CEMENT COMPOSITIONS COMPRISING DEAGG LO RATED
INORGANIC NANOT E AND ASSOCIATED METHODS
BACKGROUND
[000 j Cement compositions may be used n a variety of subterranean operations.
For example, in subterranean well construction, a pipe string (e.g., casing, liners, expandable
tubuiars, 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 ay set in the annular space, thereby forming an annular sheath of
hardened, substantially impermeable cement {i.e.., a cement sheath) tha may support and
position the pipe string in the we bore and may bond the exterior surface of the pipe string
to the subterranean formation. Among other things, the cement sheath surrounding the pipestring
functions to prevent the migration of fluids in the annulus, as well as protecting the
pipe s rin from corrosion. Cement compositions also may be used in remedial cementing
methods, or example, to seal cracks or holes pipe strings or cement sheaths, t seal highly
permeable formation zones or fractures, to place a cement plug, and the like. Cement
Compositions may also be used in surface-cementing operations, such as construction
cementing.
[0002] Once set, the cement sheath may be subjected to a variety of shear, tensile,
impact, flexural, and compressive stresses that may ead to failure o the cement sheath,
resulting in, for example, fractures, cracks, and/or debondhig of the cement sheath f om the
pipe string and/or the formation. This ca lead to undesirable consequences including lost
production, environmental pollution, hazardous rig operations resulting from unexpected
fluid .flow from the formation caused by the oss of zonal isolation, and/or hazardous
production operations, among others. Cement failures may be particularly problematic in
high temperature wells, where fluids injected into the wells or produced from the wells by
wa of the well bore may cause the temperature of an fluids trapped within the annulus to
increase. Furthermore, high fluid pressures and/or temperatures inside the pipe string may
cause additional problems during testing perforation, fl u id inj ection, and-'or fluid production
if the pressure and/or temperature inside the pipe string increases the pipe may expand and
stress the surrounding cement sheath. This may cause the cement sheath to crack, or the
bond between the outside surface o the pipe string and the cement sheath to fail, thereby
breaking the hydraulic seal between the two. Furthermore, high temperature differentials
created during production or injection of high temperature fluids through the well bore may
cause fluids trapped in the cement sheath to thermally expand, causing high pressures within
the sheath itself. Additionally, failure of the cement sheath a so may be caused by, for
example, forces exerted b shifts in subterranean formations surrounding the wel bore,
cement erosion, repeated .impacts from the drill bit and the drill pipe.
[0003] To improve the tensile strength of the set cement and at least partially
counteract the impact of these forces on the cement sheath, high aspect ratio fibers such as
glass fibers or organic fibers have been included in the cement compositions. However, the
use of these high aspect ratio fibers may have drawbacks. For example, glass fibers
generally cannot be added to the dry blend typically comprising the hydraulic cement and
other dry additives since they break down under shear during preparation of the cement
composition- By way of further example, organic fibers such as polypropylene fibers
typically have temperature limitations that cause them to .melt or soften at elevated
temperatures, which ay be problematic as higher temperatures can be encountered in
subterranean cementing operations. In addition, the length of the high aspect ratio fibers that
may be needed to enhance tensile strength is typically on the order of a few millimeters,
presenting mixing problems during preparation of the cement composition. To ensure
adequate mixability, the amount of fibers that can b added to a cement composition has
been limited, for example, with upper limits in the range of 0.5% to 2%by weight of cement
< bwo >.
SUMMARY
[0004] An embodiment of the present invention provides a method of cementing
comprising: providing an u raso icated aqueous dispersion comprising deagglomerated
nanopartsdes, a dispersing agent, and water; preparing a cement composition using the
aqueous dispersion; introducing the cement composition i to a subterranean formation; and
allowing the cement composition to set
[00051 Another embodiment of the present invention provides a method of
cementing comprising: providing a aqueous dispersion comprising deagglomerated
inorganic nanotubes and water; preparing a cement composition using the aqueous
dispersion; and a owing the cement composition to set.
[0006] Another embodiment of the present invention provides a method of
cementing comprising; providing a cement composition comprising a cement,
deagglomerated halloysUe nanotubes, a dispersing agent, and water, wherein deagglomerated
halloysite nanotubes comprise halloysUe nanotubes having a diameter in a range of
about nanometer to about 300 nanometers and length in a range of from about 500
nanometers to about 0 microns; introducing the cement composition into a subterranean
formation; and allowing the cement composition to set such that the cement composition
after setting for a period in a range of from about 24 hours to about 72 hours has a tensile
strength that s increased by about 25% when compared to the sam cement composition
without deaggSomeration of the halloysUe nanotubes,
[0007] Another embodiment of the present invention provides a cement composition
comprising a cement, deagglomerated inorganic nanotubes, and water.
[0008] 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 ar within the spirit of the invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0009] The present invention relates to subterranean cementing operations a d, ore
particularly, in certain embodiments, to cement compositions comprising deagglomerated
inorganic nanotubes and associated methods. There may be several potential advantages to
the methods and compositions of the present invention, only some of which ma e alluded
to herein. One of the man potential advantages of the methods and compositions of the
present invention is that the deagglomerated inorganic nanotubes, such as a ioys te
nanotubes may enhance mechanical properties of the cement compositions including
enhancement of tensile strength. As a result, it i believed that cement compositions
comprising deagglomerated inorganic nanotubes may have a reduced tendency to fail after
setting n a well-bore annuius. Another potential advantage of the methods and
compositions of the present Invention is that the deagglomerated inorgan ic nanotubes ay be
provided in an aqueous dispersion, thus allowing inclusion in a cement composition by use
of standard mixing techniques
[00 0 An embodiment of the cement compositions comprises cement,
deagglomerated inorganic nanotubes, and water. Those of ordinary sk l in th art will
appreciate that the cement compositions generally should have a density suitable for a
particular application. By way of example, th cement compositions may have a density in
the range of from about 4 pounds per gallon ('lb/gal") to about 20 lb/gal. in certain
embodiments, the cement compositions ma have a density in the range of from about
lb/gal to about 7 lb/gal. Embodiments of the cement compositions ma be foamed or
unfoanied or may comprise other means to reduce their densities, such as hollow
microspheres, low-density elastic beads, or other density-reducing additives known n the
art. In some embodiments, heavyweight additives e.g . hematite, magnesium oxide, etc.)
may be use for increasing the density of the cement compositions. Those of ordinary skill
in the art, with the benefit of this disclosure, wil recognize the appropriate density for a
particular application.
