A low-hazard zwitterionic thickening acid

Abstract

The application discloses a low-damage zwitterionic thickening acid which is prepared by mixing raw materials in the following mass percentages: 0.3-1.0% of zwitterionic acid liquid thickening agent, 0.5-2.0% of acidification corrosion inhibitor, 0.2-0.9% of iron ion stabilizer, 0.3-0.8% of cleanup aid, and 20% of hydrochloric acid to 100%. The zwitterionic acid liquid thickening agent can be quickly dissolved in the acid liquid, and has good viscosity increasing and retarding properties; the zwitterionic thickening acid can resist high temperature, has good salt resistance, can inhibit the hydration expansion and migration of clay minerals, has excellent corrosion inhibition performance, and has good compatibility with various acid liquid additives, and is a low-damage thickening acid.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil and gas field exploitation, and particularly relates to a low-damage zwitterionic thickened acid. BACKGROUND

[0002] With the continuous development of low-permeability oil and gas reservoirs, acidizing technology has become an important measure for oil and gas production. Conventional acid fluid has a short action distance, a fast filtration rate, can only dissolve the rock cementing material near the wellbore, and is prone to over-acidification to form a dissolution cave, and thus cannot achieve the desired effect of acidification modification. The thickened acid technology can effectively overcome the above shortcomings, increase the viscosity of the acid fluid, effectively control the diffusion speed of hydrogen ions in the acid fluid, remove the pollution in the far-wellbore zone, communicate the oil and gas flow channels, and improve the oil and gas production. The thickening agent is the most important additive in the thickened acid, and directly affects the acidizing effect of the thickened acid. In a low-permeability high-temperature environment, the fracturing fluid prepared by using the currently mainly used biological polymer and cellulose acid fluid thickening agent is limited in practical application due to the problems of low use temperature, poor acid resistance, large formation damage, and salt sensitivity. The acidizing fluid prepared by using the conventional acrylamide synthetic polymer thickening agent overcomes the above problems, but still has the problems of solubility, poor high-temperature resistance, limited thickening capacity, and poor temperature resistance.

[0003] In order to obtain a synthetic polymer acidizing fluid with excellent performance, extensive researches on the modified acrylamide polymer acid fluid thickening agent system have been carried out at home and abroad, and the modified acrylamide synthetic polymer thickening agent system has occupied the main market of acid fluid thickening agent. At present, the most studied modified acrylamide thickening agent system is a cationic polymer system, an anionic polymer system and a zwitterionic polymer system obtained by copolymerization of acrylamide and cationic monomers or anionic monomers, and the zwitterionic acid fluid thickening agent system is favored due to its unique molecular structure and excellent high temperature resistance, salt resistance, inhibition of swelling and migration of clay minerals in the formation, etc., and the zwitterionic polymer is selected as the acid fluid thickening agent to solve the salt resistance problem of complex formation. At present, the anionic structure of the reported zwitterionic acid fluid thickening agent system uses 2-acrylamido-2-methylpropane sulfonic acid (AMPS) monomer containing sulfonic acid group, and the cationic structure mostly uses methacryloyloxyethyl trimethyl ammonium chloride (DMC) and dimethyl diallyl ammonium chloride (DMDAAC) monomers. Huang Zhongyao (Natural Gas Exploration and Development. Research on Zwitterionic Acid Fluid Thickening Agent, 2010, No. 7) reported an acid fluid thickening agent prepared by using acrylamide as the main monomer, cationic monomer dimethyl diallyl ammonium chloride (DMDAAC) and anionic monomer 2-acrylamido-2-methylpropane sulfonic acid (AMPS), and studied the acid solubility, temperature resistance, shear stability and retarding property of the acid fluid thickening agent. Ma Xiping et al. (Petroleum Chemical Industry. Synthesis and Performance Evaluation of Acid Fluid Thickening Agent, 2016, No. 12) reported that the acid fluid thickening agent (PAADN) was synthesized by using dimethyl diallyl ammonium chloride (DMDAAC), 2-methyl-2-acrylamido propane sulfonic acid (AMPS), acrylamide (AM) and N-vinyl pyrrolidone (NVP) as monomers, and the thickening performance, acid resistance, thermal stability and shear stability of the acid fluid thickening agent were investigated. Patent ZL 201010511668.4 discloses a preparation method of an acid fluid thickening agent, which is composed of methacryloyloxyethyl trimethyl ammonium chloride 25-40 parts, dimethyl diallyl ammonium chloride 8-15 parts, 2-acrylamido-2-methyl propane sulfonate 6-15 parts, methyl acrylamide 10-10 parts and water. There are still few reports on the research and application of the zwitterionic acid fluid thickening agent system in the prior art. SUMMARY

