U.S. patent application number 10/116772 was filed with the patent office on 2003-10-09 for releasing mechanism for downhole sealing tool.
This patent application is currently assigned to Weatherford/Lamb, Inc.. Invention is credited to Eldridge, William J., Ingram, Gary D., Nguyen, Thomas, Ritter, Michael G., Turley, Rocky A., Zimmerman, Patrick J..
Application Number | 20030188860 10/116772 |
Document ID | / |
Family ID | 28674062 |
Filed Date | 2003-10-09 |
United States Patent
Application |
20030188860 |
Kind Code |
A1 |
Zimmerman, Patrick J. ; et
al. |
October 9, 2003 |
Releasing mechanism for downhole sealing tool
Abstract
A releasing mechanism for releasing a hydraulically actuated
setting tool from a downhole tool is provided. Preferably, the
downhole tool to be released is a wellbore sealing tool such as a
bridge plug, packer or inflatable packer. The releasing mechanism
comprises an adapter having a body, a connector above the body
connected to the setting tool, and a lower portion. The releasing
mechanism further comprises a releasable connection which
releasably connects the lower portion of the adapter to a mandrel
within the bridge plug or other sealing tool. In one embodiment,
the releasable connection defines a frangible body disposed within
the plane of the circumferential bore of the bridge plug mandrel.
In another arrangement, the releasable connection defines both a
frangible body and threaded collet fingers which releasably engage
matching threads on the outer surface of the mandrel of the bridge
plug or other wellbore sealing tool.
Inventors: |
Zimmerman, Patrick J.;
(Houston, TX) ; Turley, Rocky A.; (Houston,
TX) ; Eldridge, William J.; (Cypress, TX) ;
Ritter, Michael G.; (Conroe, TX) ; Ingram, Gary
D.; (Richmond, TX) ; Nguyen, Thomas; (Houston,
TX) |
Correspondence
Address: |
MOSER, PATTERSON & SHERIDAN, L.L.P.
Suite 1500
3040 Post Oak Blvd.
Houston
TX
77056
US
|
Assignee: |
Weatherford/Lamb, Inc.
|
Family ID: |
28674062 |
Appl. No.: |
10/116772 |
Filed: |
April 4, 2002 |
Current U.S.
Class: |
166/181 ;
166/123 |
Current CPC
Class: |
E21B 23/06 20130101;
E21B 23/04 20130101 |
Class at
Publication: |
166/181 ;
166/123 |
International
Class: |
E21B 023/06 |
Claims
1. A releasing mechanism for releasing a setting tool from a
plugging tool within a wellbore, the releasing mechanism supporting
a mandrel on the plugging tool while the plugging tool is being
set, the mandrel having an essentially circumferential bore
therein, the releasing mechanism comprising: an adapter having a
top end connected to the setting tool; and a releasable connector
connecting the adapter and the mandrel, the releasable connector
being disposed within a longitudinal plane of the circumferential
bore of the mandrel.
2. The releasing mechanism of claim 1, wherein the releasable
connector defines a nose frictionally disposed within the bore of
the mandrel, the nose having a shear plane which fails under
tensile forces applied by the setting tool.
3. The releasing mechanism of claim 2, wherein the adapter
comprises: a body; a connector above the body for connecting the
adapter with the setting tool; and a lower tubular portion having a
bore therein, the tubular portion having a bottom end which is
landed at a top end of the mandrel.
4. The releasing mechanism of claim 3, wherein the plugging tool is
a bridge plug.
5. The releasing mechanism of claim 4, further comprising a tubular
rod having a top end and a bottom end, the top end being threadedly
connected to the lower tubular portion within the bore of the
adapter, and the bottom end being threadedly connected to the shear
nose above its shear plane.
6. The releasing mechanism of claim 5, further comprising: a collet
disposed circumferentially around the tubular rod and below the
tubular portion of the adapter, the collet having a plurality of
radially spaced apart fingers which extend downward towards the
nose so as to frictionally reside between the nose below the shear
plane, and the inner surface of the mandrel; and a retrieving rod
having a top end and a bottom end, the top end having an enlarged
outer diameter portion defining a shoulder, and a lower ended
threadedly connected to a portion of the nose below the shear
plane.
7. The releasing mechanism of claim 6, wherein the threaded rod
further comprises: an enlarged wall thickness portion defining an
inner shoulder which catches the shoulder of the retrieval rod when
the nose has failed due to tensile forces, and when the adapter is
being raised within the wellbore; and an outer shoulder to retrieve
the collet from the wellbore when the adapter is being raised
within the wellbore.
8. The releasing mechanism of claim 5, further comprising a
metallic sleeve disposed along an inner surface of the mandrel
proximate to the top end of the mandrel.
9. The releasing mechanism of claim 8, further comprising: a collet
disposed circumferentially around the tubular rod and below the
tubular portion of the adapter, the collet having a plurality of
radially spaced apart fingers which extend downward towards the
nose so as to frictionally reside between the nose below the shear
plane, and the inner surface of the mandrel; and a retrieving rod
having a top end and a bottom end, the top end having an enlarged
outer diameter portion defining a shoulder, and a lower ended
threadedly connected to a portion of the nose below the shear
plane.
10. The releasing mechanism of claim 9, wherein the threaded rod
further comprises: an enlarged wall thickness portion defining an
inner shoulder which catches the shoulder of the retrieval rod when
the nose has failed due to tensile forces, and when the adapter is
being raised within the wellbore; and an outer shoulder to retrieve
the collet from the wellbore when the adapter is being raised
within the wellbore.
11. The releasing mechanism of claim 1, wherein the adapter
comprises: a body; a connector above the body for connecting the
adapter with the setting tool; and a lower tubular portion having a
bore therein, the tubular portion having a bottom end which is
landed at a top end of the mandrel.
12. The releasing mechanism of claim 11, wherein the plugging tool
is a bridge plug.
13. The releasing mechanism of claim 12, further comprising a
tubular shear rod, the shear rod having a top end and a bottom end,
the top end being threadedly connected to the tubular portion of
the adapter within the bore, and the lower portion being threadedly
connected to the inner surface of the mandrel.
14. The releasing mechanism of claim 13, wherein the releasable
connection defines a shear plane fabricated between the top end and
the bottom end of the tubular shear rod such that the shear rod
fails due to tensile forces applied on the shear rod when the
hydraulic setting tool is actuated.
15. The releasing mechanism of claim 1, wherein the adapter
comprises: a body; a connector above the body for connecting the
adapter with the setting tool; and a bottom end defining a male
portion which extends into the bore of the mandrel.
16. The releasing mechanism of claim 15, wherein the releasable
connection defines a plurality of shear screws releasably
connecting the male portion of the adapter with the mandrel.
17. The releasing mechanism of claim 16, further comprising an
inner sleeve, the inner sleeve defining a tubular metal body
disposed concentrically within the inner surface of the mandrel at
the location of the plurality of shear screws.
18. The releasing mechanism of claim 17, wherein the inner sleeve
further comprises barbs disposed about the outer surface of the
metal sleeve which frictionally engages the mandrel.
