Corrosion inhibitor for oilfield produced water

Abstract

The invention discloses a corrosion inhibitor for oilfield produced water, and relates to the technical field of petrochemical engineering, the corrosion inhibitor is composed of a corrosion inhibitor main body and an auxiliary agent, the corrosion inhibitor main body is at least one of a compound 1 and a compound 2, the compound 1 is 2, 6-bis (1-phenyl-2-p-methylphenylethylamino)-3-cyano-4-methylpyridine, the compound 2 is 2, 6-bis (1-phenyl-2-p-methylphenylethylamino)-3-cyano-4-methylpyridine, and the auxiliary agent is 2, 6-bis (1-phenyl-2-p-methylphenylethylamino)-3-cyano-4-methylpyridine. The compound 2 is 2-chloro-3-cyano-4-methyl-6-(alpha, alpha-dimethyl benzylamino) pyridine, and the compound 2 is 2-chloro-3-cyano-4-methyl-6-(alpha, alpha-dimethyl benzylamino) pyridine. The corrosion inhibitor disclosed by the invention comprises the main components of two aminopyridine compounds, the electron density of molecules is effectively improved by N atoms in the molecular structure and electron donating groups connected to pyridine rings, and the corrosion inhibitor can be firmly adsorbed on the metal surface to form a compact protective film. In addition, hydrophobic groups are introduced into molecules, and the close arrangement of the molecules of the hydrophobic layer is realized by accurately regulating and controlling the ratio of the two compounds. The corrosion inhibitor prepared by taking the compound combination as a main body shows a stable corrosion resistance effect under high-temperature and high-salt conditions, and is particularly suitable for treating oilfield produced water.

Description

Technical Field

[0001] The present invention relates to the technical field of petrochemical industry, and in particular to a corrosion inhibitor for oilfield produced water. Background Art

[0002] Metal corrosion is a widespread problem worldwide, which poses a serious threat to production safety, economic development and environmental protection. This problem is particularly prominent in energy fields such as crude oil and natural gas extraction. Metal corrosion not only leads to the decline of equipment performance and shortened service life, but also may cause serious safety accidents, bringing huge risks to people's lives and property safety. According to authoritative data provided by the International Association of Corrosion Engineers, the annual global losses caused by metal corrosion are as high as 2.5 trillion US dollars, which is equivalent to 3.5% of the total global GDP, fully demonstrating the severity and urgency of the metal corrosion problem.

[0003] In the process of crude oil and natural gas extraction, metal corrosion is particularly serious. Due to the complex and changeable mining environment, metal equipment is often exposed to harsh conditions such as high temperature, high pressure, high humidity and corrosive media (such as hydrogen sulfide, carbon dioxide, salts, etc.), which greatly accelerate the corrosion process of metals. Corrosion not only causes pipeline leakage and equipment damage, but also affects the quality and output of crude oil and natural gas, thereby increasing production costs and reducing economic benefits.

[0004] In order to deal with the problem of metal corrosion, anti-corrosion paints, anti-corrosion coatings and electroplating are relatively common anti-corrosion measures in the prior art. However, although these anti-corrosion methods can alleviate the corrosion problem to a certain extent, they cannot completely solve the losses caused by corrosion. As a new type of anti-corrosion method, corrosion inhibitors have attracted much attention due to their advantages such as small dosage, good effect and easy use. Corrosion inhibitors can be adsorbed on the metal surface through physical or chemical effects to form a protective film, or slow down or inhibit the corrosion process of the metal by changing the properties of the corrosive medium.

[0005] In the process of oil extraction, water extraction equipment often needs to operate in an extremely high temperature and high salt environment, which poses a severe challenge to metal equipment and easily causes corrosion problems. In order to protect metal equipment from corrosion, extend its service life, and improve the extraction efficiency and quality of crude oil and natural gas, more stringent requirements are placed on oilfield produced water corrosion inhibitors. These corrosion inhibitors not only need to ensure excellent corrosion inhibition effects, but also need to have excellent high temperature and salt resistance. Summary of the invention

[0006] In view of the technical problems existing in the prior art, the present invention provides a corrosion inhibitor for oilfield produced water, the corrosion inhibitor comprising a corrosion inhibitor main body and an auxiliary agent, the corrosion inhibitor main body is at least one of compound 1 and compound 2;

[0007]

[0008] The compound 1 has a structure of formula I;

[0009]

[0010] The compound 2 has the structure of formula II.

