CA2920756A1

CA2920756A1 - Foaming of set-delayed cement compositions comprising pumice and hydrated lime

Info

Publication number: CA2920756A1
Application number: CA2920756A
Authority: CA
Inventors: Kyriacos Agapiou; Thomas Jason Pisklak; Samuel J. Lewis; Peter James Boul; Pauline Akinyi Otieno; Lance Everett Brothers
Original assignee: Halliburton Energy Services Inc
Current assignee: Halliburton Energy Services Inc
Priority date: 2013-09-09
Filing date: 2014-09-08
Publication date: 2015-03-12
Anticipated expiration: 2034-09-08
Also published as: WO2015035280A1; RU2655669C2; GB2535857B; AU2018232978B2; BR112016002545A2; AU2018232978A1; NO20160086A1; CA2920756C; AU2014317923B2; RU2016103916A; AU2014317923A1; MX2016001651A; GB2535857A; AU2016222404B2; AU2016222404A1; GB201600816D0

Abstract

A variety of methods and compositions are disclosed, including, in one embodiment a method a cementing in a subterranean formation comprising: providing a set-delayed cement composition comprising water, pumice, hydrated lime, and a set retarder; foaming the set-delayed cement composition; activating the set-delayed cement composition; introducing the set-delayed cement composition into a subterranean formation; and allowing the set-delayed cement composition to set in the subterranean formation. Additional methods, foamed set-delayed cement composition, and systems for cementing are also provided.

Description

FOAMING OF SET-DELAYED CEMENT COMPOSITIONS COMPRISING
IMICE AND HYDRATED LIME
BACKGROUND
[0001.1 Cement compositions may be used in a. variety of subterranean operations.
For example, in subterranean µvell construction, a pipe string (e.g., casing, liners, expandable tubular's, 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 annulusbetween the walls of the w.ellbore and the exterior surface of the pipe string disposed therein. The 1( cement composition .may set in the annular space, thereby tbrming an annular sheath of hardened, substantially impermeable cement (i.e., a cement sheath) that may support and position the pipe string in the wellbore and may bond the exterior surface of the pipe string;
to the subterranean formation. Among other things, the cement sheath surrounding the pipe string functions to prevent the migration of fluids in the annulus, as well as protecting the pipe string:from corrosion. Cement compositions also May be used in remedial cementing methods, for example, to seal cracks or holes in pipe strings or cement sheaths., to seal highly permeable fbrmation zones or fractures, to place a cement plut.t, 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 remaining in a pumpable fluid state for at least about one day (e.g., at least about 7 days, about 2 weeks, about

2 years or more) at room temperature (e.g., about SO F) in quiescent storage. When desired Ibr use, the set-delayed cement compositions Should be capable of being activated whereby reasonable compressive strengths are developed. For example, a cement set accelerator may be added to a set-delayed cement composition whereby the composition sets into a hardened mass.
Among other things, the set-delayed cement composition may be suitable for use in wellbore applications, fbr example, where it is desired to prepare the cement composition in advance.
This tn.i ìIlcn for example, the cement composition to be stored prior to its use. In addition, this may allow, 'fbr example, the cement composition to be prepared at a convenient location and then transported to the job site. Accordingly, capital expenditures may be reduced due to a reduction in the need for on-site bulk storage and mixing equipment. This may be particularly useful for offshore cementing operations where space onboard the vessels may be limited.
1000311 While set-delayed cement compositions have been developed heretofore, challenges exist with their successful use in subterranean cementing operations. For example, set-delayed cement compositions prepared with Portland cement may have undesired gelation issues which can limit .their use an effectiveness in cementing operations. Other set-delayed compositions that have been 'developed, .Ibr example, those compiisint! hydrated lime.' and quartz, may be effective in some operations but tilt:1y have limited use at lower temperatures as they -may 1.10i develop sufficient Compressive strength when used in subtetTanean tbrinations having lower bottom hole static temperatures.
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BRIEF DESCRIPTION OF THE DRAWINGS
[00011 These drawings illustrate certain aspects of some of the embodiments of the present trethOd and should not be used to limit or define the method.
[00021 FIG. uStrates a system for preparation and delivery of a set-delayed ficement composition to a wellbore in nceoMance with certain embodiments.
[00031 .F10. 2A illustrates surtke equipment that may he used in placement of a set-delayed cement composition in a wellbore in .accordance with certain embodiments.
[00041 FIG. 2B illustrates placement of a set-delayed CCMCM compositiOn into a wellbore annulus in accordance withseertain embodiments,

3 DESCRIPTION OF PREFERRED EMBODIMENTS
[00051 The c...xample embodiments relate to subterranean c.ementing operations and, more particularly, ìn certain embodiments, to set -delayed cement compositions and methods of using set-delayed cement compositions in subterranean formations, [0006] Embodiments of the set-delayed cement compositions may generally comprise water, pumice, hydrated lime, kind a set retarder. Optionally, the set-delayed cernent 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 tot an extended period of time. For example, the set-delayed cement compositions may remain in a pumpable fluid state for at least about I day, about 2 weeks, about 2 years, or longer.
Advantageously, the set-delayed cement compositions may develop reasonable compressive strengths after activation at relatively low temperatures. While the set-delayed cement compositions may be suitable for a number of subterranean cementing operations, they may be particularly suitable for use in subterranean ibrmations having relatively low bottom hole static temperatures, e.g., temperatures less than about 200 F or ranging from about 1001? to about 200T. In alternative embodiments, the set-delayed cement compositions may be used in subterranean formations having bottom hole static temperatures up to 450F
or higher.
[00071 The water used in embodiments of the set-delayed cement compositions may be from any source provided that it does not contain an excess of compounds that may undesirably affect other components in the set-delayed cement compositions.
For example, a set-delayed cement composition may comprise fresh water or salt water, Salt water generally may include one or more dissolved salts therein and may be saturated or unsaturated as desired for a particular application. Seawater or brines may be suitable for use in embodiments. Further, the water may be present in an amount sufficient to form a pumpable slurry. In certain embodiments, the water may be present in the set-delayed cement composition in an amount in the range of from about 33% to about 200%
by weight of the pumice. In certain embodiments, the water may be present in the set-delayed cement compositions in an amount in the range of from about 35% to about 70% by weight of the pumice. One of ordinary skill in the art with the benefit of this disclosure.
Skill recognize the appropriate amount of water for a chosen application.
100081 Embodiments of the set-delayed cement compositions may comprise pumice.

