SETTABLE COMPOSITIONS COMPRISING CEMENT KILN DUST AND
METHODS OF USE
BACKGROUND
[0001] Embodiments relate to settable compositions and, more particularly,
embodiments relates to the use of alkali aluramates and alkali silicates with cement k l dust
to form a settable composition for use in subterranean operations.
[0002] A natural resource such as oil or gas residing in a subterranean formation can
b recovered by drilling a wellbore into the formation. A wellbore is typically drilled while
circulating a drilling fluid through the wellbore. Among other things, the circulating drilling
fluid ay lubricate the drill bit, carry drill cuttings to the surface, and balance the formation
pressure exerted on the wellbore. One problem associated with drilling may b the
undesirable loss of drilling fluid to the formation. Such lost fluids typically may go into, for
example, pre-existing fractures, induced fractures, cracks, vugs, channels, or other openings
through which fluid may be lost This problem ma be referred to as " ost c culation, and
the sections of the formation into which the drilling fluid (or other fluid) ay be lost may be
referred to as ost circulation zones." The loss of drilling fluid into the formation is
undesirable, inter alia, because of the expense associated with the drilling fluid lost into the
formation, loss of time, additional easing strings and, n extreme conditions, well
abandonment. n addition o drilling fluids, problems with lost circulation may also be
encountered with other fluids, for example, spacer fluids, completion fluids (e.g., completion
brines), fracturing fluids, and cement compositions that may b introduced into a wellbore.
[0003] A number of techniques have been developed for combating lost circulation
one of which involves the placement of lost circulation materials into the lost circulation
zone. Conventional lost circulation materials may include fibrous, ame !aied or granular
materials. The lost circulation materials may be placed into the formation, inter alia, as part
of a dri lling fluid or as a separate los circulation pill in an attempt to control and/or prevent
lost circulation. Another technique that has bee developed to control lost circulation
involves the placement of a settable composition into the wellbore to seal the lost circulation
zone. Fo a number of reasons, however, these techniques ay not provide a desirable level
of lost circulation control in all circumstances.
BRIEF DESCRIPTION OF TOE DRAWINGS
[0004] These drawings illustrate certa aspects of some of the embodiments of the
present method, and should not be used to limit or define the method.
[0005] F G. illustrates an embodiment of a e Ibore penetrating a subterranean
formation with a lost circulation zone extending into the subterranean formation.
[0006] FIG. 2 illustrates an embodiment of introduction of a setfable composition
into the lost circulation zone of FIG. 1.
[0007] FIG. 3 illustrates a system for the preparation and delivery of a sellable
composition into a vvellbore in accordance with certain embodiments.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0008] Embodiments re to settable corn-positions arid, in certain embodiments, to
use of alkali aluminates and alkali silicates with cement kil dust to for a sellable
composition for use in subterranean operations. There may be several potential advantages to
the present methods and compositions, only some of which may be alluded to herein. One of
the many potential advantages of the present methods and compositions i tha the settable
composition may rapidly form a non-ikn-vabie gel, which can b used to bridge off and plug
the lost circulation zones, which may include fractures (natural or pre-existing), cracks, vugs,
channels, and/or other openings through which fluid ma be lost. Because a minor portion
of the settable composition may remain an active free fluid in a flowa le liquid state even
after formation of the non-flowable gel, the active free fluid may penetrate further into the
formation a d act to provide improved sealing capacity for the settable composition. Another
potential advantage of the methods and compositions may be that, by including the cement
kiln dust, the settable composition sets into a hardened ass with reasonable compressive
strength to more effectively prevent oss of fluid circulation.
[0009] An embodiment of the settable compositions may comprise cement kiln dust,
an alkali aluminate, an alkali silicate, and an aqueous carrier fluid. Embodiments of the
settable compositions may further comprise one or more additional additives, such as a
bridging material. Those of ordinary skill in the art will appreciate that embodiments of the
settable compositions generally should have a density suitable for a particular application.
By way of example, the settable composi tions may have density in the range of from about
5 pou ds per gallon " b ga ) to about 25 ppg, in certain embodiments, th settable
compositions may have a density in the range of fro about 8 lb/gal to about 1 lb/gal and,
alternatively, about 9 lb/gal to about I I lb/gal Embodiments of the ost circulation
compositions may e foamed or fo amed or ma comprise other means to reduce their
densities, such as hollow microspheres, low-density elastic beads, or other density-reducing
additives known in the art. Weighting agents may also be used to increase the density of the
settable compositions, in some embodiments. Those of ordinary skil in the art, with the
benefit of this disclosure, will recognize the appropriate density for a particular appl ication,
j00 . The settable compositions may comprise cement kiln dust. Cement kiln dust,
as thai te r is used herein, refers to a solid material generated a a by-product of the heating
of certain materials in kilns during cement production. The term "cement kiln dost" as used
herein is intended to include cement kiln dust made as described herein and equivalent forms
of cement kiln dust. Depending on its source, for example, the cement kiln dust may exhibit
cemeutitious properties in that it can set and harden in the presence of water. Cement ki ln
dust may be generated as a by-product of cement production that is removed from the gas
stream a d collected, for example, a dust collector. Usually, large quantities of cement
kiln dust are collected in the production of cement that are commonly disposed of as waste.
