U.S. patent application number 10/426938 was filed with the patent office on 2004-02-26 for anti-extrusion assembly for a packing element system.
Invention is credited to Greenlee, Donald, Ritter, Michael G., Rochen, James A., Zimmerman, Patrick J..
Application Number | 20040036225 10/426938 |
Document ID | / |
Family ID | 24948460 |
Filed Date | 2004-02-26 |
United States Patent
Application |
20040036225 |
Kind Code |
A1 |
Ritter, Michael G. ; et
al. |
February 26, 2004 |
Anti-extrusion assembly for a packing element system
Abstract
The present invention generally relates to an apparatus and a
method for sealing a wellbore. In one aspect, a sealing apparatus
for use in a wellbore is provided. The apparatus includes a
compressible sealing member disposed around a body and an anchoring
device. The apparatus further includes an anti-extrusion assembly
having at least one flexible segment and one seal ring disposable a
each end of the compressible sealing member, wherein the
anti-extrusion assembly is constructed and arranged to form a
barrier around the ends of the compressible sealing member upon
expansion thereof. In another aspect, a downhole tool for sealing
an annulus of a wellbore is provided. In yet another aspect, a
method for sealing a wellbore is provided.
Inventors: |
Ritter, Michael G.; (Conroe,
TX) ; Rochen, James A.; (Waller, TX) ;
Zimmerman, Patrick J.; (Houston, TX) ; Greenlee,
Donald; (Murchison, TX) |
Correspondence
Address: |
MOSER, PATTERSON & SHERIDAN, L.L.P.
3040 POST OAK BOULEVARD, SUITE 1500
HOUSTON
TX
77056-6582
US
|
Family ID: |
24948460 |
Appl. No.: |
10/426938 |
Filed: |
April 30, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10426938 |
Apr 30, 2003 |
|
|
|
09733632 |
Dec 8, 2000 |
|
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Current U.S.
Class: |
277/328 |
Current CPC
Class: |
E21B 33/1208 20130101;
E21B 33/1216 20130101 |
Class at
Publication: |
277/328 |
International
Class: |
E21B 033/03 |
Claims
1. A sealing apparatus for use in a wellbore, comprising: a body; a
compressible sealing member disposed around the body; an
anti-extrusion assembly having at least one flexible segment and
one seal ring disposable at each end of the compressible sealing
member, wherein the anti-extrusion assembly is constructed and
arranged to form a barrier around the ends of the compressible
sealing member upon expansion thereof; and an anchoring device.
2. The apparatus of claim 1, wherein the flexible segment is
fabricated from a highly elastic material capable of forming to a
contour of a defined area.
3. The apparatus of claim 1, wherein the seal ring secures the
compressible sealing member to the body.
4. The apparatus of claim 1, wherein the flexible segment is
fabricated as part of the seal ring.
5. The apparatus of claim 1, further including a plurality of split
rings disposed adjacent the anti-extrusion assembly.
6. The apparatus of claim 5, wherein the anchoring device consists
of a plurality of cones and slips.
7. The apparatus of claim 6, wherein the anti-extrusion assembly is
formed into the profile of the plurality of cones and the plurality
of split rings upon expansion of the compressible sealing
member.
8. The apparatus of claim 1, wherein the anti-extrusion assembly
forms the barrier around a lower portion of the compressible
sealing member to prevent the compressible sealing member from
extruding under the anchoring device.
9. The apparatus of claim 1, wherein the mating surface of the
anti-extrusion assembly includies a smooth machined surface and a
slick coating.
10. The apparatus of claim 1, further including a spacer disposed
at the lower end of the flexible segment.
11. The apparatus of claim 1, wherein the flexible segment is
disposed adjacent the seal ring.
12. A downhole tool for sealing an annulus of a wellbore,
comprising: a body; and an anchoring and sealing system disposed
about the body, wherein the anchoring and sealing system comprises:
a compressible sealing member; an anti-extrusion assembly having at
least one flexible segment and one seal ring disposable a each end
of the compressible sealing member, wherein the anti-extrusion
assembly is constructed and arranged to form a barrier around the
ends of the compressible sealing member upon expansion thereof; a
cone and slip arrangement; and a plurality of split rings disposed
adjacent the anti-extrusion assembly.
13. The downhole tool of claim 12, wherein the flexible segment is
fabricated from a highly elastic material capable of forming to a
contour of a defined area.
14. The downhole tool of claim 12, wherein the flexible segment
forms the barrier around the lower portion of the compressible
sealing member.
15. The downhole tool of claim 12, wherein the flexible segment is
fabricated as part of the seal ring.
16. A method for sealing a wellbore, comprising: running a sealing
apparatus in to the wellbore, the sealing apparatus comprising: a
body; a compressible sealing member disposed around the body; an
anti-extrusion assembly having at least one flexible segment and
one seal ring disposable a each end of the compressible sealing
member, wherein the anti-extrusion assembly is constructed and
arranged to form a barrier around the ends of the compressible
sealing member upon expansion thereof; and an anchoring device;
applying an axial force to the sealing apparatus to cause the
anchoring device to grip the wellbore; expanding the sealing member
into contact with an area of the wellbore; and deforming the
flexible segment and creating a barrier to prevent the sealing
member from extruding under the anchoring device.
