Scale inhibitor and preparation method thereof

Abstract

The invention discloses a scale inhibitor, the main component of the scale inhibitor is a benzimidazolyl polycarboxylic acid sulfonic acid chelating agent, the structure contains a plurality of electron-donating groups such as carboxyl groups and sulfonic acid groups, the scale inhibitor can realize stable chelating with metal ions to form a multidentate chelate, and the scale inhibitor has good high temperature resistance. The synergist is added, the synergist and the benzimidazolyl benzimidazolyl polycarboxylic acid sulfonic acid chelating agent have an obvious synergistic effect, the pH of the synergist is stabilized in a neutral state through the pH buffering agent, and low corrosion to a metal pipeline is achieved. Therefore, the scale inhibitor disclosed by the invention is a phosphorus-free green environment-friendly scale inhibitor, has good temperature resistance, excellent scale inhibition rate and wide application range, can be applied to effective chelating with Ca < 2 + > and Ba < 2 + > under the condition of high temperature (60-300 DEG C) in oil and gas wells, and has high-temperature-resistant and efficient scale inhibition effects.

Description

Technical Field

[0001] The present invention relates to the technical field of high-temperature scale inhibitors for oil and gas wells, and particularly relates to a scale inhibitor and a preparation method thereof. Background Art

[0002] With the continuous acceleration of the oil and gas exploitation process in China, the exploitation depth is increasing continuously, and the problem of deep-layer scaling in oil and gas pipelines is becoming more and more serious. The water quality in deep oil and gas fields has the characteristics of high temperature, high hardness, high salinity, etc., which are extremely likely to cause the generation of inorganic scale and affect the normal production of oil and gas fields.

[0003] Oil and gas fields often inject chemical scale inhibitors to inhibit the formation of inorganic scale. At present, there are many types of scale inhibitors, and they are still in the process of continuous research and development. The common types of chemical scale inhibitors mainly include phosphorus-containing polymer scale inhibitors. Phosphorus-containing scale inhibitors will cause certain stress corrosion damage to metal pipelines in high-temperature well conditions, bringing secondary damage to the wellbore. In addition, due to the relatively high temperature in deep wells, the existing scale inhibitors have insufficient stability in high-temperature environments and cannot meet the scale inhibition requirements of high-temperature oil and gas wells. Summary of the Invention

[0004] The purpose of the present invention is to provide a scale inhibitor and a preparation method thereof, which have the characteristics of high temperature resistance, strong chelating effect, excellent scale inhibition performance, phosphorus-free, low corrosion, good water solubility, etc., and can meet the scale inhibition requirements of oil and gas fields under a wide range of conditions.

[0005] To achieve the above purpose, the present invention provides a scale inhibitor. The chemical components of the scale inhibitor include, by weight: 20-25 parts of benzimidazole-based polycarboxylic acid sulfonic acid chelating agent, 8-13 parts of synergist, 2-4 parts of polyethylene glycol, 3-5 parts of pH buffer, and the rest is water.

[0006] The present invention also provides a preparation method of a scale inhibitor. The method includes: putting the benzimidazole-based polycarboxylic acid sulfonic acid chelating agent and water into a reaction kettle, heating and stirring to obtain a first solution; adding the synergist and polyethylene glycol to the first solution and continuing to stir to obtain a second solution; adding the pH buffer to the second solution until the solution is in a neutral state to obtain the scale inhibitor.

[0007] The present invention also provides an application of a scale inhibitor, and the application of the scale inhibitor in oil and gas pipelines.

[0008] The technical effects and advantages of the present invention:

[0009] The main component of the scale inhibitor of the present invention is a benzimidazole-based polycarboxylic acid sulfonic acid chelating agent, which contains multiple electron-donating groups such as carboxyl groups and sulfonic acid groups in its structure, can achieve stable chelation with metal ions, form multidentate chelates, and has good high-temperature resistance. The addition of the synergist has an obvious synergistic effect with the benzimidazole-based polycarboxylic acid sulfonic acid chelating agent. By using a pH buffer to stabilize the pH of the synergist at a neutral state, low corrosion of metal pipelines can be achieved. Therefore, the scale inhibitor of the present invention is a phosphorus-free green environmental protection type scale inhibitor, which has good temperature resistance, excellent scale inhibition rate, a wide range of applications, and can be applied to the effective chelation of Ca 2+ , Ba 2+ under high-temperature (60 - 300 °C) conditions in oil and gas wells, playing the role of high-temperature resistance and high-efficiency scale inhibition.