[00 ] Embodiments of the cement compositions may comprise cement. Any of a
variety of cements suitable for use in subterranean cementing operations may be used in
accordance with example embodiments. Suitable examples include hydraulic cements that
comprise calcium, aluminum, silicon, oxygen and/or sulfur, which set and harden by reaction
with water. Such hydraulic cements, include, but are not limited to, Portland cements,
pozzo!ana cements, gypsum cements, high-aiuniina-conient cements, slag cements, silica
cements and combinations thereof. n certain embodiments, the hydraulic cement may
comprise a Portland cement. Portland cements that m e suited for use in example
embodiments may be classified as Class A, C and cements according to American
Petroleum institute, API Specification for Materials and Testing for Well Cements, AP I
Specification 0 , Fifth Ed., Jul. 1, 1990. h .addition, in some embodiments, hydraulic
cements suitable for use i the present invention ma be classified as ASTM Type I, I, or
ΪΪΪ ,
00 12] Embodiments of th cements composition may comprise deagglomerated
inorganic oanotubes. The deagglomerated inorganic nanotubes ma generally comprise
inorganic nanotubes in the shape of a tubular, rod-like structure having diameter in a range
of from about .nanometer ("Dm") to several hundred nanometers, for example n certain
embodiments, the inorganic oanotubes may have a diameter of less than about 300 rim, less
than about 200 urn, less than about 0 n , in some embodiments, and less than 50 nm in
additional embodiments. The inorganic nanotubes may have an aspect ratio (ratio of length
to diameter) n a range of from about 1.25 to about 500. n certain embodiments, the
inorganic nanotubes may have an aspect ratio in range of about 10 to about 200 and, in
certain embodiments, from about 25 to about 0, The size of the inorganic nanotubes may
he measured using any suitable technique. It should e understood that the measured size of
the inorganic nanotubes ay vary based on measurement technique, sample preparation, a d
sample conditions such as temperature, concentration, etc. One technique fo measuring i
of the nanotubes is Transmission Electron Microscope (TEM) observation. By this method,
it is possible to determine the length and diameter of a single nanotube, bundle diameter, and
number of nanotubes i a bundle. An example of suitable commercially available based on
laser diffraction technique is Zetasizer Nano ZS supplied by Malvern Instruments,
Worcerstershire, UK n so e embodiments, the nanotubes are hollow n some
embodiments, the nanotubes are open at one or both ends. In some embodiments, the
inorganic nanotubes may be single-walled or multi-walled nanotubes.
[0013] The inorganic nanotubes used in example embodiments may be any of
variet of different nanomaterials that ca be incorporated into the cement compositions.
The inorganic nanotubes may be synthetic or naturally occurring. Examples of suitable
inorganic nanotubes include nanotubes that comprise metal oxides, sulfides, se!enides
a minosiSieates, and combinations thereof in certain embodiments, inorganic nanotubes
may be synthesized from metal oxides, such as vanadium oxide, manganese oxide, titanium
oxide, and zinc oxide. In additional embodiments, inorganic nanotubes may be synthesized
from sulfides, such as tungsten (IV) disulfide, molybdenum disulfide, and tin (IV) disulfide.
n souse embodiments, the inorganic nanotubes may comprise a urnin siSkates, such as
hailoysite, iumgolite, y h drite, boulangerite, and combinations thereof.
[0014] n certain embodiments, the inorganic nanotubes may comprise hailoysite.
The term "hailoysite" refers to a naturally occurring a mi o i licate material comprising
aluminum, silicon, hydrogen, and oxygen, which may be formed by hydrothermal alteration
of aluminosiiicaie minerals over a period of time. HalloysUe is mined in a umber of
locations, including in Wagon Wheel Gap, Colorado, USA, for example. The hailoysite may
be mined from the Earth and then processed to separate the halloysUe that is present in
tubular form from other forms and also from other minerals. Nanotubes comprising
hailoysite may have a diameter in a range of from about nanometer to several hundred
nanometers, lor example, in certain embodiments, the nanotubes comprising hailoysite may
have a diameter of less than about 300 nm, less tha about 200 nm, less than about 100 nm,
or less than 50 nm n embodiments, the nanotubes comprising hailoysite may have a
diameter in a range of from about 30 nm to about 70 nm. The nanotubes comprising
hailoysite may have a length in a range of from about 500 nm to a few microns o more. In
some embodiments, the nanotubes comprising hailoysite may have a length in a range of
from about 500 nm to about . microns a d, alternatively, from about i micron t about 3
microns- An example of a suitable nanotube comprising hailoysite may have a diameter in a
range of from about 30 nm to about 70 nm and a length in a range of from about 1micron to
about 3 microns.
