Note: Descriptions are shown in the official language in which they were submitted.
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MITIGATION ()F CONTAMINATIM EFFECTS IN SET-DELAYED -CEMENT
COMPOSITIONS COMPRISING PUMWE AND HYDRATED LIME
BACKGROUND
[0(I01j 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
tubularsõ 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 ceinenting mthod, 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 !brining an annular
sheath of
hardened, substantially impermeable tetTleRt (i.e., a cement sheath) that may
support and
posit* the pipe string in the wellbore and bond the exterior surface -of the
pipe string to the
subterranean formation. -Among other things, the cement sheath surrotmding the
pipe string
functions to prevent the migration of fluids in the annulns and to protect the
pipe string from
corrosion. Cement compositions also may be used in remedial cementing methods
to, for
example, seal cracks or- holes in pipe strings or cement sheaths, seal highly
permeable
formation zones or fractures, place cement plugsõ and the like.
100021 .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 their ability to remain
in a. pumpable
fluid state fir at least about one day (e.g., about 7 days, about 2 weeks,
about 2 years or
more) at room temperature (i.e., about SWF) in quiescent storage. When desired
tbr use, the
set-delayed cement compositions may be capable of activation whereby
reasonable
compressive strengths may be 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, ibr example, where it is desired to prepare the cement
composition in advance.
This may allow for the cement composition to be stored prior to its use. In
addition, this
may allow for the cement composition to be prepared at a convenient location
betbre -being
3(1 transported to the job site. .Accordingly, capital and operational
expenditures may be
reduced due to a reduction in the need for on-site bulk storage and -mixing
equipment.
Advantageously, this may be particularly useful for offshore cementing
operations where
space onboard the vessels may be limited.
[0003] While set-delayed cement compositions have been developed before,
challenges exist with their successful use in subterranean cementing
operations. For
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example, set-delayed cement compositions prepared with Portland cement may
have
undesired gelation issues which may 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 have limited use at lower
temperatures as they
may not develop sufficient compressive strength when Eised in subterranean
formations
having lower bottom hole static temperatures.
[0004I The large-scale manufactum of set-delayed cement compositions may
present
additional challenges. Large batch mixers or transport trucks used during the
manufitcturina
process of' the set-delayed cement compositions may contaminate the set-
delayed cement
compositions with residual cementitious matter front previous manutacturing
operations.
The cementitious contaminants may reduce the effectiveness of the tandem or
aetivators
used with the set-delayed cernent compositions. The cent ntitious contaminants
may even
render du.; se-delayed cement compositions unusable. Thorough cleaning of the
mixers
before transitioning to a new cement composition may be expensive and decrease
manufacturing efficiency% Furthermore the use of cleaning agents (e.g., silica
sand) may be
inetTeetiVe
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1IREF DESCRIPTION OF THE DRAWINGS
10005] These drawings illustrate certain aspeets of sonie of the embodiments
of the
present method, and should not be uSed to limit or define the method.
[0006] 'Fla illustrates a system :kir preparation an delivery of a
set-delayed
cement composition to a wellbom in accordance with- Certain embodiments.
10007] :FIG. 2A illustrates surtlice equipment that may be used in placement
of a set-
de14ed canon eottipoition in a wellbore inAi.t:ixIttlatk:e with certain
ertibodiments.
[0008] Fla 2B illustrates placement of a set-delayed cement compsition into a
wellbore annulus in accordance with certain embodiments:
I 0
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DESCRIPTION OF PREFERRED EMBODIMENTS
100091 The present ernh(xliments relate to subterranean cementing operations
and,
more particularly, in certain embodiments, to set -delayed Cement compositions
and inethods
fusing set-delayed cement compositions in subterranean formations.
[00101 Embodiments of the set-delayed'cement compositions may generally
comprise water, pumice, hydrated lime, and a primary set retarder. Optionally,
the set-
delayed cement compositions may further comprise a. dispersant.
Advantageously,
embodithents of the set-delayed cement compositions tm 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 for at least about 1 day or longer (e.g.,
about 2 years or
long,er). Advantageously,. the Set-delayed cement compositiOns may develop
reasonable
compressive strengths after activation at relatively low temperatures. While
the set-delayed
cement composition's May be Suitable for a number of subterranean cementing
operations,
they :may be particularly suitable for use in subterranean formations having
relatively low
bottont hole static temperatures, eg., temperatures less titan about 200F or
ranging from
about 100`17 to about 200T. In alternative embodiments, the set-delayed -
cement
cOmpesitions may be Used in subterranean lOrmations having bottom hole static
temperatures
up to 450T- or higher.
