Note: Descriptions are shown in the official language in which they were submitted.
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FOAMING OF SET-DELAYED CEMENT COMPOSITIONS COMPRISING
PUMICE AND HYDRATED LIME
BACKGROUND
[00011 Cement compositions may be used in a variety of subterranean
operations.
For example, in subterranean well construction, a pipe string (e.g, casing,
liners, expandable
tubulars, etc.) may be run into a wellbore and cemented in place. The process
of cementing
the pipe string in place is commonly referred to as "primary cementing." In a
typical
primary cementing method, a cement composition may be pumped into an annulus
between
the walls of the wellbore and the exterior surface of the pipe string disposed
therein. The
cement composition may set in the annular space, thereby fin-ming an annular
sheath of
hardened, substantially impermeable cement (i.e., a cement sheath) that may
support and
position the pipe string in the wellbore and may bond the exterior surface of
the pipe string
to the subterranean formation. Among other things, the cement sheath
surrounding the pipe
string functions to prevent the migration of fluids in the annulus, as well as
protecting the
.. pipe string from corrosion. Cement compositions also may be used in
remedial cementing
methods, for example, to seal cracks or holes in pipe strings or cement.
sheaths, to seal highly
permeable formation zones or fractures, to place a cement plug, and the like.
[00021 A broad variety of cement compositions have been used in subterranean
cementing operations. In some instances, set-delayed cement compositions have
been used.
Set-delayed cement compositions are characterized by remaining in a pumpable
fluid state
for at least about one day (e,gõ at least about 7 days, about 2 weeks, about 2
years or more)
at room temperature (e.g., about 80 F) in quiescent storage. When desired fOr
use, the set-
delayed cement compositions should be capable of being activated whereby
reasonable
compressive strengths are developed. For example, a cement set accelerator may
be added to
a set-delayed cement composition whereby the composition sets into a hardened
mass.
Among other things, the set-delayed cement composition may be suitable ibr use
in wellbore
applications, for example, when.' it is desired to prepare the cement
composition in advance.
This may allow, for example, the cement composition to be stored prior to its
use. In
addition, this may allow, for example, the cement composition to be prepared
at a convenient
location and then transported to the job site. Accordingly. capital
expenditures may be
reduced due to a reduction in the need for on-site hulk storage and mixing
equipment. This
may be particularly useful for offshore cementing operations where space
onboard the
vessels may be limited.
[0003] While set-delayed cement compositions have been developed heretofore.
challenges exist with their successful use in subterranean cementing
operations. For
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example, set-delayed cement compositions prepared with Portland cement may
have
undesired gelation issues which can limit their use and effectiveness in
cementing
operations. Other set-delayed compositions that have been developed, tbr
example., those
comprisine hydrated lime and quartz, may be effective in some operations but
may have
limited use at lower temperatures as they may not develop sufficient
compressive strength
when used in subterranean tbrmations having lower bottom hole static
temperatures.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0001] These drawings illustrate certain aspects of some of the embodiments of
the
present method, and should not be used to limit or define the method.
[0002.I FIG. I illustrates a system for preparation and delivery of a set-
delayed
5cemen1 composition to a wellbore in accordance with certain embodiments.
100031 FIG. 2A illustrates surface equipment that may be used in placement of
a set
delayed cement composition in a wellbore in accordance with certain
embodiments.
100041 FIG. 213 illustrates placement of a set-delayed cement composition into
a
wellbore annulus in accordance with certain embodiments.
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DESCRIPTION OF PREFERRED EMBODIMENTS
[0005J The e...xample embodiments relate to subterranean (*meaning operations
and,
more particularly, in certain embodiments, to set-delayed cement compositions
and methods
of using set-delayed cement compositions in subterranean thrmations.
[0006J Embodiments of the set-delayed cement compositions may generally
comprise water, pumice, hydrated lime, and a set retarder. Optionally, the set-
delayed
cement compositions may further comprise a dispersant. Embodiments of the set-
delayed
cement compositions may be foamed. Advantageously, embodiments of the set-
delayed
cement exuripositions may be capable of remaining in a pimipable fluid state
tbr an extended
period of time. For example, the set-delayed cement compositions may remain in
a
pumpable fluid state for at least about I day, about 2 weeks, about 2 years,
or longer.
Advantageously, the set-delayed cement compositions may develop reasonable
compressive
strengths after activation at relatively low temperatures. While the set-
delayed cement
compositions may be suitable for a number of subterranean cementing
operations, they may
be particularly suitable tbr use in subterranean tbrmations having relatively
low bottom hole
static temperatures, e.g., temperatures less than about 200 F or ranging from
about 100 F to
about 200F. In alternative embodiments, the set-delayed cement compositions
may be used
in subterranean formations having bottom hole static temperatures up to 450'F
or higher.
[00071 The water used in embodiments of the set-delayed cement compositions
may
be from any source provided that it does not contain an excess of compounds
that may
undesirably affect other components in the set-delayed cement compositions.
For example, a
set-delayed cement composition may comprise fresh water or salt water. Salt
water
generally may include one or more dissolved salts therein and may be saturated
or
unsaturated as desired for a particular application. Seawater or brines may be
suitable for
use in embodiments. Further, the water may be present in an amount sufficient
to tbrm a
pumpable slurry, In certain embodiments, the water may be present in the set-
delayed
Cement composition in an amount in the range of from about 33% to about 200%
by weight
of the pumice. In certain embodiments, the water may be present in the set-
delayed cement
compositions in an amount in the range of from about 35% to about 70% by
weight of The
pumice. One of ordinary skill in the art with the benefit of this disclosure
will recognize the
appropriate amount of water for a chosen application.