[0010] Other features and advantages of the present invention will be described in the subsequent specification, and, in part, will become apparent from the specification or will be understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the structures pointed out in the specification and the drawings. Description of the Drawings

[0011] Figure 1 It is a flow chart of the preparation method of the scale inhibitor. Detailed Embodiments

[0012] Next, in combination with the drawings provided by the present invention, the technical solutions of the present invention will be clearly and completely described. Moreover, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0013] It should be noted that the structures, ratios, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those familiar with this technology to understand and read, and are not used to limit the limited conditions under which the present invention can be implemented. Therefore, they do not have technical substantive significance. Any modification of the structure, change of the proportional relationship, or adjustment of the size, without affecting the efficacy that the present invention can produce and the objectives that can be achieved, should still fall within the scope that the technical content disclosed by the present invention can cover. At the same time, the terms such as "upper", "lower", "left", "right", "middle", and "one" cited in this specification are only for the convenience of clear narration and are not used to limit the scope under which the present invention can be implemented. The change or adjustment of their relative relationships, without substantial change in the technical content, should also be regarded as the scope under which the present invention can be implemented.

[0014] The present invention discloses a scale inhibitor. The chemical components of the scale inhibitor include, by weight: 20-25 parts of benzimidazolyl polycarboxylic acid sulfonic acid chelating agent, 8-13 parts of synergist, 2-4 parts of polyethylene glycol, 3-5 parts of pH buffer, and the balance is water.

[0015] The present invention discloses a preparation method of a scale inhibitor, as Figure 1 shown, the method includes:

[0016] 1. Put the benzimidazolyl polycarboxylic acid sulfonic acid chelating agent and water into a reaction kettle, heat and stir to obtain a first solution.

[0017] Specifically, take a certain amount of benzimidazolyl polycarboxylic acid sulfonic acid chelating agent in a reaction kettle, add an appropriate amount of water, heat up to 45°C - 50°C, start stirring, and obtain a first solution.

[0018] Specifically, the preparation method of the benzimidazolyl polycarboxylic acid sulfonic acid chelating agent includes:

[0019] S1. React 2-aminobenzimidazole with ethyl chloroacetate and ethanol to obtain intermediate 1. The specific operation is as follows: Weigh an appropriate amount of 2-aminobenzimidazole into a three-necked flask, add 50 mL of water, heat to 100°C, add an appropriate amount of ethyl chloroacetate, and reflux at 100°C for 3 h. After the reaction is completed, add an appropriate amount of absolute ethanol, reflux at 83°C for 1 h, cool to room temperature, filter and dry to obtain intermediate 1.

[0020] S2. React intermediate 1 with fuming sulfuric acid to obtain the benzimidazolyl polycarboxylic acid sulfonic acid chelating agent. The specific operation is as follows: Weigh an appropriate amount of intermediate 1 into a three-necked flask, add 50 mL of water, stir to dissolve it, slowly add an appropriate amount of fuming sulfuric acid (with a mass concentration of sulfur trioxide of 20% - 30%), control the reaction temperature not to exceed 70°C, after the addition is completed, react and age for 30 min, and stop the reaction. Transfer it to a separating funnel, let it stand and separate layers at 50°C for 1 h, release the lower layer, cool to room temperature, filter and dry to obtain the benzimidazolyl polycarboxylic acid sulfonic acid chelating agent.

[0021] The reaction formula of the preparation method of the benzimidazolyl polycarboxylic acid sulfonic acid chelating agent is:

[0022]

[0023] 2. Add the synergist and polyethylene glycol to the first solution and continue stirring to obtain a second solution.

[0024] Specifically, slowly add the synergist and polyethylene glycol to the first solution in sequence, and continue stirring for 20 - 30 min to obtain a second solution.

