U.S. patent application number 12/802223 was filed with the patent office on 2010-09-23 for downhole sealing devices having a shape-memory material and methods of manufacturing and using same.
Invention is credited to Ping Duan, Paul M. McElfresh.
Application Number | 20100236794 12/802223 |
Document ID | / |
Family ID | 40130840 |
Filed Date | 2010-09-23 |
United States Patent
Application |
20100236794 |
Kind Code |
A1 |
Duan; Ping ; et al. |
September 23, 2010 |
Downhole sealing devices having a shape-memory material and methods
of manufacturing and using same
Abstract
Sealing devices such as packers comprise a shape-memory material
having a compressed run-in position or shape and an original
expanded position or shape. The shape-memory material may comprise
a polyurethane foam material held in the compressed run-in position
by an adhesion material that is dissolvable by a fluid. The fluid
may be a wellbore fluid already present in the wellbore or a fluid
pumped down the wellbore after the sealing device is disposed
within the wellbore. The fluid may also be a production fluid from
the well. Upon being contacted by the fluid, the adhesion material
dissolves and the shape-memory material expands to its original
expanded position or shape, thereby sealing and dividing the
annulus of the wellbore.
Inventors: |
Duan; Ping; (Spring, TX)
; McElfresh; Paul M.; (Spring, TX) |
Correspondence
Address: |
GREENBERG TRAURIG (HOU);INTELLECTUAL PROPERTY DEPARTMENT
1000 Louisiana Street, Suite 1700
Houston
TX
77002
US
|
Family ID: |
40130840 |
Appl. No.: |
12/802223 |
Filed: |
June 2, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11904934 |
Sep 28, 2007 |
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12802223 |
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Current U.S.
Class: |
166/387 ;
166/179 |
Current CPC
Class: |
E21B 33/127 20130101;
C08G 2110/0033 20210101; C08G 18/44 20130101 |
Class at
Publication: |
166/387 ;
166/179 |
International
Class: |
E21B 33/12 20060101
E21B033/12 |
Claims
1. A sealing device for use in a wellbore to isolate an annulus of
the wellbore, the sealing device comprising: a shape-memory
material, the shape-memory material having a compressed position
and an expanded position and the shape-memory material being
maintained in the compressed position by a dissolvable adhesion
material, wherein the dissolvable adhesion material is dissolvable
by a wellbore fluid placed in contact with the adhesion
material.
2. The sealing device of claim 1, wherein the shape-memory material
comprises a polyurethane foam material.
3. The sealing device of claim 1, wherein the dissolvable adhesion
material comprises a polymer.
4-19. (canceled)
20. A method of sealing wellbore to divide an annulus of the
wellbore, the method comprising: (a) securing a downhole tool to a
string of tubing, the downhole tool comprising a sealing device
comprising a shape-memory material, the shape-memory material
having a compressed run-in position and an original expanded
position, wherein the shape-memory material is maintained in the
compressed run-in position by a dissolvable adhesion material; (b)
running the downhole tool in a wellbore; (c) contacting the
shape-memory material and dissolvable adhesion material with a
fluid; (d) dissolving the dissolvable adhesion material with the
fluid; (e) expanding the shape-memory material from the compressed
run-in position to the original expanded position, thereby sealing
and dividing the annulus of wellbore with the shape-memory material
in the original expanded position.
21. The method of claim 20, wherein the fluid is water.
22. The method of claim 20, wherein the fluid is oil.
Description
BACKGROUND
[0001] 1. Field of Invention
[0002] The invention is directed to sealing devices used in oil and
gas wellbores to seal the wellbore and, in particular, to sealing
devices having shape memory materials that remain in a compressed
state until wellbore fluid, such as oil or water, contacts the
shape memory material so that the shape memory material can expand
and seal the wellbore.