17. The method of claim 16, wherein the flexible segment is
fabricated from a highly elastic material capable of forming to a
contour of a defined area.
18. The method of claim 16, wherein the anchoring device consists
of a cone and slip arrangement.
19. The method of claim 16, further including bridging any gaps
between the sealing member and the anchoring device due to
activation of the sealing apparatus.
20. The method of claim 16, wherein the sealing apparatus further
includes a plurality of split rings disposed adjacent the
anti-extrusion assembly.
21. The method of claim 20, further including containing the
sealing member within a predefined space by the anti-extrusion
assembly and the plurality of split rings.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of co-pending
U.S. patent application Ser. No. 09/733,632, entitled High
Temperature And Pressure Element System, filed on Dec. 8, 2000,
which patent application is herein incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to downhole packers. More
particularly, the present invention relates to a high pressure and
temperature element system for a downhole packer.
[0004] 2. Description of the Related Art
[0005] Downhole packers are typically used to seal an annular area
formed between two co-axially disposed tubulars within a wellbore.
For example, downhole packers may seal an annulus formed between
production tubing disposed within wellbore casing. Alternatively,
packers may seal an annulus between the outside of a tubular and an
unlined borehole. Routine uses of packers include the protection of
casing from pressure, both well and stimulation pressures, as well
as the protection of the wellbore casing from corrosive fluids.
Other common uses include the isolation of formations or leaks
within a wellbore casing or multiple producing zones, thereby
preventing the migration of fluid between zones. Packers may also
be used to hold kill fluids or treating fluids within the casing
annulus.
[0006] Conventional packers typically comprise a sealing element
located between upper and lower retaining rings or elements. The
sealing element is typically a synthetic rubber composite which can
be compressed by the retaining rings to expand radially outward
into contact with an inner surface of a well casing there-around.
This compression and expansion of the sealing element seals the
annular area by preventing the flow or passage of fluid across the
expanded sealing element.
[0007] Conventional packers are typically run into a wellbore
within a string of tubulars and anchored in the wellbore using
mechanical compression setting tools or fluid pressure devices.
Conventional packers are also typically installed using cement or
other materials pumped into an inflatable sealing element.
[0008] One problem associated with conventional packers arises with
high temperature and/or high pressure applications. High
temperatures are generally defined as downhole temperatures above
300.degree. F. and up to 450.degree. F. High pressures are
generally defined as downhole pressures above 7,500 psi and up to
15,000 psi. At these temperatures and pressures, conventional
sealing elements become ineffective. Most often, the physical
properties of the sealing element suffer from degradation due to
the extreme conditions. For example, the sealing element may
experience a loss of elasticity. Alternatively, the sealing element
may melt or otherwise decrease in viscosity and flow or
extrude.
[0009] Another problem associated with conventional packers occurs
during the activation of the conventional packer at high
temperatures and pressures. Most often, the sealing element softens
and possibly flows before the packer reaches its final destination
in the wellbore. Consequently, the sealing element becomes
disconfigured and cannot be properly activated. As a result, the
sealing element does not adequately seal the annulus.
[0010] Yet another problem associated with the packing element
system of the conventional packer arises when the conventional
packer is no longer needed to seal the wellbore, and must be
removed from the well. For example, plugs and packers are sometimes
intended to be temporary and must be removed to access the wellbore
there below. Rather than de-actuate the packer and bring it to the
surface of the well, the packer is typically destroyed with a
rotating milling or drilling device. As the mill contacts the
packer, the packer is "drilled up" or reduced to small pieces that
are either washed out of the wellbore or simply left at the bottom
of the hole. The more parts making up the conventional packer, the
longer the milling operation takes. Longer milling time, leads to
an increase in wear and tear of the drill bit and additional
expensive rig time.
[0011] Furthermore, another problem associated with the packing
element system of the conventional packer is the manufacturing
cost. Additional parts increase the cost and complexity of the
packer.
[0012] Therefore, there is a need for a downhole packer having an
element system that can resist or prevent extrusion or degradation
in high temperature and/or high pressure applications. There is
also a need for a method for actuating a downhole packer that can
withstand a high temperature and/or high pressure environment by
staging the expansion of a sealing element and minimizing a void
within an annulus to be sealed. Further, there is a need for a
packing element system for use in a downhole packer that will
minimize the time of a milling operation upon removal of the
packer, and subsequently reduce the wear and tear on the drill bit.
There is a further need for a packing element system with fewer
components, thereby reducing the manufacturing cost.
SUMMARY OF THE INVENTION
[0013] The present invention generally relates to an apparatus and
a method for sealing a wellbore. In one aspect, a sealing apparatus
for use in a wellbore is provided. The apparatus includes a
compressible sealing member disposed around a body and an anchoring
device. The apparatus further includes an anti-extrusion assembly
having at least one flexible segment and one seal ring disposable a
each end of the compressible sealing member, wherein the
anti-extrusion assembly is constructed and arranged to form a
barrier around the ends of the compressible sealing member upon
expansion thereof.