100111 The water use.d in embodiments of -04.7 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 sah water. Salt
water
generally may include one or more. dissolved salts therein and may be
saturated or
unsaturated as desired frir a- particular application. Seawater or brines may
be suitable for
use in embodiments. I:nether, the water may be pftsent in an amount sufficient
to form a
pumpable 8Iurry. In certain embodiments, the Watet may be present in the set-
delayed
cement compositions in an amount in the range of from about 33% to :about 200%
by weight
of the pumice. In certain etnbodiments, the water may be present in the set-
delayed cethent
compositions in an amount in the range of from about 35% to about 70% by
weight of the
pumice. OW of ordinary skill in the art with the ix,nefit of this disclosure
will recognize the
appropriate amount of water to use for a chosen application.
[00121 Embodiments (tithe set-delayed cement compositions may comprise
'pumice.
Generally, pamiee is a volcanic rock that ctm exhibit cementitiOus properties
in that it May
set and harden in the presence of hydrated lime and water. The pumice may be
ground or
um...!round. Generally, the pumice may have any particle size distribution as
desired for a
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paaicular application. In certain embodiments, the pumice may have a mean
particle size in a
range of from about 1 micron to about 200 microns. 'I' he 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, isrom
about 5 microns to about 100- microns, or :from about 10 -microns to about 50
microns. In one
particular enthodiment, the pumice may have a mean particle sin of less than
about 15
microns. An example of a suitable pumice is IDS7:.325 lightweight aggregate,
available from
Has Putnice PrOducts, inc., Malad, Idaho. 1)5-325 aggregate has a particle
size of less than
about 15 microns. It. should be appreciated that particle sizes to small may
have mixability
probleins while particle sizes too large may nOt he effectively suspended in
the
compositions. One of ordinary skill in the art, with the benefit of this
disclosure, should be
-able to select a puruiee with a particle size suitable for a chosen
application,
[00131 Embodiments of the set-delayed cement compositions may comprise
hydrated lime. As used herein, the term "hydrated lune will be understood to
Mall calcium
hydroxide. in some etribodiments, 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
exatnple, to
limn a hydraulic composition with the pumice. For example, the hydrated. lime
may be
included in a putnice-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 1(X)% by
weitilit of the
pumice. Ibr example. In SOIlle eMbOdiMenN, the hydrated lime may he present in
an amount
ranging between any of andlor including any of about 10%, about 20%, about
zIOVN about
60%, about 80%, or about 100% by weight of the pumice, in some ethbodiments,
the
eethentitiouS components, present in the set-delayed cement composition may
consist
essentially oldie pumice and the hydrated lime. For example., the cementitious
components
may primarily comprise the pumice HO the hydrated lime without, any additional
components (e.g., Portland cement, 'fly asb, slag cement) that hydraulically
set in the
presence: Of Water. Otte of ordinary skill in the art, with the benefit of
this diselostire, will
recognize the appropriate amount of hydrated lime to include for a chosen
application,
[0014) Embodiments of the set-delayed cement compositions may comprise a
primary set retarder: A broad variety of primary set retarders may be
suitable, for use in the
set-dolayed cement compositions. For example, the primary set retarders may
comprise
phosphonic acids, such as ethylenediamine tetra(Methylene phosphonie acid),
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diethylenetriamine penta(thethylene Phosphonic acid), etc.; phosphonic acid
derivatives;
lignosulfonates, suCh as sodium 4,,nosultbnate, calcium lignosulfonate, etc.;
salts such as
stannous sulfate, lead acetate, monobasic calcium Phosphate: organic acids
such as citric
acid, tartaric acid, etc:, cellulOse derivkives such as hydroxyl ethyl
cellulose MEC) and
earboxymethyl hydroxyeth,y1 cellulose (CMHEC); synthetic co- r.a- ter-polymers
comprising
suifonate and carboxylic acid groups such as su1fonate4unctiona1ized
acrylamide-acrylic
acid co-polymers; borate e.ompounds such as alkali borates, Sodium metaborate,
sodium
tetraborate, potassium pentabOnte; derivatives thereof or mixtures thereof.
