SETTABLE COMPOSITIONS COMPRISING CEMENT KILN UST AND R CE
HUSK ASH AND METHODS OF US
BACKGROUND
[0001] The present invention relates to cementing operations and, ore particularly
in certain embodiments, to methods and compositions that comprise cement ki n dust
'C ' and rice husk ash.
[0002] In cementing methods, such as well construction and remedial cementing,
sellable compositions are commonly utilized. As used herein, the term "sellable
composition *' refers to composition(s) that hydraulica!ly sets or otherwise develops
compressive strength Sellable compositions may be used n primary cementing operations
whereby pipe strings, suc h as casing and liners, are cemented in well bores. In performing
primary cementing, a setiabie composition may be pumped i to an a nu us between a
subterranean formation and the pipe string disposed in the subterranean formation. Th
setiabie composition should set in the annulus, thereby forming an annular sheath of
hardened cement {e.g., a cement sheath) that should support and positio the pipe siring in
the we l bore and bond the exterior surface of the pipe string to the wails of the well bore.
Sellable compositions also may be used i remedial cementing methods, such a the
placement of cement plugs, and in squeeze cementing tor sealing voids in a pipe string,
cement sheath, gravel pack, formation, and the like.
[000:3] Setiabie compositions used heretofore commonly comprise Portland cement.
Portland cement generally is a major component of the cost for the sellable compositions.
To reduce the cost of such setiabie compositions, other components may be included in the
setiabie composition in addition to or in place of, the Portland cement. Such components
may include fly ash, s ag cement, shale, metakaolm, micro-fine cement, and the like. "Fly
ash," as that term is used herein, refers to the residue from the combustion of powdered or
ground coal, wherein the fly ash carried by the flue gases may be recovered, for example, by
electrostatic precipitation. "Slag " as that term is used herein, refers to a granulated, blast
furnace by-product formed in the production of east iro and generally comprises the
oxidized impurities found in iron ore. Slag cement generally comprises slag and a base, for
example, such as sodium hydroxide, sodium bicarbonate, sodium carbonate, or lime, to
produce a sellable composition that, whe combined with water, may se to fo rm a hardened
mass.
SUMMARY
[0004] The present invention relates to cementing operations and, more particularly,
i certain embodiments, to methods and compositions that comprise C D and rice husk ash.
[0005] An embodiment provides a method of cementing comprising: placing a
settabie composition into a subterranean formation, the settabie composition comprising
cement kiln dust, rice husk ash, and water; and allowing the settabie composition to set
[0006] Another embodiment provides a method of cementing comprising; placing a
settabie composition into a subterranean formation, the settabie composition comprising
cement kiln dust, rice husk ash, Portland ce e t, and water; and allowing the settabie
compost tion to set.
[0007] Another embodiment provides a method of cementing comprising: placing a
settabie composition into a subterranean formation, th settabie composition comprising:
cement kiln dust, rice husk ash, and water, wherein the cement kil dust is present in an
amount in a range of from about 50% to about 80% by weight of the cement kiln dust and
the ri e husk ash, wherein the rice husk ash is present i an amount in a range of from about
20% to about 50% by weight of the cement kiln dust and the ric hus ash, wherein the water
is present in an amount i a range of from about 40% to about 200% by weight of the cement
kiln dust and the riee husk ash, wherein the settabie coniposiiioii is essentially free of
Portland cement; and allowing the settabie composition to set
[0008] Another embodiment provides a settabie composition comprising: cement
kiln dust; riee husk ash; and water
[0009] The features and advantages of the present invention wil be readily apparent
to those skilled in the art While numerous changes may be made by those skilled in the art,
such changes are within the spirit of the invention.
DETAILED DESCRIPTION
[00 10 The present invention relates to cementing operations and, more particularly,
in certain embodiments, to methods and compositions thai comprise CKD a d rice hus ash.