[0011] Furthermore, the mass ratio of the compound 1 to the compound 2 in the corrosion inhibitor body is 1 to 3:1.

[0012] Furthermore, the additives include a synergist, a co-solvent and water, and the contents of the corrosion inhibitor body, the synergist, the co-solvent and water are, by mass: 15 to 35 parts, 10 to 20 parts, 5 to 10 parts and 35 to 70 parts.

[0013] Furthermore, the synergist is one of polyethylene glycol 100, polyethylene glycol 300, a combination of ethylene glycol 100 and thiourea, and a combination of ethylene glycol 300 and thiourea.

[0014] Furthermore, the co-solvent is at least one of dodecyl dimethyl benzyl ammonium chloride and ceteareth-10.

[0015] Furthermore, the synthesis method of compound 1 is:

[0016]

[0017] 1-phenyl-2-p-methylphenylethylamine and 2,6-dichloro-3-cyano-4-methylpyridine were mixed, ZnCl2 was added, the temperature was raised to 170-220°C after stirring and nitrogen replacement, the reaction was continued for 4-8 hours, the temperature was lowered to 50-60°C, an organic solvent and water were added, the mixture was stirred, and the mixture was allowed to stand for separation, the organic phase was washed with alkali, the organic phase was placed in an ice water bath after separation, the temperature was lowered to 0°C, and the mixture was stirred for crystallization for 2-4 hours, filtered, the filter cake was washed with a small amount of organic solvent, and compound 1 was obtained after drying.

[0018] Furthermore, the molar ratio of the 1-phenyl-2-p-methylphenylethylamine to the 2,6-dichloro-3-cyano-4-methylpyridine is 5 to 8:1.

[0019] Furthermore, the synthesis method of compound 2 is:

[0020]

[0021] After mixing α,α-dimethylbenzylamine and 2,6-dichloro-3-cyano-4-methylpyridine, cuprous chloride was added, stirred and replaced with nitrogen, and then the temperature was raised to the reflux temperature of 130-140°C. After reacting for 4-8 hours, the temperature was lowered to 50-60°C, an organic solvent and water were added, stirred, and allowed to stand for separation. The upper organic phase was taken for alkali washing. After separation, the organic phase was placed in an ice water bath, cooled to 0°C, stirred for crystallization for 2-4 hours, filtered, and the filter cake was washed with a small amount of organic solvent and dried to obtain compound 2.

[0022] Furthermore, the molar ratio of α,α-dimethylbenzylamine to 2,6-dichloro-3-cyano-4-methylpyridine is 5 to 8:1.

[0023] Furthermore, the organic solvent is toluene, the ratio of toluene to water is 2:1, and the alkali solution used for alkali washing is 1% sodium bicarbonate solution.

[0024] In summary, the present invention has the following beneficial effects:

[0025] 1. The main components of the corrosion inhibitor disclosed in the present invention are two aminopyridine compounds. Through the N atom in its molecular structure and the electron-donating group connected to the pyridine ring, the electron density of the molecule is effectively increased, so that it can be firmly adsorbed on the metal surface to form a dense protective film. In addition, the hydrophobic groups such as the benzene ring and tert-butyl introduced into the molecule achieve a close arrangement of the hydrophobic layer molecules by precisely controlling the ratio of the two compounds, thereby significantly improving the anti-corrosion effect. It exhibits high-efficiency and low-dosage anti-corrosion performance, and is particularly suitable for oilfield produced water treatment. .

[0026] Second, the corrosion inhibitor provided by the present invention can maintain stable chemical properties and protective effects under high temperature conditions, and can also play an excellent anti-corrosion role in a water environment with high salt concentration. This feature not only effectively extends the service life of oilfield equipment, but also significantly reduces the maintenance cost and potential safety hazards caused by corrosion, providing a strong guarantee for the safe production and efficient operation of oilfields. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0028] Figure 1 It is the nuclear magnetic resonance spectrum of compound 1 disclosed in the present invention.

[0029] Figure 2It is the nuclear magnetic resonance spectrum of compound 2 disclosed in the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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.

