Carbon dioxide flooding casing protection liquid and preparation method and application thereof

Abstract

The invention belongs to the field of petroleum field casing protection liquid, and discloses carbon dioxide flooding casing protection liquid as well as a preparation method and application thereof. The casing protection liquid is prepared by mixing the following raw materials: an agent A: 5-10 parts of polyoxyethylene rosin amine, 5-15 parts of rosin imidazoline, 5-10 parts of oleic acid imidazoline, 10-15 parts of amide imidazoline, 8-10 parts of a bis-imidazoline corrosion inhibitor, 8-10 parts of paper pulp waste liquid and 30-59 parts of water; and the casing protection liquid is prepared from the following components in parts by weight: 4 to 8 parts of the agent A, 0.5 to 1.5 parts of glycerol polyoxypropylene polyoxyethylene ether, 20 to 30 parts of ethylene glycol and 60.5 to 75.5 parts of water. The corrosion rate of a carbon dioxide injection well can be greatly reduced, and the cost is reduced by more than 60% compared with that of an oil-based casing protection liquid.

Description

Technical Field

[0001] The invention belongs to the field of casing protection fluid for petroleum oil fields, and relates to a carbon dioxide driven casing protection fluid and a preparation method and application thereof. Background Art

[0002] In the application of CO2 injection and production technology and the subsequent expansion of CCUS application, there are some technical problems that need to be solved urgently. Carbon dioxide will cause serious corrosion problems to the oil casing of injection wells and production wells in the humid environment underground, especially under high temperature conditions. In particular, corrosion will cause casing leakage and damage, seriously affecting the normal production. Among them, for the anti-corrosion problem of injection wells, the better method is to inject casing anti-corrosion protection liquid into the annulus of the oil casing to protect the casing to the maximum extent and prevent corrosion.

[0003] At present, the commonly used casing protection liquid is oil-based casing protection liquid. 4%-7% corrosion inhibitor, 1%-5% surfactant and 1%-3% scale inhibitor are added to the oil base to form a casing protection liquid system. Because it is an oil-based system, the cost of the protection liquid is relatively high.

[0004] At the same time, in view of the casing corrosion mechanism, the annular protection fluid used in various oil fields is composed of bactericides, deoxidizers, corrosion and scale inhibitors, density regulators, etc. Among them, there are many studies and applications on corrosion and scale inhibitors. For example, imidazoline derivatives, organic phosphates, polycarboxylic acids and other corrosion and scale inhibitors are more commonly used. Density regulators can be divided into inorganic salt type and organic salt type. Although the annular protection fluid using the above technology can improve the water quality of the annular space and reduce the corrosiveness of the annular water, the effect is not ideal in the injection wells of oil and gas wells that inject CO2 corrosive gas. Especially in high-pressure injection gas wells, leakage from the gap of the packer to the annular protection fluid can easily turn the protection fluid into an acidic liquid, accelerate the corrosion of the oil pipe and casing, cause serious damage to the casing and production tubing, and thus lead to huge economic losses. Summary of the invention

[0005] In order to overcome the deficiencies of the prior art, the present invention provides a carbon dioxide driven casing protection fluid and a preparation method and application thereof, which can greatly reduce the corrosion rate of the carbon dioxide injection well and reduce the cost by more than 60% compared with oil-based casing protection fluid.

[0006] The purpose of the present invention is to provide a carbon dioxide flooding casing protection fluid, which can not only effectively solve the casing corrosion problem of CO2 flooding injection wells, but also achieve the purpose of low-cost anti-corrosion.

[0007] Another object of the present invention is to provide a method for preparing the casing protection liquid.

[0008] The present invention also aims to provide an application of a carbon dioxide driven casing protection fluid.

