U.S. patent application number 10/635383 was filed with the patent office on 2004-03-25 for locking apparatus with packoff capability.
This patent application is currently assigned to Baker Hughes Incorporated. Invention is credited to Beall, Clifford H..
Application Number | 20040055757 10/635383 |
Document ID | / |
Family ID | 31998153 |
Filed Date | 2004-03-25 |
United States Patent
Application |
20040055757 |
Kind Code |
A1 |
Beall, Clifford H. |
March 25, 2004 |
Locking apparatus with packoff capability
Abstract
A well tool locking apparatus compatible with high temperature,
high pressure well conditions comprises a packing ring mandrel that
carries a sliding locking dog cage. The locking dogs are expanded
radially into a tubing nipple channel by the axial translation of a
ramped step on the mandrel surface. Chevron ring packing seals are
positioned between the locking dog cage and an abutment shoulder
around the mandrel. Translation of the mandrel against the locking
dog cage engages the tool locking dogs and expands the chevron ring
seal against the inside bore surface of the tubing nipple. The
locked and sealed position is held by buttress threads on the
mandrel engaged with a body lock ring
Inventors: |
Beall, Clifford H.; (Broken
Arrow, OK) |
Correspondence
Address: |
PAUL S MADAN
MADAN, MOSSMAN & SRIRAM, PC
2603 AUGUSTA, SUITE 700
HOUSTON
TX
77057-1130
US
|
Assignee: |
Baker Hughes Incorporated
Houston
TX
|
Family ID: |
31998153 |
Appl. No.: |
10/635383 |
Filed: |
August 6, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60413037 |
Sep 24, 2002 |
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Current U.S.
Class: |
166/382 ;
166/115; 166/125 |
Current CPC
Class: |
E21B 23/02 20130101 |
Class at
Publication: |
166/382 ;
166/115; 166/125 |
International
Class: |
E21B 023/00 |
Claims
1. A locking apparatus that is releasably securable within a
landing nipple of a tubing string, the locking apparatus
comprising: a tool housing with an associated inner mandrel; a
locking member that is radially moveable with respect to the tool
housing, the locking member being selectively disposable into a
landing nipple receptacle to secure the locking apparatus within
the tubing string; a packing seal retained upon the inner mandrel,
the packing seal being axially compressible; and a compression
member associated with the tool housing for selective axial
compression of the packing seal to urge the packing seal into
sealing engagement with the tubing string.
2. The locking apparatus of claim 1 wherein the tool housing is
interconnectable with well control tools.
3. The locking apparatus of claim 1 wherein the compression member
is actuated to compress the packing seal by axially translating the
inner mandrel with respect to the tool housing.
4. The locking apparatus of claim 1 wherein the packing seal
comprises a chevron packing seal member.
5. The locking apparatus of claim 1 wherein the packing seal
comprises a multiple chevron seal members in a stacked
configuration.
6. The locking apparatus of claim 1 further comprising a locking
dog cage and wherein the locking member comprises a locking dog
that is urged radially outwardly through a slot in the locking dog
cage.
7. The locking apparatus of claim 6 wherein the compression member
comprises a ram end of the locking dog cage.
8. The locking apparatus of claim 1 wherein the packing seal
comprises a dynamic seal assembly.
9. A locking apparatus that is releasably securable within a
landing nipple of a tubing string, the locking apparatus
comprising: a tool housing with an associated inner mandrel; a
locking member that is radially moveable with respect to the tool
housing, the locking member being selectively disposable into a
landing nipple receptacle to secure the locking apparatus within
the tubing string; a packing seal retained upon the inner mandrel,
the packing seal being axially compressible; a compression member
associated with the tool housing for selective axial compression of
the packing seal to urge the packing seal into sealing engagement
with the tubing string; and a locking dog cage and wherein the
locking member comprises a locking dog that is urged radially
outwardly through a slot in the locking dog cage.
10. The locking apparatus of claim 9 wherein the compression member
is actuated to compress the packing seal by axially translating the
inner mandrel with respect to the tool housing.
11. The locking apparatus of claim 9 wherein the packing seal
comprises a chevron packing seal member.
12. The locking apparatus of claim 9 wherein the packing seal
comprises a multiple chevron seal members in a stacked
configuration.