[0031] The present invention provides a corrosion inhibitor for oilfield produced water, the corrosion inhibitor comprising a corrosion inhibitor main body and an auxiliary agent, the corrosion inhibitor main body is at least one of compound 1 and compound 2; the compound 1 is 2,6-di(1-phenyl-2-p-methylphenylethylamino)-3-cyano-4-methylpyridine, the compound 2 is 2-chloro-3-cyano-4-methyl-6-(α,α-dimethylbenzylamino)pyridine;

[0032]

[0033] The compound 1 has a structure of formula I;

[0034]

[0035] The compound 2 has the structure of formula II.

[0036] Furthermore, the mass ratio of the compound 1 to the compound 2 in the corrosion inhibitor body is 1 to 3:1.

[0037] Furthermore, the auxiliary agent includes a synergist, a co-solvent and water, and the contents of the synergist, the co-solvent and water are, by mass: 15 to 35 parts, 10 to 20 parts, 5 to 10 parts and 35 to 70 parts.

[0038] Furthermore, the synergist is one of polyethylene glycol 100, polyethylene glycol 300, a combination of ethylene glycol 100 and thiourea, and a combination of ethylene glycol 300 and thiourea.

[0039] Furthermore, the co-solvent is at least one of dodecyl dimethyl benzyl ammonium chloride and ceteareth-10.

[0040] Furthermore, the synthesis method of compound 1 is:

[0041] 1-phenyl-2-p-methylphenylethylamine and 2,6-dichloro-3-cyano-4-methylpyridine were mixed, ZnCl2 was added, the temperature was raised to 170-220°C after stirring and nitrogen replacement, the reaction was continued for 4-8 hours, the temperature was lowered to 50-60°C, an organic solvent and water were added, the mixture was stirred, and the mixture was allowed to stand for separation, the organic phase was washed with alkali, the organic phase was placed in an ice water bath after separation, the temperature was lowered to 0°C, and the mixture was stirred for crystallization for 2-4 hours, filtered, the filter cake was washed with a small amount of organic solvent, and compound 1 was obtained after drying.

[0042]

[0043] Furthermore, the molar ratio of the 1-phenyl-2-p-methylphenylethylamine to the 2,6-dichloro-3-cyano-4-methylpyridine is 5 to 8:1.

[0044] Furthermore, the synthesis method of compound 2 is:

[0045]

[0046] After mixing α,α-dimethylbenzylamine and 2,6-dichloro-3-cyano-4-methylpyridine, cuprous chloride was added, stirred and replaced with nitrogen, and then the temperature was raised to a reflux temperature of about 130-140°C. After reacting for 4-8 hours, the temperature was lowered to 50-60°C, an organic solvent and water were added, stirred, and allowed to stand for separation. The upper organic phase was taken for alkali washing. After separation, the organic phase was placed in an ice water bath, cooled to 0°C, stirred for crystallization for 2-4 hours, filtered, and the filter cake was washed with a small amount of organic solvent and dried to obtain compound 2.

[0047] Furthermore, the molar ratio of α,α-dimethylbenzylamine to 2,6-dichloro-3-cyano-4-methylpyridine is 5 to 8:1.

[0048] The corrosion inhibitor for oilfield produced water according to claim 6 or 8, characterized in that the organic solvent is toluene, the ratio of toluene to water is 2:1, and the alkali solution used for alkali washing is 1% sodium bicarbonate solution

[0049] The present invention provides two aminopyridine compounds, which contain N atoms in their molecular structure, and electron-donating groups are connected to the pyridine ring, which increase the electron density of the molecule, so that the compound can be adsorbed on the metal surface, thereby forming a protective film. In addition, the molecular structure of these compounds also has hydrophobic groups such as a benzene ring and a tert-butyl group. By adjusting the ratio of the two compounds, the hydrophobic layer molecules can be closely arranged, more effectively covered on metal equipment, and play an anti-corrosion role.

[0050] Example 1

[0051] Preparation of compound 1

[0052] 31.7 g (0.15 mol) of 1-phenyl-2-p-methylphenylethylamine and 5.61 g (0.03 mol) of 2,6-dichloro-3-cyano-4-methylpyridine were added to a 100 mL four-necked bottle, 0.5 g of ZnCl2 was added, stirring was started, and the temperature was raised to 170°C after nitrogen substitution. After reacting for 4 hours, the temperature was lowered to 50°C, 20 mL of toluene and 10 mL of water were added, stirred for 10 minutes, and then allowed to stand for separation. The upper organic phase was washed with 1% sodium carbonate aqueous solution. After separation, the organic phase was transferred to a 250 mL flask, placed in an ice water bath, cooled to 0°C, stirred for crystallization for 2 hours, filtered, the filter cake was washed with a small amount of toluene, and dried to obtain compound 1.

