Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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PREVENTION, ACTUATION AND CONTROL OF DEPLOYMENT OF
MEMORY-SHAPE POLYMER FOAM-BASED EXPANDABLES
TECHNICAL FIELD
[0001] The present invention relates to devices used in oil and gas well-
bores employing shape-memory materials that remain in an altered geometric
state during run-in; once the devices are in place downhole and are exposed to
a given temperature at a given amount of time, the devices attempt to return
to
their original geometric position prior to alteration. More particularly, the
present
invention relates to such devices where the Tg and/or its rigidity decrease by
optionally using a deployment fluid or which deployment fluid may be removed
from contact with the devices.
TECHNICAL BACKGROUND
[0002] Various methods of filtration, wellbore isolation, production
control,
wellbore lifecycle management, and wellbore construction are known in the art.
The use of shaped memory materials in these applications have been dis-
closed for oil and gas exploitation. Shape Memory Materials are smart materi-
als that have the ability to return from a deformed or compressed state (tempo-
rary shape) to their original (permanent) shape induced by an external
stimulus
or trigger (e.g. temperature change). In addition to temperature change, the
shape memory effect of these materials may also be triggered by an electric or
magnetic field, light, contact with a particular fluid or a change in pH.
Shape-
memory polymers (SMPs) cover a wide property range from stable to biode-
gradable, from soft to hard, and from elastic to rigid, depending on the struc-
tural units that constitute the SMP. SMPs include thermoplastic and thermoset
(covalently cross-linked) polymeric materials. SMPs are known to be able to
store multiple shapes in memory.
[0003] Dynamic Mechanical Analysis (DMA), also called dynamic mechani-
cal thermal analysis (DMTA) or dynamic thermomechanical analysis is a tech-
nique used to study and characterize SMP materials. It is most useful for
observing the viscoelastic nature of these polymers. The sample deforms under
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a load. From this, the stiffness of the sample may be determined, and the
sample modulus may be calculated. By measuring the time lag in the displace-
ment compared to the applied force it is possible to determine the damping
properties of the material. The time lag is reported as a phase lag, which is
an
angle. The damping is called tan delta, as it is reported as the tangent of
the
phase lag.
[0004] Viscoelastic materials such as shape-memory polymers typically exist
in two distinct states. They exhibit the properties of a glass (high modulus)
and
those of a rubber (low modulus). By scanning the temperature during a DMA
experiment this change of state, the transition from the glass state to the
rubber
state, may be characterized. It should be noted again that shaped memory may
be altered by an external stimulus other than temperature change.
[0005] The storage modulus E' (elastic response) and loss modulus E"
(viscous response) of a polymer as a function of temperature are shown in FIG.
1. The nature of the transition state of the shaped memory polymer affects
material's shape recovery behavior and can be descriptive of the polymer's
shape recovery. Referring to FIG. 1, the Glass State is depicted as a change
in
storage modulus in response to change in temperature which yields a line of
constant slope. The Transition State begins when a slope change occurs in the
storage modulus as the temperature is increased. This is referred to as the Tg
Onset which in FIG. 1 is approximately 90 C. The Tg Onset is also the point
where shape recovery can begin. Tg for a shape-memory polymer described by
FIG. 1 is defined as the peak of the loss modulus, which in FIG. 1 is approxi-
mately 110 C. If the slope's change of the storage modulus were represented
by a vertical line of undefined slope, the material shape recovery would occur
at a specific temperature and transition immediately from the glassy state to
the
rubber state. Generally, the more gradual the slope change of the storage
modulus in the transition state, the greater the range of temperatures which
exhibit characteristics of both the glass and rubber states. The transition
state
is the area of interest for the SMP material's shape recovery characteristics.
It
should also be evident that shape recovery would occur more slowly if stimulus
temperature is closer to the Tg Onset temperature and that shape recovery
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would be more rapid as the stimulus temperature approached or exceeded the
Tg.
[0006] One method of making use of the unique behavior of shape-memory
polymers is via temperature response described above. An example is seen in
FIG. 2. The finished molded part 100 of shape-memory polymer has a defined
Tg and Tg Onset. This may be considered an original geometric position of the
shape-memory material. The part is then heated close to the Tg of the polymer.
Force is applied to the finished part to reshape the part into a different
config-
uration or shape 100'. This may be considered an altered geometric position of
the shape-memory material. The reshaped part 100' is then cooled below the
shape-memory polymer's Tg Onset and the force removed. The finished part
100' will now retain the new shape until the temperature of the part is raised
to
the Tg Onset at which point shape recovery will begin and the part will
attempt
to return to its original shape 100 or if constrained, the part will conform
to the
new constrained shape 100". This shape 100" may be considered the shape-
memory material's recovered geometric position.
[0007] U.S. Pat. No. 7,318,481 assigned to Baker Hughes Incorporated
disclosed a self-conforming expandable screen which comprises a thermoset-
ting open cell shape-memory polymeric foam. The foam material composition is
formulated to achieve the desired transition temperature slightly below the
anticipated downhole temperature at the depth at which the assembly will be
used. This causes the conforming foam to expand at the temperature found at
the desired depth.
