U.S. patent application number 12/961333 was filed with the patent office on 2011-03-31 for cement compositions comprising a high-density particulate elastomer and associated methods.
Invention is credited to Joseph K. Maxson, Krishna M. Ravi, Ashok K. Santra.
Application Number | 20110077324 12/961333 |
Document ID | / |
Family ID | 40533061 |
Filed Date | 2011-03-31 |
United States Patent
Application |
20110077324 |
Kind Code |
A1 |
Ravi; Krishna M. ; et
al. |
March 31, 2011 |
CEMENT COMPOSITIONS COMPRISING A HIGH-DENSITY PARTICULATE ELASTOMER
AND ASSOCIATED METHODS
Abstract
A variety of methods and compositions, including, in one
embodiment, a method of treating a subterranean formation
comprising introducing a treatment fluid into a well bore, wherein
the treatment fluid comprises a particulate elastomer having a
specific gravity of at least about 1.6. Another method of treating
a subterranean formation comprises introducing a treatment fluid
into a well bore, wherein the treatment fluid comprises a
particulate elastomer having a specific gravity of at least about
1.05, wherein the particulate elastomer comprises a halogenated
thermoplastic.
Inventors: |
Ravi; Krishna M.; (Kingwood,
TX) ; Maxson; Joseph K.; (Duncan, OK) ;
Santra; Ashok K.; (Duncan, OK) |
Family ID: |
40533061 |
Appl. No.: |
12/961333 |
Filed: |
December 6, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12206229 |
Sep 8, 2008 |
7878245 |
|
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12961333 |
|
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60978951 |
Oct 10, 2007 |
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Current U.S.
Class: |
523/130 |
Current CPC
Class: |
C04B 24/2682 20130101;
C09K 8/48 20130101; C09K 8/467 20130101; C09K 8/40 20130101; C04B
14/06 20130101; C04B 24/2682 20130101; C04B 2103/22 20130101; C04B
2103/46 20130101; C04B 2103/0049 20130101; C04B 2103/408 20130101;
C04B 38/10 20130101; C04B 28/04 20130101; C04B 28/04 20130101 |
Class at
Publication: |
523/130 |
International
Class: |
C09K 8/42 20060101
C09K008/42 |
Claims
1. A cement composition comprising cement, water, and a particulate
elastomer having a specific gravity of at least about 1.6, wherein
the particulate elastomer comprises at least one thermoplastic
selected from the group consisting of: a fluorinated polymer of
ethylene and propylene; a polymer of tetrafluoroethylene and
perfluorovinylether; a polymer of tetrafluoroethylene and ethylene;
a polymer of tetrafluoroethylene and hexafluoropropylene; a polymer
of vinylidene fluoride; a polymer of tetrafluoroethylene,
hexafluoropropylene, and vinylidene fluoride; perfluoroalkoxy
polymer resin; chlorotrifluoroethylene; fluorinated
ethylene-propylene; polyethylenetetrafluoroethylene;
polyvinylfluoride; polyethylenechlorotrifluoroethylene;
polyvinylidene fluoride; polychlorotrifluoroethylene; a
perfluoroelastomer; a fluoro-carbon elastomer; polyamide imide;
polyetherether ketone; polyphenylene sulfide; polyetherketone; and
any combination thereof.
2. The cement composition of claim 1 wherein the cement comprises a
hydraulic cement.
3. The cement composition of claim 1 wherein the particulate
elastomer has a specific gravity of at least about 2.0.
4. The cement composition of claim 1 wherein the particulate
elastomer comprises a halogenated thermoplastic.
5. The cement composition of claim 1 wherein the particulate
elastomer comprises a fluoroplastic.
6. The cement composition of claim 1 wherein the particulate
elastomer is present in the cement composition in an amount of
about 0.5% to about 50% by weight of the cement.
7. The cement composition of claim 1 wherein the particulate
elastomer has a particle size of about 5 microns to about 1,500
microns.
8. The cement composition of claim 1 further comprising a swellable
elastomer.
9. The cement composition of claim 1 wherein the cement composition
is foamed.
10. A cement composition comprising cement, water, and a
particulate elastomer having a specific gravity of at least about
1.05, wherein the particulate elastomer comprises a halogenated
thermoplastic selected from the group consisting of: a fluorinated
polymer of ethylene and propylene; a polymer of tetrafluoroethylene
and perfluorovinylether; a polymer of tetrafluoroethylene and
ethylene; a polymer of tetrafluoroethylene and hexafluoropropylene;
a polymer of vinylidene fluoride; a polymer of tetrafluoroethylene,
hexafluoropropylene, and vinylidene fluoride; perfluoroalkoxy
polymer resin; chlorotrifluoroethylene; fluorinated
ethylene-propylene; polyethylenetetrafluoroethylene;
polyvinylfluoride; polyethylenechlorotrifluoroethylene;
polyvinylidene fluoride; polychlorotrifluoroethylene; a
perfluoroelastomer; a fluoro-carbon elastomer; and any combination
thereof.