One example of
a suitable commercial primary set retarder is Micro Matrix'''. cement
retarder, available frOm
Halliburton Energy Services, Inc., Houston, Texas. Generally, the primary :set
retarder may
be present in the set7delayed cement coMpositions in an amount sufficient to
delay seAting
for a desired time. :In some embodiments, the primary 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 primary set rcAarder may
be present
in AO amount ranging between any of 'and/or including, any of about f>01%.,
about 0.1%,
about 1%õ about 2%, about 4%, about 6%, about 8%, or about 10% by weight of
the pumice.
(Mc of ordinary skill in the art, with the benefit of this disclosure, will
recognize the
appropriate amount of primary set retarder to include for a chosen
application.
[0015] As discussed above, an issue with the manufacture of set-delayed
centent
corripositions is the potential for cementitions Contamination at the bulk
plant or during
transport. Cementitious contamination, as defined herein, refers to the
,contamination of a
set-delayed cement composition ..Vith tiny material that is not an intended
component of the
set-delayed ce.ment composition; said material being unintentionally added,
directly or
indirectly, to the se-delayed cement composition; %viterein said material is
cementitious iti
and of itself, becomes cementitious upon the unintended contact with the set-
delayed cement
composition, andlor promotes or induces early setting, gelling. Or any other
type of
:cementitious reaction in the set-delayed cement composition. Typically.
cementitious
contamination may be mitigated. by cleaning the bulk plant machinery or the
transport trucks.
However, this procedure may be costly andfor ineffective. Supplementing the
set-delayed
cement coMpesitions with additional cement retarders may be A low cost and
more effective
alternative to the typical cementitious contamination cleanup methods.
AdvantageoWy, the
use of multiple retarders may provide superior mechanical properties as
compared to using a
higher coneentration of a single retarder. For example, using a high
concentration of a single
retarder may cause the set-delayed cement composition slurry to thicken. This
thickening
effect may cause field handling And pumpability issues.
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[00161 Embodiments of the set-delayed cement compositions may additionally
comprise one or more secondary set retarders in addition to the primary set
retarder. 'The
secondary set retarders may be .used to mitigate the effect of cementitious
contaminants
residual :manufacturing contaminants) on the set-delayed cement compositions.
Cementitious
contaminants, as defined herein,- referS to any material that is not an
intended component of
the set-delayed cement. composition; said material being unintentionally
added, directly or
indirectly, to the set-delayed cement composition;. wherein said material is
cemerititious in
and of itself, becomes cementitious upon the unintended contact with the
setclelayed cement
composition, and/or promotes or induces early setting, gelling, Or any other
type of
cementitious reaction in the set-delayed cement composition. Without
limitation, examples
of ccmentitious contaminants include the nnintended addition of 'hydraulic
cements such as
Portland cement, calcium illuminate cement, etc.; pozzolanic material such as
fly ash, etc.;
slag; cement kiln dust; plasters such as gypsum plasters, lime, plasterS,
cernent plaster, etc.;
materials that promote or induce cemernitious reactions; and any combination
thereof
Cementitious contarninants may have an adverse effect on the properties of the
set-delayed
cement compositions. Embodiments of the Set-delayed cement compositions
comprising
secondary set retarders -may also comprise cementhious contaminants that were
Unintentionally added to the set-delayed -ccirient composition.
[00171 A broad variety of secondary set retarders :may be suitable for use in
the set,
delayed cement compositions. The secondary set retarder May be chemically
different from
the primary set. retarder; alternatively the secondary set retarder niay be
chemically similar to
the primary .set retarder. For example, the seeondary set retarders may
comprise phosphonic
acids, such as ethylenediamine tetTa(inethylene phosphonic
diethylenetriarnine
penta(tnethylene phosphonic acid), etc.; phosphonic acid derivatives;
lignosulfonates, such
as sodium lignostilfonate, calcium lignosulfonate, etc.; salts such as
stannous sulfate, lead
acetate, monobasic 'caleium phosphate; organic acids such as citric add,
tartaric acid, ete;
cellulose derivatives .such :as hydroxyl ethyl cellulose (iEC) and
carboxymethyl
hydroxyethyl celltilose (CMHEC); synthetic en- or ter-polymersõ comprising
sulfonate and
carboxylic acid groups such as .sulfonate-ftinctionalized acrylamide-acrOic
acid co-
polymers; boratt.,, compounds Such as :alkali borates, sodium metaborate,
sodium tetraborate,
potassium pentaborate; derivatives thereof or mixtures thereof One example of
a suitable
commercial secondary set retarder is 'Micro Matrie cement retarder, available
from
lialliburton Energy Services, Inc., Houston, Texas. Generally, the secondary
set retarder
may be present in the set-delayed cement compositions in an amount sufficient
to delay
setting for a desired time. In some embodiments, the secondary set retarder
may be present
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the set-delayed cement compoons in an amount in the !love of from about 0.01%
to
about 10% by weight of the punkt. In specific embodiments, the secondary set
retarder
may be present in an amount ranging between any of and/or including any of
about 0.01%,
about abott 1%, t.tbottt 2%, about 4%, about tS(.'/=i,, about 8%, or
about 18% by weight of
the pumice. One of ordinary skill in the art, with the benefit of this
disclosure, will
recognize the appropriate amount of secondary set retarder to include for a
chosen
application.