Generally, pumice is a volcanic rock that can exhibit cememitious properties in thart it may set and harden in the presence of hydrated lime and water. The pumice may also be ground, Generally.. the pumice may have any particle size distribution as desired for a particular

4 application. In certain embodiments, the pumice may have a mean particle size in a range of from about 1 micron to about 200 microns. The mean particle size corresponds to d50 values as measured by particle size analyzers such as those manufactured by Malvern instruments, Worcestershit-e, 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 purniee may have a mean particle size of less than about 15 microns. An example of a suitable pumice is available from Hess Pumice Products, Inc., Malad, Idaho, as 1)S-325 lightweig,ht 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 fiir a chosen application, 100091 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 Corm the hydrated lime. The.
hydrated lime may be included in embodiments of the set -delayed cement compositions, for example, to thrill a hydraulic composition with the pumice. For example,. the hydrated lime may be included in a pumice-to-hydrated-lime weight ratio ()Cahoot 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 alvut 10% to about 100% by weight of the pumice:, fOr example. hi SOMe embodiments, the hydrated lime may be present in an amount ranging between any of andlor 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 cetnent composition may consist essentially of the pumice and the hydrated lime. For example:, the cementitious components may primarily comprise the pumice and the hydrated lime without any additional components (e.g., Portland cement, .fly ash, .slatz cement) that hydraulically set in the presence of water. One of ordinary skill in the art, with the benefit of this disclosure, will rec,ognize the appropriate amount of the hydrated lime to include for a chosen application.
[00101 Embodiments of the set-delayed cement compositions may comprise a set retarder. A broad variety of set retarders may be suitable: for use in the set-delayed cement compositions. For example, the set retarder may comprise phosphonic acids, such as ethylenediamine tetra(methylene phosphonic acid), diethylenetriamine penta(methylene phosphonic acid), etc:; lignosulfonates, such as sodium lignosulfonate, calcium lignosulfonate, etc.; salts such as stannous sulfate, lead acetate, monobasic calcium phosphate, organic acids, such as citric acid. tartaric acid, etc.; cellulose derivatives such as hydroxyl ethyl cellulose (NE() and carboxymethyl hydroxyethyl cellulose (CMHEC);
synthetic co- or ter -polymers comprising sulfonate and carboxylic acid groups such as sulfonate-funetionalized 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, phonic acid derivatives. One example of a suitable set retarder is Micro Matrie cement 1) retarder, available from Halliburton Energy Service.s, Inc. Generally, the set retarder may be present in the set-delayed ce.ment compositions in an amount sufficient to delay the setting for a desired time. In some embodiments, the set retarder may he present in the set-delayed cement compositions in an amount in the range of from about 0.t)I% to about 10% by weight of the pumice. in spedfic embodiments, the set retarder may be present in an amount =Ong, between any of andlor including any of about 0.01%, about 0.1%, about 1%, about 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 diselosure, will recognize the appropriate amount of the set retarder to include for a Chosen application.
[00111 As previously mentioned, embodiments of the set-delayed cement compositions may optionally eomptise a dispersant. Examples of suitable dispersants include, without limitation, sulfonated-formaldehyde-based dispersants (e.g., sutfonated acetone tbrmaldehyde condensate), examples of which may include Daxad 19 available from Geo Specialty Chtõ.micals, A.trihler. .Pennsylvania. Other suitable dispersants may he polycarboxylated ether dispersants such as Liquimene' 5581F and Liquimene 5141, available from BASF Corporation Houston, Texas; or Ethacryl G available from Coatex, Genay, France. An additional example of a suitable commercially available dispersant is CFR"--3 dispersant, available from lialliburton Energy Services, Inc, Houston, Texas. Of particular importance in regards to the examples that follow, is that the Liquimene 5141.
dispersant comprises 36% by weight of the polycarboxylated ether in water.
While a variety of dispersants may- be used in accordance with embodiments, polycarboxylated ether dispersants may be particularly suitable fbr use in some embodiments. Without being limited by theory, it is believed that polycarboxylated ether dispersants may synergistically interact with other components of the set-delayed cement composition. For example, it is believed that the polycarboxylated ether dispersants may react with certain set. retarders (e.g.,