13. The locking apparatus of claim 9 wherein the packing seal
comprises a dynamic seal assembly.
14. The locking apparatus of claim 9 wherein the compression member
comprises a ram end of the locking dog cage.
15. A method of securing a locking apparatus within a tubing string
comprising the steps of: disposing the locking apparatus within a
tubing string to a location adjacent a landing nipple; moving a
locking member radially outwardly from the locking apparatus and
into locking engagement with a landing nipple receptacle; and
axially compressing a packing seal on the locking apparatus to urge
the packing seal radially outwardly into sealing engagement with
the tubing string.
16. The method of claim 15 further comprising the step of securing
the locking apparatus to at least one well control tool prior to
disposing the locking apparatus in the tubing string.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the priority of U.S.
Provisional application serial No. 60/413,037 filed Sep. 24,
2002.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to tools for developing and
producing fluids from subterranean wells. More particularly, the
invention is a wireline or coiled tube positioned locking apparatus
for securing the position of a production tube flow control or
measurement tool in a landing nipple located in a tubing string
having a profile and seal bore specifically prepared to accept the
locking apparatus with packing.
[0004] 2. Description of Related Art
[0005] A prior art procedure for placing and securing a
subterranean well tool at a predetermined position within a well
production tube is a special purpose locking apparatus having a
collet or locking dogs that are mechanically actuated by surface
manipulated wirelines or coiled tubing. Usually, the locking tool
is attached to the top of the well tool or instrument and to a
wireline running tool. The assembly is lowered into the well at the
end of the wireline to the desired depth and location. Radially
expandable locking dogs or collets are actuated, for example, by
wireline manipulation to engage or mesh with cooperative surfaces,
receptacles or profiles within the tubing.
[0006] A common method of positioning a subterranean well tool
within a well conduit, such as a tubing string, is to insert a
locking apparatus in a landing nipple, the landing nipple being
pre-installed at a particular location within the tubing string and
containing a profile into which the locking apparatus may engage.
The locking apparatus will normally no-go on a shoulder of the
landing nipple and will have means of locking into the profile of
the landing nipple using outward expanding members such as dogs or
collets.
[0007] Normally associated with the locking apparatus is a set of
chevron packing rings to provide a seal between the landing nipple
and a well tool attached to the locking apparatus, such as a
blanking plug or safety valve. Typically, the packing is positioned
in a polished seal bore of the landing nipple, between two fixed
limiting shoulders on the locking apparatus and a well tool such as
a blanking plug or safety valve. Unfortunately, however, it is not
unusual for the seal bores of the landing nipple to be damaged in
the well either by wireline cutting (longitudinal grooves) or by
general corrosion. Prior art locking devices have not provided a
mechanism or procedure to apply axial compressive loading of the
packing to improve sealing by extrusion into such grooves pits or
imperfections.
[0008] U.S. Pat. No. 4,295,528, for example, is a patent for a
"Selective Lock with Setting and Retrieving Tools." Element 104 in
FIG. 2c of this '528 patent represents a chevron packing unit or
assembly installed on the mandrel of the wireline lock in a typical
manner. The purpose of the chevron packing is to provide a seal
between the mandrel and the seal bore in a landing nipple. However,
the chevron packing material is only confined between two fixed
shoulders at each end of the packing and has no capacity for
operational adjustment.
[0009] Similar fixed or static shoulder confinements for chevron
seals are disclosed in U.S. Pat. Nos. 4,315,544; 4,510,995;
4,583,591; and 4,823,872. U.S. Pat. Nos. 4,406,324 and 4,993,493
also disclose oilfield equipment that employs chevron packing
located between two fixed shoulders. The chevron packing is landed
either on the lock mandrel or the tool attached to the lock mandrel
and is always trapped between two fixed shoulders that position and
confine the chevron packing rings but does not compress them.
[0010] Somewhat different in concept is the locking device
described in U.S. Pat. No. 5,348,087 which can actually have a seal
bore larger than the internal diameter of the tubing string. The
locking device contains an elastomeric packing element located on a
mandrel. The mandrel contains an enlarged diameter portion which,
when driven beneath the packing element, causes the packing element
to expand radially and engage the seal bore of the nipple. Due to
relative movement of the mandrel, the expanding metal rings on each
side of the packing element can not be considered fixed until after
the lock is set. After the lock is set, however, they essentially
become fixed with respect to the packing element and there is no
provision for applying or increasing the end load on the packing
element of this device as a means for improving the sealing.
