Note: Descriptions are shown in the official language in which they were submitted.
CA 02522910 2000-09-29
LINER HANGER
FIELD OF THE INVENTION
The field of this invention relates to liner hangers, and, more particularly,
to the
techniques for securing liner hangers in well bores.
BACKGROUND OF THE INVENTION
Liner hangers are secured in the well bores by slips. Actuation systems for
such slips
in the past have employed full circumference hydraulically actuated pistons to
move the slips.
These designs presented a pressure rating problem in that the full
circumference piston
frequently had a maximum working pressure significantly lower than the mandrel
which it
surrounded. Thus, this type of design limited the maximum working pressure in
the string to
the rating of the cylindrical piston housing assembly. For example, it was not
unusual in
prior designs to have mandrels rated for 12,000 PSI while the surrounding
cylinder housing
for the cylindrical piston to only have a rating of approximately 3,000 PSI.
In an effort to
improve the shortcoming of this design, another design illustrated in U.S.
Patent 5,417,288
was developed. In this design the mandrel body received a pair of bores
straddling each of
the slips. A piston assembly was mounted in each of the bores with all of the
necessary seals.
The application of hydraulic pressure in the mandrel into all the piston bores
actuated the
pistons on either side of each slip through a common sleeve to which all the
slips were
attached. This design, however, was expensive to manufacture and had many
potential leak
paths in the form of the ring seals on each of the pistons wherein each slip
required two
pistons. This design, however, did provide for a higher pressure rating for
the liner hanger
body. It also used the hydraulic pressure directly to actuate the slips.
Necessarily it did not
include a locking feature against premature slip movements due to
inadvertently applied
pressures. The design in the U.S. Patent 5,417,288 also did not provide for
flexibility for
changed conditions down-hole which could require additional force to set the
slips. In
essence, each application was designed for a pre-existing set of conditions
with field
variability not included as a feature of that prior art design.
Slip assemblies in the past have been configured in a variety of ways. In one
configuration, when the slips are actuated, the load is passed through the
slips
circumferentially through their guides or retainers and transmission of the
load to the
underlying mandrel is avoided. In other more traditional designs, the slips
are driven along
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CA 02522910 2000-09-29
tapered surfaces of a supporting cone and the loading is placed on the
supporting mandrel is
in a radial direction toward its center, thus tending to deform the mandrel
when setting the
slips. Typical of such applications are U.S. Patents 4,762,177, 4,711,326 and
5,086,845.
The design of the liner hanger needs to accommodate circulation of mud and
cement.
The prior designs, particularly those using a cylindrical piston, obstructed
the passages that
could have been used for circulating cement and mud.
The apparatus of the present invention has many objectives. A versatile
actuation
system for a locking system is provided. The apparatus uses a combination of
hydraulic
pressure to defeat a locking mechanism which in turn allows mechanical
actuation of the
slips. The slips are configured to pass the loading into the slip seat and
then into the mandrel
in a manner so as not to deform the mandrel. The slips act independently of
each other and
transfer their load through the surrounding slip seat directly to the mandrel.
The slip seats are
attached to the mandrel without welding because standard setting organizations
and well
operators have restrictions against connecting parts made of certain materials
by welding or
against welding altogether in down-hole tools. The slip seats are spaced from
each other to
provide flow channels along the exterior of the liner hanger to facilitate the
movement of
cement or mud. Those passages are continued for the length of the tool. The
actuating piston
assembly to defeat the lock mechanism is a bolt-on arrangement which can be
readily
interchanged in the field to react to changing down-hole conditions. The
actuating piston is
fully compensated for thermal effects and a system is provided to vent any
gases from the
piston actuation system which is used to defeat the lock. The lock can be in a
number of
alternative styles. One of which involves using a dog to hold the parts
together for run in and
liberating the dog from its groove to allow setting of the slips, which is
preferably done by a
plurality of springs. The parts are also disposed in a preferred spacing to
make maximum use
of the limited force available from the piston assembly for releasing the
lock. The lock
configuration can also be in the form of a split ring held together by a yoke
which allows
relative movement when the yoke is shifted, allowing the split ring to expand.
These and
other objectives of the present invention will become more apparent to those
skilled in the art
from a review of the preferred and alternative embodiments described below.
SUMMARY OF THE INVENTION
A liner hanger assembly has a slip actuation system which is locked for run-
in. A
piston assembly bolts onto the mandrel in a sealable manner to actuate a
mechanical lock.
Upon release of the lock, a plurality of springs actuate a sleeve which is in
turn attached to
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CA 02522910 2000-09-29
the slips to move them relative to their slip seats. In an alternative
embodiment, a plurality of
springs can directly move the slips relative to their slip seats, when the
springs are released.
