U.S. patent application number 15/486523 was filed with the patent office on 2018-10-18 for packer backup ring with closed extrusion gaps.
This patent application is currently assigned to BAKER HUGHES INCORPORATED. The applicant listed for this patent is BAKER HUGHES INCORPORATED. Invention is credited to Andrew J. Cayson, Guijun Deng, Alexander M. Kendall.
Application Number | 20180298716 15/486523 |
Document ID | / |
Family ID | 63792050 |
Filed Date | 2018-10-18 |
United States Patent
Application |
20180298716 |
Kind Code |
A1 |
Cayson; Andrew J. ; et
al. |
October 18, 2018 |
Packer Backup Ring with Closed Extrusion Gaps
Abstract
Alternating l-shaped side slots are cut into opposed sides of a
backup ring and are circumferentially offset and alternately extend
from the inside and outside dimension. An oval shaped opening
connects adjacent circumferentially offset slots so that on ring
expansion the inside and outside diameters increase as the openings
are sheared at one end to place a barrier in opened side slot to
prevent extrusion of the adjacent sealing element.
Inventors: |
Cayson; Andrew J.; (Cypress,
TX) ; Kendall; Alexander M.; (Houston, TX) ;
Deng; Guijun; (The Woodlands, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BAKER HUGHES INCORPORATED |
Houston |
TX |
US |
|
|
Assignee: |
BAKER HUGHES INCORPORATED
Houston
TX
|
Family ID: |
63792050 |
Appl. No.: |
15/486523 |
Filed: |
April 13, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 33/1216 20130101;
E21B 33/1293 20130101; E21B 33/128 20130101 |
International
Class: |
E21B 33/12 20060101
E21B033/12; E21B 33/129 20060101 E21B033/129; E21B 33/128 20060101
E21B033/128 |
Claims
1. A backup ring assembly for extrusion protection for a sealing
element of a borehole barrier, comprising: a continuous ring having
an inside and an outside surface and an axis; circumferentially
spaced slots having a first end extending into said ring from said
inside and outside surfaces and having a second end ending short of
an opposing said inside or outside surface such that said ring can
remain continuous as said inside and outside surfaces grow
dimensionally by virtue of said slots opening gaps, said gaps
substantially closed at one end by a portion of said ring for
contacting the sealing element to minimize extrusion through said
gaps.
2. The assembly of claim 1, wherein: said slots on said inside and
outside surfaces each formed by circumferentially spaced axially
extending segments connected by a transverse opening in said
ring.
3. The assembly of claim 2, wherein: said transverse openings at
each said slot comprise opposed ends at said inside and said
outside surfaces.
4. The assembly of claim 3, wherein: said openings are positioned
midway on said inside and outside surfaces.
5. The assembly of claim 3, wherein: said ends of said openings
that join said respective segments shearing or separating to enable
opening of said gaps.
6. The assembly of claim 3, wherein: said ends of said openings
that do not join said respective segments remaining intact when
said inside or outside surfaces increase in dimension.
7. The assembly of claim 2, wherein: said slots at an end away from
said inside and outside surfaces comprising a stress reduction
bend.
8. The assembly of claim 1, wherein: said ring having a triangular
cross-section such that said outside surface is wider than said
inside surface.
9. The assembly of claim 5, wherein: said transverse openings
comprise an oblong shape so that said shearing or separating
defines relatively moving opposed surfaces as said slots open to
form said gaps.
10. The assembly of claim 9, wherein: said surfaces are disposed at
an internal end of said gaps that open from said slots.
11. The assembly of claim 9, wherein: said relative movement of
said opposed surfaces substantially blocks an internal opening in
said gaps that open from said slots.
12. The assembly of claim 9, wherein: said relative movement of
said opposed surfaces is circumferential about said axis of said
ring.
13. The assembly of claim 9, wherein: said oblong opening shears at
opposed ends to define said opposed surfaces.
14. The assembly of claim 1, wherein: said slots define a dovetail
shape of a male portion retained by a female portion with space in
between said male and female portion to allow relative
circumferential movement for enlarging said inside and outside
surfaces as said gaps are created.
15. The assembly of claim 14, wherein: said male portion extending
into said gaps to substantially block an extrusion path for the
sealing element.
16. The assembly of claim 15, wherein: said gaps extending to
varying sizes to allow said outside surface to conform to
irregularities in the surrounding borehole.
17. The assembly of claim 1, wherein: said gaps extending to
varying sizes to allow said outside surface to conform to
irregularities in the surrounding borehole.
18. The assembly of claim 3, wherein: said openings are positioned
offset from midway on said inside and outside surfaces.
19. The assembly of claim 1, wherein: said ring having a
multilateral cross-section.