There may be several potential advantages to the methods and compositions of the present
invention, onl so e of which ma be alluded to herein. O e of the many potential
advantages of embodiments of the present invention s that inclusion of rice husk ash in
sellable compositions comprising C D may improve the mechanical properties of the CRDcontaining
settable compositions. By way of example, inclusion of rice husk ash may
provide increased compressive strength fo settable compositions comprising CKD, Another
potential advantage of embodiments of the present invention is that the CKD and/o rice
husk ash may be used to reduce the cost of the settable compositions. For example, use of
waste CKD and/or rice husk ash to replace a higher cost component, such as Portland
cement, should result in a more economical seitable composition.
[0 ] Embodiments of the settable compositions of the present invention may
comprise CKD, rice husk ash, and water. Other optional additives may also be included in
embodiments of the settable compositions as desired, including, but not limited to,
unexpanded periite, pum te, fly ash, slag cement, metakaolin, shale, zeolite, combinations
thereof, and the like. Embodiments of the settable compositions may also be foamed and/or
extended as desired by those of ordinary skill in the art. The settable compositions of the
present invention should have density suitable for a particular application as desired by
those of ordinary ski!! i the art, with the benefit of this disclosure. n som embodiments,
the settable compositions may have a density in the range of from about 8 pounds per gallon
pg") to about 16 ppg. n other embodiments, the settable compositions may be foamed to
a densit in the range of from about 8 ppg to about ppg,
[0 ] Embodiments of the settable compositions generally may comprise CKD. As
used herein, the term "CKD" refers to a partially calcined kiln feed which is removed from
the gas stream and collected, for example, in dust collector during the manufacture of
cement. Usually, large quantities of CKD are collected in th production of cement that re
commonly disposed of a waste. Disposal of the waste C .D can add undesirable costs to the
manufacture of the cement, as well as the environmental concerns associated with its
disposal. The chemical analysis of CKD from various cement manufactures varies
depending on a number of factors, including the particular kiln feed, the efficiencies of the
cement production operation, and the associated dust collection systems. CKD generally
may comprise variety of oxides, such as SK¾, Aivi¾, e C¾, CaO gO, S0 , a 0 , and
K .
0 ί 3] The C D generally may exhibit eemenlitious properties, n that it may set
and harden in the presence o water. n accordance with embodiments of the present
invention, the CKD ma be used, among other things, to replace higher cost ce e ti io s
components, such as Portland cement, resulting in more economical settable compositions,
n addition, substitution of the CKD for the Portland cement can result in a settable
composition with a reduced carbon footprint.
[0014] The CKD may be included i the settable compositions in an amount
sufficient to provide the desired compressive strength, density cost reduction, and/or
reduced carbon footprint. In so e embodiments, the CKD may be present i the settable
compositions of the present i ve tion in a n amount in the range of from about 0. % to about
99% by weight of cementitioiis components. Cementitious components include those
components or combinations o components of the settable compositions tha hydrau!ically
set, or otherwise harden, to develop compressive strength, including, for example, CKD, rice
husk ash, unexpended perlite, fly ash, purnicite, slag, lime, shale, and the like. The CKD
may be present, in ce rtain embodiments, in an amount ranging between any of and/or
including any of about 0.1%, about i%, about 5%, about %, about %, about 20%, about
25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%,
about 65%, about 0%, about 75%, about 80%, about 90%, about 95%, or about 99%. in
one embodiment, the CKD may be present in the settable compositions in an amount in the
range of from about 5% to about 95% by weight of cementitioiis components, n another
embodiment, the CKD may be present in an amount i the range of from about 50 to about
95% by weight of ee en i ou components. in yet another embodiment, the CKD may be
present in amount in the range of from about 50% to about 80% by weight of
eemeniitious components. On of ordinary skill in the art, wit the benefit of this disclosure,.
will recognize the appropriate amount of CKD to include for a chosen application.
[0015] Embodiments of the settable compositions generally may comprise rice husk
ash. As used herein, the term "rice husk" refers to the hard protective coverings of grains of
rice that are separated from the rice during production. Rice husks ar also commonly
referred to as rice hulls or rice shells. Large quantities of rice husks are typically generated
during the production of rice that are usually disposed of as waste. However, disposal of the
rice husks in landfills can be problematic as space in landfills ay b limited. The rice
husks typically contains a substantially amount of silica and when burned ield an ash.
referred to herein as "rice husk ash," which i rich In amorphous silica. In some
embodiment, the ash obtained from combustion of the rice husks may be further processed
by dry grinding the ash to a powder form.
