Leakage-proofing agent for CO2 geological storage and preparation method thereof

Abstract

The application discloses a leakage-preventing agent for CO2 geological storage, and a preparation method thereof. The structural formula of the leakage-preventing agent is as follows: R is a hydrophilic graft copolymer monomer; 5<=a<=15, and 10<=b<=20. The preparation method comprises the following steps: S1, adding polyvinyl alcohol and water into a reaction container, and then slowly adding vinyl acetate after the polyvinyl alcohol is completely dissolved; S2, adding an ammonium persulfate aqueous solution into the reaction container after the reaction, and then slowly adding the hydrophilic graft copolymer monomer after the reaction; S3, adding a compound emulsifier into water, and then adding the product II and tetraethyl orthosilicate into the water, so that the leakage-preventing agent for CO2 geological storage is obtained.

Description

Technical Field

[0001] This invention belongs to the field of sealing agents, specifically relating to a leak-proof agent for CO2 geological storage and its preparation method. Background Technology

[0002] Water injection refers to the process of injecting water into the oil reservoir through specialized injection wells during oilfield development. This maintains or restores the reservoir pressure, giving it strong driving force to improve the extraction speed and recovery rate.

[0003] Low-permeability reservoirs suffer from problems such as rapid formation energy depletion and insufficient natural energy supply, resulting in low efficiency of water injection extraction and an increasingly prominent problem of "inability to inject and production".

[0004] To address this issue, some oilfields have implemented CO2 flooding by injecting carbon dioxide under high temperature and pressure, thereby improving oil recovery. However, current CO2 sequestration relies on formation cement. Because of cracks in the formation, the cement becomes damp and is corroded and decomposed by CO2, leading to reduced sequestration effectiveness and even leakage, thus severely impacting the CO2 sequestration efficiency. Summary of the Invention

[0005] Purpose of the invention: In order to improve the CO2 sequestration efficiency in CO2 flooding and CO2-enhanced percolation oil recovery processes and achieve long-term CO2 sequestration, this invention discloses a leak-proof agent for CO2 geological storage and its preparation method.

[0006] Technical solution: A leak-proof agent for CO2 geological storage, with the following structural formula:

[0007]

[0008] Wherein, R is a hydrophilic graft copolymer monomer;

[0009] a and b are integers, 5≤a≤15, 10≤b≤20.

[0010] Furthermore, the hydrophilic graft copolymer monomer is one of acrylic acid, methyl acrylate, and ethyl acrylate.

[0011] A method for preparing a leak-proof agent for CO2 geological storage includes the following steps:

[0012] S1: Add polyvinyl alcohol and water to a reaction vessel, heat to 90-95 degrees Celsius, and after the polyvinyl alcohol is completely dissolved, cool to room temperature. Then add an emulsifier, heat to 60-65 degrees Celsius, add an appropriate amount of ammonium persulfate aqueous solution, and after the addition is complete, heat to 68-70 degrees Celsius. Slowly add vinyl acetate dropwise, and after the addition is complete, keep the reaction at this temperature for 15-20 minutes. Add an appropriate amount of ammonium persulfate aqueous solution again, heat to 80-85 degrees Celsius, and reflux for 2-3 hours. After the reaction is complete, add a certain amount of sodium bicarbonate aqueous solution to adjust the pH to 5-6 to obtain intermediate I.

[0013] S2: Add intermediate I obtained in step S1 to another reaction vessel, then heat to 50-55 degrees Celsius, add an appropriate amount of ammonium persulfate aqueous solution, and after completion, slowly add hydrophilic graft copolymer monomer to the reaction vessel, heat to 60-65 degrees Celsius, keep the reaction at this temperature for 1-2 hours, stir, and obtain product II by rotary evaporation;

[0014] S3: Add a compound emulsifier to water, and then add product II obtained from S2 and tetraethyl orthosilicate to water in a certain proportion to obtain a reaction system. After the reaction is completed, a leak-proof agent for CO2 geological storage is obtained.

[0015] The reaction vessel is a commonly used laboratory reaction vessel, such as a three-necked flask or a four-necked flask.

[0016] Preferably, the hydrophilic graft copolymer monomer mentioned in step S2 is one of acrylic acid, methyl acrylate, and ethyl acrylate.

[0017] Preferably, the amount of polyvinyl alcohol added in step S1 is 8-10% of the total mass of polyvinyl alcohol and water.

[0018] Preferably, the emulsifier in step S1 is a compound emulsifier of sodium dodecylbenzenesulfonate and OP-10 in equal mass ratio, and the amount of the compound emulsifier added is 4-7% of the amount of vinyl acetate added.

[0019] Preferably, the concentration of the ammonium persulfate aqueous solution in step S1 is 20 wt%, and the amount of ammonium persulfate aqueous solution added in step S1 is 4-6% of the amount of hydrophilic graft copolymer monomer added in step S2, wherein the first addition of the ammonium persulfate aqueous solution is 1 / 3 of its total addition amount, and the second addition is the remaining ammonium persulfate aqueous solution.