19. The releasing mechanism of claim 4, wherein the releasable
connector comprises an elongated rod having a top end and a bottom
end, the top end being threadedly connected to the bore of the
tubular portion of the adapter, and the lower end being disposed
adjacent to the reinforcing insert within the bore of the
mandrel.
20. The releasing mechanism of claim 19, further comprising a
generally tubular reinforcing insert fabricated into the inner
surface of the mandrel proximate to a top end of the mandrel.
21. The releasing mechanism of claim 1, wherein the releasable
connector defines a shear ring.
22. The releasing mechanism of claim 21, wherein the shear ring and
the reinforcing insert are each fabricated from a metallic
substance.
23. The releasing mechanism of claim 22, wherein the plugging tool
is a bridge plug.
24. The releasing mechanism of claim 23, wherein the shear ring is
disposed intermediate to the lower portion of the elongated rod and
the reinforcing insert, and wherein the shear ring includes a
shoulder extending into a profile within the reinforcing
insert.
25. A releasing mechanism for releasing a hydraulic setting tool
from a bridge plug within a wellbore, the releasing mechanism
supporting a mandrel on the bridge plug while the bridge plug is
being set, the mandrel having an essentially circumferential bore
therein, the releasing mechanism comprising: an adapter having a
body, a top end above the body connected to the setting tool, and a
shoulder disposed within the body; a tubular retaining sleeve
disposed around a lower portion of the body and connected the
shoulder of the adapter at a top end of the retaining sleeve, the
retaining sleeve further having a bottom end and a dog intermediate
the top end and the bottom end of the retaining sleeve; a collet
defining a tubular member disposed essentially concentrically
within the retaining sleeve below the adapter, the collet having a
plurality of radially spaced-apart collet fingers, the collet
fingers being held closely to the mandrel by the lower end of the
retaining sleeve; and a frangible body having a top end threadedly
connected within the bore of the tubular portion of the adapter,
and a lower end threadedly connected to the collet, and having a
shear plane fabricated between the top end and the lower end, the
shear body failing long the shear plane in response to tensile
forces when the hydraulic setting tool is actuated.
Description
NATURE OF THE INVENTION
[0001] The present invention pertains to downhole tools for a
hydrocarbon wellbore. More specifically, the present invention
pertains to downhole tools useful in conjunction with the sealing
of an opening within a wellbore. More specifically still, the
present invention pertains to a releasing mechanism for releasing a
bridge plug or other sealing tool into a wellbore after the sealing
tool has been set.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] Hydrocarbon and other wells are completed by forming a
borehole in the earth and then lining the borehole with steel pipe
or casing to form a wellbore. After a section of wellbore is formed
by drilling, a section of casing is lowered into the wellbore and
temporarily hung therein from the surface of the well. Using
apparatus known in the art, the casing is cemented into the
wellbore by circulating cement into the annular area defined
between the outer wall of the casing and the borehole. The
combination of cement and casing strengthens the wellbore and
facilitates the isolation of certain areas of the formation behind
the casing for the production of hydrocarbons.
[0003] It is sometimes desirable to seal or plug the wellbore at a
selected depth downhole. Various tools are used to accomplish a
sealing of the wellbore. These tools include a bridge plug, a
mechanical packer, and an inflatable packer. In some instances, a
sealing tool may be used to permanently plug a well after
production operations have ceased. In other instances, a wellbore
may be temporarily plugged so that formation treatment operations
may be conducted. For example, a bridge plug may be set at a depth
below a production zone in a wellbore. A formation fracturing
operation can then be conducted above the bridge plug by injecting
gel and sand, under pressure, into the formation. Other uses for
sealing tools are also known.
[0004] Traditionally, sealing tools such as bridge plugs and
packers have been fabricated from alloys of metal. Metallic plugs
are considered most durable in high temperature, high pressure
environments. Recently, sealing tools have been fabricated from
composite materials. Such composite materials include plastics and
ceramics. Advantages exist in the use of nonmetallic sealing plugs,
such as lower manufacturing costs. Also, composite tools are more
easily milled in the hole in the event it is desired to set the
downhole plugging tool only temporarily.
[0005] One disadvantage which has been encountered with the use of
nonmetallic plugs pertains to the process of releasing the plug
from a working string downhole. In the typical plugging operation,
the composite bridge plug is run into the wellbore at the end of a
working string, e.g., drill string, coiled tubing, wireline, etc. A
separate releasing tool is disposed between the bridge plug and the
working string. The releasing tool is used to release the bridge
plug from the working string once the bridge plug or other sealing
tool is set. To accomplish this, the releasing tool includes a
tubular lower portion which concentrically encompasses an upper end
of an inner mandrel of the bridge plug. A plurality of set screws
temporarily fasten the lower portion of the tubular releasing tool
and the inner mandrel of the bridge plug. The bridge plug is set by
application of differential pressure between the mandrel and outer
setting portions of the bridge plug. Differential pressure is
typically applied by either a charge deployed at the lower end of a
wireline, or through the injection of fluid under pressure into a
hydraulic setting tool. Application of additional pressure after
the bridge plug has been set causes the shear screws to shear,
allowing the setting tool to be released from the composite inner
mandrel.
[0006] The use of metallic shear screws in a nonmetallic mandrel
creates an unpredictable and, sometimes, unreliable arrangement for
shearingly releasing a setting tool from a bridge plug. This is
because the physical properties of nonmetallic materials can be
dissimilar and not typically as uniform in nature as metallic
materials. Thus, a need exists for an alternate apparatus for
releasing a hydraulic setting tool from a bridge plug after the
bridge plug has been set in a wellbore.
[0007] An apparatus is also needed which will permit a hydraulic
setting tool to be consistently released or disconnected from a
nonmetallic bridge plug after the bridge plug has been set through
application of a predictable force or pressure. Further, a need
exists for a releasing mechanism which does not require a
metal-to-composite interface between a shear screw and the inner
mandrel of the bridge plug or other sealing tool.
SUMMARY OF THE INVENTION
[0008] A releasing mechanism for releasing a hydraulic (or other)
setting tool from a bridge plug within a wellbore is provided. For
purposes of this application, the term "bridge plug" includes any
tool used for sealing an opening in a wellbore, including bridge
plugs, hydro-mechanically set packers, and inflatable packers.
Further, the term "bridge plug" includes bridge plugs of any
material, whether metallic or nonmetallic.
[0009] The releasing mechanisms of the present invention are
designed to release a bridge plug from a setting tool after the
bridge plug has been set. To this end, the releasing mechanisms of
the present invention first comprise an adapter. The adapter
includes an upper portion which is connected to a lower end of a
hydraulic setting tool. The adapter is configured to receive an
upward force generated by hydraulic pressure injected into the
hydraulic setting tool for the bridge plug. The releasing
mechanisms of the present invention further comprise a frangible
member which releasably secures the adapter to the mandrel of the
bridge plug until a releasing pressure has been reached. For each
embodiment of the present inventions, the releasing pressure is a
pressure greater than the pressure or force required to set the
bridge plug itself within the wellbore.