[001 5] Those of ordinary skill in the art, with the benefit of this disclosure, will
appreciate that the inorganic nanotubes can form agglomerates made up of inorganic
nanotubes. For example, agglomerates may form w en dispersions of the nanotubes ar
stored for a period of time, such as from a few days to several weeks or more, or when the
inorganic nanotubes are prepared, separated, and/or isolated in the solid form. t is believed
that agglomerates of the nanotubes do not exhibit the same mechanical-property
enhancement of the cement composition as the deaggiomerated nanotubes presumable
because contact area between the cement matrix and the deaggiomerated form (for example,
discrete nanotubes) is significantly higher than with the agglomerated form. Indeed, as
shown below in Example nanotubes that have not undergone a de-agglomeration process
do not show significant increase in Brazilian tensile strength for the set cement
composition. However as shown in Examples 2-4, the use of deaggiomerated nanotubes has
been shown to increase the tensile strength of th set cement compositions
[00.16] Therefore, h accordance with embodiments of the present invention, the
agglomerated inorganic nanotubes may be subjected to a deaggSomeration process. The
deagglomerated nanotubes may then be included in embodiments of the cement
compositions. The term de gg!ofnera ed does not necessarily mean that agglomerates
comprising the inorganic nanotubes have been broken down completely into individual
inorganic nanotubes. Rather, i means that the agglomerates comprising th nanotubes have
undergone some type of processing to deaggloroerate the agglomerates that may have formed
during storage of nanotube dispersions or during production of the nanotubes, for example
n so e embodiments, at least a portion or even substantially a l of the inorganic nanotubes
n the deagglomerated inorganic nanotubes a e i the fo of individual inorganic nanotubes.
For example, at least about 50% or more of the inorganic nanotubes in the deagglomerated
inorganic nanotubes ay be in th form of individual inorganic nanotubes. n some
embodiments, at least about 60%, at least about 70%, at least about 80%, or at least about
90% of the inorganic nanotubes in the deagglomerated inorganic nanotubes may be in the
form of individual inorganic nanotubes.
[00 7 'l e deagglomeration of the agglomerates of inorganic nanotubes may b
achieved usin in any of a variet of different processes suitable for the deagglomeration of
nanotubes, including ultrasonication, mixing n a magnetically assisted fluidized bed, stirring
n supercritical fluid, and magnetically assisted impaction mixing. In some embodiments,
agglomerates of th inorganic nanotubes may be provided in a liquid and ultrasonicated
using any known ultrasonication technique. The liquid may include water. Alternatively,
the liquid ay comprise alcohols, alcohol ethers, glycols, glycol ethers, and combinations
thereof. n alternative embodiments, the inorganic nanotubes may be provided in a
powdered form which may then be dispersed in a liquid (e.g.. water) and then ultrasonicated.
It is believed that the inorganic nanotubes may form agglomerates in the powder and/or after
dispersion in the liquid. As wi l be appreciated those of ordinary skill in the art, with the
benefit of this disclosure the ultrasonication may deagglomerate the inorganic nanotubes,
thus breaking the agglomerates down into smaller-sized particles, such as individual
inorganic nanotubes. In some embodiments, the agglomerates are ultrasonicated for a period
of time in range of from about 10 minutes to about I hour or more. For example the
agglomerates may be ultrasonicated for about 20 minutes to about 40 minutes, one
embodiment, the agglomerates may be ultrasonicated for about 3.0 minutes. In some
embodiments, the ultrasonication ma include use of an uSirasonicator, such as an ultrasonic
bath. The operating frequency of the ultrasonieator may range fro about 20 k lz to about
80 k z and be 40 kHz i one embodiment. Th resulting ultrasonicated dispersion may then
b stirred for a period of time, for example, to produce a more homogenous mixture. In
some embodiments, the ultrasonicated dispersion ay be stirred for about I minute to a few
hours. For example, the ultrasonieated dispersion may foe stirred for about 30 minutes to
about 1 hour. In some embodiments, stirring ay ot be needed.
[00 ] To facilitate stabilization of the deagglomerated form in the liquid, a
dispersing agent may be included in the liquid. For example, a dispersion comprising a
liquid, the inorganic nanotube agglomerates, and the dispersing agent may be provided and
then ultrasonieated, for example, as previously described. In some embodiments, the
dispersing agent may be added to the dispersion after ltrasoni at on or even during
ultrasonieation. The dispersing agent generally should facilitate deagglo erat and/or
prevent the undesirable rea¾¾lomeraiion of larger inorganic nanotube agglomerates. It is
believed that the inclusion of the dispersing agent may increase the shelf life of the
ultrasonieated dispersion comprising the deagglomerated nanotubes. thus allowing the
ultrasonieated dispersion to be stored prior to use. For example, it i believed that the
ultrasonieated dispersion may be stored tor about hour to several weeks or ore without
undesired feagglonieration such that the inorganic nanotubes may b used to provide
mechanical -property enhancement for a cement composition after storage. In some
embodiments, the ultrasonieated dispersion may be stored for at least 1 day, a least about I
week, at. least about 1 month, or longer . Where used, the dispersing agent ay be included
in a amount i a range of from about 1% to about 20%, alternatively from about 3% to
about %, and alternatively from about 5% to about %, al percentages being by weight
of the inorganic nanotubes. One of ordinar skill in the art, with the benefit of this
disclosure, should recognize the appropriate amount of the dispersing agent to include for a
chose appl ication.
