Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02921795 2016-02-24
1 COMPOUND BEAM MECHANICAL CASING COLLAR LOCATOR
2
3 CROSS-REFERENCE TO RELATED APPLICATIONS
4 This application claims the benefit of US Provisional Patent
Application Serial No. 62/120,261, filed Feb. 24, 2015.
6
7 FIELD OF THE DISCLOSURE
8 Embodiments herein relate generally to apparatus and methods for
9 detection of casing collars in a casing string for positioning of
wellbore tools relative
thereto, and in particular to a mechanical casing collar locator.
11
12 BACKGROUND
13 In the process of wellbore completion, a string of casing is
typically run
14 into an open borehole and is cemented into place. Various downhole
components
can be located along the casing, including sleeve valves for access to a
formation of
16 interest. A downhole tool can be run into the casing string on a
conveyance string
17 and the tool is located at specific downhole components by feedback from
a locater
18 positioned on the tool. The locator detects the component itself, or
another feature
19 on the casing, such as collars that can be spacially related to the
position of the
component. It is important that the tools are locatable at known and desired
21 locations within the casing for performance of well operations,
including actuation of
22 the downhole components in the string of casing.
1
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1 In
conventional embodiments, the casing comprises lengths or joints
2 of
tubing which are connected by threaded collars. Ends of the axially aligned
joints
3 of
casing are threaded into the collars. Once threaded therein, the ends of the
4 casing
do not abut, leaving an axial space therebetween. The axial space or recess
formed in the collar has a greater radial dimension than a bore of the joints
of
6 casing,
forming a locatable feature in the casing string. Alternatively, where casing
7
connections do not provide such a gap, specially designed locator tubulars or
8 collars
having a recess formed therein may be installed in the casing string for the
9 express purpose of location.
As is also known, locators can be used not only to detect the collar
11 gap or
recess, but can be used to locate any suitable recess or profile in the string
12 of
casing, which may be formed at the downhole component, such as a sleeve
13 valve.
For example, a suitable profile can be formed at an end of a shifting sleeve
14 movable therein.
A variety of apparatus are known to locate the collars within the casing
16 string
to better understand the positioning of tools run into the wellbore relative
to
17 the
casing component. Known casing collar locators include those using electronic
18 or magnetic sensors in an attempt to consistently locate the collars.
19 Other
known locators are mechanical locators which comprise
arrangements of radially extending, biased members, including protruding dogs,
21 which
releasably engage a respective axial space along the casing string. Once
22 engaged
in the collar or other recess, axial load or weight at surface on the
23
downhole tool is resisted by the locater engagement in the recess, the shift
in load
2
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1 or weight to the conveyance string being observable at surface as an
indication of
2 having reached the desired location.
3 The reliability of location using mechanical locators is generally
related
4 to the resolvable change in the force applied to the tool's conveyance
string during
movement. When the locator engages a recess, a certain axial force is required
to
6 dislodge the locator therefrom. If the locator engages the recess during
a running in
7 stage, an increased downhole force is required to dislodge it from the
recess. If the
8 locator engages the recess during a pulling out of hole stage, an
increased uphole
9 force is required to dislodge it from the recess. The increased force is
measured by
a change in the surface weight of the conveyance string. Typically, when
running in
11 using coiled tubing, lifting weight is used as a marker of locator
positioning, and thus,
12 the nature of the locator/recess interaction is designed for release of
the locater
13 from the recess during pulling out. Others may use a reduction in weight
or a
14 pushing force and, in those instances, the nature of the locator/recess
interaction is
designed for release of the locater from the recess during running in.
16 The release force is a function of a radially outward, recess
17 engagement force and a ramping interface of the locator and recess
interface. The
18 recess has uphole and downhole edges and the locator has leading and
trailing
19 ramp surfaces. Pulling or pushing of the tool and locator forms axial
loading of the
locator ramp against a recess edge. The interface imposes a radially inward
21 release force on the locator, resisted by a biasing of the locator.
22 The mechanical advantage of a shallow or small interface angle
23 produces large, radially inward force with small axial applications of
weight,
3
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1 resulting in relatively indistinguishable weight change and poor locator
resolution. A
2 steep or large interface angle produces a small radially inward force,
even at large
3 axial applications of weight, providing easily detectable weight changes
but at a risk
4 of non-release of the locator and a stuck tool and/or erratic
performance.
For example, Fig. 1 is a portion of a cross-sectional view of a prior-art
6 mechanical casing collar locator 10 with a locator dog 12 located in a
collar recess
7 14 formed by a collar 16 and adjacent casing joints 18 and 20. The
locator dog 12 is
8 profiled, having an uphole ramp or interface 22 and a downhole ramp or
9 interface 24. The dog 12 is typically driven outward with a spring. The
spring force,
and ramp, determines the release behavior of the dog 12 from the recess 14.
11 As described above, the interface angle significantly affects the
12 performance of the casing collar locator. In this example, the uphole
interface 22
13 has an interface angle 8 greater than 60 degrees with respect to a
direction 26
14 parallel to the axis of the casing 18. Consequently, the radial spring
force Fs
required to maintain the locator dog in the recess is relatively small.
