A hydrotalcite modified non-ionic composite nano thickened oil viscosity reducer, and a preparation method and application thereof
Patent Information
- Application Number
- CN202610994711.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-06
- Publication Date
- 2026-09-25
AI Technical Summary
[0004]目前，由于纳米颗粒表面能高，纳米颗粒分散稳定性不足，易团聚沉降
[0028]本发明首先通过化学合成得到不同聚合度的非离子表面活性剂，再以纳米水滑石为基础，使用静电调节，使得非离子表面活性剂与纳米水滑石通过静电吸引相互作用，从而得到双亲型复合纳米稠油降粘剂。本发明可显著提升降粘剂的油相中的分散稳定性和普适性。同时，本发明原料环保、工艺简单，所得产品对稠油具有优异的降粘效果。
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of flow improvers in the petroleum industry, specifically relating to a hydrotalcite-modified nonionic composite nano-thick oil viscosity reducer, its preparation method, and its application. Background Technology
[0002] Adding viscosity reducers during heavy oil transportation can effectively lower crude oil viscosity, pour point, and yield stress, reduce pipeline friction and pumping pressure drop, and decrease the dependence on energy and light oil resources for heated and diluted transportation. Simultaneously, heavy oil viscosity reducers can improve the low-temperature fluidity of heavy oil by weakening the gum / asphaltite aggregation network, thereby enhancing the safety and economy of pipeline transportation.
[0003] Traditional small-molecule surfactants or single oil-soluble viscosity reducers typically only target a single aspect of the oil-water interface or oil phase aggregation structure, making it difficult to simultaneously address multi-scale problems such as asphaltenes / colloid aggregation, wax crystal network construction, oil film adhesion on rock surfaces, and flow resistance in porous media. Nanocomposites, due to their high specific surface area, tunable surface chemistry, multi-interfacial adsorption capacity, and synergistic effects with polymers / surfactants, can exert combined effects in areas such as oil phase depolymerization, wax crystal morphology regulation, interfacial tension reduction, wettability alteration, and oil film stripping, representing an important direction for the development of heavy oil viscosity reducers.
[0004] Currently, due to their high surface energy, nanoparticles suffer from insufficient dispersion stability and are prone to aggregation and sedimentation. Therefore, the development of stable, dispersed, highly efficient, and green-economical nanocomposites is of great significance. Summary of the Invention
[0005] Based on the above-mentioned technical problems, this invention proposes a non-ionic composite nano-thick oil viscosity reducer based on hydrotalcite modification, its preparation method, and its application.
[0006] To achieve the above-mentioned technical effects, the present invention employs the following technical means:
[0007] This invention first discloses a method for preparing a hydrotalcite-modified nonionic composite nano-thick oil viscosity reducer, comprising the following steps:
[0008] S1. Preparation of unmodified hydrotalcite: Mg / Al-LDH was first synthesized by hydrothermal synthesis, centrifuged, washed, vacuum dried and ground to obtain unmodified hydrotalcite.
[0009] S2. Preparation of nonionic surfactants:
[0010] (1) Pretreatment: Add alkylamine to a high-pressure reactor, heat to 40-80℃ and stir under an inert atmosphere, then slowly add ethylene oxide in a catalyst-free environment to generate dihydroxyethylalkylamine;
[0011] (2) Polymerization reaction: Add an alkaline catalyst to dihydroxyethylalkylamine, dehydrate, vacuum and replace with inert gas, continue to add ethylene oxide, react at 70-120℃ for 8-24h, after the reaction is completed, keep warm and stand for 3-6h to obtain dihydroxyethylalkylamine polyoxyethylene ether.
[0012] (3) Post-treatment: Inert gas is circulated into dihydroxyethylalkylamine polyoxyethylene ether, and after the end, organic acid is added to neutralize it. After filtration and cooling, a nonionic surfactant is obtained.
