Anti-carbon dioxide corrosion inhibitor as well as preparation method and application thereof

Abstract

The invention relates to the technical field of preparation of oilfield chemical assistants, in particular to an anti-carbon dioxide corrosion inhibitor and a preparation method and application thereof.The anti-carbon dioxide corrosion inhibitor is obtained by mixing and compounding a first polymer, a second polymer and modified imidazoline according to the required amount, the second polymer is imidazoline with a linear structure. According to the corrosion inhibitor, n imidazoline rings in molecules of the first polymer are adsorbed on a stainless steel pipe, the adsorption capacity and the scouring resistance of the corrosion inhibitor are improved, the adsorbability of imidazoline is improved through the second polymer, the hydrophobic capacity of monocyclic imidazoline is improved by introducing a primary amine hydrophobic group into the modified imidazoline, the water phase is further inhibited from making contact with the metal surface, and the corrosion inhibitor has a good corrosion inhibition effect on the stainless steel pipe. Meanwhile, a guanidine structure is introduced into an imidazoline structure, so that the product has a strong sterilization effect, and a polymer chain structure contains a carboxylic acid structure, so that the product has relatively strong capability of complexing cations such as calcium and magnesium, and the scaling problem caused by carbon dioxide can be effectively inhibited.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield chemical additive preparation, and is an anti-carbon dioxide corrosion inhibitor and a preparation method and application thereof. Background Art

[0002] Oilfield wastewater contains corrosive gases such as dissolved oxygen, hydrogen sulfide and carbon dioxide, which are severely corrosive to metal pipelines and equipment in wastewater treatment and reinjection systems. Corrosion inhibitors are mainly used to prevent corrosion and oxidation of metal surfaces. They inhibit or slow down the metal corrosion process by forming a protective film or other chemical action mechanisms, reducing the contact between the metal surface and oxygen, moisture and other substances in the environment, thereby preventing corrosion and oxidation of the metal surface. In oilfield development, corrosion inhibitors can be adsorbed on the metal surface to form a protective film, inhibiting and alleviating corrosion of the metal surface.

[0003] Scaling is one of the most serious problems encountered in oilfield water quality control. Scaling can occur in various parts of the formation, wellbore or ground. Some wells and oil layers are abandoned prematurely due to the deposition of scale in the production layer of the wellbore blasthole; Scaling can also occur in gravel packing, downhole pumps, oil pipe strings, oil nozzles and oil storage equipment, gathering and transportation pipelines, crude oil processing equipment, cooling towers, boilers and water injection and sewage pipelines and other equipment and any part of the water treatment system. Scaling will bring serious harm to oilfield production: scale is a poor conductor of heat, and the formation of scale greatly reduces the heat transfer effect; the deposition of scale will cause local corrosion and damage to equipment and pipelines; scale will also reduce the cross-sectional area of ​​water flow, increase water flow resistance and transmission energy, and increase cleaning costs. The main function of scale inhibitors is to disperse insoluble inorganic salts in water, prevent or interfere with the precipitation and scaling of insoluble inorganic salts on metal surfaces. It controls the formation of scale by dispersion, chelation and other methods to maintain a good heat transfer effect of metal equipment. In oil field development, scale inhibitors can effectively prevent blockage and scaling of pipelines or water treatment equipment.

[0004] In the oilfield water system, mainly in the water injection system for reinjecting sewage, the presence of microorganisms has brought great harm to oilfield production. Among them, the most serious harm is sulfate-reducing bacteria, whose product hydrogen sulfide is particularly corrosive to metals, and the product iron sulfide is a substance that causes pipeline blockage. The second is saprophytic bacteria and iron bacteria that can produce mucus. When the number of these bacteria exceeds a certain value, they can produce oxygen concentration corrosion cells, causing the injection well to be blocked and the injection volume to be reduced. Other organisms such as algae, sulfur bacteria, yeasts and molds may also cause blockages and produce oxygen concentration corrosion cells, but the problems caused are not as serious as the above bacteria. Fungicides can prevent and control plant diseases caused by various pathogenic microorganisms. In oilfield development, fungicides are mainly used to inhibit or eliminate microorganisms in water to prevent bacteria, algae, fungi, etc. from damaging equipment.