Disposal of the cement kil dust can add. undesirable costs to the manufacture of the cement,
as well as the environmental concerns associated with its disposal. The chemical analysis of
the cement kil dust from various cement manufactures varies depending on a number o
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, such as Si ¾ A ¾, Pe ¾, CaO, gO, S ¾ Na?0, and K O
[001 n some embodiments, the cement kilo dust may he included in the settable
composition as a cemeniitious component that can set and harden by reaction with water n
add ion the cement k ln dust may also function as a bridging material that can bridge across
fractures, cracks, vugs, channels, or other openings in the lost circulation zone. The cement
kiln dust may also reinforce th non f owab e ge formed by the seitable composition. The
cement kiln dust may be present in the seitable composition in. an amount in th range of
from about % to about 30% by weight of the seitable composition and, alternatively, fr om
about 5% to about 25% by weight of the sellable composition. For example, the cement ki n
dust ay be included i an amount of about 1%, about 5%, about 10%, about 15%, about
20%, or about 25% by weight of the seitable composition. In some embodiments, the sellable
composition may be free or essentially free (<0,5% by weight) of an additional
cemeniitious components other than the cement kiln dust. One of ordinary skill in the art,
with the benefit of this disclosure, should recognize the appropriate amount of cement kiln
dust to include for a chose application,
[0012] The sellable compositions may further comprise an alkali aluminate. The
alkali aluminate may comprise any alkali metal, including, but not limited to, lithium.,
sodium, potassium, rubidium, cesium, and r ncium. n a particular embodiment, the alkali
aluminate comprises sodium aluminate, n some embodiments, the alkali aluminate ma be
provided as an aqueous alkali aluminate in which the alkali aluminate has been dissolved in
water. A example of a suitable aqueous alkali aluminate is VersaSet L ihixotropic additive,
available from Halliburton Energy Services, nc. The alkali aluminate may be present in the
seitable composition in an amount in th range of from about J.% to about 40% by weight of
the sellable composition and, alternatively, from about 5% to about 30% by weight of the
settable composition. For example, th alkali aluminate may be included in an amount of
about 1%, about 5%, about 10%, about , about 20%, about 25%, about 30% about 35%,
or about 40 by weight of the settable composition. One of ordinary skill in the art:, with the
benefit of this disclosure, should recognize the appropriate amount of the alkali aluminate to
include for a chosen application.
[00 ] The settable compositions may further comprise an alkali silicate. The alkali
silicate may interact with the alkali aluminate to lor ) a ge The gei may be a non-flowabie
gel that comprises a three-dimensional network based on interaction between the alkali
silicate a d alkali aluminate. The formation of the gel may be acid or base catalyzed. The
reaction may be quicker where base catalyzed with a slower reaction if acid catalyzed. The
alkali silicate may comprise an alkali metal, including, but not limited to, lithium, sodium,
potassium, rubidium, cesium, and ran um. I.n a particular embodiment, the alkali silicate
comprises sodium silicate. n some embodiments, the alkali silicate may be provided as an
aqueous alkali silicate n which the alkali silicate has bee dissolved in water. An example of
a suitable aqueous alkali silicate is Liquid Ee nol te additive, available from Halliburton
Energy Services The aqueous alkali silicate may be formed by adding colloidal silica to
sodiu hydroxide. The ratios of the colloidal silica to sodium hydroxide may be adjusted to
change p and silica dissolution, among others. The alkali silicate ay be present in the
settable composition in an amount i the range of from about 1% to about 40% b weight of
the setiable composition and, alternatively, from about 5% to about 30% b weight of the
settable composition. For example, the alkali silicate may be included n an amount of about
%, about 5%, about 0%, about 15%, about 20%, about 25%, about 30%, about 35%, or
about 40% by weigh of the settable composition. One of ordinar skill in the art, with the
benefit of this disclosure, should recognize the appropriate amount of the alkali silicate to
include or a chosen application.
[0 4] The settable composition ay further comprise an aqueous carrier fluid. The
aqueous carrier fluid may comprise any of a variety of different aqueous fluids, including,
but not limited to, tap water, fresh water, de-ionized water, salt water, and combinations
thereof Generally, the aqueous carrier fluid may be from any source, provided that the
aqueous carrier fluid does ot contain an excess of compounds that may undesirably affect
other components in the treatment fluid. The aqueous carrier fluid may be included in an
amount in a range of from about 1 % to about 80% by weight of the settable composition
and, alternatively, fro about 30% to about 60% by weight of the settable composition
[0015] A wide variety of additional additives may be included in the settable
compositions as deemed appropriate by o e skilled in the art, with the benefit of this
disclosure. Examples of such additives include but ar not limited to: weighting agents,
lightweight additives (e.g., microspheres) viscosifying agent (e.g., clays, h dratab e
polymers, guar gum), free water control additives, fluid loss control additives, bridging
agents dispersanis, foaming additives (e.g., foaming surfactants), defoamers, corrosion
inhibitors;, .scale inhibitors, formation condition tag agents, a d water-wetting surfactant.