[0003] 2. Description of Art
[0004] Packers having swellable materials encased within an
expandable sealing element such as a rubber casing or balloon are
known in the art. These types of packers expand and, thus, seal to
the inner wall surface of a wellbore by contacting hydraulic fluid
or other fluid with the swellable materials encased within the
rubber casing so that the swellable materials absorb the fluid and
expand. In one type of these packers, for example, hydraulic fluid
is pumped down a string of tubing having the packer secured
thereto. The hydraulic fluid travels down the bore of the string of
tubing and through a port that is in fluid communication with an
inner cavity of the rubber casing. Swellable materials disposed
within the rubber casing are contacted by the hydraulic fluid. As a
result, the swellable materials absorb the fluid and expand. As the
swellable materials expand and hydraulic fluid is pumped into the
rubber casing, the rubber casing expands to seal the wellbore.
After expansion, hydraulic fluid pressure is decreased and the
rubber casing remains is held in the expanded position solely by
the swellable materials having absorbed the fluid. The swellable
materials, however, become softer and lack desirable prolonged
strength after expansion because the fluid, which is considered a
solvent, reduces intramolecular van der Waals interactions. As a
result, packers relying on swellable materials to create a seal
with an inner wall surface of the wellbore can prematurely fail
because the swellable materials become weaker.
SUMMARY OF INVENTION
[0005] Broadly, downhole tools and, in particular, sealing elements
or devices such as packers, are disclosed. The sealing devices
include one or more shape-memory materials that are run-in to the
wellbore in a compressed shape or position. The shape-memory
material is held in the compressed shape by an adhesion material.
The adhesion material is dissolvable by a fluid placed in contact
with the adhesion material such that when the adhesion material
comes into contact with the fluid, the adhesion material dissolves.
In certain embodiments, the adhesion material is dissolvable by
water. In other embodiments, the adhesion material is dissolvable
by a hydrocarbon such as oil.
[0006] After the sealing device having the shape-memory material is
located at the desired location within the well, the shape-memory
material is contacted with the fluid that dissolves the adhesion
material. After dissolution of the adhesion material, the
shape-memory material is allowed to expand to its pre-compressed
shaped, i.e., its original, expanded shape or set position. The
expanded shape or set position, therefore, is the shape of the
shape-memory material after it is manufactured and before it is
compressed. In other words, the shape-memory material possesses
hibernated shape memory that provides a shape to which the
shape-memory material naturally takes after its manufacturing.
[0007] As a result of the shape-memory material being expanded to
its set position, the shape-memory material seals the annulus of
the wellbore. Although the shape-memory material expands due to its
contact with the dissolving fluid, it is to be understood that the
shape-memory material returns to its original, expanded shape due
to the shape-memory characteristics of the shape-memory material
and not due to the shape-memory material absorbing any fluid. In
other words, even though fluid may enter into pores, cells, or
crevices of the shape-memory material, the fluid so disposed is not
required to maintain the shape-memory material in the original,
expanded shape.
[0008] In one specific embodiment, the shape-memory materials is a
polyurethane foam material that is extremely tough and resilient
and that is capable of being compressed and returned to
substantially its original expanded shape. The polyurethane foam
material is held in the compressed state by an adhesion material.
Once the adhesion material is dissolved, the polyurethane foam
material is no longer held in its compressed or run-in shape and,
thus, the polyurethane foam material expands toward its original
shape. In so doing, the polyurethane foam material engages the
inner wall surface of the wellbore, either directly or indirectly
such as by having a rubber outer shell covering the polyurethane
foam material. In certain embodiments, the inner wall surface of
the wellbore is defined by the inner diameter of wellbore casing.
In other embodiments, the inner wall surface of the wellbore is
"open-hole," i.e., defined by the hole drilled into the earth
formation.
BRIEF DESCRIPTION OF DRAWINGS
[0009] FIG. 1 is a cross-sectional view of one embodiment of a
sealing device disclosed herein shown in the compressed or run-in
position.
[0010] FIG. 2 is a cross-sectional view of the sealing device of
FIG. 1 shown in the expanded or set position.
