Note: Descriptions are shown in the official language in which they were submitted.
CA 02221789 1997-11-21
WO 96/37680 PC'T/EP96102271
CONNECTOR ASSEMBLY FOR AN EXPANDABLE SLOTTED PIPE
This invention relates to a connector assembly for
use in connecting sections of an expandable tubing
string, and in particular but not exclusively for use in
the connection of sections of an expandable slotted
tubing (EST) string as utilised in downhole applications
in the oil and gas exploration and extraction industries.
Expandable slotted tubing (EST) is used in various
downhole applications. The tubing comprises lengths of
tube which have been machined to create a large number of
longitudinal slots. Thus, it is relatively easy to expand
the tube radially outwardly by, for example, running a
mandrel through the tubing. The expansion causes the
slots to extend to create diamond-shaped apertures. The
tubing is useful where it is desired to, for example,
line a bore below a restriction without further reducing
the diameter of the bore. Using conventional tubing, the
oiiter diameter of the tubing must, by necessity, be of
smaller diameter than the restriction, to permit the
tubing to be passed through the restriction. This
reduction in the bore diameter has a number of
significant effects, primarily in reducing the production
capabilities of the bore. Using EST, the tubing may pass
through a restriction into a reamed section of bore below
the restriction. The tubing may then be expanded to a
diameter larger than the restriction.
EST is supplied in lengths which are, at present,
made up into a string by welding the lengths to one
another. This is relatively time consuming and expensive
and in many situations, for example in an off-shore
operation in bad weather, it may be difficult to maintain
consistent weld quality. Safety problems may also arise
due to the high temperatures and exposed flames or sparks
CA 02221789 1997-11-21
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created by a welding operation. Further, in the event of
a"mis-run", requiring the welded lengths of tubing
forming the EST string to be separated, the tubing must
be cut, and the cut tubing cannot be reused.
It is among the objects of the present invention to
provide a means of connecting sections of EST which
obviates or mitigates these difficulties.
According to the present invention there is provided
a connector assembly for interconnecting sections of an
expandable slotted tubing string, the assembly comprising
a male part and a female part formed integrally with the
ends of respective tubing sections, each part being
slotted and being adapted to co-axially engage the other
part to permit expansion of the coupled parts in a
corresponding manner to the tubing string, wherein the
male and female part are interconnectable by one series
of circumferentially spaced mechanical fasteners.
Preferably, the male part is formed by an end of one
of the interconnected tubing sections of which the outer
surface has been machined away over a selected distance
and the female part is formed by an end of the other of
the interconnected tubing sections of which the inner
surface has been machined away over a similar distance.
In such case it is preferred that the free end of the
male and female part fits within an annular groove formed
at the other end of the corresponding part such that if
the parts co-axially engage each other said free ends are
locked in a radial sense inside said grooves to prevent
flaring of said free ends when the tubing string is
expanded.
AMENIDED SNEr-T
CA 02221789 1997-11-21
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This minimizes the possibility of the free ends
flaring on expansion of the tube. Such flaring of the _
male end would create an irregularity in the tubing bore
on which tools could become snagged.
i5 The slotted free ends of the parts will define
fingers and in a preferred arrangement mechanical
fasteners are provided for coupling the respective
= overlapping fingers to one another. This prevents the
ends of the parts from separating when the connected
tubing is expanded. Preferably, each fastener is located
substantially in the middle of a node and halfway between
a pair of adjacent slots. The fasteners may be
releasable, for example short screws for location in
appropriate holes provided in the parts, such that the
tubing may be separated in the event of a mis-run. The
use of screws and the like, and the associated screw-
holes, also provides a convenient means for ensuring that
the parts are properly aligned.
It is therefore preferred that the mechanical
fasteners consist of short screws that pass through
radial holes drilled through the walls of the male and
female parts and the head of each screw is sunken within
a recess formed in the outer surface of the female part
and the shank of each screw engages a screw thread formed
in the radial hole passing through the male part.
.o;tFryrP!J0 SHEET
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Furthermore, the,,female part may be formed by the
free end'..b~; IIe slo'fted tubing section which,_is
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slightly ex~ba~yidler~l trranga.ng the female part co-
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These and o~~~a~.. !e+c~s of the present invention will
now be descrila~ d~; example. with reference to
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the accomparpxyifnlq; s,, in which :
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Figure 1 is a sectional view of a length of
expandable sl-ottedi. ,tuwbing~ (EST) , shown in an expanded
configuration;
Figure 2 is a sectional view on line 2-2 of Figure 1,
and in additioli, sh t~.~ ;.the EST. in unexpanded con-
.
figuratio4;l ~ ~~l~j~ry~~e"t~~i section of a connector
"/4: :,:[(=,~(t:"'f;~ d!C;j~V17~}~ti~;i.}~('. _,r.; !.I .,. . . ..:
assembiy' "itn a preferred embodiment of the
present invention, with the parts of the assembly shown
separated; and
Figure 4 is a half section of the connector assembly
of Figure 3, showing the parts connected.
, . . .;. .,
AMENDED SHEET
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Reference is first made to Figures 1 and 2 of the
drawings, which illustrate a length of expandable slotted
tubing (EST) 10. In its initial configuration, the
tubing 10 is simply a length of pipe in which a series of
15 longitudinal slots 12 have been machined (shown as 12a in
Figure 2). Applying a radially outward force to the
tubing wall, for example by passing a cone or mandrel
through the tubing, causes the tube to expand such that
the slots 12a become diamond shaped openings 12b.
The tubing 10 is supplied in lengths suitable for
transportation and handling and these are joined to one
another to create a tubular string. The connector
assembly 20 as illustrated in Figures 3 and 4 of the
drawings is used to connect such tubing lengths. The
assembly 20 comprises a male part 22 and a female
part 24. The parts 22, 24 are intended to expand in a
similar manner to the tubing 10, and as such are provided
with similar longitudinal slots 26.
The free end of the male part 22 is machined to form
a male portion 28 having a reduced outer diameter and the
free end of the female part 22 defines a corresponding
female portion 30 having a reduced and enlarged inner
diameter to receive the male portion 28, as will be
described. Each part 22, 24 defines a respective annular
groove in the form of an undercut ledge 34, 35 for
engaging the free end 36, 37 of the other part which is
of corresponding form. This serves to prevent the free
ends of one part separating from the other part on
expansion of the tubing.
AMENDED SHEET
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The slots 26 in the parts 22, 24 are arranged such
that the free ends 36, 37 of the parts each define
fingers 40, 41, and each of these fingers defines a
hole 42, 43. The holes 43 in the female part are counter-
I5 sunk, whereas the holes 42 in the male part. 22 are
threaded such that the fingers 40, 41 may be secured to
one another using a number of short screws 44.
To connect two lengths of tubing provided with the
tubing connector assembly 20, the parts 22, 24 are
brought together such that the free end 36 of the male
part passes inside the free end 37 of the female part.
The screws 44 are then secured in the holes 42, 43.
The desired number of tubing sections is connected in
this manner to form a string and run downhole to the
desired location within the bore. The tubing and the
connector assemblies may then be expanded to the desired
diameter. However, in the event of a mis-run, requiring
the tubing to be withdrawn and disassembled, this may be
achieved relatively easy by removing the screws 44.
It will be clear to those of skill in the art that
the above-described embodiment is merely exemplary of the
present invention, and may be subject to various
modifications and improvements without departing from the
scope of the invention.
AMENDED SHEU
