Note: Descriptions are shown in the official language in which they were submitted.
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USE OF SYNTHETIC SMECTITE IN SET-DELAYED CEMENT
COMPOSITIONS COMPRISING PUMICE
BACKGROUND
[0001] Embodiments relate to subterranean cementing operations and, in certain
embodiments, to set-delayed cement compositions and methods of using set-
delayed cement
compositions in subterranean formations.
[0002] 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 forming 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.
[0003] 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.g., 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 activator 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 for use in
wellbore
applications, for example, where 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
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a reduction in the need for on-site bulk storage and mixing equipment. This
may be particularly
useful for offshore cementing operations where space onboard the vessels may
be limited.
[0004] While set-delayed cement compositions have been developed heretofore,
challenges exist with their successful use in subterranean cementing
operations. For 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, for example, those comprising 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 formations
having lower bottom hole static temperatures.
[0005] A broad variety of cement densities may be required for an operation
depending upon on the well conditions at the site. Set-delayed cement
compositions may
require unique solutions to adjust the density of the composition while
maintaining a stable
composition that can be stored until needed. As such, some chemical solutions
may destabilize
the slurry. Other solutions such as glass beads may dissolve over time
providing only a
temporary benefit.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0006] 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.
[0007] FIG. I illustrates a system for the preparation and delivery of a set-
delayed
Scement composition to a wellbore in accordance with certain embodiments.
[0008] FIG. 2A illustrates surface equipment that may be used in the placement
of a
set-delayed cement composition in a wellbore in accordance with certain
embodiments.
[0009] FIG. 28 illustrates the placement of a set-delayed cement composition
into a
wellbore annulus in accordance with certain embodiments.
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DESCRIPTION OF PREFERRED EMBODIMENTS
[0010] Embodiments relate to subterranean cementing operations and, in certain
embodiments, to set-delayed cement compositions and methods of using set-
delayed cement
compositions in subterranean formations. Embodiments comprise lightweight
stabilized set-
delayed cement compositions for use in subterranean formations. Embodiments
may comprise
use synthetic smectites to stabilize the set-delayed cement compositions. The
term set-delayed
is used herein to refer to the composition before and after activation so long
as the composition
prior to activation was characterized by remaining in a pumpable fluid state
for at least about
one day (e.g., at least about 7 days, about 2 weeks, about 2 years or more) at
room temperature
(e.g., about 80 F) in quiescent storage.
[0011] Embodiments of the set-delayed cement compositions may generally
comprise
water, pumice, hydrated lime, synthetic smectites, 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 compositions may be capable of remaining in a pumpable fluid
state for 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 for use in subterranean formations having relatively
low bottom hole
static temperatures, e.g., temperatures less than about 200 F or ranging from
about 100 F to
about 200 F. 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.
[0012] 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 form 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
4
in thc 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.
[0013] 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 lime and water. The pumice may also be ground.
Generally, the pumice may
have any particle size distribution as desired for a particular 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, United 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 25
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, Inc., Malad, Idaho, as
DS325TM 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.
[0014] 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. In 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, slag cement)
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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.
[0015] Embodiments of the set-delayed cement compositions may comprise a
synthetic smectite. Among other reasons, a synthetic smectite may be added to
aid in
stabilization of the set-delayed cement composition, for example, when the set-
delayed cement
composition is lightweight. Synthetic smectites may be aqueous mixtures of
water and
synthetic trioctahedral smectites which are similar to the natural clay
hectorite. In
embodiments, some synthetic smectites are layered hydrous sodium lithium
magnesium
silicates, further, some may be modified with tetrasodiumpyrophosphate. An
example of a
commercially available synthetic smectite is Laponite available from Southern
Clay
Products, Gonzales, Texas. Synthetic smectite may be a platelet-like clay
particle with a
thickness of less than about 100 nm and lateral dimensions of in a range of
about I to about
100 nm. Without being limited by theory, synthetic smectite clay particles may
swell in water
and may produce gels with water at concentrations greater than 0.5%. When
water is added to
a synthetic smectite, it is believed that the synthetic smectite platelets
become ionized and the
rising osmotic pressure in the interstitial fluid may be the cause of the
particle swelling. When
at equilibrium in water, the faces of typical synthetic smectites are
negatively charged while
the edges of the synthetic smectite particles are positively charged. The
polarity of the particles
may be the cause of the rheological alterations in the set-delayed cement
composition. In
embodiments, a synthetic smectite may be added to the set-delayed cement
composition as a
liquid additive or as a dry powder. The synthetic smectite may be added to the
set-delayed
cement compositions as a dry blend or to the set-delayed cement slurry. In
embodiments, the
synthetic smectite may comprise a synthetic smectite with a surface
modification. For
example, pyrophosphate may be used to bind the edges of the synthetic
smectite.
