CA2888162A1

CA2888162A1 - Methods for determining reactive index for cement kiln dust, associated compositions, and methods of use

Info

Publication number: CA2888162A1
Application number: CA2888162A
Authority: CA
Inventors: Ronnie G. Morgan; D. Chad Brenneis; Craig W. Roddy
Original assignee: Halliburton Energy Services Inc
Current assignee: Halliburton Energy Services Inc
Priority date: 2012-10-26
Filing date: 2013-10-25
Publication date: 2014-05-01
Anticipated expiration: 2033-10-25
Also published as: MX2015004677A; EP2912137A4; IN2015DN03329A; CA2888162C; AR093112A1; CN104812868B; AU2013334222A1; EP2912137A1; MY174637A; AU2013334222B2; WO2014066737A1; RU2629028C2; RU2015113607A; BR112015008990A2; CN104812868A

Abstract

A variety of methods and compositions are disclosed including a method for treating a well comprising providing a treatment fluid comprising a base fluid and a blended cementitious component, wherein the blended cementitious component comprises kiln dust from two or more different sources; and introducing the treatment fluid into a well bore, wherein the kiln dust comprises a first kiln dust from a first source and a second kiln dust from a second source, and wherein the first kiln dust and the second kiln dust have different reactive indexes.

Description

iMETLIODS FOR DETERMINING REACTIVE INDEX FOR CEMENT KILN
.DUST, ASSOCIATED COMPOSITIONS, AND METHODS OF USE
BACKGROUND
[00011 The .present invention relates to -cementitious components and, More particularly, in certain embodiments, to methods of .determining a reactive index for cementitious components, [00021 In general, well treatments include a Wide variety of methods that may be performed in oil, gas, geothermal and/or water weiis. such Its driilingcompletio.n. and -workover Methods.. The drillingõeOmpletion and-workoVer.melhods May include, but are not 10. limited to, drilling, .fracturingnacidizing, logging, cementing, gravel packing, perforating and conformance methods, :Many Of these Well treat-runts are designed to enhance.
and/or facilitate the recovery of desirable fluids from a subterranean well. These fluids may include hydrocarbons such as oil andlotgas.
10003.] in cementing methodsõ such as well construction and remedial cementing, settable compositions are Commonly utilized. As used herein,. the term "settable composition" refers to .a 'compOsieton(S) that hydraulically Sets aIr otherWise develops compressive strength Senable.compositions may be used in primary cementing operations whereby pipe strings, Such as casing. .and liners, are cemented in well bores in performing primary cementing, a. sellable composition may be pumped into an annulus between .subteuTanean formation and the pipe string dispOSed in the subterranean formation or between :the pipe. string and a larger conduit disposed in the subterranean -formation. The settable composition should. set in the annulus, thereby forming an annular sheath of hardened. cement .(04., a ceraerit sheath) that -should support and position the pipe string in the well bore:and bond the exterior surface. of the pipe string to. the walls of the well bore or

2..5 to the larger conduit. Settable compositions also may be used in remedial cementing methods, such as the placement of cement plugs, and in squeeze cementing for sealing voids in a pipe string, cement:sheath, gravel pack, formation, and the like.
.Settable compositions may also be used in surface .applications, for-example, construction cementing.
1.000411 Settable compositions for use in subterranean formations may typically include a ccmentitious.compottent which hydraulically sets, of otherwiSehardens,.to develop compressivestrength.. Examples of cementitious components that can be included in .settable compositions include Portland cement,. calcium. MultiMate cement, cement kiln dust,. lime kiln dust, fly ash, slag, pumice, and rice-hull ash, among others. The performance of these differeacementitions components in settable compositions may vary and can even vary fOr a particular ce-mentitions component depending, tbrexampIe, on the particular type or-source of the, component. For example, -certain of these cementitious components may have undesitabla properties that can make them unsuitable for use in well treatments. In addition, variation of the performance tbr the cementitions components can lead to lack .of predictability and consistency for the cementitious components when used in treatment fluids This lack of predictability consistency nlay even be apparent for the same cementitious.componcnt, for example, if sourced from different locations..

SUMMARY
[00051 The present invention relates to cenientitious components and, more particularly; in certain embodiments, to methods of determining a reactive index for cern en t it i ous coin ponentS.
100061 An embodiment disci ose5 :a method of treating a Well comprising:
providing a treatment fluid comprising a hase fluid and a Wended cementitious component, wherein the blended cementitious component comprises kiln dust from two or more different sources;
and introducing the treatment fluid into a well bore.
[0007] Another embodiment discloses a method of cethenting comprising:
providing agettable composition comprising water and a blended eementitious component, wherein the blended een-wntitioos component comprises kiln dust from two pr moiv different sources and allowing the set-table Composition to set to fbrm a hardened mass.
[0008] Another embodiment discloses a method of cementing comprising:
providing a settable composition comprising water and a blended cementitious component, wherein the blended cementitious component comprises kiln dust :and an additional cementitious component, the kiln dust and the additional cementitious component each have a determined reactive index; and allowing the settable composition to set to form a hardened mass.
[0009] Another embodiment discloses a method Of preparing a blended cementitious component comprising: providing a first kiln dust, the first kiln dust being from a first source; providing a second kiln dust, the second kiln dust being from A second source; and blending at least the first kiln dust and the second kiln dust to form the blended cementitious component [0010] Another embodiment discloses a method of measuring ;reactivity of a kiln dust comprising: measuring a parameter of the kiln dust, the kiln dust having a specific surface area; and dividing the measured parameter by the specific SUrfaCe area of the kiln dust to obtain a reactive index for the kiln dust [0011] Another embodiment discloses a well treatment fluid comprising: a base fluid; and a blended cementitious component comprising kiln dust from two or more different sources.
[0012] The features and advantages of the present invention will be readily apparent to those skilled in the art. While numerous changes may be made by thoSe skilled in the art, such changes are within the:spirit of the invention.

