AU2016266033A1 - Cement Set Activators for Set-Delayed Cement Compositions and Associated Methods - Google Patents

Abstract

Disclosed herein are cement compositions and methods of using set-delayed cement compositions in subterranean formations. In one embodiment, an activated cement composition is described. The activated cement composition may comprise water, pumice, hydrated lime, a set retarder; a monovalent salt and a polyphosphate.

Description

CEMENT SET ACTIVATORS FOR CEMENT COMPOSITIONS AND METHODS 2016266033 30 Nov 2016 [0001] The present application is a divisional application from Australian patent application number 2014317924, the entire disclosure of which is incorporated herein by reference.

BACKGROUND

[0001a] Embodiments relate to subterranean cementing operations and, in certain embodiments, to set-delayed cement compositions and methods of using set-delayed cement compositions in subterranean formations. 10 [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 15 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 20 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 25 cementing operations. In some instances, set-delayed cement compositions have been used. Set-delayed cement compositions are characterized by remaining in a pumpable fluid state for at least about one day (e.g., a least about 7 days, about 2 weeks, about 2 years or more) at room temperature (e.g., about 80° F) in quiescent storage. When desired for use, the set-delayed cement compositions should be capable of being activated whereby reasonable 30 compressive strengths are developed. For example, a cement set accelerator may be added to a set-delayed cement composition whereby the composition sets into a hardened mass. Among other things, the set-delayed cement composition may be suitable for use in wellbore 1 applications, for example, where it is desired to prepare the cement composition in advance. This may allow, for example, the cement composition to be stored prior to its use. In addition, this may allow, for example, the cement composition to be prepared at a convenient location and then transported to the job site. Accordingly, capital expenditures may be reduced due to a 5 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. 2016266033 30 Nov 2016 [0004] While set-delayed cement compositions have been developed heretofore, challenges exist with their successful use in subterranean cementing operations. For example, set-delayed cement compositions prepared with Portland cement may have undesired gelation 10 issues which can limit their use and effectiveness in cementing operations. Other set-delayed compositions that have been developed, for example, those comprising hydrated lime and quartz, may be effective in some operations but may have limited use at lower temperatures as they may not develop sufficient compressive strength when used in subterranean formations having lower bottom hole static temperatures. 15 [0004a] Throughout the description and claims of the specification, the word “comprise” and variations of the word, such as “comprising” and “comprises”, is not intended to exclude other additives, components, integers or steps.

[0004b] A reference herein to a patent document or other matter which is given as prior art is not to be taken as an admission that that document or matter was known or that the 20 information it contains was part of the common general knowledge as at the priority date of any of the claims.

SUMMARY OF THE INVENTION

[0004c] In one aspect of the invention, the invention provides an activated 25 cement composition comprising water; pumice; hydrated lime; a set retarder; a monovalent salt; and a polyphosphate. 2 PCT/US2014/054497 WO 2015/035281 2016266033 30 Nov 2016

BRIEF DESCRIPTION OF THE DRAWINGS

[0001] These drawings illustrate certain aspects of seme of the embodiments of the present method, and should not be used to limit or define the method, [0002] FIG. i illustrates a system for the preparation and delivery of a set-delayed Scement composition to a wellbore in accordance with certain embodiments, [0003] FIG. 2A illustrates surface equipment that may be used in the placement of a set-delayed cement composition in a wellbore in accordance with certain, embodiments, [0004] FIG. 2B illustrates the placement of a set-delayed cement composition into a wellbore annulus in accordance with certain embodiments. 10 [0005] FIG. 3 is a graph of the dispersant amount vs. the thickening time of set- delayed cement compositions activated with a liquid additive comprising a monovalent salt and polyphosphate activator combination. 3 PCT/US2014/054497 WO 2015/035281 2016266033 30 Nov 2016

DESCRIPTION OF .PREFERRED EMBODIMENTS

[0006] Embodiments relate to subterranean cementing operations and. in certain embodiments,Jo set-delayed cement compositions and methods of using set-delayed cement compositions in subterranean formations. In particular embodiments, improved cement set 5 activators used for the activation of set-delayed cement compositions may be provided. Embodiments of the cement set activators may he used to activate a set-delayed cement composition while also achieving desirable thickening times and compressive strength development.

