Acid-resistant geopolymer compositions

Abstract

Acid-resistant alkali-activated materials are presented. A composition is presented herein that includes a polymerization product of an alkali-reactive aluminum-silicon-oxygen material and an alkaline solution; and from about 0.1 weight percent to about 5 weight percent of a nanoparticle material having particle size less than about 500 nm disposed in spaces of the composition, wherein the composition is acid resistant. A method herein includes preparing an alkali-activated precursor using an alkali-reactive aluminum-silicon-oxygen material, an alkaline material, and a nanoparticle material having particle size of about 500 nm or less and being present in the precursor mixture in a concentration of about 0.1 percent to about 5 percent by weight of the precursor mixture; deploying the precursor to a target location; and allowing the precursor to set to obtain an acid-resistant cementitious material.

Description

ACID-RESISTANT GEOPOLYMER COMPOSITIONSCROSS REFERENCE PARAGRAPH

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 675,848, entitled 'ACID-RESISTANT GEOPOLYMER COMPOSITIONS," filed July 26, 2024, the disclosure of which is hereby incorporated herein by reference.FIELD

[0002] This application for patent relates to acid-resistant alkali-activated materials. More particularly the invention relates to the use of alkali-activated materials having additives that increase resistance to corrosive fluids.BACKGROUND

[0003] Geopolymers are a class of alkali-activated 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.

[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 slurry mixture 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 wells to provide isolation and structural support within the well. Use of cement-like materials in hydrocarbon wells presents unique challenges. The slurry mixture precursor is typically pumped over long distances to the location where the mixture is to set, so the mixture must be readily 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. In particular, subterranean environments are sometimes acidic, and acids can react with certain components of a set geopolymer to degrade the geopolymer matrix structure. There is a need for alkali-activated materials, such as geopolymer compositions, having resistance to acid attack.SUMMARY

[0006] Embodiments described herein provide a method, comprising preparing an alkali-activated precursor using an alkali-reactive aluminum-silicon-oxygen material, an alkaline material, and a nanoparticle material, the nanoparticle material having particle size of about 500 nm or less and being present in the alkali-activated precursor m ixture in a concentration of about 0.1 percent to about 5 percent by weight of the alkali-activated precursor; deploying the alkali-activated composition to a target location having corrosive fluids; and allowing the alkali-activated precursor to set, forming an acid-resistant cementitious material.

[0007] Other embodiments described herein provide a composition, comprising a polymerization product of an alkali-reactive aluminum-silicon-oxygen material and an alkaline solution; and nanoparticles having particle size less than about 500 nm disposed in spaces of the composition.

[0008] Other embodiments described herein provide a composition, comprising a polymerization product of an alkali-reactive aluminum-silicon-oxygen material and an alkaline solution; and from about 0.1 weight percent to about 5 percent, by weight of the composition, of nanoparticles having particle size less than about 500 nm disposed in spaces of the composition, wherein the composition is acid resistant.DETAILED DESCRIPTION

[0009] 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.

[0010] 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 beenspecified, and that inventors possessed knowledge of the entire range and the points within the range.

[0011] 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.

[0012] As used herein, “embodiments” refers to nonlimiting 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.

[0013] Alkali-activated compositions, including precursor materials, settable precursor mixtures, and set materials resulting from reactions of alkali-activated compositions, are described herein. The compositions herein use polymer additives to reduce susceptibility of the set material to acid attack. Such compositions, which may be geopolymers, can be useful in any application where the set alkali-activated material might come into contact with a corrosive fluid or an environment containing corrosive fluids. Such environments are frequently encountered, for example, in subterranean applications, for example well cementing, plugging, and repair, where a geopolymer, or other cementitious material can come into contact with corrosive fluids such as carbon dioxide, hydrogen sulfide, and acidic brine. Such compositions can also be used in construction and other surface applications.

[0014] In some cases, a geopolymer or other polysialate system, as described herein, can be used in a wellbore that is intended to 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, and potentially used with acid-resistant geopolymer compositions or alkali-activated materials, 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.

