METHODS FOR DETERMINING REACTI VE INDEX FOR CEMENT KILN
DUST, ASSOCIATED COMPOSITIONS, AND METHODS OF USE
BACKGROUND
[0001] The present invention relates to cementitious components and, more
particularly, in certain embodiments, to methods of determining a reactive index for
cementitious components.
[0002] In general, we l treatments include a wide variety of methods that may be
performed n oil. gas, geoihermal and/or water -wells, such as drilling, completion and
workover methods. The dri ing completion and workover methods may include, but are not
limited to, drilling, fracturing, -acidizing, logging, cementing, grave! packing, perforating a d
conformance methods. Many of these well treatments are designed to enhance and/or
facilitate the recovery of desirable fluids from a subterranean well. These fluids may include
hydrocarbons such as oil and/or gas.
[0003] cementing methods, such as well construction and remedial cementing,
settable compositions are commonly utilized. As used herein, the term "settable
composition" refers to a coraposition{s) that hydraulieally sets or otherwise develops
compressive strength. Settable compositions may be used I primary cementing operations
whereby p pe strings*, such as casing and liners, are cemented in well bores. In performing
primary cementing, a settable composition may be pumped into an ann us between a
subterranean formation and the pipe string disposed in the subterranean formation or
between the pip string and a larger conduit disposed in the subterranean formation. The
settable composition should set in the anmsSus, thereby forming an annular sheath of
hardened cement (e.g., a cement sheath) that should support and position the pipe string in
the welt bore and bond the exterior surface of the p pe string to the walls of the we l bore or
to the larger conduit. Settable compositions also ma he 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 suriace applications, for example, construction cementing.
[0004] Settable compositions tbr use in subterranean formations may typically
include a cementitious component which hydraulieally sets, or otherwise hardens, to develop
compressive strength. Examples of cementitious components that can he included in settable
compositions include Portland cement, calcium alummate cement, cement kiln dust, lime
kiln dust, fly ash, slag, pumice, and rice-hull ash, among others. The performance of these
different cementitious components in settable compositions may vary and can even vary tor
a particular cementitious component depending, for example, on the particular type or source
of the component For example, certain of these cementitious components may have
undesirable properties that a : make them unsuitable for use in well treatments. .In addition,
variation of the performance for the cementitious components can lead to lack of
predictability and consistency for the cementitious components when used in treatment
fluids. This Sack of predictability consistency ay even be apparent for the sa e
cementitious component, for example, if sourced from different locations,
SUMMARY
[0005] The present invention relates to cernentitious components and, more
particularly, i certain embodiments, to methods of determining reactive index or
cementitious components
[0006] An embodiment discloses 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 ki n dust from two or more different sources;
and introducing the treatment fluid i to well bore.
[0007] Another embodiment discloses a method of cementing comprising; providing
a setta e composition conrprising water and a blended cementitious component, wherein the
blended cementitious component comprises kiln dust from two or more different sources;
and allowing the sellable composition to set to form a hardened mass.
[0008] Another embodiment discloses method of cementing comprising: providing
a sellable 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
react e index; and allowing the sellable composition to set to form a hardened mass.
[0009 Another embodiment discloses a method of preparing 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 inde for the kiln dust.
[001.1] 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.
[00 ] The features and advantages of the present invention will be readi ly apparent
to those skilled in the art. While numerous changes ma be made by those skilled in the art,
such changes ar within the spirit of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0 3] These drawings iliustrate certain aspects of some of the embodiments of the
present invention, and should not be used to limit or define the invention.
[0014] F G. 1 is a chart showing measured reactive indexes for various supply
sources of cement kiln dust.
[0015] F G. 2 is a chart comparing actual versus predicted compressive strength for
dry blends of cement kiln dust.
[0016] F G. 3 is a chart comparing actual versus predicted volume average apparent
viscosity at 5 ! for dry blends of cement kil dust
[00 ] F G. 4 is a chart comparing actual versus predicted volume average apparent
viscosity at 5 1 see 1 for dry blends of cement kiln dust.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0 ] The present invention relates to e ent ous components and, more
particularly, in certain embodiments, to methods of determining a reactive index for
eementitious components. By determining the reactive index or cementitipus components,
blends of eementitious components may be used in well treatments, according to particular
embodiments, that can provide ore predictable and consistent performance- in addition,
additions! embodiments may include using the determined reactive index to provide blends
of eementitious components in which on or more parameters have been optimized,
including compressive strength. Young's Modulus, fluid loss, and/or thickening time, for
example.
[0 9] Without being limited b theory, the reactive index of a eementitious
component may be referred to as a measure of the cement itious component's reactivity as
adjusted for differences in surface area. Example techniques for determining the reactive
index may comprise measuring a parameter of the eementitious component, and then
dividing the measured parameter by the specific surface area of the eementitious component.