[0053] Example 2

[0054] Preparation of compound 2:

[0055] 10.84 g (0.08 mol) of α,α-dimethylbenzylamine and 3 g (0.016 mol) of 2,6-dichloro-3-cyano-4-methylpyridine were added to a 100 mL four-necked bottle, 0.3 g of cuprous chloride was added, stirring was started, and the temperature was raised to about 130°C for reflux after nitrogen replacement. After reacting for 4 hours, the temperature was lowered to 50°C, 20 mL of toluene and 10 mL of water were added, stirred for 10 minutes, and then allowed to stand for separation. The upper organic phase was washed with 1% sodium carbonate aqueous solution. After separation, the organic phase was transferred to a 250 mL flask, placed in an ice water bath, cooled to 0°C, stirred for crystallization for 2 hours, filtered, the filter cake was washed with a small amount of toluene, and dried to obtain compound 2.

[0056] Example 3

[0057] This embodiment provides a high temperature resistant corrosion inhibitor, including a corrosion inhibitor body, polyethylene glycol 300, cetearyl alcohol polyether-10 and water, with a mass ratio of 15:10:5:70. The corrosion inhibitor body is composed of compound 1 prepared in Example 1 and compound 2 prepared in Example 2, and the mass ratio of the two is 1:1.

[0058] Example 4

[0059] This embodiment provides a high temperature resistant corrosion inhibitor, including a corrosion inhibitor body, polyethylene glycol 100, dodecyl dimethyl benzyl ammonium chloride and water, with a mass ratio of 30:20:5:45. The corrosion inhibitor body is composed of compound 1 prepared in Example 1 and compound 2 prepared in Example 2, and the mass ratio of the two is 3:1.

[0060] Example 5

[0061] The present embodiment provides a high temperature resistant corrosion inhibitor, comprising a corrosion inhibitor body, a composition of polyethylene glycol 100 and thiourea, a composition of dodecyl dimethyl benzyl ammonium chloride and cetearyl alcohol polyether-10, and water, with a mass ratio of 35:15:10:40; the corrosion inhibitor body is composed of compound 1 prepared in Example 1 and compound 2 prepared in Example 2, and the mass ratio of the two is 2:1; the mass ratio of the two in the polyethylene glycol 100 and thiourea composition is 2:1; the mass ratio of the two in the dodecyl dimethyl benzyl ammonium chloride and cetearyl alcohol polyether-10 composition is 2:1.

[0062] Example 6

[0063] The present embodiment provides a high temperature resistant corrosion inhibitor, comprising a corrosion inhibitor main body, polyethylene glycol 100, dodecyl dimethyl benzyl ammonium chloride and water, with a mass ratio of 30:20:5:45.

[0064] The main body of the corrosion inhibitor is compound 1 obtained in Example 1.

[0065] Example 7

[0066] This embodiment provides a high temperature resistant corrosion inhibitor, comprising a corrosion inhibitor main body, polyethylene glycol 100, cetearyl alcohol polyether-10 and water, with a mass ratio of 30:20:5:45, and the corrosion inhibitor main body is compound 2 prepared in embodiment 2. .

[0067] Comparative Example 1

[0068] This comparative example is a control group, in which the corrosion inhibitor provided does not include the corrosion inhibitor main body, but only includes auxiliary agents such as polyethylene glycol 100, dodecyl dimethyl benzyl ammonium chloride and water, and the mass ratio is 20:5:75.

[0069] Comparative Example 2

[0070] This comparative example is a blank control group, and the test sample provided consists only of water.

[0071] The experimental conditions of the embodiment and the comparative example are shown in Table 1:

[0072] Table 1 List of test conditions for embodiments and comparative examples

[0073]

[0074] Test Case

[0075] This test example tests the performance of the corrosion inhibitors prepared in various embodiments and comparative examples under different temperature and salinity conditions.

[0076] The physical and chemical performance indicators of the corrosion inhibitor of the present invention are measured with reference to the petroleum and natural gas industry standard "SY / T5273-2014 Performance indicators and evaluation methods of corrosion inhibitors for oilfield produced water treatment". In particular, the static uniform corrosion inhibition rate and static uniform corrosion rate of the corrosion inhibitors prepared in Examples 3 to 7 and the comparative examples are comprehensively tested and evaluated.

