An oilfield corrosion and scale inhibitor and a preparation method thereof

Abstract

The application discloses an oilfield corrosion and scale inhibitor and a preparation method thereof, and relates to the technical field of corrosion and scale inhibitors. In the preparation of the oilfield corrosion and scale inhibitor, modified polyaspartic acid is prepared by reacting poly succinimide with 3,5-diamino salicylic acid and p-aminobenzenesulfonic acid; and the oilfield corrosion and scale inhibitor is prepared by reacting the modified polyaspartic acid, hydroxypropyltrimethylammonium chloride chitosan and 2,5-thiophenedicarboxaldehyde. The oilfield corrosion and scale inhibitor prepared by the application has good corrosion and scale inhibition performance.

Description

Technical Field

[0001] This invention relates to the field of corrosion and scale inhibitors, specifically to an oilfield corrosion and scale inhibitor and its preparation method. Background Technology

[0002] To increase oil production, most oilfields maintain reservoir pressure through water reinjection to facilitate extraction. However, most oilfields are located in remote areas with scarce freshwater resources, and the oil extraction process also generates large amounts of wastewater that are difficult to treat. Therefore, in actual oilfield production, to save costs and simplify the production process, formation water, surrounding seawater, and wastewater from oil extraction are often directly injected into the formation as injection water. Although this technology is widely used due to its convenience, with the continuous development of oilfields, the problems of corrosion and scaling on oil and gas pipelines have become increasingly prominent.

[0003] Corrosion inhibitors are chemical substances that slow down the corrosion rate of metals. Even trace amounts of corrosion inhibitors in the environment can significantly reduce the corrosion rate while maintaining the original physical and mechanical properties of the metal. Scale inhibitors are chemical agents added to oil and gas pipeline systems to inhibit the formation of scale-causing ions or increase the solubility of these ions, thus making deposits less likely to occur in the oil and gas pipeline system.

[0004] Polyaspartic acid (PAA) is a polymeric amino acid with carboxylic acid side chains. Because the peptide bonds in its main chain are easily broken by fungi and microorganisms, its final degradation products are CO2 and H2O, which are harmless to the environment. PAA's main characteristics are that it is pollution-free, non-toxic, phosphorus-free, and biodegradable, making it a recognized "green chemical." As a water treatment agent, it has the ability to inhibit scaling and corrosion caused by CaSO4 and CaCO3. In recent years, the synthesis and application of PAA have attracted close attention from chemical and pharmaceutical companies worldwide and have become a new research hotspot. However, PAA's ability to inhibit Ca3(PO4)2 is not outstanding, limiting its application in actual industrial production. Chitosan is a multifunctional polymer. When used in water treatment, chitosan can act as an adsorbent and scale inhibitor. However, due to its inherent limitations, chitosan is not yet suitable for large-scale industrial use. Therefore, this invention modifies PAA and chitosan to produce an oilfield corrosion and scale inhibitor with good corrosion and scale inhibition properties. Summary of the Invention

[0005] The purpose of this invention is to provide an oilfield corrosion and scale inhibitor and its preparation method, so as to solve the problems existing in the prior art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: An oilfield corrosion and scale inhibitor is prepared by reacting modified polyaspartic acid, hydroxypropyltrimethylammonium chloride chitosan, and 2,5-thiophene dicarboxaldehyde.

[0007] As an optimization, the modified polyaspartic acid is prepared by reacting polysuccinimide with 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid.

[0008] As an optimization, the polysuccinimide has a weight-average molecular weight of 7000-8000 and was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0009] A method for preparing an oilfield corrosion and scale inhibitor includes the following preparation steps: (1) Mix polysuccinimide and deionized water evenly, add a mixed solution of 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid within 30 min, stir and react at room temperature for 20-24 h, adjust the pH to 7-8 with hydrochloric acid aqueous solution, add anhydrous ethanol, filter, dry, and obtain modified polyaspartic acid. (2) Mix modified polyaspartic acid, hydroxypropyltrimethylammonium chloride chitosan, 2,5-thiophene dicarboxylate and deionized water evenly, adjust the pH to 6-7 with hydrochloric acid aqueous solution, stir and react at 35-45℃ for 3-4 hours, filter, wash and dry to obtain oilfield corrosion and scale inhibitor.

[0010] As an optimization, the preparation steps of the 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid mixed solution in step (1) are as follows: 3,5-diaminosalicylic acid, p-aminobenzenesulfonic acid and 10wt% sodium hydroxide aqueous solution are mixed evenly in a mass ratio of 1:(0.4~0.5):(5~6) to obtain the 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid mixed solution.

[0011] As an optimization, the preparation steps of the modified polyaspartic acid in step (1) are as follows: polysuccinimide and deionized water are mixed evenly at a mass ratio of 1:(4~5), and a mixed solution of 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid with a mass of 7~8 times that of polysuccinimide is added within 30 min. The mixture is stirred and reacted at room temperature for 20~24 h. The pH is adjusted to 7~8 with hydrochloric acid aqueous solution, and anhydrous ethanol with a mass of 5~6 times that of polysuccinimide is added. The mixture is filtered, and the resulting precipitate is vacuum dried at 50~60℃ for 20~24 h to obtain modified polyaspartic acid.