100181 As previously mentioned, embodiments of the set-delayed cement
compositions may optionally coinprise a dispersant. EXamples of suitable
dispersants
include, without limitation, -sulfonated-lbrinaldehyde7based dispersants.
(e.g., sultbnated
acetone fonnaidehyde condensate), exaMples of which may include :Mud* 19
Available
from Geo Specialty Chemicals, Ambler, Pennsylvania. Other suitable dispersants
may be
polycarboxylated ether dispersants such as Ligktimete 5581F and Liquimene
5141,
available from BASF Corporation Houston, Texas; or Ethacryl G available fim
Coatex,
Genay, France. An additional exaMple of a suitable commercially available
dispersant is
Rrst-3 dispersant, available from Halliburton Energy Services, Inc, Houston,.
Texm. Of
particular importance in regards to the examples that fbilow, is that the
13quimete 514,
diSpersaiit eOmpriSes 36% by Weight of the polycarboxylated ether hi water.
While a variev
of dispersants may be used in accordance with embodiments, polyearboxylated
ether
dispersants May be particularly suitable for use in some. ernbodiinents.
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 deri.vatives) tesulting in formation of a gel that suspends
the pumice and
hydrated lime in the composition for an extended period of time.
[00191 in some embodinients, 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 andfor including- any of about 0,01%, a.bout 0.1%, about 0,5%,
about 1%,
about 2%, about 3%, about 4%, or about 5% by weight of the pumice. With the
benefit of
this disclosure, one of ordinary skill in the art will recognize the
appropriate amount of
dispersant to include for a chosen: application.
[00201 Other additives suitable ibr use in subterranean eeMentin operations
also
.may be included in embodiments of the setrdelaye,d cement compositions.
Examples of such
,additives include, but are not limited to: weighting agents. Ilithtweight
additives, gas-
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generating additives, .111.0diailkal-prpperty-enbancinu additives,
lost,,circulation materials,
fatration-control additives, thiid-loss-cotitrol additives, detbaming agents,
foamina- agents,
thixotropic additives, and combinations- thereof. In embodiments, one or more
of these
additives may he added to the set-delayed cement C913113pSitii./T1 after
storing but prior to
placement of the set-delayed cement composition into a subterranean formation.
With the
benefit of this disclosure, a person having ordinary skill in the art Will be
able to determine
the type and amount ladditive useful for a particular :application and desired
result,
[0021] Those of ordinary Skill in the art will appreciate that embodiments of
the set-
delayed cement: coMpoSitions generally shotild 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 gallonõ ("Ibigal") to about 20 'lb/gal.
In certain
embodiments,. the set-delayed cement compositions may have a density in the
range of from
about 8 Ibigal to about 17 lb/gat Entbodiments,of the set-delayed cement
coMpositions may
be foamed or tin:foamed 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 att. In embodiments, the density may be twiticed after storing the
eonmosition, but
prior to placement in a subterranean formation. Those of ordinary skill in the
art, with the
benefit of this discloSure, will recognize the tippropriate density for a
particular application,
[(10221 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 I day, about 2 weeks, about 2 years or more) at room temperature in
quiescent storage.
For :example, the set-delayed cement compositions May remain in a pumpable
fluid state tbr
_a period of titne from about 1 day to about. 7 days or more. In some
embodiments, the set-
delayed cement compositions may remain in a pumpabie 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
using a pressurized consistometer in accordance with the procedure for
determining 'cement
thickening times Set forth in API RP Practice I013-2, Recotnmended Practice
16r Thstitig
Well Cements, First Edition, July :2005.
