Water shutoff agent and preparation method thereof

Abstract

The application provides a water plugging agent and a preparation method thereof. The preparation method of the water plugging agent comprises the following steps: 1) uniformly mixing water, a first chelating agent, a polymerization monomer, a primary crosslinking agent, an initiator and an accelerator to obtain liquid A; 2) uniformly mixing water, a second chelating agent, a crosslinked polymer, a secondary crosslinking agent and a stabilizer to obtain liquid B; and 3) uniformly mixing liquid A and liquid B to obtain the water plugging agent.

Description

Technical Field

[0001] This invention relates to the field of profile control and water shut-off in oilfields, and particularly to a water shut-off agent and its preparation method. Background Technology

[0002] Fractured-vuggy carbonate reservoirs in the Northwest Oilfield are characterized by high temperature, high pressure, and high salinity. Furthermore, their geological sedimentary structures, reservoir spatial distribution, and internal scale variations differ from conventional single-porosity sandstone reservoirs. Water shut-off in oil wells differs from water well profile control in terms of pressure gradient distribution, oil-water selectivity, and targeted placement of plugging agents. For fractured-vuggy carbonate reservoirs with large fractures and cavernous reservoirs, water shut-off has been widely studied as a relatively effective method for reducing water content and increasing oil production. This type of reservoir has the following geological characteristics: large burial depth (5000-8000m), high temperature (120-150℃), high salinity (200,000-220,000 mg / L), and high pressure (50-70 MPa); complex and variable scale of cavern-fracture combinations and diverse connectivity; strong water energy; prominent contradictions in the horizontal profile; and significant differences in oil-water distribution.

[0003] Faced with high-temperature deep wells and the formation water quality of fractured carbonate reservoirs in Northwest Oilfield being calcium chloride water type, the traditional gel plugging system has the following technical defects: (1) When polymer molecular chains are exposed to a high content of metal ions, the side groups such as amide groups and carboxyl groups are easily attacked by divalent calcium and magnesium ions and hydrolyzed and precipitated, which easily leads to the "pancake" phenomenon, making it difficult to form a high-strength and tough plugging structure in the three-dimensional fractured cavity position, making it difficult to form effective retention, and the long-term stability is reduced; (2) High temperature accelerates the polymerization reaction rate of acrylic monomers, which are easy to burst into gel during the pumping process, abnormal gelation and blockage of the wellbore; (3) The traditional gel system is affected by high temperature, resulting in low viscosity before gelation, and the leading edge position is not resistant to water scouring, with poor resistance to scouring and thinning, which leads to delayed gelation time and reduced plugging strength, which is not conducive to forming a high retention and strong stability baffle gel system; (4) The high mineralization geological characteristics of fractured carbonate reservoirs in Northwest Oilfield inhibit the dispersion performance of clay metal cations in water solvent. As the concentration of electrolytes in the aqueous solution increases, the hydration of metal ions competes with the hydration of clay for water molecules, reducing the clay's ability to directly adsorb water molecules. Secondly, the number of cations increases, compressing the diffusion layer and causing the clay's hydration film to thin and its hydration capacity to weaken. Therefore, under the special high-salinity geological conditions of the Northwest Oil Reservoir, the method of using clay minerals to increase the viscosity of the liquid phase of the water body to achieve anti-thinning is not feasible. Summary of the Invention

[0004] One aspect of the present invention provides a method for preparing a water-blocking agent, which includes the following steps:

[0005] 1) Mix water, the first chelating agent, the polymerizing monomer, the primary crosslinking agent, the initiator, and the accelerator evenly to obtain solution A;

[0006] 2) Mix water, the second chelating agent, the crosslinking polymer, the secondary crosslinking agent, and the stabilizer evenly to obtain solution B;

[0007] 3) Mix liquid A and liquid B evenly to obtain the water-blocking agent.

[0008] In one specific embodiment, the first chelating agent and the second chelating agent are independently sodium carbonate.

[0009] In one specific embodiment, the polymerizing monomer is an amide monomer, a sulfonate monomer, or a hydrophobic associating monomer.

