Note: Descriptions are shown in the official language in which they were submitted.
SET-DELAYED CEMENT COMPOSITIONS COMPRISING PUMICE AND
ASSOCIATED METHODS
[0001]
BACKGROUND
[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
an extended period of time (e.g., at least about 1 day to about 2 weeks or
more). 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.
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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 bulk storage and
mixing equipment.
This may be particularly useful for offshore cementing operations where space
onboard the
vessels may be limited.
[0004] In addition to cementing, drilling and fluid displacement are two other
subterranean operations that utilize treatment fluids. Drilling requires the
use of drilling fluid
or as it is also known, drilling mud. Drilling fluids may be used to maintain
hydrostatic
pressure in the wellbore, prevent formation damage, suspend cuttings, and to
transport cuttings
to the surface. Drilling fluids may be water-based or oil-based. Typical water-
based drilling
fluids may be composed of solely water or a mixture of water and various types
of clay. Oil
based drilling fluids typically use a base fluid of a petroleum product.
[0005] Fluid displacement utilizes one or more fluids to displace another
fluid from
the wellbore. Typically this may be done to prevent contamination of one fluid
with another
or the contamination of one fluid with the formation. A displacement fluid or
as it is also
known, a spacer fluid, may be water-based fluids. In most instances, spacer
fluids may be
used to separate drilling fluid from a cement composition during a cementing
operation.
Because the spacer fluid will be used to separate two other fluids, such as
the drilling fluid and
the cement composition, the spacer fluid should be compatible with both
treatment fluids.
[0006] Switching between treatment fluids in a subterranean operation can be
costly
in both time and resources. Varied fluid types may require separate fluid
storage, additional
manpower, and additional equipment. In addition to the increased operating
expenses, varied
fluid use may create additional worksite problems such as higher environmental
burdens, fluid
incompatibilities, and the inability to reuse fluids and materials once their
respective portion
of the operation has been completed.
2
SUMMARY OF THE INVENTION
[0006a] According to a broad aspect of the present invention, there is
provided a
method of drilling a wellbore in a subterranean formation comprising:
circulating a drilling
fluid comprising a set-delayed cement composition in the wellbore while
drilling the
wellbore, wherein the set-delayed cement composition comprises: pumice,
hydrated lime, a
set retarder, and water. In one embodiment, at least a portion of the drilling
fluid is recovered
and used as a spacer fluid. In an additional or alternative embodiment, at
least a portion of
the drilling fluid is recovered and used as a cementing composition. In an
additional or
alternative embodiment, the set-delayed cement composition further comprises a
cement set
activator, and the cement set activator comprises at least one cement set
activator selected
from the group consisting of calcium chloride, triethanolamine, sodium
silicate, zinc
formate, calcium acetate, sodium hydroxide, sodium sulfate, nanosilica, sodium
hexametaphosphate, and any combinations thereof.
[0006b] According to another broad aspect of the present invention, there is
provided
a method of displacing a fluid in a wellbore comprising: introducing a spacer
fluid
comprising a set-delayed cement composition into a wellbore such that the
spacer fluid
displaces one or more prior fluids from the wellbore, and wherein the set-
delayed cement
composition comprises: pumice, hydrated lime, a set retarder, and water. In
one embodiment,
at least a portion of the spacer fluid is recovered and used as a cementing
composition. In an
additional or alternative embodiment, at least a portion of the spacer fluid
is allowed to
remain in the wellbore and allowed to set therein. In an additional or
alternative embodiment,
the set-delayed cement composition further comprises a cement set activator,
and the cement
set activator comprises at least one cement set activator selected from the
group consisting of
calcium chloride, tricthanolamine, sodium silicate, zinc formate, calcium
acetate, sodium
hydroxide, sodium sulfate, nanosilica, sodium hexametaphosphate, and any
combinations
thereof.
