Organic-inorganic composite anti-corrosion well cementation admixture and preparation method thereof
By employing a multi-level synergistic anti-corrosion mechanism through organic-inorganic composite anti-corrosion cementing admixtures, the problem of poor anti-corrosion material performance in existing technologies has been solved, achieving highly efficient anti-corrosion for CO2 geological storage wells and improving the corrosion resistance and sealing performance of cement stone.
Patent Information
- Application Number
- CN202511419106.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-30
- Publication Date
- 2026-02-06
AI Technical Summary
Existing anti-corrosion materials are not effective in preventing corrosion in CO2 geological storage wells, leading to the failure of cement ring seals and their inability to effectively resist corrosion from acidic fluids.
An organic-inorganic composite anti-corrosion cementing admixture is adopted, which includes an inorganic matrix material, an organic corrosion inhibitor, a nano-reinforcement and corrosion inhibitor, forming a multi-level synergistic anti-corrosion mechanism. Through the synergistic effect of modified fly ash and lithium-magnesium slag, a dense barrier is formed to block the penetration path of corrosive media.
It significantly improves the CO2 corrosion resistance of cement slurry system, reduces environmental pollution, controls material costs, and enhances the toughness and compressive strength of cement stone through a multi-scale synergistic mechanism, constructing an efficient physical barrier to block CO2 diffusion and the penetration of acidic media.
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Figure CN121471892A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of cementing materials for oil and gas field development, specifically to an organic-inorganic composite anti-corrosion cementing admixture and its preparation method. Background Technology
[0002] CO2 capture, utilization, and storage (CCUS) technology is considered one of the effective ways to reduce carbon emissions. CO2 geological utilization and storage technology involves injecting captured CO2 into deep underground formations through a wellbore to permanently store CO2. However, CO2 geological storage wells require a large amount of oil well cement. In the downhole environment of geological storage, the oil well cement, exposed to acidic fluids for a long time, will undergo carbonization corrosion, causing changes in material composition and performance degradation, ultimately leading to cement sheath seal failure. To improve the CO2 corrosion resistance of cement sheaths, the current common practice is to add inert or active silicate admixtures (replacing part of the silicate cement) to the cement, aiming to improve the corrosion resistance of the cement stone through the "close packing effect" and "volcanic ash effect." However, the anti-corrosion effect presented by this method is limited. Therefore, developing a high-efficiency and environmentally friendly anti-corrosion material for cement is of great significance. Summary of the Invention
[0003] The purpose of this invention is to provide an organic-inorganic composite anti-corrosion cementing admixture and its preparation method, so as to solve the problem of poor anti-corrosion material performance in the prior art.
[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: An organic-inorganic composite anti-corrosion cementing admixture, comprising the following raw materials by weight percentage: Inorganic matrix material: 30-55 wt%; Organic corrosion inhibitor: 15-25 wt%; Nano-reinforcement: 20-30 wt% Corrosion inhibitor: 10-15 wt%; The inorganic matrix material is composed of metakaolin, modified fly ash and lithium-magnesium slag mixed in a mass ratio of 3:2:1.
[0005] Furthermore, the metakaolin has an Al2O3 content ≥38%, a loss on ignition ≤1.2%, and a particle size distribution satisfying: D50<4.5μm.
[0006] Furthermore, the modified fly ash has an Al2O3 content ≥30% and a particle size distribution satisfying: D50<5μm; The modified fly ash is prepared as follows: fly ash raw material is placed in a ball mill for grinding, and the ground fly ash is added to a 2 mol / L NaOH solution at a solid-liquid ratio of 1:6, and stirred to form a suspended slurry; the slurry is transferred to a microwave reactor for microwave treatment; the microwave-treated slurry is washed with deionized water until the pH value of the washing solution is between 6.5 and 7.5, and then the washed solid is vacuum dried at 80℃ for 4 hours; the vacuum-dried powder is pulverized until the particle size distribution meets the requirement: D50 < 5 μm.
[0007] Preferably, in the preparation method of modified fly ash: the grinding speed is 300 rpm and the grinding time is 30 min; the stirring time in the 2 mol / L NaOH solution is 30 min; the power of the microwave reactor is 800 W, the temperature is 70℃, and the processing time is 15 min.
[0008] Furthermore, the mineral composition of the lithium-magnesium slag includes magnesium hydroxide, magnesium borate, and magnesium oxide, and the particle size distribution of the lithium-magnesium slag satisfies: D50 < 10 μm.