[0007] Embodiments of the set-delayed cement compositions may generally 10 comprise water, pumice, hydrated lime, and a set retarder. Optionally, the set-delayed cement compositions may further comprise a dispersant. Embodiments of the set-delayed cement compositions may be foamed. Advantageously, embodiments of the set-delayed cement 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 IS pumpable fluid state for at least about 1 day, about 2 weeks, about 2 years, or longer. Advantageously, the set-delayed cement compositions may develop reasonable compressive strengths after activation at relatively low temperatures. While the set-deiaved cement compositions may be suitable lor a number of subterranean cementing operations, they may be particularly suitable for use in subterranean formations having relatively low bottom hole 20 static temperatures, e.g., temperatures less than about 200*F or ranging from about lOtfrF to about 200"F, in alternative embodiments, the set-delayed cement compositions may be used in subterranean formations having bottom hole static temperatures up to 450*F or higher, [0008] 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 25 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 imsaturaied as desired for a particular application. Seawater or brines may be suitable, for use in embodiments. Further, the water may be present in an amount sufficient to form a 30 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», die 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 4 PCT/US2014/054497 WO 2015/035281 2016266033 30 Nov 2016 pumice. Due of Ordinary skill hi the art with the benefit of this disclosure will recognize the appropriate amount of water for a chosen application, 5 10 [0009] Embodiments of tile set-delayed cement compositions may comprise -pumice. Generally, pumice is a volcanic rock that can exhibit cementitious properties in that it may set and harden in the presence of hydrated time and water. The pumice may also be ground Generally, the pumice may have any particle size distribution as desired for a particular application, in certain embodiments, the .pumice may have a mean particle size in a range of front about ! micron to about 200 microns. The mean particle size corresponds to d50 values as measured by particle size analyzers such as those manufactured by Malvern Instruments, Worcestershire, United Kingdom, in specific embodiments, the pumice may have a mean particle size in a range of from about 1 micron to about 200 microns, from about 5 microns to about 100 microns, or from about 10 microns to about 50 microns. In one particular embodiment, the pumice may have a mean particle size of less than about 15 microns. An example of a suitable pumice is available from Hess Pumice Products, Inc., 15 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 a chosen application, 20 [00 iO] Embodiments of the set-delayed cement compositions may comprise hydrated lime. As used herein, the term “hydrated lime” will be understood to mean calcium hydroxide, in some embodiments, the hydrated lime may be provided as. quicklime (calcium oxide) which hydrates when mixed with water to form the hydrated lime. The hydrated lime may be included in embodiments of the set-delayed cement compositions, for example, to 25 form a hydraulic composition with, the pumice. For example, the hydrated lime may be included in a pimrice-io-hydrated-iime 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 30 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 cemen ti tious components may primarily comprise the pumice and the hydrated lime without: any additional 35 components fe.g., "Portland cement, fly ash, slag cement) that 'hydraulically set in the 5 WO 2015/035281 PCT/US2014/054497 2016266033 30 Nov 2016 10 15 20 30 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. [0011] Embodiments of the set-delayed cement compositions may comprise a set retarder, A broad variety of set retarders may be suitable for use io the set-delayed cement compositions. For example, the set retarder may comprise phosphonie acids, such as ethylenediamine tetra(methyle.ne phosphonie acid), dietbytenetriamine pento(meihy|ene phosphonie acid), etc,; Signosuifonaies, such as sodium lignosulfonate, calcium lignosulfonate, etc.; salts such as stannous sulfate, lead acetate, monobasic calcium phosphate, organic acids, such as citric acid, tartaric acid, etc,; cellulose derivatives such as hydroxyl ethyl cellulose (HEC) and earboxymethyl hydroxyethyl cellulose (GMHEC); synthetic eo- or ter-polymers comprising sulfonate and carboxylic acid groups such as suifbnate-iunctfonalixed acrylamide-acrylic acid co-polymers; borate compounds such as alkali borates, sodium .metaborate, sodium tetraborate, potassium pentaborate; derivatives thereof or mixtures thereof Examples of suitable set retarders include, among others, phosphonie acid derivatives. One example of a suitable set retarder is Micro Matrix* cement retarder, available from Halliburton Energy Services, Inc, Generally, the set retarder may be present in the set-delayed cement compositions in an amount sufficient to delay the setting for a desired time, hi some embodiments, the set retarder may he 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, hi speci fic 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. [0012] As previously mentioned, embodiments of the sei-delaved cement compositions may optionally comprise a dispersant Examples of suitable dispersants include, without 1 imitation, sulfonated-formaldehyde-based dispersants (e.g., sulfonated acetone formaldehyde condensate), examples of which may include Daxa# 19 dispersant available from Geo Specialty Chemicals, Ambler, Pennsylvania, Other suitable dispersants may be polycarboxylated ether dispersants such as Uquimeni * 5581F and Liquiment* 5I4L dispersants available from BASF Corporation Houston, Texas; or Ethacryi™ G dispersant available from Coatex, Genay, France. An additional example of a suitable commercially available dispersant is CF R>M-3 dispersant, available from Halliburton Energy Sendees, Inc, Houston, Texas. The LiquimenP" 5141, dispersant may comprise 36% by weight of the polycarboxylated ether in water. While a variety of dispersants may be used in accordance 6 PCT/US2014/054497 WO 2015/035281 2016266033 30 Nov 2016 with embodiments, polyearboxylaied ether dispersants may be particularly suitable for use in some embodiments. Without being limited by theory, it, is believed that polycarboxySated ether dispersants may synergistically interact with other components of the set-delayed cement composition. For example, it is believed that the polycarboxylaied ether dispersants 5 may react with certain set retarders (e.g„ phosphonie acid derivatives) .resulting in formation of a gel that suspends the pumice and hydrated lime in the composition for an extended period of time.

[0013] 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 10 of the pumice, in specific embodiments, the dispersant may be present in an amount ranging between any of and/or including any of about 0.01%, about 0,1%, about 0.5%, about 1%, about 2%, about 3%, about 4%, or about 5% by weight of the pumice. One of ordinary skill in the art, with the benefit of this disclosure, will recognize the appropriate amount of the dispersant to include for a chosen application. 15 [0014] Other additives suitable for use in subterranean, cementing operations also may be included in embodiments of the set-delayed cement compositions. Examples of such additives include, but are not limited to: weighting agents, lightweight additives, gas-generating additives, meehanieal-property-enhancing additives, lost-circulation materials, filtration-control additives, iluid-loss-control additives, detoamiog agents, foaming agents, 20 thixotropic additives, and combinations thereof, in embodiments, one or more of these additives may be added to the set-delayed cement, compositions after storing but prior to the placement of a set-delayed cement composition into a subterranean formation. A person having ordinary skill in the art, with the benefit of this disclosure, should readily be able to determine the type and amount of additive useful for a particular application and desired 25 result.

[0015] 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 fib/gaT) to about 20 lb/gal. hi certain 30 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 7 PCT/US2014/054497 WO 2015/035281 2016266033 30 Nov 2016 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.

[0016] 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 5 about I day, about. 2 weeks, about 2 years or more) at room temperature {e.g., about 80° F) in quiescent storage. For example, the set-delayed cement compositions may remain in a pumpable fluid state for a period of time from about I day to about 7 days or more, in some embodiments, the set-delayed cement.compositions may remain in a pumpable fluid state for at least about 1 day, about 7 days, about 10 days, about 20 days, about 30 days, about 40 10 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 (“Be”), as measured on a pressurized eonsistometer in accordance with the procedure lor determining cement thickening times set forth in API RP Practice 10B-2, Recommended Practice for Testing Weil Cements, First Edition, July 2005. 15 [0017] When desired for use, embodiments of the set-delayed cement compositions may be activated (e.g., by combination with an activator) to set into a hardened mass. The term “cement set activator” or “activator’*, as used herein, refers to an additive that activates a set-delayed or heavily retarded cement composition and may also accelerate the setting of the set-delayed, heavily retarded, or other cement composition. By way of example, 20 embodiments of the set-delayed cement compositions may be activated to form a hardened mass in a time period in the range of from about 1 hour to about 12 hours. For example, embodiments of the set-delayed cement compositions may set to form a hardened mass in a time period ranging between any of and/or including any of about l day, about 2 days, about 4 days, about 6 days, about 8 days, about 10 days, or about 12 days. 25 [0018] In some embodiments, the .set-delayed cement compositions may set to have a desirable compressive strength after activation. Compressive strength is generally the capacity of a material or .-structure to withstand axially directed pushing forces. The compressive strength may be measured at a specified time after the set-delayed cement composition has been activated and the resultant composition is maintained under specified 30 temperature and pressure conditions. Compressive strength can be measured by either destructive or non-destructive methods. The destructive method physically tests the strength of treatment fluid samples at various points in time by crushing the sample* in a compression-testing machine. The compressive strength is calculated from the failure load divided by the cross-sectional area resisting the load land is reported in units of pound-force 35 per square inch (psi), Non-destructive methods may employ a UCAW ultrasonic cement 8 PCT/US2014/054497 WO 2015/035281 2016266033 30 Nov 2016 analyzer, available from Fann. Instrument Company, Houston, TX, Compressive strength values may be determined in accordance with API RP 108-2, Reconrmemled Practice for Testing Weil Cements, First Edition, July 2005.

