High-temperature resistant bimetallic organic framework modified oilfield scale inhibitor, its preparation method and application

Abstract

This invention relates to the field of oilfield chemistry and water treatment technology, specifically to a high-temperature resistant bimetallic organic framework modified oilfield scale inhibitor, its preparation method, and its application. It is composed of the following components in the indicated mass percentages: 50%–70% manganese-cerium bimetallic organic framework material, 20%–40% polymer dispersant, and 5%–15% environmentally friendly scale-inhibiting active ingredient. The manganese-cerium bimetallic organic framework material is a Mn-Ce-BTC material with Mn and Ce as metal nodes and 1,3,5-benzenetricarboxylic acid as ligand. The polymer dispersant is coated on the surface of the manganese-cerium bimetallic organic framework material. The environmentally friendly scale-inhibiting active ingredient is loaded within the pores of the manganese-cerium bimetallic organic framework material. This invention uses a specially designed manganese-cerium bimetallic organic framework material as a high-temperature resistant carrier. After surface polymer coating modification, it is loaded with environmentally friendly scale-inhibiting active ingredients to construct a ternary synergistic composite slow-release system of "carrier-stabilizing layer-active core," achieving efficient and long-lasting scale inhibition in high-temperature, high-salinity oilfield water.

Description

Technical Field

[0001] This invention relates to the field of oilfield chemistry and water treatment technology, specifically to a high-temperature resistant bimetallic organic framework modified oilfield scale inhibitor, its preparation method, and its application. Background Technology

[0002] During oilfield development, especially in deep wells, ultra-deep wells, or oilfields using seawater injection, produced water typically exhibits high temperatures (often exceeding 100°C), high salinity (total dissolved solids (TDS) often exceeding 150,000 mg / L), and high concentrations of calcium and magnesium ions. Under these harsh conditions, inorganic salt scale such as calcium carbonate (CaCO3) and calcium sulfate (CaSO4) readily precipitate and deposit on wellbore, pipeline, and equipment surfaces, leading to blockages in flow channels, reduced equipment efficiency, and even safety accidents, severely impacting normal oilfield production.

[0003] Currently, commonly used scale inhibitors in oilfields mainly include organophosphonates (such as ATMP and HEDP) and polymers (such as polyacrylic acid and hydrolyzed polymaleic anhydride). However, these traditional scale inhibitors have significant shortcomings in dealing with the aforementioned extreme operating conditions:

[0004] (1) Although organophosphonates have good scale inhibition performance, their chemical stability is limited. They are easily decomposed and ineffective at high temperatures, and their phosphorus content may cause environmental problems such as eutrophication of water bodies.

[0005] (2) Conventional polymer scale inhibitors are prone to molecular chain curling and degradation under high temperature and high salt conditions, which leads to a sharp decline in their dispersion and complexation capabilities and a short scale inhibition cycle;

[0006] (3) Existing products are mostly added directly in liquid form. The effective ingredients are consumed quickly in high-temperature fluids, which cannot achieve long-term sustained-release protection. Frequent dosing is required, which increases the operating cost and complexity.

[0007] Therefore, developing an oilfield scale inhibitor that combines excellent high-temperature stability, long-lasting slow-release performance, and environmental friendliness is of great significance for ensuring safe production and reducing costs and increasing efficiency in oilfields under extreme operating conditions. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a high-temperature resistant bimetallic organic framework modified oilfield scale inhibitor, its preparation method, and its application. By using a specially designed manganese-cerium (Mn-Ce) bimetallic organic framework (MOF) material as a high-temperature resistant carrier, and after surface polymer coating modification, it loads environmentally friendly scale-inhibiting active ingredients to construct a ternary synergistic composite slow-release system of "carrier-stabilizing layer-active core", thereby achieving efficient and long-lasting scale inhibition in high-temperature and high-salinity oilfield water.

[0009] This invention is achieved through the following technical solution:

[0010] This invention provides a high-temperature resistant bimetallic organic framework modified oilfield scale inhibitor, which is a solid composite composed of the following components by mass percentage:

[0011] Manganese-cerium bimetallic organic framework materials account for 50%~70%.