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. There
is a need for an extended reach design that can withstand the
pressure differentials. The present invention addresses this need
with slots that extend toward each other from opposing faces and
are circumferentially offset. The slots are connected at voids that
extend from the original inside to the original outside diameter.
Expansion of the ring allows alternating voids to separate or shear
at the outside and the inside diameter so that as gaps form in the
ring a segment of the ring presents itself in each of the opened
gaps as both the inside and the outside diameters increase. In an
alternative solution to extrusion through a backup ring a backup
ring with a common base has multiple rows of extending segments
with gaps in one row offset circumferentially with gaps in an
adjacent row. The common base lends structural integrity to the
backup ring design and reduces the risk that relative rotation can
occur between adjacent rows that would tend to align the offset
gaps from one row to the next. These and other aspects of the
present invention will be more readily apparent, to those skilled
in the art from a review of the description of the preferred
embodiment and the associated drawings while understanding that the
full scope of the invention is to be determined from the appended
claims.
SUMMARY OF THE INVENTION
[0008] Alternating l-shaped side slots are cut into opposed sides
of a backup ring and are circumferentially offset and alternately
extend from the inside and outside dimension. An oval shaped
opening connects adjacent circumferentially offset slots so that on
ring expansion the inside and outside diameters increase as the
openings are separated or sheared at one end to place a barrier in
opened side slot to prevent extrusion of the adjacent sealing
element.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a front view of a backup ring in a run in
position;
[0010] FIG. 2 is a side view of the ring of FIG. 1;
[0011] FIG. 3 is the view along line 3-3 of FIG. 2;
[0012] FIG. 4 is the view along line 4-4 of FIG. 2;
[0013] FIG. 5 is an outside diameter view of the backup ring in an
expanded position;
[0014] FIG. 6 is an inside diameter view of the backup ring in the
expanded position;
[0015] FIG. 7 is a side view of the backup ring in the expanded
position;
[0016] FIG. 8 is a section view of a backup ring showing the layers
of ring segments extending from a common base;
[0017] FIG. 9 is an isometric view of the backup ring of FIG. 8
[0018] FIG. 10 is a section view of the backup ring of FIG. 8 in a
run in position;
[0019] FIG. 11 is the view of FIG. 10 in the set position;
[0020] FIG. 12 is an expanded view of the view on FIG. 1;
[0021] FIG. 13 is an expanded view of the view in FIG. 2;
[0022] FIG. 14 is a section view of a packer in the run in position
using the backup ring;
[0023] FIG. 15 is a set position of the view in FIG. 14;
[0024] FIG. 16 is an exterior view of the view in FIG. 15;
[0025] FIG. 17 is an alternative to the dog leg slot design in FIG.
1 using a dovetail configured to allow relative circumferential
movement for an increase in diameter;
[0026] FIG. 18 is a close up view of FIG. 17 to show the dovetail
has initial gaps to allow for the relative circumferential movement
at the inside and the outside diameters;
[0027] FIG. 19 is the view of FIG. 17 after the diameters are
increased;
[0028] FIG. 20 is an enlarged view of FIG. 19 showing the dovetail
acting as a relative circumferential movement travel stop and gap
barrier at the same time.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0029] FIGS. 10 and 11 illustrate the juxtaposition of a sealing
element 10 next to a backup ring 12. FIG. 2 shows an end view of a
continuous single ring 14 that can be disposed next to a sealing
element 10. Ring 14 has an inside diameter 16 and an outside
diameter 18. There are alternating l-shaped slots 20 and 22 that
start at the outside diameter 18 and at the inside diameter 16.
FIG. 2 shows a tapered or sloping side 24 and slots 20 and 22 that
alternate as to the location of the long dimension of the l-shaped
slot. Sloping side 26 is not seen in FIG. 2 but is shown as FIG. 3
as well as the cylindrically shaped inside surface 28 that defines
the inside diameter 16. FIGS. 1 and 4 both show an outside view
where it is seen that slot 22 is a segment that goes to outside
diameter 18 has a continuation slot segment 22' that is
circumferentially offset a few degrees. Slots 22 and 22' are at
opposed ends of an oblong bore 22'' that may have internal
supports. Bore or opening 22'' is seen at an opposite end at inside
diameter 16 in FIG. 3. When ring 14 is increased in both inside
diameter 16 and outside diameter 18 the bore undergoes hoop stress
and comes apart at outside diameter 18 when outside diameter 18
grows as shown in FIG. 5. The connecting bore 22'' has separated or
sheared leaving surface 30 as a closing wall to a gap 32 that opens
and into which the sealing element 34 can move. However, since the
gap 32 is closed by surface 30, migration of the sealing element 32
in the direction of arrow 36 is stopped by surface 30. At the same
time should there be a sealing element 38 on an opposite side of
ring 14, the searing apart of bore 22'' at the outside diameter 18
also leaves surface 40 at the end of gap 42 to stop movement of
seal 38 in the direction of arrow 44.