3 BRIEF DESCRIPTION OF THE DRAWINGS
[0013] These drawings illustrate certain aspects of some of the embodiments of the present invention,, and should not be used to limit or define the invention, [0014] FIG, 1 is a chart showing measured reactive indexes for various supply Sources Of cement kiln dust, [0015] FIG. 2 is a chart Comparing actual versus predicted compressive strength for dry blends of cement kiln dust.
[0016] FIG. 3 is a chart comparing actual versus predicted volume average apparent viscosity at 51 I see for dry blends of cement kiln dust, [0017] FIG, 4 is a chart comparing actual verSos predieted volume average apparent viscosity at 51 sec for dry blends of cement kiln dust

4 DESCRIPTION OF PREFERRED EnRommENTs [0018] The present invention relates: to. cementitious components and, more particularly. M certain embodiments, to methods of determining a reactive index: .for cementitious components, By determining the reactive index for cementitious components, blends of cementitions components may be used. in well treatments., according to particular embodiments, that can provide more predictable and consistent performance. in addition, additional embodiments may include using the determined reactive index to provide blend of .cementitions components in which one or more.. parameters have been optimized, including compressive .strength, Young'S Modulus,. fluid logs, and/or thickening time, for example,.
[00191 Without being limited by theory, the reactive index of a cementitious component may be referred to as a measure.of the eementitious component's reactivity as adjusted for differences. in ..surfilet area. Example techniques for determining the reactive index may comprise measuring a parameter of the cementitious component, and then dividing the measured parameter by the specific surface area of the cementitious component.
In some embodiments, the reactive index for a cementitious component may be calculated in accordance with the following ovation:
= MP / SSA
wherein RI is the reactive index, MP is the measured parameter of the cementitious component, and SSA is the specific surface area. of the eementitiouseomponent In general, specific surface area is a property Oa particulate solid and, as used herein, is defined as the total surface area of the .cementitious component divided by the mass of the cementitious component or the total surface .area divided by the bulk volume of the cementitious component.
[00201 in general, ceinentitiouS. components are particulate: solids that hydraulically :set, .or otherwise harden to develop compressive strength in the presence of Water. Non-limiting examples of cementitious components that may be suitable for use in embodiments .of the present invention include Portland cements, calcium aleminatee, gypsum, pozzolanic materials., and kiln dust. Mixtures of one or more ditit.rent cementitious components may also be .used, In some embodiments, the cementitious. component may be combined with lime.
[0021] in some .einbodiments,:the teinentitions component may comprise Portland cement. Portland cement is a commonly used .cementitious component that hydraulically reacts with water to develop compressive strength. Example Of suitable Portland cements

5 may include thoSe classified as Classes A, C C and H cements according to American Petroleum institutc.õ4JI SpoijkiviOt for Materiais ond TagiOg (e.M.014, API
Specification 10, Fifth Edition, July I, 1990. In addition, Portland eetnents suitable for use in embodiments of the present invention may also include those classified as ASTM Type I, VII, 11,114 IV, or V> In some embodiments:, blends of cementitious 001'min:owls containing Portland cement may be used, [00221 In some embodiments, the cementitious component may comprise a calcium aluminate. Calcium aluminate may hydraulically react with water to develop compressive strength. Calcium aluminate may be included in cements commonly referred to as Calcium aluminate :cements or high alumina content cements. calcium aluminate cements my prepared in a manufacturing process that includes mixing a calcium bearing material limestone) and an aluminum-hearing material (e.gõ bauxite).
[0023] In some embodiments, the Comentitious component may Comprise gypsum Gypsum is 0 material that sets in the presence of water to develop compressive P4rength, Gypsum may be included in cements commonly referred to as gypsum cements. For use in cements, gypsum may, in some instances, be burned at eXtremely high temperatures and then ground, in particular embodiments, gypsum may be added to Portland cement.
[90241 In some embodiment's, the eementitious eoniponent may Comprise a poz2olanic material. Pozzolanic materials that may be suitable for use include a wide variety of natural or artificial materials that exhibit cementitious properties in the presence of calcium hydroxide. Examples of suitable pozzolanic material that may be suitable for use in embodiments of the present invention include natural and artificial pozzolans, such as fly ash, silica fume, slag, burned shale, burned clay, metakaol in, pumice, diatomaCeous earth, volcanic ash, opaline shale, tuff, and burned organic materials, such as agricultural waste ash, municipal waste ash municipal solid waste ash), wastewater treatment waste ash, animal wage ash, TIOTA-1111Man-non-animal industrial waste ash, and combinations thereof Specific examples of agricultural waste ash include, for example, rice husk ash, wood (e.g., sawdust, bark, twigs, branches, other waste wood) ash, tree leave ash, corn cob ash, cane (e.g., sugar cane) ash, bagasse ash, grain (e.g., amaranth, -barley, corn flaxseed, millet, oat, quinoa, rye, wheat ete) and related by-product(s) (e.g., husks, hulls, etc) ash, orchard ash, vine trimming ash, grass (e.g., Korai, Tifton, native :shiba, etc) ash, straw ash, ground nut shell ash., legume (e.g., soybean) ash, and combinations thereof [0025] In 001i.te embodii.nenta, the cementitious component may comprise a kiln dust. One example of a kiln dust includes cement kiln dust Cement kiln dust, as that term is used herein, refers to a partially calcined kiln feed which is removed ttom the gas stream and

