Green scale inhibitor for barium sulfate and preparation method thereof

Abstract

The invention belongs to the technical field of water treatment, and particularly discloses a green scale inhibitor for barium sulfate and a preparation method thereof, the scale inhibitor is a product generated by esterification reaction of polysuccinimide and hydroxyethyl methylacrylate under alkaline conditions, and a copolymer formed by graft copolymerization of aconitic acid and sodium lignin sulfonate, wherein the mass ratio of polysuccinimide to hydroxyethyl methylacrylate to aconitic acid to sodium lignin sulfonate is 2: 4: (1-6): (1-4). The scale inhibitor is a composite copolymer formed by polymerizing and grafting a product obtained after esterification of polysuccinimide / hydroxyethyl methylacrylate, aconitic acid and sodium lignin sulfonate, has carboxyl, hydroxyl, amino, sulfonic acid and other groups at the same time, and can generate strong interaction with key ions or sites in the BaSO4 crystal growth process, so that the scale inhibitor can be used for inhibiting the growth of BaSO4 crystals. The normal growth and aggregation of BaSO4 crystals are prevented, so that the formation of BaSO4 scales is effectively inhibited.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment, and particularly relates to a green scale inhibitor for barium sulfate and a preparation method thereof. Background Art

[0002] In many fields of industrial production, such as oil extraction, chemical production, and industrial circulating water systems, the formation of barium sulfate scale is a common and troublesome problem. For example, in oil extraction, barium ions and sulfate ions contained in formation water will generate barium sulfate precipitation under specific conditions, and these precipitates will gradually accumulate on the surface of pipelines and equipment. Over time, it will cause the inner diameter of the pipeline to become smaller, hinder fluid transmission, increase pump pressure, and increase energy consumption; on heat exchange equipment, barium sulfate scale will reduce the heat transfer efficiency, affect the temperature control of the production process, and thus reduce production efficiency and product quality; in industrial circulating water systems, the accumulation of barium sulfate scale will also cause secondary problems such as the growth of microorganisms, accelerate equipment corrosion, shorten the service life of equipment, increase the maintenance cost and downtime of enterprises, and seriously affect the continuity of production and economic benefits.

[0003] Generally, industrial scale inhibitors for barium sulfate scale are used to solve this problem. However, traditional barium sulfate scale inhibitors often have various defects. For example, some phosphorus-containing scale inhibitors have a certain scale inhibition effect, but they will cause eutrophication of water bodies and environmental problems such as excessive growth of algae, and are facing increasingly strict environmental protection regulations; some polymer scale inhibitors have a high cost and complex synthesis processes, increasing the use cost and production difficulty of enterprises, and are not conducive to large-scale popularization and application; there are also some traditional scale inhibitors with unstable scale inhibition performance under complex working conditions such as high temperature and high hardness, which are difficult to meet the diverse actual needs in industrial production and cannot effectively solve various problems caused by barium sulfate scale, restricting the efficient operation and sustainable development of industrial production.

[0004] Therefore, there is an urgent need for a continuously stable and effective scale inhibitor for barium sulfate at present. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a scale inhibitor that can effectively inhibit the formation of barium sulfate scale, while meeting the requirements of green environmental protection, that is, reducing the negative impact on the environment, and having cost-effectiveness, making it feasible and competitive in industrial applications, solving various problems caused by barium sulfate scale in industrial production, and ensuring the efficient and stable operation of the production process.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] According to the first aspect of the present invention, the present invention first provides a green scale inhibitor for barium sulfate, which is a copolymer formed by graft copolymerization of the product obtained by the esterification reaction of poly(succinimide) and 2-hydroxyethyl methacrylate under alkaline conditions, aconitic acid, and sodium lignosulfonate, wherein the mass ratio of poly(succinimide) / 2-hydroxyethyl methacrylate / aconitic acid / sodium lignosulfonate is 2:4:(1-6):(1-4).

[0008] Preferably, the molar ratio of poly(succinimide) to 2-hydroxyethyl methacrylate in the product obtained by the esterification reaction of poly(succinimide) and 2-hydroxyethyl methacrylate under alkaline conditions is 1:2.