[0009] Furthermore, the organic corrosion inhibitor is a mixture of a fluorinated organosilicon copolymer and a carboxylated styrene-butadiene latex in a mass ratio of 1:1.
[0010] Furthermore, the fluorinated organosilicon copolymer is prepared by reversible addition-fragmentation chain transfer controlled polymerization of dodecafluoroheptyl methacrylate and γ-aminopropyltriethoxysilane in a molar ratio of 1:2 under nitrogen protection. The preparation steps of the fluorinated organosilicon copolymer are as follows: 1.1. Take 250 mL of a mixed solvent formed by mixing toluene and isopropanol in a volume ratio of 3:1. Dehydrate the mixed solvent by passing it through a molecular sieve with a pore size of 0.4 nm until the water content is ≤100 ppm. Then, add acetylacetone to the dehydrated mixed solvent and mix thoroughly to obtain the first mixed solvent. The amount of acetylacetone added is 0.1 wt% of the total mass of the dehydrated mixed solvent. 1.2. Add 0.2 mol of γ-aminopropyltriethoxysilane and 200 mL of the first mixed solvent to a reactor protected by nitrogen gas with a purity ≥99.999% to obtain mixed solution A; 1.3. Add 0.01 mol of 2-cyano-2-propyldodecyl trithioester and azobisisobutyronitrile initiator to mixed solution A to obtain mixed solution B; 1.4. Dissolve 0.1 mol dodecafluoroheptyl methacrylate in 50 mL of a first mixed solvent to obtain a first reaction liquid; add the first reaction liquid dropwise to mixed solution B through a constant pressure dropping funnel at 0.5 mL / min and react for 10 hours to obtain a second reaction liquid, wherein the reaction temperature is 65℃ and the mixture is continuously stirred at 300 rpm during the reaction. 1.5. Cool the second reaction liquid to 10°C using an ice bath, then add hydroquinone to terminate the reaction and obtain a crude product. The amount of hydroquinone added is 0.5 wt% of the total mass of the second reaction liquid. Precipitate the crude product three times with n-heptane to obtain a precipitate. In each precipitation, add 10 ml of n-heptane for every 1 g of crude product. Dry the precipitate under vacuum at 60°C for 12 hours to obtain a white solid copolymer, i.e., a fluorinated organosilicon copolymer.
[0011] Furthermore, the carboxylated styrene-butadiene latex has a solid content ≥48%, pH ≥8.8, and particle size ≤120nm.
[0012] Furthermore, the nano-reinforcement is composed of carboxylated carbon nanotubes and core-shell structured nanocomposite materials mixed at a mass ratio of 1:(3-5).
[0013] Furthermore, the carboxylated carbon nanotubes are prepared by reflux treatment of raw carbon nanotubes with mixed acid for 4 hours. The aspect ratio of the carboxylated carbon nanotubes is 100-150, and the mixed acid is a mixture of H2SO4 and HNO3 in a volume ratio of 3:1. The preparation steps of the core-shell structured nanocomposite material are as follows: 2.1. Nano-TiO2 and graphene oxide were ultrasonically dispersed in a mixture of toluene and anhydrous ethanol at a mass ratio of 1:0.3 for 30 min to obtain a dispersion. The volume ratio of toluene to anhydrous ethanol was 4:1. KH-570 silane coupling agent and acetylacetone were added to the dispersion, with the addition amounts being 3 wt% and 0.05 wt% of the dispersion mass, respectively. The mixture was then reacted at 65 °C for 6 h under nitrogen protection. The product was centrifuged and washed, and the precipitate was vacuum dried at 60 °C to obtain modified TiO2@GO powder. 2.2. The modified TiO2@GO powder was subjected to O2 plasma treatment at a power of 100 W for 2 min. 2.3. Modified TiO2@GO powder treated with O2 plasma was placed in an atomic layer deposition vacuum reactor. Magnesium bis(2,2,6,6-tetramethyl-3,5-heptadecanoic acid) and trimethyl phosphate were used as precursors. A magnesium phosphate precursor layer was deposited on the powder surface at a deposition temperature of 100°C to obtain the sample. Subsequently, the sample was annealed at 300°C for 1 hour under a nitrogen atmosphere to obtain a core-shell structured nanocomposite material.