6

7 PCT/US2013/066771 collected, fit example, in a dust collector durinu. the manufacture of cement:
The cement kiln dust generally may exhibit cementitious properties, in that it may set and harden in the presence of water. Usually, large quantities of 'cement kiln dust. .are collected in the production cement that are commonly disposed of as waste. .Disposal of the cement kiln dust can add undesirable Costs to the .manufacture of the cement, as well as the environmental coneerns associated with its disposal. The chemical analysis of the cement kiln dust from various cement manufactures varies depending on .a number of factors, including the particular kiln teed, the efficiencies of the cement production operation, and the associated dust collection $ystems. Cement kin dust generally may comprise a variety of oxides, such as Si02, A1.203., Pe2Q,CaQ, MgO, $03, .NazO, and .K,20.
Anotherekample ofa kiln dust includes lime kiln dust. Lithe kiln dust, as that. term is used herein, refers to . a product generated in the manufacture of lime. The lime kiln dust may be collected, for 'example, by dust control systems in the calcination of limestone;
100201 in some embodiments, one or more parameters of the cementitious 1.5 component may he measured and then used in determining the reactive index. The parameters may include a number of different parameters that may be measured using .standard laboratory testing techniques for a. settable composition comprising a cementitious component and water. Additional components may also be included in the settable compositions, for example, to vary One or more properties of the treatment fluid. Parameters of the .eernentitious component, or settable composition, contained theitin., that may be measured include, for example, compressive .strength, Young's Modulus, fluid thickening time, theological values. .(e,g., volume average apparent viseOsity, plastic viscosity, yield point, etc.) and/or free water, [00271 Compressive strength is generally the capacity of a material or structure to withstand axially directed .pushing forces, The ..compressive strength of the comentitious component may be Measured. at a. specified time after the ceMentitious component has been mixed with water.and the .resultant treatment fluid is maintained under specified temperature and pressure. conditions. :For example.. compressive strength can be measured at a. time in the range of about 24 to About 48 hours after the ibid. is mixed and the fluid is maintained at a temperature. of 170 F 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 treatment .fluid samples at various points in time by crushing the.samples 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 Analyzer ("UCA''), available from Fann instrument Company, Houston, TX, CompreSS.ive strengths may be determined in accordance with API RP 10B-2.
Recoinmend0 Practice for Msting Well Cemom, First Edition, July 2005.
[00281 Young's modulus also referred to as the modulus of elasticity is a measure of the relationship of an applied: stress to the resultant strain. in general, a highly deformable (plastic) material Wi I I exhibit a lower modulus when the confined stress is increased. Thus, the Young's modulus is an elastic constant that demonstrates the ability of the *W(1 material to withstand applied loadsõ A number of different laboratory techniques may be used to measure the Young's modulus of a treatment fluid comprising a cementitious:
component after the treatment fluid has been allowed to set tbr a period of time at specified temperature and pressure conditions.
[0029] Fluid toss typically refers to loss of a. fluid such as a treatment fluid into a subterranean formation. A number of different laboratory techniques may be used to measure fluid loss of a treatment fluid to give an indication of the behavior of the treatment fluid in a well, Fluid loss may he measured using a static fluid-loss test, with either a static or stirred fluid-loSs in accordance with the atbre-mentioned API RP
Practice I 0B-2.
[0030] Thickening time typically refers to the time a fluid, such as a treatment fluid, comprising the eementitious component, remains in a fluid state capable of being pumped, A number of different laboratory techniques may be used to measure thickening time to give an indication of the aniount of time a treatment fluid will remain pumpable in a well. An example technique for determining whether a treatment fluid is in a. pumpable fluid state may use a high-temperature high-pressure eensistometer at specified pressure and temperature conditions, in accordance with the procedure for determining cement thickening times set forth in the afore-mentioned API. R.P Practice 10B-2. The thickening time may be the time for the treatment fluid to reach 70 Bearden units of consistency ("BO
and may be reported in time to reach 70 13c, [0031:1 Rheological values of a fluid may be determined to ehariicterize the fluid rheologieal behavior. Rheological values that may be determined include volume average apparent viscosity, yield point and plastic viscosity, among others: Plastic viscosity is typically a measure of the resistance of a fluid to flow, in some embodiments, the yield point may be a parameter of the Bingham plastic model, the yield point being the slope of the shear stress/shear rate line above the yield point. Yield point is typically a measure Of the point at which a material can no longer deform elastically, In some embodiment* the yield .point May be a parameter of the Bingham plastic model, the yield point being the yield stress extrapolated to a shear rate of zero. A. number of different laboratory techniques may

8 be used to measure theological values of a treatment fluid to give an indication of the behavior ofT the. treatment fluid, in a well. Rhe.ologieal Vallie; May be determined in accordance with the procedure set forth in API RP Practice 108-2.
[00321 Free water typically refers to any water in a fluid that is in excess to what is required to fully hydrate the components of the fluid. Free water can be undesired as it may physically separate from a cement composition as itsets. Freowater may also be referred to .as free fluid. A number of different laboratory techniques may be Used to Measure free water of a. treatment fluid to give an indication of the behavior of the treatment fluid in a well.
Free water may be determined in accordance with the procedure.Set forth in API.RP Practice 108,2.
[00311 As previously mentioned, the reactivity of cementitious components: may vary between different types of cementitious components or even between different sources:
for a particular type of cementitious component. For .example, the reactivity of Portland cement and another cementitious component, such .as a ponolanie material, may be different. By way of further example, the reactivity of a cementitious component may vary .between different sources .fOr the tementitious component. In SC,lthe embodiments, the.
reactive index of the cementitious component may 'vary betWeert two or more different sources by a factor .of at least about 21. For example, thereactive index of the eetnentitions component between different sources may vary . by an amount between any of and/or includiegarty of about 2 about 10:1, about 50:1, about 100A, about 250:4about 500:1, or about 1000:1. Because the reactivity varies between different cementitious components:. and even between different sources for a vernentitiOtis component, the performance of different cementitious components may be unpredictable and may also lead to a lack of consistency for the cementitious components. when used in treatment fluids such as.
settah.le 'compositions. some. instances, the performance of a particular cementitious. component may have undesirable properties, which may make it unsuitable for use, for example, a cementitious component from a particular source may have properties making it undesirable for use.
[0034] in some embodiments, a blend of two or more different cementitious .30 components may he used to provide, a blended cementitious component that may have properties = suitable fir use in a particular application. This may' be particularly useful, for .example, where one of the c'ementitious components in the blend may have properties making it unsuitable for particular applications. For example, a cementitious.
component such as cement kiln dust from a first source may be blended with a cementitious component such as cement kiln dust from a .second sourcc, in some embodiments, one or both of the