[00081 Embodiments of the set-delayed cement compositions may comprise pumice.
Generally, pumice is a volcanic rock that can exhibit cementitious properties
in that it may
set and harden in the presence of hydrated time and water. The pumice may also
be ground,
Generally, the pumice may have any particle size distribution as desired tbr a
particular
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application. In certain embodiments, the pumice may have a mean particle size
in a range of
from about 1 micron to about 200 microns. The mean particle size corresponds
to d50
values as measured by particle size analyzers such as those manufactured by
Malvern
instruments, Worcestershire, linked Kingdom, In specific embodiments, the
pumice may
.. have a mean particle size in a range of from about 1 micron to about 200
microns, from
about 5 microns to about 100 microns, or from about 10 microns to about 50
microns. In
one particular embodiment, the pumice may have a mean particle size of less
than about 15
microns. An example of a suitable pumice is available from Hess Pumice
Products, in..
Ivialad, Idaho, as DS-325 lightweight aggregate, having a particle size of
less than about 15
microns. It should be appreciated that particle sizes too small may have
mixability problems
while particle sizes too large may not be effectively suspended in the
compositions. One of
ordinary skill in the art, with the benefit of this disclosure. should be able
to select a particle
size for the pumice suitable for a chosen application.
[00091 Embodiments of the set-delayed cement compositions may comprise
.. hydrated lime. As used herein, the term "hydrated lime" will be understood
to mean calcium
hydroxide, in some embodiments, the hydrated lime may be provided as quicklime
(calcium
oxide) which hydrates when mixed with water to form the hydrated lime. The
hydrated lime
may be included in embodiments of the set-delayed cement compositions, for
example, to
form a hydraulic composition with the pumice. For example, the hydrated lime
may be
.. included in a pumice-to-hydrated-lime weight ratio of about 10:1 to about
1:1 or 3:1 to about
5:1. Where present, the hydrated lime may be included in the set-delayed
cement
compositions in an amount in the range of from about. 10% to about 100% by
weight of the
pumice, for example. in some embodiments, the hydrated lime may be present in
an amount
ranging between any of and/or including any of about 10%, about 20%, about
40%, about
60%, about 80%, or about 100% by weight of the pumice hi some embodiments, the
cementitious components present in the set-delayed cement composition may
consist
essentially of the pumice and the hydrated lime. For example, the cementitious
components
may primarily comprise the pumice and the hydrated lime without any additional
components (e.g., Portland cement, fly ash, sin cement) that hydraulically set
in the
presence of water. One of ordinary skill in the art, with the benefit of this
disclosure, will
recognize the appropriate amount of the hydrated lime to include for a chosen
application.
[00101 Embodiments of the set-delayed cement compositions may comprise a set
retarder. A broad variety of set retarders may be suitable for use in the set-
delayed cement
compositions. For example, the set retarder may comprise phosphonic acids,
such as
.. ethylenediamine tetra(methylene phosphonie acid), diethylenetriamine
penta(methylene
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phosphonic acid), etc.; lignosultbnates, such as sodium lignosultbnate,
calcium
lignosulfonate, etc.; salts such as stannous sulfate, lead acetate, monobasic
calcium
phosphate, organic. acids, such as citric acid, tartaric acid, etc.; cellulose
derivatives such as
hydroxA ethyl cellulose (T1EC) and carboxymethyl hydroxyethyl cellulose (CMHE(
);
synthetic co- or ter-polymers comprising sulfonate and carboxylic acid groups
such as
sulfonate-functionalized acrylamide-acrylic acid co-polymers; borate compounds
such as
alkali berates, sodium meta borate, sodium tetraborate, potassium pentaborate:
derivatives
thereof, or mixtures thereof Examples of suitable set retarders include, among
others,
phosphonic acid derivatives. One example of a suitable set retarder is Micro
Matrix cement
retarder, available, from Halliburton Energy Services, Inc. Generally, the set
retarder may be
present in the set-delayed cement compositions in an amount sufficient to
delay the setting
for a desired time. In some embodiments, the set retarder may be present in
the set-delayed
cement compositions in an amount M the range of from about 0.01% to about 10%
by weight
of the pumice. In specific embodiments, the set retarder may be present in an
amount
ranging between any of and/or including any of about 0.01%, about 0.1%, about
1%, about
2%, about 4%, about 6%, about- 8%, or about 10% by weight of the pumice. One
of ordinary
skill in the art, with the benefit of this disclosure, will recognize the
appropriate amount or
the set retarder to include for a Chosen application.
[00111 As previously mentioned, embodiments of the set-delayed cement
compositions may optionally comprise a dispersant. Examples of suitable
dispersants
include., without limitation sulfonated-formaldehyde-based dispersant s (e.g.,
sulfonated
acetone formaldehyde condensate), examples of which may include Dane 19
available
from Geo Specialty Chemicals, Ambler. Pennsylvania. Other suitable dispersants
may be
polycarboxylated ether dispersants' such as Liquitnene' 5581F and Liquimeie
5141,
available from BASF Corporation Houston, Texas; or Ethacryl G available from
Coatex,
Gently-, France. An additional example of a suitable commercially available
dispersant is
CFR"-3 dispersant, available from HaIliburton Energy Services, Inc. Houston,
Texas. Of
particular importance in regards to the examples that follow, is that the
Liquimene 5141.
dispersant comprises 36% by weight of the polycarboxylated ether in water.
