An antifouling agent and a method for preparing the same

Abstract

The application discloses a scale inhibitor, which mainly comprises a benzimidazole-based polycarboxylic acid sulfonic acid chelating agent; the structure contains multiple electron-donating groups such as carboxyl groups and sulfonic acid groups, can realize stable chelation with metal ions, forms a polynuclear chelate, and has good high-temperature resistance. The addition of a synergist has obvious synergistic effect with the benzimidazole-based polycarboxylic acid sulfonic acid chelating agent, the pH of the synergist is stabilized at a neutral state through a pH buffer, and low corrosion to metal pipelines is realized. Therefore, the scale inhibitor is a phosphorus-free green and environment-friendly scale inhibitor, has good temperature resistance, excellent scale inhibition rate, and wide application range, and can be applied to effective chelation of Ca 2+ , Ba 2+ under high-temperature (60-300 DEG C) conditions in oil and gas wells, and plays a role of high-temperature resistance and high-efficiency scale inhibition.

Description

Technical Field

[0001] This invention relates to the field of high-temperature scale inhibitors for oil and gas wells, and particularly to a scale inhibitor and its preparation method. Background Technology

[0002] With the continuous acceleration of oil and gas extraction in my country and the increasing depth of extraction, the problem of deep scaling in oil and gas pipelines is becoming increasingly serious. The water quality in deep oil and gas fields is characterized by high temperature, high hardness, and high salinity, which easily leads to the formation of inorganic scale and affects the normal production of oil and gas fields.

[0003] Oil and gas fields often use chemical scale inhibitors to suppress the formation of inorganic scale. Currently, there are many types of scale inhibitors, and they are still under continuous research and development. Commonly used chemical scale inhibitors mainly include phosphorus-containing polymer scale inhibitors. However, phosphorus-containing scale inhibitors can cause stress corrosion damage to metal pipelines in high-temperature well conditions, leading to secondary damage to the wellbore. Furthermore, due to the high temperatures in deep wells, existing scale inhibitors lack 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 this invention is to provide a scale inhibitor and its preparation method, which has the characteristics of high temperature resistance, strong chelation effect, excellent scale inhibition performance, phosphorus-free, low corrosiveness, and good water solubility, and can meet the scale inhibition needs of oil and gas fields under a wide range of conditions.

[0005] To achieve the above objectives, the present invention provides a scale inhibitor, the chemical composition of which, by weight, comprises: 20-25 parts of benzimidazole polycarboxylic acid sulfonic acid chelating agent, 8-13 parts of synergist, 2-4 parts of polyethylene glycol, 3-5 parts of pH buffer solution, and the remainder being water.

[0006] The present invention also provides a method for preparing a scale inhibitor, the method comprising: placing a benzimidazole polycarboxylic acid sulfonic acid chelating agent and water into a reaction vessel and heating and stirring to obtain a first solution; adding a synergist and polyethylene glycol to the first solution and continuing to stir to obtain a second solution; adding a pH buffer solution to the second solution until the solution is neutral to obtain a scale inhibitor.

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

[0008] The technical effects and advantages of this invention are as follows:

[0009] The main component of the scale inhibitor of this invention is a benzimidazole-based polycarboxylic acid sulfonic acid chelating agent. This structure contains multiple electron-donating groups such as carboxyl and sulfonic acid groups, enabling stable chelation with metal ions to form multidentate chelates, and exhibiting excellent high-temperature resistance. The addition of a synergist has a significant synergistic effect with the benzimidazole-based polycarboxylic acid sulfonic acid chelating agent. A pH buffer stabilizes the pH of the synergist at a neutral state, achieving low corrosion resistance to metal pipelines. Therefore, the scale inhibitor of this invention is a phosphorus-free, green, and environmentally friendly scale inhibitor with good temperature resistance, excellent scale inhibition rate, and a wide range of applications. It can be applied in oil and gas wells under high-temperature (60–300℃) conditions to react with Ca... 2+ Ba 2+ The effective chelation provides high-temperature resistance and efficient scale inhibition.

[0010] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0011] Figure 1 This is a flowchart of the preparation method for scale inhibitors. Detailed Implementation

[0012] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Furthermore, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0013] It should be noted that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding and reading. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0014] This invention discloses a scale inhibitor, the chemical composition of which, by weight, comprises: 20-25 parts of benzimidazole polycarboxylic acid sulfonic acid chelating agent, 8-13 parts of synergist, 2-4 parts of polyethylene glycol, 3-5 parts of pH buffer solution, and the remainder being water.

