Water treatment agent for oilfield reinjection water and preparation method of water treatment agent

Abstract

The invention relates to the technical field of water treatment, and discloses a water treatment agent for oilfield reinjection water and a preparation method thereof. The water treatment agent for oilfield reinjection water is obtained by copolymerization of sulfonic imidazoline quaternary ammonium salt modified quinoline, Mannich base modified chitosan, acrylic acid and sodium hypophosphite. The water solubility and corrosion inhibition of imidazoline are improved through quaternization modification of imidazoline, quaternary ammonium salt imidazoline can be adsorbed on the metal surface, the corrosion rate is reduced, the quaternary ammonium salt imidazoline serves as a surface active agent, the infiltration and dispersion effects are achieved, and the descaling rate is increased; the sulfonic acid group improves the temperature resistance and prevents the generation of gel, and the strong hydrophilicity of the sulfonic acid group enables a molecular chain to fully stretch in water, so that the scale inhibition performance is improved; mannich base is introduced into chitosan, the acid solubility and temperature resistance of chitosan are improved, the coordination chelation effect of chitosan is enhanced through the conjugation effect of aromatic rings, and the corrosion inhibition effect is improved; various functional groups play a synergistic effect, so that the corrosion and scale inhibition effect is further enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment, in particular to a water treatment agent for oilfield reinjection water and a preparation method thereof. Background Art

[0002] Water injection is an important measure to supplement the energy of oil layers and improve the recovery rate during oil production. In order to improve the recycling rate of water, the produced water with high mineralization is usually injected back into the formation to supplement the formation pressure and maintain production. With the application of stratified water injection development technology, formation scaling, wellbore scaling, pipeline corrosion, and sucker rod breakage often occur, affecting normal oil production. For the corrosion and scaling problems caused by water injection in oil fields, the most commonly used measure is to add corrosion inhibitors and scale inhibitors to the water injection system, but there is a general problem of poor effect. The amount of corrosion and scale inhibitors currently used is too large, and the corrosion and scale inhibition rates are low. In addition, the water temperature of the wastewater injected into the oil field is relatively high, which will also affect the activity of the corrosion and scale inhibitors, resulting in a decrease in their performance. In the document "Synthesis of Modified Polyepoxysuccinic Acid and Study on Its Scale and Corrosion Inhibition Mechanism", modified polyepoxysuccinic acid was synthesized using thiourea and polyepoxysuccinic acid, and it was found that it has good corrosion inhibition effect; however, as a scale inhibitor, polyepoxysuccinic acid has limited dispersibility and poor scale inhibition effect, which limits its application. Summary of the invention

[0003] 1. Technical issues to be resolved

[0004] In view of the shortcomings of the prior art, the present invention provides a water treatment agent for oilfield reinjection water and a preparation method thereof. The water treatment agent for oilfield reinjection water prepared by the present invention has excellent high temperature resistance and corrosion and scale inhibition effects.

[0005] (II) Technical solution

[0006] To achieve the above object, the present invention provides the following technical solution: a water treatment agent for oilfield reinjection water, comprising the following components by weight: 15-20 parts by weight of sulfonic acid imidazoline quaternary ammonium salt modified quinoline, 12-18 parts by weight of Mannich base modified chitosan, 3-7 parts by weight of acrylic acid, and 2-5 parts by weight of sodium hypophosphite;

[0007] Preferably, the method for preparing the sulfonic acid imidazoline quaternary ammonium salt modified quinoline comprises the following steps:

[0008] (1) adding 3-7 g of sodium bisulfite sulfonating agent to deionized water, heating to 72-78° C. while stirring, and dropping 9-13 g of 2-chloro-3,4-epoxy-1-butene thereinto. After the dropwise addition is completed, the temperature is raised to 80-85° C. to react for 2-3 h. After the reaction is completed, cooling in an ice bath is performed, and the crystals precipitated after cooling are filtered and recrystallized to obtain sodium olefin sulfonate;

[0009] (2) adding sodium olefin sulfonate and 2-imidazoline to an acetone solvent, stirring and dissolving, heating to 60-65° C., and reflux heating at 200-400 rpm for 4-6 hours. After the reaction is completed, filtering, washing, and rotary drying are performed to obtain a sulfonic acid imidazoline quaternary ammonium salt;