[0009] The above object of the present invention is achieved through the following technical solutions:

[0010] A carbon dioxide flooding casing protection fluid, wherein the mass fraction ratio of each raw material component of the casing protection fluid is:

[0011]

[0012] The mass ratio of the raw material components of Agent A is:

[0013]

[0014] The polyoxyethylene rosin amine, rosin imidazoline, oleic acid imidazoline, amide imidazoline, bisimidazoline corrosion inhibitor, pulp waste liquid, glycerol polyoxypropylene polyoxyethylene ether and ethylene glycol are all commercially available industrial products. The pulp waste liquid in the present invention is a byproduct of sulfite papermaking wood pulp.

[0015] Any commercially available product meeting the corresponding quality standards can be used in the present invention and achieve the purpose of the present invention.

[0016] According to some specific embodiments of the present invention, the casing protection liquid is prepared by mixing the following raw materials: Agent A: 5-10 parts of polyoxyethylene rosin amine, 5-15 parts of rosin imidazoline, 5-10 parts of oleic acid imidazoline, 10-15 parts of amide imidazoline, 8-10 parts of bisimidazoline corrosion inhibitor, 8-10 parts of pulp waste liquid, and 30-59 parts of water; Casing protection liquid: 4-8 parts of Agent A, 0.5-1.5 parts of glycerol polyoxypropylene polyoxyethylene ether, 20-30 parts of ethylene glycol and 60.5-75.5 parts of water.

[0017] The casing protection fluid of the present invention has a good corrosion inhibition effect on metals in a carbon dioxide injection environment. In the indoor corrosion rate simulation experiment, the corrosion reaction time is 72h. The corrosion rate is 4.21mm / a before adding the casing protection fluid. After using the casing protection fluid, the corrosion rate is 0.026mm / a. After the casing protection fluid is injected into the field test well, carbon dioxide is injected. The test time is one month. After the test, the corrosion rate is measured to be only 0.002mm / a. It is proved by indoor experiments and field tests that the casing protection fluid of the above invention has a good effect of preventing carbon dioxide corrosion. At present, more than 30 wells have been implemented on site. With the expansion of carbon storage in carbon drive oil, the casing protection fluid has a good application prospect.

[0018] The present invention also provides a method for preparing the above-mentioned casing protection liquid, which comprises:

[0019] (1) Weigh 180 kg to 708 kg of water into a reaction kettle and begin heating to 40° C. while stirring;

[0020] (2) Weigh 30 kg to 120 kg of polyoxyethylene rosin amine into a reaction kettle and stir for 5 minutes;

[0021] (3) Weigh 30 kg to 180 kg of rosin imidazoline into a reaction kettle and stir for 5 minutes;

[0022] (4) Weigh 30 kg to 120 kg of oleic acid imidazoline into a reaction kettle and stir for 5 minutes;

[0023] (5) Weigh 60 kg to 180 kg of amide imidazoline into a reaction kettle and stir for 5 minutes;

[0024] (6) Weigh 48 kg to 120 kg of bisimidazoline corrosion inhibitor into the reactor and stir for 20 minutes;

[0025] (7) Weigh 48 kg to 120 kg of pulp waste liquid into the reactor and stir for 20 minutes;

[0026] (8) Stop heating and lower the temperature of the reactor to room temperature to obtain Agent A.

[0027] (9) Weigh 9075 kg - 11325 kg of water at 15m 3 In a stirring tank, add 75 kg to 225 kg of glycerol polyoxypropylene polyoxyethylene ether while stirring and stir for 15 minutes.

[0028] (10) Add 600 kg to 1200 kg of Agent A into a mixing tank, stirring for 15 minutes;

[0029] (11) Add 3000 kg to 4500 kg of ethylene glycol and stir for 20 minutes to obtain a casing protection liquid.

[0030] Preferably, in step (1), the temperature of the reactor is raised to 40±1°C.

[0031] Preferably, in steps (1)-(7), the stirring speed is 45 rpm.

[0032] Preferably, in steps (9)-(11), the stirring speed is 60 rpm.