10006c] According to yet another broad aspect of the present invention, there
is
provided a system for drilling and cementing in subterranean formation, the
system
comprising: a drilling fluid for use in drilling a wellbore in the
subterranean formation, the
drilling fluid comprising: water; pumice; hydrated lime; and a set retarder; a
set-delayed
cement composition for use in cementing in the wellbore, the set-delayed
cement
composition comprising: water; pumice; hydrated lime; and a set retarder; and
a spacer fluid
for use in separating the drilling fluid and the set-delayed cement
composition in the
wellbore, the spacer fluid comprising: water; pumice; hydrated lime; and a set
retarder. In
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one embodiment, the system further comprises pumping equipment For delivering
at least
one of the drilling fluid, the set-delayed cement composition, or the spacer
fluid to the
wellbore; and an activator for activating at least one of the drilling fluid,
the set-delayed
cement composition, or the spacer fluid.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0007] 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.
[0008] FIG. 1 illustrates a system for drilling a wellbore using a set-delayed
cement
5composition as the drilling fluid in accordance with certain embodiments.
[0009] FIG. 2A illustrates surface equipment that may be used in placement of
a
settable composition in a wellbore in accordance with certain embodiments.
[0010] FIG. 2B illustrates placement of a settable composition into a wellbore
annulus
in accordance with certain embodiments.
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DESCRIPTION OF PREFERRED EMBODIMENTS
[0011] The present embodiments relate to subterranean operations and, more
particularly, in certain embodiments, to set-delayed cement compositions and
methods of
using set-delayed cement compositions in subterranean formations.
[0012] 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. 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 or longer. Advantageously, the
set-delayed
cement compositions may develop reasonable compressive strengths after
activation. The set-
delayed cement compositions may be suitable for a number of subterranean
cementing
operations, including those in subterranean formations having bottom hole
static temperatures
ranging from about 100 F to about 450 F or even greater. In some embodiments,
the set-
delayed cement composition may be used in subterranean formations having
relatively low
bottom hole static temperatures, e.g., temperatures less than about 200 F.
[0013] 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
certain 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
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.
[0014] Embodiments of the set-delayed cement compositions may comprise pumice.
Generally, pumice is a volcanic rock that may exhibit cementitious properties,
in that it may
set and harden in the presence of hydrated lime and water. The pumice may also
be ground,
for example. 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
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d50 values as measured by particle size analyzers such as those manufactured
by Malvem
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
micron, from about
microns to about 100 microns, or from about 10 micron to about 50 microns. In
one
5 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 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 use for a chosen application.
[0015] 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.
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) 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.
[0016] Embodiments of the set-delayed cement compositions may comprise a set
retarder. A broad variety of set retarders may be suitable for use in
embodiments of the set-
delayed cement compositions. For example, the set retarder may comprise
phosphonic acid,
phosphonic acid derivatives, lignosulfonates, salts, organic acids,
carboxymethylated
hydroxyethylated celluloses, synthetic co- or ter-polymers comprising
sulfonate and
carboxylic acid groups, borate compounds, derivatives thereof, or mixtures
thereof.
Examples of suitable set retarders include, among others, phosphonic acid
derivatives
available from Halliburton Energy Services, Houston, TX, as Micro Matrix e
cement retarder.
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Generally, the set retarder may be present in the set-delayed cement
composition 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 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 of the set retarder to include for a chosen application.
[0017] 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 and
polycarboxylated ether
dispersants. One example of a sulfonated-formaldehyde-based dispersant that
may be suitable
is a sulfonated acetone formaldehyde condensate, available from Halliburton
Energy Services,
Houston, TX, as CFR--3 dispersant. One example of polycarboxylated ether
dispersant that
may be suitable is Liquiment 514L dispersant, available from BASF
Corporation, Houston,
Texas, that comprises 36% by weight of the polycarboxylated ether in water.
While a variety
of dispersants may be used in accordance with certain 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 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.
[00181 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.
[0019] 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,
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thixotropic additives, and combinations thereof. In embodiments, one or more
of these
additives may be added to the set-delayed cement composition after 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.
[0020] 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
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.