9 .cementitious components may have. reactivities that are unsuitable for a.
particular application. For example, the reaclivitieS: of. each cementitious component may be individually too.slow.or too fast for a. particular application. The blends:
of the cementitious component .from the two .different: sources may form a blended cementitious component having. compressive strength properties that are suitable for the application.
In some embodiments, the relative proportions. (e.g,õ weight fractions) of each cementitious component in the blended. cem.entitious component may then be adjusted to adjust the compressive strength properties of the blended cementitious component.
100351 The two or more cementitious components in the blended cementitiotis component may include,. fc-a- example, two or more: different types of cementitious components, such .as Portland cement and cement kiln dusty Alternatively, the two or more cementitious components in the blended cementitious component may include, .for example, a :cementitious .component from two. or more different sources. For example,.
A. first cementitious component may comprise cement kiln dust from a first source, and the second cementitious component may comprise cement kiln dust from a second source. It Should be understood that embodiments are not limited to only two different sources, but may include a cernentitious component, such as cement kiln dust, .from . three,. thur, five, or even more different sources. The two or .more different sources for the. cementitious .component may include different manufactures, different cement manufacturing plants, .and the like. A
cementitious component:, such as cethent kiln dust which is al byproduct from the cement :manufacturing plant, may have a number Of different sources available throughout the world.
For example, different sources for cement kiln dust may include different manufacturing plants throughout The world at which cement kiln dust can. be generated.
[00361 The two .or more cementitious components may be blended to: form the 2.5 blended cementitious component, thtexampie, prior to combination with water and/or other components of the treatment fluid. In particular embodiments, the two or more cementitious components may be dry blended to form a dry blend comprising the two or more cementitious components. The dry blend may then be combined with water and/or other components, in any order, to firm the treatment fluid. floWever, the use of the term "blend"
is not intended to imply that the two or tn.Cire cementitious components have been dry blended prior to .combination with water. For example, .the blend of two or more cementitious components may not be combined until after one, or even both, of the cementitious Components has already been blended with water.
[0037.] In some embodimeM, the reactive index may be used to optimize the blended cementitious component, wherein the blended cementitious component comprises MO or more cementitious components. For example, the reactive index may be Used to optimize one. or more paramcWr$! Of the blended cementitious component, including compressive strength, Young's Modulus, fluid loss, and/or thickening time.
Optimizing the blended cementitious component may include determining the reactive index for each of the cementitious components in the blended cementitious component. The reactive indexes tbr the cementitious components may then be used to predict the performance of the blended cementitious component. The ratio a each cementitious component may be adjusted to optimize the performance, of the blended cementitious component. 71'he performance of the blended cementitious component May be optimized with the performance of the blended cementitious componentesti mated using the following equation:
ENwnd Evaix.s&itx fir Wherein BP. .k the estimated parameter for the blended. cementitious 'component, i is.the individual cementitious component from the set of cementitious components I to n, n is an integer, RI i is the reactive index for cementitious CoMponent i, SSA i is the specific surface area for cementitious component I, is the Mass fit:client of the cementitious component and m is ..a number from 1 to .10. The set of cementitious components may :include lor more diMrent.cernentitious components. The two or' more different cementitious.
component may be different types of cementitious components, such as Portland cement and slag, or May be from diffc.tent sources, such as cement kiln dust from a. first ..source..and cement kiln dust from a second source. In some embodimentsõm may be. 1.. In alternative embodiments, tri may be [00381 In some embodiments, the mean padicle size of the cementitious component may be altered from its original particle- size. The reactive index may then be measured for the altered cementitious component. The altered cementitious component may be included in a blended cementitious Component. In accordance .with present embodiments, the mean particle .size of the cementitious 'Component can be altered using any Suitable technique, including, without limitation, grinding or separating. to provide a material having an altered particle size.. Separating the .cementitious component may include sieving or any other suitable technique for separating the cementitious component to provide a.
mean particle size that. has been altered from its original size. For 'example, sieving may be used to produce cementitious component having an increased or reduced mean particle size as desired for .a particular application. By way Of further example, grinding may be used to decrease the mean particle size of the cemeniitious...component. Combinations of grinding and separating may be used in some embodiments. The term "'ground" or "grinding" as used herein means using a. grinder (e,g., ball mill, rod mill, etc.) to. tultice the particle size of the Speci tied component(s). An.exampk ofa Suitable -grinder is.an 8000 N4ixet1MiIf ball mill, available from SPEX. Sample Prep. In some, embodimcnts, .the cementhiou.s component may be ground for a time period in a range of from about .30 'minutes to about 1 hour.
[0039] The mean particle. Size of the eementitious component can be altered to any 'size suitable for use in cementing operations. In SOMt embodiments, the mean particle size of the eementitiouscomponent may be altered frOnl. it original particle size to. have a mean particle size in a range of about 1 micron to about 350 microns. The mean particle size corresponds to d50 values as measured by partiele.sizoanalyzers such as those manufactured by Malvern Instruments, Worcestershire, United Kingdom.
[0040] in. some embodiments, the mean particle size of the eetnentitious component may be increased from its .original Size. For example, the mean particle Size of the CeMentitious component may be at lea*: 5% greater than its Original sizeõ in some embodiments, at :IOW a portion of the cementitious component may be increased to a size that is in a range of from about. 5% to about 500% greater than its originaLsize. In some.
embodiments, the mean particle size may be increased to size. ranging between any of and/or including any of about 5%, about 10%, about .20%, about 30%, about 40%, about 50%,. about 60%,about 70%õ about $0%,..abotit 90%, about 100%,..abont 200%, about about 400%, or about 500% Mater than itS Original size, [0041] In some'embodiments, the mean .particle size of the cementitiou's component may be reduced from its original :size. For example, the mean particle size may be reduced in an amount sufficient to increase. the compressive strength of the eementitions component.
In some embodiments, the-emend-nous component .may have a mean particle siZelhat is at least .5%. less than its original size,. In some :embodiments,. 41 iCast a portion of the cementitious component may be reduced to have a mean particle .size in a range of from .about 5% to about 95%. of its original. size. For example, the mean particle size may be reduced to a size ranging between arrs,,,, of .atidtor including any of about 5%, about 1:0%, about 15%, about 20%, about i.25%, about 30%, about 3.5%, about 40%, about 45.%, about 50%, about 55%, about 60%, about 6%, about 70%, about 75%, about 80%, .about 90%, or .30 about.
95%: of its original .size. =Byway of example, :the reduced particle .size cementitious component may have .a mean particle size .or less than about 15 microns. In ..some embodiments, the reduced particle size cementitioas component may have a mean particle size ofless. than about 10 .micronS, less than about 5 microns, lea's than about 4 microns, less than about 3 'microns, less than about .2 microns ,.or less than about .1 micron, In specific embodiments, the reduced particle size: cementitious component may have a mean particle size in a range of from about 0.1 microns to about 15 microns, from about 0.1 microns to about 10 microns, or from about 1 trilettn to about 10 microns. One of ordinary skill in the art, with the benefit of this .4isclosure, should be able to select a particle Size for the cementthous component suitable for a particular application.
[0042] in some embodiments, the mean particle size of the cement kiln dust may be reduced in An amount sufficient to provide an increase in compressive:
strength thr the .settable composition: For example, the mean particle size may be reduced .to provide an increase in compressive strength of at least about 5%, about 25%, about 50%, about 75%õ or about 100%, [0043] In accordance with present embodiments, the cemeinitious components may be included in treatment fluids that Can be .uSed in a variety of operations that may be performed in: Subterranean formations: The cernentitious component may have reactive index calculated aecOrding to disclosed embodiments. In some embodiments, a blended cementitious component may be used. In some embodiments, the reactive index may be used in determining the eementitious components in a particular blended .cementitious component. As referred to herein, the term -treatment fluid" will be understood to mean any fluid that may be used in a subterranean application in conjunction with .a desired function and/or for a desired purpose. The term "treatment fluid" .is not intended to imply any particular action by the fluid. Treatment fluids Wien are used in, el.., well drilling, 'd ompietion, and stimulation operations, Examples Of such treatment fluids include drilling fluids, well cleanup fluids, workover fluids, conformance fluids, gravel pack.
fluids, acidizing fluids, fracturing fluids, cement compositions, spacer fluids,: and the like.
[0044] While embodiments of the compositions and methods may be used in a variety of applications, they may be particularly useful for subterranean well completion and.
remedial operations,. such as primary cementing of casings and liners in well bores. They also may be useful for surface cementing operations, including construction cementing, Operations, Accordingly, embodiments of the present invention disclose sellable compositions.co.mpri.sing.a.cementitious component and water.
[00451 The cenlentitiQUS component may be included in embodiments of the settable compositions in an amount suitable for .a particular application. In some embodimentsõ:the cementitious component may eomprise, cement kiln dust. The cement kiln dust may be present in an amount in a range of from about 0.01% to 100% by Weight of the cementitious component: ("bwoc"). For example, the. cement kiln dust May be present in an amount ranging between any of and/Or including. any Of about 0.01%, about 5%, about.
:10%, About 35. 20%, about. 30%, 40%, about 50%, about 60%, about 70%, about 80%, about 90%, or about 100%. The eeinentitious component may be free or essentially .frm (for example, no more than 1%. by weight of the Cementitious component) of any additional eementitiong components other than the cementitious component. In some embodiments, the cementitious component may be essentially free of Portland cement. One of ordinary in the art with the benefit of this disclosure should be able to determine An appropriate amount of the cementitious.eomponent to include for a particular application., [0046] The water Used in embodiments of the settable compositions of the present invention may include, or example, freshwater,. saltwater (e.g., water containing one or more salts dissolved therein), brine (e.g.., saturated saltwater produced from subterranean formationS), seawater, or any combination thereof. Generally, the water may be from any source, provided, for example, that it does nOt contain an excess of compounds that may undesirably .affect other components in the settable, coMposition, in some embodiments, the water may be. included in an amount sufficient to form a pumpable slurry. in some embodiments, the water may be 'included in the settable Compositions of the present invention in an amount in a range Of from about 40%-to about 200% .bwoc: For example, the water may be present in an amount ranging, between any of and/or including any of about 50%, about. 75%, about 100%, about .125%, about 150%, or about 175"4 by .weight of the cement. In specific embodiments, the water may be included in an amount in the range of from about 40% to about 150% bWoc. One of ordinary skill in the art, with the benetit.of this dis=closiire, recognize the appropriate amount of water .to include for a chosen application.
[0047] Other additiveS .suitable for Use in subterranean cementing operations may also be added to Ombodiments.of the.isettable compositions, in accordance with embodiments of the present invention. .Examples: of such additives .include, but are not limited to, fluid-loss-control additive, set retarder, strength-retrogression additives; set accelerators, weighting agents, tiahtweight additives, gas-generating additives., mechanical-property-enhancing: additives, lost,c=irc u ati on materials, filtration-control addi dye's, %tuning additives, thixotropic additives, and any combination thereoff. Specific examples of these, and other, additives include crystalline. Oita, amorphous = silica, finned silica, salts, fibers, hydratable clays, calcined shale, vitrified shale, microspheres, hollow- glass spheres, fly ash, diatomaceous earth, metakaolin, ground perliteõ rice, husk ash, natural pozzolanõ
cement kiln dust, resins, any combination thereof, and the like. A person having ordinary Skill in the art, with .the benefit of this disclosure, will readily be able to determine the type and. amount of additive: useful for a particular application and desired result [00481 Those of ordinary skill in the art will appreciate that embodiments of the settabie compositions generally should have a density suitable for a particular application.
By way of example, embodiments of the settable compositions may have a density of about 4 pounds per gallon (lb/gal") to about 20 ltVgal. in certain embodiments, the settable Compositions may have a density of about 8 to about 17 lb/gal. Embodiments of the settable compositions may be foamed or untbamed or may comprise other means to reduce their densities, such as hollow micrcispheres, low-density elastic beads, or other density-reducing additives known in the art. hi addition, the settable composition may comprise weighting agents or other means to increase their densities. Those of ordinary skill in the art, with the benefit of this disclosure, will recognize the appropriate density for a particular application.
[0049] in some embodiments, the settable compositions may have a thickening time of greater than about I hour, alternatively, greater than about 2 hours, alternatively greater than about 5 hours at 3,000 psi and temperatures in a range of from about 50 F
to about 400 F, :alternatively, in a range of from about 80 F to about 250*1, and alternatively at a temperature of about 140 F. in soffic embodiments; the settable composition may have a 24-hour compressive strength in a range of from about WO psi to about .10,000 psi and, alternatively, from about 350 psi about 3,000 psi at atmospheric pressure and temperatures in a range of from about 50 F to about 400 F, alternatively, in a range of from about 80 F to about 250 F, and. alternatively at a temperature of about 180 F.
[0050-1 The components of the settable composition may be combined in any order desired to form a settable composition that can be placed into p subterranean formation. In addition., the components of the gettable compositions may be combined using any mixing device compatible with the composition, including a bulk mixer,. for example.
In some embodiments, a dry blend may first be formed by the cementitious component or mixture of =cementitious components. The dry blend may then be combined with water to form the settable composition. Other Suitable techniques May be used for preparation of the gettable compositions as will be appreciated by those of ordinary skill in the art in accordance with embodiments of the present invention.
100511 As will 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 cementing operations, including surface and subterranean operations, Such as primary and remedial cementing In. some embodiments, a cement composition may be provided that comprises a cememitious component and water., and allowed set. in certain embodiments, the cement composition may be introduced into a subterranean formation and allowed to set therein. As used herein, introducing the cement composition i.nto a subterranean lbrmation includes introductiOn into any portion of the subterranean II-Irina-tit* 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, [0052] in primary-cementing. embodiments, .for example, embodiments may comprise providing a cement composition, introducing the cement composition into a well-bore annulus; and allowing the cement composition to set in the annulus to tbrm a hardened mass. The well-bore annulus may include, for example, an annular space between a conduit (e,g.õ pipe. string, liner, etc;) and a wall of a well bore or between the conduit and a larger .10 conduit in the well bore. Generally, in most instances, the hardened mass...should fix,. the conduit in the well bOrcõ
(0053 ln reinedial-cementing embodiments,a cement composition may be used, for example, in squeeze-cementing operations or in the placement ofeement 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, andlora microannulus between the cement sheath and the conduit or .formation. An example of such a method may comprise .placing the cement composition into the void, and allowing the content composition to set in the void.
1.0054] While the preceding description is directed to the use of the cementitious component in Cementing method* it should be understood that embodiments of the present technique also encompasses the use of the cementitious component. in any of a variety of different subterranean treatments. The cementitious component may have a reactive index determined according to disclOsed embodiments. in some embodiments, a blended cementitious component may be used.. In some embodiments, the reactive index.
may be used in determining the amount of' cementitious components that are in a particular blended tementitious component. An example method may include a subterranean treatment method that comprises providing a treatment fluid comprising the cementitious component and introducing the treatment fluid into a subterranean formation, ror example, a.
drilling. fluid may comprise the cementitious component, wherein .the drilling fluid may be circulated .30 downwardly through a drill pipe and drill bit and then upwardly through the well bore to the surface. The drilling. fluid .used may be any number of fluids (gaseous or liquid) and mixtures of fluids and solids (such as solid suspensions, mixtures, and emulsions).
1.0055] In some embodiments, a spacer fluid may comprise the cementitious component, which may have a determined reactive index according to disclosed 35.
embodiments. Spacer :fluids may be used, far exam*, in the displacement of fluids from.