[0033] The present invention also provides the application of the above-mentioned casing protection fluid in a carbon dioxide injection well. In specific application, the following steps can be followed: the casing protection fluid is pumped into the wellbore by a pump truck, injected into the casing through the oil pipe and returned, and circulated until the returned fluid is consistent with the injected fluid, and the injection of the casing protection fluid is stopped. Then, the ball-dropping downhole packer is set to seal the casing protection fluid in the oil-casing annulus, thereby protecting the casing from corrosion.

[0034] The beneficial effects of the present invention compared with the prior art are:

[0035] The present invention provides a carbon dioxide flooding casing protection fluid and its preparation method and application. The casing protection fluid can be injected from the oil pipe into the casing and returned, and circulated until the returned fluid is consistent with the injected fluid. Then, the ball-dropping downhole packer is set to seal the casing protection fluid in the oil casing annulus, thereby efficiently and low-costly solving the corrosion problem of CO2 flooding injection wells and ensuring normal production. DETAILED DESCRIPTION

[0036] The present invention is described in detail below by specific examples, but the protection scope of the present invention is not limited. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can be obtained from commercial channels.

[0037] Example 1

[0038] Synthesize 15 tons of casing protection fluid, the preparation method is as follows:

[0039] (1) Weigh 342 kg of water into a reaction kettle and begin heating to 40° C. while stirring;

[0040] (2) Weigh 30 kg of polyoxyethylene rosin amine and add it into the reaction kettle, stirring for 5 minutes;

[0041] (3) Weigh 30 kg of rosin imidazoline into the reactor and stir for 5 minutes;

[0042] (4) Weigh 30 kg of oleic acid imidazoline and add it into the reaction kettle, and stir for 5 minutes;

[0043] (5) Weigh 60 kg of amide imidazoline into the reactor and stir for 5 minutes;

[0044] (6) Weigh 48 kg of bisimidazoline corrosion inhibitor and add it to the reactor, stirring for 20 minutes;

[0045] (7) Weigh 60 kg of pulp waste liquid into the reactor and stir for 20 minutes;

[0046] (8) Stop heating and lower the temperature of the reactor to room temperature to obtain Agent A.

[0047] (9) Weigh 11325 kg of water at 15 m 3 In the mixing tank, add 75 kg of glycerol polyoxypropylene polyoxyethylene ether while stirring and stir for 15 minutes.

[0048] (10) Add 600 kg of Agent A into the mixing tank, stirring for 15 minutes;

[0049] (11) Add 3000 kg of ethylene glycol and stir for 20 minutes to obtain a casing protection liquid.

[0050] In step (1), the reactor is heated to 40±1°C;

[0051] In steps (1)-(7), the stirring speed is 45 rpm.

[0052] In steps (9)-(11), the stirring speed is 60 rpm.

[0053] Effect evaluation of the casing protection liquid prepared in Example 1:

[0054] Indoor evaluation experimental steps:

[0055] Before the experiment, wipe the corrosion coupons with filter paper, then put them into a container filled with petroleum ether or acetone with a boiling range of 60℃-90℃, remove the grease on the surface of the coupons with absorbent cotton, and then soak them in anhydrous ethanol for about 5 minutes for further degreasing and dehydration. Take out the coupons and place them on filter paper, blow dry with cold air, wrap them with filter paper, and store them in a desiccator. After leaving them for 1 hour, measure the size and weigh them with an accuracy of 0.1mg.

[0056] According to the volume of the reactor, the simulated water on site was taken and put into the reactor. Nitrogen was first passed into the simulated water on site for 0.5h to remove the oxygen in the simulated water. Then the treated N80 corrosion coupon was hung. After the reactor cover was sealed, the CO2 pressure value required for the experiment was set according to the actual situation on site, and the reactor was kept at the actual temperature on site for static corrosion evaluation experiment. The experimental time was 72h. Three parallel experiments were carried out for each group of experiments, and the average value of the parallel experiments was taken as the measurement result.

