U.S. patent application number 12/058007 was filed with the patent office on 2009-10-01 for swell packer.
This patent application is currently assigned to SCHLUMBERGER TECHNOLOGY CORPORATION. Invention is credited to Frederick Lemme, SR., Manuel Marya, Nitin Y. Vaidya.
Application Number | 20090242189 12/058007 |
Document ID | / |
Family ID | 40600771 |
Filed Date | 2009-10-01 |
United States Patent
Application |
20090242189 |
Kind Code |
A1 |
Vaidya; Nitin Y. ; et
al. |
October 1, 2009 |
SWELL PACKER
Abstract
A swell packer includes a base tubular; a seal member encircling
the base tubular, the seal member swelling radially to a seal
equilibrium swell upon contact with a particular fluid; and a disc
positioned about the base tubular substantially abutting an end of
the seal member but not physically connected to the seal member in
a manner that limits the equilibrium swell of the seal member, the
disc swelling radially to a first equilibrium swell upon contact
with a particular fluid.
Inventors: |
Vaidya; Nitin Y.; (Missouri
City, TX) ; Marya; Manuel; (Stafford, TX) ;
Lemme, SR.; Frederick; (Katy, TX) |
Correspondence
Address: |
SCHLUMBERGER RESERVOIR COMPLETIONS
14910 AIRLINE ROAD
ROSHARON
TX
77583
US
|
Assignee: |
SCHLUMBERGER TECHNOLOGY
CORPORATION
Sugar Land
TX
|
Family ID: |
40600771 |
Appl. No.: |
12/058007 |
Filed: |
March 28, 2008 |
Current U.S.
Class: |
166/134 ;
166/179 |
Current CPC
Class: |
E21B 33/1277 20130101;
E21B 33/1216 20130101; E21B 33/1208 20130101 |
Class at
Publication: |
166/134 ;
166/179 |
International
Class: |
E21B 33/12 20060101
E21B033/12 |
Claims
1. An apparatus for supporting a radially swellable seal member of
a swell packer, the apparatus comprising a radially swellable disc
positioned at an end of the seal member.
2. The apparatus of claim 1, wherein the disc has a modulus of
elasticity greater than that of the seal member.
3. The apparatus of claim 2, wherein the disc includes an internal
stiffening element.
4. The apparatus of claim 2, further including a stiffening element
operationally connected to the disc opposite from the seal
member.
5. The apparatus of claim 2, wherein the disc is not physically
connected to the seal member.
6. The apparatus of claim 3, further including a stiffening element
operationally connected to the disc opposite from the seal
member.
7. The apparatus of claim 6, wherein the disc is not physically
connected to the seal member.
8. The apparatus of claim 1, wherein the disc is radially less
swellable than the seal member.
9. The apparatus of claim 1, further including a stiffening
element.
10. The apparatus of claim 9, wherein the stiffening element is
operationally connected to the exterior of the disc opposite from
the seal member
11. The apparatus of claim 1, further including a stiffening
element operationally connected to the exterior of the disc
opposite from the seal member.
12. The apparatus of claim 11, wherein the stiffening element is an
end-ring.
13. The apparatus of claim 11, wherein the disc is not physically
connected to the seal member.
14. An anti-extrusion device positionable at an end of a packer
seal member that radially swells when contacted by a particular
fluid to form an annular seal in a wellbore, the device comprising:
a first disc for positioning adjacent the seal member, the first
disc expandable to a first equilibrium swell upon contact with the
particular fluid; and a second disc positionable adjacent the first
disc and opposite the seal member, the second disc expandable to a
second equilibrium swell upon contact with the particular fluid,
wherein the second equilibrium swell is less than the first
equilibrium swell.
15. The device of claim 14, further including a stiffening
element.
16. A swell packer comprising: a base tubular; a seal member
encircling the base tubular, the seal member swelling radially to a
seal equilibrium swell upon contact with a particular fluid; and a
disc positioned about the base tubular substantially abutting an
end of the seal member but not physically connected to the seal
member in a manner that limits the equilibrium swell of the seal
member, the disc swelling radially to a first equilibrium swell
upon contact with a particular fluid.
17. The swell packer of claim 16, further including a stiffening
element operationally connected to the disc opposite the seal
member.