[0012] As an optimization, the preparation steps of the oilfield corrosion and scale inhibitor in step (2) are as follows: Modified polyaspartic acid, hydroxypropyltrimethylammonium chloride chitosan, 2,5-thiophene dicarboxylate, and deionized water are mixed evenly in a mass ratio of 1:(0.6~0.7):(0.4~0.5):(15~20), the pH is adjusted to 6~7 with hydrochloric acid aqueous solution, the mixture is stirred and reacted at 35~45℃ for 3~4h, filtered and washed 2~4 times with 2wt% acetic acid aqueous solution, and vacuum dried at 40~50℃ for 10~12h to obtain the oilfield corrosion and scale inhibitor.

[0013] As an optimization, the preparation method of the hydroxypropyltrimethylammonium chloride chitosan is carried out with reference to the synthesis of O-quaternary ammonium salt chitosan in "Synthesis of O-quaternary ammonium salt oxidized chitosan and its antibacterial finishing of cotton fabrics".

[0014] As an optimization, the structure of the hydroxypropyltrimethylammonium chloride chitosan is as follows: .

[0015] Compared with the prior art, the beneficial effects achieved by the present invention are: In preparing the corrosion and scale inhibitor for oilfields, this invention involves reacting polysuccinimide with 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid to obtain modified polyaspartic acid; and reacting the modified polyaspartic acid, hydroxypropyltrimethylammonium chloride, chitosan, and 2,5-thiophene dicarboxaldehyde to obtain the corrosion and scale inhibitor for oilfields.

[0016] First, polysuccinimide undergoes a ring-opening reaction with the amino groups on 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid to generate modified polyaspartic acid containing sulfonic acid groups, phenolic hydroxyl groups, and amino groups. The polyaspartic acid structure contains peptide bonds similar to proteins, which can be oxidized and decomposed into CO2 and H2O under the action of microorganisms, making it an environmentally friendly water treatment agent with good application prospects. Polyaspartic acid also contains a large number of carboxylic acid groups, which can... 2+ Mg 2+ The modification alters the crystallization rate and crystal structure of ions that easily form scale in water, resulting in better scale inhibition performance. Sulfonic acid groups exhibit strong scale inhibition properties against CaCO3 and significantly suppress the formation of Ca3(PO4)2 scale. Since sulfonic acid is a stronger acid than carboxylic acid, incorporating sulfonic acid into polyaspartic acid, the resulting compound, through the synergistic effect of its functional groups, can effectively reduce the formation of calcium gel, is less susceptible to the influence of metal ions in water, and has a good inhibitory effect on calcium scale such as Ca3(PO4)2 and CaCO3. Furthermore, the carboxylic acid, phenolic hydroxyl, and sulfonic acid groups on the modified polyaspartic acid can react with Fe on the corroded metal surface. 2+ or Fe 3+ The combination of these components can form a protective film on the surface of the metal, thereby effectively hindering the development of corrosion and giving it good corrosion inhibition properties.

[0017] Secondly, modified polyaspartic acid and hydroxypropyltrimethylammonium chloride chitosan undergo a Schiff base reaction under the action of 2,5-thiophene dicarboxaldehyde to form a cross-linked network structure. Introducing quaternary ammonium salt chitosan into polyaspartic acid, the chitosan containing a large number of -OH groups enhances the polymer's stability against divalent cations, improving its resistance to hydrolysis and gelation. Therefore, the resulting oilfield corrosion and scale inhibitor forms a complex with calcium ions in water. This allows the oilfield corrosion and scale inhibitor to adsorb Ca3(PO4)2 and CaCO3 microcrystals, covering the crystal growth points and hindering crystal growth. Crystal dislocation occurs, reducing the interaction between crystals and decreasing calcium scale formation, thus improving the scale inhibition performance of the oilfield corrosion and scale inhibitor. Furthermore, the quaternary ammonium cations in the structure readily attract the negative charges on the metal surface, thereby increasing the H... + The discharge reaction is suppressed, hindering the cathodic reaction of the corrosion process, thus giving the prepared oilfield corrosion and scale inhibitor good corrosion inhibition performance; at the same time, the introduction of imine bonds increases the adsorption activity of the corrosion inhibitor, thereby further improving the corrosion inhibition performance; the sulfur atom in the thiophene ring of 2,5-thiophene dicarboxaldehyde contains lone pairs of electrons, which can form coordinate bonds with iron ions on the metal surface, forming a protective film on the metal surface, thereby improving the corrosion inhibition performance of the oilfield corrosion and scale inhibitor. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] The chitosan used in Comparative Example 15 below had a degree of deacetylation ≥95% and a viscosity-average molecular weight of 7.2 × 10⁻⁶. 5 Purchased from Sigma-Aldrich (Shanghai) Trading Co., Ltd.

[0020] Example 1:

[0021] A method for preparing an oilfield corrosion and scale inhibitor includes the following preparation steps: (1) 3,5-diaminosalicylic acid, p-aminobenzenesulfonic acid and 10wt% sodium hydroxide aqueous solution were mixed evenly in a mass ratio of 1:0.4:5 to prepare a mixed solution of 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid; polysuccinimide and deionized water were mixed evenly in a mass ratio of 1:4, and 7 times the mass of polysuccinimide mixed solution of 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid were added within 30 min. The mixture was stirred and reacted at room temperature for 20 h. The pH was adjusted to 7 with hydrochloric acid aqueous solution, and 5 times the mass of polysuccinimide anhydrous ethanol was added. The mixture was filtered, and the precipitate was dried under vacuum at 50℃ for 20 h to obtain modified polyaspartic acid. (2) Modified polyaspartic acid, hydroxypropyltrimethylammonium chloride chitosan, 2,5-thiophene dicarboxylate and deionized water were mixed evenly in a mass ratio of 1:0.6:0.4:15. The pH was adjusted to 6 with hydrochloric acid aqueous solution. The mixture was stirred at 35°C for 3 hours, filtered and washed twice with 2wt% acetic acid aqueous solution. The mixture was then vacuum dried at 40°C for 10 hours to obtain an oilfield corrosion and scale inhibitor.