6 phosphonic acid derivatives) resulting in formation of a gel that suspends the pumice and hydrated lime in the composition for an extended period of time, [0012] In some embodiments, the dispersant may be included in the set-delayed cement compositions in an amount in the range of from about 0.01% to about 5%
by weight :of the pumice. In specific embodiments, the dispersant may be present in an amount ranging between any of and/or including any of about 0.0M, about 0.19/4, 0.5%, about 194), about 2%, about i3,%, 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.
I 0 [00131 Ernbodiments of the set-delayed cement compositions may comprise a meehanical property enhancing additive. Mechanical-property-enhancing tidditives may be included in emboditnents of the set-delayed compositions to, for example, ensure adequate compressive strength and long4ertn structural integrity. These properties can he affected by the strains, stresses, tempenuure, pressure, and impact effetts from a subterranean etwironment. Examples of mechanical property enhancing additives include fibers, such as graphitic carbon fibers, glass fibers, steel fibers, mineral fibers., silica fibers, polyester fibers, polya.mide fibers, and polyolefin fibers, among others. Specific examples of graphitic carbon fibem include fibers derived from polyacrylonitrile, 'rayon, and petroleum pitch, Where used, the filechanical-property-enbta ming additives may be present in an _amount from about 0.01%
to about 5% by weight of the pumice. In specific embodiments, the mechanical-property-enhancing additives may be present. in an amount ranging between any of andfor including any of about 0.01%, about 0.1%, 0.5%, about 1%, about 29i'i), about 3%, about 4 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 mechanical-property-enhancing -additives to include for a chosen application.
[00141 Other additives suitable fOr use in subterranean cementing operations also may be included in embodiments of the set-delayed cement compositions.
Examples of such additives include:, but are not limited to, weighting :agents, lightweight additives, gas-generating additives, lost-circulation materials, filtnition-contrOl additives, fluid-loss-control additives, defoaming agents, "batting agents, thixotropie additives, and combinations thereof, in embodiments, one or more of these: additives may be added to the set-delayed cement composition atter storing but prior to placement of the set-delayed cement coMposition into a subtetTanean fbimation. A person having ordinary skill in the art,. with the benefit of this disclosure, will readily be able to determine the type and amount of additive useful for a particular application and desired result.

7 [0015] `Those of ordinary Skill in the art will appreciate that enibodiments of the set-.
delayed ceinent 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 ib/gal") to about 20 Ibiegal. In certain einbodiments, the set-delayed cement compositions may have a density in the range of from .about 8 lbfgal to about 17 lbfgal, Embodiments of the set-delayed f:Calerit compositions may be foamed or unfoamed or may comprise other means to reduce their densities, spelt as hollow micmspheres, low-density elastic beads, or other density-reducing additives known in the art. In embodiments, the density may be reduced after storing the composition, but prior to placement in a stibterranean formation, Those of ordinary skill in the art, with the benefit of this disclosure, will recognize the appropriate density for a particular -application.
[00161 As discussed above, embodiments of the set,delayed cement compositions may be foamed. Embodiments of the set-delayed cement compositions may be foamed to provide a lightweight composition that does not exert excessive fbrce on formations penetrated by the wellbore. In addition to being lightweight, a %wed composition :may also improve the ability of the composition to maintain pressure and prevent the flow of Rrnnation fluids into and through the composition during its transition time.
Foamed compositions may also be advantageous because they have low fluid loss properties, thus limiting loss of fluid circulation, Additionally, foamed compositions when set may also have a lower modulus of elasticity than non-foarned compoSitions which is often desirable as it enables the resultant set cement composition to resist stresses exerted on the composition in situ, [0017] In particular erithodiments, the set-delayed cement compOsition may be foamed at the well site. By way of example, the set-delayed cement compositions may be foamed immediately prior to use. Embodiments may be foamed with a foaming additive and by entraining gas into the set-delayed cement compositions. In particular embodiments, the foaming additive and gas may be introduced after combination of the composition with an activator. The set-delayed cement compositions may be foamed, for example, to provide a Set-delayed cement composition with a reduced density.
[0018] The gas used for foaming the composition may be any suitable gas for foaming, including, but not limited to: air, nitrogen, and combinations thereof Generally, the gas should be in an amount sufficient to form the desired foam. Foaming additives may be included in embodiments to, for example, facilitate foaming andior -stabilize the resultant foam formed therewith,

8 [0019] In particular embodiments, the fbathing additive may include a surfactant or combination of surfactants that ivtluce the surface tension of the water. By way of example, the flaming agent may cc prise an anionic, nonionic, amphoteric (including zwitterionic surfactants), cationic surfactant, or mixtures thereof Examples of suitable foaming additives include, but are not limited to: betaines; anionic surfactants such as hydrolyzed keratin;
amine oxides such as a alkyl or alkene dimethyl amine, oxides;
eocoarnidopropyl dimethylamine oxide; methyl ester sulfonates; alkyl or alkene atnidobetaines such as cocoamidopropyl Maine: alpha-olefin sulfonates; quaternary surfactants such as trimethyltallowammonium chloride and trimethylcocoammonium chloride: C8 to C22 alkylethoxylate sulfates; and conibinations thereof. Specific: extunples of suitable foaming agents include -mixtures of an ammonium salt of an alkyl ether sulfate, a cocoattlidopropyl beta:Me surfactant, a coCoamidopropyl dimethylamine oxide surfactant, sodium chloride, and Water; mixtures of an ammonium salt of an alkyl ether sulfate surfactant, a eocoatnidopropyl hydroxysuhaine surfactant, a cocoamidopropyl dimethylamine surfacttmt, sodium Chloride, and Water; mixtures of an ethoxylated alcohol ether sulfate surfactant, an .alkyl or Acne amidopropyl betaine surfactant, and an alkyl or alkene dimethylamine oxide surfimant; aqueous solutions of an alpha-olefinie sulfonate surfactant and a betaine surfactant and combinations thereof Examples of suitable foaming additives are ZONESEALANTT" 2000 agent and Foainer 1026, both available from Hailiburton Energy Service.,,s Inc., Houston, Texas. Embodiments may be foamed within a foam quality range of between about 5% to about 80% and, more particularly, from about 18% to about 38%. As used herein, the term "foam quality" refers to the volume of entrained gas and is defined by the following. Ibrmula: Foam Quality (Total Foam Volume Liquid Volume) f Total Foam Volume.
[00201 As previously mentioned, the cement compositions may have a delayed set in that they remain in a pumpable fluid state for at least one day (e.g., at least about I day, .about 2 weeks, about 2 years, or longer) at room temperature,' in quiescent storm:. For example, the set-dcIayed cement compositions may remain in a pumpable fluid state for a period of time from about I day, about 2 weeks, about 2 years, or longer. In some embodinients, the set-delayed cement compositions may reinain in a Oumpable fluid state ibr 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, about 2 years, or longer, A fluid is considered to be in a pumpable fluid state where the fluid has a consistency of less than 70 Bearden units. of -consistency ("Bc"), as measured on a high-temperature high-pressure consistometer at room temperature (e.g... about 80 F) in accordance with the procedure for determining cement

