Gas well water shut-off composition, gas well gel water shut-off agent

Abstract

This invention relates to a gas well water shut-off composition and a gas well gel water shut-off agent, belonging to the field of oilfield chemical technology. When the gas well water shut-off composition of this invention is applied to gas wells for water shut-off, it preferentially enters high-permeability layers and fractures due to formation property selection. During the curing process, the foaming agent and surfactant generate a large number of bubbles. These bubbles communicate with the micropores of some hypercrosslinked polymers. Under the dual effect of the hydrophobic microporous structure of the hypercrosslinked polymer and the bubbles generated by foaming, the water phase permeability can be reduced, with minimal impact on the gas phase permeability. Simultaneously, the large pores formed by foaming reduce gas flow resistance, ensuring rapid gas passage and achieving the effect of water shut-off and gas flow. Furthermore, the gas well water shut-off composition of this invention exhibits good heat resistance and H2S corrosion resistance after curing, making it suitable for high-sulfur gas wells.

Description

Technical Field

[0001] This invention relates to gas well water shut-off compositions and gas well gel water shut-off agents, belonging to the field of oilfield chemical technology. Background Technology

[0002] After a gas well produces water, its production capacity decreases, and the pressure in the producing formation also drops, leading to premature well shutdown. Water shut-off is one of the common measures for restarting gas well production. Water shut-off technology can be divided into mechanical water shut-off technology and chemical water shut-off technology. For horizontal wells, wells with deformed casings, wells with gas and water in the same layer, and wells with a small reservoir thickness above the water intrusion surface, the commonly used mechanical water shut-off technology cannot meet the requirements, and chemical water shut-off technology needs to be implemented. Chemical water shut-off technology can be divided into physical accumulation type and chemical reaction type according to the mechanism of action of the plugging agent used. The commonly used plugging agents for physical accumulation type are inorganic particles such as calcium carbonate and mica, and organic particles such as water-swellable bodies and rubber particles. Because the reverse pressure resistance of the particle blockage is weak after accumulation, it is easy to disperse and is often used as a temporary plugging agent. The commonly used plugging agents for chemical reaction type are inorganic plugging agents such as cement and quicklime, and organic plugging agents such as gels and resins. After the plugging agent solidifies in the formation, it forms a whole with the formation, with high sealing strength, which is the development direction of chemical water shut-off technology for natural gas wells. Commonly used chemical plugging agents are polyacrylamide gel plugging agents and polyvinyl alcohol gel plugging agents. Polyacrylamide gel plugging agents are not resistant to medium and high temperatures (≤93℃) and are easily degraded after mechanical shearing. Currently, the formation temperature of most gas reservoirs in China is above 90℃, reaching up to 180℃, which limits their field application. Polyvinyl alcohol has good water solubility, temperature resistance, and shear resistance, making it an ideal alternative to polyacrylamide gel plugging agents.

[0003] Currently, there is also relevant research on polyvinyl alcohol (PVA) plugging agents in China. For example, Chinese special document CN108893101A discloses a method for preparing a plugging agent. The method involves mixing a modified PVA mixture with borax at a mass ratio of 100:1 to 100:2, adding a mixing treatment agent at 0.05 to 0.06 times the mass of the modified PVA mixture, and a plasticizer at 0.01 to 0.03 times the mass of the modified PVA mixture. After stirring and mixing, a plugging agent blank is obtained. The plugging agent blank is dried to constant weight and pulverized to obtain a pretreated plugging agent blank. The pretreated plugging agent blank is mixed with water-absorbing resin at a mass ratio of 30:1 to 40:1, and an additive at 0.3 to 0.5 times the mass of the pretreated plugging agent blank is added. After stirring and mixing, the plugging agent is obtained. The leak-stopping agent prepared by the Chinese special train document has excellent leak-stopping effect and compressive strength. The main technical drawback is that it does not have gas and water selectivity. It can block both water and gas, and is not suitable for water plugging in reservoirs where the water layer is not clear or where gas and water are in the same layer. Summary of the Invention

[0004] The purpose of this invention is to provide a gas well water shut-off composition that can solve the problem that current gas well water shut-off agents can both shut off water and gas, and are not suitable for water shut-off in reservoirs where the water-producing layer is unclear or where gas and water are in the same layer.