[0022] Example 2:

[0023] A method for preparing an oilfield corrosion and scale inhibitor includes the following preparation steps: (1) 3,5-Diaminosalicylic acid, p-aminobenzenesulfonic acid, and 10wt% sodium hydroxide aqueous solution were mixed evenly in a mass ratio of 1:0.45:5.5 to obtain a mixed solution of 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid; polysuccinimide and deionized water were mixed evenly in a mass ratio of 1:4.5, and 7.5 times the mass of polysuccinimide of the mixed solution of 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid were added within 30 min. The mixture was stirred and reacted at room temperature for 22 h. The pH was adjusted to 7.5 with hydrochloric acid aqueous solution, and 5.5 times the mass of polysuccinimide of anhydrous ethanol was added. The mixture was filtered, and the resulting precipitate was dried under vacuum at 55℃ for 22 h to obtain modified polyaspartic acid. (2) Modified polyaspartic acid, hydroxypropyltrimethylammonium chloride chitosan, 2,5-thiophene dicarboxylate and deionized water were mixed evenly in a mass ratio of 1:0.65:0.45:18. The pH was adjusted to 6.5 with hydrochloric acid aqueous solution. The mixture was stirred and reacted at 40°C for 3.5 h. After filtration, the mixture was washed three times with 2wt% acetic acid aqueous solution and dried under vacuum at 45°C for 11 h to obtain an oilfield corrosion and scale inhibitor.

[0024] Example 3:

[0025] A method for preparing an oilfield corrosion and scale inhibitor includes the following preparation steps: (1) 3,5-diaminosalicylic acid, p-aminobenzenesulfonic acid and 10wt% sodium hydroxide aqueous solution were mixed evenly in a mass ratio of 1:0.5:6 to prepare a mixed solution of 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid; polysuccinimide and deionized water were mixed evenly in a mass ratio of 1:5, and 8 times the mass of polysuccinimide mixed solution of 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid were added within 30 min. The mixture was stirred and reacted at room temperature for 24 h. The pH was adjusted to 8 with hydrochloric acid aqueous solution, and 6 times the mass of polysuccinimide anhydrous ethanol was added. The mixture was filtered, and the resulting precipitate was dried under vacuum at 60℃ for 24 h to obtain modified polyaspartic acid. (2) Modified polyaspartic acid, hydroxypropyltrimethylammonium chloride chitosan, 2,5-thiophene dicarboxylate and deionized water were mixed evenly in a mass ratio of 1:0.7:0.5:20. The pH was adjusted to 7 with hydrochloric acid aqueous solution. The mixture was stirred and reacted at 45°C for 4 hours. The mixture was filtered and washed 4 times with 2wt% acetic acid aqueous solution. The mixture was then vacuum dried at 50°C for 12 hours to obtain an oilfield corrosion and scale inhibitor.

[0026] Comparative Example 1: The difference between the preparation method of the oilfield corrosion and scale inhibitor in Comparative Example 1 and Example 2 lies in the different step (1). Step (1) is modified as follows: 3,5-diaminosalicylic acid, p-aminobenzenesulfonic acid, and 10wt% sodium hydroxide aqueous solution are mixed evenly at a mass ratio of 1:0.2:5.5 to obtain a mixed solution of 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid; polysuccinimide and deionized water are mixed evenly at a mass ratio of 1:4.5, and 7.5 times the mass of the polysuccinimide mixed solution of 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid are added within 30 min. The mixture is stirred and reacted at room temperature for 22 h, the pH is adjusted to 7.5 with hydrochloric acid aqueous solution, and 5.5 times the mass of the polysuccinimide anhydrous ethanol is added. The mixture is filtered, and the resulting precipitate is vacuum dried at 55℃ for 22 h to obtain modified polyaspartic acid. The remaining steps are the same as in Example 2.

[0027] Comparative Example 2: The difference between the preparation method of the oilfield corrosion and scale inhibitor in Comparative Example 2 and Example 2 lies in step (1). Step (1) is modified as follows: 3,5-diaminosalicylic acid, p-aminobenzenesulfonic acid, and 10wt% sodium hydroxide aqueous solution are mixed evenly at a mass ratio of 1:0.3:5.5 to obtain a mixed solution of 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid; polysuccinimide and deionized water are mixed evenly at a mass ratio of 1:4.5, and 7.5 times the mass of the polysuccinimide mixed solution of 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid are added within 30 min. The mixture is stirred and reacted at room temperature for 22 h, the pH is adjusted to 7.5 with hydrochloric acid aqueous solution, and 5.5 times the mass of the polysuccinimide anhydrous ethanol is added. The mixture is filtered, and the resulting precipitate is vacuum dried at 55℃ for 22 h to obtain modified polyaspartic acid. The remaining steps are the same as in Example 2.

