Corrosion inhibitor for acidification of oil field and preparation method of corrosion inhibitor

Abstract

The invention relates to the technical field of corrosion inhibitors, and discloses a corrosion inhibitor for acidification of an oil field and a preparation method thereof, and the corrosion inhibitor comprises the following components by weight: 4-8 parts of alkenyl sulfur-containing cellulose and 2-5 parts of modified imidazoline. And the alkenyl sulfur-containing cellulose and the modified imidazoline are added into a stirrer to be stirred for 10-14 min, and the corrosion inhibitor for acidification of the oil field is obtained after stirring is finished. The alkenyl sulfur-containing cellulose and a branched chain of the modified imidazoline can be wound, so that a layer of compact protective film is formed on the metal surface, contact between an acid solution and the metal surface is effectively isolated, and corrosion is slowed down; meanwhile, the corrosion inhibitor for acidification of the oil field has a good high-temperature-resistant effect and a good corrosion inhibition effect.

Description

Technical Field

[0001] The invention relates to the technical field of corrosion inhibitors, in particular to a corrosion inhibitor for oilfield acidification and a preparation method thereof. Background Art

[0002] In the process of oil field development, acidizing operation is one of the important means to improve the productivity of oil wells. The acid used in the acidizing process can dissolve the minerals in the formation, expand the oil flow channel, and thus increase the production of oil wells. However, the acid is highly corrosive to the oil pipe, casing and downhole equipment. Long-term use will cause the equipment to fail to operate normally. Therefore, how to avoid this phenomenon is the key to solving the problem.

[0003] For example, the document "Preparation and Inhibition Mechanism of Corrosion Inhibitors for Shifting Acid" reports that the pyridine group or benzene ring forms an electron-donating conjugated system with the nitrogen-containing heterocyclic part of the corrosion inhibitor, which increases the adsorption area and enhances the adsorption capacity. When selecting the structure of the corrosion inhibitor, substituents such as pyridine group, thiol group and amino group are given priority. This application introduces a thiol substituent and then modifies it to prepare a corrosion inhibitor for oilfield acidification. Summary of the invention

[0004] Technical issues solved In view of the deficiencies in the prior art, the present invention provides a corrosion inhibitor for oilfield acidification and a preparation method thereof, which has a good corrosion inhibition effect.

[0005] To achieve the above object, the present invention provides the following technical solution: A corrosion inhibitor for oilfield acidification, comprising the following components by weight: 4-8 parts by weight of alkenyl sulfur-containing cellulose, 2-5 parts by weight of modified imidazoline; The preparation method of the modified imidazoline comprises the following steps: adding xylene and dimer acid into a four-necked flask in sequence, starting stirring and oil bathing, setting the temperature, and then adding 2-aminoethylheptadecenyl imidazoline in 4 batches; continuing stirring after the addition of 2-aminoethylheptadecenyl imidazoline, and then adding tetraethylenepentamine and continuing stirring; increasing the oil bath temperature to react; stopping heating after the reaction is completed, cooling and discharging the material to obtain the modified imidazoline.

[0006] Furthermore, the preparation method of the alkenyl sulfur-containing cellulose is: S1. Add 4.3-4.8 g of phosphorus-containing intermediate, 3.13-3.56 g of thioacetic acid, and 4.2-4.4 g of potassium carbonate to a methanol solvent, react at 20-25 ° C for 22-30 min, then add 4.1-4.2 g of potassium carbonate, continue to react for 3-4 h, add hydrochloric acid solution to neutralize the pH of the reaction solution to 6, concentrate the solution, precipitate, wash with water and acetone, and dry to obtain a dithiol phosphorus-containing intermediate; S2. Add epoxy cellulose, dithiol phosphorus-containing intermediate and tetrabutylammonium fluoride catalyst to 65-85 mL of N,N-dimethylformamide to carry out a ring-opening reaction, dilute the precipitate after the reaction, filter and wash to obtain modified cellulose; S3. Add 2.4-2.57 g of modified cellulose to 70-90 mL of N,N-dimethylformamide, stir and disperse, add 2.51-2.74 g of N-acryloyl-L-histidine and 0.012-0.015 g of catalyst, react at 50-65° C. for 6-10 h, filter after completion, wash the filter cake, and obtain alkenyl sulfur-containing cellulose; Preparation of the phosphorus-containing intermediate in S1: adding 3,9-dichloro-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane 3,9-dioxide, 4-bromomethylbenzyl alcohol and triethylamine to an acetonitrile solvent for reaction, concentrating the solution after the reaction, washing the precipitate with acetone and drying to obtain the phosphorus-containing intermediate; The preparation of epoxy cellulose in S2 is as follows: cellulose is added to a sodium hydroxide aqueous solution, and then epichlorohydrin and ethanol are added dropwise, and stirred for reaction to obtain epoxy cellulose; The preparation of N-acryloyl-L-histidine in S3 is as follows: sodium hydroxide and L-histidine are added to distilled water, and then acryloyl chloride is continuously added dropwise to react, and after the reaction, a hydrochloric acid solution is added dropwise to adjust the pH of the solution, acetone is added to the solution, and the filtrate is filtered and then decompressed and distilled to remove the acetone, and freeze-dried, and the product is added to a hydrochloric acid solution, and acetone is added again to precipitate a precipitate, which is filtered and dried to obtain N-acryloyl-L-histidine.