[0005] Another object of the present invention is to provide a gas well gel plugging agent.

[0006] To achieve the above objectives, the technical solution adopted by the gas well water shut-off composition of the present invention is as follows:

[0007] A gas well water shut-off composition comprises the following components in parts by weight: 100-108 parts water, 5-10 parts polyvinyl alcohol, 0.7-5 parts polyvinyl alcohol crosslinking agent, 1-10 parts foaming agent, 2-5 parts surfactant, and 5-10 parts hypercrosslinked polymer; the pores of the hypercrosslinked polymer are hydrophobic; the pore size of the hypercrosslinked polymer is 3-30 nm.

[0008] The gas well water shut-off composition of the present invention, when applied to gas well water shut-off, preferentially enters water channeling channels such as high-permeability layers and fractures due to formation physical properties selection. During the curing process, the foaming agent and surfactant generate a large number of bubbles, which communicate with the micropores of some hypercrosslinked polymers (e.g., Figure 1 As shown, 1 is a hypercrosslinked polymer, 2 is a bubble, and 3 is a polyvinyl alcohol gel. Under the dual effects of the hydrophobic microporous structure of the hypercrosslinked polymer (the capillary force formed by the hydrophobic micropores acts as a resistance to water molecules, reducing the flow capacity of the aqueous phase while having minimal impact on gas molecules) and the bubbles generated by foaming, a connected hierarchical porous structure can be constructed in situ within the polyvinyl alcohol gel. This reduces the permeability of the aqueous phase and minimizes its impact on the permeability of the gas phase. Simultaneously, the large pores formed by foaming reduce airflow resistance, ensuring rapid gas passage and achieving a water-blocking and gas-permeable effect. Furthermore, the gas well water-blocking composition of this invention exhibits excellent heat resistance and H2S corrosion resistance after curing, making it suitable for high-sulfur gas wells.

[0009] It is understandable that hypercrosslinked polymers (HCPs) are a class of permanent microporous polymers formed by highly crosslinking rigid aromatic monomers through chemical reactions such as Friedel-Crafts reaction or Scholl oxidative coupling. (The polymer network has high rigidity and poor mobility, and the gaps between the molecular chains can form a stable microporous structure. Its high crosslinking and stable covalent bond connection enable its microporous structure to exist stably.) They have advantages such as light weight, controllable pore structure, large specific surface area, and good thermal and chemical stability.

[0010] Preferably, the particle size of the hypercrosslinked polymer is 0.5–100 μm. If the amount of hypercrosslinked polymer added to the gas well plugging composition is too small, the air permeability of the cured product will decrease; if the amount added is too large, the viscosity of the gas well plugging composition will be too high, which is not conducive to construction.

[0011] In this invention, the hypercrosslinked polymer can be purchased directly or prepared in-house. For example, commercially available styrene-based hypercrosslinked polymers can be used, or benzene, substituted benzene, or polycyclic aromatic hydrocarbons can be used as monomers, 1,4-dimethoxybenzene, dimethyl formaldehyde, or trimethyl orthoformate as crosslinking agents, and ferric chloride as a catalyst to prepare the hypercrosslinked polymer through polymerization. Preferably, the hypercrosslinked polymer is prepared by a method comprising the following steps: heating a mixture mainly composed of monomers, polymerization crosslinking agents, solvents, and Lewis acid catalysts to 45°C and reacting for 4 hours, then heating to 80°C and reacting for 19 hours, and then purifying the reaction product to obtain the polymer; the monomers are selected from one or any combination of benzene, toluene, chlorotoluene, and phenol; the polymerization crosslinking agents are selected from one or any combination of 1,4-dimethoxybenzene, dimethyl formaldehyde, and trimethyl orthoformate; the molar ratio of monomers, catalysts, and polymerization crosslinking agents is 1:3:3. Preferably, the solvent is 1,2-dichloroethane. Preferably, the volume of solvent used is 30 mL per 10 g of monomer. Preferably, the purification method includes the following steps: soaking the reaction product in a methanol solution of hydrochloric acid for 6 h, then performing solid-liquid separation, washing the solid obtained from the solid-liquid separation, extracting the washed solid using a Soxhlet extractor, and finally drying the extracted product to obtain the hypercrosslinked polymer.