[0011] It is, therefore, an object of the present invention is to
provide a locking apparatus having the ability to apply axial
compressive loading on a chevron packing or other packing
configuration associated with the locking apparatus.
[0012] Another object of the present invention is a means to
improve the sealing ability of locking apparatus packing under
adverse condition such as mechanical or chemical corrosion damage
to seal the bore of the landing nipple or other adverse sealing
condition such as high pressure and high temperature.
[0013] Also an object of the present invention to provide a locking
apparatus having the ability to apply an axial compressive load to
the chevron packing to improve sealing of the packing using
conventional wireline manipulation means.
[0014] Another object of the present invention is locking apparatus
mechanism having the capacity to apply an axial end load to the
chevron seal packing thereby forcing the packing material into
grooves or other imperfection in the seal bore of the landing
nipple to effect a seal when otherwise, the seals would leak.
[0015] Also an object of the invention is provision of an ability
to apply an axial compressive load to locking apparatus chevron
seals to aid in sealing the tubing bore under high pressure, high
temperature applications, even when the seal bore in the landing
nipple is perfect.
[0016] An additional object of the invention is to provide the
means of applying additional axial compressive loading in a
remedial action to shut off an existing leak using normal wireline
manipulation means.
SUMMARY OF THE INVENTION
[0017] The invention provides an ability to apply a compressive,
axial loading on the chevron packing to expand the packing material
radially thereby forcing the chevron packing material into the
grooves, pits or other imperfections in the seal bore of the
landing nipple and thereby effecting a seal when otherwise, the
seal would leak.
[0018] To these ends, the present well tool locking connector
includes an interior packing mandrel having a first cylindrical
surface that carries a compression expanded packing ring that is
axially confined along the packing mandrel first surface by an
compression abutment shoulder. An axial extension of the packing
mandrel transitions over a ramped shoulder onto a second, lesser
diameter cylindrical surface. At least a portion of the second
cylindrical surface extended from the ramped shoulder is profiled
with directionally biased channels such as buttress threads. A body
lock ring having a correspondingly profiled I.D. meshes with the
packing mandrel surface profile.
[0019] Further along the packing mandrel extension from the ramped
shoulder and the meshed locking ring is a fishing tool connection
surface such as a locking dog receptacle detent or channel or a
fishing barb ring.
[0020] Between the fishing tool connection surface and the meshed
locking ring, a control sleeve slidably overlies the packing
mandrel extension. The control sleeve also includes a fishing tool
connection surface such as that used for the packing mandrel,
preferably. Distal from the fishing tool connection, the control
sleeve includes an abutment shoulder band having an O.D. shoulder
in facing proximity with the fishing tool connection and an I.D.
shoulder in facing proximity with the locking ring. The I.D.
shoulder of the control sleeve is axially recessed from a retaining
ring abutment shoulder.
[0021] A locking dog caging sleeve slidably overlaps the first
cylindrical surface of the packing mandrel and the control sleeve
abutment shoulder band. An end of the caging sleeve lapped upon the
first cylindrical surface of the packing mandrel proximate of the
packing ring is a compression ram. An opposite distal end of the
caging sleeve includes a I.D. abutment shoulder in facing proximity
with the O.D. abutment shoulder of the control sleeve. One or more
locking dogs are confined by caging slots in the caging sleeve. A
radially expandable retaining ring provides a preset connection
between the body lock ring and the caging ring.
[0022] A preset alignment of the tool components is secured by
calibrated shear fasteners. Such preset alignment provides a
retracted position for the locking dog or dogs and an uncompressed
packing ring for well run-in. When suspended at the end of a
suitable suspension structure such as a wireline or coiled tubing,
for location within a well, the fishing tool engagement surfaces
respective to the packing ring mandrel and the control sleeve are
axially separated by a first manipulation of the suspension
structure to translate the packing ring mandrel relative to the
caging sleeve and the control sleeve. This translation draws the
ramped shoulder of the mandrel under or in radial contiguity with
the locking dog thereby causing a radial displacement of the
locking dog or dogs into a well tubing receptacle or detent
channel. Simultaneously, the packing ring is compressed between the
mandrel compression shoulder and the ram end of the caging sleeve.