[0010] (3) adding 12-16 g of 2-quinolinecarboxylic acid and 8-10 g of sulfonic acid imidazoline quaternary ammonium salt to a dichloromethane solvent, stirring to dissolve, adding 0.05-0.08 g of N,N'-dicyclohexylcarbodiimide dehydrating agent, reacting at 24-30° C. for 3-5 h, and after the reaction is completed, filtering with suction, and drying by rotary evaporation to obtain sulfonic acid imidazoline quaternary ammonium salt modified quinoline;

[0011] Preferably, the method for preparing the Mannich base modified chitosan comprises the following steps:

[0012] S1. Add 4-8g of N-vinylpyrrolidone, 12-18g of formaldehyde solution, 0.02-0.04g of p-diphenol reducing agent to the reactor, introduce nitrogen for 20-40min to remove oxygen, heat to 85-90°C, add 6-12g of 4-methylaminobenzoic acid, heat to 130-140°C and react for 6-9h. After the reaction, wash and dry to obtain an alkenyl-containing Mannich base;

[0013] S2. Add 14-18 g of chitosan to an acetic acid solution with a mass fraction of 0.8%-1.2%, stir to dissolve, add 0.04-0.08 g of 1-hydroxybenzotriazole initiator and 3-6 g of alkenyl-containing Mannich base, heat to the reaction temperature, react for 6-10 hours, and after the reaction is completed, dialyze and freeze-dry to obtain Mannich base-modified chitosan.

[0014] Preferably, the dripping time of 2-chloro-3,4-epoxy-1-butene in step (1) is controlled within 40-60 min.

[0015] Preferably, in step (2), the mass ratio of sodium olefin sulfonate to 2-imidazoline is 1:1-1.4.

[0016] Preferably, the mass fraction of the formaldehyde solution in S1 is 38%-42%.

[0017] Preferably, the reaction temperature in S2 is 70-80°C.

[0018] Preferably, the preparation method of the water treatment agent for oilfield reinjection water is: add sulfonic acid imidazoline quaternary ammonium salt modified quinoline, Mannich base modified chitosan, acrylic acid, sodium hypophosphite to deionized water, stir and mix at 60-68°C and then heat to 80-90°C, add 0.2-0.5 weight parts of ammonium persulfate initiator thereto, keep warm for 3-4h, after the reaction is completed, filter after sedimentation in ethanol, and vacuum dry to obtain the water treatment agent for oilfield reinjection water.

[0019] (III) Beneficial technical effects

[0020] The invention obtains a water treatment agent for oilfield reinjection water by copolymerizing sulfonic acid imidazoline quaternary ammonium salt-modified quinoline, Mannich base-modified chitosan, acrylic acid and sodium hypophosphite under the initiator of ammonium persulfate.

[0021] The epoxy group in 2-chloro-3,4-epoxy-1-butene reacts with sodium bisulfite to produce sodium olefin sulfonate and introduces hydroxyl group. The chlorine in sodium olefin sulfonate reacts with 2-imidazoline to produce sulfonic acid imidazoline quaternary ammonium salt. The hydroxyl group in sulfonic acid imidazoline quaternary ammonium salt reacts with the carboxyl group in 2-quinoline carboxylic acid to produce sulfonic acid imidazoline quaternary ammonium salt modified quinoline. N-vinylpyrrolidone, formaldehyde, and 4-methylaminobenzoic acid react with Mannich reaction to produce Mannich base containing olefin group and introduce carboxyl group. The carboxyl group in Mannich base containing olefin group reacts with amino group in chitosan to produce Mannich base modified chitosan.