[0021] As previously mentioned, the set-delayed cement compositions may have a
delayed set in that they remain 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 at a
temperature, for example, about 100 F, 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 at a temperature, for example, about I00 F, for at least
about I 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 high-
temperature high-pressure consistometer at room temperature (e.g., about 80 F)
in accordance
with the procedure for determining cement thickening times set forth in API RP
Practice 10B-
2, Recommended Practice for Testing Well Cements, First Edition, July 2005.
[0022] When desired for use, embodiments of the set-delayed cement
compositions
may be activated (e.g., by combination with a cement set 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 2
hours 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 2 hours, about 4 hours, about 6 hours, about 8 hours, about 10 hours,
or about 12
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hours. After activation, 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. The
compressive strengths may be determined in accordance with API RP 10B-2,
Recommended
Practice for Testing Well Cements, First Edition, July 2005, using an UCA at
140 F while
maintained at 3000 psi.
[0023] Embodiments may include addition of a cement set activator to the set-
delayed
cement compositions. Examples of suitable cement set activators include, but
are not limited
to, calcium chloride, triethanolamine, sodium silicate, zinc formate, calcium
acetate, sodium
hydroxide, a monovalent salt, nanosilica (i.e., silica having a particle size
of less than or equal
to about 100 nanometers), a polyphosphate, and combinations thereof. In some
embodiments,
a combination of the polyphosphate and a monovalent salt may be used for
activation. The
monovalent salt used 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, calcium chloride, 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, for example. Specific examples of polymeric metaphosphate salts that
may be used
include sodium hexametaphosphate, sodium trimetaphosphate, sodium
tetrametaphosphate,
sodium pentametaphosphate, 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.
[0024] The cement set activator should be added to embodiments of the set-
delayed
cement composition in an amount sufficient to activate the extended settable
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 and/or including any of 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
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of this disclosure, will recognize the appropriate amount of the cement set
activator to include
for a chosen application.
[0025] 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 drilling, fluid displacement. and primary and remedial cementing.
Collectively,
these types of operations may use the set-delayed cement composition as a
"treatment fluid."
As used herein, the term "treatment," or -treating- fluid refers to any
subterranean operation
that uses a fluid in conjunction with a desired function and/or for a desired
purpose. The term
-treatment," or "treating," does not imply any particular action by the fluid.
[0026] 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 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, or longer. In
some embodiments, the set-delayed cement composition may remain in storage for
a time
period in a range of from about I 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.
[0027] An embodiment provides a system for drilling and cementing in
subterranean
formation. The system may comprise a drilling fluid for use in drilling a
wellbore in the
subterranean formation, the drilling fluid comprising: water; pumice; hydrated
lime; and a set
retarder. The system further may comprise a set-delayed cement composition for
use in
cementing in the wellbore, the set-delayed cement composition comprising:
water; pumice;
hydrated lime; and a set retarder. The system further may comprise a spacer
fluid for use in
separating the drilling fluid and the set-delayed cement composition in the
wellbore, the spacer
fluid comprising: water; pumice; hydrated lime; and a set retarder.
[0028] In drilling fluid embodiments, a drilling fluid may be used that
comprises the
set-delayed cement composition. For example, the drilling fluid embodiments
comprise the
formulations of the disclosed set-delayed cement composition discussed above.
In
embodiments, the drilling fluid may be comprised entirely of the set-delayed
cement
composition. In embodiments, the disclosed set-delayed cement composition may
be used to
drill a subterranean formation, e.g., by circulating the set-delayed cement
composition while
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drilling a wellbore in contact with a drill bit and a subterranean formation.
An embodiment
may provide a method of drilling a wellbore in a subterranean formation
comprising:
circulating a drilling fluid comprising a set-delayed cement composition in
the wellbore while
drilling the wellbore, wherein the set-delayed cement composition comprises:
pumice,
hydrated lime, a set retarder, and water. In an embodiment, the set-delayed
cement
composition is used to drill a wellbore in a subterranean formation, after
which casing is placed
within the wellbore. In further embodiments, all or a portion of the set-
delayed cement
composition is permitted to set behind the casing.