The slip seats are preferably mounted to the mandrel without welding and have
longitudinal
spaces for mud or cement flow therebetween. Load is distributed from each slip
through its
slip seat into the mandrel without interaction from an adjacent slip or slip
seat. A rupture
disk ensures that a predetermined pressure is built up before the piston can
actuate to defeat
the lock. The lock can come in a variety of configurations. One of which is a
sliding sleeve
over a dog and another is a yoke over a split ring which, when shifted, allows
the split ring to
expand, thus unlocking the parts. Yet another variant is a yoke restraining a
split ring. The
slips can also be configured to allow flow of mud or cement behind them, thus
reducing the
resistance to flow of such materials.
Accordingly in one aspect of the present invention there is provided a liner
hanger
comprising:
a body;
a plurality of slips, said slips being actuable by a bias force stored in said
body and
applied to a connected sliding sleeve;
a lock selectively retaining said sleeve to said body; and
a pressure operated release mechanism on said body to selectively move said
lock to
allow said sliding sleeve to be biased by said stored force to move said slips
to a set position.
According to another aspect of the present invention there is provided a liner
hanger
comprising:
a body;
a plurality of slips, said slips being actuable by a bias force applied to a
connected
sliding sleeve;
a lock selectively retaining said sleeve to said body; and
a release mechanism on said body to allow said biased sliding sleeve to move
said
slips to a set position, said release mechanism being removably secured to
said body by a
fastener to allow different release mechanisms to be used on the same body.
According to yet another aspect of the present invention there is provided a
liner
hanger comprising:
a body;
a plurality of slips, said slips being actuable by a bias force applied to a
connected
sliding sleeve;
a lock selectively retaining said sleeve to said body; and
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CA 02522910 2000-09-29
a release mechanism on said body to allow said biased sliding sleeve move said
slips
to a set position;
said slips being individually supported by seats which are circumferentially
spaced
and non-weldingly secured to said body whereupon loads transferred from said
slips to their
respective seats are principally tangentially transferred into said body.
DETAILED DESCRIPTION OF THE DRAWINGS
Embodiments of the present invention will now be described more fully with
reference to the accompanying drawings in which:
FIGS, 1A through C are a plan view of the apparatus looking down on the spring
housing;
FIG. 2 is a rotated view from the view of FIGS. 1A and B showing a plan view
of the
lock housing;
FIG. 3 is a section view through lines 3-3 of FIG. 2;
FIG. 4 is a section of lines 4-4 of FIG. 2;
FIG. S is a section through lines 5-S of FIG. 2;
FIG. 6 is a section through lines 6-6 of FIG. 2;
FIG. 7A through C are a section view through the lock housing during the run-
in
position;
FIG. 8 is the section view through the piston housing in the set position when
the lock
has been defeated.;
FIG. 9 illustrates the connection between the spring housing and the gage
ring;
FIG. 10 illustrates the springs used to set the slips and the guide for each
spring in
section through either the spring housing or the lock housing.
FIG. 11 is a top view showing the longitudinal passages that facilitate the
flow of
cement or mud;
FIG. 12 is a section view through the piston housing retainer bolt showing the
passages therethrough;
FIG. 13 is a section view through the piston housing showing the passages from
the
retainer bolt to the rupture disk location;
FIG. 14 is a plan view of one of the slips;
FIG. 15 is a perspective view of the same slip shown in FIG. 14, showing the
slip in
perspective and the sloping end surfaces;
FIG. 16 is a plan view of the lock dog retainer;
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CA 02522910 2000-09-29
FIG. 17 is a section view through lines 17-17 in FIG. 16;
FIG. 18 is a section view of the lock dog;
FIG. 19 is a plan view of the lock dog release;
FIG. 20 is a section view through lines 20-20 of FIG. 19;
FIG. 21 is a partial section through the longitudinal interior passage in the
lock
housing which in part holds the locking dog;
FIG. 22 is a plan view of the lock housing;
FIG. 23 is a plan view of the slip seat;
FIG. 24 is a section view through lines 24-24 of FIG. 23;
FIG. 25 is a section view through lines 25-25 of FIG. 24;
FIG. 26 is a section through the slip seat retainer;
FIG. 27 is a plan view of the mandrel;
FIG. 28 is a more detailed plan view of the mandrel;
FIG. 29 is a section through lines 2929 of FIG. 28;
FIG. 30 is a section view of an alternative embodiment taken through one of
the slips;
FIG. 31 is a plan view of the slip shown in FIG. 30 taken along line 31-31 of
FIG.
30.
FIG. 32 A through C are the view of FIGS. 30 A through C rotated to show the
spring housings;
FIGS. 33 A through C are the view of FIGS. 30 A through C rotated to show the
spring housings;
FIGS. 33 A through C are the view of FIGS. 30 A through C further rotated to
show
the locking feature;
FIG. 34 is an elevation view of the snap ring;
FIG. 35 is an isometric view of the internal key;
FIG. 36 is a view taken along lines 36 - 36 of FIG. 31.