11. The cement composition of claim 10 wherein the particulate
elastomer has a specific gravity of at least about 2.0.
12. The cement composition of claim 10 wherein the halogenated
thermoplastic comprises a fluoroplastic.
13. The cement composition of claim 10 wherein the particulate
elastomer has a particle size of about 5 microns to about 1,500
microns.
14. The cement composition of claim 10 further comprising a
swellable elastomer.
15. A cement composition comprising cement, water, and a
particulate elastomer comprising a polymer of tetrafluoroethylene
and perfluorovinylether.
16. The cement composition of claim 15 wherein the particulate
elastomer has a specific gravity of at least about 1.05.
17. The cement composition of claim 15 wherein the particulate
elastomer has a particle size of about 5 microns to about 1,500
microns.
18. The cement composition of claim 15 wherein the particulate
elastomer is present in the cement composition in an amount of
about 0.5% to about 50% by weight of the cement.
19. The cement composition of claim 18 wherein the cement
composition further comprises a swellable elastomer.
20. The cement composition of claim 19 wherein the swellable
elastomer is present in the cement composition in an amount of
about 0.5% to about 50% by weight of the cement.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of U.S.
application Ser. No. 12/206,229, filed on Sep. 8, 2008, which
claims the benefit of U.S. Provisional Application No. 60/978,951,
entitled "Cement Compositions Comprising a High-Density Particulate
Elastomer and Associated Methods," filed on Oct. 10, 2007, the
entire disclosures of which are incorporated herein by
reference.
BACKGROUND
[0002] The present invention relates to subterranean treatment
fluids and associated methods. More specifically, in certain
embodiments, the present invention relates to cement compositions
that comprise a particulate elastomer having a specific gravity of
at least about 1.05 and associated methods.
[0003] Cement compositions are one type of subterranean treatment
fluid that may be used in a variety of subterranean applications.
For example, in subterranean well construction, a pipe string
(e.g., casing, liners, expandable tubulars, etc.) may be run into a
well bore and cemented in place. The process of cementing the pipe
string in place is commonly referred to as "primary cementing." In
a typical primary cementing method, a cement composition may be
pumped into an annulus between the walls of the well bore and the
exterior surface of the pipe string disposed therein. The cement
composition sets in the annular space, thereby forming an annular
sheath of hardened, substantially impermeable cement (i.e., a
cement sheath) that may support and position the pipe string in the
well bore and may bond the exterior surface of the pipe string to
the subterranean formation. Among other things, the cement sheath
surrounding the pipe string functions to prevent the migration of
fluids in the annulus, as well as protecting the pipe string from
corrosion. Cement compositions also may be used in remedial
cementing methods, for example, to seal cracks or holes in pipe
strings or cement sheaths, to seal highly permeable formation zones
or fractures, to place a cement plug, and the like. Cement
compositions also may be used in surface applications, for example,
construction cementing.
[0004] Once set, the cement sheath may be subjected to a variety of
cyclic, shear, tensile, impact, flexural, and/or compressive
stresses that may lead to failure of the cement sheath, resulting,
for example, in fractures, cracks, and/or debonding of the cement
sheath from the pipe string and/or the formation. This may lead to
undesirable consequences such as lost production, environmental
pollution, hazardous rig operations resulting from unexpected fluid
flow from the formation caused by the loss of zonal isolation,
and/or hazardous production operations. Furthermore, failure of the
cement sheath also may be caused by forces exerted by shifts in
subterranean formations surrounding the well bore, cement erosion,
and repeated impacts from the drill bit and the drill pipe.
[0005] To counteract these problems, various additives may be
included in the cement composition to enable the cement composition
to withstand cyclic changes in imposed stresses. For example,
hydrocarbon-based elastomers (e.g., styrene-butadiene random and
block copolymers, acrylonitrile-butadiene, and
acrylonitrile-styrene-butadiene elastomers) have been included in
cement compositions to modify the mechanical and expansion
properties of the cement composition. Generally, such materials are
used in the particulate form. As used herein, the term
"particulate" refers to materials in solid state having a
well-defined physical shape as well as those with irregular
geometries, including any particulates elastomers having the
physical shape of platelets, shavings, fibers, flakes, ribbons,
rods, strips, spheroids, hollow beads, toroids, pellets, tablets,
or any other physical shape. Among other things, the particulate
elastomers may function to control shrinkage cracking in the early
stages of the cement setting process, and also may provide
resiliency, ductility, expansion, and toughness to the set cement
composition (e.g., the cement sheath) so that it resists and seals
cracking or fracturing.