[0008] Flawless installation and deployment of memory-shape polymer
foam-based conformable sand screens, packing elements and other downhole
tools are two crucial steps that determine the overall success of the
expandable
tool's operation. These steps may be challenging to execute. Therefore, effec-
tive prevention of the deployment during the installation, flawless triggering
of
the deployment of the expandable elements at the appropriate time, and
reliable control of the rate and the extent of the deployment are essential
for
the expandable elements' successful performance would be very desirable and
important. It would be very helpful to discover a method and device for pre-
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cisely installing and deploying an element made of shaped memory material at
a particular location downhole to achieve some desired function of filtration,
wellbore isolation, production control, wellbore lifecycle management, and
wellbore construction. Generally, the more control and versatility for
deploying
an element the better, as this gives more flexibility in device designs and
provides the operator more flexibility in designing, placement and
configuration
of the wellbore devices.
SUMMARY
[0009] This is provided, in one non-limiting form, a wellbore
device that
includes at least one polymeric shape-memory material having an original
glass transition temperature (Tg) and the original rigidity. The wellbore
device
also includes a deployment fluid contacting the polymeric shape-memory
material in an amount effective to have an effect selected from the group
consisting of lowering the T9 and/or decreasing the rigidity.
[0010] There is additionally provided in another non-restrictive
version a
method of installing a wellbore device on a downhole tool in a wellbore, the
method comprising: introducing the downhole tool bearing the wellbore device
into a wellbore, wherein the wellbore device comprises at least one polymeric
shape-memory material having an original glass transition temperature (Tg) and
an original rigidity, wherein the polymeric shape-memory material is in an
altered geometric position and the polymeric shape-memory material is
contacted by a first fluid; substantially removing the first fluid; contacting
the
polymeric shape-memory material with a deployment fluid in an amount
effective to have an effect upon the polymeric shape-memory material, the
effect selected from the group consisting of lowering the Tg, decreasing the
rigidity, and both; removing the deployment fluid; and recovering the
polymeric
shape-memory material from its altered geometric position for run-in to a
recovered geometric position, wherein the wellbore device has the property
that when substantially all of the deployment fluid is removed from the
polymeric shape-memory material, an effect is obtained selected from the
group consisting of restoring the Tg to within at least about 90% of the
original
Tg, restoring the rigidity to within at least about 25% of the original
rigidity, and
both.
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[0011] In another non-limiting embodiment there is provided a method of
installing a wellbore device on a downhole tool in a wellbore. The method
involves introducing the downhole tool bearing the wellbore device into a
wellbore. Again, the wellbore device includes at least one polymeric shape-
memory material having an original Tg and an original rigidity. The polymeric
shape-memory material is in an altered geometric position and the polymeric
shape-memory material is contacted by a first fluid. The first fluid is
substantially removed. The method further involves contacting the polymeric
shape-memory material with a deployment fluid in an amount effective to have
an effect selected from the group consisting of the lowering the Tg and/or
decreasing the rigidity. The deployment fluid may be optionally removed. The
method additionally involves recovering the polymeric shape-memory material
from its altered geometric position for run-in downhole to a recovered
geometric position.
[0012] There is further provided a method of installing a wellbore device
on
a downhole tool in a wellbore, the method comprising: introducing the
downhole tool bearing the wellbore device into a wellbore, wherein the
wellbore
device comprises: a substrate, and at least one polymeric shape-memory
material on the substrate, the polymeric shape-memory material having an
original glass transition temperature (Tg) and an original rigidity, wherein
the
polymeric shape-memory material is in an altered geometric position and the
polymeric shape-memory material is contacted by a first fluid, wherein the
polymeric shape-memory material is selected from the group consisting of
polyurethanes, polyurethanes made by reacting a polycarbonate polyol with a
polyisocyanate, polyamides, polyureas, polyvinyl alcohols, vinyl alcohol-vinyl
ester copolymers, phenolic polymers, polybenzimidazoles, polyethylene
oxide/acrylic acid/methacrylic acid copolymer crosslinked with N,N'-methylene-
bis-acrylamide, polyethylene oxide/methacrylic acid/N-vinyl-2-pyrrolidone
copolymer crosslinked with ethylene glycol dimethacrylate, polyethylene
oxide/poly(methyl methacrylate)/N-vinyl-2-pyrrolidone copolymer crosslinked
with ethylene glycol dimethacrylate, and combinations thereof; substantially
removing the first fluid; contacting the polymeric shape-memory material with
a
deployment fluid in an amount effective to have an effect upon the polymeric
shape-memory material, the effect selected from the group consisting of
lowering the Tg resulting in a second and lower Tg, decreasing the original
rigidity resulting in a second, decreased rigidity, and both; removing the
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deployment fluid; and recovering the polymeric shape-memory material from its
altered geometric position for run-in to a recovered geometric position,
wherein
the wellbore device has the property that when substantially all of the
deployment fluid is removed from the polymeric shape-memory material, an
effect is obtained selected from the group consisting of restoring the Tg to
within at least about 90% of the original Tg, restoring the rigidity to within
at
least about 25% of the original rigidity, and both.
