One-sack geopolymer compositions

Abstract

Alkali activated precursor compositions are presented that are useful for cementing a subterranean well, among other uses. The precursor compositions are dry mixtures that have an aluminosilicate source and an activator consisting of a metal carbonate, metal silicate, or combination thereof. A precursor is formed by adding water to the dry precursor compositions. Such precursors have suitable characteristics for use in cementing applications that use pumpable mixtures.

Description

ONE-SACK GEOPOLYMER COMPOSITIONSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claims priority benefit of United States Provisional Patent Application 63 / 594,219 filed October 30, 2023, which is entirely incorporated herein by reference.FIELD

[0002] This application for patent relates to geopolymer compositions. More particularly the invention relates to the use of geopolymer compositions that do not use strong alkaline solutions to activate polymerization.BACKGROUND

[0003] Geopolymers are a class of materials that are formed by chemical reaction of various aluminosilicates, oxides, and silicates to form an amorphous three- dimensional framework cement-like structure. The term geopolymer was proposed and first used by J. Davidovits. His work is described in Davidovits, J: “Synthesis of New High-Temperature GeoPolymers for Reinforced Plastics / Composites.' Society of Plastics Engineers, IUPAC International Symposium on Macromolecules, Stockholm (1976). Other terms have been used to describe materials synthesized utilizing a similar chemistry, such as alkali-activated cement, geocement, alkali- bonded ceramic, inorganic polymer, hydroceramic. In the following description, the term geopolymer will be used.

[0004] Geopolymers have been investigated for use in several applications, including as concrete systems within the construction industry, as refractory materials and as encapsulants for hazardous and radioactive waste streams. Geopolymers are also recognized as being rapid setting and hardening materials. They exhibit superior hardness and chemical stability. The preparation of geopolymers generally involves mixing a blend of reactive solid materials and activating the polymerization reaction by adding an alkaline solution. Typically, the activated geopolymerprecursor is then applied and allowed to harden in place. In construction, faster hardening is usually valued.

[0005] In the hydrocarbon industry, cement-like materials are used to line well pipes to provide isolation and structural support within the well. Use of cement-like materials in hydrocarbon wells presents unique challenges. The precursor of the cement-like material is typically pumped over long distances to the location where the mixture is to set hard and build sufficient strength, so the precursor mixture must be pumpable without undue burden on equipment. Additionally, ambient conditions encountered in a typical hydrocarbon well are much more extreme than those encountered in a typical construction application. Further, the large vertical extent of hydrocarbon well applications presents challenges of density, temperature, salinity, and pressure not faced in the construction industry. Other applications, like plugs, squeeze, and injector wells for water or carbon dioxide, also require a cementitious precursor to be pumped to an application site, so geopolymer compositions find broad use where pumping is required.

[0006] While geopolymers have been found to be useful tools for cementing subterranean wells, and in other applications requiring pumping a cementitious precursor, handling of alkaline solutions that are prepared by adding alkaline materials to water to mix geopolymer slurries is challenging. The practice of adding alkaline materials to water prior to mixing geopolymer slurries requires extra equipment and transportation of volumes of liquid to the well site. Such practices also bring handling and operating concerns related to the characteristics of such materials. For example, adding alkali metal hydroxide activator to water releases heat and causes a large temperature rise in the prepared alkaline solution that complicates preparation of the geopolymer precursor and can cause unpredictable variation in setting and gelation performance. It would be useful to find geopolymer blends that can be used for lining hydrocarbon wells and for other uses such as construction uses, but that do not need strong alkaline solutions to be delivered to a well or construction site to create a precursor mixture.SUMMARY

[0007] Embodiments described herein provide a method of cementing a subterranean well, comprising mixing a dry precursor, comprising an aluminosilicate source comprising at least about 18 wt% calcium oxide and a chemical activator consisting of a metal carbonate, a metal silicate, or a combination thereof, with a nonactivating water material to form an alkali activated precursor; pumping the alkali activated precursor into a subterranean well; and hardening the alkali activated precursor into a solid alkali activated material within the subterranean well.

[0008] Other embodiments described herein provide a method of cementing a subterranean well, comprising mixing a dry precursor, comprising an aluminum-, silicon-, and oxygen-containing reactant comprising at least about 18 wt% calcium oxide and a chemical activator consisting of a metal carbonate, a metal silicate, or a combination thereof, with a non-activating water material to form an alkali activated precursor; pumping the alkali activated precursor into a subterranean well; and hardening the alkali activated precursor into a solid alkali activated material within the subterranean well.

[0009] Other embodiments described herein provide a dry alkali activated composition, comprising an aluminum-, silicon-, and oxygen-containing reactant comprising at least about 18 wt% calcium oxide and a chemical activator consisting of a metal carbonate, a metal silicate, or a combination thereof.

[0010] BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Fig. 1 is a graph showing compressive strength of various alkali activated materials according to embodiments described herein.

[0012] Fig. 2 is a graph showing compressive strength of various alkali activated materials according to other embodiments described herein.DETAILED DESCRIPTION

[0013] In the following description, numerous details are set forth to provide an understanding of the present disclosure. However, it may be understood by those skilled in the art that the methods of the present disclosure may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.