[0029] The exemplary drilling fluids comprising the set-delayed cement
composition
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 composition. For example, and
with reference to
FIG. 1, the disclosed set-delayed cement composition may directly or
indirectly affect one or
more components or pieces of equipment associated with an exemplary wellbore
drilling
assembly 100, according to one or more embodiments. It should be noted that
while FIG. 1
generally depicts a land-based drilling assembly, those skilled in the art
will readily recognize
that the principles described herein are equally applicable to subsea drilling
operations that
employ floating or sea-based platforms and rigs, without departing from the
scope of the
disclosure.
[0030] As illustrated, the drilling assembly 100 may include a drilling
platform 102
that supports a derrick 104 having a traveling block 106 for raising and
lowering a drill string
108. The drill string 108 may include, but is not limited to, drill pipe and
coiled tubing, as
generally known to those skilled in the art. A kelly 110 supports the drill
string 108 as it is
lowered through a rotary table 112. A drill bit 114 is attached to the distal
end of the drill
string 108 and is driven either by a downhole motor and/or via rotation of the
drill string 108
from the well surface. As the bit 114 rotates, it creates a borehole 116 that
penetrates various
subterranean formations 118.
[0031] A pump 120 (e.g., a mud pump) circulates drilling fluid 122 comprising
the
set-delayed cement composition, through a feed pipe 124 and to the kelly 110,
which conveys
the drilling fluid 122 downhole through the interior of the drill string 108
and through one or
more orifices in the drill bit 114. The drilling fluid 122 is then circulated
back to the surface
via an annulus 126 defined between the drill string 108 and the walls of the
borehole 116. At
the surface, the recirculated or spent drilling fluid 122 exits the annulus
126 and may be
conveyed to one or more fluid processing unit(s) 128 via an interconnecting
flow line 130.
After passing through the fluid processing unit(s) 128, a "cleaned" drilling
fluid 122 is
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deposited into a nearby retention pit 132 (i.e, a mud pit). While illustrated
as being arranged
at the outlet of the wellbore 116 via the annulus 126, those skilled in the
art will readily
appreciate that the fluid processing unit(s) 128 may be arranged at any other
location in the
drilling assembly 100 to facilitate its proper function, without departing
from the scope of the
scope of the disclosure.
[0032] In embodiments, the drilling fluid 122 comprising the set-delayed
cement
composition may be added to a mixing hopper 134 communicably coupled to or
otherwise in
fluid communication with the retention pit 132. The mixing hopper 134 may
include, but is
not limited to, mixers and related mixing equipment known to those skilled in
the art. In
alternative embodiments, however, the drilling fluid 122 comprising the set-
delayed cement
composition may not be added to a mixing hopper. In at least one embodiment,
for example,
there could be more than one retention pit 132, such as multiple retention
pits 132 in series.
Moreover, the retention put 132 may be representative of one or more fluid
storage facilities
and/or units where the disclosed set-delayed cement composition may be stored,
reconditioned, and/or regulated until used as drilling fluid 122.
[0033] As mentioned above, the disclosed drilling fluids comprising the set-
delayed
cement composition may directly or indirectly affect the components and
equipment of the
drilling assembly 100. For example, the disclosed set-delayed cement
composition may
directly or indirectly affect the fluid processing unit(s) 128 which may
include, but is not
limited to, one or more of a shaker (e.g., shale shaker), a centrifuge, a
hydrocyclone, a separator
(including magnetic and electrical separators), a desilter, a desander, a
separator, a filter (e.g.,
diatomaceous earth filters), a heat exchanger, any fluid reclamation
equipment. The fluid
processing unit(s) 128 may further include one or more sensors, gauges, pumps,
compressors,
and the like used store, monitor, regulate, and/or recondition the exemplary
set-delayed cement
composition.