[00 6 ] Addition of the rice h usk ash to sellable compositions comprising C D has
been shown to provide increases in compressive strength. In accordance with present
embodiments, the ric husk ash may be included in CKD-containing settable compositions to
increase the compressive strength thereof. By way of example, inclusion of the rice husk ash
in settable compositions comprising CKD may increase the compressive strength in an
amount greater than or equal to about % in one embodiment, greater tha or equal to about
25% in another embodiment, greater than or equal to about 50% in another embodiment, and
greater than or equal to about 75% in yet another embodiment, as compared to the same
settable composition that does not contain the .latex strength enhancer. As use herein,
"compressive strength" is measured at a specified time after th composition has been mixed
and the composition is maintained under specified temperature and pressure conditions. For
example, compressi ve strength can be measured at a time i the range of about 24 to about
48 hours after the composition is mixed and the composition is maintained at a temperature
of 0 P and atmospheric pressure. Compressive strength can be measured by either a
destructive method or non-destructive method. The destructive method physically tests the
strength of settable composition samples at various points in time by crushing the samples in
a compression-testing machine. The compressive strength is calculated from the failure load
divided by the cross-sectional area resisting the load and is reported in units of pound-force
per square inch (psi) Non-destructive methods typically may employ an Ultrasonic Cement
Anal zer (" CA ), available fro Fann Instrument Company, Houston, TX.
[00 ] in some embodiments, the rice husk ash may be present in the settable
compositions of the present invention in an amount i the range of from about 0.1% to about
99% by weight of cementitioos components. The rice husk ash may be present, in certain
embodiments, in m amount ranging between any of and/or including any of about 0 . ,
about 1%, about 5%, about %, about 5%, about 20%, about 25%, about 30%, about 35%,
about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about
75%, about 80%. about 90%, about 95%, or about 99%. n one embodiment, the rice husk
ash may be present in the settable compositions in a amount in th range of from about 5%
to about 95% by weight o f cementitioos components n another embodiment, the rice husk
ash ma be present i an amount in the range of from about 5% to about 50% by weight of
cementitious components. yet another embodiment, the rice husk ash may be present in
an amount in the range of from about 20% to about 50% by weight of cementitious
components. One of ordinary skill in the art, with the benefit of this disclosure, will
recognize the appropriate amount of rice husk ash to include or a chosen application.
[00 ] The water that may be used in embodiments o f the sellable compositions
includes, tor example, freshwater, saltwater (e.g., water containing one or more salts
dissolved therein), bri e (e.g., saturated saltwater produced from subterranean formations),
seawater, or combinations thereof. Generally, the water may be from any source, provided
that the water does not contain an excess of compounds that may undesirably affect other
components in th settable composition, in some embodiments, the water may be included
n an amount sufficient to form a punipable slurry. n some embodiments, the water .may be
included in the settable composiiions of the present invention in an amount in the range of
about 40% to about 200% by weight of ce entiti s components n some embodiments,
the water may be included in an amount in the range of about 40% to about 0% by weight
of cementittous components. One of ordinary skill n the art, with the benefit of this
disclosure, wi l recognize the appropriate amount of water to include for a chosen
application..
00 19] In some embodiments, the settable compositions may further comprise a
hydraulic cement A variety of hydraulic cements may be utilized in accordance with the
present invention, including, but not limited to, those comprising calcium, aluminum, silicon,
oxygen, iro , and/or sulfur, which set and harden by reaction with water. Suitable hydraulic
cements Include, but are no limited to, Portland cements, pozzolana cements, gypsum
cements, high alumina content cements, silica cements, and an combination thereof in
certain embodiments, the hydraulic cement may comprise a Portland cement n some
embodiments, the Portland cements that are suited for use i the present invention are
classified as Classes A, C, fi, and G cements according to American Petroleum Institute, .^/
Specification for Materials a/id Testingfor We l Cements, AP Specification , Fifth Ed.,
July , 90. In addition, in some embodiments, cements suitable for use in the present
invention may include cements classified as ASTM Typ , 1, or lit.
