[0001] The present invention relates to spacer fluids for use n subterranean
operations and, more particularly, in certain embodiments, to foamed spacer fluids
comprising cement kiln dust C ) and methods of use i subterranean formations.
[0002] Spacer fluids are often used in subterranean operations to facilitate improved
displacement efficiency when introducing new fluids into a wel bore. For example, a spacer
fluid can be used to displace a fluid in a well bore before introduction of another fluid,
When used for drilling fluid displacement, spacer fluids can enhance solids removal as well
as separate the drilling fluid from a physically incompatible fluid. For instance, in primary
cementing operations, the spacer fluid may be placed into the well bore to separate the
cement composition from the drilling fluid. Spacer fluids may also be placed between
different drilling fluids during drilling change outs or between a drilling fluid and a
completion brine, for example.
[0003] To be effective, the spacer fluid can have certain characteristics. For
example, the spacer fluid may be compatible with the drilling fluid and the cement
composition. This compatibility may also be present at downhole temperatures and
pressures. n some instances, it is also desirable for the spacer fluid to leave surfaces the
well bore water wet, thus facilitating bonding with the cement composition. Rheology of the
spacer fluid can also be important. A number of different rheological properties may be
important in the design of a spacer fluid, including yield point, plastic viscosity, gel strength,
and shear stress, among others. While rheology can be important in spacer fluid design,
conventional spacer fluids may not have the desired rheology at downhole temperatures. For
instance, conventional spacer fluids may experience undesired thermal thinning at elevated
temperatures. As a result, conventional spacer fluids ma not provide the desired
displacement some instances.
SUMMARY
[0004] The present invention relates to spacer fluids for use in subterranean
operations and, more particularly, i certain embodiments, to foamed spacer fluids
comprising CKD a d methods o f use i subterranean- formations.
[0005] An embodiment discloses a method comprising: providing a foamed spacer
fluid comprising CKD, a foaming agent, a gas, and water: a d introducing the foamed spacer
fluid into a well bore to displace at -least a portion of a first fl ui present in the well bore.
[0006] Another embodiment discloses a method comprising: providing a foamed
spacer fluid comprising a partially calcined kiln feed removed from a gas stream, a foaming
agent, a gas, and water, wherein the partially calcined kiln feed comprises Si<¾, At ,
F , CaO, gO, S , a , and ¾ and introducing the foamed spacer fluid into a well
bore to displace at least a portion of a first fluid present n the well bore.
[0007] Yet another embodiment discloses a foamed spacer fluid comprising: CKD, a
foaming agent, a gas, and water, wherein the foamed spacer fluid has: a higher yield point at
130 F than at 80° F a higher yield point at 0° F than at F, and/or a higher plastic
viscosity at F than at 80 F.
[0008] The feaiures and advantages of the present invention wil be readily apparent
to those skilled in the art. While numerous changes may be made b those skilled in the art,
such changes are within the spiri t of the invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0009] The present invention relates to spacer fluids for use in subterranean
operations and more particularly in certain embodiments, to foamed spacer fluids that
comprise CKD and methods that use CKD t r enhancing one or more rheologicai properties
of a spacer fluid. There ma be several potential advantages to the methods a d
compositions of the present invention, only so e of which may be alluded to herein. One of
the many potential advantages of the methods and compositions of the present invention is
that the CKD may be used in spacer fluids as a rheology modifier allowing formulation of a
spacer fluid with desirable rheologicai properties. Another potential advantage of the
methods and compositions of the present invention is that inclusion of the CKD in the spacer
fluids may result in a spacer fluid without undesired thermal thinning. Yet another potential
advantage of the present invention is that spacer fluids comprising CK may be more
economical than conventional spacer fluids, which are commonly prepared with higher cost
additives. Yet another potential advantage of the present invention i that foamed spacer
fluids comprising CKD may be use for displacement of lightweight drilling fluids.
[0010] Embodiments of the spacer fluids of th present invention may comp se
water a d CKD. i some embodiments, the spacer flu ids may be foamed. For example, the
teamed spacer fluids may comprise water, CKD, a foaming agent, and a gas. A foamed
spacer fluid may be used, for example, where it is desired for the spacer fluid to be
lightweight. n accordance with present embodiments, th spacer fluid may be used to
displace a first fluid fro a well bore wit the spacer fluid having a higher yield point than
the first fluid. For example, the spacer fluid ay be used to displace at least a portion of a
drilling fluid from the well bore. Other optional additives may also be included in
embodiments of the spacer fluids as desired for a particular application. For example, the
spacer fluids may further comprise viseosifymg agents, organic polymers, dispersants,
surfactants, weighting agents, and any combination thereof.