[0012] Polymer dispersant 20%~40%,

[0013] Environmentally friendly scale inhibitor active ingredient 5%~15%;

[0014] Among them, the manganese-cerium bimetallic organic framework material is a Mn-Ce-BTC material composed of manganese (Mn) and cerium (Ce) as metal nodes and 1,3,5-benzenetricarboxylic acid (BTC) as organic ligand; a polymer dispersant is coated on the surface of the manganese-cerium bimetallic organic framework material; and an environmentally friendly scale inhibitor active ingredient is loaded in the pores of the manganese-cerium bimetallic organic framework material.

[0015] Preferably, in the manganese-cerium bimetallic organic framework material, the molar ratio of manganese (Mn) to cerium (Ce) is 1:1.5 to 1:2.5.

[0016] More preferably, in the manganese-cerium bimetallic organic framework material, the molar ratio of manganese (Mn) to cerium (Ce) is 1:1.8 to 1:2.2.

[0017] At this ratio, Mn and Ce form optimal synergy in the MOF framework, endowing the carrier with structural stability that surpasses that of single-metal MOFs (such as Mn-BTC or Ce-BTC) under high-temperature hydrothermal conditions. This is the cornerstone for achieving long-term sustained release.

[0018] Preferably, the polymer dispersant is selected from at least one of sodium polymaleic anhydride (HPMA), sodium polyacrylate (PAAS), and sodium polyepoxysuccinate (PESA).

[0019] This coating not only further enhances the dispersibility and colloidal stability of the MOF support in harsh media, preventing its aggregation and sedimentation, but its molecular chains also have a certain scale inhibition and dispersion effect, synergistically working with the core active ingredients.

[0020] Preferably, the environmentally friendly scale inhibitor is selected from at least one of polyepoxysuccinic acid (PESA), polyaspartic acid (PASP), or their salts.

[0021] This type of component is phosphorus-free, biodegradable, environmentally friendly, and has excellent complexing and lattice distortion capabilities for calcium, magnesium, and other ions.

[0022] This invention also provides a method for preparing the above-mentioned high-temperature resistant bimetallic organic framework modified oilfield scale inhibitor, comprising the following steps:

[0023] S1. Disperse the manganese-cerium bimetallic organic framework material in a polar solvent, wherein the polar solvent is one or a mixture of water, methanol, and N,N-dimethylformamide (DMF);

[0024] S2. Adjust the pH of the system to 6-7, add the polymer dispersant under stirring conditions, and continue the reaction to allow the polymer to be fully adsorbed and coated on the surface of the manganese-cerium bimetallic organic framework material.

[0025] S3. Under mild heating and stirring conditions of 40~60℃, add environmentally friendly scale inhibitory active ingredients to the system obtained in step S2, so that they are loaded into the internal pores of the MOF carrier through physical adsorption and pore penetration.

[0026] S4. Separate the solid product by centrifugation or filtration, wash with deionized water, and dry in a vacuum drying oven at 60~80℃ to constant weight to obtain the composite slow-release scale inhibitor.

[0027] This invention also provides the application of the above-mentioned high-temperature resistant bimetallic organic framework modified oilfield scale inhibitor in inhibiting calcium carbonate and calcium sulfate scale in oilfield produced water. It is particularly suitable for extreme oilfield water treatment environments with temperatures not lower than 100°C and salinity not lower than 150,000 mg / L.

[0028] The beneficial effects of this invention are:

[0029] This invention, through a combination of material structure design and surface functionalization modification, can improve the high-temperature stability, sustained-release performance, and environmental friendliness of scale inhibitors, specifically in the following ways:

[0030] I. Enhanced Structural Stability through Synergistic Doping: By introducing manganese (Mn) and cerium (Ce) for bimetallic synergistic doping, the crystal framework stability of the MOF material with 1,3,5-benzenetricarboxylic acid as a ligand was improved. This material maintained good structural and functional stability even under high-temperature (100~140℃) and typical high-salinity produced water (TDS≥150000 mg / L) conditions, reducing the risk of collapse and aggregation, thus providing a stable carrier for scale inhibitors and extending their effective period. To further verify the thermal stability of the manganese-cerium bimetallic organic framework material, thermogravimetric analysis (TGA) was performed on the prepared Mn-Ce-BTC material under a nitrogen protective atmosphere. Its main framework did not exhibit significant decomposition behavior before approximately 300~350℃, demonstrating good thermal stability and meeting the requirements for use as a slow-release carrier for scale inhibitors under high-temperature oilfield conditions. Although the TGA was a dry-state test, combined with the results of high-temperature static scale inhibition experiments, no sudden performance drop or failure was observed, indicating that the material has sufficient stability in actual aqueous systems.