[0016] The synthetic smectite may be included in embodiments of the set-
delayed
cement compositions, for example, to stabilize the set-delayed cement
composition as
additional water is added to create a lightweight set-delayed cement
composition. Where
present, the synthetic smectite 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 water,
for example. In
some embodiments, the synthetic smectite 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%, or
about 5% by
weight of the water.
[0017] 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
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compositions. For example, the set retarder may comprise phosphonic acids,
such as amino
tris(methylene phosphonic acid), ethylenediamine tetra(methylene phosphonic
acid),
diethylenetriamine penta(methylene phosphonic acid), etc.; lignosulfonates,
such as sodium
lignosulfonate, 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 hydroxyl ethyl cellulose (HEC) and carboxymethyl
hydroxyethyl cellulose
(CMHEC); 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 borates, sodium metaborate, 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 in the range of from about 0.01% to about 5% by
weight of the
water. 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%, or
about 5%, by weight of the water. One of ordinary skill in the art, with the
benefit of this
disclosure, will recognize the appropriate amount of the set retarder to
include for a chosen
application.
[0018] 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 dispersants (e.g.,
sulfonated acetone
formaldehyde condensate), examples of which may include Daxad 19 dispersant
available
from Geo Specialty Chemicals, Ambler, Pennsylvania. Other suitable dispersants
may be
polycarboxylated ether dispersants such as Liquiment 5581F and Liquiment
514L
dispersants available from BASF Corporation Houston, Texas; or Ethacryl" G
dispersant
available from Coatex, Genay, France. An additional example of a suitable
commercially
available dispersant is CFe-3 dispersant, available from Halliburton Energy
Services, Inc,
Houston, Texas. The Liquiment 514L dispersant may comprise 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 for 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
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with certain set retarders (e.g., 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.
[0019] 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%, about 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.
[0020] In some embodiments, a viscosifier may be included in the set-delayed
cement
compositions. The viscosifier may be included to optimize fluid rheology and
to stabilize the
suspension. Without limitation, examples of viscosifiers include biopolymers.
An example of
a commercially available viscosifier is SA-101r available from Halliburton
Energy Services,
Inc., Houston, TX. The viscosifier may be included in the set-delayed cement
compositions
in an amount in the range of from about 0.01% to about 0.5% by weight of the
pumice. In
specific embodiments, the viscosifier may be present in an amount ranging
between any of
and/or including any of about 0.01%, about 0.05%, about 0.1%, about 0.2%,
about 0.3%, about
0.4%, or about 0.5% by weight of the pumice. One of ordinary skill in the art,
with the benefit
of this disclosure, will recognize the appropriate amount of viscosifier to
include for a chosen
application.
[0021] 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,
ground rubber tires, polyamide fibers, and polyolefin fibers, among others.
Specific examples
of graphitic carbon fibers include fibers derived from polyacrylonitrile,
rayon, and petroleum
pitch. A commercial example of a mechanical-property-enhancing additive is
Welll,ife 684
additive available from Halliburton Energy Services, Inc. Houston, Texas.
Where used, 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 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
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weight of the pumice. One of ordinary skill in the art, with the benefit of
this disclosure, will
recognize the appropriate amount of the mechanical-property-enhancing
additives to include
for a chosen application.
[0022] 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, mechanical-property-enhancing additives, lost-
circulation materials,
filtration-control additives, fluid-loss-control additives, defoaming agents,
foaming agents,
thixotropic additives, mechanical-property-enhancing additives, polyimines,
and
combinations thereof. In embodiments, one or more of these additives may be
added to the
set-delayed cement compositions after storing but prior to the placement of a
set-delayed
cement composition into a subterranean formation. A person having ordinary
skill in the an,
with the benefit of this disclosure, should readily be able to determine the
type and amount of
additive useful for a particular application and desired result.