However, a
16 large uphole force Fp is required to pull the locator dog 12 out of the
recess 14.
17 It is believed that the release behavior or predictability of a
locator dog
18 having an interface angle greater than 60 degrees can become erratic due
to the
19 requirement of a large release force for releasing the locator dog out
of the collar
recess, even if the radial spring force is small. As the interface angle
becomes
21 larger, even up to 90 degrees, the locator dog becomes stuck.
22 At 60 degrees or smaller, release is much more predictable,
however
23 in order to provide a visual indication at surface, the spring force
must be quite high.
4
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1
Ideally, the interface and biasing force are complementary to provide
sufficient
2 weight
change for consistent detection of locator engagement, yet not so great as to
3 risk tool entrapment or a non-consistent release force.
4 Given
the risk of entrapment or poor detection resolution, there is still
room for improvement to locator technology.
6
7 SUMMARY
8 Given
that tool entrapment is highly undesirable, the designed
9
interface angles at the locator and recess are usually shallow and therefore
robust
radial biasing is required to provide engagement indication. Biasing is
typically
11
associated with the spring material selection and dimensions. Given limited
12
selections in material, the industry typically employs larger springs for
applying
13 more
force. Larger springs, coil springs or spring beams, require a significant
14 portion
of the tool cross-section. If smaller robust springs are required, material
properties need to be increased, however only at the risk of limited elastic
16
displacement before entering the plastic range of deformation. Further,
springs such
17 as coil
springs are prone to trapping of debris therein which may affect tool
18 performance.
19 In
conventional downhole tools, the cross-section typically includes
fluid passageways and apparatus, including equalization valves, sliding
members
21 and the
like. Robust locators, having structure to provide high radial engagement
22
biasing, can interfere with the sizing and placement of tool components and
thus the
23
strength of the biasing is generally limited. Known prior art apparatus have
such
5
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1 restricted diametrical area, and the integration of a locator in such an
environment
2 limits the biasing strength. Such restrictions can compromise the radial
force
3 needed to achieve a pull-through force which is high enough to be
consistently
4 detected and ensure positive and reliable location. In Canadian Patent
Application
No. 2,693,676 to NCS Oilfield Services Inc., the locator is physically
positioned in
6 the tool to reside within the sleeve valve, such as to engage ends of the
tubular
7 sleeve. The tool is fit with fluid passageways to conduct fluid across
the tool,
8 including through the locator. A spring-loaded dog locator is provided
having a
9 locator body, dogs and coil springs between the dogs and the body for
urging the
dogs radially outwardly. The body structure occupies a significant portion of
the tool
11 cross-section and thus, the spring aspect is minimized, limiting the
biasing force
12 possible. Further, with respect to published patent application CA
2,856,184 to
13 NCS Oilfield Services Inc., a locator comprising a leaf spring cage
having dog
14 formed thereon is positioned concentrically about at least a J-slot
arrangement. The
J-slot arrangement occupies a significant portion of the tool cross-section
and thus,
16 the spring aspect is also minimized, limiting the biasing force
possible.
17 Solutions to constraints on the spring can, to a certain extent,
be
18 managed with changes to spring material or spring thickness, however,
this is also
19 associated with reduced elastic range and potential for reduced fatigue
life or even
plastic deformation. Further, attempts to counter reduced radial biasing
forces by
21 increasing the interface angle increases the risk of tool entrapment or
inconsistent
22 release loads.
6
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1 According to one aspect of this disclosure, there is provided an
2 apparatus for locating an annular recess along a wellbore string. The
apparatus
3 comprises: a plurality of circumferentially-spaced, radially outwardly
extending dogs
4 for engaging the recess; and a plurality of supporting structures for
supporting the
plurality of dogs; wherein each supporting structure comprises: two or more
radially
6 stacked layers of circumferentially-spaced, radially flexible, leaf
spring beam
7 members extending along an axial direction.
8 In some embodiments, each dog comprises a first interface for
9 engaging an edge of the recess, the first interface being angled from the
axial
direction at a first interface angle of about or less than 60 degrees.
11 In some embodiments, the first interface angle is about 50
degrees.
12 In some embodiments, the first interface is an uphole interface.
13 In some embodiments, at least a first layer of the two or more
layers of
14 circumferentially spaced leaf spring beam members form a locator cage.
In some embodiments, the locator cage is a slotted tubular.
16 In some embodiments, the circumferentially spaced leaf spring beam
17 members of the locator cage are supported at at least one of two axially
opposite
18 ends thereof by a solid tubular portion.
19 In some embodiments, the circumferentially spaced leaf spring beam
members of the locator cage are supported at each of two axially opposite ends
21 thereof by a solid tubular portion.
7
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1 In some
embodiments, the at least first layer is the radially outmost
2 layer,
and wherein at least a second layer of the two or more layers of
3 circumferentially spaced leaf spring beam members form a reinforcement
cage.
4 In some embodiments, the reinforcement cage is a slotted tubular.
In some embodiments, the circumferentially spaced leaf spring beam
6 members
of the locator cage are supported at at least one of two axially opposite
7 ends thereof by a solid tubular portion.
8 In some
embodiments, the circumferentially spaced leaf spring beam
9 members
of the locator cage are supported at each of two axially opposite ends
thereof by a solid tubular portion.