[0005] Therefore, corrosion, scaling and bacterial growth are common problems in the process of oil field development and pipeline network collection and transportation. If they are not effectively controlled, they will have a serious impact on oil field production. At present, corrosion inhibitors, scale inhibitors and bactericides are usually added after simple compounding. However, this not only leads to high cost of the agents, but also poor compatibility between various agents, resulting in poor use effect after compounding.

[0006] Therefore, it is necessary to develop a chemical additive with excellent corrosion inhibition effect, bactericidal effect and strong ability to complex cations such as calcium and magnesium for application in oil field development. Summary of the invention

[0007] The present invention provides an anti-carbon dioxide corrosion inhibitor and a preparation method and application thereof, which overcome the deficiencies of the above-mentioned prior art and can effectively solve the problems in the existing oil field development, such as high cost of corrosion inhibitors, scale inhibitors and bactericides when simply compounded and added, poor compatibility of various agents, easy corrosion, scaling and bacterial growth.

[0008] One of the technical solutions of the present invention is achieved by the following measures: A method for preparing a carbon dioxide corrosion inhibitor is carried out according to the following method: The required amount of the first polymer, the second polymer and the modified imidazoline are mixed and compounded to obtain a carbon dioxide corrosion inhibitor, wherein the first polymer is a comb-shaped imidazoline, the second polymer is a linear structure imidazoline, and the modified imidazoline is a primary amine modified imidazoline.

[0009] The following is a further optimization and / or improvement of one of the above-mentioned technical solutions: The first polymer is obtained according to the following method: S1, mixing the required amount of macromolecular petroleum acid and polyamine uniformly and reacting them to obtain intermediate 1; S2, mixing the intermediate 1 and a required amount of guanidine hydrochloride uniformly and reacting them to obtain the intermediate 2; S3, adding a solvent and a chain transfer agent to a required amount of monomer, and then adding a required amount of initiator to react to obtain an intermediate three; S4, uniformly mixing the intermediate 2, the intermediate 3 and a required amount of polyetheramine and reacting them to obtain a first polymer.

[0010] In the above step S1, the molar ratio of macromolecular petroleum acid to polyamine is 0.9 to 1.1:0.9 to 1.1, the reaction temperature is 250°C to 300°C, and the reaction time is 9h to 11h, wherein the polyamine is polyethylene polyamine and the macromolecular petroleum acid is a by-product in the petroleum refining process.

[0011] In the above step S2, the molar ratio of intermediate 1 to guanidine hydrochloride is 0.9 to 1.1:0.9 to 1.1, the reaction temperature is 140° C. to 150° C., and the reaction time is 2.5 h to 3.5 h.

[0012] In the above step S3, the monomer is one or more of acrylic acid, maleic anhydride, and methacrylic acid, the solvent is one of methanol, ethanol, n-butanol, propylene glycol, glycerol, ethylene glycol, xylene, trimethylbenzene, dimethyl sulfoxide, and dimethylformamide, the chain transfer agent is n-dodecyl mercaptan, the initiator is one of azobisisobutyronitrile and dibenzoyl peroxide, the reaction temperature is 60°C to 120°C, and the reaction time is 3.5h to 4.5h.

[0013] In the above step S4, the polyetheramine is one of D350 and D600, the reaction temperature is 100° C. to 150° C., and the reaction time is 3.5 h to 4.5 h.

[0014] The second polymer is obtained according to the following method: S11, reacting a required amount of the intermediate 1 obtained in step S1 with a polycarboxylic acid to obtain a first reaction product; S12, mixing the chlorine-containing compound with the first reaction product and performing a cross-linking reaction to obtain a second polymer.

[0015] In the above step S11, the polycarboxylic acid is one of adipic acid, suberic acid and oxalic acid, the molar ratio of the polycarboxylic acid to the intermediate 1 is 1:1 to 2, the reaction temperature is 100° C. to 150° C., and the reaction time is 3.5 h to 4.5 h.

[0016] In the above step S12, the chlorine-containing compound is 1,4-benzyl dichloride, the molar ratio of the chlorine-containing compound to the first reaction product is 1:1 to 2, the reaction temperature is 70° C. to 100° C., and the reaction time is 3.5 h to 4.5 h.

[0017] The modified imidazoline is obtained by the following method: required amounts of the intermediate 1 obtained in step S1, guanidine hydrochloride and a primary amine are mixed and reacted to obtain the modified imidazoline.