[0031] Comparative experiments demonstrate that using Mn-Ce-BTC MOF alone, or a mixture of polymer dispersant and scale inhibitor alone, results in significantly lower high-temperature scale inhibition efficiency and durability compared to the ternary composite of this invention. This confirms the inseparable synergistic effect among the Mn-Ce-BTC carrier (providing stable channels and synergistic metal nodes), the polymer coating layer (providing dispersion and secondary stability), and the environmentally friendly scale inhibitor (providing the core scale inhibition function).

[0032] II. Multiple Modifications for Long-Lasting Slow Release: A polymer dispersant is used to form a coating layer on the MOF surface, combined with environmentally friendly scale-inhibiting active ingredients loaded inside the pores, constructing a dual slow-release mechanism of "adsorption-coating". This invention is a solid composite slow-release formulation, where the scale-inhibiting active ingredients are encapsulated within stable MOF pores and released under the regulation of the polymer layer. Experiments show that its cumulative release rate is approximately 50% within 72 hours, exhibiting an ideal initial rapid release followed by a slow release curve, without sudden release, achieving long-term stable scale protection, significantly extending the dosing cycle, and enabling controllable adjustment of slow-release performance. It features high scale inhibition efficiency and a long action period.

[0033] III. Scale inhibition performance verification: at 100℃, Ca 2+ In a high-salinity simulated water system with a concentration of 3000 mg / L, static scale inhibition experiments were conducted according to Q / SY17126-2019 "Technical Specification for Corrosion and Scale Inhibitors for Oilfield Water Treatment". The results showed that the composite scale inhibitor achieved an average scale inhibition rate of over 85% for scale types such as calcium sulfate and calcium carbonate. Its scale inhibition effect was higher than that of conventional polymer-based and phosphine-based scale inhibitors, solving the problem of rapid failure of traditional scale inhibitors under such conditions.

[0034] IV. Environmental adaptability: The selected scale inhibitor active ingredients (such as PESA and PASP) are biodegradable, which reduces environmental risks and is in line with the development trend of green oilfield chemicals. In addition, this invention does not use phosphine substances, which can reduce the potential impact on water and soil ecosystems and meet the requirements of greening oilfield chemicals.

[0035] Therefore, the scale inhibitor of the present invention is suitable for scale prevention operations in oilfield produced water, water injection pipelines, gathering and transportation systems and downhole tubing. It can maintain structural stability and scale inhibition activity for a long time under high temperature and high salinity conditions, and is suitable for scale prevention applications in complex oilfield systems. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of thermogravimetric analysis (TGA) of the Mn-Ce-BTC material prepared in this invention under a nitrogen protective atmosphere.

[0037] Figure 2 The slow-release curve of the composite scale inhibitor prepared according to the present invention is shown. Detailed Implementation

[0038] To clearly illustrate the technical features of this solution, the following detailed implementation method will be used to explain the solution.

[0039] I. Testing and Characterization Methods

[0040] 1. Scale inhibition performance test: The static scale inhibition method was conducted according to the People's Republic of China Petroleum and Natural Gas Industry Standard Q / SY 17126-2019 "Technical Specification for Corrosion and Scale Inhibitors for Oilfield Water Treatment". Specifically, a solution with a salinity of 150,000 mg / L (of which Ca...) was prepared. 2+ The concentration is 3000 mg / L, HCO3 - Simulated oilfield produced water (concentration 2000 mg / L) was used. A certain amount of this water sample was placed in a high-pressure reactor, and 50 mg / L of the test sample (based on the total mass of the composite scale inhibitor) was added. After sealing, the sample was placed in an oven at a specified temperature (e.g., 100℃, 120℃, 140℃) and allowed to stand for 24 hours. After the reaction was completed, the sample was cooled to room temperature, filtered, and the residual calcium ion concentration in the filtrate was determined by disodium ethylenediaminetetraacetate (EDTA) titration. The scale inhibition rate for calcium carbonate (CaCO3) or calcium sulfate (CaSO4) was calculated according to the formula.

