CEMENT COMPOSITIONS AND METHODS OF USING THE SAME
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part application of U.S.
patent application Ser. No. 13/107,055, entitled "Settable Compositions
Containing Metakaolin Having Reduced Portland Cement Content," filed on May
13, 2011, the entire disclosure of which is incorporated herein by reference.
BACKGROUND
[0002] The present invention relates to cement compositions suitable
for use in subterranean operations. More specifically, the present invention
relates to cement compositions resistant to degradation in carbon dioxide
containing zones and their use in subterranean cementing operations.
[0003] During the construction of a well, such as an oil and gas well, a
hydraulic cement is typically placed into the annular space between the walls of
the well bore penetrating a subterranean formation and the exterior surface of
the well bore casing suspended therein. Such cement compositions have also
been placed into the annular space between the walls of concentric pipes, such
as a well bore casing and a liner suspended in the well bore. Following
placement of the cement composition, further operations in the well bore, such
as drilling, may be suspended for a time sufficient to permit the cement to set to
form a mass of hardened cement in the annulus. The annular mass of hardened
cement is referred to in the art as the "sheath." The cementing procedure
resulting in the initial construction of the sheath is often referred to as the
primary cementing operation.
[0004] The function of a cement sheath may include providing physical
support and positioning of the casing in the well bore, bonding of the casing to
the walls of the well bore, preventing the movement of fluid (liquid or gas)
between formations penetrated by the well bore, and preventing fluid from
escaping the well at the surface of the formation. The set cement sheath should
be able to endure a number of stresses during various downstream operations
after the primary cementing operation.
[0005] In practice, a cement sheath may be compromised due to
numerous stresses that may cause the cement sheath to fail resulting in a loss
of hydraulic seal. In addition to physical stresses such as pressure and shear,
conventional cementing materials may be susceptible to chemical alteration. For
example, a typical hydraulic cement composition may suffer from carbonization
in C0 2 rich zones. Portland-based cements, in particular, may contain hydrated
cement phases that may readily react with C0 2 to form calcite, dolomite, and
amorphous silica gel. Such chemical changes may negatively affect the porosity,
density and texture of the cement sheath and may affect the sheath's
mechanical and hydrologic properties. Moreover, such chemical degradation
processes may compound problems arising from the physical stresses on the
cement sheath, which in turn may compromise the sheath's hydraulic seal.
[0006] The hydraulic seal that the cement sheath provides may be
particularly important in maintaining zonal isolation. If the seal becomes
compromised, inter-zonal communication may lead to oil and gas flowing to
lower pressure zones within the well rather than being directed into the wellbore
for production. Loss of seal integrity may also lead to water production or
annular pressure build up. Any of these occurrences may require expensive
remedial services and/or may even result in the well being shut down in order to
comply with regulatory procedures.
SUMMARY OF THE INVENTION
[0007] The present invention relates to cement compositions suitable
for use in subterranean operations. More specifically, the present invention
relates to cement compositions resistant to degradation in carbon dioxide
containing zones and their use in subterranean cementing operations.
[0008] I n some embodiments, the present invention provides methods
comprising introducing cement compositions into subterranean formations,
wherein the cement compositions comprise aluminosilicates, at least one of a
sodium aluminate and a calcium aluminate, and water, and the methods
comprising allowing the cement compositions to set to provide set cement
sheaths, wherein the set cement sheath is resistant to degradation to corrosive
components within the subterranean formation
[0009] In some embodiments, the present invention provides cement
compositions comprising aluminosilicates, at least one of a sodium aluminate
and a calcium aluminate, and water, wherein the cement composition does not
include Portland cements.
[0010] In some embodiments, the present invention provides methods
comprising introducing cement compositions into subterranean formations,
wherein the cement compositions comprise a metakaolin, a secondary pozzolan
additive, at least one of a sodium aluminate and a calcium aluminate, and water,
and the methods comprising allowing the cement compositions to set to provide
set cement sheaths, wherein the set cement sheaths do not contain Portland
cements.
[0011] The features and advantages of the present invention will be
readily apparent to those skilled in the art upon a reading of the description of
the preferred embodiments that follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The following figures are included to illustrate certain aspects of
the present invention, and should not be viewed as exclusive embodiments. The
subject matter disclosed is capable of considerable modifications, alterations,
combinations, and equivalents in form and function, as will occur to those skilled
in the art and having the benefit of this disclosure.
[0013] FIG. 1 is a thickening time chart for an exemplary cement
composition, in accordance with embodiments disclosed herein.
[0014] FIG. 2 is a thickening time chart for another exemplary cement
composition, in accordance with embodiments disclosed herein.
[0015] FIG. 3 is a thickening time chart for yet another exemplary
cement composition, in accordance with embodiments disclosed herein.