[0009] Preferably, the molar ratio of the product obtained by the esterification reaction of poly(succinimide) and 2-hydroxyethyl methacrylate under alkaline conditions, aconitic acid, and sodium lignosulfonate is 6:2:(1-3).

[0010] According to the second aspect of the present invention, the present invention also provides a preparation method of the above scale inhibitor, which includes the following steps:

[0011] S1. Mix poly(succinimide) and 2-hydroxyethyl methacrylate, add an alkali solution to control the pH = 9-10, and carry out an esterification reaction under heating conditions to obtain product A;

[0012] S2. Carry out a graft polymerization reaction on product A, an aconitic acid solution, a sodium lignosulfonate solution, and an initiator solution under heating conditions to obtain the product.

[0013] Preferably, in step S1, the alkali solution is one of sodium hydroxide solution and potassium hydroxide solution, the heating temperature is 55-60°C, and the reaction time of the esterification reaction is 3-4 h.

[0014] Preferably, in step S2, before the graft polymerization reaction, product A is heated to 85-90°C, and the graft polymerization reaction conditions are to react at 90°C for 3-4 h.

[0015] Preferably, the initiator solution is an ammonium persulfate solution.

[0016] Preferably, it further includes step S3: precipitating the solid from the product solution obtained in step S2 with methanol, filtering, washing, and vacuum drying the solid.

[0017] According to the third aspect of the present invention, the present invention also provides the application of the above scale inhibitor in water body scale inhibition.

[0018] Preferably, the water body is the water body during oilfield development, and the concentration of the scale inhibitor in the water body is 10-30 mg / L.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. The scale inhibitor of the present invention is a composite copolymer formed by polymerization and grafting of the product after the esterification of poly(succinimide) / 2-hydroxyethyl methacrylate, aconitic acid and sodium lignosulfonate. It has groups such as carboxyl, hydroxyl, amino and sulfonic acid groups at the same time, and can strongly interact with key ions or sites during the growth process of BaSO4 crystals, preventing the normal growth and aggregation of BaSO4 crystals, thereby effectively inhibiting the formation of BaSO4 scale. Aconitic acid has multiple active groups such as carboxyl groups, and sodium lignosulfonate has a complex aromatic structure and sulfonic acid groups, etc. They act synergistically with the reaction product of poly(succinimide) and 2-hydroxyethyl methacrylate, enhancing the affinity and inhibition ability for BaSO4, making it excellent in BaSO4 scale inhibition.

[0021] 2. The scale inhibitor of the present invention has great advantages in terms of raw materials. Firstly, poly(succinimide) can be prepared from renewable resources, and sodium lignosulfonate is an industrial by-product, realizing secondary utilization, and the synthesis reaction can improve the atomic utilization rate; secondly, in terms of environmental impact, there is no phosphorus discharge, avoiding water eutrophication, the synthesis adopts a green process, reducing pollutants, and has biodegradability;

[0022] 3. The preparation process of the present invention can improve the operation efficiency of industrial equipment, reduce costs, promote technological innovation, drive industrial development, comply with environmental protection policies, and ensure the sustainable operation of enterprises at the economic and social benefit levels. Description of the Drawings

[0023] For the convenience of those skilled in the art to understand, the present invention will be further described below in conjunction with the accompanying drawings;

[0024] Figure 1 It is the infrared spectrum diagram of the PSI-HEMA copolymer prepared by the present invention;

[0025] Figure 2 It is the infrared spectrum diagram of the PSI-HEMA-ANAN-SL copolymer prepared. Detailed Embodiments

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0027] An embodiment of the present invention provides a green scale inhibitor with high BaSO4 scale inhibition rate. The scale inhibitor is a copolymer formed by the esterification reaction of poly(succinimide) and 2-hydroxyethyl methacrylate under alkaline conditions (as shown in Formula 1), and the graft copolymerization of aconitic acid and sodium lignosulfonate (as shown in Formula 2). The mass ratio of poly(succinimide), 2-hydroxyethyl methacrylate, aconitic acid and sodium lignosulfonate is 2:4:(1-6):(1-4).