[0020] Preferably, the amount of vinyl acetate added in step S1 is 30% of the total mass of polyvinyl alcohol and water.

[0021] Further, in step S1, the pH is adjusted to 5-6 by adding an aqueous sodium bicarbonate solution.

[0022] Furthermore, the mass concentration of the sodium bicarbonate aqueous solution in step S1 is 10–30 wt%.

[0023] Preferably, the amount of hydrophilic graft copolymer monomer added in step S2 is 2 to 3 times the amount of vinyl acetate added.

[0024] Preferably, the mass concentration of the ammonium persulfate aqueous solution in step S2 is 20 wt%, and the amount of ammonium persulfate aqueous solution added in step S2 is 4-6% of the amount of hydrophilic graft copolymer monomer added in step S2.

[0025] Preferably, the compound emulsifier mentioned in step S3 is a compound emulsifier of emulsifier SP-60 and emulsifier TW60, with an HLB value of 10 to 12, and the amount of compound emulsifier added is 1-2% of the total mass of compound emulsifier and water.

[0026] Preferably, the mass ratio of product II obtained in step S2 to tetraethyl orthosilicate in step S3 is 2:(1-1.1).

[0027] Preferably, the amount of water added in step S3 is 60-70% of the mass of the reaction system in step S3.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The preparation method is simple and easy to implement, with a clear reaction mechanism. It improves the hydrophilicity of the polymerized product by grafting hydrophilic copolymer monomers onto polyvinyl acetate. A homogeneous emulsion is formed with tetraethyl orthosilicate using a compound emulsifier. Upon entering the formation, the emulsion is affected by the increased formation temperature. The polyvinyl acetate structure of the copolymer in the emulsion undergoes thermal dehydration and decomposition, exposing hydroxyl groups. Simultaneously, the tetraethyl orthosilicate is hydrolyzed by the formation environment (high temperature and low pH), generating silicic acid. This silicic acid reacts with the exposed hydroxyl groups of the copolymer to form a highly polymerized solid gel, thereby blocking cracks and pores and improving CO2 sealing efficiency. This method has excellent sealing effect and can achieve highly efficient CO2 sealing.

[0030] 2. The present invention provides a method for preparing a leak-proof agent for CO2 geological burial. First, vinyl acetate is polymerized to form polyvinyl acetate, which is then polymerized with a hydrophilic graft copolymer monomer to improve its hydrophilicity. Finally, a homogeneous emulsion is formed with tetraethyl orthosilicate and a compound emulsifier for application. This leak-proof agent for CO2 geological burial can form a high-strength solid gel, effectively sealing cracks and pores in CO2-bearing formations, thereby improving CO2 burial efficiency and preventing its escape. Attached Figure Description

[0031] Figure 1A schematic diagram of the experimental setup used to characterize the plugging performance.

[0032] in:

[0033] 1-Computer-aided data acquisition system 2-Pressure sensor 3-Intermediate Container Tank 4-Horizontal Flow Pump 5-Storage tank 6-Thermostatic Bath 7-Sand-filled pipe Detailed Implementation

[0034] The specific embodiments of the present invention are described in detail below.

[0035] This invention provides a method for preparing a leak-proof agent for CO2 geological burial. First, vinyl acetate is polymerized to form polyvinyl acetate. Then, it is polymerized with a hydrophilic graft copolymer monomer to improve its hydrophilicity. Finally, a homogeneous emulsion is formed with tetraethyl orthosilicate and a compound emulsifier for application. This leak-proof agent for CO2 geological burial can form a high-strength solid gel, effectively sealing cracks and pores in CO2-bearing formations, thereby improving CO2 burial efficiency and preventing its escape.

[0036] This invention discloses a method for preparing a leak-proof agent for CO2 geological storage, and its synthetic route is as follows:

[0037]

[0038] The mechanism by which tetraethyl orthosilicate is hydrolyzed at high temperature to form silicic acid is as follows:

[0039]

[0040] The mechanism by which leak-proof agents used in CO2 geological storage form solid gels is as follows:

[0041]

[0042] Example 1

[0043] A method for preparing a leak-proof agent for CO2 geological storage includes the following steps:

[0044] S1. Weigh 6.4g of polyvinyl alcohol and 80g of water into a reaction vessel (e.g., a 500mL three-necked flask equipped with a stirrer). Heat to 90°C and stir thoroughly until the polyvinyl alcohol is completely dissolved. Cool to room temperature, then add 0.52g of OP-10 and 0.52g of sodium dodecylbenzenesulfonate, respectively. After adding, heat to 60°C. Weigh 1g of ammonium persulfate in a 25mL beaker and dissolve in 5g of water until fully dissolved to obtain an ammonium persulfate solution. Add 1 / 3 of the prepared ammonium persulfate solution to the reaction vessel. Heat to 68°C and slowly add 26g of vinyl acetate dropwise. After the addition is complete, maintain the temperature for 15 minutes. Then add the remaining 2 / 3 of the ammonium persulfate solution, and heat to 80°C. Reflux for 2 hours. After the reaction is complete, add 10wt% sodium bicarbonate aqueous solution to adjust the pH to 5 to obtain intermediate I.