[0004] The purpose of the present application is to provide a low-damage zwitterionic thickening acid with good acid solubility, high temperature resistance, good retarding property, inhibition of hydration swelling and migration of clay minerals, and inhibition of corrosion of metal equipment in oil and gas wells.

[0005] To achieve the above object, the low-damage zwitterionic thickening acid provided by the present application is composed of raw materials in the following mass percentage: zwitterionic acid liquid thickening agent 0.3% to 1.0%, acidizing corrosion inhibitor 0.5% to 2.0%, iron ion stabilizer 0.2% to 0.9%, cleanup aid 0.3% to 0.8%, and 20% hydrochloric acid added to 100%.

[0006] Further preferably, the low-damage zwitterionic thickening acid is composed of raw materials in the following mass percentage: zwitterionic acid liquid thickening agent 0.5% to 0.8%, acidizing corrosion inhibitor 1.0% to 1.5%, iron ion stabilizer 0.4% to 0.6%, cleanup aid 0.5% to 0.7%, and 20% hydrochloric acid added to 100%.

[0007] Further preferably, the zwitterionic acid liquid thickening agent is copolymerized from N-2-hydroxypropanesulfonic acid-based-4-vinylpyridine quaternary ammonium salt, alkyl acrylate, 4-acryloyl morpholine, and 2-acrylamido-2-methylpropyl phosphonic acid, has a viscosity average molecular weight of 2 million to 12 million Dalton, and has a molecular structure as shown in the following formula:

[0008]

[0009] In the formula, R represents any one of dodecyl, hexadecyl, and octadecyl, and the molar ratio n:p:l:m = 1:0.5:4-5.5:1-3.

[0010] The preparation method of the zwitterionic acid thickening agent is as follows: N-2-hydroxypropyl sulfonic acid-4-vinyl pyridine quaternary ammonium salt, alkyl acrylate, 4-acryloyl morpholine and 2-acrylamido-2-methyl propyl phosphonic acid four monomers are added into distilled water in a molar ratio of 1:0.5:4-5.5:1-3, mixed uniformly, heated to 40-50 DEG C under nitrogen protection and stirring, an initiator is added, constant temperature stirring is carried out for 2-3 hours, and a gel-like product is obtained; the gel-like product is purified, sheared, dried at 100-120 DEG C, crushed and sieved, and the zwitterionic acid thickening agent is obtained. The alkyl acrylate is any one of dodecyl acrylate, hexadecyl acrylate and octadecyl acrylate; the total mass concentration of the four monomers added in the distilled water is 50%-65%; the initiator is a mixture of H2O2 and NaHSO3 in a molar ratio of 1:1, and the addition amount of the initiator is 0.1%-0.2% of the total mass of the four monomers; when used, the initiator is first dissolved in distilled water to prepare an initiator aqueous solution with a mass concentration of 1%-5%, and then added by dropwise addition, which is completed within 10 minutes. The preparation method of the N-2-hydroxypropyl sulfonic acid-4-vinyl pyridine quaternary ammonium salt is as follows: 4-vinyl pyridine and 3-chloro-2-hydroxypropane sulfonic acid sodium are added into distilled water in a molar ratio of 1:1.2-1.4, mixed uniformly, and then the pH of the system is adjusted to 7.5-8.5 by using a 10% sodium hydroxide aqueous solution; the system is heated to 60-80 DEG C under stirring, hydroquinone is added, the addition amount of the hydroquinone is 0.5%-1.0% of the total mass of the 4-vinyl pyridine and 3-chloro-2-hydroxypropane sulfonic acid sodium, constant temperature stirring is carried out for 2-4 hours, a viscous liquid is obtained, washed by anhydrous ethanol, and then rotary evaporated to remove excess solvent, and the N-2-hydroxypropyl sulfonic acid-4-vinyl pyridine quaternary ammonium salt is obtained.