well bore, In an embodiment, the fluid displaced by the spacer fluid.
comprises a drilling fluid, By way of example, the spacer fluid may be used to displace the drilling fluid from the well bore. The drilling fluid may include, for example, any number of fluids., such as solid suspensions, mixtures, and emulsions. Additional steps in embodiments of the method may comprise introducina a pipe string into the well bOre, introducing a ecinent compOsition into the well bore with the spacer fluid separating the cement composition and the first fluid.
in an embodiment, the cement composition may be allowed to set in the well bore. The Cement composition may include, for example, cement and water. In some embodiments, at least a portion of the spacer fluid may be left in the well bore, the spacer fluid in the well bore setting to -fbrm a hardened mass, EXAMPLES
[00561 To facilitate a better understanding of the present invention, the following eXaMples of Certain aspeet$ or some embodiments are given. In no Way should the following examples be read to limit. or define, the entire scope of the invention.
Example I
[0057] The reaetiµv indexes for compressive strength for thirty-three different samples of cement kiln dust, designated Samples A through 00, were determined and are provided in FIG. 1. The CK.D samples are each from a different supply source.
The reactive indexes =fbr thirty-three CKD samples were determined by dividing the determined 24-hour .compressive strength for a 8ettable composition by the specific surface area of the CKD
sample. The specific surface area for each CKD sample was determined by dividing the total surface area of the particular CKD sample by the sample. mass. The surface area Was determined using a Malvern particle size analyzer. The 24-hour compressive strength for each CKD sample was determined by first preparing a senable composition that comprised the CKD sample in an amount of 100% bwoc and water in an amount sufficient to provide a density Of about 13 Ihigal. After preparation, the settable composition was allowed to cure fir 24 hours in a 2" x 4" metal cylinder that was placed in a water bath at 170W to %rm. set cement cylinders. Immediately after removal from the water bath, destructive compressive strengths were determined using a mechanical press in accordance With API RP
1013-2, Example 2 100581 Blended cementitioua components were prepared that comprised mixtures of the CKD samples from Example 1. as indicated in the table below. The determined reactive indexc.s for the MD sample$, Were then used in the following equation to predict the performance or each blended cententitious component.