[0019] By way of example, the set-delayed cement compositions may develop a 24-5 hour compressive strength in the range of from about 50 psi to about 5000 psi, alternati vely, from about 100 psi to about 4500 psi, or alternatively from about 500 psi to: about 4000 psi. In some embodiments, the set-delayed cement compositions may develop a compressive strength in 24 hours of at least about 50 psi, at least about 100 psi, at least about 500 psi, or more. In some embodiments, the compressive strength values may be determined using 10 destructive or non-destructive methods at a temperature ranging from ΓΟΟ'Ι7 to 200°F, [0020] in some embodiments, the set-delayed cement compositions may have desirable thickening times after activation. Thickening time typically refers to the time a fluid, such as a set-delayed cement composition, remains in a fluid state capable of being pumped. A number of different laboratory techniques may be used to measure thickening 15 time, A pressurized consistometer, operated in accordance with the procedure set forth in the aforementioned API RP Practice 10:8-2, may be used to measure whether a fluid is in a pumpable fluid state. The thickening time may be the time fonhe treatment fluid to reach 70 8c and may be reported as the time to reach 70 Be. in some embodiments, the cement compositions may have a thickening time of greater than about 1 hoar, alternatively, greater 20 than about 2 hours, alternatively greater than about 5 hours at 3,000 psi and temperatures in a range of from about 50°F to about 400CF, alternatively, in a range of from about S0°F to about 250°F, and alternatively at a temperature of about J40eF.

[0021] 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 25 not limited to: zeolites, amines such as triethanolamine, diethanolamine; silicates such as sodium silicate; zinc formate; calcium acetate; Groups IA and HA hydroxides such as sodium hydroxide, magnesium hydroxide, and calcium hydroxide; monovalent salts such as sodium chloride; divalent salts such as calcium chloride; nanosiliea (i.e., silica having a particle size of less than or equal to about 100 nanometers); polyphosphates; and 30 combinations thereof. In some embodiments, a combination of the polyphosphate and a monovalent salt may be used for activation. The monovalent salt may he any salt that dissociates to form a monovalent cation, such as sodium and potassium salts. Specific examples of suitable monovalent salts include potassium sulfate, and sodium sulfate. A variety of different polyphosphates may be used in combination with the monovalent, salt, for 35 activation of the set-delayed esmtent compositions, including polymeric metaphosphate salts. 9 PCT/US2014/054497 WO 2015/035281 2016266033 30 Nov 2016 phosphate salts, and combinations thereof. Specific examples of polymeric metaphosphate salts that may be used include sodium hexametaphosphate, sodium trimetaphosphaie, sodium tetrametaphosphate, sodium pemtametaphospha.te, sodium heptametaphosphate, sodium octaineiaphosphate, and combinations thereof, A. specific example of a suitable cement set 5 activator comprises a combination of sodium sulfate and sodium hexanietapliosphate, 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- 15 [0022] Some embodiments may include a cement set activator comprising nanosilica. As used herein, the term “nanosllica” refers to silica having a particle size of less than or equal: to about 100 nanometers (“nm”). The size of the nanesiliea may be measured using any suitable technique, it should be understood that the measured size of the nanosiliea may vary based: on measurement technique, sample preparation:, and sample conditions such as temperature, concentration:, etc. One technique for measuring the particle size of the nanosilica is Transmission Electron Microscopy (TEM), An example of a commercially available product based on Jaw- diffraction is 'the ZETASIZBB Nano ZS particle size analyzer supplied by Malvern Instruments, Worcerstershire, UK, In some embodiments, the nanosilica may comprise colloidal nanosiliea. The nanosiliea may he stabilized using any suitable technique, In some embodiments, the nanosilica may be stabilized with a metal oxide, such as lithium oxide, sodium oxide, potassium oxide, and/or a combination thereof. Additionally the nanosllica may be stabilized with an amine and/or a metal oxide as mentioned above. Embodiments of the nanosliicas have an additional advantage in that they have been known to fill in pore space in cements which can result in superior mechanical properties in the cement after it has set. 25 [0023] Some embodiments may include a cement set activator comprising a combination of a monovalent salt and a polyphosphate. The monovalent salt and the polyphosphate may be combined prior to addition to the set-delayed cement composition or may be separately added to the set-delayed cement composition. The monovalent salt may'' he any salt that dissociates to form a monovalent cation, such as sodium and potassium salts. 30 Specific examples of suitable monovalent salts include potassium sul fate and sodium sulfate. A variety of different polyphosphates may he 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 he used include sodium hexametaphosphate, sodium 35 trimetaphosphaie, sodium tetrametaphosphate, sodium pentametaphosphate, sodium 10 PCT/US2014/054497 WO 2015/035281 2016266033 30 Nov 2016 heptametaphosphate, sodium oetametaphosphate, and combinations thereof. A specific example of a suitable cement set activator comprises a combination of sodium aultitle and sodium hexametaphosphate. Interestingly, sodium hexametaphosphate Is also known in the art to be a strong retarder of Portland cements. Because of the unique chemistry of 5 polyphosphates, polyphosphates may be used as a cement set activator for embodiments of the set-delayed cement compositions disclosed herein. The ratio of the monovalent salt to the polyphosphate may range, for example,, from about 5:1 to about 1:25 or from about 1:1 to about 1:10. Embodiments of the cement set activator may comprise the monovalent salt and the polyphosphate salt in a ratio (monovalent salt to polyphosphate) ranging between any of 10 and/or including any of about 5:1, 2:1, about 1:1* about 1:2, about 1:5., about 1:10, about 1:20, or about 1. :25.

[0024] in some embodiments, the combination of the monovalent salt and the polyphosphate may be mixed with a dispersant and waiter to form a liquid additive for activation of a set-delayed cement composition. Examples of suitable-dispersants Include, 15 without limitation, the previously described dispersants, such as sidfohated-fbnnaldehyde-based dispersants and polycarboxylated.' ether dispersants. One example of a suitable sulfonated-fbnnaldehyde-based dispersant is a sulfbnated acetone formaldehyde condensate, available from .Halliburton Energy Services, Inc., as CFR-3™ dispersant. One example of a suitable polycarboxylated ether dispersant is Liquiment® 514L or 558IF dispersants, 20 available from BASF Corporation, Houston* Texas.