[0011] Further preferably, the acidizing corrosion inhibitor is any one or two of long-chain alkyl quaternary ammonium salt, Mannich base, pyridine quaternary ammonium salt and quinoline quaternary ammonium salt.

[0012] Further preferably, the iron ion stabilizer is any one of disodium ethylenediaminetetraacetate, sodium citrate and sodium ethylenediaminetetramethylene phosphonate.

[0013] Further preferably, the cleanup agent is any one of dodecylamine polyoxyethylene ether, tetradecylamine polyoxyethylene ether, octadecylamine polyoxyethylene ether, lauric acid diethanolamide and coconut oil acid diethanolamide.

[0014] The preparation method of the low-damage zwitterionic thickened acid is as follows: according to the mass percentage composition, the acidizing corrosion inhibitor, the iron ion stabilizer and the cleanup agent are added into 20% hydrochloric acid, then the zwitterionic acid liquid thickening agent is added under the stirring speed of 1500-2000 r / min, after the addition, the stirring is continued for 25-35 min, and finally the standing is carried out in a water bath at 25-30 ℃ for 1.5-2 h.

[0015] Compared with the prior art, the zwitterionic thickened acid has the following beneficial effects:

[0016] (1) The zwitterionic acid liquid thickening agent can be quickly dissolved in the acid liquid, has good tackifying and retarding properties, can greatly improve the acidizing depth, and can expand the acid liquid treatment radius;

[0017] (2) The zwitterionic thickened acid has stable performance, can resist high temperature, and has good salt resistance;

[0018] (3) The zwitterionic thickened acid can inhibit the hydration and migration of clay minerals, and can reduce the formation damage, so it is a low-damage thickened acid.

[0019] (4) The zwitterionic thickened acid can inhibit the corrosion of high-concentration acid liquid to the metal equipment in the oil and gas well, and has excellent corrosion inhibition performance;

[0020] (5) The zwitterionic thickened acid has excellent compatibility of various acid liquid additives. DETAILED DESCRIPTION

[0021] The application will be further described in detail in combination with the examples, but the protection scope of the application is not limited to the examples.

[0022] The preparation method of the N-2-hydroxypropanesulfonic acid-4-vinylpyridine quaternary ammonium salt used in the following examples is as follows: 42.06 g (0.4 mol) of 4-vinylpyridine, 94.36 g (0.48 mol) of 3-chloro-2-hydroxypropanesulfonic acid sodium and 193.80 g of distilled water are added into a reactor, after being uniformly mixed, the pH of the system is adjusted to 8.2 by using 10% sodium hydroxide aqueous solution, and then the system is heated to 68 ℃ under stirring, 1.09 g of hydroquinone is added, and constant-temperature stirring is carried out for 4 hours to obtain a viscous liquid, after being washed with anhydrous ethanol for 3 times, the excess solvent is removed by rotary evaporation, and the N-2-hydroxypropanesulfonic acid-4-vinylpyridine quaternary ammonium salt is obtained.

[0023] Example 1

[0024] For example, 1 kg of zwitterionic thickened acid is prepared, which is composed of the following raw materials: 6 g of zwitterionic acid liquid thickening agent, 10 g of dodecyl dimethyl benzyl ammonium chloride, 5 g of sodium citrate, 6 g of lauric acid diethanolamide, and 973 g of 20% hydrochloric acid.

[0025] The preparation method of the zwitterionic thickening acid of the present example is as follows: 10 g of dodecyl dimethyl benzyl ammonium chloride, 5 g of sodium citrate, and 6 g of lauric acid diethanolamide are added to 973 g of 20% mass concentration hydrochloric acid, then 6 g of zwitterionic acid thickener is slowly and uniformly added under the stirring speed of 1500 r / min, after the addition is completed, the stirring is continued for 30 min, after the stirring is stopped, the mixture is placed in a water bath at 30°C for 2 h, and then the zwitterionic thickening acid is obtained.