[0006] The use of particulate elastomers in cement compositions,
however, may be problematic. For example, particulate elastomers
used heretofore generally have a density equal to or less than
water. Accordingly, these particulate elastomers may be
particularly suited for use in lower-density cement compositions.
These low-density particulate elastomers have also been used in
higher-density cement compositions (e.g., greater than about 15
pounds per gallon), as no suitable higher-density particulate
elastomers have been available. However, when used in the
higher-density cement compositions, heavyweight additives may need
to be used to compensate for the low-density particulate
elastomers. The concentration of the heavyweight additives that may
be needed to compensate for the low-density particulate elastomers,
however, may undesirably affect certain properties of the cement
compositions, such as its mixability and rheology.
SUMMARY
[0007] The present invention relates to subterranean treatment
fluids and associated methods. More specifically, in certain
embodiments, the present invention relates to cement compositions
that comprise a particulate elastomer having a specific gravity of
at least about 1.05 and associated methods.
[0008] In one embodiment, the present invention provides a method
of treating a subterranean formation comprising: introducing a
treatment fluid into a well bore, wherein the treatment fluid
comprises a particulate elastomer having a specific gravity of at
least about 1.6.
[0009] In one embodiment, the present invention provides a method
of treating a subterranean formation comprising: introducing a
treatment fluid into a well bore, wherein the treatment fluid
comprises a particulate elastomer having a specific gravity of at
least about 1.05, wherein the particulate elastomer comprise a
halogenated thermoplastic.
[0010] In one embodiment, the present invention provides a
treatment fluid comprising a particulate elastomer having a
specific gravity of at least about 1.6.
[0011] In one embodiment, the present invention provides a
treatment fluid comprising a particulate elastomer having a
specific gravity of at least about 1.05, wherein the particulate
elastomer comprises a halogenated thermoplastic.
[0012] The features and advantages of the present invention will be
readily apparent to those skilled in the art. While numerous
changes may be made by those skilled in the art, such changes are
within the spirit of the invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0013] The present invention relates to subterranean treatment
fluids and associated methods. More specifically, in certain
embodiments, the present invention relates to cement compositions
that comprise a particulate elastomer having a specific gravity of
at least about 1.05 and associated methods. As used herein, a
particulate elastomer having a specific gravity of at least about
1.05 will be referred to as a "high-density particulate
elastomer."
[0014] In some embodiments, the cement compositions of the present
invention generally comprise cement, water, and a high-density
particulate elastomer. Those of ordinary skill in the art will
appreciate that the cement compositions of the present invention
generally should have a density suitable for a particular
application. By way of example, the cement compositions of the
present invention may have a density in the range of about 4 pounds
per gallon ("lb/gal") to about 24 lb/gal. In certain embodiments,
the cement compositions of the present invention have a density in
the range of about 8 lb/gal to about 19 lb/gal. Embodiments of the
cement compositions may be foamed or unfoamed or may comprise other
means to reduce their densities, such as hollow microspheres,
low-density elastic beads, or other density-reducing additives
known in the art. In addition, embodiments of the cement
composition may comprise heavyweight additives (e.g., hematite,
magnesium oxide, etc.). However, as discussed in more detail below,
the need for the heavyweight additives to achieve a particular
density may be reduced, or potentially eliminated, when using the
high-density particulate elastomer as compared to a low-density
particulate elastomer. One of ordinary skill in the art with the
benefit of this disclosure will recognize the appropriate density
of the cement composition for a chosen application.
[0015] Any cement suitable for use in subterranean applications may
be suitable for use in the present invention. In certain
embodiments, the cement compositions of the present invention
comprise a hydraulic cement. Suitable examples of hydraulic cements
that may be used include, but are not limited to, those that
comprise calcium, aluminum, silicon, oxygen, and/or sulfur, which
set and harden by reaction with water. Examples include, but are
not limited to, Portland cements, pozzolanic cements, gypsum
cements, calcium-phosphate cements, high-alumina-content cements,
silica cements, high-alkalinity cements, and mixtures thereof.