[0025] The liquid additive may function as a cement set: activator. As discussed above, a cement set activator may also accelerate the setting Of the set-delayed or heavily retarded cement The use of a liquid additive to accelerate a set-delayed or heavily retarded cement is dependent, upon the compositional makeup of the liquid additive as well as the 25 compositional makeup of the set-delayed or heavily retarded cement. With the benefi t of th is disclosure, one of ordinary skill in the art should be able to formulate a liquid additive to activate and/or accelerate a set-delayed or heavily retarded cement composition.

[0026] The formulation of the liquid additive is a delicate balance that correlates with the specific compositional makeup of the set-delayed cement composition. The amount 30 of the monovalent salt and the polyphosphate must he carefully balanced in relation to the dispersant. A liquid additive with an irregular mixture of components may lead to a set-delayed cement composition with less than optimal rheology. In some embodiments, the liquid additive may be added to the set-delayed cement composition in an amount of from about 1% to about 20% by weight of the set-delayed cement composition and, alternatively, 35 from about I % to about 10% by weight of the set-delayed cement com position. 11 PCT/US2014/054497 WO 2015/035281 2016266033 30 Nov 2016 [0027] The .monovalent .salt may be present in the liquid additive in an amount of about 0.1% to about 30% by weight of the liquid additive, In specific embodiments, the polyphosphate may be present in an amount ranging between any of and/or including any of •about 0.1 %, about 1.0%, about 10%, or about 30% by weight of the liquid additive. With the 5 benefit of this disclosure, one of ordinary skill in the art should be able to-formulate a liquid additive with a sufficient amount of polyphosphate for a .specific application.

[0028] The polyphosphate may be present in the liquid additive in an amount of about 0.1% to about 30% by weight of the liquid additive. In specific embodiments, the polyphosphate may be present In an amount ranging between any of and/or including any of 10 about 0.1%, about 1.0%, about 10%, or about 30% by weight of the liquid additive. With the benefit of this disclosure, one of ordinary skill in. the art should be able to formulate a liquid additive with a sufficient amount of polyphosphate fora specific application.

[0029] The dispersant may be present in the liquid additive in an amount of about 0.1% to about 90% by weight of the liquid additive, in specific embodiments, the dispersant I S may be present in an amount ranging between any of and/or incl uding any of about OJ'%, about 1%, about 50%, or about 90% by weight of the liquid additive. With the benefit of this disclosure, one of ordinary skill in the art should be able to formulate a liquid additive with a sufficien t amount of dispersant for a specific application.

[0030] The water may be present in the liquid additive in an amount of about 50% to 20 about 90% by weight of the liquid additive. In specific embodiments, the water may be present in an amount ranging between any of and/or including any of about 50%, about 60%, about 75%, or about 90% by weight of the liquid additive. With the benefit of this disclosure, one of ordinary skill in the art should be able to formulate a liquid additi ve with a sufficient amount of water for a specific application. 25 [003.1] in accordance with embodiments, the component ratio of the liquid additive may be relative to the makeup of the set-delayed cement composition. Whereby the amounts of the monovalent sait, polyphosphate, and the dispersant are therefore a .function, of the amounts of the lime, pumice, and sum total of the water (i.e. the water in the set-delayed cement -composition and any water in the liquid additive) used in the activated cement 30 composition.

[0032] Without being limited by theory, the main limitations in the formulation of the fiqukf additive are the solubility limits of the monovalent salt and the polyphosphate; and the amount of dispersant necessary to provide the cement with an acceptable rheology. The solubility limit is innate to the chosen monovalent salt and polyphosphate and therefore not 33 alterable; .however, the amount of dispersant is linked to the amounts of the mo novalent salt 12 WO 2015/035281 PCT/US2014/054497 2016266033 30 Nov 2016 10 15 20 25 and polyphosphate. The amounts of the monovalent salt/polyphosphate and the dispersant are in a pseudo direct relationship, whereby in a balanced formulation increasing the amount of one requires an increase in the. amount of the other to maintain a balanced composition. For example, if the monovalent salt and the polyphosphate amounts are increased, the dispersant must also be increased or the cement composition will be too thick to pump. On the contrary, if the dispersant amount is increased, the cement composition will be too thin and the solid particulates may settle out of solution unless the amounts of the monovalent salt and the polyphosphate are also increased. [0033] In some embodiments, the liquid additive should provide for a thickening time at wellbore conditions of greater than about 1 hour, .alternatively, greater than about 2 hours, alternatively greater than about 5 hours. In some embodiments, the liquid additive may provide a thickening time at wellbore conditions of about four to about six hours. As described above, thickening time typically' refers to the time a fluid, such as a cement composition, remains in a fluid state capable of being pumped. The liquid additi ve affects the rheology of the cement composition. 'Therefore, a liquid additive may affect the pump lime of a cement. If cement rheology is not opti mal the activated cement composition may be too thick or too thin, and therefore would be unsuitable for the desired pump time. [0034] In some embodiments, the liquid additive may provide a set-delayed or heavily retarded cement with desirable 24-hour mechanical properties. Desirable mechanical properties include 24 hour compressive strength that is greater than 250 psi, a uniform density fix. no settling), and the absence of any free' fluid. [0035] "Without being limited by theory, a description of a mechanism for activation of a lime and pumice set-delayed cement composition using a set-delayed cement activator comprising a combination of sodium sulfate and sodium hexametaphosphate is provided, it is believed that the sodium sulfate produces sodium hydroxide upon reaction with the lime. This .reaction causes a resul ting rise in the pH of the slurry and consequently an increase in the rate of dissolution of silicon dioxide. Cement hydration rate has a direct relationship with the proportion of free silicates and/or aluminosilicates, Sodium hexametaphosphate chelates and increases the dissolution rate of calcium, hydroxide. The combination of sodium sulfate and sodium hexametaphosphate creates a synergy -in various compositions of set-delayed cement compositions that provides better results than the singular use of either cement set activator.

[0036] The cement set activator may he added to embodiments of the set-delayed cement composition in an amount sufficient' to induce the set-delayed cement composition to 35 set into a hardened mass. In certain embodiments, the cement set activator may be added to PCT/US2014/054497 WO 2015/035281 2016266033 30 Nov 2016 the set-delayed cement composition in an amount in the range of about 0.1% to about 20% by weight of the pumice, in .specific embodiments, the cement set acti vator may be present in an. amount ranging between any of and/or including any of about 0.1%, about }.%, about 5%, about 1.0% about 15%, or about 20% by weight of the pumice. One of ordinary skill in the 3 art, with the benefit of this disclosure, will recognize the appropriate amount of cement set activator to include, lor a chosen application.