[0034] The disclosed set-delayed cement composition may directly or indirectly
affect
the pump 120, which representatively includes any conduits, pipelines, trucks,
tubulars, and/or
pipes used to fluidically convey the set-delayed cement compositions downhole,
any pumps,
compressors, or motors (e.g., topside or downhole) used to drive the set-
delayed cement
composition into motion, any valves or related joints used to regulate the
pressure or flow rate
of the set-delayed cement composition, and any sensors (i.e., pressure,
temperature, flow rate,
etc.), gauges, and/or combinations thereof, and the like. The disclosed set-
delayed cement
composition may also directly or indirectly affect the mixing hopper 134 and
the retention pit
132 and their assorted variations.
11
[0035] The disclosed drilling fluids comprising the set-delayed cement
composition
may also directly or indirectly affect the various downhole equipment and
tools that may come
into contact with the set-delayed cement composition such as, but not limited
to, the drill
string 108, any floats, drill collars, mud motors, downhole motors and/or
pumps associated
with the drill string 108, and any measrurement while drilling/logging while
drilling
("MWD/LWD") tools and related telemetry equipment, sensors or distributed
sensors
associated with the drill string 108. The disclosed set-delayed cement
composition may also
directly or indirectly affect any downhole heat exchangers, valves and
corresponding actuation
devices, tool seals, packers and other wellbore isolation devices or
components, and the like
associated with the wellbore 116. The disclosed set-delayed cement composition
may also
directly or indirectly affect the drill bit 114, which may include, but is not
limited to, roller
cone bits. PDC bits, natural diamond bits, any hole openers, reamers, coring
bits, etc.
[0036] While not specifically illustrated herein, the disclosed drilling
fluids
comprising the set-delayed cement compositions may also directly or indirectly
affect any
transport or delivery equipment used to convey the set-delayed cement
composition to the
drilling assembly 100 such as, for example, any transport vessels, conduits,
pipelines, trucks,
tubulars, and/or pipes used to fluidically move the set-delayed cement
composition from one
location to another, any pumps, compressors, or motors used to drive the set-
delayed cement
composition into motion, any valves or related joints used to regulate the
pressure or flow rate
of the set-delayed cement composition, and any sensors (i.e., pressure and
temperature),
gauges, and/or combinations thereof, and the like.
[0037] In displacement fluid embodiments, the set-delayed cement composition
may
be used as a displacement or spacer fluid. The displacement fluid embodiments
comprise the
formulations of the disclosed set-delayed cement composition discussed above.
In
embodiments, the displacement or spacer fluid may be comprised entirely of the
set-delayed
cement composition. In embodiments, the disclosed set-delayed cement
composition may be
used to displace a drilling mud or other treatment fluid, e.g., by circulating
the set-delayed
cement composition back to the surface via the annulus between the drill
string and the walls
of the borehole. As the spacer fluid is circulated back to the surface, it
displaces any prior
placed fluids remaining in the wellbore. An embodiment provides a method of
displacing a
fluid in a wellbore comprising: introducing a spacer fluid comprising a set-
delayed cement
composition into a wellbore such that the spacer fluid displaces one or more
prior fluids from
the wellbore, and wherein the set-delayed cement composition comprises:
pumice, hydrated
lime, a set retarder, and water. In an embodiment, the set-delayed cement
composition is used
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to displace a treatment fluid in a subterranean formation. In this embodiment,
the set-delayed
cement composition is permitted to set behind the casing.
[0038] In additional displacement fluid embodiments, the density of the set-
delayed
cement composition may be adjusted by the addition of water and/or
viscosifier, for example.
The water and viscosifiers may be added in any amount to achieve the
appropriate density for
a rheological hierarchy for a given application. An example of a suitable
viscosifier is SA-
1015" suspending agent available from Halliburton Energy Services, Houston,
TX.
Additionally, light weight and heavy weight agents may also be added to adjust
the density as
is appropriate to maintain the rheological hierarchy. One of ordinary skill in
the art, with the
benefit of this disclosure, will recognize the appropriate density and method
of density
adjustment necessary for a chosen application.
[0039] Displacement fluid embodiments may also be foamed with a foaming
additive
and/or a gas, for example, to provide a set-delayed cement composition with a
reduced density.