[0010] Various embodiments for a releasing mechanism are provided
in accordance with the present inventions. The various embodiments
present different means for releasing the adapter from the inner
mandrel of the bridge plug. In accordance with the various
releasing means, different frangible members are employed.
Preferably, the frangible member is disposed within the
longitudinal plane of the circumference of the inner mandrel. This
affords greater clearance for running the bridge plug into the
surrounding casing of the wellbore.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] So that the manner in which the above recited features of
the present invention are attained and can be understood in detail,
a more particular description of the invention, briefly summarized
above, may be had by reference to the embodiments thereof which are
illustrated in the appended drawings. It is to be noted, however,
that the appended drawings illustrate exemplary embodiments of this
invention and are, therefore, not to be considered limiting of its
scope, for the invention may admit to other legally equivalent
embodiments.
[0012] FIG. 1 presents a wellbore containing a releasing mechanism
of the present invention in one embodiment. The releasing mechanism
is being run into the wellbore on a working string intermediate a
hydraulic setting tool and bridge plug.
[0013] FIGS. 1A-1D provide an enlarged view for the tools within
FIG. 1. FIG. 1A depicts a working string being lowered into a
surrounding casing string within a wellbore. FIG. 1B shows a
hydraulic setting tool as might be used to set a bridge plug. FIG.
1C presents the releasing mechanism of FIG. 1. FIG. 1D presents one
arrangement for a bridge plug, attached to the lower end of the
releasing mechanism of FIG. 1C.
[0014] FIGS. 1C-R presents a cross-sectional view of the releasing
mechanism of FIG. 1C released from the mandrel of the bridge
plug.
[0015] FIG. 2C presents a second embodiment of a releasing
mechanism in accordance with the present invention. In this view,
the releasing mechanism is in its run-in position such that it
remains connected to the mandrel of a bridge plug.
[0016] FIGS. 2C-R presents the releasing mechanism of FIG. 2C being
released from the mandrel of the bridge plug.
[0017] FIG. 3C presents a third embodiment of a releasing mechanism
in accordance with the present invention. In this cross-sectional
view, the releasing mechanism is in its run-in position such that
it remains connected to the mandrel of a bridge plug.
[0018] FIGS. 3C-R presents the releasing mechanism of FIG. 3C being
released from the mandrel of the bridge plug.
[0019] FIG. 4C presents a fourth embodiment of a releasing
mechanism in accordance with the present invention. In this
cross-sectional view, the releasing mechanism is in its run-in
position such that it remains connected to the mandrel of a bridge
plug.
[0020] FIGS. 4C-R presents the releasing mechanism of FIG. 4C being
released from the mandrel of the bridge plug.
[0021] FIG. 5C presents a fifth embodiment of a releasing mechanism
in accordance with the present invention. In this cross-sectional
view, the releasing mechanism is in its run-in position such that
it remains connected to the mandrel of a bridge plug.
[0022] FIGS. 5C-R presents the releasing mechanism of FIG. 5C being
released from the mandrel of the bridge plug.
[0023] FIG. 6C presents a sixth embodiment of a releasing mechanism
in accordance with the present invention. In this cross-sectional
view, the releasing mechanism is in its run-in position such that
it remains connected to the mandrel of a bridge plug.
[0024] FIGS. 6C-R presents the releasing mechanism of FIG. 6C being
released from the mandrel of the bridge plug.
[0025] FIG. 7C presents a seventh embodiment of a releasing
mechanism in accordance with the present invention. In this
cross-sectional view, the releasing mechanism is in its run-in
position such that it remains connected to the mandrel of a bridge
plug.
[0026] FIGS. 7C-R presents the releasing mechanism of FIG. 7C being
released from the mandrel of the bridge plug.
[0027] FIG. 8C presents an eighth embodiment of a releasing
mechanism in accordance with the present invention. In this
cross-sectional view, the releasing mechanism is in its run-in
position such that it remains connected to the mandrel of a bridge
plug.
[0028] FIGS. 8C-R presents the releasing mechanism of FIG. 8C being
released from the mandrel of the bridge plug.
[0029] FIG. 9C presents a ninth embodiment of a releasing mechanism
in accordance with the present invention. In this cross-sectional
view, the releasing mechanism is in its run-in position such that
it remains connected to the mandrel of a bridge plug.
[0030] FIGS. 9C-R presents the releasing mechanism of FIG. 9C being
released from the mandrel of the bridge plug.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0031] FIG. 1 presents a releasing mechanism 100 of the present
invention, in one embodiment. The releasing mechanism 100 is shown
disposed in a wellbore 10. The wellbore 10 is cased with a string
of casing 15. The casing is resides within a surrounding formation
18.
[0032] In the view of FIG. 1, the releasing mechanism 100 is being
run into the wellbore 10 on a working string 20. The working string
20 may be any tubular string, including but not limited to drill
pipe and coiled tubing. At the lower end of the working string 20
are various tools, including a hydraulic setting tool 30, a bridge
plug 50, and a bridge plug releasing mechanism 100. The releasing
mechanism 100 is used to release the bridge plug 50 from the end of
the hydraulic setting tool 30. Exemplary arrangements of a
hydraulic setting tool 30 and a bridge plug 50 are shown in FIG.
1.
[0033] FIGS. 1A-1D provide enlarged views of the tools 30,50,100 of
FIG. 1. FIG. 1A presents a cross-sectional view of a wellbore, with
the working string 20 being lowered into the surrounding casing 15
within the wellbore 10. An upper portion of the setting tool 30 is
shown attached to a lower end of the working string 20. FIG. 1B
shows the hydraulic setting tool 30 as might be used to set a
bridge plug 50. FIG. 1C presents a first embodiment of a releasing
mechanism 100 of the present invention. The releasing mechanism 100
is disposed intermediate the setting tool 30 and a bridge plug 50.
Finally, FIG. 1D presents an exemplary arrangement for a bridge
plug 50.
DESIGN 1
[0034] Turning to FIG. 1C, a releasing mechanism 100 in one
arrangement is presented. Visible in FIG. 1C is a setting sleeve 32
of the setting tool 30 circumferentially encompassing the releasing
mechanism 100. The setting sleeve 32 defines a tubular body which
is used by the setting tool 30 of FIG. 1B in order to exert
downward pressure against the bridge plug 50 of FIG. 1D. In this
regard, the setting sleeve 32 includes a lower shoulder 34 which
butts downward against a setting ring 58 of the bridge plug 50. The
setting sleeve 32 has an upper threaded connector 36 for connecting
to an inner adapter 38 of the setting tool 30.
[0035] An upper portion of the bridge plug 50 is visible in FIG.
1C. The upper portion of the bridge plug 50 defines a mandrel 51
having a bore 52 therethrough. Also disposed on the bridge plug 50
is a support ring 56. The support ring is threadedly connected to
the mandrel 51 near the top end 54. Thus, the support ring 56
defines a tubular body concentrically placed around the mandrel 51.