[0045] S2. Add intermediate I obtained in S1 to another reaction vessel (e.g., a three-necked flask), then heat to 50 degrees Celsius. Weigh 2g of ammonium persulfate in a 25mL beaker and dissolve it in 10g of water. After the ammonium persulfate solution is fully dissolved, add it to the reaction vessel. After the addition is complete, slowly add 52g of acrylic acid, heat to 60 degrees Celsius, keep the temperature for 1 hour, and then stir and rotary evaporate to obtain product II.

[0046] S3. Add 1g of compound emulsifier to 60g of water, then add 26.7g of the product obtained in step S2 and II and 13.3g of tetraethyl orthosilicate, and stir thoroughly to obtain the leak-proof agent for CO2 geological burial.

[0047] Further, the compound emulsifier mentioned in step S3 is a compound emulsifier of emulsifier SP-60 and emulsifier TW60, with an HLB value of 10.

[0048] Example 2

[0049] A method for preparing a leak-proof agent for CO2 geological storage includes the following steps:

[0050] S1. Weigh 8g of polyvinyl alcohol and 80g of water into a reaction vessel (e.g., a 500mL three-necked flask equipped with a stirrer). Heat to 95°C and stir thoroughly until the polyvinyl alcohol is completely dissolved. Cool to room temperature, then add 0.91g of OP-10 and 0.91g of sodium dodecylbenzenesulfonate, respectively. After addition, heat to 65°C. Weigh 1g of ammonium persulfate in a 25mL beaker and dissolve in 5g of water until fully dissolved to obtain an ammonium persulfate solution. Add 1 / 3 of the prepared ammonium persulfate solution to the reaction vessel. Heat to 70°C and slowly add 26g of vinyl acetate dropwise. After the addition is complete, maintain the temperature for 20 minutes. Then add the remaining 2 / 3 of the ammonium persulfate solution, and heat to 85°C. Reflux for 3 hours. After the reaction is complete, add 30wt% sodium bicarbonate aqueous solution to adjust the pH to 6 to obtain intermediate I.

[0051] S2. Add intermediate I obtained in S1 to another reaction vessel (e.g., a three-necked flask), and then heat to 55 degrees Celsius. Weigh 3g of ammonium persulfate into 15g of water in a 25mL beaker, and after it is fully dissolved to obtain an ammonium persulfate solution, add it to the reaction vessel. After the addition is complete, slowly add 78g of acrylic acid, heat to 65 degrees Celsius, and maintain the temperature for 2 hours. After stirring and rotary evaporation, obtain product II.

[0052] S3. Add 2g of compound emulsifier to 60g of water, then add 26.4g of product II from step S2 and 13.6g of tetraethyl orthosilicate, and stir thoroughly to obtain the leak-proof agent for CO2 geological storage.

[0053] Example 3

[0054] A method for preparing a leak-proof agent for CO2 geological storage includes the following steps:

[0055] S1. Weigh 6.4g of polyvinyl alcohol and 80g of water into a reaction vessel (e.g., a 500mL three-necked flask equipped with a stirrer). Heat to 94°C and stir thoroughly until the polyvinyl alcohol is completely dissolved. Cool to room temperature, then add 0.8g of OP-10 and 0.8g of sodium dodecylbenzenesulfonate, respectively. After addition, heat to 62°C. Weigh 1g of ammonium persulfate in a 25mL beaker and dissolve in 5g of water until fully dissolved to obtain an ammonium persulfate solution. Add 1 / 3 of the prepared ammonium persulfate solution to the reaction vessel. Heat to 69°C and slowly add 26g of vinyl acetate dropwise. After the addition is complete, maintain the temperature for 18 minutes. Then add the remaining 2 / 3 of the ammonium persulfate solution, and heat to 82°C. Reflux for 2.5 hours. After the reaction is complete, add 20wt% sodium bicarbonate aqueous solution to adjust the pH to 5.5 to obtain intermediate I.

[0056] S2. Add intermediate I obtained in S1 to another reaction vessel (e.g., a three-necked flask), and then heat to 55 degrees Celsius. Weigh 2g of ammonium persulfate into a 25mL beaker and dissolve it in 10g of water. After the ammonium persulfate solution is fully dissolved, add it to the three-necked flask. After the addition is complete, slowly add 78g of methyl acrylate, heat to 60 degrees Celsius, and maintain the temperature for 2 hours. After stirring and rotary evaporation, obtain product II.

[0057] S3. Add 2g of compound emulsifier to 60g of water, then add 26.7g of product II from step S2 and 13.3g of tetraethyl orthosilicate, and stir thoroughly to obtain the leak-proof agent for CO2 geological storage.