[0007] Furthermore, the amount of methanol in the S1 is 65-75 mL.

[0008] Furthermore, the mass ratio of epoxy cellulose, dithiol phosphorus-containing intermediate and tetrabutylammonium fluoride catalyst in S2 is 3.1-3.5g:1.46-2.21g:0.02-0.03g.

[0009] Furthermore, the reaction temperature in S2 is 70-80°C.

[0010] Furthermore, the reaction time in S2 is 3-5h.

[0011] Furthermore, the catalyst in S3 is 4-dimethylaminopyridine.

[0012] Furthermore, the preparation method of the corrosion inhibitor for oilfield acidification is: adding olefinic sulfur-containing cellulose and modified imidazoline into a stirrer and stirring for 10-14 minutes, and then obtaining the corrosion inhibitor for oilfield acidification.

[0013] Beneficial technical effects The invention adds alkenyl sulfur-containing cellulose and modified imidazoline into a stirrer and stirs for 10-14 minutes to obtain a corrosion inhibitor for oilfield acidification.

[0014] The bromine group in the phosphorus-containing intermediate and thioacetic acid are reacted under the action of potassium carbonate to introduce a thiol group, thereby obtaining a dithiol phosphorus-containing intermediate; the epoxy group in epoxy cellulose and the thiol group in the dithiol phosphorus-containing intermediate undergo a ring-opening reaction to introduce a thioether bond and generate a hydroxyl group, thereby obtaining modified cellulose; and the esterification reaction with the carboxyl group in N-acryloyl-L-histidine is continued to introduce an alkenyl group, thereby obtaining alkenyl sulfur-containing cellulose.

[0015] In the highly acidic oil field environment (such as acidic oil and gas wells containing high concentrations of hydrogen sulfide), the π electrons of the olefinic group form weak coordination bonds with the empty metal orbitals (such as the 3d orbitals of Fe), temporarily blocking the corrosion reaction and reducing the contact area between the metal and the acid. This adsorption is based on the π electrons of the double bond and the empty d orbitals or sp orbitals of the metal atoms. 3 The interaction between the hybrid orbitals enables the alkenyl molecules to form an adsorption layer on the metal surface, which has a good corrosion inhibition effect; the alkenyl in the modified imidazoline can also have a good corrosion inhibition effect. The sulfur atoms contained in the alkenyl sulfur-containing cellulose have lone pairs of electrons, which can form stable coordination bonds with the metal surface and form a dense protective film, thereby effectively isolating the contact between the acid and the metal surface. In addition, there are more grafting sites on cellulose, which increases the degree of substitution of the alkenyl and sulfur elements, further improving its corrosion inhibition performance; at the same time, the alkenyl sulfur-containing cellulose will be entangled with the side chains of the modified imidazoline, so that it forms a dense protective film on the metal surface, thereby effectively isolating the contact between the acid and the metal surface and slowing down corrosion. DETAILED DESCRIPTION

[0016] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] Preparation of epoxy cellulose: Add 2 g of cellulose to 100 mL of 4% sodium hydroxide aqueous solution, then drop 6 mL of epichlorohydrin and 20 mL of ethanol, stir and react at 60 °C for 4 h to obtain epoxy cellulose.