[0014] At the outset, it should be noted that in the development of any such actual embodiment, numerous implementation — specific decisions are made to achieve the developer's specific goals, such as compliance with system related and business related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time consuming but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. In addition, the composition used / disclosed herein can also comprise some components other than those cited. In the summary of the disclosure and this detailed description, each numerical value should be read once as modified by the term "about" (unless already expressly so modified), and then read again as not so modified unless otherwise indicated in context. The term “about” should be understood as any amount or range within 10% of the recited amount or range (for example, a range from about 1 to about 10 encompasses a range from 0.9 to 11 ). Also, in the summary and this detailed description, it should be understood that a concentration range listed or described as being useful, suitable, or the like, is intended that any concentration within the range, including the end points, is to be considered as having been stated. For example, “a range of from 1 to 10” is to be read as indicating each possible number along the continuum between about 1 and about 10. Furthermore, one or more of the data points in the present examples may be combined together, or may be combined with one of the data points in the specification to create a range, and thus include each possible value or number within this range. Thus, even if specific data points within the range, or even no data points within the range, are explicitly identified or refer to a few specific data points, it is to be understood that inventors appreciate and understand that any data points within the range are to be considered to have been specified, and that inventors possessed knowledge of the entire range and the points within the range.

[0015] Regarding chemical formulas, it should be noted that measurements may not conform precisely to the chemical formulas described herein due to various sources of error that can affect real-world testing. The chemical formulas described herein should therefore be understood as expressing the nominal chemical makeup of compounds, where real-world testing may show close, but not exact, conformity to the formulas.

[0016] As used herein, “embodiments” refers to non-limiting examples disclosed herein, whether claimed or not, which may be employed or present alone or in any combination or permutation with one or more other embodiments. Each embodiment disclosed herein should be regarded both as an added feature to be used with one or more other embodiments, as well as an alternative to be used separately or in lieu of one or more other embodiments. It should be understood that no limitation of the scope of the claimed subject matter is thereby intended, any alterations and further modifications in the illustrated embodiments, and any further applications of the principles of the application as illustrated therein as would normally occur to one skilled in the art to which the disclosure relates are contemplated herein.

[0017] Geopolymer materials, and other alkali activated materials, are formed by admixing an aluminosilicate source and an alkali activator in a water mixture having high pH. Examples of aluminosilicate sources that can be used include (but are not limited to) ASTM Class C fly ash, ASTM Class F fly ash, fly ash not classified by ASTM, volcanic ash, volcanic glass, slag, ferrous slag, ferroalloy slag, non ferrous slag, such as copper slag, nickel slag, tin slag, zinc slag, and the like, blast furnace slag, basic oxygen furnace slag, electric arc furnace slag, and ground slags, such as ground blast furnace slag, ground granulated blast furnace slag (GGBS), diatomaceous earths, pumice, and calcined clays, which may be partially or fully calcined clays (metakaolin is a partially calcined clay), aluminum-containing silica fume, natural aluminosilicate, feldspars, which may be dehydrated, alumina and silica sols, synthetic aluminosilicate glass powder, zeolite, scoria, allophone, bentonite, pumice, red mud, which may be calcined. Other examples of aluminosilicates with similar activity are ashes produced by combustion of some forest or agricultural industry by-products commonly known as biomass ash, or more specifically biomassfly ash, from various sources such as witchgrass ash, walnut shell ash, rice husk ash, and the like. These materials contain a significant proportion of an amorphous aluminosilicate phase, which reacts in strong alkaline solutions. The more common aluminosilicates are fly ash, metakaolin and blast furnace slag. Mixtures of two or more aluminosilicate sources are also commonly used. In addition, alumina and silica may be added separately, for example as a blend of bauxite and silica fume. Other amorphous silica sources are also used, including soda-lime glass dust, borosilicate glass dust, microsilica, fumed silica, precipitated silica, nanosilica, rice husk ash, or a combination thereof.

[0018] In general, a material containing aluminum, silicon, and oxygen that is thermally treated to become alkali activated can be used, whether or not that material is an “aluminosilicate” material, as such. These materials become reactive when placed in strongly alkaline environments, typically at pH greater than 11. The materials described above react under such conditions to form geopolymers and other alkali activated materials. Binder components such as Portland cement, kaolin, bauxite, aluminum oxide, and aluminum hydroxide can also be included.

[0019] In some cases, aluminosilicate sources for alkali activated materials (“AAMs”) including geopolymers have particle sizes, and particle size distributions, that are smaller than traditional cement materials. GGBS materials, for example, often have D90 particle size that is less than 50 pm, for example less than 40 pm. The D50 particle size of GGBS materials can be less than 20 pm, and in some cases less than 15 pm, and the D10 particle size can be less than 3 pm, in some cases less than 2 pm. Fly ash Type C materials often have D90 particle size that is less than 150 pm, for example less than 100 pm. The D50 particle size of fly ash Type C materials can be less than 50 pm, and in some cases less than 20 pm, and the D10 particle size can be less than 10 pm, in some cases less than 5 pm.