18. The swell packer of claim 16, wherein the first swell
equilibrium is less than the seal swell equilibrium, and the disc
is more rigid at the first swell equilibrium than the seal member
is at the seal swell equilibrium.
19. The swell packer of claim 18, further including a second disc
positioned about the base tubular adjacent the disc opposite the
seal member, the second disc swelling radially to a second
equilibrium swell upon contact with a particular fluid, wherein the
second equilibrium swell is less than the first equilibrium
swell.
20. The swell packer of claim 19, further including an external
stiffening element positioned between the disc and the second disc.
Description
TECHNICAL FIELD
[0001] The present invention relates in general to wellbore packers
and more specifically to packers that swell when exposed to a
particular fluid or condition in the wellbore.
BACKGROUND
[0002] It is often desired to utilize packers to form an annular
seal in wellbores. Open-hole packers provide an annular seal
between the earthen sidewall of the wellbore and a tubular. Cased
hole packers provide an annular seal between an outer tubular and
an internal tubular.
[0003] Common types of packers include inflatable packers,
mechanical expandable packers, and swell packers. Inflatable
packers typically carry a bladder that may be pressurized to expand
outwardly to form the annular seal. Mechanical expandable packers
have a flexible material expanding against the outer casing or wall
of the formation when compressed in the axial direction of the
well. Swell packers comprise a sealing material that increases in
volume and expands radially outward when a particular fluid
contacts the sealing material in the well. For example the sealing
material may swell in response to exposure to a hydrocarbon fluid
or to exposure to water in the well. The sealing material may be
constructed of a rubber compound or other suitable swellable
material.
[0004] One drawback of swell packers is that the sealing material
may extrude, due to differential pressure for example.
Anti-extrusion, or anchoring, devices in the form of end-rings have
been utilized as a means of mediating this drawback. The end-rings
typically include petals or the like that expand outwardly by the
force of the swelling seal material. While the end-rings may
provide a benefit in some installations, cased hole installations
it is believed that they may deter sealing in other installations.
For example, in open hole installations the ovality or eccentricity
of the wellbore varies along its length. The non-uniformity in the
cross-sectional shape and dimensions of the wellbore, means that
the annular gap to be sealed may vary substantially from point to
point. It also means that the dimension of the annular gap is often
unknown.
SUMMARY
[0005] An example of an apparatus for supporting a radially
swellable seal member of a swell packer includes a radially
swellable disc positioned at an end of the seal member. The disc
may have a modulus of elasticity greater than that of the seal
member. The disc may have an internal stiffening element. A
stiffening element may be operationally connected to the disc
opposite from the seal member. It may be that the disc is not
physically connected to the seal member, in a manner such that the
connection would limit the ability of the disc to expand to its
equilibrium swell.
[0006] An example of an anti-extrusion device positionable at an
end of a packer seal member that radially swells when contacted by
a particular fluid to form an annular seal in a wellbore includes a
first disc for positioning adjacent the seal member, the first disc
expandable to a first equilibrium swell upon contact with the
particular fluid; and a second disc positionable adjacent the first
disc and opposite the seal member, the second disc expandable to a
second equilibrium swell upon contact with the particular fluid,
wherein the second equilibrium swell is less than the first
equilibrium swell.
[0007] An example of a swell packer includes a base tubular; a seal
member encircling the base tubular, the seal member swelling
radially to a seal equilibrium swell upon contact with a particular
fluid; and a disc positioned about the base tubular substantially
abutting an end of the seal member but not physically connected to
the seal member in a manner that limits the equilibrium swell of
the seal member, the disc swelling radially to a first equilibrium
swell upon contact with a particular fluid.
[0008] The foregoing has outlined some of the features and
technical advantages of the present invention, in order that the
detailed description of the invention that follows may be better
understood. Additional features and advantages of the invention
will be described hereinafter which form the subject of the claims
of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The foregoing and other features and aspects of the present
invention will be best understood with reference to the following
detailed description of a specific embodiment of the invention,
when read in conjunction with the accompanying drawings,
wherein:
[0010] FIG. 1 is a conceptual illustration of an example of a swell
packer and anti-extrusion device of the present invention;
[0011] FIG. 2 is a conceptual illustration of an example of swell
packer of the present invention expanded and concentrically aligned
in a wellbore;
[0012] FIG. 3 is a conceptual illustration of an example of a swell
packer of the present invention expanded and eccentrically
positioned in a wellbore; and
[0013] FIG. 4 is an end view an example of a swell packer of the
present invention activated in an open-hole wellbore.