FIG. 36a illustrates a longitudinal cross section of the tool through the
piston
assembly, lock mechanism, slip and slip seat.
FIG. 37 is a plan view of the tool in the set position.
FIG. 38 is a plan view of the tool in the run-in position.
FIG. 39 is a section view of the piston assembly and lock mechanism in the run-
in
position.
FIG. 40 is a section view of the piston assembly and lock mechanism in the set
position.
CA 02522910 2000-09-29
FIG. 41 is a section view through FIG. 39, of the piston assembly bolted to
the
mandrel.
FIG. 42 is an end view of the lock.
FIG. 43 is an end view of the snap ring.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 1 through 11, the major components of the apparatus in A
will
now be described. Apparatus A has a mandrel 10 which has a lower end 12. Lower
end 12 is
shown schematically and those skilled in the art will appreciate that the
liner string is
connected at lower end 12. The mandrel 10 has an upper end 14 to which those
skilled in the
art will appreciate is attached a running string for proper positioning of
securing assembly S
shown in FIGS. 1A through C. The mandrel 10 has a shoulder 16 which defines a
reduced
diameter segment 18.
A gage ring 20 is shown in FIGS. 1A and in section in FIG. 3. The gage ring 20
has
a split 22 (see FIG. 3) and a draw bolt 24 so as to bring the components of
the gage ring 20
together at split 22 once the gage ring 20 has been advanced beyond the
shoulder 16 and
onto the reduced diameter segment 18. Gage ring 20 has several flats, one of
which 26 is
shown in interrupted form in FIG. 9. FIG. 9 is a section view through the gage
ring 20
showing the spring housing 28 mounted to it. By comparing FIGS. 1A and 9, it
can be seen
that the spring housing 28 has a tab 30 which extends into a window 32 in flat
26 of gage ring
20. In that manner as shown in FIG. 9, the position of the spring housing 28
is initially fixed
to the gage ring 20 and that engagement is secured by bolts 34.
FIG. 2 shows a rotated view from FIGS. 1A and B, indicating that the gage ring
20
also supports the lock housing 36. The number of spring housings 28 can vary
without
departing from the spirit of the invention. In the preferred embodiment
disclosed, there are
three spring housings 28 and one lock housing 36, generally at 90 degree
spacings, thus
defining elongated passages 38 therebetween (see FIG. 11), these passages 38
shown
schematically in FIG. 1B allow mud or cement to pass relatively unimpeded.
Referring again to FIG. 2, the lock housing 36 is secured to the gage ring 20
by bolts
34. Referring to FIG. 22, a top view of the lock housing 36 is illustrated. It
has a top end 40
adjacent to which are the openings 42 through which the bolts 34 are inserted.
Also shown in
hidden lines is a downwardly oriented tab 44 which is placed through a
corresponding
opening or window in the gage ring 20, similar to the method of attachment
shown in FIG.
1A. The lock housing 36 also has an extending arm 46 which is rectangular in
cross-section
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CA 02522910 2000-09-29
and includes a receptacle 48 for engagement of a slip 50 (see FIG. 1B). It
should be noted
that FIG. 1B illustrates in dashed lines the movement of receptacle 48 into a
second position
which reflects the setting of the slip 50. Arm 46, shown in FIG. 22 also has
an oblong
undercut 52 which fits into slot 54 of slip seat retainer 56 (see FIGS. 26 and
1B). In that
manner the slot 54 acts as a guide to the longitudinal motion of lock housing
36. It also holds
arm 46 against centrifugal force created by rotation of the apparatus A at
speeds as high as
about 250 RPM. The same configuration is found in the spring housing 28 shown
in FIGS.
1A through C employing the identical undercut 52 with the same slip seat
retainer 56
providing a slot 54 to guide an arm 46 which in turn through receptacle 48
secures yet
another slip 50. It should be noted that FIG. 2 is a partial view of the lock
housing 36 shown
in a rotated position from the view of FIG. 22, and therefore, it does not
show the arm 46 or
receptacle 48 at the end of it which is used to connect to a slip 50.
Referring again to FIG.
22, the lock housing 36 has a series of blind bores 58, two of which are shown
in FIG. 22 in
hidden lines. A section through one of the blind bores 58 is seen in FIG. 10.
There, a spring
60 surrounds a spring retainer 62. In the run-in position, the spring 60 is
compressed so that
when the lock mechanism L is released, the energy stored in spring 60 is also
released
allowing upward movement of the gage ring 20 as shown by comparing FIGS. 7 and
8.