Immediately below the support ring 56 and also disposed
circumferentially around the mandrel 51 is the setting ring 58. The
setting ring 58 has a larger outer diameter than the support ring
56. As noted, the setting ring 58 serves as a shoulder against
which the setting sleeve 32 of the setting tool 30 acts. Thus,
downward force applied by the setting sleeve 32 of the setting tool
30 provides the actuating force for setting the bridge plug 50.
[0036] Those of ordinary skill in the art will understand that the
typical bridge plug 50 is set when upper 57' and lower 57" slips
and an intermediate elastomeric packing element 59 engage the
surrounding string of casing 15 in order to seal the wellbore 10.
These features are seen in the exemplary bridge plug 50 of FIG. 1D.
The slips are shown in 57', 57" while the packing element is shown
at 59.
[0037] It is the purpose of the releasing mechanism 100 to release
the setting tool 30 from the bridge plug 50. To accomplish this, an
adapter 110 is first provided for the releasing mechanism 100. The
adapter 110 includes a threaded upper connector 114 for sealingly
connecting with the setting tool 30. In the arrangement of FIG. 1C,
the adapter 110 further comprises a lower tubular portion 116
having a bore 112 therein. The lower tubular portion 116 butts
downward against the end 54 of the inner mandrel 51.
[0038] Disposed partially within the lower portion 116 of the
adapter 110 is a threaded rod 120. The threaded rod 120 defines a
tubular body having an inner bore 112 running therethrough. The
inner rod 120 is configured to fit within the inner bore 112 of the
lower tubular portion 116 of the adapter 110. The inner rod 120 is
threadedly connected to the lower portion 116 of the adapter 110
within the inner bore 112.
[0039] The rod 120 includes a lower portion 127 having an enlarged
wall thickness. It can be seen in FIG. 1C that the enlarged wall
portion 127 of rod 120 has both a slightly enlarged outer diameter
to form an outer shoulder 124, and a significantly reduced inner
diameter to form an inner shoulder 129.
[0040] In the arrangement of FIG. 1C, the releasing mechanism 100
also comprises a collet ring 130. The collet ring 130 defines a
plurality of fingers 132 which are radially disposed between the
threaded rod 120 and the mandrel 51 of the bridge plug 50. Each of
the collet fingers 130 includes a shoulder portion 134 which butts
against the outer shoulder 124 of the threaded rod 120. Each
collect finger 132 includes gripping teeth on the outer diameter
for gripping the surrounding mandrel 51.
[0041] Disposed within the lower portion of the threaded rod 120 is
a shear nose 140. The shear nose includes a shear plane 145 formed
normal to the plane of the longitudinal bore 52 in the mandrel 51.
The shear plane 145 creates an area of structural weakness within
the shear nose 140. As will be described below, upon application of
tensile force, the shear nose 140 will fail along the shear plane
145. To aide in the application of tensile force, the shear nose
140 includes a severable lower portion 140L having a generally
conical cross section. In the run-in position of FIG. 1C, the lower
ends of the collet fingers 130 engage the lower portion 140L of the
shear nose 140 in a friction fit between the lower nose portion
140L and the mandrel 51.
[0042] Finally, the releasing mechanism 100 in FIG. 1C includes a
catch rod 150. The catch rod 150 defines an elongated rod having an
upper end and a lower end. The lower end is threadedly connected to
the lower portion 140L of the shear nose 140. The upper portion
includes a shoulder 154 which resides within the inner bore 122 of
the threaded rod 120 above the enlarged lower portion 127. As will
be discussed, the inner shoulder 129 of the threaded rod 120
catches the shoulder 154 of the catch rod 150 when the releasing
mechanism 100 releases from the bridge plug 50.
[0043] In operation, actuation of the hydraulic setting tool 30
creates a simultaneous downward force against the setting ring 58
of the bridge plug 50 and an upward force against the adapter 110
of the releasing mechanism 100. The threaded rod 120 is threadedly
connected to the lower tubular portion 116 of the adapter 110.
Therefore, an upward force against the adapter 110 serves to also
pull the threaded rod 120 upward. As noted, the collet fingers 130
include a shoulder portion 134. An upward force of the threaded rod
120 causes the outer shoulder 124 to engage the shoulder 134 of the
collet fingers 130. Thus, upward force against the adapter 110 also
pulls the collet 130 upward within the wellbore.
[0044] A threaded connection is provided between the shear nose 140
and the lower portion of the threaded rod 120. Eventually, upward
force against the adapter 110 pulls the threaded rod 120, the base
of the shear nose 140, and the collet fingers 130 upward together.
The shear nose 140 shears along the shear plane 145, leaving the
lower portion 140L of the shear nose 140 within the mandrel 51.
[0045] Referring now to the cross-sectional view of FIGS. 1C-R, the
releasing mechanism 100 is shown being released from the inner
mandrel 51 of the bridge plug 50. It is to be noted that removal of
the releasing mechanism 100 from the wellbore 10 brings with it the
entire shear nose 140, including the sheared lower portion 140L. To
accomplish this, the lower end of the catch rod 150 is threadedly
connected to the lower portion 140L of the shear nose 140. Further,
as the threaded rod 120 moves upward in the wellbore 10, the inner
shoulder 129 catches the shoulder 154 of the catch rod 150. The
sheared portion 140L of the shear nose 140 is then pulled from the
wellbore 10 upon raising of the working string 20.
[0046] It can be seen from FIGS. 1C-R that the releasing mechanism
100 is simple to install, and leaves no metal parts within the
bridge plug mandrel 51 after the bridge plug 50 has been released
from the setting tool and the releasing mechanism 100. The
releasing mechanism 100 of FIG. 1C can function properly with
nonmetallic materials, and without concern as to the collapse of a
nonmetallic mandrel. No metal components or parts are left in the
wellbore 10 after the bridge plug 50 is released, and all parts of
the releasing mechanism 100 are reusable, except for the shear nose
140. Further, the mechanism 100 does not rely on metal-to-composite
shearing.
[0047] Various other arrangements for a releasing mechanism 100 are
provided in this application. These are listed below.
DESIGN 2
[0048] FIG. 2C presents an alternate arrangement for a releasing
mechanism 200 of the present invention. Releasing mechanism 200
includes all of the same features as releasing mechanism 100
described in connection with FIG. 1C. However, releasing mechanism
200 further includes a metal sleeve 260 disposed along the inner
diameter of the mandrel 51 proximate to the top end 54. In the
arrangement of FIG. 2C, the metal sleeve 260 also wraps over the
top end 54 of the mandrel 51. Thus, in one aspect, the inner metal
sleeve 260 covers the inner diameter, the top end 54, and the outer
diameter of the top of the mandrel 51.