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. Examples of suitable foaming additives include, but are not limited
to: mixtures of
an ammonium salt of an alkyl ether sulfate, a cocoamidopropyl betaine
surfactant, a
cocoamidopropyl dimethylamine oxide surfactant, sodium chloride, and water;
mixtures of an
ammonium salt of an alkyl ether sulfate surfactant, a cocoamidopropyl
hydroxysultaine
surfactant, a cocoamidopropyl dimethylamine oxide surfactant, sodium chloride,
and water;
hydrolyzed keratin; mixtures of an ethoxylated alcohol ether sulfate
surfactant, an alkyl or
alkene amidopropyl betaine surfactant, and an alkyl or alkene dimethylamine
oxide surfactant;
aqueous solutions of an alpha-olefinic sulfonate surfactant and a betaine
surfactant; and
combinations thereof. An example of a suitable foaming additive is
ZONESEALANTTh 2000
agent, available from Halliburton Energy Services, Houston, TX.
[0040] As will be appreciated by those of ordinary skill in the art,
embodiments of the
set-delayed cement compositions of the present invention may be used in a
variety of
cementing operations, including primary and remedial cementing. 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
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
13
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, addition of a cement set activator to the set-delayed cement
composition.
[0041] In primary cementing embodiments, for example, embodiments of the set-
delayed cement composition may be introduced into a space between a wall of a
wellbore and
a conduit (e.g., pipe strings, liners) located in the wellbore, the wellbore
penetrating the
subterranean formation. The set-delayed cement composition may be allowed to
set to form
an annular sheath of hardened cement in the space between the wellbore wall
and the conduit.
Among other things, the set cement composition may form a barrier, preventing
the migration
of fluids in the wellbore. The set cement composition also may, for example,
support the
conduit in the wellbore.
[0042] 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,
such as a void or crack, in the formation, in a gravel pack, in the conduit,
in the cement sheath,
and/or a microannulus between the cement sheath and the conduit.
[0043] 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 210 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 210 may include a cementing unit 212, which
may include
one or more cement trucks. The cementing unit 212 may include mixing equipment
204 and
pumping equipment 206 as will be apparent to those of' ordinary skill in the
art. The cementing
unit 212 may pump a set-delayed cement composition 214 through a feed pipe 216
and to a
cementing head 218 which conveys the set-delayed cement composition 214
downhole.
[0044] Turning now to FIG. 2B, the set-delayed cement composition 214 may be
placed into a subterranean formation 220 in accordance with example
embodiments. As
illustrated, a wellbore 222 may be drilled into the subterranean formation
220. While wellbore
222 is shown extending generally vertically into the subterranean formation
220, the
principles described herein are also applicable to wellbores that extend at an
angle through the
subterranean formation 220, such as horizontal and slanted wellbores. As
illustrated, the
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wellbore 222 comprises walls 224. In the illustrated embodiment, a surface
casing 226 has
been inserted into the wellbore 222. The surface casing 226 may be cemented to
the walls 224
of the wellbore 222 by cement sheath 228. In the illustrated embodiment, one
or more
additional conduits (e.g., intermediate casing, production casing, liners,
etc.), shown here as
casing 230 may also be disposed in the wellbore 222. As illustrated, there is
a wellbore annulus
232 formed between the casing 230 and the walls 224 of the wellbore 222 and/or
the surface
casing 226. One or more centralizers 234 may be attached to the casing 230,
for example, to
centralize the casing 230 in the wellbore 222 prior to and during the
cementing operation.
[0045] With continued reference to FIG. 2B, the set-delayed cement composition
214
may be pumped down the interior of the casing 230. The set-delayed cement
composition 214
may be allowed to flow down the interior of the casing 230 through the casing
shoe 242 at the
bottom of the casing 230 and up around the casing 230 into the wellbore
annulus 232. The set-
delayed cement composition 214 may be allowed to set in the wellbore annulus
232, for
example, to form a cement sheath that supports and positions the casing 230 in
the wellbore
222. While not illustrated, other techniques may also be utilized for
introduction of the set-
delayed cement composition 214. By way of example, reverse circulation
techniques may be
used that include introducing the set-delayed cement composition 214 into the
subterranean
formation 220 by way of the wellbore annulus 232 instead of through the casing
230.