[0020] It should be understood that use of hydraulic cement in embodiments of the
settable compositions addition to the C D and/or rice husk ash can be reduced or even
eliminated to provide, for example, the desired cost savings and/or reduced carbon footprint.
Accordingly, embodiments of the settable compositions of the present invention may
comprise hydraulic cement in an amount of 0% to about 75%. For example, the hydraulic
cement may be present, in certain embodiments, in an amount ranging between any of and/or
including any of about 1%, about 5%, about 10%, about %, about 20%, about 24%, about
25%, about 30%, about 35%, about 40%, about 50%, about 55%, about 60%, about 65%,
about 0%, or about 75%. in an embodiment, the hydraulic cement may be present in an
amount in the range of from about 0% to about 20%. . n another embodiment, the hydraulic
e ay be present in an amount in the range of from about 0% to about 10%. to yet
another embodiment, the sellable compositions ay be essentially free of hydraulic cemen
A herein, the term "essentially free"' means tha hydraulic cement s ot present or to
the extent, that trace amounts of hydraulic cement may be present, is present in an amount
less than about 1% b weight of cementitious components. In certain embodiments, the
sellable composition may contain hydraulic cement in. an amount less than about 0.1 % by
weight o f cementitious components and, alternatively, ess than about 0.01% b weight of
cementitious components. By wa of example, the sellable composition, in certain
embodiments, ay be free of hydraulic cement, to that the sellable composition contains no
hydraulic cement,
[0021] Embodiments of the sellable compositions further may comprise a set
retarding additive. As used herein, the term "set retarding additive" refers t an additive that
retards the setting of the sellable compositions o the present invention. Examples of
suitable se retarding additives include, but are not limited to, ammonium, alkali metals,
alkaline earth metals, metal salts of suifoaikyialed lign ns, organic acids (e.g.,
hydroxycarboxy acids), copolymers that comprise acrylic acid or n a ei acid, and
combinations thereof. One example of a suitable s l a ylated ligniu comprises a
sulfomeihy lated gnin. Suitable set retarding additives are disclosed i more detail in
United States Patent No. Re. 31,190 the entire disclosure of which is incorporated herein
by reference. Suitable set retarding additives are commercially available from Halliburton
Energy Services, nc. under the trademarks R* 4, I * 5, R¾ , HR* 12, R* , ! ¾5,
HR*601, SCR.' 100, and SCR™ 500 retarders. Generally, where used, the set retarding
additive may be included in the sellable compositions of the present invention in a n amount
sufficient to provide the desired set retardation n so e embodiments, the set retarding
additive may be present in the sellable compositions of the present invention an amount in
the range of about 0.1% to about 5% by weight of cementitious components. One of
ordinary skill in the art, with the benefit of this disclosure, will recognize the appropriate
amount o f the set retarding additive to include for a chosen application.
[0022] Optionally, other additional additives ay be added to the sellable
compositions of the present invention as deemed appropriate by one skilled in the art, with
the benefit of this disclosure. 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, dispersants, d- loss-control additives, defbaming agents,
foaming agents, oi! swe!l b e particles, water-swei Sable particles, thixotropic additives, and
combinations thereof. Specific examples of these, and other additives include unexpended
perlite, pun te y ash, slag cement, metakaolin, shale, zeolite, crystalline silica,
amorphous silica, fumed silica, salts, fibers, hydraiabie clays, microspheres, elastomers,
elastomeric particles, resins, latex, combinations {hereof, and the l ke. A perso having
ordinary skill in the art, with the benefit of this disclosure, will readily be able to determine
the type and amount of additive useful for a particular application and desired result
[0023] In some embodiments, the CKD and the rice husk ash may be combined to
for a cementitious component In addition to the CKD and rice husk ash, additional
components may also be included in the cementitious component as filler or for other
purposes as will be apparent to one of ordinary skill in the art with the benefit of this
disclosure. For example, other components that may set and harden in the presence o f water
can a so be included n the cementitious component, n some embodiments, the cementitious
component further may comprise unexpanded perlite, pumicite, fly ash, slag cement
metakaolin, shale, zeolite, or combinations thereof. In some embodiments, the cementitious
component may be placed in a bag or other suitable container for storage and/or delivery to a
well site, i an embodiment, the cementitious component may then b combined with water
t create a settable composition.