In some embodiments, the reactive index for a eementitious component may be calculated in
accordance with the following equation:
R MP / SSA
wherein R is the reactive index, MP is the measured parameter of the eementitious
component, and SSA is the specific surface area of the eementUious component, h general,
specific surface area is a property of a particulate soli and, as used herein, is defined as the
total surface area of the eementitious component divided by the mass of the eementitious
component or the total surface area divided by the bulk volume o the eementitious
component,
[0020] n general, ee e ious components are particulate solids that hydrau!ically
set, or otherwise harden, to develop compressive strength in the presence of water, Nonlimiting
examples of eementitious components that may be suitable for use in embodiments
of the present invention include Portland cements, calcium a!unrinate, gypsum, po zo ani
materials, and ki ln dust. Mixtures of one or more different eementitious components may
also be used some embodiments, the eementitious component may be combined with
lime.
[0021 ] n some embodiments, the eementitious component may comprise Portland
cement. Portland cement is a commonly used eementitious component tha hydrauHcally
reacts with water to develop compressive strength. Examples of suitable Portland cements
ay include those classified as Classes A, C> and cements according to American
Petroleum institute, API: Specification for Materials and Testing for Weil Cements, AP
Specification 10, Fi th Edition, Ju y 1, 1990. n addition, Portland cements suitable fo use
embodiments of the present invention .may also include those classified as ASTM Type 1,
1/1 , I, 0 , V, or V, s me embodiments, blends of cementitious components containing
Portland cement may be used.
[0022 n some embodiments, the cementitious component may comprise a calcium
alummate. Calcium aluminate may hydrauticai!y react with water t develop compressive
strength. Calcium alummate may be included in cements commonly referred to as calcium
aluminate cements or high alumina content cements. Calcium aluminate cements may be
prepared in a manufacturing process that includes mixing a calcium bearing material (e.g.,
limestone) and an a minu -bearing material (e.g., bauxite).
[ 023 In some embodiments, the cementitious component may comprise gypsum.
Gypsum is a material that sets in the presence of water to develop compressive strength,
Gypsum may be included in cements commonly referred to as gypsum cements. For use i
cements, gypsum may, in some instances, be burned at extremely high temperatures and then
ground, n particular embodiments, gypsum may be added to Portland cement,
[00.24] n some embodiments, the cementitious component may comprise a
pozzolanie material. Pozzolanie .materials thai may be suitable for use include a wide variety
o f 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, metakao!in, pumice, dia ma eous earth,
volcanic ash, opaline shale, tuff, and burned organic materials, such as agricultural waste
ash, municipal waste ash (e.g., municipal solid waste ash), waste-water treatment waste ash,
animal waste ash, non-hiim.an-non~ani.mal 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, co cob ash, ane
(e.g., sugar cane) ash, bagasse ash. grain e .. amaranth, bar ev co flaxseed- millet, oat.
quinoa, rye, wheat etc,) and related by-product(s) (e.g., husks, hulls, etc.) ash, orchard ash,
vine trimming ash, grass (e.g., Korai, Tifton, native s ba, etc.) ash, straw ash, ground nut
shell ash, legume (e.g., soybean) ash, and combinations thereof.
0025] In some embodiments, the cementitious component may comprise a kiln
dust. One example o f kiln dust Includes cement kiln dust . Cement kil dust, as that term is
used herein, refers to a partially calcined kiln feed which is removed from the gas stream and
collected, for example, i a dust coiiector during the manufacture of cement. The cement
kilo dust generally ma exhibit cemeniitious properties, in tha it may set a d harden in the
presence of water. Usually, large quantities o cement kiln dust are collected i the
production of cement thai are commonly disposed of as waste. isposal of the cement kiln
dust can add undesirable costs to the manufacture o the cement, as well as the
environmental concerns 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 feed, the efficiencies of the cement production operation, and
the associated dust collection systems. Cement kin dust generally may comprise a variety of
oxides, suc as Si0 , A 0 , Pe , CaO, MgC), $ ί , and Q Another example of a
kiln dust includes lime ki n dust. Lime kiln dust, s that term is used herein, refers to a
product generated in th manufacture of lime. The lime kiln dust may be collected, for
example, by dust control systems i the calcination of lime-stone.
[0026] n some embodiments, one or more parameters of the cemeniitious
component may be measured and then used .in determining the reactive index. The
parameters may include a number o different parameters that may be measured usi g
standard laboratory testing techniques for a sellable composition comprising a cemeniitious
component and water. Additional components may also be included in the se-ttable
compositions, for example, to vary on or more properties of the treatment fluid. Parameters
of the cementitious component, or settable composition contained therein, that may be
measured include, for example, compressive strength, Young's Modulus, fluid loss,
thickening lime, rheo ogiea values (e.g., volume average apparent viscosity, plastic
viscosity, yield point, etc and/or free water.