[0014] Furthermore, the corrosion inhibitor is a mixture of sodium molybdate, sodium tripolyphosphate, and modified activated carbon in a mass ratio of 1:1:(2-3); The sodium molybdate has a purity ≥99% and a particle size distribution satisfying: D90≤12μm; the sodium tripolyphosphate has a purity ≥99% and a median particle size D90≤18μm; the modified activated carbon has a specific surface area ≥1550m² / g. The modification method of the modified activated carbon is as follows: the activated carbon is immersed in a 2mol / L KOH solution at a solid-liquid ratio of 1:10, heated to 80℃ and stirred for 2h, then washed with deionized water until the pH value of the washing solution is between 6.5 and 7.5, and then the washed solid is dried at 105℃ for 4h to obtain the modified activated carbon.
[0015] A method for preparing an organic-inorganic composite anti-corrosion cementing admixture includes the following steps: S1. The inorganic matrix material and corrosion inhibitor are mixed in a double cone mixer at 100 rpm for 10 min and then at 300 rpm for 5 min to form a dry mixture. S2. After preheating the organic corrosion inhibitor to 40°C, add it to the nano-reinforcement in two batches and mix at 1500 rpm for 10 min to form a wet mixture. S3. Add the dry mixture to the wet mixture in three batches and mix at 1500 rpm for 20 minutes to obtain a mixed slurry. Spray dry the mixed slurry to form a shape. Control the inlet temperature of the spray drying tower to be 180℃ and the outlet temperature to be 80℃ to finally obtain an organic-inorganic composite anti-corrosion cementing admixture.
[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention adopts a multi-level synergistic anti-corrosion mechanism, which breaks through the corrosion resistance limitations of traditional single materials and endows the cement slurry system with excellent CO2 corrosion resistance. At the same time, by using solid waste as the main raw material, the pollution of solid waste to the environment is significantly reduced and the material cost is effectively controlled.
[0017] (2) The inorganic matrix material adopts a solid waste composite system. The three components optimize the cement stone structure through synergistic effects: the lithium magnesium slag dissolves first, providing a stable alkaline environment for the system. This environment not only promotes the hydration reaction of cement, but more importantly, it stimulates the large-scale dissolution of active silicon and aluminum components in metakaolin and modified fly ash. The dissolved ions then participate in the reaction to generate nanoscale hydrated calcium silicate (aluminate) gel. These nanoproducts can effectively fill and refine the pore structure of cement stone, significantly improve its density, and thus build an efficient physical barrier to block the penetration path of corrosive media.
[0018] (3) The organic corrosion inhibitor has dual protective functions: its silane group and carboxyl group can form chemical bonds with cement hydration products, enhancing the interfacial bonding force with cement matrix; the fluorine-containing segments gradually construct a dense superhydrophobic film to achieve superhydrophobic protection and inhibit CO2 diffusion; at the same time, styrene-butadiene latex can effectively form a film and block pores, further reducing permeability.
[0019] (4) The nano-reinforcement improves material performance through a multi-scale synergistic mechanism: carboxylated carbon nanotubes can be embedded in cement pores, bridging organosilanes and inorganic matrix, and enhancing the toughness and compressive strength of cement stone through interface strengthening and crack bridging; the core-shell structured nanocomposite material can not only physically block CO2 diffusion, but also release phosphate and magnesium ions after CO2 intrusion, realizing the self-repair of microcracks.
[0020] (5) The corrosion inhibitor adsorbs bicarbonate ions through physical adsorption and ion exchange, thus alleviating the local acidic environment; sodium molybdate and sodium tripolyphosphate can be released in a gradient and react with Ca 2+ / Mg 2+ Chelation forms a dense protective film, thereby inhibiting further carbonization reactions.
[0021] In summary, this invention achieves hierarchical filling at the micro-nano scale through inorganic matrix materials and nano-reinforcement, and systematically enhances the barrier against CO2 and acidic formation media by combining organic corrosion inhibitors and corrosion accelerators to construct a dense barrier. Attached Figure Description
[0022] Figure 1 The thermal analysis diagrams are of cement paste samples and cement stone samples prepared according to Examples 1-3 after 28 days of corrosion. Detailed Implementation
[0023] In this invention, unless otherwise stated, the particle size distribution characteristics (such as D50, D90, etc.) are measured using a laser diffraction particle size analyzer according to the ISO 13320:2009 standard. During measurement, water or ethanol is used as the dispersion medium, and the sample is pretreated by ultrasonic dispersion for 3 minutes, for example.