[001 ] The spacer fluids generally should have a density suitable for a particular
application as desired by those of ordinary ski ll in the art, with the benefit of this disclosure.
n some embodiments, the spacer fluids may have a density in the range o from about 4
pounds per gallon ( T /ga " ) to about 24 lb/gal. n other embodiments, the spacer f ids may
have density in the range of about 4 lb/gal to about 17 lb/gal. n yet other embodiments,
the spacer fluids may have a density i the range of about 8 lb/gal to about 13 lb/gal.
Embodiments of the spacer fluids may be foamed or un.tbam.ed or comprise other means to
reduce their densities known in the art, such as lightweight additives. Those of ordinary skill
in the art, with the benefit of this disclosure, will recognize the appropriate density for a
particular application.
[0012] The water used an embodiment of the spacer fluids may include, for
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 that the water
does not contain an excess of compounds tha ma undesirably affect other components in
the spacer fluid, The water is included in an amount sufficient to form a pumpable spacer
fluid n some embodiments, the water may be included in the spacer fluids in an amount in
the range of from about 5% to about 95% by weight of the spacer fl uid in other
embodiments, the water may be included in the spacer fluids of th present invention in an
amount in the range of from about 25% to about 85% by weight of the spacer fluid. One of
ordinal*}-' skill in the art, with the benefit of this disclosure, will recognize the appropriate
amount of water to include for a . chosen application.
The CKD m be included in embodiments of the spacer fluids as a rheology
modifier. Among other things, using CKD in embodiments of the present invention can
provide spacer fluids having rheology suitable for a particular application. Desirable
rheology may e advantageous to provide spacer fluid that is effective for drilling fluid
displacement, for example. In some instances, the CKD can be used to provide a. spacer
fluid with a low degree of thermal thinning. For example, the spacer fluid may even have a
yield point that increases at. elevated temperatures, such as those encountered downhoie.
[00 4 CK is a material generated dur in the manufacture o cement that is
commonly referred to as cement kiln dost. The term "CKD' is used herei to mean cement
kil dust as described herein and equivalent forms of cement kiln dust made in other ways.
The term "CKD" typically refers to a partially calcined kiln feed which can be removed from
the gas stream and collected, for example, in a dust collector during the manufacture of
cement. Usually, large quantities of CKD are collected in the production of cement that are
commonly disposed of as waste. Disposal of the waste CKD can add undesirable costs to the
manufacture of the cement, as well as the environmental concerns associated with its
disposal. Because the CKD is commonly disposed as a waste material, spacer fluids
prepared with CKD may be more economical than conventional spacer fluids, which are
commonly prepared with higher cost additi ves. The chemical analysis of CKD from various
cement manufactures varies depending on a number of factors, including the particular kiln
feed, the efficiencies of the cement production operation, and the associated dus collection
systems. CKD generally may comprise a vari et of oxides, such a SiO , A € , ¾
Ca MgQ, S0 , Na , and K G.
[001 5] The C D may be included i the spacer fluids in an amount sufficient to
provide, for example, the desired Theological properties, n so e embodiments, the CKD
may be present in the spacer fluids in art amount in the range of from about 1% to about 65%
by weight of the spacer fluid (e.g., about 1%. about 5%. about % about 15%, about 20%,
about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about
60%, about 65%, etc.). In some embodiments, the CKD may be present in the spacer fluids
in an amount in the range of from about 5% to about 60% by weight of the spacer luid
some embodiments, the CKD may be present in an amount in the range of from about 20%
to about 35% by weight of the spacer fluid. Alternatively, th amount of CKD may be
expressed by weight of dry solids. As used herein, the term "by weight dry sol ids" refers to
the amount of a component, such as CKD, relati v to th overall amount of dry solids used in
preparation of the spacer fluid. For example, the CKD may be present in a amount in
ranee of fro about 1% to 0% v weight of drv solids (e.g.. about 1%. about 5%, about
10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%,
about 90%, 0%, etc.). In some embodiments, the CKD may b present i an amount in the
range of from about 50% to 100% and, alternatively, f om about 80% to 100% b weight of
dry solids. One of ordinary skill in the art, with the benefit of this disclosure, will recognize
the appropriate amount of CKD to include for a chosen application.
[0016] While the preceding description describes CKD, the present invention is
broad enough to encompass the use of other partially calcined kiln feeds. Fo example,
embodiments of the spacer fluids may comprise lime kiln dust, which is a material that is
generated during the manufacture of lime. The term lime kiln dust typically refers to a
partially calcined kiln feed which ca be removed from the gas stream and collected, for
example, in a dust collector during the manufacture of lime. The chemical analysis of lime
kiln dust from various lime manufactures varies depending on a number of factors, including
the particular limestone or doiomitic limestone feed, the type of kiln, the mode of operation
of the kiln, the efficiencies of the lime production operation, and the associated dust
collection systems. Lime kjln dust generally may comprise varying amounts of free lime and
free magnesium, lime stone, and or doiomitic limestone and a variety of oxides, such as
SiOj, i O , Cat) , MgO, ¾ Na 0 , and . , and other components, such as
chlorides.