[0 ] Examples of suitable dispersing agents include water-soluble, low-mo!eeuiarweight
components that may be anionic, non-ionic, or amphoteric. n some embodiments,
the dispersing agent may include an anionic polymer comprising a carboxylic group and/or
sulfonate group. Without being limited by theory, the anionic polymers generally should
disperse the inorganic nanotubes and prevent reagglomeraiiou by means of electrostatic as
well as steric repulsion. In some embodiments, comb/branched polycarhoxylates such as
comb/branched polycarboxy!ate ethers may be used to disperse the inorganic nanotubes
and/or prevent reagglomeration. For example, suitable poiycarboxylate ethers include
MELFL X ' Dispersing agent (BASF Chemical Company), ET ACRY " Dispersing
agent (Coatex, LLC) and MIGHTY EG* Dispersing agent ( ao Specialties Americas, LLC)
n some embodiments, the carboxylated dispersant may be non-polymeric, for example, a tty
acids or their salts such as inolei acid, stearic acid, and the ike n some embodiments,
sulfonated water-soluble anionic polymers such as polystyrene sulfonate can be used. A
example of a suitable polystyrene sulfonate is Gel Modifier 5 (Halliburton Energy
Services). Other suitable a ioni polymeric or monomelic dispersants include those
containing phosphate o phospfiooate anionic groups. Examples of non-ionic dispersants
include polyethylene glycols, ethylene oxide/propylene oxide copolymers (block or random)
and polyvinyl alcohol and any combination thereof In some embodiments, the d spersan s
may be surface active. I should be possible for one skilled in the art to select a proper
dispersant depending the dispersion medium, and the chemical composition of particular
inorganic anot be
[0020] n some embodiments, the deagglomerated inorganic nanotubes function as a
mechanical property enhancer. For example, deagglomeration of the inorganic nanotubes
ca be used to enhance the Brazilian tensile strength of the set cement composition. By way
of example, the Brazilian tensile strength of ceme t compositions comprising
deagglomerated inorganic nanotahc may be increased by at least about 25% in one
embodiment, at least about 50% in another embodiment, and at least about 0% i yet
another embodiment, as compared to the same cement composition that does not contain the
inorganic nanotubes or in which the inorganic nanotubes were not deagglomerated. In some
embodiments, the cement composition has a Brazilian tensile strength after setting of at least
about 400 psi, ai least about 600 psi in some embodiments, and at least about 800 in
alternative embodiments in some embodiments, the cement composition has a Brazilian
tensile strength in a range of from about 400 psi to about 850 ps . As described herein, the
Brazilian tensile strength is measured at a specified time after the cement composition has
been mixed and then allowed to set under specified temperature and pressure conditions for a
period of time. For example, Brazilian tensile strength can be measured after a period of n a
range of from about 24 hours to about 96 hours. The Brazilian tensile strengths can be
measured as specified in TM C496/C496M in which the splitting tensile strength is
measured for a cylindrical concrete specimen.
[0021] n general, the deagglomerated inorganic nanotubes may be included in the
cement composition in an amount sufficient to provide the desired mechanical property
enhancement, for example. In some embodiments, the deagglomerated inorganic nanotubes
may be present in an amount in a range of from about 0.01% bwoe to about 10% bwoe. h
particular embodiments, the deagglomerated inorganic nanotubes may be present in an
amoun ranging between any of and/or including any of about 0.01%, about 0.05%, about
0. %, about 0.5%, about %, about 2%, about 3%, about 4%, about 5% about 6%, about
%, about 8%, about 9%, or about 10%, a i percentages bwoe. One of ordinary skill in the
art, with the benefit of this disclosure, should recognize the appropriate amount of the
deagglomerated inorganic nanotubes o include for a chose application.
[0022] Embodiments of the cement compositions may comprise water. The water
may be fresh water or salt water, -Salt water -generally may include one or more dissolved
salts therein and may be saturated or unsaturated as desired for a particular application.
Seawater or brines may be suitable for use in embodiments of the present invention. Further,
the water may be present in an amount sufficient to form pumpable slurry n so e
embodiments, the water ay be included in the setiable compositions of the present
invention in a amount in the range of from about 40% bwoc to about 200% bwoc. For
example, the water may be present in an amount ranging between any o f and/or including
any of about 50%, about 5%, about 100%, about 25%, about 50%, or about 175%, a l
percentages- bwoc. In specific embodiments, the water ma be included in a amount in the
range of from about 40% bwoc to about 50% bwoc. One of ordinary skill in the art, with
the benefit of this disclosure, wil recognize the appropriate amount of water o include for a
chosen application
[0023] Other additives suitable for use in subterranean cementing operations a so
may be added to embodiments of the cement compositions. Examples of such additives
include, but are not limited to, strength-retrogression additives, se accelerators, weighting
agents, lightweight additives, gas-generating additives, mechanical property enhancing
additives, lost-circulation materials, filtration-control additives, dispersing agents, fluid loss
control additives, defoammg agents, foamin agents, thixotropic additives, and combinations
thereof. By way of example, the cement composition may b a foamed cement composition
further comprising a foaming agent and a gas. Specific examples of these, and other,
additives include crystalline silica, amorphous silica, fumed silica, salts, fibers, hydratahle
clays, calcined shale, vitrified shale, microspheres, fly ash, slag, dlatomaceous earth,
metakaolin, ri e husk ash, natural pozzolan, zeolite, cement kiln dust, lime, elastomers,
resins, latex, combinations thereof and th like. A person having ordinary skil in the art,
with the benefit of this disclosure, will readily e able to determine the type an amount of
additive useful for a particular application and desired result.
[0024] The components of the cement compositions comprising deagglomerated
inorganic nanotubes may be combined in any order desired to form a cement composition
that can be placed into a subterranean formation. The components of th cement
compositions comprising deagglomerated inorganic nanotubes may be combined using any
mixing device compatible with the composition, including a bulk mixer, for example, n
some embodiments, a dispersion comprising the deagglomerated nanotubes may be provided
and combined with the water before it is mixed with the cement to form the cement
composition. certain embodiments, the dispersion may be an ultrasomcated dispersion
that further comprises a dispersing agent
[0025] As wil be appreciated by those of ordinary skill in the art, embodiments of
the cement compositions of the present invention may be used in a variety of subterranean
operations, including primary and remedial cementing. In some embodiments, a cement
composition may be provided that comprises cement, deagglomerated nano bes, and water.