[0016] The water utilized in the cement compositions of the present
invention may be fresh water, salt water (e.g., water containing
one or more salts dissolved therein), brine (e.g., saturated salt
water), or seawater. Generally, the water may be from any source,
provided that it should not contain an excess of compounds that may
adversely affect other components in the cement composition.
Further, the water may be present in an amount sufficient to form a
pumpable slurry. In certain embodiments, the water is present in
the cement composition in an amount in the range of about 30% to
about 180% by weight of the cement ("bwoc") therein. In certain
embodiments, the water is present in the cement composition in the
range of about 40% to about 90% bwoc. In certain embodiments, the
water is present in the cement composition in the range of about
40% to about 60% bwoc. One of ordinary skill in the art with the
benefit of this disclosure will recognize the appropriate amount of
water for a chosen application.
[0017] The cement compositions of the present invention further
comprise a high-density particulate elastomer. Among other things,
it is believed that the high-density particulate elastomer should
generally provide the set cement composition a lower Young's
modulus, higher recoverable elongation, greater
resilience/toughness without unduly compromising its compressive
strength. Accordingly, the set cement composition, at least in some
instances, should be more able to withstand the stresses
encountered in a downhole environment that may, for example, lead
to failure of a cement sheath. Moreover, the high-density
particulate elastomer included in the cement compositions of the
present invention is generally heavier than the particulate
elastomers used heretofore, in that the particulate elastomers used
heretofore generally have a density equal to or less than water,
i.e., a specific gravity of about 1.0. Of their many potential
advantages, one such advantage of using the high-density
particulate elastomer is that the need for heavyweight additives
may be reduced or even eliminated. As such, the mixability and
rheology issues associated with heavyweight additives may be
reduced or even eliminated.
[0018] As previously mentioned, the high-density particulate
elastomer included in the cement compositions of the present
invention has a specific gravity of at least about 1.05. In certain
embodiments, the high-density particulate elastomer may have a
specific gravity of at least about 1.1 (e.g., about 1.2, about 1.3,
about 1.4, about 1.5, about 1.6, about 1.7, about 1.8, about 1.9,
about 2.0, about 2.1, about 2.2, etc.). In certain embodiments, the
high-density particulate elastomer may have a specific gravity of
at least about 1.6. In certain embodiments, the high-density
particulate elastomer may have a specific gravity of at least about
2.0. In one particular embodiment, the high-density particulate
elastomer may have a specific gravity of about 2.15. As will be
appreciated, as the specific gravity of the particulate elastomer
used increases, the amount of the heavyweight additive that may be
needed to prepare a cement composition of a particular density
decreases.
[0019] Any of a variety of high-density particulate elastomers
having a specific gravity of at least about 1.05 may be included in
the cement compositions of the present invention. Examples of
suitable high-density particulate elastomers include, but are not
limited to, particulate elastomers that comprise a thermoplastic.
Examples of suitable thermoplastics include, but are not limited
to, halogenated thermoplastics, such as fluoroplastics.
Thermoplastics that do not comprise fluorine atoms may also be
suitable for use, in certain embodiments. In general,
fluoroplastics may be characterized by their high chemical
resistance, for example, it is believed that the fluoroplastics do
not degrade in a carbon dioxide environment. As such, the
fluoroplastics generally should undergo negligible, if any,
swelling when exposed to fluids (e.g., brines, hydrocarbons, etc.)
downhole. Furthermore, fluoroplastics may be suitable for use in
carbon sequestration applications. In addition, fluoroplastics
generally may be characterized by their temperature stability. For
example, fluoroplastics generally may retain their structural
integrity at temperatures in excess of 600.degree. F. Accordingly,
while the fluoroplastics are suitable for use in applications
having a wide variety of temperatures, they may be particularly
suitable for use in high-temperature applications, such as those
having a bottom hole circulating temperature ("BHCT") greater than
about 600.degree. F.