[0013] S3. Preparation of composite nano-thick oil viscosity reducer: Add mixed organic solvent to a round-bottom flask, adjust the pH value of the system, add unmodified hydrotalcite, and ultrasonically disperse it evenly. Then add the nonionic surfactant prepared above, adjust the temperature to 50-100℃ and continue the reaction for 4-12 hours. After the reaction is completed, centrifuge and take the lower layer precipitate. Add the precipitate to the pre-prepared mixed solution and ultrasonically treat it for 30-60 minutes. Then centrifuge, wash and vacuum dry to obtain composite nano-thick oil viscosity reducer (named M-LDH).
[0014] Furthermore, in step S1, the molar ratio of magnesium to aluminum is 3:1, the hydrothermal synthesis temperature is 80-180℃, and the hydrothermal synthesis time is 3-6h.
[0015] Further, in step S2, the alkylamine is one or a mixture of two or more straight-chain alkylamines with 12 to 22 carbon atoms;
[0016] The molar ratio of the alkylamine to ethylene oxide is 1:n, where n = 5~50.
[0017] Further, in step S2, the alkaline catalyst is one of NaOH, sodium fatty alcohol, and sodium ethoxide; the amount of alkaline catalyst added is calculated as 0.1% to 0.3% of the theoretical total mass of the dihydroxyethylalkylamine polyoxyethylene ether obtained from the polymerization reaction.
[0018] The sodium lauryl alcohol salt is one of sodium lauryl alcohol or sodium octadecanol.
[0019] The organic acid is one of glacial acetic acid, citric acid, and lactic acid, and the amount of organic acid added corresponds to the acid equivalent: acid value 1.07~1.25 mgKOH / g.
[0020] Further, in step S3, the mixed organic solvent is prepared by mixing ethanol and water in a volume ratio of 2:8.
[0021] Furthermore, in step S3, the pH value is 8-11; the reagent used to adjust the pH value is NaOH.
[0022] Further, in step S3, the mixed solution is a mixed solution prepared by ethanol and acetone in a volume ratio of 3:7 to 7:3.
[0023] The present invention also discloses a hydrotalcite-modified nonionic composite nano-thick oil viscosity reducer prepared according to any of the above preparation methods.
[0024] This invention also discloses a hydrotalcite-modified nonionic composite nano-thick oil viscosity reducer prepared according to any of the above preparation methods, wherein:
[0025] The heavy oil viscosity reducer is an amphiphilic nanocomposite material, comprising hydrotalcite particles and an oligomeric nonionic surfactant modifier, wherein the oligomeric nonionic surfactant is bound to the surface of the hydrotalcite particles by electrostatic adsorption.
[0026] This invention also discloses the application of the above-mentioned hydrotalcite-modified nonionic composite nano-heavy oil viscosity reducer in heavy oil extraction and pipeline transportation.
[0027] The beneficial technical effects of the present invention are as follows:
[0028] This invention first synthesizes nonionic surfactants with different degrees of polymerization through chemical synthesis. Then, based on nano-hydrotalcite, electrostatic regulation is used to allow the nonionic surfactants and nano-hydrotalcite to interact through electrostatic attraction, thereby obtaining an amphiphilic composite nano-thick oil viscosity reducer. This invention can significantly improve the dispersion stability and versatility of the viscosity reducer in the oil phase. Furthermore, the raw materials used in this invention are environmentally friendly, the process is simple, and the resulting product exhibits excellent viscosity-reducing effects on heavy oils.
[0029] Specifically, the preparation method of the present invention and the obtained heavy oil viscosity reducer have the following advantages:
[0030] (1) Synergistic effect of multiple mechanisms: Nanocomposites have a high specific surface area and designable surface functional groups, which can adsorb or disturb heavy components such as asphaltene and gum, weaken their π-π stacking, hydrogen bonding, van der Waals interaction and polar association, thereby destroying the three-dimensional aggregation network in heavy oil.
[0031] (2) Compared with polymer viscosity reducers, it has better structural stability: Polymer viscosity reducers may degrade, curl, or experience performance degradation under high temperature, high salinity, and shear conditions. In contrast, inorganic nanoparticles themselves have high thermal and chemical stability, and after organic modification or composite formation, they can balance dispersibility and interfacial activity. Therefore, whether in high-temperature oil reservoirs, long-distance transportation, or complex water quality conditions, nanocomposite materials have better potential for environmental adaptability.