[0020] Precursor compositions in one sack for use in cementing subterranean wells, such as zonal isolation of hydrocarbon wells in the case of primary cementing, injector wells, or plug and abandon or squeeze activity, or for other applications above or below ground, such as construction applications, are described herein. The precursor compositions described herein are such that non-activating water materials can be used to prepare a settable slurry mixture for use at a target location. A non-activating water material, for purposes herein, is a water material having pH less than about 11 . Water, free of any alkaline activator, can be used. Thus, the precursor compositions described herein can be such that only water, free of any activators, is needed to prepare a settable slurry mixture for deployment into a subterranean well, and the resulting slurry mixture has controlled setting time, viscosity profile, and density profile suitable for pumping into such a well. Thus, precursor compositions that can be safely handled and mixed with activator-free water to prepare a settable slurry for lining a hydrocarbon well are described herein. Upon addition of appropriate amounts of non-activating water material to the dry ingredients, the precursor formed thereby can be pumpable, so such compositions can be pumped into subterranean wells or in any application where pumping a cementitious material is needed, such as for grouting applications related to construction at a pipeline location or for underground or subsea electrical installations. In some cases, the water used to mix with the dry blend, containing one or more activators, is not activator-free, but can contain activator species in solution, which might be insufficient to achieve setting of an AAM. The precursor compositions described herein are made using dry ingredients that include activators as dry ingredients, so the water used to make the precursor can be free of any activators.

[0021] The AAMs described herein can be used for many different kinds of wellbores. In some embodiments, the wellbore may be used for carbon capture, utilization, and storage (CCUS) and / or for recovery and use of geothermal energy. Geothermal energy is a promising source of renewable energy that captures energy from heat generated or stored within the earth. For example, geothermal energy may be used to perform climate control (e.g., heating, cooling) for structures (e.g., buildings) using heat pumps and / or to generate electricity (e.g., by heating water to generate steam and drive a turbine with the steam). The wellbores described herein may be used to circulate a working fluid that exchanges heat within the earth formation through which the wellbore extends. The working fluid may be circulated to the surface where a surface heat exchanger is used to transfer thermal energy to another fluid used to generate electricity and / or for climate control. After the thermal energy is transferred from the working fluid in the surface heat exchanger, the working fluid is circulated back to the earth formation to continue the cycle.

[0022] CClIS facilitates the capture, use, and / or storage of carbon (e.g., carbon dioxide), which has a goal of achieving carbon neutrality and / or net zero carbon emissions (NZE). Carbon capture may include the capture of carbon dioxide from large point sources, such as power plants, refineries, cement plants, other industrial processing plants, or other industrial facilities that use fossil fuels, biomass fuels, or other fuels that generate carbon dioxide. The captured carbon dioxide may be converted into valuable products such as, for example, ethanol, sustainable aviation fuel, chemicals, mineral aggregates, and / or other products. Alternatively, the carbon dioxide may be stored in geologic formations, such as in depleted hydrocarbon reservoirs. The carbon dioxide may be introduced into the earth formation through a wellbore, such as the wellbores described herein. In the earth formation, the carbon in the carbon dioxide may be dispersed in an aqueous phase and stored as carbon dioxide, may be stored in mineral form (e.g., as a carbonate, such as calcium carbonate, magnesium carbonate, iron(ll) carbonate), or as another form of carbon.

[0023] Where the reactant source has a calcium oxide content of at least about 18 wt%, for example in aluminosilicate sources such as fly ash Type C and GGBS, metal carbonates, metal silicates, or a combination thereof can be used as the activator, with no other activator material. The metal of the metal carbonate and metal silicate is an alkali metal such as Na, Li, K, Rb, or Cs. Combinations can also be used. Sodium carbonate, sodium silicate, and sodium metasilicate can be used, along or in combination. Where a combination of carbonate, silicate, and / or metasilicate is used, any combination of the above metals can be used as cation. Thus, carbonate, silicate, and metasilicate anions can be combined with any metal ions from the list above in a dry activator material.

[0024] Such compositions also remove the need to transport large volumes of caustic liquid ingredients to a well site for mixing geopolymer slurries, and to mix such liquid ingredients at the well site (requiring equipment for such mixing), reducing the overall equipment footprint at the well site and incrementally reducing the health, safety, and environmental burden of using and transporting caustic liquids and using them at the well site. Such compositions also generate less heat on mixing with water, allowing for more operating flexibility because cooling time is not needed. Forexample, using the compositions described herein, geopolymer precursors can be mixed and pumped “on-the-fly,” without the need to mix liquid ingredients and wait for them to cool, or precursors can be batch-mixed and pumped with no limitation imposed by the need to moderate heating upon dissolution. Pumpable geopolymer precursors typically have viscosity of about 300 cPs or less at ambient conditions. The precursors herein, having such low viscosities, nevertheless develop suitable compressive strength as geopolymers for subterranean uses.