While a variety
of dispersants may be used in accordance with embodiments, polycarboxylated
ether
dispersants may be particularly suitable -Eby use in some embodiments. Without
being
limited by theory, it is believed that polycarboxylated ether dispersants may
synergistically
interact with other components of the set-delayed cement composition. For
example, it is
believed that the polycarboxylated ether dispersants may react with certain
set retarders (e.g.,
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phosphonic acid derivatives) resulting in formation of a gel that suspends the
pumice and
hydrated lime in the composition for an extended period of time.
00121 in some embodiments, the dispersant may be included in the set-delayed
cement compositions in an amount in the range of from about 0.01% to about 5%
by weight
.. of the pumice. in specific embodiments, the dispersant may be present in an
amount ranging
between any of and/or including any of about 0.01%, about 0.1%, 0.5%, about
1%, about
2%, about 3%, about 4%, or about 5% by weight of the pumice. One of ordinary
skill in the
art, with the benefit of this disclosure, will recognize the appropriate
amount of the
dispersant to include for a chosen application.
[0013] Embodiments of the set-delayed cement compositions may comprise a
mechanical property enhancing additive. Mechanical-property-enhancing
additives may be
included in embodiments of the set-delayed compositions to, for example,
ensure adequate
compressive strength and long-term structural integrity. These properties can
be affected by
the strains, stresses, temperature, pressure, and impact effects from a
subterranean
environment, Examples of mechanical property enhancing additives include
fibers, such as
graphitic carbon fibers, glass fibers, steel fibers, mineral fibers, silica
fibers, polyester fibers,
polyamide fibers, and polyolefin fibers, among others. Specific examples of
graphitic carbon
fibers include fibers derived from polyacrylonitrile rayon, and petroleum
pitch, Where us.xl,
the mechanical-property-enhancing additives may be present in an amount from
about 0,01%
to about 5% by weight of the pumice. In specific embodiments, the mechanical-
property-
enhancing additives may be present in an amount ranging between any of andfor
including
any of about 0.01%, about 0,1%, 0.5%, about 1%, about 2%, about 3%, about 4%,
or about
5% by weight of the pumice. One of ordinary skill in the art, with the benefit
of this
disclosure, will recognize the appropriate amowit of the mechanical-property-
enhancing
additives to include for a chosen application.
[0014] Other additives suitable for use in subterranean cementing operations
also
may be included in embodiments of the set-delayed cement compositions.
Examples of such
additives include, but are not limited to, weighting agents, lightweight
additives, gas-
generating additives, lost-circulation materials, filtration-control
additives, fluid-loss-control
additives, defoamink.-,! agents, foaming agents, thixotropic additives, and
combinations
thereof. In embodiments, one or more of these additives may be added to the
set-delayed
cement composition alter storing but prior to placement of the set-delayed
cement
composition into a subterranean formation. 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.
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[00151 Those of ordinary skill in the art will appreciate that embodiments of
the set-
delayed cement compositions generally should have a, density suitable for a
particular
application. By way of example, the set-delayed cement compositions may have a
density in
the range of from about 4 pounds per gallon ("lb/gal") to about 20 lb/gal. In
certain
embodiments, the set-delayed cement compositions may have a density in the
range of from
about 8 lb/gal to about 17 lb/gal. Embodiments of the set-delayed cement
compositions may
he foamed or unfoamed or may comprise other means to reduce their densities,
such as
hollow microspheres, low-density elastic beads, or other density-reducing
additives known
in the art. In embodiments, the density may be reduced after storing the
composition, but
prior to placement in a subterranean formation. Those of ordinary skill in the
art, with the
benefit of this disclosure, will teeognize the appropriate density for a
,particular application.
[00161 As discussed above, embodiments of the set-delayed cement compositions
may be foamed. Embodiments of the set-delayed cement compositions may be
foamed to
provide a lightweight composition that does not exert excessive force on
formations
penetrated by the wellbore In addition to being lightweight, a foamed
composition may also
improve the ability of the composition to maintain pressure and prevent the
flow of
formation fluids into and through the composition during its transition time.
Foamed
compositions may also be advantageous because they have low fluid loss
properties, thus
limiting loss of fluid circulation. Additionally, foamed compositions when set
may also have
a lower modulus of elasticity than non-foamed compositions, which is often
desirable as it
enables the resultant set cement composition to resist stresses exerted on the
composition in
situ.
[0017] In particular embodiments, the set-delayed cement composition may be
foamed at the well site. By way of example, the set-delayed cement
compositions may be
foamed immediately prior to use. Embodiments may be foamed with a foaming
additive and
by entraining gas into the set-delayed cement compositions. In particular
embodiments, the
foaming additive and gas may be introduced after combination of the
composition with an
activator. The set-delayed cement compositions may be foamed, for example, to
provide a
set-delayed cement composition with a reduced density.
[0018] The gas used for foaming the composition may be any suitable gas for
foaming, including, but not limited to: air, nitrogen, and combinations
thereof. Generally, the
gas should be in an amount sufficient to form the desired foam, Foaming
additives may be
included in embodiments to, for example, facilitate foaming and/or stabilize
the resultant
foam formed therewith.
