CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from a continuation-in-part of U.S.
Application No. 12/264,010, entitled "Reduced Carbon Footprint Sealing Compositions for
Use in Subterranean Formations," filed on November 3, 2008, which is a continuation-in-part
of U.S. Application No. 11/223,669, now U.S. Patent No. 7,445,669, entitled "Settable
Compositions Comprising Cement Kiln Dust and Additive(s)," filed September 9, 2005, the
entire disclosures of which are incorporated herein by reference.
BACKGROUND
[0002] The present invention relates to subterranean operations and, more
particularly, in certain embodiments, to spacer fluids comprising cement kiln dust ("CKD")
and methods of use in subterranean formations.
[0003] Spacer fluids are often used in subterranean operations to facilitate improved
displacement efficiency when introducing new fluids into a well 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.
[0004] 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. In some
instances, it is also desirable for the spacer fluid to leave surfaces in 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 may not provide the desired displacement in some
instances.
SUMMARY
[0005] The present invention relates to subterranean operations and, more
particularly, in certain embodiments, to spacer fluids comprising CKD and methods of use in
subterranean formations.
[0006] According to one aspect of the invention there is provided a method
comprising: providing a spacer fluid comprising CKD and water; introducing the spacer
fluid into a well bore to displace at least a portion of a first fluid from the well bore, wherein
the spacer fluid has a yield point at 80° F [27°C] that is higher than a yield point of the first
fluid at 80° F [27°C].
[0007] According to another aspect of the invention there is provided a method
comprising: providing a spacer fluid comprising CKD and water; and introducing the spacer
fluid into a well bore, wherein the spacer fluid has a higher yield point at bottom hole static
temperature of the well bore than at 80° F [27°C].
[0008] According to another aspect of the invention there is provided a method
comprising: providing a spacer fluid comprising CKD and water; and introducing the spacer
fluid into a well bore, wherein the spacer fluid has a higher yield point at 130° F [54°C] than
at 80° F [27°C].
[0009] According to another aspect of the invention there is provided a method
comprising: providing a spacer fluid comprising CKD and water; and introducing the spacer
fluid into a well bore, wherein the spacer fluid has a higher plastic viscosity at 180° F [82°C]
than at 80° F [27°C].
[0010] According to another aspect of the invention there is provided a method
comprising: providing a spacer fluid comprising CKD and water; and introducing the spacer
fluid into a well bore, wherein the spacer fluid has:
(a) a higher yield point at bottom hole static temperature of the well bore than at 80°
F [27°C],
(b) a higher yield point at 130° F [54°C] than at 80° F [27°C], and/or
(c) a higher plastic viscosity at 180° F [82°C] than at 80° F [27°C],
[00 11] In an embodiment, the spacer fluid has:
(a) a higher yield point at bottom hole static temperature of the well bore
than at 80° F [27°C], or
(b) a higher yield point at 130° F [54°C] than at 80° F [27°C], or
(c) a higher plastic viscosity at 180° F [82°C] than at 80° F [27°C].
[0012] In an embodiment, the spacer fluid has:
(a) a higher yield point at bottom hole static temperature of the well bore
than at 80° F [27°C], and
(b) a higher yield point at 130° F [54°C] than at 80° F [27°C], and
(c) a higher plastic viscosity at 180° F [82°C] than at 80° F [27°C].
[00 13] In an embodiment, the spacer fluid has:
(a) a higher yield point at bottom hole static temperature of the well bore
than at 80° F [27°C], and
(b) a higher yield point at 130° F [54°C] than at 80° F [27°C].
[00 14] In an embodiment, the spacer fluid has:
(a) a higher yield point at bottom hole static temperature of the well bore
than at 80° F [27°C], and
(b) a higher plastic viscosity at 180° F [82°C] than at 80° F [27°C].
[0015] In an embodiment, the spacer fluid has:
(a) a higher yield point at 130° F [54°C] than at 80° F [27°C], and
(b) a higher plastic viscosity at 180° F [82°C] than at 80° F [27°C].
[0016] According to another aspect of the invention there is provided a spacer fluid
comprising C D and water, wherein the spacer fluid has:
(a) a higher yield point at 130°F [54°C] than at 80° F [27°C],
(b) a higher yield point at 180° F [82°C] than at 80° F [27°C], and/or
(c) a higher plastic viscosity at 180°F [82°C] than at 80° F [27°C].