[0025] A dry alkali activated precursor composition typically includes an aluminosilicate source, or thermally-prepared aluminum-, silicon-, and oxygencontaining material, such as those described above, an activator or mixture of activators, and one or more density, viscosity profile modifiers, retarders, and / or accelerators to render the precursor suitable for pumping downhole and setting at a target location within the well, before substantial hardening takes place after a suitable amount of water, which may be activator-free or may have insufficient activator concentration to cause a polymerization reaction, is added to make the precursor. In conventional practice, an alkali activated precursor is formed by adding an alkali metal or alkaline earth hydroxide solution to a dry mixture. In the precursors described herein, such solutions are not needed, and the precursor composition is a dry blend material that contains a solid particulate source of alkalinity that can be mixed with water containing no activator, or an amount of activator insufficient to form a suitable polymer, to raise the pH of the slurry to an activation level.

[0026] The activators used herein are generally dry materials, to which water or a non-activating water material is added. The activator used herein can be a metal silicate M2xSiyO2y+x where x is 1 , 2, or 3 and y is 1 or 2 (for example silicates, metasilicates, orthosilicates, and pyrosilicates), or a metal carbonate M2CO3, or a combination thereof, where M can be Li, Na, K, Rb, or Cs, or a combination thereof. The metal silicates and / or carbonates are used, typically with reactants having calcium oxide content of at least about 18 wt%, in an amount to provide a pH of 11 or higher to activate components for polymerization to occur and form a hardened polymer.

[0027] The activators used herein can include an alkaline earth metal hydroxide,such as Ca(0H)2, Sr(0H)2, Mg(0H)2 and / or Ba(OH)2; or alkaline earth metal oxide, such as CaO, SrO, MgO and / or BaO or a combination thereof, or alkaline earth metal peroxide, such as MgO2 and Ca02 or a combination thereof ; or an alkali metal salt such as a metal carbonate M2CO3, metal sulphate M2SO4, metal sulphite M2SO3, metal phosphate M3PO4, metal oxalate M2C2O4, metal silicate M2xSiyO2y+x where x is 1 , 2, or 3 and y is 1 or 2 (for example silicates, metasilicates, orthosilicates, and pyrosilicates), metal fluoride MF, metal hexafluoridosilicate M2SiFe, metal iodate MIO3, metal molybdate M2MOO4, where M can be Li, Na, K, Rb, or Cs, where such salts can have a combination of different metals and a combination of different anions. Lime and hydrated lime are examples of materials that contain calcium oxide and / or calcium hydroxide. Hydrogenated metal salts, such as MHCO3, MHSO4, MHPO4, MHC2O4, M2HPO4, MH2PO4, and MHSO3 can also be used, alone or in combination with other activators described herein, where M is as listed above. These activators raise pH in a precursor upon addition of water such that the reactants in the precursor composition dissolve and begin to polymerize. Alkali metal oxide and hydroxide solids are not used as activators herein due to extremely exothermic reactions of such materials with water. The activators may further include Portland cement, cement kiln dust, cement by-pass dust or a combination thereof.

[0028] The solid activators described above are particulate materials that are blended with the reactants to make a dry particulate blend. As noted above, a combination of such activators can be used. The solid activators are typically added in a quantity that is 2 to 40 parts per hundred based on the weight of the dry precursor particulate blend, for example 4 to 20 parts per hundred or 4 to 40 parts per hundred based on the weight of the total dry precursor particulate blend. The solid activator content of the precursor composition is selected to provide enough pump time for deploying the precursor composition downhole along with acceptable compressive strength after passage of a requisite time period such as 24 hours. For example, the compositions described herein can be formulated to have a selected thickening time, which is equivalent to the job time of placing the precursor to a target location of the wellbore plus extra time as safety margin (i.e., 1 -2 hrs). Typically, the thickening time is measured in the lab as the time for the precursor to reach a consistency of 70 Be reading, while being subjected to simulated wellbore conditions (T, P) and constantstirring at 150 rpm. The amount of solid activator used depends on the type of solid activator, the type of aluminosilicate source used, the desired thickening time, and the desired strength of the final polymer. Use of the activators described herein can provide the capability to make AAMs such as geopolymers, in the absence of added alkali metal or alkaline earth metal hydroxides.

[0029] Thickening time of the precursor formed by adding water to the precursor solid dry blend described herein can be influenced by adding retarders and accelerators. Several retarders may delay the setting and hardening of geopolymer systems. Retarders such as sodium pentaborate decahydrate, borax, sucrose, boric acid, lignosulphonates, sodium glucoheptonate, tartaric acid, citric acid, or phosphorus containing compounds such as phosphoric acid, salts thereof, or mixtures thereof can be added to the precursor particulate mixture in amounts of 0.01 to 5 part per hundred by weight of the total particulate precursor mixture. The amount of retardation of the polymerization reaction, and the setting of the precursor, depends on the type of raw materials used for the precursor and the type and relative quantity of retarder used. Adding too much retarder reagent to a precursor can cause the precursor to remain unhardened by interfering with the polymerization reaction so the geopolymer does not set. In other embodiments a retarder solution can be added to the carrier fluid or to the geopolymer precursor, or both. By this means, the same precursor could be pumped into different sections of a well and setting time of precursors in the different sections can be controlled through addition of a different amount of the retarder solution.