[00 .17] Optionally, embodiments of the spacer fluids may further comprise fly ash.
A variety of fly ashes may e suitable, including f y ash classified as Class C or Class F fly
ash according to American Petroleum institute., AP Specification for Materials and Testing
for We Cements, API Specification 10, Fifth Ed., Ju 1, 990. Suitable examples of fly
ash include, st are not limited to, PO MLX A cement additive, commercially available
from Halliburton Energy Services, Inc., Duncan, Oklahoma. Where used, the fly ash
generally may be included n the spacer fluids n an amount desired for a particular
application, n some embodiments, the f y ash may b present in the spacer fluids in an
amount in the range of from about 1% to abou 60% by weight of the spacer fluid (e.g., about
5%, about %, about %, about 20%, about 25%, about 30%, about 35%, about 40%,
about 45%, about 50%, about 55%, etc.). in some embodiments, the fly ash ay be present
in the spacer fluids in an amount in the range of from about 1% to about 35% by weight of
the spacer fluid in some embodiments, the fly ash may be present in the spacer fluids n an
amount in the range o f from about % to about % by weight of the spacer fluid.
Alternatively, the amount of fly ash may be expressed by weight of dry solids. For example,
the fly ash may be present in an amount in a range of fro about % to about 99% by weight
of dry solids (e.g., about 1%, about 5%, about %, about 20%, about 30%, about 40%,
about 50%, about 60%, about 70%, about 80%, about 90%, about 99%, etc.). In some
embodiments, the fly ash may be present n an amount in the range of from about % to
about 20% and, alternatively, from about 1% to about % by weight of dry solids. One of
ordinary skill in the art, with th benefit of th s disclosure, will recognize the appropriate
amount of the fly ash to include for a chosen application.
[0 ] Optionally, embodiments of the spacer fluids ay further comprise a ree
water control additive. As used herein, the term "free water control additive" refers to an
additive included m a liquid for, among other things, reducing (or preventing) the presence
of free water n the liquid. Free water control additive may also reduce (or prevent) the
settling of solkls. Examples of suitable free water control additives include, but are not
limited to, bentonite, amorphous silica, hydroxyethyl cellulose, and combinations thereof
An example of a suitable free water control additive is SA~I0I5™ suspending agent,
available from Halliburton Energy Services, Inc. Another example of a suitable free water
control additive is WG~f7 " solid additive, available from Halliburton Energy Services, Inc.
The free water control additive may be provided as a dry solid in some embodiments. Where
used, the tree water control additive ay be present in an amount in the range of from about
0.1% to about 16% by weight of dry solids, for example. n alternative embodiments, the
free water control additive may be present in an amount in the range of from about 0.1% to
about 2% by weight of dry solids.
0 ί ] in som embodiments, the spacer fluids m further comprise a lightweight
additive. The lightweight additive may be included to reduce th density of embodiments of
the spacer fluids. For example, the lightweight additive may be used to form a lightweight
spacer fluid, for example, having a density o f less than about 3 lb/gal The lightweight
additive typically ma have a specific gravity of less than about 2.0, Examples of suitable
lightweight additives may include sodium silicate, hollow microspheres, gt om , perliie,
and combinations thereof. An example of a suitable sodium silicate is E N L TE
additive, available from Halliburton Energy Services, inc. Where used, the lightweight
additive may be present in an amount in the range of from about 0.1% to about 20% by
weight of dry solids, for example n alternative embodiments, the lightweight additive may
be present in an amount in the range of from about 1% t about % by weight of dry solids,
[0020] A previously mentioned, embodiments of the spacer fluids may be foamed
with a gas, for example, to provide a spacer fluid with a reduced density i should be
understood that reduced densities ma be needed for embodiments of the spacer fluids to
more approximately match the density o a particular drilling fluid, for example, where
lightweight drilling fluids are being used, A drilling fluid may be considered lightweight if it
has a density of less than about 13 lb/gal, alternatively, less than about. 10 lb/gal, and
alternatively less than about 9 lb/gal n some embodiments, the spacer fluids may be
foamed to have a density within about 10% of the density of the drilling fluid and,
alternatively, within about 5% of the density of the drilling fl uid While techniques, such as
lightweight additives, may be used to reduce the density of the spacer fluids comprising
CKD without foaming, these techniques may have drawbacks. For example, reduction of the
spacer fluid's density to below about 13 lb/gal using lightweight additives may produce
unstable slurries, which can have problems with settling of so lids, floating o lightweight
additives, and free water, among others. Accordingly, the spacer fluid may be foamed to
provide a spacer fluid having a reduced density that is more stable.