[0049] The metallic sleeve 260 is machined to include a slotted
profile in the inner diameter for the teeth of the collet rings 130
to locate. This helps secure the collet 130 to the mandrel 51
during run-in without applying undue burst pressure to the mandrel
51. Preferably, the sleeve 260 is fabricated from a softer metal,
such as aluminum. The sleeve 260 helps control any possible
ballooning or swelling of the mandrel 50 material when a severe
load is applied during the bridge plug 50 releasing operation.
[0050] FIGS. 2C-R presents the releasing mechanism 20 of FIG. 2C
being released from the mandrel 51 of the bridge plug 50. Operation
of the releasing mechanism 200 in FIGS. 2C-R is the same as the
operation of the releasing mechanism 100 in FIGS. 1C-R. It can be
seen from FIGS. 2C-R that the releasing mechanism 200 enjoys the
advantage of preventing the composite layers of a non-metallic
mandrel from shearing. In this respect, the metal insert sleeve
assist in spreading the load over the outer diameter and inner
diameter of the mandrel when the bridge plug is set.
DESIGN 3
[0051] An alternate design for a releasing mechanism 300 of the
present invention is depicted in FIG. 3C. As seen in FIG. 3C, the
alternate releasing mechanism 300 first comprises an adapter 310.
The adapter 310 is configured in accordance with the adapter 110 of
Design 1 (shown in FIG. 1C) for the releasing mechanism 100. In
this regard, the adapter 310 includes an upper connecting end 314,
a lower tubular portion 316, and a bore 312 within the lower
tubular portion 316.
[0052] The releasing mechanism 300 further comprises an inner
tubular body 320 having an inner bore 322. The tubular body defines
a shear rod 320. In this respect, the shear rod 320 includes a
shear plane 345 which is normal to the longitudinal plane of the
circumferential bore 52 within the mandrel 51 of the bridge plug
50. To aide in the failure of the shear rod 320 along the shear
plane 345, a reduced wall thickness can be seen at the point of the
shear plane 345.
[0053] The upper portion of the shear rod 320 is threadedly
connected to the inner diameter of the tubular portion 316 of the
adapter 310. By this arrangement, an upward force against the
adapter 310 acts to create an upward force against the shear rod
320. The lower portion of the shear rod 330 is connected to the
inner diameter of the mandrel 51. The lower portion of the shear
rod 320 is shown at 320L.
[0054] The connection between the lower portion 320L of the shear
rod 320 and the mandrel 51 may be of any number of means.
Preferably, the lower portion 320L of the shear rod 320 is directly
fabricated into the mandrel 51. The fabrication may include
winding, molding, inserting, bonding, or gluing in to the mandrel
51. The connection may also be through a threaded connection.
[0055] In operation, actuation of the hydraulic setting tool causes
an upward force against the adapter 310 and the shear rod 320. At
the same time, the setting sleeve 32 acts downwardly against the
setting ring 58 of the bridge plug 50. Ultimately, a releasing
pressure is obtained within the hydraulic setting tool 30 which
causes a failure of the shear rod 320 along the shear plane 345.
Failure is due to tensile forces applied within the shear rod
320.
[0056] FIGS. 3C-R depicts the releasing mechanism 300 of FIG. 3C
being removed from the wellbore 10. In this arrangement, the lower
portion 320L of the shear rod 320 remains connected to and becomes
a part of the mandrel 51 of the bridge plug 50 along an inner
surface.
[0057] As can be seen, the releasing mechanism 300 is relatively
inexpensive, and is simple to install. The releasing mechanism 300
further enjoys the advantage that it can be applied to bridge plugs
having a small inner diameter within the mandrel. The releasing
mechanism functions properly with both metallic and nonmetallic
materials. A ball (not shown) may also be incorporated into the
design. Further, the mechanism 300 does not rely on
metal-to-composite shearing for tool 50 release.
DESIGN 4
[0058] Turning now to FIG. 4C, yet an additional alternate
embodiment 400 for a releasing mechanism is disclosed. The
releasing mechanism 400 first comprises an adapter member 410. The
adapter 410 includes an upper portion 414 which serves as a
threaded connector for connecting with the hydraulic setting tool
30 (not shown) in FIG. 4C. The adapter 410 also includes a middle
portion 412 having an enlarged outer diameter. The base of the
middle portion 412 defines a shoulder 418. Finally, the adapter 410
includes a lower male portion 416. The male portion 416 of the
adapter 410 extends into the bore 52 of the mandrel 51.
[0059] The releasing mechanism 400 in FIG. 4C also comprises an
insert sleeve 460. The insert sleeve 460 defines a tubular body
disposed within the mandrel 51, and includes a bore 462 therein.
The insert sleeve 460 is disposed concentrically within the bore 52
of the mandrel 51, and proximate to the upper end 54 of the mandrel
51. The insert sleeve 460 preferably is fabricated from a metallic
material.
[0060] The insert sleeve 460 is releasably connected to the inner
mandrel 51. In one aspect, a releasable connection is provided in
the form of a plurality of shear pins 425. The shear pins 425 are
inserted through holes 426 aligned through the mandrel 51, the
insert sleeve 460 and the male portion 416 of the adapter 410. In
one aspect, the shear pins 425 are threaded into drilled holes
within the male portion 416.
[0061] In one aspect, the outer surface of the insert sleeve 460
includes a plurality of barbs 428. The barbs 428 are pressed into
the inner surface of the mandrel 51 in order to further hold the
insert sleeve 460 within the mandrel 51. In this arrangement, the
inner sleeve 460 becomes a permanent part of the bridge plug
50.
[0062] In operation, the hydraulic setting tool 30 is actuated so
as to provide opposing forces between the mandrel 51 and the
setting ring 58 of the bridge plug 50. A setting pressure is
ultimately reached by the hydraulic setting tool 30 in order to set
the bridge plug 50 within the wellbore 10. Pressure continues to be
applied through the working string 20 and into the setting tool 30
so as to release the releasing mechanism 400. In this respect, an
upward force applied by the setting tool 30 against the adapter 410
causes the shear pins 425 to shear. The use of a metal-to-metal
contact between the shear pins 425 and the insert sleeve 460 serves
to provide dependability and predictability as to the release
pressure.
[0063] FIGS. 4C-R depicts the releasing mechanism 400 being pulled
from the wellbore. In this arrangement, the shear pins 425 have
been sheared from the connection with the male portion 416 of the
adapter 410. The adapter 410 is now being pulled from the wellbore
10. However, the insert sleeve 460 remains a permanent fixture
within the mandrel 51 of the bridge plug 50.
[0064] As can be seen from this disclosure in FIGS. 4C-R, the
releasing mechanism 400 is relatively inexpensive, and is simple to
install. The releasing mechanism 400 further enjoys the advantage
that it can be applied to bridge plugs having a small inner
diameter within the mandrel 51. A simple shear screw 425 can be
used to achieve the desired load. A ball and seat (not shown) can
be incorporated into the design.