9 thickening times set forth in API RP Practice 108-29 Recommended Phlake for Testing WW1 Cements, First Edition, July 2005.
1:0021.1 When desired for use, embodiments of the set-delayed cement compositions may be activated (e.g., by combination with an activator) to thereby set into a hardened MASS. I3y way of example, embodiments of the; set-delayed cement compositions May be activated to set to tbrm a hardened mass in a time period in the range of from about 1 our to Omit 12 hours, For example, embodiments of the set-delayed cement compositions may set to form a hardened mass in a time period ranging between any of and/or including any of about 1 day, about 2 days, about 4 days, about 6 days, .about 8 days, about 10 days, or about 12 days.
[00.22.J In some ernbodimots, the set-delayed cement compositions may set to have desirable compressive .strength after activation. Compressive strength is generally the capacity of a mate.rial or structure to withstand axially directed pushing fbrees. The compressive gtrength may be measured at a specified time after the set-delayed cement composition has been activated and the resultant composition is .maintained under specific temperattim and pressure controls. Compressive strength can be measured by either a destructive method- or ran-destructive method. The destructive method physically tests the strength of treatment fluid samples at various points in time by crushing the samples in a compression-testing machine. The compressive strength is calculated from the failure load divided by the cross-sectional area resisting the load and is reported in units of pound-foree per square inch (psi). Non-destructive methods typically .may employ an Ultrasonic Cement Analyzer rucA'), available from Fatm Instrument Company, Houston, TX.
Compressive strengths may be determined in accordance with API RI> 1013-2, Recommended Practice fiii=
Testing Well Cements, First Edition, July 2005, [0023] By way of example, the set-delayed cement composition, may develop a 24-hour compressive strength in the range of from about 50 psi to about 5000 psi, alternatively, frOm about 100 psi to about 4500 psi, or alternatively frOm about 500 psi to about 4000 psi.
In some embodiments, the set-delayed cement composition may develop a compressive strength in 24 hours of at least about 50 psi, at least abotit 100 psi, at least about 500 psi, or more, In soine entbodiments, the compressive strength values may be determined using :destructive or non-destructive methods at a temperature ranting from 100T to 200F, [0024] Embodiments may Mehl& the addition of a cement set activator to the set-delayed cement compositions, 1:-LXamples of suitable cement set activators.
include, but at -e not limited to: amines such as trietbanoiamine, diethanolamine; silicates such as sodium silicate: zinc fbrmate; calcium acetate; Groups IA and flA hydroxides such as sodium hydroxide, inagnesium hydroxide, and calcium hydroxide; Monovalent salts such as sodium chloride; divalent salts such as CaMUM chloride; nanosilica (i,e., silica having a partiele size of less than or equal to about -100 nanoineters); polyphosphates; and combinations thereof In some embodiments, a combination of the polyphosphate and a monovalent salt may be used for activation. The monovalent salt .may be any salt that dissociates to form a monovalent cation, such as sodium and potassium salts. Specific examples of suitable monovalent salts include potassium sulfate, and sodium stillate. A variety of different polyphoSphates may be used in combination with the monovalent salt for activation of the set-delayed cement compositions, including polymeric metaphosphate salts, phosphate sahs, and combinations thereof Specific examples of polymeric metaphosphate salts that my be used -include sodium hexametaphosphate, sodium trimetaphosphate, sodium tetrametaphosphate, sodiu.rn pentametaphosphate, sodittm heptametaphosphate, sodium octametaphosphate, and combinations thereof. A specific example of a suitable cernent set activator cornprises a combination of sodium sulfate and sodium hexametaphosphate. In particular embodiments, the activator may be provided and added to the set-delayed cement composition as a liquid additive, for .example, a liquid additive comprising a monovalent salt, a polyphosphate, and optionally a dispersant.
[00251 The cement set activator should be added to embodiments of the set-delayed cement coMposition in an athount sufficient to activate the set-delayed cement composition to set into a hardened mass. In certain embodiments, the cement set activator may be added to the set-delayed cement composition in an amount in the range of about P<i) to about 20%
by weight of the pumice. In specific embodiments, the cement set activator may be present in an amount ranging between any of and/or including any of. about 1.9,4, about 5%, about 10%, about 15%, or about 20% by weight of the pumice. One of ordinary Skill in the art, with the benefit of this disclosure, will recognize the appropriate ,a:mount of the cement set activator to include for a chosettapplication, [00261 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 prithary and remedial cementing. In some embodiments, a set-delayed cement 34) composition may be provided that compriSes water, pumice, hydrated lime, a set retarder, and optionally a dispersant. The set-delayed cement composition inay be introduced into a subterranean formation and allowed to set therein. As used herein, introducing the set-delayed cement coMposition into a subterranean formation includes introduction into any portion of the subterranean formation, including, without limitation, into a welIbore drilled :into the sobterronean formation, into a. near wellbore region. surrounding the weilborp, or into both. Embodiments may limber include activation of the set-delayed cement composition.
The activation of the set-delayed cement crimposition Mks( comprise, for example, the addition of a cement set activator to the set-delayed cement composition, [00271 In some embodiments, a set-delayed cement composition may be provided that comprises water, pumiee, hydrated lime, a. Set retarder-, and optionally a dispersant. The set-delayed cement composition may be stored, for example, in a vessel or other suitable container. The set-delayed cement composition may be permitted to remain in storage- Ibr a desired time period. For example, the set-delayed cement composition may remain in storage ibr a time period of about I day, about 2. weeks, about 2 years, or longer. For example, the set-delayed cetnent composition may remain in storage for a. time period of about I day, .about 2 days, about 5 days, about 7 days, about 10 days, about 20 days, about 30 days, about 40 days, about 50 days, about 60 days, about 2 years, or longer. in Some embodiments, the set-delayed cement composition may remain in storage for a time period in a range of from a.bout 1 day to about 2 years or longer. Thereafter, the set-delayed cement composition may be actiVated, for example, by addition of a eement set activator, introduced into a subterranean formation, and allowed to set therein. Optionally, the set-delayed cement composition may be foamed prior to introduction into the subterranean formation.
I00281 In primary cementing embodiments, for example, einbodiments of the set-delayed cement composition may be introduced into an annular space between a conduit located in a wellborn and the walls of a wellbore (andlor a larger conduit in the wellbore), wherein the wellbore penetrates the subterranean formation. The set-delayed cement compositiOn may be allowed to set in the annular space to .tbrm 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.
10029] :In remedial cementing embodiments, a set-delayed cement composition /nay be used, for example, in sque0t-Cementing operations or in the platement of cement plugs.
By way of example, the set,delayed composition may be placed in a wellborn to plug an opening suit as a void or crack that is in the formation, in a gravel pack, in the conduit, in