[0041] 2. Slow-release performance test: Accurately weigh 1.000 g of the composite scale inhibitor sample and place it in a sealed container containing 1000 mL of simulated brine (mineralization 150,000 mg / L) at 100℃. Conduct a release experiment in a constant temperature water bath shaker (speed: 100 rpm). Take 5 mL samples at predetermined time points (e.g., 2h, 6h, 12h, 24h, 48h, 72h), filter through a 0.22 μm filter membrane, and determine the concentration of the scale-inhibiting active ingredient in the filtrate using UV-Vis spectrophotometry (for scale inhibitors containing characteristic functional groups, such as PESA) at a specific wavelength (e.g., around 210 nm for PESA). Quantify the concentration using a pre-plotted standard curve. Alternatively, determine the concentration of the scale-inhibiting active ingredient in the filtrate using a total organic carbon (TOC) analyzer. Calculate the percentage of the cumulative released mass of the active ingredient at each time point relative to its initial total load mass; this is the cumulative release rate (slow-release rate).

[0042] 3. Material characterization: The specific surface area and pore size distribution of the material were determined by nitrogen adsorption-desorption (BET); the thermal stability of the material was evaluated by thermogravimetric analysis (TGA) under a nitrogen atmosphere.

[0043] II. Key Raw Materials and General Preparation Methods

[0044] 1. Preparation of manganese-cerium bimetallic organic framework materials (Mn-Ce-BTC):

[0045] Weigh 0.89 g (3.2 mmol) of manganese nitrate hexahydrate (Mn(NO3)2·6H2O) and 2.61 g (6.0 mmol) of cerium nitrate hexahydrate (Ce(NO3)3·6H2O) (Mn:Ce molar ratio = 1:1.875), and dissolve them in a mixed solvent consisting of 40 mL of N,N-dimethylformamide (DMF), 5 mL of anhydrous ethanol, and 5 mL of deionized water. Stir until completely dissolved, and label this solution A. Separately weigh 1.05 g (5.0 mmol) of 1,3,5-benzenetricarboxylic acid (H3BTC) and dissolve it in 20 mL of DMF, label this solution B. Under vigorous stirring, slowly add solution B dropwise to solution A, and continue stirring for 30 minutes to form a homogeneous mixture. Transfer this mixture to a 100 mL polytetrafluoroethylene-lined high-pressure reactor and react in an oven at 120 °C for 12 hours. After naturally cooling to room temperature, the resulting solid product was centrifuged and washed three times sequentially with DMF and anhydrous ethanol to remove unreacted raw materials and solvents. Finally, the product was dried in a vacuum drying oven at 80°C for 12 hours, and then ground to obtain a light yellow powder of Mn1Ce. 1.875 -BTC material. According to BET testing, its specific surface area is approximately 580 m². 2 / g.

[0046] By adjusting the molar ratio of manganese nitrate to cerium nitrate in equal proportions, Mn-Ce-BTC materials with different Mn / Ce ratios can be prepared in the range of 1:1.5 to 1:2.5, and these materials are all applicable to this invention.

[0047] In this embodiment, the weight-average molecular weight (Mw) of the polymer dispersant sodium polymaleic anhydride (HPMA) is preferably 800-2000; the Mw of sodium polyacrylate (PAAS) is preferably 2000-5000; and the Mw of sodium polyepoxysuccinate (PESA) as a dispersant is preferably 1000-3000. The Mw of the environmentally friendly scale inhibitory active ingredient polyepoxysuccinic acid (PESA) or its salt is preferably 1000-3000; and the Mw of polyaspartic acid (PASP) or its salt is preferably 3000-6000. These molecular weight ranges provide better dispersion and sustained-release effects.

[0048] 2. General preparation method of composite scale inhibitors:

[0049] S1. Carrier dispersion: Disperse the specified mass of Mn-Ce-BTC material in 50 mL of polar solvent (preferably a mixture of deionized water and ethanol with a volume ratio of 4:1), and sonicate for 30 minutes to form a uniform suspension.

[0050] S2. Polymer coating: Adjust the pH of the above suspension to 6.5 with 0.1 mol / L NaOH solution, and slowly add an aqueous solution (concentration 10 wt%) containing the specified mass of polymer dispersant under continuous mechanical stirring (500 rpm), and continue stirring at room temperature for 6 hours.