[0023] 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. In some embodiments, the set-delayed cement
compositions
may be lightweight. The set-delayed cement composition may be considered
lightweight if it
has a density of about 13 lb/gal or less. In particular embodiments, the set-
delayed cement
composition may have a density from about 8 lb/gal to about 13 lb/gal.
Embodiments of the
set-delayed cement compositions may be foamed or unfoamed or may comprise
other means
to reduce their densities, such as hollow microspheres, low-density elastic
beads, or other
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 recognize the
appropriate density for a
particular application.
[0024] The density of the set-delayed cement compositions may be altered
before
injection into the wellbore. Embodiments of the set-delayed cement
compositions may
comprise a synthetic smectite and water to provide a lightweight composition
that does not
exert excessive force on formations penetrated by the wellbore. Water may be
added to the
slurry in addition to the water already present in the slurry in order to
lower the density of the
slurry further. Alternatively, enough initial water may be added to a dry
blend of a set-delayed
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cement composition to achieve a targeted density while producing the slurry.
Amongst other
reasons, a synthetic smectite may be added to the set-delayed cement
compositions to stabilize
the set-delayed cement compositions should large amounts of water be required
in order to
produce a slurry with a specific density. In particular embodiments, the
synthetic smectite
may be added as a dry powder and/or as a liquid additive (i.e. mixed with
additional water) at
the well site or in the manufacture of the set-delayed cement composition. As
such, the
synthetic smectite, as a dry powder and/or a liquid additive, may be added to
the set-delayed
cement compositions when the set-delayed cement compositions are a dry blend
or when the
set-delayed cement compositions are a slurry. By way of example, a set-delayed
cement slurry
may have a synthetic smectite added immediately prior to use (e.g., as a dry
powder or as a
liquid additive). The amount of synthetic smectite to add to the set-delayed
cement
compositions is dependent upon the amount of additional water needed to
achieve a specific
density. In embodiments, the synthetic smectite may be added to the set-
delayed cement
compositions before, after, or in combination with an activator. Moreover,
additional additives
may be added to the set-delayed cement compositions in combination with the
synthetic
smectite. For example, polyethyleneimine and/or mechanical-property-enhancing
additives
such as carbon fibers may be mixed or blended with the synthetic smectite
liquid additive or
the synthetic smectite dry powder and the resulting combination added to the
set-delayed
cement compositions (i.e. added to either the set-delayed cement composition
dry blend or to
the set-delayed cement slurry). With the benefit of this disclosure, one
having ordinary skill in
the art will be able to choose an amount of a synthetic smectite and water to
add for a specific
application.
[0025] In some embodiments, a liquid additive comprising water and a synthetic
smectite may be added to a set-delayed cement composition to lower the density
of the set-
delayed cement composition. The set-delayed cement composition may comprise
water,
pumice, hydrated lime, and a set retarder. Other additives described herein
may also be
included in the set-delayed cement composition. The set-delayed cement
composition may
have an initial density of from about 13 lb/gal to about 20 lb/gal. By
addition of the liquid
additive, the density of the set-delayed cement composition may be lowered. By
way of
example, a sufficient amount of the liquid additive may be added to lower the
density by about
1 lb/gal or more. In some embodiments, the liquid additive may be used to
lower the density
to about 8 lb/gal to about 13 lb/gal. The synthetic smectite may be included
in the liquid
additive in amount of about 0.01% to about 2% percent by weight.
[0026] As previously mentioned, the set-delayed 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
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I day, about 2 weeks, about 2 years or more) at room temperature (e.g., about
80 F) in
quiescent storage. For example, the set-delayed cement compositions may remain
in a
pumpable fluid state for a period of time from about 1 day to about 7 days or
more. 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 50 days, about 60 days, 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
("Bc"), as
measured on a pressurized consistometer in accordance with the procedure for
determining
cement thickening times set forth in API RP Practice 103-2, Recommended
Practice for
Testing Well Cements, First Edition, July 2005.