[0013] The wellbore device may have a property that when the polymeric
shape-memory material is recovered from its altered geometric position, an
effect is obtained selected from the group consisting of restoring the Tg to
within at least about 90% of the original Tg, restoring the rigidity within at
least
about 25% of the original rigidity, and both.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a graph of storage modulus E' (elastic response) (left
vertical axis) and modulus E" (viscous response) (right vertical axis) as a
function of temperature for shape memory polymers illustrating the change in
each modulus as the polymer is heated from the Glass State through the
Transition State to the Rubber State;
[0015] FIG. 2 is a photograph of a finished shape-memory polymer part
before it is heated close to the Tg of the polymer and force is applied to
reshape it to a different configuration or shape and then cooled below the
polymer's onset Tg, and finally when the part is heated to the onset Tg at
which
point recovery will begin and the part returns to at or near its original
shape;
[0016] FIG. 3 is a schematic illustration of polyurethane chains coupled
via
hydrogen bonding, illustrating the crystal structure of polyurethane where the
mobility of polymer chains is limited, therefore the material has higher Tg;
[0017] FIG. 4 is a schematic illustration of the hydrogen bonding network
between polyurethane chains being disrupted by an alcohol deployment fluid
ROH, showing that the polymer chains are decoupled and relatively more
mobile, therefore, Tg of the material is lower and its rigidity is reduced;
[0018] FIG. 5 is a chart of % deployment of compacted samples of the
shape-memory polyurethane-polycarbonate rigid open-cell foam in vegetable
oil and water as a function of time at 65 C;
[0019] FIG. 6 is a graph of the storage (E) and loss (E') moduli of the
foam
samples immersed in vegetable oil and water as functions of the temperature;
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the glass transition temperature of the polymer immersed in liquid (Tg) corre-
sponds to the peak value of the loss modulus E",
[0020] FIG. 7 is a graph of the deployment temperatures of compacted
samples of a polymeric foam shape-memory material in water as a function of
temperature;
[0021] FIG. 8 is a graph of Tg as a function of % ethylene glycol monobutyl
ether (EGMBE) in an alcohol-based deployment fluid illustrating that the Tg of
the polymeric shape-memory material decreases as the EGMBE content in the
deployment fluid increases; and
[0022] FIG. 9 is a chart illustrating that the higher the content of the
EGMBE
in an alcohol-based deployment fluid is, the less time it takes to deploy the
polymeric shape-memory material to gauge hole diameter.
DETAILED DESCRIPTION
[0023] It has been discovered that the actuation and control of the
deploy-
ment of the memory-shape polymer foam-based expandables can be accom-
plished by treating the compacted expandables with deployment fluids reducing
the glass transition temperature of the polymer, Tg, softening the polymer
mate-
rial at a given temperature and, therefore, triggering its expansion. In
another
non-limiting embodiment, the expansion of the memory-shape polymer foam
may be accomplished without a deployment fluid (that is, in the absence of
such a specially engineered fluid such as a surfactant or alcohol) by
subjecting
the compacted expandable to a certain or particular temperature range. Alter-
natively, the deployment of the compacted expandables at a given temperature
may be prevented by shielding the expandables with a screen or shield of the
fluids from the naturally occurring wellbore deployment fluids.
[0024] Wellbore devices, such as those used in filtration, wellbore
isolation,
production control, lifecycle management, wellbore construction and the like
may be improved by including the shape-memory materials that are run into the
wellbore in altered geometric positions or shapes where the shape-memory
materials change to their respective original or recovered geometric positions
or
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shapes at different Tg Onsets and/or different slope changes (the slope change
in the respective transition state from a glass state to a rubber state).
[0025] The shape-memory material is made in one non-limiting embodiment
from one or more polyol, such as, but not limited to, a polycarbonate polyol
and
at least one isocyanate, including, but not necessarily limited to, a modified
diphenylmethane diisocyanate (MDI), as well as other additives including, but
not necessarily limited to, blowing agents, molecular cross linkers, chain
extenders, surfactants, colorants and catalysts.
[0026] The shape-memory polyurethane materials are capable of being
geometrically altered, in one non-limiting embodiment compressed substan-
tially, e.g., 20-30% of their original volume, at temperatures above their
onset
glass transition temperatures (Tg) at which the material becomes soft. While
still being geometrically altered, the material may be cooled down well below
its
Onset Tg, or cooled down to room or ambient temperature, and it is able to
remain in the altered geometric state even after the applied shape altering
force is removed. When the material is heated near or above its Onset Tg, it
is
capable of recovery to its original geometric state or shape, or close to its
original geometric position; a state or shape which may be called a recovered
geometric position. This is optionally done in the absence of a deployment
fluid.
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. The compositions of polyurethanes and other
polymeric shape-memory materials are able to be formulated to achieve
desired onset glass transition temperatures which are suitable for the
downhole
applications, where deployment can be controlled for temperatures below
Onset Tg of devices at the depth at which the assembly will be used.