[0037] As will be appreciated by those of ordinary skill in the art, embodiments of the set-delayed cement compositions may be used in a variety--of subterranean operations, including primary and remedial cementing. In some embodiments, a set-delayed cement 10 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 15 into the subterranean formation, into a near wellbore region surrounding the wellbore, or into both. Embodiments may further include·'.activation of the set-delayed cement composition. The activation of the set-delayed cement composition may comprise, for example, the addition of a cement set activator to the set-delayed cement composition.

[0038] in some embodiments, a set-delayed cement composition may be provided 20 that comprises water, pumice, hydrated lime, a set retarder, and optionally a dispersant. T he set-delayed cement composition may be stored, for example, in a vessel or other suitable container. The set-delayed cement composition may be permitted to remain in storage for a desired time period. For example, the set-delayed cement composition may remain in storage for a time period of about 1 day or longer. For example, the set-delayed cement 25 composition may remain in storage for a time period of about 1 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 tor a time period in a range of from about 1 day to about 7 days or longer. Thereafter, the set-delayed cement 'composition may be activated, for example, by 30 addition of a cement set activator, introduced into a subterranean formation, and allowed to set therein.

[0039] So primary cementing embodiments, for example, embodiments of the set-delayed cement composition may be introduced into an annular space between a conduit located in a wellbore and the walls of a wellbore (and/or a larger conduit in the wellbore), 35 wherein the wellbore penetrates the subterranean formation. The set-delayed cement 14 PCT/U S2014/054497 WO 2015/035281 2016266033 30 Nov 2016 composition may be allowed to set in the annular space to form an annular sheath of hardened cement. The set-delayed cement composition may form a barrier that prevents the migration of fluids in the wellbore. The set-delayed cement composition may also, for example, support the conduit in the wellbore. 5 [0040] In remedial cementing embodiments, a set-delayed cement composition may be used, for example, in squeeze-cementing operations or in the placement of cement pings. By way of example, the set-delayed composition may be placed in a wellbore to plug an opening (e.g„ a void or crack) in the formation, in a grave! pack, in the conduit in the cement sheath, and/or between the cement sheath and the conduit (e.g,, a microannulus). 10 [0041] An embodiment comprises a method of cementing comprising: providing a set-delayed cement composition comprising water, pumice, hydrated lime, and a set retarder; activating the set-delayed cement composition with a liquid additive to produce an activated cement composition, wherein the liquid additive comprises a monovalent salt, a polyphosphate, a dispersant, and water; and allowing the activated cement composition to 15 set.

[0042] An embodiment comprises an activated cement composition comprising: water; pumice; hydrated lime; a set retarder; a monovalent salt; and a polyphosphate.

[0043] .An embodiment comprises a cementing system comprising: a set-delayed cement composition comprising: water, pumice, hydrated lime, and a set retarder; and a 20 liquid additive for activation of the set-delayed cement composition comprising; water, a monovalent salt, a polyphosphate, and a dispersant, [0044] Referring now to FIG. 1, the preparation of a set-delayed cement composition in accordance with example embodiments will now be described, FIG. 1. illustrates a system 2 for the preparation of a setidelayed cement composition and subsequent 25 delivery of the composition to a wellbore in accordance with certain embodiments. As shown, the set-delayed cement composition may be mixed in mixing equipment 4, such as a jet mixer, re-circulating mixer, or a batch mixer, for example, and then pumped via pumping equipment 6 to the wellbore. In some embodiments, the mixing equipment 4 and the pumping equipment 6 may be disposed on one or more cement trucks as will be apparent to 30 those of ordinary skill in the art, In some embodiments, a jet mixer may be used, for example, to continuously mix the lime/settable material with, the water as it is being pumped to the wellbore. In set-delayed embodiments, a re-circulating mixer and/or a batch mixer may be used to mix the set-delayed cement composition, and the activator may be added to the mixer as a powder prior to pumping the cement composition downhole. Additionally, 35 batch mixer type units, for the slurry may be plumbed in line with a separate tank containing 15 PCT/US2014/054497 WO 2015/035281 2016266033 30 Nov 2016 a cement set activator. The cement set-activator may then be fed in*line with the slurry as it is pumped out of the mixing unit.

[0045] 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 5 illustrates surface equipment '10 that may be used in placement of a set-delayed cement composition in accordance with certain embodiments. It should be noted that while FIG, 2A generally depicts a land-based operation, those skilled in the art will readily recognise 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. 10 As illustrated by FIG. 2A, the surface equipment 10 may include a cementing unit .12, which may include one or more cement trucks. The cementing unit 12 may include mixing equipment 4 and pumping equipment 6 (e.g.. FIG. I) as will be apparent to those of ordinary skill in the ait. The cementing unit 12 may pump a set-delayed cement composition 14 through a feed pipe 16 and to a cementing head 18 which conveys the set-delayed .cement 15 composition 14 downhole.

[0046] Fuming now-to FIG. 2B, the set-delayed cement composition 14 may he placed into a subterranean formation 20 in accordance with example embodiments. As illustrated, a wellbore 22 may be drilled into the subterranean formation 20. While wellbore 22 is shown extending generally vertically into the subterranean Formation. 20, the principles 20 described herein are also applicable "to wellbores that extend at an angle through the subterranean formation 20, such as horizontal and slanted wellbores. As illustrated, the wellbore 22 comprises walls 24. In the illustrated embodiment, a surface casing 26 has been inserted into the wellbore 22. The surface casing 26 may be cemented to the walls 24 of the wellbore 22 by cement sheath 28, In the illustrated embodiment, one or more additional 25 conduits (e.g,, intermediate easing, production easing, liners, etc,), shown here as casing 30 may also be disposed in the wellbore 22. As illustrated, there is a wellbore annulus 32 formed between the casing 30 and. the wails 24 of the wellbore 22 and/or the surface easing 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. 30 [0047] With continued reference to FIG, 2B, the set-delayed cement composition 14 may be pumped down the interior of the casing 30. The set-delayed cement composition .14 may be allowed to flow down the interior of the casing 30 through the casing shoe 42 at the bottom of the easing 30 and up around the easing 30 into the wellbore annulus 32.1'he set-delayed cement composition 14 may be allowed to set in the wellbore annulus 32, lor 35 example, to form a cement sheath that supports and positions the casing 30 in the wellbore 16 PCT/US2014/054497 WO 2015/035281 2016266033 30 Nov 2016 22, While not illustrated, other techniques may also be utilized for introduction of the set-delayed cement Composition 14. By -way of example, reverse circulation techniques may be used that include introducing the set-delayed cement composition 14 into the subterranean formation 20 by wav of the wellbore annulus 32 instead of through the casing 30. 5 [0048] As it is introduced, the set-delayed cement composition 14 may displace other fluids 36, such as drilling fluids and/or spacer fluids that may be present in the interior of the casing 30 and/or the wellbore annulus 32. At least a portion of the displaced fluids 36 may exit the wellbore annulus 32 via a flow line 38 and be deposited, for example, in one or more retention pits 40 (e.g., a mud pit), as shown on .FIG. 2A. Referring again to FIG. 28, a 10 bottom plug 44 may be Introduced into the wellbore 22 ahead of the set-delayed cement composition 14, for example, to separate the set-delayed cement composition 14 from the fluids 36 that may be inside the casing 30 prior to cementing. After the bottom plug 44 reaches the landing collar 46, a diaphragm or other suitable device should rupture to allow the set-delayed cement composition 14 through the bottom plug 44. la MG. 28, the bottom 15 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 cemen t composition 14 through the bottom plug 44.

