 101. A number of cable dividers
103 are provided on the strip close to the strap receiving portion 120.
Different cable combinations and types can be held by changing the number
and location of cable dividers 103; it will be noted that the embodiments
shown in figures 19, 21 and 23 show four such dividers (figure 21
illustrating a clamp securing 11 ~ 11 instrumentation lines 130 and 1/4 inch
control lines 132), whilst those in figures 20, 22, 24 and 25 show three
dividers (figure 22 illustrating a clamp securing a 23 ~ 11 instrumentation
line 134 and 1/4 inch control lines 132, figure 24 illustrating a clamp
securing a 1.356 inch cable 136 and 11 X 11 control lines 138, figure 25
illustrating the same clamp securing a 1.156 inch cable 137 and 11 X 11
control lines 138).
The cable dividers are preferably integrally formed with the strap in
the desired number and position. On the cable dividers are fins 102 which
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are flexible and conform to the outside diameter of a cable as it is pushed
into the gap 104 between adjacent cable dividers 103. The resilient
flexibility of the fins ensures that a range of cable shapes and diameters can
be accommodated between neighbouring dividers separated at a particular
distance. The fms are approximately perpendicular to the cables, but may
be slightly angled to aid the cables' insertion. Ideally, the cable clamp is
cast in plastic. In order to conveniently cast the cable dividers, in
particular
the flexible fins, longitudinal slots 122 are provided, so that two sides of
the
die create the fins and the fins are free to flex. Casting of a different
number of cable dividers, or alteration of their position, could conveniently
be achieved by adding, removing and/or repositioning moveable/removable
components in the die halves that form the cable dividers.
The strap receiving portion 120 also accommodates a pawl 105 for a
ratchet. When the front end of the strap (that is, the end of the cable clamp
opposite the strap receiving portion 120 of the clamp) is wrapped around
the pipe 109 and tile cables to be clamped to the pipe, its leading tip 107 is
fed into the slot 108 and pulled tight. A hole 112 in the strap allows the
operator to use a finger to grip the strap easily and pull on it. Once at the
required tensile load any excess is cut off just after the ratchet at 110. The
pawl prevents the teeth on the strap from slipping out of the slot, so
retaining the clamp securely upon the pipe. A wedge 111 could also be
placed behind the strap to provide additional guarantee that the strap could
not come undone. . The tube may then for example be deployed in a 7 111ch
casing 140.
It will be seen that the pawl 105 and the toothed strap could be
configured in a number of ways. Figure 21 shows a clamp where the pawl
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points inwards towards the pipe on which it is attached, and the teeth
exposed on the outer surface of the strap as it is wrapped around the pipe.
Figure 22 shows a pawl that points away from the pipe, and interacts with
teeth provided on the inner surface of the strap as it is wrapped around the
pipe. Equally, one or both edges of the strap could be toothed, with a
corresponding pawl or pawls in the angled part 100 of the cable.
It will be observed that shape of surface of the angled part 100 may
be varied depending upon what type of cable is expected, particularly with
regard to the largest cable expected. Thus the cable clamps shown in
figures 19, 21 and 22 include a right angled portion 124 suitable for holding
a cable square or rectangular section. The cable clamps shown in figure 23,
24 and 25 have a longer angled part without a right angled portion, and are
suitable for holding larger round cables. It will be seen that when holding
large diameter cables, the angled part of the clamp may be lifted clear of the
surface of the pipe 109.
It will be seen that the methods described herein by which the strap may be
secured to the strap receiving part and the methods for positioning the
cables, may be interchanged in a straightforward manner to create further
embodiments; it is particularly comprehended that the cable dividers shown
in figures 19 to 25 can be employed within previously described fastening
means such as the wire loop and tensioning arm. In the embodiments
shown, the clamp member is ideally formed from plastics material, possible
with the addition of metal components (for example, where a wire loop is
employed). It will be realised however that the embodiments could equally
be formed from other material, in particular from metal; thin pieces of
metal can for example be conveniently be stamped into the required form,
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the straps of such clamps being sufficiently defonmable to be wrapped
around a pipe.
14