[0028] Comparative Example 3: The difference between the preparation method of the oilfield corrosion and scale inhibitor in Comparative Example 3 and Example 2 lies in the different step (1). Step (1) is modified as follows: 3,5-diaminosalicylic acid, p-aminobenzenesulfonic acid, and 10wt% sodium hydroxide aqueous solution are mixed evenly at a mass ratio of 1:0.6:5.5 to obtain a mixed solution of 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid; polysuccinimide and deionized water are mixed evenly at a mass ratio of 1:4.5, and 7.5 times the mass of the polysuccinimide mixed solution of 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid are added within 30 min. The mixture is stirred and reacted at room temperature for 22 h, the pH is adjusted to 7.5 with hydrochloric acid aqueous solution, and 5.5 times the mass of the polysuccinimide anhydrous ethanol is added. The mixture is filtered, and the resulting precipitate is vacuum dried at 55℃ for 22 h to obtain modified polyaspartic acid. The remaining steps are the same as in Example 2.

[0029] Comparative Example 4: The difference between the preparation method of the oilfield corrosion and scale inhibitor in Comparative Example 4 and Example 2 lies in step (1). Step (1) is modified as follows: 3,5-diaminosalicylic acid, p-aminobenzenesulfonic acid, and 10wt% sodium hydroxide aqueous solution are mixed evenly at a mass ratio of 1:0.7:5.5 to obtain a mixed solution of 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid; polysuccinimide and deionized water are mixed evenly at a mass ratio of 1:4.5, and 7.5 times the mass of the polysuccinimide mixed solution of 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid are added within 30 min. The mixture is stirred and reacted at room temperature for 22 h, the pH is adjusted to 7.5 with hydrochloric acid aqueous solution, and 5.5 times the mass of the polysuccinimide anhydrous ethanol is added. The mixture is filtered, and the resulting precipitate is vacuum dried at 55℃ for 22 h to obtain modified polyaspartic acid. The remaining steps are the same as in Example 2.

[0030] Comparative Example 5: The difference between the preparation method of the oilfield corrosion and scale inhibitor in Comparative Example 5 and Example 2 lies in step (2). Step (2) is modified as follows: Modified polyaspartic acid, hydroxypropyltrimethylammonium chloride chitosan, 2,5-thiophene dicarboxylate, and deionized water are mixed evenly at a mass ratio of 1:0.65:0.45:18. The pH is adjusted to 6.5 with hydrochloric acid aqueous solution, and the mixture is stirred and reacted at 20°C for 3.5 hours. The mixture is then filtered and washed three times with 2wt% acetic acid aqueous solution. Finally, it is vacuum dried at 45°C for 11 hours to obtain the oilfield corrosion and scale inhibitor. The remaining steps are the same as in Example 2.

[0031] Comparative Example 6: The difference between the preparation method of the oilfield corrosion and scale inhibitor in Comparative Example 6 and Example 2 lies in step (2). Step (2) is modified as follows: Modified polyaspartic acid, hydroxypropyltrimethylammonium chloride chitosan, 2,5-thiophene dicarboxylate, and deionized water are mixed evenly at a mass ratio of 1:0.65:0.45:18. The pH is adjusted to 6.5 with hydrochloric acid aqueous solution, and the mixture is stirred and reacted at 30°C for 3.5 hours. The mixture is then filtered and washed three times with 2wt% acetic acid aqueous solution. Finally, it is vacuum dried at 45°C for 11 hours to obtain the oilfield corrosion and scale inhibitor. The remaining steps are the same as in Example 2.

[0032] Comparative Example 7: The difference between the preparation method of the oilfield corrosion and scale inhibitor in Comparative Example 7 and Example 2 lies in step (2). Step (2) is modified as follows: Modified polyaspartic acid, hydroxypropyltrimethylammonium chloride chitosan, 2,5-thiophene dicarboxylate, and deionized water are mixed evenly at a mass ratio of 1:0.65:0.45:18. The pH is adjusted to 6.5 with hydrochloric acid aqueous solution, and the mixture is stirred and reacted at 50°C for 3.5 h. After filtration, the mixture is washed three times with 2wt% acetic acid aqueous solution and then vacuum dried at 45°C for 11 h to obtain the oilfield corrosion and scale inhibitor. The remaining steps are the same as in Example 2.

[0033] Comparative Example 8: The difference between the preparation method of the oilfield corrosion and scale inhibitor in Comparative Example 8 and Example 2 lies in step (2). Step (2) is modified as follows: Modified polyaspartic acid, hydroxypropyltrimethylammonium chloride chitosan, 2,5-thiophene dicarboxylate, and deionized water are mixed evenly in a mass ratio of 1:0.65:0.45:18. The pH is adjusted to 6.5 with hydrochloric acid aqueous solution, and the mixture is stirred and reacted at 60°C for 3.5 hours. The mixture is then filtered and washed three times with 2wt% acetic acid aqueous solution. Finally, it is vacuum dried at 45°C for 11 hours to obtain the oilfield corrosion and scale inhibitor. The remaining steps are the same as in Example 2.

[0034] Comparative Example 9: The difference between the preparation method of the oilfield corrosion and scale inhibitor in Comparative Example 9 and Example 2 lies in step (2). Step (2) is modified as follows: Modified polyaspartic acid, hydroxypropyltrimethylammonium chloride chitosan, 2,5-thiophene dicarboxylate, and deionized water are mixed evenly in a mass ratio of 1:0.65:0.45:18. The pH is adjusted to 6.5 with hydrochloric acid aqueous solution, and the mixture is stirred and reacted at 40°C for 1 hour. The mixture is then filtered and washed three times with 2wt% acetic acid aqueous solution. Finally, it is vacuum dried at 45°C for 11 hours to obtain the oilfield corrosion and scale inhibitor. The remaining steps are the same as in Example 2.