[0014] In another aspect, a downhole tool for sealing an annulus of
a wellbore is provided. The downhole tool includes an anchoring and
sealing system disposed about a body. The anchoring and sealing
system includes a compressible sealing member and a cone and slip
arrangement. The anchoring and seal system further includes an
anti-extrusion assembly having at least one flexible segment and
one seal ring disposable a each end of the sealing member, wherein
the anti-extrusion assembly is constructed and arranged to form a
barrier around the ends of the compressible sealing member upon
expansion thereof.
[0015] In another aspect, a method for sealing a wellbore is
provided. The method includes running a sealing apparatus in to the
wellbore. The sealing apparatus includes a compressible sealing
member disposed around a body and an anti-extrusion assembly having
at least one flexible segment and one seal ring disposable a each
end of the sealing member, wherein the anti-extrusion assembly is
constructed and arranged to form a barrier around the ends of the
compressible sealing member upon expansion thereof. The method
further includes applying an axial force to the sealing apparatus
to cause the anchoring device to grip the wellbore and expanding
the sealing member into contact with an area of the wellbore. The
method also includes deforming the flexible segment and creating a
barrier to prevent the sealing member from extruding under the
anchoring device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] So that the manner in which the above recited features,
advantages, and objects 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.
[0017] It is to be noted, however, that the appended drawings
illustrate only typical embodiments of this invention and are
therefore not to be considered limiting of its scope, for the
invention may admit to other equally effective embodiments.
[0018] FIG. 1 is a cross section of a packer of the present
invention.
[0019] FIG. 1A is an enlarged view of a retaining assembly disposed
about a body of the packer shown in FIG. 1.
[0020] FIG. 2 is a partial cross section of the packer during a
first stage of activation.
[0021] FIG. 3 is a partial cross section of the packer during a
second stage of activation.
[0022] FIG. 4 is a partial cross section of the packer during a
third stage of activation.
[0023] FIG. 4A is an enlarged view of the element system disposed
about the body of the packer shown in FIG. 4 during the third stage
of activation.
[0024] FIG. 5A is a cross-sectional view illustrating a preferred
embodiment of an anti-extrusion assembly prior to activation of a
sealing apparatus.
[0025] FIG. 5B is an enlarged view of the anti-extrusion
assembly.
[0026] FIG. 5C is a cross-sectional view illustrating the preferred
embodiment of the anti-extrusion assembly during the initial
activation stage of the sealing apparatus.
[0027] FIG. 5D is a cross-sectional view illustrating the preferred
embodiment of the anti-extrusion assembly after the activation of
the sealing apparatus.
[0028] FIG. 6A is an enlarged cross-sectional view illustrating an
alternative embodiment of an anti-extrusion assembly with a spacer
prior to activation of the sealing apparatus.
[0029] FIG. 6B is an enlarged cross-sectional view illustrating the
anti-extrusion assembly with the spacer after activation of the
sealing apparatus.
[0030] FIG. 7A is an enlarged cross-sectional view illustrating an
alternative embodiment of an anti-extrusion assembly prior to
activation of the sealing apparatus.
[0031] FIG. 7B is an enlarged cross-sectional view illustrating the
anti-extrusion assembly after activation of the sealing
apparatus.
[0032] FIG. 8A is an enlarged cross-sectional view illustrating an
alternative embodiment of an anti-extrusion assembly prior to
activation of the sealing apparatus.
[0033] FIG. 8B is an enlarged cross-sectional view illustrating the
anti-extrusion assembly after activation of the sealing
apparatus.
[0034] FIG. 9A is an enlarged cross-sectional view illustrating a
two piece anti-extrusion assembly prior to activation of the
sealing apparatus.
[0035] FIG. 9B is an enlarged cross-sectional view illustrating the
two piece anti-extrusion assembly after activation of the sealing
apparatus.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0036] FIG. 1 is a cross section of a high temperature down hole
packer 100. According to one aspect of the invention, the packer
100 includes a body 102 having a first and second retaining system
and an element system disposed there-around. The body 102 may
include a longitudinal bore there through, and may include a sealed
bore there-through. The retaining systems are disposed at either
end of the element system and all are comprised of ring-shaped
components concentrically disposed about the body 102. The element
system comprises filler rings 320, 620, containment rings 340, 640,
anti-extrusion rings 360, 660, back-up rings 380, 680, and an
element 500. The first and second retaining system each comprises
slips 200, 400, cones 220, 420, expansion rings 260, 460, and slide
rings 300, 600. In operation, the retaining systems secure the
packer 100 within a tubular therearound, such as casing for
example, and provide the boundaries of an annular area for the
element system to expand and seal, thereby providing an effective
seal in high temperature and high pressure applications.