[0015] CCUS 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. Use of the acid-resistant alkali-activated materials described herein may be advantageous in such applications where carbon dioxide is prevalent.

[0016] Geopolymer materials, and other alkali activated materials, are formed by disposing oxidized and prepared aluminum and silicon, as an alkali-reactivealuminum-silicon-oxygen material, along with an alkali activator, in a water mixture having high pH. The aluminum and silicon is typically in a form that is oxidized and treated at elevated temperature to prepare for alkali polymerization. These reactants can include, aluminum oxide, silicon oxide, and aluminosilicate materials. 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 byproducts commonly known as biomass ash, or more specifically biomass fly 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 may also be used if desired. In addition, alumina and silica may be added separately, for example as a blend of bauxite and silica fume. Other amorphous silica sources can also be used, which may include soda-lime glass dust, borosilicate glass dust, microsilica, fumed silica, precipitated silica, nanosilica, rice husk ash, or a combination thereof. It should be noted that some of the aluminosilicate sources mentioned above, such as GGBS and ASTM Class C fly ash, also contain calcium oxide, so these materials can also be considered activator sources. Suitable aluminosilicate sources for purposes here can have at least 2%, at least 7%, at least 12%, at least 18%, or at least 25%, for example up to 30-45%, by weight calcium oxide. These alkali-reactive aluminum-silicon-oxygen materials become reactive when placed in strongly alkaline environments, typically at pH greater than 11. Thematerials 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.

[0017] Polysialate systems, which include a polysialate matrix (a polymer of silicon, oxygen, and aluminum), include geopolymers and other materials polymerized in alkaline solution. In addition to raw materials derived from other industrial processes, as described herein, raw materials can be synthesized for use in making polysialate systems. Such raw materials are generally synthesized from materials containing aluminum, silicon, and / or oxygen using application of energy to render the raw material alkaline-reactive. Synthetic raw materials can be made from mixtures containing aluminum, silicon, and oxygen by heating (e.g. by combustion), application of electrical or mechanical energy, or any combination thereof, to transform the mixture at the atomic level into an aluminum, silicon, oxygen material suitable for polymerization in alkaline solution. Elemental aluminum and silicon can be processed in the presence of oxygen to make such materials. Oxides of aluminum and silicon, and generic aluminosilicate materials, whether alkaline-reactive or not, can also be used to make alkaline-reactive raw materials. The combination of materials can be tailored to provide a desired elemental composition, for example silicon to aluminum ratio, and the processing of the materials can be tailored to provide a polysialate precursor having desired physical and chemical properties such as particle size distribution, particle morphology (e.g. shape, roundness, aspect ratio, etc.), particle specific gravity, compositional homogeneity, alkaline reactivity, and crystallinity.

[0018] It should be noted that, in the context of making cementitious materials that are acid resistant, synthetic raw materials can be used to make a cementitious material containing no acid-responsive species. Thus, where it is noted below that use of raw materials having a low content of acid-responsive materials such as lime can impart acid resistance to a resulting cementitious material, the synthetic raw materials above can be fashioned to contain no acid-responsive species so that the resulting cementitious material also contains no acid-responsive species, further enhancing the acid resistance of the cementitious material.