[0023] 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. By
way of example, embodiments of the set-delayed cement compositions may be
activated to
tbrm 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
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hardened 'mass in a time period ranging betett any of andfor including any of
about I day,
about 2 days, about 4 days, about 0 days, about 8 days, aboat 10 days, or
about 12 days.
[00241 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 palling
forces. The
compressive strength may be measured at a specified time: after the set-
delayed cement
i01.11pOiti011 has been aCtivated and the resultant composition is maintained
undt.1 :specified
temperature and pressure conditions. Compressive strength can be measured by
either
destruetive 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 pound4orce
per square inch (psi). Non --destructive methods May employ a UCATm ultrasonic
cement
analyzer, available, front Fann Instrument Company, Houston, TX. Compressive
strength
values May be determined in accordance with API RP 10B-2, Recommended Practice
fiir
Tesling Vel1 aments, First Edition, July 2005.
1I0025'1 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: abentt 5000
psi, -alternatively,
from about 100 psi to about 4500 psi, or alternatively from about 500 psi to
about 4000 psi,
In seine 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 hi some embodimentsõ the compressive Strength values may be determitk..d
using
destructive or iron-destructive methods at a temperature ranging from 100"F to
2001.-7
[00261 Embodiments may include the addition of a cement set activator to the
set-
delayed cement compositions. Examples of suitable cement set activators
include, but are
not limited to: amines such as triethanolamine, diethanotamine; silicates such
as sodium.
silicate; zinc forinate., calcium acetate; .Groups lA .and 11A hydroxides such
as sodium
hydroxide, magnesium hydmide, 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 MO 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 SOdit1111 OM 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 Ibr activation of the set-delayed
cement
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compositions, including polymeric metaphosphate salts, phosphate salts, and
combinations
thereof: Specific examples of pOlyrrierie metaphosphate salts that Ttlay be
used include
sodium hexametaphosphate, sodium trimetaphosphate, sodium tetrametaphosphate,
sodium
pnt etaphophatr. xiiuin 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 exa.mple., a liquid additive comprising a monovalent salt, a
polyphosphate, and
optionally a dispersant.
[00271 Tile Ceraellt set activator Should be added to embodiments of the set-
delayed
cement compositions in amounts sufficient to induce the set-delayed cement
compositions to
set into a. hardened mass. In certain embodiments, the cement .set activator
may be added to
a se-delayed centent composition in an amo-unt 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 andfor 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 of this disclosure, will K.-cognize the appropriate amount of cement
set activator to
include for a chosen application.
[00281 :As will be appreciated by those of ordinary skill in the art,
embodiments of
the set-delayed cement conipositions 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 set
retarder,
.and optionally a dispersant. The set-delayed cement composition may be
introduced into a
subterranean. formation and allowed to set therein. As used herein,
introducing the set-
delayed cement composition into a subterranean formation includes:
introduction into any
portion of the subterranean formation, including-, without limitation, into a
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 cornprise, for
exaMple, =the
addition of a cement set activator to the set-delayed cement composition.
[00291 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 coMpositiori may be gored, for example, in a vessel of
other Suitable
container. The set-delayed cement composition may be permitted to remain. in
storage foe a
desired time period. For example, the set-delayed cement tomposition may
remain in
11
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'storage for a time period of about 1 day or 'longer. For example, the set-
delayed cement
composition may remain in storage frit- a time period of (*Out 1 clay, 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 simile embodiments, the se-delayed cement
composition
may remain in storage for a time periOd ìn a rang;... of t7rom about l 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:
[003.01 In pritnary cementing embodiments, for example, .embodiments of the
set-
delayed cement compoSition may be: introduced into an annular space between a
conduit
located in a etlhon. and the walls of a wellbore and oi a larger conduit in
the xvellbore),
Wherein the wellbore penetrates the subterranean formation. The set-delayed
cement
composition may be allowed to, set in the annular space to form an annular
sheath of
hardened cement, 'The set-dehryed 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.
[00311 in remedial cementing embodiments, a. set-delayed cement composition
may
be used, for example, in squeeze-(_ementing operations or in the placement of
cement plum.
'By way of example, the set-delayed composition may be placed in a wellbore to
plug an
20. 'opening. (e.g., a void or crack) in the formation, in a gravel pack, M
the conduit, in the
cement sheath, andlor between the cement sheath and the conduit (e.g., a
mieroannulus).
