U.S. patent application number 15/800966 was filed with the patent office on 2019-05-02 for axially articulated and rotationally locked backup ring assembly for a sealing element.
This patent application is currently assigned to Baker Hughes, a GE company, LLC. The applicant listed for this patent is Baker Hughes, a GE company, LLC. Invention is credited to Guijun Deng, Daniel Guerra, Alexander M. Kendall, John K. Wakefield.
Application Number | 20190128089 15/800966 |
Document ID | / |
Family ID | 66242752 |
Filed Date | 2019-05-02 |
United States Patent
Application |
20190128089 |
Kind Code |
A1 |
Guerra; Daniel ; et
al. |
May 2, 2019 |
Axially Articulated and Rotationally Locked Backup Ring Assembly
for a Sealing Element
Abstract
A backup or extrusion barrier ring assembly has multiple rows of
rings in segments that have circumferentially offset slots. The
rings are rotationally locked to each other to maintain the
circumferential offset of the slots that allow the rings to be more
flexible in the setting process. The rings as a unit can be mounted
to relatively rotate on a supporting mandrel. The rings are mounted
to allow them to move axially during setting either in tandem or
axially relatively to each other. The axial run in heights of rings
decline from innermost to outermost so that when set the heights
approach each other to minimize or eliminate sharp ends against the
seal. Alternatively, the height difference can be such as to allow
ends to bend over an adjacent end further out radially so that free
ends bend toward the surrounding tubular and avoid the seal.
Inventors: |
Guerra; Daniel; (Sugar Land,
TX) ; Deng; Guijun; (The Woodlands, TX) ;
Kendall; Alexander M.; (Houston, TX) ; Wakefield;
John K.; (Cypress, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Baker Hughes, a GE company, LLC |
Houston |
TX |
US |
|
|
Assignee: |
Baker Hughes, a GE company,
LLC
Houston
TX
|
Family ID: |
66242752 |
Appl. No.: |
15/800966 |
Filed: |
November 1, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 33/128 20130101;
E21B 33/1216 20130101 |
International
Class: |
E21B 33/12 20060101
E21B033/12 |
Claims
1. An extrusion barrier assembly for a mandrel mounted sealing
element in a borehole barrier, comprising: a plurality of nested
discrete rings mounted to the mandrel for relative axial movement,
with respect to the mandrel, of first ends of said rings nearest
the mandrel when second ends of said rings are radially actuated
from a run in position adjacent said mandrel to a set position in
contact with a surrounding borehole wall.
2. The assembly of claim 1, wherein: said rings comprise a
plurality of axially oriented slots extending from a first axial
end thereof, with said slots in adjacent rings circumferentially
offset so as to avoid extrusion gaps in said set position.
3. The assembly of claim 2, wherein: said rings are rotationally
locked with respect to each other to maintain said circumferential
offset of said slots.
4. The assembly of claim 3, wherein: said rings are rotatably
mounted to said mandrel.
5. The assembly of claim 3, wherein: said rings each comprise at
least one axial keyway such that keyways in said rings are aligned
to accept a retainer that permits relative axial movement of said
rings and precludes relative rotation between said rings.
6. The assembly of claim 5, wherein: said keyways begin at a second
axial end opposite said first axial end.
7. The assembly of claim 3, wherein: said rings are retained to
said mandrel with a retainer ring further comprising a lateral
opening for advancing a force regulating retainer radially against
said rings to regulate the force required to relatively move said
rings in an axial direction.
8. The assembly of claim 7, wherein: said rings each comprise at
least one axial keyway such that keyways in said rings are aligned
to accept a keyway retainer that permits relative axial movement of
said rings and precludes relative rotation between said rings.
9. The assembly of claim 3, wherein: said slots widen as between
said run in and set positions while remaining circumferentially
offset as between adjacent said rings.
10. The assembly of claim 3, wherein: said rings vary in axial
length in said run in position at said first axial end thereof.
11. The assembly of claim 10, wherein: said rings comprise a
longest in axial length innermost said ring and a shortest in
axial. length outermost said ring to define an initial run in
height difference, said height difference being reduced in said set
position.
12. The assembly of claim 10, wherein: said rings comprise a
longest in axial length innermost said ring and a shortest in axial
length outermost said ring to define an initial run in height
difference, said height difference being eliminated in said set
position.