[0015] This invention discloses a method for preparing a scale inhibitor, such as... Figure 1 As shown, the method includes:

[0016] 1. Place benzimidazole polycarboxylic acid sulfonic acid chelating agent and water into a reaction vessel, heat and stir to obtain the first solution.

[0017] Specifically, a certain amount of benzimidazole polycarboxylic acid sulfonic acid chelating agent is placed in a reaction vessel, an appropriate amount of water is added, the temperature is heated to 45℃~50℃, and stirring is started to obtain the first solution.

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

[0019] S1 2-Aminobenzimidazole reacts with ethyl chloroacetate and ethanol to give intermediate 1. The specific procedure is as follows: An appropriate amount of 2-aminobenzimidazole is weighed into a three-necked flask, 50 mL of water is added, and the mixture is heated to 100°C. An appropriate amount of ethyl chloroacetate is added, and the mixture is refluxed at 100°C for 3 hours. After the reaction is complete, an appropriate amount of anhydrous ethanol is added, and the mixture is refluxed at 83°C for 1 hour. The mixture is then cooled to room temperature, filtered, and dried to obtain intermediate 1.

[0020] S2 intermediate 1 reacts with fuming sulfuric acid to obtain a benzimidazole-based polycarboxylic acid sulfonic acid chelating agent. The specific procedure is as follows: Weigh an appropriate amount of intermediate 1 into a three-necked flask, add 50 mL of water, stir to dissolve, and slowly add an appropriate amount of fuming sulfuric acid (containing 20%–30% sulfur trioxide by mass). Control the reaction temperature to not exceed 70°C. After the addition is complete, age the reaction for 30 minutes and then stop the reaction. Transfer the solution to a separatory funnel, allow it to stand at 50°C for 1 hour to separate the layers, release the lower layer, cool to room temperature, filter, and dry to obtain the benzimidazole-based polycarboxylic acid sulfonic acid chelating agent.

[0021] The reaction formula for the preparation method of benzimidazole polycarboxylic acid sulfonic acid chelating agent is as follows:

[0022]

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

[0024] Specifically, the synergist and polyethylene glycol are slowly added to the first solution in sequence, and the mixture is stirred for 20 to 30 minutes to obtain the second solution.

[0025] The synergist is at least one of polyepoxysuccinic acid, polyaspartic acid, polymaleic anhydride, polyacrylic acid, and acrylate-acrylate-sulfonate terpolymer. Preferably, it comprises 30-50 parts by weight of polyepoxysuccinic acid and 50-70 parts by weight of polyaspartic acid.

[0026] The polyethylene glycol can be any type with a molecular weight between 200 and 1500, specifically including PEG-200, PEG-400 or PEG-600.

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

[0028] Specifically, pH buffer solution is slowly added dropwise to the second solution, and the pH of the system is measured multiple times. When the pH of the system reaches 7-8, the addition of pH buffer solution is stopped, and stirring is continued for 20 minutes. Then, the mixture is stopped, cooled, and the high-temperature scale inhibitor is obtained.

[0029] The pH buffer solution is a mixture of ammonium chloride and ammonia, sodium acetate, ammonia, sodium hydroxide, and potassium hydroxide. Preferably, it is a mixture of ammonium chloride and ammonia.

[0030] To better explain the present invention, embodiments are also provided below.

[0031] Example 1

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

[0033] Preparation of the chelating 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 reflux at 100 °C for 3 h. After the reaction is complete, add 0.6 mol of anhydrous 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, and slowly add 0.65 mol of fuming sulfuric acid (containing 20%–30% sulfur trioxide by mass), controlling the reaction temperature not to exceed 70 °C. After the addition is complete, age the reaction for 30 min and stop the reaction. Transfer to a separatory funnel, let stand at 50 °C for 1 h to separate the layers, release the lower layer, cool to room temperature, filter, and dry to obtain the benzimidazole-based polycarboxylic acid sulfonic acid chelating agent.