[00321 An example embodiment comprises a method of cementing comprising:
providing, a Set-delayed cement composition comprising water, pumice, hydrated
litne, a
primary set retarder, and a secondary set retarder; activating the set-delayed
cement
composition to produce ,an aetiVated cement composition; introducing the
activated cement
composition into a subterranean tbrmation; and allowing the activated cement
composition
to set in the subterranean formation.
1100311 :An example embodiment comprises a :method of mitigating contamination
in
the manufacture of a set-delayed eel-nem composition, the method comprising:
providing a
dry-blend cement composition comprising pumice and hydrated lime; and
preparing a set-
delayed cement composition comprising water,' the dry-blend cement
composition, a primary
set retarder, arid a swortdary set retarder,
[00341 An example embodiment comprises a set-delayed cement composition
comprising; water; pumice; hydrated Hine; a primary set retarder;: and a
Secondary set
:retarder; wherein the set-delayed cement composition further comprises a
cementitious
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contaminant; and whetein the set-delayed cement composition will remain in a
pumpable
fluid State frit a time period of at least abOut I day at toOm temperatthe in
quiescent storage.
[0035] An example embodiment etnnprises a set-delayed cement system
comprising:
a set-delayed cernent composition comprising water, pumice, hydrated lime, a
primary set
retarder, and a secondary set retarder; wherein the set-delayed ceinent
composition
-additionally comprises a cementitious contaminant; an activator for
activating the set
delayed cetnent composition; mixing e,quipment fOr mixing the set-delayed
cetnem
composition and the activator to form an activated cement composition; and
pumping
equipmentibr delivering the activated centerit eomposition into a wellbore.
[0036] Referring now to FIG, 1, preparation ola set-delayed cement composition
in
accordance with example embodiments will now be described. FIG. 1 illustrates
a system 2
for preparation of a set-delayed cement composition and delivery to a
µ,vellbore in accordance
with certain embodiments. As shown, the set-delayed cement composition may be
mixed in
mixing equipme.nt 4, suCh as a jet mixer, re-circ.ulating mixer, or a batch
mixer, for example,
and then pumped via pumping equipment 6 to the \Venom. _In some embodiments,
the
mixing, equipment 4 and the pumping equipment 6 :may he disposed on one or
More cement
trucks as will be apparmt to those of ordinary skill in the art. in some.
embodiments, a jet
mixer may be used,: tbr example, to continuously -mix the limesettable
material with the
water as it is being pumped to the wellbore.
[0037] An example technique tbr placing a set-delayed cenient 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 dep.icts 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 FICi..2A, the surface Nuipmerit 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 pun-Ong 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 whieb conveys the set-
delayed cement
composition 14 downhole.
[0038] Turning no.s,,v to FIG. 23, the setAtIayed cement cornposition 14 may
be
placed into a Subterranean formation 20 in accordance with example
emboditnents. As
illustrated, a wellbore 22 may be drilled into the subterranean formation 20.
While wellbore
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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
thmugh the.
subterranean formation 20, such as horizontal and slanted wellbores. As
illustrated, the
wellbore 22 COmmises walls 24 in the illustrated embodiment, a suriace casing
26 has been
inserted into the wellbore 22. The surface casing NS 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
may also be disposed in the wellbore 22. As illustrated, there is a wellbore
annulus 32
tbmed between the casing 30 and the walls 24 of the welIbore 22 andfor 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.
[0039] With continued reference to F1G. 2B, the set-delayed cement
compositions
14 may be pumped down the interior of the casing 30..I.he setAelayed cement
composition
14 may be allowed to flow down the interior of the casing 30 through the
easing 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 ibrm 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 he
used that include introducing the set.-delayed cement composition 14 into the
subterranean
lomation 20 by way of the wellbore annulus 32 instead of through the casing
30.
[00401 As it is introduced, the set-delayed cement composition .14 may
displace
other fluids 36, such as drilling fluids andfor 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)õ 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 easing 30 prior to cementing. After the
bottom plug 44
reaches the landing collar 46, a diaphragm or other suitable device. rupture
to allow the set-
delayed cement composition 14 through the bottom pl.ug 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 ping 44.