Specific examples of these, and other, additives include: organic polymers, biopolymers,
latex, ground rubber, surfactants, crystalline silica, amorphous silica, silica floor, fumed
silica, nano~elays (e.g., clays havi g at least one dimension less than 0 ran), salts, fibers,
hydratable clays, microspheres, rice husk ash, micro-fine cement e.g. cement having an
average particle size of from about 5 microns to about 10 microns), metakao n, zeolite,
shale, Portland cement, Portland cement interground with pumice, perlite, barite, slag, lime
(e.g., hydrated lime), gypsum, and any combinations thereof, and the like. A person having
ordinary skill in the art, with the benefit of this disclosure, will .readily be able to determine
the t p and amount of additive useful for a particular application and desired result, it
should be understood that, while the present disclosure describes a number of optional
additives that may be included in the settable compositions, it is intended to cover all
combinations of the disclosed additi ves.
[0 ] The settable compositions ma b used in a variety of different applications
where it may be desired to form a seal in a subterranean formation, including plugging,
abandoning, lo st circulation, and fluid control, among others, n some embodiments, a
settable composition may be introduced into a we ore; a d allowed to form a n n f owa e
ge The settable composition may form the non-fiowable gel in a lost circulation zo e or
other location through which the flow of fluids a be desirably reduced or prevented. The
settable composition may comprise cement kiln dust, an alkali aluminate, an alkali silicate,
a nd an aqueous carrier fluid. The settable composition ma further comprise one or more
optional additives as described herein.
[0017] An embodiment may provide a settable composition comprising; cement kiln
dust, an alkali aluminate, an alkali silicate, and an aqueous carrier fluid.
[00 ] Another embodiment may provide a system comprising; a settable
composition comprising cement kiln dust, a alka li aluminate, an alkali silicate, and an
aqueous carrier fluid; and pumping equipment for introducing the settable composition into a
subterranean formation.
[00 1 ] Another embodiment may provide a method comprising cement kil dust, an
alkali aluminate, a alkali silicate, and an aqueous carrier fluid into a subterranean
formation; and allowing the settable composition to set and thereby reduce fluid f ow
through a portion of the subterranean formation,
[0020] Another embodiment may provide a method comprising: introducing a first
stream comprising an aqueous alkali aluminate and cemen kiln dust into lost circulation
zone in a subterranean formation; introducing a second stream comprising an aqueous alkali
silicate into the lost circulation zo e in the subterranean formation; forming a settable
composition upon intermixing of the first stream nd the second stream; and allowing the
settable composition to set in the lost circulation zone.
[0021] n some embodiments, the settable composition m set to form an
aluminosilicate gel. n particular embodiments, the sellable composition may form a nonowable
gel By inclusion of the cement kiln dus in the settable composition, the settable
composition may set into a hardened mass with reasonable compressive strength.
Furthermore, in embodiments, a minor portion of the settable composition may remain an
active free fluid in a fiowable liquid state even after ge formation. In some embodiments,
the settable composition ay be prepared by mixing the cement kiln dust into an aqueous
alkali aluminate to make a slurry and then introducing an aqueous alkali silicate to the slurry
to form the settable composition. In a particular embodiment, the ratio of aqueous alkali
aluminate to cement kiln dust to aqueous alkali silicate in the settable composition may b
about 2:1 :2 However, by adjusting the concentration of composition components, the
performance and behavior of the settable composition may be attenuated. By way of
example, the volume of gel and hardened material may increase with decreasing ratio of
a ky aluminate to alky! silicate. The volume of the active free fluid ay also decrease with
decreasing ratio of alkyl aluminate to alkyl silicate
[0022] embodiments, the settable composition may be characterized by exhibiting
an unconfmed uniaxial compressive strength of about SO psi or more. These values may be
achieved in 7 days or less. Some formulations may be designed so as to provide these
compressive strengths with 24 hours to 48 hours. Typical sample geometry and sizes for
measurement are similar to, but not limited to, those use for characterizing oil well cements:
2 inch cubes; or 2 inch diameter cylinders that are 4 inches in length; or 1 inch diameter
cylinders that are 2 inches in length; and other methods known to thos skilled in the art of
measuring "mechanical properties" of oil well cements. For example the compressive
strength ma be determined by crushing the samples in a compression-testing machine. The
compressive strength is calculated from the failure load divided by the cross-sectional area
resisting the load and is reported in units of pound-force per square inch (psi). Compressive
strengths may be determined in accordance with AP P IOB-2, Recommended Practice for
Testing Well Cements, First Edition, July 2005.
[0023] In embodiments, a minor portion of the settable composition may remain a
active free fluid in a fiowable liquid state even after non-flowable gel formation. For
example, the active free fluid may be present in the settable composition in an amount of
about 40% or less by volume o f the settabie composition, alternatively about 20% or less by
volume; alternatively about . % or ess by volume; am alternatively about 5% of ess by
volume.