[0018] The molar ratio of the intermediate 1, guanidine hydrochloride and primary amine is 1:1:1, the reaction temperature is 145° C. to 155° C., and the reaction time is 3.5 h to 4.5 h.

[0019] The primary amine is one of dodecyl primary amine, tetradecyl primary amine, hexadecyl primary amine and octadecyl primary amine.

[0020] The second technical solution of the present invention is achieved by the following measures: a method for preparing an anti-carbon dioxide corrosion inhibitor to obtain an anti-carbon dioxide corrosion inhibitor.

[0021] The third technical solution of the present invention is achieved through the following measures: application of an anti-carbon dioxide corrosion inhibitor in corrosion protection, sterilization and scale inhibition of oil and gas wells.

[0022] In the first polymer molecule of the present invention, n imidazoline rings are adsorbed on the stainless steel pipe, thereby improving the adsorption capacity and scouring resistance of the corrosion inhibitor; the second polymer increases the adsorption of imidazoline; the modified imidazoline improves the hydrophobicity of the monocyclic imidazoline by introducing a primary amine hydrophobic group, further inhibiting the water phase from contacting the metal surface; and at the same time, a guanidine structure is introduced into the imidazoline structure, so that the product has a strong bactericidal effect; the polymer chain structure contains a carboxylic acid structure, so that the product has a strong ability to complex cations such as calcium and magnesium, and can effectively inhibit the scaling problem caused by carbon dioxide. DETAILED DESCRIPTION

[0023] The present invention is not limited by the following embodiments, and specific implementation methods can be determined according to the technical scheme of the present invention and actual conditions. Unless otherwise specified, the various chemical reagents and chemicals mentioned in the present invention are all known and commonly used chemical reagents and chemicals in the prior art.

[0024] The present invention will be further described below in conjunction with embodiments: Example 1: The preparation method of the anti-carbon dioxide corrosion inhibitor is carried out according to the following method: The required amount of the first polymer, the second polymer and the modified imidazoline are mixed and compounded to obtain a carbon dioxide corrosion inhibitor, wherein the first polymer is a comb-shaped imidazoline, the second polymer is a linear structure imidazoline, and the modified imidazoline is a primary amine modified imidazoline.

[0025] The anti-carbon dioxide corrosion inhibitor of the present invention adopts macromolecular petroleum acid to prepare an imidazoline corrosion inhibitor intermediate. Due to the strong hydrophobicity of the macromolecular petroleum acid, the corrosion inhibition effect of the imidazoline corrosion inhibitor is significantly better than that of the oleic acid imidazoline corrosion inhibitor. The anti-carbon dioxide corrosion inhibitor also forms a comb-shaped structure through polymerization, and n imidazoline rings in the polymer molecule are adsorbed on the stainless steel pipe, which greatly improves the adsorption capacity of the imidazoline corrosion inhibitor and improves the erosion resistance of the product. At the same time, a guanidine structure is introduced into the imidazoline structure, so that the final product has a strong bactericidal effect. The polymer chain structure of the obtained anti-carbon dioxide corrosion inhibitor contains a large amount of carboxylic acid (sodium) structure, so that it has a strong ability to complex cations such as calcium and magnesium.

[0026] Example 2: As an optimization of the above example, the first polymer is obtained according to the following method: S1, mixing the required amount of macromolecular petroleum acid and polyamine uniformly and reacting them to obtain intermediate 1; S2, mixing the intermediate 1 and a required amount of guanidine hydrochloride uniformly and reacting them to obtain the intermediate 2; S3, adding a solvent and a chain transfer agent to a required amount of monomer, and then adding a required amount of initiator to react to obtain an intermediate three; S4, uniformly mixing the intermediate 2, the intermediate 3 and a required amount of polyetheramine and reacting them to obtain a first polymer.

[0027] The chemical reaction mechanism to obtain intermediate 1 is as follows: The value range of k is 2 to 10.

[0028] The chemical reaction mechanism to obtain intermediate 2 is as follows: The value range of k is 2 to 10.

[0029] The chemical reaction mechanism to obtain intermediate 3 is as follows: The chemical reaction mechanism for obtaining the first polymer is as follows: The values ​​of a, b, c and k are all in the range of 2 to 10.