[0037] For ease and clarity of description, the packer 100 will be
further described in more detail as if disposed within a tubular
700 in a vertical position as oriented in the figures. It is to be
understood, however, that the packer 100 may be disposed in any
orientation, whether vertical or horizontal. It is also to be
understood that the packer 100 may be disposed in a borehole
without a tubular therearound. Additionally, for ease and clarity
of description, the first retaining system and an upper portion of
the element system will be described since the components of the
second retaining system and a lower portion of the element system
are substantially identical.
[0038] Considering the retaining system in greater detail, the slip
200 is disposed about the body 102 adjacent a first end 221 of the
cone 220. Each slip 200 comprises a tapered inner surface 201
conforming to the first end 221 of the cone 220. An outer surface
of the slip 200, preferably includes at least one outwardly
extending serration or edged tooth 205, to engage an inner surface
of the tubular 700 when the slip 200 is driven radially outward
from the body 102 by the movement of the sloped surfaces of the
cones 220, 420 thereunder.
[0039] The slip 200 is designed to fracture with radial stress as
the cones 220, 420 are driven thereunder. The slip 200 typically
includes at least one recessed groove (not shown) milled therein to
fracture under stress allowing the slip 200 to expand outwards to
engage the inner surface of the tubular 700. For example, the slip
200 may include four evenly sloped segments separated by equally
spaced recessed grooves to contact the tubular 700 and become
evenly distributed about the outer surface of the body 102.
[0040] The cone 220 is disposed about the body 102 adjacent the
slip 200 and is secured to the body 102 by a plurality of shearable
members such as shear pins 106. As stated above, the cone 220
comprises a tapered first end 221 which rests underneath the
tapered inner surface 201 of the slip 200. The slip 200 travels
about the tapered first end 221 of the cone 220, thereby expanding
radially outward from the body 102 to engage the inner surface of
the tubular 700. Referring to FIG. 1A, the cone 220 also comprises
a second end 223 which is tapered and abuts a corresponding tapered
end 261 of the expansion ring 260.
[0041] Referring to FIGS. 1 and 1A, the expansion ring 260 is
disposed between the cone 220 and the slide ring 300. In the
preferred embodiment, the expansion ring 260 includes a male split
ring 270 and a female split ring 280. The male and female split
rings 270, 280, are disposed about the body 102 so that their
respective expandable openings are not vertically aligned. In this
orientation, the male split ring 270 and female split ring 280
provide a solid circumferential barrier against extruded or
expanded material of back-up ring 380. The male split ring 270, as
depicted in section view, includes three sides. A first side 261
has a sloped surface corresponding to the sloped second end 223 of
the cone 220 as described above. A second side is substantially
flat or perpendicular to the body 102, with an extension 265
extending therefrom. The female split ring 280 also includes three
sides, visible in section view, including a substantially flat or
perpendicular first side having a recessed groove 285 disposed
therein. The female split ring 280 also includes a second side
having a tapered surface 283 to abut a first end of the slide ring
300. The extension 265 disposed on the second side of the male
split ring 270 is disposable within the recessed groove 285. The
extension 265 and recessed groove 285 allow the male and female
split rings 270, 280 to engage one another thereby allowing the
expansion rings 260, 460 to move radially outward from the body 102
as a single unit.
[0042] The slide ring 300 includes a first end having a first 301
and second 303 tapered surface. The first tapered surface 301
corresponds to the second tapered surface 283 of the female split
ring 280. The second tapered surface 303 is sloped in an opposite
direction from the first tapered surface 301 and corresponds to the
sloped second end 223 of the cone 220. The slide ring 300 also
includes a second end abutting the filler ring 320 and having an
extension 307 disposed thereon. The extension 307 extends axially
away from the slide ring 300 toward the element 500 and extends
between a portion of an inner surface of the filler rings 320, 620
and an outer surface of the body 102.
[0043] Considering the element system in greater detail, the filler
ring 320 comprises two sections, a larger diameter section and a
smaller diameter section which form a shoulder 325 at the interface
of the two sections. The smaller diameter section of the filler
ring 320 is disposed about the extension 307 of slide ring 300. The
larger diameter section rests against the outer surface of the body
102. The filler ring 320 may be manufactured from Teflon.RTM. or
any flexible plastic or resin material which flows at a
predetermined temperature. As will be explained below, the filler
ring 320 will expand under high temperature and/or pressure and
create a collapse load on the extension 307 of the slide ring 300.
This collapse load holds the slide ring 300 firmly against the body
102.
[0044] A spacer ring 310 is disposed about the body 102 between the
slide ring 300 and the filler ring 320. The spacer ring 310 serves
to accommodate tolerance variations created during the
manufacturing of the element system.
[0045] The back-up ring 380 is disposed about the body 102 between
the element 500 and the filler ring 320. The back-up ring 380
includes a recessed groove 385 formed in a portion of an outer
surface thereof. Similar to the filler ring 320 the back-up ring
380 may be manufactured from Teflon.RTM. or any flexible plastic or
resin material which flows at a predetermined temperature. At high
temperatures, the back-up ring 380 expands radially outward from
the body 102 and flows across the outer surface of the body 102. As
will be explained below, the back-up ring 380 helps to fill a void
550 created between the expansion rings 260, 460, thereby reducing
a volume of the void 550 to be filled by the element 500.