DETAILED DESCRIPTION
[0016] The present invention relates to cement compositions suitable
for use in subterranean operations. More specifically, the present invention
relates to cement compositions resistant to degradation in carbon dioxide
containing zones and their use in subterranean cementing operations.
[0017] The present invention provides methods and compositions for
cementing well bores that may prevent or reduce the effects of chemical
alteration of a set cement sheath when exposed to various chemical agents.
Portland cements are prone to attack by corrosive chemicals such as inorganic
salts, carbon dioxide / carbonic acid hydrogen chloride and hydrogen sulfide
present in the subterranean formation. For example, carbon dioxide and
carbonic acid can attack Portland cements and conver the calcium hydroxide into
calcium carbonate and/or calcium bicarbonate. Dissolution and leaching of
calcium bicarbonate may increase porosity and/or permeability thereby
decreasing overall mechanical strength of the cement sheath. Such occurrence
may lead to inefficient zonal isolation and, in extreme cases, complete failure of
the cement composition.
[0018] Carbon dioxide containing subterranean formations may exist
naturally and the cement compositions disclosed herein may be useful in primary
cementing operations to provide a set cement sheath that may be chemically
resistant to carbon dioxide-induced chemical degradation C0 2-containing zones.
The compositions of the present invention may also be beneficially employed in
remedial cementing operations as well, with similar resistance to chemical
stresses.
[0019] Moreover, because the cement composition of the present
invention resists degradation from carbon dioxide, not only is the integrity of the
cement itself improved, but C0 2-vunerable materials inside the sheath, such as
reinforcing rods (rebar), also benefit from the protection.
[0020] Advantageously, cement compositions of the present invention
may provide a complete replacement for the use of Portland cement without
compromising the required compressive and shear bond strength of the set
cement sheath. Cement compositions and methods of the invention may be
employed in any application which indicates the use of a robust cement that is
resistant to carbonization or other chemical reactivity associated with
conventional hydraulic cements. Other advantages of the methods and
compositions disclosed herein will be recognized by those skilled in the art.
[0021] I n some embodiments, the present invention provides methods
comprising introducing cement compositions into subterranean formations,
wherein the cement compositions comprise aluminosilicates; an aluminate
selected from the group consisting of sodium aluminate, calcium aluminate,
potassium aluminate, and a combination thereof; and water, the methods
further comprising allowing the cement compositions to set to provide set
cement sheaths, wherein the set cement sheath is resistant to degradation to
corrosive components within the subterranean formation. In particular
embodiments, the base cement composition consists essentially of
aluminosilicates combined with an aluminate selected from the group consisting
of sod ium aluminate, calci um aluminate, potassi um aluminate, and a
combination thereof. Without bei ng bou nd by theory, the particu lar absence of
Portla nd-based cements in cement compositions of the invention impart
resista nce to C0 2-based deg radation in the set cement. In some embod iments,
resista nce to deg radation incl udes resista nce to corrosive components incl uding,
without limitation, carbon dioxide, hydrogen sulfide, hydrogen chloride, carbon ic
acid, and mixtu res thereof. In some embod iments, Portland-based cements are
absent from cement compositions of the invention
[0022] As used herei n, " resistant to deg radation" refers to the relative
lack of reactivity of the set cement sheath upon exposu re to chem ica l attack, in
particu la r, attack by carbon dioxide and/or carbon ic acid . "Resista nt to
deg radation," may also include relative inertness to other chem ical stresses on
the set cement sheath such as inorga nic salts, hydrogen chloride, and hydrogen
sulfide. " Deg radation" encom passes any alteration in the chem ica l structu re of
the set cement sheath lead ing to comprom ised set cement sheath integ rity as it
relates to porosity, textu re, compressive or shea r strength, abil ity to maintai n
hydra ulic sea l, and other factors appa rent to those ski lled in the art.
[0023] Methods employi ng cement compositions of the invention may
incl ude primary cementi ng operations, multi-stage cementi ng operations and
remed ia l (seconda ry) cementi ng operations such as plug- back cementi ng,
squeeze cementi ng, and packer squeeze cementing . Other operations that may
incl ude introd uci ng cement compositions of the invention into a subterra nea n
formation incl ude subterra nea n storage of carbon dioxide, which may provide a
means of safe storage of this green house gas and cement- based haza rdous
material seq uestration with underg rou nd storage where the set cement may be
exposed to carbon dioxide- rich envi ronments.
[0024] Another exam ple of a method of the present invention is a
method of cementi ng a cond uit (e.g., casi ng, expanda ble casi ng, liners, etc. )
disposed in a subterra nean formation . An exam ple of such a method may
comprise introd ucing a cement composition comprisi ng aluminosi licates, an
aluminate selected from the grou p consisti ng of sod ium aluminate, calci um
aluminate, potassi um aluminate, and a combination thereof, and water into the
annulus between the cond uit and the subterra nea n formation ; and allowing the
cement composition to set in the annu lus to form a hardened mass. General ly,
the hardened mass shou ld fix the condu it in the formation . The method may
commence, for example, by introd uci ng the cond uit into the subterra nea n
formation . As desi red by one of ord inary ski ll in the art, with the benefit of this
disclosu re, embod iments of the cement compositions of the present invention
usefu l in this method may comprise any of the add itives descri bed herei n below,
as wel l as any of a variety of other add itives suita ble for use in subterra nea n
appl ications.