11 In some
embodiments, the reinforcement cage is concentrically
12 received in the locator cage.
13 In some
embodiments, each dog is supported by at least one beam
14 member
of the first layer, and each beam member of the first layer is supported by
at least one beam member of the at least second layer.
16 In some
embodiments, the locator cage further comprises a first
17
coupling mechanism at an uphole end thereof for coupling the locator cage to a
first
18 sub and
a second coupling mechanism at a downhole end thereof for coupling the
19 locator cage to a second sub.
In some embodiments, after the locator cage is coupled to a first sub
21 at the
uphole end thereof and to a second sub at the down hole thereof, the at least
22 first
reinforcement cage is axially fixed or axially moveable within a predefined
23 range.
8
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1 In some
embodiments, the two or more radially stacked layers of leaf
2 spring beam members are radially aligned.
3 In some
embodiments, the reinforcement cage is circumferentially
4 fixed with respect to the locator cage.
In some embodiments, the apparatus further comprises: a delimit pin
6
extending from the reinforcement cage radially outwardly into a slot between
two
7
adjacent positioned in a slot between two adjacent spring beam members of the
8 locator
cage, for preventing the reinforcement cage from rotating with respect to the
9 locator cage.
According to another aspect of this disclosure, there is provided an
11
apparatus for locating an annular recess along a wellbore string. The
apparatus
12
comprises: a tubular locator cage having a plurality of circumferentially-
spaced,
13
radially flexible, locator leaf spring beam members extending along an axial
14
direction, each locator leaf spring beam member having a locator dog thereon
and
extending radially outwardly, the locator cage having a locator bore; and at
least a
16 first
tubular reinforcement cage fit concentrically within the locator bore, each of
the
17 at
least a first tubular reinforcement cage having a plurality of
circumferentially-
18 spaced,
radially flexible, reinforcement spring beam members extending along the
19 axial direction and for supporting the locator leaf spring beam members.
21 BRIEF DESCRIPTION OF THE DRAWINGS
22 Figure
1 is a portion of a cross-sectional view of a prior-art casing
23 collar
locator having a dog thereon engaging a casing collar recess, the dog having
9
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1 an uphole interface with a relatively large interface angle greater than
60 degrees,
2 resulting in a requirement of a large uphole pulling force to pull the
dog from the
3 recess, and resulting in risk of trapping of the dog in the recess;
4 Figure 2 is a perspective view of an assembled casing collar
locator,
according to an embodiment;
6 Figure 3 is an end view of the casing collar locator of Fig. 1,
showing
7 an outmost, locator leaf spring cage and two reinforcement leaf spring
cages being
8 arranged concentrically;
9 Figure 4 is a perspective view of a partially assembled casing
collar
locator with the locator leaf spring cage and two reinforcement leaf spring
cages
11 being axially offset, the leaf spring beam members of the locator leaf
spring cage
12 and two reinforcement leaf spring cages being aligned;
13 Figure 5 is a perspective view of the locator leaf spring cage,
14 Figure 6 is an end view of the locator leaf spring cage of Fig. 5;
Figure 7 is a cross-sectional view of the locator leaf spring cage of
16 Fig. 5;
17 Figure 8 is a perspective view of a reinforcement leaf spring
cage;
18 Figure 9 is a cross-sectional view of the reinforcement leaf
spring
19 cage of Fig. 8;
Figure 10 is a cross-sectional view of the casing collar locator of Fig. 1;
21 Figure 11 is a portion of a cross-sectional view showing the
casing
22 collar locator of Fig. 1 engaging a collar recess;
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1 Figure 12 is an enlarged view of portion A of Fig. 11, showing an
2 uphole interface of a dog engaging an uphole edge of the collar recess;
3 Figure 13 is a perspective view of the locator leaf spring cage,
4 according to some alternative embodiments;
Figure 14 is a perspective view of a reinforcement leaf spring cage,
6 according to some alternative embodiments; and
7 Figure 15 is a perspective view of the locator leaf spring cage,
8 according to some other embodiments.
9
DETAILED DESCRIPTION
11 Various embodiments of a mechanical casing collar locator are
12 disclosed herein, comprising an outermost, locator leaf spring cage, and
one or
13 more radially stacked reinforcement leaf spring cages. Each leaf spring
cage
14 comprises a plurality of circumferentially-spaced, flexible, leaf spring
beam
members. Each flexible leaf spring beam member of the locator leaf spring cage
16 comprises a locator dog formed to extend radially outwardly from an
intermediate
17 position thereof. The reinforcement leaf spring cage radially supports
the locator
18 leaf spring cage for providing enhanced radially outward spring force.
19 Each locator dog is a profiled dog, extending radially outwardly
from
each flexible leaf spring beam member of the locator leaf spring cage so as to
21 engage collar recesses, or other recesses, in the wellbore casing. The
profiling
22 includes uphole and downhole interfaces or ramps, the selected angle of
which is
23 discussed below for adjusting pull-through forces in combination with
the recess.