[0058] Example 4

[0059] A method for preparing a leak-proof agent for CO2 geological storage includes the following steps:

[0060] S1. Weigh 8g of polyvinyl alcohol and 80g of water into a reaction vessel (e.g., a 500mL three-necked flask equipped with a stirrer). Heat to 90°C and stir thoroughly until the polyvinyl alcohol is completely dissolved. Cool to room temperature, then add 0.65g of OP-10 and 0.65g of sodium dodecylbenzenesulfonate, respectively. After addition, heat to 60°C. Weigh 1g of ammonium persulfate into a 25mL beaker and dissolve in 5g of water until fully dissolved to obtain an ammonium persulfate solution. Add 1 / 3 of the prepared ammonium persulfate solution to the reaction vessel. Heat to 70°C and slowly add 26g of vinyl acetate dropwise. After the addition is complete, maintain the temperature for 20 minutes. Then add the remaining 2 / 3 of the ammonium persulfate solution, and heat to 85°C. Reflux for 3 hours. After the reaction is complete, add 15wt% sodium bicarbonate aqueous solution to adjust the pH to 6 to obtain intermediate I.

[0061] S2. Add intermediate I obtained in S1 to another reaction vessel (e.g., a three-necked flask), and then heat to 60 degrees Celsius. Weigh 2g of ammonium persulfate into a 25mL beaker and dissolve it in 10g of water. After the ammonium persulfate solution is fully dissolved, add it to the reaction vessel. After the addition is complete, slowly add 52g of methyl acrylate, heat to 65 degrees Celsius, and maintain the temperature for 2 hours. After stirring and rotary evaporation, obtain product II.

[0062] S3. Add 1g of compound emulsifier to 60g of water, then add 26.1g of product II from step S2 and 13.9g of tetraethyl orthosilicate, and stir thoroughly to obtain the leak-proof agent for CO2 geological storage.

[0063] Example 5

[0064] A method for preparing a leak-proof agent for CO2 geological storage includes the following steps:

[0065] S1. Weigh 6.4g of polyvinyl alcohol and 80g of water into a reaction vessel (e.g., a 500mL three-necked flask equipped with a stirrer). Heat to 90°C and stir thoroughly until the polyvinyl alcohol is completely dissolved. Cool to room temperature, then add 0.6g of OP-10 and 0.6g of sodium dodecylbenzenesulfonate, respectively. After adding, heat to 65°C. Weigh 1g of ammonium persulfate in a 25mL beaker and dissolve in 5g of water until fully dissolved to obtain an ammonium persulfate solution. Add 1 / 3 of the prepared ammonium persulfate solution to the reaction vessel. Heat to 68°C and slowly add 26g of vinyl acetate dropwise. After the addition is complete, maintain the temperature for 20 minutes. Then add the remaining 2 / 3 of the ammonium persulfate solution, and heat to 80°C. Reflux for 3 hours. After the reaction is complete, add 10wt% sodium bicarbonate aqueous solution to adjust the pH to 5-6 to obtain intermediate I.

[0066] S2. Add intermediate I obtained in S1 to another reaction vessel (e.g., a three-necked flask), and then heat to 60 degrees Celsius. Weigh 2g of ammonium persulfate into a 25mL beaker and dissolve it in 10g of water. After the ammonium persulfate solution is fully dissolved, add it to the reaction vessel. After the addition is complete, slowly add 52g of ethyl acrylate, heat to 65 degrees Celsius, and maintain the temperature for 2 hours. Then, stir and rotary evaporate to obtain product II.

[0067] S3. Add 1g of compound emulsifier to 60g of water, then add 26.7g of product II from step S2 and 13.3g of tetraethyl orthosilicate, and stir thoroughly to obtain the leak-proof agent for CO2 geological storage.

[0068] Example 6

[0069] A method for preparing a leak-proof agent for CO2 geological storage includes the following steps:

[0070] S1. Weigh 8g of polyvinyl alcohol and 80g of water into a reaction vessel (e.g., a 500mL three-necked flask equipped with a stirrer). Heat to 90°C and stir thoroughly until the polyvinyl alcohol is completely dissolved. Cool to room temperature, then add 0.9g of OP-10 and 0.9g of sodium dodecylbenzenesulfonate, respectively. After addition, heat to 60°C. Weigh 1g of ammonium persulfate in a 25mL beaker and dissolve in 5g of water until fully dissolved to obtain an ammonium persulfate solution. Add 1 / 3 of the prepared ammonium persulfate solution to the three-necked flask. Heat to 68°C and slowly add 26g of vinyl acetate dropwise. After the addition is complete, maintain the temperature for 20 minutes. Then add the remaining 2 / 3 of the ammonium persulfate solution, and heat to 80°C. Reflux for 3 hours. After the reaction is complete, add 25wt% sodium bicarbonate aqueous solution to adjust the pH to 6 to obtain intermediate I.

[0071] S2. Add intermediate I obtained in S1 to a three-necked flask, and then heat to 60 degrees Celsius. Weigh 3g of ammonium persulfate into a 25mL beaker and dissolve it in 15g of water. After the ammonium persulfate solution is fully dissolved, add it to the three-necked flask. After the addition is complete, slowly add 78g of ethyl acrylate, heat to 65 degrees Celsius, and maintain the temperature for 2 hours. After stirring and rotary evaporation, obtain product II.