[0025] Another exam ple of a method of the present invention is a
method of seal ing a portion of a gravel pack or a portion of a subterranea n
formation ; that is, a non-a nnu lar use. An example of such a method may
comprise introd ucing a cement composition comprisi ng aluminosi licates, an
aluminate selected from the grou p consisti ng of sod ium aluminate, calci um
aluminate, potassi um aluminate, and a combination thereof, and water into the
portion of the gravel pack or the portion of the subterra nean formation ; and
allowi ng the cement composition to form a hardened mass in the portion . The
portions of the subterra nea n formation may incl ude permea ble portions of the
formation and fractu res (natu ral or otherwise) in the formation and other
portions of the formation that may allow the undesi red flow of f luid into, or from,
the wel l bore. The portions of the gravel pack may incl ude those portions of the
gravel pack, wherei n it is desi red to prevent the flow of f luids into, or out of, the
wel l bore. Among other thi ngs, this method may allow the sea ling of the portion
of the gravel pack to prevent the flow of f luids without req uiri ng the gravel
pack's remova l.
[0026] Another exam ple of a method of the present invention is a
method of seal ing voids located in a cond uit (e.g., casi ng, expanda ble casi ngs,
liners, etc. ) or in a cement sheath . Genera lly, the condu it may be disposed in a
wel l bore, and the cement sheath may be located in the annu lus between the
cond uit and a subterranean formation . An example of such a method may
comprise introd ucing a composition comprisi ng aluminosi licates, an aluminate
selected from the grou p consisti ng of sodi um aluminate, calcium aluminate,
potassi um aluminate, and a combination thereof, and water into the void ; and
allowi ng the cement composition to set to form a hardened mass in the void . As
desi red by one of ord inary ski ll in the art, with the benefit of this disclosu re,
embod iments of cement compositions of the present invention usefu l in this
method may comprise any of the add itives descri bed herei n below, as wel l any
of a variety of other add itives suita ble for use in subterranea n appl ications.
[0027] When sealing a void in a conduit, in some embodiments
methods of the present invention may further comprise locating the void in the
conduit; and isolating the void by defining a space within the conduit in
communication with the void, wherein the cement composition may be
introduced into the void from the space. The void may be isolated using any
suitable technique and/or apparatus, including bridge plugs, packers, and the
like. The void in the conduit may be located using any suitable technique known
in the art. When sealing a void in the cement sheath, the methods of the
present invention, in some embodiments, further may comprise locating the void
in the cement sheath; producing a perforation in the conduit that intersects the
void; and isolating the void by defining a space within the conduit in
communication with the void via the perforation, wherein the cement
composition is introduced into the void via the perforation. The void in the
conduit may be located using any suitable technique. The perforation may be
created in the conduit using any suitable technique, for example, perforating
guns. The void may be isolated using any suitable technique and/or apparatus,
including bridge plugs, packers, and the like.
[0028] Another example of a method of the present invention is a
method of forming a plug in a well bore. An example of such a method may
include introducing a cement composition comprising aluminosilicates, an
aluminate selected from the group consisting of sodium aluminate, calcium
aluminate, potassium aluminate, and a combination thereof, and water into the
well bore at a location in the well bore; and allowing the cement composition to
set to form the plug in the well bore. The plug may be formed, for example,
when plugging and abandoning the well or to form a kickoff plug when changing
the direction of drilling the well bore. An example of changing the direction of
drilling a well bore may comprise introducing a cement composition comprising
aluminosilicates, an aluminate selected from the group consisting of sodium
aluminate, calcium aluminate, potassium aluminate, and a combination thereof,
and water into the well bore at a location in the well bore wherein the direction
of drilling is to be changed; allowing the cement composition to set to form a
kickoff plug in the well bore; drilling a hole in the kickoff plug; and drilling of the
well bore through the hole in the kickoff plug. As desired by one of ordinary skill
in the art, with the benefit of this disclosure, embodiments of the cement
compositions of the present invention may comprise any of the additives
described herein, as well as any of a variety of other additives suitable for use in
subterranean applications.
[0029] The various components and optional additives useful in
practicing methods of the invention are now described herein below.
"Aluminosilicate," as used herein, refers to a mineral comprising of aluminum,
silicon, and oxygen, plus any requisite countercations to make up charge.