[0046] The anti-extrusion ring 360 is disposed in a portion of the
groove 385 and extends over the second portion of the filler ring
320. The anti-extrusion ring 360 includes a lip 365 which extends
radially inward toward the body 102. The lip 365 is disposed
adjacent the shoulder 325 formed between the larger diameter and
the smaller diameter sections of the filler ring 320. As will be
explained below, the lip 365 prevents the filler ring 320 from
flowing or traveling between the anti-extrusion ring 360 and the
containment ring 340. The lip 365 also acts as a carrier when the
back-up ring 380 expands and travels over the slide ring 300.
[0047] The containment ring 340 is disposed about an outer surface
of the smaller diameter section of the filler rings 320, 620. The
containment ring 340 includes a first end which abuts the spacer
ring 310 and a second end which abuts the anti-extrusion ring 360.
As will be explained below, the containment ring 340 holds the
filler ring 320 in place and prevents the filler ring 320 from
extruding across an outer surface of the slide ring 300.
[0048] The element 500 is disposed about the body 102 between the
back-up rings 380, 680. The element 500 may have any number of
configurations to effectively seal the annulus created between the
body 102 and the casing wall. For example, the element 500 may
include grooves, ridges, indentations, or extrusions designed to
allow the element 500 to conform to variations in the shape of the
interior of the tubular 700 there-around. The element 500 can be
constructed of any expandable or otherwise malleable material which
creates a permanent set position and stabilizes the body 102
relative to the wellbore casing. For example, the element 500 may
be a metal, a plastic, an elastomer, or a combination thereof. The
element 500, however, must withstand temperatures in excess of
450.degree. F., and pressures in excess of 15,000 psi.
[0049] Referring to FIG. 4, the packer 100 further includes a
ratchet assembly 800 disposed about a first end of the packer 100
to prevent the components described above from prematurely
releasing once the components have been actuated. The ratchet
assembly 800 includes a ring housing 810 disposed about a lock ring
830 and is disposed about the body 102 adjacent to and abutting a
first end of the slip 200.
[0050] The lock ring 830 is a cylindrical member annularly disposed
between the body 102 and the ring housing 810 and includes an inner
surface having profiles disposed thereon to mate with profiles
formed on the outer surface of the body 102. The profiles formed on
the lock ring 830 have a tapered leading edge allowing the lock
ring 830 to move across the mating profiles formed on the body 102
in one axial direction while preventing movement in the other
direction. The profiles formed on both the outer surface of the
body 102 and an inner surface of the lock ring 830 consist of
formations having one side which is sloped and one side which is
perpendicular to the outer surface of the body 102. The sloped
surfaces of the mating profiles allows the lock ring 830 to move
across the body 102 in a single axial direction. The perpendicular
sides of the mating profiles prevent movement in the opposite axial
direction. Therefore, the split ring may move or "ratchet" in one
axial direction, but not the opposite axial direction.
[0051] The ring housing 810 comprises a jagged inner surface to
engage a mating jagged outer surface of the lock ring 830. The
relationship between the jagged surfaces creates a gap
there-between allowing the lock ring 830 to expand radially as the
profiles formed thereon move across the mating profiles formed on
the body 102. A longitudinal cut within the lock ring 830 allows
the lock ring 830 to expand radially and contract as it movably
slides or ratchets in relation to the outer surface of the body
102. The ring housing 810 also comprises a first end which abuts a
first end of the slip 200 thereby transferring movement of the
ratchet assembly 800 to the slip 200.
[0052] To set or activate the packer 100, the packer 100 is first
run down the hole to a predetermined depth. A setting tool applies
an axial load to the outer components of the packer 100 relative to
the body 102. Once the axial force reaches a predetermined value,
the pins 106 release or shear, thereby causing the outer components
to move axially across the body 102.
[0053] FIG. 2 is a section view of a packer 100 during a first
stage of activation. During a first stage of activation, axial
movement of the outer components forces the cone 420 underneath the
slip 400, thereby forcing the slip 400 radially outward toward the
tubular 700. As shown in FIGS. 2 and 4A, the slip 400 engages the
inner surface of the tubular 700 creating an opposing axial force
which causes the expansion rings 260, 460, to slide radially
outward across the surface 223 of the cones 220, 420 and across the
first tapered surface 301 of the slide rings 300, 600, thereby
engaging the inner surface of the tubular 700. The actuation of the
expansion rings 260, 460, provide a fixed volume or void space 550
within the annulus to be sealed off by the element 500 and back-up
rings 380, 680 and also provide an extrusion barrier on the face of
the cones 220, 420, and the inner surface of the tubular 700.
[0054] The axial forces next cause the recessed grooves of the slip
400 to fracture, and divide into equal segments, permitting the
serrations or teeth 405 to engage the inner surface of the tubular
700. Once the slip 400 fractures, the axial forces across the body
102 are met by an equal and opposite axial force which causes the
malleable outer portions of the packer 100 to compress and expand
radially outward.