[0011] While the invention will be described in connection with the
preferred embodiments, it will be understood that it is not
intended to limit the invention to that embodiment. On the
contrary, it is intended to cover all alternatives, modifications,
and equivalents, as may be included within the spirit and scope of
the invention as defined by the appended claims.
DETAILED DESCRIPTION OF INVENTION
[0012] Referring now to FIGS. 1-2, sealing device 30 is disposed on
the outer wall surface 40 of a tubing string 42. As shown in FIGS.
1-2, sealing device 30 comprises shape-memory material 32
comprising a polyurethane foam material. The polyurethane foam
material is formed by combining two separate portions of chemical
reactants. These two separate portions are referred to herein as
the isocyanate portion and polyol portion. The isocyanate portion
may comprise a modified isocyanate (MI) or a modified
diphenylmethane diisocyanate (MDI) based monomeric diisocyanate or
polyisocyanate. The polyol portion may comprise a polyether,
polyester or polycarbonate-based di- or multifunctional hydroxyl
ended prepolymer.
[0013] Water is included as part of the polyol portion and acts as
a blowing agent to provide a foam structure because of carbon
dioxide generated from the reaction between isocyanate and water
when the isocyanate portion and the polyol portion are
combined.
[0014] In one embodiment, the isocyanate portion contains modified
MDI Mondur PC and the polyol portion contains (1) polyester polyol,
which consist of a trimethylolpropane branched diethylene glycol
adipate sold under the commercial name as Fomrez 45 from Crompton
Corporation; (2) chain extender aromatic diamine
Dimethylthiotoluenediamine ("DMTDA") sold by Albemarle under the
commercial name Ethacure 300; (3) catalysts; (4) surfactant; and
(5) water. The chain extender is a liquid slower polyurethane
curative that provides enhanced high temperature properties. The
catalyst and surfactant are added into the polyol portion to
control final foam cell structure, either open or close, as well as
the foam physical properties. In certain embodiments, either amine
or metal-based catalysts are included to achieve good properties of
polyurethane foam materials. Such catalysts are commercially
available from companies such as Air Products. Suitable catalysts
that provide especially good properties of polyurethane foam
materials include pentamethyldipropylenetriamine, an amine-based
catalyst sold under the commercial name Polycat 77 by Air Products,
dibutyltindilaurate, a metal-based catalyst sold under the
commercial name DABCO T-12 by Air Products.
[0015] A small amount of surfactant, e.g., 0.5% of total weight,
such as the surfactant sold under the commercial name DABCO DC-198
by Air Products, can be added to control foam cell structure and
distribution. Colorant may be added in the polyol portion to
provide desired color in the finished product. Such colorants are
commercially available from companies such as Milliken Chemical
which sells a suitable colorant under the commercial name
Reactint.
[0016] After the isocyanate portion and the polyol portions are
prepared, they are combined together at a desired temperature. The
temperature at which the two portions are combined determines the
degree of cell size within the resultant polyurethane foam
material. For example, higher temperatures of the mixture provide
larger cell size while lower temperatures of the mixture provide
smaller cell size.
[0017] In one particular embodiment, the polyester polyol
comprising of a trimethylolpropane branched diethylene glycol
adipate sold under the commercial name as Fomrez 45 from Crompton
Corporation, is pre-heated to 100.degree. C. before combining with
the isocyanate portion. The isocyanate portion is the combined with
the polyol portion and a foaming reaction is immediately initiated
and the mixture's viscosity increases rapidly.
[0018] In another particular embodiment, the polyol comprising of
poly(1,6-hexanediol carbonate) polyol sold by Arch Chemicals under
the commercial name Poly-CD220 is preheated to 100.degree. C.
before combing with the isocyanate portion. The isocyanate portion
is then combined with the polyol portion and a foaming reaction is
immediately initiated and the mixture's viscosity increases
rapidly. The resulting foam made from polycarbonate polyols has a
high resistance to hydrolysis and oil attacks.