[0057] Take out the coupons that have reached the experimental cycle, observe and record the surface corrosion state and the adhesion of corrosion products, immediately rinse off the experimental medium with clean water, and wipe the coupons dry with filter paper. Put the coupons into a container with petroleum ether or acetone with a boiling range of 60℃-90℃, wipe gently with absorbent cotton, and then soak them in anhydrous ethanol for 5 minutes for further degreasing and dehydration. Take out the coupons and soak them in the acid cleaning solution prepared according to Appendix A of SY / T5273-2000 standard for 5 minutes, and use tweezers to hold a small amount of absorbent cotton to gently wipe the corrosion products on the surface of the coupons. Take out the coupons from the cleaning solution, rinse the surface residual acid with tap water, and immediately immerse the coupons in sodium hydroxide solution (60g / L), rinse with tap water after 30s, and then soak them in anhydrous ethanol for about 5 minutes, and wash and dehydrate twice. Take out the hanging piece and place it on filter paper, blow it dry with cold air, then wrap the hanging piece with filter paper, store it in a desiccator, and weigh it after leaving it for 1 hour, with an accuracy of 0.1 mg.

[0058] Indoor evaluation test results:

[0059] The corrosion rate is calculated as follows:

[0060]

[0061] Where: r corr ——Uniform corrosion rate, mm / a; m——Mass of the coupon before the test, g; m t ——The weight of the coupon after the test, g; S1——The total area of ​​the coupon, cm 2 ; ρ——density of the hanging material, g / cm 3 ; t——test time, h.

[0062] The specific experimental results are shown in Table 1:

[0063] Table 1. Anticorrosion performance evaluation table

[0064] Evaluation Project Evaluation results Corrosion rate (blank) 4.212mm / a Corrosion rate (casing protection fluid) 0.035mm / a

[0065] On-site evaluation:

[0066] A coupon with a corrosion cycle of one month was taken out from the well. The coupon treatment and corrosion rate calculation steps after field corrosion were the same as those in the indoor experiment. After the casing protection fluid was injected into the field test well, the corrosion rate of the corrosion coupon was measured to be only 0.002mm / a.

[0067] Embodiment 2:

[0068] Synthesize 15 tons of casing protection fluid, the preparation method is as follows:

[0069] (1) Weigh 360 kg of water into a reaction kettle and heat it to 40°C while stirring;

[0070] (2) Weigh 120 kg of polyoxyethylene rosin amine into a reaction kettle and stir for 5 minutes;

[0071] (3) Weigh 180 kg of rosin imidazoline into the reactor and stir for 5 minutes;

[0072] (4) Weigh 120 kg of oleic acid imidazoline into a reaction kettle and stir for 5 minutes;

[0073] (5) Weigh 180 kg of amide imidazoline into the reactor and stir for 5 minutes;

[0074] (6) Weigh 120 kg of bisimidazoline corrosion inhibitor and add it to the reactor, stirring for 20 minutes;

[0075] (7) Weigh 120 kg of pulp waste liquid into the reactor and stir for 20 minutes;

[0076] (8) Stop heating and lower the temperature of the reactor to room temperature to obtain Agent A.

[0077] (9) Weigh 9075 kg of water at 15 m 3 In the mixing tank, add 225 kg of glycerol polyoxypropylene polyoxyethylene ether while stirring and stir for 15 minutes.

[0078] (10) Add 1200 kg of Agent A into the mixing tank, stirring for 15 minutes;

[0079] (11) Add 4500 kg of ethylene glycol and stir for 20 minutes to obtain a casing protection liquid.

[0080] In step (1), the reactor is heated to 40±1°C;

[0081] In steps (1)-(7), the stirring speed is 45 rpm.

[0082] In steps (9)-(11), the stirring speed is 60 rpm.