[0028]

[0029]

[0030] In some specific embodiments, the mass ratio of poly(succinimide), 2-hydroxyethyl methacrylate, aconitic acid and sodium lignosulfonate is preferably 2:4:1:(1-2.67), and more preferably 2:4:1:2.

[0031] In some specific embodiments, in Formula (1), x and n respectively represent the number of moles of poly(succinimide) and 2-hydroxyethyl methacrylate, and x:n = 1:2.

[0032] An embodiment of the present invention also provides a preparation method of the above scale inhibitor, including the following steps:

[0033] S1. Mix poly(succinimide) and 2-hydroxyethyl methacrylate, add an alkali solution to control the pH = 9-10, and carry out an esterification reaction under heating conditions to obtain product A;

[0034] S2. Carry out a graft polymerization reaction on product A, an aconitic acid solution, a sodium lignosulfonate solution and an initiator solution under heating conditions to obtain the product.

[0035] In some specific embodiments, in step S1, the alkali solution is one of sodium hydroxide solution and potassium hydroxide solution, the heating temperature is 55-60 °C, and the reaction time of the esterification reaction is 3-4 h.

[0036] In some specific embodiments, in step S2, before the graft polymerization reaction, product A is heated to 85-90 °C, and the graft polymerization reaction conditions are reaction at 90 °C for 3-4 h.

[0037] In some specific embodiments, the initiator solution is ammonium persulfate solution.

[0038] In some specific embodiments, it further includes step S3: precipitating the solid from the product solution obtained in step S2 with methanol, filtering, washing and vacuum drying the solid.

[0039] In the scale inhibitor provided by the embodiment of the present invention, the specific structure after the reaction of poly(succinimide) and 2-hydroxyethyl methacrylate. Poly(succinimide) contains imide groups; 2-hydroxyethyl methacrylate contains hydroxyl and ester groups, and both can participate in the interaction with BaSO4. It can itself act as a dispersant or surfactant to inhibit the growth of BaSO4. The imide groups, hydroxyl groups, ester groups, etc. in the product interact with BaSO4, showing affinity. The product may also form an adsorption layer on the surface of BaSO4 crystals, interfering with crystal growth and aggregation, thereby inhibiting the growth of BaSO4. The specific reaction process is as follows:

[0040]

[0041] In a specific embodiment, in step S2, the product A of S1 is grafted with aconitic acid and sodium lignosulfonate in the presence of initiator ammonium persulfate. The reaction formula is as follows:

[0042]

[0043] Specifically, it includes the following steps:

[0044] Prepare aconitic acid solution, sodium lignosulfonate solution and initiator ammonium persulfate solution respectively;

[0045] After heating the product A of step S1 to 85 - 90 °C, add aconitic acid solution, sodium lignosulfonate solution and initiator ammonium persulfate solution to the product A, and react at 90 °C for 3 - 4 h to obtain a green scale inhibitor.

[0046] In some specific embodiments, the initiator can be a commonly used initiator known in the polymer field, including but not limited to ammonium persulfate. The dosage of the initiator is 2 - 5% of the total mass of product A, aconitic acid and sodium lignosulfonate monomers.

[0047] To make the implementation purpose, technical solution and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be described in more detail below with reference to the drawings of the present invention.

[0048] Example 1

[0049] A preparation method of a green scale inhibitor with high BaSO4 scale inhibition rate, including the following steps:

[0050] S1. Prepare poly(succinimide) / 2-hydroxyethyl methacrylate (PSI-HEMA) polymer

[0051] Put poly(succinimide) and deionized water into a three-necked flask equipped with a thermometer, a reflux condenser, and a magnetic stir bar to obtain a poly(succinimide) suspension, where the mass-volume ratio of poly(succinimide) to deionized water is 1:10; start stirring and heat up to 55 - 60 °C. During this process, add 2-hydroxyethyl methacrylate, where the mass-volume ratio of 2-hydroxyethyl methacrylate to deionized water is 1:5, and continuously add a 10% sodium hydroxide solution dropwise during this process to adjust the pH of the reaction system to 9 - 10 and react for 3 - 4 h; after the reaction is completed, add methanol for purification to obtain the product A (PSI-HEMA) polymer.