Such compression expands the sleeve radially to a pressure sealing
engagement with the inside bore wall of the well tube.
[0023] When the packing mandrel is drawn against the control
sleeve, the buttress threads are translated under the lock body
ring to rectify the movement and secure the compressed
position.
[0024] At this point, the tool connector is locked and sealed with
the tubing bore. The suspension structure may be released from the
fishing tool connection surfaces and withdrawn from the well for
replacement by other tools, if desired.
[0025] When release of the well tool from the tubing is desired,
fishing tools reengage the mandrel and control sleeve. A second
manipulation of the suspension structure translates the control
sleeve from abutted engagement of the respectively facing abutment
surfaces. This translation of the control sleeve also extracts a
spacing hood portion of the control sleeve from between the
retaining ring and the caging sleeve thereby permitting it to
expand out of linkage engagement between the lock ring and the
caging sleeve. A third manipulation of suspension structure
translates the first cylindrical surface of the mandrel from under
the locking dog or dogs thereby permitting a radial retraction of
the dog from the tubing channel. The same mandrel translation
decompresses the packing ring.
BRIEF DESCRIPTION OF DRAWINGS
[0026] For a thorough understanding of the present invention,
reference is made to the following detailed description of the
preferred embodiments, taken in conjunction with the accompanying
drawings in which like reference characters designate like or
similar elements throughout the several figures of the drawing.
[0027] FIG. 1 is a sectioned view of a locking apparatus in
operative assembly with a running tool set for well run-in.
[0028] FIG. 2 is a sectioned view of a locking apparatus in
operative assembly with a running tool in an intermediate well
setting condition.
[0029] FIG. 3 is a sectioned view of a locking apparatus in
operative assembly with a running tool in a set and sealed
condition within a well production tube.
[0030] FIG. 4 is a sectioned view of a locking apparatus in
operative assembly with a running tool where the locking apparatus
is in a set and sealed condition and the running tool is released
from the locking apparatus.
[0031] FIG. 5 is an enlarged sectioned view of the locking
apparatus configured for well run-in.
[0032] FIG. 6 is an enlarged sectioned view of the locking
apparatus configured for a locked and sealed setting within a well
production tube.
[0033] FIG. 7 is an enlarged sectioned view of the locking
apparatus configured for release from a well production tube.
[0034] FIG. 8 is an enlarged sectioned view of the packing seal
portion of the locking apparatus.
[0035] FIG. 9 is an enlarged sectioned view of an alternative
packing seal assembly.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0036] A first embodiment of the invention is represented by FIG. 1
to include a running tool 10 attached to a wireline lock 20. The
running tool 10 comprises An inner mandrel 12 that may be a
threaded assembly of several sections to provide a structurally
continuous tube element that extends between a threaded box end 13
and a threaded pin end 14. Optionally, the pin end may also include
a fishing neck 15. A running tool housing 30 is releasably secured
to the mandrel 12 by a calibrated failure element such as a shear
pin 32. The housing 30 is secured to the mandrel 12 at such a
position as to provide translational space 62 between the sleeve
end 35 and a mandrel abutment shoulder 64. The translational space
62 is covered by a housing extension sleeve 36. Opposite from the
extension sleeve 36, the housing further includes a control dog
housing 66. The control dog housing has a control dog detent
channel 37 for cooperation with a control dog element 38.
Additionally, the control dog housing provides a multiplicity of
caging slots 41 for fishing neck dogs 40.
[0037] When free of the locking dog 38, the control dog housing 66
may slidably translate along a spring mandrel 16. A compression
spring 17 is seated between the shoulder 68 on the control dog
housing 66 and the spring seat shoulder 18 on the spring mandrel
16. The bias of spring 17 is to separate the respective spring
seats and translate the spring mandrel end 70 into the space
72.
[0038] The outside perimeter of the inner mandrel 12 is profiled to
provide a locking dog retraction channel 75 on one side of a
locking dog support band 77 and a ramped shoulder 79 on the other
side.