DETAILED DESCRIPTION
[0014] Refer now to the drawings wherein depicted elements are not
necessarily shown to scale and wherein like or similar elements are
designated by the same reference numeral through the several
views.
[0015] FIG. 1 is a conceptual illustration of an example of a swell
packer of the present invention, generally denoted by the numeral
10. Swell packer 10 includes a base tubular 12, swellable seal
member 14, and an anti-extrusion device generally denoted by the
numeral 16. Swell packer 10 has a longitudinal axis 18 shown by the
dashed line.
[0016] Swell packer 10 is shown disposed in a wellbore 20 having a
sidewall 22. Open-hole refers to sidewall 22 being formed by the
surrounding earthen formation. Cased hole refers to the sidewall 22
being formed by a tubular. The tubular may be a casing, liner,
tubing, production string, screen or in general any other tubular
in which packer 10 is positioned.
[0017] Seal member 14 has opposing ends 24, 26 and encircles base
tubular 12. Seal member 14 may be may be connected to base tubular
12 in various manners. Seal member 14 is formed of a material that
swells when exposed to a particular fluid or condition in wellbore
20. For example, seal member 14 could swell in volume in response
to a hydrocarbon, water, or other activating fluid or chemical.
Seal material 14 may be of a rubber compound or other material.
Seal member 14 may be constructed as a unitary member or in layers.
To form an annular seal, seal member 14 must expand radially the
distance of annular gap 34, which is the distance between the outer
surface of seal member 14 and sidewall 22.
[0018] Anti-extrusion device 16 may be positioned about base
tubular 12 at one or both of ends 24, 26 of seal member 14.
Anti-extrusion device 16 includes one or more discs 28. Discs 28
are formed of a swellable material. Anti-extrusion device 16 is now
described with reference to the left end of seal member 14,
referred to herein as end 24. Anti-extrusion device 16 includes
multiple discs identified as 28a, 28b, 28c, 28d, etc. from the end
24 of seal member 14 outward. Although, four discs are illustrated
in the Figures, device 16 may include more or fewer discs 28.
[0019] Adjacent discs 28 are in functional connection with one
another so as to cooperatively provide support to seal member 14
against extrusion without limiting the radial expansion of seal
member 14. Adjacent discs 28 may physically abut one another or may
be spaced apart by one or more elements. Anti-extrusion device 16
may include various non-swellable elements such as reinforcement
members, components, and the like.
[0020] Each disc 28 may be constructed of a material having a
different swellability and modulus of elasticity than its adjacent
disc. "Swellability" is utilized herein to denote the ability to
increase in volume and extend radially outward from base tubular
12. In the illustrated example, discs 28 decrease in swellability
as they move outward from an end of seal member 14. Thus, disc 28a
has a greater swellability than disc 28b which has a greater
swellability than disc 28c, and so forth. As the swellability
decreases, the modulus of elasticity, or Young's Modulus,
increases. Thus, the discs become more rigid or stiffer as they
move outward from the end of seal member 14.
[0021] Discs 28 may be constructed of materials such as, but not
limited to, swellable rubber compounds and non-elastomeric
plastics. Examples include Ryton/elastomer blender, Xtel XE3200
polyphenylene sulfide alloy with 100 percent elongation at break
and 450 psi tensile strength, PVDF/Viton blends, and thermoplastic
elastomers.
[0022] Refer now to FIG. 2, wherein swell packer 10 is illustrated
in the expanded position. In this example, swell packer 10 is
concentrically aligned within wellbore 20. The longitudinal axis 36
(FIG. 3) of this portion of wellbore 20 corresponds to longitudinal
axis 18 of packer 10 and is therefore not visible in this view.
FIG. 2 illustrates an installation that is common to cased
holes.