13. The assembly of claim 10, wherein: at least one of said rings
at said first axial end thereof bends over a said first axial end
of an adjacent ring when moved to said set position.
14. The assembly of claim 10, wherein: at least one of said rings
at said first axial end thereof is bent over a said first axial end
of an adjacent ring in said run in position.
15. An extrusion barrier assembly for a mandrel mounted sealing
element in a borehole barrier, comprising: a plurality of nested
discrete rings mounted to the mandrel having first ends of said
rings nearest the mandrel and second ends, said second ends of said
rings are radially actuated from a run in position adjacent said
mandrel to a set position in contact with a surrounding borehole
wall; said rings comprise a plurality of axially oriented slots
extending from a first axial end thereof, with said slots in
adjacent rings circumferentially offset so as to avoid extrusion
gaps in said set position; said slots widen as between said run in
and set positions while remaining circumferentially offset as
between adjacent said rings; said rings vary in axial length in
said run in position at said first axial end thereof.
16. The assembly of claim 15, wherein: said rings comprise a
longest in axial length innermost said ring and a shortest in axial
length outermost said ring to define an initial run in height
difference, said height difference being reduced in said set
position.
17. The assembly of claim 15, wherein: said rings comprise a
longest in axial length innermost said ring and a shortest in axial
length outermost said ring to define an initial run in height
difference, said height difference being eliminated in said set
position.
18. The assembly of claim 15, wherein: at least one of said rings
at said first axial end thereof bends over a said first axial end
of an adjacent ring when moved to said set position.
19. The assembly of claim 15, wherein: at least one of said rings
at said first axial end thereof is bent over a said first axial end
of an adjacent ring in said run in position.
20. An extrusion barrier assembly for a mandrel mounted sealing
element in a borehole barrier, comprising: a plurality of nested
discrete rings mounted to the mandrel having first ends of said
rings nearest the mandrel and second ends, said second ends of said
rings are radially actuated from a run in position adjacent said
mandrel to a set position in contact with a surrounding borehole
wall; said rings comprise a plurality of axially oriented slots
extending from a first axial end thereof, with said slots in
adjacent rings circumferentially offset so as to avoid extrusion
gaps in said set position; said slots widen as between said run in
and set positions while remaining circumferentially offset as
between adjacent said rings; said rings are rotationally locked
with respect to each other to maintain said circumferential offset
of said slots.
21. The assembly of claim 20, wherein: said rings are rotatably
mounted to said mandrel.
22. The assembly of claim 20, wherein: said rings each comprise at
least one axial keyway such that keyways in said rings are aligned
to accept a retainer that permits relative axial movement of said
rings and precludes relative rotation between said rings.
23. The assembly of claim 22, wherein: said keyways begin at a
second axial end opposite said first axial end.
24. The assembly of claim 20, wherein: said rings are retained to
said mandrel with a retainer ring further comprising a lateral
opening for advancing a force regulating retainer radially against
said rings to regulate the force required to relatively move said
rings in an axial direction.
25. The assembly of claim 24, wherein: said rings each comprise at
least one axial keyway such that keyways in said rings are aligned
to accept a keyway retainer that permits relative axial movement of
said rings and precludes relative rotation between said rings.
26. The assembly of claim 1, wherein: said rings are made from
abutting or selectively attached segments.
27. The assembly of claim 15, wherein: said rings are made from
abutting or selectively attached segments.
28. The assembly of claim 20, wherein: said rings are made from
abutting or selectively attached segments.
Description
FIELD OF THE INVENTION
[0001] The field of the invention is sealing systems for
subterranean tools against tubular or open hole or cased hole and
more particularly anti-extrusion barriers for low, medium and
extended reach for a seal element.
BACKGROUND OF THE INVENTION
[0002] In the unconventional drilling and completion industry, oil
and gas deposits are often produced from tight reservoir formations
through the use of fracturing and frack packing methods. To frack a
well involves the high pressure and high velocity introduction of
water and particulate media, typically a sand or proppant, into the
near wellbore to create flow paths or conduits for the trapped
deposits to flow to surface, the sand or proppant holding the
earthen conduits open. Often, wells have multiples of these
production zones. Within each production zone it is often desirable
to have multiple frack zones. For these operations, it is necessary
to provide a seal known as a frack packer, between the outer
surface of a tubular string and the surrounding casing or borehole
wall, below the zone being fractured, to prevent the pumped fluid
and proppant from travelling further down the borehole into other
production zones. Therefore, there is a need for multiple packers
to provide isolation both above and below the multiple frack
zones.