10 the cement sheath, andlor between the cement sheath and the conduit (e.g., a microannuluS).
[00301 .An example embodiment comprises a method of cementing in a subterranean fortnation comprising: providing a set-delayed cement composition comprising water, pumice, hydrated lime, and a set retarder; foaming the: set-delayed cement composition;
activating the foamed set-delayed cement .composition; introducing the foamed -Set-delayed cement composition into a subterranean formation; and allowing the foamed set-delayed cement composition to set in the subterranean formation.
[0031] An example embodiment comprises a foamed set-delayed cement composition comprising: water, pumice, hydrated lime, a foaming additive, entrained gas, and a set retarder.
[0032] An example embodiment comprises a system for cementing comprising: a set-delayed cement composition comprising: water, pumice., hydrated lime, a set retarder, a foaming additive for foaming the set-delayed cement txtmposition; a gas for tbaming the, set-delayed cement composition; and a cement set activator for activation of the set-delayed cement composition.
[0033] Referring now to Fki. 1, preparation of a set-delayed cement composition in accordance with example .embodime.nts will now be described. FIG. 1 illustrates a system 2 for preparation of a set-delayed cement composition and delivery to a wellbore in accordance with certain embodiments. As shown, the set-delayed cement composition may be mixed in mixing equipment 4, such as a jet mixer, te-circulating mixer, or a batch mixer.'for example, and then pumped via pumping equipment 6 to the wellbore. In some embodiments, the mixing equipment 4 and the pumping equipment 6 may be disposed on one or more cement trucks aS Will be apparent to those of ordinary skill M the at in some embmliments, a jet mixer may be used, for example, to continuously mix the Iimefsettable material with the water as it is being pumped to the wellbore.
[0034] Art example technique for placing a set-delayed cement composition into a subterranean formation will now be described with reference to FIGS, 2A and 213. FIG. 2A
illustrates surface equipment 10 that may be used in placement of a set-delayed cement composition in accordance with certain embodiments. It should be noted that while FIG. 2A
generally depicts a land-based operation, those skilled in the art will readily xecognize that the principles described herein are equally applicable to subsea operations that employ floating or sea-based platforms and rigs, without departing from the scope of the disclosure.
As illustrated by FIG, 2A, the surface equipment 10 may include a cementing unit 12, which may include one or more cement trucks. The cementing unit 12 may include.
mixing equipment 4 and pumping equipment 6 (e.g., FIG. 1) as will be apparent to those of ordinary skill in the art. The cementing unit 12 may pump a set-delayed cement composition 14 through a feed pipe 16 and to a cementing head 18 which conveys the set-delayed CeMera composition 14 downhole.
[0035] 'fuming now to FIG. 213, the set-delayed cement composition 14 may be placed into a subterranean formation 20 in accordance with example embodiments. As ilhtstrated, a wellhore 22 may bs drilled into the subterranean formation 20.
While wellbore 22 is shown extending generally vertically into the subterranean formation 20, the principles described herein are also applicable to wellixwes that extend at an angle through the subterranean formation 20, such as horizontal and slanted wellborn& As illustrated, the wellbore 22 comprises walls 24. In the illustrated embodiment, a surface casing 26 has been inserted into the wellbore 22. Ths surface casing 26 may be cemented to the walls 24 of the wellborn 22 by cement sheath 2s. In the illustrated embodiment, one or more additional conduits (e.g., intermediate casing, production casing, liners, etc.), ShOWil here as casing 30 may also be disposed in the wellbore 22. As illustrated, there is a wellbore tumulus 32 formed between the easing 30 and the walls 24 of the wellbore 22 andlor the surface casing 26. One or more centralizers 34 may be attached to the casing 30, I'm example, to centralize the casing 30 in the wellbore 22 prior to and during the cementing operation.
[0036] with continued reference to FKi. 2B, the set-delayed cement composition 1.4 may be pumped down the interior of the casing 30, 'The set-delayed cement composition 14 may be allowed to flow down the interior of the casing 30 through the casing shoe 42 at the bottom of the casing 30 and up around the easing 30 into the wellborn annulus 32. The set-delayed cement composition 14 may be allowed to set in the welibore annulus 32, tbr example, to form a ceme,nt sheath that supports and positions the casing 30 in the wellbore 22. While not illustrated, other techniques may also be utilized for introduction of the set-delayed cement composition 14. By way of example, reverse circulation techniques may be used that include introducing the set-delayed cement composition 14 into the subterranean tbrmation 20 by way of the wellhore annulus 32 instead of through the casing 30, 1'00371 As it is introduced, the set-delayed cement composition 14 may displace other fluids 36, such as drilling fluids land /or spacer fluids that may be present in the interior of the casing 30 andior the wellbore annulus 32. At least a portion of the displaced fluids 36 may exit the wellbore annulus 32 via a flow line 38 and be deposited, for example, in one or more retention pits 40 (c,t1,, a mud pit), as shown on FIG. 2A. Referring again to 12I0, 213, a bottom plug 44 may be inuoduced 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 ruptuiv to allow the setAelayed cement composition 14 through the bottom plug 44. In 110, 213, the bottom plug 44 is shown on the landing collar 46. In the illustrated embodiment, a top plug 48 may be introduced into the welIbore 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 Alt-delayed cement composition 14 through the bottom plug 44.
tt)038 J The exempla*, set-delayed cement compositions disclosed herein may directly or indirectly affect one or more components or pieces of equipment associated with the preparation, delivery, recapture, recycling, reuse, and/or disposal of the disclosed set-delayed cement compositions. For example, the disclosed set-delayed cement compositions may directly or indirecdy affect one or more mixers, related mixing equipment, mud pits, storage fkilities or units, composition separators, heat exchangers, sensors, gauges, pumps, compressors, and the like used generate, store, monitor, regulate, and/or recondition the exemplary set-delayed cement compositions. The disclosed set-delayed cement compositions may also directly or indirectly affect any transport or delivery equipment used to convey the set-delayed cement compositions to a well site or downhole such as, for example, any transport vessels, conduits, pipelines, trucks, tubulars, and/or pipes used to compositionally move the set-delayed cement compositions from one location to another, any pumps, compressors, or motors (e.g., topside or downhole) used to drive the set-delayed cement compositions into motion, any valves or related joints used to regulate the pressure or flow rate of the set-delayed cement compositions, and any sensors (i.e., pressure and temperature), gauges, and/or c.ombirtations thereof, and the like. The disclosed set-delayed cement compositions may also directly or indirectly affect the various downhole equipment and tools that may come into contact with the set-delayed cement compositions such as, but not limited to, wellbore casing, wellbore litter, completion string, insert strings, drill string, coiled tubing, slickline, wireline, drill pipe, drill collars, mud motors, downhole motors and/or pumps, cement pumps, surface-mounted motors and/or pumps, centralizers, turbolizers, scratchers, floats (e.g., shoes, collars, valve.s, 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-, ete.), couplings (e.g, electro-hydraulic wet connect, dry connect, inductive coupler, etc.), control lines (e.g., electrical, fiber optic..., hydraulic, etc.), surveillance lines, drill bits and reamers, sensors or distributed sensors, downhole heat exchangers, valves and corresponding actuation devices, tool seals, packers, cement plugs, bridge plugs, and other wellbore isolation devices, or components, and the like.