[0052] S2. Preparation of (PSI-HEMA-ANA-SL) copolymer scale inhibitor

[0053] Weigh the following components according to percentages: in step S1, obtain the (PSI-HEMA) polymer, 20% of aconitic acid, 5% of sodium lignosulfonate, and 5% of initiator ammonium persulfate, and the sum of the mass percentages of each component is 100%.

[0054] Put the obtained product A (PSI-HEMA) into a three-necked flask, add sodium lignosulfonate and deionized water, and heat up to 85 - 90 °C; continuously add an aconitic acid solution and an ammonium persulfate solution (0.5 - 1 h) dropwise during this process, and the reaction lasts for 3 - 4 h; after the reaction is completed, take an appropriate amount and dialyze it with methanol, and finally dry it in an oven for 24 h to obtain a light yellow polymer, which is the (PSI-HEMA-ANA-SL) copolymer scale inhibitor of the present invention. Among them, the mass ratio of poly(succinimide), 2-hydroxyethyl methacrylate, aconitic acid, and sodium lignosulfonate is 2:4:6:1.

[0055] Example 2

[0056] A preparation method of a green scale inhibitor with a high BaSO4 scale inhibition rate, comprising the following steps:

[0057] S1. Preparation of poly(succinimide) / 2-hydroxyethyl methacrylate (PSI-HEMA) polymer

[0058] Put poly(succinimide) and deionized water into a three-necked flask equipped with a thermometer, a reflux condenser, and a magnetic stir bar to obtain a poly(succinimide) suspension, where the mass-volume ratio of poly(succinimide) to deionized water is 1:10; start stirring and heat up to 55 - 60 °C. During this process, add 2-hydroxyethyl methacrylate, where the mass-volume ratio of 2-hydroxyethyl methacrylate to deionized water is 1:5, and continuously add a 10% sodium hydroxide solution dropwise during this process to adjust the pH of the reaction system to 9 - 10 and react for 3 - 4 h; after the reaction is completed, add methanol for purification to obtain the product A (PSI-HEMA) polymer.

[0059] S2. Preparation of (PSI-HEMA-ANA-SL) copolymer scale inhibitor

[0060] Weigh the following components by percentage: in step S1, obtain (PSI-HEMA) polymer, aconitic acid 5%, sodium lignosulfonate 10%, initiator ammonium persulfate 3%. The sum of the mass percentages of each component is 100%.

[0061] Take the obtained product A (PSI-HEMA) and put it into a three-necked flask, add sodium lignosulfonate and deionized water, and heat up to 85 - 90 °C; during this process, continuously dropwise add aconitic acid solution and ammonium persulfate solution of the initiator (0.5 - 1 h), and the reaction lasts for 3 - 4 h; after the reaction is completed, take an appropriate amount and dialyze it with methanol, and finally dry it in an oven for 24 h to obtain a pale yellow polymer, which is the (PSI-HEMA-ANA-SL) copolymer scale inhibitor of the present invention. Among them, the mass ratio of polysuccinimide, 2-hydroxyethyl methacrylate, aconitic acid and sodium lignosulfonate is 2:4:1:2.

[0062] Example 3

[0063] A preparation method of a green scale inhibitor with high BaSO4 scale inhibition rate, comprising the following steps:

[0064] S1. Preparation of polysuccinimide / 2-hydroxyethyl methacrylate (PSI-HEMA) polymer

[0065] Put polysuccinimide and deionized water into a three-necked flask equipped with a thermometer, a condenser reflux device and a magnetic stirrer to obtain a polysuccinimide suspension, where the mass-volume ratio of polysuccinimide to deionized water is 1:10; start stirring and heat up to 55 - 60 °C. During this process, add 2-hydroxyethyl methacrylate, where the mass-volume ratio of 2-hydroxyethyl methacrylate to deionized water is 1:5, and continuously dropwise add a 10% sodium hydroxide solution to adjust the pH of the reaction system to 9 - 10 and react for 3 - 4 h; after the reaction is completed, add methanol for purification to obtain product A (PSI-HEMA) polymer.