[0026] The zwitterionic acid thickener of the present example is prepared by copolymerization of N-2-hydroxypropanesulfonic acid-4-vinylpyridine quaternary ammonium salt, octadecyl acrylate, 4-acryloyl morpholine, and 2-acrylamido-2-methylpropyl phosphonic acid in a molar ratio of 1:0.5:4:1.5, and the viscosity average molecular weight thereof is 3.07 million Dalton. The specific preparation method is as follows: 36.48 g (0.15 mol) of N-2-hydroxypropanesulfonic acid-4-vinylpyridine quaternary ammonium salt, 24.33 g (0.075 mol) of octadecyl acrylate, 84.70 g (0.60 mol) of 4-acryloyl morpholine, 46.61 g (0.225 mol) of 2-acrylamido-2-methylpropyl phosphonic acid, and 129.30 g of distilled water are added to a reactor and uniformly mixed; 0.071 g (0.0021 mol) of H2O2 and 0.219 g (0.0021 mol) of NaHSO3 are dissolved in 14 g of distilled water to obtain an initiator solution; under the protection of nitrogen, heating and stirring are started, and when the temperature of the reactor reaches 49°C, the initiator solution is started to be added dropwise, and the addition is completed within 10 min, and then the stirring is continued for 2.5 h to obtain a gel-like product; the gel-like product is washed with anhydrous ether for three times, sheared, dried at 116°C, crushed, and sieved through a 140-mesh sieve to obtain the zwitterionic acid thickener.

[0027] Example 2

[0028] For example, 1 kg of zwitterionic thickening acid is prepared from the following raw materials: 8 g of zwitterionic acid thickener, 8 g of cetyl dimethyl benzyl ammonium bromide, 7 g of ethylenediamine tetramethylene phosphonic acid sodium, 5 g of dodecyl amine polyoxyethylene ether, and 972 g of 20% mass concentration hydrochloric acid.

[0029] The preparation method of the zwitterionic thickening acid of the present example is as follows: 10 g of dodecyl dimethyl benzyl ammonium chloride, 5 g of sodium citrate, and 6 g of lauric acid diethanolamide are added to 973 g of 20% mass concentration hydrochloric acid, then 6 g of zwitterionic acid thickener is slowly and uniformly added under the stirring speed of 1500 r / min, after the addition is completed, the stirring is continued for 30 min, after the stirring is stopped, the mixture is placed in a water bath at 30°C for 2 h, and then the zwitterionic thickening acid is obtained.

[0030] The zwitterionic acid thickening agent of the present embodiment is prepared by copolymerization of N-2-hydroxypropanesulfonic acid-4-vinylpyridine quaternary ammonium salt, hexadecyl acrylate, 4-acryloyl morpholine and 2-acrylamido-2-methylpropyl phosphonic acid in a molar ratio of 1:0.5:4.5:2, and has a viscosity average molecular weight of 7.65 million Dalton. The specific preparation method is as follows: 31.62 g (0.13 mol) of N-2-hydroxypropanesulfonic acid-4-vinylpyridine quaternary ammonium salt, 19.27 g (0.065 mol) of hexadecyl acrylate, 82.58 g (0.585 mol) of 4-acryloyl morpholine, 53.86 g (0.26 mol) of 2-acrylamido-2-methylpropyl phosphonic acid and 141.5 g of distilled water are added into a reactor and uniformly mixed; 0.054 g (0.0016 mol) of H2O2 and 0.166 g (0.0016 mol) of NaHSO3 are dissolved in 12 g of distilled water to obtain an initiator solution; under nitrogen protection, heating and stirring are started, and when the temperature of the reactor reaches 45°C, the initiator solution is started to be added dropwise, and after 10 minutes, the stirring is continued for 2 hours to obtain a gel-like product; the gel-like product is washed with anhydrous ether for three times, sheared, dried at 105°C, crushed, and sieved through a 140-mesh sieve to obtain the zwitterionic acid thickening agent.