[0019] Due to the high viscosity of the mixture and the reaction
occurring quickly, a suitable mixer is recommended to form the
polyurethane foam material. Although there are many commercially
available fully automatic mixers specially designed for two-part
polyurethane foam processing, it is found that mixers such as
KitchenAid type mixers with single or double blades work
particularly well. In large-scale mixing, eggbeater mixers and
drill presses work particularly well.
[0020] In mixing the isocyanate and polyol portions, the amount of
isocyanate and polyol included in the mixture should be chemically
balanced according to their equivalent weight. In one specific
embodiment, 5% more isocyanate by equivalent weight is combined
with the polyol portion.
[0021] In one embodiment, the polyol portion is formed by 50 g of
Fomrez 45 polyester polyol is combined with 1.6 g of water, 1.5 g
of DMTDA chain extender, 0.1 g of Polycat 77 catalyst, 0.5 g of
DABCO DC-198 surfactant, and 0.5 g of Reactint colorant to form the
polyol portion. The polyol portion is preheated to 100.degree. C.
and mixed in a KitchenAid type single blade mixer with 40.4 of MDI
Mondur PC. As will be recognized by persons of ordinary skill in
the art, these formulations can be scaled-up to form larger volumes
of this shape-memory material.
[0022] In another embodiment, the polyol portion is formed by 50 g
of Poly-CD220 polycarbonate polyol is combined with 1.6 g of water,
1.5 g DMTDA chain extender, 0.1 g of Polycat 77 catalyst, 0.5 g
DABCO DC-198 surfactant, and 0.5 g Reactint colorant to form the
polyol portion. The polyol portion is preheated to 100.degree. C.
and mixed in a KitchenAid type single blade mixer with 41.5 g of
MDI Mondur PC. As will be recognized by persons of ordinary skill
in the art, these formulations can be scaled-up to form larger
volumes of this shape-memory material.
[0023] The mixture containing the isocyanate portion and the polyol
portion is mixed for about 20 seconds and then poured into a mold
and immediately closed by placing a top metal plate on the mold.
Due to the significant amount of pressure generated by the
foam-forming process, a C-clamp can be used to hold the top metal
plate and mold together to prevent leakage of the mixture from the
mold. After approximately 2 hours, the polyurethane foam material
is sufficiently cured such that the mold can be removed.
Thereafter, in one specific embodiment, the polyurethane foam
material is treated "post-cure" at a temperature of 100.degree. C.
for approximately 6 hours so that the polyurethane foam material
reaches its full strength.
[0024] Additionally, the polyurethane foam material at this stage
will, almost always, include a layer of "skin" on the outside
surface of the polyurethane foam. The "skin" is a layer of solid
polyurethane elastomer formed when the mixture contacts with the
mold surface. It is found that the thickness of the skin depends on
the concentration of water added to the mixture. Excess water
content decreases the thickness of the skin and insufficient water
content increases the thickness of the skin. The formation of the
skin is believed to be due to the reaction between the isocyanate
in the mixture and the moisture on the mold surface. Therefore,
additional mechanic conversion processes are needed to remove the
skin. Tools such as band saws, miter saws, or hack saws may be used
to remove skin. After removing the skin from the polyurethane foam
material, it will have a full open cell structure, excellent
elasticity, and very good tear strength.
[0025] At this point, the polyurethane foam material is in its
original, expanded, shape having an original, or expanded,
thickness 36 (FIG. 2).
[0026] Prior to including the polyurethane foam material as part of
sealing device 30, the polyurethane foam material is saturated in
an adhesion material. Suitable adhesion materials include water and
isopropyl alcohol dissolvable polymers such as poly(vinyl
pyrrolidone) sold by International Specialty Products under the
commercial name PVP K-30. This adhesion material is used for
water-triggered shape-memory polyurethane foam materials. Any
polymers that are dissolvable in oil and solvent can be used for as
adhesion materials for oil-triggered shape-memory materials.
Suitable polymers for these applications include polystyrene,
poly)methyl methacrylate), etc.