[0027] When desired for use, embodiments of the set-delayed cement
compositions
may be activated (e.g., by combination with an activator) to set into a
hardened mass. The
term "cement set activator" or "activator", as used herein, refers to an
additive that activates a
set-delayed or heavily retarded cement composition and may also accelerate the
setting of the
set-delayed, heavily retarded, or other cement composition. By way of example,
embodiments
of the set-delayed cement compositions may be activated 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 form a hardened mass in a time
period ranging
between any of and/or including any of about 1 day, about 2 days, about 4
days, about 6 days,
about 8 days, about 10 days, or about 12 days.
[0028] 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 forces. 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 specified
temperature and
pressure conditions. Compressive strength can be measured by either
destructive or non-
destructive methods. 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 may employ a UCAT" ultrasonic cement analyzer, available
from Farm
Instrument Company, Houston, TX. Compressive strength values may be determined
in
accordance with API RP 10B-2, Recommended Practice for Testing Well Cements,
First
Edition, July 2005.
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[0029] By way of example, the set-delayed cement compositions 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 compositions 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 100 F to 200 F.
[0030] In some embodiments, the set-delayed cement compositions may have
desirable thickening times after activation. Thickening time typically refers
to the time a fluid,
such as a set-delayed cement composition, remains in a fluid state capable of
being pumped.
A number of different laboratory techniques may be used to measure thickening
time. A
pressurized consistometer, operated in accordance with the procedure set forth
in the
aforementioned API RP Practice 10B-2, may be used to measure whether a fluid
is in a
pumpable fluid state. The thickening time may be the time for the treatment
fluid to reach 70
Bc and may be reported as the time to reach 70 Bc. In some embodiments, the
cement
compositions may have a thickening time of greater than about 1 hour,
alternatively, greater
than about 2 hours, alternatively greater than about 5 hours at 3,000 psi and
temperatures in a
range of from about 50 F to about 400 F, alternatively, in a range of from
about 80 F to about
250 F, and alternatively at a temperature of about 140 F.
[0031] 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: zeolites, amines such as triethanolamine, diethanolamine;
silicates such as sodium
silicate; zinc formate; calcium acetate; Groups IA and 11A hydroxides such as
sodium
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 form a
monovalent
cation, such as sodium and potassium salts. Specific examples of suitable
monovalent salts
include potassium sulfate, and sodium sulfate. 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 tetrametaphosphate, sodium
pentametaphosphate, sodium heptametaphosphate, sodium octametaphosphate, and
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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.
[0032] The cement set activator may be added to embodiments of the set-delayed
cement composition in an amount sufficient to induce 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 0.1% 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 and/or including any of about 0.1%, about 1%,
about 5%,
about 10%, about 15%, or about 20% by weight of the pumice. One of ordinary
skill in the art,
with the benefit of this disclosure, will recognize the appropriate amount of
cement set
activator to include for a chosen application.
[0033] 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 comprises water, pumice, hydrated lime, a
synthetic
smectite, a set retarder, and optionally a dispersant, a mechanical-property-
enhancing additive,
or polyethyleneimine. 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 wellbore
drilled into the
subterranean formation, into a near wellbore region surrounding the wellbore,
or into both.
Embodiments may further include activation of the set-delayed cement
composition. The
activation of the set-delayed cement composition may comprise, for example,
the addition of
a cement set activator to the set-delayed cement composition.
[0034] In some embodiments, a set-delayed cement composition may be provided
that
comprises water, pumice, hydrated lime, a synthetic smectite, a set retarder,
and optionally a
dispersant, a mechanical-property-enhancing additive, or polyethyleneimine.
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 1 day or longer. For example, the set-delayed cement
composition may remain
in storage for a time period of about 1 day, about 2 days, about 5 days, about
7 days, about 10
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days, about 20 days, about 30 days, about 40 days, about 50 days, about 60
days, 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 7 days 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.
[0035] 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 wellbore and the walls of a wellbore (and/or a larger conduit in
the wellbore),
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.
[0036] 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
plug an
opening (e.g., a void or crack) 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
microannulus).
[0037] An embodiment comprises a method of cementing in a subterranean
formation
comprising: providing a set-delayed cement composition comprising pumice,
hydrated lime,
a cement set retarder, a synthetic smectite, and water; introducing the set-
delayed cement
composition into a subterranean formation; and allowing the set-delayed cement
composition
to set in the subterranean formation.