The cement corn-position may be introduced into a subterranean formation and allowed to set
therein. As used herein, introducing the cement composition int a subterranean formation
includes .introduction into any portion of the subterranean formation, including, without
limitation, into a wel bore drilled into the subterranean formation, into a near well bore
region surrounding the well bore, or i to both
[0026] In primary-cementing embodiments, for example, embodiments of the
cement composition may be introduced into a well-bore annul us such as a space between a
wall of a wel bore and a conduit (e.g., pipe strings, liners) located n the well bore, the well
bore penetrating the subterranean formation. The cement composition may be allowed to set
to form an annular sheath of hardened cement in the well bore annul us. Amon other things,
the set cement composition may form a barrier., preventing the -migration of fluids in the well
bore. The set cement composition a so may, for example, support the conduit n the well
bore,
[0027] In remedial-cementing embodiments, a cement composition may be used, for
example, in squeeze-cementing operations or in the placement of cement plugs. By way of
example, the cement composition may be placed in a well bore to plug an opening, such as a
void or crack, in the formation, in a gravel pack, in the conduit, in the cement sheath, and/or
a microannulus between the cement sheath and the conduit.
[0028] While the preceding description is directed to the use of deagglomerated
inorganic nanoiubes, those of ordinary skill in the art, with the benefit of this disclosure,
should appreciate that it may be desirable to utilize other types of deagglomerated
nanoparticles in accordance with embodiments of the present invention. For example, by use
of deagglomerated .nanoparticles the .nanoparticles included in a cement composition may
have a higher surface exposed surface area, thus providing increase performance
improvement to cement compositions. Examples of such nanoparticles may include nanoelay,
nano-hydraulic cement, nano a um na, nano-zmc oxide, nano-horoo, nano-iron oxide,
and combinations thereof. In some embodiments, nanosilica dispersions are not included, n
general, the nanoparticles may be defined as having at leas t one dimension (e.g., length,
width, diameter) that is less tha 0 nanometers. For example, the nanopartieles may have
at least one dimension that is n a . range of from about nm to less than 00 nanometers. n
particular embodiments, the nanoparticles may have at least one dimension ranging between
any of and/or including any of about 1 nm, nm about 50 nm., about 60 nm, about 70 nm,
about 80 nm, about 90 nm, or about 99 nm. In addition, the nanoparticles ay be configured
in any of a variety of different shapes in accordance with embodiments of the present
invention. Examples of suitable shapes include nanoparticles in the general shape of
platelets, shavings, flakes, rods, strips, spheroids, toroids, pellets, tablets, or a y other
suitable shape,
EXAMPLES
[0029] To facilitate a better understanding of the present invention, the following
examples of certain aspects of some embodiments are given, n no way should the following
examples be read to limit, or define, the entire scope of the invention.
Example ί
[0030] The following example was performed to evaluate the effect of the addition
of halloysite nanotubes to a cement composition. Three sample cement compositions,
designated Samples 1-3 , were prepared that had a density of 15.8 lb/gal and comprised
Portland Class G cement in an amount of 00% bwoc, water in an amount of 5.09 gallons
per 94-pound sack of the 4eement ( ga sk ) and a cement dispersing agent (C R~3
cement friction reducer from Halliburt on Energy Services. Inc.) in an amount of 0,2% bwoc.
Sample ί was a control and did not include a tensile strength enhancer. Sample 2 further
included glass fibers (Well Life*" 734 Additive, from Halliburton Energy Services), in an
amount of .0% bwoc, as a tensile strength enhancer. The glass fibers ha a length of 3 mm.
Sample 3 included halloysite nanotubes (Halloysite from Signia-Aidrich Co, L LC' ), in an
amount of .0% bwoc, as a tensile strength enhancer,
[003 The physical properties of the halloysite nanotubes tested in this example are
g en below:
Chemical Formula: A S O
Molecular Weight; 294. g n o
Diameter x Length 30-70 nanometers x 1-3 microns
Surface Area: 64 m g
Pore Size .26- 1.34 mL g
Density: 2.53 g/ i v'
The halloysite nanotubes were provided in a dry, powder fro Prior to mixing with cement,
the halloysite nanotubes were dispersed in water by stirring for 2 hours. To this dispersion,
the Portland Class G cement was added. The cement dispersing agent was provided in a
powder form and was dry blended with the cement prior to mixing with the water
[0032] After preparation, each sample cement composition was then cured for 72
hours h a 2" x 5" raetal cylinder in a water bath at 1S0 and atmospheric pressure to form
set e ent cylinders. The Brazilian tensile strength (ASTM C496/ 496M for each set
cement cylinder was the determined. The results from the tensile strength tests are set forth
in the table below. The percent increase reported is the difference between the tensile
strength for the particular sample and the tensile strength for Sample I (control) divided by
the tensite strength for Sample 1, The reported values in the table below are an average
value for testing of 2 cement cylinders for each sample.
TABLE 1
[0033] As indicated in the table above, Sample 3 with the halloysite nanotubes did
not exhibit a significant improvement in tensile strength in comparison to the control sa ple
in contrast. Sample 2 with the glass fibers exhibited an 8 . .2% increase in tensile strength.
Example 2
[0034] The following example was performed to further evaluate the effect of the
addition of halloysite nanotubes to cement composition o particular, this example
evaluated the impact of the ltrasonication of halloysite nanotubes on the tensile strength of
the cement composit n.