[0077] (1) Determination of corrosion inhibitor performance under normal conditions:

[0078] Test piece preparation: Use a vernier caliper to measure the size of the test piece of the oilfield produced water equipment material, with an accuracy of 0.02mm, calculate the test piece area, and weigh the mass of the clean test piece.

[0079] Preparation of salt-containing mineralized water (1L): NaHCO3=0.95g, NaSO4=0.86g, MgCl2=10.5g, CaCl2=7.45g, pH 4.5. This mineralized water is used to simulate oil field produced water with a mineralization of 20,000.

[0080] Test process: Add the prepared corrosion inhibitor solution into the test container with a pipette according to the designed mass concentration value. The amount of corrosion inhibitor prepared in all embodiments and comparative examples is 30ppm. Hang two test pieces in each experimental container. The test pieces are not allowed to contact the container wall. The distance between the test pieces should be more than 1cm, and the upper end of the test piece should be more than 3cm from the liquid surface. Put the test device in a constant temperature box and keep it at a constant temperature of 60℃ for 7 days. Take out the test pieces that have reached the test cycle, observe, immediately rinse with clean water and wipe dry with filter paper.

[0081] Place the test piece in a vessel containing petroleum ether with a boiling range of 60-90℃, remove the oil stains on the surface of the test piece with absorbent cotton, take out the test piece and soak it in the acid cleaning solution for 5 minutes, and gently wipe the corrosion products on the surface of the test piece with absorbent cotton; take out the test piece from the cleaning solution, rinse the residual acid on the surface with tap water, and then dehydrate it in anhydrous ethanol. Take out the test piece and place it on filter paper, blow it dry with cold air, then wrap the test piece with filter paper, place it in a desiccator, and weigh it after 1 hour, with an accuracy of 0.1mg.

[0082] Performance index parameter calculation formula:

[0083] Static uniform corrosion inhibition rate:

[0084]

[0085] η: Uniform corrosion inhibition rate, expressed as a percentage;

[0086] Δm0: mass loss of the test piece in the blank test (sample of comparative example 2), in grams (g);

[0087] Δm1: mass loss of the test piece in the test group, in grams (g);

[0088] Static uniform corrosion rate:

[0089]

[0090] r c : static uniform corrosion rate, in millimeters per year (mm / a);

[0091] m: the mass of the test piece before the test, in grams (g);

[0092] m1: the mass of the test piece after the test, in grams (g);

[0093] S: The total area of ​​the test piece, in square centimeters (cm 2 );

[0094] ρ: Density of the test piece material, in grams per cubic centimeter (g / cm 3 );

[0095] t: test time, in hours (h).

[0096] (2) Corrosion inhibitor performance test under high salt conditions

[0097] In this test, conventional saline mineralized water was replaced with high-salt mineralized water (1L): NaHCO3 = 0.95g, NaSO4 = 0.86g, NaCl = 120g, MgCl2 = 10.5g, CaCl2 = 7.45g, pH 4.5. The mineralization of this simulated water reaches 140,000, which is 7 times the mineralization of conventional saline mineralized water. The rest of the test methods are the same as conventional conditions.

[0098] Under this condition, the static uniform corrosion inhibition rate parameters of the corrosion inhibitors prepared in Examples 3 to 7 and the comparative example were measured.

[0099] (3) Corrosion inhibitor performance test under high temperature and high salt conditions

[0100] In this test, the salinity (mineralization) of the saline mineralized water simulating oilfield produced water was greatly increased, and the temperature conditions were further improved, and the ambient temperature of the test device placed in the constant temperature box was adjusted from 60°C to 90°C. The rest of the test methods are the same as the normal conditions.

[0101] Under this condition, the static uniform corrosion inhibition rate parameters of the corrosion inhibitors prepared in Examples 3 to 7 and the comparative example were measured.

[0102] Tests, results and analysis

[0103] (1) Successful preparation of compounds 1 and 2

[0104] The content of compound 1 prepared in Example 1 is 97% and the yield is 65%. Figure 1 As shown, the NMR results: 1 H NMR(400MHz, CDCl3)δ8.942(s,5H),7.347-7.328(m,4H),7.263-7.241(m,7H),6.948(d,4H) ,6.833(d,4H),4.368-4.332(m,2H),3.45-3.405(m,2H),3.175-3.116(m,2H),2.238(s,6H).