[0018] Preparation of phosphorus-containing intermediate: Add 4 g of 3,9-dichloro-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane 3,9-dioxide, 6.2 g of 4-bromomethylbenzyl alcohol, and 2.8 g of triethylamine to 60 mL of acetonitrile solvent, first react at 10°C for 60 min, then react at 70°C for 6 h. After the reaction, concentrate the solution, wash the precipitate with acetone, and dry to obtain the phosphorus-containing intermediate.

[0019] Add 1 g of sodium hydroxide and 3.1 g of L-histidine to 10 mL of distilled water, add 1.8 g of acryloyl chloride dropwise at 0°C, and then react at 20°C for 18 hours. After the reaction, add hydrochloric acid solution dropwise to adjust the pH of the solution to 2. Add 400 mL of acetone to the solution, filter, and distill the filtrate under reduced pressure to remove acetone, freeze-dry, add the product to 3 mL of hydrochloric acid solution (pH = 2), and then add 50 mL of acetone to precipitate the precipitate, filter, and dry to obtain N-acryloyl-L-histidine.

[0020] The preparation method of modified imidazoline refers to the literature "Preparation and Performance Study of MTB Imidazolin Curing Agent": xylene and 0.3 mol of dimer acid are added to a four-necked flask in sequence, stirring and oil bath are turned on, the temperature is set to 40°C, and then 0.3 mol of 2-aminoethylheptadecenyl imidazoline is added in 4 batches, with an interval of 10 min between each batch; after the addition of 2-aminoethylheptadecenyl imidazoline is completed, stirring is continued for 20 min, and then 0.3 mol of tetraethylenepentamine is added at one time, and stirring is continued for 20 min; the oil bath temperature is increased and set to 140-160°C. When a fraction appears in the oil-water separator, high-purity nitrogen protection is turned on and the reaction time is calculated. The reaction time is set to 3-4h (the reaction progress can be evaluated by weighing the mass of the lower fraction of the oil-water separator in the later stage of the reaction); after the reaction is completed, heating is stopped, and the material is discharged in time when the temperature drops to 70~80°C to obtain modified imidazoline. Example 1

[0021] S1. Add 4.3 g of phosphorus-containing intermediate, 3.13 g of thioacetic acid, and 4.2 g of potassium carbonate to 65 mL of methanol solvent, react at 20 ° C for 22 min, then add 4.1 g of potassium carbonate, continue to react for 3 h, add hydrochloric acid solution to neutralize the pH of the reaction solution to 6, concentrate the solution, precipitate, wash with water and acetone, and dry to obtain a dithiol phosphorus-containing intermediate; the reaction is as follows:

[0022] S2. 3.1 g of epoxy cellulose, 1.46 g of dithiol phosphorus intermediate and 0.02 g of tetrabutylammonium fluoride catalyst were added to 65 mL of N,N-dimethylformamide, and the ring-opening reaction was carried out at 70° C. for 3 h. After the reaction, the precipitate was diluted, filtered and washed to obtain modified cellulose; the reaction was as follows:

[0023] S3. Add 2.4 g of modified cellulose to 70 mL of N,N-dimethylformamide, stir and disperse, add 2.51 g of N-acryloyl-L-histidine and 0.012 g of 4-dimethylaminopyridine catalyst, react at 50° C. for 6 h, filter after completion, wash the filter cake, and obtain alkenyl sulfur-containing cellulose; the reaction is as follows:

[0024] S4. 4 parts by weight of alkenyl sulfur-containing cellulose and 2 parts by weight of modified imidazoline are added into a stirrer and stirred for 10 minutes to obtain a corrosion inhibitor for oilfield acidification. Example 2

