Gas extraction drilling and hole sealing material with CO reaching standard and preparation method of gas extraction drilling and hole sealing material

Abstract

The invention provides a gas extraction drilling hole sealing material with CO reaching the standard and a preparation method thereof, and relates to the field of coal mining. The concrete comprises the following raw materials in parts by weight: 90-100 parts of cement, 3-10 parts of an accelerator, 5-15 parts of anhydrous sodium sulphate, 1-2.5 parts of a water reducing agent, 1-4 parts of methyl cellulose, 1.5-6 parts of sodium percarbonate, 3-5 parts of modified montmorillonite, 1-3 parts of porous alumina particles and 1-3 parts of polyvinyl alcohol. The preparation method comprises the following steps: uniformly mixing sodium percarbonate and porous alumina to obtain a first mixture; mixing polyvinyl alcohol and water, heating and stirring, adding the modified montmorillonite, stirring for 1-2 hours, standing for 20-24 hours, drying and grinding to obtain a second mixture; and uniformly mixing the first mixture, the second mixture and other raw materials. The hole sealing material does not generate CO, and has the advantages of being high in fluidity, large in expansion rate, uniform in distribution, high in compressive strength and good in compactness.

Description

Technical Field

[0001] The present invention relates to the field of coal mining, and in particular to a CO2-compliant gas extraction drilling sealing material and a preparation method thereof. Background Art

[0002] Domestic coal mines mainly drill extraction holes at certain intervals along the coal seam and then directly connect them to the extraction pipeline to extract gas. This extraction technology requires the sealing of the extraction holes to improve the extraction effect.

[0003] At present, the main sealing materials are cement mortar and polyurethane. Cement mortar sealing is to mix expansive cement and sand with water to make cement mortar, and seal the hole manually or with a mechanical pump. The cement mortar has high strength after sealing the hole, and has good support for the extraction pipe, and is widely used in gas extraction. Patent 201610142375.0 discloses a gas extraction drilling sealing material, which is composed of 85-95% ordinary cement and 5-15% additives. The preparation method is as follows: the additive is a mixture of iron powder: aluminum powder, ammonium chloride, water reducer, pull-open powder, sodium thiosulfate and sodium chloride, iron powder: aluminum powder: ammonium chloride: water reducer: pull-open powder: sodium thiosulfate: sodium chloride = 19000:1:160:80:60:300:240. The sealing material has low cost and good sealing and extraction effect. However, during the use of the sealing material, CO will be generated, which affects the concentration of CO in the mine and does not meet environmental protection requirements. Summary of the invention

[0004] The purpose of the present invention is to provide a gas extraction borehole sealing material that meets CO standards. The material generates oxygen through the reaction of sodium percarbonate and water, and uses the expansion of oxygen to seal boreholes and cracks. When used, it generates oxygen but does not generate CO, thus meeting environmental protection requirements.

[0005] Another object of the present invention is to provide a method for preparing a gas extraction drilling sealing material that meets CO standards. The preparation method is simple and can be industrially produced.

[0006] The present invention solves the technical problem by adopting the following technical solutions.

[0007] On the one hand, an embodiment of the present invention provides a CO2-compliant gas extraction drilling sealing material, which includes the following raw materials by weight: 90-100 parts of cement, 3-10 parts of accelerator, 5-15 parts of sodium sulfate, 1-2.5 parts of water reducer, 1-4 parts of methyl cellulose, 1.5-6 parts of sodium percarbonate, 3-5 parts of modified montmorillonite, 1-3 parts of porous alumina particles, and 1-3 parts of polyvinyl alcohol.

[0008] In some embodiments of the present invention, the following raw materials are included by weight: 90 parts of cement, 3 parts of accelerator, 5 parts of sodium sulfate, 1.5 parts of water reducer, 2 parts of methyl cellulose, 3 parts of sodium percarbonate, 3 parts of modified montmorillonite, 2 parts of porous alumina particles, and 3 parts of polyvinyl alcohol.

[0009] In some embodiments of the present invention, the modified montmorillonite is prepared by the following method:

[0010] The montmorillonite and the polyol aqueous solution are mixed evenly, subjected to ultrasonic oscillation for 10-30 minutes, allowed to stand, and the supernatant is removed; subsequently, the cuprous compound is added, mixed evenly, subjected to treatment in a supercritical CO2 atmosphere for 30-60 minutes, and dried.

[0011] In some embodiments of the present invention, the polyol is ethylene glycol, glycerol or a mixture of the two.