[0010] In one specific embodiment, the amide monomer is acrylamide and / or N,N-dimethylacrylamide.

[0011] In one specific embodiment, the sulfonate monomer is at least one of sodium 3-allyloxy-2-hydroxy-1-propanesulfonate, sodium styrenesulfonate, and sodium allylsulfonate.

[0012] In one specific embodiment, the hydrophobic associating monomer is at least one of octadecyltrimethylammonium chloride and / or hexadecyltrimethylammonium bromide.

[0013] In one specific embodiment, the acrylamide monomer content is 60% to 78% based on the mass of the polymeric monomers, the sulfonate monomer content is 20% to 35%, and the hydrophobic associating monomer content is 2% to 5%.

[0014] In one specific embodiment, the primary crosslinking agent is N,N-methylenebisacrylamide.

[0015] In one specific embodiment, the secondary crosslinking agent is at least one selected from hexamethylenetetramine, resorcinol, p-phenylenediamine, zirconium acetate, and chromium acetate.

[0016] In one specific embodiment, the initiator is dicumyl peroxide and / or tert-butanol peroxide.

[0017] In one specific embodiment, the promoter is tetramethylethylenediamine.

[0018] In one specific embodiment, the crosslinking polymer is at least one of partially hydrolyzed polyacrylamide, partially hydrolyzed polyacrylonitrile, and acrylamide-acrylic acid-octadecyltrimethylammonium chloride copolymer.

[0019] In one specific embodiment, the partially hydrolyzed polyacrylamide has a viscosity-average molecular weight of 15 million to 18 million and a degree of hydrolysis of 20% to 25%.

[0020] In one specific embodiment, the partially hydrolyzed polyacrylonitrile has a viscosity-average molecular weight of 15 million to 18 million and a degree of hydrolysis of 35% to 40%.

[0021] In one specific embodiment, the acrylamide-acrylic acid-octadecyltrimethylammonium chloride copolymer has a viscosity-average molecular weight of 15 million to 18 million.

[0022] In one specific embodiment, the stabilizer is thiourea.

[0023] In one specific embodiment, based on the mass of liquid A as 100%, the content of the first chelating agent is 2% to 4%, and the content of the polymeric monomer is 3% to 6%.

[0024] In one specific embodiment, the primary crosslinking agent comprises 1% to 5% by mass of the polymeric monomer; the accelerator comprises 0.1% to 0.2% by mass; and the initiator comprises 0.5% to 1% by mass.

[0025] In one specific embodiment, based on the mass of liquid B as 100%, the content of the second chelating agent is 3% to 6%, the content of the crosslinking polymer is 0.4% to 1.2%, the content of the secondary crosslinking agent is 0.5% to 1.5%, and the content of the stabilizer is 0.05% to 0.1%.

[0026] The second aspect of the present invention provides the water-blocking agent prepared by the preparation method according to any one of the present inventions.

[0027] The beneficial effects of this invention are:

[0028] (1) Excellent resistance to water dilution. Conventional polymer gel-type water shut-off agents mainly consist of polymer crosslinking systems and monomer polymerization systems. Water-soluble polymers or monomers are often selected as reaction reagents. After contact with formation water in a high-temperature environment, they are dispersed and diluted, resulting in poor gel quality or even difficulty in gel formation. This invention uses a pre-crosslinked weak gel as the primary structure. The injected water is mechanically encapsulated in the pores of the porous gel, improving the resistance to formation water dilution.

[0029] (2) Excellent water-blocking ability. Secondary water-soluble crosslinking agents such as hexamethylenetetramine are hidden inside the pre-crosslinked weak gel. As the ambient temperature rises, the reactive substances or catalysts are released. Aldehyde groups or aromatic amine groups react with amide groups in the primary structure to form a secondary interpenetrating crosslinking network, which further improves the strength of the water-blocking agent and plays the role of a pre-baffle.

