U.S. patent application number 12/013519 was filed with the patent office on 2009-07-16 for multi-layer water swelling packer.
Invention is credited to James R. Korte, Edward T. Wood.
Application Number | 20090178800 12/013519 |
Document ID | / |
Family ID | 40849660 |
Filed Date | 2009-07-16 |
United States Patent
Application |
20090178800 |
Kind Code |
A1 |
Korte; James R. ; et
al. |
July 16, 2009 |
Multi-Layer Water Swelling Packer
Abstract
A packer for downhole use responds to water containing fluids by
swelling from its core. The core is preferably covered with an
outer layer that preferably has a lower rate of diffusion and
swelling than the core that it surrounds. Because of this
arrangement, the packer can be delivered to the desired location
before it is set by swelling of the core. The outer layer can also
be responsive to water containing fluids by dissolving slowly to
allow time to properly position the packer before the core swells
to a sealing relationship with the surrounding tubular or the
wellbore wall.
Inventors: |
Korte; James R.; (Katy,
TX) ; Wood; Edward T.; (Kingwood, TX) |
Correspondence
Address: |
DUANE MORRIS LLP - Houston
3200 SOUTHWEST FREEWAY, SUITE 3150
HOUSTON
TX
77027
US
|
Family ID: |
40849660 |
Appl. No.: |
12/013519 |
Filed: |
January 14, 2008 |
Current U.S.
Class: |
166/187 |
Current CPC
Class: |
E21B 33/1208
20130101 |
Class at
Publication: |
166/187 |
International
Class: |
E21B 23/04 20060101
E21B023/04 |
Claims
1. A packer for downhole use, comprising: a mandrel; a
multi-component element wherein a first component, having a
cohesive shape supported by said mandrel, swells responsive to
water containing fluid and a second component controls access of
water containing fluids to said first component.
2. The packer of claim 1, wherein: said second component is mounted
over said first component.
3. The packer of claim 2, wherein: said second component allows
water containing fluid to diffuse through it.
4. The packer of claim 3, wherein: said second component has
openings.
5. The packer of claim 1, wherein: said second component dissolves
in the presence of water containing fluids.
6. The packer of claim 1, wherein: said first component is made of
an elastomeric polymer material or acrylate, acetate or formate
salts.
7. The packer of claim 6, wherein: said material further comprises
acrylonitrile, nitrile, hydrogenated nitrile, chloroprene, ethylene
vinyl acetate, ethylene propylene diene monomer, ethylene
propylene, or polynorbornen and acrylic copolymer, super absorbent
polymers (SAP), carboxy methyl cellulose or/and a partially
modified or fully cross-linked acrylic polymer added.
8. The packer of claim 1, wherein: said second component is made of
an elastomeric polymer material or acrylate, acetate or formate
salts.
9. The packer of claim 8, wherein: said material further comprises
acrylonitrile, nitrile, hydrogenated nitrile, chloroprene, ethylene
vinyl acetate, ethylene propylene diene monomer, ethylene
propylene, or polynorbornen with an acrylic copolymer added.
10. The packer of claim 1, wherein: said second component swells
less than said first component.
11. The packer of claim 1, wherein: said second component diffuses
water containing fluids at a slower rate than said first
component.
12. The packer of claim 10, wherein: said first component comprises
an annular cylindrical shape disposed around said mandrel.
13. The packer of claim 12, wherein: said second component covers
substantially the entire outer surface of said first component.
14. The packer of claim 11, wherein: said first component comprises
an annular cylindrical shape disposed around said mandrel.
15. The packer of claim 14, wherein: said second component covers
substantially the entire outer surface of said first component.
16. The packer of claim 10, wherein: said second component diffuses
water containing fluids at a slower rate than said first component.
Description
FIELD OF THE INVENTION
[0001] The field of the invention is a packer for downhole use and
more particularly a swelling packer responsive to water containing
fluids where the swelling rate is regulated to allow proper
placement before a full set.
BACKGROUND OF THE INVENTION
[0002] Packers are used to isolate zones in a wellbore. Many
different types of packers have been used over the years. Some of
these designs involve mechanical compression that comes from a
setting tool that uses relative movement. Other designs use
pressure that is converted with a piston to a mechanical force to
set the packer. Another packer style is an inflatable where the
fluid is pumped through a series of check valves into a sealed
annular space between a mandrel and an element. One end of the
element is generally fixed to the mandrel with the opposite end
riding toward it as the element radially expands from the pumped
fluid into the annular space.
[0003] More recently, packers have used materials that swell. In
one design a structure similar to an inflatable was used and the
annular space contained swelling clay such as bentonite. Annular
well fluids were admitted into this annular space and distributed
with a wick. The swelling clay then enlarged the annular space
defined by the sealing element until the assembly closed off the
wellbore. Another design used an elastic polymer sensitive to
hydrocarbons in the well. There was an inner and an outer layer
that was rubber and allowed the hydrocarbons to get through to the
inner core. The outer layer had a greater resistance and a lower
diffusion rate to hydrocarbons than the core. The outer layer was
optionally reinforced. This design is described in U.S. Pat. No.
7,143,832. Also of interest but working in the opposite direction
are plugs that can be used downhole and then removed by exposure to
well fluids such as is illustrated in U.S. Pat. No. 5,607,017.
Packers that use water expandable materials are shown in U.S. Pat.