[00 1] Therefore, in some embodiments, the spacer fluids may be foamed and
comprise water, CKD, a foaming agent, and a gas Optionally, to provide spacer fluid with
a lower densit and more stable foam, the foamed spacer fluid may further comprise a
lightweight additive, for example. With the lightweight additive, a base slurry ma be
prepared tha may then be foamed to provide an even lower density, n some embodiments,
the foamed spacer fluid may have a density in the range of from about 4 lb/gal to about 13
lb/gal and, alternatively, about ? lb/gal to about 9 lb/gal. In one particular embodiment, a
base slurry may be foamed from a density of in the range of from about 9 lb/gal to about 3
lb/gal to a lower density, for example, in a range of from about 7 lb/gal to about 9 lb/gal.
[0022] The gas used in embodiments of the foamed spacer fluids ay be any
suitable gas for foaming the spacer fluid, including, but ot limited to air, nitrogen, and
combinations thereof. Generally, the gas should b present in embodi e s of the foamed
spacer fluids in an amount sufficient to form the desired foam. I certain embodiments, the
gas may be present in an amount in the range of from about 5% to about 80% by volume of
the foamed spacer fluid at atmospheric pressure, alternatively, about 5% to about 55% by
volume, and, alternatively, about . % to about 30% by volume.
[0023] Where foamed, embodiments of the spacer fluids may comprise a foaming
agent for providing a suitable foam. As used herein, the term "foaming agent" refers to a
material or combination of materials that facilitate th formation of a foam in a liquid. Any
suitable foaming agent for forming a foam in an aqueous liquid may be used in embodiments
of the spacer fluids. Examples of suitable foaming agents may include, but are not limited
to: mixture of an ammonium salt of an alkyl ethe sulfate, a cocoamidopropyl betaine
surfactant, a cocoamidopropyJdimethylamme oxide surfactant, sodium chloride, and water;
mixtures of a n ammonium salt of an alkyl ether sulfate surfactant, a cocoamidopropyl
hydroxysultaine surfactant, a cocoamidopropyl dimethylamme oxide .surfactant, sodium
chloride, and water; hydro ly ed keratin; mixture of an ethoxy Sated alcohol ether sulfate
surfactant an alkyl or alkene amidopropyS betaine surfactant, and an alkyl or alkene
dimethylamme oxide surfactant; aqueous solutions of an pha-o efin sulfonate surfactant
and a betaine surfactant; and combinations thereof An example of a suitable fo amin agen
is FOA E 760 foaraer/stabilixer, available from Halliburton Energy Services, Inc.
Suitable foaming agents are described in U.S. Patent Nos, 6,797,054, 6 547,87 , 6,367,550,
6,063,738, and 5,897,699, the entire disclosures of which a e incorporated herein by
reference
[0024] Generally, the foaming agent may be present in embodiments of the foamed
space fluids i an amount sufficient to provide a suitable foam. n some embodiments, th
foaming agent ma e present i an amount in the range of from about 0.8% to about 5% by
volume of the water ( bvo ) .
[0025] A wide variety of additional additives may be included in the spacer fluids as
deemed appropriate by one skilled n the art, with the benefit of this disclosure. Examples of
such additives include, but are not limited to, weighting agents, viscosity irig agents (e.g.,
clays, hydratable polymers, guar gum), fluid loss control additives, lost circulation materials,
filtration control additives, dispersants, defoamers, corrosion inhibitors, scale inhibitors,
formation conditioning agents. Specific examples of these, and other, additives include
organic polymers, surfactants, crystalline silica, amorphous silica, fumed silica, salts, fibers,
hydratable clays, microspheres, rice husk ash, combinations thereof, and the like, A person
having ordinary skill in the art, w th the benefit of this disclosure, will readil be able to
determine the type and amount of additive useful for a particular application and desired
result.
[0026] Embodiments of the spacer fluids of the present invention may be prepared in
accordance with any suitable technique. In some embodiments, the desired quantity of water
may be introduced into a mixer (e.g., a cement blender) followed b the dry blend. The dry
blend may comprise the CKD and additional solid additives, for example. Additional liquid
additives, if any may be added to the water as desired prior to, or after, combination with th
dry blend. This mixture may be agitated for a sufficient period of time to form a base slurry.
This base slurry may then be introduced into the we l bore via pumps, for example. n the
foamed embodiments, the base slurry may be pumped into the well bore, and a foaming
agent may be metered into the base slurry followed by injection o a gas, e.g., at a foam
mixing T, in an amount sufficient to foam the base slurry thereby forming a foamed spacer
fluid, in accordance with embodiments of the present invention. After foaming, the foamed
spacer fluid may be introduced into a well bore. As will b appreciated by those of ordinary
skill in the art, w th the benefit of this disclosure, other suitable techniques for preparing
spacer fluids ay he used in accordance with embodiments of the present invention.