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100191 In particular embodiments, the thinning additive may include a
surfactant or
combination of surfactants that reduce the surface tension of the water. By
way of example,
the thatning agent may comprise an anionic, nonionic, amphoteric (including
zwitterionic
surfactants), cationic surfactant, Or mixtures thereof Examples of suitable
foaming additives
include, but are not limited to: betaines: anionic mit-filet:ants such as
hydrolyzed keratin;
amine oxides such as a alkyl or alkene &methyl amine oxides; cocoamidopropyl
dimethylamine oxide; methyl ester sulfbnates; alkyl or alkene amidobetaines
such as
cocoamidopropyl betaine: alpha-olefin sulfonatcs; quaternary surfactants such
as
trimethyltallowammonium chloride and trimethylcocoarrimonium chloride; C8 to
C22
alkylethoxylate sulfates; and combinations thereof. Specific examples or
suitable foaming
agents include mixtures of an ammonium salt of an alkyl ether sulfate, a
cocoamidopropyl
betaine surfactant, a cocoamidopropyl dimethylamine oxide surfactant, sodium
chloride, and
water; mixtues of an ammonium salt of an alkyl ether sulfate surfactant, a
cocoamidopropyl
hydroxysuhaine surfactant, a cocoamidopropyl dimethylamine oxide surfactant,
sodium
chloride, and water; mixtures of an ethoxylated alcohol ether sulfate
surfactant, an alkyl or
alkenc amidopropyl beanie surfactant, and an alkyl or alkene dimethylamine
oxide
surfactant; aqueous solutions of an alpha-olefinic sulfonate surfactant and a
betaine
surfactant; and combinations thereof Examples of suitable fbarning additives
are
ZONESEALANTT" 2000 agent and Eoamer 1026, both available from Halliburton
Energy
Services Inc., Houston, Texas. Embodiments may he foamed within a foam quality
range of
between about 5% to about 80% and, more particularly, from about 18% to about
38%. As
used herein, the term "foam quality- refers to the volume of entrained gas and
is defined by
the following formula; Foam Quality = (Total Foam Volume- Liquid Volume) /
Total Foam
Volume.
[00201 As previously mentioned, the cement compositions may have a delayed set
in
that they remain in a pumpable fluid state for at least one day (e..g., at
least about I day,
about 2 weeks, about 2 years, or longer) at room temperature in quiescent
storage. Pot
example, the set-delayed cement compositions may remain in a pumpable fluid
state tor a
period of time from about I day, about 2 weeks, about 2 years, or longer. In
some
embodiments, the set-delayed cement compositions may remain in a pumpable
fluid state for
at least about 1 day, about 7 days, about 10 days, about 20 days, about 30
days, about 40
days, about SO days, about 60 days, about 2 years, or longer. A fluid is
considered to be in a
pumpable fluid state where the fluid has a consistency of less than 70 Bearden
units of
consistency ("Be), as measured on a high-temperature high-pressure
consistometer at room
temperature (e4.1., about 80 F) in accordance with the procedure for
determining cement
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thickening times set forth in API RP Practice 108-2, Recommended Practice for
Testing
Well Cements, First Edition, July 2005.
[0021] When desired for use, embodiments of the set-delayed cement
compositions
may be activated (e.g., by combination with an activator) to thereby set into
a hardened
mass. By way of example, embodiments of the set-delayed cement compositions
may be
activated to set to form a hardened mass in a time period in the range of frOM
about 1 hour to
about 12 hours, For example, embodiments of the set-delayed cement
compositions may set
to fonn a hardened mass in a time period ranging between any of and/or
including any of
about I day, about 2 days, about 4 days, about 6 days, about 8 days, about 10
days, or about
.. 12 days.
[0022] In some embodiments, the set-delayed cement compositions may set to
have
a desirable compressive strength after activation. Compressive strength is
generally the
capacity of a material or structure to withstand axially directed pushing
fbrces. The
compressive strength may be measured at a specified time after the set-delayed
cement
composition has been activated and the resultant composition is maintained
under specific
temperature and pressure controls. Compressive strength can be measured by
either a
destructive method or non-destructive method. The destructive method
physically tests the
strength of treatment fluid samples at various points in time by crushing the
samples in a
compression-testing machine. The compressive strength is calculated from the
failure load
.. divided by the cross-sectional area resisting the load and is reported in
units of pound-force
per square inch (psi). Non-destructive methods typically may employ an
Ultrasonic Cement
Analyzer C'UCA"), available from Eann Instrument Company, Houston, TX.
Compressive
strengths may be determined in accordance with API RP 1013-2, Recommended
Pmetke
Testing Well Cements, First Edition, July 2005,
[00231 13y way of .tliatriple, the set-delayed cement composition, may develop
a 24
hour compressive strength in the range of from about 50 psi to about 5000 psi,
alternatively,
from about 100 psi to about 4500 psi, or alternatively from about 500 psi to
about 4000 psi.