[0039] The inside perimeter of the spring mandrel 16 is profiled to
provide a ramped shoulder 80 to cooperatively engage the ramped
shoulder 79 on the inner mandrel 12. The outside perimeter of the
spring mandrel 16 is also profiled with a ramped shoulder 82 for
cooperative engagement with a corresponding inside shoulder ramp 90
near the end of the control dog housing 66.
[0040] Respective to FIGS. 1 and 5, the primary structural element
of the locking apparatus 20 is the packing mandrel 22 which
includes the mandrel sleeve extension 25. The packing mandrel
directly supports a chevron packing 28 against a compression
shoulder 84. One or more shear pins 34 releasably secure the
packing mandrel 22 to the running tool spring mandrel 16. Box
threads 27 secure the locking apparatus to additional elements of
the tool assembly that are to be secured within the production
tube. The inside perimeter of the packing mandrel sleeve extension
25 accommodates a fishing tool connection channel 44.
[0041] With respect to FIG. 5, the outer profile of the mandrel
sleeve extension 25 is stepped to provide an elongated groove
channel between an abrupt shoulder 86 and a ramped shoulder 88 on
the packing mandrel 22. Between the shoulders 86 and 88, the
outside surface of the ring channel is grooved by, for example,
buttress threads or rings 48. A lock ring 56 has corresponding
buttress threads around its inside circumference to mesh with the
threads 48. The lock ring 56 is an expansible hoop spring that will
accommodate radial expansion to advance axially in one direction
over the buttress threads 48 but opposes movement in the opposite
axial direction.
[0042] A control sleeve 46 is slidably confined within the groove
extension channel between the abrupt shoulder 86 and the lock ring
56. The end of the control sleeve proximate of the abrupt shoulder
86 has a threaded connection with a lock assembly sleeve 23 whereby
both elements function dynamically as an integral structure.
[0043] The control sleeve 46 also includes a hood extension 49 that
projects over the lock ring 56. The hood extension 49 includes a
counterbored shoulder that confines a retainer ring 58 against an
end shoulder of a locking dog cage 52. The retainer ring 58 is an
expansible hoop spring that is biased to expand against the inside
surface of the hood extension 49.
[0044] An extension 54 of the locking dog cage 52 laps over the
control sleeve 46 and the hood extension 49. The distal end of the
cage extension 54 is rimmed to provide an outside abutment face 55
and an inside abutment shoulder 57. The locking dog cage 52 laps
onto the outside packer seal surface of the packer mandrel 22 to
cover a translational space 59 between the ramped shoulder 88 of
the of the mandrel 22 and the lock ring 56. Within the locking dog
cage 52 are a plurality of locking dogs 50 that are confined by
slots to radial movement into and out of the translational space
59. A corresponding translational space 96 is provided between the
inside abutment shoulder 57 and a control sleeve shoulder 47. A
calibrated failure fastener 60 such as a shear screw secures an
initial axial relationship between the locking dog cage 52 and the
control sleeve 46. A safety fastener 24 between the lock assembly
sleeve 23 and the packing mandrel sleeve 25 also provides alignment
security during transport to the well location. The safety fastener
24 is removed, however, after the locking apparatus 20 is assembled
to the running tool but before it is inserted in the well.
[0045] Preparatory to well descent, the wireline lock tool 20 is
assembled with the running tool 10 in the manner illustrated by
FIG. 1. The inner mandrel 12 of the running tool is secured to the
sleeve 35 end of the housing 30 by the upper shear pin 32. An end
thread on the mandrel 12 secures it to a tool joint pin 14 to
facilitate connection of the assembly to a well suspension
structure such as a wireline or coiled tubing.
[0046] The spring mandrel 16 is aligned along the inner mandrel 12
length to position the locking dog support band 77 under the
control dog 38 thereby meshing the control dog 38 into the detent
ring 37 in the control dog housing 66. This meshing of the control
dog 38 in the housing 66 detent ring 37 immobilizes the spring
mandrel 16 with the housing 30 and hence, due to the upper shear
pin 32, with the inner mandrel 12.
[0047] The lower end of the running tool 10 penetrates the central
bore of the locking apparatus 20 to receive the lower shear pin 34
through the spring mandrel 16. This calibrated shear failure
assembly is supplemented by the meshed engagement of the fishing
neck dog 40 with the detent channel 42 in the lock assembly sleeve
23. The meshed engagement of the fishing neck dog 40 is supported
by the outside surface of the spring mandrel 16.