[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. In the description of this invention, it should be noted that the terms "first," "second," "third," "A," "B," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0025] In this embodiment of the invention, the inorganic matrix material is composed of metakaolin, modified fly ash and lithium-magnesium slag mixed in a mass ratio of 3:2:1.
[0026] In this embodiment of the invention, the modified fly ash has an Al2O3 content ≥30% and a particle size distribution that satisfies: D50<5μm; The modified fly ash is prepared as follows: fly ash raw material is placed in a ball mill and ground at a speed of 300 rpm for 30 min; the ground fly ash is added to a 2 mol / L NaOH solution at a solid-liquid ratio of 1:6 and stirred for 30 min to form a suspended slurry; the slurry is transferred to a microwave reactor for microwave treatment at a power of 800 W, a temperature of 70 °C, and a treatment time of 15 min; the microwave-treated slurry is washed with deionized water until the pH of the washing solution is between 6.5 and 7.5, and then the washed solid is vacuum dried at 80 °C for 4 hours; the vacuum-dried powder is pulverized to a median particle size D50 < 5 μm.
[0027] In this embodiment of the invention, the mineral composition of the lithium-magnesium slag includes magnesium hydroxide, magnesium borate and magnesium oxide, and the particle size distribution of the lithium-magnesium slag satisfies: D50 < 10 μm.
[0028] In this embodiment of the invention, the organic corrosion inhibitor is a mixture of fluorinated organosilicon copolymer and carboxylated styrene-butadiene latex in a mass ratio of 1:1.
[0029] In this embodiment of the invention, 1.1. 250 mL of a mixed solvent formed by mixing toluene and isopropanol in a volume ratio of 3:1 was taken. The mixed solvent was dehydrated by passing it through a molecular sieve with a pore size of 0.4 nm until the water content was ≤100 ppm. Then, acetylacetone was added to the dehydrated mixed solvent and mixed evenly to obtain a first mixed solvent. The amount of acetylacetone added was 0.1 wt% of the total mass of the dehydrated mixed solvent. 1.2. Add 0.2 mol of γ-aminopropyltriethoxysilane and 200 mL of the first mixed solvent to a reactor protected by nitrogen gas with a purity ≥99.999% to obtain mixed solution A; 1.3. Add 0.01 mol of 2-cyano-2-propyldodecyl trithioester and azobisisobutyronitrile initiator to mixed solution A to obtain mixed solution B; 1.4. Dissolve 0.1 mol dodecafluoroheptyl methacrylate in 50 mL of a first mixed solvent to obtain a first reaction liquid; add the first reaction liquid dropwise to mixed solution B through a constant pressure dropping funnel at 0.5 mL / min and react for 10 hours to obtain a second reaction liquid, wherein the reaction temperature is 65℃ and the mixture is continuously stirred at 300 rpm during the reaction. 1.5. The second reaction liquid was cooled to 10°C in an ice bath, and then hydroquinone was added to terminate the reaction to obtain a crude product. The amount of hydroquinone added was 0.5 wt% of the total mass of the second reaction liquid. The crude product was precipitated three times with n-heptane to obtain a precipitate. In each precipitation, 10 ml of n-heptane was added for every 1 g of crude product. The precipitate was dried under vacuum at 60°C for 12 hours to obtain a white solid copolymer, namely a fluorinated organosilicon copolymer. Carboxylated styrene-butadiene latex has a solid content ≥48%, pH ≥8.8, and particle size ≤120nm.
[0030] In this embodiment of the invention, carboxylated carbon nanotubes are prepared by reflux treatment of raw carbon nanotubes with mixed acid for 4 hours. The aspect ratio of the carboxylated carbon nanotubes is 100-150, and the mixed acid is a mixture of H2SO4 and HNO3 in a volume ratio of 3:1. The preparation steps of core-shell structured nanocomposites are as follows: 2.1. Nano-TiO2 and graphene oxide were ultrasonically dispersed in a mixture of toluene and anhydrous ethanol at a mass ratio of 1:0.3 for 30 min to obtain a dispersion. The volume ratio of toluene to anhydrous ethanol was 4:1. KH-570 silane coupling agent and acetylacetone were added to the dispersion, with the addition amounts being 3 wt% and 0.05 wt% of the dispersion mass, respectively. The mixture was then reacted at 65 °C for 6 h under nitrogen protection. The product was centrifuged and washed, and the precipitate was vacuum dried at 60 °C to obtain modified TiO2@GO powder. 2.2. The modified TiO2@GO powder was subjected to O2 plasma treatment at a power of 100 W for 2 min. 2.3. Modified TiO2@GO powder treated with O2 plasma was placed in an atomic layer deposition vacuum reactor. Magnesium bis(2,2,6,6-tetramethyl-3,5-heptadecanoic acid) and trimethyl phosphate were used as precursors. A magnesium phosphate precursor layer was deposited on the powder surface at a deposition temperature of 100°C to obtain the sample. Subsequently, the sample was annealed at 300°C for 1 hour under a nitrogen atmosphere to obtain a core-shell structured nanocomposite material.