Initially, however, each of the spring housings 28 has a plurality of blind
bores 58 (see FIG.
1B), each of which has a spring 60 and a retainer 62 mounted therein. The
number of springs
and the size of the spring 60 can vary without departing from the spirit of
the invention.
Those skilled in the art will appreciate that the number of available spring
60 and their size
will dictate the amount of upward force that can be exerted on gage ring 20
which pulls up
with it the spring housing 28 and the lock housing 36, which in turn pull
slips 50 relative to
slip seat 64, securing assembly S to a tubular in the well bore.
One version of the lock mechanism L will now be described. The lock housing 36
has a mufti-dimensional longitudinal opening 66 (see FIG. 22). As shown in
FIG. 22, the
opening 66 extends for a significant length of the piece and then continues as
a bore 68 which
has a generally rectangular cross-section with a downwardly depending opening
70, shown in
hidden lines in FIG. 22 and a subsequent upwardly depending opening 72. These
features
can be better seen in the section view of the lock housing 36 illustrated in
FIG. 21. In FIG.
21, bore 68 is illustrated with an opening 74 for insertion of a breakable pin
76 (see FIG.
7B). Further down bore 68 is another opening 78 for the insertion of a guide
pin 80 (see
FIG. 7A). Finally, the downwardly oriented opening 70 and upwardly oriented
opening 72
are illustrated as well as one opening 42 for attachment to the gage ring 20.
The downwardly
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CA 02522910 2000-09-29
oriented opening 70 accepts a dog 82. Its tapered up-hole and down-hole
surfaces 84 and 86
(see FIG. 18) are illustrated to be disposed at preferably an 80 degree angle
measured from
the lower end 88 of dog 82. Dog 82 sits in notch 90 on the mandrel 10 as shown
in FIG. 7A.
Notch 90 has tapered surfaces conforming to the tapered surfaces 84 and 86 of
dog 82. While
80 degrees is preferred, other angles can be used without departing from the
spirit of the
invention. The matching taper angles between the dog 82 and the receptacle 90
facilitate in
driving the dog 82 out of receptacle 90. In the run-in position shown in FIG.
7A, the dog 82
is retained by lock dog retainer 92. As show in FIGS. 7A and B, the lock dog
retainer 92
overlays the dog 82 holding it in the notch 90 on mandrel 10. Referring to
FIG. 16 which is
a top view of the lock dog retainer 92, an elongated slot 94 accepts the guide
pin 80 which
extends through the lock housing 36. In that manner, the guide pin 80 limits
the down-hole
movement of lock dog retainer 92. This concept is illustrated in FIG. 16 by
placement of
guide pin 80 in the slot 94 to illustrate that only movement up-hole or to the
left in FIG. 16 is
possible for lock dog retainer 92. Lock dog retainer 92 has a receptacle 96
shown in FIG. 16.
As shown in FIGS. 19 and 20, receptacle 96 accommodates tab 98 of lock dog
release 100.
In an important feature, the width of tab 98 is shorter than the length of
receptacle 96, thus
allowing for the possibility of relative motion therebetween. For the run-in
position, the lock
dog release 100 has a receptacle 102 (see FIGS. 19 and 20) which accepts pin
76, which in
turn extends through the lock housing 36. Thus, for run-in, the lock dog
release 100 is pinned
to the lock housing 36 and has a tab 98 inserted into receptacle 96 of lock
dog retainer 92.
FIG. 16 shows the maximum down-hole position of lock dog retainer 92 due to
the travel
limitation of guide pin 80 extending into slot 94. In the position shown in
FIG. 16, the tab 98
of lock dog release 100 is so positioned in receptacle 96 so as to be able to
move up- hole, i.e.
toward pin 80 for a limited distance before tandem movement of lock dog
release 100 and
lock dog retainer 92 occurs. The significance of the relative movement will be
explained
later.
Referring to the section view of the lock dog retainer 92 (FIG. 17), it can
also be seen
that it has an undercut 104 which is offset from dog 82 in FIGS. 7A and B, and
shifted to
coincide with dog 82 in FIG. 8. Those skilled in the art will appreciate that
when the
undercut 104 moves over the dog 82 the dog can be pushed out of notch 90, thus
allowing an
unlocking of the lock housing 36 from the mandrel 10. As previously explained,
when such
unlocking of the lock mechanism L occurs, the various springs 60 bearing on
their respective
retainers 62 collectively expand up hole, moving the spring housings 28 and
the lock housing
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CA 02522910 2000-09-29
36, along with gage ring 20 to which housings 28 and 36 are connected, which
has the
ultimate effect of pulling the slips 50 to set them.