[0038] An embodiment comprises a set-delayed cement composition for cementing
in
a subterranean formation comprising: pumice, hydrated lime, a cement set
retarder, a synthetic
smectite, and water.
[0039] An embodiment comprises a set-delayed cementing system for cementing in
a
subterranean formation comprising: a set-delayed cement composition
comprising: water,
pumice, hydrated lime, a synthetic smectite, and a cement set retarder; a
cement set activator
for activating the set-delayed cement composition; mixing equipment for mixing
the set-
delayed cement composition and the cement set activator to produce an
activated set-delayed
cement composition; and pumping equipment for pumping the activated set-
delayed cement
composition into the subterranean formation.
[0040] Referring now to FIG. 1, the preparation of a set-delayed cement
composition
in accordance with example embodiments will now be described. FIG. 1
illustrates a system 2
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for the preparation of a set-delayed cement composition and subsequent
delivery of the
composition 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 apparent to those of
ordinary skill in the
art. In some embodiments, a jet mixer may be used, for example, to
continuously mix the
lime/settable material with the water as it is being pumped to the wellbore.
In set-delayed
embodiments, a re-circulating mixer and/or a batch mixer may be used to mix
the set-delayed
cement composition, and the activator may be added to the mixer as a powder
prior to pumping
the cement composition downhole. In lightweight set-delayed cement
compositions, a
synthetic smectite may be added as a liquid additive mixture with water. This
liquid additive
may be added to the set-delayed cement composition as it is mixed in mixing
equipment 4.
[0041] An example technique for placing a set-delayed cement composition into
a
subterranean formation will now be described with reference to FIGS. 2A and
2B. 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.
[0042] Turning now to FIG. 2B, the set-delayed cement composition 14 may be
placed into a subterranean formation 20 in accordance with example
embodiments. As
illustrated, a wellbore 22 may be drilled into the subterranean formation 20.
While wellbore
22 is shown extending generally vertically into the subterranean 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 wellbores. As
illustrated, the
wellbore 22 comprises walls 24. In the illustrated embodiment, a surface
casing 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 casing, production casing, liners, etc.), shown
here as casing 30
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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 and/or the surface
casing 26. One
or more centralizers 34 may be attached to the casing 30, for example, to
centralize the casing
30 in the wellbore 22 prior to and during the cementing operation.
[0043] With continued reference to FIG. 2B, the set-delayed cement composition
14
may be pumped down 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 casing 30 and up around the casing 30 into the wellbore annulus
32. The set-
delayed cement composition 14 may be allowed to set in the wellbore 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 casing 30.
[0044] 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 (e.g., a mud pit), as shown on FIG. 2A. Referring again to
FIG. 2B, 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 be 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. 2B, 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 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.
[0045] 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, reuse, 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
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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, for
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 casing,
wellbore 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, hydrornechanical 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., electro-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.
[0046] To fticilitate 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 entire scope of the embodiments.
EXAMPLES
Example 1
[0047] The following example describes a set-delayed cement composition
comprising the following components:
Table 1
Compositional Makeup
Component Amount
Pumice 250g
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Lime 50g
Fluid Loss Control Additive 3 g
Synthetic Smectite 3 g
Dispersant 7.1 g
Retarder 6.4 g
Water 301 g
[0048] The synthetic smectite was blended in 301 grams of water at 1000 rpm in
a
Waring Blender for 1 minute. Following this blending step, the dispersant and
the retarder
were added to the synthetic smectite mixture. The mixture was then blended for
another minute
at 1000 rpm. Following this blending step, the pumice, lime, and fluid loss
control additive
were added and blended with the mixture according to API Recommended Practice
for Testing
Well Cements, API Recommended Practice 10B-2. The fluid loss control additive
was
HALAD -344 fluid loss additive available from Halliburton Energy Services,
Inc., Houston,
Texas. The synthetic smectite was Laponite RD available from Southern Clay
Products, Inc.,
Gonzales, Texas. The dispersant was Coatex Ethacryl G dispersant available
from Coatex,
Chester, South Carolina. The cement retarder was Dequest 2006 available from
ltalmatch
Chemicals, Red Bank, New Jersey.