[0055] FIG. 3 shows a second stage of activation which involves
extruding the back-up rings 380, 680. As shown, the compressive
forces exerted against opposite sides of the back-up rings 380, 680
cause the back-up rings 380, 680, to expand radially outward toward
the tubular 700. Expansion of the back-up rings 380, 680, causes
the anti-extrusion rings 360, 660 to expand due to the applied hoop
stress created by the expanding back-up rings 380, 680. As the
anti-extrusion rings 360, 660, yield, the back-up rings 380, 680,
are allowed to travel or flow up and over the filler rings 320,
620, the containment rings 340, 640, and the slide rings 300, 600,
as shown in FIG. 4. The increasing pressure exerted by the back-up
rings 380, 680, and the element 500 applies a load to the filler
rings 320, 620, that applies a collapse load on the extension 307
of the slide rings 300, 600, thereby eliminating any extrusion
between the slide rings 300, 600, and the body 102. The lip 365
formed on the first end of the anti-extrusion rings 360, 660,
prevents the filler rings 320, 620, from flowing or traveling
between the anti-extrusion rings 360, 660, and the containment
rings 340, 640. The lip 365 also acts as a carrier when the back-up
rings 380, 680, expands and travels over the slide rings 300, 600.
The anti-extrusion rings 360, 660, also serve to retain the back-up
rings 380, 680, until the expansion rings 260, 460, are fully
expanded against the tubular 700.
[0056] FIG. 4 shows a third stage of activation. During a third
stage of activation, the back-up rings 380, 680 flow and fill a
substantial portion of the void 550 created by the expansion rings
260, 460, while the element 500 is expanded radially outward toward
the tubular 700 to seal off the remaining portion of the void 550.
Because the back-up rings 380, 680, occupy a significant portion of
the void 550, the element 500 must only expand radially outward,
not axially, to fill the remaining void 550. As a result, less
stress is placed on the element 500, and the element 500 is less
subject to degradation providing a more effective seal for a longer
period of time.
[0057] During the final stages of activation, the axial forces
cause the ratchet assembly 800 to move or ratchet down the outer
surface of the body 102. As described herein, the ratcheting is
accomplished when the axial forces against the lock ring 830 cause
the profiles formed on the ring 830 to ramp up and over the mating
profiles formed on the outer surface of the body 102. Once the
profiles of the ring 830 travel up and over the adjoining profiles
of the body 102, the first lock ring 830 contracts or snaps back
into place, re-setting or interlocking the concentric profiles of
the lock ring 830 against the next adjoining profiles formed on the
outer surface of the body 102. In this manner, the ratchet assembly
800 moves in a first direction and not in a second, opposite
direction.
[0058] In another aspect, the present invention includes a packing
element system for use in a sealing apparatus. Generally, the
sealing apparatus is placed within the wellbore to isolate the
upper and lower zones of the wellbore. Additionally, the sealing
apparatus may be used to create a pressure seal in the wellbore in
order to treat the isolated formation with pressurized fluids or
solids. As illustrated, the sealing apparatus is a packer. It is to
be understood, however, that the sealing apparatus could be a
bridge plug or a frac-plug or any other device used to seal off a
wellbore.
[0059] FIG. 5A is a cross-sectional view illustrating a preferred
embodiment of an anti-extrusion assembly 900 prior to activation of
a sealing apparatus 750. In this embodiment, the anti-extrusion
assembly 900 comprises of a thin flexible segment 905 machined as
part of a conventional seal ring 910. Preferably, the thin flexible
segment 905 is constructed from a highly elastic material that is
capable of forming to the contour of a defined area, thereby
bridging any gaps that may occur during activation of the sealing
apparatus 750.
[0060] FIG. 5B is an enlarged view of the anti-extrusion assembly
900. As shown, the segment 905 is formed on the lower portion of
the conventional seal ring 910. This arrangement allows the segment
905 to follow the contour of a sealing element 710. Preferably, the
anti-extrusion assembly 900 is fabricated from a material with
mechanical properties that will withstand high temperatures and
pressures while remaining ductile in order to be milled or drilled
through quickly.
[0061] Referring back to FIG. 5A, the primary purpose of the
conventional seal ring 910 is to hold the sealing element 710 on a
mandrel 715 of the sealing apparatus 750. As illustrated, the
anti-extrusion assembly 900 is disposed on both the upper and lower
ends of the sealing element 710. In this respect, the
anti-extrusion assembly 900 of this embodiment serves two
functions. The first function is to aid in securing the element 710
to the mandrel 715, and the second function is to provide a solid
barrier to the lower portion of the element 710 upon the activation
of the sealing apparatus 750. To facilitate the formation of the
barrier, the mating surface to the anti-extrusion assembly 900
includes a machined smooth surface and covered with a slick
coating.