[0019] In general, polysialate raw materials, synthetic or otherwise, may contain elements other than silicon, oxygen, and aluminum provided that silicon, oxygen, and aluminum are present in sufficient quantity, and proper atomic arrangement, to be reactive in alkaline solution to form a polysialate matrix or system. Materials that can be used to form synthetic polysialate raw materials may thus include other elements such as alkali metals (e.g. Li, Na, K, Rb, Cs), alkaline earth metals (e.g. Be, Mg, Ca, Sr, Ba), transition metals, which may be common metals such as Fe, Co, Ni, V, Zr, Cu, Cr, Zn, and Ti, noble metals, rare earth metals, and / or lanthanoid metals, and elements of Groups 5-9 of the periodic table, including metalloids and nonmetals such as B, Al, Ga, In, TI, C, Si, Ge, Sn, Pb, N, P, As, Sb, Bi, S, Se, Te, F, Cl, Br, and I, and actinides such as U and Th. These additional elements may be dopants (e.g. purposely added) or naturally occurring elements, and may occupy positions in the crystal lattice of a material before processing to make the material polysialation- reactive, or after such processing. Such elements may be present in any reasonable quantity, so long as the material, before or after processing, has enough silicon, oxygen, and aluminum to form an alkaline-reactive material that can participate in a polysialation reaction. An alkaline material is used to raise pH of the alkaline-activated precursor composition to cause the materials of the precursor to polymerize into a matrix. The alkaline material can be added to the precursor mixture as a solution or as a dry material. Where the alkaline material is added as a dry material, and no other aqueous materials are used, water, or water-containing material, is added to the dry material to form ions of the alkaline material. Dry materials such as alkali metal silicates (e.g. metasilicates, orthosilicates, pyrosilicates), alkaline earth metal oxides and hydroxides, and alkali metal salts such as carbonates, sulphates, sulphites, phosphates, oxalates, fluorides, hexafluoridosilicates, iodates, and molybdates, and derivatives thereof such as hydrogenated salts, can be used. Alkaline solutions, such as sodium hydroxide or potassium hydroxide solution, can also be used, and combinations of any of the above materials can be used.

[0020] The alkali-activated precursors described herein use particles of hydrophobic polymers, such as styrene-butadiene, styrene-acrylic acid, styrenemethacrylate, polyvinyl acetate, polystyrene, and other hydrophobic polymers, and combinations thereof, to provide acid resistance to the set alkali-activated material.The polymer particles function to provide more acid resistance to materials made from alkali-activated precursor mixtures having lower solid volume fraction, for example less than about 45%, or lower slurry density, such as less than about 15 ppg (“pounds per gallon”) slurry density. Precursor mixtures having lower density or solid volume fraction typically result in a set material with more porosity than those resulting from higher-density precursor mixtures, and more porous cementitious materials are more susceptible to attack by corrosive fluids because the corrosive fluid can penetrate the porous solid. Generally, alkali-activated precursors for use with acid-resistant polymers have a slurry density that ranges from 0.84 g / cm3(7 ppg) to 1.92 g / cm3(16 ppg), such as 1.0 g / cm3(8.3 ppg) to 1.5 g / cm3(12.5 ppg), for example 1.32 g / cm3(11 ppg) or 1.68 g / cm3(14 ppg).

[0021] 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 mixture. Density modifiers can include density increasing particles and density lowering particles. Low-density particles may be added to the precursor 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, such as lower than 1 .3 g / cm3, or lower than 1 .0 g / cm3, for example 0.84 g / cm3, 0.75 g / cm3, or 0.35 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 0.06 kg / L and 0.6 kg / L (20 Ib / bbl and 200 Ib / bbl). The lightweight particles may be used in a dry precursor blend at doses from 0.1 % to 25% by volume of the blend (BVOB). 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, or more than 3 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 MicroMax™ and MicroMax FF™.

[0022] The polymer particles generally have size less than about 2 pm, and particle size distribution with D50 less than about 1 pm, such as between about 50 nm and about 500 nm, or between about 100 nm and about 200 nm, for example about 160 nm. In some cases, all polymer particles included in the geopolymer have dimension of less than about 400 nm. The small particles are believed to fill in the void spaces in the set alkali-activated material, reducing porosity and susceptibility to penetration by corrosive fluids. Such activity is believed to reduce surface area of the cementitious matrix that can be exposed to corrosive attack. In some cases, the polymer particles may also coat, or partially coat, particles of the matrix or in the internal domains of the matrix. In some cases, for example the polymer particles can form a film, or a partial film, on particles of the cementitious matrix.