EXAMPLES
[0039] TO facilitate a. better understanding of the present ethbodiments, the following examples of certain aspects of some embodiments are elven. In no way should the -following examples be read to limit, or define, the scope Of the embodiments.
Example I
100401 A sample set-delayed cement composition was prepared with the following eomponents: pumice (1)S.325 lightweight aggregate), hydrated lime, dispersant ClAttimene 5581F), primary retarder (Micro Matrix4' cement retarder), weighting additive (MicroMax Weight Additive, available from Ilailiburton 'Energy Services, Incõ :Houston, Texas), secondary retarder (I-lle-5 cement retarder, available from flalliburton Energy Services, Inc., Houston, Texas), class 1-1 Portland cement, and water. Each component, with the exception of the primary retarder (Micro Marie cement retarder), is presented as a percentage of the weiebt of pumice (bwoP). 'The primary retarder is :measured in units of gallons per 46 pound sack of pumice (gals). The compnsitional Makeup is listed in Table 1 below.
Table 1 Sample Setaelayed Cement COMpOSM011ai Makeup Material Amount Units Weida (g) % bw in total PUrflice 100 % bwoP 58682,7 55.56 Hydrated lime 20 % bwoP 11736.5 11.11 Dispersant 0.5 % bwoP 291.1 0.28 Primaty Retarder 0.06 ga tisk 734.6 0.70 Weighting, Additive 2 % bwoP 1173.7 1.11 Secondary Retarder % bwoP 293.4 0.28 Portland Cement 2 % bwoP 1173.7 1.11 Water 51.7 bwoP 31534.5 29.86 Total 105620.2 100 [00411 The sample in Example 1 remained fluid, mixable, pumpable, and stable with no solids settling or gelation for greater than 40 days. The sample had a measured density of 13.5 ponds per gallon. Minimal doses of dispersant were added during the storage period to maintain the slurry's optimal theology. This exemplary sample serves as the base slurry tbr the remaining examples provided below.
Example 2 100421 The theological properties of the sample set-delayed cement compo,sition of Example, I were measured after storing the samples at room temperature and pressure for a period of 41 days. After preparation, the theological properties of the samples were determined using a Model 35A Fann Viscometer and a No, 2 spring with a Fann Yield Stress Adapter, in accordance with the procedure set forth in API RP Practice 1013-2, Recommended Practice for Thsting Well Cements. The results of this test are set forth in Table 2 below.
Table 2 'Viscosity Tests FYSA Readings Age of Sample ________________________________________________________ (days) RPM 3 6 100 200 300 1 3) 6D
41 AVG. 13 13 35 1 56 75.5 5 4 Example 3 E00431 Three sample set-delayed cement compositions, samples 1-3, and two controls, controls 1 and 2, were prepared from the base slurry described in Example I.
Foamer 1026'", a foaming additive, was added to each or the three samples in varying amounts after a time period of 41 days, Additionally, a cement set activator, COI, was added to sample 2 and control 2. The amount of the cement set activator added to each sample was sufficient to deliver a 5% by weight of pumice activator amount to the set-delayed cement composition. The base and foamed densities were measured.
Additionally, the destructive compressive strength was measured using a mechanical press in accordance with API RP Practice 10B-2, Recommended Practice Jr Testing Well Cements.
Additionally, the destructive compressive strength was measured by allowing the samples to cure in a 2" by 4" plastic cylinder that was placed in a water bath at 1901' 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, Recommended Awake lin. Testing Weil Cements. The results of this test are set forth below.
The reported compressive strengths ant an average thr two cylinders of each sample. The samples and controls were cured at 1 atmosphere, 190('1; compressive strength measurements were taken at 72 hours, Tahle 3 Compositional Makeup arid Characteristics ; ___________________________________________________________________________ Sample 1 1 Sample 2 sa mp. 3 C
ontro 1 Control 2 I
Sample Weight (g) 1363.2 1 1363.2 i 1363.2 817.5 817.5 .
.
Foaming Additive (g) 8.14 12.21 14 - .
Activator (g) - 1 37.87 - - 25.8 -.
1-33SC Density (ppg) 13.6 13.5 13.5 13.5 13.3*
' Foamed Density (ppg) 11 9.1 9.2 . -Foam Quality 19% 33% ,...)0,, .)... /0 - .