[0032] (3) Excellent compatibility and dispersibility: Through chemical modification, the surface of hydrotalcite has polar and non-polar functional groups, which not only allows it to be stably dispersed in oil, but also allows its polar side chains to interact better with the asphaltenes in crude oil.
[0033] (4) Reduced cost: The prepared nanocomposite material does not require dispersion or dilution, which greatly reduces the cost and has little impact on the quality of oil products. Attached Figure Description
[0034] Figure 1 The figure shows the experimental results of the effect of the composite nano-thick oil viscosity reducer of Example 1, Comparative Example 1, and Comparative Example 2 on the viscosity of the same crude oil.
[0035] Figure 2 The Fourier transform infrared spectrum is shown for the nanocomposite thick oil viscosity reducer prepared in Example 1 of this invention.
[0036] Figure 3 The nano-composite thick oil viscosity reducer prepared in Example 1 of this invention is used in water ( Figure 3 (as shown in a) and diesel ( Figure 3 (b) Comparison of dispersion stability experiments at different times.
[0037] Figure 4 Before adding the nano-composite heavy oil viscosity reducer prepared in Example 1 of this invention to heavy oil ( Figure 4 a) and after adding heavy oil ( Figure 4 b) Characterization diagrams of in-situ oil 1H NMR and 1C NMR spectra. Detailed Implementation
[0038] The surface of magnesium-aluminum layered double hydroxide (MLD) layers is rich in -OH groups. These hydroxyl groups can form hydrogen bonds or polar interactions with carboxyl, hydroxyl, and heteroatom groups in the gum and asphaltene molecules of heavy oil. Compared with some polymeric viscosity reducers, magnesium-aluminum MLD has an inorganic layered framework, exhibiting better thermal and structural stability. However, due to its strong hydrophilicity, unmodified magnesium-aluminum MLD tends to agglomerate in the oil phase, resulting in poor dispersion stability.
[0039] Based on this, the present invention synthesizes nonionic surfactants with different degrees of polymerization, and through electrostatic regulation, enables the nonionic surfactants to interact with magnesium aluminum hydrotalcite through electrostatic attraction, thereby modifying the surface of magnesium aluminum hydrotalcite, regulating interfacial activity, and thus preparing a composite nano-thick oil viscosity reducer with high efficiency.
[0040] This invention transforms hydrotalcite from an inert, hydrophilic inorganic nanomaterial into an amphiphilic nanocomposite viscosity reducer that better acts on the asphaltene and gum of crude oil by surface organic chemical modification.
[0041] The specific steps include:
[0042] (1) Preparation of unmodified magnesium aluminum hydrotalcite: Mg / Al-LDH was first synthesized by hydrothermal synthesis, centrifuged, washed, vacuum dried and then ground to obtain unmodified hydrotalcite.
[0043] (2) Synthesis of nonionic surfactants:
[0044] (2.1) Pretreatment: Alkylamine was added to a high-pressure reactor and heated and stirred under an inert atmosphere. Then, ethylene oxide was slowly added in a catalyst-free environment to generate dihydroxyethylalkylamine.
[0045] (2.2) Polymerization reaction: Add alkaline catalyst, dehydrate, vacuum and replace with inert gas, continue to add ethylene oxide, and after the reaction is completed, keep warm and stand.
[0046] (2.3) Post-treatment: Inert gas is circulated through the system, and organic acid is added to neutralize the gas after the process is completed. The system is then filtered and cooled to obtain a nonionic surfactant.
[0047] (3) Preparation of composite nanomaterials: Add organic solvent and hydrotalcite prepared in step S1, disperse evenly by ultrasonication, adjust pH value, add nonionic surfactant, and continue reaction. After the reaction is completed, centrifuge to take the lower precipitate, add the precipitate to the pre-prepared mixed solution, disperse by ultrasonication, then centrifuge, wash, and vacuum dry to obtain composite nano-thick oil viscosity reducer.
[0048] The present invention will be further described below with reference to specific embodiments.