[0031] Example 3

[0032] For example, to prepare 1 kg of zwitterionic thickening acid, the following raw materials are used: 5 g of zwitterionic acid thickening agent, 4 g of 4-vinylbenzyl chlorinated quinoline, 6 g of bromotetradecyl pyridine, 9 g of disodium ethylenediaminetetraacetate, 8 g of coconut oil diethanolamide, and 968 g of 20% mass concentration hydrochloric acid.

[0033] The preparation method of the zwitterionic thickening acid of the present embodiment is as follows: 4 g of 4-vinylbenzyl chlorinated quinoline, 6 g of bromotetradecyl pyridine, 9 g of disodium ethylenediaminetetraacetate, and 8 g of coconut oil diethanolamide are added into 968 g of 20% mass concentration hydrochloric acid, and then 5 g of zwitterionic acid thickening agent is slowly and uniformly added under stirring at a speed of 1800 r / min, and after the addition is completed, the stirring is continued for 25 min, and after the stirring is stopped, the mixture is placed in a water bath at 30°C for 2 h to obtain the zwitterionic thickening acid.

[0034] The zwitterionic acid thickener of this embodiment is prepared by copolymerization of N-2-hydroxypropanesulfonic acid-4-vinylpyridine quaternary ammonium salt, dodecyl acrylate, 4-acryloyl morpholine and 2-acrylamido-2-methylpropyl phosphonic acid in a molar ratio of 1:0.5:5.5:2, and has a viscosity average molecular weight of 5.81 million Dalton. The specific preparation method is as follows: 31.62 g (0.13 mol) of N-2-hydroxypropanesulfonic acid-4-vinylpyridine quaternary ammonium salt, 13.94 g (0.065 mol) of dodecyl acrylate, 100.94 g (0.715 mol) of 4-acryloyl morpholine, 53.86 g (0.26 mol) of 2-acrylamido-2-methylpropyl phosphonic acid and 125.34 g of distilled water are added into a reactor and uniformly mixed; 0.075 g (0.0022 mol) of H2O2 and 0.229 g (0.0022 mol) of NaHSO3 are dissolved in 15 g of distilled water to obtain an initiator solution; under nitrogen protection, heating and stirring are started, and when the temperature of the reactor reaches 45°C, the initiator solution is started to be added dropwise, and after the addition is completed within 10 minutes, the stirring is continued for 2.5 hours to obtain a gel-like product; the gel-like product is washed with anhydrous ether for three times, sheared, dried at 106°C, crushed, and sieved through a 140-mesh sieve to obtain the zwitterionic acid thickener.

[0035] Example 4

[0036] For example, to prepare 1 kg of zwitterionic thickening acid, the following raw materials are used: 7 g of zwitterionic acid thickener, 15 g of bromohexadecylpyridine, 4 g of sodium citrate, 5 g of octadecylamine polyoxyethylene ether, and 969 g of 20% hydrochloric acid.

[0037] The preparation method of the zwitterionic thickening acid of this embodiment is as follows: 15 g of bromohexadecylpyridine, 4 g of sodium citrate and 5 g of octadecylamine polyoxyethylene ether are added into 969 g of 20% hydrochloric acid, and then 7 g of zwitterionic acid thickener is slowly and uniformly added under stirring at a speed of 1600 r / min, and after the addition is completed, the stirring is continued for 30 minutes, and after the stirring is stopped, the mixture is left to stand in a water bath at 28°C for 1.8 hours to obtain the zwitterionic thickening acid.