11
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1 The
resulting casing collar locator provides significant radially outward
2
directed engagement force (i.e., a force of a direction perpendicular to and
pointing
3 away
from an axis of the casing collar locator), enabling a reduction in the
interface
4 angle
of an engagement interface of each of one or more profiled dogs, such that,
the profiled dogs of the casing collar locator can engage a collar recess with
a low
6 risk of
tool entrapment and higher weight resolution at surface for consistent
7
detection of casing collar recesses. The casing collar locator disclosed
herein
8
achieves high engagement force while able to use a minimum of the locator
cross-
9
section, or simply provide significantly higher radial biasing forces while
remaining
within the elastic range of operation of the biasing with the radial range of
11 displacement required to enter and exit casing recesses.
12 In
embodiments, the present locator achieves sufficient outwardly
13
directed radial force therein, such that an angle of an uphole interface or
ramp of a
14
profiled dog formed thereon is maintained at an angle below that at which
erratic
pull-through force could occur. In combination, the strong radial force and
dog
16
interface angle achieve an optimum pull-through force, such as about 3000-4000
17 dN, for
positive, consistent and reliable location. The pull-through force can also be
18 varied
from tool to tool, such as depending upon the number of spring cages utilized.
19 Thus,
in addition to the ability to provide suitable engagement force
with low interface angles for restricted diametrical environments, further
advantage
21 is
obtained where larger diametrical extent is available, and greater weight
22
resolution can be achieved at surface. The casing collar locator disclosed
herein is
23
particularly useful for tool strings which are arrange to position the locator
therein
12
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away from other internal apparatus so as to provide maximum diametric space
2
therein. Generally, if the locator is used to locate a casing collar spaced
axially from
3 a
shifting sleeve, rather than to the end of the shifting sleeve as known in the
prior
4 art,
the locator can be spaced below other apparatus in the tool string where
increased diametrical area is available therein to accommodate the locator
6
disclosed herein and maximize the release resolution. Embodiments disclosed
7 herein
can locate within a sleeve, however the sleeve length must be adjusted
8 accordingly.
9 Thus,
the locator disclosed herein may be used in various scenarios.
For example, in some embodiments, a downhole tool may comprise a bottom hole
11
assembly (BHA) coupled to the locator disclosed herein. The locator comprises
a
12 bore
forming a flow path, which is in fluid communication with a flow path of the
13 BHA.
14 Turning
now to Figs. 2 to 4, a mechanical casing collar locator is
shown, and is referenced using numeral 100. Similar to traditional casing
collar
16
locators, the collar locator 100 may be coupled to, at either or both ends
thereof,
17
suitable subs 106 such as a crossover sub, and is used for locating one or
more
18 locator
recesses of a casing string such as at collar recesses 14. The one or more
19 collar
recesses 14 are formed as described above, and each collar recess has a
recess diameter.
21 As
shown, the collar locator 100 is a beam-type locator having a
22 tubular
locator leaf spring cage 102 with a bore for receiving therein one or more
23
concentrically arranged, stacked reinforcement leaf spring cages 104. Fig. 4
shows
13
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1 a partially assembled locator leaf spring cage 102 and two reinforcement
leaf spring
2 cages 104A and 1046, axially offset for better illustration.
3 As shown in Figs. 5 to 7, in this embodiment, the locator leaf
spring
4 cage 102 comprises a tubular housing 110 having a bore formed
therethrough. The
housing 110 is machined to form a plurality of circumferentially and
alternately
6 arranged slots 108 and resilient, leaf spring beam members 112 (denoted
as locator
7 leaf spring beam members 112), extending along an axial or longitudinal
direction.
8 Therefore, the locator leaf spring beam members 112 are spaced from each
other,
9 and are separated by the slots 108.
Each leaf spring beam member 112 comprises a radially outwardly
11 extending dog 114 formed intermediate therealong. For example, in Figs.
5 to 7,
12 eight (8) leaf spring beam members 112 are formed, each having an
integrated,
13 radially outwardly extruded dog 114 located at about a mid-point of the
14 corresponding leaf spring beam member 112. The leaf spring beam members
112
are made of metal material with suitable elasticity to provide required radial
flexibility
16 for dogs 114 to enter and exit the recess 14.
17 In this embodiment, each slot 108 terminates at an end 112A/112B
18
spaced axially inwardly from each opposing end of the housing 110, leaving a
rigid, .
19 solid tubular portion 118 at opposing ends of the locator leaf spring
cage 102. The
tubular portion 118 supports the ends 112A and 112B of each beam member 112,
21 and provides a structure for retaining the beam members 112 in axial and
22 circumferential alignment.
14
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1 In an unbiased position, the diameter about the dogs 114 is
greater
2 than that of the inside diameter of the casing, and corresponds more to a
diameter
3 of, or larger than that of, the circumferential collar recess.
Accordingly, the dogs 114
4 drag along the casing string, biased to enter any recess therealong.