[0025] Among them, the synergist is at least one of polyepoxysuccinic acid, polyaspartic acid, polymaleic anhydride, polyacrylic acid, and acrylic acid-acrylate-sulfonate terpolymer. Preferably, it includes 30 to 50 parts by weight of polyepoxysuccinic acid and 50 to 70 parts by weight of polyaspartic acid.

[0026] Among them, any one of the polyethylene glycols with a molecular weight between 200 and 1500 can be selected, specifically including one of PEG-200, PEG-400, or PEG-600.

[0027] 3. Add a pH buffer to the second solution until the solution is in a neutral state to obtain the scale inhibitor.

[0028] Specifically, slowly drop the pH buffer into the second solution, measure the pH of the system multiple times, stop dropping the pH buffer when the pH value of the system reaches 7 to 8, continue stirring for 20 min, stop, and cool down to obtain the high-temperature resistant scale inhibitor.

[0029] Among them, the pH buffer is an ammonium chloride-ammonia water mixed solution, sodium acetate, ammonia water, sodium hydroxide, or potassium hydroxide. Preferably, it is an ammonium chloride-ammonia water mixed solution.

[0030] To better explain the present invention, the following examples are also provided.

[0031] Example 1

[0032] The specific preparation process of the high-temperature resistant scale inhibitor is operated according to the following steps:

[0033] Preparation of the chelating main agent: Weigh 0.2 mol of 2-aminobenzimidazole into a three-necked flask, add 50 mL of water, heat to 100 °C, add 0.6 mol of ethyl chloroacetate, and heat under reflux at 100 °C for 3 h. After the reaction is completed, add 0.6 mol of absolute ethanol, heat under reflux at 83 °C for 1 h, cool to room temperature, filter, and dry to obtain Intermediate 1. Weigh 0.2 mol of Intermediate 1 into a three-necked flask, add 50 mL of water, stir to dissolve it, slowly drop 0.65 mol of fuming sulfuric acid (with a sulfur trioxide mass concentration of 20% to 30%), control the reaction temperature not to exceed 70 °C, and age for 30 min after dropping. Stop the reaction. Transfer it to a separatory funnel, let it stand and separate layers at 50 °C for 1 h, release the lower layer, cool to room temperature, filter, and dry to obtain the benzimidazolyl polycarboxylic acid sulfonic acid chelating agent.

[0034] Preparation of high-temperature scale inhibitor: The high-temperature scale inhibitor includes 23 parts of benzimidazole-based polycarboxylic acid sulfonic acid chelating agent; 10 parts of synergist; 3 parts of polyethylene glycol; 4 parts of pH buffer; and the rest is water. The synergist includes 40 parts of polyepoxysuccinic acid and 60 parts of polyaspartic acid by weight. The specific steps are as follows: Take 23 parts of the chelating main agent in a reaction kettle, add an appropriate amount of water, heat up to 45°C - 50°C, start stirring, and slowly add 10 parts of the synergist and 3 parts of polyethylene glycol in sequence. After continuing to stir for 20 - 30 min, slowly dropwise add 4 parts of the pH buffer. Measure the pH of the system multiple times. When the pH value of the system reaches 7 - 8, stop dropping the pH buffer, continue stirring for 20 min, stop, cool down, and obtain the high-temperature scale inhibitor.

[0035] Example 2

[0036] The specific preparation process of the high-temperature scale inhibitor is operated according to the following steps:

[0037] Preparation of chelating main agent: Weigh 0.2 mol of 2-aminobenzimidazole in a three-necked flask, add 50 mL of water, heat to 100°C, add 0.7 mol of ethyl chloroacetate, and reflux at 100°C for 3 h. After the reaction is completed, add 0.7 mol of absolute ethanol, reflux at 83°C for 1 h, cool to room temperature, filter, and dry to obtain Intermediate 1. Weigh 0.2 mol of Intermediate 1 into a three-necked flask, add 50 mL of water, stir to dissolve it, slowly dropwise add 0.65 mol of fuming sulfuric acid (with a mass concentration of sulfur trioxide of 20% - 30%), control the reaction temperature not to exceed 70°C, age for 30 min after the dropping is completed, and stop the reaction. Transfer it to a separating funnel, let it stand and separate for 1 h at 50°C, drain the lower layer, cool to room temperature, filter, and dry to obtain the benzimidazole-based polycarboxylic acid sulfonic acid chelating agent.