[0017] In an embodiment, the spacer fluid has:
(a) a higher yield point at 130°F [54°C] than at 80° F [27°-C], or
(b) a higher yield point at 180° F [82°C] than at 80° F [27°C], or
(c) a higher plastic viscosity at 180°F [82°C] than at 80° F [27°C].
[0018] In an embodiment, the spacer fluid has:
(a) a higher yield point at 130°F [54°C] than at 80° F [27°C], and
(b) a higher yield point at 180° F [82°C] than at 80° F [27°C], and
(c) a higher plastic viscosity at 180°F [82°C] than at 80° F [27°C].
[0019] In an embodiment, the spacer fluid has:
(a) a higher yield point at 130°F [54°C] than at 80° F [27°C], and
(b) a higher yield point at 180° F [82°C] than at 80° F [27°C].
[0020] In an embodiment, the spacer fluid has:
(a) a higher yield point at 130°F [54°C] than at 80° F [27°C], and
(b) a higher plastic viscosity at 180°F [82°C] than at 80° F [27°C].
[0021] In an embodiment, the spacer fluid has:
(a) a higher yield point at 180° F [82°C] than at 80° F [27°C], and
(b) a higher plastic viscosity at 180°F [82°C] than at 80° F [27°C].
[0022] The features and advantages of the present invention will be readily apparent
to those skilled in the art. While numerous changes may be made by those skilled in the art,
such changes are within the scope of the invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0023] The present invention relates to spacer fluid compositions comprising CKD,
methods of use in subterranean formations and, more particularly, in certain embodiments, to
compositions and methods that use CKD for enhancing one or more rheological properties of
a spacer fluid. There may be several potential advantages to the methods and compositions
of the present invention, only some 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 rheological 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 CKD may be more economical than
conventional spacer fluids, which are commonly prepared with higher cost additives.
[0024] Embodiments of the spacer fluids of the present invention may comprise water
and CKD. In accordance with present embodiments, the spacer fluid may be used to displace
a first fluid from a well bore with the spacer fluid having a higher yield point than the first
fluid. For example, the spacer fluid may 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 viscosifying agents, organic polymers, dispersants, surfactants, weighting
agents, and any combination thereof.
[0025] The spacer fluids generally should have a density suitable for a particular
application as desired by those of ordinary skill in the art, with the benefit of this disclosure.
In some embodiments, the spacer fluids may have a density in the range of about 8 pounds
per gallon ("ppg") [about 960 kilogram/m 3] to about 24 ppg [about 2880 kilogram/m3] . In
other embodiments, the spacer fluids may have a density in the range of about 8 ppg [about
960 kilogram/m3] to about 14 ppg [about 1680 kilogram/m3]. In yet other embodiments, the
spacer fluids may have a density in the range of about 10 ppg [about 1200 kilogram/m3] to
about 12 ppg [about 1440 kilogram/m 3].
[0026] The water used in 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 that may undesirably affect other components in the
spacer fluid. The water is included in an amount sufficient to form a pumpable spacer fluid.
In some embodiments, the water may be included in the spacer fluids in an amount in the
range of about 15% to about 95% by weight of the spacer fluid. In other embodiments, the
water may be included in the spacer fluids of the present invention in an amount of about
25% to about 85% by weight of the spacer fluid. One of ordinary skill in the art, with the
benefit of this disclosure, will recognize the appropriate amount of water to include for a
chosen application.
[0027] The CKD may be included in embodiments of the spacer fluids as a rheology
modifier. Among other things, it has been discovered that using CKD in embodiments of the
present invention can provide spacer fluids having rheology suitable for a particular
application. Desirable rheology may be advantageous to provide a 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 downhole.
[0028] CKD is a material generated during the manufacture of cement that is
commonly referred to as cement kiln dust. The term "CKD" is used herein to mean cement
kiln 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 a e
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 additives. The chemical analysis of CKD from various cement
manufactures varies depending on a number of factors, including the particular kiln feed, the
efficiencies of the cement production operation, and the associated dust collection systems.
CKD generally may comprise a variety of oxides, such as Si0 2, A 120 , Fe 0 3, CaO, MgO,
S0 3, Na20 , and K20 .
[0029] The CKD may be included in the spacer fluids in an amount sufficient to
provide, for example, the desired Theological properties. In some embodiments, the CKD
may be present in the spacer fluids in an amount in the range of about 1% to about 65% by
weight of the spacer fluid (e.g., about 5%, about 10%, about 15%, about 20%, about 25%,
about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, etc.). In
some embodiments, the CKD may be present in the spacer fluids in an amount in the range of
about 5% to about 60% by weight of the spacer fluid. In some embodiments, the CKD may
be present in an amount in the range of about 20% to about 35% by weight of the spacer
fluid. 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.