[0012] In some embodiments of the present invention, the cuprous compound is a mixture of one or more of cuprous chloride, cuprous bromide, and cuprous acetate.

[0013] In some embodiments of the present invention, the mass ratio of the montmorillonite to the cuprous compound is 1:(0.1-0.5).

[0014] In some embodiments of the present invention, the particle size of the porous alumina particles is 0.1-0.5 mm.

[0015] In some embodiments of the present invention, the water reducing agent is one of calcium lignin sulfonate and sodium lignin sulfonate.

[0016] On the other hand, an embodiment of the present invention provides a method for preparing a CO2-compliant gas extraction borehole sealing material, comprising the following steps:

[0017] S1, mixing sodium percarbonate and porous alumina uniformly to obtain a first mixture;

[0018] S2, mixing polyvinyl alcohol and water, heating and stirring, then adding the modified montmorillonite, stirring for 1-2 hours, standing for 20-24 hours, drying and grinding to obtain a second mixture;

[0019] S3, uniformly mixing the first mixture, the second mixture and the remaining raw materials.

[0020] In some embodiments of the present invention, in step S2, the mass ratio of the polyvinyl alcohol to water is 1:(1-2).

[0021] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects:

[0022] The sealing material provided by the present invention can quickly and effectively penetrate into the cracks of the coal body around the borehole, merge with the coal body, and undergo an expansion reaction, so that the sealing material and the coal body fit together to achieve the best sealing effect. It effectively solves the problem of low concentration and fast attenuation of the extraction borehole due to poor sealing effect. It has the advantages of strong fluidity, large expansion rate and uniform distribution, high compressive strength and good density.

[0023] It uses cement as the main raw material, mixed with sodium percarbonate, modified montmorillonite, porous alumina particles, etc. When used, it is added and mixed into a slurry. Sodium percarbonate is hydrolyzed into hydrogen peroxide in water, and further decomposed into oxygen, which makes the cement expand and enter the cracks. As the cement solidifies, the drilled holes and cracks are sealed. In this process, the sealing material does not produce CO, which meets the relevant national requirements.

[0024] On the other hand, the sealing material provided by the present invention includes porous alumina particles. The porous alumina particles have a large specific surface area and can adsorb sodium percarbonate. The porous alumina particles are used as reinforcing particles to improve the strength of the sealing material.

[0025] The preparation method provided by the present invention firstly mixes sodium percarbonate and porous alumina evenly so that the sodium percarbonate is loaded and adsorbed on the porous alumina particles, and then polyvinyl alcohol is mixed with modified montmorillonite, and a layer of polyvinyl alcohol film can be coated on the surface of the modified montmorillonite to protect the modified montmorillonite. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0027] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to specific embodiments.

[0028] On the one hand, an embodiment of the present invention provides a CO2-compliant gas extraction drilling sealing material, which includes the following raw materials by weight: 90-100 parts of cement, 3-10 parts of accelerator, 5-15 parts of sodium sulfate, 1-2.5 parts of water reducer, 1-4 parts of methyl cellulose, 1.5-6 parts of sodium percarbonate, 3-5 parts of modified montmorillonite, 1-3 parts of porous alumina particles, and 1-3 parts of polyvinyl alcohol.

[0029] It should be noted that in the present invention, the glauber's salt used is a white powder formed by weathering and losing crystal water, and its main component is sodium sulfate Na2SO4. The cement used is ordinary silicate cement, which can be directly purchased from the market. The accelerator used is Red Star Type 1 accelerator, which can be directly purchased from the market.

[0030] In some embodiments of the present invention, the following raw materials are included by weight: 90 parts of cement, 3 parts of accelerator, 5 parts of sodium sulfate, 1.5 parts of water reducer, 2 parts of methyl cellulose, 3 parts of sodium percarbonate, 3 parts of modified montmorillonite, 2 parts of porous alumina particles, and 3 parts of polyvinyl alcohol.

[0031] In some embodiments of the present invention, the modified montmorillonite is prepared by the following method:

[0032] The montmorillonite and the polyol aqueous solution are mixed evenly, subjected to ultrasonic oscillation for 10-30 minutes, allowed to stand, and the supernatant is removed; subsequently, the cuprous compound is added, mixed evenly, subjected to treatment in a supercritical CO2 atmosphere for 30-60 minutes, and dried.