CSwend UtiASSAAfzr (RIASSAFOr atiO(SSAE)(fan Wherein CSwend is the estimated compressive strength for the blended cememitious component. RI z is the reactive index for compressive strength for CKD Sample Z and was m is I, SSAz is the specific surface area for CKD Sample Z and was 2,32, fz, is the mass fraction of CKD Sample Z, RIF is the reactive index for compressive strength for CKD
Sample F and was 105, SSAF is the specific surface area for CKD Sample F and was 2.33, fy is the mass fraction of CKD Sample F. RIE is the reactive index for compressive strength for CKD Sample E. and was 107, SSAE is the specific surface area for CKD Sample E
and was 3.6, and f, is the mass fraction of CKD Sample Li.
[00591 The estimated compressive strength valuesl for the blended cementitious components were then compared with the actual 24-hour compressive strength values for the blended cementitious components. The 24-hour compressive strength for each blended cemeatitious component was determined by first preparing a settable composition that comprised the blended cementitious component in an amount of 100% bwoc.: and water in an amount sufficient to provide a density of 13 lb/gal. A cement dispersant (1C-F11.-3"4 cement fron reducer, from Hall iburton Energy Services, Inc.) in an amount of from 0.5% bwoc to 1.0% bwoc was added to some of the samples and should not impact determined compressive strength values. Atter preparation, the settable composition was allowed to cure for 24 hours in a 2" x 4" metal cylinder that was placed in a water bath at I40"F to form set cement cylinders. Immediately after removal from the water bath, destructive compressive strengths were determined using a mechanical press in accordance with API RP
1013-2.
10060] A chart of the actual compressive strength values versus the estimated compressive strength values is provided on FIG. 2, As shown on FIG. 2, the charted values have an.R value of 0,952 and a slope of 0,9253. The estimated and actual compressive strength values for the blended cementitious components are also provided in Table I below, Table I
CKID Sample CKD Sample CKD Sample Estimated Actual F Compressive Compressive (44 bwoe) bwoe) bwoe) Strength Strength ist) 100 0 0 .16 16 0 .100 0 :244 244 292. 216 Example 3 [0061] The reactive indexes for volume Average apparent Viscosity at 511 Seel and 51 see were determined for CKD Sa.mples Z, F, and E from Example 1 and are provided in 5 Table 2 below. The reactive indexes for these samples were determined by dividing the determined volume average apparent viscosity for a .Settable composition by the specific surface area of the CK.0 sample. The specific surface area for each CKD sample was determined hy dividing the total surface area of the particular CKD sample by the sample mass. The surface area was determined using a Malvern particle size analyzer.
The 24-hour volume average apparent viscosity ("VAV") for each CKD sample was determined by tint preparing a settable composition that comprised the CKD sample in an amount of 100%
bwoc and water in an amount sufficient to provide a density of about 12 lb/gal. The volume average apparent viscosities were measured at 511 !see and 51 see in accordance with Table 2 CM) Sample Z CM) Sample F CKD Sample E
SSA 2.31 2.33 3.6 VAV at 511 Seel (cp) 11 62 123 RI at 511 See 5 27 32 VAV at 51 sec- (9?) 40 410 860 RI at St see-1 17 176 239 00621 Next, blended ccmentitiouS components were prepared that comprised mixtures of OM .samples Z, F, E. as indicated in the table below. The determined reactive indexes At 511 see and 51 stel far the (11(1) samples were then used in the following equation to predict the :performance of each blended cementitious component.
(Riz)(SSAz)(V,(RI)(SSAAtir + (RIASSAO(V