[0105] The content of compound 2 prepared in Example 2 is 98% and the yield is 55%. Figure 2 As shown, the NMR results: 1 H NMR (400MHz, CDCl3) δ7.41-7.332(m,4H),7.297-7.289(m,1H),5.724(s,1H),5.567(s,1H),2.166(s,3H),1.699-1.581(d,6H).

[0106] (2) Performance results of the corrosion inhibitors prepared in various examples and comparative examples under different temperature and salinity conditions

[0107] According to the method provided by the petroleum and natural gas industry standard "SY / T 5273-2014 Performance Indicators and Evaluation Methods of Corrosion Inhibitors for Oilfield Produced Water Treatment", the performance indicators of the corrosion inhibitor were comprehensively measured. The corrosion inhibitor prepared in Example 37 has good water solubility, no emulsification tendency, is uniform and stable liquid as a whole, has good compatibility, no flocculation or precipitation, has a pH value between 5 and 9, and a flash point greater than 60°C. These basic parameters all meet the performance requirements specified by the industry.

[0108] At the same time, the static uniform corrosion inhibition rate (30 mg / L) of the corrosion inhibitor for oilfield produced water must reach the requirement of 70%. The static uniform corrosion inhibition rate test results of the corrosion inhibitor provided by the present invention under different environmental conditions are shown in Table 2:

[0109] Table 2 Test results of static uniform corrosion inhibition rate of examples and comparative examples

[0110]

[0111] As shown in Table 2, under the normal conditions specified by the industry standards, the corrosion inhibitors of Examples 3 to 7 can achieve a static uniform corrosion inhibition rate of more than 70%. Specifically, the corrosion inhibition rates of Examples 6 and 7 using Compound 1 and Compound 2 alone are between 70% and 80%, while Examples 3 to 5 using the two in combination perform even better, all reaching more than 80%. Among them, Example 5, in which the mass ratio of Compound 1 to Compound 2 is 2:1, has a corrosion inhibition rate of nearly 90%, which is the best performance. Comparative Example 1, to which Compound 1 or Compound 2 is not added, also shows a certain corrosion inhibition effect due to the presence of a synergist, but the overall effect fails to meet the standard requirement of 70%.

[0112] Furthermore, under high salt and high temperature and high salt conditions, the corrosion inhibition rate data of Examples 6 and 7 did not fluctuate or change greatly. The combined Examples 3 to 5 of the two showed only a small decrease as a whole, but were still able to maintain a high level of corrosion inhibition of more than 80%. Despite the presence of the synergist, the corrosion inhibition level of Comparative Example 1 under high temperature and high salt conditions dropped significantly. The test results show that the main corrosion inhibitor (Compound 1 and Compound 2) plays a major role in corrosion inhibition in the corrosion inhibitor, and the composite ratio of the two ensures the performance stability of the corrosion inhibitor. Not only can it meet the standard requirement of 70% under normal conditions, but Example 5 also reaches a high level of 89%. A stable corrosion inhibition effect can also be achieved under more severe high temperature and high salt simulation conditions.

[0113] On the basis of meeting the industry standards, the examples also examine the static uniform corrosion rate test results of the examples and comparative examples under different environmental conditions, as shown in Table 3:

[0114] Table 3 Static uniform corrosion efficiency test results of examples and comparative examples

[0115]

[0116] The national standard "GB / T 23258-2020 Specification for Internal Corrosion Control of Steel Pipelines" proposed by the National Technical Committee for Standardization of Petroleum and Natural Gas stipulates the requirements for the internal corrosion evaluation indexes of steel pipelines that transport oil, natural gas, water and other media in petroleum and natural gas production. Among them, the average corrosion rate (mm / a) (the determination method of this index in the national standard refers to the uniform corrosion rate of the industry standard SY / T5273-2014) is divided into four levels: low corrosion rate <0.025; medium corrosion rate 0.0250.12; heavy corrosion rate 0.130.25; severe corrosion rate >0.25.

[0117] As can be seen from Table 3, under conventional test conditions, compared with the more serious corrosion rate level of Comparative Example 2 where the blank control group is located, the static uniform corrosion rates of Examples 3 to 5 prepared by compound 1 and compound 2 of the present invention are all below 0.025 mm / year, reaching the optimal level. In particular, Example 5 achieved an excellent level of 0.0165 under the condition that the mass ratio of Compound 1 to Compound 2 is 2:1. Under high-salt conditions and high-temperature and high-salt simulated environments, the corrosion inhibition effect of each embodiment declined due to harsh environmental conditions and failed to reach the optimal level, but overall its performance was in the first half of the second level, which was very close to the standard dividing line data of the first two levels.