Aluminosilicates useful in methods of the invention may include kaolin, calcined
kaolin (i.e. metakaolin), class C fly ash, class F fly ash, pumice, oil shale ash,
vitrified shale ash, zeolite, granulated blast furnace slag and other clay minerals,
such as naturally occurring andalusite, kyanite, and sillimanite. In some
embodiments, aluminosilicates employed in cement compositions disclosed
herein are substantially dehydrated aluminosilicates. In some embodiments,
aluminosilicates employed in cement compositions disclosed herein are calcined.
As used herein, "calcined" or the process "calcination," refers to aluminosilicates
that have been sufficiently thermally heated to remove hydroxyl groups from the
aluminosilicates in the form of water. Thus, calcination refers to a process that
removes additional water beyond the adsorbed water of hydration. I n some
preferred embodiments, metakaolin may be used. In some embodiments,
methods of the invention employ an aluminosilicate comprising metakaolin in
conjunction with other aluminosilicates. I n some embodiments, SATINTONE®
(calcined aluminosilicate available from BASF®) may be used in cement
compositions of the invention.
[0030] Aluminosilicates form the bulk material in cement compositions
of the invention and they may be present in cement compositions in an amount
ranging from a lower limit of about 10% to an upper limit of about 60% by
weight of the cement composition, and wherein the percentage of
aluminosilicates may range from any lower limit to any upper limit and
encompass any subset between the upper and lower limits. Some of the lower
limits listed above are greater than some of the listed upper limits, one skilled in
the art will recognize that the selected subset will require the selection of an
upper limit in excess of the selected lower limit.
[0031] In some embodiments, methods of the invention employ a
cement composition comprising an aluminate selected from the group consisting
of sodium aluminate, calcium aluminate, potassium aluminate, and a
combination thereof. These additives may be employed to control free water,
promote early strength development, prevent cement fallback, and control fluid
migration during primary cementing applications, for example. They may also
be used to accelerate a cement slurry at low temperatures and impart
thixotropy. These reagents may also improve compressive-strength
development in the nascent set sheath and may provide control of settling in a
cement slurry. VERSASET ® is an example of a sodium aluminate commercially
available from Halliburton Energy Services.
[0032] In some embodiments, methods of the invention employ a
cement composition comprising an aluminate selected from the group consisting
of sodium aluminate, calcium aluminate, potassium aluminate, and a
combination thereof. The amount of sodium aluminate is less than or equal to
28% by weight of the aluminosilicates. The amount of calcium aluminate ranging
from a lower limit of about 20% to an upper limit of about 80% by weight of the
aluminosilicates, and wherein the percentage of calcium aluminate may range
from any lower limit to any upper limit and encompass any subset between the
upper and lower limits. The amount of potassium aluminate ranging from a
lower limit of about 20% to an upper limit of about 80% by weight of the
aluminosilicates, and wherein the percentage of potassium aluminate may range
from any lower limit to any upper limit and encompass any subset between the
upper and lower lim. Some of the lower limits listed above are greater than
some of the listed upper limits, one skilled in the art will recognize that the
selected subset will require the selection of an upper limit in excess of the
selected lower limit.
[0033] In some embodiments, water used in cement compositions of
the invention may comprise fresh water, saltwater (e.g., water containing one or
more salts dissolved therein), brine (e.g., saturated saltwater), seawater, or
combinations thereof, and may be from any source, provided that they do not
contain components that might adversely affect the stability and/or performance
of the cemented well bore.
[0034] In some embodiments, methods of the invention may employ
additional additives in the cement compositions as deemed appropriate by one
skilled in the art, with the benefit of this disclosure. Examples of such additives
include, inter alia, fly ash, silica, fluid loss control additives, surfactants,
dispersants, accelerators, retarders, salts, mica, fibers, formation-conditioning
agents, bentonite, cement kiln dust (CKD), expanding additives, microspheres,
weighting materials, defoamers, and the like. For example, the cement
compositions of the present invention may be foamed cement compositions
comprising one or more foaming surfactants that may generate foam when
contacted with a gas, e.g., nitrogen. An example of a suitable fly ash is an
ASTM class F fly ash that is commercially available from Halliburton Energy
Services of Dallas, Texas under the trade designation "POZMIX® A." An
example of a suitable expanding additive comprises deadburned magnesium
oxide and is commercially available under the trade name "MICROBOND HT"
from Halliburton Energy Services, Inc., at various locations.
[0035] I n some embodiments methods of the invention employ cement
compositions further comprising catalysts to accelerate setting of the cement
compositions. Such compounds may be employed to modulate effects of cement
retardants. Catalysts to accelerate setting of the cement compositions may
include inorganic or organic catalysts. Suitable inorganic catalysts include,
without limitation, salts of chloride, carbonate, silicates, aluminates, nitrates,
sulfates, thiosulfates, phosphates like sodium hexametaphosphate, and
ammonium hydroxide. In some embodiments inorganic catalysts that are salts
of chloride, such as calcium chloride and sodium chloride, may be preferred.