[0030] Accelerators can also be added to the precursor particulate mixture in amounts up to about 0.01 -10, such as 1 -5, parts per hundred weight of the total particulate precursor mixture. The amount of acceleration of the polymerization reaction, and the setting of the precursor, depends on the type of raw materials used for the precursor and the type and relative quantity of accelerating reagent used. Adding too much accelerator to an alkali activated precursor can cause the precursor to thicken too quickly making it difficult to deploy the precursor to target locations downhole. It should be noted that the retarders and accelerants described herein can be included as particulate materials in the precursor composition, or suchreagents can be added to water before the water is added to a precursor composition described herein.

[0031] Alkali activated precursors for use in well lining applications typically are mixed into a slurry density range from 0.84 g / cm3(7 Ibm / gal) to 2.87 g / cm3(24 Ibm / gal), such as 1 .32 g / cm3(11 Ibm / gal) to 2.4 g / cm3(20 Ibm / gal) or 1 .32 g / cm3(11 Ibm / gal) to 2.16 g / cm3(18 Ibm / gal), for example 1.36 g / cm3(11.3 Ibm / gal) to 1.90 g / cm3(15.8 Ibm / gal). The slurry density can be influenced by quantity of water added and / or by adding density modifiers. Water typically makes up from about 20% by weight to about 60% by weight of an alkali activated precursor. Density modifiers can include density increasing particles and density lowering particles. Low-density particles may be added to the precursor particulate mixture to achieve lower slurry densities for a given amount of water added, or heavy particles may be added to achieve higher slurry densities. The lightweight or low-density particles may have densities lower than 2 g / cm3, or lower than 1 .3 g / cm3. Examples include hollow glass or ceramic microspheres (cenospheres), plastic particles such as polypropylene beads, rubber particles, uintaite (sold as GILSONITE™), vitrified shale, petroleum coke or coal or combinations thereof. The lightweight particles may be present in the compositions at concentrations between about 0.05 kg / L and 0.6 kg / L (20 Ib / bbl and 200 Ib / bbl). The particle size range of the low-density particles may be between about 38 pm and 3350 pm (6 mesh and 400 mesh). The heavy particles typically may have densities exceeding 2 g / cm3, more than 3 g / cm3, or more than 4 g / cm3, and up to 5 g / cm3. Examples include hematite, barite, ilmenite, silica (e.g. crystalline silica sand), crushed granite and also manganese tetroxide commercially available under the trade names of Micro Max™ and MicroMax FF™. For example, alkali activated precursors herein may have slurry density from about 11.4 Ibm / gal to about 16.4 Ibm / gal.

[0032] Other additives, such as anti-foam agents, defoamers, silica, fluid-loss control additives, viscosifiers, dispersants, expanding agents, anti-settling additives or combinations thereof may be added to the precursor particulate mixture, and or to the non-activating water material. Selection of the type and amount of additive largely depends on the nature and composition of the set composition, and those of ordinaryskill in the art will understand how to select a suitable type and amount of additive for compositions herein.

[0033] The fluid-loss control agent may comprise a latex. The latex may be an alkali-swellable latex. The latex may be present in the compositions at a concentration between 0.02 L / L and 0.3 L / L or between 0.05 L / L and 0.15 L / L, or between 0.5 gallons per sack and 3 gallons per sack.

[0034] Viscosifiers may comprise diutan gum having a molecular weight higher than about 1 x 106. The diutan gum may be present at a concentration between 0.14 g / L and 1.4 g / L (0.05 Ibm / bbl and 0.5 Ibm / bbl). In some cases, viscosifiers are present in the dry precursor at a concentration of 0.04-5% by weight of the total dry precursor. Other viscosifiers may comprise a polysaccharide material, which may be a biopolymer. Suitable polysaccharide biopolymers can include welan gum, xanthan gum, a polyanionic cellulose (PAC), a carboxymethylcellulose (CMC), and combinations thereof. One or more polysaccharide materials, which may be biopolymers, may be present at a concentration between 0.14 g / L and 1.4 g / L (0.05 Ibm / bbl and 0.5 Ibm / bbl). The molecular weight of the polysaccharide material, which may be a biopolymer, may be between 100,000 and 1 ,000,000. Bentonite can also be used as a viscosifier, alone or combined with other viscosifiers.

[0035] Carboxylic acids including gluconic acid and soluble salts thereof, glucoheptonic acid and soluble salts thereof, tartaric acid and soluble salts thereof, citric acid and soluble salts thereof, glycolic acid and soluble salts thereof, lactic acid and soluble salts thereof, formic acid and soluble salts thereof, acetic acid and soluble salts thereof, proprionic acid and soluble salts thereof, oxalic acid and soluble salts thereof, malonic acid and soluble salts thereof, succinic acid and soluble salts thereof, adipic acid and soluble salts thereof, malic acid and soluble salts thereof, nicotinic acid and soluble salts thereof, benzoic acid and soluble salts thereof, and ethylenediamine tetraacetic acid (EDTA) and soluble salts thereof may be included in the compositions as retarders or dispersants or both. Phosphoric acids may be present for the same purpose. Salts of these acids may also be employed. These materials may be present in the compositions at concentrations between 0.5 g / L and 10 g / L, or between 1 g / L and 5 g / L.