[0027] The adhesion materials are usually supplied in the form of
solid powders or pellets. Therefore, the adhesion material solution
has to be prepared before use. For one specific example of
water-triggered adhesion material solution, 30% PVP K-30 and 70%
isopropyl alcohol ("IPA") by weight are mixed together. For one
specific example of an oil-triggered adhesion material solution,
30% polystyrene pellets and 70% Methyl Isobutyl Ketone ("MIBK") by
weight are mixed together.
[0028] After saturation of the polyurethane foam material in the
adhesion material solution, a vacuum at approximately 762 mm Hg is
applied to the polyurethane foam material so that the adhesion
material solution can penetrate throughout the cells of the
polyurethane foam material, air trapped inside the polyurethane
foam material can be removed, and voids within the polyurethane
foam material can be replaced with the adhesion material
solution.
[0029] The polyurethane foam material impregnated with the adhesion
material solution is then placed between two metal plates and
mechanically compressed from its original, or expanded, thickness
of about 20 mm to approximately 14 mm or less. In one specific
embodiment, the polyurethane foam material impregnated with the
adhesion material solution is compressed from an original thickness
to about 50% of the original thickness. In another embodiment, the
polyurethane foam material impregnated with the adhesion material
is compressed from an original thickness to about 30% of the
original thickness. Spacers and c-clamps can be used to control
finished thickness. The compressed polyurethane foam material is
then placed inside a vacuum oven and heated to 80.degree. C. for
approximately 8 hours or more to remove all of the liquid used to
suspend the adhesion material from the polyurethane foam
material.
[0030] After all of this suspending liquid is removed from the
polyurethane foam material, the finished polyurethane foam material
is stable in its compressed position or shape at dry conditions and
has compressed, or run-in, thickness 34. The polyurethane foam
material can then be installed onto a base pipe with a permanent
bonding material so that the polyurethane foam material forms
sealing device 30. Alternatively, the polyurethane foam material
may be included as part of sealing device 30 such as by including a
rubber casing over the polyurethane foam material in place of the
prior art swellable absorbent materials.
[0031] The impregnated polyurethane foam material remains in its
compressed state, or run-in position, during run-in of the sealing
device 30 into wellbore 50. The impregnated polyurethane foam
material also remains in the run-in position until the correct
fluid contacts the impregnated polyurethane foam material for a
sufficient amount of time so that the adhesion material dissolves
and the polyurethane foam material can expand to the set or
expanded position. The correct fluid may be water, oil, or some
other type of fluid. The correct fluid is determined based upon the
adhesion material utilized in forming the impregnated polyurethane
foam material. If the adhesion material is dissolvable in water,
then the correct fluid is water. If the adhesion material is
dissolvable in oil, then the correct fluid is oil.
[0032] In the embodiment in which the correct fluid is water, the
water dissolves the adhesion material. As a result, the forces
holding the impregnated polyurethane foam weaken until the point
that the energy stored in the polyurethane foam material are
greater than the adhesion forces provided by the adhesion material.
At that point, the polyurethane foam material expands from its
compressed position to its original shape as formed prior to
impregnation and compression. In so doing, the polyurethane foam
material contacts inner wall surface 54 of wellbore 50 to establish
a seal that divides annulus 60 of the wellbore 50. As will be
recognized by persons of ordinary skill in the art, expansion of
the polyurethane foam material is not dependent upon absorption of
any fluid. Thus, the polyurethane foam material, by itself,
provides the expanded shape to establish the seal against inner
wall surface 54 of wellbore 50.
[0033] Still with reference to FIGS. 1-2, in operation, the tubing
string having sealing device 30 comprising shape-memory material 32
is run-in wellbore 50, which is defined by wellbore casing 52, to
the desired location. As shown in FIG. 1, shape-memory material 32
has a compressed, run-in, thickness 34. Fluid is then either pumped
down annulus 60 between outer wall surface 42 and inner wall
surface 54 of wellbore casing 52. Alternatively, fluid can be
pumped down bore 44 of tubing string 42 and through ports (not
shown) in the wall of tubing string 42 to contact sealing device
30. By contacting sealing device 30 and, thus, shape-memory
material 32, the fluid "activates" shape-memory material 32 by
dissolving the adhesion material holding shape-memory material 32
in the run-in or compressed position. After a sufficient amount of
adhesion material is dissolved, i.e., after the adhesion material
is dissolved such that the stored energy in the compressed
shape-memory material 32 is greater than the compressive forces
provided by the adhesion material, shape-memory material 32 expands
from the run-in or compressed position (FIG. 1) to the expanded or
set position (FIG. 2) having an original, expanded, thickness 36.