[0035] Three sample cement compositions designated Samples 4-6, were prepared
that had density of 1 .S lb/gal and comprised Portland Class cement in an amount o
0% hwoc, water in an amount of 5.09 ga /s a cement dispersing agent (CF -3 cement
friction reducer from Halliburton Energy Services, nc.) in an amount of 0,2% bwoe, and
halloysite nanotubes. The amount of the halloysite nanotubes (Halloysite from SigmaA
h ch Co LLC) in Samples 4-6 was varied fro 1,0% bwoc to 2.0% bwoc as indicated in
the table below.
[0036] In this example, a different technique was used for slurry preparation than
was performed in the preceding example. As described above, the hailoysite nanotubes were
provided in a . dry, powder from. Prior to mixing with cement, the hailoysite nanotubes were
dispersed in water and then u tra on ated for 30 minutes. The uitrasonication used an
ultrasonic water ba h having an operating frequency of 40 k te for the ultrasonicator. To this
ultrasonicated dispersion, the Portland Class G cement was added. The cement dispersing
agent was provided in a powder form a d was dry blended with the cement prior to mixing
with the water.
[0037] After preparation, each sample cement composition was then cured for 72
hours i a 2" x 5" metal cylinder i a water bath at and atmospheric pressure to form
set cement cylinders. The Brazilian tensile strength (ASTM C496/G4 ) for each set
cement cylinder was then determined. The results ra m the tensile strength tests are set forth
in the table below. The percent increase reported is the difference between the tensile
strength for the particular sample and the tensile strength for Sample 1 (control) divided by
the tensile strength for Sample . The reported values in the table be ow are an average
value for testing of 2 cement cylinders for each sample.
TABLE 2
[0038] As indicated in the table above, a significant increase in tensile strength was
observed for Sample 4 and Sample 5 as compared to Sample 1 (control) from the preceding
example that did not include a tensile strength enhancer. For example, Sample 4 that
contained hailoysite nanotubes in the amount of .0% bwoc had a tensile strength increase of
35 43%. By way of further example. Sample 5 that contained hailoysite nanotubes in the
amount of 1.5% bwoc had a . tensile strength increase of 77. % bwoc. This indicates that
uitrasonication of the hailoysiie nanotubes likely broke down agglomerates of the hailoysite
nanotubes into individual hailoysite nanotubes, thus providing significant increases n tensile
strength when the hailoysiie nanotubes were used in the cement composition.
Example 3
[0039] In the following example, the tests performed in Example 2 were repeated
except that the dispersing agent (CFR-3™ cement friction reducer) was replaced with a
anionic aerylate polymeric dispersing agent (Coatex XP 1629 from Coatex LLC). The
dispersing agent was added to the ultrasonicated dispersion in an amount of 0.05 ga /sk
before addition of the cement. The testing was also repeated o r Sample 1 (control) from
Example w th .replacement of the dispersing agent (CFR-3™ cement friction reducer) with
the anionic aerylate polymeric dispersing agent.
[0040] The results from the tensile strength tests are set forth in the table below
The percent increase reported is the difference between the tensile strength for th particular
sample and the tensile strength for Sample 7 (control) divided by the tensile strength for
Sample 7. The reported values in the table below are an average value for testing o 2
cement cylinders for each sample.
TABLE
Halioysite
Nanotubes ( oc) Brazilian TS (psi) j % crease
j Sample 7 Control 36 ,23 ....
j Sample 8 1.0 558.96 54.73
Sample 9 1.5 668.92 85. ?
j Sample 2.0 574.21 58.95
[0041] As indicated in the table above, a significant increase n tensile strength was
observed for Samples S-!O as compared t Sample 7 (control) that did no include a tensile
strength enhancer in particular. Sample 8-10 had tensile-strength increases ranging fro
54.73% to 85. 17%. This indicates that !trason ation of the halioysite nanotubes likely
broke dow agglomerates of the halioysite nanotubes, thus providing significant increases in
tensile strength when the halioysite nanotubes were used in the cement composition.
Example 4
[0042] The following example was performed to further evaluate the effect of the
addition of halioysite nanotubes to a cement composition, in particular, the example
evaluated the impact of the raso cation of halioysite nanotubes in the presence of a
dispersing agent -and compared the performance of halioysite nanotubes with kaolmi e
another alummosilicate material.
[0 43] S x sample cement compositions, designated Samples - 7 were prepared
that ad a density of 15.8 lb/gal a d compri sed Portland Class 0 cement i an amount of
0% b oc, water in an amount of 5.09 gal/sk, and a dispersing agent. Samples 3- 5 and
17 included halloysste nanotubes (hial ysite irons Sigma A d ch Co . LLC) in an amount
ranging from 0.4% bwo to 2,5% bwoc. Sample 2 included kaolin ( ano Caliber- 100 from
English India Clays Ltd.) in an amount of .5% bwoc. The kaolimte had a thickness of less
than 10 ran and width of 0-200 am. Samples and were controls that did not include
a aiuminosi!icate. The dispersing agent used in Samples 1- 5 was an anionic acry at
polymeric dispersing agent (Coatex XP 29 from Coatex LLC) in an amount of 0.05 gal/sk.
The dispersing agent used in Samples 16 and 17 was a polystyrene sulfonate (Ge Modifier
750L from Halliburton Energy Services, Inc.) in an amount o . 3 gal/sk.
[0044] n this example, a different technique was used for slurry preparation tha
was performed in the preceding examples. As described above, the hal oys ie nanotuhes
were provided in a dry, powder form. Prior to mixing with cement, the halloysiie .nanotubes
were dispersed in water and then u!irasonicated fo 30 minutes. The ui ra soni a io used an
ultrasonic water bath having an operating frequency of 40 kHz for the ultrasonicator. The
dispersing agent wa provided in a liquid form and added to the water prior to ultrasonicatton
such that the ultrasonieation of the halloysite nanotuhes was performed in the presence of the
dispersing a ent To this ui raso ated dispersion, the Portland Class G cement was added.