[0024] As above, in an embodiment, the settabie compositions be
introduced into the wellbore to provide tost circulation control For example, the settabie
composition ay be used to prevent the loss of fluids (e.g., drilling fluids) into lost
circulation zones, which ay contain fractures (natural or pre-existing), cracks, vugs,
channels and other openings into which fluid may lost, n particular embodiments, the
settabie composition may be introduced into the wellbore as a single stream to form barrier
that substantially seals a lost circulation or other undesirable flowpath. For example, the
settabie composition may be placed downhoie through the drill bit. in another embodiment,
the settabie composition ma be formed downhoie by mixing a first stream comprising one
or more composition components and a second stream comprising additional composition
components, For example, the settabie composition may be formed downhoie by the mixing
of a rst aqueous stream comprising an alkali alummate and a second aqueous stream
comprising an alkali silicate. The cement kiln dust may be included in the first aqueous
stream, the second aqueous stream, or both the first and second aqueous streams
[0025] in an embodiment, the settabie composition may be introduced into the
wellbore, the subterranean formation, or a lost circulation zone as a single aqueous stream
That is, in such an embodiment, all components of the settabie composition may be mixed
and introduced into the wellbore as a single composition. As will be understood by those of
skill in the art with the aid of this disclosure, introduction as a single aqueous stream may be
an appropriate mode of introduction where the setting of a gel can be delayed, retarded, or
otherwise controlled such that the gel will not set until reaching a desired location. For
example, on or more of the reactive components (e.g., alkali alummate, -alkali silicate) may
be encapsulated when introduced into the wellbore to retard the gelation. The encapsulated
component may be released so to contact the other components of the settabie
composition in a downhoie portion of the wellbore near, proximate to, or within the lost
circulation zone When the components of the settabie composition ar allowed to contact,
the settabie composition may ge or begin to gel. Thus, by contacting the composition
components within (or near) the lost circulation zone, the ge may form within the los
circulation zone. By way of further example, one or more of the reactive components {e.g.,
alkali alummate, alkali sificaie) may be provided in a .solid fo rm so that reaction is delayed
until dissolution of the solid material in the aqueous carrier fluid.
[0026] In an alternative embodiment, the settable composition ma be introduced
into the weilbore, the formation, or the iost circulation zo in .multiple components. As will
b understood by those of ordinary skill in the art, may be desirable or advantageous to
introduce components of the sellable composition separately, for example, in situations
where the settable composition will gel withi a relatively short time-frame (e.g., those gels
which may set or begin to set within an amount of lime less than is necessary to introduce
the settable composition into the desired location) introducing two or ore of the
components of the settable composition separately allows the settable composition to be
positioned within the iost circulation zone prior to gelation. The separate introduction of at
least two of the composition components ay be achieved by various means, described in
greater detail herein below,
[0027] n some embodiments, the separate introduction of at least two of the
composition components may be achieved by introduction via two or more independent -fluid
streams. That is, a first component ma be introduced into the weilbore, formation, or lost
circ ulation zone via a first flowpath and a second component ma be introduced via a second
flowpath which is separate tram the first flowpath. The introduction of fluids into a weilbore
via two or more flowpaths is known to those of skill in the art, for example, via flow inside a
tubular and an annular spaced defined by the tubular and the weilbore (or a larger tubular)
introduction into the weilbore via two or more flowpaths may provide several advantages to
the operator. For example, the first component of the settable composition may be included
within a drilling fl uid wh ich is circulated through the weilbore during drilling operations. If a
lost circulation zone is encountered during drilling operations, a second component may be
introduced into the weilbore via a flowpath separate from the flowpath by which the drilling
fluid is circulated. Utilizing a ge!able composition which sets instantaneously or
substantially instantaneously causes gelation to occur where, or substantially near where, the
first component and the second component come into contact. Thus, utilizing multiple
flowpaths may allow the operator to plug or seal a los circulation zone without entirely
ceasing drilling operations.
[0028] In another embodiment, the separate introduction of at least two of th
composition components may be achieved by introducing the components within a single
flowpath,. but being separated by a spacer fluid. Such a spacer fluid may comprise a highly
viscous fluid which substantially or entirely prevents the intermingling of the composition
components while being pumped into a weilbore. Example spacer fluids and methods of
using th same are generally known to those of ordinary skill in the art. Once introduced to
the subterranean formation the settable composition ay enter the lost circulation zone and
set to form a mass that substantially inhibits or eliminates lost circulation.
[0029] n an embodiment, the method of combating lost circulation may comprise
introducing the sellable composition into a ost circulation zone or other undesirable
fiowpath. The settable composition may be an effective means o f combating lost circulation
i a lost circulation zone or other fiowpath. The settable composition may be introduced as a
single stream or multiple streams as described previously herein. Not seeking to be bound by
any particular theory, the components of the settable composition may work synergisticalSy
to combat lost circulation. For example, as the settable composition is introduced into the
ost circulation zone or fiowpath. the cement kiln dust may bridge some portion of the
cavities in the lost circulation zone or other fiowpath. Once introduced, at least a portion o f
the settable composition ma rapidly form a gel, n particular embodiments, the settable
composition may form a ringing gel Over time, the ge may set into a hardened mass with
reasonable compressive strength, A minor portion of the settable composition may remain an
active free fluid in a flowabie liquid state even after gel formation. This active free fluid may
permeate further into the lost circulation zone where it ay then harden to more effectively
control lost circulation.
[0030] Turning now to FIG. 1, an example operating environment for the methods
and compositions described herein is shown. It should be noted tha while F G. 1 generally
depicts a land-based operation, those skilled in the art wi l readily recognize that the
principles described herein are equally applicable to subsea. operations that employ floating
or sea-based platforms and rigs, without departing from the scope of the disclosure. As
illustrated, a drilling rig 0 may be positioned on the Earth's surface 2 and extends over
and around aw e l bore 104 that penetrates a subterranean formation 106. While the we bore
104 is shown extending generally vertically into the subterranean formation 6, the
principles described herein are also applicabie to we Shores that extend at an angle through
the subterranean formation 06, such as horizontal and slanted well bores. The wellbore 4
may be drilled into the subterranean formation 6 using any suitable drilling technique, in
an embodiment, the drilling rig 100 comprises a derrick 108 with a rig floor I SO throug
which a wor string 112 extends downward from the drilling rig 1.00 into the wellbore 104,
While not shown, the work string . may a deliver a wellbore servicing apparatus (e.g., a
drill bit) or some part thereof to a predetermined depth within the wellbore 104. In some
embodiment^ least a portion of the wellbore 1.0 may be lined with a casing that may
be secured into position in the wellbore 04 using cement , In alternative embodiments,
the wellbore 4 may be partially cased and ce e ted thereby resulting in a portion of the
wellbore 4 being openhole.