Suitable organic catalysts include, without limitation, calcium formate,
ammonium formate, oxalic acid, and triethanolamine. When present, such
catalysts may be present in an amount ranging from a lower limit of about 0.1%
to an upper limit of about 10% by weight of the aluminosilicates, and wherein
the percentage of catalyst may range from any lower limit to any upper limit and
encompass any subset between the upper and lower limits. Some of the lower
limits listed above are greater than some of the listed upper limits, one skilled in
the art will recognize that the selected subset will require the selection of an
upper limit in excess of the selected lower limit.
[0036] In some embodiments, methods of the invention employ cement
compositions further comprising fluid loss additives. Suitable fluid loss additives
may include particulate materials including, without limitation, bentonite,
microsilica, asphalt, thermoplastic resins, latex, and the like. Other suitable fluid
loss additives may include any water-soluble high molecular weight material
such as naturally occurring polymers, modified naturally occurring polymers,
synthetic polymers, and the like. Such polymers include, without limitation,
cellulose derivatives such as hydroxyethyl cellulose (HEC), carboxymethyl
cellulose (CMC), and carboxymethyl hydroxyethyl cellulose, acrylamide-acrylic
acid copolymers (AM/AA), such as acrylamide-sodium acrylate copolymer, binary
acrylamide-vinyl imidazole copolymer, ternary acrylamide-2-acrylamido-2-
methylpropane sulfonic acid-imidazole copolymer, N,N-dimethylacrylamide-2-
acrylamido-2-methylpropane sulfonic acid copolymer, acrylic acid-2-acrylamido-
2-methylpropane sulfonic acid copolymer, diallyldimethylammonium chloride-2-
acrylamido-2-methylpropane sulfonic acid copolymer, and vinyl pyrrolidone
copolymers. When present, fluid loss additives may be present in an amount
ranging from a lower limit of about 0.5% to an upper limit of about 5% by
weight of the aluminosilicates, and wherein the percentage of fluid loss additive
may range from any lower limit to any upper limit and encompass any subset
between the upper and lower limits. Some of the lower limits listed above are
greater than some of the listed upper limits, one skilled in the art will recognize
that the selected subset will require the selection of an upper limit in excess of
the selected lower limit.
[0037] I n some embodiments, methods of the invention employ cement
compositions further comprising a cement retarder. As used herein, the term
"cement retarder" refers to an additive that retards the setting of the cement
compositions of the present invention. Suitable cement retarders include,
without limitation, citric acid, citric acid derivatives, such as sodium citrate,
phosphonic acid, phosphonic acid derivatives, such as sodium phosphate,
lignosulfonates, salts, sugars/carbohydrate compounds, such as celluloses
exemplified by carboxymethylated hydroxyethylated celluloses, organic acids,
synthetic co- or ter-polymers comprising sulfonate and carboxylic acid groups,
and/or borate compounds. Examples of suitable borate compounds include,
without limitation, sodium tetraborate and potassium pentaborate. Examples of
suitable organic acids include, without limitation, gluconic acid, citric acid and
tartaric acid. Commercially available cement retarders, include, without
limitation, those available from Halliburton Energy Services, Inc. (Duncan, OK)
under the trademarks HR® 4, HR® 5, HR® 7, HR® 12, HR® 15, HR® 25, HR® 601,
SCR™ 100, and SCR™ 500 retarders.
[0038] Generally, the cement retarder may be present in the cement
compositions used in the present invention in an amount sufficient to delay the
setting of the cement composition in a subterranean formation for a desired
time. More particularly, the cement retarder may be present in the cement
compositions used in the present invention in an amount ranging from a lower
limit of about 0.1% to an upper limit of about 10% by weight of the
aluminosilicates, and wherein the percentage of cement retarder may range
from any lower limit to any upper limit and encompass any subset between the
upper and lower limits. Some of the lower limits listed above are greater than
some of the listed upper limits, one skilled in the art will recognize that the
selected subset will require the selection of an upper limit in excess of the
selected lower limit. In certain embodiments, the cement retarder may be
present in the cement compositions used in the present invention in an amount
ranging from a lower limit of about 0.5% to an upper limit of about 4% by
weight of the aluminosilicates, and wherein the percentage of cement retarder
may range from any lower limit to any upper limit and encompass any subset
between the upper and lower limits. Some of the lower limits listed above are
greater than some of the listed upper limits, one skilled in the art will recognize
that the selected subset will require the selection of an upper limit in excess of
the selected lower limit.