[0038] The preparation of the high-temperature scale inhibitor is the same as that in Example 1.

[0039] Example 3

[0040] The specific preparation process of the high-temperature scale inhibitor is operated according to the following steps:

[0041] Preparation of chelating main agent: Weigh 0.2 mol of 2-aminobenzimidazole into a three-necked flask, add 50 mL of water, heat to 100 °C, add 0.8 mol of ethyl chloroacetate, and reflux at 100 °C for 3 h. After the reaction is completed, add 0.8 mol of absolute ethanol, reflux at 83 °C for 1 h, cool to room temperature, filter and dry to obtain intermediate 1. Weigh 0.2 mol of intermediate 1 into a three-necked flask, add 50 mL of water, stir to dissolve it, slowly add 0.65 mol of fuming sulfuric acid (mass concentration of sulfur trioxide is 20% - 30%), control the reaction temperature not exceeding 70 °C, age for 30 min after the addition is completed, and stop the reaction. Transfer it to a separatory funnel, let it stand and separate layers at 50 °C for 1 h, drain the lower layer, cool to room temperature, filter and dry to obtain the benzimidazole-based polycarboxylic acid sulfonic acid chelating agent.

[0042] The preparation of the high-temperature scale inhibitor is the same as that in Example 1.

[0043] Example 4

[0044] The specific preparation process of the high-temperature scale inhibitor is operated according to the following steps:

[0045] Preparation of chelating main agent: Weigh 0.2 mol of 2-aminobenzimidazole into a three-necked flask, add 50 mL of water, heat to 100 °C, add 0.7 mol of ethyl chloroacetate, and reflux at 100 °C for 3 h. After the reaction is completed, add 0.7 mol of absolute ethanol, reflux at 83 °C for 1 h, cool to room temperature, filter and dry to obtain intermediate 1. Weigh 0.2 mol of intermediate 1 into a three-necked flask, add 50 mL of water, stir to dissolve it, slowly add 0.8 mol of fuming sulfuric acid (mass concentration of sulfur trioxide is 20% - 30%), control the reaction temperature not exceeding 70 °C, age for 30 min after the addition is completed, and stop the reaction. Transfer it to a separatory funnel, let it stand and separate layers at 50 °C for 1 h, drain the lower layer, cool to room temperature, filter and dry to obtain the benzimidazole-based polycarboxylic acid sulfonic acid chelating agent.

[0046] The preparation of the high-temperature scale inhibitor is the same as that in Example 1.

[0047] Example 5

[0048] The specific preparation process of the high-temperature scale inhibitor is operated according to the following steps:

[0049] Preparation of Chelating Agent Main Agent: Weigh 0.2 mol of 2-aminobenzimidazole into a three-necked flask, add 50 mL of water, heat to 100 °C, add 0.7 mol of ethyl chloroacetate, and reflux at 100 °C for 3 h. After the reaction is completed, add 0.7 mol of absolute ethanol, reflux at 83 °C for 1 h, cool to room temperature, filter and dry to obtain Intermediate 1. Weigh 0.2 mol of Intermediate 1 into a three-necked flask, add 50 mL of water, stir to dissolve it, slowly add 1 mol of fuming sulfuric acid (sulfur trioxide mass concentration is 20% - 30%), control the reaction temperature not to exceed 70 °C, after the addition is completed, age the reaction for 30 min, and stop the reaction. Transfer it to a separatory funnel, let it stand and separate layers at 50 °C for 1 h, release the lower layer, cool to room temperature, filter and dry to obtain the benzimidazole-based polycarboxylic acid sulfonic acid chelating agent.

[0050] The preparation of the high-temperature scale inhibitor is the same as that in Example 1.

[0051] Example 6

[0052] The specific preparation process of the high-temperature scale inhibitor is operated according to the following steps:

[0053] The preparation of the chelating agent main agent is the same as that in Example 4.