[0036] Expanding agents may comprise calcium sulphate hemihydrate, metal oxides such as MgO or combinations thereof. The expanding agents may be present in the compositions at concentrations between 0.01 kg / L and 0.2 kg / L of geopolymer precursor, or between 0.05 and 0.1 kg / L.

[0037] The water added to form the precursor slurry can be activator-free water or part of an activator solution. Sea water can be used in some cases. Also, in some cases, additional activator may be included with the water to make an incremental activator solution, which used alone without any other activators would be nonactivating. The non-activating water solution is added to the dry mixture to make the precursor, and / or added to an alkali activated slurry precursor. For example, a precursor mixture containing a solid activator may be mixed with a solution of an activator in water to form a precursor slurry having a target total amount of activator. In such cases, the solution can be a non-activating solution of alkali metal hydroxide MOH, alkaline earth metal oxide or hydroxide such as Ca(OH)2, Sr(OH)2, Mg(OH)2, Ba(OH)2, an alkali metal salt selected from the group consisting of M2CO3, M2SO4, M3PO4, M2C2O4, M2xSiyO2y+x where x is 1 , 2, or 3 and y is 1 or 2, MF, M2SiFe, MIO3, M2MOO4, where M is Li, Na, K, Rb, or Cs, or a combination thereof, that adds an incremental amount of activator to the activator present in the dry precursor particulate mixture prior to blending with the solution. Because the dry precursor mixture contains solid activator, the added activator solution can contain an amount of activator that alone would be insufficient to cause a polymerization reaction, and thus would be non-activating, but when combined with the components released by reaction of the solid activator with water, results in desired setting of the precursor. In some embodiments, a first water volume, free of activator, can be added, and a second water volume comprising a non-activating water material that contains some activator can be added separately, in any order.Examples

[0038] Table 1 shows preparation of Examples A1 -A3. These examples were prepared by adding precursor compositions in one sack containing GGBS, silica, barite, and sodium metasilicate activator and other ingredients to water as shown in Table 1 .Table 1The compositions shown in Table 1 can be prepared by mixing the dry ingredients together, and then adding water to complete the composition. The mixed dry ingredients can be stored, shipped, and otherwise handled in dry form, and then water can be added at the time the composition is to be deployed to make a precursor slurry. The slurry can be made pumpable for deployment in a hydrocarbon well. In general, the dry polymerization precursor described herein can be blended with water to make an alkali activated slurry that will develop into a hard polymer usable for many applications above and below ground, including applications such as hydrocarbon wells where the slurry is to be pumped to a setting location. In other cases, the slurry can be disposed at any setting location by any suitable means. Additional dry ingredients, as described above, can be added to the dry mixture for thickening time control, density or viscosity profile control, or other objectives.

[0039] Rheology of examples A1 -A3 was measured after conditioning the mixtures at 60°C (bottom hole circulating temperature, “BHCT”) according to API procedure RP 10B. Thickening time was measured at 60°C and 2000 psi, compressive strength was measured after 24 hours by crushing 2”x2” cubes of each material. The results are summarized in Table 2 (thickening time to 70 Bearden consistency units, “Be,” are given).Table 2

[0040] Table 3 shows preparation of Examples A10-A14. These examples show alkali activated materials activated using only sodium carbonate (soda ash) as the activator. These examples also show different slurry densities, use of GGBS from different sources, and use of different additives. Properties of some set materials obtained from the precursors are also shown. The GGBS reactants were sourced from different geographic sites. To make the precursors, the dry ingredients were blended separately, and then water was added. The anti-foam is a conventional PEG-based material, the dispersant is a polynaphthalene sulfonate-based material, the retarder is a sodium glucoheptonate-based material, the two silica materials have different particle sizes with silica-2 having larger particle size than silica-1 , and the latex is a dry latex material.Table 31Different batch;2Average of four samplesThe different types of silica used for Examples A13 and A14 necessitated different rheological testing from the other examples. Specifically, whereas Examples A10- A12 were tested using the typical R1 B1 rheology configuration, the Examples A12 and A13 were tested using R1 B5 configuration.The compositions shown in Table 3 demonstrate that AAMs can be prepared using only soda ash (sodium carbonate) as activator. Such materials can be made using precursors of different densities and precursor materials of different provenance, withmultiple different additives. The precursors of Table 3 can be prepared by mixing the dry ingredients together, and then adding water to complete the composition. The mixed dry ingredients can be stored, shipped, and otherwise handled in dry form, and then water can be added at the time the composition is to be deployed to make a precursor slurry. The slurry is pumpable for deployment in a hydrocarbon well or other type of well. In some cases, a precursor slurry is pumpable where the slurry has a slurry consistency lower than about 70 Be as measured by a high-temperature, high-pressure consistometer, a yield value (Ty) lower than about 50 lbm / 100 ft2, or both.

[0041] The examples above show that one-sack AAM precursor compositions can be made using solid activator materials that are safer to store, transport, and mix with water. The precursor compositions can be prepared at a well site to suitable density and rheology for pumping into a subterranean well such as a hydrocarbon well. The compositions then set in a suitable time period for use in cementing subterranean wells. Additionally, mixing water with these precursor compositions generates only modest heat that will not adversely affect pumpability of the slurry by accelerating setting.