[0030] Example 3: As an optimization of the above example, in step S1, the molar ratio of macromolecular petroleum acid to polyamine is 0.9 to 1.1:0.9 to 1.1, the reaction temperature is 250°C to 300°C, and the reaction time is 9h to 11h, wherein the polyamine is polyethylene polyamine and the macromolecular petroleum acid is a by-product of the petroleum refining process.

[0031] Example 4: As an optimization of the above example, in step S2, the molar ratio of intermediate 1 to guanidine hydrochloride is 0.9 to 1.1:0.9 to 1.1, the reaction temperature is 140°C to 150°C, and the reaction time is 2.5h to 3.5h.

[0032] Example 5: As an optimization of the above example, in step S3, the monomer is one or more of acrylic acid, maleic anhydride, and methacrylic acid, the solvent is one of methanol, ethanol, n-butanol, propylene glycol, glycerol, ethylene glycol, xylene, trimethylbenzene, dimethyl sulfoxide, and dimethylformamide, the chain transfer agent is n-dodecyl mercaptan, the initiator is one of azobisisobutyronitrile and dibenzoyl peroxide, the reaction temperature is 60°C to 120°C, and the reaction time is 3.5h to 4.5h.

[0033] Example 6: As an optimization of the above example, in step S4, the polyetheramine is one of D350 and D600, the reaction temperature is 100° C. to 150° C., and the reaction time is 3.5 h to 4.5 h.

[0034] Example 7: As an optimization of the above example, the second polymer is obtained according to the following method: S11, reacting a required amount of the intermediate 1 obtained in step S1 with a polycarboxylic acid to obtain a first reaction product; S12, mixing the chlorine-containing compound with the first reaction product and performing a cross-linking reaction to obtain a second polymer.

[0035] The chemical reaction mechanism to obtain the first reaction product is as follows: The value range of k is 2 to 10.

[0036] The chemical reaction mechanism to obtain the second polymer is as follows: The value ranges of k and d are both 2 to 10.

[0037] Example 8: As an optimization of the above example, in step S11, the polycarboxylic acid is one of adipic acid, suberic acid and oxalic acid, the molar ratio of the polycarboxylic acid to the intermediate one is 1:1 to 2, the reaction temperature is 100°C to 150°C, and the reaction time is 3.5h to 4.5h.

[0038] Example 9: As an optimization of the above example, in step S12, the chlorine-containing compound is 1,4-dichlorobenzyl, the molar ratio of the chlorine-containing compound to the first reaction product is 1:1 to 2, the reaction temperature is 70°C to 100°C, and the reaction time is 3.5h to 4.5h.

[0039] Example 10: As an optimization of the above example, the modified imidazoline is obtained according to the following method: required amounts of the intermediate 1 obtained in step S1, guanidine hydrochloride and primary amine are mixed and reacted to obtain the modified imidazoline.

[0040] The chemical reaction mechanism for obtaining modified imidazoline is as follows: The value ranges of k and d are both 2 to 10.

[0041] Example 11: As an optimization of the above example, the molar ratio of intermediate 1, guanidine hydrochloride and primary amine is 1:1:1, the reaction temperature is 145°C to 155°C, and the reaction time is 3.5h to 4.5h.

[0042] Embodiment 12: As an optimization of the above embodiment, the primary amine is one of dodecyl primary amine, tetradecyl primary amine, hexadecyl primary amine and octadecyl primary amine.

[0043] Example 13: The anti-carbon dioxide corrosion inhibitor obtained by the preparation method of the anti-carbon dioxide corrosion inhibitor.

[0044] Example 14: Application of the anti-carbon dioxide corrosion inhibitor in oil and gas well corrosion protection, sterilization and scale inhibition.