[0023] The polymer particles can be a latex material, which can be added as a material having a dry, watery, or pasty consistency. For example, a liquid emulsion latex of styrene-butadiene polymer particles, generally according to the particles sizes above, can be incorporated in an alkali-activated precursor mixture to confer acid resistance to the resulting hardened material. The amount of such a material used in an alkali-activated precursor is typically less than 1 gallon per sack (gps) in a precursor mixture having a lower density in the range described above. For example, in a precursor mixture having slurry density of 11-12 ppg, a latex material containing hydrophobic polymer particles can be added in an amount of 1 gps or less, such as 0.75 gps or less, for example 0.50 gps, 0.25 gps, or 0.10 gps. A small amount of the latex material is used to avoid accentuating porosity in the set material resulting from the precursor mixture. In general, and depending on target density of the alkali- activated precursor mixture, hydrophobic polymer particles present, in a pumpable precursor mixture, in a quantity of about 0.1 to about 5 percent, such as about 0.5 to about 3 percent, for example about 1 percent, by weight of the total precursor mixture, will reduce degradation of the set cementitious material from corrosive attack.

[0024] The polymer particles can be dispersed, as a dry powder, for example a “latex powder,” in a dry blend of alkali-activated precursor materials, to which water can be added to start the geopolymerization reaction. Alternately, the polymer particles can be added, as a latex paste, to a wet alkali-activated precursor mixture,or the polymer particles can be added, as a liquid latex, to a wet or dry alkali-activated precursor mixture.

[0025] Thickening time of the alkali-activated precursor mixtures described herein can be influenced by adding retarders and accelerators or adjusting the concentration of the chemical activators. Several retarders may delay the setting and hardening of alkali-activated 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 mixture in amounts of 0.01 to 5 parts per hundred by weight of the total 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 an alkali-activated precursor can cause the precursor to remain unhardened by interfering with the polymerization reaction so the alkali-activated precursor does not set, or by overdispersion of solid particles in the precursor. In other embodiments a retarder solution can be added to the carrier fluid or to the precursor, or both. By this means, the same precursor could be pumped into different sections of a well and setting time of precursor in the different sections can be controlled through addition of a different amount of the retarder.

[0026] Accelerators can also be added to the alkali-activated precursor in amounts up to about 0.01-10, such as 1-5, parts per hundred weight of the total precursor mixture. As above, 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 before the precursor becomes unmovable. The accelerator concentration can be selected based on the slurry density of the precursor mixture and the expected wellbore conditions at the target location for the precursor deployment. It should be noted that the retarders and accelerants described herein can be added as particulate materials in the precursor, or such reagents can be added to water before the wateris added to an alkali-activated precursor composition described herein.

[0027] Other additives, such as anti-foam agents, defoamers, crystalline and amorphous silica, fluid-loss control additives, gas migration control additives, viscosifiers, dispersants, expanding agents, anti-settling additives or combinations thereof. Selection of the type and amount of additive largely depends on the nature and composition of the set composition, and those of ordinary skill in the art will understand how to select a suitable type and amount of additive for compositions herein. These materials are generally solids or liquids, and may be added as dry materials or liquid dispersions.

[0028] Viscosifiers may comprise diutan gum having a molecular weight higher than about 1 x 106. The diutan gum may be present at a concentration of 0.01 to 2% by weight of the total dry alkali-activated precursor. In some cases, viscosifiers are present in the dry precursor at a concentration of 0.1-5% 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, 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 of 0.1 to 5% by weight of the total dry alkali-activated precursor. The molecular weight of the polysaccharide material, which may be a biopolymer, may be between 100,000 and 1 ,000,000. Clay minerals such as bentonite, sepiolite, attapulgite, and others can also be used as viscosifiers, alone or in combination with other types of viscosifiers such as polysaccharides.

[0029] 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 includedin 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.

[0030] 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 slurry, or between 0.05 and 0.1 kg / L.