Wherein VAVt,i,õd is the estimated volume average apparent viscosity for the blended cementitious component. Rlz is the reactive index for volume -average apparent viscosity for CKD Sample Z, SSA z is the specific surface area for MD Sample Z, fz is the mass fraction of CKD Sample Z, m is 7/3, RIF is the reactive index for volume average apparent viscosity fbr CKD Sample F, SSAF is the specific surfiice area for CKD Sample F, ff is the mass fraction of CKD Sample F, Ri is the reactive index for volume average apparent viscosity for CKD Sample E, SSA E is the specific surface area for CK.D Sample E, and f is the mass fraction of CKD Sample E.
[0063] The estimated volume average apparent viscosities at 511 see and 5.1 sec' for the blended cementitious components were then compared with the actual volume average apparent viscosities at 511 see and 51 see for the blended cementitious components. The volume average apparent viscosities for each blended cementitious component was determined by first preparing a settable composition that comprised the blended cementitious component in an amount of 100% bwoc and water in an amount sufficient to provide a density of 12 lb/gal. After preparation, the volume average apparent viscosities at 511 see and 51 see were determined in accordance with API RP
10B-2.
[0064] Charts of the actual volume average viscosity values versus the estimated volume average viscosity values are provided on FIGS. 3 and 4. As shown on FIG. 3, the charted values at 51.1 see have an R2 value of 0.9894 and. a slope of 0.9975.
As shown on FIG. 4, the dialled values at 51 see have an R2 value of 0.9931 and a slope of 0,9814. The estimated and actual volume average viscosity values for the blended cementitious components are also provided in Table 2 below.
Table 3 CKD CKD CKD Actual Est. Actual Est.
Sample Z Sample F Sample E VAN/ VAV VAN' VAN' bwoc) (% bwoc) bwuc) kE0 511 sec 4 511 see -I 51 sec -1 @
51 see (SP) (cli) (c.P) ..
100 0 0 11.0 11.0 40.0 40.0 75 25 0 I 1.0 8.1 40.0 36.7 75 0 24.0 1 32.2 190.0 211.3 , 0 100 0 62.0 ; 62.0 410.1 410.0 0 0 100 123.0 1 123.0 860.2 860.0 66.0 63.4 500.1 441.5 50 0 50 .25.0 1 26.7 160.0 179.0 75 0 25 16.0 10.5 60.0 54.5 [0065] It should be understood that the compositions and methods are described in 25 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. Moreover, the indefinite articles "tr or '.=.atiõ." As used in the claims, are defined herein to rneati One Or more than one of the element that it introduces.
[0066j For the sake of brevity, only certain ranges are explicitly disclosed herein.
However, ranges from any lower limit may be combined with any upper limit to recite a range not explicitly recited, as well as, raneeS 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 ranee not explicitly recited. Additionally, whenever a numerical range with a lower limit and an upper limit is disclOsed, any number and any included range falling Within the range are specifically diselosed. In particular, every range of values (of the form, from about a to about 11," or, equiValentlY, from approximately a to 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 even if not explicitly recited. Thus, every point or individual value may serve as its own lower or upper limit combined with any other point or individual value or any other lower or upper Iimit to recite a range nOt explicitly recited, [00671 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 diseWetl 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. Although individual embodiments are discussed, the invention covers all combinations of all those embodiments. Furthermore, no limitations are intended to the details Of COnstruetiort or design herein shown, other than as described in the claims below, Also, :the terms in the claims have their plain, ordinaly meaning unless otherwise explicitly and *att.,' defined by the patentee. It is therefore evident that the particular illustrative embodiments disclosed above may be altered or modified and all such variations are considered within the: scope and spirit of the present invention. if there is any conflict in the mites of a word or term in this specification and one or more patent(s): or other documents that may be incorporated herein by reference, the definitions that are consistent with this specification should be adopted

Claims

What is claimed is:

1. A method of treating a well comprising:
providing a treatment fluid comprising a base fluid and a blended cementitious component, wherein the blended cementitious component comprises kiln dust from two or more different sources; and introducing the treatment fluid into a well bore.

2. The method of claim 1 wherein the base fluid comprises water selected from the group consisting of freshwater, saltwater, brine, and any combination thereof.

3. The method of claim 1 wherein the kiln dust is selected from the group consisting of lime kiln dust, cement kiln dust, and a combination thereof.

4. The method of claim 1 wherein the kiln dust comprises cement kiln dust, the cement kiln dust being present in the treatment fluid in an amount in a range of from about 0.01% to 100% by weight of by weight of the blended cementitious component.

5. The method of claim 1 wherein the treatment fluid is essentially free of any additional cementitious components other than the blended cementitious component.