[0049] The exemplary set-delayed cement compositions disclosed herein may 20 directly or indirectly affect one or more components or pieces of equipment associated with the preparation, delivery, recapture, recycling, reuse, and/or disposal of the disclosed set-delayed cement compositions. For example, the disclosed set-delayed cement compositions may directly or Indirectly affect one or more mixers, related mixing equipment, mud pits, storage Facilities or units, composition separators, heat exchangers, sensors, gauges, pumps, 25 compressors, and the like used generate, store, monitor, regulate, and/or recondition the exemplary set-delayed cement compositions. The disclosed set-delayed cement, compositions may also directly or indirectly affect any transport or delivery equipment used to convey the set-delayed cement compositions to a well site or downhole such as, for example, any transport vessels, conduits, pipelines, trucks, tubulars, and/or pipes used to compositionally 30 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 oompositiom, and any sensors tie., pressure and temperature), gauges, and/or combinations thereof and the like. The disclosed set-delayed cement '35 compositions may also directly or indirectly affect the various downhole equipment and 17 PCT/US2014/054497 WO 2015/035281 2016266033 30 Nov 2016 tools that may come into contact with the set-delayed cement compositions such as, but not limited to, wellbore casing, wellbore liner, completion string, insert: sitings, 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, 5 turbohxers, seratehers, 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 10 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.

[0050] To facilitate a better understanding of the present embodiments, the 15 following examples of certain aspects of some embodiments are given, in no way should the following examples be read to limit, or define, the entire scope of the embodiments, EXAMPLES Example 1 20 [0051 ] The following example describes an example liquid additive composition for use with an example set-delayed cement composition. For this example, the liquid additive was added to the set delayed cement composition In the amount of 8% of the total mass of the combined hydrated lime and pumice. Alter activation, the activated set-delayed cement composition had a thickening time of 5.5 hours at HKFF, The thickening time was measuring 25 using a pressurized eonsistometer at 10O°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. As discussed above, varying the concentration of the dispersantwithout adjusting the monovalent salt and polyphosphate to compensate may produce an activated slurry with less than optimal rheology and may alter 30 the thickening time.

[00521 The example set-delayed cement composition comprised water; DS-325 lightweight aggregate pumice, available from 'Hess Pumice Products, Inc,, Malad, Idaho; hydrated lime; Liquiraent 55811^ dispersant, available from BASF Corporation, Houston, Texas; and Micro Matrix4 cement retarder (MMCR), available from Halliburton Energy 18 PCT/US2014/054497 WO 2015/035281 2016266033 30 Nov 2016

Services, Inc,, Duncan, Oklahoma, The compositional makeup is presented in Table I below. The amounts listed in Table I are shown as a percentage by weight of the pumice.

Table I

Example Set-Delayed Cement Composition

Component % by weight of pumice Water 60 Pumice 100 Hydrated lime 20 Dispersant 0.7 Retarder ! .26 5 [0053] The example liquid additive comprised water,;», monovalent (sodium sulfate), a polyphosphate (sodium hexametaphosphate), and Liquiment 5581dispersant. The compositional makeup is presented in Table 2 below. The amounts listed are shown as a percentage of the total composition of the liquid additive.

Table 2 10 Example Liquid Additive

Component Weight % of Liquid Additive Water 68.7 Monovalent Salt 13.7 Polyphosphate 13.7 Dispersant 3.4

Example 2 [0054] In this example, a series of six liquid additive samples were prepared for use with an example set-delayed cement composition. The composition for the set-delayed 15 cement composition is presented in Table 3 below, in Table 3, “%bWP* stands lot “percentage by weight ;of pumice” and “gal/sk” stands for “gallons per sack 46 lb. sack of pumice,” The liquid additive comprised water, a monovalent salt (sodium sulfate), a polyphosphate (sodium hexametaphosphate), and Liquiment 558 I F® dispersant The water, monovalent salt, and polyphosphate amounts were held constant as shown in Table 4 below, 20 The dispersant concentration was varied each of the six samples as shown in Table 5 below,

The liquid additive from Table 4 was added to the set-delayed cement composition from 19 PCT/US2014/054497 WO 2015/035281 2016266033 30 Nov 2016

Table 3 such that the liquid additive comprised 10% of the combined weight of the set-delayed cement composition and the liquid additive.

Table 3 5 Example Set-JMayed Clement Composition

Component Amount Units Water 64.1 %bwP Pumice 100 %bwP Hydrated Lime .19.8 %bwP Coatex 1.8 %bwP MMCR 0.06 gal/sk MicroMax 2.06 %bwP HR-5 0.516 %bwi>

Table 4

Example Liquid Additive

Component Wt% of total sum of the water, monovalent salt, and the polyphosphate Water 83,33 Monova le nt Sal t 8.33 Polyphosphate 8,33 Dispersant X

[0055] The dispersant amounts varied from a range of 0.()()% to 4.3%, The rheology 10 of the shinies also varied based on the amount of dispersant present since the monovalent salt and polyphosphate amounts were held constant. To reiterate, the dispersant amount is a percentage of the total activated composition. After preparation, the rheological properties of the samples were determined using a Model 35A Farm Viscometer and a No. 2 spring with a Fann Yield Stress Adapter, in accordance with the procedure set forth in API RP Practice 15 108-2, Recommended Practice for Testing Well Cements, The data is presented in Table 5 below. 1'he rheological data shown in 'fable 5 are apparent viscosity values measured at a hear rate of 100 fl/sec). 20 PCT/US2014/054497

Table 5

Dispersant Amount -vs. Rheology | Sample # Dispersant Amount Rheology in eentipoise I 1 0.00 2704 2 0,45 754 13 0.68 468 4 10.90 390 1 5 2.4 286 | 6 4.3 260 WO 2015/035281 2016266033 30 Nov 2016 [0056] Example 2 illustrates that varying the dispersant amount,, without compensating by-adjusting the monovalent sail and the polyphosphate· amounts, may create 5 slurries with less than optimal rheologies, [0057] Slurry Sample l from Table 5 was unworkable and was not pourable. Archimedes tests were performed for the remaining 5 slurries. In order to do the Archimedes tests, each of the samples was poured into. 2” x 4” eylinders and left to set at 140°F for 24 hours. The set samples were then cut into three equally spaced parts along the length of the 10 eylinders. Using the Archimedes principle of density and displacement, the densities of the samples were determined and recorded in units of ib/gai. The results are presented in Table .6 below.