[0035] Comparative Example 10: The difference between the preparation method of the oilfield corrosion and scale inhibitor in Comparative Example 10 and Example 2 lies in step (2). Step (2) is modified as follows: Modified polyaspartic acid, hydroxypropyltrimethylammonium chloride chitosan, 2,5-thiophene dicarboxylate, and deionized water are mixed evenly in a mass ratio of 1:0.65:0.45:18. The pH is adjusted to 6.5 with hydrochloric acid aqueous solution, and the mixture is stirred and reacted at 40°C for 2 hours. The mixture is then filtered and washed three times with 2wt% acetic acid aqueous solution. Finally, it is vacuum dried at 45°C for 11 hours to obtain the oilfield corrosion and scale inhibitor. The remaining steps are the same as in Example 2.

[0036] Comparative Example 11: The difference between the preparation method of the oilfield corrosion and scale inhibitor in Comparative Example 11 and Example 2 lies in step (2). Step (2) is modified as follows: Modified polyaspartic acid, hydroxypropyltrimethylammonium chloride chitosan, 2,5-thiophene dicarboxaldehyde, and deionized water are mixed evenly in a mass ratio of 1:0.65:0.45:18. The pH is adjusted to 6.5 with hydrochloric acid aqueous solution, and the mixture is stirred and reacted at 40°C for 5 hours. The mixture is then filtered and washed three times with 2wt% acetic acid aqueous solution. Finally, it is vacuum dried at 45°C for 11 hours to obtain the oilfield corrosion and scale inhibitor. The remaining steps are the same as in Example 2.

[0037] Comparative Example 12: The difference between the preparation method of the oilfield corrosion and scale inhibitor in Comparative Example 12 and Example 2 lies in step (2). Step (2) is modified as follows: Modified polyaspartic acid, hydroxypropyltrimethylammonium chloride chitosan, 2,5-thiophene dicarboxaldehyde, and deionized water are mixed evenly in a mass ratio of 1:0.65:0.45:18. The pH is adjusted to 6.5 with hydrochloric acid aqueous solution, and the mixture is stirred and reacted at 40°C for 6 hours. The mixture is then filtered and washed three times with 2wt% acetic acid aqueous solution. Finally, it is vacuum dried at 45°C for 11 hours to obtain the oilfield corrosion and scale inhibitor. The remaining steps are the same as in Example 2.

[0038] Comparative Example 13: The difference between the preparation method of the oilfield corrosion and scale inhibitor in Comparative Example 13 and Example 2 lies in step (1). Step (1) is modified as follows: 3,5-diaminosalicylic acid, aniline, and 10wt% sodium hydroxide aqueous solution are mixed evenly at a mass ratio of 1:0.45:5.5 to obtain a mixed solution of 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid; polysuccinimide and deionized water are mixed evenly at a mass ratio of 1:4.5, and 7.5 times the mass of the polysuccinimide mixed solution of 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid are added within 30 min. The mixture is stirred and reacted at room temperature for 22 h, the pH is adjusted to 7.5 with hydrochloric acid aqueous solution, and 5.5 times the mass of the polysuccinimide anhydrous ethanol is added. The mixture is filtered, and the resulting precipitate is vacuum dried at 55℃ for 22 h to obtain modified polyaspartic acid. The remaining steps are the same as in Example 2.

[0039] Comparative Example 14: The difference between the preparation method of the oilfield corrosion and scale inhibitor in Comparative Example 14 and Example 2 lies in step (1). Step (1) is modified as follows: 3,5-diaminobenzoic acid, p-aminobenzenesulfonic acid, and 10wt% sodium hydroxide aqueous solution are mixed evenly at a mass ratio of 1:0.45:5.5 to obtain a mixed solution of 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid; polysuccinimide and deionized water are mixed evenly at a mass ratio of 1:4.5, and 7.5 times the mass of the polysuccinimide mixed solution of 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid are added within 30 min. The mixture is stirred and reacted at room temperature for 22 h, the pH is adjusted to 7.5 with hydrochloric acid aqueous solution, and 5.5 times the mass of the polysuccinimide anhydrous ethanol is added. The mixture is filtered, and the resulting precipitate is vacuum dried at 55℃ for 22 h to obtain modified polyaspartic acid. The remaining steps are the same as in Example 2.

[0040] Comparative Example 15: The difference between the preparation method of the oilfield corrosion and scale inhibitor in Comparative Example 15 and Example 2 lies in step (2). Step (2) is modified as follows: Modified polyaspartic acid, chitosan, 2,5-thiophene dicarboxaldehyde, and deionized water are mixed evenly in a mass ratio of 1:0.65:0.45:18. The pH is adjusted to 6.5 with hydrochloric acid aqueous solution, and the mixture is stirred and reacted at 40°C for 3.5 hours. The mixture is then filtered and washed three times with 2wt% acetic acid aqueous solution. Finally, it is vacuum dried at 45°C for 11 hours to obtain the oilfield corrosion and scale inhibitor. The remaining steps are the same as in Example 2.