[0025] S1. Add 4.8 g of phosphorus-containing intermediate, 3.56 g of thioacetic acid, and 4.4 g of potassium carbonate to 75 mL of methanol solvent, react at 25 ° C for 30 min, then add 4.2 g of potassium carbonate, continue to react for 4 h, add hydrochloric acid solution to neutralize the pH of the reaction solution to 6, concentrate the solution, precipitate, wash with water and acetone, and dry to obtain a dithiol phosphorus-containing intermediate; S2. 3.5 g of epoxy cellulose, 2.21 g of dithiol phosphorus intermediate and 0.03 g of tetrabutylammonium fluoride catalyst were added to 85 mL of N,N-dimethylformamide, and the ring-opening reaction was carried out at 80 ° C for 5 h. After the reaction, the precipitate was diluted, filtered and washed to obtain modified cellulose; S3. Add 2.57 g of modified cellulose to 90 mL of N,N-dimethylformamide, stir and disperse, add 2.74 g of N-acryloyl-L-histidine and 0.015 g of 4-dimethylaminopyridine catalyst, react at 65 ° C for 10 h, filter after completion, wash the filter cake, and obtain alkenyl sulfur-containing cellulose; S4. 8 parts by weight of alkenyl sulfur-containing cellulose and 5 parts by weight of modified imidazoline are added to a stirrer and stirred for 14 minutes to obtain a corrosion inhibitor for oilfield acidification. Example 3

[0026] S1. Add 4.5 g of phosphorus-containing intermediate, 3.34 g of thioacetic acid, and 4.3 g of potassium carbonate to 70 mL of methanol solvent, react at 22 ° C for 26 min, then add 4.15 g of potassium carbonate, continue to react for 3.5 h, add hydrochloric acid solution to neutralize the pH of the reaction solution to 6, concentrate the solution, precipitate, wash with water and acetone, and dry to obtain a dithiol phosphorus-containing intermediate; S2. 3.3 g of epoxy cellulose, 1.83 g of dithiol phosphorus intermediate and 0.025 g of tetrabutylammonium fluoride catalyst were added to 75 mL of N,N-dimethylformamide, and the ring-opening reaction was carried out at 78 ° C for 4 h. After the reaction, the precipitate was diluted, filtered and washed to obtain modified cellulose; S3. Add 2.48 g of modified cellulose to 80 mL of N,N-dimethylformamide, stir and disperse, add 2.74 g of N-acryloyl-L-histidine and 0.013 g of 4-dimethylaminopyridine catalyst, react at 60 ° C for 8 h, filter after completion, wash the filter cake, and obtain alkenyl sulfur-containing cellulose; S4. 6 parts by weight of alkenyl sulfur-containing cellulose and 4 parts by weight of modified imidazoline are added into a stirrer and stirred for 12 minutes to obtain a corrosion inhibitor for oilfield acidification. Example 4

[0027] S1. Add 4.3 g of phosphorus-containing intermediate, 3.13 g of thioacetic acid, and 4.2 g of potassium carbonate to 65 mL of methanol solvent, react at 20 ° C for 22 min, then add 4.1 g of potassium carbonate, continue to react for 3 h, add hydrochloric acid solution to neutralize the pH of the reaction solution to 6, concentrate the solution, precipitate, wash with water and acetone, and dry to obtain a dithiol phosphorus-containing intermediate; S2. 3.5 g of epoxy cellulose, 2.21 g of dithiol phosphorus intermediate and 0.03 g of tetrabutylammonium fluoride catalyst were added to 85 mL of N,N-dimethylformamide, and the ring-opening reaction was carried out at 80 ° C for 5 h. After the reaction, the precipitate was diluted, filtered and washed to obtain modified cellulose; S3. Add 2.57 g of modified cellulose to 90 mL of N,N-dimethylformamide, stir and disperse, add 2.74 g of N-acryloyl-L-histidine and 0.015 g of 4-dimethylaminopyridine catalyst, react at 65 ° C for 10 h, filter after completion, wash the filter cake, and obtain alkenyl sulfur-containing cellulose; S4. 6 parts by weight of alkenyl sulfur-containing cellulose and 4 parts by weight of modified imidazoline are added into a stirrer and stirred for 12 minutes to obtain a corrosion inhibitor for oilfield acidification. Example 5