[0024] i some embodiments, the components of the settable compositions may be
combined n any order as will be appreciated by those of ordinary skill i the art. n one
embodiment the CKD and rice husk ash may be combined with water to create a settable
composition. As will be appreciated, on or more additional components as described
above, for example, may also be included in the settable composition. The components of
the settable composition may be combined using any mixing device compatible with the
composition as known to one of ordinary skill in the art, for example a bulk mixer.
[0025] As will be appreciated by those of ordinary skill in the art. embodiments of
the settable compositions may be used in a variety of subterranean applications, including
primary and remedial cementing. Embodiments of the settable compositions may be
introduced into a subterranean formation and allowed to set therein. For example, the
settable composition may e placed into a space between a subterranean formation and a
conduit located in the subterranean formation. As used herein, introducing the settable
composition into a subterranean formation includes introduction into an portion of the
subterranean formation, including, without limitation, into a well bore drilled into the
subterranean formation, into a near well bore region surrounding the well bore, or into both.
[0026] n primary cementing embodiments, for example, a settable composition may
be introduced into a space outside a conduit (e.g., pip strings, liners) located in the
subterranean formation. The conduit may be located in a well bore drilled into the
subterranean formation,. The settable composition may be allowed to set to form an annular
sheath of hardened cement in the space outside conduit. Among other things, the set settable
composition may form a barrier, preventing the migration of fluids in the well bore. The set
settable composition also may, for example, support the conduit in the well bore.
[0027] In remedial cementing embodiments, a settable composition may be used, for
example, in squeeze-cementing operations or in the placement of cement plugs. By way of
example, the settable composition may b placed in a well bore to plug a void or crack in the
formation, in gravel pack, in the conduit, in the cement sheath, and/or a microannulus
between the cement sheath and the conduit
[0028] To facilitate a better understanding of the present invention, the following
example of certain aspects of some embodiments is given. In no way should the following
example be read to limit, or define, the scope of the invention.
EXAMPLE
[0029] A series of .sample settable compositions were prepared and tested to analyse
the force resistance properties of settable compositions that comprise CKD and rice husk; ash.
The sample compositions were allowed to cure in a water bath at 6 ' for 24 hours at
ambient pressure. Immediately after removal from the water bath, crush strengths
(destructive compressive strengths) were determined using a Tinius O sen tester. The results
of the crush strength tests are set forth in the table below.
[0030] Ten different tests wer conducted, designated Test Nos. 1-10, using the
indicated amounts of water, CKD, r c husk ash, hydraied li e, and cement dispersant. The
amounts of these components are indicated in the table be!ow with percent by weight ( by
wt") indicating the percent of the component by weight of the cement and rice husk ash. The
amount of r ce husk ash was varied i an amount ranging f om 0% to 50% by weight. Tests
1 and 5 were comparative tests that did not include any rice husk ash. The dispersant used
was CF -3 cement friction reducer, from Halliburton Energy Services, Inc., Duncan,
Oklahoma. Th CKD used was supplied by oieem (US) nc., from Ada, Oklahoma. The
rice husk ash use was supplied by Rice!and Foods, nc., Stuttgart,, Arkansas, and had
particles ranging from about 1 micron to about 1 microns.
TABLE I
Crush Strength Tests
24-Hr
Rice sk Hydrate Crush
Test Water CKD Ash Lime (% Dispersant Strength
No ( by wt) ( by wt) (% by wt) by wt) (% by wt) (psi)
1 48.75 00 _, 0.75
[00 ] This example thus indicates that inclusion o f the rice husk ash provides
strength enhancement to CKD-coniaining compositions, indeed, increases in compressive
strength of 50% or more were obtained for Tests No. 6-1.0 having a density of 1.2.5 ppg and
containing rice husk ash in an amount ranging fro 20% to 50% by weight, as compared o
Test No, 5 that did not contain any rice husk ash.