[0027] Generally, polyurethane polymer or polyurethane foam is considered
poor in thermal stability and hydrolysis resistance, especially when it is
made
from polyether or polyester. It has been previously discovered that the
thermal
stability and hydrolysis resistance are significantly improved when the
polyure-
thane is made from polycarbonate polyols and methylene diphenyl diisocyanate
(MDI) as noted above. The compositions of polyurethane foam herein are able
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to be formulated to achieve different glass transition temperatures within the
range from 60 C to 170 C, which is especially suitable to meet most downhole
application temperature requirements. More details about these particular
polyurethane foams or polyurethane elastomers may be found in U.S. Pat. No.
7,926,565.
[0028] Notwithstanding the above, the wellbore devices described herein
and methods of using them may be practiced with a wide variety of polymeric
shape-memory materials including, but not necessarily limited to, polyure-
thanes, polyurethanes made by reacting a polycarbonate polyol with a polyiso-
cyanate , polyamides, polyureas, polyvinyl alcohols, vinyl alcohol-vinyl ester
copolymers, phenolic polymers, polybenzimidazole, polyethylene oxide/acrylic
acid/methacrylic acid copolymer crosslinked with N, N'-methylene-bis-acryl-
amide, polyethylene oxide/methacrylic acid/N-viny1-2-pyrrolidone copolymer
crosslinked with ethylene glycol dimethacrylate, polyethylene
oxide/poly(methyl
methacrylate)/ N-vinyl-2-pyrrolidone copolymer crosslinked with ethylene
glycol
dimethacrylate, and combinations thereof. While it is expected that in most
implementations the polymeric shape-memory material will be a cellular foam,
it
is also to be understood that other physical structures which are not cellular
foams, for instance an elastomer, may find use as the polymeric shape-
memory material. Of course, elastomers may also be cellular in some non-
limiting embodiments.
[0029] The methods described herein may be performed without the use of
or in the absence of a deployment fluid. The polymeric shape-memory material
may be recovered from its altered geometric position (in one non-limiting em-
bodiment a compressed position) at a certain temperature range or tempera-
ture window, for instance subjecting or exposing the polymeric shape-memory
material in its altered geometric position to a temperature within a range of
about 10 F (about -12 C) independently to about 150 F (about 66 C), alterna-
tively a range from about 15 F (about -9 C) independently to about 140 F
(60 C), in another non-restrictive version from about 20 F (-7 C)
independently
to about 130 F (54 C). The term "independently" as used herein with respect to
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a range means that any lower threshold may be used together with any upper
threshold to create a suitable alternative range for that parameter.
[0030] In an alternate embodiment, recovering the polymeric shape-memory
material from its altered geometric position (deployment) may occur when the
polymeric shape-memory material reaches a temperature within 10 F of its Tg,
alternatively within 7 F of its Tg, or in another non-limiting embodiment
within
5 F of its Tg.
[0031] In a different non-restrictive version, recovering the polymeric
shape-
memory material from its altered geometric position (deployment) may occur
when the polymeric shape-memory material is exposed to a heating device that
temporarily increases the temperature above the material Tg. Suitable heating
devices include, but are not necessarily limited to, catalytic chambers, such
as
those described in U.S. Pat. No. 7,708,073, assigned to Baker Hughes Incorpo-
rated; electrothermic heaters using wireline or electric submersible pump
(ESP)
cables, such as those utilized by Tyco Thermal Controls Co.; and the like.
Other suitable heating devices include, but are not necessarily limited to
those
involving microwave heating of the shape-memory material and/or the brine
with which it is contacted, such as described in U.S. Patent Application
Publica-
tion No. 2012/0012319 A and the like; as well as any devices involving exother-
mic reactions (other than combustion) such as galvanic corrosion of Mg powder
when a mixture of Mg/Fe powders is added to the brine, and the like; heating
of
conductive pipe on which the screen is mounted using inductive heater; and
heating using strontium sources as described in U.S. Pat. No. 8,127,840, and
the like.
[0032] Suitable optional deployment fluids include, but are not
necessarily
limited to water, brines, dimethyl sulfoxide, ketones, alcohols, glycols,
ethers,
hydrocarbons, and mixtures thereof. Specific examples of suitable polar fluids
include, but are not necessarily limited to, water, brines, methanol, ethanol,
isopropyl alcohol, ethylene glycol monobutyl ether (EGMBE), dimethyl sulfox-
ide, and acetone. Specific examples of suitable non-polar fluids include, but
are
not necessarily limited to, vegetable oils, mineral oil, LVT 200 oil, and
crude oil.
LVT 200 oil is described as hydrotreated distillate of light C9-16 containing
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cycloparaffinic, isoparaffinic, and normal paraffinic hydrocarbons available
from
Delta Drilling Products & Services, LLC. Generally, the more polar a fluid is,
the
more likely the fluid will serve as a deployment fluid, although nearly all
fluids
may exhibit some benefit as a deployment fluid, depending on the polymeric
shape-memory material being treated. It should be understood that the particu-
lar deployment fluid should not be a solvent for the polymeric shape-memory
material. That is, that the polymeric shape-memory material should not be
soluble in the deployment fluid to any appreciable extent.