[0083] Effect evaluation of the casing protection liquid prepared in Example 2:

[0084] Indoor evaluation experimental steps:

[0085] Before the experiment, wipe the corrosion coupons with filter paper, then put them into a container filled with petroleum ether or acetone with a boiling range of 60℃-90℃, remove the grease on the surface of the coupons with absorbent cotton, and then soak them in anhydrous ethanol for about 5 minutes for further degreasing and dehydration. Take out the coupons and place them on filter paper, blow dry with cold air, wrap them with filter paper, and store them in a desiccator. After leaving them for 1 hour, measure the size and weigh them with an accuracy of 0.1mg.

[0086] According to the volume of the reactor, the simulated water on site was taken and put into the reactor. Nitrogen was first passed into the simulated water on site for 0.5h to remove the oxygen in the simulated water. Then the treated N80 corrosion coupon was hung. After the reactor cover was sealed, the CO2 pressure value required for the experiment was set according to the actual situation on site, and the reactor was kept at the actual temperature on site for static corrosion evaluation experiment. The experimental time was 72h. Three parallel experiments were carried out for each group of experiments, and the average value of the parallel experiments was taken as the measurement result.

[0087] Take out the coupons that have reached the experimental cycle, observe and record the surface corrosion state and the adhesion of corrosion products, immediately rinse off the experimental medium with clean water, and wipe the coupons dry with filter paper. Put the coupons into a container with petroleum ether or acetone with a boiling range of 60℃-90℃, wipe gently with absorbent cotton, and then soak them in anhydrous ethanol for 5 minutes for further degreasing and dehydration. Take out the coupons and soak them in the acid cleaning solution prepared according to Appendix A of SY / T5273-2000 standard for 5 minutes, and use tweezers to hold a small amount of absorbent cotton to gently wipe the corrosion products on the surface of the coupons. Take out the coupons from the cleaning solution, rinse the surface residual acid with tap water, and immediately immerse the coupons in sodium hydroxide solution (60g / L), rinse with tap water after 30s, and then soak them in anhydrous ethanol for about 5 minutes, and wash and dehydrate twice. Take out the hanging piece and place it on filter paper, blow it dry with cold air, then wrap the hanging piece with filter paper, store it in a desiccator, and weigh it after leaving it for 1 hour, with an accuracy of 0.1 mg.

[0088] Indoor evaluation test results:

[0089] The corrosion rate is calculated as follows:

[0090]

[0091] Where: r corr ——Uniform corrosion rate, mm / a; m——Mass of the coupon before the test, g; m t ——The weight of the coupon after the test, g; S1——The total area of ​​the coupon, cm 2 ; ρ——density of the hanging material, g / cm 3 ; t——test time, h.

[0092] The specific experimental results are shown in Table 2:

[0093] Table 2. Anticorrosion performance evaluation table

[0094] Evaluation Project Evaluation results Corrosion rate (blank) 3.962mm / a Corrosion rate (casing protection fluid) 0.026mm / a

[0095] On-site evaluation:

[0096] A coupon with a corrosion cycle of one month was taken out from the well. The coupon treatment and corrosion rate calculation steps after field corrosion were the same as those in the indoor experiment. After the casing protection fluid was injected into the field test well, the corrosion rate of the corrosion coupon was measured to be only 0.001mm / a.

[0097] Embodiment 3:

[0098] Synthesize 15 tons of casing protection fluid, the preparation method is as follows:

[0099] (1) Weigh 684 kg of water into a reaction kettle and begin heating to 40° C. while stirring;

[0100] (2) Weigh 60 kg of polyoxyethylene rosin amine into a reaction kettle and stir for 5 minutes;

[0101] (3) Weigh 60 kg of rosin imidazoline into the reactor and stir for 5 minutes;

[0102] (4) Weigh 60 kg of oleic acid imidazoline and add it into the reaction kettle, and stir for 5 minutes;

[0103] (5) Weigh 120 kg of amide imidazoline into the reactor and stir for 5 minutes;

[0104] (6) Weigh 96 kg of bisimidazoline corrosion inhibitor into the reactor and stir for 20 minutes;

[0105] (7) Weigh 120 kg of pulp waste liquid into the reactor and stir for 20 minutes;

[0106] (8) Stop heating and lower the temperature of the reactor to room temperature to obtain Agent A.