[0041] Comparative Example 16: The difference between the preparation method of the oilfield corrosion and scale inhibitor in Comparative Example 16 and Example 2 lies in step (2). Step (2) is modified as follows: Modified polyaspartic acid, hydroxypropyltrimethylammonium chloride chitosan, glutaraldehyde, and deionized water are mixed evenly in a mass ratio of 1:0.65:0.45:18. The pH is adjusted to 6.5 with hydrochloric acid aqueous solution, and the mixture is stirred and reacted at 40°C for 3.5 h. After filtration, the mixture is washed three times with 2wt% acetic acid aqueous solution and then vacuum dried at 45°C for 11 h to obtain the oilfield corrosion and scale inhibitor. The remaining steps are the same as in Example 2.

[0042] Comparative Example 17: The preparation method of the oilfield corrosion and scale inhibitor in Comparative Example 17 differs from that in Example 2 in that step (2) is omitted, and step (1) is modified as follows: 3,5-diaminosalicylic acid, p-aminobenzenesulfonic acid, and 10wt% sodium hydroxide aqueous solution are mixed evenly at a mass ratio of 1:0.45:5.5 to obtain a mixed solution of 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid; polysuccinimide and deionized water are mixed evenly at a mass ratio of 1:4.5, and 7.5 times the mass of the polysuccinimide mixed solution of 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid are added within 30 min. The mixture is stirred and reacted at room temperature for 22 h, the pH is adjusted to 7.5 with hydrochloric acid aqueous solution, and 5.5 times the mass of the polysuccinimide anhydrous ethanol is added. The mixture is filtered, and the resulting precipitate is vacuum dried at 55℃ for 22 h to obtain the oilfield corrosion and scale inhibitor. The remaining steps are the same as in Example 2.

[0043] Test Example 1: Calcium carbonate scale inhibition performance test: The test method for calcium carbonate scale inhibition performance adopts GB / T16632-2008 "Determination of Scale Inhibition Performance of Water Treatment Agents - Calcium Carbonate Deposition Method". First, calcium chloride is used to prepare Ca... 2+ A water sample with a concentration of 240 mg / L was mixed with a borax buffer solution at pH 9, and then the oilfield corrosion and scale inhibitors prepared in Examples 1-3 and Comparative Examples 1-17 were added to form a mixture. Finally, an HCO3-based solution prepared with sodium bicarbonate was added. 3- A water sample with a concentration of 366 mg / L was placed in a constant-temperature water bath for a certain period of time. The Ca in the solution... 2+ During the storage process, the sample will form CaCO3 precipitate, thereby increasing the Ca content in the solution. 2+ The concentration decreased. Based on the determination of the remaining Ca in the sample... 2+ The scale inhibition efficiency was calculated based on the concentration; after the experiment, the Ca concentration was determined by titration. 2+ Concentration value, scale inhibition efficiency In the formula: η （碳酸钙） This indicates the scale inhibition rate of calcium carbonate; ρ0 and ρ1 represent the calcium carbonate scale inhibition rate of the blank water sample and the scale inhibition rate of the oilfield sample after adding the scale inhibitor. 2+ Concentration; ρ2 represents the Ca prepared at the beginning of the experiment. 2+ concentration.

[0044] Calcium phosphate scale inhibition performance test: The test method for calcium phosphate scale inhibition performance adopts GB / T22626-2008 "Determination of scale inhibition performance of water treatment agents - Calcium phosphate deposition method". First, sodium hydrogen phosphate is used to prepare PO4... 3- A water sample with a concentration of 5 mg / L was mixed with a borax buffer solution at pH 9, and then the oilfield corrosion and scale inhibitors prepared in Examples 1-3 and Comparative Examples 1-17 were added to form a mixture. Finally, a solution containing Ca2+ was added. 2+A water sample with a concentration of 240 mg / L was placed in a constant temperature water bath for a certain period of time. The water bath reaction caused the formation of Ca3(PO4)2 precipitate in the solution. The PO4 content was measured before and after equilibrium. 3- The phosphate concentration of the solution was measured using a 721 spectrophotometer at a wavelength of 710 nm to calculate the scale inhibition efficiency of the Ca3(PO4)2 scale. In the formula: η （磷酸钙） This indicates the scale inhibition rate of calcium phosphate; β0 and β1 represent the PO4 content of the blank water sample and the sample after adding the oilfield corrosion and scale inhibitor, respectively. 3- Concentration; β2 represents the PO4 solution prepared at the start of the experiment. 3- concentration.

[0045] Corrosion inhibition performance test: 20# carbon steel was used, the temperature was controlled at 45℃, the motor speed was controlled at 75 r / min, and the total test time was 72 h. 1.110 g CaCl2, 0.986 g MgSO4·7H2O, 0.336 g NaCl, and 0.336 g NaHCO3 were weighed and placed in a beaker to prepare a 2 L mixed solution. An oilfield corrosion and scale inhibitor was added, and the solution was placed in a unit tank of an RCC-Ⅲ type rotating plate corrosion apparatus. 20# carbon steel plates, after being degreased with anhydrous ethanol, dried, and weighed, were mounted on the rotating support, ensuring complete immersion in the solution. After the test, the 20# carbon steel was removed, acid-washed, alkali-washed, and dehydrated with anhydrous ethanol, then dried and weighed. The corrosion inhibition rate of the oilfield corrosion and scale inhibitor on the 20# carbon steel was calculated (20# carbon steel specifications: 50 mm × 25 mm × 2 mm, density: 7.85 g / cm³). 3 (The concentration of the slow-release scale inhibitor used in oilfields is 15 mg / L). The formula for calculating the corrosion inhibition rate is: ; ; Where m1 is the mass (g) of the carbon steel strip after pretreatment and drying before the experiment; m0 is the mass (g) of the 20# carbon steel strip after acid washing, alkali washing, dehydration with anhydrous ethanol, and drying. S represents the mass loss (g) of the pickling blank carbon steel strip; S represents the surface area (cm²) of the 20# carbon steel strip. 2 T represents the experimental time (h); D represents the density of the 20# carbon steel hanging sheet (g / cm³). 3 η represents the corrosion inhibition rate (%) of the oilfield corrosion and scale inhibitor under the experimental conditions. The annual corrosion rate (mm / a) of 20# carbon steel under conditions without oilfield corrosion and scale inhibitors. The annual corrosion rate (mm / a) of 20# carbon steel under the condition of adding oilfield corrosion and scale inhibitor.