[0033] The amount of the optional deployment fluid effective to affect the Tg
and/or the rigidity is a quantity sufficient to essentially saturate or soak
all of the
polymeric shape-memory material that is desired to be affected. Since it is
expected that in most embodiments the polymeric shape-memory material will
be an open cell foam, it may not be physically possible for the deployment
fluid
to infiltrate all of the cells, but at least 25 vol%, alternatively at least
50 vol%,
and even at least 90 vol% of the material may be contacted. In the event that
the polymeric shape-memory material is not a foam, or is instead a material
such as an elastomer which is non-cellular, it may be more difficult for the
deployment fluid to reach all of the polymer chains in the material. In non-
limiting embodiments, more time may be needed for the deployment fluid to be
more effective or the deployment fluid may need to be altered, for instance a
fluid having relatively smaller molecules to permit the polymer chain
structure to
be infiltrated.
[0034] One non-limiting theory about how the method and devices de-
scribed herein may operate may be seen with reference to FIGS. 3 and 4. As
shown in FIG. 3, polyurethane chains coupled via hydrogen bonding represent
the crystal structure of polyurethane and because the polyurethane chains are
more ordered and regular, the polymer chains are relatively parallel, the
crystal-
line polyurethane is more rigid. The mobility of polymer chains is limited,
there-
fore the material has higher Tg. However, if another substance is introduced,
for
instance an alcohol, ROH, serving as a deployment fluid, the hydrogen bonding
network between polyurethane chains is disrupted. The polymer chains are
decoupled from one another and relatively more mobile, therefore, the Tg of
the
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material is lower and the rigidity of the material is reduced, for instance to
a
second, lower Tg and a second, decreased rigidity, respectively.
[0035] It has been discovered that water alone cannot decrease the Tg of
the polycarbonate-polyurethane material significantly enough to deploy a
wellbore device at 115 F (46.1 C), for example. On the other hand, it has been
found that a EGMBE/Me0H/KCI brine deployment fluid can deploy a wellbore
device at this temperature. A non-limiting explanation is that a single water
molecule has a negatively charged oxygen and two positively charged hydro-
gen atoms. Therefore it can make two H-bonds simultaneously: in a first
scenario of one with the oxygen atom of carboxyl group of one polymer chain,
the other with an oxygen atom of a carboxyl group of a second polymer chain.
However, it may also have a second scenario of a hydrogen bond to one
carboxyl oxygen on a first polymer chain and a second hydrogen bond to a
hydrogen atom on a urethane link of a second polymer chain. Thus chains 1
and chain 2 are not very effectively decoupled since they are coupled via a
single water molecule. Note however that water molecules can also form H-
bonded chains between themselves. Therefore, there may be coupling such as:
Chain 1-water--water-Chain 2. This coupling via chains of water molecules
would not be expected to be strong.
[0036] Alternatively, ROH alcohols cannot form H-bonds with two chains
simultaneously via the first scenario described above, but may do so via the
second scenario. In another non-limiting embodiment, such coupling may occur
through a glycol or through a bridge such as: Chain 1-ROH-...-ROH-Chain 2,
but would not be expected to be a strong coupling. However, the alkyl portions
of alcohol molecules may serve as the spacers between the polymer chains
and decouple the chains more effectively than water alone. Therefore, the
polymer's Tg in alcohols or more complex (multi-component) deployment fluids
may be lower than that achieved in only water.
[0037] In a polyurethane-polycarbonate polymer, in one non-restrictive
version herein, there are many carboxyl oxygen atoms on the chain and fewer
hydrogen atoms of the urethane linkages. Thus, water molecules may make
many Chain 1-water-Chain 2 bridges, while alcohols ROH may make fewer
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Chain 1-ROH-Chain 2 bridges since there are relatively fewer hydrogen atoms
of polyurethane linkages on the chain compared to carboxyl oxygen atoms.
[0038] Deployment fluids which cannot disrupt the hydrogen bonding of the
polymer chains by engaging in hydrogen bonding themselves may still affect
the Tg and rigidity of the polymer chains by simply physically interfering or
coming between the hydrogen bonding sites of the adjacent polymer chains to
prevent or inhibit the chains from hydrogen bonding with each other. This non-
limiting understanding may help explain why non-polar materials such as
hydrocarbons, e.g. oils, can still lower Tg and reduce rigidity of the polymer
materials. It may thus be understood that there is roughly a spectrum of
useful
deployment fluids, where the more polar fluids have more of an effect and the
less polar fluids have less of an effect.