[0030] (3) It has a certain ability to regulate gel time. The amide group is hydrolyzed at high temperature to form a carboxylic acid group, which reduces the reactivity and causes a decrease in gel strength. Taking advantage of the characteristic that the cyano group in partially hydrolyzed polyacrylonitrile can be hydrolyzed into an amide group, and at the same time, the hexamethylenetetramine crosslinking agent hydrolyzes to generate a reactive aldehyde group as the temperature increases, thereby reserving more potential reactive sites and improving the ability to regulate gel time in a high-temperature environment. Attached Figure Description

[0031] Figure 1 The diagram shows the state of the water-blocking agent prepared in Example 1 after curing at ambient temperature for 5 hours.

[0032] Figure 2 The diagram shows the state of the water-blocking agent prepared in Example 1 after being placed at 140°C for 5 hours.

[0033] Figure 3 The diagram shows the state of the water-blocking agent prepared in Comparative Example 1 after being placed at 140°C for 5 hours.

[0034] Figure 4 The diagram shows the state of the water-blocking agent prepared in Comparative Example 2 after being placed at 140°C for 5 hours.

[0035] Figure 5 The image shows a scanning electron microscope observation of the water-blocking agent prepared in Example 1 after curing at ambient temperature for 5 hours.

[0036] Figure 6 The image shows a scanning electron microscope observation of the water-blocking agent prepared in Example 1 after being placed at 140°C for 5 hours. Detailed Implementation

[0037] The present invention will be further described below with reference to the embodiments. However, the embodiments of the present invention are merely illustrative examples and should not be construed as limiting the present invention under any circumstances.

[0038] The content of various mineral ions in the formation water used in the following examples is shown in Table 1.

[0039] Table 1. Concentrations of various mineral ions in the formation water used in each embodiment of the present invention.

[0040]

[0041] Example 1

[0042] A method for preparing an impact-resistant dilute gel baffle water-blocking agent based on a secondary cross-linked structure, comprising the following steps:

[0043] (1) Add 3g of chelating agent sodium carbonate, 4.5g of polymer monomer to 92.5g of formation water, then add 135mg (3% of the total monomer mass) of primary crosslinking agent N,N-methylenebisacrylamide, 6.75mg of accelerator tetramethylethylenediamine (0.15% of the total monomer mass), and 33.75mg of initiator dicumyl peroxide (0.75% of the total monomer mass) and stir until homogeneous to obtain solution A;

[0044] The total mass of the polymerized monomers is 100%, comprising 3.105 g (69% by mass) acrylamide, 1.2375 g sodium 3-allyloxy-2-hydroxy-1-propanesulfonate (27.5% by mass) and 0.1575 g octadecyltrimethylammonium chloride (3.5% by mass).

[0045] (2) Add 4.5g of chelating agent sodium carbonate, 0.8g of partially hydrolyzed polyacrylamide (viscosity-average molecular weight 18 million, degree of hydrolysis 25%), 1g of secondary crosslinking agent (a combination of 0.5g hexamethylenetetramine and 0.5g resorcinol), and 0.075g of stabilizer thiourea to 93.625g of formation water and stir until homogeneous to obtain solution B;

[0046] (3) Mix liquid A and liquid B evenly to obtain an impact-resistant dilute gel baffle water-blocking agent based on a secondary cross-linking structure.

[0047] Example 2

[0048] A method for preparing an impact-resistant dilute gel baffle water-blocking agent based on a secondary cross-linked structure, comprising the following steps:

[0049] (1) Add 2g of chelating agent sodium carbonate and 3g of polymerizing monomer to 95g of formation water, then add 150mg (5% of the total monomer mass) of primary crosslinking agent N,N-methylenebisacrylamide, 3mg of accelerator tetramethylethylenediamine (0.1% of the total monomer mass), and 15mg of initiator dicumyl peroxide (0.5% of the total monomer mass). Stir until homogeneous to obtain solution A.

[0050] The total mass of the monomers is 100%, including 2.25g acrylamide and 0.09g N,N-dimethylacrylamide (78% by mass), 0.6g sodium 3-allyloxy-2-hydroxy-1-propanesulfonate (20% by mass), and 0.06g octadecyltrimethylammonium chloride (2% by mass).