[0031] In this embodiment of the invention, the purity of sodium molybdate is ≥99%, and the particle size distribution satisfies: D90≤12μm; the purity of sodium tripolyphosphate is ≥99%, and the particle size distribution satisfies: D90≤18μm; the specific surface area of the modified activated carbon is ≥1550m² / g. The modification method of the modified activated carbon is as follows: the activated carbon is immersed in a 2mol / L KOH solution at a solid-liquid ratio of 1:10, heated to 80℃ and stirred for 2h, then washed with deionized water until the pH value of the washing solution is between 6.5 and 7.5, and then the washed solid is dried at 105℃ for 4h to obtain the modified activated carbon.
[0032] Example 1 As a preferred embodiment of the present invention, the composition of the organic-inorganic composite anti-corrosion cementing admixture disclosed in this embodiment is shown in Table 1.
[0033] Table 1. Composition of Organic-Inorganic Composite Anti-Corrosion Cementing Admixture in Example 1
[0034] In this embodiment, the nano-reinforcement is composed of carboxylated carbon nanotubes and core-shell structured nanocomposite materials mixed at a mass ratio of 1:3.
[0035] In this embodiment, the corrosion inhibitor is a mixture of sodium molybdate, sodium tripolyphosphate, and modified activated carbon in a mass ratio of 1:1:2.
[0036] In this embodiment, the preparation method of the organic-inorganic composite anti-corrosion cementing admixture includes the following steps: S1. Mix the inorganic matrix material and corrosion inhibitor at 30wt% and 15wt% by weight respectively in a double cone mixer at 100rpm for 10min and then at 300rpm for 5min to form a dry mix. S2. After preheating the organic corrosion inhibitor (25 wt% by weight) to 40°C, add the nano-reinforcement (30 wt% by weight) in two batches and mix at 1500 rpm for 10 min to form a wet mixture. S3. Add the dry mixture to the wet mixture in three batches and mix at 1500 rpm for 20 minutes to obtain a mixed slurry. Spray dry the mixed slurry to form a shape. Control the inlet temperature of the spray drying tower to be 180℃ and the outlet temperature to be 80℃. Finally, organic-inorganic composite anti-corrosion cementing admixture No. 1 is obtained.
[0037] Example 2
[0038] As a preferred embodiment of the present invention, the composition of the organic-inorganic composite anti-corrosion cementing admixture disclosed in this embodiment is shown in Table 2.
[0039] Table 2. Composition of Organic-Inorganic Composite Anti-Corrosion Cementing Admixture in Example 2
[0040] In this embodiment, the nano-reinforcement is composed of carboxylated carbon nanotubes and core-shell structured nanocomposite materials mixed at a mass ratio of 1:5.
[0041] In this embodiment, the corrosion inhibitor is a mixture of sodium molybdate, sodium tripolyphosphate, and modified activated carbon in a mass ratio of 1:1:2.
[0042] In this embodiment, the preparation method of the organic-inorganic composite anti-corrosion cementing admixture includes the following steps: S1. Inorganic matrix material and corrosion inhibitor, with weight percentages of 42wt% and 13wt% respectively, are mixed in a double cone mixer at 100rpm for 10min and then at 300rpm for 5min to form a dry mix. S2. After preheating the organic corrosion inhibitor (20 wt% by weight) to 40°C, add the nano-reinforcement (25 wt% by weight) in two batches and mix at 1500 rpm for 10 min to form a wet mixture. S3. Add the dry mixture to the wet mixture in three batches and mix at 1500 rpm for 20 minutes to obtain a mixed slurry. Spray dry the mixed slurry to form a shape. Control the inlet temperature of the spray drying tower to be 180℃ and the outlet temperature to be 80℃. Finally, organic-inorganic composite anti-corrosion cementing admixture #2 is obtained.