[0012] Preferably, the gas well water plugging composition comprises the following components in parts by weight: 102.7 to 105.3 parts water, 6 to 8 parts polyvinyl alcohol, 1.3 to 2.7 parts polyvinyl alcohol crosslinking agent, 3 to 10 parts foaming agent, 3 to 5 parts surfactant, and 4 to 10 parts hypercrosslinked polymer.

[0013] Preferably, the degree of polymerization of the polyvinyl alcohol is 1700-2800. Preferably, the degree of alcoholysis of the polyvinyl alcohol is not less than 55%. For example, the polyvinyl alcohol is selected from one or any combination of polyvinyl alcohol 1755, polyvinyl alcohol 1788, polyvinyl alcohol 1792, polyvinyl alcohol 1799, polyvinyl alcohol 2099, polyvinyl alcohol 2499, polyvinyl alcohol 2699, and polyvinyl alcohol 2888.

[0014] Preferably, the polyvinyl alcohol crosslinking agent is an aldehyde crosslinking agent or is composed of an aldehyde crosslinking agent and a phenolic crosslinking agent. Preferably, the aldehyde crosslinking agent is selected from one or any combination of formaldehyde, paraformaldehyde, paraformaldehyde, hexamethylenetetramine, glyoxal, and glutaraldehyde. Preferably, the phenolic crosslinking agent is selected from one or any combination of phenol, catechol, resorcinol, and hydroquinone.

[0015] Urotropin, also known as hexamethylenetetramine, has the chemical formula C6H. 12 N4 can decompose to produce formaldehyde under high temperature (>100℃) conditions.

[0016] Preferably, the polyvinyl alcohol crosslinking agent is composed of an aldehyde crosslinking agent and a phenolic crosslinking agent, and the mass ratio of the aldehyde crosslinking agent to the phenolic crosslinking agent is (1-2):1.

[0017] Preferably, the foaming agent is selected from one or any combination of carbonates, bicarbonates, azo compounds, and sulfonyl hydrazides. Preferably, the bicarbonate is sodium bicarbonate. Preferably, the azo compound is azodicarbonamide. Preferably, the sulfonyl hydrazide is 4,4-oxobisbenzenesulfonyl hydrazide.

[0018] Preferably, the surfactant is a nonionic surfactant. Preferably, the nonionic surfactant is a Tween surfactant. Preferably, the Tween surfactant is Tween 80.

[0019] The technical solution adopted by the gas well gel plugging agent of the present invention is as follows:

[0020] A gas well gel plugging agent includes a hydrogel matrix and a hypercrosslinked polymer dispersed in the hydrogel matrix; the gas well gel plugging agent has a porous structure; the hydrogel matrix is ​​formed from polyvinyl alcohol through a crosslinking reaction.

[0021] The gas well gel plugging agent of this invention can reduce the permeability of the aqueous phase and have a minimal impact on the permeability of the gas phase. Simultaneously, the large pores formed by foaming reduce gas flow resistance, ensuring rapid gas passage and achieving a water-blocking and gas-permeable effect. Furthermore, the gas well gel plugging agent of this invention exhibits excellent heat resistance and H2S corrosion resistance, making it suitable for high-sulfur gas wells.