[0034] Preparation of high-temperature resistant scale inhibitor: The high-temperature resistant 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 remainder is water. The synergist, by weight, comprises 40 parts of polyepoxysuccinic acid and 60 parts of polyaspartic acid. The specific steps are as follows: Take 23 parts of the chelating agent into a reaction vessel, add an appropriate amount of water, heat to 45℃~50℃, start stirring, and slowly add 10 parts of synergist and 3 parts of polyethylene glycol in sequence. After continuing to stir for 20~30 minutes, slowly add 4 parts of pH buffer. Measure the pH of the system multiple times. When the pH value of the system reaches 7~8, stop adding pH buffer. Continue stirring for 20 minutes, then stop and cool to obtain the high-temperature resistant scale inhibitor.

[0035] Example 2

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

[0037] Preparation of the chelating 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 complete, add 0.7 mol of anhydrous 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, and slowly add 0.65 mol of fuming sulfuric acid (containing 20%–30% sulfur trioxide by mass), controlling the reaction temperature not to exceed 70 °C. After the addition is complete, age the reaction for 30 min and stop the reaction. Transfer to a separatory funnel, let stand at 50 °C for 1 h to separate the layers, release 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 in Example 1.

[0039] Example 3

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

[0041] Preparation of the chelating 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 complete, add 0.8 mol of anhydrous 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, and slowly add 0.65 mol of fuming sulfuric acid (containing 20%–30% sulfur trioxide by mass), controlling the reaction temperature not to exceed 70 °C. After the addition is complete, age the reaction for 30 min and stop the reaction. Transfer to a separatory funnel, let stand at 50 °C for 1 h to separate the layers, release 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 in Example 1.

[0043] Example 4

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

[0045] Preparation of the chelating 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 complete, add 0.7 mol of anhydrous 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, and slowly add 0.8 mol of fuming sulfuric acid (containing 20%–30% sulfur trioxide by mass), controlling the reaction temperature not to exceed 70 °C. After the addition is complete, age the reaction for 30 min and stop the reaction. Transfer to a separatory funnel, let stand at 50 °C for 1 h to separate the layers, release 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 in Example 1.

[0047] Example 5

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

[0049] Preparation of the chelating 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 complete, add 0.7 mol of anhydrous 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, and slowly add 1 mol of fuming sulfuric acid (containing 20%–30% sulfur trioxide by mass), controlling the reaction temperature not to exceed 70 °C. After the addition is complete, age the reaction for 30 min and stop the reaction. Transfer to a separatory funnel, let stand at 50 °C for 1 h to separate the layers, 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 in Example 1.

[0051] Example 6

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

[0053] The preparation of the chelating agent was the same as in Example 4.

[0054] Preparation of high-temperature resistant scale inhibitor: The high-temperature resistant scale inhibitor comprises 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; and the remainder is water. The synergist, by weight, comprises 40 parts of polyepoxysuccinic acid and 60 parts of polyaspartic acid. The specific steps are as follows: Take 20 parts of the chelating agent into a reaction vessel, add an appropriate amount of water, heat to 45℃~50℃, start stirring, and slowly add 10 parts of synergist and 3 parts of polyethylene glycol in sequence. After continuing to stir for 20~30 minutes, slowly add 3 parts of pH buffer. Measure the pH of the system multiple times. When the pH value of the system reaches 7~8, stop adding pH buffer, continue stirring for 20 minutes, stop, and cool down to obtain the high-temperature resistant scale inhibitor.

[0055] Example 7

[0056] The difference from Example 6 is that the high-temperature scale inhibitor in this example 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; and the remainder 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 the high-temperature scale inhibitor in this example includes 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 remainder is water. The synergist includes 40 parts of polyepoxysuccinic acid and 60 parts of polyaspartic acid by weight.

[0059] Example 9

[0060] The difference from Example 6 is that the high-temperature scale inhibitor in this example includes 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 remainder is water. The synergist includes 40 parts of polyepoxysuccinic acid and 60 parts of polyaspartic acid by weight.

[0061] Example 10

[0062] The difference from Example 9 is that the high-temperature scale inhibitor in this example includes 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 remainder is water. The synergist includes 30 parts of polyepoxysuccinic acid and 70 parts of polyaspartic acid by weight.

[0063] Example 11

[0064] The difference from Example 9 is that the high-temperature scale inhibitor in this example 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 remainder is water. The synergist includes 50 parts of polyepoxysuccinic acid and 50 parts of polyaspartic acid by weight.