[0033] Montmorillonite is a layered silicate mineral, consisting of two layers of silicon-oxygen tetrahedrons with one layer of aluminum-oxygen octahedron in between. The unit cell in its crystal structure has a unique one-dimensional layered nanostructure and cation exchange properties. When it is mixed with a polyol aqueous solution, under the action of high-frequency ultrasound, the polyol molecules and water molecules can enter the montmorillonite interlayer, so that the montmorillonite molecules have hydroxyl groups and free water molecules; then it is mixed with cuprous compounds, and under the action of supercritical CO2, the cuprous compounds can combine with the hydroxyl groups to load them on the montmorillonite, while CO2 can combine with free water and adsorb on the montmorillonite. When the sealing material is used, the cuprous compounds on the montmorillonite can react with CO to adsorb CO, and the CO2 combined with water can be converted into carbonate ions, which are further combined with calcium ions in cement to form calcium carbonate, thereby improving the strength of the sealing material after hardening. After sealing, it can be used for a long time without cracks.

[0034] In some embodiments of the present invention, the polyol is ethylene glycol, glycerol or a mixture of the two. The volume fraction of the polyol aqueous solution is 40-60%.

[0035] In some embodiments of the present invention, the cuprous compound is a mixture of one or more of cuprous chloride, cuprous bromide, and cuprous acetate. In the present invention, the aqueous solution of the cuprous compound used, for example, cuprous chloride solution, cuprous bromide solution, etc., has a mass fraction of 10-20%.

[0036] In some embodiments of the present invention, the mass ratio of the montmorillonite to the cuprous compound is 1:(0.1-0.5).

[0037] In some embodiments of the present invention, the particle size of the porous alumina particles is 0.1-0.5 mm.

[0038] In some embodiments of the present invention, the water reducing agent is one of calcium lignin sulfonate and sodium lignin sulfonate.

[0039] On the other hand, an embodiment of the present invention provides a method for preparing a CO2-compliant gas extraction borehole sealing material, comprising the following steps:

[0040] S1, mixing sodium percarbonate and porous alumina uniformly to obtain a first mixture;

[0041] S2, mixing polyvinyl alcohol with water, heating and stirring, then adding the modified montmorillonite, stirring for 1-2 hours, standing for 20-24 hours, drying and grinding to obtain a second mixture; in this step, polyvinyl alcohol is used to form a protective film on the surface of the modified montmorillonite, which can reduce the loss of water in the modified montmorillonite and prevent the modified montmorillonite from reacting with other raw materials such as cement in advance during the storage of the sealing material, thereby extending the shelf life of the sealing material

[0042] S3, uniformly mixing the first mixture, the second mixture and the remaining raw materials.

[0043] In some embodiments of the present invention, in step S2, the mass ratio of the polyvinyl alcohol to water is 1:(1-2).

[0044] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0045] Example 1

[0046] Preparation of modified montmorillonite:

[0047] The montmorillonite was mixed evenly with a 40% ethylene glycol aqueous solution by volume, treated with 20KHz ultrasonic vibration for 20 minutes, left to stand, and the supernatant was removed by filtration; then a 10% cuprous chloride aqueous solution by mass was added, mixed evenly, treated in a supercritical CO2 atmosphere for 50 minutes, dried, and crushed to obtain modified montmorillonite; wherein the temperature of the supercritical CO2 was 50°C; the pressure of the supercritical CO2 atmosphere was 8MPa. The mass ratio of montmorillonite to the solid in the cuprous chloride aqueous solution was 1:0.5.

[0048] Prepare the raw materials according to the following ratio:

[0049] 90 parts of cement, 3 parts of accelerating agent, 5 parts of sodium sulfate, 1.5 parts of water reducing agent (calcium lignin sulfonate), 2 parts of methyl cellulose, 3 parts of sodium percarbonate, 3 parts of modified montmorillonite, 2 parts of porous alumina particles, 3 parts of polyvinyl alcohol. The average particle size of the porous alumina particles is 0.3 mm, and the particle size of a single porous alumina particle is within 0.1-0.5 mm.

[0050] The sealing material of this embodiment is prepared as follows:

[0051] S1, mixing sodium percarbonate and porous alumina uniformly to obtain a first mixture;

[0052] S2, mixing polyvinyl alcohol and water in a ratio of 1:1, heating to 90° C. with stirring, adding the modified montmorillonite, stirring for 1 hour, standing for 24 hours, drying, and grinding to obtain a second mixture;

[0053] S3, uniformly mixing the first mixture, the second mixture and the remaining raw materials.