[0045] Example 15: The preparation method of the anti-carbon dioxide corrosion inhibitor is carried out according to the following steps: In the first step, 350 kg (1 kmol) of macromolecular petroleum acid (molecular weight 350) and 439 kg (1 kmol) of polyethylene polyamine (molecular weight 439) were added to the reactor, mixed evenly, and then slowly heated to 280°C, and refluxed for 10 hours to obtain intermediate 1; In the second step, the intermediate 1 is mixed evenly with 95.5 kg (1 kmol) of guanidine hydrochloride, and the temperature is controlled at 150°C for 3 hours to obtain the intermediate 2; Step 3: Take 200 kg of solvent (ethanol), add 100 kg of monomer (acrylic acid), 2 kg of chain transfer agent (n-dodecyl mercaptan), control the temperature at 80°C, add 0.4 kg of initiator (azobisisobutyronitrile) (add in 4 times, 0.1 kg / h), react for 4 hours, and remove the solvent by vacuum dehydration to obtain intermediate 3; Step 4: 884.5 kg of intermediate 2 and 302 kg of intermediate 3 were mixed evenly, 50 kg of polyetheramine (D350) was added, and the temperature was controlled at 150° C. to react for 4 hours to obtain the first polymer (comb-shaped imidazoline); Step 5: Take 789 kg of intermediate 1 and 73 kg of adipic acid (0.5 kmol), control the temperature at 150°C for 4 hours, then add 87.5 kg (0.5 kmol) of 1,4-dichlorobenzyl chloride, and react at 80°C for 4 hours to obtain a second polymer (linear structure imidazoline); Step 6: Take 789 kg of intermediate 1, 95.5 kg of guanidine hydrochloride, and 241.5 kg of hexadecyl primary amine, and react at 150° C. for 4 hours to prepare modified imidazoline; In the seventh step, the first polymer, the second polymer and the modified imidazoline are mixed in a mass ratio of 9:0.5:0.5, and stirred evenly to obtain a carbon dioxide corrosion inhibitor.

[0046] Example 16: The difference between the preparation method of the anti-carbon dioxide corrosion inhibitor and that of Example 15 is that: In the fourth step, 50 kg of polyetheramine (D350) was replaced with 50 kg of polyetheramine (D600); The rest of the process is the same.

[0047] Example 17: The preparation method of the anti-carbon dioxide corrosion inhibitor is different from that of Example 15 in that: In the third step, the monomer added is methacrylic acid; The rest of the process is the same.

[0048] Example 18: The preparation method of the anti-carbon dioxide corrosion inhibitor is different from that of Example 15 in that: In the third step, the initiator is dibenzoyl peroxide; The rest of the process is the same.

[0049] Example 19: The difference between the preparation method of the anti-carbon dioxide corrosion inhibitor and that of Example 15 is that: In the sixth step, 241.5 kg of hexadecyl primary amine was replaced with 185.3 kg of dodecyl primary amine; The rest of the process is the same.

[0050] Example 20: The difference between the preparation method of the anti-carbon dioxide corrosion inhibitor and that of Example 15 is that: In the fifth step, 73 kg of adipic acid was replaced with 87 kg of suberic acid; The rest of the process is the same.

[0051] The performance test and evaluation of the anti-carbon dioxide corrosion inhibitor obtained according to Examples 15 to 20: (1) Evaluation of bactericidal performance According to SY / T5890 "Bactericide Performance Evaluation Method", the extinction dilution method was used to determine the bactericidal effect of the anti-carbon dioxide corrosion inhibitor on sulfate-reducing bacteria, iron bacteria and saprophytic bacteria. The dosing concentration of the anti-carbon dioxide corrosion inhibitor of the present invention was 1%.

[0052] Comparative Example 1: Using a monoguanidine fungicide.

[0053] Comparative Example 2: A composite agent of oleic acid imidazoline, polyacrylic acid and monoguanidine was used as a fungicide.

[0054] (Bacteria test bottle SRB (sulfate reducing bacteria) readings, IB (iron bacteria) readings, TGB (saprophytic bacteria) readings) The experimental results are shown in Table 1.

[0055] Table 1 .

[0056] It can be seen from Table 1 that the bactericidal performance of the anti-carbon dioxide corrosion inhibitor of the present invention is slightly better than that of the monoguanidine bactericide on the market, but is significantly better than the composite agent containing monoguanidine. The reason is that when multiple agents in the composite agent containing monoguanidine are compounded, there is incompatibility between the agents, resulting in poor performance.

[0057] (2) Corrosion inhibition experiment Referring to the SYT5273 standard for the performance evaluation method of corrosion inhibitors for oilfield produced water reinjection water, six 1L stoppered bottles were taken, and oilfield water source well water and 1% anti-carbon dioxide corrosion inhibitor (Examples 15 to 20) were added to make the volume 1L, and the prepared N80 hanging plate (with an outer size of 40mm×13mm×2mm, a round hole was drilled in the middle of one end 5mm away from the edge, and the surface area was 12cm 2 ), CO2 and H2S were introduced to saturation to simulate the working conditions in acidic oil and gas wells. The samples were placed in a constant temperature oven at 90°C for 14 days, and the coupons were taken out. After cleaning the corrosion products on the surface of the coupons, they were dried with cold air and weighed. The corrosion rate of the steel coupons was calculated according to formula (1). The results are shown in Table 2.