[0048] Before the assembly enters the wellhead, the safety fastener
24 is removed. The locking apparatus 20 remains mechanically linked
to the running tool 10 by the fishing neck dog 40 and the lower
shear pin 34.
[0049] Upon alignment with the desired downhole location, the
assembly is "jarred" to shear the upper shear pin 32. That event
allows the running tool housing 30 to translate along the inner
mandrel 12 and close the translational space 62 as illustrated by
FIG. 2. This axial downward shifting of the inner mandrel 12 with
respect to the housing 30 also translates the control dog support
land 77 downward out from underneath the control dogs 38 allowing
the control dogs 38 to drop into the locking dog retraction channel
75. Alignment of the control dog 38 with the retraction channel 75
allows the control dog 38 to be radially displaced within the
control dog cage of the spring mandrel 16 and out of the detent
channel 37 in the control dog housing 66.
[0050] Retraction of the control dogs 38 from the control dog
housing 66 releases the spring mandrel 16 relative to the housing
30 but does not release the spring mandrel from the packing mandrel
22 of the locking apparatus 20 due to the lower shear pin 34.
Support linkage is also maintained by the fishing neck dog 40
engagement with the detent channel 42 in the lock assembly sleeve
23 and the abutment of shoulders 82 and 90 on the spring sleeve and
control dog housing, respectively.
[0051] Furthermore, the control dog housing 66 is biased downward
against the lock assembly sleeve 23 while the spring mandrel 16,
connected by lower shear pin 34 to the packing mandrel 22, is
biased upward, both due to the urging of the compression spring 17.
Consequently, when the control dogs 38 are released from the
control dog housing 66, the upward bias of the spring mandrel 16
lifts the packing mandrel 22 while holding the lock assembly sleeve
23 down thereby causing a compressive closure between the packing
mandrel 22 and the locking dog cage 52 shown by FIG. 3. As the
ramped shoulder 88 of the packing mandrel 22 engages with the
locking dogs 50, the locking dogs are radially displaced into a dog
receptacle channel 102 in the landing nipple 100 component of the
well fluid production tube thereby securing the locking apparatus
20 to the landing nipple 100 by a mechanical interference as is
illustrated by FIGS. 3 and 4.
[0052] Continued expansion of the spring 17 by compression of the
packing ring 28 displaces the spring mandrel 16 relative to the
control dog housing 66 until the support land 92 portion of the
spring mandrel 16 passes from under the fishing neck dog 40. As the
ramped shoulder 82 passes the fishing neck dog 40 (FIG. 6), the dog
40 drops from the detent channel 42 thereby releasing the running
tool 10 from the locking apparatus at that point. However, the
shear pin connection 34 between the spring mandrel 16 and the
packing mandrel 22 remains.
[0053] With the locking apparatus thus secured to the landing
nipple, additional upward jarring movement of the inner mandrel 12
as shown by FIG. 4 causes the upward facing bevel at the lower end
of the control dog retraction channel 75 to engage the inner bevel
of the control dogs 38. With the inner mandrel 12 in physical
abutment with the control dogs 38, such subsequent upward jarring
shears the lower shear pin 34 to complete the release of the
running tool 10 from the locking apparatus 20. Before the running
tool release sequence is complete, however, the process imposes
maximum compressive load against the chevron packing ring 28
between the ram end 53 of the locking dog cage 52 and the
compression shoulder 84 of the mandrel 22. When compressed axially,
the packing ring expands radially out to a pressure sealed
engagement with the landing nipple I.D. 104. Upon shear failure of
the pin 34, the running tool 10 is released from the locking
apparatus 20 and may be removed from the well.
[0054] Also before the release sequence is complete, as the packing
mandrel 22 is drawn against the relatively fixed position of the
locking dogs 50 and cage 52, the sleeve 25 also advances the
buttress threads 48 on the outer surface of the packing mandrel
sleeve 25 under the lock ring 56. FIG. 6. As long as the retainer
ring 58 remains engaged with the lock ring 56, displacement of the
packing mandrel 22 relative to the locking dog cage 52 and control
sleeve 46 is unidirectional. The buttress thread bias between the
mandrel threads 48 and lock ring 56 prevents a reverse movement.