[0072] S3. Add 1g of compound emulsifier to 60g of water, then add 26.7g of product II from step S2 and 13.3g of tetraethyl orthosilicate, and stir thoroughly to obtain the leak-proof agent for CO2 geological storage.

[0073] Performance Characterization

[0074] 1. The effect of temperature on leak-proof agents for CO2 geological storage

[0075] To characterize the effect of temperature on the formation of solid gel in a CO2 geological burial sealant, the CO2 geological burial sealant obtained in Example 2 was placed in a glass bottle, acid was added to adjust the pH to 6, and the solid precipitation was observed by heating.

[0076] The experimental results show that the leak-proof agent for CO2 geological burial does not precipitate solid gel at room temperature. When the temperature rises to 80 degrees Celsius, solid gel is precipitated. At the same time, as the temperature continues to rise, the amount of solid precipitate does not change. This indicates that temperature only affects the precipitation rate of solid gel and has no effect on the solid gel itself. This means that temperature does not change the sealing efficiency of the leak-proof agent for CO2 geological burial.

[0077] 2. Sealing performance

[0078] To characterize the sealing performance of a leak-proof agent for CO2 geological storage, the following methods were used: Figure 1 The device shown was used for a sealing test experiment.

[0079] like Figure 1 As shown, the liquid storage tank 5, the horizontal flow pump 4, the intermediate container tank 3, and the constant temperature bath 6 are connected in sequence. The constant temperature bath 6 is equipped with a sand filling pipe 7. A pressure sensor 2 is installed in the pipe connecting the intermediate container tank 3 and the constant temperature bath 6. The output end of the pressure sensor 2 is connected to the input end of the computer acquisition system 1.

[0080] Sand-filled tubes 7 with different permeabilities were fabricated using the wet-filling method, and the porosity was calculated. Water was then injected at a rate of 0.5 mL / min, and the aqueous phase permeability of the sand-filled tubes 7 was calculated. Subsequently, 1.0 PV of the CO2 geological burial sealant obtained in Example 2 was injected into each sand-filled tube. The valves at both ends of the sand-filled tubes were closed, and the constant temperature bath 6 was maintained at 80 degrees Celsius to form a solid gel. Water was then injected at a rate of 0.5 mL / min, and the pressure at the injection end was recorded to calculate the sealing rate. The experimental results are shown in Tables 1 and 2.

[0081] Table 1 Basic Parameters of Sand-filled Pipes

[0082]

[0083] Table 2. Sealing effect of sand-filled pipes

[0084]

[0085] As can be seen from Table 2, the sealing rate of the CO2 geological burial anti-leakage agent obtained by this method is all above 95%, indicating that the CO2 geological burial anti-leakage agent has an excellent sealing effect on cracks and pores in the formation and can prevent CO2 from escaping.

[0086] 3. Thermal stability

[0087] To characterize the thermal stability of a leak-proof agent for CO2 geological storage, thermal stability experiments were conducted using sand-filled tubes as shown in Table 1. The leak-proof agent for CO2 geological storage obtained in Example 2 was added to the sand-filled tubes. Example 2 used the 1-1 sand-filled tube, which was then sealed and stored in a 150°C oven. The tubes were removed after 10, 30, and 90 days, respectively, and the thermal stability was then assessed. Figure 1 The testing methods for the device and its plugging performance were described, and the plugging rate was calculated for different aging times. The experimental results are shown in Table 3.

[0088] Table 3. Sealing effect of sand-filled pipes at different aging times

[0089]

[0090] As shown in Table 3, the plugging pressure differential gradually decreases with increasing aging time, but the decrease in plugging rate is very small. After 90 days, the plugging rate is 0.16% lower than the initial rate, but the plugging rate is still greater than 95%. Therefore, this plugging agent has good thermal stability.

[0091] Example 7

[0092] A leak-proof agent for CO2 geological storage, with the following structural formula:

[0093]

[0094] Wherein, R is a hydrophilic graft copolymer monomer;

[0095] a and b are integers, where a = 5 and b = 10.

[0096] Furthermore, the hydrophilic graft copolymer monomer is acrylic acid.

[0097] Example 8

[0098] A leak-proof agent for CO2 geological storage, with the following structural formula:

[0099]

[0100] Wherein, R is a hydrophilic graft copolymer monomer;

[0101] a and b are integers, where a = 10 and b = 15.

[0102] Furthermore, the hydrophilic graft copolymer monomer is methyl acrylate.

[0103] Example 9

[0104] A leak-proof agent for CO2 geological storage, with the following structural formula:

[0105]

[0106] Wherein, R is a hydrophilic graft copolymer monomer;

[0107] a and b are integers, where a = 15 and b = 20.

[0108] Furthermore, the hydrophilic graft copolymer monomer is ethyl acrylate.