[0027] Compressive strength is generally the capacity of a material or structure to
withstand axially directed pushing forces. The compressi ve strength of the cementitious
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 fluid is mixed and the fluid is maintained at a
temperature of l?0°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
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 poundforce
per square inch (psi). Non-destructive methods typically may emplo an Ultrasonic
Cement Analyzer ("UCA"),, available from Fa instrument Company,, Houston, TX,
Compressive strengths may be determined n accordance with AP RP -2, Recommended
Practicefor Testing Well Cements, First Edition, July 2005,
[0028] 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. n general, a highly deformable
(plastic) material will 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 tested material
to withstand applied loads. 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 b en allowed to set for a period of time at specified temperature
and pressure conditions.
[0029] Fluid loss typically refers to loss of a fluid such as a treatment fluid nto 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 be measured using a static fluid-loss test, with either a static
or stirred fluid-loss cell, in accordance with th afore-mentioned AP RP Practice B-2.
[0030] Thickening time typically refers to the time a fluid, such as treatment fluid,
comprising the cementltious 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 amount of time a treatment fl id wil remain pumpable i a wel An
example technique for determining whether a treatment fluid is in a pumpable fluid state
may use a high-temperature high-pressure consistometer at specified pressure and
temperature conditions, in accordance with the procedure for determining cement thickening
times set forth in the afore-mentioned API RP Practice B-2. The thickening time may be
the time for the treatment fluid to reach 70 Bearclen units of consistency ("B ) and may be
reported in ti e to reach 70 B
[0031 ] h olog ca values of a fluid may be determined to characterize the fluid's
heolog ca behavior. he ogica values that ma be determined include volume average
apparent viscosity, yield point and plastic viscosity, among others. Plastic viscosity is
typically a measure of the resistance of fluid to flow. In some embodiments, the yield
point may be a parameter of the Bing am 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 longe deform elastically. In some embo e s, the
yield poi t may b a parameter of the Bingham plastic model, the yield point being th yield
stress extrapolated to a shear rate of zero. A number of different laboratory techniques may
be used to measure rheoiogieal values of a treatment fluid to g ve an indication of the
behavior of the treatment fluid in a well. Rheoiogieal values may be determined in
accordance with the procedure set forth in AP RP Practice S0B~2,
[0032] Free water typically refers to any water in 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 it sets. Free water may also be referred to
a 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 o the treatment fluid in a well.
Free water may be determined in accordance with the procedure set forth in AP RP Practice
1 B 2.
[0033] As previously mentioned, the reactivity of cementiiious components may
vary between different t p es of cementiiious components or even between different sources
for a particular typ of cementitious component. For example, the reactivity of Portland
cement and another cementitious component, such as a po olanic materia!, may be
different. By way of further example, the reactivity of a cementiiious component may vary
between different sources for the cementitious component n some embodiments, the
reactive index of the cementitious component may vary between two or more different
sources by a factor of at least about 2:1. For example, the reactive index of the cementitious
component between different sources may vary by an amount between any of and/or
including any of about 2 1, about 10: , about 50:1, about 100: about 250: about 500:1, or
about 1000:1. Because the reactivity varies between different cementitious components and
even between different sources for a cementitious component, the performance of different
cementitious components ay be unpredictable and may also lead to a lack of consistency
for the cementitious components when used n treatment fluids such as sellable
compositions, in some instances, the perionnance 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
components ma be used to provide a blended cementitious component that may have
properties suitable for use in a particular application. This may be particularly useful for
example, where one of the cementitious components i the blend may have properties
making it unsuitable for particular applications. For example, a cementitious component
such as cement k n dust from a first source may be blended with a cementiiious component
such as cement kiln dust fro a second source. n some embodiments, on or both of the
eementitious components may have reactivities thai are unsuitable for a particular
application For example, the reactivities of each cemeniitious component may be
individually too slow or too fast for a particular application, The blends of the eementitious
component from the two different sources may form a blended cemeniitious component
having compressive strength properties that ar suitable for the application. In some
embodiments, the relative proportions (e.g., weight fractions} of each eementitious
component in the blended eementitious component may the be adjusted to adjust the
compressive strength properties of the blended eementitious component.
[0035] The two or more eementitious components in the blended eementitious
component may include, for example, two or more different types of eementitious
components, such as Portland cement and cement ki n dust. Alternatively, the two or more
eementitious components in the blended eementitious component may include, for example,
a eementitious component from two or more different sources. For example, a first
eementitious component may comprise ce en kiln dust from a first source and the second
eementitious component may comprise cement kiln dust from a second source, t should be
understood that embodiments are not limited to only two different sources, but may include a
eementitious component, such as cement kiln dust, fro three, four, five, or even more
different sources. The two or more different sources for the eementitious component may
include different manufactures, different cement manufacturing plants, and the like A
eementitious component, such as cement ki ln dust which is byproduct f om 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 di.tYere.nt manufacturing
plants throughout the world at which cement kil dust can be generated.