[0049] Example 1
[0050] (1) Preparation of unmodified hydrotalcite:
[0051] Mg / Al-LDH was synthesized by hydrothermal synthesis at 160℃ for 6 hours in an alkaline environment. After centrifugation, washing, vacuum drying, and grinding, unmodified hydrotalcite was obtained.
[0052] (2) Synthesis of nonionic surfactants:
[0053] Pretreatment: 1 mol of octadecylamine was added to a high-pressure reactor and heated to 40°C under an inert atmosphere. Then, 5 mol of ethylene oxide was slowly added dropwise in a catalyst-free environment to generate dihydroxyethyloctadecylamine. Polymerization reaction: 0.6 g of NaOH was added for dehydration, vacuuming, and inert gas replacement. 25 mol of ethylene oxide was then added, and the reaction was carried out at 70°C for 12 hours. After the reaction was complete, the mixture was allowed to stand at this temperature for 6 hours. Post-treatment: Inert gas was circulated through the reactor. After the reaction was complete, an organic acid was added for neutralization, followed by filtration and cooling to obtain a nonionic surfactant.
[0054] (3) Preparation of composite nano-thick oil viscosity reducer:
[0055] In a round-bottom flask, add an ethanol / water mixture, adjust the pH to 9, then add 3g of the hydrotalcite prepared in the previous step, and after ultrasonic dispersion, add 2g of nonionic surfactant. Under an inert atmosphere, at a temperature of 70℃, react for 4 hours.
[0056] (4) Post-treatment of composite nano-thick oil viscosity reducer:
[0057] After the reaction was completed, the lower layer of precipitate was removed by centrifugation. The precipitate was added to a pre-prepared solution and sonicated for 30 minutes. Then, it was centrifuged, washed, and vacuum dried to obtain the composite nano-thick oil viscosity reducer (sample A).
[0058] Fourier transform infrared spectroscopy was performed on the nanocomposite heavy oil viscosity reducer prepared in Example 1, and the results are as follows: Figure 2 As shown: Fourier transform infrared (FTIR) characterization was performed on the nanoparticles before and after modification. Since the absorption peaks of the amine form were covered by the absorption peaks of the hydrotalcite (-OH), water, and ether forms, the presence of -CH2- and COC structures was determined to indicate whether these structures affected the surface. Figure 2 It can be seen that at 2925cm -1 The characteristic peak at 1105 cm⁻¹ is attributed to the antisymmetric stretching vibration of the -CH₂- alkyl chain in the alkylamine polyoxyethylene ether. -1 and 1064cm -1 The enhanced absorption peak is attributed to the stretching vibration of COC at 748 cm⁻¹. -1 The enhanced characteristic peak at this location is attributed to the out-of-plane oscillation of -CH2-. Based on the above results, it can be preliminarily determined that alkylamine polyoxyethylene ether has been successfully applied to the surface of hydrotalcite.
[0059] The dispersion stability of the nanocomposite heavy oil viscosity reducer prepared in Example 1 was tested. Dispersion stability experiments were conducted on LDH and sample A in water and diesel oil. Figure 3 a. It can be seen that the modified hydrotalcite has improved dispersion stability in water compared to the unmodified hydrotalcite, indicating the presence of polar side chains in the nonionic surfactant, thus explaining this experimental phenomenon; through Figure 3 As can be seen from b, the modified hydrotalcite exhibits more stable dispersion in oil. This is due to the presence of alkyl side chains in the nonionic surfactant, which makes its surface more oleophilic, thus resulting in this phenomenon. The above experimental phenomena also indirectly reflect the successful action of the nonionic surfactant on the surface of the hydrotalcite.