[0051] S3. Active ingredient loading: Heat the system from step S2 to 50°C, add the specified mass of environmentally friendly scale inhibitor active ingredient (solid or concentrated solution) at the same stirring rate, and stir at a constant temperature for 8 hours for adsorption.

[0052] S4. Post-processing: After the reaction is complete, the mixture is centrifuged (8000 rpm, 10 min) to separate the solids. The solids are washed three times with deionized water to remove physically adsorbed impurities. The obtained solids are dried in a vacuum drying oven at 70°C for 12 hours until constant weight. After grinding, the target composite slow-release scale inhibitor product is obtained.

[0053] III. Examples and Performance Testing

[0054] The following examples and comparative examples were prepared according to the general method described above, with only specific components, contents, or types changed according to the table. Unless otherwise specified, all performance test conditions are: temperature 100°C, Ca... 2+ Concentration 3000 mg / L, mineralization 150000 mg / L, reaction time 24h, scale inhibitor dosage 50 ppm.

[0055] Example 1 (Effect of Mn-Ce-BTC content and Mn / Ce molar ratio)

[0056] To verify the effectiveness of the material within the Mn:Ce molar ratio range (1:1.5~1:2.5), this embodiment systematically investigated the effects of the carrier content and its metal molar ratio. In the experiment, the polymer dispersant was fixed at HPMA (30%), and the environmentally friendly scale inhibitor active ingredient was PESA (10%). The content of the Mn-Ce-BTC carrier and the Mn / Ce molar ratio were varied.

[0057] Preparation of supports with different Mn / Ce molar ratios:

[0058] Mn:Ce = 1:1.5: Following the general method, the feed was adjusted to 1.00 g (3.6 mmol) of manganese nitrate hexahydrate and 2.35 g (5.4 mmol) of cerium nitrate hexahydrate, while the amount of ligand H3BTC remained unchanged, to obtain Mn1Ce. 1.5 -BTC.

[0059] Mn:Ce = 1:2.5: Following the general method, the feed was adjusted to 0.80 g (2.9 mmol) manganese nitrate hexahydrate and 3.15 g (7.2 mmol) cerium nitrate hexahydrate, while the amount of ligand H3BTC remained unchanged, to obtain Mn1Ce. 2.5 -BTC. The results of scale inhibition and sustained-release performance tests under different conditions are shown in Table 1 below:

[0060] Table 1. Scale inhibition performance under different Mn-Ce-BTC contents and Mn / Ce molar ratios

[0061] serial number Mn-Ce-BTC content (wt%) Mn:Ce molar ratio <![CDATA[Scale inhibition rate of CaCO3(%)]]> <![CDATA[CaSO4 scale inhibition rate (%)]]> 72-hour sustained release rate (%) Example 1-1 50 1：1.875 90.5 88.7 55 Examples 1-2 60 1：1.875 92.8 90.2 50 Examples 1-3 70 1：1.875 93.5 91.8 48 Examples 1-4 60 1：1. 5 92.1 89.8 49 Examples 1-5 60 1：2.5 91.9 89.5 48 Comparative Example 1-1 0 - 35.2 28.7 No effective sustained release

[0062] The results show that the introduction of the Mn-Ce-BTC carrier is key to achieving high performance. Not only does it exhibit excellent performance within the 50%–70% content range, but the prepared composite scale inhibitor also demonstrates high and stable scale inhibition rates (>89%) and ideal sustained-release rates (48–50%) across the entire Mn:Ce molar ratio range of 1:1.5 to 1:2.5, proving the universality and effectiveness of the technical solution of this invention within the specified parameter range. Considering both performance and economy, the preferred Mn-Ce-BTC content is 55%–65%, and the preferred Mn:Ce molar ratio is 1:1.8–1:2.2.

[0063] High temperature stability test

[0064] To verify the thermal stability of the composite system, static scale inhibition experiments were conducted using the formulations from Examples 1-2 (Mn-Ce-BTC content 60%) at different temperatures. The scale inhibition performance at different temperatures is shown in Table 2 below.

[0065] Table 2. Scale inhibition performance at different temperatures

[0066] Temperature (°C) <![CDATA[Calcium carbonate scale inhibition rate (%)]]> <![CDATA[CaSO4 scale inhibition rate (%)]]> 72-hour sustained release rate (%) 100 92.8 90.2 50 120 90.3 86.5 48 140 86.8 85.6 45

[0067] When the temperature rises to 140℃, the scale inhibition rate remains above 85%, indicating that the system still has good scale inhibition stability under high temperature and high salt environment. As the temperature rises, the MOF framework structure tends to be denser and more stable, and the confinement effect of the polymer coating layer is enhanced, making the release process of active ingredients more controlled. The cumulative release ratio within 72h decreases slightly, but still maintains stable and controllable slow-release characteristics.