[0066] S2. Preparation of (PSI-HEMA-ANA-SL) copolymer scale inhibitor

[0067] Weigh the following components by percentage: in step S1, obtain (PSI-HEMA) polymer, aconitic acid 5%, sodium lignosulfonate 10%, sodium bisulfite 1%, initiator ammonium persulfate 3%. The sum of the mass percentages of each component is 100%.

[0068] The obtained product A (PSI-HEMA) was placed in a three-necked flask, and sodium lignosulfonate, sodium bisulfite, and deionized water were added, and the temperature was raised to 85-90 °C; during this process, the aconitic acid solution and the initiator ammonium persulfate solution were continuously added dropwise (0.5-1 h), and the reaction continued for 3-4 h; after the reaction was completed, an appropriate amount was taken and dialyzed with methanol, and finally dried in an oven for 24 h to obtain a light yellow polymer, which is the copolymer scale inhibitor (PSI-HEMA-ANA-SL) of the present invention. Among them, the mass ratio of polysuccinimide, 2-hydroxyethyl methacrylate, aconitic acid, and sodium lignosulfonate is 2:4:1:2.

[0069] Control group 1

[0070] Preparation of (HEMA-ANA-SL) copolymer scale inhibitor

[0071] Weigh the following components according to percentages: 10% of 2-hydroxyethyl methacrylate, 5% of aconitic acid, 10% of sodium lignosulfonate, and 3% of the initiator ammonium persulfate. The sum of the mass percentages of each component is 100%.

[0072] Weigh 2-hydroxyethyl methacrylate, sodium lignosulfonate, and deionized water, and raise the temperature to 85-90 °C; during this process, the aconitic acid solution and the initiator ammonium persulfate solution are continuously added dropwise (0.5-1 h), and the reaction continues for 3-4 h; after the reaction is completed, an appropriate amount is taken and dialyzed with methanol, and finally dried in an oven for 24 h to obtain the (HEMA-ANA-SL) copolymer. Among them, the mass ratio of 2-hydroxyethyl methacrylate, aconitic acid, and sodium lignosulfonate is 4:1:2.

[0073] Control group 2

[0074] Mix polysuccinimide and 2-hydroxyethyl methacrylate, add an alkali solution to control the pH = 9-10, and carry out an esterification reaction under heating conditions. The mass ratio of polysuccinimide to 2-hydroxyethyl methacrylate is 1:2 to obtain product A.

[0075] Figure 1 This is the infrared spectrum of the PSI-HEMA copolymer prepared in the present invention. As can be seen from the curve in Figure 1 The absorption peak at 3417.5 cm -1 is the absorption peak of the stretching vibration of the amide N-H bond and the combined absorption peak of the stretching vibration of the carboxyl O-H bond. The absorption peak at 2970 cm -1 is the absorption peak of the stretching vibration of the methyl C-H bond, and the absorption peak at 2932.8 cm -1 is the absorption peak of the stretching vibration of the methylene C-H bond. Both polysuccinimide and 2-hydroxyethyl methacrylate contain saturated carbon atoms. The absorption peak at 1624.1 cm -1 This absorption peak is the stretching vibration peak of C=C, and the absorption peak at 1557 cm -1It is the combined absorption peak of the bending vibration of the N-H bond and the stretching vibration of the C-N in the amide group. Since polysuccinimide contains an amide structure, 1418.2 cm -1 It is the bending vibration absorption peak of methylene, further proving the presence of a saturated alkyl structure in the product. 1243.3 cm -1 This absorption peak is the stretching vibration peak of C-O-C, corresponding to the vibration of the ester bond, indicating that an ester bond may be formed in the esterification reaction. It proves the successful preparation of the PSI-HEMA polymer, and the polymer molecule contains functional groups such as carboxyl, amide, ester, and double bond, indicating scale inhibition activity.