No. 5,048,605 and Japan application 07-334115 filed Nov. 29, 1995
and entitled Borehole Packing Method
[0004] What is needed and is the focus of the present invention is
a packer that employs swelling and sensitivity to water containing
fluids and that has a mechanism to control the swelling of a core
until the packer is delivered in its intended location. An outer
covering layer is fitted over the core where preferably the outer
layer allows water containing fluids to diffuse but that has a
substantially lower swelling rate than the core in response to
water containing fluids. As a result, the core is protected and its
swelling is inhibited long enough to allow it to be properly
placed. Alternatively the outer covering can be made to dissolve in
water containing fluids as opposed to diffusing water containing
fluids and swelling at a lower rate than the core. These and other
aspects of the present invention will be more readily understood by
those skilled in the art from a review of the description of the
preferred embodiment and the associated drawing, which appear below
while understanding that the claims determine the full scope of the
invention.
SUMMARY OF THE INVENTION
[0005] A packer for downhole use responds to water containing
fluids by swelling from its core. The core is preferably covered
with an outer layer that preferably has a lower rate of diffusion
and swelling than the core that it surrounds. Because of this
arrangement, the packer can be delivered to the desired location
before it is set by swelling of the core. The outer layer can also
be responsive to water containing fluids by dissolving slowly to
allow time to properly position the packer before the core swells
to a sealing relationship with the surrounding tubular or the
wellbore wall.
BRIEF DESCRIPTION OF THE DRAWING
[0006] FIG. 1 is a half section view of the packer in the run in
configuration before the core swells.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0007] The packer of the present invention is illustrated in FIG.
1. In the preferred embodiment, the mandrel 10 is surrounded by a
core material 12 which in turn is covered by an outer layer 14. The
core material and the outer layer material are preferably
responsive to water containing fluids which are defined as having
at least 2% water and the preferred responses to exposure to such
fluids is diffusion and swelling. Swelling in water or saline
brines is illustrated by a super absorbent polymer, sodium
polyacrylate. Sodium polyacrylate is a polyelectrolyte and swells
due to osmotic pressure effects. The fixed anionic charge on the
pendent group of the polymer chain or on the swelling agent needs
to be balanced by cationic counter ions to maintain electro
neutrality. Thus, the counter ions will not diffuse out of the
polymer matrix although they are mobile. As a consequence, the
chemical potential of the counter ions in the polymer matrix is
higher than that of the counter ions in the water outside the
polymer. To equalize the chemical potential of the counter ions (or
to maintain thermodynamic equilibrium), water migrates into the
polymer matrix, leading to swelling of the polymer matrix. The
extent of swelling of the polymer matrix is derived from the
balance between the elasticity of the polymer network and the
osmotic pressure effects of the counter ions. The water swellable
rubber can be obtained by either copolymerization or compounding of
a polyelectrolyte polymer with rubber.
[0008] Preferably the core 12 swells more extensively than the
outer layer 14. In that manner, the outer layer 14 delays the
swelling of the core in the presence of water containing fluids so
that the packer P of the present invention can be delivered to the
desired location. Stated differently, the balance between the
elasticity of the outer polymer network and the osmotic pressure
forces is in favor of limiting the swell reaction rate while the
balance between the elasticity and the osmotic pressure forces of
the inner layer are in favor of swelling (expansion). The net
result is the inner layer expands the outer layer, or the outer
layer retards the swell (expansion) rate of the inner layer.
[0009] The outer layer 14 protects the core from abrasion and other
mechanical impacts and regulates the rate that the water containing
fluids reach the core 12.
[0010] The core 12 can preferably be made from acrylate, acetate or
formate salts or one of the following elastomeric polymer materials
or combinations thereof: acrylonitrile, nitrile, hydrogenated
nitrile, chloroprene, ethylene vinyl acetate, ethylene propylene
diene monomer, ethylene propylene, or polynorbornen and acrylic
copolymer, super absorbent polymers (SAP), carboxy methyl cellulose
or/and a partially modified or fully cross-linked acrylic polymer
added.
[0011] The outer layer 14 can be made from acrylate, acetate or
formate salts or one or more of the following elastomeric polymer
materials or combinations thereof: acrylonitrile, nitrile,
hydrogenated nitrile, chloroprene, ethylene vinyl acetate, ethylene
propylene diene monomer, ethylene propylene, or polynorbornen with
an acrylic copolymer added.
[0012] The outer layer 14 can be continuous in its coverage of the
core 12 or there can be openings or gaps in the outer layer through
which water containing fluids can reach the core 12. The outer
layer 14 can be in a single or multiple layers. If it is continuous
the water containing fluid can diffuse through it to reach the core
12. Alternatively, the outer layer can be made of a material that
will dissolve in a water containing fluid such as water containing
drilling mud, sea water or saline brines.
[0013] The core 12 and the outer layer 14 should preferably have
different swelling or diffusion rates with the core 12 swelling
substantially more than the outer layer 14 and preferably having a
higher diffusion rate for water containing fluids than the outer
layer 14. Together the packer P components can take the shape of an
irregular wellbore. In the preferred embodiment the packer P
responds only to the presence of water containing fluids.
[0014] When the outer layer is designed to dissolve in water
containing fluids, it simply slowly goes away as the core 12
swells.
[0015] The core need not be uniform as far as the material. It can
be designed to swell more toward the center of the element
initially so that well fluids are displaced to opposed ends that
have not yet swelled into contact with the surrounding
wellbore.
[0016] The above description is illustrative of the preferred
embodiment and various alternatives and is not intended to embody
the broadest scope of the invention, which is determined from the
claims appended below, and properly given their full scope
literally and equivalently.
* * * * *