Modified resin film-forming sealant and method of making same

Abstract

This invention relates to the field of oilfield additives technology, specifically a modified resin film-forming plugging agent and its preparation method. The former uses modified high-temperature resistant unsaturated polyester resin and polypropylene as raw materials. The latter is prepared by spraying 1 to 1.5 parts of polypropylene onto 3 to 3.5 parts of modified high-temperature resistant unsaturated polyester resin at 175°C to 185°C, followed by cooling to obtain the modified resin film-forming plugging agent. This invention utilizes modified high-temperature resistant unsaturated polyester resin and polypropylene as main raw materials. Polypropylene is typically soluble in organic solvents such as toluene but insoluble in water. In water-based drilling fluids, it forms a solid phase to seal micro-fractures and reduce filtration loss. Furthermore, the outer polypropylene layer becomes liquid under formation temperature. The hydrophobicity of polypropylene allows it to adsorb onto the wellbore, increasing the bonding performance of the wellbore and thus enhancing its strength, stability, and reducing well leakage.

Description

Technical Field

[0001] This invention relates to the field of oilfield additives technology, specifically a modified resin film-forming and sealing agent and its preparation method. Background Technology

[0002] Modified resin film-forming plugging agents belong to the field of petroleum drilling engineering chemical agents technology, specifically involving a functional material used in oil and gas drilling processes to stabilize the wellbore and seal formation fractures. In oil and gas drilling operations, drilling fluid (also known as drilling mud) is a crucial process material ensuring the smooth progress of drilling operations, possessing important functions such as cooling and lubricating the drill bit, removing wellbore debris, balancing formation pressure, and sealing formation fractures and pores. Among these, plugging and inhibition performance are key technical indicators for maintaining wellbore stability and reducing mud loss, directly affecting the safety and economy of drilling operations.

[0003] Wellbore leakage and wellbore instability are common accidents during drilling, seriously threatening drilling safety, reducing drilling efficiency, and significantly increasing drilling costs. Wellbore leakage, a common drilling accident, refers to the process of fluid entering the wellbore through the wellbore wall, causing a decrease in fluid column pressure and affecting normal production. Causes include low formation pressure and excessive drilling fluid loss. Wellbore instability refers to the disruption of the stable relationship between the wellbore and the formation. During drilling, due to complex and variable geological conditions, wellbore instability is frequently encountered, seriously affecting the smooth progress of drilling operations. Especially in shale formations, wellbore instability is one of the most serious and complex situations in oil and gas drilling engineering; approximately 90% of wellbore stability problems worldwide occur in shale formations. As oil and gas exploration and development extend to deeper formations and areas with complex geological conditions, the demand for high-performance plugging agents is increasingly urgent, driving the innovative development of modified resin film-forming plugging agent technology.

[0004] Chinese patent document CN118562464A discloses a drilling fluid nanofilm-forming plugging agent and its preparation method. The drilling fluid nanofilm-forming plugging agent comprises the following components by weight: emulsifier, glyceryl stearate, pentaerythritol stearate, styrene, styrene-propylene, methyl methacrylate, chloroprene latex, chlorinated paraffin, nano-titanium oxide, catalyst, diethylene glycol monobutyl ether, and water. While this technical solution presents innovative ideas for nanofilm plugging and film-forming performance, its design and implementation process suffers from high complexity, difficulty in industrial production, stringent preparation processes, and environmental and safety deficiencies. For example, chloroprene latex and chlorinated paraffin may contain chlorinated persistent organic pollutants, and diethylene glycol monobutyl ether (a potential endocrine disruptor) may also be present, which does not align with the trend of green drilling fluid development.

[0005] Chinese patent document CN106479456B discloses a method for preparing a multi-component vinyl polymer emulsion for drilling fluid film-forming and sealing. The method involves preparing the raw materials according to the specified proportions; adding 4 / 5 of the formulated amount of solvent and emulsifier sequentially to reactor No. 1, heating to 50-70℃, and stirring for 20-30 minutes; then adding styrene, maleic anhydride, acrylate, initiator, and molecular weight regulator sequentially, raising the temperature to 70-80℃, starting the reaction timer, stopping heating after 1 hour, and cooling; adding 1 / 5 of the formulated amount of solvent, stabilizer, scavenger, defoamer, and modified nano-calcium carbonate sequentially to reactor No. 2, and stirring at room temperature for 30-40 minutes; and slowly adding the mixture obtained in step d to reactor No. 1, reacting at 40-50℃ for 2-3 hours to obtain a multi-component vinyl polymer emulsion film-forming and sealing agent. The film-forming plugging agent has insufficient temperature resistance (150℃), salt resistance, and multi-scale plugging ability, making it difficult to meet the needs of deep wells and complex formations.

[0006] Therefore, there is a need to develop a new film-forming plugging agent that provides a systematic solution to the key bottlenecks in existing technologies. This is expected to significantly improve the efficiency and safety of drilling operations, reduce overall costs, and has significant industrial application value and market prospects. Summary of the Invention

[0007] This invention provides a modified resin film-forming plugging agent and its preparation method, which overcomes the shortcomings of the prior art and can effectively solve the problem that complex and variable geological conditions in the existing drilling process lead to wellbore instability, thereby affecting the smooth progress of drilling operations.