[0046] The results are shown in Table 1. Table 1 Calcium carbonate scale inhibition Calcium phosphate scale inhibition Corrosion inhibition Example 1 93.5% 91.7% 89.2% Example 2 93.8% 92.1% 90.1% Example 3 93.7% 92.0% 89.7% Comparative Example 1 92.6% 86.3% 90.5% Comparative Example 2 93.3% 87.5% 90.2% Comparative Example 3 93.6% 92.3% 89.8% Comparative Example 4 93.4% 92.2% 89.5% Comparative Example 5 75.3% 70.8% 72.9% Comparative Example 6 81.6% 74.4% 78.7% Comparative Example 7 78.5% 71.9% 74.2% Comparative Example 8 68.1% 60.6% 60.4% Comparative Example 9 66.2% 56.4% 64.3% Comparative Example 10 74.7% 68.1% 73.6% Comparative Example 11 93.6% 91.9% 89.8% Comparative Example 12 93.4% 91.5% 89.5% Comparative Example 13 84.8% 69.7% 83.4% Comparative Example 14 93.3% 91.1% 81.0% Comparative Example 15 92.7% 90.8% 79.3% Comparative Example 16 93.1% 91.4% 77.9% Comparative Example 17 78.5% 70.3% 62.7% A comparison of the experimental data from Examples 1-3 and Comparative Examples 1-17 in Table 1 reveals that the corrosion and scale inhibitor prepared in this invention for oilfield applications exhibits excellent corrosion and scale inhibition properties.

[0047] Comparison of data from Example 2 with Comparative Examples 1-4 shows that the Ca3(PO4)2 inhibition performance of polyaspartic acid is not outstanding. With the increase of p-aminobenzenesulfonic acid content, the calcium phosphate scale inhibition rate of the prepared oilfield corrosion inhibitor increases accordingly. When the mass ratio of 3,5-diaminosalicylic acid to p-aminobenzenesulfonic acid is 1:0.45, even if the p-aminobenzenesulfonic acid content is further increased, the calcium phosphate scale inhibition rate does not increase significantly. On the contrary, due to the decrease of 3,5-diaminosalicylic acid, the phenolic hydroxyl content decreases, resulting in a decrease in the corrosion inhibition rate. Therefore, a mass ratio of 3,5-diaminosalicylic acid to p-aminobenzenesulfonic acid of 1:0.45 is the optimal condition for preparing the oilfield corrosion and scale inhibitor.

[0048] By comparing the data from Example 2 with those from Comparative Examples 5-8, it was shown that too low an experimental temperature would result in a low product conversion rate, while too high a temperature would cause hydrolysis and chain scission of polyaspartic acid or chitosan. Therefore, the optimal reaction temperature for synthesizing the oilfield corrosion and scale inhibitor is 40°C.

[0049] By comparing the data from Example 2 with those from Comparative Examples 9-12, it was shown that the corrosion inhibition rate and scale inhibition rate of the oilfield corrosion and scale inhibitor gradually increased with the increase of reaction time. When the experimental reaction time was more than 3.5 hours, the scale inhibition performance and corrosion inhibition performance of the oilfield corrosion and scale inhibitor did not increase significantly. Therefore, in order to avoid wasting time and energy, the optimal reaction time for synthesizing the oilfield corrosion and scale inhibitor is 3 hours.

[0050] The comparison between Example 2 and Comparative Example 13 demonstrates that polysuccinimide undergoes a ring-opening reaction with the amino groups on 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid to generate modified polyaspartic acid containing sulfonic acid groups, phenolic hydroxyl groups, and amino groups. The sulfonic acid groups exhibit strong scale inhibition properties against CaCO3 and significantly suppress the formation of Ca3(PO4)2 scale. Since sulfonic acid is a stronger acid than carboxylic acid, introducing sulfonic acid into polyaspartic acid results in a compound that, through the synergistic effect of its functional groups, effectively reduces the formation of calcium gel, is less susceptible to the influence of metal ions in water, and exhibits good inhibition of calcium scale such as Ca3(PO4)2 and CaCO3. Furthermore, the sulfonic acid groups can react with Fe on the corroded metal surface. 2+ or Fe 3+ The combination of these components can form a protective film on the surface of the metal, thereby effectively hindering the development of corrosion and giving it good corrosion inhibition properties.