[0076] Figure 2 It is the infrared spectrum of the prepared PSI-HEMA-ANAN-SL copolymer. 3388.9 cm -1 The absorption peak near this wavenumber usually belongs to the stretching vibration of O-H. 3074.2 cm -1 and 2946.5 cm -1 The absorption peaks near these two wavenumbers correspond to the stretching vibration of C-H. 3074.2 cm -1 The absorption peak near is related to the unsaturated C-H (C-H on the double bond), while the absorption peak near 2946.5 cm -1 corresponds to the stretching vibration of saturated C-H (such as C-H on the alkyl group). 1713 cm -1 The absorption peak at this wavenumber belongs to the stretching vibration of C=O, which may be the vibration absorption of the carbonyl group in polysuccinimide, the ester group (formed by the esterification reaction of polysuccinimide and 2-hydroxyethyl methacrylate), or the carbonyl group in aconitic acid, etc. 1658.3 cm -1 This wavenumber is related to the stretching vibration of C=C, which comes from the carbon-carbon double bond in aconitic acid, or the stretching vibration absorption peak of the C=C in the aromatic ring. Lignin has an aromatic ring structure. 1398.3 cm -1 The absorption peak near this wavenumber is related to the bending vibration of C-H, especially the symmetric bending vibration of the methyl group (-CH3). 1122.4 cm -1 This wavenumber corresponds to the stretching vibration absorption peak of S=O, which is the vibration absorption of the ether bond and others in the structure of sodium lignosulfonate. 614 cm -1 It is the stretching absorption vibration peak of C-S. All these indicate the polymerization and grafting of the PSI-HEMA-ANA-SL copolymer scale inhibitor.

[0077] Performance test:

[0078] In Examples 1 to 3 and Control Groups 1-2, the method for determining the barium sulfate scale inhibition rate is as follows:

[0079] Accurately weigh 0.50 g of the scale inhibitor, dissolve it with a small amount of deionized water, and transfer it to a 250 mL volumetric flask and dilute it to the mark to obtain a scale inhibitor solution.

[0080] Barium sulfate: Take 200 mL of deionized water in a 250 mL volumetric flask, add the pre-prepared BaCl2 solution to make the Ba 2+ content 2.8 mg·mL -1 . For three groups of experiments, accurately add 1.25 mL, 2.50 mL, and 3.75 mL of the scale inhibitor solution respectively, let it stand for 10 min, and then add the pre-prepared Na2SO4 solution while shaking to make the SO4 2- content 2.06 mg·mL -1 . Dilute to the mark with deionized water, transfer it to a ground glass conical flask, place it in a water bath at 50°C ± 1°C for half an hour, and then let it stand for 24 h.

[0081] After the reaction is completed, cool the solution to room temperature and filter it with quantitative filter paper. Titrate the filtrate of BaSO4 with an ethylenediaminetetraacetic acid (EDTA) standard solution to determine the concentration of Ba 2+ . The scale inhibition performance is shown in Table 1.

[0082] As can be seen from Table 1, the scale inhibitors prepared in Examples 1-3 have different scale inhibition efficiencies due to different monomer ratios and preparation conditions.

[0083] Table 1 Static test of barium sulfate

[0084]

[0085]

[0086] As can be seen from Table 1, the scale inhibitor provided by the present invention has good inhibition performance on barium sulfate, and a scale inhibition efficiency of 90% can be achieved with a scale inhibitor of 30 mg / L.

[0087] Application test 1

[0088] Take the injection water of an oil well in Jianghan Oilfield and store it in five 100 ml test tubes respectively. Put the scale inhibitors of Examples 1-3 and Control Groups 1-2 into test tubes 1-5 respectively, and the dosing concentration is 30 mg / L. The results are shown in Table 2.

[0089] Table 2 Application data of Examples 1-3 and Control Groups 1-2

[0090] Project Appearance Anti-swelling rate % Actual scale inhibition rate % Test tube 1 No obvious stratification after mixing 29.4 81.2 Test tube 2 No obvious stratification after mixing 32.1 90.0 Test tube 3 No obvious stratification after mixing 30.8 85.4 Test tube 4 Poor miscibility, turbid 21.7 33.5 Test tube 5 Poor miscibility, turbid 17.2 14.9

[0091] Application test 2

[0092] The barium sulfate scale inhibitor prepared in Example 2 was applied in an oil well in Jianghan Oilfield, and the concentration of the scale inhibitor was 30 mg / L. In February 2024, a fixed online water injection boosting device was installed at the well site to increase the pressure. As the pressure rose, the water injection met the injection requirement. From April to May 2024, the pressure continued to rise. Since June 2024, the barium strontium scale inhibitor with the above concentration has been continuously added for 3 months until September 2024. The oil pressure dropped by 1.3 MPa. After stopping the addition of the scale inhibitor, the oil pressure recovered to the level before the addition of the scale inhibitor in December 2024. After adding the scale inhibitor again in January 2025, the pressure has remained stable until now, as shown in Table 3.