DESIGN 5
[0065] An additional alternate design for a releasing mechanism 500
of the present invention is shown in FIG. 5C. The alternate
arrangement 500 first comprises an adapter 510. The adapter 510
includes an upper threaded portion 514 for connection with the
setting tool 30 (not shown). The adapter 510 also includes a middle
portion 512 having an enlarged outer diameter. The base of the
middle portion 512 defines a shoulder 518. Finally, the adapter 510
includes a lower male portion 516. The male portion 516 of the
adapter 510 extends into the bore 52 of the mandrel 51.
[0066] The male portion 540 of the adapter 510 includes a shear
plane 545 which is designed to fail upon application of tensile
forces within the adapter 510. The shear plane 545 is oriented
essentially normal to the plane of the circumferential bore 52 of
the mandrel 51. A lower portion 540L of the male portion 540
extends below the shear plane 545.
[0067] In the arrangement of FIG. 5C, the mandrel 51 includes
threads 56 machined into the outer diameter. Preferably, the
threads are a tapered, acme-style thread. Where a nonmetal mandrel
51 is employed, the tapered threads assist in applying a load over
different ceramic or composite layers through the nonmetallic
material. This is especially useful when using a wrapped roving
composite or a filament winding composite. A matching tapered acme
buttress box 536 is machined into a collet 530 for intermeshing
with the threads 56 of the mandrel 51. The buttress-style threads
536 allow the setting tool 30 to release properly, as will be
described further below. The threaded collet 530 includes a
shoulder portion 534 which butts against the upper end 54 of the
mandrel 51. Further, an upper portion 538 of the collet 530
includes an upper shoulder 538U and a lower shoulder 538L.
[0068] Disposed circumferentially around the collet 530 is a
retaining sleeve 560. The retaining sleeve 560 defines a tubular
member which has an upper end threadedly connected to the adapter
510. The upper end of the retaining sleeve 560 butts against the
shoulder 518 of the adapter. The retaining sleeve 560 also has a
shoulder 544 which butts against the upper shoulder 538U of the
collet 530. Finally, at least one dog 565 is positioned through the
retaining sleeve 540, as shown in FIG. 5C.
[0069] In operation, the releasing mechanism 500 is releasably
connected to the mandrel 51 of the bridge plug 50. Injection of
fluid under pressure into the hydraulic setting tool 30 above the
releasing tool 500 creates opposing forces between the releasing
mechanism 500 and the bridge plug 50. As noted previously, a
downward force is applied by the setting sleeve 32 against the
setting ring 58 of the bridge plug 50, and associated floating
members such as the packing element 59 (shown in FIG. 1D).
Simultaneously, an upward force is applied against the adapter 510.
In the arrangement 500 of FIG. 5C, the adapter 510 is threadedly
connected to the upper portion of the retaining sleeve 560. At the
same time, a threaded connection is also maintained between the
lower end 540L of the male portion 540 of the adapter 510 and the
collet 530. Thus, an upward force applied against the adapter 510
pulls the retaining sleeve 560 upward, while the threaded collet
530 holds the lower portion 540L of the adapter 540 in place.
Ultimately, upon application of the releasing pressure, the male
portion 540 of the adapter 510 fails along the shear plane 545 due
to the tensile forces described above.
[0070] FIGS. 5C-R presents a cross-sectional view of the releasing
mechanism 500 being removed from the wellbore 10. In this
arrangement, it can be seen that the adapter 510 and the threadedly
connected retaining sleeve 560 are being moved upward through the
casing 15 within the wellbore 10. As the retaining sleeve 560 moves
upward, the threaded collet 530 is released from the outward-facing
threads 56 of the mandrel 51. In this regard, the collet 530 is
pre-stressed to cause the fingers 532 be biased to move outwardly
away from the threads 56 of the mandrel 51. As the retaining sleeve
560 further moves up the wellbore 10, the dogs 565 of the retaining
sleeve 560 shoulder against the lower shoulder 538L of the collet
530. In this way, the collet 530 is removed from the wellbore 10
along with the adapter 510.
[0071] As can be seen from this disclosure and from FIGS. 5C-R, the
releasing mechanism 500 leaves no metal components within the bore
of the mandrel after the bridge plug or other wellbore sealing tool
has been set. The releasing mechanism 500 further enjoys the
advantage that it can be applied to bridge plugs having a small
inner diameter within the mandrel. All releasing mechanism 500
components are tripped out of the wellbore 100 after the bridge
plug 50 is set and released.
DESIGN 6
[0072] Still further, an alternate arrangement 600 for a releasing
mechanism of the present invention is depicted in FIG. 6C. As shown
in FIG. 6C, the releasing mechanism 600 first comprises an adapter
610. The adapter 610 includes an upper threaded portion 614 for
connecting to the lower end of the setting tool 30. The adapter 610
also comprises a lower tubular portion 616. The lower tubular
portion 616 creates an inner bore 622 partially into the adapter
610. A shoulder 618 is fabricated onto the outer surface of the
lower tubular portion 616 of the adapter 610.
[0073] The releasing mechanism 600 also comprises a retaining
sleeve 660. The top of the retaining sleeve 660 butts against the
shoulder 618 of the adapter 610. The retaining sleeve 660 defines
an elongated tubular body which extends downward from a shoulder
664. A plurality of dogs 665 are disposed within the elongated
portion 646 of the retaining sleeve 660 in order to serve as a
shoulder.
[0074] As with the mandrel 51 of FIG. 5C, the mandrel 51 of FIG. 6C
includes threads 56 along the outer surface of the mandrel 51. A
tapered acme-style thread is machined into the outer diameter of
the mandrel 51 proximate to the upper end 54. The threads 56 of the
mandrel 51 are configured to mate with matching tapered acme
buttress box threads 636 on the inner surface of a collet 630. To
this end, a collet 630 is disposed below the tubular portion 616 of
the adapter 610, and around the upper portion of the mandrel 51.
The collet 630 includes a plurality of collet fingers 632 which
include the threads 636 for intermeshing with the outer threads 56
of the mandrel 51. This mating arrangement serves as the support
mechanism for supporting the bridge plug 50 during run-in.
[0075] Above the fingers 632 of the collet 630 is one or more dog
members 634. The dog members 634 protrude inwardly within the
collet 630. As will be described below, the dogs 634 will catch
against the bottom end of the tubular portion 616 of the adapter
610 when the releasing mechanism 600 is pulled from the wellbore
10.
[0076] The collet 630 generally resides within the retaining sleeve
660 below the adapter 610. The retaining sleeve 660 and the collet
630 are initially held together through a releasable connection
645. Preferably, the releasable connection defines a shear screw
645. The shear screw 645 is sheared upon upward force applied to
the retaining sleeve 660 by the threaded connection with the
adapter 610.
[0077] The releasing mechanism 600 finally comprises a support rod
620. The support rod 620 defines an elongated body having a top end
and a bottom end. The top end of the support rod 620 is threadedly
connected within a bore 622 of the tubular portion 616 of the
adapter 610. A lower portion 624 of the support rod 620 has an
enlarged outer diameter. The enlarged outer diameter portion 624 is
configured to move within the bore 52 of the mandrel 51, but to
catch the dogs 634 of the collet 630 when the releasing mechanism
600 is raised within the wellbore 10.