[0031] During any o e or more wellborn drilling, completion, or servicing
operations, a lost circulation zone may be encountered. Where the lost circulation zone
8 is encountered, it ay be desirable to employ a settable composition disclosed herein to
prevent, lessen, minimize, and/or cease the loss of fluids to the lost circulation zone
Placement of the settable composition into the lost circulation zone may be an effective
means of plugging or sealing o f the lost circulation zone 18 and thereby preventing,
ceasing, and/or substantially lessening th loss of fluids from the wellbore 104 to the lost
circulation zone . . , As previously described, in embodiments, the settable composition
may be placed into the ost circulation zone as a single strea or as two or more streams.
While the lost circulation zon 8 i shown as an opening that extends fr the wellbore
104 into the subterranean formation 106, it is contemplated that the tost circulation zone 1
may contain one or more features including without limitation fractures (natural or pre¬
existing), cracks, vugs, channels, openings, and/or the like. Moreover, while the lost
circulation zone s illustrated n an openhole section of the wellbore 04, i is
con templa ted that a lost circiila tio n zone may also occur in a section of the wel lbore 4 with
the casin ί 14.
[0032] Turning now to FIG. 2, the settable composition, which may comprise
cement kil dust, an alkali aluminate, an alkali silicate, and an aqueous carrier fluid, may be
placed into the lost circulation zone 8 in accordance with example embodiments, A first
stream 120 may be pumped down through the interior of the work string 112 through the
drill bit 122 on the work siring 12 and into th lost circulation zone 120. The first stream
0 may comprise one or more components of the settable composition. For example, the
firs stream .20 may comprise the alkali aluminate or th alkali silicate. Optionally, the first
stream 120 may further comprise the cement kiln dust. A second stream 24 may be pumped
down through an annulus 1 4 between the work string 1 and the casing 114 and into the
ost circiilation zone 8 . The second stream 4 may comprise one or more components of
the settable composition. For example, the second stream 124 may comprise the alkali
aluminate or the alkali silicate. Optionally, the first stream 124 may further comprise the
cement kiln dust Additional components of the settable composition may also be included in
the first and second streams 120, 24 as desired by on o ordinary skill in the art. As
illustrated by arrows 12 8 , the fi st and second stream 120, 1 4 may contact and intermix to
form the settable composition in the lost circulation zone 1 8 . The contact and intermixing
of the first and second streams 1 0, 124 may occur in a downh e portion of the wellbore
4 near, proximate to, or within the ost circulation zone 8. A least a portion of the
settabie composition may set i the ost circulation to for a hardened mass
thereby preventing, ceasing, and/or substantially lessening the oss of fluids from the
weilbore 104 to the lost circulation zone 8. As previously described, in embodiments a
minor portion of the settabie composition ma remain in an active fluid state even after gel
formation allowing greater penetration of th settabie composition into the lost circulation
zone .
[0033] Turning now to F G, 3, a system 130 is illustrated that may be used in
placement of a settabie composition or particular portion thereof into weilbore 18 in
accordance with certain embodiments. As shown, the settabie composition (or a portion
thereof) may be mixed in mixing equipment 32, such as a jet mixer, ^-circulating mixer, or
a batch mixer, for example, and then pumped via pumping equipment 134 t the weilbore
18. n some embodiments, the mixing equipment 32 and the pumping equipment 134 may
be disposed on one or more cement trucks will be apparent to those of ordinary skill in the
art. While not shown separately, in embodiments, the mixing equipment 32 may comprise
one or more of a circulating pump, a liquid additive system, a additive tank, and/or a
storage tank. While also not shown separately, the pumping equipment 134 ma comprise
o e or more pumps configured to separately introduce the settabie composition to the
weilbore 11 in tw or more different streams.
[0034] The exemplary settabie compositions disclosed herein may directly or
indirectly affect one or more components or pieces of equipment associated with the
preparation, delivery, recapture, recycling, reuse, and/or disposal of the disclosed settabie
compositions. For example, the settabie compositions may directly or indirectly affect one or
more mixers, related mixing equipment, mud pits, storage facilities or units, composition
separators, heat exchangers, sensors, gauges, pumps, compressors, and the like used
generate, store, monitor, regulate, and/or recondition the exemplary settabie compositions.