Referring to Fig. 7, the dog 114 of each leaf spring beam member 112
6 is profiled, having an uphole locator ramp or interface 122 and a
downhole locator
7 ramp or interface 124. The interface angles a and 13 of the locator
interfaces 122
8 and 124, respectively, with respect to a direction parallel to the
longitudinal axis of
9 the locator leaf spring cage 102 are chosen to be relatively small
angles, depending
on the design requirements. For example, in the embodiment shown in Fig. 7,
the
11 casing collar locator 100 is used for locating collar recesses during a
pull-out-of-hole
12 stage. Therefore, the downhole interface is angled such that the
downhole tool
13 including the casing collar locator 100 can be readily run in and moved
downhole
14 along the casing and past the recesses therein. For example, the
downhole
interface angle 13 in this example is a relatively small angle such as about
15
16 degrees for ease of insertion of the locator into the casing. The uphole
interface
17 angle a may be an angle suitable for a sufficiently high resolution to
locate a collar
18 recess with sufficient accuracy, e.g., about 60 degrees or smaller.
19 In this embodiment, the locator leaf spring cage 102 also has a
plurality of screw holes 116 on each ends thereof for locking the casing
collar
21 locator 100 to suitable subs (not shown).
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1 To
provide the radial range of motion, while maintaining the radially
2 elastic
deflection of the locator leaf spring cage 102, one or more concentrically
3 arranged, stacked reinforcement spring cages 104 are provided.
4 As
shown in Figs. 8 and 9, the structure of the reinforcement spring
cage 104 is similar to that of the locator leaf spring cage 102. In
particular, the
6
reinforcement spring cage 104 comprises a tubular housing 130 having a bore
7 formed therethrough. The housing 130 is machined to form a plurality of
8
circumferentially and alternately arranged slots 132 and resilient, leaf
spring beam
9 members
134 (denoted as reinforcement beam members 134), extending along a
longitudinal direction. At least the leaf spring beam members 134 are made of
metal
11
material with suitable elasticity to provide required radial flexibility.
However, in this
12
embodiment the leaf spring beam members 134 do not comprise any radially
13 outward protrusion.
14 In this
embodiment, the number of leaf spring beam members 134 of
each reinforcement spring cage 104 can correspond to that of the leaf spring
beam
16 members
112 of the locator leaf spring cage 102 such that each locator leaf spring
17 beam
member 112 is supported by at least one reinforcement beam member 134 to
18 reinforcing the biasing thereof.
19 Similar
to the slots 108 of the locator leaf spring cage 102, each of the
slot 132 of the reinforcement spring cage 104 terminates spaced axially
inwardly
21 from
each opposing end of the housing 130, leaving a rigid, solid tubular portion
138
22 at
opposing ends of the reinforcement spring cage 104 for providing fixed
supports
16
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at the end of each beam member 134 and a structure for retaining the beam
2 members 134 in axial and circumferential alignment.
3 In this embodiment, each reinforcement spring cage 104 also
4 comprises an alignment port 136 axially spaced from a slot 132 for
receiving an
alignment pin (described later).
6 The outer diameters of the reinforcement spring cages 104 are such
7 that each reinforcement spring cage 104 fits concentrically within the
bore of an
8 adjacent outer spring cage, which may be the locator leaf spring cage 102
or an
9 outer reinforcement spring cage 104.
In this embodiment, each reinforcement spring cage 104 has a length
11 shorter than that of the locator leaf spring cage 102 to allow the
locator leaf spring
12 cage 102 to receive other subs extending thereinto for coupling thereto.
13 As described above, a casing collar locator 100 may be assembled
14 using a locator leaf spring cage 102 and one or more reinforcement
spring cages
104. In an example shown in Figs. 2 to 4 and 10, a casing collar locator 100
is
16 assembled using a locator leaf spring cage 102. Concentrically received
within the
17 locator cage 102 are two reinforcement spring cages 104A and 104B, with
the
18 spring cage 104B received within the spring cage 104A. As shown in Fig.
4, the
19 spring cages 102, 104A and 104B are circumferentially aligned such that
the slots
108 and 132 thereof are aligned and the leaf spring beam members 112 and 134
21 are also aligned.
22 After the spring cages 102, 104A and 104B are axially in position
(see
23 Figs. 1 and 10), the alignment ports 136 of the reinforcement spring
cages 104A
17
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and 104B are also aligned. As the lengths of the two reinforcement spring
cages
2 104A and 104B are shorter than that of the locator leaf spring cage 102,
the
3 alignment ports 136 thereof are exposed through a slot 108A of the
locator leaf
4 spring cage 102. As shown in Fig. 1, a delimit pin 140, such as a socket
head cap
screw, extends through the slot 108a and is secured into the alignment ports
136 of
6 the reinforcement spring cages 104A and 104B. The head of the pin 140
prjects
7 from the cage 105A to be circumferentially constrained within the slot
108A to
8 prevent relative rotation between the spring cages 102, 104A and 104B so as
to
9 maintain the radially stacked alignment of the leaf spring beam members
112 and
134.
11 As persons skilled in the art appreciate, the aligned slots 108
and 132
12 in the concentric spring cages 102 and 104 can also provide fluid
pathways
13 therethrough, such as to a bore of the locator and tool string. Such
fluid pathways
14 are useful in flushing debris therethrough.
After assembling, the reinforcement spring cages 104A and 104B are
16 circumferentially constrained, but are allowed to move or slide axially.
For ease of
17 storage and transportation, the assembled casing collar locator 100 may
be capped
18 at both ends thereof to prevent the inner, reinforcement spring cages
104A and
19 104B from moving out of the outer, locator spring cage 102.