[0078] In operation, the releasing mechanism 600 holds the mandrel
51 in place when the hydraulic setting tool 30 is actuated.
Connection is accomplished through the threads 56 of the mandrel 51
and the threads 636 of the collet 630. The threads 56, 636 continue
to support the mandrel 51 when the setting sleeve 32 of the setting
tool 30 presses downward on the setting ring 58 and associated
floating tools, e.g., element 59, of the bridge plug 50.
[0079] As pressure builds within the hydraulic setting tool 30, the
bridge plug 50 is sealingly set within the surrounding casing 15.
As additional pressure is injected into the wellbore 10, tensile
stress is applied to the shear screws 645 between the collet 630
and the surrounding retaining ring 640. Ultimately, a releasing
pressure is reached and the shear screws 645 are sheared, thereby
releasing the retaining sleeve 660 from the collet 630. This
permits the adapter 610, and the connected retaining sleeve 660 and
support rod 620 to move upward within the wellbore 10 relative to
the mandrel 51.
[0080] As the retaining sleeve 660 is raised within the wellbore
10, the elongated portion lower portion of the retaining sleeve 660
moves away from the collet fingers 632. The collet fingers 632 are
pre-stressed in order to be biased to move away from the mandrel
51. As the retaining sleeve 660 is raised, the collet fingers 632
are freed from the restraining force of the retaining sleeve 660.
The collet fingers 632 and associated threads 636 then release from
the mandrel 51.
[0081] FIGS. 6C-R presents the releasing mechanism 600 of FIG. 6C
being released from the mandrel 51 of the bridge plug 50. Pulling
the releasing mechanism 600 from the wellbore 10 moves the support
rod 620 upward relative to the collet 630. The releasing mechanism
600 is configured so that the lower enlarged outer diameter portion
624 of the support rod 620 will catch against the dogs 634 of the
collet 630 as the adapter 610 is raised. This provides support for
removal of the collet 630 from the wellbore 10. Contact with the
dogs 634 by the enlarged outer diameter portion 624 of the support
rod 620 also assists in releasing the collet fingers 632 from the
mandrel 51. In this respect, the enlarged outer diameter portion
624 of the support rod 620 is configured to have a tapered diameter
so as to urge the collet fingers 632 away from the mandrel 51.
[0082] As can be seen from FIGS. 6C-R, the releasing mechanism 600
is completely reusable save for the shear screws 645. Removal of
the releasing mechanism 600 after the bridge plug 50 of other
wellbore sealing tool has been set leaves no metal components
within the mandrel. Nothing related to the releasing mechanism 600
other than the external threads 56 of the mandrel 51 remain after
the releasing mechanism 600 is removed from the wellbore 10. The
releasing mechanism 600 design is adaptable to all mandrel sizes
and can function properly with both metallic and nonmetallic
materials.
DESIGN 7
[0083] An alternate design for a releasing mechanism 700 of the
present invention is depicted in FIG. 7C. As seen in FIG. 7C, the
alternate releasing mechanism 700 first comprises an adapter 710.
The adapter 710 is configured in accordance with the adapter 110 of
the first embodiment 100 for a releasing mechanism. In this regard,
the adapter 710 includes an upper end 714 for connection with a
setting tool 30, a lower tubular portion 716, and a bore 712 within
the lower tubular portion 716.
[0084] A reinforcing insert 740 is fabricated into the mandrel 51.
Preferably, the insert 740 is fabricated from a metallic substance.
The insert 740 provides structural support and reinforcement for
the mandrel 51. Fabrication of the insert 740 into the mandrel 51
may be through any known means, including gluing, winding,
threading or bonding.
[0085] The reinforcing insert 740 is generally tubular in
construction. However, the insert 740 is fabricated into the
mandrel 51 through matching teeth 746. The teeth 746 in the insert
740, in one embodiment, define castellations in the form of a
buttress thread. However, any acme-type thread may be employed. The
teeth 746 of the insert 740 mate with the threads 56 in the mandrel
51. Preferably, the threads 56 of the mandrel 51 define a tapered,
acme-style thread configured to mate with the teeth 746 of the
insert 740.
[0086] In one aspect, the reinforcing insert 740 includes one or
more through-openings 743. The insert through-openings 743 are
positioned to align with corresponding one or more through-openings
53 in the mandrel 51. The through-openings 53, 743 receive a
temporary pin or screwdriver (not shown) or other device which
permits the bridge plug 50 and inner rod 740 to be made up to the
adapter 710 during assembly of the releasing mechanism 700.
[0087] A threaded rod 720 is also provided for the releasing
mechanism 700 of FIG. 7C. The threaded rod 720 in one arrangement
defines a tubular body. However, a solid piece may also be used.
The upper portion of the threaded rod 720 is designed to threadedly
connect into the inner bore 722 of the lower tubular portion 716 of
the adapter 710. A lower portion of the rod 720 extends into the
bore 52 of the mandrel 51. The outer surface of the lower portion
720L of the rod 720 is generally adjacent to the teeth 746 of the
reinforcing insert 740.
[0088] Finally, the releasing mechanism 700 in FIG. 7C comprises a
frangible member 745. Preferably, the frangible member 745 defines
a shear ring, such as a split ring or "C" ring. The shear ring 745
is disposed along the inner surface of the reinforced mandrel 51
within a profile 748 of the insert 740. The shear ring 745 is
positioned above a shoulder portion 724 of the rod 720. The
shoulder portion 724 is affixed to the rod 720 along the lower
portion 720L of the rod 720.
[0089] In operation, the releasing mechanism 700 holds the mandrel
51 in place when the hydraulic setting tool 30 is actuated.
Connection is accomplished through the shear ring 745 and the
mandrel 51. As noted, the adapter 710 is threadedly connected to
the tubular rod 720. Upward force against the adapter 710 serves to
apply a reciprocal upward force upon the rod 720. When the
releasing pressure for the releasing mechanism 700 is reached, the
shear ring 745 is sheared, thereby releasing the adapter 710 and
rod 720 from the mandrel 51. The presence of the metallic
reinforcing insert 740 provides reliability and predictability for
shearing the shear ring 745 by establishing a metal-to-metal
contact between the shear ring 745 and the insert 740. In other
words, a consistent shear value is provided for the releasing
mechanism 700.
[0090] FIGS. 7C-R depicts the releasing mechanism 700 being raised
within the wellbore 10 after release from the bridge plug 50. In
this view, the shear ring 745 around the rod 720 has been sheared.
It can be seen that the adapter 710 and the rod 720 are being
removed from the wellbore 10. However, the reinforcing insert 740
remains attached to the mandrel 51.
DESIGN 8
[0091] Turning now to FIG. 8C, yet an additional alternate
embodiment for a releasing mechanism 800 of the present invention
is provided. As seen in FIG. 8C, the alternate releasing mechanism
800 first comprises an adapter 810. The adapter 810 generally is
configured in accordance with the adapter 110 of the first
embodiment 100 for a releasing mechanism. In this regard, the
adapter 800 includes an upper connecting end 814, a lower tubular
portion 816, and a bore 812 within the lower tubular portion
816.