.
Compressive Strength (psi) 639.37 1 534.45 I 135.18 1222.46 1360.14 *Density of Control 2 with the Activator, [0044] in addition to the characteristics of Table 3, the foarn stability of samples 1-3 was measured in both the slurry state and the set state. This data is set %nit in Table 4 below.

Table 4 Foam Stability Measurements.
Foam Stability Sample 1 Sample 2 Sample 3 Slurry Set Slurry Set Slurry Set More than a trace of tree fluid?
Bubbles on surface of bubble coalescing :(breaking, enlargement, merging)? NN I N
Excessive column-height reduction?
Signs of density segregation (streaking or dark Coloration from top to bottom)? N N N l, N
[0045] The Archimedes Method was used to measure the. slurry density of Samples 1.3 in ipp, middle., and bottom portions. :Densities that weiv close in weight from top to bottom indicate stable foam while considerable variation in densities indicates unstable foam. All units are in pounds per gallon. This data is set forth in Table 5 below.
Table 5 Density Uniformity Archimedes: Method :Example 1 Example .2 Example 3 Top (ppg) 10.50 859.?6 Middle (ppg) 10.52 8.99 9.10 BOttonl (PO) 10.46 8.83 9,25 100461 1.11stlyõ the theology a foamed Skimples 1.3 'MIS MeaStired Wing tIV
Same 1,0 technique as used in Example 2 to measure the rheolOgy of the 'base slurry. The base slurry is designated as Control I in Table 6 below. The theology data is set forth in Table 6 below.

11 9 Table 6 Viscosity Tests FYSA Readings Density (ppg) RPM 3 6 1(10 200 300 31) 61) Control 1 13,5 AVG. 13 13 35 56 75.5 5 Sample, 1 11 AVG. 10 10.5 33.5 50.25 65.5 3.5 2,5 Sample 2 9,1 A VG. 2.25 = 17.5 29.5 40 1.5 Sample 3 9.2 AVG-. 1'7 17.5 40,5 56,5 70,5 12 [0047] Example 3 thus indicates that the foamed slurries exhibit good compressive strength while maintaining suitable rheolmies and uniform densities.
Example 4 [00481 Two sample set-delayed cement compositions, samples 4 and S. were prepared from the base slurry described in Example 1. A cement set activator, CaCI", was added to the samples in an amount sufficient to deliver a 5% by weight of pumice activator amount to the set-delayed cement CoMpositirm. Sample 5 further included graphitic carbon fibers in an alllOtlin of about 0.18% by weight of the, pumice. The graphitic carbon fibers were PAN carbon -fibers derived from polyacrylonitrile. Foamer 1026 a foaming additive, was added to each of the samples in an amount of 0.18% by weight of the pi...Unice.
Additionally, the destructive compressive strength was measumd by allowing the samples to cure in a 2" by 4." plastic cylinder that was placed in a water bath at I90'1?
fOrtn set cylinders: Immediately after rernoval from the water bath, destructive Compressive strengths were determined using a inc.chanical press in aceordance with API RP 10B-2, Recommenekd ?make .16r Tecting (7ements. The results of this test are set ibrth below. The reported compressive strengths are an average for three cylinders of each sattiple. The samples and controls were cured at 1 atmosphere, 190"F; compressive strength measurements were taken at '72 hours, Table 7 Compositional Makeup and Characteristics Sample 4 Sample 5 Base Slurry (u) 1000 1000 Carbon Fiber (g) 10 Activator (g) "7,8 27.8 Foaming Additive (g) 10 I 0 Base Density (ppg) 13.5 13.5 Foamed Density (ppg) 8.33 8.33 Compressive Strength (psi) 62 143 [0049] It should be understood that the compositions and methods are described in terms of "comprising," "containing," or "including' various components or steps, the compositions and methods can also "consist essentially or or "consist of the various components and steps, _Moreover, the indefinite articles -a" or '`an," as used in the claims, are defined herein to mean one or more than one of the element that it introduces.
I:0050j For the sake of brevity, only certain ranges are explicitly disclosed herein, 1-lowevt...r., ranges from any lower limit may be combined with any upper limit to recite a range not explicitly recited, as well as, ranges from any lower limit may be combined with any other lower limit to recite a range not explicitly recited, in the same way, ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited. Additionally, whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range are specifically disclosed. In particular, c...very 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. "fhus, 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.
[005 1 Therefore, the present embodiments are well adapted to attain the ends and advantages ine.ritioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, and may be modifk..d and practiced in different but equivalent Mantlerti apparent 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. 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 clahns have their plain, ordinary meaning ItilleSS
othemise explicitly and dearly defined by the patentee. It is therefore evident that the particular illustrative embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit Of the invention. If there is any conflict in the usages of a word or term in this specification and one or more patein(s) or other documents that may be incorporated herein by reference, the definitions that are consistent with this specification should be adopted.