[0003] A packer typically consists of a cylindrical elastomeric
element that is compressed axially, or set, from one end or both by
gages within a backup system that cause the elastomer to expand
radially and form a seal in the annular space. Gages are compressed
axially with various setting mechanisms, including mechanical tools
from surface, hydraulic pistons, atmospheric chambers, etc. Setting
typically requires a fixed end for the gages to push against. These
fixed ends are often permanent features of a mandrel but can
include a dynamic backup system. When compressed, the elastomeric
seal has a tendency to extrude past the gages. Therefore,
anti-extrusion backups have become common in the art. However,
typical elastomeric seals maintain the tendency to extrude through
even the smallest gaps in an anti-extrusion backup system.
[0004] In cased-hole applications, anchoring of compression set
packers is a common feature in the completion architecture.
Anchoring is provided by wedge-shaped slips with teeth that ride up
ramps or cones and bite into the casing before a packer is set.
These systems are not part of the backup system nor are they
designed to provide anti-extrusion. Often they are used in the
setting of the packer to center the assembly which lowers the
amount of axial force needed to fully set the elastomer seal. Once
set, anchoring systems are also useful for the life of the packer
to provide a uniform extrusion gap, maintain location and help
support the weight of a bottom-hole assembly in the case of coiled
tubing frack jobs. Anchors also prevent tube movement in jointed
strings resulting from the cooling of the string by the frack
fluid. Movement of the packers can cause them to leak and lose
seal.
[0005] In open-hole frack pack applications it is rarer for the
packer to have anchoring mechanisms, as the anchor teeth create
point load locations that can overstress the formation, causing
localized flow paths around the packer through the near well-bore.
However, without anchors, movement from the base pipe tubing can
further energize the elastomeric seal. Energizing the seal from
tube movement tends to overstress the near wellbore as well,
leading to additional overstressing of the wellbore, allowing
communication around the packer, loss of production, and potential
loss of well control to surface. However, the art of anchoring has
been reintroduced in new reservoirs in deep-water open-hole
fracking operations. The current state of the art in open-hole
frack pack operations requires a choice between losing sealing due
to anchor contact induced fractures, packer movement, or
over-energizing of the elastomeric element.
[0006] Extrusion barriers involving tapers to urge their movement
to block an extrusion path for a sealing element have been in use
for a long time as evidenced by U.S. Pat. No. 4,204,690. Some
designs have employed tapered surfaces to urge the anti-extrusion
ring into position by wedging them outwardly as in U.S. Pat. No.
6,598,672 or in some cases inwardly as in U.S. Pat. No. 8,701,787.
Other designs simply wrap thin metal rings at the extremities of
the sealing element that are designed to contact the surrounding
tubular to create the anti-extrusion barrier. Some examples of
these designs are U.S. Pat. No. 8,479,809; U.S. Pat. No. 7,708,080;
US 2012/0018143 and US 2013/0147120. Of more general interest in
the area of extrusion barriers are U.S. Pat. No. 9,140,094 and WO
2013/128222.
[0007] In some applications the gap across which the seal is
expected to function is quite large placing such applications
beyond the limits of the design in U.S. Pat. No. 6,598,672.
[0008] The present invention addresses operational issues in the
past with a multi-layer ring assembly of nested rings with
circumferentially offset slots where the ring heights decline from
the innermost to the outermost rings in the assembly. The rings are
rotationally locked to each other to maintain the slot
circumferential offset. The nested ring assembly is mounted for
axial relative articulation during the set so that the number of
sharp edges exposed to the sealing element is reduced if not
eliminated. The free ends of rings inside the outermost ring can be
bent by the sealing element during the setting in a way to protect
the sealing element from sharp ends as the ends of the rings are
protected by an adjacent ring and the innermost ring is bent toward
the surrounding tubular to shield sharp ends of the rings further
out from contact with an end of the sealing element. These and
other aspects of the present invention will be more readily
understood from a review of the description of the preferred
embodiments while recognizing that the full scope of the invention
is to be determined by the appended claims.
SUMMARY OF THE INVENTION
[0009] A backup or extrusion barrier ring assembly has multiple
rows of rings in segments that have circumferentially offset slots.