In some embodiments, the set-delayed cement composition may develop a
compressive
strength in 24 hours of at least about 50 psi, at least about 100 psi, at
least about 500 psi, or
.. more. In some embodiments, the compressive strength values may be
determined using
destructive or non-destructive methods at a temperature ranging from 100T to
200 F,
[0024] Embodiments may include the addition of a cement set activator to the
set-
delayed cement compositions. Examples of suitable cement set activators
include, but are
not limited to: amines such as triethanolamine, diethanolamine; silicates such
as sodium
15 silicate: zinc formate; calcium acetate; Groups IA and IIA hydroxides
such as sodium
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hydroxide, magnesium hydroxide, and calcium hydroxide; monovalent salts such
as sodium
chloride; divalent salts such as calcium chloride; nanosilica (i.e., silica
having a particle size
of less than or equal to about 100 nanometers); polyphosphates; and
combinations thereof In
some embodiments, a combination of the polyphosphate and a monovalent salt may
be used
for activation. The monovalent salt may be any salt that dissociates to .1brin
a monovalent
cation, such as sodium and potassium salts. Specific examples of suitable
monovalent salts
include potassium sulfate, and sodium sul fate. A variety of different
polyphosphates may be
used in combination with the monovalent salt for activation of the set-delayed
cement
compositions, including polymeric metaphosphate salts, phosphate salts, and
combinations
thereof Specific examples of polymeric metaphosphate salts that may be used
include
sodium hexametaphosphate, sodium trimetaphosphate, sodium tetrametapbosphate,
sodium
pentamentphosphate. sodium heptametaphosphate, sodium octametaphosphate, and
combinations thereof. A specific example of a suitable cement set activator
comprises a
combination of sodium sulfate and sodium hexametaphosphate. In particular
embodiments,
the activator may be provided and added to the set-delayed cement composition
as a liquid
additive, for example, a liquid additive comprising a monovalent salt, a
polyphosphate, and
optionally a dispersant
[0025] The cement set activator should be added to embodiments of the set-
delayed
cement composition in an amount sufficient to activate the set-delayed cement
composition
to set into a hardened mass. In certain embodiments, the cement set activator
may be added
to the set-delayed cement composition in an amount in the range of about 1% to
about 20%
by weight of the pumice. In specific embodiments, the cement set activator may
be present in
an amount ranging between any of andlor including any of about 1%, about 5%,
about 10%,
about 15* or about 20% by weight of the pumice. One of ordinal .y skill in the
an with the
benefit of this disclosure, will recognize the appropriate amount of the
cement set activator
to include for a chosen application.
[0026] As will be appreciated by those of ordinary skill in the art,
embodiments of
the set-delayed cement compositions may be used in a variety of subterranean
operations,
including primary and remedial cementing. In some embodiments, a set-delayed
cement
composition may be provided that eomprises water, pumice, hydrated lime, a set
retarder,
and optionally a dispersant. The set-delayed cement composition may be
introduced into a
subterranean formation and allowed to set therein. As used herein, introducing
the set-
delayed cement composition into a subterranean formation includes introduction
into any
portion of the subterranean formation, including, without limitation, into a
welIbore drilled
into the subterranean formation, into a near wellbore region surrounding the
wellbore, or into
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both. Embodiments may further include activation of the set-delayed cement
composition.
The activation of the set-delayed cement composition may comprise, Ibr
example, the
addition of a cement set activator to the set-delayed cement composition,
100271 In some embodiments, a set-delayed cement composition may be provided
that comprises water, pumice, hydrated lime, a set retarder, and optionally a
dispersant. The
set-delayed cement composition may be stored, for example, in a vessel or
other suitable
container. The set-delayed cement composition may be permitted to remain in
storage for a
desired time period. For example, the set-delayed cement composition may
remain in
storage for a time period of about I day, about 2 weeks, about 2 years, or
longer. For
example, the set-delayed cement composition may remain in storage for a time
period of
about I day, about 2 days, about 5 days. about 7 days, about 10 days, about 20
days, about
30 days, about 40 days, about 50 days, about 60 days, about 2 years. or
longer. In some
embodiments, the set-delayed cement composition may remain in storage for a
time period in
a range of from about 1 day to about 2 years or longer. Thereafter, the set-
delayed cement
.. composition may be activated, for example, by addition of a cement set
activator, introduced
into a subterranean formation, and allowed to set therein. Optionally, the set-
delayed cement
composition may be foamed prior to introduction into the subterranean
formation.
[0028] In primary cementing embodiments, for example, embodiments of the set-
delayed cement composition may be introduced into an annular space between a
conduit
located in a WabOre and the walls of a wellbore (and/or a larger conduit in
the xvellbore),
wherein the wellbore penetrates the subterranean formation. The set-delayed
cement
composition may be allowed to set in the annular space to form an annular
sheath of
hardened cement. The set-delayed cement composition may form a barrier that
prevents the
migration of fluids in the wellbore. The set-delayed cement composition may
also, for
example, support the conduit in the wellbore.
[0029] In remedial cementing embodiments, a set-delayed cement composition may
be used, for example, in squeeze-cementing operations or in the placement of
cement plugs.
By way of example, the set-delayed composition may be placed in a wellbore to
plum an
opening such as a void or crack that is in the formation, in a gravel pack, in
the conduit, in
the cement sheath, and/or between the cement sheath and the conduit (e.g., a
mieroannulus).
1003011 An example embodiment comprises a method of cementing in a
subterranean
formation comprising: providing a set-delayed cement composition comprising
water,
pumice, hydrated lime, and a set retarder; foaming the set-delayed cement
composition;
activating the foamed set-delayed cement composition; introducing the foamed
set-delayed
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cement composition into a subterranean formation; and allowing the foamed set-
delayed
cement composition to set in the subterranean formation.
[0031 ] An example embodiment comprises a foamed set-delayed cement
eomposition comprising: water, pumice, hydrated lime, a foaming additive,
entrained gas,
and a set retarder.
[0032] An example embodiment comprises a system for cementing comprising; a
set-delayed cement composition comprising: water, pumice, hydrated lime, a set
retarder, a
foaming additive for foaming the set-delayed cement composition; a gas for
foaming, the set-
delayed cement composition; and a cement set activator for activation of the
set-delayed
cement composition.