[0046] As it is introduced, the set-delayed cement composition 214 may
displace other
fluids 236, such as drilling fluids and/or spacer fluids that may be present
in the interior of the
casing 230 and/or the wellbore annulus 232. At least a portion of the
displaced fluids 236 may
exit the wellbore annulus 232 via a flow line 238 and be deposited, for
example, in one or
more retention pits 240 (e.g., a mud pit), as shown on FIG. 2A. Referring
again to FIG. 2B, a
bottom plug 244 may be introduced into the wellbore 222 ahead of the set-
delayed cement
composition 214, for example, to separate the set-delayed cement composition
214 from the
fluids 236 that may be inside the casing 230 prior to cementing. After the
bottom plug 244
reaches the landing collar 246, a diaphragm or other suitable device rupture
to allow the set-
delayed cement composition 214 through the bottom plug 244. In FIG. 2B, the
bottom plug
244 is shown on the landing collar 246. In the illustrated embodiment, a top
plug 248 may be
introduced into the wellbore 222 behind the set-delayed cement composition
214. The top plug
248 may separate the set-delayed cement composition 214 from a displacement
fluid-250 and
also push the set-delayed cement composition 214 through the bottom plug 244.
In some
embodiments, the displacement fluid 250 may comprise a set-delayed cement
composition. In
further embodiments, a displacement fluid 250 comprising a set-delayed cement
composition,
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may comprise a set-delayed cement composition separate from the set-delayed
cement
composition 214.
[0047] In embodiments the set-delayed cement composition may be used for
different
subterranean operations. In embodiments, the set-delayed cement composition
may be used
for one or more subterranean operations at a specific worksite. As discussed
above, the set-
delayed cement composition may serve as a treatment fluid for these different
subterranean
operations. In embodiments, the set-delayed cement composition may be used as
a drilling
fluid and also used as a spacer fluid. In other embodiments, the set-delayed
cement
composition may be used as a spacer fluid and as a cementing composition. In
other
embodiments, the set-delayed cement composition may be used as a drilling
fluid and a
cementing composition. In still other embodiments, the set-delayed cement
composition may
be used as a drilling fluid, a spacer fluid, and a cementing composition. In
embodiments, the
set-delayed cement composition may be reused or recirculated in the wellbore
for the same or
a different operation. As an example, at least a portion of the set-delayed
cement composition
used as a drilling fluid may be removed and then later reintroduced as a
displacement fluid
and/or a cementing composition in the subterranean formation. As another
example, at least a
portion of the set-delayed cement composition used a displacement fluid may be
removed and
then later reintroduced as a cementing composition in the subterranean
formation. The
reusability of the set-delayed cement composition as any type of treatment
fluid allows for the
recycling of treatment fluids. Furthermore, this process reduces the amount of
equipment and
manpower needed between operations in regards to transitioning between
operations, fluid
handling, and fluid storage. Lastly, because the treatment fluids may be the
same for each
operation there may no longer be compatibility issues between treatment
fluids.
[0048] The exemplary set-delayed cement composition 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 composition. For example, the disclosed set-delayed cement composition
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 composition. The disclosed set-delayed cement composition may also
directly or
indirectly affect any transport or delivery equipment used to convey the set-
delayed cement
composition 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
composition from one location to another, any pumps, compressors, or motors
(e.g., topside
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or downhole) used to drive the set-delayed cement composition into motion, any
valves or
related joints used to regulate the pressure or flow rate of the set-delayed
cement composition,
and any sensors (i.e., pressure and temperature), gauges, and/or combinations
thereof, and the
like. The disclosed set-delayed cement composition may also directly or
indirectly affect the
various downhole equipment and tools that may come into contact with the set-
delayed cement
composition 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,
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 (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.