[0022] Preferably, the gas well gel plugging agent is formed by the above-mentioned gas well plugging composition through a curing reaction.

[0023] Preferably, the curing reaction temperature is 100–200°C. Preferably, the curing reaction time is 24–48 hours. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the gas well water plugging composition of the present invention after curing or the gas well gel water plugging agent of the present invention; wherein, the reference numerals are as follows: 1-hypercrosslinked polymer; 2-bubble; 3-polyvinyl alcohol gel. Detailed Implementation

[0025] The technical solution of the present invention will be further described below with reference to specific embodiments. It should be noted that the purpose of this embodiment is to further illustrate the present invention and is not intended to limit the scope of protection of the present invention.

[0026] The hypercrosslinked polymers used in Examples 1-3 of this invention were prepared by a method comprising the following steps: 10 g of monomer was added to a 150 mL single-necked flask, followed by 30 mL of solvent (1,2-dichloroethane), and stirred until homogeneous. Then, a crosslinking agent and a Lewis acid catalyst were added, and the mixture was stirred at room temperature for 30 min. The mixture in the single-necked flask was then heated to 45 °C and reacted for 4 h. The temperature was then raised to 80 °C and reacted for 19 h. After the reaction was completed, the solid in the single-necked flask was poured into a beaker and soaked in a methanol solution of hydrochloric acid for 6 h. The solid was then repeatedly filtered and washed with anhydrous methanol until the filtrate changed from yellow-green to colorless. The filtered and washed solid was then extracted using a Soxhlet extractor for 72 h. The solvents used for extraction were tetrahydrofuran and methanol, respectively. Finally, the extracted product was dried in a vacuum oven at 60 °C for 12 h to obtain the hypercrosslinked polymer. The monomer was benzene, the crosslinking agent was dimethylformaldehyde, and the Lewis acid catalyst was FeCl3. The molar ratio of monomer, Lewis acid catalyst, and crosslinking agent was 1:3:3. The pore size distribution range of the prepared hypercrosslinked polymer is 3–30 nm, and the particle size distribution range is 0.5–100 μm.

[0027] I. Specific embodiments of the gas well water-plugging composition of the present invention are as follows:

[0028] Example 1

[0029] The gas well water shut-off composition of this embodiment includes the following components in parts by weight: 102.7 parts water, 6 parts polyvinyl alcohol (PVA) 1799, 1.3 parts PVA crosslinking agent, 3 parts sodium bicarbonate foaming agent, 3 parts Tween 80 surfactant, and 4 parts hypercrosslinked polymer; the PVA crosslinking agent is composed of phenol and formaldehyde in a mass ratio of 1:1.

[0030] The gas well plugging composition of this embodiment is prepared by a method including the following steps:

[0031] (1) Take an appropriate amount of deionized water, add 1 part by mass of phenol and an appropriate amount of formaldehyde aqueous solution with a mass fraction of 37% in sequence, stir at room temperature until dissolved to obtain a crosslinking agent solution; the mass ratio of formaldehyde to phenol in the formaldehyde aqueous solution is 1:1, and the mass ratio of water to phenol in the crosslinking agent solution is 4:1.

[0032] (2) Take 100 parts by mass of deionized water, heat it to 90°C, then add 6 parts by mass of polyvinyl alcohol 1799, stir until completely dissolved, cool to 20°C, then add 3 parts by mass of surfactant Tween 80, 3 parts by mass of foaming agent sodium bicarbonate, 4 parts by mass of hypercrosslinked polymer, and 4 parts by mass of crosslinking agent solution in sequence, stir evenly, and the product is obtained.

[0033] Example 2

[0034] The gas well water shut-off composition of this embodiment includes the following components in parts by weight: 104 parts water, 28,888 parts polyvinyl alcohol, 2 parts polyvinyl alcohol crosslinking agent, 6 parts foaming agent 4,4-oxobisbenzenesulfonyl hydrazine, 4 parts surfactant Tween 80, and 7 parts hypercrosslinked polymer; the polyvinyl alcohol crosslinking agent is composed of resorcinol and hexamethylenetetramine in a mass ratio of 1:1.5.