[0033] Referring now to FIG. 1, preparation of a set-delayed cement
composition in
accordance with example .embodiments will now he described. FIG, 1 illustrates
a system 2
for preparation of a set-delayed cement composition and delivery to a wellbore
in accordance
with certain embodiments. As shown, the set-delayed cement composition may be
mixed in
mixing equipment 4, such as a jet mixer, re-circulating mixer, or a batch
mixer, for example,
and then pumped via pumping equipment 6 to the wellbore. In some embodiments,
the
mixing equipment 4 and the pumping equipment 6 may be disposed on one or more
cement
trucks as will be app rent to those of ordinary skill M the art in some
embodiments, a jet
mixer may be used, for example, to continuously mix the time/gettable material
with the
water as it is being pumped to the wellbore.
[0034] An example technique for placing a set-delayed cement composition into
a
subterranean formation will now be described with reference to FIGS, 2A and
213. FIG. 2A
illustrates surface equipment 10 that may be used in placement of a set-
delayed cement
composition in accordance with certain embodiments. It should be noted that
while FIG. 2A
generally depicts a land-based operation, those skilled in the art will
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 by FIG. 2A, the surface equipment 10 may include a cementing
unit 12, which
may include one or more cement trucks. The cementing unit 12 may include
mixing
equipment 4 and pumping equipment 6 (e.g., FIG. 1) as will be apparent to
those of ordinary
skill in the art. The cementing unit 12 may pump a set-delayed cement
composition 14
through a feed pipe 16 and to a cementing head 18 which conveys the set-
delayed cement
composition 14 downhole.
[0035] Turning now to FIG. 213, the set-delayed cement composition 14 may be
placed into a subterranean formation 20 in accordance with example
embodiments. As
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illustrated, a \venom 22 may be drilled into the subterranean formation 20.
While wellbore
22 is shown extending E,,enerally vertically into the subteroinean formation
20., the principles
described herein are also applicable to wellbores that extend at an angle
through the
subterranean formation 20, such as horizontal and slanted u'ellbores. As
illustrated, the
wellbore 22 comprises walls 24. In the illustrated embodiment, a surface
easing 26 has been
inserted into the wellbore 22. The surface casing 26 may be cemented to the
walls 24 of the
wellbore 22 by cement sheath 28. in the illustrated embodiment, one or more
additional
conduits (e.g., intermediate easingõ, production casing, liners, etc..), shown
here as casing 30
may also be disposed in the wellbore 22. As illustrated, there is a wellbore
annulus 32
formed between the casing 30 and the walls 24 of the wellbore 22 andlor the
surface casing
26. One or more centralizers 34 may be attached to the casing 30, liar
example, to centralize
the casing 30 in the wellbore 22 prior to and during the cementing operation.
[00361 With continued reference to FIG. 2B, the set-delayed cement composition
14
may he pumped do ii the interior of the casing 30. The set-delayed cement
composition 14
may be allowed to flow down the interior of the casing 30 through the casing
shoe 42 at the
bottom of the easing 30 and up around the easing 30 into the wellbore annulus
32. The set
delayed cement composition 14 may be allowed to set in the welittore annulus
32, for
example, to form a cement sheath that supports and positions the casing 30 in
the wellbore
22. While not illustrated, other techniques may also be utilized for
introduction of the set-
delayed cement composition 14. By way of example, reverse circulation
techniques may be
used that include introducing the set-delayed cement composition 14 into the
subterranean
formation 20 by way of the wellbore annulus 32 instead of through the easing
30,
[00371 As it is introduced, the set-delayed cement composition 14 may displace
other fluids 36, such as drilling fluids and/or spacer fluids that may be
present in the interior
of the casing 30 and/or the wellbore annulus 32. At least a portion of the
displaced fluids 36
may exit the wellbore annulus 32 via a flow line 38 and be deposited, for
example, in one or
more retention pits 40 (c.a., a mud ph), as shown on FIG. 2A. Referring again
to FIG. 213, a
bottom plug 44 may be introduced into the wellbore 22 ahead of the set-delayed
cement
composition 14, for example, to separate the set-delayed cement composition 14
from the
fluids 36 that may he inside the casing 30 prior to cementing. After the
bottom plug 44
reaches the landing collar 46. a diaphragm or other suitable device should
rupture to allow
the set-delayed cement composition 14 through the bottom plug 44. In FIG. 213,
the bottom
plug 44 is shown on the landing collar 46. In the illustrated embodiment, a
top plug 48 may
be introduced into the wellbore 22 behind the set-delayed cement composition
14. The top
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plug 48 may separate the set-delayed cement composition 14 from a displacement
fluid 50
and also push the set-delayed cement composition 14 through the bottom plug
44.