[0109] Example 10

[0110] A method for preparing a leak-proof agent for CO2 geological storage includes the following steps:

[0111] S1: Add polyvinyl alcohol and water to the reaction vessel, heat to 90 degrees Celsius, and after the polyvinyl alcohol is completely dissolved, cool to room temperature. Then add emulsifier, heat to 60 degrees Celsius, add an appropriate amount of ammonium persulfate aqueous solution, heat to 68 degrees Celsius after the addition is complete, slowly add vinyl acetate dropwise, keep the reaction temperature for 15 minutes after the addition is complete, add an appropriate amount of ammonium persulfate aqueous solution again, heat to 80 degrees Celsius, reflux for 3 hours, after the reaction is complete, add a certain amount of sodium bicarbonate aqueous solution to adjust the pH to 5, and obtain intermediate I;

[0112] S2: Add intermediate I obtained in step S1 to another reaction vessel, then heat to 50 degrees Celsius, add an appropriate amount of ammonium persulfate aqueous solution, and after completion, slowly add hydrophilic graft copolymer monomer to the reaction vessel, heat to 60 degrees Celsius, keep the reaction at this temperature for 2 hours, stir, and obtain product II by rotary evaporation;

[0113] S3: Add a compound emulsifier to water, and then add product II obtained from S2 and tetraethyl orthosilicate to water in a certain proportion to obtain a reaction system. After the reaction is completed, a leak-proof agent for CO2 geological storage is obtained.

[0114] The reaction vessel is a commonly used laboratory reaction vessel, such as a three-necked flask.

[0115] Preferably, the hydrophilic graft copolymer monomer in step S2 is acrylic acid.

[0116] Preferably, the amount of polyvinyl alcohol added in step S1 is 8% of the total mass of polyvinyl alcohol and water.

[0117] Preferably, the emulsifier in step S1 is a compound emulsifier of sodium dodecylbenzenesulfonate and OP-10 in equal mass ratio, and the amount of the compound emulsifier added is 4% of the amount of vinyl acetate added.

[0118] Preferably, the concentration of the ammonium persulfate aqueous solution in step S1 is 20 wt%, and the amount of ammonium persulfate aqueous solution added in step S1 is 4% of the amount of hydrophilic graft copolymer monomer added in step S2, wherein the first addition of the ammonium persulfate aqueous solution is 1 / 3 of its total addition, and the second addition is the remaining ammonium persulfate aqueous solution.

[0119] Preferably, the amount of vinyl acetate added in step S1 is 30% of the total mass of polyvinyl alcohol and water.

[0120] Further, in step S1, the pH is adjusted to 5 by adding an aqueous sodium bicarbonate solution.

[0121] Furthermore, the sodium bicarbonate aqueous solution described in step S1 has a mass concentration of 10 wt%.

[0122] Preferably, the amount of hydrophilic graft copolymer monomer added in step S2 is twice the amount of vinyl acetate added.

[0123] Preferably, the mass concentration of the ammonium persulfate aqueous solution in step S2 is 20 wt%, and the amount of ammonium persulfate aqueous solution added in step S2 is 4 wt% of the amount of hydrophilic graft copolymer monomer added in step S2.

[0124] Preferably, the compound emulsifier mentioned in step S3 is a compound emulsifier of emulsifier SP-60 and emulsifier TW60, with an HLB value of 10, and the amount of compound emulsifier added is 1 wt% of the total mass of compound emulsifier and water.

[0125] Preferably, the mass ratio of product II obtained in step S2 to tetraethyl orthosilicate in step S3 is 2:1.

[0126] Preferably, the amount of water added in step S3 is 60 wt% of the mass of the reaction system described in step S3.

[0127] Example 11

[0128] A method for preparing a leak-proof agent for CO2 geological storage includes the following steps:

[0129] S1: Add polyvinyl alcohol and water to the reaction vessel, heat to 95 degrees Celsius, and after the polyvinyl alcohol is completely dissolved, cool to room temperature. Then add emulsifier, heat to 65 degrees Celsius, add an appropriate amount of ammonium persulfate aqueous solution, heat to 70 degrees Celsius after the addition is complete, slowly add vinyl acetate dropwise, keep the reaction temperature for 20 minutes after the addition is complete, add an appropriate amount of ammonium persulfate aqueous solution again, heat to 85 degrees Celsius, reflux for 2 hours, after the reaction is complete, add a certain amount of sodium bicarbonate aqueous solution to adjust the pH to 6, and obtain intermediate I;

[0130] S2: Add intermediate I obtained in step S1 to another reaction vessel, then heat to 55 degrees Celsius, add an appropriate amount of ammonium persulfate aqueous solution, and after completion, slowly add hydrophilic graft copolymer monomer to the reaction vessel, heat to 65 degrees Celsius, keep the reaction at this temperature for 1 hour, stir, and obtain product II by rotary evaporation;

[0131] S3: Add a compound emulsifier to water, and then add product II obtained from S2 and tetraethyl orthosilicate to water in a certain proportion to obtain a reaction system. After the reaction is completed, a leak-proof agent for CO2 geological storage is obtained.

[0132] The reaction vessel is a commonly used laboratory reaction vessel, such as a four-necked flask.

[0133] Preferably, the hydrophilic graft copolymer monomer in step S2 is methyl acrylate.