[0020] Fluoroplastics that are suitable for use in embodiments of
the cement compositions of the present invention generally include
thermoplastic polymers that comprise fluorine atoms. Examples of
suitable fluoroplastics include, but are not limited to:
fluorinated polymers of ethylene and propylene; polymers of
tetrafluoroethylene and perfluorovinylether; polymers of
tetrafluoroethylene and ethylene; polymers of tetrafluoroethylene
and hexafluoropropylene; polymers of vinylidene fluoride; polymers
of tetrafluoroethylene, hexafluoropropylene, and vinylidene
fluoride; polytetrafluoroethylene (PTFE); perfluoroalkoxy polymer
resin (PFA); chlorotrifluoroethylene (CTFE); fluorinated
ethylene-propylene (FEP); polyethylenetetrafluoroethylene (ETFE);
polyvinylfluoride (PVF); polyethylenechlorotrifluoroethylene
(ECTFE); polyvinylidene fluoride (PVF); polychlorotrifluoroethylene
(CTFE); perfluoroelastomers (FFKM); fluoro-carbon elastomers
(FPM/FKM). Combinations of suitable fluoroplastics may also be
used. Examples of suitable fluoroplastics are available from:
Dyneon, a 3M company, under the brandname DYNEON.TM. fluorpolymers;
from Dupont, under the brandnames VITON.RTM. fluoropolymers,
TEFZEL.RTM. fluoropolymer resin, KALREZ.RTM. FFKM, and TEDLAR.RTM.
polyvinly fluoride; Solvay Solexis, under the brandnames
TECNOFLON.RTM. fluoropolymers and HALAR.RTM. ECTFE; Arkema Inc.,
under the brandname KYNAR.RTM. PVDF; Daikin America, Inc. under the
brandname NEOFLON.RTM. fluoropolymers.
[0021] As set forth above, thermoplastics that do not comprise
fluorine atoms may be also be suitable for use in certain
embodiments. Examples of suitable thermoplastics that do not
comprise fluorine atoms, include, but are not limited to, polyamide
imide (PAD, polyetherether ketone (PEEK), polyphenylene sulfide
(PPS), polyetherketone (PEK), and combinations thereof.
[0022] The high-density particulate elastomer generally should be
present in the cement compositions of the present invention in an
amount sufficient to provide the desired mechanical properties,
such as, for example, resiliency, compressive strength, and tensile
strength. In some embodiments, the high-density particulate
elastomer may be present in the cement compositions of the present
invention in an amount from about 0.5% to about 50% bwoc,
alternatively from about 1% to about 20% bwoc, and alternatively
from about 4% to about 15% bwoc.
[0023] In addition, the high-density particulate elastomer present
in the cement compositions of the present invention may have a wide
variety of shapes and sizes of individual particles suitable for
use in the cement compositions of the present invention. By way of
example, the high-density particulate elastomers may have
well-defined physical shapes as well as irregular geometries,
including the physical shape of platelets, shavings, fibers,
flakes, ribbons, rods, strips, spheroids, hollow beads; toroids,
pellets, tablets, or any other physical shape. In some embodiments,
the high-density particulate elastomer may have a particle size in
the range of about 5 microns to about 1,500 microns. In some
embodiments, the high-density particulate elastomer may have a
particle size in the range of about 20 microns to about 500
microns. However, particle sizes outside these defined ranges also
may be suitable for particular applications.
[0024] The cement compositions of the present invention further may
comprise a swellable elastomer. As used herein, an elastomer is
characterized as swellable when it swells upon contact with an
oleaginous and/or an aqueous fluid, such as water. Among other
things, the inclusion of a swellable elastomer may help to provide
zonal isolation, for example, by swelling to seal the annulus if
any oleaginous or aqueous fluids flow through any cracks and/or
micro-annulus that may be created in the cement sheath during well
operations.
[0025] Swellable elastomers suitable for use in the cement
compositions of the present invention may generally swell by up to
about 500% of their original size at the surface. Under downhole
conditions, this swelling may be more or less depending on the
conditions presented. For example, the swelling may be at least 10%
at downhole conditions. In some embodiments, the swelling may be up
to about 200% under downhole conditions. However, as those of
ordinary skill in the art, with the benefit of this disclosure,
will appreciate, the actual swelling when the swellable elastomer
is included in a cement composition may depend on, for example, the
concentration of the swellable elastomer included in the cement
composition. In general, the swellable elastomers included in the
cement compositions of the present invention have a specific
gravity of about 1.0. Some specific examples of suitable elastomers
that swell upon contact with an oleaginous fluid and/or an aqueous
fluid include, but are not limited to, natural rubber, acrylate
butadiene rubber, polyacrylate rubber, isoprene rubber,
choloroprene rubber, butyl rubber (IIR), brominated butyl rubber
(BIIR), chlorinated butyl rubber (CIIR), chlorinated polyethylene
(CM/CPE), neoprene rubber (CR), styrene butadiene copolymer rubber
(SBR), sulphonated polyethylene (CSM), ethylene acrylate rubber
(EAM/AEM), epichlorohydrin ethylene oxide copolymer (CO, ECO),
ethylene-propylene rubber (EPM and EDPM), ethylene-propylene-diene
terpolymer rubber (EPT), ethylene vinyl acetate copolymer,
fluorosilicone rubbers (FVMQ), silicone rubbers (VMQ), poly
2,2,1-bicyclo heptene (polynorborneane), alkylstyrene, crosslinked
substituted vinyl acrylate copolymers and diatomaceous earth.