In order to actuate the lock mechanism L to unlock and permit setting of the
slips 50 a
release device is required. In this instance, the release device comprises a
piston housing 106
which has internal passages which are best seen in FIG. 13. Passage 108
accepts a bolt 110
whose details are best shown in FIG. 12. Bolt 110 is placed over an opening
112 in the
mandrel 10. The piston housing 106 has a circular groove 114 which accepts a
sealing
member, such as an O-ring 116 (see FIG. 7B). With bolt 110 securing the piston
housing
106 about the opening 112, there is a sealed passage from inside the mandrel
10 through the
bolt 110, through its passage 118 (see FIG. 12). Passage 118 in bolt 110 is
sealingly aligned
to passage 120 in piston housing 106. Passage 120 leads to passage 122 within
which are
mounted a rupture disk 124 and a piston assembly 126 (see FIG. 7B).
FIG. 7B shows the rupture disk 124 adjacent the piston assembly I26 all within
the
passage 122 of the piston housing 106. The purpose of the rupture disk 124 is
to insure that a
certain minimum pressure is achieved in the mandrel 10 before internal
pressure in mandrel
is communicated to the piston assembly 126. The piston assembly 126 has a
central
passage 128 which can be sealed by a cap 130 in combination with a seal 132.
Externally,
the piston assembly 126 has a seal 134 to seal it in passage 122 for
reciprocal movement
therein. The cap 130 allows proper displacement of air or other gases from
passage 122 as
the piston assembly 126 is inserted into the passage 122. Upon insertion to
the position
shown in FIG. 7B, the trapped fluids are displaced through passage 128 until
the desired
position of the piston assembly 126 is reached. At that time, the cap 130 is
screwed on,
sealing off the piston assembly 126 in passage 122. Prior to installing the
piston assembly
126, the rupture disk 124 is inserted. The piston assembly 126 is thus free to
move in
opposed directions to compensate for thermal effects or other effects. As
shown in FIG. 7B,
there is a space between the piston assembly 126 extending out of the piston
housing 106 and
the lock dog release 100. This space can also be easily seen in FIG. 2. Those
skilled in the
art will appreciate that the piston housing 106 as well as the piston assembly
126 which is in
it, can be easily replaced with a different sized unit to accommodate these
specific down hole
conditions as they occur. Such replacements can be done in the field without
having to send
the tool back to the shop. What is simply done is that the bolt 110 is
loosened and a different
piston housing 106, having a bigger or smaller piston, or with a rupture disk
124 set to break
at a different value is easily insertible as a unit in replacement of the
original equipment.
Thus the bolt-on feature of the piston housing 106 holding the piston assembly
126 adds
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CA 02522910 2000-09-29
versatility to the apparatus A of the present invention and allows for field
changes to meet
last minute changes in well operating conditions where the apparatus A is to
be set. It also
facilitates the presence of passages 38.
In order to set the slips 50, pressure must be built up sufficiently within
the mandrel
to break the rupture disk 124. When the rupture disk 124 breaks, pressure is
then applied
to the piston assembly 126, moving the piston to the left as seen by comparing
FIGS. 7B and
8B. The piston assembly 126 first impacts the lock-dog release 100, pushing it
up hole. As
seen in FIG. 2, the lock- dog release 100 has a downwardly oriented tab 136
adjacent to an
opening 138. As shown in FIGS. 7A & B, the lock-dog release 100 is initially
retained by a
shear pin 76 or similar retaining device. The impact of the piston assembly
126 on the lock-
dog release 100 breaks the shear pin 76 and starts the lock-dog release 100
moving up hole.
It should be noted that at this time there is no movement of the lock-dog
retainer 92. As
previously explained, the receptacle 96 of the lock-dog retainer 92 (see FIG.
16) is longer
than the width of the tab 98 on lock-dog release 100. As a result, the energy
imparted into
the piston assembly 126 is initially expended solely to break the shear pin 76
without also, at
the same time, having a need to overcome the frictional resistance between the
lock-dog
retainer 92 and the dog 82, which it squeezes into notch 90. Those skilled in
the art will
appreciate that these movements occur almost instantaneously so that after the
shear pin 76 is
broken and the piston assembly 126 is moving in tandem with lock-dog release
100, the lock-
dog retainer 92 is eventually driven up hole as shown in FIG. 8A. This places
the undercut
104 (see FIG. 17) in alignment with dog 82. Further movement of lock-dog
retainer 92
allows springs 60 to push lock housing 36 which in turn forces tapered surface
84 of dog 82
along its parallel surface in notch 90 so that the dog 82 comes out of notch
90 to the final
position shown in FIG. 8A. It should be noted that as these movements are
occurring, the tab
136 pushes any mud out through opening 138 in lock- dog release 100.
Similarly, the uphole
movement of lock-dog retainer 92 forces any adjacent mud through the upwardly
oriented
opening 72 in the lock housing 36.