The samples with kaolin were also prepared using this technique.
[0045] After preparation, each sample cement composition was stored for 30
minutes and then cured for 2 hours in a 2" x . 5" meta cylinder in a water bath at. I O' F and
atmospheric pressure to form set cement cylinders. The Brazilian tensile strength ( TM
C496/C496M) for each set cement cylinder was then determined. The results from the
tensile strength tests are set forth in the table below. The percent increase reported is the
difference between the tensile strength for the particular sample and the tensile strength for
the control (Sample or 6 ) divided by the tensile strength for the control (Sample or
16). The reported values in the table below are an average value for testing of 2 cement
cylinders for each sample.
TABLE 4
[0046] As indicated in the table above, a significant increase tensile strength was
observed for Samples 13-15 and as compared to the control samples (Samples and )
from the preceding example that did not include a tens e strength enhancer in particular,
tensile-strength increases ranging from 36.14% to 134.88% were observed. The
ult o ication of the haiioysite nanoiubes in the presence of the dispersing agent appears to
have increased tensile strength of the set cement cylinders as tensile strength increases over
0% were observed for Samples 3 and . n addition, as further indicated in the table
above, th kaolin was not observed o have a positive impact on tensile strength.
Example 5
[0047] The following example was performed to evaluate the effect of the addition
of halloysite nanoiubes on a cement composition. n particular, the example evaluated the
compressi ve strength development of cement compositions comprising halloysite nanoiubes.
[0048] For this example, portions of Samples 1-3 from Example 1 were used. As set
fo rt above, each sample composition had a density of . lb/ al and comprised Portland
Class G cement in an amount of 0% bwoc, water n an amount of 5.09 gal/sic, and a
e dispersing agent (CF 3 cement friction reducer) in an amou t of 0.2% b oc
Sa ple wa a control and di not include a tensile strength enhancer. Sample 2 further
included glass fibers (WeilLife* 34 Additive), in an amount of 1.0% bwoc, as a tensile
strength enhancer. Sample 3 included halloysUe nanotubes (Signa A d eh Co. LLC),
amou t of 0%bwoc, as a tensile strength enhancer.
[0049] After preparation, the compressive strength over t m was determined for
each sample cement composition using an Ultrasonic Cement Analyzer UCA , available
from Pan instrument Company, Houston, IX, n the UCA, the sample cement
compositions were cured at 0 F while maintai e at 3000 psi. The results from the CA
tests are set forth below.
TABLE S
[0050] As indicated in the able above, Sample 3 with the haSloysite nanotubes did
not exhibit a significant impact on compressive strength development as compared Sample I
(control) and Sample 2 containing th glass fibers.
[005 It should be understood that the compositions and methods are described in
terms of "comprising," "containing," o "including" various components or steps, the
compositions and methods can also "consist essentially of or "consist of the various
components and steps. 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 t introduces.
[0052] For the sake of brevity, only certain ranges are explicitly disclosed herein.
However, ranges fro any lower limit may be combined with any upper limit to recite a
range not explicitly recited, as well as, ranges from any lower limit may be combined with
any other lower limit to recite a range not explicitly recited, in the same way, ranges from
any upper limit ma be combined with any other upper limit to recite a range not explicitly
recited. Additionally, whenever a numerical range with a lower limit and an upper limit is
disclosed, any number and any included range felling within the range are specifically
disclosed. n particular, ever range of values (of the form, "from about a to about b, or
equivalently, "from approximately a to b, or, qt valen y, "from approximately a- )
disclosed herein is to be understood to set forth every number and range encompassed within
the broader range of values eve if not explicitly recited. Thus, every point or individual
value may serve as ts own lower or upper limit combined with any other point or individual
value or any other lower or upper limit, to recite a range no explicitly recited.
[0053] Therefore, the present invention is well adapted to attain the ends a d
advantages mentioned as well as those thai 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 h the art having the benefit of
the teachings herein. Although individual embodiments are discussed, the invention covers
al combinations of all those embodiments. Furthermore, no limitations are intended t the
details of construction or design herein shown, other than as described in the claim below.
Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly
and clearly defined by the patentee. t 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, if there is any conflict in the
usages of a word or term in this specification and one or more paterst(s) or other documents
that may be incorporated herein by reference, the definitions that are consistent w t this
specification should be adopted.

What is claimed is:
1. A method of cementing comprising:
providing an aqueous dispersion comprising deagglomerated inorganic
nanotubes and water;
preparing a cement composition using the aqueous dispersion; and
allowing the cement composition to set.
2. The method of claim i wherein the deagglomerated inorganic nanotubes
were deagglomerated by a process comprising u o ca n mixing n a magnetically
assisted fluidized bed, stirring in a supercritical fluid, or magnetically assisted impaction
mixing,
3. The method of claim wherein the aqueous dispersion is an ultrasonicated
aqueous dispersion further comprising a dispersing agent.
4. The method of claim wherein the dispersing agent is present in the aqueous
dispersion in an amount in a range of from about 1% to about 20% b weight of the
inorganic nanotubes, and wherein the dispersing agent comprises at least one component
selected from the group consisting of an anionic polymer comprising a carboxylic group, an
anionic polymer comprising a sulfonate group, a comb/benched p y arboxylate ether, a
fatty acid, noleic acid, stearic acid, a sulfonated water-soluble anionic polymer, polystyrene
sulfonate, a polyethylene glycol, eth len oxide/propyiene oxide block copolymer, polyvinyl
alcohol, and any combination thereof
5. The method of claim 1 wherein the deagglomerated inorganic nanotubes
comprise at least one material selected from the group consisting of a metal oxide, a sulfide,
a selenide, an a um nos icate, and any combination thereof.