[0027] An example method of the presen invention includes a method o f enhancing
rheoiogieal properties of a spacer fluid. The method may comprise including CKD in a
spacer fluid. The CKD may be included in the spacer fluid in an amount sufficient to
provide a higher yield point than a first fluid. The higher yield point may be desirable, for
example, to effectively displace the first fluid from the well bore. As used herein, the term
"yield point" refers to the resistance of a fluid to initial flow or representing the stress
required to start fluid movement in an embodiment, the yield point of the spacer fluid at a
temperature of up to about I 0 F is greater than about 5 b 0 ft 5. In an embodiment, the
yield point of the spacer fluid at a temperature of up to about 0°F is greater than abou 10
lb/ 100 n an embodiment, the yield point of the spacer fluid at a temperature of up to
about §0°F is greater than about 20 lb/ 0 ft. t may be desirable for the spacer fluid t ot
thermally thin to a yield point below the first fluid at elevated temperatures. Accordingly,
the spacer fluid may have a higher yield point than the first fluid at elevated temperatures,
such as 0° F or bottom hole static temperature ( S '). n one embodiment, the spacer
fluid may have a yield point that increases at elevated temperatures. For example, the spacer
f id may have a yield point that is higher at 180° F than at 80 . By way of further
example. The spacer fluid may have a yield point that is higher at ST tha at 8.0° F.
[0028] Another example method of the present invention includes a method of
displacing a first fluid from a we l bore, the well bore penetrating a subterranean formation.
The method may comprise providi a spacer fluid that comprises C D and water. The
.method may further comprise introducing the spacer fluid into the well bore to displace at
least a portion of the first fluid from the well bore. n some embodiments, the spacer fluid
may be characterized by having a higher yield point than the first fluid at 80°F. som
embodiments, the spacer fluid may be characterized by having a higher yield point than the
first fluid at 30°F. n some embodiments, the spacer fluid may be characterized by having a
higher yield point than the first fluid at °F.
[0029] n an embodiment, the first 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 he 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 introducing a pipe siring into the well bore, introducing a cement
composition into th well bore with the spacer fluid separating the cement composition and
the first fluid. n a embodiment, the cement composition ma be allowed to set in the well
bore. The cement composition may include, for example, cement and water.
[0030] Another example method of the present invention includes a method of
separating fluids in a well bore, the well bore penetrating a subterranean formation. The
method may comprise introducing a spacer fluid into the well bore, the well bore havin a
first fluid disposed therein. The spacer fluid ay comprise, for example, CKD and water.
The method may further comprise introducing a second fluid into the well bore with the
spacer fluid separating the first fluid and the second fl uid t n an embodiment, the first fluid
comprises a drilling fluid and the second fluid comprises a cement composition. By way of
example, the spacer fluid may prevent the cement composition from contacting the drilling
fluid. n an embodiment, the cement composition comprises cement kiln dust, water, a d
optionally a hydraulic ement tious material. A variety of hydraulic cement may be utilized
in accordance with the present invention, including, but not limited to, those comprising
calcium, aluminum, silicon, oxygen, iron, and/or sulfur, which set and harden by reaction
with water. Suitable hydraulic cements include, but are not limited to Portland cements,
poz o ana cements, gypsum cements, high alumina content cements, slag cements, silica
cements, and combinations thereof. n certain embodiments, the hydraulic cement may
comprise a Portland cement. n some embodiments, the Portland cements that are suited for
use in th present invention are classified as Classes A, C, , and G cements according to
American Petroleum institute, API Specification for Materials and Testing for Well
Cements, API Specification 0 , Fifth Ed., Jul. , 1990. The spacer fluid ma also remove
the drilling fluid, dehydrated/gelled drilling fluid, and/or filter cafe solids from the well bore
in advance of the cement composition. Removal of these compositions from the well bore
enhance bonding of the cement composition to surfaces in the well bore n an
additional embodiment, at least portion of used and/or unused CKD containing spacer fluid
are included in the cement composition that is placed into the well and allowed to set
003 1 To Facilitate a better understanding of the present invention, the following
examples of certain aspects of some embodiments ar given. n no way should the following
example he read to limit, or define, th scope of the invention in the following examples,
concentrations are given in weight percent of the overall composition.
EXAMPLE
[0032 Sample spacer fluids were prepared to evaluate the rheologicai properties of
spacer fluids containing CKD The sample spacer fluids were prepared as follows. First, a
dry components (e.g., CKD, fly ash, ben on te, FWCA, etc) were weighed into a glass
container having a clean lid and agitated by hand int.i blended, tap water was then weighed
into a Waring blender jar. The dry components were then mixed into the water with 4,000
rpm stirring. The blender speed was then increased to ,000 rpn for about 35 seconds
[0033] Sample Space F uid No, 1 was an pound per gallon slurr that comprised
60,62% water, 34 . %CKD, 4,63% fly ash, and 0,58% free water control additive (WO 17
solid additive).