[0058] Formula (1) Among them, γ c is the corrosion rate, in mm / a; ω0 is the initial mass of the coupon, in g; ω1 is the mass of the coupon at the end of the experiment, in g; S is the surface area of ​​the coupon, in cm 2 ; t is the reaction time, in h; ρ is g / cm 3 .

[0059] Blank example: CO2 and H2S are introduced into the water source well of the oil field until it is saturated, and no anti-CO2 corrosion inhibitor is added. The remaining steps are consistent with the above steps. The results are shown in Table 2.

[0060] Comparative Example 1: using oleic acid imidazoline corrosion inhibitor.

[0061] Comparative Example 2: A composite agent of oleic acid imidazoline, polyacrylic acid and monoguanidine was used as a corrosion inhibitor.

[0062] Table 2 .

[0063] It can be seen from Table 2 that the anti-carbon dioxide corrosion inhibitor of the present invention has excellent corrosion inhibition performance, which is slightly better than or close to that of oleic acid imidazoline, but significantly better than the composite agent containing oleic acid imidazoline. The reason is that when multiple agents are compounded in the composite agent containing oleic acid imidazoline, there is incompatibility between the agents, resulting in poor performance.

[0064] (3) Scale inhibition experiment According to the SY / T5673-93 "Performance Evaluation Method of Scale Inhibitors for Oilfields" standard, the scale inhibition rate of calcium carbonate is required to be ≥90%. The experimental results are shown in Table 3.

[0065] Comparative Example 1: using polyacrylic acid scale inhibitor.

[0066] Comparative Example 2: A composite agent of oleic acid imidazoline, polyacrylic acid and monoguanidine was used as a scale inhibitor.

[0067] Table 3 .

[0068] As shown in Table 3, the scale inhibition performance of the anti-carbon dioxide corrosion inhibitor of the present invention is similar to that of the polyacrylic acid scale inhibitor, but it can meet the on-site requirements (standard requirement ≥ 90%); however, the scale inhibition performance is significantly better than the composite agent containing polypropylene, because when multiple agents in the composite agent containing polypropylene are compounded, there is incompatibility between the agents, resulting in poor performance. This agent can effectively solve the problem of incompatibility of agents.

[0069] Through corrosion, post-inhibition and sterilization tests, it can be known that the anti-carbon dioxide corrosion inhibitor of the present invention has a good corrosion inhibition effect under simulated working conditions, and the corrosion inhibition rate is lower than 0.05mm / a, which is far lower than the corresponding industry standard. The scale inhibition rate and sterilization rate meet the industry standards. It has a good protective function for the inner wall of the casing in the annular space and the outer wall of the oil and gas pipeline in the acidic environment, prolongs the service life, and ensures the safe production of the oil field.

[0070] In conclusion, the anti-carbon dioxide corrosion inhibitor of the present invention has strong adsorption and can be effectively adsorbed on the surface of the steel sheet, thereby reducing metal corrosion, and also has certain bactericidal and scale inhibition properties.

[0071] In summary, in the first polymer molecule of the present invention, n imidazoline rings are adsorbed on the stainless steel pipe, which improves the adsorption capacity and erosion resistance of the corrosion inhibitor, the second polymer increases the adsorption of imidazoline, and the modified imidazoline improves the hydrophobicity of the monocyclic imidazoline by introducing a primary amine hydrophobic group, further inhibiting the water phase from contacting the metal surface, and at the same time, a guanidine structure is introduced into the imidazoline structure, so that the product has a strong bactericidal effect, and the polymer chain structure contains a carboxylic acid structure, so that it has a strong ability to complex cations such as calcium and magnesium, and can effectively inhibit the scaling problem caused by carbon dioxide.

[0072] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.

Claims

1. A method for preparing a carbon dioxide corrosion inhibitor, characterized in that The method is as follows: required amounts of a first polymer, a second polymer and a modified imidazoline are mixed and compounded to obtain a carbon dioxide corrosion inhibitor, wherein the first polymer is a comb-shaped imidazoline, the second polymer is a linear imidazoline, and the modified imidazoline is a primary amine modified imidazoline.