Examples of suitable elastomers that swell when in contact with
aqueous fluid include, but are not limited to, nitrile rubber
(NBR), hydrogenated nitrile rubber (HNBR, FINS), fluoro rubbers
(FKM), perfluoro rubbers (FFKM), tetrafluorethylene/propylene
(TFE/P), starch-polyacrylate acid graft copolymer, polyvinyl
alcoholcyclic acid anhydride graft copolymer, isobutylene maleic
anhydride, acrylic acid type polymers, vinylacetate-acrylate
copolymer, polyethylene oxide polymers, carboxymethyl cellulose
type polymers, starch-polyacrylonitrile graft copolymers and the
like, polymethacrylate, polyacrylamide, and non-soluble acrylic
polymers. Combinations of suitable swellable elastomer may also be
used. One example of a suitable swellable elastomer includes WELL
LIFE.TM. 665 additive, available from Halliburton Energy Services,
Inc., Duncan, Okla. Other swellable materials that behave in a
similar fashion with respect to oleaginous fluids or aqueous fluids
also may be suitable. Those of ordinary skill in the art, with the
benefit of this disclosure, will be able to select an appropriate
swellable elastomer for use in the compositions of the present
invention based on a variety of factors, including the application
in which the composition will be used and the desired swelling
characteristics.
[0026] Where used, the swellable elastomer generally may be present
in the cement compositions of the present invention in an amount
sufficient to provide the desired mechanical properties. In some
embodiments, the swellable elastomer may be present in the cement
compositions of the present invention in an amount from about 0.5%
to about 50% bwoc, alternatively from about 1% to about 20% bwoc,
and alternatively from about 4% to about 15% bwoc.
[0027] Those of ordinary skill in the art, with the benefit of this
disclosure, will appreciate that the ratio of the swellable
elastomer to the high-density particulate elastomer may be
optimized to the various properties of each elastomer, such as
high-chemical resistance (e.g., the fluoroplastics) and swelling
characteristics (e.g., the swellable elastomers). For example, a
cement composition may be designed to include a particular
concentration of elastomeric materials. In certain embodiments, it
may be desired for the elastomeric materials to include a
high-density particulate elastomer and a swellable elastomer. For
example, optimal swelling characteristics of the elastomeric
materials may be achieved with only a portion of the elastomeric
material comprising the swellable elastomer. Likewise, optimal
chemical resistance of the elastomeric materials may be achieved
with only a portion of the elastomeric material comprising the
high-density particulate elastomer, for example. Accordingly, a
method of the present invention may include determining a
concentration of the particulate elastomer and the swellable
elastomer to include based, for example, on the desired mechanical
properties of the cement composition, desired swelling of
elastomeric materials in the cement composition, desired chemical
resistance of elastomeric materials in the cement composition.
[0028] In addition, the swellable elastomer that may be present in
the cement compositions of the present invention may have a wide
variety of shapes and sizes of individual particles suitable for
use in the cement compositions of the present invention. By way of
example, the swellable elastomer may have a well-defined physical
shape as well as an irregular geometry, including the physical
shape of platelets, shavings, fibers, flakes, ribbons, rods,
strips, spheroids, hollow beads, toroids, pellets, tablets, or any
other physical shape. In some embodiments, the swellable elastomer
may have a particle size in the range of about 5 microns to about
1,500 microns. In some embodiments, the swellable elastomer may
have a particle size in the range of about 20 microns to about 500
microns. However, particle sizes outside these defined ranges also
may be suitable for particular applications.
[0029] Optionally, other additives suitable for use in subterranean
cementing operations also may be added to the cement compositions
of the present invention. Examples of such additives include, but
are not limited to, strength-retrogression additives, set
accelerators, weighting agents, weight-reducing additives,
heavyweight additives, lost-circulation materials,
filtration-control additives, dispersants, defoaming agents,
foaming agents, and combinations thereof. Specific examples of
these, and other, additives include, but are not limited to,
crystalline silica, amorphous silica, salts, fibers, hydratable
clays, vitrified shale, microspheres, fly ash, lime, latex,
thixotropic additives, combinations thereof and the like. A person
having ordinary skill in the art, with the benefit of this
disclosure, will readily be able to determine the type and amount
of additive useful for a particular application and desired
result.