With the dog 82 out of notch 90, the spring housings 28 and lock housing 36
are no
longer held to the mandrel 10. At that point, the springs 60 in the various
spring housings 28
and the lock housing 36 can push off against their respective retainers 62,
thus moving uphole
all of the spring housings 28 and lock housing 36 along with gauge ring 20.
This upward
movement shown by a comparison of FIGS. 7 & 8 results in a pull upward on all
of the slips
50 which drives the slips 50 outwardly into a gripping engagement with the
tubular in the
well bore to set the apparatus A.
CA 02522910 2000-09-29
The method of securing the slips 50 to the respective slips seat 64 will now
be
described. Each of the slip seats 64 can be attached to the reduced diameter
segment 18 of
the mandrel 10 without welding. This is a distinct advantage to well operators
whose
requirements preclude welding as well as when certain materials are used
allowing the
affixation of the slip seat 64 to the mandrel 10 in conformance with
regulations that prohibit
welding, such as those promulgated by the National Association of Corrosion
Engineers
(NACE). The mandrel 10 is shown in more detain in FIGS. 27 through 29. As seen
in FIG.
27, each slip seat 64 is attachable to the mandrel 10 through a series of rows
of longitudinal
slots 140. Each individual slot 140 is shown in greater detail in FIG. 28. At
least one
opposed pair of slots, shown in FIG. 28, has a lateral opening 142, which is
designed to
accept a tab 144 (see FIG. 25) on the underside of the slip seat 64. The
various tabs on the
underside of the slip seat 64 are aligned with the longitudinal slots 140 and
more particularly,
the lateral openings 142. The slots 140 have elongated undercuts 146 such that
the tab 144
on the underside of the slip seat 64 can be first inserted into the lateral
opening 142 as shown
in FIG. 28 and then the slip seat 64 can be moved longitudinally with respect
to mandrel 10
to put the tabs 144 in an offset position from lateral opening 142. This
position is shown in
FIG. 27. Also shown in FIG. 27 is an opening 148 in the mandrel 10. Opening
148 is in fact
a depression in the outer surface of mandrel 10. Referring to FIG. 24, the
slip seat 64 has a
transverse lug 150 which fits into the opening 148 and mandrel 10. Opening 148
is
necessarily larger than the lug 150 so that upon insertion of tabs 144 and lug
150 into
respective openings 140 and 148 and translation of the slip seat 64 with
respect to the
mandrel 10, any load transmitted to the slip seat 64 goes into the mandrel 10
via transverse
lug 150 and aligned lugs 144. In essence, lugs 144 take a hanging load on
upper ends of slots
140 and take up a radial load on the sides of slots 140 while transverse lug
150 bears on the
upper end of opening 148. To finally fix the slip seat 64 to the mandrel 10, a
slip seat retainer
56 is inserted through an opening 152 in the slip seat 64 and further into a
notch 154 in the
mandrel 10 (see FIGS. 23 & 27). Each of the slip seat 64 are attached to the
mandrel 10
which does not deform the mandrel 10 in the identical manner. While a specific
non-welding
mode of attachment of slip seat 64 to mandrel 10 is disclosed, those skilled
in the art will
appreciate that other techniques for so joining those two components can be
utilized without
departing from the spirit of the invention.
Another feature of the apparatus A of the present invention is the manner in
which the
loading is transferred from the slip 50 to the slip seat 64 and into the
mandrel 10. Each
individual slip 50 transfers loading to the slip seat 64 which surrounds it,
whereupon the
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CA 02522910 2000-09-29
loading through the shape of the slip 50 is transferred into the wall of the
mandrel 10. There
is no interaction between one slip 50 and its slip seat 64 and any other slip
seat 64. The
loading is transferred from each slip 50 into the wall of mandrel 10 through
slip seat 64 rather
than radially toward the center of mandrel 10, which would be a force that
would tend to
deform or crush the mandrel 10. Referring specifically to FIGS. 23 and 14 and
15, it can be
seen that the edges 156 and 1S8 are preferably beveled with respect to the
plane of the paper
and there is a matching slope on surfaces 160 & 162 of the slip seat 64. Thus,
taking into
consideration the strength of the slip seat 64, the edge configuration of each
slip 50 along
surfaces 158 & 156 and the conforming surfaces on the slip seat 64 surfaces
160 & 162 are
such that the resultant force from loading a slip 50 is a force that is merely
close to tangential
to the wall which comprises the mandrel 10. In the preferred embodiment, the
angle is
approximately 80 degrees, putting the greatest component of force closer to
the tangential
direction into the wall which comprises the mandrel 10 with a smaller
component directed
radially toward the central of the mandrel 10. Such angles can be placed in
the slip 50 by
repositioning it during the machining process. As can be seen in looking at
FIG. 23, when
the upward pull comes to each of the slips 50, they are guided by surfaces 160
& 162 to move
radially outwardly to lock the apparatus A downhole, while at the same time,
independently
transferring load from each slip to its respective slip seat 64 through
surfaces 160 & 162
which are preferably at a slope of about 80 degrees resulting in the largest
component of
force being transferred into the mandrel 10 in a near tangential manner.