[0039] In some embodiments, methods of the invention employ cement
compositions further comprising a dispersant. When present, the dispersant,
among other things, may control the rheology of the cement composition and
stabilize the cement composition over a broad density range. A variety of
dispersants known to those skilled in the art may be used in accordance with the
present invention. An example of a suitable dispersant comprises a watersoluble
polymer prepared by the caustic-catalyzed condensation of formaldehyde
with acetone wherein the polymer contains sodium sulfate groups, which
dispersant is commercially available under the trade designation "CFR-3™"
dispersant from Halliburton Energy Services, Inc. (Duncan, OK). Another
suitable dispersant is commercially available under the trade designation "CFR-
2™" dispersant, also from Halliburton Energy Services, Inc. When used, the
dispersant may be present in the cement compositions of the present invention
in an amount ranging from a lower limit of about 0.1% to an upper limit of about
5.0% by weight of the aluminosilicates, and wherein the percentage of
dispersant may range from any lower limit to any upper limit and encompass
any subset between the upper and lower limits. Some of the lower limits listed
above are greater than some of the listed upper limits, one skilled in the art will
recognize that the selected subset will require the selection of an upper limit in
excess of the selected lower limit. In some embodiments, the dispersant may
be present in the cement compositions of the present invention in an amount
ranging from a lower limit of about 0.1% to an upper limit of about 3.0% by
weight of the aluminosilicates, and wherein the percentage of dispersant may
range from any lower limit to any upper limit and encompass any subset
between the upper and lower limits. Some of the lower limits listed above are
greater than some of the listed upper limits. One skilled in the art will recognize
that the selected subset will require the selection of an upper limit in excess of
the selected lower limit.
[0040] Cement compositions suitable for use in the present invention
may be foamed or non-foamed. In some embodiments, methods of the
invention may employ cement compositions further comprising a defoamer. An
example of a suitable defoamer is commercially available from Halliburton
Energy Services, Inc., of Duncan, Okla., under the trade name D-AIR 3000L™
antifoaming agent. When present, the defoamer may be present in an amount
ranging from a lower limit of about 0.1% to an upper limit of about 1.0% by
weight of the aluminosilicates, and wherein the percentage of antifoaming agent
may range from any lower limit to any upper limit and encompass any subset
between the upper and lower limits. Some of the lower limits listed above are
greater than some of the listed upper limits, one skilled in the art will recognize
that the selected subset will require the selection of an upper limit in excess of
the selected lower limit.
[0041] I n some embodiments, the cement compositions employed in
methods of the present invention may be foamed cement compositions
comprising one or more foaming surfactants that may generate foam when
contacted with a gas, e.g., nitrogen. As will be understood by one of skill in the
art, foamed cement compositions may be indicated where a formation is
relatively weak and a lighter weight set cement sheath is desired. When
present, foaming surfactants may be present in an amount ranging from a lower
limit of about 0.1% to an upper limit of about 1.0% by weight of the
aluminosilicates, and wherein the percentage of foaming surfactant may range
from any lower limit to any upper limit and encompass any subset between the
upper and lower limits. Some of the lower limits listed above are greater than
some of the listed upper limits, one skilled in the art will recognize that the
selected subset will require the selection of an upper limit in excess of the
selected lower limit.
[0042] In some embodiments, methods of the invention employ cement
compositions further comprising a weighting agent. Suitable weighting agents
may include, without limitation, barite, precipitated barite, submicron
precipitated barite, hematite, ilmentite, manganese tetraoxide, galena, and
calcium carbonate. The weighting agent may be present in the cement
composition in an amount sufficient for a particular application. For example,
the weighting agent may be included in the cement composition to provide a
particular density. In certain embodiments, the weighting agent may be present
in the cement composition in an amount up to about 70% by volume of the
cement composition (v%) {e.g., about 5%, about 15%, about 20%, about 25%,
about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about
60%, about 65%, up to about 70%). In certain embodiments, the weighting
agent may be present in the cement composition in an amount ranging from a
lower limit of about 10% to an upper limit of about 40% by weight of the
aluminosilicates, and wherein the percentage of weighting agent may range from
any lower limit to any upper limit and encompass any subset between the upper
and lower limits. Some of the lower limits listed above are greater than some of
the listed upper limits, one skilled in the art will recognize that the selected
subset will require the selection of an upper limit in excess of the selected lower
limit. By way of example, the cement composition may have a density of
greater than about 9 pounds per gallon ("lb/gal")- In certain embodiments, the
cement composition may have a density of about 9 lb/gal to about 22 lb/gal.
[0043] In some embodiments, the present invention provides a method
comprising introducing a cement composition into a subterranean formation,
wherein the cement composition comprises a metakaolin, a secondary pozzolan
additive, an aluminate selected from the group consisting of sodium aluminate,
calcium aluminate, potassium aluminate, and a combination thereof, and water,
and the method further comprising allowing the cement composition to set to
provide a set cement sheath, wherein the set cement sheath does not contain a
Portland cement. I n some such embodiments, methods of the invention may
employ a cement composition further comprising one or more of a catalyst to
accelerate setting of the cement composition, a fluid loss additive, a cement
retarder, a dispersant, a defoamer, and a weighting agent.