[0054] Example 2

[0055] Prepare the raw materials according to the following ratio:

[0056] 100 parts of cement, 10 parts of accelerating agent, 15 parts of sodium sulfate, 2.5 parts of water reducing agent (calcium lignin sulfonate), 4 parts of methyl cellulose, 6 parts of sodium percarbonate, 5 parts of modified montmorillonite, 3 parts of porous alumina particles, 3 parts of polyvinyl alcohol. The average particle size of the porous alumina particles is 0.3 mm, and the particle size of a single porous alumina particle is within 0.1-0.5 mm.

[0057] The modified montmorillonite of Example 1 was used and the same method as that of Example 1 was adopted to prepare the sealing material of this example.

[0058] Example 3

[0059] Prepare the raw materials according to the following ratio:

[0060] 95 parts of cement, 8 parts of accelerating agent, 10 parts of sodium sulfate, 2 parts of water reducing agent (calcium lignin sulfonate), 3 parts of methyl cellulose, 3 parts of sodium percarbonate, 4 parts of modified montmorillonite, 2 parts of porous alumina particles, 2 parts of polyvinyl alcohol. The average particle size of the porous alumina particles is 0.3 mm, and the particle size of a single porous alumina particle is within 0.1-0.5 mm.

[0061] The modified montmorillonite of Example 1 was used and the same method as that of Example 1 was adopted to prepare the sealing material of this example.

[0062] Example 4

[0063] Preparation of modified montmorillonite:

[0064] The montmorillonite was mixed evenly with a 40% propylene glycol aqueous solution by volume, treated with 30KHz ultrasonic vibration for 30 minutes, left to stand, and the supernatant was removed by filtration; then a 10% cuprous acetate aqueous solution by mass was added, mixed evenly, treated in a supercritical CO2 atmosphere for 60 minutes, dried, and crushed to obtain modified montmorillonite; wherein the temperature of the supercritical CO2 was 50°C; the pressure of the supercritical CO2 atmosphere was 8MPa. The mass ratio of montmorillonite to the solid in the cuprous acetate aqueous solution was 1:0.3.

[0065] Prepare the raw materials according to the following ratio:

[0066] 90 parts of cement, 3 parts of accelerating agent, 5 parts of sodium sulfate, 1.5 parts of water reducing agent (calcium lignin sulfonate), 2 parts of methyl cellulose, 3 parts of sodium percarbonate, 3 parts of modified montmorillonite, 2 parts of porous alumina particles, 3 parts of polyvinyl alcohol. The average particle size of the porous alumina particles is 0.3 mm, and the particle size of a single porous alumina particle is within 0.1-0.5 mm.

[0067] The sealing material of this embodiment is prepared as follows:

[0068] S1, mixing sodium percarbonate and porous alumina uniformly to obtain a first mixture;

[0069] S2, mixing polyvinyl alcohol and water in a ratio of 1:2, heating to 90° C. with stirring, adding the modified montmorillonite, stirring for 2 hours, standing for 20 hours, drying, and grinding to obtain a second mixture;

[0070] S3, uniformly mixing the first mixture, the second mixture and the remaining raw materials.

[0071] Example 5

[0072] Preparation of modified montmorillonite:

[0073] Montmorillonite, 40% propylene glycol aqueous solution and 60% ethylene glycol aqueous solution were mixed evenly, wherein the volume ratio of propylene glycol aqueous solution to ethylene glycol aqueous solution was 1:1. After 30KHz ultrasonic oscillation treatment for 30 minutes, the mixture was allowed to stand and the supernatant was removed by filtration. Subsequently, 10% cuprous bromide aqueous solution was added and mixed evenly, and the mixture was treated in a supercritical CO2 atmosphere for 60 minutes, dried and crushed to obtain modified montmorillonite. The temperature of the supercritical CO2 was 50°C and the pressure of the supercritical CO2 atmosphere was 8MPa. The mass ratio of montmorillonite to cuprous bromide solid was 1:0.1.

[0074] Prepare the raw materials according to the following ratio:

[0075] 90 parts of cement, 3 parts of accelerating agent, 5 parts of sodium sulfate, 1.5 parts of water reducing agent (calcium lignin sulfonate), 2 parts of methyl cellulose, 3 parts of sodium percarbonate, 3 parts of modified montmorillonite, 2 parts of porous alumina particles, 3 parts of polyvinyl alcohol. The average particle size of the porous alumina particles is 0.3 mm, and the particle size of a single porous alumina particle is within 0.1-0.5 mm.