[0049] After preparation, the rheological properties of the sample were
measured
using a Model 35A Fann Viscometer and a No. 2 spring with a Fann Yield Stress
Adapter
(FYSA), in accordance with the procedure set forth in API RP Practice 10B-2,
Recommended
Practice for Testing Well Cements. The results are presented in Table 2 below.
Table 2
Rheological Profile
FYSA Readings (Centipoise)
RPM 3 6 100 200 300
Up Reading 7 10 32 50 69
Down Reading 3 4 29 48
[0050] The slurry remained stable for more than 2 weeks and displayed no free
water
or solids settling. The slurry was activated with 4.0 grams of Na2SO4 and 4.0
grams of sodium
hexametaphosphate. The destructive compressive strength was measured by
allowing the
sample to cure for 24 hours in a 2" by 4" plastic cylinder that was placed in
a water bath at
140 F to form a set cylinder. Immediately after removal from the water bath,
destructive
compressive strengths were determined using a mechanical press in accordance
with API RP
10B-2, Recommended Practice for Testing Well Cements. The sample had a 24 hour
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compressive strength of 121 psi. The reported compressive strengths are an
average for two
cylinders of each sample. The Archimedes Method was used to measure the slurry
density of
the sample in top, middle, and bottom portions. The density was uniform for
all three sections
and was 11.15 pounds per gallon.
Example 2
[0051] The following example describes a set-delayed cement composition
comprising the following components:
Table 3
Compositional Makeup
Component Amount
Pumice 125g
Lime 25 g
Fluid Loss Control Additive 3 g
Synthetic Smectite 3 g
Dispersant 2.7g
Retarder 6.4g
Water 301 g
[0052] The synthetic smectite was blended in 301 grams of water at 1000 rpm in
a
Waring Blender for I minute. Following this blending step, the dispersant and
the retarder
were added to the synthetic smectite mixture. The mixture was then blended for
another minute
at 1000 rpm. Following this blending step, the pumice, lime, and fluid loss
control additive
were added and blended with the mixture in accordance with API RP 10B-2,
Recommended
Practice for Testing Well Cements. The fluid loss control additive was HALAID -
344 fluid
loss additive available from Halliburton Energy Services, Inc., Houston,
Texas. The synthetic
smectite was Laponite RD available from Southern Clay Products, Inc.,
Gonzales, Texas. The
dispersant was Coatex Ethacryl G dispersant available from Coatex, Chester,
South Carolina.
The cement retarder was Dequest 2006 available from Italmatch Chemicals, Red
Bank, New
Jersey.
[0053] After preparation, the rheological properties of the sample were
measured
using a Model 35A Fann Viscometer and a No. 2 spring with a Fann Yield Stress
Adapter
(FYSA), in accordance with the procedure set forth in API RP Practice 10B-2,
Recommended
Practice for Testing Well Cements. The results are presented in Table 4 below.
Table 4
Rheologieal Profile
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FYSA Readings (Centipoise)
RPM 3 6 100 200 300
Up Reading 4 6 14 22 30
Down Reading 2 3 11 19
[0054] The slurry remained stable for more than 2 weeks and displayed no free
water
or solids settling. The Archimedes Method was used to measure the slurry
density of the
sample in top, middle, and bottom portions. The density was uniform for all
three sections and
was 9.45 pounds per gallon.
Example 3
[0055] The following example describes a set-delayed cement composition
comprising the following components:
Table 5
Compositional Makeup
Component Amount
Pumice 500 g
Lime 100 g
Fluid Loss Control Additive 3 g
Dispersant 9.2 g
Retarder 6.4 g
Water 301 g
[0056] The dispersant and the retarder were added to 301 g of water. The
mixture was
then blended for a minute at 1000 rpm in a Waring* Blender. Following this
blending step, the
pumice, lime, and fluid loss control additive were added and blended with the
mixture
according to API RP 10B-2, Recommended Practice for Testing Well Cements. The
fluid loss
control additive was HALADe-344 fluid loss additive available from Halliburton
Energy
Services, Inc., Houston, Texas. The dispersant was Coatex Ethacryl G
dispersant available
from Coatex, Chester, South Carolina. The cement retarder was Dequest 2006
available from
Italmatch Chemicals, Red Bank, New Jersey. The slurry had a density of 13. 2
pounds per
gallon.