[0032] it should be understood that the compositions and methods arc described n
terms of "comprising," "containing" or "including" various components or steps, the
composition s and methods can also "consist essentially of or "consist of the various
components a d steps
[0033] For the sake of brevity, only certain ranges are explicitly disclosed herein.
However, ranges from a y lower limit ma be combined w th 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 may 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 is specifically
disclosed. In particular, every range of values (of the form, "from about a to about b, or,
equivalently, "from approximately a to , or, equiva!ently, "from approximately a-b")
disclosed herein is to be understood to set forth every number and range encompassed within
the broader range of values even f not explicitly recite. Thus every point or individual
value may serve as s own lower or upper limit combined with any other point or individual
value or any other lower or upper limit, to recite a range not explicitly recited,
[0034] 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 o
the teachings herein. thou h individual embodiments are discussed, the invention covers
all combinations of all those embodiments. Furthermore, no limitations are intended to the
details of construction or design herein shown, oilier than as described in the claims below.
Also, th 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 he present invention.
What is claimed is:
. A method of cementing comprising;
placing a sellable composition into a subterranean formation, the sellable
composition comprising cement kiln dost, rice husk ash, and water; and
a owing the sellable composition to set,
2. The method of claim ί whereiti th settabie composition has a density in a
range of from ab ut pounds per gallo to about pounds per gallon,
3. The method of claim 1 wherein the cement kiln dust is present in an amount
in a range of from about 0. 1% to about 99% by weight of cementitious components, and
wherein the rice hus ash s present i an amount in a range of from about 0.1% to about
99% by weight of cementitious components.
4 The ethod of claim i wherein the cement kiln dust is present in an amount
in a range o ro about 50% to about 95% by weight of cementitious components,
5. The method of claim 1 wherein the r ce husk ash i present in an amount n a
range of from about 5% to about 50% by weight of cementitious components.
6. The method of claim 1 wherein the r ce husk ash is included n the settabie
composition in an amount sufficient to increase the 24-hour destructive compressive strength
of the settabie composition at 60°F and atmospheric pressure n an amount equal to or
greater than about %.
7. The method of clai 1 wherein the rice husk ash is included i the settabie
composition in an amount sufficient t increase the 24-hour destructive compressive strength
of the settabie composition at I60°F and atmospheric pressure in an amount equal to or
greater than about 75%.
8. The method of claim i wherein the water is present in an amount in a range
of from about 40% to about 200% by weight of cementitious components,
9 . The method of claim 1 wherein the settabie composition is essentially free
hydraulic cement in addition to the cement kiln dust,
. The method of claim 1 wherein th settabie composition further comprises a
set. retarding additive,
. The method of claim wherein the settabie composition further comprises at
least one additive selected from the group consisting of unexpanded per!ite, pumicite, lime,
fly ash, slag cement, metakaolin, shale, zeolite, crystalline silica, amorphous silica, fumed
silica, salt, fiber, hydraiahle clay, microsphere, elastomer, elastomeric particle, resin, latex,
and any combination thereof.
. The method of claim 1 wherein the settable composition further comprises at
least o e additive selected from the group consisting of strength-retrogression additive, a
set accelerator, a weighting agent, a lightweight additive, a gas-generating additive, a
mechanical property enhancing additive, a ost c r tion material, a filtration-control
additive, a dispersant, a fluid-loss-control additive, a defoaming agent, a foaming agent, an
oi swe abSe particle, a water-swel!ahle particle, a thixoiropic additive, and any combination
thereof.
3 . The method of claim 1 wherein the settable composition is allowed to set in
an annulus outsid a conduit disposed in the subterranean formation,
14. The method of claim ! wherei the settable composition is used in primary
cementing.
15. The method of claim I wherein the settable composition i used in remedial
cementing.
. A method of cementing comprising;
placing a settable composition into a subterranean formation, the settable
composition comprising cement kiln dust, rice hus ash, Portland cement, and water; and
allowing the settable composition to set.
17. The cementitious component of claim 16 wherein the cement kiln dust is
present in an amount n a range of from about 0.1% to about 99% by weight of cementittous
components, and wherein the rice- husk ash is present in an amount in a range of from about
0. % to about 99% by weight ofcementitious components.