[0076] The sealing material of this embodiment is prepared as follows:

[0077] S1, mixing sodium percarbonate and porous alumina uniformly to obtain a first mixture;

[0078] S2, mixing polyvinyl alcohol and water in a ratio of 1:2, heating to 90° C. with stirring, adding the modified montmorillonite, stirring for 2 hours, standing for 20 hours, drying, and grinding to obtain a second mixture;

[0079] S3, uniformly mixing the first mixture, the second mixture and the remaining raw materials.

[0080] Example 6

[0081] Preparation of modified montmorillonite:

[0082] Montmorillonite, 40% propylene glycol aqueous solution and 60% ethylene glycol aqueous solution were mixed evenly, wherein the volume ratio of propylene glycol aqueous solution to ethylene glycol aqueous solution was 1:1. After 30KHz ultrasonic oscillation treatment for 30 minutes, the mixture was allowed to stand and the supernatant was removed by filtration. Subsequently, 10% cuprous bromide aqueous solution and 10% cuprous chloride aqueous solution were added in a volume ratio of 1:1, and the mixture was mixed evenly. The mixture was treated in a supercritical CO2 atmosphere for 60 minutes, dried and crushed to obtain modified montmorillonite. The temperature of the supercritical CO2 was 50°C and the pressure of the supercritical CO2 atmosphere was 8MPa. The mass ratio of montmorillonite to cuprous bromide and cuprous chloride solids was 1:0.1.

[0083] Prepare the raw materials according to the following ratio:

[0084] 100 parts of cement, 10 parts of accelerating agent, 15 parts of sodium sulfate, 2.5 parts of water reducing agent (sodium lignin sulfonate), 4 parts of methyl cellulose, 6 parts of sodium percarbonate, 5 parts of modified montmorillonite, 3 parts of porous alumina particles, 3 parts of polyvinyl alcohol. The average particle size of the porous alumina particles is 0.1 mm, and the particle size of a single porous alumina particle is within 0.1-0.2 mm.

[0085] The sealing material of this embodiment is prepared as follows:

[0086] S1, mixing sodium percarbonate and porous alumina uniformly to obtain a first mixture;

[0087] S2, mixing polyvinyl alcohol and water in a ratio of 1:2, heating to 90° C. with stirring, adding the modified montmorillonite, stirring for 2 hours, standing for 20 hours, drying, and grinding to obtain a second mixture;

[0088] S3, uniformly mixing the first mixture, the second mixture and the remaining raw materials.

[0089] Example 7

[0090] This example uses the modified montmorillonite prepared in Example 1 and the raw material ratio and preparation method of Example 2 to prepare the sealing material.

[0091] Example 8

[0092] This example uses the modified montmorillonite prepared in Example 2, and the raw material ratio and preparation method of Example 1 to prepare the sealing material.

[0093] Example 9

[0094] This example uses the modified montmorillonite prepared in Example 1 and the raw material ratio and preparation method of Example 3 to prepare the sealing material.

[0095] Comparative Example 1

[0096] The difference from Example 1 is that in this example, the raw materials do not contain modified montmorillonite and polyvinyl alcohol, and the remaining raw materials and preparation method are the same as those in Example 1.

[0097] Comparative Example 2

[0098] The difference from Example 1 is that, in this example, the raw materials do not contain porous alumina particles, and the remaining raw materials and preparation method are the same as those in Example 1.

[0099] Comparative Example 3

[0100] The difference from Example 1 is that in this example, the raw materials do not contain modified montmorillonite, polyvinyl alcohol and porous alumina particles, and the remaining raw materials and preparation method are the same as those in Example 1.

[0101] Experimental example

[0102] The sealing materials of Examples 1-6 and Comparative Examples 1-3 were used as test objects, and the following tests were performed respectively:

[0103] 1. Take 50g of sealing material respectively, place it in a container with the same bottom area, add 100g of water, stir evenly, let it stand, and after it is completely hardened, calculate the initial setting time, final setting time, volume before adding water V1 (bottom area of ​​container × height of sealing material in container), volume after expansion and hardening V2, and calculate The results are shown in Table 1.

[0104] 2. Take out the hardened sealing material and test its compressive strength. The results are shown in Table 1.

[0105] 3. After the hardened sealing material was placed at room temperature for 6 months, it was tested for cracks inside. The results are shown in Table 1.