[0039] It should also be realized that the effect of the deployment fluid
is
reversible. That is, when the deployment fluid is removed, the Tg of the poly-
meric shape-memory material as well as the original rigidity are restored. As
a
practical matter, it is not possible to remove all of the deployment fluid
from the
polymeric shape-memory material once it has been contact thereby or even
saturated therewith. Since the polymeric shape-memory material is porous, and
in one beneficial embodiment is an open cell foam, it is simply physically
difficult to remove all of the deployment fluid once it is contacted with and
introduced into the foam. Thus, in one non-limiting embodiment "substantially
removing all of the deployment fluid" is defined herein as removing at least
90
volume % of the fluid, alternatively at least about 95 vol%, and in another
version at least 99 vol%. Of course, complete removal is a goal. In one method
described herein, substantially all of the deployment fluid is removed.
[0040] Thus, it may be understood that with substantially all of the deploy-
ment fluid is removed from the polymeric shape-memory material, the effects
may be restoring the Tg to within at least 90% of the original Tg and/or
restoring
the rigidity within at least 25% of the original rigidity. Alternatively, the
Tg is
restored to within at least 95% of the original Tg and/or the rigidity is
restored to
within at least 50% of the original rigidity. In another non-restrictive
version, the
Tg is restored to within at least 99% of the original Tg and/or the rigidity
is
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restored to within at least 90% of the original rigidity. Of course, complete
resto-
ration of these properties is desirable. Rigidity may be restored when, in a
non-
limiting example, the alcohol ROH is removed from the schematic structure
shown in FIG. 4 and the hydrogen bonding between the polymer chains is
restored, as schematically shown in FIG. 3.
[0041] In one non-limiting embodiment, an optional surfactant may be used
to help recover a deployment fluid from the polymeric shape-memory material.
Suitable surfactants when the deployment fluid being removed include a polar
fluid such as water, brines, dimethyl sulfoxide, ketones, alcohols, glycols
and
ethers may include, but not necessarily limited to, anionic, cationic,
amphoteric,
and non-ionic surfactants. Suitable surfactants when the deployment fluid
being
removed is a non-polar fluid such as an oil, e.g. a plant oil, for instance,
olive oil
or sunflower oil, may include, but not necessarily limited to, anionic,
cationic,
amphoteric, and non-ionic surfactants
[0042] The method described herein may have considerable benefit. In one
non-limiting example, a single wellbore device product having only one type of
polymeric shape-memory material may be used in a variety of applications
requiring deployment of the polymeric shape-memory material from its altered
geometric position to a recovered geometric position at different Tgs simply
by
contacting, soaking or saturating the polymeric shape-memory material in its
altered geometric position in a suitable different deployment fluid designed
to
alter its Tg in different amounts. Alternatively, the deployment fluid may be
subsequently completely removed, or in another non-restrictive version, the
method may be practiced in the absence of a deployment fluid where on a
certain temperature window or range deploys the polymeric shape-memory
material from its altered or compressed geometric state or position.
[0043] In one specific non-limiting embodiment, the shape-memory material
is a polyurethane material that is extremely tough and strong and that is capa-
ble of being geometrically altered and returned to substantially its original
geometric shape. The Tg of the shape-memory polyurethane foam may range
from about 40 C to about 200 C and it is geometrically altered by mechanical
force at 40 C to 190 C. While still in geometrically altered state, the
material
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may be cooled down to room temperature or some other temperature below the
Tg of each shape-memory material. The shape-memory polyurethane is able to
remain in the altered geometric state even after applied mechanical force is
removed. However, as described herein, the polymeric shape-memory material
in its altered geometric state may be contacted, saturated or soaked in a
deployment fluid which alters its Tg, generally lowering it. When the com-
pressed polymeric shape-memory material is heated to above its reduced or
modified onset Tg, it is able to return to its original shape, or close to its
original
shape. The time required for geometric shape recovery can vary from about 20
minutes to 40 hours or longer depending on the slope of the transition curves
as the material moves from a glass state to a rubber state. If the material
remains below the altered or lowered onset Tg it remains in the geometrically
altered state and does not change its shape.
[0044] In one non-limiting embodiment, when shape-memory polyurethane
is used as a downhole device, the device remains in an altered geometric state
during run-in until it reaches to the desired downhole location. Usually, down-
hole tools traveling from surface to the desired downhole location take hours
or
days. Thus, it may be helpful to match the altered onset Tgs of the material
with
the expected downhole temperatures. The deployment fluids described herein
help the designer prevent premature deployment of the polymeric shape-
memory material and control when and where deployment occurs, thus permit-
ting flawless implementation and deployment of the wellbore device.
[0045] In some non-limiting embodiments, when the temperature is high
enough during run-in, the devices made from the shape-memory polyurethane
could start to recover. To avoid undesired early recovery during run-in,
delaying
methods may or must be taking into consideration. In previous non-limiting
embodiments, a poly(vinyl alcohol) (PVA) film or other suitable film may be
used to wrap or cover the outside surface of devices made from shape-memory
polyurethane to prevent recovery during run-in. Once devices are in place
downhole for a given amount of time at temperature, the PVA film is capable of
being dissolved in the water, emulsions or other downhole fluids and, after
such
exposure, the shape-memory devices may recover to their original geometric
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shape or conform to the bore hole or other space. However, the apparatus and
methods described herein instead prevent undesired early recovery of the
polymeric shape-memory material by contacting, soaking or enveloping the
material in a deployment fluid that alters the Tg sufficiently to help inhibit
or
prevent premature deployment.