[0036] The two or more eementitious components may be blended to form the
blended eementitious component, for example, prior to combination with water and/or other
components of the treatment fluid. n particular embodiments, the two or more eementitious
components may be dry blended to form a dry blend comprising the two or more
eementitious components. The dry blend may then be combined with water and/or other
components, n any order, t form the treatment fluid. However, the use of the term "biend"
is not intended to imply that the two or more eementitious components hav been dry
blended prior to combination with water. For example, the blend o two or more
eementitious components ma not be combined until after one, or even both, of the
eementitious components has already bee blended with water.
[0037] n some embodiments, the reactive index may be used to optimize the
blended eementitious component, wherein the blended eementitious component comprises
two or more cementitious components. For example, the reactive index may be used to
optimize o e or or parameters of the blended cementitious compo ent including
compressive strength. Young's Modulus, fluid loss, a d/or thickening time. Optimizing the
blended cementitious component may include determining the reactive index for each of the
e enliti s components i the blended cementitious component. The reactive indexes for
the cementitious components may then be used to predict th performance of the blended
cementitious component The ratio of each cementitious component may be adjusted to
optimize the performance of the blended cementitious component. The performance of the
blended cementitious component may be optimized with the performance of the blended
cementitious com onent estimated using the following equation:
Wherein s 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, j is the reactive index for cementitious component i, SSAj is the specific surface
area or cementitious component i, f is the mass fraction of the cementitious component I,
an is a number from . t 10. The set of cementitious components may include 2 or more
different cementitious components. The two or more different cementitious component may
he different types of cementitious components, such as Portland cement and slag, or may he
fro different sources, such as cement kil dust from a first source a d cement kiln dust
from a second source, i some embodiments, m may he , alternative embodiments,
may be /3.
[0038] In so e embodiments, the mean particle size of t e cementitious component
may be altered from its original particle size. The reactive index may the 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 fo r separating the cementitious component to provide a mean particle size
that as 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 use to decrease the
particle size of the cementitious component. Combinations of grinding and separating
may be used in some embodiments. The term "ground" or "grinding" as used herein means
using grinder (e.g., ball mill, rod mill, etc) to reduce the particie size of th specified
component(s). An example of a suitable grinder is an 8000 Mixer/Mil I* ball mill avai lable
from SPEX Sample Prep n some embodiments the cementitious component may be
ground for a time period in a range of about 30 minutes to abou S hour
[0039] The mean particle size of the cememitious component can be altered to any
size suitable for use in cementing operations. In some embodiments, the mean particle size
of the cementitious component may be altered from its original particie size to have a mean
particie size in a range of about micron to about 350 microns. The mean particle size
corresponds to d50 values as measured by particie size analyzers such as those manufactured
by Malvern instruments, Worcestershire, United Kingdom.
[0040] n some embodiments, the mean particle size of the cementitious component
may be increased from its original size, or example, the mean particle size of the
cementitious component may be at least 5% greater than ts original size in some
embodiments, at least 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 original size some
embodiments, the mea particle size may be increased to a size ranging between any of
and/or including any of about 5%, about 10%, about 20%, about 30% about 40%, abou
50%, about 60%,about 70% about 80%, about 90%, about 0%, about 200%, about 300%,
about 400%, or about 500% greater tha its original size.
[0041] n some embodiments, th mean particle size of the cementitious component
may he reduced from ts original size. For example, the mean particie size may be reduced
in an amount sufficient to increase the compressive strength of the cementitious component.
n some embodiments, the cementitious component may have a mean particle size that is at
least 5% less than its original size so e embodiments, a least a portion of the
cementitious component may be reduced to have a mean particie size n 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 any of and/or including any of about 5%, about 10%,
about i5%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about
50%, about 55%, about 60%, about 6%, about 70%, about 75%, about 80%, about 90%, or
about 95% of its original size. By way of example, the reduced particle size cementitious
component may have a mean particle size of less than about microns. n some
embodiments, the reduced particle size cementitious component may have a mean particie
size of less than about 10 microns, less than about 5 microns, less than about 4 microns, less
than about 3 microns, less than about 2 microns, or ess than about 1 micron n specific
embodiments, the .reduced particle size cementitious component may have a mean particle
s ze in a range of from about (5 1 microns to about 15 microns, from about 0.1 microns to
abou microns, o fro about micron to about SO microns. One of ordinary- skill in the
art, with th benefit of this disclosure, should be able to select a particle size for the
cementitious component suitable for a particular application.