Those skilled in the art will now appreciate that the above-described
preferred
embodiment has numerous advantageous over tools in the prior art. The
apparatus A
employs a mechanical lock which prevents premature settings. It uses a bolt-on
piston
housing 106 which allows for field replacements to obtain different forces for
disabling the
mechanical lock. The rupture disk 124 requires a pre-determined pressure be
applied before
the lock mechanism L can release. The use of a bolt-on piston housing 106 also
helps reduce
the profile of the lock mechanism L and enables the provision of longitudinal
passages 38 for
the passage of mud and cement. The slips 50 are secured to slip seat 64 which
are, in turn,
connected to the mandrel 10 without welding. Each slip 50 is configured to
direct applied
loads into the mandrel 10 in a direction nearly approximating the tangential
or into the wall of
the mandrel 10. Thus there is less of a tendency to deform the mandrel as with
designs of the
prior art which simply move slips up cones. Additionally, as distinguished
from other slip
designs of the prior art, there is no interaction in sharing the load among
the slips 50. Each
slip individually distributes the load applied to it to the mandrel 10 through
the slip seat 64.
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CA 02522910 2000-09-29
The piston assembly 126 through the use of cap 130 allows venting of fluids
from passage
122 in the piston housing 106. The piston assembly 126 is free to move in both
directions to
react to thermal and other effects. The rupture disk 124 can be configured so
that it ruptures
at significantly higher pressures upon an excess of pressure in passage 122 as
opposed to its
normal operation where an increase in pressure from the mandrel 10 results in
breaking of the
rupture disk 124. Maximum use is made of the force generated by the piston
assembly 126
through the lost motion between the lock dog release 100 and the lock dog
retainer 92. Since
rotation of the apparatus A is possible, provisions have been made to retain
the arms 46
which are attached to the slips 50 against centrifugal force from such
rotation. The slip seat
retainer 56 accomplishes this function. Yet another new feature is the drop-in
arrangement
for the slip seat 64 into the slots 140 and opening 148. The dove- tail
arrangement also helps
to secure the slip seat 64 to the mandrel 10. The edge slopes on the slips 50
are designed to
avoid over-stressing the slip seat 64 while at the same time efficiently
communicating loads
on each slip 50 into the wall which defines the mandrel 10.
Referring now through FIGS. 30 through 36, an alternative embodiment is
described.
As shown in FIGS. 30 A through C, a mandrel 160 has a series of slips 162
retained in a
similar manner as previously described for the slips 50. What is different in
the alternative
embodiment can be seen in FIG. 33A where a passage 164 leads from internally
of the
mandrel 160 to a rupture disk 166. On the other side of the rupture disk 166
is a piston
assembly 168. These components operate in the identical manner as described
for the
comparable structure in the preferred embodiment. Looking at FIG. 32B, a
spring housing
170 is locked to the mandrel 160 by virtue of the fact that a split ring 172
extends into a
groove 174 in the mandrel 160. The split ring 172 also extends into a recess
176 in spring
housing 170. A spring 178 is shown in FIG. 32B. Those skilled in the art will
appreciate it
as one of many springs 178, each of which is guided by a guide 180. Referring
to FIG. 31,
the lower end 182 of the spring housing 170 has a recess 184 which accepts a
tab 186 which
is part of the structure of the slip 162. Accordingly, the spring housing 170
is operably
connected to all the slips 162 and has numerous springs 178 which will drive
all the slips 162
upward as the spring housing 170 moves upwardly once the split ring 172 is
moved out of the
way. This occurs when the split ring 172 is allowed to expand effectively out
of groove 174
thereby no longer restraining the spring housing 170 and thus allowing the
force of all the
springs 178 to move the slips 162 upwardly, thus distributing the load on each
of the slips
162 in the manner previously described for the preferred embodiment. The split
ring 172 is
shown in FIG. 34. It has a pair of opposed shoulders 188 & 190 which are
tightly squeezed
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CA 02522910 2000-09-29
together by a yoke 192 (shown in FIG. 35). Yolk 192 has a pair of opposed
surfaces 194 &
196 which engage surfaces 190 & 188 respectively to hold the position of the
split ring I72 to
a diameter sufficiently small so that it can effectively serve as an anchor
when fixed in
groove 174. The release simply occurs by a pressure buildup in the mandrel 160
which is
communicated through passage 164 to break rupture disk 166 which in turn
actuates the
piston assembly 168. The piston assembly 168 engages a connecting rod 198
which is
fixedly secured to the yoke 192. When the surfaces 194 & 196 on yoke 192 are
displaced
from the surfaces 190 & 188 on split ring 172, the split ring 172 can expand
radially
outwardly, thus defeating the lock of the spring housing 170 to the mandrel
160. When this
occurs, the springs 178 can bias the spring housing 170 upwardly, thus taking
up all the slips
162 and securing the apparatus A while distributing the load into the mandrel
160 in the
manner previously described.