6. The method of claim 1 wherein the treatment fluid is used in the well bore in well drilling.

7. The method of claim wherein the treatment fluid is used in the well bore in well completion.

8. The method of claim 1 wherein the treatment fluid is used in the well bore in well stimulation.

9. The method of claim I wherein the amount of kiln dust .from each of the two sources in the blended cementitious component is adjusted based on a parameter selected from the group consisting of compressive strength, Young's modulus, fluid loss, thickening time, a rheological value, free water, and any combination thereof.

10. The method of claim 1 wherein the kiln dust comprises a first kiln dust from a first source and a second kiln dust from a second source, and wherein the method further comprises further comprises determining a reactive index for the first kiln dust and determining a reactive index for the second kiln dust.

11. The method of claim 10:
wherein the step of determining the reactive index for the first kiln dust uses the following equation:
RI1 = MP1 / SSA1 wherein R1 is the reactive index for the first kiln dust, MP1 is a measured parameter of the first kiln dust, and SSA1 is the specific surface area of the first kiln dust;
and wherein the step of determining the reactive index for the second kiln dust uses the following equation;
RI2 = MP2 / SSA2 wherein RI2 is the reactive index for the second kiln dust, MP2 is a measured parameter of the second kiln dust, and SSA2 is the specific surface area of the second kiln dust

12. The method of claim 11 wherein the measured parameter is compressive strength, Young's modulus, fluid loss, thickening time, a rheological value, free water, or any combination thereof.

13. The method of claim 12 wherein performance of the blended cementitious component is optimized using the following equation:
EP blend (RI1)(SSA1)(f1)m + (RI2)(SSA2)(f2)m wherein EP is an estimated parameter for the blended cementitious component, f1 is mass fraction of first kiln dust, f2 is mass fraction of the second kiln dust, and m is a number from 1 to 10, and wherein the optimizing comprises adjusting f1 and/or f2.

14. A method of cementing comprising:
providing a settable composition comprising water and a blended cementitious component, wherein the blended cementitious component comprises kiln dust from two or more different sources; and allowing the settable composition to set to form a hardened mass.

15. The method of claim 14 wherein the kiln dust is selected from the group consisting of lime kiln dust, cement kiln dust, and a combination thereof.

16. The method of claim 14 wherein the kiln dust comprises cement kiln dust, the cement kiln dust being present in the settable composition in an amount in a range of from about 0.01% to 100% by weight of by weight of the blended cementitious component.

17. The method of claim 14 wherein the settable composition is essentially free of any additional cementitious components other than the blended cementitious component.

18. The method of claim 14 wherein the amount of kiln dust from each of the two sources in the blended cementitious component is adjusted based on a parameter selected from the group consisting of compressive strength, Young's modulus, fluid loss, thickening time, a theological value, free water, and any combination thereof.

19. The method of claim 14 wherein the amount of kiln dust from each of the two sources in the blended cementitious component is adjusted to adjust compressive strength of the settable composition.

20. The method of claim 14 wherein the kiln dust comprises a first kiln dust from a first source and a second kiln dust from a second source.

21. The method of claim 20 further comprising adjusting particle size of the first kiln dust and/or the second kiln dust to adjust compressive strength of the settable composition.

22. The method of claim 20 wherein particle size of the first kiln dust and/or the second kiln dust has been reduced by way of grinding to adjust compressive strength of the settable composition.

23. The method of claim 20 wherein a reactive index for the first kiln dust and a reactive index for the second kiln dust vary by a factor of a least about 2:1.

24. The method of claim 20 wherein a reactive index for the first kiln dust and a reactive index for the second kiln dust vary by a factor of at least about 100:1.

25. The method of Claim 20 wherein the first kiln dust and the second kiln dust have different reactive indexes.

26. The method of claim 20 further comprising determining a reactive index for the first kiln dust and determining a reactive index for the second kiln dust.

27. The method of claim 26 wherein the step of determining the reactive index for the first kiln dust uses the following equation:
RI1= MP1 / SSA1 wherein RI1 is the reactive index for the first kiln dust, MP1 is a measured parameter of the first kiln dust, and SSA1 is the specific surface area of the first kiln dust, and wherein the step of determining the reactive index for the second kiln dust uses the following equation;
RI2 = MP2 / SSA2 wherein RI2 is the reactive index for the second kiln dust, MP2 is a measured parameter of the second kiln dust, and SSA2 is the specific surface area of the second kiln dust.

28. The method of claim 27, wherein the measured parameter is compressive strength, Young's modulus, fluid loss, thickening time, a rheological value, free water, or any combination thereof.

29. The method of claim 27 wherein performance of the blended cementitious component is optimized using the following equation:
EP blend = (RI1)(SSA1)(f1)m + (RI2)(SSA2)(f2)m wherein EP is an estimated parameter for the blended cementitious component, f1 is mass fraction of first kiln dust, f2 is mass fraction of the second kiln dust, and m is a value from 1 to 10, and wherein the optimizing comprises adjusting f1 and/or f2.

30. The method, of claim 14 further comprising placing the settable composition.
into a subterranean formation penetrated by a well bore.

31. The method of claim 30 wherein settable composition is used in primary cementing in the well bore.

32. The method of claim 30 wherein the settable composition is used remedial cementing in the well bore.

33. A method. of cementing comprising;
providing a settable composition comprising water and a blended cementitious component, wherein the blended cementitious component comprises kiln dust and an additional cementitious component, the kiln dust and the. additional cementitious component each have a determined reactive index, and allowing the settable composition to set to form a hardened mass.

34. The method of claim 33, wherein the settable composition comprises one or more of the features defined in claim 15 or claim 16,

35. A method of preparing a blended cementitious component. comprising:
providing a. first kiln dust, the first kiln dust being from a first source;
providing a second kiln dust, the second kiln dust being from a second source; and blending at least the first kiln dust and the second kiln dust to form the blended cement it long component.

36. A method of measuring reactivity of a kiln dust compris measuring a parameter of the kiln dust, the kiln dust having a specific surface area; and dividing the measured parameter by the specific surface area of the kiln dust to obtain a reactive index for the kiln dust,

37. A well treatment fluid comprising:
a base fluid; and a blended cementitious component comprising kiln dust from two or more different sources.

38. The well treatment fluid of claim 37 comprising one or more features defined in any one of claims 1 to 5.