[0030] Optionally, embodiments of the spacer fluids may further comprise fly ash. A
variety of fly ashes may be suitable, including fly ash classified as Class C or Class F fly ash
according to American Petroleum Institute, API Specification for Materials and Testing for
Well Cements, API Specification 10, Fifth Ed., July 1, 1990. Suitable examples of fly ash
include, but are not limited to, POZMIX® A cement additive, commercially available from
Halliburton Energy Services, Inc., Duncan, Oklahoma. Where used, the fly ash generally
may be included in the spacer fluids in an amount desired for a particular application. In
some embodiments, the fly ash may be present in the spacer fluids in an amount in the range
of about 1% to about 60% by weight of the spacer fluid (e.g., about 5%, about 10%, about
15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%,
about 55%, etc.). In some embodiments, the fly ash may be present in the spacer fluids in an
amount in the range of about 1% to about 35% by weight of the spacer fluid. In some
embodiments, the fly ash may be present in the spacer fluids in an amount in the range of
about 1% to about 10% by weight of the spacer fluid. One of ordinary skill in the art, with
the benefit of this disclosure, will recognize the appropriate amount of the fly ash to include
for a chosen application.
[0031] Optionally, embodiments of the spacer fluids may further comprise a free
water control additive. As used herein, the term "free water control additive" refers to an
additive included in a liquid for, among other things, reducing (or preventing) the presence of
free water in the liquid. Examples of suitable free water control additives include, but are not
limited to, bentonite, amorphous silica, hydroxyethyl cellulose, and combinations thereof.
Where used, the free water control additive may be present in an amount in the range of about
0.1% to about 16% by weight of the spacer fluid, for example.
[0032] A wide variety of additional additives may be included in the spacer fluids as
deemed appropriate by one skilled in the art, with the benefit of this disclosure. Examples of
such additives include, but are not limited to, weighting agents, viscosifying 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, with the benefit of this disclosure, will readily be able to
determine the type and amount of additive useful for a particular application and desired
result.
[0033] An example method of the present invention includes a method of enhancing
rheological 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 180°F [about 82°C] is greater than about 5 lb/100 ft2 [about 2 Pa] . In an
embodiment, the yield point of the spacer fluid at a temperature of up to about 180°F [about
82°C] is greater than about 10 lb/100 ft2 [about 5 Pa]. In an embodiment, the yield point of
the spacer fluid at a temperature of up to about 180°F [about 82°C] is greater than about 20
lb/100 ft2 [about 10 Pa]. It may be desirable for the spacer fluid to not 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 180° F [82°C]
or bottom hole static temperature ("BHST"). In one embodiment, the spacer fluid may have
a yield point that increases at elevated temperatures. For example, the spacer fluid may have
a yield point that is higher at 180° F [82°C] than at 80° F [27°C]. By way of further example.
The spacer fluid may have a yield point that is higher at BHST than at 80° F [27°C].
[0034] Another example method of the present invention includes a method of
displacing a first fluid from a well bore, the well bore penetrating a subterranean formation.
The method may comprise providing a spacer fluid that comprises CKD 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. In some embodiments, the spacer fluid
may be characterized by having a higher yield point than the first fluid at 80°F [27°C]. In
some embodiments, the spacer fluid may be characterized by having a higher yield point than
the first fluid at 130°F [54°C]. In some embodiments, the spacer fluid may be characterized
by having a higher yield point than the first fluid at 180°F [82°C]
[0035] In 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. The drilling fluid may include, for example, any number of fluids, such
as solid suspensions, mixtures, and emulsions. Additional steps in embodiments of the
method may comprise introducing a pipe string into the well bore, introducing a cement
composition into the well bore with the spacer fluid separating the cement composition and
the first fluid. In an embodiment, the cement composition may be allowed to set in the well
bore. The cement composition may include, for example, cement and water.