[0038] The zwitterionic acid thickening agent of the embodiment is prepared by copolymerization of N-2-hydroxypropanesulfonic acid group-4-vinylpyridine quaternary ammonium salt, dodecyl acrylate, 4-acryloyl morpholine and 2-acrylamido-2-methylpropyl phosphonic acid in a molar ratio of 1:0.5:5:3, and has a viscosity average molecular weight of 4.15 million Dalton. The specific preparation method is as follows: 29.19 g (0.12 mol) of N-2-hydroxypropanesulfonic acid group-4-vinylpyridine quaternary ammonium salt, 12.86 g (0.06 mol) of dodecyl acrylate, 84.70 g (0.60 mol) of 4-acryloyl morpholine, 74.58 g (0.36 mol) of 2-acrylamido-2-methylpropyl phosphonic acid and 133.38 g of distilled water are added into a reactor and uniformly mixed; 0.099 g (0.0029 mol) of H2O2 and 0.302 g (0.0029 mol) of NaHSO3 are dissolved in 15 g of distilled water to obtain an initiator solution; under nitrogen protection, heating and stirring are started, and when the temperature of the reactor reaches 40°C, the initiator solution is started to be added dropwise, and after the addition is completed within 10 minutes, the reaction is continued for 3 hours to obtain a gel-like product; the gel-like product is washed with anhydrous ether for three times, sheared, dried at 110°C, crushed, and sieved through a 140-mesh sieve to obtain the zwitterionic acid thickening agent.

[0039] Example 5

[0040] For example, to prepare 1 kg of zwitterionic thickening acid, the following raw materials are used: 6 g of zwitterionic acid thickening agent, 10 g of Mannich base HK-936, 8 g of sodium ethylenediamine tetramethylene phosphonate, 7 g of lauric acid diethanolamide, and 969 g of 20% mass concentration hydrochloric acid.

[0041] The preparation method of the zwitterionic thickening acid of the embodiment is as follows: 10 g of Mannich base HK-936, 8 g of sodium ethylenediamine tetramethylene phosphonate and 7 g of lauric acid diethanolamide are added into 969 g of 20% mass concentration hydrochloric acid, and then 6 g of zwitterionic acid thickening agent is slowly and uniformly added under stirring at a speed of 2000 r / min, and after the addition is completed, the stirring is continued for 29 min, and after the stirring is stopped, the mixture is left to stand in a water bath at 26°C for 1.6 h to obtain the zwitterionic thickening acid.

[0042] The zwitterionic acid thickener of the embodiment is prepared by copolymerization of N-2-hydroxypropanesulfonic acid group-4-vinyl pyridine quaternary ammonium salt, hexadecyl acrylate, 4-acryloyl morpholine and 2-acrylamido-2-methylpropyl phosphonic acid in a molar ratio of 1:0.5:5:2.5, and has a viscosity average molecular weight of 8.99 million Dalton. The specific preparation method is as follows: 27.24 g (0.112 mol) of N-2-hydroxypropanesulfonic acid group-4-vinyl pyridine quaternary ammonium salt, 16.60 g (0.056 mol) of hexadecyl acrylate, 79.06 g (0.560 mol) of 4-acryloyl morpholine, 58.00 g (0.28 mol) of 2-acrylamido-2-methylpropyl phosphonic acid and 140.2 g of distilled water are added into a reactor and uniformly mixed; 0.081 g (0.00239 mol) of H2O2 and 0.249 g (0.00239 mol) of NaHSO3 are dissolved in 13 g of distilled water to obtain an initiator solution; under the protection of nitrogen, heating and stirring are started, and when the temperature of the reactor is increased to 42℃, the initiator solution is started to be added dropwise, and after the addition is completed within 10 minutes, the stirring is continued for 2.5 hours to obtain a gel-like product; the gel-like product is washed with anhydrous ether for three times, sheared, dried at 116℃, crushed, and sieved through a 140-mesh sieve to obtain the zwitterionic acid thickener.

[0043] In order to prove the beneficial effects of the present application, the zwitterionic thickening acids prepared in Examples 1-5 and 20% hydrochloric acid were respectively reacted with marble at 30℃, and every 20 min, a certain amount of acid was taken out and titrated with standard sodium hydroxide solution to obtain the concentration of residual acid, and the test results are shown in Table 1.

[0044] Table 1 Retardation performance of zwitterionic thickening acid

[0045]

[0046]

[0047] As can be seen from Table 1, the residual acid concentration of the zwitterionic thickening acids prepared in Examples 1-5 is much higher than that of 20% hydrochloric acid at the same time, which indicates that the zwitterionic thickening acid of the present application has good retardation performance.