[0022] The carboxyl group in the water treatment agent for oilfield reinjection water has a strong complexing ability for calcium ions, magnesium ions and iron ions, which not only has the effect of dispersion and coagulation, but also can disrupt the regular arrangement of the crystal structure of scaling substances, thereby achieving the purpose of scale inhibition; in the quaternary ammonium salt of sulfonic acid imidazoline modified quinoline, the water solubility and corrosion inhibition of imidazoline are improved by quaternization modification of imidazoline. The quaternary ammonium salt imidazoline can be adsorbed on the metal surface to form a dense protective layer, effectively reducing the metal corrosion rate, and can also act as a surfactant to play a wetting and dispersing role, making it easier for the water treatment agent to enter the scale layer and accelerate the descaling rate; the introduction of sulfonic acid groups with stronger acidity than carboxyl groups can not only increase the temperature resistance of the water treatment agent, but also prevent the carboxyl group from forming a gel-like substance with scaling cations, and the strong hydrophilicity of the sulfonic acid group enables the molecular chain to fully stretch in water, thereby improving the permeability and thus improving the scale inhibition performance; the ester group has the properties of both lattice distortion and dispersed microcrystals, and has a better complexing effect on scaling cations, thereby achieving It has the functions of anti-scaling and anti-fouling, and exhibits good thermal stability at high temperatures, which enhances the high temperature resistance of the water treatment agent. Quinoline is a nitrogen-containing bicyclic compound with a high electron density, which can reduce the enrichment of anions on the metal surface and improve the corrosion inhibition effect. In the Mannich base-modified chitosan, the chitosan molecule contains a large number of active groups such as hydroxyl and amino groups, and the molecular chain can carry a positive charge after being dissolved in water, which can produce a strong binding force with metal atoms to form a protective film, reduce the active corrosion sites on the metal surface, and have the function of anti-scaling and anti-corrosion. By introducing Mannich base into the chitosan molecule, the acid solubility and temperature resistance of chitosan are improved, and the conjugation effect of the aromatic ring in the Mannich base strengthens the coordination and chelation between the chitosan molecule and the metal, thereby enhancing the corrosion inhibition effect. By modifying quinoline with sulfonic acid imidazoline quaternary ammonium salt, Mannich base-modified chitosan, acrylic acid, and sodium hypophosphite to form a copolymer, multiple functional groups can play a synergistic effect, further enhancing the corrosion and scale inhibition effect of the water treatment agent for oilfield reinjection water. DETAILED DESCRIPTION

[0023] Example 1

[0024] (1) adding 3 g of sodium bisulfite sulfonating agent to deionized water, heating to 72° C. while stirring, and dripping 9 g of 2-chloro-3,4-epoxy-1-butene therein, the dripping time is controlled to be 40 min. After the dripping is completed, the temperature is raised to 80° C. to react for 2 h. After the reaction is completed, the water is cooled in an ice bath, and the crystals precipitated after cooling are filtered and recrystallized to obtain sodium olefin sulfonate;

[0025] (2) adding sodium olefin sulfonate and 2-imidazoline to an acetone solvent, stirring and dissolving, wherein the mass ratio of sodium olefin sulfonate to 2-imidazoline is 1:1, heating to 60° C., reflux heating at 200 rpm for 4 h, and after the reaction is completed, filtering with suction, washing and rotary drying to obtain sulfonic acid imidazoline quaternary ammonium salt;

[0026] (3) Add 12 g of 2-quinolinecarboxylic acid and 8 g of sulfonic acid imidazoline quaternary ammonium salt to dichloromethane solvent, stir to dissolve, add 0.05 g of N,N'-dicyclohexylcarbodiimide dehydrating agent, react at 24 ° C for 3 h, filter after the reaction, and dry by rotary evaporation to obtain sulfonic acid imidazoline quaternary ammonium salt modified quinoline;

[0027] (4) Add 4 g of N-vinyl pyrrolidone, 12 g of a 38% formaldehyde solution, and 0.02 g of p-diphenol reducing agent to a reactor, introduce nitrogen for 20 min to remove oxygen, heat to 85° C., add 6 g of 4-methylaminobenzoic acid, heat to 130° C. and react for 6 h. After the reaction is completed, wash and dry to obtain an alkenyl-containing Mannich base;

[0028] (5) adding 14 g of chitosan to a 0.8% acetic acid solution, stirring to dissolve, adding 0.04 g of 1-hydroxybenzotriazole initiator and 3 g of alkenyl-containing Mannich base, heating to 70° C., reacting for 6 h, and after the reaction, dialyzing and freeze-drying to obtain Mannich base-modified chitosan;

[0029] (6) Add 15 parts by weight of sulfonic acid imidazoline quaternary ammonium salt-modified quinoline, 12 parts by weight of Mannich base-modified chitosan, 3 parts by weight of acrylic acid, and 2 parts by weight of sodium hypophosphite to deionized water, stir and mix at 60° C. and then heat to 80° C., add 0.2 parts by weight of ammonium persulfate initiator, and keep the temperature for reaction for 3 hours. After the reaction is completed, filter after precipitation in ethanol and vacuum dry to obtain a water treatment agent for oilfield reinjection water.