[0134] Preferably, the amount of polyvinyl alcohol added in step S1 is 10% of the total mass of polyvinyl alcohol and water.

[0135] Preferably, the emulsifier in step S1 is a compound emulsifier of sodium dodecylbenzenesulfonate and OP-10 in equal mass ratio, and the amount of the compound emulsifier added is 7% of the amount of vinyl acetate added.

[0136] Preferably, the concentration of the ammonium persulfate aqueous solution in step S1 is 20 wt%, and the amount of ammonium persulfate aqueous solution added in step S1 is 6% of the amount of hydrophilic graft copolymer monomer added in step S2, wherein the first addition of the ammonium persulfate aqueous solution is 1 / 3 of its total addition, and the second addition is the remaining ammonium persulfate aqueous solution.

[0137] Preferably, the amount of vinyl acetate added in step S1 is 30% of the total mass of polyvinyl alcohol and water.

[0138] Further, in step S1, the pH is adjusted to 6 by adding an aqueous sodium bicarbonate solution.

[0139] Furthermore, the sodium bicarbonate aqueous solution described in step S1 has a mass concentration of 30 wt%.

[0140] Preferably, the amount of hydrophilic graft copolymer monomer added in step S2 is 3 times the amount of vinyl acetate added.

[0141] Preferably, the mass concentration of the ammonium persulfate aqueous solution in step S2 is 20 wt%, and the amount of ammonium persulfate aqueous solution added in step S2 is 6 wt% of the amount of hydrophilic graft copolymer monomer added in step S2.

[0142] Preferably, the compound emulsifier mentioned in step S3 is a compound emulsifier of emulsifier SP-60 and emulsifier TW60, with an HLB value of 12, and the amount of compound emulsifier added is 2wt% of the total mass of compound emulsifier and water.

[0143] Preferably, the mass ratio of product II obtained in step S2 to tetraethyl orthosilicate in step S3 is 2:1.1.

[0144] Preferably, the amount of water added in step S3 is 70 wt% of the mass of the reaction system described in step S3.

[0145] Example 12

[0146] A method for preparing a leak-proof agent for CO2 geological storage includes the following steps:

[0147] S1: Add polyvinyl alcohol and water to the reaction vessel, heat to 93 degrees Celsius, and after the polyvinyl alcohol is completely dissolved, cool to room temperature, then add emulsifier, heat to 62 degrees Celsius, add an appropriate amount of ammonium persulfate aqueous solution, heat to 69 degrees Celsius after the addition is complete, slowly add vinyl acetate dropwise, keep the reaction temperature for 18 minutes after the addition is complete, add an appropriate amount of ammonium persulfate aqueous solution again, heat to 82 degrees Celsius, reflux for 2-3 hours, after the reaction is complete, add a certain amount of sodium bicarbonate aqueous solution to adjust the pH to 5.5, to obtain intermediate I;

[0148] S2: Add intermediate I obtained in step S1 to another reaction vessel, then heat to 52 degrees Celsius, add an appropriate amount of ammonium persulfate aqueous solution, and after completion, slowly add hydrophilic graft copolymer monomer to the reaction vessel, heat to 62 degrees Celsius, keep the reaction at this temperature for 1.5 hours, stir, and rotary evaporate to obtain product II;

[0149] S3: Add a compound emulsifier to water, and then add product II obtained from S2 and tetraethyl orthosilicate to water in a certain proportion to obtain a reaction system. After the reaction is completed, a leak-proof agent for CO2 geological storage is obtained.

[0150] The reaction vessel is a commonly used laboratory reaction vessel, such as a three-necked flask.

[0151] Preferably, the hydrophilic graft copolymer monomer in step S2 is ethyl acrylate.

[0152] Preferably, the amount of polyvinyl alcohol added in step S1 is 9% of the total mass of polyvinyl alcohol and water.

[0153] Preferably, the emulsifier in step S1 is a compound emulsifier of sodium dodecylbenzenesulfonate and OP-10 in equal mass ratio, and the amount of the compound emulsifier added is 5% of the amount of vinyl acetate added.

[0154] Preferably, the concentration of the ammonium persulfate aqueous solution in step S1 is 20 wt%, and the amount of ammonium persulfate aqueous solution added in step S1 is 5% of the amount of hydrophilic graft copolymer monomer added in step S2, wherein the first addition of the ammonium persulfate aqueous solution is 1 / 3 of its total addition amount, and the second addition is the remaining ammonium persulfate aqueous solution.

[0155] Preferably, the amount of vinyl acetate added in step S1 is 30% of the total mass of polyvinyl alcohol and water.

[0156] Further, in step S1, the pH is adjusted to 5.5 by adding an aqueous sodium bicarbonate solution.

[0157] Furthermore, the mass concentration of the sodium bicarbonate aqueous solution in step S1 is 20 wt%.

[0158] Preferably, the amount of hydrophilic graft copolymer monomer added in step S2 is 2.5 times the amount of vinyl acetate added.

[0159] Preferably, the mass concentration of the ammonium persulfate aqueous solution in step S2 is 20 wt%, and the amount of ammonium persulfate aqueous solution added in step S2 is 5% of the amount of hydrophilic graft copolymer monomer added in step S2.