Yet another feature of the alternative embodiment can be seen from FIGS. 31 &
36.
As shown in FIG. 36, a flow channel 200 on the back side of each slip 162
allows mud or
cement flow underneath to permit circulation of such materials during the
normal operation
of the apparatus A. This is significant in this particular design because it
does not have the
feature of the longitudinal passages 38 as in the preferred embodiment.
However, in common
with the preferred embodiment, pressure in the mandrel 160 results in defeat
of a lock
mechanism (in this embodiment the split ring 172). The slips 162 are
independently set with
the spring force from springs 178. This mode of operation is to be contrasted
with that
revealed in U.S. Patent No. 5,417,288 where the pistons actuate a ring which
is directly
connected to the slips. Thus, in that design the hydraulic pressure actually
moves the slips
whereas in this alternative embodiment, as well as in the preferred
embodiment, the applied
hydraulic pressure, without breaking any components other than a rupture disk
such as 124
and shear pin 76, results in the release of a mechanical lock which allows the
independent
operation of the setting of the slips 50. Again, comparing to the previous
technique of U.S.
Patent 5,417,288, numerous passages have to be drilled in the mandrel. More
specifically,
two passages were needed for each slip to operate it. Here, a single passage
is presented
through the mandrel 160 to operate the connecting rod 198 so as to release the
split ring 172
from the groove 174 thus allowing independent mechanical actuation using
spring force to set
the slips 162.
Referring to FIG. 36a, one alternative embodiment of the liner hanger is
composed of
a mandrel 201 which has a lower end 217. The lower end is shown schematically
and those
skilled in the art will appreciate that the liner string is connected at the
lower end 217. The
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mandrel 201 has an upper end 216 which, to those skilled in the art will
appreciate, is
attached to a running tool for proper positioning and securing of assembly S
shown in FIGS.
36a through 38.
Referring to FIG. 36a, a piston assembly 202 is secured to the mandrel 201
using a
bolt 110 previously described. Secured loosely by the piston assembly 202, is
a lock bar 203,
which connects to the snap ring 204, which extends into a recess 205 (FIGS. 39
and 40) on
the mandrel 201, and is retained in place by a breakable pin 206. The pusher
sleeve 207 is
biased against the snap ring 205 through the t-slot segment 212, which is
biased by the slip
50, which is biased by the spring 60 through the spring guide 62.
One alternative embodiment of the piston housing 223 can best be seen in FIG.
39 in
the run- in and FIG. 40 in the set position, where the end of the piston
housing 223 has been
extended to present a cover 218 over the lock bar 203 to prevent shifting of
the lock bar 203
by means other that the piston 126. The lock bar 203 is similar to the yoke
192 in that it
combines the yoke 192 and the connecting rod 198 from the previous
description. The lock
bar 203 has a pair of opposed surfaces 219 & 220 (FIG. 42) which hold the
opposed
shoulders 212 & 222 (FIG. 43) respectively of the snap ring 204 and secure the
snap ring 204
in the recess 205 in the mandrel 201. This method demonstrates that the snap
ring 204 can be
restrained from the top or the bottom without departing from the spirit of the
invention.
Another alternative embodiment of the piston housing 223 is that it can be
mounted
on a milled flat FIG. 41 on the mandrel, verses mounting on a curved surface
FIG. 6 of the
mandrel 201 & 10 without departing from the spirit of the invention.
The alternative embodiment of the slip seat 209, where the springs 60 are
contained in
the slip seat 209 and bias the slips from the bottom, indirectly through a
collection of parts,
against the snap ring 205 and lock bar 203, also demonstrates that the slips
50, can be pushed
versus pulled, to set the slips 50 without departing from the spirit of the
invention.
Further modifications to the equipment and to the techniques described herein
should
be apparent from the above description of these preferred embodiments.
Although the
invention has thus been described in detail for a preferred embodiment, it
should be
understood that this explanation is for illustration, and that the invention
is not limited to the
described embodiments. Alternative equipment and operating techniques will
thus be
apparent to those skilled in the art in view of this disclosure. Modifications
are thus
contemplated and may be made without departing from the spirit of the
invention, which is
defined by the claims.