[0044] I n some embodiments, the cement composition comprises a
metakaolin, a secondary pozzolan additive, an aluminate selected from the
group consisting of sodium aluminate, calcium aluminate, potassium aluminate
and a combination thereof, and water. In some embodiments, the cement
composition consists essentially of a metakaolin, a secondary pozzolan additive,
an aluminate selected from the group consisting of sodium aluminate, calcium
aluminate, potassium aluminate, and a combination thereof, and water. I n
some preferred embodiments, the cement composition does not include Portland
cement.
[0045] In some embodiments, the cement composition comprises an
alumincosilicate, an aluminate selected from the group consisting of sodium
aluminate, calcium aluminate, potassium aluminate, and a combination thereof,
and water. In some embodiments, the cement composition consists essentially
of an alumincosilicate, an aluminate selected from the group consisting of
sodium aluminate, calcium aluminate, potassium aluminate, and a combination
thereof, and water. In some preferred embodiments, the cement composition
does not include Portland cement.
[0046] In some embodiments, the cement composition comprises an
aluminate selected from the group consisting of sodium aluminate, calcium
aluminate, potassium aluminate, and a combination thereof, and water. I n
some embodiments, the cement composition consists essentially of an aluminate
selected from the group consisting of sodium aluminate, calcium aluminate,
potassium aluminate, and a combination thereof, and water. I n some preferred
embodiments, the cement composition does not include Portland cement.
[0047] In some embodiments, the present invention provides a cement
composition comprising aluminosilicates, at least one of a sodium aluminate and
a calcium aluminate, and water, wherein the cement composition does not
include a Portland cement. Cement compositions of the invention may further
comprise a catalyst to accelerate setting of the cement composition, a fluid loss
additive, a cement retarder, a dispersant, a defoamer, and/or a weighting agent
as described herein above. In some embodiments, the cement compositions of
the invention may further comprise silica fume, diatomaceous earth, granulated
blast furnace slag, pumice, and calcined shale. In some embodiments, the
cement compositions of the invention may employ a mixture of aluminosilicates
that is metakaolin and fly ash. Any of the aforementioned additives may be
employed in any combination as would be evident to those skilled in the art.
[0048] In some embodiments, the present invention provides cement
compositions consisting essentially of aluminosilicate, at least one of a sodium
aluminate and a calcium aluminate, and water. Other embodiments of the
present invention may provide methods of subterranean cementing operations
using a cement composition that consists essentially of aluminosilicate, at least
one of a sodium aluminate and a calcium aluminate, and water.
[0049] To facilitate a better understanding of the present invention, the
following examples of preferred or representative embodiments are given. In no
way should the following examples be read to limit, or to define, the scope of the
invention.
EXAMPLE
[0050] This Example shows the preparation and characterization of a
variety of cement compositions useful in the practice of methods of the
invention.
[0051] Cement compositions in Table 1 below were prepared according
to the following general procedure: Metakaolin, POZMIX A and other solid
additives were dry blended. D-Air 3000L was added into water and then the dry
blend was suspended to form slurry according to API procedure 10B-2.
[0052] Metakaolin is a pozzolanic material. It is a chemical phase that
forms upon thermal treatment of kaolinite. Kaolinite's chemical composition is
AI20 3:2Si02 2H20 and as a result of thermal treatment the water is driven away
to form an amorphous aluminosilicate called metakaolin. POZMIX A (Fly ash) is
a residue from the combustion of coal, which exhibits pozzolanic properties.
Versaset is a sodium aluminate commercially available from Halliburton Energy
Services. Secar 60 is a calcium aluminate commercially available from
Halliburton Energy Services. SHMP is sodium hexametaphosphate and is used
as an accelerator). Alcomer is a fluid loss control additive which is an
amphoteric copolymer comprising diallyldimethylammonium chloride and 2-
Acrylamido-2-methylpropane sulfonic acid commercially available from BASF
chemical company. HR-800 is a acyclic oligosaccharide type, non-lignin based
cement retarder commercially available from Halliburton Energy Services. HR-
800 was added as a material diluted with gypsum in a 2 : 1 ratio. CFR-3 is a
dispersant commercially available from Halliburton Energy Services. D-Air
3000L is a defoamer commercially available from Halliburton Energy Services.
Each of the designs below had a slurry composition density of 13.5 ppg.
Table 1.
[0053] The rheology of the slurries was measured using Fann 35
viscometer at speeds of 3, 6, 30, 60, 100, 200, 300, and 600 rpm. The slurries
were thin and pourable, indicating pumpability through a well bore. Table 2,
below, shows the results for Design 1, in particular.
Table 2. (Rheology of Design 1)
[0054] The slurries were tested for thickening time at 165°F BHCT
(Bottom Hole Circulation Temperature) using HPHT consistometer according to
API standard procedure. The thickening time was 3 to 12 hours depending on
the composition of the slurry (Table 3 and Figures 1-3).