[0107] (9) Weigh 9075 kg of water at 15 m 3 In the mixing tank, add 225 kg of glycerol polyoxypropylene polyoxyethylene ether while stirring and stir for 15 minutes.

[0108] (10) Add 1200 kg of Agent A into the mixing tank, stirring for 15 minutes;

[0109] (11) Add 4500 kg of ethylene glycol and stir for 20 minutes to obtain a casing protection liquid.

[0110] In step (1), the reactor is heated to 40±1°C;

[0111] In steps (1)-(7), the stirring speed is 45 rpm.

[0112] In steps (9)-(11), the stirring speed is 60 rpm.

[0113] Effect evaluation of the casing protection liquid prepared in Example 3:

[0114] Indoor evaluation experimental steps:

[0115] Before the experiment, wipe the corrosion coupons with filter paper, then put them into a container filled with petroleum ether or acetone with a boiling range of 60℃-90℃, remove the grease on the surface of the coupons with absorbent cotton, and then soak them in anhydrous ethanol for about 5 minutes for further degreasing and dehydration. Take out the coupons and place them on filter paper, blow dry with cold air, wrap them with filter paper, and store them in a desiccator. After leaving them for 1 hour, measure the size and weigh them with an accuracy of 0.1mg.

[0116] According to the volume of the reactor, the simulated water on site was taken and put into the reactor. Nitrogen was first passed into the simulated water on site for 0.5h to remove the oxygen in the simulated water. Then the treated N80 corrosion coupon was hung. After the reactor cover was sealed, the CO2 pressure value required for the experiment was set according to the actual situation on site, and the reactor was kept at the actual temperature on site for static corrosion evaluation experiment. The experimental time was 72h. Three parallel experiments were carried out for each group of experiments, and the average value of the parallel experiments was taken as the measurement result.

[0117] Take out the coupons that have reached the experimental cycle, observe and record the surface corrosion state and the adhesion of corrosion products, immediately rinse off the experimental medium with clean water, and wipe the coupons dry with filter paper. Put the coupons into a container with petroleum ether or acetone with a boiling range of 60℃-90℃, wipe gently with absorbent cotton, and then soak them in anhydrous ethanol for 5 minutes for further degreasing and dehydration. Take out the coupons and soak them in the acid cleaning solution prepared according to Appendix A of SY / T5273-2000 standard for 5 minutes, and use tweezers to hold a small amount of absorbent cotton to gently wipe the corrosion products on the surface of the coupons. Take out the coupons from the cleaning solution, rinse the surface residual acid with tap water, and immediately immerse the coupons in sodium hydroxide solution (60g / L), rinse with tap water after 30s, and then soak them in anhydrous ethanol for about 5 minutes, and wash and dehydrate twice. Take out the hanging piece and place it on filter paper, blow it dry with cold air, then wrap the hanging piece with filter paper, store it in a desiccator, and weigh it after leaving it for 1 hour, with an accuracy of 0.1 mg.

[0118] Indoor evaluation test results:

[0119] The corrosion rate is calculated as follows:

[0120]

[0121] Where: r corr ——Uniform corrosion rate, mm / a; m——Mass of the coupon before the test, g; m t ——The weight of the coupon after the test, g; S1——The total area of ​​the coupon, cm 2 ; ρ——density of the hanging material, g / cm 3 ; t——test time, h.

[0122] The specific experimental results are shown in Table 2:

[0123] Table 3. Anticorrosion performance evaluation table

[0124]

[0125]

[0126] On-site evaluation:

[0127] A coupon with a corrosion cycle of one month was taken out from the well. The coupon treatment and corrosion rate calculation steps after field corrosion were the same as those in the indoor experiment. After the casing protection fluid was injected into the field test well, the corrosion rate of the corrosion coupon was measured to be only 0.001mm / a.