Claims

What is claimed is:

1. A method of cementing in a subterranean formation comprising;
providing a set-delayed cement composition comprising water, pumice, hydrated lime, and a set retarder;
foaming the set-delayed cement composition;
activating the set-delayed cement composition;
introducine the set-delayed cement composition into a subterranean formation; and allowing the set-delayed cement composition to set in the subterranean formation.

2. A method according to claim 1 wherein the foaming the Set-delayed cement composition comprises adding a foaming additive to the set-delayed cement composition and entraining a eas into the set-delayed cement composition.

3. A method according to claim 2 wherein the foaming additive is selected from the group consisting of: a betaine; hydrolyzed keratin; an amine oxides; an alkyl o.r alkene dimethyl amine oxide; a cocoamidopropyl dimethyl amine oxide; a methyl ester sulfonate;
an alkyl or Aerie dimethyl amidobetaine; cocoamidopropyl betainc; an alpha-olefin sulfonate: a uaternary surfactant; tri methyltallowarn mon i um chloride ;
trimethylcocoammonium chloride; a C8 to C22 alkylethoxylate sulfate; and any combinatim thereof.

4. A method according to any of claims 1 to 3 wherein the foaming the set-delayed cement composition produces a foamed set-delayed cement composition comprising a foam quality between about 5% to about 80%.

5. A method according to any of claims 1 to 4 wherein the foaming the set-delayed cement composition produces a foamed set-delayed cement composition having a density between about 9 pounds per gallon to about 11 pounds per gallon.

6. A method according to any of claims 1 to 5 wherein the set retarder cmprises at least one retarder selected from the group consisting of a phosphonic acid a phosphonic acid derivative, a lignosulfonate, a salt, an organic acid, a cellulose derivate, a synthetic co- or ter-polymer comprising sulfonate and carboxylic acid groups, a borate compound, and any combination thereof.

7. A. method according to any of claims 1 to 6 wherein the set-delayed cement composition further comprises a dispersant.

8. A method according to any of claims 1 to 7 wherein the dispersant comprises at least one dispersant selected from the group consisting of a sulfonated-formaldehyde-based dispersant, a polycarhoxylated ether dispersant, and a combination thereof.

9. A. method according to any of claims 1 to 8 wherein the set retarder comprises a phosphonic acid derivative, and wherein the set-delayed cement composition further comprises a polycarboxylated ether dispersant.

10. A method according to any of claims 1 to 9 wherein the activating the foamed set-delayed cement composition comprises adding a cement set activator to the set-delayed cement composition, wherein the cement set activator comprises at least one activator selected from the group consisting of an amine, a silicate, zinc formate, calcium acetate, a Group lA hydroxide; a Group IIA hydroxide, a monovalent salt, a divalent salt, nanosilica, a polyphosphate, and any combination thereof

11. A method according to any of claims 1 to 10 where the set-delayed cement composition is introduced into the subterranean formation by a process comprising pumping the set-delayed cement: composition through a conduit, through a casing shoe, and into a well bore annulus,

12. A foamed set-delayed cement composition comprising:
water, pumice, hydrated lime, a foaming additive, entrained gas, and a set retarder.

13. The foamed set-delayed cement composition according to Claim 12 comprising one or more of the features defined in any one of claims 3 and 6 to 9.

14. A system for cementing comprising:
a set-delayed cement composition comprising:
water, pumice, hydrated lime, and a set retarder;
a foaming additive for foaming the set-delayed cement composition;
a gas for foaming the set-delayed cement composition; and a cement set activator for activation of the set-delayed cement composition.

15. A system according to claim 14 further comprising mixing equipment for mixing the foaming additive, gas, and cement set activator with the set-delayed cement composition and pumping equipment for delivering the cement composition into a wellbore.

16. A system according to claim 14 or 15 wherein the foaming additive is selected front the group consisting of: a betaine; hydrolyzed keratin; an amine oxides; an alkyl or alkene dimethyl amine oxide; a cocoamidopropyl dimethyl amine oxide;
a methyl ester sulfonate; an alkyl or alkene dimethyl amidobetaine; cocoamidopropyl betaine; an alpha-olefin sulfonate; a quaternary surfactant, trimethyltallowammonium chloride;
trimethykocoammonium chloride; a C8 to C22 alkylethoxylate sulfate; and any combination thereof.

17. A system according to any of claims 14 to 16 wherein the set retarder comprises at least one retarder selected from the group consisting of a phosphonic add, a phosphonic acid derivative, a lignosulfonate, a salt, an organic acid, a cellulose derivate, a synthetic co- or ter-polymer comprising sulfonate and carboxylic acid groups, a borate compound, and any combination thereof.

18. A system according to any of claims 14 to 17 further comprising at least one selected front the group consisting of a sulfonated-formaldehyde-based dispersant, a polycarboxylated ether dispersant, and a combination thereof.

19. A system according to any of claims 14 to 18 wherein the set retarder comprises a phosphonic acid derivative, and wherein the set-delayed cement composition further comprises a polycarboxylated ether dispersant.

20. A system according to any of claims 14 to 19 wherein the cement set activator comprises at least one activator selected from the group consisting of an amine, a silicate, zinc formate, calcium acetate, a Group IA hydroxide; a Group IIA
hydroxide, a monovalent salt, a divalent salt, nanosilica, a polyphosphate, and any combination thereof.