[0036] 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 having a
first fluid disposed therein. The spacer fluid may 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 fluid. In 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. In an embodiment, the cement composition comprises cement kiln dust, water, and
optionally a hydraulic cementitious material. A variety of hydraulic cements may be utilized
in accordance with the present invention, including, but not limited to, those comprising
calcium, aluminum, silicon, oxygen, iron, and/or sulfur, which set and harden by reaction
with water. Suitable hydraulic cements include, but are not limited to, Portland cements,
pozzolana cements, gypsum cements, high alumina content cements, slag cements, silica
cements, and combinations thereof. In certain embodiments, the hydraulic cement may
comprise a Portland cement. In some embodiments, the Portland cements that are suited for
use in the present invention are classified as Classes A, C, H, and G cements according to
American Petroleum Institute, API Specification for Materials and Testing for Well Cements,
API Specification 10, Fifth Ed., Jul. 1, 1990. The spacer fluid may also remove the drilling
fluid, dehydrated/gelled drilling fluid, and/or filter cake solids from the well bore in advance
of the cement composition. Removal of these compositions from the well bore may enhance
bonding of the cement composition to surfaces in the well bore. In an additional
embodiment, at least a 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.
[0037] To facilitate a better understanding of the present invention, the
following examples of certain aspects of some embodiments are given. In no way should
the following examples be read to limit, or define, the scope of the invention. In the
following examples, concentrations are given in weight percent of the overall
composition.
EXAMPLE 1
[0038] Sample spacer fluids were prepared to evaluate the rheological properties of
spacer fluids containing CKD. The sample spacer fluids were prepared as follows. First, all
dry components (e.g., CKD, fly ash, bentonite, FWCA, etc.) were 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
rpm stirring. The blender speed was then increased to 12,000 rpm for about 35 seconds.
[0039] Sample Spacer Fluid No. 1 was an 11 pound per gallon [1320 kilogram/m 3]
slurry that comprised 60.62% water, 34.17% CKD, 4.63% fly ash, and 0.58% free water
control additive (WG-17™ solid additive).
[0040] Sample Spacer Fluid No. 2 was an 1 pound per gallon [1320 kilogram/m 3]
slurry that comprised 60.79% water, 30.42% CKD, 4.13% fly ash, 0.17% free water control
additive (WG-17™ solid additive), 3.45% bentonite, and 1.04% Econolite™ additive.
[0041] Rheological values were then determined using a Far Model 35 Viscometer.
Dial readings were recorded at speeds of 3, 6, 100, 200, and 300 with a Bl bob, an Rl rotor,
and a 1.0 spring. The dial readings, plastic viscosity, and yield points for the spacer fluids
were measured in accordance with API Recommended Practices 10B, Bingham plastic model
and are set forth in the table below. The abbreviation "PV" refers to plastic viscosity, while
the abbreviation "YP" refers to yield point.
TABLE 1
[0042] The thickening time of the Sample Spacer Fluid No. 1 was also determined in
accordance with API Recommended Practice 10B at 205° F [96.1° C]. Sample Spacer Fluid
No. 1 had a thickening time of more than 6:00+ hours at 35 Be [Bearden units of
consistency].
[0043] Accordingly, the above example illustrates that the addition of CKD to a
spacer fluid may provide suitable properties for use in 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
yield point that increases with temperature. For example, Sample Spacer Fluid No. 2 had a
higher yield point at 180° F [82° C] than at 80° F [27° C]. In addition, the yield point of
Sample Spacer Fluid No. 1 had only a slight decrease at 180° F [82° C] as compared to 80° F
[27 °C]. Even further, the example illustrates that addition of CKD to a spacer fluid may
provide a plastic viscosity that increases with temperature.
EXAMPLE 2
[0044] Additional sample spacer fluids were prepared to further evaluate the
rheological properties of spacer fluids containing CKD. The sample spacer fluids were
prepared as follows. First, all dry components (e.g., CKD, fly ash) were 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
rpm stirring. The blender speed was then increased to 12,000 rpm for about 35 seconds.
[0045] Sample Fluid No. 3 was a 12.5 pound per gallon [1498 kilogram/m 3] fluid that
comprised 47.29% water and 52.71% CKD.
[0046] Sample Fluid No. 4 was a 12.5 pound per gallon [1498 kilogram/m 3] fluid that
comprised 46.47% water, 40.15% CKD, and 13.38% fly ash.
[0047] Sample Fluid No. 5 was a 12.5 pound per gallon [1498 kilogram/m 3] fluid that
comprised 45.62% water, 27.19% CKD, and 27.19% fly ash.
[0048] Sample Fluid No. 6 was a 12.5 pound per gallon [1498 kilogram/m 3] fluid that
comprised 44.75% water, 13.8 1% CKD, and 41.44% fly ash.