As shown in Fig. 10, in use, the assembled casing collar locator 100 is
21 coupled to subs 106A and 106B on the uphole and downhole ends thereof.
As
22 shown, the outermost, locator leaf spring cage 102 comprises inwardly
threaded
23 ends, operatively connected to outwardly threaded respective ends of
subs 106A
18
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and 106B. The connections of the locator leaf spring cage 102 and subs 106A
and
2 106B are further secured by the screws 142 screwing through the holes 116
of the
3 locator leaf spring cage 102 and onto the respective subs 106A and 106B. Of
4 course, other known methods of coupling the locator leaf spring cage 102
to subs
106A and 106B are also readily available and may be alternatively used.
6 After coupling the locator leaf spring cage 102 to subs 106A and
106B,
7 the reinforcement spring cages 104A and 104B are then axially sandwiched
8 between the subs 106A and 106B, with the opposite ends of the
reinforcement
9 spring cages 104A and 104B loosely facing the butt ends of subs 106A and
106B.
The axial location of the reinforcement spring cages 104A and 104B is thus
11 delimited by the subs 106A and 106B respectively at the uphole and
downhole
12 sides thereof.
13 As the spring cages 102, 104A and 104B have the same number of
14 leaf spring beam members 112, 134, and are aligned circumferentially,
after
assembly, the leaf spring beam members 112, 134 of the spring cages 102, 104A
16 and 104B are radially aligned and stacked "on top of one another". As
will be
17 described in more detail below, the stacked leaf spring beam members
112, 134
18 provide higher radial spring force Fs for maintaining the locator dogs
114 in the
19 collar recess.
As described above, in a radially unbiased position, the diameter
21 about the dogs 114 is greater than that of the inside diameter of the
casing. In some
22 embodiments, the diameter about the dogs 114 is about, or even larger
than, a
23 diameter of the circumferential collar recess. While running in, each
dog 114 and
19
CA 02921795 2016-02-24
1 the
corresponding leaf spring beam member 112 are deflected radially inward to a
2 smaller
diameter, such as the inner diameter of the casing or the downhole
3
component or sleeve. Any axial length change due to the radial deflection of
the
4 spring
cage 102 is reflected in a change in the axial spacing of the subs 106A and
106B. However, any change of axial length of the reinforcement cages 104A and
6 104B
are unconstrained as the delimit pin 140 can move axially in slot 108A, and
7 thus
the reinforcement cages 104A and 104B can float axially between subs 106A
8 and 106B.
9 The
inward, elastic deflection of the leaf spring beam member 112 of
the outmost locator leaf spring cage 102 urges and inwardly and elastically
deflects
11 the
radially stacked, one or more leaf spring beam members 134 of the one or more
12 inner,
reinforcement spring cages 104. As the corresponding leaf spring beam
13 members
112 and 134 are not mounted together, they can deflect radially and can
14 shift
axially with respect to each other. Comparing to the embodiment of a locator
cage having "thick" leaf spring beam members but with no reinforcement cages,
the
16 above
design shown in Fig. 10 allows larger elastic range. Comparing to the
17
embodiment that the reinforcement cage(s) 104 are also axially fixed to the
locator
18 cage
102 (described later), the above design shown in Fig. 10 avoids stress caused
19 by
different deflections and/or different length changes of the leaf spring beam
members 112 and 134.
21 As each
leaf spring beam member 112 of locator leaf spring cage 102
22 is
elastically supported radially by the respective leaf spring beam members 134
of
23 the one
or more inner, reinforcement spring cages 104, the total radially outwardly
CA 02921795 2016-02-24
1 directed spring force Fs is an aggregated radial spring force exerted by
the stacked
2 leaf spring beam members 112 and 134. For example, in the embodiment of
Fig. 10,
3 the casing collar locator 100 comprises three spring cages 102, 104A and
104B,
4 and the outward radial force Fs is much larger than that of a single
spring cage 102,
104A or 104B. Those skilled in the art appreciate that an estimate or
calculation of
6 the radial force Fs is readily available using known theories.
7 When the dogs 114 move into a collar recess, the radially outward
8 force Fs causes the dogs 114 and the leaf spring beam members 112 and 134
to
9 return towards their normal, radially unbiased positions.
Fig. 11 is an illustration showing a portion of the casing collar locator
11 100 being pulled uphole and having engaged a collar recess 14 formed by
a casing
12 collar 16 between two adjacent casing joints 18 and 20. The aggregated
force Fs
13 allows the casing collar locator 100 to provide higher recess detection
resolution (or
14 weight resolution if using weigh change as an indication of detection)
at surface.
As shown in Figs. 11 and 12, when the tubing string and therefore the
16 casing collar locator 100 is again pulled uphole by an uphole force Fp,
the edge 152
17 of the collar recess 14 pushes the uphole locator interface 122 of the
dog 114
18 engaged therewith, with a force Fr perpendicular to the plane of the
uphole locator
19 interface 122. The force Fr corresponds to an axially downhole force Fd
combatting
the pulling force Fp, and a radially inward force Fi combatting the radially
outward
21 spring force Fs to urge the leaf spring beam members 112 and 134 to
deflect
22 radially inwardly against the combined or aggregated beam biasing.