[0030] Bores 20'' are seen as alternating with bores 22'' at the
outside diameter 18 as seen in FIG. 1 and are seen at inside
diameter 16 in FIG. 3 as connecting slots 20 and 20' in the run in
condition. FIG. 6 shows bores 20'' separated or sheared from hoop
stress during radial expansion of inside diameter 16. Surfaces 50
and 52 are presented respectively at the ends of widened slots 54
and 56 from the inside diameter 16 radial expansion. As a result, a
sealing element 58 will be blocked from passing surface 50 in the
direction of arrow 62 or/and a sealing element 60 will be blocked
by surface 52 when moving in the direction of arrow 64 under
differential pressure that would otherwise allowed for extrusion in
gaps closed at the inside diameter by surfaces 50 and 52 as a
result of separating or shearing of bores or openings 20'' at
inside dimension 28. Note that at inside dimension 28 bores 22'' do
not separate or shear as they are supported at that location by the
ring structure unlike bores 20'' that span slots 20 and 20' at
inside dimension 28.
[0031] Note that as shown in FIG. 6 opposed surfaces 50 and 54 may
separate circumferentially to leave a small gap or their ends can
alternatively align or overlap and may also optionally involve a
stop or overlap to limit the relative circumferential movement
between surfaces such as 50 and 54 at inside surface 28 to insure
that any gap such as 54 and 56 are fully closed at maximum
condition for inside diameter 16. This is equally true at outside
diameter 18 shown in FIG. 5 where surfaces 30 and 40
circumferentially separate to an end position where there is
overlap between them, a small gap or alignment between their ends
so that there is no effective gap in the directions of arrows 36
and 44. Alternatively opposed surfaces 30 and 40 can have one or
move travel stops 31 to limit the amount of relative
circumferential movement to an overlapping position as shown in
FIG. 5.
[0032] FIG. 7 shows how surfaces 30 and 50 close off gaps 32 and 54
respectively when in the inside diameter 16 and the outside
diameter 18 are increased. It also shows the short slot segments
that make the l-shape 70 and 72 that are there to reduce stress
concentration at ends of opening gaps such as 32 and 54, for
example.
[0033] FIG. 12 is similar to FIG. 5 and represents the gaps closed
with end walls 30 and 40 after the inside and outside diameters are
enlarged, as previously described. FIG. 13 is the view of FIG. 2
after the inside and outside diameters are enlarged graphically
illustrating the alternating pattern of opened gaps on the inside
diameter and the outside diameter with the extrusion gaps closed
using a single ring that can grow in outside diameter, for example
from 8.3 inches to 9.875 inches while closing extrusion paths.
[0034] FIGS. 17-20 are an alternative design using the concepts of
the design in FIGS. 1-7 but instead of l-shaped slots with a dog
leg that starts out as a bore but then separates or shears to
create relative circumferential movement to produce end walls to
close gaps that enlarge at the inside and the outside diameters,
uses slots that are interacting dovetail shapes that alternatively
start at the inside diameter and the outside diameter and do not go
all the way through. Diameter enlargement at the inside and the
outside diameters is enabled in a relative circumferential
direction until one part of the dovetail closes an initial dovetail
gap. The dovetail limits the ring gaps and acts as an extrusion
barrier by its presence in those enlarging gaps that open
alternatingly from the inside and outside diameters. FIGS. 17 and
18 show the initial gaps 80 between the male 82 and the female 84
components of each dovetail. FIG. 20 shows gap 80 closed during
diameter expansion at the inside and the outside diameters. An
extrusion gap such as 86 opens but the male component 84 is in that
gap to close it up. The same condition happens at the inside
dimension and the outer dimension of the backup ring as previously
described in the context of FIGS. 1-7. Bores 88 do not open on the
outside diameter as between FIGS. 17 and 19 but on the inside
diameter that is not shown for this variation there is relative
circumferential movement until the counterpart dovetail on the
inside diameter closes an initial dovetail gap that defines the end
of relative circumferential movement where gaps open on the inside
dimension. In the sense of alternating gaps that open from the
inside and then the outside diameters the embodiments of FIGS. 1-7
and 17-20 operate the same way. Instead of bores separating or
shearing to enable circumferential growth the slack in dovetails
closed to enable circumferential growth at the inside and the
outside diameters. FIGS. 17-20 are schematic and can illustrate the
view at an outer diameter or an inner diameter. The operating
principle is the same as previously described for FIGS. 1-7 in that
gaps alternatingly open up in a circumferentially offset manner on
the inside and the outside dimensions and the gaps so created are
then closed to seal element extrusion. In the case of FIGS. 1-7 a
wall surface is interposed in the gap due to the alternating gaps
opening up and in FIGS. 17-20 the dovetail itself allows the gaps
to open up until slack in the dovetail is removed at which time the
male portion of the dovetail is interposed in the gap to block it
entirely or at least substantially.