Hence, the locking dogs 50 and packer seal 28 are secured at the
engagement position with the landing nipple 100.
[0055] Displacement of the packing mandrel sleeve 25 relative to
the control sleeve 46 also opens a translational space 87 shown by
FIG. 6 between the abrupt shoulder 86 on the packing mandrel sleeve
25 and the stepped end of the control sleeve 46. This translational
space 87 will come into use for eventual retrieval of the locking
apparatus 20
[0056] Retrieval of the locking tool may be accomplished by a
fishing tool not illustrated but of construction and operation as
is well known to the prior art. In particular, such fishing tools
have two or more sets of axially translated fishing dogs carried by
either a wireline or continuous tube workstring. Such fishing dogs
are of common use in the industry.
[0057] Applied to the present invention, one set of such fishing
dogs is manipulated to engage the outer detent channel 42 in the
lock assembly sleeve 23. An inner fishing dog set engages the inner
detent channel 44 in the packing mandrel sleeve 25. The lock
assembly sleeve 23 has a threaded connection to the control sleeve
46 and when translated by force exerted by the outer fishing dog
set on the outer detent channel 42, the screw 60 that links lock
assembly sleeve 25 to the packing mandrel sleeve 25 fails and the
control sleeve shoulder 47 is shifted against the inside abutment
shoulder 57 on the end of the cage extension 54.
[0058] Translation of the control sleeve 46 withdraws the radial
structure support of the hood extension 49 from the retainer ring
58 as shown by FIG. 7. Consequently, the retainer ring expands
against the inside diameter of the cage extension 54. When
expanded, the retainer ring 58 no longer links the locking dog cage
52 to the lock ring 56 and the packing mandrel sleeve 25. Hence,
the packing mandrel sleeve 25 may be shifted by force applied with
inner fishing dogs to the inner detent channel 44. This packing
mandrel shift is oriented toward axial separation of the
compression shoulder 84 from the ram end 53 of the locking dog cage
52. Hence, the seal surface 26 supporting the locking dogs 50
engagement with the landing nipple 100 is withdrawn and the locking
dogs 50 are radially free to contract against the O.D. surface of
the packing mandrel 22. Consequently, the locking apparatus 20 is
released from mechanical interference engagement with the landing
nipple 100 and may be withdrawn from the well.
[0059] FIG. 8 is a close-up view, depicting in greater detail the
packing sleeve 28 of the locking apparatus 20. As shown, the
packing sleeve 28 includes a pair of metal end rings 110, 112 at
either axial end, and a central metal ring 114. A stack of
elastomeric chevron rings 116, 118 is disposed axially between each
of the end rings 110, 112 and the central ring 114. Each of the
chevron rings 116, 118 has a peaked, generally V-shaped
cross-section that is apparent from FIG. 8. When the ram end 53
compresses the packing sleeve 28, the chevron rings 116, 118 are
flattened out such that the peaked V in their cross-section is
substantially removed.
[0060] FIG. 9 is an enlarged cross-sectional view of portions of
locking device 20 incorporating an alternative axially compressible
seal assembly 120 for use as packing sleeve 28. The compressible
seal assembly 120 is known commercially as a "Dynamic Seal
Assembly" available from Baker Hughes Incorporated. As the
structure and function of this seal assembly is well known, it will
not be described here. Other suitable seal assemblies may also be
utilized as or within the packing sleeve 28 in accordance with the
present invention, including seal assemblies that incorporate, for
instance, axially compressible hat rings and/or U-cups.
[0061] The preferred invention embodiment has been described to
function with expanding dog fishing tools to engage the detent
channels 42 and 44. Those of skill in the art will understand that
external fishing connectors that accept and connect with overshot
fishing tools may obviously be substituted for the internal
connectors 42 and 44.
[0062] Although the invention has been described in terms of
particular embodiments which are set forth in detail, it should be
understood that this is by illustration only and that the invention
is not necessarily limited thereto. Alternative embodiments and
operating techniques will become apparent to those of ordinary
skill in the art in view of the present disclosure. Accordingly,
modifications of the invention are contemplated which may be made
without departing from the spirit of the claimed invention.
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