[ 042] in s embodiments, the mean particle size of the cement kiln dust may be
reduced in an amount sufficient to provide a increase n compressive strength for the
settable composition. For example, the .mean particle i may be reduced to provide an
increase in compressive strength of at least about 5% about 25%, about 50%, abou 75%, or
about 0%
[0043] In accordance with present embodiments, the cemeniitious components may
be included in treatment fluids that can be used in a variety of operations that ay be
performed in subterranean formations. The cementitious component may have reactive
index calculated according to disclosed embodiments. n some embodiments, a blended
cementitious component may be used n some embodiments, the reactive index may be
used in determining the cementitious components in a particular blended cementitious
component. As referred to herein, the term "treatment fluid" wil be understood to mean any
fluid that ma 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 ofte are used i , e.g., we l drilling,
completion, and stimulation operations. Examples of such treatment fluids include drilling
fluids, wel cleanup fluids, wor v r 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 wel completion and
remedial operations, such as primary cementing of casings and lin rs in we bores. They
also may be useful for surface cementing operations, including construction cementing
operations. Accordingly, embodiments of the present invention disclose settable
compositions comprising a cementitious component and water.
[0045 The cementitious component may be included in embodiments of the settable
compositions in a amount suitable for a particular application. some embodiments, the
cementitious component may comprise cement kiln dust. The cement kiln dust may b
present i an amount in a range of from about 0 01% to 0% by weight of the cementitious
component ( b oc") For example, the cement kiln dust may b present in a amount
ranging beiween any o f and/or including any of about 0.01%, about 5%, about 1 %, about
20%, about 30%, 40%, about 50%, about 60%, about 70%, about 80%, about 90% or about
0%. The cementitious component may be free or essentially free (for example, no more
than .1% by weight of the cementitious component) of any additional cementitious
components other than the cementitious component, some embodiments, the cementitious
component may be essentially free of Portland cement. One of ordinary skill n the art with
the benefit of th s disclosure should be able to determine an appropriate amount of the
cementitious component to include for a particular application.
[0046] The water used in embodiments of the settable compositions of the present
invention ma include, for 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 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 p mpa e 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 5% by weight of the
cement speciilc embodiments, the water ma be included in an amount in the range of
from about 40% to about 50% bwoc. One of ordinary skill in th art, wit the benefit of
this disclosure, will 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 embodiments of the settable compositions, in accordance with embodiments
of the present invention. Examples of such additives include, but are not limited to, fiuidloss-
control additive, set retarder, strength-retrogression additives, set accelerators,
weighting agents, lightweight additives, gas-generating additives, mechanical-propertyenhancing
additives, lost-circulation materials, filtration-control additives, foaming
additives, thixotropic additives, and any combination thereof. Specific examples of these,
and other, additives include crystalline silica, amorphous silica, fumed silica, salts, fibers,
hydratable clays, calcined shale, vitrified shale, microspheres, hollow glas spheres, fly ash,
diatomaceous earth, raetakaolin, ground perlite, rice husk ash, natural pozzolan, zeolite,
cement kiln dust, resins, any combination thereof, and the ike A person having ordinary
skill in the art, with the benefit of this disclosure, wi l readily be able to determine the type
and amount of additive useful for a particular application and desired result.
[0048] Those of ordinary skill in the art ill appreciate that embodiments of the
sellable compositions generally should have a density suitable for a particular application.
By way of example, embodiments of t e sellable compositions may have a density of about
4 pounds per gallon b gaP ) to about 20 lb/gal in certain embodiments, the settable
compositions may have density of about lb/gal to about I? lb/gal. Embodiments of the
sellable compositions may be foamed or unfoamed or may comprise other means to reduce
their densities, such as hollow microspheres, low-density elastic beads, or other densityreducing
additives known in the art. n addition, the sellable composition may comprise
weighting agents or other means to increase their de sities Those of ordinary skill in the art,
with the benefit of this disclosure, wil recognize the appropriate density for a particular
application
[004 In some embodiments, the settable compositions have a thickening time
of greater than about 1 hour, alternative! v. greater than about 2 hours, alternative! v greater
tha about 5 hours at 3,000 psi and temperatures in &range of from about 50° to about
400 ' P alternatively, i a range of from about 80°F to about 250 F, and alternatively at a
temperature of about 140°F. n some embodiments, the settable composition may have a 24-
hour compressive strength in a range of from about 0 psi to about 10,000 psi and,
alternatively, from about 350 psi about 3,000 psi at atmospheric pressure and temperatures in
range of from about 50°F to about 400 I alternatively, in a range of from about 80°F to
about 250°F, and alternatively at a temperature of about 0 F
[0050] The components of the settable composition ay b combined in an order
desired to form a settable composition that ca be placed into a subterranean formation. n
addition, the components of the settable impositions may be combined using any mixing
device compatible with the composition, including a bu k mixer, for example in some
embodiments, a dry blend ay first b formed by the cementitious component or mixture o
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 settable
compositions as will be appreciated by those of ordinary skill in the art i accordance with
embodiments of the present invention.