[0035] FIGS. 14-16 show a typical packer in the run in and set
positions using the ring 14 as a backup ring. FIG. 16 graphically
shows how the dog leg slots that open on the outside diameter block
the extrusion of the sealing element as previously described.
Details of the operation of the rings 90, 92 and 94 can be reviewed
in U.S. application Ser. No. 14/989,199 that is fully incorporated
herein as if fully set forth. While that design featured
alternating gaps opening on the inside diameter and the outside
diameter, there was no feature of blocking the opened gaps against
extrusion.
[0036] FIG. 8 illustrates a backup ring design featuring a common
base ring 100 that has multiple segmented rings 102 integrally
extending therefrom, with 2-4 being preferred. The segmented nature
of each ring can be seen in FIG. 9 in the form of offset gaps 104
and 106 in adjacent rings. Preferably there is a circumferential
offset of about 12 degrees between gaps on adjacent rings. Each
ring has multiple gaps that are all offset from gaps on an adjacent
ring on either side. Because the segments that make up each ring
are integrally connected to the base ring 100 there is no relative
rotation among the stacked segmented rings 102 and the rings 102
are still flexible as seen by comparing FIGS. 10 and 11 for the run
in and the set positions. Since the stacked rings 102 are supported
circumferentially along the length of each ring segment from base
100 the assembly of rings also has greater resistance to extrusion
when pushed against the surrounding tubular as shown in FIG. 11.
Ring segments 102 extend to different axial lengths for running in
and have a free end that is offset and axially aligned with an axis
of ring 100. Gaps 104 are as long axially as said segments 102. An
internal groove 108 holds a mandrel seal 110 to prevent extrusion
of sealing element 10 along the mandrel.
[0037] Those skilled in the art will appreciate that alternative
backup ring designs are described that have the objective of
dimensional growth while limiting or eliminating extrusion of a
sealing element on preferably opposed ends of a sealing element. In
FIGS. 1-7 alternating circumferential slots with dog leg connectors
in the form of a bore extend from the inside diameter and the
outside diameter in alternating fashion. On radial expansion the
bores separate or shear on surfaces where the bore is a connector
to slots that extend from opposed ends of an outer or inner
diameter and where the two slots are themselves circumferentially
offset by the width of the oblong bore or void. As a result the
inside and outside diameters grow as the slots part to form gaps
and the offset disposition of slots connected by an oblong bore
allows an end surface to be positioned in each gap that minimizes
or completely prevents seal element extrusion. The dimensional
growth need not be uniform so that the enlarged dimension can
conform to an irregularly shaped borehole wall, for example. The
adjacent and oppositely facing end walls can interact with each
other as a given oblong opening is separated or sheared to expose
such end walls so that there is overlap between such adjacent end
walls with a stop device that limits relative circumferential
movement between them. Alternatively the wall ends can align or
pull away from each other slightly so that there is either no
extrusion gap or a minimal gap for the sealing element.
[0038] The same pattern of slots that open into gaps alternating on
the inside and outside diameters can be used with dovetail cuts
that have slack in them in the run in diameter and where the
relative circumferential movement of each pair of dovetail
components is limited by the slack coming out of each dovetail
connection. The gaps that open are blocked by the extension of the
male of the dovetail pair extending into the opening. The dovetail
pairs start in an alternating pattern on the inside and outside
diameters to present a cohesive ring structure that can expand on
the inside and outside diameters. The dovetail slots on the inside
diameters are circumferentially spaced from the dovetail slots on
the outside diameter and the gaps that form as the diameters
increase are substantially blocked by the male dovetail component
bottoming on the female surrounding component or when the outside
dimension of the backup ring engages a surrounding tubular,
whichever happens first. The structure with alternating dog leg
slots or dovetail slots lets the ring remain whole while lending
the ring flexibility of going out of round so that if the
surrounding tubular has dimensional imperfections, the backup ring
can adapt to the actual shape of the inside wall of the surrounding
tubular. A single ring can be placed between sealing elements and
reduce or eliminate extrusion between the sealing element in either
of opposed directions.
[0039] In a backup ring with multiple stacked rows of segmented
rings the gaps in adjacent rings are offset and all the rings are
preferably integral to a common ring base. The extrusion gaps are
closed off while the integration of the stacked rings with the base
provides for a stronger yet still flexible design that can conform
to the surrounding tubular wall for closing an extrusion gap. The
outer edge of the stacked rings is made long enough so that there
is bending into a more parallel orientation with the surrounding
tubular when the set position of FIG. 11 is reached. A support ring
can backstop the backup ring in the set position on an opposite
side from the sealing element as shown also in FIG. 11.
[0040] 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:
* * * * *