[0049] Sample Fluid No. 7 (comparative) was a 12.5 pound per gallon [1498
kilogram/m 3] fluid that comprised 43.85% water, and 56.15% fly ash.
[0050] Rheological values were then determined using a Fann Model 35 Viscometer.
Dial readings were recorded at speeds of 3, 6, 30, 60, 100, 200, 300, and 600 with a Bl bob,
an Rl rotor, and a 1.0 spring. The dial readings, plastic viscosity, and yield points for the
spacer fluids were measured in accordance with API Recommended Practices 10B, Bingham
plastic model and are set forth in the table below. The abbreviation "PV" refers to plastic
viscosity, while the abbreviation "YP" refers to yield point.
TABLE 2
Viscometer RPM YP
C DSample
Temp. PV (lb/
F y
Spacer ( p (cP) 100
Ash 600 300 200 100 60 30 6 3
Fluid [° C] [Pa-s] ft2)
Ratio
[Pa]
80 12 11
33 23 20 15 13 12 8 6
[27] [0.012] [5.27]
130 12 19
3 100:0 39 3 1 27 23 22 19 16 11
[54] [0.012] [9.1]
180 16.5 41.5
66 58 5 1 47 40 38 2 1 18
[82] [0.0165] [19.9]
80 10.5 11.5
28 22 19 15 14 11 8 6
[27] [0.0105] [5.51]
130 10.5 17.5
4 75:25 39 28 25 2 1 19 16 14 11
[54] [0.0105] [8.38]
180 6 33
5 1 39 36 35 3 1 26 16 11
[82] [0.006] [15.8]
80 7.5 3.5
20 11 8 6 5 4 4 3
[27] [0.0075] [1.68]
130 7.5 7.5
5 50:50 2 1 15 13 10 9 8 6 5
[54] [0.0075] [3.59]
180 9 1 1
25 20 17 14 13 12 7 5
[82] [0.009] [5.27]
80 7.5 0.5
16 8 6 3 2 1 0 0
[27] [0.0075] [0.239]
130 6 2
6 25:75 15 8 6 4 3 2 1 1
[54] [0.006] [0.958]
180 6 3
15 9 7 5 4 4 2 2
[82] [0.006] [1.44]
80 6 1
16 7 5 3 1 0 0 0
[27] [0.006] [0.479]
7 130 4.5 -0.5 [-
0:100 11 4 3 1 0 0 0 0
(Comp.) [54] [0.0045] 0.239]
180 4.5 -1.5 [-
8 3 2 0 0 0 0 0
[82] [0.0045] 0.718]
[0051] Accordingly, the above example illustrates that the addition of CKD to a
spacer fluid may provide suitable properties for use in 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
yield point that increases with temperature. In addition, as illustrated in Table 2 above,
higher yield points were observed for spacer fluids with higher concentrations of CKD.
EXAMPLE 3
[0052] A sample spacer fluid containing CKD was prepared to compare the
rheological 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,
bentonite, etc.) were 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 rpm stirring. The blender speed was then
increased to 12,000 rpm for about 35 seconds.
[0053] Sample Spacer Fluid No. 8 was an 11 pound per gallon [1320 kilogram/m 3]
slurry that comprised 60.79% water, 30.42% CKD, 4.13% fly ash, 0.17% free water control
additive (WG-17™ solid additive), 3.45% bentonite, and 1.04% Econolite™ additive.
[0054] The oil-based drilling fluid was a 9.1 pound per gallon [1090 kilogram/m 3]oilbased
mud.
[0055] Rheological values were then determined using a Farm Model 35 Viscometer.
Dial readings were recorded at speeds of 3, 6, 100, 200, and 300 with a Bl bob, an Rl 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 API Recommended Practices 10B, Bingham
plastic model and are set forth in the table below. The abbreviation "PV" refers to plastic
viscosity, while the abbreviation "YP" refers to yield point. The abbreviation "OBM" refers
to oil-based mud.
TABLE 3
[0056] Accordingly, the above example illustrates that the addition of CKD to a
spacer fluid may provide suitable properties for use in subterranean applications. In
particular, the above example illustrates, inter alia, that CKD may be used to provide a spacer
fluid with a yield point that is greater than a drilling fluid even at elevated temperatures. For
example, Sample Spacer Fluid No. 8 has a higher yield point at 180° F [82 C] than the oilbased
mud.