The disclosed settabie compositions may also directly or indirectly affect any transport or
delivery equipment used to conve the settabie compositions (or components thereof) to a
well site or downhole such as, for example, any transport vessels, conduits, pipelines, trucks,
tubulars, and/or pipes used to compositionally move the settabie compositions from one
location to another, any pumps, compressors, or motors (e.g., topside or downhole) used to
drive the settabie compositions into motion, any valves or related joints used to regulate the
pressure or flow rate of the settabie compositions, and any sensors (i.e., pressure and
temperature), gauges, and/or combinations thereof, and the like. The disclosed settabie
compositions may also directly or indirectly affect the various downhole equipment and
tools that may come nt contact with the sellable compositions such as, but not limited to,
weilbore casing, e l ore li er, completion string, insert strings, drill string, coiled tubing,
s iek ine, wireline, drill pipe, dri l l collars, mud motors, downhole motors and/or pumps,
cement pumps, surface-mounted motors and/or pumps, eentralizers, turbo zers scratchers,
floats (e.g., shoes, collars, valves, etc.), logging tools and related telemetry equipment,
actuators (e.g., electromechanical devices, yd mec anieal devices, etc.), sliding sleeves,
production sleeves, plugs, screens, filters, flow control devices (e.g., inflow control devices,
autonomous inflow control devices, outflow control devices, etc.), couplings (e.g., electrohydraulic
wet connect, dry connect, inductive coupler, etc.), control lines (e.g., electrical,
fiber optic, hydraulic, etc.). surveillance tines, drill bits and reamers, sensors or distributed
sensors, downhole eat exchangers, valves and corresponding actuation devices, tool seals,
packers, cement plugs, bridge plugs, a d other weilbore isolation devices, or components,
and the like.
[0035] To facilitate a . better understanding of the present embodiments, the
following examples of certain aspects of some embodiments are give in no way should the
following examples be read t limit, or define, the entire scope of the embodiments.
EXAMPLES
[0036] The following example was performed to demonstrate gelation a d
hardening of set a e compositions comprising cement kil dust, an aqueous sodiu
aluminate, and an aqueous sodium silicate. Thirteen different samples (designated Samples
1—3> were prepared using the indicated amounts of cement kiln dust, aqueous sodium
aluminate, and aqueous sodium silicate. An aqueous carrier fluid is not separately listed as
the aqueous sodium aluminate and aqueous sodium silicate were aqueous solutions of 38%
sodium aluminate by weight and 40% sodium silicate by weight, respectively. Samples 3, 6,
and 9 are comparative samples because no cement kiln dust was included. Sample 12 is a
comparative sample as it did not contain the sodium silicate. Sample 13 is a comparative
sample as it did not contain the sodium aluminate. The cement kiln dust used in this example
was obtained from Ho ei , inc. The aqueous sodium aluminate used in this example was
VersaSet thixotropic additive, available from Halliburton Energy Services, nc. The
aqueous sodium silicate used in this example was Liquid Econolite™ additive, available
f om Halliburton Energy Services.
[0037] The samples were mixed by first preparing the aqueous sodium aluminatecement
kiln dust slurry, followed by addition of the aqueous sodium silicate solution to th
slurry with stirring. For example, to 50 grams of aqueous sodium aluminate (38% by weight)
was added 25 grams of cemen kiln dust. The mixture was manually stirred with a spatula to
form a slurry. After, 50 grams of aqueous sodiura silicate soluiion (40% by vve g ) was
added to the slurry, and the mixture stirred manually with a spatula to form a or vab
gelatinous materia!. After preparation, the samples were eft undisturbed i their containers
to into a hardened mass. The compositions were analyzed for gelation and solidification
y visual observation. The amount of active free fl ui was determined by decanting the fluid
fro the bulk gelatinous product into a graduated cylinder.
0038] The results of this Example are summarised i the table below.
Table
Sample Aqueous Aqueous Cement Volume of Observations
S«xl i Sodium Kiln D st Active-
Ai i a Silicate (g) Free Fluid
(8 g (ml)
1 50 25 5 ab e ge! .formed immediately;
never fully solidified
2 50 2 5 10 0 able gel formed immediately; gel
remained in a abie state after 24 hours
3 50 25 0 3.2 s -fi o abie gel formed immediately;
never fully solidified
4 50 50 5 25 on- wabie gel .formed immediately;
complete solidification in less than 30
minutes
5 50 50 1 30 o -f !o ab e gel forraed immediately;
complete solidifi cat ion in less than 20
minutes
6 50 50 0 24 o -f o ab e gel formed immediately; o
solidification; free fluid remained after 48
hours
7 25 50 5 4.5 o ab e gel formed immediately;
solidification in less than 30
minutes
25 50 2,5 o r -f o abl gel forraed immediately;
complete solid i cation in less than 20
minutes
50 0 0 o -f vabie gel forraed immediately; no
solidification
10 O 50 25 24 N n o ab e gel formed immediately;
complete solidification in less than 20
minutes
1! 25 50 25 0 on-fio bie gel formed i mediatel ;
complete solidification in less than 3
inute
12 50 0 S va Formed viscous slurry tha was o able ;
on- o abie gel di not form for at least
48
o 50 5 n a j n x i vis slurry that ab ;
h ί · i ai J e i did ot fo for at least
1 4 $ hours
[0039] Samples 1 -3: t was found that the gel formed immediately. However, the
resulting compositions never folly solidified.