[0060] The in-situ oil samples before and after the addition of the nanocomposite heavy oil viscosity reducer prepared in Example 1 were characterized by proton NMR and carbon NMR spectra. The results are as follows: Figure 4As shown: Figure 4 a represents oil samples before and after the addition of the nano-composite thick oil viscosity reducer. 1 HNMR showed a more prominent peak in the oil sample at 2.1-2.3 ppm, indicating that the nano-composite viscosity reducer made the asphaltenes in the crude oil more dispersed, thus weakening the hydrogen shielding effect at the α-position of the aromatic ring, resulting in the appearance of the peak. Figure 4 b represents oil samples before and after the addition of the nano-composite thick oil viscosity reducer. 13 The CNMR spectrum shows a distinct peak at 125-132 ppm, indicating improved mobility of aromatic components, which macroscopically manifests as a decrease in viscosity. The characterization results further demonstrate at the molecular level the effect of the nanocomposite heavy oil viscosity reducer on heavy oil, thereby achieving the desired viscosity reduction.
[0061] Based on the above experimental results, it can be seen that the composite nano-thick oil viscosity reducer of the present invention can improve the fluidity of thick oil by synergistically destroying the three-dimensional aggregated network structure of asphaltenes in thick oil through multiple mechanisms.
[0062] Comparative Example 1 (Sample B):
[0063] By changing the hydrothermal synthesis conditions (adjusting the reaction temperature to 100℃ and the reaction time to 3h), hydrotalcite with a smaller particle size distribution was prepared. Other conditions were the same as in Example 1.
[0064] Comparative Example 2 (Sample C):
[0065] The degree of polymerization of the nonionic surfactant was changed (the total amount of EO was adjusted to 15 mol to synthesize a nonionic surfactant with a degree of polymerization of 15), and other conditions were the same as in Example 1.
[0066] Experimental Example 1
[0067] In Examples 1, 1, and 2 of this invention, nano-composite thick oil viscosity reducers were prepared, and their viscosity-reducing effects were significant. The performance of these nano-composite thick oil viscosity reducers prepared in Examples 1, 1, and 2 is studied below.
[0068] The nanocomposite heavy oil viscosity reducers prepared in Examples 1, 1, and 2 were taken out and heat-treated at 70°C with the nanocomposite material for 1 hour. The prepared nanocomposite material requires no dispersion or dilution, significantly reducing costs while having minimal impact on oil quality. The composite nano-heavy oil viscosity reducers of Examples 1, 1, and 2 were tested using an evaluation testing system. The test results are as follows: Figure 1 As shown.
[0069] Test method: The viscosity-temperature profile of the oil samples was tested using an MCR 92 controlled stress rheometer manufactured by Antonpah AG, Austria, according to GB / T 28910-2026 "Determination of Rheological Properties of Crude Oil". The oil samples were pretreated in a 70℃ water bath with magnetic stirring for 1 hour, and then transferred to the rheometer with a controlled shear rate of 20 s⁻¹. -1 The cooling rate was 0.5℃ / min, the test temperature range was 70℃-40℃, and the viscosity change with temperature was recorded.
[0070]
[0071] Where μ0 is the original viscosity of heavy oil (without viscosity reducer, mPa•s); μ1 is the viscosity of heavy oil after adding viscosity reducer (at the same temperature and shear conditions, mPa•s).
[0072] The experimental results of the effects of samples A, B, and C on the viscosity of the same crude oil are as follows: Figure 1 As shown. From Figure 1 It can be seen that the nanocomposite viscosity reducer for heavy oil (sample A) prepared by this invention exhibits viscosity-reducing effects in the temperature range of 40-70℃, with the optimal viscosity reduction. The nanocomposite viscosity reducer can achieve high-temperature viscosity reduction with little or no dilution, significantly reducing costs during transportation.
[0073] This invention uses nano-hydrotalcite as a base and performs electrostatic conditioning, so that nonionic surfactants interact with nano-hydrotalcite through electrostatic attraction, thereby modifying the surface of nano-hydrotalcite. At the same time, the raw materials are environmentally friendly and the process is simple. The resulting product has excellent viscosity-reducing effect in crude oil extraction and transportation.
[0074] Example 2
[0075] Preparation of unmodified hydrotalcite:
[0076] Mg / Al-LDH was synthesized by hydrothermal synthesis at 100℃ for 3 hours in an alkaline environment. After centrifugation, washing, vacuum drying, and grinding, unmodified hydrotalcite was obtained.