[0068] The thermal stability of the prepared Mn-Ce-BTC support was characterized. Figure 1 As shown, its thermogravimetric analysis (TGA) curves indicate that the main framework of the material did not show significant decomposition before about 300°C under a nitrogen atmosphere, demonstrating good thermal stability, which provides a basis for its use as a slow-release carrier in high-temperature oilfield environments.

[0069] Example 2 (Influence of Polymer Dispersant Type)

[0070] The Mn-Ce-BTC content is fixed at 60%, and the content of the environmentally friendly active ingredient PESA remains constant (10%), with only the type of polymer dispersant being replaced. The scale inhibition performance under different polymer dispersants is shown in Table 3 below:

[0071] Table 3. Scale inhibition performance under different polymer dispersants

[0072] serial number Types of dispersants <![CDATA[Scale inhibition rate of CaCO3(%)]]> <![CDATA[CaSO4 scale inhibition rate (%)]]> 72-hour sustained release rate (%) Example 2-1 HPMA 92.8 90.2 50 Example 2-2 PAAS 92.1 90.5 48 Example 2-3 PESA 91.2 89.7 55 Comparative Example 2-1 No addition 60.0 55.0 85

[0073] The results showed that HPMA, PAAS, and PESA all significantly improved scale inhibition performance, with HPMA exhibiting the best overall performance, demonstrating good dispersion stability and slow-release regulation. In Comparative Example 2-1, without dispersant, although the release rate was high, it was a rapid burst release, failing to maintain an effective scale inhibition concentration, resulting in a significant decrease in scale inhibition rate.

[0074] Example 3 (Influence of environmentally friendly scale-inhibiting active ingredients)

[0075] With the Mn-Ce-BTC content fixed at 60% and the HPMA content fixed at 30%, different scale-inhibiting active ingredients were investigated. A comparative study was conducted using the phosphine-based scale inhibitor HEDP. The scale inhibition performance under different scale-inhibiting active ingredients is shown in Table 4 below.

[0076] Table 4. Scale inhibition performance under different scale inhibitory active ingredients

[0077] serial number Scale inhibitor active ingredients <![CDATA[Scale inhibition rate of CaCO3(%)]]> <![CDATA[CaSO4 scale inhibition rate (%)]]> 72-hour sustained release rate (%) Example 3-1 PESA 92.8 90.2 50 Example 3-2 PASP 92.1 90.5 48 Example 3-3 HEDP 95.2 93.5 20

[0078] The results showed that PESA and PASP had the best overall performance; although HEDP showed a high scale inhibition rate in the short term, its slow-release performance was poor under high temperature conditions, making it difficult to meet the long-term scale prevention needs of oilfields.

[0079] Comparative Example: To verify the synergistic effect and innovativeness of the ternary composite system, comparative experiments were conducted on the absence and substitution of key components. All test conditions were standardized as follows: temperature 100℃, mineralization 150,000 mg / L, Ca... 2+ 3000 mg / L, reaction time 24 h, dosage 50 ppm.

[0080] Table 5. Impact of Key Component Deletion on Performance

[0081] serial number Comparison and explanation <![CDATA[CaCO3 scale inhibition rate (%)]]> <![CDATA[CaSO4 scale inhibition rate (%)]]> 72-hour sustained release rate (%) Examples 1-2 Standard complete formula 92.8 90.2 50 Comparative Example 1-1 Missing Mn-Ce-BTC 35.2 28.7 none Comparative Examples 1-2 HPMA only (without vector and PESA) 45.0 41.3 12 Comparative Examples 1-3 PASP only (without vector and HPMA) 55.8 50.6 18 Comparative Examples 1-4 Mn-BTC (Ce-free) 70.2 66.5 25 Comparative Examples 1-5 Ce-BTC (Mn-free) 68.7 64.8 23

[0082] The results showed that the performance was significantly reduced when any key component (carrier, dispersant, active ingredient) was missing or when a single metal MOF was used to replace a bimetallic MOF, proving that the synergistic effect of the three components and the synergistic effect of the Mn-Ce bimetallic MOF were indispensable.