[0160] Preferably, the compound emulsifier mentioned in step S3 is a compound emulsifier of emulsifier SP-60 and emulsifier TW60, with an HLB value of 10 to 12, and the amount of compound emulsifier added is 1.5 wt% of the total mass of compound emulsifier and water.

[0161] Preferably, the mass ratio of product II obtained in step S2 to tetraethyl orthosilicate in step S3 is 2:1.05.

[0162] Preferably, the amount of water added in step S3 is 65% of the mass of the reaction system in step S3.

[0163] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.

Claims

1. A method for preparing a leak prevention agent for CO2 geological storage, characterized by, Comprise the following steps: S1: add polyvinyl alcohol and water in the reaction container, warm up to 90-95 degrees Celsius, after the polyvinyl alcohol is completely dissolved, cool to room temperature, then add emulsifier, warm up to 60-65 degrees Celsius, add the appropriate amount of ammonium persulfate aqueous solution, after adding, warm up to 68-70 degrees Celsius, slowly add vinyl acetate, after the dropwise addition is completed, keep warm for 15-20 min, add the appropriate amount of ammonium persulfate aqueous solution again, warm up to 80-85 degrees Celsius, reflux for 2-3 h, after the reaction is completed, add a certain amount of sodium bicarbonate aqueous solution to adjust the pH to 5-6, obtain intermediate I; S2: add the intermediate I obtained in step S1 to another reaction container, then warm up to 50-55 degrees Celsius, add the appropriate amount of ammonium persulfate aqueous solution, after completion, slowly add the hydrophilic graft copolymer monomer to the reaction container, warm up to 60-65 degrees Celsius, keep warm for 1-2 h, stir, rotary evaporation to obtain product II; S3: add the compound emulsifier in water, then add the product II obtained in S2 and tetraethyl orthosilicate to the water to obtain a reaction system, after the reaction is completed, the CO2 geological storage leak-proof agent is obtained.

2. The method of claim 1, wherein the leak prevention agent for CO2 geological storage is prepared by the steps of: The hydrophilic graft copolymer monomer in step S2 is one of acrylic acid, methyl acrylate and ethyl acrylate. ​ 3. The method of claim 1, wherein the leak prevention agent for CO2 geological storage is prepared by the steps of: The addition amount of polyvinyl alcohol in step S1 is 8-10% of the total mass of polyvinyl alcohol and water. ​ 4. The method of claim 1, wherein the leak prevention agent for CO2 geological storage is prepared by the steps of: The emulsifier in step S1 is a compound emulsifier of sodium dodecyl benzene sulfonate and OP-10 with equal mass ratio, and the addition amount of the compound emulsifier is 4-7% of the addition amount of vinyl acetate. ​ 5. The method of claim 1, wherein the leak prevention agent for CO2 geological storage is prepared by the steps of: The concentration of the ammonium persulfate aqueous solution in step S1 is 20wt%, and the addition amount of the ammonium persulfate aqueous solution in step S1 is 4-6% of the addition amount of the hydrophilic graft copolymer monomer in step S2, wherein the first addition amount of the ammonium persulfate aqueous solution is 1 / 3 of the total addition amount, and the second addition amount is the remaining ammonium persulfate aqueous solution. ​ 6. The method of claim 1, wherein the leak prevention agent for CO2 geological storage is prepared by the steps of: The addition amount of vinyl acetate in step S1 is 30% of the total mass of polyvinyl alcohol and water. ​ 7. The method for preparing a leak-proof agent for CO2 geological storage as described in claim 1, characterized in that, Step S1 adjusts the pH to 5-6 by adding sodium bicarbonate aqueous solution; The mass concentration of the sodium bicarbonate aqueous solution in step S1 is 10-30wt%.

8. The method of claim 1, wherein the leak prevention agent for CO2 geological storage is prepared by the steps of: The addition amount of the hydrophilic graft copolymer monomer in step S2 is 2-3 times of the addition amount of vinyl acetate. ​ 9. The method of claim 1, wherein the leak prevention agent for CO2 geological storage is prepared by the steps of: The mass concentration of the ammonium persulfate aqueous solution in step S2 is 20wt%, and the addition amount of the ammonium persulfate aqueous solution in step S2 is 4-6% of the addition amount of the hydrophilic graft copolymer monomer in step S2. ​ 10. The method of claim 1, wherein the leak prevention agent for CO2 geological storage is prepared by the steps of: The compound emulsifier in step S3 is a compound emulsifier of emulsifier SP-60 and emulsifier TW60, with HLB value of 10-12, and the addition amount of the compound emulsifier is 1-2% of the total mass of the compound emulsifier and water. ​ 11. The method of claim 1, wherein the leak prevention agent for CO2 geological storage is prepared by the steps of: The mass ratio of the product II obtained in step S2 to tetraethyl orthosilicate in step S3 is 2:(1-1.1); ​ The addition amount of water in step S3 is 60-70% of the mass of the reaction system in step S3.

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