[0043] Example 3
[0044] As a preferred embodiment of the present invention, the composition of the organic-inorganic composite anti-corrosion cementing admixture disclosed in this embodiment is shown in Table 3.
[0045] Table 3. Composition of Organic-Inorganic Composite Anti-Corrosion Cementing Admixture in Example 3
[0046] In this embodiment, the nano-reinforcement is composed of carboxylated carbon nanotubes and core-shell structured nanocomposite materials mixed at a mass ratio of 1:3.
[0047] In this embodiment, the corrosion inhibitor is a mixture of sodium molybdate, sodium tripolyphosphate, and modified activated carbon in a mass ratio of 1:1:3.
[0048] In this embodiment, the preparation method of the organic-inorganic composite anti-corrosion cementing admixture includes the following steps: S1. Mix the inorganic matrix material and corrosion inhibitor at 55wt% and 10wt% by weight respectively in a double cone mixer at 100rpm for 10min and then at 300rpm for 5min to form a dry mix. S2. After preheating the organic corrosion inhibitor (15 wt% by weight) to 40°C, add the nano-reinforcement (20 wt% by weight) in two batches and mix at 1500 rpm for 10 min to form a wet mixture. S3. Add the dry mixture to the wet mixture in three batches and mix at 1500 rpm for 20 minutes to obtain a mixed slurry. Spray dry the mixed slurry to form a shape. Control the inlet temperature of the spray drying tower to be 180℃ and the outlet temperature to be 80℃. Finally, organic-inorganic composite anti-corrosion cementing admixture #3 is obtained.
[0049] Comparative Example 1 Compared with Example 1, the difference in this comparative example is that the inorganic matrix material does not contain lithium magnesium slag, while all other conditions are the same, and anti-corrosion material 1# is obtained.
[0050] Comparative Example 2 Compared with Example 1, this comparative example does not contain corrosion inhibitors and uses inorganic matrix materials instead of corrosion inhibitors. All other conditions are the same, and anti-corrosion material 2# is obtained.
[0051] Test case According to GB / T 19139-2012 standard, the organic-inorganic composite anti-corrosion cementing admixtures prepared in Examples 1-3 and the anti-corrosion materials prepared in Comparative Examples 1-2 were formulated into cement slurries at a dosage of 6 wt% and a water-cement ratio of 0.44. Pure G-grade oil well cement was used to prepare a cement paste as a blank example. The cement stone samples after curing of each cement slurry and cement paste were placed in a CO2 corrosion reactor at a carbonization temperature of 90℃, a total pressure of 10 MPa, a CO2 pressure of 5 MPa, and carbonization periods of 7 days and 28 days. The mechanical properties and permeability after different carbonization periods were tested, as shown in Table 4.
[0052] Table 4. Test results of mechanical properties and permeability of various cement stone samples.
[0053] As shown in Table 4, the compressive strength degradation rate and permeability of the cement stone samples formed by cement paste showed a significant increasing trend over time, with growth rates of 15.6% and 16.5%, respectively. The cement stone samples prepared in Examples 1-3 exhibited better compressive strength and permeability than the cement paste, although both showed some deterioration, but the deterioration rate was less than 5%, indicating better corrosion resistance and a denser structure. While the cement stone samples in Comparative Examples 1-2 performed better than the cement paste, they were inferior to those in Examples 1-3. The compressive strength and permeability results in Table 4 all demonstrate that the present invention can effectively improve the compressive strength of cement stone, reduce its permeability, resist CO2 erosion, and exhibit excellent corrosion resistance.
[0054] The study found that the corrosion product of cement is calcium carbonate, and the decomposition temperature range of calcium carbonate is 600-900℃. Thermogravimetric analysis was used to measure the weight loss of cement stone in this temperature range to characterize the corrosion of cement stone under given conditions. The greater the weight loss of the sample in the above range, the more easily the sample is corroded, and vice versa.
[0055] Figure 1 The images show thermal analysis results of cement paste samples and cement stone samples prepared according to Examples 1-3 after 28 days of corrosion. The thermal analysis of the cement stone samples was conducted on a Mettle Toledo thermal analysis instrument at a heating rate of 10°C / min under nitrogen protection.