[0030] Example 2

[0031] (1) adding 7 g of sodium bisulfite sulfonating agent to deionized water, heating to 78° C. while stirring, and dripping 13 g of 2-chloro-3,4-epoxy-1-butene therein, the dripping time is controlled within 60 min, and after the dripping is completed, the temperature is raised to 85° C. to react for 3 h. After the reaction is completed, cooling in an ice bath, filtering the crystals precipitated after cooling, and recrystallizing to obtain sodium olefin sulfonate;

[0032] (2) adding sodium olefin sulfonate and 2-imidazoline to an acetone solvent, stirring and dissolving, wherein the mass ratio of sodium olefin sulfonate to 2-imidazoline is 1:1.4, heating to 65° C., reflux heating at 400 rpm for 6 h, and after the reaction is completed, filtering with suction, washing and rotary drying to obtain sulfonic acid imidazoline quaternary ammonium salt;

[0033] (3) Add 16 g of 2-quinolinecarboxylic acid and 10 g of sulfonic acid imidazoline quaternary ammonium salt to dichloromethane solvent, stir to dissolve, add 0.08 g of N,N'-dicyclohexylcarbodiimide dehydrating agent, react at 30°C for 5 h, and after the reaction is completed, filter and dry by rotary evaporation to obtain sulfonic acid imidazoline quaternary ammonium salt modified quinoline;

[0034] (4) adding 8 g of N-vinyl pyrrolidone, 12-18 g of a 42% formaldehyde solution, and 0.04 g of p-diphenol reducing agent to a reactor, introducing nitrogen for 40 min to remove oxygen, heating to 90° C., adding 12 g of 4-methylaminobenzoic acid, heating to 140° C. to react for 9 h, and after the reaction is completed, washing and drying to obtain an alkenyl-containing Mannich base;

[0035] (5) adding 18 g of chitosan to a 1.2% acetic acid solution, stirring to dissolve, adding 0.08 g of 1-hydroxybenzotriazole initiator and 6 g of alkenyl-containing Mannich base, heating to 80° C., reacting for 10 h, and after the reaction, dialyzing and freeze-drying to obtain Mannich base-modified chitosan;

[0036] (6) Add 20 parts by weight of sulfonic acid imidazoline quaternary ammonium salt-modified quinoline, 18 parts by weight of Mannich base-modified chitosan, 7 parts by weight of acrylic acid, and 5 parts by weight of sodium hypophosphite to deionized water, stir and mix at 68° C. and then heat to 90° C., add 0.5 parts by weight of ammonium persulfate initiator, and keep the temperature to react for 4 hours. After the reaction is completed, filter after precipitation in ethanol and vacuum dry to obtain a water treatment agent for oilfield reinjection water.

[0037] Example 3

[0038] (1) Add 5 g of sodium bisulfite sulfonating agent to deionized water, heat to 75° C. while stirring, and dropwise add 11 g of 2-chloro-3,4-epoxy-1-butene thereto, the dropping time being controlled within 50 min. After the dropwise addition is completed, the temperature is raised to 82° C. and reacted for 2.5 h. After the reaction is completed, cool in an ice bath, filter the precipitated crystals after cooling, and recrystallize to obtain sodium olefin sulfonate;

[0039] (2) adding sodium olefin sulfonate and 2-imidazoline to an acetone solvent, stirring and dissolving, wherein the mass ratio of sodium olefin sulfonate to 2-imidazoline is 1:1.2, heating to 62° C., reflux heating at 300 rpm for 5 h, and after the reaction is completed, filtering with suction, washing and rotary drying to obtain sulfonic acid imidazoline quaternary ammonium salt;

[0040] (3) Add 14 g of 2-quinolinecarboxylic acid and 9 g of sulfonic acid imidazoline quaternary ammonium salt to dichloromethane solvent, stir to dissolve, add 0.06 g of N,N'-dicyclohexylcarbodiimide dehydrating agent, react at 27 ° C for 4 h, filter after the reaction, and dry by rotary evaporation to obtain sulfonic acid imidazoline quaternary ammonium salt modified quinoline;