[0083] Table 6. Effects of Key Component Substitution

[0084] serial number Comparison and explanation <![CDATA[Scale inhibition rate of CaCO3(%)]]> <![CDATA[CaSO4 scale inhibition rate (%)]]> 72-hour sustained release rate (%) Examples 1-2 Complete formula 92.8 90.2 50 Comparative Example 2-1 Replace Mn-Ce-BTC with HKUST-1 61.3 53.6 82 Comparative Example 2-2 Replace environmentally friendly active ingredients with HEDP 95.2 93.5 20

[0085] Comparative Example 2-1 uses a common Cu-based MOF (HKUST-1) instead of the carrier of this invention. Although the slow release rate is high, the scale inhibition rate is low, indicating that its controlled release ability is poor and harmful burst release occurs. Mn-Ce-BTC shows higher high-temperature structural stability after replacing the traditional Cu-based MOF (HKUST-1). Comparative Example 2-2 further confirms that phosphine-based components lack long-term effectiveness, and environmentally friendly active ingredients have significant slow release and environmental advantages over phosphine-based scale inhibitors.

[0086] Table 7 Performance Comparison with Commercially Available Products

[0087] serial number Comparison and explanation <![CDATA[Scale inhibition rate of CaCO3(%)]]> <![CDATA[CaSO4 scale inhibition rate (%)]]> 72-hour sustained release rate (%) Examples 1-2 Product of this invention 92.8 90.2 50 Comparative Example 3-1 Commercially available polymer scale inhibitors 68.4 70.2 none Comparative Example 3-2 Commercially available phosphorus scale inhibitors 94.6 92.7 21

[0088] While maintaining a scale inhibition rate comparable to that of high-efficiency phosphine-based products, the product of this invention has a long-lasting slow-release performance (50% slow-release rate at 72h) that far exceeds that of phosphine-based products (21%), and is also environmentally friendly, with obvious comprehensive advantages.

[0089] Taking a standard formulation with 60 wt% Mn-Ce-BTC, 30 wt% HPMA, and 10 wt% PESA as an example, its sustained-release behavior was characterized. Figure 2 As shown, the results indicate that the slow-release curve of the composite scale inhibitor exhibits a clear characteristic of rapid release followed by slow release: approximately 20% is released cumulatively within the first 12 hours, approximately 35% within 24 hours, and approximately 50% within 72 hours. No significant burst release phenomenon occurs during the entire release process, indicating that the Mn-Ce-BTC metal-organic framework pore structure and polymer coating layer have significant confinement and controlled release effects on the scale-inhibiting active ingredients.

[0090] Mn-Ce-BTC framework adsorption-catalysis mechanism: The Mn-Ce-BTC metal-organic framework, with its high specific surface area and well-ordered channels, can preferentially adsorb Ca from water. 2+ Ba 2+ SO4 2- The presence of scale-forming ions effectively reduces localized supersaturation. More importantly, Ce... 3+ / Ce 4+ The variable valence state and unsaturated electron shell structure of Ce can interfere with the normal growth process of nucleated microcrystals; 3 + / Ce 4+ High-valence ions may participate in competitive adsorption at the crystal growth interface, inducing lattice distortion, making it difficult for them to form dense hard scale, and instead generating loose and fragile flocculent matter.

[0091] Polymer coating dispersion mechanism: The coating layer formed by polymer dispersants (such as HPMA) on the surface of MOF not only effectively enhances the stability of the MOF skeleton in high temperature and high salt environment and prevents it from agglomerating and collapsing, but also the negatively charged groups on its molecular chain can be adsorbed on the surface of microcrystals and dispersed and suspended in water through steric hindrance and electrostatic repulsion effects, preventing it from further agglomerating and depositing.

[0092] Environmentally friendly active ingredient complexation mechanism: Environmentally friendly scale inhibitors such as polyepoxysuccinic acid (PESA) loaded in the MOF channels can efficiently complex metal ions at a concentration far below the stoichiometric ratio through slow release, surrounding the active growth points of scale crystals and disrupting their ordered lattice arrangement.