[0035] The gas well plugging composition of this embodiment is prepared by a method including the following steps:

[0036] (1) Take 5 parts by mass of deionized water, add 1 part by mass of resorcinol and 1.5 parts by mass of hexamethylenetetramine in sequence, stir at room temperature until dissolved to obtain a crosslinking agent solution;

[0037] (2) Take 100 parts by weight of deionized water, heat it to 80°C, then add 8 parts by weight of polyvinyl alcohol 2888, stir until completely dissolved, cool to 20°C, then add 4 parts by weight of surfactant Tween 80, 6 parts by weight of foaming agent 4,4-oxobisbenzenesulfonyl hydrazine, 7 parts by weight of hypercrosslinked polymer, and 6 parts by weight of crosslinking agent solution in sequence, stir evenly, and the product is obtained.

[0038] Example 3

[0039] The gas well water shut-off composition of this embodiment includes the following components in parts by weight: 105.3 parts water, 8 parts polyvinyl alcohol (PVA) 1755, 2.7 parts PVA crosslinking agent, 10 parts foaming agent azodicarbonamide, 5 parts surfactant Tween 80, and 10 parts hypercrosslinked polymer; the PVA crosslinking agent is composed of phenol and glutaraldehyde in a mass ratio of 1:2.

[0040] The gas well plugging composition of this embodiment is prepared by a method including the following steps:

[0041] (1) Take 6 parts by mass of deionized water, add 1 part by mass of phenol and 2 parts by mass of glutaraldehyde in sequence, stir at room temperature until dissolved to obtain a crosslinking agent solution;

[0042] (2) Take 100 parts by weight of deionized water, heat it to 70°C, then add 8 parts by weight of polyvinyl alcohol 1755, stir until completely dissolved, cool to 20°C, then add 5 parts by weight of surfactant Tween 80, 10 parts by weight of foaming agent azodicarbonamide, 10 parts by weight of hypercrosslinked polymer, and 8 parts by weight of crosslinking agent solution in sequence, stir evenly, and the product is obtained.

[0043] Comparative Example 1

[0044] The only difference between the gas well plugging composition of this comparative example and the gas well plugging composition of Example 1 is that the mass fraction of the hypercrosslinked polymer used in the gas well plugging composition of this comparative example is 0.

[0045] II. Specific embodiments of the gas well gel water-blocking agent of the present invention are as follows:

[0046] Example 4

[0047] The gas well gel plugging agent of this embodiment includes a hydrogel matrix and a hypercrosslinked polymer dispersed in the hydrogel matrix; the gas well gel plugging agent has a porous structure; the hydrogel matrix is ​​prepared from polyvinyl alcohol through a crosslinking reaction. The gas well gel plugging agent of this comparative example is prepared by curing the gas well plugging composition of Example 1 at 100°C for 48 hours.

[0048] Example 5

[0049] The gas well gel plugging agent of this embodiment includes a hydrogel matrix and a hypercrosslinked polymer dispersed in the hydrogel matrix; the gas well gel plugging agent has a porous structure; the hydrogel matrix is ​​prepared from polyvinyl alcohol through a crosslinking reaction. The gas well gel plugging agent of this comparative example is prepared by curing the gas well plugging composition of Example 2 at 150°C for 36 hours.

[0050] Example 6

[0051] The gas well gel plugging agent of this embodiment includes a hydrogel matrix and a hypercrosslinked polymer dispersed in the hydrogel matrix; the gas well gel plugging agent has a porous structure; the hydrogel matrix is ​​prepared from polyvinyl alcohol through a crosslinking reaction. The gas well gel plugging agent of this comparative example is prepared by curing the gas well plugging composition of Example 3 at 200°C for 24 hours.