Table 6 15 Sample Density Measurements

Sample #· Top Middle Bottom i N/A. N/A N/A 2 1Ϊ .71 11.78 1.1,84 3 12.11 12.14 12.18 4 12.3 12.3 12.4 5 12.19 12.19 12.20 6 12.06 12.3 12.7 [0058] Samples 2-5 had no significant settling issues. Sample 6 did display settling. In general» the more 'dispersant that is added, the .less viscous the cement slurry will be. Sample 5 possessed the best slurry characteristics and would be the optimal choice compared to the other 5 samples on this measure alone. The other slurries could potentially be optimal 20 when such factors as cost and early mechanical strength development are taken into account. 21 WO 2015/035281 PCT/US2014/054497 2016266033 30 Nov 2016

Example 3 [0059] The slurry composition presented in Table 3 above was used as an example set-delayed cement composition. The example liquid additive formulation however, is 5 different from the one presented in Table 4. fable 7 lists a new liquid additive formulation specific to this example.

Table 7 Example Liquid Additive Component Wt% of total sum of the water, monovalent salt, and the polyphosphate Water 87.5 Monovalent Salt 6.25 'Polyphosphate 6.25 Dispersant X 10 [0060] Table 8 depicts the different values for the dispersant described in 'fable 7. Four different dispersant amounts were used. The dispersant concentration is a percentage of the total weight of the activated slurry. The dispersant amount ranged from 0.0% to 4.3%« After preparation, the rheological properties of the samples were determined using a Model '35 A Fan» Viscometer and a No. 2 spring with a Farm Yield Stress Adapter, in accordance 15 with the procedure set forth in API RP Practice 10B-2, Recommended Practice for Testing Weil Cements. The data is presented in Table 8 below. The rheological data shown in Table 8 are apparent viscosity values measured at a shear rale of 100 (1 /sec). 20

TableR Dispersant Amount vs. Rheology

Sample # Dispersant Amount Rheology in ceniipoise 7 0.00 1274 8 0.45 416 9 0,68 312 10 4.3 234 1006!] Arehimec es tests were performed for the 4 slurry samples, la order to do the

Archimedes teste, each of the samples was cut into three equally spaced parts. Using the ?? WO 2015/035281 2016266033 30 Nov 2016 PCT/US2014/054497

Archimedes principle of density and displacement, the densities of the samples were determined, and recorded in uni ts of Ib/gaL The results are presented in 'fable 9 below. 5 Densities of Samples Described in Table 8 J Sample# Top Middle Bottom 7 .1 .(.80 11,80 11,86 8 12.04 12.06 12,06 9 12.15 12,19 12,31 I 10 11.7 12,2 12.8 [()0:62] Significant settling occurred in Samples 9 and 10,. representing. 0.6.$%' -and •4.3% dispersant respectively, in comparison with Example 2, this indicates that reducing the amount of liquid additive added to the sample may also cause the optimum liquid additive dispersant concentration to change. Here the optimum concentration was 0,45% dispersant, 10 whereas in the previous example the opti mum concentration was 2,4%.

Example 4 [0063] in this example, the slurry described in Table 3 was used for the base composition. The liquid additive formulation is described in Table 10 below. The .monovalent salt was sodium 'sulfate. The polyphosphate was sodium hexametaphosphate. IS The dispersant was Coatex 1702, available From Coatex Inc., Chester, South Carolina. As illustrated in Table 11, the dispersant concentration varied from 0,45% to 8,33%.

Table 10

Example Liquid Additive

Component Wt% of total sum of the water, monovalent salt, and the polyphosphate Water 76.9 Monovalent Salt 1U Polyphosphate 11.5 Dispersant X 20 WO 2015/035281 PCT/US2014/054497 2016266033 30 Nov 2016

Table Π Dispersant Concentration per Sample Sample Number Dispersant Amount (g) Wt% of total sum of the water, monovalent: salt, and the polyphosphate 1 5 0,45 15 1.35 3 30 2.65 4 70 5.98 5 100 8,33 [0064] in order to determine the effect of varying the dispersant concentration on the compressive strength of set samples, the compressive strength of each sample was measured 5 after five days. The destructive compressive strength was measured: by allowing the samples to cure in a 2” by 4W plastic cylinder that was placed in a; water hath at ί 90c F to form set cylinders. Immediately after removal from the water bath, destructive compressive.strengths were determined using a mechanical press: In accordance with API RP I OB-2* Remmmemied Practice .for Testing Well Cements. The results of this test are set forth below in Table 12, in 10 units of psi, The reported compressive strengths are an average for two cylinders: of each sample. 15

Table 12 Compressive Strength Tests Sample Number Compressive Strength (psi) 1 964 2 778 3 398 4 411 5 34 [0065] Varying the dispersant concentration had a direct impact on the compressive strength of the samples. This effect was stronger than the sett l ing effect of adding dispersant. It therefore stands to reason that the dispersant can have an antagonistic effect on the sodium hexamefaphosphate activation of the extended iife slurry when retarded with the phosphonate, nitrllotrisfnethylenetriphosphouic acid.

[0066] Archimedes tests were performed for Samples '.1-5. Each of the samples was poured info 2” x 4” cylinders: and left to set at 140°F for five days. The set samples were 24 PCT/US2014/054497 WO 2015/035281 2016266033 30 Nov 2016 then cut into three equally spaced parts along the length of the cylinders. Using the Archimedes principle of density and displacement the densities of the samples were determined and recorded. The results are presented in Tables 13? 17 below, where PPG is the symbol for units of Ib/gal.