[0030] As will be appreciated by those of ordinary skill in the
art, with the benefit of this disclosure, the cement compositions
of the present invention may be used in a variety of subterranean
applications, including, but not limited to, primary cementing and
remedial cementing. For example, in primary cementing applications,
the cement compositions may be introduced into an annulus between a
pipe string located in a subterranean formation and the
subterranean formation and allowed to set therein. It is to be
understood that "subterranean formation" encompasses both areas
below exposed earth and areas below earth covered by water, such as
ocean or fresh water. In addition, in remedial cementing
applications, the cement compositions may used, for example, in
squeeze cementing operations or in the placement of cement plugs.
Moreover, the cement compositions of the present invention also may
be used in surface applications, such as construction
cementing.
[0031] In accordance with embodiments of the present invention, a
cement composition may be introduced into a selected location and
allowed to set therein. As will be appreciated, the selected
location may any suitable location above ground or in a well bore
where it is desired for the cement composition to set into a
hardened mass. For example, the selected location may in a well
bore penetrating a subterranean formation, such as an annulus
between a pipe string located in the subterranean formation and the
subterranean formation.
[0032] While the preceding discussion is directed to the use of a
high-density particulate elastomer in well cementing methods, those
of ordinary skill in the art will appreciate that the present
technique also encompasses the use of high-density particulate
elastomers in a variety of different subterranean treatments,
including drilling fluids, completing fluids, stimulation fluids,
spacer fluids, and well clean-up fluids. In accordance with one
embodiment, a high-density particular elastomer may be included in
a spacer fluid. For example, a spacer fluid may be placed between
two fluids contained in or to be pumped within a well bore.
Examples of fluids between which spacer fluids are utilized include
between cement compositions, and drilling fluids, between different
drilling fluids during drilling fluid changeouts and between
drilling fluids and completion brines. Among other things, spacer
fluids may be used to enhance drilling fluid and filter cake
removal from the walls of well bores, to enhance displacement
efficiency and to physically separate chemically incompatible
fluids. For example, a hydraulic cement composition and a drilling
fluid may be separated by a spacer fluid when the cement
composition is placed in the well bore. In accordance with
embodiments of the present invention, the spacer fluid may prevent,
or at least partially reduce, intermixing of the cement composition
and the drilling fluid and may facilitate the removal of filter
cake and gelled drilling fluid from the walls of the well bore
during displacement of the drilling fluid by the cement
composition.
[0033] To facilitate a better understanding of the present
invention, the following examples of certain aspects of some
embodiments are given. In no way should the following examples be
read to limit, or define, the entire scope of the invention.
Example 1
[0034] To compare the use of high- and low-density particulate
elastomers, cement compositions were designed having a density of
17 lb/gal. As illustrated by Tables 1 and 2 below, the cement
composition with the high-density particulate elastomer maintained
a density of 17 lb/gal without the addition of a heavyweight
additive, improving mixability of the cement composition. However,
to maintain the density of 17 lb/gal, the cement composition with
the low-density particulate elastomer needed 40% bwoc of a
heavyweight additive.
[0035] Sample Cement Composition No. 1 included the low-density
particulate elastomer. As illustrated by Table 1 below, Sample
Cement Composition No. 1 was designed to include water in an amount
of 53.44% bwoc, Portland Class H cement, the low-density
particulate elastomer (WELLIFE.TM. 665 additive) in an amount of
12% bwoc, a heavyweight additive (MICROMAX.TM. cement additive from
Halliburton Energy Services, Inc.) in an amount of 40% bwoc, a set
retarder (SCR-100.TM. cement additive from Halliburton Energy
Services, Inc.) in an amount of 0.5% bwoc, a fluid-loss-control
additive (HALAD-413.TM. fluid-loss additive from Halliburton Energy
Services, Inc.) in an amount of 0.6% bwoc, a cement dispersant
(CFR-3.TM. cement dispersant from Halliburton Energy Services,
Inc.) in an amount of 0.2% bwoc, silica flour (SSA-1.TM. cement
additive from Halliburton Energy Services, Inc.) in an amount of
20% bwoc, and course silica flour (SSA-2.TM. cement additive from
Halliburton Energy Services, Inc.) in an amount of 20% bwoc. As
noted above, Sample Cement Composition No. 1 needed 40% bwoc of the
heavyweight additive to provide a density of 17 lb/gal.