[0052] Comparative Example 2

[0053] The gas well gel plugging agent of this comparative example was prepared by curing the gas well plugging composition of Comparative Example 1 at 100°C for 48 hours.

[0054] Experimental Example 1

[0055] (1) Test the pore volume of the sand-filled pipe and the foundation parameters

[0056] Clean and dry the sand-filled tube, fill it with quartz sand of 20-80 mesh size, compact the quartz sand, evacuate the sand-filled tube, and weigh it. Record the mass as mg. Pass distilled water into the sand-filled tube until saturated, weigh it, and record the mass as Mg. Use vernier calipers to measure the inner diameter of the sand-filled tube and record it as D mm; measure the length of the sand-filled tube and record it as L mm.

[0057] (2) Determine the gas and water phase permeability of the sand-filled pipe.

[0058] Distilled water was injected into the sand-filled tube at a rate of 2 mL / min using a horizontal flow pump. Once the inlet and outlet flow rates of the sand-filled tube stabilized and were equal, the pressure at the inlet end of the sand-filled tube was recorded. Nitrogen gas was then introduced into the sand-filled tube at a pressure of 0.1 MPa until the flow velocity at the outlet end of the sand-filled tube stabilized, and the flow velocity at the outlet end of the sand-filled tube was measured. The water permeability (before sealing) and the effective gas permeability (before sealing) of the sand-filled tube were calculated using Darcy's law.

[0059] (3) Using a displacement pump, the water-blocking compositions of Examples 1-3 and the comparative example with a pore volume of 1PV were driven into the sand-filled pipe at a certain discharge rate. The inlet and outlet of the sand-filled pipe were sealed, and the sand-filled pipe was placed at the curing temperature of the water-blocking composition for curing. The curing time was 48h. The curing temperatures of the water-blocking compositions of Examples 1-3 and the comparative example were 100℃, 150℃, 200℃ and 100℃, respectively.

[0060] (4) Inject distilled water into the sand-filled tube at a rate of 2 mL / min using a horizontal flow pump. Once the inlet and outlet flow rates of the sand-filled tube are stable and the inlet and outlet flow rates are the same, record the pressure at the inlet end of the sand-filled tube. Use a nitrogen cylinder to purge the sand-filled tube at a pressure of 0.1 MPa until the flow velocity at the outlet end of the sand-filled tube stabilizes, then measure the flow velocity at the outlet end of the sand-filled tube. Calculate the water permeability (after sealing) and the effective gas permeability (after sealing) of the sand-filled tube according to Darcy's law.

[0061] The water-blocking and air-permeability properties of the gas well plugging compositions of Examples 1-3 and Comparative Example 1 are shown in Table 1.

[0062] Table 1 shows the water-blocking and gas-permeability performance of the gas well plugging and sand-filling pipes tested in Examples 1-3 and Comparative Example 1.

[0063]

[0064] Note: Blocking rate = (permeability before blocking - permeability after blocking) / permeability before blocking × 100%.

[0065] Experimental Example 2

[0066] Compression tests were conducted on the gas well gel plugging agents of Examples 4-6 and Comparative Example 2 according to the methods specified in the national standard GB / T1041-2008 "Determination of Compression Properties of Plastics". The practical application performance of the gas well gel plugging agent was evaluated by simulating the underground working conditions of a high-sulfur gas well in a high-temperature, high-pressure reactor, and by testing the changes in compressive strength of the gas well gel plugging agent under high temperature, H2S, and formation water conditions. The H2S corrosion test method was as follows: The gas well gel plugging agent was placed in a high-temperature, high-pressure reactor containing simulated water (mineralization of 67800 mg / L), then heated to 150℃, and 2.5 MPa of H2S and 1.6 MPa of CO2 were introduced. The pressure was then increased to 16 MPa with N2. After certain test times (7 days, 30 days, and 60 days), the gas well gel plugging agent was removed, and the compressive strength before and after H2S corrosion was tested. The experimental results are shown in Table 2.