[0028] S1. Add 4.8 g of phosphorus-containing intermediate, 3.56 g of thioacetic acid, and 4.4 g of potassium carbonate to 75 mL of methanol solvent, react at 25 ° C for 30 min, then add 4.2 g of potassium carbonate, continue to react for 4 h, add hydrochloric acid solution to neutralize the pH of the reaction solution to 6, concentrate the solution, precipitate, wash with water and acetone, and dry to obtain a dithiol phosphorus-containing intermediate; S2. 3.3 g of epoxy cellulose, 1.83 g of dithiol phosphorus intermediate and 0.025 g of tetrabutylammonium fluoride catalyst were added to 75 mL of N,N-dimethylformamide, and the ring-opening reaction was carried out at 78 ° C for 4 h. After the reaction, the precipitate was diluted, filtered and washed to obtain modified cellulose; S3. Add 2.48 g of modified cellulose to 80 mL of N,N-dimethylformamide, stir and disperse, add 2.53 g of N-acryloyl-L-histidine and 0.013 g of 4-dimethylaminopyridine catalyst, react at 60 ° C for 8 h, filter after completion, wash the filter cake, and obtain alkenyl sulfur-containing cellulose; S4. 4 parts by weight of alkenyl sulfur-containing cellulose and 2 parts by weight of modified imidazoline are added into a stirrer and stirred for 10 minutes. After stirring, a corrosion inhibitor for oilfield acidification is obtained. Example 6

[0029] S1. Add 4.5 g of phosphorus-containing intermediate, 3.34 g of thioacetic acid, and 4.3 g of potassium carbonate to 70 mL of methanol solvent, react at 22 ° C for 26 min, then add 4.15 g of potassium carbonate, continue to react for 3.5 h, add hydrochloric acid solution to neutralize the pH of the reaction solution to 6, concentrate the solution, precipitate, wash with water and acetone, and dry to obtain a dithiol phosphorus-containing intermediate; S2. 3.1 g of epoxy cellulose, 1.46 g of dithiol phosphorus intermediate and 0.02 g of tetrabutylammonium fluoride catalyst were added to 65 mL of N,N-dimethylformamide, and the ring-opening reaction was carried out at 70 ° C for 3 h. After the reaction, the precipitate was diluted, filtered and washed to obtain modified cellulose; S3. Add 2.4 g of modified cellulose to 70 mL of N,N-dimethylformamide, stir and disperse, add 2.51 g of N-acryloyl-L-histidine and 0.012 g of 4-dimethylaminopyridine catalyst, react at 50 ° C for 6 h, filter after completion, wash the filter cake, and obtain alkenyl sulfur-containing cellulose; S4. 8 parts by weight of alkenyl sulfur-containing cellulose and 5 parts by weight of modified imidazoline are added to a stirrer and stirred for 14 minutes to obtain a corrosion inhibitor for oilfield acidification.

[0030] Comparative Example 1

[0031] Compared with Example 6, this comparative example differs in that a dithiol phosphorus-containing intermediate is used instead of alkenyl sulfur-containing cellulose.

[0032] Comparative Example 2

[0033] Compared with Example 6, this comparative example differs in that modified cellulose is used instead of alkenyl sulfur-containing cellulose.

[0034] The static corrosion rate at normal pressure and the dynamic corrosion rate at high temperature and high pressure were determined according to the method in SY / T 5405-2019 "Performance Test Method and Evaluation Method of Corrosion Inhibitors for Acidification". Test 1: acid solution 20wt% hydrochloric acid, reaction time 4h, reaction temperature 90℃ at normal pressure, corrosion inhibitor (mass fraction) 1%; Test 2: acid solution 20wt% hydrochloric acid, reaction time 4h, reaction temperature 180℃ at 16Mpa, corrosion inhibitor (mass fraction) 5%.

[0035] Table 1: Corrosion inhibition performance test.

[0036] project Surface morphology <![CDATA[Test 1 Corrosion Rate (gm -2 h -1 )]]> <![CDATA[Test 2 Corrosion Rate (gm -2 h -1 )]]> Example 1 Smooth and flat 1.22 25.48 Example 2 Smooth and flat 1.08 24.15 Example 3 Smooth and flat 1.12 25.74 Example 4 Smooth and flat 1.09 24.39 Example 5 Smooth and flat 1.14 25.76 Example 6 Smooth and flat 1.11 24.19 Comparative Example 1 Slightly uneven 3.27 45.37 Comparative Example 2 Slightly uneven 2.89 39.22 It can be seen from Table 1 that the corrosion inhibitor for oilfield acidification of the present invention, Examples 1-6 have better corrosion inhibition effect and high temperature resistance effect than Comparative Examples 1-2.