[0054] Preparation of High-Temperature Scale Inhibitor: The high-temperature scale inhibitor includes 20 parts of benzimidazole-based polycarboxylic acid sulfonic acid chelating agent; 10 parts of synergist; 3 parts of polyethylene glycol; 3 parts of pH buffer; the rest is water. The synergist includes 40 parts of polyepoxysuccinic acid and 60 parts of polyaspartic acid by weight. The specific steps are as follows: Take 20 parts of the chelating agent main agent in a reaction kettle, add an appropriate amount of water, heat up to 45 °C - 50 °C, start stirring, slowly add 10 parts of synergist and 3 parts of polyethylene glycol in sequence, continue stirring for 20 - 30 min, then slowly add 3 parts of pH buffer, measure the pH of the system multiple times, stop adding the pH buffer when the pH value of the system reaches 7 - 8, continue stirring for 20 min, stop, and cool down to obtain the high-temperature scale inhibitor.

[0055] Example 7

[0056] The difference from Example 6 is that in this example, the high-temperature scale inhibitor includes 25 parts of benzimidazole-based polycarboxylic acid sulfonic acid chelating agent; 10 parts of synergist; 3 parts of polyethylene glycol; 5 parts of pH buffer; the rest is water. The synergist includes 40 parts of polyepoxysuccinic acid and 60 parts of polyaspartic acid by weight.

[0057] Example 8

[0058] The difference from Example 6 is that in this example, the high-temperature scale inhibitor comprises 23 parts of benzimidazole-based polycarboxylic acid sulfonic acid chelating agent; 8 parts of synergist; 3 parts of polyethylene glycol; 3 parts of pH buffer; and the balance is water. The synergist comprises 40 parts of polyepoxysuccinic acid and 60 parts of polyaspartic acid by weight.

[0059] Example 9

[0060] The difference from Example 6 is that in this example, the high-temperature scale inhibitor comprises 23 parts of benzimidazole-based polycarboxylic acid sulfonic acid chelating agent; 13 parts of synergist; 3 parts of polyethylene glycol; 5 parts of pH buffer; and the balance is water. The synergist comprises 40 parts of polyepoxysuccinic acid and 60 parts of polyaspartic acid by weight.

[0061] Example 10

[0062] The difference from Example 9 is that in this example, the high-temperature scale inhibitor comprises 23 parts of benzimidazole-based polycarboxylic acid sulfonic acid chelating agent; 10 parts of synergist; 3 parts of polyethylene glycol; 5 parts of pH buffer; and the balance is water. The synergist comprises 30 parts of polyepoxysuccinic acid and 70 parts of polyaspartic acid by weight.

[0063] Example 11

[0064] The difference from Example 9 is that in this example, the high-temperature scale inhibitor comprises 23 parts of benzimidazole-based polycarboxylic acid sulfonic acid chelating agent; 10 parts of synergist; 3 parts of polyethylene glycol; 4 parts of pH buffer; and the balance is water. The synergist comprises 50 parts of polyepoxysuccinic acid and 50 parts of polyaspartic acid by weight.

[0065] Example 12

[0066] The difference from Example 9 is that in this example, the high-temperature scale inhibitor comprises 23 parts of benzimidazole-based polycarboxylic acid sulfonic acid chelating agent; 10 parts of synergist; 3 parts of polyethylene glycol; 4 parts of pH buffer; and the balance is water. The synergist is polyepoxysuccinic acid.

[0067] Example 13

[0068] The difference from Example 9 is that in this example, the high-temperature scale inhibitor comprises 23 parts of benzimidazole-based polycarboxylic acid sulfonic acid chelating agent; 10 parts of synergist; 3 parts of polyethylene glycol; 4 parts of pH buffer; and the balance is water. The synergist is polyaspartic acid.

[0069] Example 14

[0070] The difference from Example 9 is that in this example, the high-temperature scale inhibitor comprises 23 parts of benzimidazole-based polycarboxylic acid sulfonic acid chelating agent; 10 parts of synergist; 3 parts of polyethylene glycol; 4 parts of pH buffer; and the balance is water. The synergist is maleic anhydride.

[0071] Example 15

[0072] The difference from Example 6 is that in this example, the high-temperature scale inhibitor comprises 23 parts of benzimidazole-based polycarboxylic acid sulfonic acid chelating agent; 10 parts of synergist; 2 parts of polyethylene glycol; 3 parts of pH buffer; and the balance is water. The synergist comprises 40 parts of polyepoxysuccinic acid and 60 parts of polyaspartic acid by weight.