[0051] (2) Add 6g of chelating agent sodium carbonate, 0.4g of partially hydrolyzed polyacrylonitrile (viscosity-average molecular weight 18 million, degree of hydrolysis 40%), 0.5g of secondary crosslinking agent (a combination of 0.4g of p-phenylenediamine and 0.1g of zirconium acetate), and 0.1g of stabilizer thiourea to 93g of formation water and stir until homogeneous to obtain solution B.

[0052] (3) Mix liquid A and liquid B evenly to obtain an impact-resistant dilute gel baffle water-blocking agent based on a secondary cross-linking structure.

[0053] Example 3

[0054] A method for preparing an impact-resistant dilute gel baffle water-blocking agent based on a secondary cross-linked structure, comprising the following steps:

[0055] (1) Add 4g of chelating agent sodium carbonate and 6g of polymerizing monomer to 90g of formation water in sequence, then add 60mg (1% of the total mass of monomer) of primary crosslinking agent N,N-methylenebisacrylamide, 12mg of accelerator tetramethylethylenediamine (0.2% of the total mass of monomer) and 60mg of initiator hydrogen peroxide tert-butanol (1% of the total mass of monomer) and stir evenly to obtain solution A;

[0056] The total mass of the monomers is 100%, including 3.6g N,N-dimethylacrylamide (60% by mass), 2.1g sodium allyl sulfonate (35% by mass), and 0.3g cetyltrimethylammonium bromide (5% by mass).

[0057] (2) Add 3g of chelating agent sodium carbonate, 1.2g of acrylamide-acrylic acid-octadecyltrimethylammonium chloride copolymer (viscosity average molecular weight 18 million), 1.5g of secondary crosslinking agent (a combination of 1g of p-phenylenediamine and 0.5g of chromium acetate), and 0.075g of stabilizer thiourea to 94.225g of formation water and stir until homogeneous to obtain solution B;

[0058] (3) Mix liquid A and liquid B evenly to obtain an impact-resistant dilute gel baffle water-blocking agent based on a secondary cross-linking structure.

[0059] Example 4

[0060] A method for preparing an impact-resistant dilute gel baffle water-blocking agent based on a secondary cross-linked structure, comprising the following steps:

[0061] (1) Add 3g of chelating agent sodium carbonate and 5g of polymer monomer to 92g of formation water in sequence, then add 150mg (3% of the total mass of monomer) of primary crosslinking agent N,N-methylenebisacrylamide, 8.5mg of accelerator tetramethylethylenediamine (0.17% of the total mass of monomer), and 37.5mg of initiator hydrogen peroxide tert-butanol (0.75% of the total mass of monomer) and stir until homogeneous to obtain solution A;

[0062] The total mass of the monomers is 100%, including 3.5g acrylamide (70% by mass), 1.375g sodium styrene sulfonate (27.5% by mass), and 0.125g octadecyltrimethylammonium chloride (2.5% by mass).

[0063] (2) Add 6g of chelating agent sodium carbonate, 1.2g of acrylamide-acrylic acid-octadecyltrimethylammonium chloride copolymer (viscosity average molecular weight 15 million), 1.5g of secondary crosslinking agent (a combination of 0.75g hexamethylenetetramine and 0.75g resorcinol), and 0.1g of stabilizer thiourea to 91.2g of formation water and stir until homogeneous to obtain solution B;

[0064] (3) Mix liquid A and liquid B evenly to obtain an impact-resistant dilute gel baffle water-blocking agent based on a secondary cross-linking structure.