J0034] Sample Spacer Fluid No. 2 was an 1 poun per gallon slurry that comprised
60.79% water, 30.42% CKD 4 1 % y ash, 0.17% free water control additive (WG S
solid additi ve), 3,45% bentonite, and .04% Econo!ite^ additive.
[0035] Rheologicai values were then determined using a ane Model 35
Viscometer. Dial readings were recorded at speeds of 3, 6 0 , 200. and 300 with a bob,
rotor, and a 1.0 spring. The dial readings, plastic viscosity, and yield points for the
spacer fl uids were measured in accordance with AP Recommended Practices IOB, Bingham
plastic odel and are set forth in the table below. The abbreviation PV refers to plastic
viscosity, while the abbreviation ' R refers to yield point.
i
TABLE
[0036] The thickening time of the Sample Spacer Fluid No, was also determined in
accordance with AP Recommended Practice B at 205° F. Sample Spacer Fluid No, had
thickening time of more tha 6 :00÷· hours at 35 15c.
[0037] Accordingly, the above example illustrates that the addition of CKD to a
spacer fluid may provide suitable properties for use n subterranean applications. In
particular, the above example illustrates, inter alia, thai CKD may be used to provide a
spacer fluid thai may not exhibit thermal thinning with the spacer fluid potentially even
having a yield point that increases with temperature. For example, Sample Spacer Fluid No.
2 had a higher yiel point at 1 0° F tha n at 80° F. hi addition, the yiel point of Sample
Spacer Fluid No. .1 had o ly a slight decrease at . 0° F as compared to 80* F. Even further,
the example illustrates that addition of CKD to a spacer fluid may provide a plastic viscosity
that increases with temperature,
EXAMPLE 2
[0038] Additional sample spacer fluids were prepared to further evaluate the
rheoiogicai properties of spacer fluids containing CKD, The sample spacer fluids were
prepared as follows. First, all dry components (e.g., CKD, f y ash) were weighed info a glass
container having a clean id and agitated by hand until blended. Tap water was then weighed
into a Waring blender j ar The dry components were then mixed into the water with 4,000
rpm stirring. The blender speed was then increased to 2,000 rpm for about 35 seconds.
[0039] Sample Fluid No. 3 was a 2.5 pound per gallon fluid that comprised 47.29%
water and 52.71% CKD.
[0040] Sample Fluid No. 4 was a 2.5 pound per gallon fluid that comprised 46.47%
water, 40. % CKD, and .38% fly ash,
[0041] Sample Fluid No. was a 1.2.5 pound per gallon fluid that comprised 45.62%
water, 27. % CKD, and 27.19% fly ash.
[ 4 2] Sample Fluid No. 6 was a .5 pound per gallon fluid that comprised 44.75%
water, 13.81% CKD, and 4 .44% f y ash.
[0043] Sample Fluid No, 7 (comparative) was a 12.5 pound per gallon fluid that
comprised 43.85% water, and 56. % fly ash.
[0044] Rheologica! values were then determined using a Farm Model 35
Viscometer, Dial readings were recorded at speeds of 3. 6, 30 60, 0, 200, 300, and 600
with a B bob, an I I rotor, and a .0 spring. The dia readings, plastic viscosity, and yield
points for the spacer fluids were measured in accordance with API Recommended Practices
OB, Bingham plastic mode! and are set forth in the table below. The abbreviation PV
refers to plastic viscosity, while- the abbreviation "YP" refers io yield point.
TABL 2
[0045] Accordingly, the above example lustrate s that the addition of CKD o a
spacer fluid ma provide suitable properties for use i subterranean applications. In
particular, the above example illustrates, inter alia, that CKD may be used to provide a
spacer fluid that may not exhibit thermal thinning with the spacer fluid potentially even
having a yie d point that increases with te perature n addition, as illustrated i Table 2
above, higher yield points were observed for spacer fluids with higher concentrations of
CKD.
EXAMPLE 3
[0046] A sample spacer fluid containing CKD was prepared to compare the
rheoiogical properties of a spacer fluid containing CKD with an oil-based drilling fluid. The
sample spacer fluid was prepared as follows. First, all dry components (e.g., CKD, fly ash,
bentontte, etc.) wer weighed into a glass container having a clean lid and agitated by hand
until blended. Tap water was then weighed into a Waring blender jar. The dry components
were then mixed into the water with 4,000 rp stirring. The blender speed was then
increased to 12,000 rpm for about 35 seconds.
[0047 Sample Spacer Fluid No. S was an pound per gallon slurry thai comprised
60.79% water, 30.42% CKD, 4. 3% fly ash, 0.1 % free water control additive (WG-17™
solid additive), 3.45% benionite, and 1.04% Eeo oli e additive.