[0046] In one non-limiting embodiment, a downhole tool may have a well-
bore device that is a polymeric shape-memory material as described herein
which may be designed to permit fluids, but not fines or other solids to pass
through, such as a screen. In a different non-restrictive version, the
polymeric
shape-memory material may be designed to prevent fluids as well as solids
from passing therethrough, in which case the tool is a packer or other
isolation
device. In these and other such embodiments, the recovered geometric posi-
tion of the polymeric shape-memory material may be to totally conform to the
available space between the wellbore device and the borehole wall or casing.
When it is described herein that a device "totally conforms" to the borehole,
what is meant is that the shape-memory material recovers or deploys to fill
the
available space up to the borehole wall. The borehole wall will limit the
final,
recovered shape of the shape-memory material and in fact not permit it to
expand to its original, geometric shape. In this way however, the recovered or
deployed shape-memory material, will perform the desired function within the
wellbore. In summary, suitable wellbore devices used on the apparatus or in
the methods described herein include, but are not necessarily limited to an
expansion took a screen, a packer, and an isolation plug.
[0047] The invention will now be described with respect to certain specific
examples which are not intended to limit the invention in any way but simply
to
more fully illuminate it.
EXAMPLE 1
[0048] The effect of polar and non-polar deployment fluids on the deploy-
ment of the memory-shape polymer foam-based expandables is shown in FIG.
5. Two cylindrical samples of polyurethane-polycarbonate rigid open-cell foam
(h = 4 mm, d = 7 mm) were immersed into vegetable oil and water at 65 C and
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compacted to 35.2% and 39.4% of their original height, respectively. After the
compressive loads on samples were removed, the sample immersed in the
vegetable oil expanded to 39.9% of its original height within 21 seconds and
then further expanded to only 40.9% of its original height during the next
2468
minutes, while the sample immersed in water rapidly expanded to 50.8% of its
original height within 62 seconds and then gradually expanded further to 67.2%
of its original height during the next 2500 minutes. Note that the initial
rapid
expansion of the foam samples reflects an elastic response of the foam to the
compressive load removal and can be avoided if the pre-compacted samples
are immersed into the liquid to deploy. Therefore, the foam sample immersed
in the vegetable oil was effectively "frozen" at 65 C, while the sample
immersed
in the water was able to continually expand with a decreasing rate as a
function
of time at the same temperature. Thus, this experiment shows that a com-
pacted polyurethane/polycarbonate foam-based expandable element can be
safely transported downhole and installed at the temperatures less than at
least
65 C if the vvellbore is circulated with an oil-based liquid. Replacement of
the
oil-based circulating fluid with a water-based liquid would trigger the deploy-
ment of the expendables at the same temperature. This experiment also shows
that the onset temperature for the deployment of a foam-based element
immersed in the water is lower than 65 C.
EXAMPLE 2
[0049] In this particular case of a polycarbonate-polyurethane memory-
shape foam material, it is believed that the relatively light and mobile water
molecules form hydrogen bonds with the negatively charged oxygen atoms of
polycarbonate chains and the positively charged hydrogen atoms of urethane
(carbamate) links inducing their motion and likely acting as an "internal
lubri-
cant" between the polymer chains, as previously discussed. A comprehensive
molecular-level understanding of interactions of water molecules with polymer
chains may be provided by the Molecular Dynamics simulations, described by
Tamar Schlick in "Molecular Modeling and Simulation", Springer-Verlag, New
York, 2002.
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[0050] This phenomenon effectively reduces a glass transition temperature,
Tg, of the polyurethaneipolycarbonate foam immersed in the water in compari-
son with Tg of the same material immersed in vegetable oil by a ATg of about -
17 C, as seen in FIG. 6. FIG. 6 is a graph of the storage (E) and loss (E')
moduli of the polymeric shape-memory material samples immersed in oil and
water as functions of the temperature. The glass transition temperature of the
polymer immersed in liquid (Tg) corresponds to the peak value of the loss
modulus E" and indicates that the Tg is about 17 C lower when water is used
as compared to when oil is used. Please also note the shift to the left of the
storage modulus E' curve when water is used compared to when the oil is
employed.
[0051] Hence, the water acts as a deploying or activating agent on the
polymer foam while the vegetable oil does not display as significant Tg reduc-
tion and "lubricating" (rigidity reduction) properties. Therefore, by
replacing a
non-polar (hydrocarbon) wellbore circulating fluid which does not have rela-
tively large Tg-reducing properties with a relatively more Tg-reducing ability
fluid
contacting the polymer foam material, the onset temperature for the deploy-
ment of the memory-shape polymer foam-based expandables may be reduced.
In one non-limiting implementation, the deployment onset temperature may be
kept high during the transportation downhole and the installation procedures.
Then the T0 may be lowered by replacing the oil-based circulating fluids with
the water-based ones to actuate the deployment of the expandables. It should
be noted that the variety of possible deployment fluids is wide, and the water
and the vegetable oil are used only as examples.