21
CA 02921795 2016-02-24
1 As
described above, the angle a of the uphole locator interface 122 is
2
relatively small, e.g., about or smaller than 60 degrees. However, by
reinforcing the
3 dog 114
with two or more leaf spring beam members 112 and 134 to obtain an
4
aggregated radial spring force Fs, a large force is then required to pull the
dog 114
out of the recess, giving rise to a higher weight resolution at surface for
recess
6 detection.
7
Further, at about 60 degrees or less, risk of jamming between the
8 uphole
locator interface 122 and the edge 152 of the collar recess 14 and/or tool
9
entrapment is minimized. In some embodiments, the uphole locator interface 122
may be angled at about 50 degrees. The degree of angle of the uphole locator
11
interface 122 can be balanced with the number of stacked spring cages 102 and
12 104 to
provide the desired pull-through force to achieve reliable location. With the
13 above
described casing collar locator 100, locating a collar recess 14 by the casing
14 collar
locator 100 can be consistently observed at surface, and the profiled dog 114
can also be reliably disengaged and removed from the recess 14.
16 As a
comparison, the traditional mechanical casing collar locator 10 of
17 Fig. 1,
assuming that it is manufactured using the same material as the casing collar
18 locator
100 disclosed herein, provides a smaller spring force Fs. Consequently, a
19 large
interface angle a, e.g., larger than 60 degrees and up to 90 degrees, is
needed to provide sufficient weight resolution at surface. However, such a
large
21 interface angle a has a high risk of jamming and/or entrapment.
22 In a
process for locating a casing collar recess 14, the tool string,
23 having
the casing collar locator 100 positioned therein, is deployed into the
wellbore,
22
CA 02921795 2016-02-24
1 such as
on coiled tubing. The tool string is run into the wellbore below a depth at
2 which
the operator anticipates a collar of interest to be located as is well
understood
3 in the
art. The tubing string is then lifted until the profiled dogs 114 reach the
collar
4 recess
14 at which time the deflected, stacked spring cages 102 and 104 are able
to release and apply the radial outwardly force, resulting in positive
engagement of
6 the
profiled dogs 114 within the recess 14. As the dogs 114 engage in the recess
14,
7 weight
applied to the coiled tubing is transferred to the casing which can be
8
observed at surface. When the tool string is to be moved within the wellbore,
a
9 pulling
force Fp is applied to the coiled tubing string. At the design pull-through
force,
for example at about 3000-4000 daN (Decanewton), the profiled dogs 114 are
11 pulled
out of the recess 14 and the tool can thereafter be moved within the wellbore.
12 In some
alternative embodiments, the collar recess 14 may also have
13 angled
uphole and/or downhole edges, and the angles of the uphole and/or
14
downhole locator interface 122, 124 may be selected to mate the angles of
uphole
and/or downhole edges, respectively.
16 In
above embodiments, the uphole interface angle a is larger than the
17
downhole interface angle 13. However, those skilled in the art appreciate that
the
18 uphole
and downhole angles a and 6 may be any suitable values. For example, in
19 some
alternative embodiments, the uphole and downhole interfaces 122 and 124
have the same interface angle, i.e., a=6, and in some other embodiments, the
21 uphole interface angle a may be smaller than the downhole interface
angle 13.
22
Referring again to Figs. 7 and 10, in above embodiments, the leaf
23 spring
beam members 112 of the locator leaf spring cage 102 are also profiled at an
23
CA 02921795 2016-02-24
1 inner surface thereof beneath the respective dogs 114, forming
discontinuous areas
2 or points of contact between the leaf spring beam members 112 of the
locator leaf
3 spring cage 102 and the leaf spring beam members 134A of the adjacent
4 reinforcement leaf spring cage 104A.
In some alternative embodiments, the leaf spring beam members 112
6 of the locator leaf spring cage 102 are not profiled at the inner surface
thereof (in
7 other words, having a local, thicker cross-section at the dog location),
and are in
8 contact with the leaf spring beam members 134A of the adjacent
reinforcement leaf
9 spring cage 104A substantially along their entirety.
In some other embodiments, the leaf spring beam members 112 of the
11 locator leaf spring cage 102 are profiled at the inner surface thereof.
12 Correspondingly, the leaf spring beam members 134A of the adjacent
reinforcement
13 leaf spring cage 104A are also profiled accordingly such that the leaf
spring beam
14 members 112 are in contact with corresponding leaf spring beam members
134A
thereunder substantially along their entirety.
16 In above embodiments, the leaf spring beam members 112 and 134 of
17 the locator leaf spring cage 102 and reinforcement leaf spring cage(s)
104,
18 respectively, are supported at both ends 112A and 112B thereof.
19 In some alternative embodiments as shown in Fig. 13, the leaf
spring
beam members 112 may be supported only at one end 112A thereof by a solid
21 tubular portion 118, being cantilevered therefrom. In such cantilevered
22 embodiments, additional spring force Fs may be required compared to the
above
23 described embodiments to achieve the design pull-through force. Additional
24
CA 02921795 2016-02-24
1 concentric reinforcement leaf spring cages 104 or other types of springs
may be
2 added to increase the spring force.