In so doing, shape-memory material 32 engages with inner wall
surface 54 of wellbore casing 50 to divide annulus 60 and, thus,
isolate a portion of wellbore 50 below sealing device 30.
[0034] As will be recognized by persons of ordinary skill in the
art, sealing device 30 should have an outer diameter around tubing
string 42, i.e., original or expanded thickness 36 that is large
enough such that expansion of sealing device 30 results in sealing
device 30 exerting a force into inner wall surface 54 of wellbore
casing 52 so that a sufficient seal can be formed between sealing
device 30 and inner wall surface 54 of wellbore casing 52.
Therefore, the outer diameter of tubing sting 42, as well as inner
diameter of wellbore casing 52 should be taken into consideration
when determining the thickness (or outer diameter) formed by
sealing device 30. Determining the size of shape-memory material 32
in a given sealing device 30 to provide the desired or necessary
sealing between the sealing device and the inner wall surface of
the wellbore is easily achieved by persons of ordinary skill in the
art in light of the present disclosure.
[0035] In one embodiment, the adhesion material is selected based
upon its ability to maintain shape-memory material 32 in the
compressed position (FIG. 1) while being submerged in water, oil,
or other fluid for an amount sufficient for tubing string 42 to be
lowered and properly disposed within wellbore casing 52 prior to
expansion. Thus, sealing device 30 is capable of being run-in
wellbores having fluids already present in within annulus 60
without concern that shape-memory material 32 will expand
prematurely. In certain embodiments, the adhesion material has a
known dissolution rate so that the time for sealing device 30 to
expand from the run-in position (FIG. 1) to the set position (FIG.
2) can be predicted with little or no error. In other embodiments,
shape-memory material 32 and, thus, the adhesion material, are
protected from prematurely contacting the fluid that is used to
dissolve the adhesion material such as by encasing shape-memory
material 32 with an additional layer of polyurethane coating. This
additional polyurethane coating on the outside surface of the
shape-memory material includes those that are easily degradable in
a fluid such as conventional liquid moisture-cured TDI-polyether
based polyurethane resin. These conventional moisture-cured
polyurethane resins can be obtained from companies such as Bayer as
sold under the commercial name Baytec MP-080.
[0036] The use of shape-memory materials provide prolonged
resiliency and strength compared to swellable materials and other
materials that rely on absorb fluids to maintain their expanded
shapes. Moreover, the shape-memory materials provide their sealing
characteristics in their naturally occurring expanded shapes,
whereas the swellable materials and other materials that rely on
absorbed fluids to maintain their expanded shapes are in their
"unnaturally" occurring expanded shape. In other words, the
shape-memory materials are energized in their compressed position,
and unenergized in their expanded position, whereas the swellable
materials are unenergized in their compressed positions and
energized in their expanded positions. As a result, the swellable
materials have a tendency to release their energy when in their
expanded position, thereby weakening the seal against the inner
wall surface of the wellbore. On the other hand, the shape-memory
materials have no stored energy in their expanded position that, if
released, would weaken the seal against the inner wall surface of
the wellbore. Thus, any stored energy in the shape-memory materials
would only create a greater force into the inner wall surface of
the wellbore to increase the strength of the seal against the inner
wall surface of the wellbore.
[0037] It is to be understood that the invention is not limited to
the exact details of construction, operation, exact materials, or
embodiments shown and described, as modifications and equivalents
will be apparent to one skilled in the art. Accordingly, the
invention is therefore to be limited only by the scope of the
appended claims.
* * * * *