[0057] Therefore, the present invention is well 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 all 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 that the particular illustrative embodiments disclosed above
may be altered or modified and all such variations are considered within the scope of the
present invention. While compositions and methods are described in terms of "comprising,"
"containing," or "including" various components or steps, the compositions and methods can
also "consist essentially of or "consist of the various components and steps. Whenever a
numerical range with a lower limit and an upper limit is disclosed, any number and any
included range falling within the range is specifically disclosed. In particular, every range of
values (of the form, "from about a to about b," or, equivalently, "from approximately a to b,"
or, equivalently, "from approximately a-b") disclosed herein is to be understood to set forth
every number and range encompassed within the broader range of values. Also, the terms in
the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined
by the patentee.

CLAIMS
1. A method comprising:
providing a spacer fluid comprising cement kiln dust and water; and
introducing the spacer fluid into a well bore to displace at least a portion of a
first fluid from the well bore,
wherein the spacer fluid has a yield point at 80° F [27°C] that is higher than a
yield point of the first fluid at 80° F [27°C].
2. A method according to claim 1, wherein the spacer fluid comprises the cement kiln
dust in an amount of about 20% to about 35% by weight of the spacer fluid, and wherein the
spacer fluid further comprises fly ash in an amount of about 1% to about 10% by weight of
the spacer fluid.
3. A method according to claim 1, wherein the spacer fluid has a yield point at 180 °F
[82 ° C] that is higher than a yield point of the first fluid at 180°F [82 ° C].
4. A method according to claim 1,wherein the yield point of the spacer fluid at 180°F
[82 ° C] is greater than about 20 lb/100 ft2 [about 10 Pa].
5. A method comprising:
providing a spacer fluid comprising cement kiln dust and water; and
introducing the spacer fluid into a well bore,
wherein the spacer fluid has a higher yield point at bottom hole static
temperature of the well bore than at 80° F [27°C].
6. A method according to claim 1 or claim 5, wherein the cement kiln dust is present in
the spacer fluid in an amount of about 1% to about 60% by weight of the spacer fluid.
7. A method according to claim 1 or claim 5, wherein the spacer fluid further comprises
fly ash.
8. A method according to claim 1 or claim 5, wherein the spacer fluid further comprises
at least one additive selected from the group consisting of a free water control additive, a
weighting agent, a viscosifying agent, a fluid loss control additive, a lost circulation material,
a filtration control additive, a dispersant, a defoamer, a corrosion inhibitor, a scale inhibitor, a
formation conditioning agent, and any combination thereof.
9. A method according to claim 1 or claim 5, wherein the spacer fluid further comprises
at least one additive selected from the group consisting of a clay, a hydratable polymer, guar
gum, an organic polymer, a surfactant, crystalline silica, amorphous silica, fumed silica, a
salt, a fiber, hydratable clay, a microsphere, rice husk ash, any combination thereof.
10. A method comprising:
providing a spacer fluid comprising cement kiln dust and water; and
introducing the spacer fluid into a well bore,
wherein the spacer fluid has a higher yield point at 130° F [54°C] than at 80° F
[27°C].
11. A method comprising:
providing a spacer fluid comprising cement kiln dust and water; and
introducing the spacer fluid into a well bore,
wherein the spacer fluid has a higher plastic viscosity at 180° F [82 C] than
at 80° F [27°C].
12. A method according to claim 10 or claim , wherein the spacer fluid has a higher
yield point at 180° F [82 C] than at 80° F [27°C].
13. A method according to of claim 5, claim 10 or claim 11, wherein the step of
introducing the spacer fluid into the well bore displaces at least a portion of a first fluid from
the well bore.
14. A method according to 1 or claim 13, wherein the first fluid comprises a drilling fluid.
15. A method according to claim 1 or claim 14, further comprising introducing a cement
composition into the well bore to displace at least a portion of the spacer fluid from the well
bore, wherein the spacer fluid separates the cement composition from the drilling fluid.
16. The method of claim 1, claim 5, claim 10 or claim 11, further comprising introducing
a cement composition into the well bore to displace at least a portion of the spacer fluid from
the well bore, wherein the cement composition comprises cement kiln dust.
17. A spacer fluid comprising:
cement kiln dust; and
water,
wherein the spacer fluid has:
(a) a higher yield point at 130°F [54°C] than at 80° F [27°C],
(b) a higher yield point at 180° F [82 ° C] than at 80° F [27°C], and/or
(c) a higher plastic viscosity at 180°F [82 C] than at 80° F [27°C].