Table 13

Sample 1 Archimedes Test | Volume imL) Weight (g) Density (g/mL) Density (PPG) Top 1 65,96 1 ............. 99.18 1.5036 12.5 Middle 60.55 91,12 1.5049 12.5 Bottom 64,:29 96.45 1.5002 12.5 10 Table 14

Sample 2 Archimedes Test

Volume (mL) Weight (g.) Density (g/mL) Density (PPG) Top 54.31 81,58 1.5021 12.5 Middle | 67,38 ί 00.97 1.4985 12,5 Bottom. | 54,18 81.53 1,5048 12.5

Table IS

Sample 3 Archimedes Test

Volume (mL) Weight (g) Density (g/mL) Density (PPG) Top 60.56: 90.98 1.5023 12.5 Middle 57.44 85.84 1.4944 12.4 Bottom 61.3 91.8 1.4976 12.5

Table 16

Sample 4 Archimedes Test

Volume (ml) Weight (g) Density (g/mL) Density (PPG) fop 60.63 89.53 1.4767 12.3 Middle 58.83 87.83 1.4929 12.4 Bottom 62.12 93.05 1.4979 12.5 25 PCT/US2014/054497

Table 17

Sample 5 Archimedes lest I Volume (ml) Weight (g) Density (g/mL) Density (PPG) Top | 64.04 94.09 1.4692 12.2 Middle 1 56.47 82.6 1.4627 12.2 Bottom j 59.5 87.91 1.4775 12.3 [0067] Samples 4 ami 5 displayed slight settling behavior. WO 2015/035281 2016266033 30 Nov 2016

Example 5 [0068] in this example, ten sample liquid additives were prepared for use with a set-delayed cement composition; The compositional makeup of the set-delayed cement Composition is presented in Table 18 below. The liquid additive comprised water, .a 10 monovalent salt in the form of sodium sulfate, a polyphosphate in the form of sodium hexametaphosphate. and Liquimeut 5581?* dispersant It should be noted that the percentages of the monovalent sail and the polyphosphate were held constant throughout the experiment while the dispersant, concentration was varied. The composition of the liquid additive is illustrated below in Tabic 19. All of the listed .amounts are shown as a percentage 15 of the total composition of the liquid additive. The liquid additive from Table 19 was added to the set-delayed cement composition described in Table 18 such that the monovalent salt, and polyphosphate were present in the combined amount of 1.25 % bwP or 1.06% bwP,

Table 18

Example Set-Belayed Cement Composition

Component Amount units Water 60.0 %bwP Pumice 100.0 %bwP Hydrated Lime 20 %bwP Liquiment 5581.F 0,6 %bwP MMCR 0.06 ga'I/sk MicroMax 2.0 %bwP HR-5 0,5 %bwP SA-1.015 0,035 %bwP 26 PCT/US2014/054497

Table-19

Example Liquid Additive

Component Wt% of total sum of the water, monovalent salt, and the polyphosphate Water Si.59 .Monovalent Salt 8.53 Polyphosphate 8,53 Dispersant X WO 2015/035281 2016266033 30 Nov 2016 [0069] The dispersant amount varied from a range of 0.10% to 1,39%. The 5 thickening time of the slurries varied based on the amount of dispersant, since the monovalent salt and polyphosphate were held constant, [0070] 'The compressive strength and thickening times of each sample were measured. The destructive compressive strength was measured by allowing the samples to cure in a 2” by 4” plastic cylinder that was placed in a water bath at 190aF to form set 10 cylinders, immediately after removal from the water bath, destructive compressive strengths were determined using a mechanical press in accordance with API RP 10B-2, Recommended Practice for Testing Well Cements. The 'results of this test are set forth in Table 20 below. The reported compressive strengths are an average for three cylinders of each sample. TABLE 20 15 Dispersant Amount vs. Thickening rime and Compressive Strength

Sample Number Monvalent Salt and Polyphosphate Amount (%bwP) Dispersant Amount (% bwP) Thickening Time (hnrain) Compressive Strength (psi) 1 1,25 0.10 1:59 Ϊ 047 9 1.25 0.25 2:18 .. 3 1.25 0.49 2:54 ~ 4 1.25 0.88 3:51 741 5 1.25 1,15 4:07 824 6 1.25 1.41 4:53 1146 7 i .00 0.08 2:46 1201 8 1,00 Θ.87 4:44 1066 9 1.00 1.13 4:48 635 10 1.00 1.39 11:17 672 PCT/US2014/054497 WO 2015/035281 2016266033 30 Nov 2016 Γ007ί1 Varying the dispersant concentration of the liquid additive allowed the thickening time of the set-delayed cement composition to be controlled. This added benefit was realized through the observation that the thickening .time of the cement: samples increased with increasing dispersant amount. For the liquid additive samples containing 5 1.25% bwP monovalent salt-polyphosphate, the relationship is almost linear as shown in FIG. 3.

[0072] it should be understood that the compositions and methods are described in terms of “comprising,” “containing,” or “jncluding” various components or steps, the compositions and methods can also “consist essentially of or “consist of the various 10 components and steps. Moreover, the indefinite articles “a” or “anf as used in the claims, are defined herein to mean one or more than one of the element that it introduces.

[0073] For the sake of brevity, only certain ranges are explicitly disclosed herein. However, ranges from any lower limit may he combined with any upper limit to. recite a range not explicitly recited, as well as, ranges from any lower limit may be combined with 15 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 bf or, 20 equivalently·, “from approximately a to bf 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. 25 [0074] Therefore, foe present embodiments are well adapted to attain foe ends and advantages mentioned as well as those that am inherent therein. T he particular embodiments disclosed above are illustrative only, as the present embodiments may be modified and practiced in different but equivalent manners apparent to those skilled in foe art having the benefit of the teachings herein. Although individual embodiments are discussed, all 30 combinations of each, embodiment are contemplated and covered by the disclosure. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. If is therefore evident that the particular illustrative embodiments disclosed above maybe altered 35 or modi lied and all such variations are considered within the scope and spirit of the present 28 PCT/US2014/054497 WO 2015/035281 2016266033 30 Nov 2016 disclosure. If there is any conflict in the usages of a word or term in this specification and one or more pateni(s) or other documents that may be incorporated herein by reference, the definitions that are consistent with this specification should be adopted. 29

Claims (6)

1. The claims defining the invention are as follows:

   1. An activated cement composition comprising water; pumice; hydrated lime; a set retarder; a monovalent salt; and a polyphosphate.
2. 2. An activated cement composition according to claim 1 wherein the polyphosphate comprises sodium hexametaphosphate.
3. 3. An activated cement composition according to claim 1 or claim 2 wherein the monovalent salt comprises sodium sulfate.
4. 4. An activated cement composition according to any one of claims 1 to 3, further comprising a dispersant.
5. 5. An activated cement composition according to claim 4 wherein the dispersant comprises a polycarboxylated ether.
6. 6. An activated cement composition according to any one of claims 1 to 5 wherein the ratio of the monovalent salt to the polyphosphate is from about 5:1 to about 1:25.