[0037] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

Claims

1. A corrosion inhibitor for oilfield acidification, characterized in that: The invention comprises the following components by weight: 4-8 parts by weight of alkenyl sulfur-containing cellulose and 2-5 parts by weight of modified imidazoline; The preparation method of the modified imidazoline comprises the following steps: adding xylene and dimer acid into a four-necked flask in sequence, starting stirring and oil bathing, setting the temperature, and then adding 2-aminoethylheptadecenyl imidazoline in 4 batches; continuing stirring after the addition of 2-aminoethylheptadecenyl imidazoline, and then adding tetraethylenepentamine and continuing stirring; increasing the oil bath temperature to react; stopping heating after the reaction is completed, cooling and discharging the material to obtain the modified imidazoline.

2. The corrosion inhibitor for oilfield acidification according to claim 1, characterized in that: The preparation method of the alkenyl sulfur-containing cellulose is: S1. Add 4.3-4.8 g of phosphorus-containing intermediate, 3.13-3.56 g of thioacetic acid, and 4.2-4.4 g of potassium carbonate to a methanol solvent, react at 20-25 ° C for 22-30 min, then add 4.1-4.2 g of potassium carbonate, continue to react for 3-4 h, add hydrochloric acid solution to neutralize the pH of the reaction solution to 6, concentrate the solution, precipitate, wash with water and acetone, and dry to obtain a dithiol phosphorus-containing intermediate; S2. Add epoxy cellulose, dithiol phosphorus-containing intermediate and tetrabutylammonium fluoride catalyst to 65-85 mL of N,N-dimethylformamide to carry out a ring-opening reaction, dilute the precipitate after the reaction, filter and wash to obtain modified cellulose; S3. Add 2.4-2.57 g of modified cellulose to 70-90 mL of N,N-dimethylformamide, stir and disperse, add 2.51-2.74 g of N-acryloyl-L-histidine and 0.012-0.015 g of catalyst, react at 50-65° C. for 6-10 h, filter after completion, wash the filter cake, and obtain alkenyl sulfur-containing cellulose; Preparation of the phosphorus-containing intermediate in S1: adding 3,9-dichloro-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane 3,9-dioxide, 4-bromomethylbenzyl alcohol and triethylamine to an acetonitrile solvent for reaction, concentrating the solution after the reaction, washing the precipitate with acetone and drying to obtain the phosphorus-containing intermediate; The preparation of epoxy cellulose in S2 is as follows: cellulose is added to a sodium hydroxide aqueous solution, and then epichlorohydrin and ethanol are added dropwise, and stirred for reaction to obtain epoxy cellulose; The preparation of N-acryloyl-L-histidine in S3 is as follows: sodium hydroxide and L-histidine are added to distilled water, and then acryloyl chloride is continuously added dropwise to react, and after the reaction, a hydrochloric acid solution is added dropwise to adjust the pH of the solution, acetone is added to the solution, and the filtrate is filtered and then decompressed and distilled to remove the acetone, and freeze-dried, and the product is added to a hydrochloric acid solution, and acetone is added again to precipitate a precipitate, which is filtered and dried to obtain N-acryloyl-L-histidine.

3. The corrosion inhibitor for oilfield acidification according to claim 2, characterized in that: The amount of methanol in the S1 is 65-75 mL.

4. The corrosion inhibitor for oilfield acidification according to claim 2, characterized in that: The mass ratio of epoxy cellulose, dithiol phosphorus-containing intermediate and tetrabutylammonium fluoride catalyst in S2 is 3.1-3.5g:1.46-2.21g:0.02-0.03g.

5. The corrosion inhibitor for oilfield acidification according to claim 2, characterized in that: The reaction temperature in S2 is 70-80°C.

6. The corrosion inhibitor for oilfield acidification according to claim 2, characterized in that: The reaction time in S2 is 3-5h.

7. The corrosion inhibitor for oilfield acidification according to claim 2, characterized in that: The catalyst in S3 is 4-dimethylaminopyridine.

8. A method for preparing the corrosion inhibitor for oilfield acidification according to any one of claims 1 to 7, characterized in that: The preparation method of the corrosion inhibitor for oilfield acidification is as follows: adding alkenyl sulfur-containing cellulose and modified imidazoline into a stirrer and stirring for 10-14 minutes, and then obtaining the corrosion inhibitor for oilfield acidification.

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