The rings are rotationally locked to each other to maintain the
circumferential offset of the slots that allow the rings to be more
flexible in the setting process. The rings as a unit can be mounted
to relatively rotate on a supporting mandrel. The rings are mounted
to allow them to move axially during setting either in tandem or
axially relatively to each other. The axial run in heights of rings
decline from innermost to outermost so that when set the heights
approach each other to minimize or eliminate sharp ends against the
seal. Alternatively, the height difference can be such as to allow
ends to bend over an adjacent end further out radially so that free
ends bend toward the surrounding tubular and avoid the seal.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a section view showing a stack of three rings with
different axial lengths;
[0011] FIG. 2 is a top view of a segment that makes up a ring in
FIG. 1 showing a slot that allows axial movement and rotational
locking to at least the other ring segments in the assembly;
[0012] FIG. 3 is the set position of FIG. 1;
[0013] FIG. 4 is a rolled flat top view of a ring segment showing
slots at one end and wider slots at an opposite end for segment
mounting;
[0014] FIG. 5 is a section view of rings with different lengths
where at least one ring has an end bend when running in;
[0015] FIG. 6 is a section view near the ends of stacked ring
segments showing reduced height from innermost to outermost
rings;
[0016] FIG. 7 shows the ends of FIG. 6 in the set position against
a surrounding tubular;
[0017] FIG. 8 is the set position of the rings shown in FIG. 5;
[0018] FIG. 9 is a section view of set rings that were the same
height at run in;
[0019] FIG. 10 is a section view when running in of rings of
differing lengths;
[0020] FIG. 11 is the view of FIG. 10 in the set position with the
ends extending substantially the same axial height;
[0021] FIG. 12 is an end view of a portion of radially stacked
rings with their gaps at the smallest during running in;
[0022] FIG. 13 is the view of FIG. 12 with the offset gaps between
layers enlarged in the set position with extrusion paths still
prevented.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0023] FIG. 1 shows a part of a borehole packer that is mounted on
a mandrel 10 and further illustrates the run in position of the
sealing element 12 at one end. Those skilled in the art will
recognize that the opposite end of the sealing element 12 has a
mirror image layout of the parts that will now be described. Rings
14, 16 and 18 are nested to each other and supported by mandrel 10.
Each of rings 14, 16 and 18 are preferably in segments with a
segment shown rolled flat in FIG. 4. Narrow slots 20 start from end
22 and wider keyways 24 start from opposite end 26 for ease of
assembly. Alternatively, keyways 24 can be elongated openings that
come short of end 26. Referring back to FIG. 1 ring 28 is supported
from mandrel 10 either fixedly or with a bushing or bearing that
permits ring 28 to rotate relatively to mandrel 10. Mounting ring
30 is threaded to ring 28 and features threaded openings 32 that
accept a threaded rod or stud that can go through the keyways 24 of
rings 14, 16 and 18 to prevent relative rotation among rings 14, 16
and 18. Although each of the rings 14, 16 and 18 are preferably
made of abutting segments one of which is shown in FIG. 4, those
skilled in the art will appreciate that rotationally locking one of
several segments that make up a ring locks the entire ring against
rotation relative to other rings through which the stud 34 extends.
The abutting segments can be attached at run in and can release
from each other in the set position. The need to avoid relative
rotation among rings 14, 16 and 18 is best understood from FIGS. 12
and 13. In FIG. 12, gaps 20 are offset among rings 14, 16 and 18 in
the run in position with the gaps 20 having their narrowest
circumferential dimension. That circumferential dimension grows as
shown in FIG. 13 when the set position is obtained. However,
because there has been no relative rotation among rings 14, 16 and
18 during the set the now broader gaps 20 are still covered as
between adjacent rings 14, 16 and 18 so there are no extrusion
gaps. While all the rings 14, 16 and 18 can rotate relatively to
the mandrel 10 to preserve the movements of FIG. 12 to FIG. 13, the
individual rings should not rotate with respect to each other to
avoid creating extrusion paths in the set position of the sealing
element 12. Allowing relative rotation of the rings 14, 16 and 18
relative to mandrel 10 can also ensure better contact with the
surrounding tubular whose wall can have surface irregularities that
would otherwise snag the rings 14, 16 and 18 as they are pushed out
to the surrounding tubular during the setting process.