[0077] Synthetic nonionic surfactants:
[0078] Pretreatment: 1 mol of octadecylamine was added to a high-pressure reactor and heated to 40°C under an inert atmosphere. Then, 5 mol of ethylene oxide was slowly added dropwise in a catalyst-free environment to generate dihydroxyethyloctadecylamine. Polymerization reaction: 0.6 g of NaOH was added for dehydration, vacuuming, and inert gas replacement. 25 mol of ethylene oxide was then added dropwise. The reaction temperature was 70°C, and the reaction time was 12 h. After the reaction was completed, the mixture was kept at this temperature and allowed to stand for 6 h. Post-treatment: Inert gas was circulated through the reactor. After the reaction was completed, an organic acid was added for neutralization. The mixture was then filtered and cooled to obtain a nonionic surfactant.
[0079] Preparation of composite nano-thick oil viscosity reducer:
[0080] In a round-bottom flask, add an ethanol / water mixture, adjust the pH to 10, then add 3g of the hydrotalcite prepared in the previous step, and after ultrasonic dispersion, add 2g of nonionic surfactant. Under an inert atmosphere, at a temperature of 70℃, react for 6 hours.
[0081] Post-treatment of composite nano-thick oil viscosity reducer:
[0082] After the reaction was complete, the lower layer of precipitate was removed by centrifugation. The precipitate was added to a pre-prepared solution and sonicated for 30 minutes. Then, it was centrifuged, washed, and vacuum dried to obtain the composite nano-thick oil viscosity reducer (sample B).
[0083] Example 3
[0084] Preparation of unmodified hydrotalcite:
[0085] Mg / Al-LDH was synthesized by hydrothermal synthesis at 120℃ for 6 hours in an alkaline environment. After centrifugation, washing, vacuum drying, and grinding, unmodified hydrotalcite was obtained.
[0086] Synthetic nonionic surfactants:
[0087] Pretreatment: 1 mol of octadecylamine was added to a high-pressure reactor and heated to 40°C under an inert atmosphere. Then, 5 mol of ethylene oxide was slowly added dropwise in a catalyst-free environment to generate dihydroxyethyloctadecylamine. Polymerization reaction: 0.6 g of NaOH was added for dehydration, vacuuming, and inert gas replacement. 10 mol of ethylene oxide was then added dropwise. The reaction temperature was 70°C, and the reaction time was 12 h. After the reaction was completed, the mixture was allowed to stand at this temperature for 6 h. Post-treatment: Inert gas was circulated through the reactor. After the reaction was completed, an organic acid was added for neutralization. The mixture was then filtered and cooled to obtain a nonionic surfactant.
[0088] Preparation of composite nano-thick oil viscosity reducer:
[0089] In a round-bottom flask, add an ethanol / water mixture, adjust the pH to 11, then add 3g of the hydrotalcite prepared in the previous step, and after ultrasonic dispersion, add 2g of nonionic surfactant. Under an inert atmosphere, at a temperature of 70℃, react for 4 hours.
[0090] Post-treatment of composite nano-thick oil viscosity reducer:
[0091] After the reaction was completed, the lower layer of precipitate was removed by centrifugation. The precipitate was added to a pre-prepared solution and sonicated for 30 minutes. Then, it was centrifuged, washed, and vacuum dried to obtain the composite nano-thick oil viscosity reducer (sample C).
[0092] In summary, this invention first utilizes ring-opening reactions to synthesize nonionic surfactants with varying degrees of polymerization. Then, nano-hydrotalcite is prepared through hydrothermal synthesis. Using the nano-hydrotalcite as a base, electrostatic regulation is applied, allowing the nonionic surfactants to interact with the nano-hydrotalcite through electrostatic attraction. This modifies the surface of the nano-hydrotalcite, adjusting its interfacial activity. Through surface organic chemical modification, the hydrotalcite is transformed from an inert, hydrophilic inorganic nanomaterial into an amphiphilic nanocomposite viscosity reducer that better acts on the asphaltenes and gums of crude oil. This invention uses environmentally friendly raw materials and employs a simple process, resulting in a product with excellent viscosity-reducing effects in crude oil extraction and transportation.