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[0041] The exemplary set-delayed cement compositions disclosed herein may
directly or indirectly affect one or mote 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, andfor
recondition the
exemplary set-delayed cement compositions. The disclosed set-delayed cement
compositions
may also directly or indirectly afitct 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, tubular, arid 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 pressure and
temperature),
gauges, and/or combinations thereof, and the like. The disclosed set-delayed
cement
compositions may also directly or indirectly alTect the -various downhole
equipment and
tools that may come into contact with the set-delayed cement compositions such
as, hut 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 andlor pumpsõ centralizers,
turbolizers, scratchers, floats (e.g., shoes, collars, valves, etc.), logging
tools and related
telemetry equipmentõ 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
electricalõ fiber optic, hydraulic, etc.), surveillance lines, drill bits and
reamers,
sensors or distributed sensors, downhole heat exchanaers, valves and
corresponding
actuation devices, tool seals, packers, cement plugs, bridge plugs, and other
wellbore
isolation devices, or components, and the like.
EXAMPLES
[0042.1 To facilitate a better understanding of the present embodiments, the
following c.txamples of certain aSpects of some embodiments are given, in no
way should the
following exatnples be read to limit, or define, the entire scope of the
embodiments.
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Exalt*pie
[0043.1 TiNtAvt-tilOW4and Out.mds Of pumice and hydrated lime fOr use in a set-
delayed cement coMposition- were dry blended at a bulk Own faCility. Samples
of the dry
blend cement composition were collected for use. Using the collected dry blend
cement
composition, six experimental set-delayed samples were prepared. 'fhe
experimental samples
differed only in that each contained A unique secondary set retarder. Two
additional
laboratory set-delayed samples were prepared using pumice and hydrated lime
that were not
dry blended in the trial. The two laboratory samples did not contain a
secondary retarder;
however, one of the laboratory samples was intentionally contarninated with
Class li
Portland cement, The experimental and laboratory Samples additionally
comprised water,
weight additive (ground hausmannite ore), a primary retarder (phosphonic acid
'derivative),
and a polycarboxylated ether dispersant lite compositional makeup of the eight
samples is
displayed in Table 1 below. While not indicated in Table I, it is believed
that the six
experimental samples were contaminated with Portland cement or other
eementitious
15. contaminants at the bulk plant facility.
Table 1
Sample Composftions
% By weight Laboratory Laboratory
Experimental
of Pumice 'Sample 1 (g) Sample 2 (g)
Samples (g)
Pumice 100 133.3 133.3 113.3
Lime 20 16.7 26.7 26.7
Water
1 65 80.0 80.0 80.0
Weighting
Additive 2.0 2.7
Primary
Retarder 0.06 galisk 1.7 1.7 1.7
Dispersant: 0.60 0.8 0.8 0.8
Class 11.
Portland
Cement 5.0 6.67
00441 As discussed..in the preceding paragrilph, the six experimental
SEITITICS each
comprised A unique .secondary set .retarder. The secondary set retarder was
present in an
amount of 0,5% by weiAt of the pumice, ATI eight of the samples were placed in
sealed
containers and allowed to age 'for 2A hours before observation. The six
retarders used. for the
experimental Samples comprised zinc oxide, a copolymer of 2-acrylamido-2-
methylpropane
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sulfonic acid and acrylic acid, a lignosultbnate retarder, tartaric acid,
potassium pentaborate,
and citric kid. The results of each OTTIbination are listed in Table 2 below.
Table 2
Sample Regal&
:Sample Secondary Retarder Observation
Laboratory Sample I None Still floWable
=
Laboratory Sample 2 None Gelled overnight
Experimental Sample 1 Zinc Oxide -Gelled overnight
Experimental Sample 2 Copolymer Gelled OVerilight
Experimental Sample 3 Liimosulfonate Still flowable
Experimental Sample 4 Tartaric Acid Partially gelled overnight
Experimental Sample 5 Potassium Pentaborate Still flowable
Experimental Sample:, 6 Citric Acid Cielled immediately
[0045] The results indicate that the set-delayed samples adversely reacted to
the
inclusion of 'Portland Class H cement. In particular, Laboratory Sample 2 that
included the
Portland Class /4 cement gelled while Laboratory Sample 1 without any added
Portland
cement was still flowable. As seen from the experimental -smnplesõ the
addition of a
secondary set retarder May be used to counteract the cetnentitious
contaminants from the
10. bulk
plant. By way of example, the experimental samples with the lignosulfbnate and
the
potassium pentaborate retarders did not gel overnight.