[0065] Example 5

[0066] A method for preparing an impact-resistant dilute gel baffle water-blocking agent based on a secondary cross-linked structure, comprising the following steps:

[0067] (1) Add 3g of chelating agent sodium carbonate and 5g of polymer monomer to 92g of formation water in sequence, then add 150mg (3% of the total mass of monomer) of primary crosslinking agent N,N-methylenebisacrylamide, 8.5mg of accelerator tetramethylethylenediamine (0.17% of the total mass of monomer), and 37.5mg of initiator hydrogen peroxide tert-butanol (0.75% of the total mass of monomer) and stir until homogeneous to obtain solution A;

[0068] The total mass of the monomers is 100%, including 3.5g (70% by mass) acrylamide, 1.4g sodium 3-allyloxy-2-hydroxy-1-propanesulfonate (28% by mass) and 0.1g octadecyltrimethylammonium chloride (2% by mass).

[0069] (2) Add 3g of chelating agent sodium carbonate, 0.4g of partially hydrolyzed polyacrylamide (viscosity-average molecular weight 15 million, degree of hydrolysis 20%), 0.5g of secondary crosslinking agent (a combination of 0.25g of p-phenylenediamine and 0.25g of zirconium acetate), and 0.05g of stabilizer thiourea to 96.05g of formation water and stir until homogeneous to obtain solution B;

[0070] (3) Mix liquid A and liquid B evenly to obtain an impact-resistant dilute gel baffle water-blocking agent based on a secondary cross-linking structure.

[0071] Example 6

[0072] A method for preparing an impact-resistant dilute gel baffle water-blocking agent based on a secondary cross-linked structure, comprising the following steps:

[0073] (1) Add 4g of chelating agent sodium carbonate and 3g of polymerizing monomer to 93g of formation water in sequence, then add 30mg (1% of the total monomer mass) of primary crosslinking agent N,N-methylenebisacrylamide, 4.5mg of accelerator tetramethylethylenediamine (0.15% of the total monomer mass), and 22.5mg of initiator dicumyl peroxide (0.75% of the total monomer mass) and stir until homogeneous to obtain solution A;

[0074] The total mass of the monomers is 100%, including 3.5g (70% by mass) acrylamide, 1.4g sodium 3-allyloxy-2-hydroxy-1-propanesulfonate (28% by mass) and 0.1g octadecyltrimethylammonium chloride (2% by mass).

[0075] (2) Add 6g of chelating agent sodium carbonate, 0.8g of partially hydrolyzed polyacrylonitrile (viscosity-average molecular weight 15 million, degree of hydrolysis 35%), 0.5g of secondary crosslinking agent (a combination of 0.25g of p-phenylenediamine and 0.25g of zirconium acetate), and 0.05g of stabilizer thiourea to 92.65g of formation water and stir until homogeneous to obtain solution B;

[0076] (3) Mix liquid A and liquid B evenly to obtain an impact-resistant dilute gel baffle water-blocking agent based on a secondary cross-linking structure.

[0077] Comparative Example 1

[0078] This comparative example provides a method for preparing a water-blocking agent, the steps of which are as follows:

[0079] Add 0.8g of partially hydrolyzed polyacrylamide (viscosity-average molecular weight 18 million, degree of hydrolysis 25%), 1g of crosslinking agent (a combination of 0.5g hexamethylenetetramine and 0.5g resorcinol), and 0.075g of stabilizer thiourea to 98.125g of formation water and stir until homogeneous to obtain a water-blocking agent.

[0080] Comparative Example 2

[0081] This comparative example provides a method for preparing a water-blocking agent, the steps of which are as follows:

[0082] Add 4.5g of chelating agent sodium carbonate, 0.8g of partially hydrolyzed polyacrylamide (viscosity-average molecular weight 18 million, degree of hydrolysis 25%), 1g of crosslinking agent (a combination of 0.5g hexamethylenetetramine and 0.5g resorcinol), and 0.075g of stabilizer thiourea to 93.625g of formation water and stir until homogeneous to obtain a water-blocking agent.