[0040] Samples 4-6: t was found that , when a mixture of aqueous sodium
aluminafe, cement k n dust a d aqueous Sodium silicate where mixed i a 10:1 ; f) ratio
(Sample 4), a non~ilowable gel formed immediately with the retention of an active tree fluid
surrounding the n n owab!e gel. This active free fluid within Jess than 30 minutes of
mixing also solidified and the entire mixture became a hardened mass, increasing the amount
o f cement kiln dust i Sample 5 such that the ratio o aqueous sodium aluminate, cement kin
dust and aqueous sodium silicate was 5:1 5, resulting in similar immediate non f ow b *gel
formation and amount of free .fluid retained; however, the setting time was reduced by 1/3
(fr o 30 minutes for Sample 4 to 20 minutes for Sample 5). Fo the control. (Sample 6), &
mixture of equal parts aqueous sodium aluminate and aqueous sodium silicate with no
cement kiln dust formed a non o ab e ge immediately upon mixing; however, the mixture
did not set into a hardened mass. Rather, it remained a non-flowable gel surrounded by the
active free f d.
[0041] Samples 7-9; Reducing the amount of aqueous sodium aluminate such that
the ratio of aqueous sodium aluminate, cement kin dust and aqueous sodium silicate was
5: :10 (Sample 7), resulted in compositions with similar behavior to that of Samples 4 and 5
except that muc less free fluid was retained (> 80% less fluid). This amount of free fluid
could be reduced by increasing the amount of cement kiln dust n the mixture by two-fold as
illustrated by Sample 8. Samples 7 and 8 both completely solidified into a hardened mass in
less than 30 minutes. For the control (Sample 9), a 1; mixtur of aqueous sodium aluminate
and aqueous -sodium silicate formed a non-fiowable ge upo mixing, with no free fluid, and
did not sent into a hardened mass.
[0042] Samples 10 and ; Increasing the amount of cement k n dust such that the
ratio of aqueous sodium aluminate, cement ki dust and aqueous sodium silicate was 2:1:2
(Sample ) again resulted in immediate gelaiio with a reasonable amount of free fluid.
This material set into a hardened mass i less than 20 minutes and a compressive strength of
greater than 30 psi was measured after 24 hours ( 0 cylinder crush). Compressive
strength was determined in accordance with API RP B-2, Recommended Practice .for
Testing Well Cements, First Edition, July 2005. As illustrated by Sample , a mixture with
a ! ;2 ratio of aqueous sodium aluminate, cement kin dust and aqueous sodium silicate also
produced a non o vable gel upon raking, but did not retain a ty free fluid. It did, however,
completely solidify i less than 30 minutes, ut had less compressive strength (crumbly
solid) than Sample . In a further example, the design of Sample 10 was prepared and upon
mixing the components, the free fluid was poured into a separate container. This free fluid
remained i a owable, liquid state for at least 30 minutes before setting into a solid mass,
thus illustrated that it is an active free fluid,
0043 Samples 12 and 13: n order to determine whether the observations could
occur with the .combination of only two active components or required all three active
components, comparative Samples 12 and 1 were prepared. It was shown that either a
.mixture of aqueous sodium alurmnate and cement kiln dust (Sample 12 or a mixture of
aqueous sodium silicate and cement kiln dust (Sample 13), both in a 10 1 ratio, formed a
viscous slurry but did not form a o -flowabl gel nor set nto a hardened mass for at least
48 hours.
[0044] For the sake of brevity, only certain ranges are explicitly disclosed herein,
However, ranges m any lower limit may be combined with any upper limit to recite a
range not explicitly recited, as well as, range from any lower limit may e combined with
any other ower limit to recite a range not explicitly recited, in the same way, ranges from
a y upper limit may be combined with any other upper limi to recite a range not explicitly
recited. Additionally, whenever a .numerical range with a lower limit and an upper limit is
disclosed, any number and any included range falling within the range are specifically
disclosed, n particular, every range of values (of the form, "from about a to about b," or,
equivaiently, "from approximately a to b, or, equivalent!}', " approximately a-b")
disclosed herein is to be understood to set forth every number and range encompassed within
the broader range of values even 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.
[0045] Therefore, the example embodiments are well adapted to attain the ends and
advantages mentioned as well as those that are inherent therein. Th particular embodiments
disclosed above are illustrative only, as the disclosed embodiments may be modified and
practiced in different hut 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 meanin unless
otherwise explicitly and clearly defined by the patentee, it is therefore evident that the
particular illustrative embodiments disclosed above ay be altered or modified and a l such
variations are considered within the scope and spirit of the present invention. If there is any
conflict in the usages of a word or term in this specification and one or ore patent(s) or
other documents that ay be incorporated herein by .reference, the definitions that are
consistent with this specification should be adopted.

What is claimed is:
. A method comprising:
introducing a seitable composition comprising cement kiln dust, an alkali
aSitnnnate. an alkali silicate, and an aqueous carrier fluid into a subterranean formation; and
allowing the sellable composition to set a d thereby reduce fluid flow
through a portion of the subterranean formation.
2 . The method of claim wherein the introducing the settabie composition
comprises introducing the settabie composition into the subterranean formation as two or
more different streams.
3 . The method of claim 1. wherein the introducing the settabie compos ition
comprises introducing the settabie composition into the subterranean formation as a single
stream.
4 . The method of claim 1, wherein portion of the settabie composition sets to
form a non owa le gel while a minor portion of th settabie composition remains an active
free fluid in a flowable liquid state, the active free fluid penetrating further into the portion of
the subterranean formation.
5. The method of claim 1, wherein the settabie composition sets i the portion
of the subterranean formation to or a hardened mass.
6 . The method of claim ! wherein at least a portion of the settabie composition
sets to form a non-flowable gel and then further sets to form a hardened mass.