[0056] pass Figure 1 It can be seen that the mass loss of calcium carbonate in the cement stone samples of Examples 1-3 is much smaller than that in the blank example (cement paste) cement stone sample. This experimental result shows that the corrosion resistance of the cement stone samples prepared in Examples 1-3 is much greater than that of cement paste, further indicating that the present invention has excellent corrosion resistance and can significantly enhance the corrosion resistance of cementing cement in CO2 environment.
[0057] Finally, it should be noted that the above embodiments are merely preferred embodiments of the present invention used to illustrate the technical solutions of the present invention, and are not intended to limit the invention, nor are they intended to limit the patent scope of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. That is to say, any changes or refinements made to the main design concept and spirit of the present invention that are not of substantial significance, but whose technical problems are still consistent with the present invention, should be included within the protection scope of the present invention. In addition, the direct or indirect application of the technical solutions of the present invention to other related technical fields are similarly included within the patent protection scope of the present invention.
Claims
1. An organic-inorganic composite anti-corrosion cementing admixture, characterized in that, Including the following raw materials by weight percentage: Inorganic matrix material: 30-55 wt%; Organic corrosion inhibitor: 15-25 wt%; Nano-reinforcement: 20-30 wt% Corrosion inhibitor: 10-15 wt%; The inorganic matrix material is composed of metakaolin, modified fly ash and lithium-magnesium slag mixed in a mass ratio of 3:2:
1.
2. The organic-inorganic composite anti-corrosion cementing admixture according to claim 1, characterized in that, The metakaolin has an Al2O3 content ≥38%, a loss on ignition ≤1.2%, and a particle size distribution satisfying: D50<4.5μm.
3. The organic-inorganic composite anti-corrosion cementing admixture according to claim 1, characterized in that, The modified fly ash has an Al2O3 content ≥30% and a particle size distribution satisfying: D50<5μm; The modified fly ash is prepared by grinding fly ash raw material in a ball mill, adding the ground fly ash to a 2 mol / L NaOH solution at a solid-liquid ratio of 1:6, stirring to form a suspended slurry; and transferring the slurry to a microwave reactor for microwave treatment. The microwave-treated slurry was washed with deionized water until the pH of the washing solution was between 6.5 and 7.
5. The washed solid was then vacuum-dried at 80°C for 4 hours. The vacuum-dried powder was then pulverized until the particle size distribution met the requirement of D50 < 5 μm.
4. The organic-inorganic composite anti-corrosion cementing admixture according to claim 1, characterized in that, The mineral composition of the lithium-magnesium slag includes magnesium hydroxide, magnesium borate and magnesium oxide, and the particle size distribution of the lithium-magnesium slag satisfies: D50 < 10 μm.
5. The organic-inorganic composite anti-corrosion cementing admixture according to claim 1, characterized in that, The organic corrosion inhibitor is a mixture of fluorinated organosilicon copolymer and carboxylated styrene-butadiene latex in a mass ratio of 1:
1.
6. The organic-inorganic composite anti-corrosion cementing admixture according to claim 5, characterized in that, The fluorinated organosilicon copolymer was prepared by reversible addition-fragmentation chain transfer controlled polymerization of dodecafluoroheptyl methacrylate and γ-aminopropyltriethoxysilane in a molar ratio of 1:2 under nitrogen protection. The preparation steps of the fluorinated organosilicon copolymer are as follows: 1.
1. Take 250 mL of a mixed solvent formed by mixing toluene and isopropanol in a volume ratio of 3:
1. Dehydrate the mixed solvent by passing it through a molecular sieve with a pore size of 0.4 nm until the water content is ≤100 ppm. Then, add acetylacetone to the dehydrated mixed solvent and mix thoroughly to obtain the first mixed solvent. The amount of acetylacetone added is 0.1 wt% of the total mass of the dehydrated mixed solvent. 1.
2. Add 0.2 mol of γ-aminopropyltriethoxysilane and 200 mL of the first mixed solvent to a reactor protected by nitrogen gas with a purity of ≥99.999% to obtain mixed solution A; 1.
3. Add 0.01 mol of 2-cyano-2-propyldodecyl trithioester and azobisisobutyronitrile initiator to mixed solution A to obtain mixed solution B; 1.
4. Dissolve 0.1 mol dodecafluoroheptyl methacrylate in 50 mL of a first mixed solvent to obtain a first reaction liquid; add the first reaction liquid dropwise to mixed solution B through a constant pressure dropping funnel at 0.5 mL / min and react for 10 hours to obtain a second reaction liquid, wherein the reaction temperature is 65℃ and the mixture is continuously stirred at 300 rpm during the reaction. 1.