[0023] Upon contact with a selected fluid, seal member 14 and discs
28 of anti-extrusion device 16 swell and expand radially outward
from base tubular 12 to their respective equilibrium swells or
until contained by sidewall 22. Discs 28b, 28c, and 28d have each
reached their respective equilibrium swell in FIG. 2. Disc 28a may
have reached its equilibrium swell or it contacted sidewall 22
prior to reaching equilibrium.
[0024] Disc 28a, being the disc adjacent to the end of seal member
14 has a swellability similar to the swellability of seal member
14. In some examples, disc 28a will have a swellability less that
that of seal member 14 and thus have a higher modulus than seal
member 14. Disc 28a is not physically connected to seal member 14
in a manner that will limit seal member 14 from obtaining its
equilibrium swell. The rigidity and the swellability of disc 28a,
aides in preventing or limiting the extrusion of seal member 14,
while not interfering with the ability of seal member 14 to contact
and form a seal against sidewall 22. Each subsequent disc (28b,
28c, etc.) out from the end of seal member 14 decreases in
swellability and increases in stiffness (higher modulus of
elasticity), thus providing additional support against extrusion of
seal member 14.
[0025] Anti-extrusion device 16 may include one or more elements to
provide additional rigidity. For example, device 16 may include an
external or first stiffening element 30, such as an expandable
end-ring that is spaced apart from seal member 14 and abutting a
disc 28. Anti-extrusion device 16 may include disc 28a abutting an
end of seal member 14 and a first stiffening element 30, such as an
end-ring, that is operationally connected to the end of disc 28a
opposite of seal member 14. Stiffening element 30 may provide the
support to disc 28a necessary to prevent or limit the extrusion of
seal member 14 without materially limiting the ability of seal
member 14 to expand radially. In one example, disc 28a may have a
swellability and modulus of elasticity that is the same or
substantially the same as seal member 14.
[0026] Device 16 may include internal or second stiffening elements
32. Examples of second stiffening elements 32 include without
limitation, Kevlar, glass, and carbon incorporated into discs 28
for example as chopped fibers, fiber mats, and long fibers.
[0027] Refer now to FIGS. 3 and 4 illustrating swell packer 10
activated in an open-hole wellbore 20. Swell packer 10 is shown
eccentrically positioned in wellbore 20, indicated by the
misalignment of longitudinal axis 18 of base tubular 12 and
longitudinal axis 36 of wellbore 20 (FIG. 3).
[0028] As is common in open-hole wellbores, the cross-sectional
dimensions of wellbore 20 is non-uniform along its length. The
unpredictability of the wellbore dimensions at the desired seal
location creates difficulties in obtaining an effective seal. One
difficulty is presented by the inability to determine the annular
gap at the desired point of sealing. The inability to accurately
identify the annular gap at the point of the seal may result in the
mis-sizing of the traditional anti-extrusion devices, in particular
the end-ring type devices. The mis-sizing of the traditional
anti-extrusion devices may not only fail to operate as desired but
may in fact prevent the seal member from sealing against the
sidewall. For example, if an tradition end-ring is selected for an
annular gap less than the actual annular gap to be sealed, the
traditional end-ring may prevent the sealing element from expanding
sufficiently to achieve the desired seal.
[0029] Anti-extrusion device 16 does not grip seal member 14 in a
manner that will limit the radial expansion of seal member 14. As
illustrated in FIG. 4, seal member 14 is free to expand radially
from base tubular 12 to seal against the contour of sidewall 22.
Disc 28a swells radially to an extent to aide against extrusion of
seal member 14 without limiting the radial expansion of seal member
14. As can be seen in the end-view of FIG. 4, disc 28a may expands
to sidewall 22 or may reach its equilibrium swell before reaching
sidewall 22 without limiting the radial expansion of seal member
14.
[0030] From the foregoing detailed description of specific
embodiments of the invention, it should be apparent that swell
packers and anti-extrusion devices for swell packers that are novel
have been disclosed. Although specific embodiments of the invention
have been disclosed herein in some detail, this has been done
solely for the purposes of describing various features and aspects
of the invention, and is not intended to be limiting with respect
to the scope of the invention. It is contemplated that various
substitutions, alterations, and/or modifications, including but not
limited to those implementation variations which may have been
suggested herein, may be made to the disclosed embodiments without
departing from the spirit and scope of the invention as defined by
the appended claims which follow.
* * * * *