Example 2
[00461 Three liter-sized samples of set-delayed eetnent compositions were
prepared
using the same components and proportions as Example 1, however, the samples
additionally cornpriSed A secondary liignosallonate retarder the saine
retarder used in
Experimental Sample 3 fi7om Example 1) and/or were intentionally contaminated
with Class
14 Portland cement The compositional makeup of the three samples is displayed
in Table 3
below,
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TAW 3
Sample Compositions
) By W eight of
Pumice Sample (g) Sample 2 (g) Sample 3 (g)
Pumice 1:00 1000.0 1000:0 1000,0
Lime 20 200.0
200.0 200.0
Water: 65 650,0 650.0 650.0
=
,
Weighting
Agent 2.0 20.0 20.0 20.0
Prirnary
Retarder 0.06 galfsk 12.5 11.5 12.5
Dispersant 0.60 6.0 6:0 6.0
Class .FI l'ortland
Cement 2.5 0,0 25.0 25.0
Secondary
Retarder 0.50 5,0 5.0 0.0
[00471 The volumetric average viscosity was plotted at 100 rpm for each sample
over a 21 day span. A Model 35A Fann ViScometer and a No, 2 spring with a Fun
Yield
Stress Adapter were used to measure the volumetric average viscosity in
accordance with the
procedure Set forth in API RP Practice 108-2, Recotint1entied Preletiee lin'
raging frell
Cements. The results of this test are shown in Table 4 below.
Table 4
Volume Average Viscosity of the $amples
51uffy Age ()ays)
'0 1 5 12 16 1921
Sample
1235 1235 1417 1508 1521 1538 1560
Sample VAV
1417 1560 2015 2457 2743 949 1313 rpm
Sample
3 1.749 not .measurable
[00481 Liquimene 55811 dispersant was added to Sample 2 on day 19 in an amount
of 0.1% by weight of the putnice. Example 2 indicates that the inclusion of a
secondary
retarder such as a lignosulfonate retarder may be used to counteract the
effects of Portland
cement in set-delayed cement compositions.
Example 3
[00491 The same set-delayed cement composition of Sample 2 in Example 2 was
scaled tip from 3 liters to 15 gallons and also to 35 barrels, The volumetric
average viscosity
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w each sample size. was plotted at 100 rpm over a 21 day span. The results of
this test are
111.gs-A in Table 5 Wow.
Table 5
Viscosity Tests
1 titer 15 Gallon 35 hhl
SlurryVAV Slurryrry Slurry (4..1 Age V x V N
:tii
, ,,....õ. VAV @ Age Age
100 rprn 100 rpm = 10(> rpth
(Days) (Days) (Days)
___________________________________________________________________ ,
0 l 1417 0 559 0 9'75
,
. 1 1560 = 1 897 . 1 , 1508 ,
2015 4 1131 7 1560
12 2457 5 13113 3 1566.5
16 2743 6 1154.5 4 1677
, 19 949 7 1202.5 , 5 1859
71 1313 8 1625 6 1703
, 2860 7 1950
10 377 . 8 2210
11 988 9 1976
1118 10 2769
73 897 11 2795
17 1391 11 1521
27 , 598 11 1898 .
32 1703 13 202$
14 2314
15 2444
15 1001
16 1.456
17 1989 .
18 2509
18 1066
19 1950
1989 ,
21 3796
77 2470
,
5 [00501 Example 3 thus indicates that the inclusion of .a secondary
retarder such as a
lignosulfonate retarder may be used to counteraet the effects of Portland
cement in set-
delayed cernent compositiOns on a larger scale.
1:00511 It should he understood .that the compositions and methods are
described. in
terms of "co.mprising," "containingõ" or "including" various components or
steps, the
10 compositions and methods can also "consist essentially of' or "consist
of' the various
l 9
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components and -steps. Nloreover, 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.
[00521 For the sake of brevity, only certain ranges are explicitly disclosed
herein.
l-lowever, ranges from any lower limit may be conibined with any upper limit
to recite a
range not explicitly recited, as well as, names 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 Unlit 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, Thos, every point
or individual
value may serve as its own lower or npper limit conibined With any other point
or individual
value or any other lower or upper limit, to recite:a range not explicitly
recited.
[0053) Therefore, the 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 illtistrative only, and they :may be modified and
practiced in different but
equivalent manners appamin to those skilled in the art having the benefit of
the teachings
herein. Although individual embodiments are discussed, the invention covers
all
combinations of all those embodiments. Furthennore, no limitations are
intended to the
details of construction or design herein ShOWn, other than as described in the
claims below.
AIso, 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
anisidered 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.