[0062] Adjacent the anti-extrusion assembly 900 is a plurality of
split rings 725. Similar to the split rings described in a previous
paragraph, the split rings 725 include a male split ring and a
female split ring. Preferably, the male and female split rings are
disposed about the mandrel 715 so that their respective expandable
openings are not vertically aligned. In this orientation, the male
split ring and female split ring provide a solid circumferential
barrier for the anti-extrusion assembly 900 prior to activation of
the sealing apparatus 750.
[0063] As illustrated, cones 720, 770 are disposed adjacent each
split ring 725 and secured to the mandrel 715 by a plurality of
shearable members 735. The cones 720, 770 include a first tapered
end that abuts to a corresponding tapered end of the split rings
725. The cones 720, 770 further include a second tapered end which
rests underneath a tapered inner surface of a plurality of slips
740, 760.
[0064] Preferably, the slips 740, 760 are disposed about the
mandrel 715 adjacent the cones 720, 770. Each of the slips 740, 760
include at least one outwardly extending serration or edged tooth
to engage an inner surface of a surrounding casing 730 as the slips
740, 760 are driven radially outward as they ride up the second
tapered end of the cones 720, 770. As previously described, the
slips 740, 760 are designed to radially fracture as the cones 720,
770 are driven thereunder to ensure an effective engagement with
the casing 730.
[0065] FIG. 5C is a cross-sectional view illustrating the preferred
embodiment of the anti-extrusion assembly 900 during the initial
activation stage of the sealing apparatus 750. As similarly
discussed in FIG. 2, the axial movement of the outer components
apply an axial force on the cones 720, 770. At a predetermined
force, the shear members 735 fail permitting the cones 720, 770 to
move axially. Simultaneously, the cone 770 is forced underneath the
slip 760, thereby forcing the slip 760 radially outward towards the
casing 730. As the slip 760 engages the inner surface of the casing
730, an opposing axial force is created which causes the split
rings 725 to move radially outward across the first tapered end of
the cones 720, 770 and across a tapered end of the anti-extrusion
assembly 900, thereby engaging the inner surface of the casing 730.
The actuation of the split rings 725 provide an upper extrusion
barrier for the element 710.
[0066] FIG. 5D is a cross-sectional view illustrating the preferred
embodiment of the anti-extrusion assembly 900 after the activation
of the sealing apparatus 750. As similarly discussed in FIG. 4, the
element 710 is expanded radially outward towards the casing 730 to
create a sealing relationship between the sealing apparatus 750 and
the casing 730 and to fill the void created between the split rings
725. At the same time, the element 710 forces the anti-extrusion
assembly 900 against the split rings 725 and the cones 720, 770
causing the segment 905 to form into the profile of the cones 720,
770 resulting in the formation of a solid barrier to prevent the
element 710 from extruding under the split rings 725 and the cones
720, 770. In this respect, the upper portion of the element 710 is
contained by the plurality of split rings 725 while the lower
portion of the element 710 is contained by the flexible segment 905
of the anti-extrusion assembly 900, thereby protecting the element
710 from degradation and containing the element 710 in a defined
area.
[0067] FIG. 6A is an enlarged cross-sectional view illustrating an
alternative embodiment of an anti-extrusion assembly 915 with a
spacer 920 prior to activation of the sealing apparatus 750.
Similar to the previous embodiment, the anti-extrusion assembly 915
is disposed adjacent each side of the element 710. The
anti-extrusion assembly 915 includes the conventional seal ring 910
and the flexible segment 905. Additionally, the anti-extrusion
assembly 915 includes the spacer 920 disposed at the lower end of
the flexible segment 905. The spacer 920 is typically fabricated
from a metallic material to provide a rigid barrier at the lower
end of the segment 905. However, the spacer 920 may be fabricated
from other types of material so long as the material has the
capability to provide a rigid base for the flexible segment 905. As
illustrated in this embodiment, the spacer 920 is orientated in a
manner to provide the greatest amount of surface area for the
contact with the cones 720, 770 upon actuation of the sealing
apparatus 750. It is to be understood, however, that the spacer 920
may be disposed below the flexible segment 905 in any orientation,
such as in front of the flexible segment 905 or behind the flexible
segment 905 to provide an effective barrier to the lower portion of
the element 710.
[0068] FIG. 6B is an enlarged cross-sectional view illustrating the
anti-extrusion assembly 915 with the spacer 920 after activation of
the sealing apparatus 750. In a similar manner as previously
described, the activation of the sealing apparatus 750 moves the
cones 720, 770 axially, thereby causing the split rings 725 to move
radially outward from an upper barrier for the element 710.
Subsequently, the element 710 is expanded radially outward toward
the casing 730 to create a sealing relationship between the sealing
apparatus 750 and the casing 730 and to fill the void created
between the split rings 725. At the same time, the element 710
forces the anti-extrusion assembly 915 and the spacer 920 against
the split rings 725 and the cones 720, 770 causing the segment 905
to form into the profile of the cones 720, 770. The formation of
the segment 905 and the movement of the spacer 920 results in the
creation of a solid barrier to prevent the element 710 from
extruding under the split rings 725 and the cones 720, 770.