[0042] The metal silicates and carbonates mentioned above can be used as activators alone, without any other alkaline materials. Soda ash and sodium metasilicate are materials that can be used to activate AAM precursors alone. For example, soda ash can be used as a single activator for a geopolymer precursor comprising GGBS or type C fly ash with high quick lime (CaO) content.

[0043] Fig. 1 is a graph 100 showing compressive strength of various AAMs, at least some of which are geopolymers, made using GGBS and ASTM Class C fly ash as aluminosilicate sources and soda ash as the only activator. These AAMs were each made using 0.02 gallons per sack (gps) polypropylene glycol as defoamer, 0.04% by weight diutan gum as viscosifier, and 0.15% by weight of polynaphthalene sulfonate dispersant, based on the weight of the aluminosilicate source. The dry ingredients, including aluminosilicate source and dry activator, were blended, and the slurries were made by adding activator-free water and mixing. At 102, a first axis of the graph 100 shows quantity of calcium oxide in the aluminosilicate source. At 104,a second axis of the graph 100 shows compressive strength in pounds per square inch.

[0044] In Fig. 1 , the data points showing results for ASTM Class C fly ash as the aluminosilicate source are grouped at 110 and the data points showing results for GGBS as the aluminosilicate source are grouped at 112. The fly ash used to make the AAMs represented by the grouping 110 of data points contained 30.08 % calcium oxide, and 59.59% calcium oxide plus silica, by weight. The GGBS used to make the AAMs represented by the grouping 112 of data points contained 39.93 % calcium oxide, and 72.23% calcium oxide plus silica, by weight. The AAMs represented by the data points at 110 were made by subjecting a precursor based on ASTM Class C fly ash to curing at 81 °C for 168 hours, and the AAMs represented by the data points at 112 were made by subjecting a GGBS-based precursor to curing at 81 °C for 24 hours.

[0045] The AAMs represented by the data points in Fig. 1 were made by compiling all the dry ingredients into a dry mixture and adding water to the dry mixture to make the precursor. The dry mixtures use different amounts of soda ash activator. The data points 114 represent AAMs made using 2% by weight soda ash activator, based on the weight of the aluminosilicate source. The data points 116 represent AAMs made using 4% by weight soda ash activator, based on the weight of the aluminosilicate source. The data point 120 represents an AAM made using 6% by weight soda ash activator, based on the weight of the aluminosilicate source. The data point 122 represents an AAM made using 8% by weight soda ash activator, based on the weight of the aluminosilicate source. All the AAM precursors that produced the AAMs of Fig. 1 were made to a density of 15.2 pounds per gallon.

[0046] The data of Fig. 1 shows that soda ash can be used as the sole activator for AAM precursors using GGBS and / or ASTM Class C fly ash as aluminosilicate sources. With these two aluminosilicate sources, which contain at least about 18 wt% calcium oxide, using sufficient soda ash activator can result in a set hardened AAM having suitable compressive strength for some applications. As shown in Fig. 1 , using more activator generally results in an AAM having higher compressive strength, up to a point. As also shown in Fig. 1 , GGBS generally develops highercompressive strength than ASTM Class C fly ash for a given activator concentration. Generally speaking, the data of Fig. 1 shows that using soda ash as a single activator for a dry mixture that, when water is added to form an AAM precursor, reacts with the water to form an AAM, where the soda ash is present in the dry mixture at a concentration of 4% by weight or more, based on the total weight of the aluminosilicate source in the dry mixture, provides an AAM having suitable compressive strength for some applications. With some aluminosilicate sources having higher calcium oxide content, for example at least 40% by weight of the aluminosilicate source, as little as 2% by weight soda ash, based on the weight of the aluminosilicate source, can provide an AAM having suitable compressive strength for some applications.

[0047] Fig. 2 is a graph 200 showing compressive strength of various AAMs, at least some of which are geopolymers, made using the same GGBS and ASTM Class C fly ash materials from Fig. 1 as aluminosilicate sources and sodium metasilicate as the only activator (“sodium metasilicate” is abbreviated, in the figure, as “S-MET”). These AAMs were each made using 0.04% by weight of diutan gum viscosifier, based on the weight of the GGBS, and 0.15% by weight of polynaphthalene sulfonate dispersant, based on the weight of the GGBS. The graph 200 has the same axes 102 and 104 as the graph 100, with the same data groupings 110 and 112. The AAMs represented by the data points in the graph 200 were all cured at 81 °C for 24 hours.

[0048] As with Fig. 1 , the AAMs represented by the data points in Fig. 2 were made by compiling all the dry ingredients into a dry mixture and adding activator-free water to the dry mixture to make the precursor. For all these precursors, 0.02 gallons per sack of propylene glycol was added as a defoamer. The dry mixtures use different amounts of ASTM Class C fly ash activator. The data points 202 represent AAMs made using 7.31 % by weight sodium metasilicate activator, based on the weight of the aluminosilicate source. The data points 204 represent AAMs made using 11 % by weight sodium metasilicate activator, based on the weight of the aluminosilicate source. The data points 206 represent AAMs made using 15% by weight sodium metasilicate activator, based on the weight of the aluminosilicatesource. All the precursors that formed the AAMs of Fig. 2 were made to a density of 15.2 pounds per gallon.