[0031] Examples

[0032] Geopolymer materials prepared according to embodiments herein were tested for acid durability. The same geopolymer precursor mixture was prepared to two different slurry density targets, one at 11 .6 ppg and another at 14.8 ppg. The 11 .6 ppg material was prepared by adding low-density glass beads to the 14.8 ppg material. For each material, one version was prepared with polymer particles, added as a latex, while another version had none. For the acid-resistant specimens, a styrene-butadiene water latex material was used to impart acid resistance or durability. The latex material had dso of 159 nm, with substantially all particles smaller than 400 nm. Different specimens were tested having different doses of polymer. Each geopolymer was cured for 14 days in a 170°F water bath at ambient pressure. The hardened geopolymer specimens were then exposed to a solution of 15% HCI in water (pH <0.5) for varying amounts of time. Table 1 shows the results for the 14.8 ppg version.Table 1 - Percent Mass Loss in 14.8 ppg Geopolymer Samples Exposed to 15%HCITable 1 shows the clear acid resistance conferred by inclusion of hydrophobic polymer particles in the geopolymer. After 3 days’ exposure to 15% HCI, the aciddurable geopolymer exhibited about 50% mass loss. Since the environment likely to be encountered by a geopolymer in an application is much less corrosive that thesetest conditions, these specimens, and others like them as described herein, would be expected to have strong durability in an acid environment of pH above about 4.

[0033] Table 2 shows the results for the 11 .6 ppg version.Table 2 - Percent Mass Loss in 11.6 ppg Geopolymer Samples Exposed to 15% HCITable 2 also shows acid resistance of geopolymers containing particles of hydrophobic polymer.

[0034] Table 3 shows results for an 11.6 ppg geopolymer precursor mixture having different amounts of the latex, other parameters being equal.Table 3 - Effect of Latex Addition on Geopolymer Acid-DurabilityAs shown in Table 3, for low amounts of latex (polymer particle) addition, more polymer confers higher acid durability.

[0035] In some cases, acid resistance can arise from low porosity of a geopolymer system. Ensuring that acidic species cannot penetrate into the geopolymer system, or penetrate only slowly, can provide resistance to acid damage. Some of the materials described above can function as porosity reduction agents. Other materials that can be used, alone or in combination with the materials described above, to reduce porosity of a geopolymer system, and thus add resistance to acid attack, include acid-resistant particles such as silica and metal oxide particles. Such particles can be nanoparticles, i.e. particles having nanometer scale dimensions, such as a dimension less than about 500 nm, less than 300 nm, or less than 200 nm, for example about 100 nm. Thus, for example, some embodiments can have hydrophobic polymer nanoparticles as well as inorganic nanoparticles, which canhave the same or different particle size and / or particle size distribution. Such particles can be added at any stage of precursor preparation, and to the extent addition of such particles affects properties of the geopolymer precursor, the quantity and type of other ingredients and additives can be adjusted accordingly.

[0036] In other cases, a geopolymer can acquire acid resistance from high amounts of solids in the precursor used to form the geopolymer. High solids volume fraction, for example about 30% or above, or 40% or above, for example 45% or above, in a geopolymer precursor mixture, can lead to a geopolymer that has low porosity, and thus some resistance to penetration and acid attack. The solids that contribute to low porosity in a set geopolymer can be those that participate in a geopolymerization reaction or those that do not participate in the reaction.

[0037] In other cases, using geopolymer raw materials having low content of acid- reactive species, such as lime, generally provide better acid resistance in a geopolymer. Where geopolymer systems contain residual acid-reactive species, acidic species from the environment can react with the residual acid-reactive species, increasing porosity locally within the geopolymer system and creating progressive damage to the geopolymer system. Using raw materials that have low concentration of acid-reactive species, resulting in geopolymer systems having low concentration of such species, reduces the opportunity for acid attack and damage. For example, geopolymer raw materials such as fly ash, especially Fly Ash Type F, typically have low concentrations of acid-reactive species, and low concentration of such species in the resulting geopolymer system, yielding a geopolymer system less susceptible to acid attack. The lime content of Fly Ash Type F is less than, or equal to, 18% (ASTM C618-19). While the lime content of Fly Ash Type C can be greater than 18%, for example 25-30%, fly ashes in the lower part of the range can be used to form geopolymers having low or reduced acid susceptibility, or acid resistance.