[0093] The specific embodiments described above do not constitute a limitation on the scope of protection of this application. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.
Claims
1. A method for preparing a hydrotalcite-modified nonionic composite nano-thick oil viscosity reducer, characterized in that... Includes the following steps: S1. Preparation of unmodified hydrotalcite: Mg / Al-LDH was first synthesized by hydrothermal synthesis, centrifuged, washed, vacuum dried and ground to obtain unmodified hydrotalcite. S2. Preparation of nonionic surfactants: (1) Pretreatment: Add alkylamine to a high-pressure reactor, heat and stir under an inert atmosphere, and then slowly add ethylene oxide under a catalyst-free environment to generate dihydroxyethylalkylamine; (2) Polymerization reaction: Add an alkaline catalyst to dihydroxyethylalkylamine, dehydrate, vacuum and replace with inert gas, continue to add ethylene oxide, and after the reaction is completed, keep warm and stand to obtain dihydroxyethylalkylamine polyoxyethylene ether. (3) Post-treatment: Inert gas is circulated into dihydroxyethylalkylamine polyoxyethylene ether, and after the end, organic acid is added to neutralize it. After filtration and cooling, a nonionic surfactant is obtained. S3. Preparation of composite nano-thick oil viscosity reducer: Add mixed organic solvent to a round-bottom flask, adjust the pH value of the system, add unmodified hydrotalcite, and ultrasonically disperse it evenly. Then add the nonionic surfactant prepared above and continue the reaction. After the reaction is completed, centrifuge to take the lower precipitate, add the precipitate to the pre-prepared mixed solution, and ultrasonically treat it for 30-60 minutes. Then centrifuge, wash and vacuum dry to obtain composite nano-thick oil viscosity reducer.
2. The preparation method according to claim 1, wherein: In step S1, the molar ratio of magnesium to aluminum is 3:1, the hydrothermal synthesis temperature is 80-180℃, and the hydrothermal synthesis time is 3-6h.
3. The preparation method according to claim 1, wherein: In step S2, the alkylamine is one or a mixture of two or more straight-chain alkylamines with 12 to 22 carbon atoms; The molar ratio of the alkylamine to ethylene oxide is 1:n, where n = 5~50.
4. The preparation method according to claim 1, wherein: In step S2, the alkaline catalyst is one of NaOH, sodium fatty alcohol, and sodium ethoxide; the amount of alkaline catalyst added is calculated as 0.1% to 0.3% of the theoretical total mass of the dihydroxyethylalkylamine polyoxyethylene ether obtained from the polymerization reaction. The sodium lauryl alcohol salt is one of sodium lauryl alcohol or sodium octadecanol. The organic acid is one of glacial acetic acid, citric acid, and lactic acid, and the amount of organic acid added corresponds to the acid equivalent: acid value 1.07~1.25 mgKOH / g.
5. The preparation method according to claim 1, wherein: In step S3, the mixed organic solvent is prepared by mixing ethanol and water in a volume ratio of 2:
8.
6. The preparation method according to claim 1, wherein: In step S3, the pH value is 8-11; the reagent used to adjust the pH value is NaOH.
7. The preparation method according to claim 1, wherein: In step S3, the mixed solution is a mixture of ethanol and acetone prepared in a volume ratio of 3:7 to 7:
3.
8. A hydrotalcite-modified nonionic composite nano-thick oil viscosity reducer prepared by the preparation method according to any one of claims 1 to 7.
9. A hydrotalcite-modified nonionic composite nano-thick oil viscosity reducer prepared by the preparation method according to any one of claims 1 to 7, wherein: The heavy oil viscosity reducer is an amphiphilic nanocomposite material, comprising hydrotalcite particles and an oligomeric nonionic surfactant modifier, wherein the oligomeric nonionic surfactant is bound to the surface of the hydrotalcite particles by electrostatic adsorption.
10. The application of the hydrotalcite-modified nonionic composite nano-viscosity reducer for heavy oil as described in claim 8 in heavy oil extraction and pipeline transportation.