3 Similarly in some alternative embodiments as shown in Fig. 14, the
4 leaf spring beam members 134 may be supported only at one end 134A
thereof by
a solid tubular portion 138, being cantilevered therefrom.
6 In some alternative embodiments as shown in Fig. 15, some leaf
7 spring beam members 112-1 may be supported only at one end 112A thereof
by a
8 solid tubular portion 118A, being cantilevered therefrom, and other leaf
spring beam
9 members 112-2 are supported at both ends 112A and 112B thereof by solid
tubular
portions 118A and 118B, respectively. Similarly, in some alternative
embodiments,
11 some of the leaf spring beam members 134 may be supported only at one
end
12 thereof by a solid tubular portion, being cantilevered therefrom, and
others of the
13 leaf spring beam members 134 are supported at both ends thereof by solid
tubular
14 portions, respectively.
In above embodiments, the leaf spring beam members 112 and 134 of
16 the locator leaf spring cage 102 and reinforcement leaf spring cage(s)
104,
17 respectively, are radially aligned, and each of the leaf spring beam
members 112
18 and 134 (except those of the innermost reinforcement leaf spring cage)
is supported
19 by one leaf spring beam member 134 thereunder. In some alternative
embodiments,
at least one of the leaf spring beam members 112 and/or 134 is supported by
two or
21 more leaf spring beam members 134 thereunder. For example, at least one
22 reinforcement leaf spring cage may be misaligned with the (locator or
reinforcement)
23 leaf spring cage adjacent and radially outward thereof such that each
leaf spring
CA 02921795 2016-02-24
beam member of the outer leaf spring cage is supported by two leaf spring beam
2 members of the inner leaf spring cage.
3 In above embodiments, each leaf spring cage comprises a same
4 number of leaf spring beam members. In some alternative embodiments, at
least
one leaf spring cage comprises a different number of leaf spring beam members.
6 In above embodiments, the leaf spring cages 102 and 104 are
7 circumferentially fixed to each other by a delimit pin 140. In some
alternative
8 embodiments, at least some of the leaf spring cages 102 and 104 are not
9 circumferentially fixed such that they may rotate and circumferentially
misaligned.
In above embodiments, each dog 114 is an integrated part of the
11 respective leaf spring beam member 112 formed by outwardly extending a
mid-
12 portion of the leaf spring beam member 112. In some alternative
embodiment, at
13 least some dogs 114 are manufactured separately, and then each dog 114
is
14 mounted to an outer surface of the respective leaf spring beam member
112 using
suitable means such as welding, screwing and the like.
16 In above embodiments, the dogs 114 are at about a mid-point of
their
17 respective leaf spring beam members 112. In some alternative
embodiments, the
18 dogs 114 are at a point axially offset from the mid-point of the
respective leaf spring
19 beam members 112.
In some alternative embodiments, some leaf spring beam members
21 112 of the locator leaf spring cage 102 may not comprise any dogs.
22 In some alternative embodiments, the spring cages 102 and 104 are
23 also axially fixed to each other using suitable fastening means, e.g.,
screws.
26
CA 02921795 2016-02-24
In the casing collar locator 100 disclosed herein, each dog 114 is
2 supported by two or more leaf spring beam members 112 and 134, i.e.,
directly
3 supported by a locator leaf spring beam member 112 and further reinforced
by one
4 or more reinforcement leaf spring beam members 134. In above embodiments,
the
casing collar locator 100 comprises a locator spring cage 102 for forming the
locator
6 leaf spring beam members 112, and one or more reinforcement spring cage
104 for
7 forming the reinforcement leaf spring beam members 134.
8 In some alternative embodiments, the casing collar locator 100
9 comprises a locator spring cage 102 for forming the locator leaf spring
beam
members 112 for directly supporting the dogs 114. However, the casing collar
11 locator 100 does not comprise any reinforcement spring cage 104. Rather,
one or
12 more laminated, reinforcement leaf spring beams each having one or more
layers of
13 leaf spring beam members 134 is coupled to each locator leaf spring beam
member
14 112 by using suitable fasteners. The reinforcement leaf spring beam may
be
circumferentially constrained, but may be allowed to move axially within a
16 predefined range. The laminated, reinforcement leaf spring beams may be
coupled
17 to the inner surface, outer surface or both surfaces of the locator leaf
spring beam
18 member 112, as needed or desired.
19 In above embodiments, after the locator leaf spring cage 102 is
coupled to a first and a second subs 106 at the uphole and downhole ends
thereof,
21 respectively, the reinforcement leaf spring cage(s) 104 are axially
fixed in a
22 predefined position. In some alternative embodiments, after the locator
leaf spring
23 cage 102 is coupled to a first and a second subs 106 at the uphole and
downhole
27
CA 02921795 2016-02-24
1 ends thereof, respectively, the reinforcement leaf spring cage(s) 104 may
still be
2 axially moveable within a predefined range.
3 Although embodiments have been described above with reference
to
4 the accompanying drawings, those of skill in the art will appreciate that
variations
and modifications may be made without departing from the scope thereof as
defined
6 by the appended claims.
28