[0048] The oϊ -based drilling fu d was a 9, pound per gallon oil-based mud
[0049] Rheoiogical values were the determined using a Fann Model 35
Viscometer. Dial readings were recorded a speeds of 3, 6, 0, 200, and 300 with a bob,
an R 1 rotor, and a 1.0 spring. The dial readings, plastic viscosity, and yield points for the
spacer fluid and drilling fluid were measured in accordance with AP Recommended
Practices B, Bingham plastic model a d are set forth in the table below. The abbreviation
"PV" refers to plastic viscosity, while the abbreviation YP refers to yield point. The
abbreviation " BM" refers to oil-based mud.
TABLE 3
[0050] Accordingly, the above example illustrates that the addition of CKD to a
spacer fluid may provide suitable properties for use in subterranean applications. n
particular, the above example illustrates, inter alia, that CKD may be used to provide a
spacer fluid with a yield point that greater tha a drilling fluid even at elevated
temperatures. For example, Sample Spacer Fluid No. 8 has a higher yield point at 180° F
than the oil-based mud.
EXAMPLE 4
foanrsed spacer fluid was prepared that comprised. CKD. First, a base
slurry was prepared that had a density of 10 lb/gal and comprised CKD, a free water control
additive (0.7% by weight of CKD), a lightweight additive (4% by weight of CKD), and fresh
water (32. gallons per 94-pound sack of CKD). The free water control additive was SA¬
! 5™ suspending aid. The lightweight addit e wa EC N L TE additive. Next, a
foaming agent (FOA 760 amer/ s abtli er) in an amount o f 2% bvow was added,
and the base slurry was then mixed in a fo a blending jar for 4 seconds at. ,000 rp . The
resulting foamed spacer fluid had density of 8.4 lb gal. The of the resultant foamed
spacer fluid was then measured using a free fluid test procedure as specified in API
Recommended Practice 108. However, rather than measuring the fre fluid, the amount of
" " was measured after the foamed spacer fluid remained static for a period of 2 hours.
The foamed spacer fluid was initially at 200° and cooled to ambient temperature over the 2-
hour period. The measured sink for th s foamed spacer fluid was 5 millimeters.
EXAMPLE 5
[0052] Another foamed spacer fluid was prepared that comprised CKD. First, a base
slurry was prepared that had a. density of 10.5 lb/gal and comprised CKD, a. free water
control additive (0 6% by weight of CKD), a lightweight additive (4% by weight of CKD),
and fresh water (23.7 gallons per 94-pound sack of CK ). The free water control additive
was SA- 5™ suspending aid. The lightweight additive was ECONOLITE™ additive.
Next, a foaming agent (a hexylene g!yeol/eoeobetaine blended surfactant) in an amount of
2% bvow was added, and the base slurr was then mixed in a foam blending jar for 6
seconds at 12,000 rpm. The resulting foamed spacer fluid had a density of 8.304 lb/gal. The
resultant foamed spacer fluid had a sink of 0 millimeters, measured as described above for
Example 4.
[0053] Therefore, the present invention is we l adapted to attain the ends and
advantages mentioned as well as those that are inherent therein. Although individual
embodiments are discussed, the invention covers all combinations of al those embodiments.
The particular embodiments disclosed above are illustrative only, as the present invention
may be modified and practiced in different but equivalent manners apparent to those skilled
in the art having the benefit of the teachings herein. Furthermore, no limitations are intended
to the details of construction or design herein shown, other than as described in the claims
below. It is therefore evident tha the particular illustrative embodiments disclosed above
may be altered or modified and all such variations are considered withi the scope and spirit
of the present invention. While compositions and methods are described n terms o
"comprising," "containing," or "including" various components or steps the compositions
and methods ca also "consist essentially of or "consist o the various components and
steps. Whenever a nuraerical range with a lower limit and an upper limit is disclosed, any
number and any included range falling within the range is specifically disclosed.
particular, every range of va es (of the form, "from about a to about " or, equivalent!} ,
approximately a to b, or, equivalent!y, "from approximately a b ) disclosed herein is
to be understood to set forth every number and range encompassed within the broader range
of values. Also, the terms in the claims have their plain, ordinary meaning unless otherwise
explicitly and clearly defined by the patentee.

WE CLAIMS:-
. A method comprising:
providing a foamed spacer fluid comprising cement kiln dus a foaming
agent, a gas, a d water; and
introducing the foamed spacer fluid into a we bore to displace at least a
poriion of a irst fluid present in th well bore.
2. A method according to claim ί wherein the cement kiln dust s present in the
foamed spacer fluid in an amount in a range of iror about 1% to about 60% by weight of the
foamed spacer fluid.
3 . A method according to claim 1 or claim 2 wherein the cement kiln dust is
present in the foamed spacer fluid in an amount in a range of from about 80% to 100% by
weight of dry solids.