[0093] MOF pore-channel sustained-release mechanism: The regularized pores of MOFs confine and protect the active ingredients, preventing their rapid decomposition at high temperatures. The active ingredients are slowly released through concentration gradient diffusion and ion exchange, achieving intelligent controlled release of only the required amount, thereby effectively extending the action period.

[0094] The composite scale inhibitor provided in this embodiment achieves highly efficient and long-lasting scale inhibition under extreme conditions of high temperature (≥100℃) and high mineralization (≥150000 mg / L) through a unique ternary structure of "Mn-Ce-BTC carrier-polymer dispersant coating layer-environmentally friendly scale-inhibiting active ingredient core". The composite scale inhibitor system achieves highly efficient and broad-spectrum scale inhibition through a four-pronged mechanism of adsorption-dispersion-complexation-slow release. The Mn-Ce-BTC framework adsorbs Ca... 2+ SO4 2- Plasma induces crystal distortion; a polymer dispersant forms a stable coating layer on its surface, preventing agglomeration and collapse; environmentally friendly active ingredients are slowly released within the MOF channels, complexing with metal ions and disrupting the crystal lattice structure. Experiments demonstrate that this system achieves excellent comprehensive performance through the synergistic effects of multiple mechanisms, including adsorption and lattice interference within the Mn-Ce-BTC framework, spatial stability and dispersion of the polymer coating layer, and the slow release and complexation of the environmentally friendly scale inhibitor within the channels.

[0095] The results of each embodiment and comparative example consistently demonstrate that the product of the present invention is significantly superior to commercially available phosphine-based or polymer scale inhibitors in terms of scale inhibition rate, slow-release performance, and environmental friendliness.

[0096] Of course, the above description is not limited to the examples above. Technical features not described in this invention can be implemented by or using existing technology, and will not be repeated here. The above embodiments and drawings are only used to illustrate the technical solutions of this invention and are not intended to limit this invention. This invention has been described in detail with reference to preferred embodiments. Those skilled in the art should understand that any changes, modifications, additions or substitutions made by those skilled in the art within the scope of this invention do not depart from the spirit of this invention and should also fall within the scope of protection of the claims of this invention.

Claims

1. A high temperature resistant bimetallic organic framework modified oilfield scale inhibitor characterized in that: It is composed of the following components in mass percentage: Manganese-cerium bimetallic organic framework materials account for 50%~70%. Polymer dispersant 20%~40%, Environmentally friendly scale inhibitor active ingredient 5%~15%; Among them, the manganese-cerium bimetallic organic framework material is a Mn-Ce-BTC material composed of Mn and Ce as metal nodes and 1,3,5-benzenetricarboxylic acid as ligand; wherein the molar ratio of Mn to Ce is 1:1.8~1:2.

2. The polymer dispersant is at least one of sodium polyacrylate and sodium polyepoxysuccinate; The environmentally friendly scale inhibitory active ingredient is at least one of polyepoxysuccinic acid and polyaspartic acid; A polymer dispersant is coated on the surface of a manganese-cerium bimetallic organic framework material, and an environmentally friendly scale-inhibiting active ingredient is loaded into the pores of the manganese-cerium bimetallic organic framework material. Oilfield scale inhibitors are used for scale inhibition treatment in oilfield produced water systems with a salinity of not less than 150,000 mg / L and a temperature of not less than 100℃. The preparation method of this scale inhibitor includes the following steps: S1. Disperse the manganese-cerium bimetallic organic framework material in a polar solvent; S2. Under pH conditions of 6-7, an aqueous solution containing a polymer dispersant is slowly added dropwise to the system of step S1 under continuous mechanical stirring, and stirred to form a coating layer on the surface of the manganese-cerium bimetallic organic framework material. S3. At 40~60℃, add environmentally friendly scale inhibitory active ingredients to the system in step S2 and stir to load them into the pores of the manganese cerium bimetallic organic framework material. S4. Separate the solid product and dry it under vacuum at 60~80℃ to obtain the composite slow-release scale inhibitor.

2. The application of the high-temperature resistant bimetallic organic framework modified oilfield scale inhibitor as described in claim 1 in inhibiting calcium carbonate and calcium sulfate scale in oilfield produced water.

3. Use according to claim 2, characterized in that: The compound slow-release scale inhibitor is added to oilfield produced water with a temperature of not less than 100℃ and a salinity of not less than 150,000 mg / L. The dosage is determined based on the concentration of scale-forming ions in the water.

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