[0073] Example 16

[0074] The difference from Example 6 is that in this example, the high-temperature scale inhibitor comprises 23 parts of benzimidazole-based polycarboxylic acid sulfonic acid chelating agent; 10 parts of synergist; 4 parts of polyethylene glycol; 3 parts of pH buffer; and the balance is water. The synergist comprises 40 parts of polyepoxysuccinic acid and 60 parts of polyaspartic acid by weight.

[0075] The high-temperature scale inhibitors prepared in Examples 1-14 of the present invention were subjected to a static scale inhibition experiment according to the method in the standard Q / SY 126-2014 "Technical Specification for Corrosion and Scale Inhibitors for Oilfield Water Treatment" of China National Petroleum Corporation. The experimental evaluation temperatures were 60 °C and 180 °C. Compared with the commercially available product (DTPMPA, Shandong Kerry Chemical Co., Ltd.), the scale inhibition effect was obvious and the stability was strong, superior to general commercially available agents. The experimental results are shown in Table 1.

[0076] Table 1 Results of scale inhibition rate determination

[0077]

[0078]

[0079] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A scale inhibitor, characterized in that: The chemical components of the scale inhibitor include, by weight: 20 to 25 parts of benzimidazole polycarboxylic acid sulfonic acid chelating agent, 8 to 13 parts of synergist, 2 to 4 parts of polyethylene glycol, 3 to 5 parts of pH buffer solution, and the rest is water.

2. A method for preparing a scale inhibitor, characterized in that: The method comprises: Putting a benzimidazole polycarboxylic acid sulfonic acid chelating agent and water into a reaction kettle, heating and stirring, to obtain a first solution; adding a synergist and polyethylene glycol to the first solution and continuing stirring to obtain a second solution; A pH buffer solution is added to the second solution until the solution is in a neutral state to obtain a scale inhibitor.

3. The method according to claim 2, characterized in that The synergist comprises at least one of the following: polyepoxysuccinic acid, polyaspartic acid, polymaleic anhydride, polyacrylic acid, and acrylic acid-acrylate-sulfonate terpolymer.

4. The method according to claim 2, characterized in that: The molecular weight of the polyethylene glycol is 200-1500, and the polyethylene glycol includes at least one of the following: PEG-200, PEG-400, and PEG-600.

5. The method according to claim 2, characterized in that: The pH buffer solution includes one of the following: ammonium chloride-ammonia water mixed solution, sodium acetate, ammonia water, sodium hydroxide, and potassium hydroxide.

6. The method according to claim 2, characterized in that The heating temperature is 45°C to 50°C.

7. The method according to claim 2, characterized in that The stirring time is 20 to 30 minutes.

8. The method according to claim 2, characterized in that: The method for obtaining the benzimidazole polycarboxylic acid sulfonic acid chelating agent comprises: Intermediate 1 is obtained by reacting 2-aminobenzimidazole with ethyl chloroacetate and ethanol; The benzimidazole-based polycarboxylic acid sulfonic acid chelating agent is obtained by reacting the intermediate 1 with fuming sulfuric acid.

9. The method according to claim 8, characterized in that By reacting 2-aminobenzimidazole with ethyl chloroacetate and ethanol, intermediate 1 is obtained, including: Under heating conditions, adding ethyl chloroacetate to the aqueous solution of 2-aminobenzimidazole to react to obtain a fourth solution; Anhydrous ethanol was added to the fourth solution to carry out a reaction, thereby obtaining an intermediate 1.

10. The method according to claim 8, characterized in that The benzimidazole polycarboxylic acid sulfonic acid chelating agent is obtained by reacting the intermediate 1 with fuming sulfuric acid, including: Add fuming sulfuric acid to the aqueous solution of intermediate 1, and react under heating conditions to obtain a fifth solution; Performing aging and liquid separation treatment on the fifth solution to obtain an upper layer of liquid; The upper layer liquid is filtered and dried to obtain a benzimidazole polycarboxylic acid sulfonic acid chelating agent.

11. The use of the scale inhibitor obtained according to claim 1, characterized in that: The scale inhibitor is used in oil and gas pipelines.

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