4. A method comprising:
providing a foamed spacer fluid comprising partially calcined kiln feed
removed rom a ¾as stream, a foaming aeent, a gas, and water, wherein the partially calcined
kiln feed comprises Si Fc¾0¾, CaO, VfgO SO?, Na^O, and ; and
introducing the foamed spacer fluid into a well bor to displace at least a
portion of first fluid present in the we bore.
5. A method according to claim 4 wherein the partially calcined kiln feed is
present in the foamed spacer fluid in an amount in a range of from about 1% t about 60%
hy weight of the foamed spacer fluid.
6. A method according to claim 4 or claim. 5 wherein the partially calcined k ln
feed is present i the foamed spacer fluid in an amount in a range of from about 80% to
00% by weight of dry solids,
7. A method according to any one of claims 4 to 6 wherei the partially
calcined kiln feed is collected in dust collector,
S. A method according to any of claims 4 to 7 wherein the partially calcined
kiln feed is from th manufacture of cement,
9 . A method according to any of claims 4 to 7 wherein the partially calcined
k ln feed is from the manufacture of lime.
10. A method according to any one of the preceding claims wherein the foamed
spacer fluid has a yield point at 80° that is higher than a yield point of the first fluid at 80°
1. A .method according to any one of the preceding claims wherein the foamed
spacer fluid has a yield point at .80 F thai is higher than a yield point of the first fluid at
. A method according to an one of the preceding claims wherein the foamed
Spacer fluid has a higher yield point at bottom hole static temperature of the well: bore t a at
F,
13. A method according o an one of th preceding claims wherein the yield
point of the foamed spacer fluid a i.8 F is greater than about 20 lb/100 IV .
A method according to any one of the preceding claims wherein the foamed
spacer fluid. as a density n a range of from about 4 lb/gal to about lb/gal.
. A method according to any one of the preceding claims wherein providing
the foamed spacer fluid comprises foaming a base slurry from a density in range of from
about 9 lb/gal to about S3 lb/gal to a density in a range of from about 7 lb/gal about 9
ib/aaf,
. A method according to claim wherein foaming the base slurry comprises
providing a base slurry comprising the cement kiln dust, a lightweight additive, a f ee water
control additive, and the water; and adding the foaming agent to the base s rry.
7. A method according to any one of the preceding claims wherein the gas
comprises at. least one gas selected from the group consisting of air, nitrogen, and any
combination thereof an wherein the foaming agent comprises at leas o e additive selected
from the group consisting of a mixture of an ammonium salt of an aikyl ether sulfate, a
cocoamidopropyl betaine surfactant, a cocoamidopropyl ditnemylamine oxide surfactant,
sodium chloride, and water; a mixture of an ammonium salt of an aikyl ether sulfate
surfactant, a cocoamidopropyl hydroxysultaine surfactant, a cocoamidopropyl
dimet y am ne oxide surfactant, sodium chloride, and water; ydroly ed keratin; a mixture
of an ethoxyiatecl alcohol ether sulfate surfactant, an alky! or alkene amidopropyl betaine
surfactant, and an aikyl or alkene dimethylamine oxide surfactant; an aqueous solution of an
alpha-olelinic sulfonate surfactant and a betaine surfa ctant; and any combination thereof
. A method according to any one of the preceding claims wherein the foamed
spacer fluid further comprises at least one additive selected from the group consisting of a
free water control additive, a lightweight additive, a weighting agent, a viscosifying agent, a
fluid loss control additive, lost circulation material, a filtration control additive, a
dispersani, a corrosion inhibitor, a scale inhibitor, a formation conditioning agent, and any
combination thereof.
. A method according to any one of the preceding claims wherein the foamed
spacer fluid further m ri e at least o e additive selected from the group consisting of fly
ash, a clay a hydraiahSe polymer, guar gum, an organic polymer, a surfactant, crystalline
silica, amorphous silica, fume silica, a salt, a fiber, hydratable c ay, a microsphere, rice
husk ash, and any combination thereof,
20. A method according to any one of the preceding claims wherein the first
fluid comprises a drilling fluid,
2 . A method according to claim 20 further comprising introducing a cement
composition into the well bore to displace at least a portion of the spacer fluid present in the
well bore, wherein the spacer fluid separates the cement composition from th drilling fluid.
22. A .method according to a y one of the preceding claims further comprising
introducing a cement composition into the well bo e to displace at least a portion of the
spacer fluid present in the well bore, wherein the cement composition comprises cement kiln
dust.
23. A foamed spacer fluid comprising:
cement kil dust,
a foaming agent,
a gas, and
water,
wherein the foamed spacer fl id has:
(a) a higher yield point at 0 P than at 80° F,
b) a higher yield point at 0 F tha at 8 F, and/or
(c) a higher plastic viscosity at 1S0 F than at " F.