[0048] Further, according to the method of 6.2 in “Thickening Agent for Thickening Acid” (SY / T 6214-2016), 350 mL of the zwitterionic thickening acid prepared in Examples 1-5 is added into a six-speed rotational viscometer sample cup, the sample cup is heated, the heating rate is controlled at 3℃ / min, and at the same time, the sample cup is rotated at 170 s -1The sample temperature and apparent viscosity were measured every 10 minutes, and the sample temperature and apparent viscosity were measured every 5 minutes when the temperature was above 120 DEG C. The results are shown in Table 2.

[0049] Table 2 Temperature and shear resistance of zwitterionic thickening acid (unit: mPa s)

[0050]

[0051] As shown in Table 2, the apparent viscosity of the zwitterionic thickening acid prepared in Examples 1-5 is greater than 40 mPa s at 30 DEG C and greater than 15 mPa s at 165 DEG C, indicating that the zwitterionic acid thickener prepared in Examples 1-5 has good solubility and dispersion in the acid, and the thickening effect is significant. The thickening acid prepared by compounding with other additives has good temperature and shear resistance.

[0052] Further, according to the salt addition amount in Table 3, the same mass of CaCl2 and NaCl was added to 350 mL of the zwitterionic thickening acid prepared in Examples 1-5, respectively, and after stirring and dissolving, it was placed in a water bath at 90 DEG C for 24 hours. The apparent viscosity of the solution with different salt contents was measured at a shear rate of 170 s -1

[0053] Table 3 Salt resistance of zwitterionic thickening acid (unit: mPa s)

[0054]

[0055]

[0056] As shown in Table 3, with the increase of salt content, the apparent viscosity of the zwitterionic thickening acid prepared in Examples 1-5 gradually decreases, and when the salt content is 9%, the apparent viscosity retention rate is above 75%, indicating that the zwitterionic thickening acid prepared in Examples 1-5 has significant salt resistance.

[0057] Further, according to the method in standard 4 of “Performance Test Method and Evaluation Index for Acidification Corrosion Inhibitor” (SY / T 5405-2019), the corrosion inhibition performance of the zwitterionic thickening acid prepared in Examples 1-5 was tested, and the test results are shown in Table 4.

[0058] Table 4 Corrosion inhibition performance of zwitterionic thickening acid

[0059] Embodiments Corrosion rate / g / (m 2 ·h) Example 1 1.86 Example 2 4.84 Example 3 2.05 Example 4 0.68 Example 5 2.16

[0060] Note: Experimental conditions: 20% HCl, N80, 90 DEG C, 4h.

[0061] ​As shown in Table 4, in the hydrochloric acid medium with a mass concentration of 20%, the corrosion rates of the zwitterionic thickened acids prepared in Examples 1-5 on N80 test pieces at 90 ℃ all reach the index requirement of ≤6.00 g / (m 2 ·h) in SY / T 5405-2019.

[0062] Further, after being placed for 24 h, the solutions prepared in Examples 1-5 are observed, and no delamination and precipitation phenomenon occurs in the appearance of the solutions. In combination with the apparent viscosity change after temperature resistance and shearing in Table 2, it is indicated that the compatibility of the additives of the zwitterionic thickened acid is good.

Claims

1. A low-damage zwitterionic thickened acid, characterized in that, It is composed of the following raw materials in the following mass percentages: zwitterionic acid thickener 0.3% to 1.0%, acidification corrosion inhibitor 0.5% to 2.0%, iron ion stabilizer 0.2% to 0.9%, drainage aid 0.3% to 0.8%, and hydrochloric acid with a mass concentration of 20% added to 100%; The zwitterionic acid thickener is copolymerized from N-2-hydroxypropanesulfonic acid-4-vinylpyridine quaternary ammonium salt, alkyl acrylate, 4-acryloylmorpholine, and 2-acrylamido-2-methylpropylphosphonic acid, with a viscosity-average molecular weight of 2 million to 12 million Daltons. Its molecular structure is as follows: In the formula, R represents any one of dodecyl, hexadecyl, and octadecyl, and the molar ratio n:p:l:m = 1:0.5:4~5.5:1~3.