[0057] A liquid additive was prepared separate from the slurry comprising 300
g of
water and 7 g of synthetic smectite. The synthetic smectite was Laponite RD
available from
Southern Clay Products, Inc., Gonzales, Texas. The liquid additive was blended
at 1000 rpm
in a Waring Blender for one minute. 200 mL of the 13.2 PPG cement slurry was
added to the liquid
additive. The final density of the slurry was 10.3 PPG.
[0058] After preparation, the rheological properties of the sample were
measured using a
Model 35A Fann Viscometer and a No. 2 spring with a Fann Yield Stress Adapter
(FYSA), in
accordance with the procedure set forth in API RP Practice 10B-2, Recommended
Practice for
Testing Well Cements. The results are presented in Table 6 below.
Table 6
Rheological Profile
FYSA Readings (Centipoise)
RPM 3 6 100 200 300
Up Reading 8 9 11 12 13
Down Reading 6 6 8 10
[0059] The slurry remained stable for more than 2 weeks and displayed
some free water
but no solids settling.
Example 4
[0060] The following example describes a set-delayed cement composition
comprising
the following components:
Table 7
Compositional Makeup
Component Amount
Pumice 500 g
Lime 100 g
Fluid Loss Control Additive 3 g
Dispersant 11.8 g
Retarder 4.2 g
Water 300 g
[0061] The dispersant and the retarder were added to 300 g of water.
The mixture was
then blended for a minute at 1000 rpm in a Waring Blender. Following this
blending step, the
pumice, lime, and fluid loss control additive were added and blended with the
mixture according to
API RP 10B-2, Recommended Practice for Testing Well Cements. The slurry was
left to sit for 24
hours. It displayed no solids settling and was flowable. The fluid loss
control additive was HALAD -
344 fluid loss additive available from Halliburton Energy Services, Inc.,
Houston, Texas. The
dispersant was Coatex XPl7O2TM dispersant available from Coatex,
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Chester, South Carolina. The cement retarder was Dequest 2006 available from
ltalmatch
Chemicals, Red Bank, New Jersey.
[0062] Three individual samples of 300 g each were taken from the cement
slurry and
each sample was mixed with a different liquid additive comprising synthetic
smectite and
water. The liquid additive compositions are described in Table 8 below.
Table 8
Liquid Additive Makeup
Liquid Additive Mixture
Liquid Additive Mixture 1 Liquid Additive Mixture 2
3
Component Amount Component Amount Component Amount
Water 100 g Water 100 g Water 100 g
Synthetic
Synthetic Smectite 1 g Synthetic Smectite 1 g 1 g
Smectite
Polyethyleneimine 1g Polyethyleneimine I g
Viscosifier 0.25 g
Carbon Fibers 3.33 g Carbon Fibers 3.33 g
[0063] The synthetic smectite was Laponite RD available from Southern Clay
Products, Inc., Gonzales, Texas. The carbon fibers were WellLife 684 additive
available from
Halliburton Energy Services, Inc. Houston, Texas. The viscosifier was SA-1015"
available
from Halliburton Energy Services, Inc., Houston, TX. The polyethyleneimine is
a linear
poly(ethyleneimine) with an average molecular weight of 60,000 daltons, it is
available
commercially from Sigma-Aldrich, St. Louis, Missouri. Each liquid additive
mixture was
blended at 1000 rpm in a Waring Blender for one minute.
[0064] Each slurry was allowed to sit for 24 hours. No solids settling or free
water
were observed in any sample. The slurry was activated with 4.0 grams of Na2SO4
(1.3% by
weight of the pumice) and 4.0 grams of sodium hexametaphosphate (1.3% by
weight of the
pumice). The destructive compressive strength was measured by allowing each
sample to cure
for 24 hours in a 2" by 4" plastic cylinder that was placed in a water bath at
140 F to form a
set cylinder. Immediately after removal from the water bath, destructive
compressive strengths
were determined using a mechanical press in accordance with API RP 10B-2,
Recommended
Practice for Testing Well Cements. The reported compressive strengths are an
average for two
cylinders of each sample. The Archimedes Method was used to measure the slurry
density of
the sample in top, middle, and bottom portions. The density was uniform for
all three slurries
and was 11.2 pounds per gallon. Compressive strength data is displayed in
Table 9 below.