5. The second reaction liquid was cooled to 10°C in an ice bath, and then hydroquinone was added to terminate the reaction to obtain a crude product. The amount of hydroquinone added was 0.5 wt% of the total mass of the second reaction liquid. The crude product was precipitated three times with n-heptane to obtain a precipitate. In each precipitation, 10 ml of n-heptane was added for every 1 g of crude product. The precipitate was dried under vacuum at 60°C for 12 hours to obtain a white solid copolymer, namely a fluorinated organosilicon copolymer. The carboxylated styrene-butadiene latex has a solid content ≥48%, pH ≥8.8, and particle size ≤120nm.
7. The organic-inorganic composite anti-corrosion cementing admixture according to claim 1, characterized in that, The nano-reinforcement is composed of carboxylated carbon nanotubes and core-shell structured nanocomposite materials mixed in a mass ratio of 1:(3-5).
8. The organic-inorganic composite anti-corrosion cementing admixture according to claim 7, characterized in that, The carboxylated carbon nanotubes were prepared by reflux treatment of raw carbon nanotubes with mixed acid for 4 hours. The aspect ratio of the carboxylated carbon nanotubes was 100-150. The mixed acid was a mixture of H2SO4 and HNO3 in a volume ratio of 3:
1. The preparation steps of the core-shell structured nanocomposite material are as follows: 2.
1. Nano-TiO2 and graphene oxide were ultrasonically dispersed in a mixture of toluene and anhydrous ethanol at a mass ratio of 1:0.3 for 30 min to obtain a dispersion. The volume ratio of toluene to anhydrous ethanol was 4:
1. KH-570 silane coupling agent and acetylacetone were added to the dispersion, with the addition amounts being 3 wt% and 0.05 wt% of the dispersion mass, respectively. The mixture was then reacted at 65 °C for 6 h under nitrogen protection. The product was centrifuged and washed, and the precipitate was vacuum dried at 60 °C to obtain modified TiO2@GO powder. 2.
2. The modified TiO2@GO powder was subjected to O2 plasma treatment at a power of 100 W for 2 min. 2.
3. The modified TiO2@GO powder treated with O2 plasma was placed in an atomic layer deposition vacuum reactor. Magnesium bis(2,2,6,6-tetramethyl-3,5-heptadecanoic acid) and trimethyl phosphate were used as precursors. At a deposition temperature of 100°C, a magnesium phosphate precursor layer was deposited on the powder surface to obtain the sample. Subsequently, under nitrogen atmosphere protection, the sample was annealed at 300℃ for 1 hour to obtain a core-shell structured nanocomposite material.
9. The organic-inorganic composite anti-corrosion cementing admixture according to claim 1, characterized in that, The corrosion inhibitor is a mixture of sodium molybdate, sodium tripolyphosphate, and modified activated carbon in a mass ratio of 1:1:(2-3). The sodium molybdate has a purity ≥99% and a particle size distribution satisfying D90≤12μm; the sodium tripolyphosphate has a purity ≥99% and a particle size distribution satisfying D90≤18μm; the modified activated carbon has a specific surface area ≥1550m² / g. The modification method of the modified activated carbon is as follows: the activated carbon is immersed in a 2mol / L KOH solution at a solid-liquid ratio of 1:10, heated to 80℃ and stirred for 2h, then washed with deionized water until the pH value of the washing solution is between 6.5 and 7.5, and then the washed solid is dried at 105℃ for 4h to obtain the modified activated carbon.
10. A method for preparing an organic-inorganic composite anti-corrosion cementing admixture according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1. The inorganic matrix material and corrosion inhibitor are mixed in a double cone mixer at 100 rpm for 10 min and then at 300 rpm for 5 min to form a dry mixture. S2. After preheating the organic corrosion inhibitor to 40°C, add it to the nano-reinforcement in two batches and mix at 1500 rpm for 10 min to form a wet mixture. S3. Add the dry mixture to the wet mixture in three batches and mix at 1500 rpm for 20 minutes to obtain a mixed slurry. Spray dry the mixed slurry to form a shape. Control the inlet temperature of the spray drying tower to be 180℃ and the outlet temperature to be 80℃ to finally obtain an organic-inorganic composite anti-corrosion cementing admixture.