2. The method for preparing the anti-carbon dioxide corrosion inhibitor according to claim 1, characterized in that The first polymer is obtained according to the following method: S1, mixing the required amount of macromolecular petroleum acid and polyamine uniformly and reacting them to obtain intermediate 1; S2, mixing the intermediate 1 and a required amount of guanidine hydrochloride uniformly and reacting them to obtain the intermediate 2; S3, adding a solvent and a chain transfer agent to a required amount of monomer, and then adding a required amount of initiator to react to obtain an intermediate three; S4, uniformly mixing the intermediate 2, the intermediate 3 and a required amount of polyetheramine and reacting them to obtain a first polymer.

3. The method for preparing the anti-carbon dioxide corrosion inhibitor according to claim 2, characterized in that In step S1, the molar ratio of macromolecular petroleum acid to polyamine is 0.9 to 1.1:0.9 to 1.1, the reaction temperature is 250°C to 300°C, and the reaction time is 9h to 11h, wherein the polyamine is polyethylene polyamine and the macromolecular petroleum acid is a by-product in the petroleum refining process; or / and, in step S2, the molar ratio of intermediate 1 to guanidine hydrochloride is 0.9 to 1.1:0.9 to 1.1, the reaction temperature is 140°C to 150°C, and the reaction time is 2.5h to 3.5h; or / and, in step S3, the monomers are acrylic acid, maleic anhydride , methacrylic acid, the solvent is one of methanol, ethanol, n-butanol, propylene glycol, glycerol, ethylene glycol, xylene, trimethylbenzene, dimethyl sulfoxide, and dimethylformamide, the chain transfer agent is n-dodecyl mercaptan, the initiator is one of azobisisobutyronitrile and dibenzoyl peroxide, the reaction temperature is 60°C to 120°C, and the reaction time is 3.5h to 4.5h; or / and, in step S4, the polyetheramine is one of D350 and D600, the reaction temperature is 100°C to 150°C, and the reaction time is 3.5h to 4.5h.

4. The method for preparing the anti-carbon dioxide corrosion inhibitor according to claim 2 or 3, characterized in that The second polymer is obtained as follows: S11, reacting a required amount of the intermediate 1 obtained in step S1 with a polycarboxylic acid to obtain a first reaction product; S12, mixing the chlorine-containing compound with the first reaction product and performing a cross-linking reaction to obtain a second polymer.

5. The method for preparing the anti-carbon dioxide corrosion inhibitor according to claim 4, characterized in that In step S11, the polycarboxylic acid is one of adipic acid, suberic acid and oxalic acid, the molar ratio of the polycarboxylic acid to the intermediate one is 1:1 to 2, the reaction temperature is 100°C to 150°C, and the reaction time is 3.5h to 4.5h; or / and, in step S12, the chlorine-containing compound is 1,4-dichlorobenzyl, the molar ratio of the chlorine-containing compound to the first reaction product is 1:1 to 2, the reaction temperature is 70°C to 100°C, and the reaction time is 3.5h to 4.5h.

6. The method for preparing the anti-carbon dioxide corrosion inhibitor according to claim 2, 3 or 5, characterized in that The modified imidazoline is obtained by the following method: required amounts of the intermediate 1 obtained in step S1, guanidine hydrochloride and a primary amine are mixed and reacted to obtain the modified imidazoline.

7. The method for preparing the anti-carbon dioxide corrosion inhibitor according to claim 6, characterized in that The molar ratio of intermediate 1, guanidine hydrochloride and primary amine is 1:1:1, the reaction temperature is 145° C. to 155° C., and the reaction time is 3.5 h to 4.5 h.

8. The method for preparing the anti-carbon dioxide corrosion inhibitor according to claim 7, characterized in that The primary amine is one of dodecyl primary amine, tetradecyl primary amine, hexadecyl primary amine and octadecyl primary amine.

9. An anti-carbon dioxide corrosion inhibitor obtained according to the preparation method according to any one of claims 1 to 8.

10. Use of the anti-carbon dioxide corrosion inhibitor according to claim 9 in corrosion protection, sterilization and scale inhibition of oil and gas wells.

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