[0041] (4) Add 6 g of N-vinyl pyrrolidone, 15 g of a 40% formaldehyde solution, and 0.03 g of p-diphenol reducing agent to a reactor, introduce nitrogen for 30 min to remove oxygen, heat to 88° C., add 9 g of 4-methylaminobenzoic acid, heat to 135° C. and react for 7.5 h. After the reaction is completed, wash and dry to obtain an alkenyl-containing Mannich base;

[0042] (5) adding 16 g of chitosan to a 1% acetic acid solution, stirring to dissolve, adding 0.06 g of 1-hydroxybenzotriazole initiator and 4.5 g of alkenyl-containing Mannich base, heating to 75° C., reacting for 8 h, and after the reaction, dialyzing and freeze-drying to obtain Mannich base-modified chitosan;

[0043] (6) Add 17 parts by weight of sulfonic acid imidazoline quaternary ammonium salt-modified quinoline, 15 parts by weight of Mannich base-modified chitosan, 5 parts by weight of acrylic acid, and 3 parts by weight of sodium hypophosphite to deionized water, stir and mix at 64° C. and then heat to 85° C., add 0.3 parts by weight of ammonium persulfate initiator, and keep the temperature to react for 3.5 hours. After the reaction is completed, filter after precipitation in ethanol and vacuum dry to obtain a water treatment agent for oilfield reinjection water.

[0044] Example 4

[0045] (1) adding 3 g of sodium bisulfite sulfonating agent to deionized water, heating to 72° C. while stirring, and dripping 9 g of 2-chloro-3,4-epoxy-1-butene therein, the dripping time is controlled to be 40 min. After the dripping is completed, the temperature is raised to 80° C. to react for 2 h. After the reaction is completed, the water is cooled in an ice bath, and the crystals precipitated after cooling are filtered and recrystallized to obtain sodium olefin sulfonate;

[0046] (2) adding sodium olefin sulfonate and 2-imidazoline to an acetone solvent, stirring and dissolving, wherein the mass ratio of sodium olefin sulfonate to 2-imidazoline is 1:1, heating to 60° C., reflux heating at 200 rpm for 4 h, and after the reaction is completed, filtering with suction, washing and rotary drying to obtain sulfonic acid imidazoline quaternary ammonium salt;

[0047] (3) Add 16 g of 2-quinolinecarboxylic acid and 10 g of sulfonic acid imidazoline quaternary ammonium salt to dichloromethane solvent, stir to dissolve, add 0.08 g of N,N'-dicyclohexylcarbodiimide dehydrating agent, react at 30°C for 5 h, and after the reaction is completed, filter and dry by rotary evaporation to obtain sulfonic acid imidazoline quaternary ammonium salt modified quinoline;

[0048] (4) adding 8 g of N-vinyl pyrrolidone, 12-18 g of a 42% formaldehyde solution, and 0.04 g of p-diphenol reducing agent to a reactor, introducing nitrogen for 40 min to remove oxygen, heating to 90° C., adding 12 g of 4-methylaminobenzoic acid, heating to 140° C. to react for 9 h, and after the reaction is completed, washing and drying to obtain an alkenyl-containing Mannich base;

[0049] (5) adding 16 g of chitosan to a 1% acetic acid solution, stirring to dissolve, adding 0.06 g of 1-hydroxybenzotriazole initiator and 4.5 g of alkenyl-containing Mannich base, heating to 75° C., reacting for 8 h, and after the reaction, dialyzing and freeze-drying to obtain Mannich base-modified chitosan;

[0050] (6) Add 17 parts by weight of sulfonic acid imidazoline quaternary ammonium salt-modified quinoline, 15 parts by weight of Mannich base-modified chitosan, 5 parts by weight of acrylic acid, and 3 parts by weight of sodium hypophosphite to deionized water, stir and mix at 64° C. and then heat to 85° C., add 0.3 parts by weight of ammonium persulfate initiator, and keep the temperature to react for 3.5 hours. After the reaction is completed, filter after precipitation in ethanol and vacuum dry to obtain a water treatment agent for oilfield reinjection water.