[0065] Example 12

[0066] The difference from Example 9 is that the high-temperature scale inhibitor in this example 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 remainder is water. The synergist is polyepoxysuccinic acid.

[0067] Example 13

[0068] The difference from Example 9 is that the high-temperature scale inhibitor in this example 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 remainder is water. The synergist is polyaspartic acid.

[0069] Example 14

[0070] The difference from Example 9 is that the high-temperature scale inhibitor in this example 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 remainder is water. The synergist is polymaleic anhydride.

[0071] Example 15

[0072] The difference from Example 6 is that the high-temperature scale inhibitor in this example includes 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 remainder is water. The synergist includes 40 parts of polyepoxysuccinic acid and 60 parts of polyaspartic acid by weight.

[0073] Example 16

[0074] The difference from Example 6 is that the high-temperature scale inhibitor in this example includes 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 remainder is water. The synergist includes 40 parts of polyepoxysuccinic acid and 60 parts of polyaspartic acid by weight.

[0075] The high-temperature scale inhibitors prepared according to this invention were used in Examples 1-14 to conduct static scale inhibition experiments according to the methods in China National Petroleum Corporation standard Q / SY 126-2014 "Technical Specification for Corrosion and Scale Inhibitors for Oilfield Water Treatment". The evaluation temperatures were 60℃ and 180℃. Compared with commercially available products (DTPMPA, Shandong Kairui Chemical Co., Ltd.), the scale inhibition effect was significant, and the stability was stronger, which was superior to general commercially available agents. The experimental results are shown in Table 1.

[0076] Table 1 Results of scale inhibition rate measurement

[0077]

[0078]

[0079] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is 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 make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a scale inhibitor, characterized in that, The method includes: The benzimidazole polycarboxylic acid sulfonic acid chelating agent and water were placed in a reaction vessel and heated and stirred to obtain the first solution; Add the synergist and polyethylene glycol to the first solution and continue stirring to obtain the second solution; Add pH buffer solution to the second solution until the solution is neutral to obtain a scale inhibitor; The synergist includes at least one of the following: polyepoxysuccinic acid, polyaspartic acid, polymaleic anhydride, polyacrylic acid, and acrylic acid-acrylate-sulfonate terpolymer. Obtaining the benzimidazole polycarboxylic acid sulfonic acid chelating agent comprises: Intermediate 1 was obtained by reacting 2-aminobenzimidazole with ethyl chloroacetate and ethanol; The benzimidazole polycarboxylic acid sulfonic acid chelating agent was obtained by reacting intermediate 1 with fuming sulfuric acid.

2. The method according to claim 1, characterized in that, The polyethylene glycol has a molecular weight of 200-1500, and the polyethylene glycol includes at least one of the following: PEG-200, PEG-400, and PEG-600.

3. The method according to claim 1, characterized in that, The pH buffer solution includes one of the following: ammonium chloride-ammonia solution, sodium acetate, ammonia, sodium hydroxide, or potassium hydroxide.

4. The method according to claim 1, characterized in that, The heating temperature is 45℃~50℃.

5. The method according to claim 1, characterized in that, The stirring time is 20-30 minutes.

6. The method according to claim 1, characterized in that, Intermediate 1 is obtained by reacting 2-aminobenzimidazole with ethyl chloroacetate and ethanol, comprising: Under heating conditions, ethyl chloroacetate was added to an aqueous solution of 2-aminobenzimidazole to react and obtain a fourth solution; Anhydrous ethanol was added to the fourth solution to carry out the reaction and obtain intermediate 1.

7. The method according to claim 1, characterized in that, The benzimidazole polycarboxylic acid sulfonic acid chelating agent is obtained by reacting intermediate 1 with fuming sulfuric acid, including: Fuming sulfuric acid was added to the aqueous solution of intermediate 1, and the reaction was carried out under heating conditions to obtain the fifth solution; The fifth solution is aged and separated to obtain the upper liquid. The upper liquid is filtered and dried to obtain a benzimidazole polycarboxylic acid sulfonic acid chelating agent.

8. The method according to claim 1, characterized in that, The scale inhibitor comprises, by weight, 20-25 parts benzimidazole polycarboxylic acid sulfonic acid chelating agent, 8-13 parts synergist, 2-4 parts polyethylene glycol, 3-5 parts pH buffer solution, and the remainder is water.

9. The application 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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