[0069] FIG. 7A is an enlarged cross-sectional view illustrating an
alternative embodiment of an anti-extrusion 925 device prior to
activation of the sealing apparatus 750. Similar to the previous
embodiment, the anti-extrusion assembly 925 is disposed adjacent
each side of the element 710 and includes the conventional seal
ring 910 and the flexible segment 905. As shown in this embodiment,
the flexible segment 905 follows the contour of the split rings 725
prior to the activation of the sealing apparatus 750. This
arrangement permits the flexible segment 905 to be molded upon
activation of the sealing apparatus 750 to create an effective
barrier for the element 710.
[0070] FIG. 7B is an enlarged cross-sectional view illustrating the
anti-extrusion 925 device after activation of the sealing apparatus
750. In a similar manner as previously described, the axial force
applied to the sealing apparatus 750 causes the cones 720, 770 to
move axially, thereby urging the split rings 725 radially outward
to seal from an upper barrier for the element 710. Upon radial
movement of the split rings 725, the lower portion of the flexible
segment 905 previously contoured to the split rings 725 becomes
exposed. Subsequently, the element 710 is expanded radially outward
toward the casing 730 to create a sealing relationship between the
sealing apparatus 750 and the casing 730 and to fill the void
created between the split rings 725. At the same time, the element
710 forces the anti-extrusion assembly 925 against the split rings
725 and the cones 720, 770 causing the segment 905 to form into the
profile of the cones 720, 770 resulting in the formation of a solid
barrier to prevent the element 710 from extruding under the split
rings 725 and the cones 720, 770.
[0071] FIG. 8A is an enlarged cross-sectional view illustrating an
alternative embodiment of an anti-extrusion assembly 930 prior to
activation of the sealing apparatus 750. Similar to a previous
embodiment, the anti-extrusion assembly 925 is disposed adjacent
each side of the element 710 and includes the conventional seal
ring 910 and the flexible segment 905. As shown in this embodiment,
the flexible segment 905 is constructed and arranged to follow the
contour of the conventional seal ring 910 and the split rings 725
prior to the activation of the sealing apparatus 750. In this
arrangement, the flexible segment 905 may be deformed upon the
activation of the sealing apparatus 750 to create an effective
barrier for the element 710.
[0072] FIG. 8B is an enlarged cross-sectional view illustrating the
anti-extrusion assembly 930 after activation of the sealing
apparatus 750. In a similar manner as previously described, the
axial force on the sealing apparatus 750 causes the cones 720, 770
to move axially, thereby causing the split rings 725 to move
radially outward to contact with the surrounding casing 730. Upon
radial outward movement of the split rings 725, the lower portion
of the flexible segment 905 previously contoured to the split ring
725 becomes exposed. Subsequently, the element 710 is expanded
radially outward towards the casing 730 to create a sealing
relationship between the sealing apparatus 750 and the casing 730
and to fill the void created between the split rings 725. At the
same time, the element 710 forces the anti-extrusion assembly 930
against the split rings 725 and the cones 720, 770 causing the
segment 905 to form into the profile of the cones 720, 770. This
formation of the segment 905 results in the creation of a solid
barrier to prevent the element 710 from extruding under the split
rings 725 and the cones 720, 770. Therefore, the element 710 is
defined within a predetermined area with a seal barrier on the
upper portion of the element 710 created by the split rings 725 and
the seal barrier on the lower portion of the element 710 created by
the flexible segment 905.
[0073] FIG. 9A is an enlarged cross-sectional view illustrating a
two piece anti-extrusion assembly 935 prior to activation of the
sealing apparatus 750. In a similar manner to the previous
embodiment, the anti-extrusion assembly 935 is disposed adjacent
each side of the element 710. The anti-extrusion assembly 935
includes a ring 940 to hold the sealing element 710 to the mandrel
715. The anti-extrusion assembly 935 further includes an end
segment 945 disposed adjacent the ring 940 but not rigidity
attached to the ring 940. As shown in this embodiment, the end
segment 945 is constructed and arranged to form a partial enclosure
around the ring 940 and the element 710 prior to activation of the
sealing apparatus 750. Preferably, the end segment 945 is
constructed from a high elastic material capable of forming to the
contour of a defined area.
[0074] FIG. 9B is an enlarged cross-sectional view illustrating the
two piece anti-extrusion assembly 935 after activation of the
sealing apparatus 750. In a similar manner as previously described,
the axial force applied to the sealing apparatus 750 causes the
cones 720, 770 to move axially, thereby urging the split rings 725
to move radially outward. Thereafter, the element 710 is compressed
and urged radially outward to form a seal with the surrounding
casing 730. At the same time, the element 710 forces the end
segment 945 against the split rings 725 and the cones 720, 770
causing the end segment 945 to form into the profile of the split
rings 725 and the cones 720, 770 resulting in the formation of a
solid barrier to prevent the element 710 from extruding under the
split rings 725 and the cones 720, 770.
[0075] While foregoing is directed to the preferred embodiment of
the present invention, 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.
* * * * *