[0106] Table 1 Sealing material properties of Examples 1-5 and Comparative Examples 1-3

[0107]

[0108]

[0109] It can be concluded from Table 1 that the sealing materials prepared by Examples 1-5 have high expansion rate and good compressive strength. After long-term use in laboratory simulation, no cracks are generated. In Comparative Example 1, it does not contain modified montmorillonite, and the expansion rate of the sealing material does not change much, but its compressive strength decreases because modified montmorillonite can be used as a reinforcing material to improve the compressive strength after hardening. In Comparative Example 2, it does not contain porous alumina particles, and the compressive strength and expansion rate both decrease. On the one hand, porous alumina can be used as reinforcing particles to improve the compressive strength. On the other hand, the porous structure can load sodium percarbonate to avoid concentrated release of sodium percarbonate and reduce the expansion rate. The porous structure in Examples 1-5 can control the decomposition rate of sodium percarbonate and the time when it starts to decompose, so that sodium percarbonate is gradually decomposed, continuously produces oxygen, and then increases the expansion rate.

[0110] In summary, the sealing material provided in the embodiment of the present invention can quickly and effectively penetrate into the cracks of the coal body around the borehole, merge with the coal body, and undergo an expansion reaction, so that the sealing material and the coal body fit together to achieve the best sealing effect. It effectively solves the problem of low concentration and fast attenuation of the extraction borehole due to poor sealing effect. It has the advantages of strong fluidity, large expansion rate and uniform distribution, high compressive strength and good density.

[0111] The embodiments described above are part of the embodiments of the present invention, rather than all of the embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A CO-compliant gas extraction drilling sealing material, characterized in that: The raw materials include the following by weight: 90-100 parts of cement, 3-10 parts of accelerating agent, 5-15 parts of sodium sulfate, 1-2.5 parts of water reducing agent, 1-4 parts of methyl cellulose, 1.5-6 parts of sodium percarbonate, 3-5 parts of modified montmorillonite, 1-3 parts of porous alumina particles and 1-3 parts of polyvinyl alcohol.

2. The CO2-compliant gas extraction drilling sealing material according to claim 1 is characterized in that: The following raw materials are included by weight: 90 parts of cement, 3 parts of accelerating agent, 5 parts of sodium sulfate, 1.5 parts of water reducing agent, 2 parts of methyl cellulose, 3 parts of sodium percarbonate, 3 parts of modified montmorillonite, 2 parts of porous alumina particles, and 3 parts of polyvinyl alcohol.

3. The CO2-compliant gas extraction drilling sealing material according to claim 1, characterized in that: The modified montmorillonite is prepared by the following method: The montmorillonite and the polyol aqueous solution are mixed evenly, subjected to ultrasonic oscillation for 10-30 minutes, allowed to stand, and the supernatant is removed; subsequently, the cuprous compound is added, mixed evenly, subjected to treatment in a supercritical CO2 atmosphere for 30-60 minutes, and dried.

4. The CO2-compliant gas extraction drilling sealing material according to claim 3 is characterized in that: The polyol is ethylene glycol, glycerol or a mixture of the two.

5. The CO2-compliant gas extraction drilling sealing material according to claim 3, characterized in that: The cuprous compound is a mixture of one or more of cuprous chloride, cuprous bromide and cuprous acetate.

6. The CO2-compliant gas extraction drilling sealing material according to claim 3, characterized in that: The mass ratio of the montmorillonite to the cuprous compound is 1:(0.1-0.5).

7. The CO2-compliant gas extraction drilling sealing material according to claim 1, characterized in that: The particle size of the porous alumina particles is 0.1-0.5 mm.

8. The CO2-compliant gas extraction drilling sealing material according to claim 1, characterized in that: The water reducing agent is one of calcium lignin sulfonate and sodium lignin sulfonate.

9. A method for preparing a CO2-compliant gas extraction drilling sealing material according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1, mixing sodium percarbonate and porous alumina uniformly to obtain a first mixture; S2, mixing polyvinyl alcohol and water, heating and stirring, then adding the modified montmorillonite, stirring for 1-2 hours, standing for 20-24 hours, drying and grinding to obtain a second mixture; S3, uniformly mixing the first mixture, the second mixture and the remaining raw materials.

10. The method for preparing the CO2-compliant gas extraction drilling sealing material according to claim 8, characterized in that: In step S2, the mass ratio of the polyvinyl alcohol to water is 1:(1-2).

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