18. The cementittous component of claim 16 wherein the cement kiln dust is
present in an amount in a range of front about 0.1% to about 50% by weight of cementitious
components, wherein the rice husk ash is present in an amount in a range of from about 0.1%
to about 50% by weight of cementitious. components, and wherein the Portland ceme t is
present in an amount in a range of from about 50% to about 99% by weight ofcementitious
components.
19. The method of claim 1 wherein the settable composition further comprises
at least one additive selected -from the group consisting of unexpanded per!ite, pumicite,
lime, fly ash, slag cement, metakaoiin. shale, zeolite, crystalline silica, amorphous silica,
fumed silica, sa t fiber, hydraiable clay, microsphere, elastomer, elastomerie particle, resin,
latex, and any combination thereof.
20. The method of claim 16 wherein the settable composi tion further comprises
at least one additive selected from the group consisting of strength-retrogression additive, a
set accelerator, a weighting agent, a lightweight additive, a gas-generating additive, a
mechanical property enhancing additive, a lost-circulation material, a filtration-control
additive, a dispersant, a d-Jos ontro additive, a defpaming agent, a foaming agent, an
oil-swellab!e particle, a waier-swe!lab!e particle, a thixotropic additive, a d any combination
thereof.
2 A method of cementing comprising;
placing a settable composition i to a subterranean formation, the settable
composition comprising:
cement k n dust,
rice husk ash, and
water.
wherein the cement kiln dust is present in an amount in a range o
from about 50% to about 80% by weight of the cement kiln dost and the rice husk ash,
wherein the rice husk ash is present in an amount in a range o from
about 20% to about 50% by weight of the cement kiln dust and the rice husk ash,
wherein the water is present i an amount i a range of from about
40% to about 200% by weight of the cement kiln ust and the rice husk ash,
wherein the settable composition is essentially free o f Portland
cement; and
allowing the settable composition to set.
22. The method of claim 2 1 wherein the settable composition has a density in a
range of from about 8 pounds per gallon to about 1.6 pounds per gallon.
23. The method of claim wherein inclusion of the rice husk ash in the settable
composition increases the 24-hour destructive compressive strength of the settable
composition at 0 F and atmospheric pressure in an amount equal to or greater than about
10%.
24. The method of claim 2 1 wherein inclusion of the rice husk ash in the settable
composition increases the 24-hour destructive compressive strength of the settable
composition at ? 0 ad atmospheric pressure in an amount equal to or greater than about
75%.
25, The method of claim 2 1 wherein the settable composition further comprises a
set retarding additive.
26. The method of claim 2 1 wherein the settable composition farther comprises
at least one additive selected from the group consisting of unexpended pcr Si te , pumiciie,
lime, fly ash, slag cement, metakaotm, shale, zeolite, crystalline silica, amorphous silica.
filmed silica, salt, fiber, hy ratab e clay, microsphere, elastomer, elastomeric particle, resin,
latex, and any combination thereof.
27. The method of claim wherein the sellable composition further comprises
at least one addit e selected from the group consisting of a strength-retrogression addit e, a
set accelerator, a weighting agent, a lightweight additive, a gas-generating additive, a
mechanical property enhancing additive, lost-circulation material a filtration-control
additive, a dispersant, a fl id os -contro additive, a defoammg agent, a foaming agent, art
oil-swell able particle, a water-swellable particle, a ih o ropi additive, and any combination
thereof.
28. The method of claim 2 wherein the .settable composition is allowed to set in
an annu s outside a conduit disposed in the subterranean formation
29, The method of claim 2 1 wherein the settable composition is used in primary
cementing.
30 The method of claim 2 1 wherein the settable composition is used in remedial
cementing,
. A settable composition comprising:
cement kiln dust;
rice husk ash: a d
water.
32. The settable composition of claim 3 wherein the cement ki n dust Is present
in an amou in a range of .from about 0.1% to about 99% by weight of cemeniitious
components, and wherein the rice husk ash is present i an amount in a range of from about
0. % to about 99% by weight of cementitious components.