[0083] Performance evaluation of water-blocking agents

[0084] The water-blocking agents prepared in Examples 1 to 6, as well as Comparative Examples 1 and 2, were cured at ambient temperature for 5 hours. The apparent gel strength of the water-blocking agents was observed using the visual code method, and their apparent viscosity was measured using a Brookfield viscometer. The results are shown in Table 1. Subsequently, the agents were placed in a sealed metal curing vessel and pressurized with nitrogen to 1.0 MPa (the purpose of pressurization is to ensure that the ambient pressure is higher than the saturated vapor pressure of the solvent at this temperature, thereby avoiding the actual temperature inside the container from falling below the design temperature due to solvent evaporation). The sealed metal curing vessel was then placed in an electric thermostatic drying oven and cured at 140°C for 5 hours. The sealed metal curing vessel was then removed and allowed to return to ambient temperature. The pressure inside the metal curing vessel was released, and the apparent gel strength of the water-blocking agents was observed using the visual code method. The elastic modulus was measured using a MARSIII Hacker rheometer. The results are shown in Table 1. Among them, the visual code method given in Chinese patent CN 109181664B "A temperature-resistant gel plugging agent of phenylenediamine crosslinked polyacrylamide and its preparation method" is used to evaluate the gel strength of the plugging agent at different curing times.

[0085] Figure 1 The image shows the gel-forming state of the water-blocking agent prepared in Example 1 after curing at ambient temperature for 5 hours.

[0086] Figure 2 The image shows the gel-forming state of the water-blocking agent prepared in Example 1 after curing at 140°C for 5 hours.

[0087] Figure 3 The image shows the gel-forming state of the water-blocking agent prepared for Comparative Example 1 after curing at 140℃ for 5 hours.

[0088] Figure 4 The image shows the gel-forming state of the water-blocking agent prepared in Comparative Example 2 after curing at 140℃ for 5 hours.

[0089] Figure 5 The results of scanning electron microscopy observation of the water-blocking agent prepared in Example 1 after curing at natural ambient temperature for 5 hours.

[0090] Figure 6 The results of scanning electron microscopy observation of the water-blocking agent prepared in Example 1 after curing at 140°C for 5 hours.

[0091] Table 1

[0092]

[0093] According to the experimental results in Table 1:

[0094] (1) After curing at ambient temperature for 5 hours, the water-blocking agents prepared in Examples 1 to 6 exhibited a macroscopic morphology of a viscous, highly fluid, weak gel with an apparent viscosity ranging from 1500 mPa·s to 2500 mPa·s and a strength code of B. Due to the covalent cross-linking of the prepolymer, the water-blocking agent possessed excellent resistance to water dilution and erosion, which facilitated the stable advancement of the leading edge of the pore-type medium and prevented the "pancake phenomenon." After curing at 140℃ for 5 hours, the mechanical strength of the secondary cross-linking product increased from grade B to grade G or H, with an elastic modulus ranging from 1000 Pa to 1600 Pa. Furthermore, combined with scanning electron microscopy observations, the network structure of the gel product after secondary cross-linking was denser than that of the primary pre-cross-linked weak gel, and the mesh formed by the interlacing of chain bundles was smaller, further demonstrating the improvement in the mechanical properties of the gel after secondary cross-linking. Thus, through secondary cross-linking, the sealing ability of three-dimensional pore-type structures was further enhanced, playing the role of a pre-baffle.

[0095] (2) The water-blocking agents prepared in Comparative Examples 1 and 2 showed low apparent viscosity after curing at ambient temperature for 5 hours. This is because the viscosity contribution mainly comes from linear polymers such as partially hydrolyzed polyacrylamide, and their resistance to water dilution and scouring is weaker than that of the pre-crosslinked, weakly fluid gels in Examples 1 to 5. After curing at 140°C for 5 hours, although the mechanical strength improved and the strength code reached grade D, and the elastic modulus approached 500 Pa, the amide groups are prone to hydrolysis in high-temperature and high-salt environments to generate carboxylic acid groups. However, the reaction conditions of carboxylic acid groups are difficult to adapt to the temperature and pressure environment of the reservoir, and they cannot be used as covalent crosslinking sites. Therefore, their mechanical properties are still far lower than those of the double-network gels formed by secondary crosslinking in Examples 1 to 5, which is insufficient to effectively seal three-dimensional cavities.