6 The method o claim 1 wherein the deagglomerated inorganic nanotubes
comprise at least one aluminosilicate selected fro the group consisting of halloysite,
imogo!ite, cylindrite, boulangeriie, an any combination thereof
7. The method of claim f further comprising introducing the cement
composition into a subterranean formation.
8 . The method of claim i wherein the cement composition s used i primary
cementing.
9. The method o claim wherein the aqueous dispersion comprising the
deagglomerated inorganic nanotubes was stored for at least Ί day prior to preparing th
cement composition.
10. A method of cementing comprising:
providing an ultrasonicated aqueous dispersion comprising deagglomerated
nanoparticies, a dispersing agent, and water;
preparing a cement composition usin the aqueous dispersion;
introducing the cement composition into a subterranean formation; and
allowing the cement composi tion to set
11. The method of claim 0 wherein the deagglomerated nanoparticies comprise
at least one material selected from the group consisting of nano-c ay, nano-hydraulie cement,
nano s ica nan -al n i a, ano- ri nc oxide, nano-boron, nano-iron oxide, and combinations
thereof.
12. The method of claim wherein the deagglomerated nanoparticies comprise
inorganic nanotubes.
13, The method of claim wherein the inorganic nanotubes comprise at least
on material selected fro the group consisting of a metal oxide, a sulfide, a se!emde, an
aluminosUicate, and any combination thereof.
4 , The method of claim wherein the inorganic nanotubes comprise a least
ne aluminas] I ca e selected from the grou consisting of a oys e, imogolite, yl ndrite,
boulange e, and any combination thereof
15. The method of claim 12 wherein the inorganic nanotubes comprise
halloysife,
16. The method of claim wherein the inorganic nanotubes have a diameter of
less than about 300 nanometers and a length in a range of from about 500 nanometers to
about 10 microns.
17 . The method of claim 12 wherein he inorganic nanotubes have a diameter in
a range of f om about 30 nanometers to about 70 nanometers, a length in a range of from
about micron to about 3 microns.
18. The method of claim 10 wherein the dispersing agent is present in the
aqueous dispersion in an amount in a range of fr o about % to about 20% by weight of the
nanoparticies, and wherein the dispers ing agent comprises at least one component selected
from the group consisting of an anionic polymer comprising a carboxylic group, an anionic
polymer comprising a sulfonate group, a comb/branched polyearboxylate ether, a fatty acid,
linoleic acid, stearic acid, a sulfonated water-soluble anionic polymer, polystyrene sulfonate,
a polyethylene glycol, ethylene oxide/propylene oxide block copolymer, polyvinyl alcohol,
and any combination thereof
19. The method of claim 10 wherein at least about 50% of the deagglomerated
nanoparticies are in the f rm of individual nanoparticies.
20. The method of claim 0 wherein th ultrasonieated aqueous dispersion was
prepared by a process comprising trasoni ation for a period of time in a range of from
about minutes to about I hour..
21. The method of claim 20 wherein the ultrasonieated aqueous dispersion was
prepared fa a process further comprising stirring the ultrasonieated dispersion for period of
time in range of 1 minute to about ! hour after the step of ukrasonlcation.
22. The method of claim 20 wherein deagglomeration of th inorganic
nanoparticles increases the Brazilian tensile strength of the cement composition by at least
about 25% as measured aft e a period of n a range of from about 24 hours to about 9 hours
when compared to use of the inorganic nanoparticles without deagglomeration.
23. The method of claim 10 wherein the deagglomerated nanoparticles are
present n the cement composition in an amount range of from about 0.01% t about %
fa weight of hydraulic ce ent the cement composition further comprising the hydraulic
cement
24 The method of claim wherein the cement composition is used i primary
cementing.
25. The method of claim if) further comprising introducing the cementing
composition into a well-bore annulus between a wall of a well bore and a conduit locat n
the well bore.
26. A method of cementing comprising:
providing a cement composition comprising a cement, deagglomerated
halloysite .nanotubes, a dispersing agent, and water, wherein deagglomerated halloysite
nanotubes comprise halloysite nanotubes having a diameter in a range of from about I
nanometer to about 300 nanometers and length in a range of from about 500 nanometers to
about microns;
introducing the cement composition into a subterranean formation; and
allowing the cement composition to set such tha the cement composition
after setting for a period i a range of from about 24 hours to about 72 hours has a tensile
strength that is increased by at least 25% when compared to the same cement composition
without deagglomeration of the halloysite nanotubes,
.27. The method of claim 26 wherein the dispersing agent comprises at least onecomponent
selected from the group consisting of an anionic polymer comprising a
earboxyiie group, an anionic polymer comprising a sulfonate group, a comb/branched
polycarboxylate ether, a fatty acid, tinoleic acid, stearic acid, a sulfonated water-soluble
anionic polymer, polystyrene sulfonate, a polyethylene glycol, ethylene oxk e pr py ene
oxide block copolymer, polyvinyl alcohol, and an combination thereof.
28. The method of claim 26 wherein at least about 50% of the deagg!omerated
ha! oysi e i anot i e are in the form of individual haUoysite nanot es.
29 The method of clai 26 wherein deagglomeration of th halloysite nanotubes
increases the Brazilian tensile strength of the cement composition by at least about 25% as
measured after a period of in a range of from about 24 hours to about 96 hours.
30. The method of claim 2 wherein the cemem composition is used in primary
cementing,
1. A cement composition comprising;
a cement;
deagg ome t d inorganic nanotubes; and
water.