[00 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
cementitious component and water, and allowed set. certain embodiments, the cement
composition may be introduced into a subterranean fo rmation and allowed to set therein. As
used herein, introducing the cement composition into 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 wel bore, or into both
[ 052] in primary-cementing embodiments, for example, embodiments may
comprise providing a cement composition, introducing the cement composition into a wellbore
ann lus; and allowing the cement composition to set n the a nul s to for a hardened
mass. The well-bore annul us may include, for example, an annular space between a conduit
(e.g., pipe string, liner, etc.) and a wall of a well bore or between the conduit and a larger
conduit in the well bore, Generally, in most instances, the hardened mass should fix the
conduit in the w bore.
[0053] In remedial-cementing embodiments, a cement composition may be used, for
example, in squeeze-cementing operations or in the placement of cement plugs. By way of
example, the cement composition may be placed i a we l bore to plug an opening, such as a
void or crack in the formation, in a gravel pack, in the conduit, i the cement sheath, and/or a
mic oann lus between the cement sheath and the conduit or formation. An example of such
a method may comprise piacing the cement composition into the void, a d allowing the
cement composition to set in th void.
[0054] While the preceding description is directed to the use o the cementitious
component in cementing methods, 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, n some embodiments, a blended
cementitious component may be used. n some embodiments, the reactive inde may be
used in determining the amount of cementitious components that are n a particular blended
cementitious 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. For example, a drilling fluid
may comprise the cementitious component, wherein the drilling fluid may be circulated
downwardly through 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).
0055] In some embodiments, a spacer fluid ay comprise the cementitious
component, which may have a determined reactive index according to disclosed
embodiments. Spacer fluids may be used, for example, the displacement of fluids fr om
well bore, in an embodiment, the fluid displaced by the spacer fluid comprises a drilling
fluid. By way of example, th spacer fluid ay be used to displace th drilling fluid from
the well bore. The drilling fluid ay include, or example, any number of fluids, such as
solid suspensions, mixtures, and emulsions. Additional steps in embodiments of the method
may comprise introducing a pipe string into the well bore, introducing a cement composition
into the w ll bore with the spacer fluid separating the cement composition and the first fluid.
In an embodiment, the cement composition may be allowed to set i the well bore. The
cement composition may include, for example, cement and water n some embodiments, at
least a portion of the spacer fluid may he left in the well bore, the spacer fluid in the well
bore setting to form a hardened mass
EXAMPLES
[0056] To facilitate a better understanding of the present invention, the following
examples of certain aspects of some embodiments ar given. In no way should the following
examples be read to limit, or define, the entire scope of the invention.
1
[0057] The react e indexes for compressive strength for thirty-three different
samples of cement kiln dust, designated Samples A through GO, were determined and are
provided n FIG. . The CKD samples are each from a different supply source, The reactive
indexes for thirty-three CKD samples were determined by dividing the determined 24-hour
compressive strength for settable 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 ass The surface area was
determined usin a Malvern particle size analyzer. The 24-hour compressive strength for
each CKD sample was determined by first 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 13 lb/ga After preparation, the settable composition was allowed t cure
for 24 hours in 2" x . 4 metal cylinder that was placed in a water bath at 170*F to form set
cement cylinders. Immediately after removal fr om the water bath, destructive compressive
strengths were determined using a mechanical press in accordance with AP RP 108-2.
Example 2
0058] Blended emen i ious components were prepared that comprised mixtures o
the CKD samples from Example 1 as indicated in the table below. The determined reactive
indexes for the CKD samples were then tsed in the following equation to predict the
performance of each blended cementitious component.
( :x)(SSA )(¾ -(R )(SSA )(Sv) + (R )(SSA )
Wherein ihe estimated compressive strength tor the blended cemeniMous
component, is the reactive index for comp ssive strength for CKD Sample Z and was
6.9, is 1, s the specific surface area for CKD Sample Z and was 2.32, ¾ is the mass
fraction of CKD Sample X, Rip is the reactive index for compressive strength for CKD
Sample and wa 105, SSAF is the specific surface area for CKD Sample F and was 2.33,
i the mass fraction of CKD Sample F R 1K is the reactive index for compressive strength for
CKD Sample E and was 107, SSA is ihe specific surface area for CKD Sample E was
3.6, and is the mass fraction of CKD Sample E.
[0059] The estimated compressive strength values for the blended eementitious
components were the compared with the actual 24-hour compressive strength values for the
blended eementitious components. The 24-hour compressive strength for each blended
eementitious component was determined by first preparing a seitable composition that
comprised the blended eementitious component i an amount of 100% bwoc and water in an
amount sufficient to prov de a density of B Sh/gaL A cement dispe s t (CF . cement
friction reducer, from Halliburton Energy Services, lac.) n an amount of fro 0,5% bwoc to
0 bwoc wa added to some of th samples and should not impact determined
compressive strength values. After preparation, the sellable composition was allowed to
cure for 24 hours n a 2" x 4'* metal cylinder that was placed in a water ath at 0 F to form
set cement cylinders. Immediately after removal from the water bath, destructive
compress e strengths were determined using a mechanical press in accordance w th AP P
10B-2.