[0118] In summary, the main components of the corrosion inhibitor disclosed in the present invention are two aminopyridine compounds. Due to its unique structure, it can show good anti-corrosion performance when used alone. The corrosion inhibitor prepared with the combination of these two compounds as the main body maintains stable chemical properties and protective effects under high temperature conditions, and can also play an excellent anti-corrosion role in a water environment with high salt concentration. This feature not only effectively extends the service life of oilfield equipment, but also significantly reduces the maintenance cost and potential safety hazards caused by corrosion, providing a strong guarantee for the safe production and efficient operation of oilfields.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A corrosion inhibitor for oilfield produced water, characterized in that: The corrosion inhibitor is composed of a corrosion inhibitor main body and an auxiliary agent, and the corrosion inhibitor main body is at least one of compound 1 and compound 2; The compound 1 has a structure of formula I; The compound 2 has the structure of formula II.

2. The corrosion inhibitor for oilfield produced water according to claim 1, characterized in that: The mass ratio of the compound 1 to the compound 2 in the corrosion inhibitor body is 1 to 3:

1.

3. The corrosion inhibitor for oilfield produced water according to claim 1, characterized in that: The auxiliary agent includes a synergist, a co-solvent and water. The contents of the corrosion inhibitor body, the synergist, the co-solvent and water are, by mass, 15 to 35 parts, 10 to 20 parts, 5 to 10 parts and 35 to 70 parts.

4. The corrosion inhibitor for oilfield produced water according to claim 3, characterized in that: The synergist is one of polyethylene glycol 100, polyethylene glycol 300, a combination of ethylene glycol 100 and thiourea, and a combination of ethylene glycol 300 and thiourea.

5. The corrosion inhibitor for oilfield produced water according to claim 3, characterized in that: The co-solvent is at least one of dodecyl dimethyl benzyl ammonium chloride and ceteareth-10.

6. The corrosion inhibitor for oilfield produced water according to claim 1, characterized in that: The synthesis method of compound 1 is: 1-phenyl-2-p-methylphenylethylamine and 2,6-dichloro-3-cyano-4-methylpyridine were mixed, ZnCl2 was added, the temperature was raised to 170-220°C after stirring and nitrogen replacement, the reaction was continued for 4-8 hours, the temperature was lowered to 50-60°C, an organic solvent and water were added, the mixture was stirred, and the mixture was allowed to stand for separation, the organic phase was washed with alkali, the organic phase was placed in an ice water bath after separation, the temperature was lowered to 0°C, and the mixture was stirred for 2-4 hours for crystallization, the filter cake was washed with a small amount of organic solvent after filtration, and compound 1 was obtained after drying.

7. The corrosion inhibitor for oilfield produced water according to claim 6, characterized in that: The molar ratio of the 1-phenyl-2-p-methylphenylethylamine to the 2,6-dichloro-3-cyano-4-methylpyridine is 5 to 8:

1.

8. The corrosion inhibitor for oilfield produced water according to claim 1, characterized in that: The synthesis method of compound 2 is: α,α-dimethylbenzylamine and 2,6-dichloro-3-cyano-4-methylpyridine were mixed, cuprous chloride was added, the mixture was stirred and replaced with nitrogen, the temperature was raised to the reflux temperature of 130-140°C, the reaction was carried out for 4-8 hours, the temperature was lowered to 50-60°C, an organic solvent and water were added, stirred, and the mixture was allowed to stand for separation, the upper organic phase was taken for alkali washing, the organic phase was placed in an ice water bath, cooled to 0°C, stirred for crystallization for 2-4 hours, filtered, the filter cake was washed with a small amount of organic solvent, and dried to obtain compound 2.

9. The corrosion inhibitor for oilfield produced water according to claim 8, characterized in that: The molar ratio of the α,α-dimethylbenzylamine to the 2,6-dichloro-3-cyano-4-methylpyridine is 5 to 8:

1.

10. The corrosion inhibitor for oilfield produced water according to claim 6 or 8, characterized in that: The organic solvent is toluene, the ratio of toluene to water is 2:1, and the alkali solution used for alkali washing is 1% sodium bicarbonate solution.

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