[0051] Example 5

[0052] (1) adding 7 g of sodium bisulfite sulfonating agent to deionized water, heating to 78° C. while stirring, and dripping 13 g of 2-chloro-3,4-epoxy-1-butene therein, the dripping time is controlled within 60 min, and after the dripping is completed, the temperature is raised to 85° C. to react for 3 h. After the reaction is completed, cooling in an ice bath, filtering the crystals precipitated after cooling, and recrystallizing to obtain sodium olefin sulfonate;

[0053] (2) adding sodium olefin sulfonate and 2-imidazoline to an acetone solvent, stirring and dissolving, wherein the mass ratio of sodium olefin sulfonate to 2-imidazoline is 1:1.4, heating to 65° C., reflux heating at 400 rpm for 6 h, and after the reaction is completed, filtering with suction, washing and rotary drying to obtain sulfonic acid imidazoline quaternary ammonium salt;

[0054] (3) Add 14 g of 2-quinolinecarboxylic acid and 9 g of sulfonic acid imidazoline quaternary ammonium salt to dichloromethane solvent, stir to dissolve, add 0.06 g of N,N'-dicyclohexylcarbodiimide dehydrating agent, react at 27 ° C for 4 h, filter after the reaction, and dry by rotary evaporation to obtain sulfonic acid imidazoline quaternary ammonium salt modified quinoline;

[0055] (4) Add 6 g of N-vinyl pyrrolidone, 15 g of a 40% formaldehyde solution, and 0.03 g of p-diphenol reducing agent to a reactor, introduce nitrogen for 30 min to remove oxygen, heat to 88° C., add 9 g of 4-methylaminobenzoic acid, heat to 135° C. and react for 7.5 h. After the reaction is completed, wash and dry to obtain an alkenyl-containing Mannich base;

[0056] (5) adding 14 g of chitosan to a 0.8% acetic acid solution, stirring to dissolve, adding 0.04 g of 1-hydroxybenzotriazole initiator and 3 g of alkenyl-containing Mannich base, heating to 70° C., reacting for 6 h, and after the reaction, dialyzing and freeze-drying to obtain Mannich base-modified chitosan;

[0057] (6) Add 15 parts by weight of sulfonic acid imidazoline quaternary ammonium salt-modified quinoline, 12 parts by weight of Mannich base-modified chitosan, 3 parts by weight of acrylic acid, and 2 parts by weight of sodium hypophosphite to deionized water, stir and mix at 60° C. and then heat to 80° C., add 0.2 parts by weight of ammonium persulfate initiator, and keep the temperature for reaction for 3 hours. After the reaction is completed, filter after precipitation in ethanol and vacuum dry to obtain a water treatment agent for oilfield reinjection water.

[0058] Comparative Example 1

[0059] The difference between this comparative example and Example 5 is that no sulfonic acid imidazoline quaternary ammonium salt is added to modify quinoline in step (6).

[0060] Comparative Example 2

[0061] The difference between this comparative example and Example 5 is that no Mannich base-modified chitosan is added in step (6).

[0062] According to the national standard GB / T16632-2008 "Determination of scale inhibition performance of water treatment agents - calcium carbonate deposition method", a static scale inhibition experiment was conducted to test the scale inhibition performance of water treatment agents for oilfield reinjection water. + and HCO3 - The concentrations of 250mg / L and 750mg / L were respectively, and the amount of water treatment agent added to the oilfield reinjection water was 8mg / L. The water was kept at constant temperature for 24h at different temperatures, and then cooled and filtered, and then complex titrated with EDTA standard solution to calculate the scale inhibition rate. The test results are shown in Table 1.

[0063] Table 1: Antiscaling performance test.

[0064]

[0065] It can be seen from Table 1 that Examples 1-5 of the present invention have better scale inhibition performance than Comparative Examples 1-2, and as the temperature increases, the scale inhibition rate remains above 90%, having better high temperature resistance.

[0066] A 50 mm × 10 mm × 2 mm carbon steel sheet was polished smooth with sandpaper, washed with deionized water and ethanol, and vacuum dried before weighing. 2+ =200.4mg / L, Mg 2+ =48.62mg / L, Cl - =399.1mg / L, HCO3 2- =122.0mg / L simulated solution, put carbon steel sheet into the simulated solution, add 20mg / L of water treatment agent for oilfield reinjection water, keep constant temperature for 24h at different temperatures, take out carbon steel sheet, wash with deionized water and ethanol, dry in vacuum, weigh, and calculate corrosion inhibition rate. Test results are shown in Table 2.