[0049] 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 entire scope of the embodiments.
EXAMPLE 1
[0050] Sample set-delayed cement compositions were prepared that varied in the
temperature and presence of activator. All other variables were kept constant.
The samples
comprised 2000 grams of pumice (DS-325 lightweight aggregate), 400 grams of
hydrated
lime, 12.0 grams of Liquiment 514L dispersant, 25 grams of Micro Matrix
cement retarder,
and 1300 grams of water. The temperature was held constant at 200 F, 140 F,
or 100 F. A
set-delayed cement activator was added to one sample in each temperature
group. The amount
of the activator added was 5% of the combined weight of the pumice and lime,
Calcium
chloride was used as the activator for the 200 F and 140 F samples. Sodium
hydroxide was
used as the activator for the 100 F sample. The + sign next to the initial
set time data indicates
that the test was stopped at that time with the slurry having not reached the
conditions for
initial setting. The initial set time was determined by placement of a sample
into an Ultrasonic
Cement Analyzer, available from Fann Instrument Company, Houston, Texas, while
maintained at the indicated temperature and 3000 psi. The initial set time was
determined in
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accordance with API RP Practice 10B-2, Recommended Practice for Testing Well
Cements by
recording the time for the sample to reach a compressive strength of 50 psi.
The results of this
test are set forth in Table 1 below.
TABLE 1
Delayed-Set Behavior as a Function of Temperature
CaC12' or Na0Hb (%0
Temperature ( F) bwo[P+1.]) Initial Set Time (hr:min)
200 0 72:00+
200 5' 4:23
140 0 94:00+
140 5' 7:49
100 0 72:00+
100 5b 2:51
[0051] Example 1 thus indicates that the set-delayed cement composition is
sufficiently retarded and exists in a stable pumpable state for use as a
circulatable treatment
fluid. The data also shows that the set-delayed cement composition also
remains capable of
setting quickly if a suitable activator is used.
EXAMPLE 2
[0052] Sample set-delayed cement compositions were prepared. The samples
comprised 2000 grams of pumice (DS-325 lightweight aggregate), 4000 grams of
hydrated
lime, 12 grams of Liquiment 514L dispersant, 25 grams of Micro Matrix cement
retarder,
and 1300 grams of water. The temperature was held constant at room
temperature. A Farm
Yield Stress Adapter was used with a standard Fann model 35 viscometer.
Measurements were
taken at RPMs of 600, 300, 200, 100, 60, and 30. The slurries were aged to 8,
14, and 26 days.
A viscosity measurement was taken at the time of slurry preparation. This
measurement is
represented in Table 2 as 0 under the Age of Slurry column. All results are
measured in
centipoise. The results of this test are set forth in Table 2 below.
TABLE 2
Rheology of the Set-Delayed Cement Compositions over Time
Fann Readings
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Age of
600 RPM 300 RPM 200 RPM 100 RPM 60 RPM 30 RPM
Slurry
(Days)
0 663 cP 600 cP 607 cP 520 cP 534 cP 534 cP
8 587 cP 476 cP 427 cP 373 cP 356 cP 356 cP
14 605 cP 520 cP 460 cP 413 cP 378 cP 356 cP
26 605 cP 480 cP 413 cP 347 cP 322 cP 311 cP
[0053] Example 2 thus indicates that the set-delayed cement composition shows
lower
viscosities than at the time of preparation, however, there is little
difference in the viscosities
of the slurry over time as shown by comparison of the 8 day and 26 day data
sets.
[0054] 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.
[0055] 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
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.
[0056] Therefore, the present invention is 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 invention may be
modified and practiced
in different but equivalent manners apparent to those skilled in the art
having the benefit of the
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teachings herein. Although individual embodiments are discussed, the invention
covers all
combinations of all those embodiments. Furthermore, no limitations are
intended to the details
of construction or design herein shown, other than as described in the claims
below. Also, the
terms in the claims have their plain, ordinary 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 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
incorporated herein by reference, the definitions that are consistent with
this specification
should be adopted.