[0051] The comparison between Example 2 and Comparative Example 14 demonstrates that polysuccinimide undergoes a ring-opening reaction with the amino groups on 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid to generate modified polyaspartic acid containing sulfonic acid groups, phenolic hydroxyl groups, and amino groups. The phenolic group on the modified polyaspartic acid can react with Fe on the corroded metal surface. 2+ or Fe 3+ The combination of these components can form a protective film on the surface of the metal, thereby effectively hindering the development of corrosion and giving it good corrosion inhibition properties.

[0052] The comparison between Example 2 and Comparative Example 15 demonstrates that the quaternary ammonium cations in the structure readily attract the negative charges on the metal surface, thereby enabling H... + The discharge reaction is suppressed, which hinders the cathodic reaction of the corrosion process, thus giving the prepared oilfield corrosion and scale inhibitor good corrosion inhibition performance.

[0053] The comparison between Example 2 and Comparative Example 16 demonstrates that the sulfur atom in the thiophene ring of 2,5-thiophenedicarboxaldehyde contains a lone pair of electrons, which can form a coordinate bond with iron ions on the metal surface, forming a protective film on the metal surface, thereby improving the corrosion inhibition performance of the oilfield corrosion and scale inhibitor.

[0054] The comparison between Example 2 and Comparative Example 17 demonstrates that modified polyaspartic acid and hydroxypropyltrimethylammonium chloride chitosan undergo a Schiff base reaction under the action of 2,5-thiophene dicarboxaldehyde to form a cross-linked network structure. The introduction of quaternary ammonium salt chitosan into polyaspartic acid, with its abundant -OH groups, enhances the polymer's stability against divalent cations, improving its resistance to hydrolysis and gelation. Therefore, the resulting oilfield corrosion and scale inhibitor forms a complex with calcium ions in water. This allows the inhibitor to adsorb Ca3(PO4)2 and CaCO3 microcrystals, covering the crystal growth points and hindering crystal growth. This leads to crystal dislocation, reduced inter-crystal interactions, and decreased calcium scale formation, thus improving the scale inhibition performance of the oilfield corrosion and scale inhibitor. The introduction of imine bonds further increases the adsorption activity of the corrosion inhibitor, thereby enhancing its corrosion inhibition performance.

[0055] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A corrosion and scale inhibitor for oilfield use, characterized in that, The oilfield corrosion and scale inhibitor is prepared by reacting modified polyaspartic acid, hydroxypropyltrimethylammonium chloride chitosan with 2,5-thiophene dicarboxaldehyde. The modified polyaspartic acid is prepared by reacting polysuccinimide with 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid.

2. The oilfield corrosion and scale inhibitor according to claim 1, characterized in that, The weight-average molecular weight of the polysuccinimide is 7000-8000.

3. A method for preparing a corrosion and scale inhibitor for oilfield use, characterized in that, The preparation steps include the following: (1) Mix polysuccinimide and deionized water evenly, add a mixed solution of 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid within 30 min, stir and react at room temperature for 20-24 h, adjust the pH to 7-8 with hydrochloric acid aqueous solution, add anhydrous ethanol, filter, dry, and obtain modified polyaspartic acid. (2) Mix modified polyaspartic acid, hydroxypropyltrimethylammonium chloride chitosan, 2,5-thiophene dicarboxylate and deionized water evenly, adjust the pH to 6-7 with hydrochloric acid aqueous solution, stir and react at 35-45℃ for 3-4 hours, filter, wash and dry to obtain oilfield corrosion and scale inhibitor.

4. The method for preparing an oilfield corrosion and scale inhibitor according to claim 3, characterized in that, The preparation steps of the 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid mixed solution in step (1) are as follows: 3,5-diaminosalicylic acid, p-aminobenzenesulfonic acid and 10wt% sodium hydroxide aqueous solution are mixed evenly in a mass ratio of 1:(0.4~0.5):(5~6) to obtain the 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid mixed solution.

5. The method for preparing an oilfield corrosion and scale inhibitor according to claim 3, characterized in that, The preparation steps of the modified polyaspartic acid in step (1) are as follows: polysuccinimide and deionized water are mixed evenly at a mass ratio of 1:(4~5). Within 30 min, a mixed solution of 3,5-diaminosalicylic acid and p-aminobenzenesulfonic acid with a mass of 7~8 times that of polysuccinimide is added. The mixture is stirred and reacted at room temperature for 20~24 h. The pH is adjusted to 7~8 with hydrochloric acid aqueous solution. Anhydrous ethanol with a mass of 5~6 times that of polysuccinimide is added. The mixture is filtered, and the resulting precipitate is vacuum dried at 50~60℃ for 20~24 h to obtain modified polyaspartic acid.

6. The method for preparing an oilfield corrosion and scale inhibitor according to claim 3, characterized in that, The preparation steps of the oilfield corrosion and scale inhibitor in step (2) are as follows: Modified polyaspartic acid, hydroxypropyltrimethylammonium chloride chitosan, 2,5-thiophene dicarboxylate, and deionized water are mixed evenly in a mass ratio of 1:(0.6~0.7):(0.4~0.5):(15~20), the pH is adjusted to 6~7 with hydrochloric acid aqueous solution, the mixture is stirred and reacted at 35~45℃ for 3~4h, filtered and washed 2~4 times with 2wt% acetic acid aqueous solution, and vacuum dried at 40~50℃ for 10~12h to obtain the oilfield corrosion and scale inhibitor.

7. A method for preparing an oilfield corrosion and scale inhibitor according to claim 3 or 6, characterized in that, The structure of the hydroxypropyltrimethylammonium chloride chitosan is as follows: .

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