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Table 9
Compressive Strength Profile
Liquid Additive Mixture 1 Liquid Additive Mixture 2
Liquid Additive Mixture 3
366 13 psi 430 psi 398 6 psi
17% increase 9% increase
[0065] As illustrated in the table above, the liquid additive mixtures with
the carbon
fibers provided an 11.2 ppg set-delayed cement composition and a 9-17%
increase in 24 hour
compressive strength.
Example 5
[0066] The following example describes a set-delayed cement composition
comprising the following components:
Table 10
Compositional Makeup
Component Amount Unit
Pumice 100 %bwoP
Lime 19.8 %bwoP
Weighting Agent 2.06 %bwoP
Dispersant 1.8 %bwoP
Primary Retarder 0.06 Gal/sk
Secondary Retarder 0.516 %bwoP
Water 64.1 %bwoP
%bwoP = percent by weight of the pumice; Gal/sk = gallons per 46 lb. sack of
pumice
[0067] The mixture was then blended for one minute at 1000 rpm Waring Blender
for 1 minute according to API RP 10B-2, Recommended Practice for Testing Well
Cements.
The weighting agent was MICROMAX weight additive available from Halliburton
Energy
Services, Inc., Houston, Texas. The dispersant was Coatex Ethaeryl G
dispersant available
from Coatex, Chester, South Carolina. The primary cement retarder was Micro
Matrix
Cement Retarder available from Halliburton Energy Services, Inc., Houston,
Texas. The
secondary cement retarder was HR 5 retarder available from Halliburton Energy
Services,
Inc., Houston, Texas.
[0068] After preparation, an experimental sample comprising a liquid additive
was
prepared. The liquid additive comprised synthetic smectite (i.e. Laponite RD
available from
Southern Clay Products, Inc., Gonzales, Texas) and water. 250 g a 1% (by
weight of water)
aqueous synthetic smectite liquid additive was added to 600 g of the cement
slurry described
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WO 2015/085177
PCT/US2014/068804
in Table 10 above. 16.6 g (5.2% by weight of the pumice) of CaC12 was then
added to this
resulting mixture to activate the slurry. The slurry was then blended for 30
seconds at 4000
rpm in a Waring Blender.
[0069] A control sample was then prepared that comprised 600 of the cement
slurry
described in Table 10 above and an additional 250 g of water. No synthetic
smectite was
present in the control sample. 16.6 g (5.2% by weight of the pumice) of CaCl2
was then added
to this resulting mixture to activate the slurry. The slurry was then blended
for 30 seconds at
4000 rpm in a Waring e Blender.
[0070] The experimental sample and the control sample were then placed into 2"
by
4" plastic cylinders that were placed in a water bath at 140 F for one week
to form a set
cylinder. The Archimedes Method was used to measure the slurry density of each
sample in
top, middle, and bottom portions. The densities are described in Table 11
below.
Table 11
Sample Densities
Experimental Sample Control Sample
Top 10.810 Top 9.9086
Middle 10.946 Middle 9.9395
Bottom 10.987 Bottom 10.253
[0071] The control sample had free water and solids settling. The experimental
sample
had no free water and only minimal solids settling was observed.
[0072] It should be understood that the 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. Moreover, the indefinite articles "a" or "an," as used
in the claims, are
defined herein to mean one or more than one of the element that it introduces.
[0073] 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 falling within the range are 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
24
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.
[0074]
Therefore, the present embodiments are well adapted to attain the ends and
advantages mentioned as well as those that are inherent therein. The
particular embodiments
disclosed above are illustrative only, as the present embodiments may be
modified and practiced in
different but equivalent manners apparent to those skilled in the art having
the benefit of the
teachings herein. Although individual embodiments are discussed, all
combinations of each
embodiment are contemplated and covered by the disclosure. 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 present disclosure. 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, the definitions
that are consistent with
this specification should be adopted.
CA 2928213 2017-10-20