[0049] The data of Fig. 2 shows that sodium metasilicate can be used as the sole added activator for precursors using GGBS and / or ASTM Class C fly ash as aluminosilicate sources. With these two aluminosilicate sources, using sufficient sodium metasilicate in a dry blend as a single activator, to mix with activator-free water to form a precursor, can result in an AAM having suitable compressive strength for some applications. As shown in Fig. 2, using more activator generally results in an AAM having higher compressive strength, up to a point. As also shown in Fig. 2, in contrast to the result in Fig. 1 , GGBS and ASTM Class C fly ash generally develop similar compressive strength for a given activator concentration. Generally speaking, the data of Fig. 2 shows that mixing a dry mixture having sodium metasilicate as a single activator with water forms an AAM having suitable compressive strength for some uses, where the sodium metasilicate is present in the dry mixture at a concentration of 7% by weight or more, based on the total weight of the aluminosilicate source in the dry mixture.

[0050] Other embodiments using soda ash as a single activator for a dry mixture, using sodium metasilicate as the sole added activator for alkali activated precursors, or using combinations of soda ash and sodium metasilicate as activator for precursors can be formulated.

[0051] The dry mixtures described above can be mixed with any of the additives described herein prior to adding water, or any of the additives described herein can be added to the precursor formed by adding water after the water is added. Upon adding water, an AAM precursor is formed that can be deployed at a setting location by any suitable means, for example by pumping in certain embodiments, and allowed to harden into an AAM.

Claims

CLAIMSWe claim:1 . A method of cementing a subterranean well, comprising: mixing a dry precursor, comprising an aluminosilicate source comprising at least about 18 wt% calcium oxide and a chemical activator consisting of a metal carbonate, a metal silicate, or a combination thereof, with a non-activating water material to form an alkali activated precursor; pumping the alkali activated precursor into a subterranean well; and hardening the alkali activated precursor into a solid alkali activated material within the subterranean well.

2. A method of cementing a subterranean well, comprising: mixing a dry precursor, comprising an aluminum-, silicon-, and oxygencontaining reactant comprising at least about 18 wt% calcium oxide and a chemical activator consisting of a metal carbonate, a metal silicate, or a combination thereof, with a non-activating water material to form an alkali activated precursor; pumping the alkali activated precursor into a subterranean well; and hardening the alkali activated precursor into a solid alkali activated material within the subterranean well.

3. The method of claim 1 or 2, wherein the metal carbonate or metal silicate comprises alkali metal ions.

4. The method of any of claims 1 to 3, wherein the aluminosilicate source of claim 1 , or the reactant of claim 2, comprises fly ash, ground granulated blast furnace slag, or a combination thereof.

5. The method of any of claims 1 to 4, wherein the dry precursor further comprises a retarder selected from the group consisting of boric acid, glucoheptonic acid and soluble salts thereof, gluconic acid and soluble salts thereof, tartaric acid and soluble salts thereof, citric acid and soluble salts thereof, phosphoric acid and soluble salts thereof, sodium pentaborate decahydrate, borax, sucrose, lignosulphonates, and combinations thereof.

6. The method of any of claims 1 to 5, wherein the dry precursor further comprises a viscosifier selected from the group consisting diutan gum, welan gum, xanthan gum, a polyanionic cellulose (PAC), a carboxymethylcellulose (CMC), bentonite, and combinations thereof.

7. The method of any of claims 1 to 6, wherein the dry precursor further comprises one or more accelerators, retarders, density modifiers, antifoam agents, viscosifiers, defoamers, silica, fluid-loss control additives, dispersants, expanding agents, anti-settling additives or combinations thereof.

8. The method of any of claims 1 to 7, wherein the alkali activated precursor has a viscosity, at ambient conditions, of no more than about 300 cPs.

9. The method of any of claims 1 to 8, wherein the metal carbonate is sodium carbonate and the metal silicate is sodium metasilicate.

10. The method of any of claims 1 to 9, wherein the dry precursor comprises a density modifier selected from the group consisting of hollow glass or ceramic microspheres, plastic particles, rubber particles, uintaite, vitrified shale, petroleum coke, coal, hematite particles, barite particles, ilmenite particles, silica particles, crushed granite, manganese tetroxide particles, and combinations thereof.

11. The method of any of claims 1 to 10, wherein the alkali activated precursor has a slurry density of about 11 .4 Ibm / gal to about 16.4 Ibm / gal.

12. A dry alkali activated composition, comprising: an aluminum-, silicon-, and oxygen-containing reactant comprising at least about 18 wt% calcium oxide and a chemical activator consisting of a metal carbonate, a metal silicate, or a combination thereof.

13. The composition of claim 12, wherein the metal carbonate or metal silicate comprises alkali metal ions.

14. The composition of claim 12, wherein the reactant comprises fly ash, ground granulated blast furnace slag, or a combination thereof.

15. The composition of claim 12, further comprising one or more accelerators, retarders, density modifiers, antifoam agents, viscosifiers, defoamers, silica, fluidloss control additives, dispersants, expanding agents, anti-settling additives or combinations thereof.

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