[0128] The above-described embodiments are only preferred embodiments of the present invention, but not all feasible embodiments of the present invention. For those skilled in the art, any obvious changes made thereto without departing from the principles and spirit of the present invention should be considered to be included in the scope of protection of the claims of the present invention.

Claims

1. A carbon dioxide driven casing protection fluid, characterized in that: The mass fraction ratio of each raw material component of casing protection liquid is:

2. A carbon dioxide flooding casing protection fluid as claimed in claim 1, characterized in that: The mass ratio of the raw material components of Agent A is:

3. A method for preparing a carbon dioxide flooding casing protection fluid according to any one of claims 1 to 2, characterized in that: Among them A The preparation method of the agent comprises: (1) Weigh water into a reaction kettle and heat it to 40°C while stirring; (2) Weigh polyoxyethylene rosin amine and add it into a reaction kettle, stirring for 5 minutes; (3) Weigh rosin imidazoline and add it into the reaction kettle, stirring for 5 minutes; (4) Weigh oleic acid imidazoline and add it into the reaction kettle, and stir for 5 minutes; (5) Weigh amide imidazoline and add it into the reaction kettle, and stir for 5 minutes; (6) Weigh the bisimidazoline corrosion inhibitor and add it to the reactor, stirring for 20 minutes; (7) Weigh the pulp waste liquid and add it into the reactor, stirring for 20 minutes; (8) Stop heating and lower the temperature of the reactor to room temperature to obtain Agent A.

4. The preparation method according to claim 3, characterized in that: The specific preparation is as follows: (a) Weigh water at 15m 3 In a mixing tank, add glycerol polyoxypropylene polyoxyethylene ether while stirring, and stir for 15 minutes; (b) Add Agent A to the mixing tank, stirring for 15 minutes; (c) adding ethylene glycol and stirring for 20 minutes to obtain a casing protection liquid.

5. The preparation method according to claim 4, characterized in that: In step (1), the reactor is heated to 40±1°C.

6. The preparation method according to claim 5, characterized in that: In steps (1)-(7), the stirring speed is 45 rpm.

7. The preparation method according to claim 6, characterized in that: In steps (a)-(c), the stirring speed is 60 rpm.

8. A method for preparing a carbon dioxide flooding casing protection fluid according to any one of claims 1 to 2, characterized in that: The details are as follows: (1) Weigh 180 kg to 708 kg of water into a reaction kettle and begin heating to 40° C. while stirring; (2) Weigh 30 kg to 120 kg of polyoxyethylene rosin amine into a reaction kettle and stir for 5 minutes; (3) Weigh 30 kg to 180 kg of rosin imidazoline into a reaction kettle and stir for 5 minutes; (4) Weigh 30 kg to 120 kg of oleic acid imidazoline into a reaction kettle and stir for 5 minutes; (5) Weigh 60 kg to 180 kg of amide imidazoline into a reaction kettle and stir for 5 minutes; (6) Weigh 48 kg to 120 kg of bisimidazoline corrosion inhibitor into the reactor and stir for 20 minutes; (7) Weigh 48 kg to 120 kg of pulp waste liquid into the reactor and stir for 20 minutes; (8) stopping heating and lowering the temperature of the reactor to room temperature to obtain Agent A; (9) Weigh 9075 kg - 11325 kg of water at 15m 3 In a stirring tank, add 75 kg to 225 kg of glycerol polyoxypropylene polyoxyethylene ether while stirring, and stir for 15 minutes; (10) Add 600 kg to 1200 kg of Agent A into a mixing tank, stirring for 15 minutes; (11) Add 3000 kg to 4500 kg of ethylene glycol and stir for 20 minutes to obtain a casing protection liquid.

9. Use of the casing protection fluid according to any one of claims 1 to 2 in a carbon dioxide injection well.

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