[0060] 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 value of 0.952 and a slope of 0.9253. The estimated and actual compressive
strength values for the blended eementitious components are also provided in Table below.
Table
Example 3
[00 The reactive indexes for volume average apparent viscosity a 1 se 1 and
5 1 were determined for CKD Samples Z , F, d E from Example and are provided in
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 o 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 analyser. The 24-hour
volume average apparent viscosity ("VAV") for each CKD sample was determined by first
preparing a settable composition hat comprised the CKD sample in an amount of 0%
bwoc and water i an amount sufficient to provide a density of about ih/gaf. The volume
average apparent viscosities were measured at 5 1 ec and 5 see" in accordance with
API P iOB-2.
Table 2
[0062] Next, blended cementitious components were prepared that comprised
mixtures of CKD samples Z, , E, as indicated in the tabic below. The determined reactive
indexes at 5 sec and 5 1 sec"' for the CKD samples were then used in the following
equation to predict the performance of each blended cementitious conipotient.
tes (Rlz)(SSA )f¾;) )(SSA ¾iV} + ( I XSSA ) )
Wherein A is the estimated volume average apparent viscosity for the blended
eementitious component, ll is the .reactive index tor volume average apparent viscosity for
CKD Sample å, SSA is the specific surface area for CKD SampSe Z, t¾ is the mass fraction
of CKD Sample Z, is 7/3, 1¾ is the reactive inde x for volume average apparent viscosiiy
for CKD Sample F, SSA . is the specific surface area for CKD Sample F, f is the ass
{Taction of CKD Sample F, R¾ is the reactive index for volume average apparent viscosiiy
for CKD Sample E $$A¾ is the specific surface area for CKD Sample , and is the mass
fraction of CKD Sample E,
[0063 The estimated volume average apparent viscosities at 5 . sec ' and 5 1 sec "
for the blended eementitious components were then compared with the actual volume
average apparent viscosities at 5 se and 5 1 sec *' for the blended eementitious
components. The volume average apparent viscosities for each blended eementitious
component was determined by first preparing a sellable composition that comprised the
blended eementitious component in a amount of 100% bwoc and water in an amount
sufficient to provide a density of 1 lb/gal After preparation, the volume average apparent
viscosities at 5 see " and 5 see were determined in accordance w th AP F 0 -2.
[0064] Charts of the actual volume average viscosity values versus the estimated
volume average viscosity values are provided on F GS. 3 and 4. As shown on F G 3, the
charted values at 5 1 1 sec ' have an R value of 0.9894 an a slope of 0.9975. As shown on
FIG. 4, the charted values at 5 1 see " have an R2 value of 0.99 and a slope of 0.9814. The
estimated and actual volume average viscosity values for the blended eementitious
components are a so provided in Table 2 below.
Table 3
[0065] t should be understood that the compositions and methods are described in
terms of ''comprising," "containing," o "including ' various components or steps, th
compositions and methods can also "consist essentially of or "consist of the various
components and steps. Moreover, the indefinite articles "a" or "an. " as used in the claims,
are defined herein to mean one or ore than one of the element that Introduces.
[0066] For the sake of brevity, o ly 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, ranges fro 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 limi to recite a range not explicitly
recited. Additionally, whenever a numerical range wit a lower limit and an upper limit is
disclosed, any number and any included range falling within the range are specifically
disclosed. n particular, every range of values (of the form, "from about a to about V or,
eq iva en y, "from approximately a to b,w 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 limit, to recite a range not explicitly recited.
[0(167] Therefore, the present invention is well adapted to attain the ends and
advantages mentioned as well as those that are inherent therein. The particular embodiments
disclosed above are illustrative only, as the present invention may be modified and practiced
in different but equivalent manners apparent to those skilled .in the art having the benefit of
the teachings herein. Although 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, other than as described in the claims below.
Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly
and clearly defined by the patentee. 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 f there is any conflict in the
usages 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.

What is claimed is:
. A method of treating well comprising:
providing a treatment fluid comprising a base fl ui and a blended
cementitious component, wherein th 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 dus i selected from the group
consisting of lime kiln dust, cement kiln dust, and a combination thereof.
4 . The method of claim I wherein the kil dust comprises cement kiln dust, the
ceme t kiln dust being present in the treatment fluid a n amoun in a range of from about
0.01% to 0% by weight of by weigh of the blended cementitious component.
5. The method of claim wherein the treatment fluid is essentially free of any
additional cementitious components other than the blended cementi tious component.