7. The method of claim 1, wherein the cement kiln ust Is present in the settabie
composition in an amount of about 1% to about 25% by weight of the settabie composition,
wherein the alkali aluminate is present in the settabie composition in a amount of about 1%
to about 40% by weight of the settabie composition, and wherein the alkali silicate is present
i the settabie composition in an amount of about % to about 40% by weight of the settabie
composition .
8. The method of clai , wherein the cement kiln dust is present in the settabie
composi tio n in an amount of about 5% to about 25% by weight of the settabie composition,
wherein the alkali aluminate is present in the settabie composition in an amount of about 5%
to about 30% by weight of the settabie composition, and wherein the alkali silicate is present
in the seitable composition in an amount of about 5% to about 30% by weight of the settabi
composition,
9. The method of claim 1, wherein the alkali aluminate comprises sodium
aluminate, and wherein the alkali silicate comprises sodium silicate.
10. The method of claim wherein a least one of the alkali ahmiinate or the
alkali silicate re encapsulated.
11. A method co ri ng
introducing a first stream comprising an aqueous alkali alu a and cement
k ln dust i to a !ost circulation zo e in a subterranean formation;
introducing a second stream comprising an aqueous alkali silicate into the
lost circulation zone in the subterranean formation;
forming a settabie composition pon intermixing of the first stream and the
second stream; and
allowing the settabie composition to set in the lo st circulation zone.
12. The method of claim 11, wherein first stream and the second stream are
separated by a spacer fl u id ..
1 . The method claim J. , wherein one of the first stream or the second stream
s introduced through a work string while the other one of the first stream or the second
stream s introduced through an ann us formed between the work string and th
subterranean formation or a larger conduit,
14. The method of claim , wherein a portion of the settabie composition sets to
form a non-flowable gel while a minor portion of the settabie composition remains an active
free fluid in a flowabSe liquid state, the active free fluid penetrating further into th lost
circulation zone.
. The method of claim , wherein the settabie composition sets the portion
of the subterranean formation to form a hardened mass.
16. The method of claim 1 , wherein at least a portion of the settabie
composition sets to form a non- f o ab e gei and then further sets to form a hardened mass.
1 . The method of claim 11, wherein the cement kiln dust is present in the
settabie composition in an amount of about % to about 25% by weight of the settabie
composition, wherein the alkali aiuminate is present in the settabie composition i an amount
of about % to about 40% by weight of the settabie composition, and wherein the alkali
silicate is present in the settabie composition in an amount o about % to about 40% by
weight of the settabie composition.
18. The method o claim 11, wherein the cement kiln dust is present in the
settabie composition in an amount of about 5% to about 25% by weight of the settabie
composition, wherein the a kali aiuminate is present in. th setiable composition in an amount
of about 5% to about 30% by weight of the settabie composition, and wherein the alkali
silicate is present in the settable composition in an amount of about 5% to about 3 % by
weight of the sellable composition.
19. The method of claim , wherein the alkali aluminate comprises sodium
aluminate. and wherein the alkali silicate comprises sodium silicate.
5 20. A settable composition comprising;
cement k n dust,
an alkali aluminate,
an alkali silicate, a d
an aqueous carrier fluid.
1 . The settable composition of claim 20, wherein the cement kiln dust is present
in the settable composition i an amount of about 1% to about 25% by weight of the settable
composition
22. The settable composition of claim 20, wherem the alkali aluminate is present
n the settable composition in an amount of about 1% to about 40% by weight of the settable
composition,
23. The settab!e composition of claim 2 , wherein the alkali silicate is present in
t e settable composition i an amount of about 1% to about 40% by weight of the settable
composition.
24. The settable composition of claim 20 wherein the cement kiln dust is present
0 in the settable composition i an amount of about 5% to about 25% by weight of the settable
composition, wherein the alkali aluminate is present in the settable composition in an amount
of about 5% to about 30% by weight of the settable composition, and wherein the alkali
silicate is present in the settable composition in an amount of about 5% to about 30% by
weight of the settable composition.
5 25. The settable composition of claim 20, wherein the alkali aluminate comprises
sodium aluminate, and wherein the alkali silicate comprises sodium silicate.
26. A system comprising:
a settable composition comprising cement kiln dust, an alkali aluminate, an alkali
silicate, and an aqueous carrier fluid; and
0 pumping equipment for introducing the settable composition into a subterranean
formation.
27. The system of clai 26. further comprising a work string, the pumping
equipment being configured to introduce at least a portion of the settable composition into
the subterranean formation through the work string.
5 28. The system of claim 27, wherein a drill bit is disposed on the work string,
29. The system of claim 26, wherein the pumping equipment comprises one or
more pumps configured to separately introduce the sellable composition into the
subterranean formation its two or more different streams.
30. The system o claim 26, wherein the cement ki dust is present i the
sellable composition in an amount of about 5% to about 25% by weight o the settab!e
composition, wherein the alkali aiuminate is present in the setiabSe composition in an amount
of about 5% to about 30% by weight of the suitable composition, and wherein the alkali
silicate is present n the settable composition in an amount of about 5% to about 30% by
weight of the settabfe composition.
3 1. The system of claim 26, wherein the alkali aiuminate comprises sodium
aiuminate, and wherein the alkali silicate comprises sodium silicate.