[00381 The exemplary set-delayed cement compositions disclosed herein may
directly or indirectly affect one or more components or pieces of equipment
associated with
the preparation, delivery, recapture, recycling, muse, and/or disposal of the
disclosed set-
delayed cement compositions. For example, the disclosed set-delayed cement
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 set-delayed cement compositions. The disclosed set-delayed cement
compositions
may also directly or indirectly affect any transport or delivery equipment
used to convey the
set-delayed cement compositions to a well site or downhole such as, fbr
example, any
transport vessels, conduits, pipelines, trucks, tubulars, and/or pipes used to
compositionally
move the set-delayed cement compositions from one location to another, any
pumps,
compressors, or motors (e.g., topside or downhole) used to drive the set-
delayed cement
compositions into motion, any valves or related joints used to regulate the
pressure or flow
rate of the set-delayed cement compositions, and any sensors (i.e., pressure
and temperature),
gauges, and/or combinations thereof, and the like. The disclosed set-delayed
cement
compositions may also directly or indirectly affect the various downhole
equipment and
tools that may come into contact with the set-delayed cement compositions such
as, but not
limited to, wellbore easing, wellhore liner, completion string, insert
strings, drill string,
coiled tubing, slickline, wireline, drill pipe, drill collars, mud motors.
downhole motors
and/or pumps, cement pumps, surface-mounted motors and/or pumps, centralizers,
turbolizers, scratchers, floats (e.g., shoes, collars, valves, etc.), logging
tools and related
telemetry equipment, actuators (e.g., electromechanical devices,
hydromechanical 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 elesctro-hydraulic wet connect, dry connect, inductive
coupler, etc.), control
lines (e.g., electrical, fiber optic, hydraulic, etc.), surveillance lines,
drill bits and reamers,
sensors or distributed sensors, downhole heat exchangers, valves and
corresponding
actuation devices, tool seals, packers, cement plugs, bridge plugs, and other
wellbore
isolation devices, or components, and the like.
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EXAMPLES
[0039] To facilitate a better understanding of the present embodiments, 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 embodiments.
Example l
[00401 A sample set-delayed cement composition was prepared with the Ibllowing
components: purnice (DS-325 lightw,eight aggregate), hydrated limeõ dispersant
(Liquimene
55(1F), primary retarder (Micro Matrix cement retarder), weighting additive
(MicroMax
Weight Additive, available from Ilatliburton Energy Services, Inc., Houston,
Texas),
secondary retarder (Hie-5 cement retarder, available from Halliburton Energy
Services,
Incõ Houston, Texas), Class 11 Portland cement, and water. Each component,
with the
exception of the primary retarder (Micro Matrix cement retarder), is presented
as a
percentage of the weight of pumice (bwoP). The primary retarder is measured in
units of
gallons per 46 pound sack of pumice (galisk). The compositional makeup is
listed in Table 1
below.
Table I
Sample Set-Delayed C7ement Compositional Makeup
Material Amount Units Weight (g) % bw n
total
Pumice 100 bwoP 58682.7 55.56
Hydrated lime 10 % bwoP 11736.5 11.11
Dispersant 0.5 % bwoP 291.1 0.28
Primaiy Retarder 0.06 ga Usk 734.6 0.70
Weighting Additive 2 % bwoP 1173.7 1.11
Secondary Retarder 0.5 % bwoP 293.4 0,28
Portland Cement 2 % bwoP 1173.7 1.11
Water 53.7 bwoP 31534.5 29.86
Total 105620.2 100
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100411 The sample in Example I remained fluid, mixable, pumpable, and stable
with
no solids settling or gelation %r greater than 40 days, The sample had a
measured density of
13.5 pounds per gallon. Minimal doses of dispersant were added during the
storage period to
maintain the slurry's optimal theology, 'This exemplary sample serves as the
base slurry tbr
.. the remaining examples provided below.
Example 2
00421 The theological properties of the sample set-delayed cement composition
of
Example 1 were measured after storing the samples at room temperature and
pressure for a
period of 41 days. After preparation, the theological properties of the
samples were
determined mina a Model 35A Fann Viscometer and a No. 2 spring with a Fann
Yield Stress
Adapter, in accordance with the procedure set lbrth in API RP Practice 1013-2,
Recommended Practice for Testing Well Cements. The results of this test are
set forth in
Table 2 below.
Table 2
Viscosity Tests
FYSA Readings
Age of Sample ___________________________________________________
(days) RPM 3 6 100 I 200 300 1 I 3D 61)
___________________________________________ t
41 A VG. 13 13 35 1 56 75.5 5 4
Example 3
10043] Three sample set-delayed cement compositions, samples 1-3, and two
controls, controls I and 2, were prepared from the base slurry described in
Example 1.
Foamer 1026CM, a foaming additive, was added to each of the three samples in
varying
amounts after a time period of 41 days. Additionally, a cement set activator,
CaCl2, was
added to sample 2 and control 2. The amount of the cement set activator added
to each
sample was sufficient to deliver a 5% by weight of pumice activator amount to
the set-
delayed cement composition. The base and foamed densities were measured.
Additionally,
the destructive compressive strength was measured using a mechanical press in
accordance
with API RP Practice 1013-2, Recommended Practice fOr Testing Well Cements.
Additionally, the destructive compressive stmngth was measured by allowing the
samples to
cure in a 2" by 4" plastic cylinder that was placed in a water bath at 190T to
form set
cylinders. Immediately after removal from the water bath, destructive
compressive strengths
were determined using a mechanical press in accordance with API RP I013-2,
Recommended
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Praeriechr Testing 1-*// Cements. The results of this test are set forth
below. The reported
compressive strengths are an average for two cylinders of each sample. The
samples and
controls were cured at I atmosphere, 190 F; compressive strength measurements
were taken
at 72 hours.
Table 3
Compositional Maheup and Characteristics
Sample I Sample
2 Sample 3 Control 1 Control 2
Sample Weight (g) 1363.2 = 1363.2 1363.2 817.5 817.5
Foaming Additive (g) 8.14 12.21 14
Activator (g) 37.87 25.8
4
Base Density (ppg) 13.5 13.5 13.5 13.5 13.3*
Foamed Density (ppg) 11 9.1 9.2
Foam Quality 19% I 33% 32%
Compressive Strength (psi) 639.37 534.45 135.18 1222.46 1360.14
*Density of Control 2 with the Activator,
[0044] In addition to the characteristics of Table 3, the foam stability of
samples 1-3
was measured in both the slurry state and the set state. This data is set
forth in Table 4 below.