[0067] Table 2 shows the compressive strength of the gas well gel plugging agents in Examples 4-6 and Comparative Example 2 before and after H2S corrosion.

[0068]

[0069] The results show that the gas well gel plugging agents of Examples 4-6 exhibit small changes in compressive strength over time under high temperature, H2S, and simulated water conditions, and demonstrate good temperature and H2S resistance.

Claims

1. A gas well water shutoff composition characterized by, The composition comprises the following components in mass fraction: water 100-108 parts, polyvinyl alcohol 5-10 parts, polyvinyl alcohol crosslinking agent 0.7-5 parts, foaming agent 1-10 parts, surfactant 2-5 parts and super-crosslinked polymer 5-10 parts; the pores of the super-crosslinked polymer are hydrophobic; the pore size of the super-crosslinked polymer is 3-30 nm; the foaming agent is selected from one or any combination of carbonates, bicarbonates, azo compounds and sulfonhydrazide compounds; the surfactant is a Tween surfactant; and the super-crosslinked polymer is prepared by using benzene as a monomer, 1,4-dimethoxybenzene, dimethyl glycol formaldehyde or trimethyl orthoformate as a crosslinking agent, and ferric chloride as a catalyst through a polymerization reaction.

2. The gas well water shutoff composition of claim 1, wherein, The particle size of the super-crosslinked polymer is 0.5-100 μm.

3. The gas well water shutoff composition of claim 1, wherein, The polyvinyl alcohol has a degree of polymerization of 1700-2800 and an alcoholysis degree of not less than 55%.

4. The gas well water shutoff composition of claim 1, wherein, The polyvinyl alcohol crosslinking agent is an aldehyde crosslinking agent or is composed of an aldehyde crosslinking agent and a phenolic crosslinking agent; the aldehyde crosslinking agent is selected from one or any combination of formaldehyde, trioxane, paraformaldehyde, urotropine, glyoxal and glutaraldehyde; and the phenolic crosslinking agent is selected from one or any combination of phenol, catechol, resorcinol and hydroquinone.

5. The gas well water shutoff composition of claim 4, wherein, The polyvinyl alcohol crosslinking agent is composed of an aldehyde crosslinking agent and a phenolic crosslinking agent, and the mass ratio of the aldehyde crosslinking agent to the phenolic crosslinking agent is (1-2):

1.

6. The gas well water shutoff composition of claim 1, wherein, The foaming agent is one of sodium bicarbonate, azodicarbonamide and 4,4-oxobisbenzenesulfonylhydrazide.

7. The gas well water shutoff composition of claim 1, wherein, The Tween surfactant is Tween 80.

8. The gas well water shutoff composition of any one of claims 1-7, wherein, The gas well water plugging composition comprises the following components in mass fraction: water 102.7-105.3 parts, polyvinyl alcohol 6-8 parts, polyvinyl alcohol crosslinking agent 1.3-2.7 parts, foaming agent 3-10 parts, surfactant 3-5 parts and super-crosslinked polymer 4-10 parts; and the surfactant is Tween 80. The super-crosslinked polymer is prepared by a method comprising the following steps: heating a mixture mainly composed of a monomer, a polymerization crosslinking agent, a solvent and a Lewis acid catalyst to 45℃, reacting for 4 h, then heating to 80℃ and reacting for 19 h, and then purifying the reaction product to obtain the super-crosslinked polymer; and the molar ratio of the monomer, the catalyst and the polymerization crosslinking agent is 1:3:

3.

9. A gas well gel water shutoff agent characterized by, The gas well gel water plugging agent is formed by a curing reaction of the gas well water plugging composition according to any one of claims 1-8; and the gas well gel water plugging agent has a porous structure.

10. The gas well gel water shutoff agent of claim 9, wherein, The temperature of the curing reaction is 100-200℃.

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