TABLE-US-00001 TABLE 1 Specific Additive % BWOC Grams Gravity Water
53.44 267.2 0.998 Portland Class H 100 500 3.18 Cement Low-Density
12 60 0.99 Particulate Elastomer Heavyweight 40 200 4.9 Additive
Set Retarder 0.5 2.5 1.42 Fluid-Loss-Control 0.6 3 1.428 Additive
Dispersant 0.2 1 1.28 Silica Flour 20 100 2.63 Course Silica Flour
20 100 2.63
[0036] Sample Composition No. 2 included the high-density
particulate elastomer. As illustrated by Table 2, Sample
Composition No. 2 was designed to include water in an amount of
49.2% bwoc, Portland Class H cement, a high-density particulate
elastomer (DYNEON.TM. PFA) in an amount of 8% bwoc, a set retarder
(SCR-100.TM. cement additive) in an amount of 0.5% bwoc, a
fluid-loss-control additive (HALAD-413.TM. fluid-loss additive) in
an amount of 0.6% bwoc, a cement dispersant (CFR-3.TM. cement
dispersant) in an amount of 0.2% bwoc, silica flour (SSA-1.TM.
cement additive) in an amount of 20% bwoc, and course silica flour
(SSA-2.TM. cement additive) in an amount of 20% bwoc. As noted
above, Sample Cement Composition No. 2 did not need any of the
heavyweight additive to provide a density of 17 lb/gal because the
high-density particulate elastomer was used rather than the
low-density particulate elastomer.
TABLE-US-00002 TABLE 2 Specific Additive % BWOC Grams Gravity Water
49.2 295.2 0.998 Portland Class H 100 600 3.18 Cement High-Density
8 48 2.15 Particulate Elastomer Set Retarder 0.5 3 1.42
Fluid-Loss-Control 0.6 3.6 1.428 Additive Dispersant 0.2 1.2 1.28
Silica Flour 20 120 2.63 Course Silica Flour 20 120 2.63
Example 2
[0037] The following tests were performed to evaluate the
mechanical properties of a set cement composition that included a
high-density particulate elastomer. First, a cement composition was
prepared having a density of 14.7 lb/gal and containing water in an
amount of 67% bwoc, Portland Class H cement, fly ash in an amount
of 27% bwoc, a high-density particulate elastomer (DYNEON.TM. PFA)
in an amount of 20% bwoc, a fluid-loss-control additive
(HALAD-344.TM. EXP fluid-loss additive from Halliburton Energy
Services, Inc.) in an amount of 0.6% bwoc, and a cement dispersant
(CFR-3.TM. cement dispersant) in an amount of 0.1 gallons per 94
pound sack of the cement. This sample cement composition was then
tested to determine the compressive strength, Young's modulus, and
Poisson's ratio. The compressive-strength tests were performed in
accordance with API Specification 10. The Young's modulus and
Poisson's ratio were statically determined by means of compression
testing using a load frame. The Young's modulus (or modulus of
elasticity) for each sample was obtained by taking a ratio of a
simple tension stress applied to each sample to a resulting strain
parallel to the tension in that sample. The Poisson's ratio for
each sample was determined by calculating a ratio of transverse
strain to a corresponding axial strain resulting from uniformly
distributed axial stress below a proportional limit of each sample.
The values determined for two series of tests for this sample
cement composition are set forth below in Table 3.
TABLE-US-00003 TABLE 3 Confining Compressive Pressure Strength
Young's Poisson's Test (psi) (psi) Modulus Ratio No. 1 0 947
3.93E+05 0.173 No. 2 0 946 3.89E+05 0.163
[0038] Therefore, the present invention is well adapted to attain
the ends and advantages mentioned as well as those that are
inherent therein. The particular embodiments disclosed above are
illustrative only, as the present invention may be modified and
practiced in different but equivalent manners apparent to those
skilled in the art having the benefit of the teachings herein.
Furthermore, no limitations are intended to the details of
construction or design herein shown, other than as described in the
claims below. It is therefore evident that the particular
illustrative embodiments disclosed above may be altered or modified
and all such variations are considered within the scope and spirit
of the present invention. Whenever a numerical range with a lower
limit and an upper limit is disclosed, any number and any included
range falling within the range is specifically disclosed. In
particular, every range of values (of the form, "from about a to
about b," or, equivalently, "from approximately a to b," or,
equivalently, "from approximately a-b") disclosed herein is to be
understood to set forth every number and range encompassed within
the broader range of values. Moreover, the indefinite articles "a"
or "an", as used in the claims, are defined herein to mean one or
more than one of the element that it introduces. Also, the terms in
the claims have their plain, ordinary meaning unless otherwise
explicitly and clearly defined by the patentee.
* * * * *