[0055] The thickening time refers to the time required for the
composition to achieve 70 Bearden units of Consistency (Be). Consistency is a
measure of the pumpability of cement slurry measured in Bearden units (Be),
and when a cement slurry reaches a Consistency of 70 Be, it is no longer
considered a pumpable slurry.
[0056] The slurries were poured in the mold and cured at 180°F BHST
(Bottom Hole Static Temperature) at 3000 psi. The cured cubes were crushed
using a hydraulic press to estimate the strength. The compositions develop the
strength of about 600 psi within 16 hours and it increases with time (Table 3).
Table 3.
[0057] The slurry design 1 was cured at 180°F, 3000 psi for 7 days. The
cured cylinder was exposed to carbon dioxide at 200°F for 30 days. The crush
strength of the cylinder after exposing to carbon dioxide was 3040 psi.
[0058] 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, combined, or modified and all such variations are considered within the
scope and spirit of the present invention. The invention illustratively disclosed
herein suitably may be practiced in the absence of any element that is not
specifically disclosed herein and/or any optional element disclosed herein. While
compositions and methods are described in terms of "comprising," "containing,"
or "including" various components or steps, the compositions and methods can
also "consist essentially of" or "consist of" the various components and steps.
All numbers and ranges disclosed above may vary by some amount. 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. I n
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. Also, the terms in the claims
have their plain, ordinary meaning unless otherwise explicitly and clearly defined
by the patentee. 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. If there is any conflict in the usages of a word or term in this
specification and one or more patent or other documents that may be
incorporated herein by reference, the definitions that are consistent with this
specification should be adopted.
CLAIMS
The invention claimed is:
1. A method comprising:
introducing a cement composition into a subterranean formation having
corrosive components therein, wherein the cement composition comprises:
an aluminosilicate;
a sodium aluminate, a calcium aluminate, a potassium aluminate,
or a combination thereof; and
water; and
allowing the cement composition to set to provide a set cement sheath;
wherein the set cement sheath is resistant to degradation from the
corrosive components within the subterranean formation.
2. The method of claim 1, wherein the corrosive components comprise
one selected from the group consisting of carbon dioxide, hydrogen sulfide,
hydrogen chloride, carbonic acid, and mixtures thereof.
3. The method of any of the preceding claims, wherein the cement
composition further comprises: a catalyst to accelerate setting of the cement
composition, a fluid loss control additive, a cement retarder, a dispersant, a
defoamer, a weighting agent, or a combination thereof.
4. The method of any of the preceding claims, wherein the cement
composition further comprises a fluid loss control additive comprising a
copolymer of diallyldimethylammonium chloride and 2-Acrylamido-2-
methylpropane sulfonic acid.
5. The method of any of the preceding claims, wherein the
aluminosilicate is a metakaolin.
6. The method of any of the preceding claims, further comprising a
pozzolan selected from the group consisting of fly ash, silica fume, granulated
blast furnace slag, pumice, and calcined shale.
7. A cement composition comprising:
an aluminosilicate;
a sodium aluminate, a calcium aluminate, a potassium aluminate, or a
combination thereof; and
water;
wherein the cement composition does not include a Portland
cement.
8. The method of claim 7, wherein the cement composition further
comprises one or more of a catalyst to accelerate setting of the cement
composition, a fluid loss control additive, a cement retarder, a dispersant, a
defoamer, and a weighting agent.
9. The method of claim 7 or 8, wherein the cement composition
further comprises a fluid loss control additive comprising a copolymer of
diallyldimethylammonium chloride and 2-Acrylamido-2-methylpropane sulfonic
acid.
10. The cement composition of claim 7, 8, or 9, wherein the
aluminosilicate is a metakaolin.
11. The cement composition of claim 7, 8, 9, or 10, further comprising
a pozzolan selected from the group consisting of fly ash, silica fume, granulated
blast furnace slag, pumice, and calcined shale.
12. A method comprising:
introducing a cement composition into a subterranean formation, wherein
the cement composition comprises:
a metakaolin;
a secondary aluminosilicate;
a sodium aluminate, a calcium aluminate, a potassium aluminate,
or a combination thereof; and
water; and
allowing the cement composition to set to provide a set cement sheath;
wherein the set cement sheath does not contain a Portland cement.
13. The method of claim 12, wherein the cement composition further
comprises one or more of a catalyst to accelerate setting of the cement
composition, a fluid loss control additive, a cement retarder, a dispersant, a
defoamer, and a weighting agent.
14. The method of claim 12 or 13, wherein the cement composition
further comprises a fluid loss control additive comprising a copolymer of
diallyldimethylammonium chloride and 2-Acrylamido-2-methylpropane sulfonic
acid.
15. The cement composition of claim 12, 13, or 14, wherein the
aluminosilicate is a metakaolin.
16. The cement composition of claim 12, 13, 14, or 15, further
comprising a pozzolan selected from the group consisting of fly ash, silica fume,
granulated blast furnace slag, pumice, and calcined shale.