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Table 4
Foam Stability Measurements.
Foam Stability Sat'11 pie 1 Sample 2 SUMAC 3
Slurry Set Shiny Set Slurry Set
More than a trace of free fluid?
Bubbles on surface of bubble coalescing
(breaking, enlargement, merging)?
Excessive column-height reduction?
Signs of density segreg,tnion (streaking or dark
coloration from top to bottom)?
(0045) The Archimedes Method was used to measure the slurry density of Samples
1-3 in top, middle, and bottom portions. Densities that were close in weight
from top to
bottom indicate stable foam while considerable variation in densities
indicates unstable
foam. All units are in pounds per gallon. This data is set forth in Table 5
below.
Table 5
Density Uniformity
Archimedes Method Example I Example 2 Example 3
Top (ppg) 10.50 8.95 9.26
Middle (ppg) 10.52 8.99 9.30
Bottom (ppg) 10,46 8.83 9.25
f0046] Lastly, the theology of foamed Samples 11 waS measured using the same
technique as used in Example 2 to measure the theology of the base shirty. The
base slurry is
designated as Control 1 in Table 6 below, The theology data is set thrth in
Table 6 below.
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Table 6
Viscosity 'rests
. .
PYSA Readings
Density
(17Pg) RPM 3 6 100 200 300 30 61)
Control 1 133 AVG. 13 13 35 56 75.5 5 4
Sample 1 = 11 AVG. 10 10.5 13.5 50.25 65.5
3.5 7.5
Sample 2 9.1 AVG. 2.25 3 17.5 29.5 40 1.5
Sample 3 9.7 AVG. 17 17.5 40.5 56.5 70.5
12 9
[0047] Example 3 thus indicates that the foamed slurries exhibit good
compressive
strength while maintaining suitable rheoloaies and uniform densities.
Example 4
100481 Two sample set-delayed cement compositions. samples 4 and 5, were
prepared from the base slurry described in Example I. A cement set activator,
CaCk, was
added to the samples in an amount sufficient to deliver a 5% by weight of
pumice activator
amount to the set-delayed cement composition. Sample 5 further included
graphitic carbon
fibers in an amount of about 0.18% by weight of the pumice. The graphitic
carbon fibers
were PAN carbon fibers derived from polyacrylonitrile, ['barrier 10260, a
foaming additive,
was added to each of the samples in an amount of 0.18% by weight of the
pumice.
Additionally, the destructive compressive strength was measured by allowing
the samples to
cure in a 2" by 4" plastic cylinder that was placed in a water bath at 190 F
to form set
cylinders. Immediately after removal from the water bath, destructive
compressive strengths
were determined using a mechanical press in accordance with API RP 1013-2,
Recommended
Practice fior Testing Well Cements. The results of this test are set forth
below. The reported
compressive strengths are an average for three cylinders of each sample. The
samples and
controls were cured at I atmosphere, 190*F; compressive strength measurements
were taken
at 72 hours.
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Table 7
Compositional Makeup and Characteristics
Sample 4 Sample 5
Base Slurry (g) 1000 .1000
Carbon Fiber (g) 10
Activator (g) 27.8 27.8
Foaming Additive (g) 10 10
Base Density (ppg) 13.5 13.5
Foamed Density (ppg) 833 8.33
Compressive Strength (psi) 62 143
100491 It should be understood that the compositions and methods are described
in
terms of "amiprising," "containing; or "including" various components or
steps, the
compositions and methods can also "consist essentially of' or "consist or the
various
components and steps. Moreover, the indefinite articles -a" or -an,' as used
in the claims,
are defined herein to mean one or morel than one of the element that it
introduces.
[00501 For the sake of brevity, only certain ranges are explicitly disclosed
herein.
However., ranges from any lower limit may be combined with any upper limit to
recite a
range not explicitly recited, as well as, ranges from any lower limit may be
combined with
any other lower limit to recite a range not explicitly recited, in the same
way, ranges from
any upper limit may be combined with any other upper limit to recite a 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 thll.ing within the range are
specifically
disclosed. In particular, every range of values (of the form, '11-om 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 even if not explicitly recited. Thus, every point
or individual
value may serve as its own lower or upper limit combined with any other point
or individual
value or any other lower or upper limit, to recite a range not explicitly
recited.
[00511 Therelbre. the present embodiments are well adapted to attain the ends
and
advantages mentioned as well as those that are inherent therein. 1hc
particular embodiments
disclosed above are illustrative only, and may be modified and practiced in
different but
equivalent manners apparent to those skilled in the art having the benefit of
the teachings
21
herein. Although individual embodiments are discussed, the' invention covers
all
combinations of all those embodiments. Furthermore, no limitations are
intended to the
details of construction or design herein shown, other than as described in the
claims below.
Also, the terms in the claims have their plain, ordinary meaning unless
otherwise explicitly
.. and clearly defined by the patentee. It is therefore evident that the
particular illustrative
embodiments disclosed above may be altered or modified and all such variations
are
considered within the scope and spirit of the invention. If there is any
conflict in the usages
of a word or term in this specification and one or more patent(s) or other
documents that may
be referred to herein, the definitions that are consistent with this
specification should be
.. adopted.
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