[0038] To demonstrate the effect that using raw materials having low concentration of acid-reactive species has on acid resistance of a resulting geopolymer, geopolymers were made using Fly Ash Type C and Fly Ash Type F, and Class C cements were also made. These materials were treated with an acetic acidsolution having pH of 2 at 140°F, and weight loss of the materials was observed to quantify acid susceptibility. Table 4 shows the results.Table 4 - Weight Loss of Cementitious Materials in pH 2 Acetic Acid SolutionAs the data of Table 4 demonstrates, the geopolymers made from fly ash raw materials generally exhibited less susceptibility to acid attack than conventional Class C cement, and the geopolymer made from Fly Ash Type F exhibited less acid susceptibility than the geopolymer made from Fly Ash Type C. It is also notable that the two specimens of Class C cement also exhibit the effect of solids volume fraction (SVF) on acid susceptibility, with higher SVF yielding a cementitious material exhibiting less weight loss upon acid exposure.

[0039] The preceding description has been presented with reference to certain embodiments. Persons skilled in the art and technology to which this description pertains will appreciate that changes in the methods described can be practiced without meaningfully departing from the principle and scope of this subject matter and inventions described herein. Accordingly, the foregoing description should not be read as pertaining only to the precise compositions described, but rather should be read as consistent with and as support for the following claims, which are to be understood as having their fullest and fairest scope.

Claims

CLAIMSWe claim:

1. A method, comprising: preparing an alkali-activated precursor using an alkali-reactive aluminum- silicon-oxygen material, an alkaline material, and a nanoparticle material, the nanoparticle material having a particle size of about 500 nm or less and the alkali- activated precursor mixture having a concentration of the alkali-activated precursor from about 0.1 percent to about 5 percent by weight; deploying the alkali-activated composition to a target location having corrosive fluids; and allowing the alkali-activated precursor to set to obtain an acid-resistant cementitious material.

2. A composition, comprising: a polymerization product of an alkali-reactive aluminum-silicon-oxygen material and an alkaline solution; and nanoparticles having particle size less than about 500 nm disposed in spaces of the composition.

3. A composition, comprising: a polymerization product of an alkali-reactive aluminum-silicon-oxygen material and an alkaline solution; and from about 0.1 weight percent to about 5 percent, by weight of the composition, of nanoparticles having particle size less than about 500 nm disposed in spaces of the composition, wherein the composition is acid resistant.

4. The method or composition of any preceding claim, wherein the nanoparticles comprise hydrophobic polymer particles selected from the group consisting of styrene-butadiene polymer, styrene-acrylic acid polymer, styrene-methacrylate polymer, polyvinyl acetate, polystyrene, and combinations thereof.

5. The method or composition of any preceding claim, wherein the alkali- activated precursor used to make the composition has a slurry density of 7 to 16 pounds per gallon.

6. The method or composition of any preceding claim, wherein the nanoparticles have particle size less than about 400 nm.

7. The method or composition of any preceding claim, wherein the nanoparticles comprise hydrophobic polymer particles that at least partially coat particles of the composition.

8. The method or composition of any preceding claim, wherein the nanoparticles comprise hydrophobic latex polymer particles.

9. The method or composition of any preceding claim, wherein the nanoparticles are a combination of hydrophobic polymer particles and inorganic particles.

10. The method or composition of any preceding claim, wherein the cementitious material or the composition further comprises a density modifier.11 . The method or composition of any preceding claim, wherein the nanoparticles are a combination of hydrophobic polymer particles and inorganic particles, and the polymer particles have a different particle size, particle size distribution, or both, from the inorganic particles.

12. The method or composition of any preceding claim, wherein the cementitious material or composition includes particles at least partially coated with a polymer film.

13. The method or composition of any preceding claim, wherein the cementitious material or the composition has no acid responsive species.1 . The method or composition of any preceding claim, wherein the nanoparticles comprise silica particles, metal oxide particles, or both.

15. The method or composition of any preceding claim, wherein the nanoparticles comprise particles selected from the group consisting of styrene-butadiene polymer,styrene-acrylic acid polymer, styrene-methacrylate polymer, polyvinyl acetate, polystyrene, silica, metal oxide, and combinations thereof.

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