[0092] A shoulder 818 is fabricated into the adapter 810 along an
outer surface. In the arrangement of FIG. 8C, the shoulder 818 is
positioned at the level of the lower tubular portion 816.
[0093] The releasing mechanism 800 further comprises a retaining
sleeve 820. The retaining sleeve 820 defines a tubular body. A top
portion 824 of the retaining sleeve 820 butts up against the
shoulder 818 of the adapter 810. In the arrangement of FIG. 8C, the
connection between the retaining sleeve 820 and the adapter 810 is
by welding. Preferably, the retaining sleeve 820 is fabricated from
a metallic substance to facilitate the welding connection. However,
other means of connection are within the spirit of the present
invention.
[0094] The releasing mechanism 800 further comprises an inner rod
840. An upper portion of the rod 840 is disposed within the bore
812 of the adapter 810. The upper portion of the rod 840 is
externally threaded. In one aspect, the rod 840 defines a solid
metallic cylindrical body. However, a tubular piece may also be
used.
[0095] A shear tube 850 is also disposed within the bore 812 of the
adapter 810. An upper portion 852 of the shear tube 850 is
internally threaded in order to threadedly connect with the upper
portion of the rod 840. At the same time, the upper portion 852 of
the shear tube 850 is externally threaded in order to connect with
the tubular portion 816 of the adapter 810. Thus, the inner rod 840
and the shear tube 850 are concentrically nested within the tubular
portion 816 of the adapter 810.
[0096] Both the threaded rod 840 and the threaded shear tube 850
extend below the bore 812 of the adapter 810. A lower portion 856
of the shear tube 850 extends below the tubular portion 816 of the
adapter 810, but does not extend into the bore 52 of the mandrel
51. However, the elongated threaded rod 840 does extend into the
bore 52 of the mandrel 51. A lower portion 844 of the rod 840
includes an enlarged outer diameter in order to define a
shoulder.
[0097] The releasing mechanism 800 further comprises a collet 830.
The collet 830 defines a generally tubular body having an outer
surface which is retained within the surrounding retaining sleeve
820. The collet 830 is internally threaded in order to connect to
the lower portion 856 of the shear tube 850. The collet 830 has a
plurality of radially spaced-apart collet fingers 832 which extend
downward in order to overlap with the upper portion of the mandrel
51. The collet fingers include a tapered, acme buttress box thread
or other style with constellations or other threads 836. These
collet finger threads 836 match threads 56 machined into the outer
surface of the mandrel 51.
[0098] A retrieval tube 860 is disposed below the shear tube 850.
The retrieval tube 860 defines a tubular body which encompasses a
portion of the threaded rod 840 below the adapter 810. An upper end
866 of the retrieval tube 860 resides proximate to the lower
portion 856 of the shear tube 850. The outer surface of the upper
end 866 of the retrieval tube 860 is threaded, so as to connect
with the inner threads of the collet 830.
[0099] The retrieval tube 860 generally extends downward in the
wellbore 10 adjacent to the rod 840. The retrieval tube 860
includes an enlarged inner diameter portion which defines a
shoulder 864. As will be described, the shoulder 864 of the
retrieval tube 860 will catch the shoulder 844 of the inner rod 840
when the retrieval mechanism 800 is removed from the wellbore
10.
[0100] Finally, a shear plane 845 is fabricated into the rod 840.
In the arrangement of FIG. 8C, the shear plane 845 is positioned
between the adapter 810 and the collet 830. The shear plane 845 is
essentially normal to the bore 52 of the mandrel 51.
[0101] In operation, the releasing mechanism 800 holds the mandrel
51 in place when the hydraulic setting tool 30 is actuated.
Connection is accomplished through the threads 56 of the mandrel 51
and the threads 836 of the collet 830. Because of the threaded
connections between the adapter 810, the rod 840, and the shear
tube 850, an upward force on the adapter 810 causes the inner rod
840 and the shear tube 850 to be urged upward in the wellbore 10.
Ultimately, releasing pressure is achieved within the hydraulic
setting tool 30. The shear tube 850 then fails along shear plane
845 in response to tensile forces created by the hydraulic setting
tool 30.
[0102] FIGS. 8C-R presents the releasing mechanism 800 after the
shear tube 850 has failed. After the shear tube 850 has failed, the
adapter 810, inner rod 840 and retaining sleeve 820 are raised
within the wellbore 10. The retaining sleeve 820 then clears the
collet fingers 832, allowing the collet fingers 832 to radially
expand outward from the fingers 56 of the mandrel 51. In this
regard, the collet fingers 832 are preferably pre-stressed in order
to be biased away from the mandrel 51. This allows the threads 836
of the collet fingers 832 to be released from the threads 56 of the
mandrel 51.
[0103] Once the collet fingers 832 are released from the mandrel
51, the adapter 810 is free to pull the inner rod 840 further in
the wellbore. Ultimately, the shoulder 844 of the rod 840 catches
the shoulder 864 of the retrieval tube 860. In this way, all parts
of the releasing mechanism 800 are retrieved from the wellbore
following release from the bridge plug 50. Release of the bridge
plug 50 is shown in FIGS. 8C-R.
DESIGN 9
[0104] Finally, a ninth design is provided as an alternative
arrangement for a releasing mechanism 900. This arrangement 900 is
similar to the releasing mechanism 500 of FIG. 5C. The releasing
mechanism 900 shown in FIG. 9C has the same parts as the releasing
mechanism 500 of FIG. 5C. However, an additional retrieval body 970
is disposed below the lower portion 910L of the adapter 910. The
retrieval body 970 includes an upper connecting portion 972 which
threadedly connects within the collet 930. The retrieval body 970
has a lower portion having an enlarged outer diameter in order to
define a shoulder 974. The lower portion 974 extends into the bore
52 of the mandrel 51 during run-in.
[0105] FIGS. 9C-R presents the releasing mechanism 900 being
removed from the wellbore 10 after reaching a releasing pressure. A
dog 965 on the retaining sleeve 960 catches a lower shoulder 938L
on the collet 930 as the adapter 910 is removed from the wellbore
10. This allows the collet 930 and the connected retrieval body 972
to be removed from the wellbore 10 along with the adapter 910 and
the retaining sleeve 960. The retaining sleeve 960 provides
reinforcing support for the mandrel 51 during the setting process
for the bridge plug 50.
[0106] A releasing mechanism for releasing a downhole tool has been
described in the context of releasing a bridge plug. However, it is
understood that the releasing mechanism of the present invention
has utility in any operation where wellbore fluids are circulated
downhole to release a tool. It is also understood that the
depictions of the releasing mechanism and other downhole tools are
not to scale. Neither the drawings, nor the description of the
drawings, are intended to limit the present invention to a
particular embodiment. Other and further embodiments of the
invention may be devised without departing from the basic scope
thereof, and the scope thereof is determined by the claims that
follow.
* * * * *