[0067] Table 2: Corrosion inhibition performance test.

[0068]

[0069]

[0070] It can be seen from Table 2 that Examples 1-5 of the present invention have better corrosion inhibition performance and high temperature resistance effect than Comparative Examples 1-2.

[0071] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A water treatment agent for oilfield reinjection water, characterized in that: The invention comprises the following components by weight: 15-20 parts by weight of sulfonic acid imidazoline quaternary ammonium salt modified quinoline, 12-18 parts by weight of Mannich base modified chitosan, 3-7 parts by weight of acrylic acid, and 2-5 parts by weight of sodium hypophosphite; The preparation method of the sulfonic acid imidazoline quaternary ammonium salt modified quinoline comprises the following steps: (1) adding 3-7 g of sodium bisulfite sulfonating agent to deionized water, heating to 72-78° C. while stirring, and dropping 9-13 g of 2-chloro-3,4-epoxy-1-butene thereinto. After the dropwise addition is completed, the temperature is raised to 80-85° C. to react for 2-3 h. After the reaction is completed, cooling in an ice bath is performed, and the crystals precipitated after cooling are filtered and recrystallized to obtain sodium olefin sulfonate; (2) adding sodium olefin sulfonate and 2-imidazoline to an acetone solvent, stirring and dissolving, heating to 60-65° C., and reflux heating at 200-400 rpm for 4-6 hours. After the reaction is completed, filtering, washing, and rotary drying are performed to obtain a sulfonic acid imidazoline quaternary ammonium salt; (3) adding 12-16 g of 2-quinolinecarboxylic acid and 8-10 g of sulfonic acid imidazoline quaternary ammonium salt to a dichloromethane solvent, stirring to dissolve, adding 0.05-0.08 g of N,N'-dicyclohexylcarbodiimide dehydrating agent, reacting at 24-30° C. for 3-5 h, and after the reaction is completed, filtering with suction, and drying by rotary evaporation to obtain sulfonic acid imidazoline quaternary ammonium salt modified quinoline; The method for preparing the Mannich base modified chitosan comprises the following steps: S1. Add 4-8g of N-vinylpyrrolidone, 12-18g of formaldehyde solution, 0.02-0.04g of p-diphenol reducing agent to the reactor, introduce nitrogen for 20-40min to remove oxygen, heat to 85-90°C, add 6-12g of 4-methylaminobenzoic acid, heat to 130-140°C and react for 6-9h. After the reaction, wash and dry to obtain an alkenyl-containing Mannich base; S2. Add 14-18 g of chitosan to an acetic acid solution with a mass fraction of 0.8%-1.2%, stir to dissolve, add 0.04-0.08 g of 1-hydroxybenzotriazole initiator and 3-6 g of alkenyl-containing Mannich base, heat to the reaction temperature, react for 6-10 hours, and after the reaction is completed, dialyze and freeze-dry to obtain Mannich base-modified chitosan.

2. The water treatment agent for oilfield reinjection water according to claim 1, characterized in that: The dripping time of 2-chloro-3,4-epoxy-1-butene in the step (1) is controlled within 40-60 minutes.

3. The water treatment agent for oilfield reinjection water according to claim 1, characterized in that: In the step (2), the mass ratio of sodium olefin sulfonate to 2-imidazoline is 1:1-1.

4.

4. The water treatment agent for oilfield reinjection water according to claim 1, characterized in that: The mass fraction of the formaldehyde solution in S1 is 38%-42%.

5. The water treatment agent for oilfield reinjection water according to claim 1, characterized in that: The reaction temperature in S2 is 70-80°C.

6. A method for preparing a water treatment agent for oilfield reinjection water according to any one of claims 1 to 5, characterized in that: The preparation method of the water treatment agent for oilfield reinjection water comprises the following steps: adding sulfonic acid imidazoline quaternary ammonium salt modified quinoline, Mannich base modified chitosan, acrylic acid and sodium hypophosphite to deionized water, stirring and mixing at 60-68° C. and then heating to 80-90° C., adding 0.2-0.5 parts by weight of ammonium persulfate initiator thereto, keeping the temperature for reaction for 3-4 hours, and after the reaction is finished, filtering after settling in ethanol and vacuum drying to obtain the water treatment agent for oilfield reinjection water.

Images