[0096] By combining and comparing the experimental results of the examples and comparative examples, the following three conclusions can be drawn: (1) The mechanical strength of the primary cross-linked polymer is low, making it difficult to form a high-strength and tough baffle structure; (2) The primary pre-cross-linked weak flow gel formed by the polymerization of acrylamide monomers exists in the form of covalent cross-linking, which gives the water-blocking agent good resistance to water dilution and water erosion; (3) The primary structure formed by the polymerization of acrylamide monomers and the secondary structure formed by the cross-linked polymer interpenetrate each other to form a polymer interpenetrating network system gel, which can improve the gelation performance of a single polymer network.

[0097] While the present invention has been described with reference to specific embodiments, those skilled in the art will understand that various changes can be made without departing from the true spirit and scope of the invention. Furthermore, numerous modifications can be made to the subject, spirit, and scope of the invention to suit specific situations, materials, material compositions, and methods. All such modifications are included within the scope of the claims of the present invention.

Claims

1. A method for preparing a water-blocking agent, comprising the following steps: 1) Mix water, the first chelating agent, the polymerizing monomer, the primary crosslinking agent, the initiator, and the accelerator evenly to obtain solution A; 2) Mix water, the second chelating agent, polymer A, the secondary crosslinking agent, and the stabilizer evenly to obtain solution B; 3) Mix liquid A and liquid B evenly to obtain the water-blocking agent; The first chelating agent and the second chelating agent are independently sodium carbonate; The polymerization monomers are amide monomers, sulfonate monomers, and hydrophobic associating monomers; The amide monomer is acrylamide and / or N,N-dimethylacrylamide; The sulfonate monomer is at least one of sodium 3-allyloxy-2-hydroxy-1-propanesulfonate, sodium styrenesulfonate, and sodium allylsulfonate. The hydrophobic associating monomer is at least one of octadecyltrimethylammonium chloride and / or hexadecyltrimethylammonium bromide; The accelerator is tetramethylethylenediamine; The polymer A is at least one of partially hydrolyzed polyacrylamide and partially hydrolyzed polyacrylonitrile.

2. The preparation method according to claim 1, characterized in that, The content of the acrylamide monomer is 60% to 78% based on the mass of the polymerizable monomers, the content of the sulfonate monomers is 20% to 35%, and the content of the hydrophobic associating monomers is 2% to 5%.

3. The preparation method according to claim 1, characterized in that, The primary crosslinking agent is N,N-methylenebisacrylamide; and / or The secondary crosslinking agent is at least one of hexamethylenetetramine, resorcinol, p-phenylenediamine, zirconium acetate, and chromium acetate.

4. The preparation method according to claim 1, characterized in that, The initiator is dicumyl peroxide and / or tert-butanol peroxide.

5. The preparation method according to claim 1, characterized in that, The partially hydrolyzed polyacrylamide has a viscosity-average molecular weight of 15 million to 18 million and a degree of hydrolysis of 20% to 25%.

6. The preparation method according to claim 1, characterized in that, The partially hydrolyzed polyacrylonitrile has a viscosity-average molecular weight of 15 million to 18 million and a degree of hydrolysis of 35% to 40%.

7. The preparation method according to claim 1, characterized in that, The stabilizer is thiourea.

8. The preparation method according to claim 1, characterized in that, Based on the mass of liquid A as 100%, the content of the first chelating agent is 2% to 4%, and the content of the polymeric monomer is 3% to 6%.

9. The preparation method according to claim 1, characterized in that, The content of the primary crosslinking agent is 1% to 5% based on the mass of the polymerizing monomer (100%); the content of the accelerator is 0.1% to 0.2%; the content of the initiator is 0.5% to 1%; and / or Based on the mass of liquid B as 100%, the content of the second chelating agent is 3% to 6%, the content of polymer A is 0.4% to 1.2%, the content of the secondary crosslinking agent is 0.5% to 1.5%, and the content of the stabilizer is 0.05% to 0.1%.

10. The water-blocking agent prepared by the preparation method according to any one of claims 1 to 9.

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