[0093] Table 3 Pressure data of an oil well in Jianghan Oilfield from 2024 to 2025 for nearly one year

[0094] Time period Pressure change relative to the initial value (MPa) 2024.2 -- 2024.4 +0.45 2024.5 +0.65 2024.6 -0.2 2024.9 -1.5 2024.12 0 2025.1 - present -1.35

[0095] In summary, the scale inhibitor provided by the present invention integrates the biodegradability of PSI, the strong chelating ability of aconitic acid, and the dispersibility of SL through monomer design and grafting process optimization, forming a multi-functional synergistic system, thereby significantly improving the scale inhibition performance and achieving a high scale inhibition rate of 90%, far exceeding the effect of single sodium lignosulfonate. This result is in line with the development trend of modern water treatment agents towards "multiple grafting, green and efficient".

[0096] It should be noted that the above embodiments all belong to the same inventive concept. The descriptions of the embodiments have their own focuses. For the parts not described in detail in individual embodiments, reference can be made to the descriptions in other embodiments.

[0097] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present application, and all should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claimed rights.

Claims

1. A green scale inhibitor for barium sulfate, characterized in that, The scale inhibitor is a copolymer formed by the esterification reaction of poly(succinimide) and 2-hydroxyethyl methacrylate under alkaline conditions, and the graft copolymerization of aconitic acid and sodium lignosulfonate. Among them, the mass ratio of poly(succinimide) / 2-hydroxyethyl methacrylate / aconitic acid / sodium lignosulfonate is 2:4:(1-6):(1-4).

2. The green scale inhibitor for barium sulfate according to claim 1, characterized in that, In the product formed by the esterification reaction of poly(succinimide) and 2-hydroxyethyl methacrylate under alkaline conditions, the molar ratio of poly(succinimide) to 2-hydroxyethyl methacrylate is 1:

2.

3. A green scale inhibitor for barium sulfate according to claim 1 or 2, characterized in that, The molar ratio of the product formed by the esterification reaction of poly(succinimide) and 2-hydroxyethyl methacrylate under alkaline conditions, aconitic acid and sodium lignosulfonate is 6:2:(1-3).

4. A preparation method of the scale inhibitor according to any one of claims 1-3, characterized in that, It includes the following steps: S1. Mix poly(succinimide) and 2-hydroxyethyl methacrylate, add an alkali solution to control the pH = 9-10, and carry out an esterification reaction under heating conditions to obtain product A; S2. Carry out a graft polymerization reaction on product A, an aconitic acid solution, a sodium lignosulfonate solution, and an initiator solution under heating conditions to obtain the product.

5. The preparation method according to claim 4, characterized in that, In step S1, the alkali solution is one of sodium hydroxide solution and potassium hydroxide solution, the heating temperature is 55-60 °C, and the reaction time of the esterification reaction is 3-4 h.

6. The preparation method according to claim 4, characterized in that, In step S2, before the graft polymerization reaction, product A is heated to 85-90 °C, and the graft polymerization reaction conditions are to react at 90 °C for 3-4 h.

7. The preparation method according to claim 4, characterized in that, The initiator solution is an ammonium persulfate solution.

8. The preparation method according to claim 4, characterized in that, It also includes step S3: Precipitate the solid from the product solution obtained in step S2 with methanol, filter, wash, and vacuum dry the solid.

9. The application of a scale inhibitor as described in any one of claims 1-3 in water body scale inhibition.

10. The application according to claim 9, wherein The water body is the water body in the process of oilfield development, and the concentration of the scale inhibitor in the water body is 10-30 mg / L.

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