[0024] Returning to FIGS. 1 and 2 the keyways 24 permit axial
movement of either all the rings 14, 16 and 18 together or relative
movement in the axial direction as between or among rings 14, 16
and 18. Although three rings 14, 16 and 18 are discussed, those
skilled in the art will appreciate that other quantities of such
nested rings can be used. Some of the openings 32 can accommodate a
stud 34 that instead of extending through aligned keyways 24 of
rings 14, 16 and 18 can actually bear on the outermost ring 14 at a
circumferentially offset location from the location of keyways 24
so that the rings 14, 16 and 18 are in effect pushed together to
control the friction force between or among them and with that
regulate their tendency to move relatively to each other in the
axial direction during the setting process.
[0025] As shown in FIGS. 1 and 6 the axially longest ring 18 is the
innermost ring and the next two adjacent rings 16 and 14 going in a
radially outward direction are axially shorter. If the axial length
of the rings in the run in position was the same, their end profile
in the set position would look like FIG. 9 where sharp edges 36, 38
and 40 would present themselves facing the element 12 and dig into
it potentially causing pieces to be cut off at opposed ends of the
element 12. Using differing heights such as illustrated in FIGS. 1
and 6 when the set position is attained can reduce the number of
sharp edges acting on the sealing element 12 to a single edge such
as 40 in FIG. 7 on ring 18 while similar edges on rings 16 and 14
are protected from sharp edges contacting the sealing element 12
and instead present blunt ends to the end of the sealing element
12. Taking the use of height differences among rings in the run in
position one step further, FIGS. 10 and 11 show that with the right
height differences among the rings 14, 16 and 18 for run in, their
relative heights can be close to the same in the set position as
shown in FIG. 11 so that what is in essence a blunt surface 46 is
presented against the sealing element 12. The innermost ring 18
could still potentially form an edge 48 against the sealing element
12 in the set position but that edge can be rounded off in
manufacturing to minimize the impact on the sealing element 12 even
in the FIG. 11 configuration with the blunt edge 46.
[0026] As shown in FIG. 3 with the right axial height differences
and with an initial parallel end configuration of the rings 14, 16
and 18, the setting can result in the outermost ring 14 sitting
flush against the surrounding tubular 50 while end 52 bends over
the end of outermost ring 14 and end 54 of ring 18 bends over the
bend 52 of ring 16. In this way the ring ends 52 and 54 are
oriented toward the tubular 50 instead of into the sealing element
12. FIGS. 5 and 8 are slightly different. In FIG. 5 the end 60 of
innermost ring 18 is manufactured with its end already bent so that
in the set position that bent end 60 orients to the surrounding
tubular 50 and bends end 62 toward the tubular 50 as shown in FIG.
8. Either the innermost ring 18 alone is bent at its end initially
or more than one ring can have an initial end bend so that all but
the outermost ring 14 are bent initially at a free end that
contacts the surrounding tubular 50.
[0027] Those skilled in the art will appreciate that a backup ring
assembly features multiple rings with circumferentially spaced
slots to avoid extrusion paths also has a rotational locking
feature to maintain relative orientations that preclude extrusion
gaps from forming in the set position. The rings further have a
capability of rotating in tandem with respect to the mandrel and of
travelling axially relative to each other while still retained to
the mandrel. The rings have different axial heights to allow the
reduction or elimination of sharp ends facing the sealing element
in the set position. The set position brings the ends of the rings
closer to an alignment of their ends so that a blunt face is
opposite the sealing element. The run in height differences also
allow ends of inner rings to bend over ends of adjacent rings so
that the sealing element sees a bent end of the innermost ring
which is blunt. The ends of some of the rings other than the
outermost can be bent for the run in position to encourage better
end contact with the surrounding tubular as well as avoiding sharp
ring ends from cutting into the sealing element. The ability of the
rings to slide axially relatively to each other can be controlled
with studs that force the rings toward a supporting mandrel. A
bushing or bearing allows the assembly of all the rings to rotate
in tandem relative to the mandrel to assure a better peripheral
connection to the surrounding tubular to reduce or eliminate
extrusion paths along the surrounding tubular wall.
[0028] The above description is illustrative of the preferred
embodiment and many modifications may be made by those skilled in
the art without departing from the invention whose scope is to be
determined from the literal and equivalent scope of the claims
below:
* * * * *