EXAMPLE 3
[0052] As shown in FIG. 7, by changing the temperature of the circulating
liquid, it is possible to control both the rate and the extent of the
deployment of
the memory-shape polymer foam-based expandables. As shown in FIG. 7,
increasing the temperature increases the rate as well as the extent of the
expandables' deployment. It should be noted that this effect holds for the
foam
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immersed in both the more polar deployment fluids and the non-polar deploy-
ment fluids.
EXAMPLE 4
[0053] The following data support the understanding that a polar deploy-
ment fluid which decreases Tg of the material relatively more than a non-polar
fluid is also more effective for reducing the deployment time of the totally
con-
formable sand screen (TCS). In this Example the TCS was a polyurethane/-
polycarbonate foam.
[0054] The TCS material before contact with the activation fluid has a Tg in
3% KCI solution of 71 C. After its immersion in activation fluids at 115 F
for 72
hours, the Tgs in 3% KCI solution are as shown in Table I.
TABLE I
Tg of the Material in 3% KCI Solution after Deployment
Using Various Blends of EGMBE and Me0H
Deployment Fluid Composition T 'C
None (Tg of Material before Compaction and Deployment) 71
4% volume Ethylene Glycol Monobutyl Ether (EGMBE) 25% 44.1
volume CH3OH and 8.9 ppg KCI
5% volume EGMBE 25% volume CH3OH and 8.9 ppg KCI 38.9
6% volume EGMBE 25% volume CH3OH and 8.9 ppg KCI 32.6
[0055] The results of Table I are plotted in FIG. 8. It may be seen that the
Tg
of the material decreases as the EGMBE content in the activation fluid
increases.
[0056] FIG. 9 shows that the higher the content of EGMBE in the deploy-
ment fluid, the less time it takes to deploy the TCS to gauge hole diameter.
In
the deployment experiments, the deployment fluids and corresponding
deployment times were as shown in Table II. It thus may be seen that the
deployment fluid which reduces Tg more also reduces the deployment time
more.
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TABLE II
Deployment Times for Various Deployment Fluid Compositions
Fluid Composition Deployment Time, hr
3% EGMBE 25% CH3OH and 8.9 ppg KCI 22
4% EGMBE 25% CH3OH and 8.9 ppg KCI 22 (1st test)
27 (2nd test)
5% EGMBE 25% CH3OH and 8.9 ppg KCI 17
7.5% EGMBE 25% CH3OH and 8.9 ppg KCI 7 (1st test)
8 (2nd test)
14 (31d test)
[0057] 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 ap-
pended claims. Further, the specification is to be regarded in an illustrative
rather than a restrictive sense. For example, specific combinations of compo-
nents to make the polymeric shape-memory materials, particular Tgs, particular
deployment fluids used, particular temperature ranges, particular heating
devices, specific downhole tool configurations, designs and other
compositions,
components and structures falling within the claimed parameters, but not
specifically identified or tried in a particular method or apparatus, are
antici-
pated to be within the scope of this invention.
[0058] The terms "comprises" and "comprising" in the claims should be
interpreted to mean including, but not limited to, the recited elements. For
instance, a wellbore device within the descriptions herein may consist of or
consist essentially of at least one polymeric shape-memory material and a
deployment fluid as defined by the claims. Similarly, a method of installing a
wellbore device on a downhole tool in a wellbore may consist of or consist
essentially of introducing the downhole tool bearing the wellbore device into
a
wellbore where the polymeric shape-memory material is contacted by a first
fluid, substantially removing the first fluid, contacting the polymeric shape-
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memory material with a deployment fluid and recovering the polymeric shape-
memory material from its altered geometric position for run-in to a recovered
geometric position as further specified in the claims. This method may also
consist of or consist essentially of removing the deployment fluid.
[0059] The method herein installing a wellbore device on a downhole tool in
a wellbore may consist essentially of or consist of introducing the downhole
tool
bearing the wellbore device into a wellbore, where the wellbore device com-
prises at least one polymeric shape-memory material having an original glass
transition temperature (Tg) and an original rigidity, where the polymeric
shape-
memory material is in an altered geometric position and the polymeric shape-
memory material is contacted by a brine or oil; and recovering the polymeric
shape-memory material from its altered geometric position, in the absence of a
deployment fluid, upon the occurrence of an event including, but not neces-
sarily limited to (1) the polymeric shape-memory material reaching a tempera-
ture between about 10 F to about 150 F, (2) the polymeric shape-memory
material reaching a temperature within 10 F of its Tg, and/or (3) the
polymeric
shape-memory material being exposed to a heating device that increases the
temperature above the material Tg. Optionally the wellbore device has the
property that when the polymeric shape-memory material is recovered from its
altered geometric position, an effect is obtained selected from the group
consisting of restoring the Tg to within at least about 90% of the original
Tg,
restoring the rigidity within at least about 25% of the original rigidity, and
both.
[0060] The present invention may suitably comprise, consist or consist
essentially of the elements disclosed and may be practiced in the absence of
an element not disclosed.