2. The low-damage zwitterionic thickened acid according to claim 1, characterized in that, It is composed of the following raw materials in the following mass percentages: zwitterionic acid thickener 0.5% to 0.8%, acidification corrosion inhibitor 1.0% to 1.5%, iron ion stabilizer 0.4% to 0.6%, drainage aid 0.5% to 0.7%, and hydrochloric acid with a mass concentration of 20% added to 100%.

3. The low-damage zwitterionic thickened acid according to claim 1 or 2, characterized in that, The preparation method of the zwitterionic acid thickener is as follows: four monomers, N-2-hydroxypropanesulfonic acid-4-vinylpyridine quaternary ammonium salt, alkyl acrylate, 4-acryloylmorpholine, and 2-acrylamido-2-methylpropylphosphonic acid, are added to distilled water in a molar ratio of 1:0.5:4-5.5:1-3, mixed evenly, and heated to 40-50°C under nitrogen protection and stirring. An initiator is added, and the mixture is stirred at a constant temperature for 2-3 hours to obtain a gel-like product. The gel-like product is purified, sheared, dried at 100-120°C, pulverized, and sieved to obtain the zwitterionic acid thickener. The alkyl acrylate is any one of dodecyl acrylate, hexadecyl acrylate, and octadecyl acrylate.

4. The low-damage zwitterionic thickened acid according to claim 3, characterized in that, The total mass concentration of the four monomers added to the distilled water is 50% to 65%; the initiator is a mixture of H2O2 and NaHSO3 in a molar ratio of 1:1, and the amount of initiator added is 0.1% to 0.2% of the total mass of the four monomers; when using the initiator, it is first dissolved in distilled water to prepare an initiator aqueous solution with a mass concentration of 1% to 5%, and then added dropwise over 10 minutes.

5. The low-damage zwitterionic thickened acid according to claim 3, characterized in that, The preparation method of the N-2-hydroxypropanesulfonic acid-4-vinylpyridine quaternary ammonium salt is as follows: 4-vinylpyridine and sodium 3-chloro-2-hydroxypropanesulfonate are added to distilled water at a molar ratio of 1:1.2-1.

4. After mixing evenly, the pH of the system is adjusted to 7.5-8.5 with a 10% sodium hydroxide aqueous solution. The mixture is heated to 60-80°C with stirring, and hydroquinone is added. The mixture is stirred at a constant temperature for 2-4 hours to obtain a viscous liquid. After washing with anhydrous ethanol, excess solvent is removed by rotary evaporation to obtain the N-2-hydroxypropanesulfonic acid-4-vinylpyridine quaternary ammonium salt. The amount of hydroquinone added is 0.5%-1.0% of the total mass of 4-vinylpyridine and sodium 3-chloro-2-hydroxypropanesulfonate.

6. The low-damage zwitterionic thickened acid according to claim 1 or 2, characterized in that, The acidification corrosion inhibitor is any one or two of the following: long-chain alkyl quaternary ammonium salts, Mannich bases, pyridine quaternary ammonium salts, and quinoline quaternary ammonium salts.

7. The low-damage zwitterionic thickened acid according to claim 1 or 2, characterized in that, The iron ion stabilizer is any one of disodium ethylenediaminetetraacetate, sodium citrate, and sodium ethylenediaminetetramethylenephosphonate.

8. The low-damage zwitterionic thickened acid according to claim 1 or 2, characterized in that, The drainage aid is any one of dodecylamine polyoxyethylene ether, tetradecylamine polyoxyethylene ether, octadecylamine polyoxyethylene ether, lauric acid diethanolamide, and cocoyl oleate diethanolamide.

9. The low-damage zwitterionic thickened acid according to claim 1 or 2, characterized in that, According to the mass percentage composition, the acidification corrosion inhibitor, iron ion stabilizer and drainage aid are added to hydrochloric acid with a mass concentration of 20%. Then, the zwitterionic acid thickener is added while stirring at a speed of 1500-2000 r / min. After the addition is complete, stirring is continued for 25-35 min. Finally, the mixture is allowed to stand in a water bath at 25-30℃ for 1.5-2 h to obtain a low-damage zwitterionic thickened acid.

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