6. The method of claim 1 wherein the treatment fluid is used in the well bore in
well dril ng,
7 The method of claim 1 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 1 wherein the amount of k ln 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 rheo ogi aS. value, free water, and any combination thereof.
10. The method of claim 1 wherein the kiln dust comprises a first kil dust from
a first source and a second kil dust .from a second source, and wherein the method further
comprises further comprises determining a reactive index for the first k ln dust and
determining a reactive index for th second kiln dust.
. The method of claim O:
wherein the step of determining the reactive index for the first kiln dust uses
the following equation:
wherein R i is the reactive index for the first kiln dust, is measured parameter of the
first kiln dust, and SS is th specific surface area of the first k dust; and
wherein the step of determining the reactive index for the second ki dust
uses the following equation;
RI MP2 / SSA
wherein Rf the reactive index fo the second kiln dust, is a measured parameter of
the second k ln dust, and SSA is the specific surface area of the second ki dust.
12 The method of claim 11 wherein the measured parameter i compressive
strength. Young's modulus, fluid loss, thickening time, a rheological value, free water, or
any combination thereof.
. The method of claim wherein performance of the blended eementitious
component is optimized using the following- equation:
fe i (Rl,)(SSA Xf ,) Rl (SSA )(f )m
wherein EP is an estimated parameter for the blended eementitious component, f is mass
fraction of firs kiln dust, f is mass fraction of the second kiln dust, and m is a number fro
1 to 0 and wherein the optimizing comprises adjusting f j and/or ¾.
4. A method of cementing comprising;
providing a settable composition comprising water and a blended
eementitious component, wherein th blended eementitious component conrsprises kiln dust
from two or .more different sources: and
allowing the settable composition to se to form a hardened mass,
15. The method of claim 14 wherein the kil dust is selected from the group
consisting of lime kiln dust, cement kiln dust, and a combination thereof
16. The metho of claim 14 wherein the kiln ust comprises cement kiln dust,
the cement ki n dust being present in the settable composition in an amount in a range of
from about 0.01% to 0% by weight of by weight of the blended eementitious component.
17. The method of claim 4 wherein the settable composition is essentially free
of an additional eementitious components othe than the blended eementitious compo ent
18. The method of claim 14 wherein the amount of kiln dust from each of the
two sources in the blended eementitious component is adjusted based on a parameter
selected from the group consisting of compress e strength. Yo ng s modulus, fluid loss,
thickening time, a rheological value, free water, and any combination thereof
19. The method of claim wherein the amount of ki l dust from each of the
two sources in the blended cementitious component is adjusted to adjust compressive
strength of the sellable composition.
20. The method of clai 1.4 wherein the ki ln dust comprises a first kiln dust from
a first source and a second kiln dust from a second source.
. 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 settahle
composition.
22. The method of claim 20 wherein particle size of the first kiln dust and/or the
second kiln dust ha been reduced by wa of grinding to adjust compressive strength of the
settahle composition.
23. The method of claim 20 wherein a reactive index for the first kiln dust and a
reactive index for the second k n dust vary by factor of a least about 2:1. .
24. The method of claim 20 wherein a reactive index for the first k ln dust and a
reactive inde for the second kiln dust vary by a factor of at least about 100; .
25. The method of claim 20 wherein the fir st 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 k dust and determining a reactive index for the second ki n dust.
27. The method of claim 26:
wherein the step of determining the reacti v index for the first kiln dust uses
the following equation:
wherein is the reactive inde for the first kiln dust, Pi is a measured parameter of the
first kiln dust, and SSAj 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:
wherein f is the reactive index for the second kiln dust, is a measured parameter of
the second kiln dust, and SSA 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 rheoiogical value, free water, or
a y combination thereof.
29. The method of claim 27 wherein performance of the blended cementitious
component is optimized using the following equation:
= S A (Rl2)(SSA:)½)"
wherein EP is a . estimated parameter for the blended cementitious component, i is mass
fractiori of first kiln dust, ¾is mass fraction of the second kiln dust, and is a value fro
to 10, and wherein the optimizing comprises adjusting ft and/or ¾
30. The method of claim 14 further comprising placing the settable composition
into a subterranean formation penetrated b a well bore
3 The method of claim 30 wherein settable composition is use h primary
cementing in the well bore.
32. The method of claim 30 wherein the settable composition is used remedial
cementing i 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 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 ,
35. A method of preparing blended cementitious component comprising:
providing first ki n dust, the first k st 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
36. A method of measuring reactivity of a kiln dust comprising;
measuring a parameter of the k n dust, the ki n dust having a specific surface
area; and
dividing the measured parameter by the specific surface area of the ki l dust
to obtain a reactive inde for the kiln dust.
37. A well treatment fluid comprising:
a base fluid; and
a blended ce en ti s 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 a y one of claims 1 to 5.