[0008] One of the technical solutions of this invention is achieved through the following measures: a modified resin film-forming blocker, comprising, by weight, 3 to 3.5 parts of modified high-temperature resistant unsaturated polyester resin and 1 to 1.5 parts of polypropylene, obtained by the following method: spraying 1 to 1.5 parts of polypropylene onto 3 to 3.5 parts of modified high-temperature resistant unsaturated polyester resin at 175°C to 185°C, and obtaining the modified resin film-forming blocker after cooling, wherein the modified high-temperature resistant unsaturated polyester resin is prepared by the following method:

[0009] S1, add the required amount of maleic anhydride to ethylene glycol to react, stir until the viscosity of the reaction product no longer changes, stop the reaction, remove the solvent on the upper part of the reaction product to obtain the first emulsion;

[0010] S2, add the first crosslinking agent to the obtained first emulsion and react, stirring until the viscosity of the reaction product no longer changes, to obtain high-temperature resistant unsaturated polyester resin;

[0011] S3. Add the required amount of nano-silica to the high-temperature resistant unsaturated polyester resin, mix evenly, and then react. Stir until the viscosity of the reaction product no longer changes. After cooling to room temperature, crush, grind, and screen to obtain the modified high-temperature resistant unsaturated polyester resin.

[0012] The following are further optimizations and / or improvements to one of the above-mentioned technical solutions:

[0013] In step S1 above, the mass ratio of maleic anhydride to ethylene glycol is 1:4, the reaction temperature is 185℃ to 195℃, and the reaction time is 1h to 2h.

[0014] In step S2 above, the first crosslinking agent is a mixture of dimethacrylates and 4-methylstyrene in a molar ratio of 1:2.5 to 3.5.

[0015] In step S2 above, the mass ratio of the first emulsion to the first crosslinking agent is 100:1 to 1.5, the reaction temperature is 185°C to 195°C, and the reaction time is 1h to 2h.

[0016] In step S3 above, the mass ratio of nano-silica to high-temperature resistant unsaturated polyester resin is 1:1, the reaction temperature is 185℃ to 195℃, and the reaction time is 0.5h to 1h.

[0017] In step S3 above, the particle size range of the crushing, grinding and screening is 1μm to 50μm.

[0018] The second technical solution of the present invention is achieved through the following measures: a method for preparing a modified resin film-forming blocker, comprising the following steps: spraying 1 to 1.5 parts of polypropylene onto 3 to 3.5 parts of a modified high-temperature resistant unsaturated polyester resin at a temperature of 175°C to 185°C, and obtaining the modified resin film-forming blocker after cooling, wherein the modified high-temperature resistant unsaturated polyester resin is prepared according to the following method:

[0019] S1, add the required amount of maleic anhydride to ethylene glycol to react, stir until the viscosity of the reaction product no longer changes, stop the reaction, remove the solvent on the upper part of the reaction product to obtain the first emulsion;

[0020] S2, add the first crosslinking agent to the obtained first emulsion and react, stirring until the viscosity of the reaction product no longer changes, to obtain high-temperature resistant unsaturated polyester resin;

[0021] S3. Add the required amount of nano-silica to the high-temperature resistant unsaturated polyester resin, mix evenly, and then react. Stir until the viscosity of the reaction product no longer changes. After cooling to room temperature, crush, grind, and screen to obtain the modified high-temperature resistant unsaturated polyester resin.

[0022] The following are further optimizations and / or improvements to the second technical solution of the above invention:

[0023] In step S1 above, the mass ratio of maleic anhydride to ethylene glycol is 1:4, the reaction temperature is 185℃ to 195℃, and the reaction time is 1h to 2h.

[0024] In step S2 above, the first crosslinking agent is a mixture of dimethacrylate and 4-methylstyrene in a molar ratio of 1:2.5 to 3.5, the mass ratio of the first emulsion to the first crosslinking agent is 100:1 to 1.5, the reaction temperature is 185°C to 195°C, and the reaction time is 1h to 2h.

[0025] In step S3 above, the mass ratio of nano-silica to high-temperature resistant unsaturated polyester resin is 1:1, the reaction temperature is 185℃ to 195℃, the reaction time is 0.5h to 1h, and the particle size range of the pulverized, ground, and screened particles is 1μm to 50μm.

[0026] This invention utilizes modified high-temperature resistant unsaturated polyester resin and polypropylene as the main raw materials. These materials are generally soluble in organic solvents such as toluene but insoluble in water. In water-based drilling fluids, they form a solid phase to seal micro-cracks and reduce filtration loss. Furthermore, the outer polypropylene layer becomes liquid under formation temperature. The hydrophobicity of polypropylene can adsorb onto the well wall, increasing the bonding performance of the well wall and thus enhancing its strength, stability, and reducing well leakage. Detailed Implementation

[0027] This invention is not limited to the following embodiments; specific implementation methods can be determined based on the technical solution of this invention and actual circumstances. Unless otherwise specified, all chemical reagents and chemical products mentioned in this invention are well-known and commonly used chemical reagents and chemical products in the prior art.

[0028] The present invention will be further described below with reference to embodiments:

[0029] Example 1: This modified resin film-forming blocker comprises, by weight, 3 to 3.5 parts of modified high-temperature resistant unsaturated polyester resin and 1 to 1.5 parts of polypropylene, obtained by the following method: 1 to 1.5 parts of polypropylene are sprayed onto 3 to 3.5 parts of modified high-temperature resistant unsaturated polyester resin at 175°C to 185°C, and after cooling, the modified resin film-forming blocker is obtained. The modified high-temperature resistant unsaturated polyester resin is prepared by the following method:

[0030] S1, add the required amount of maleic anhydride to ethylene glycol to react, stir until the viscosity of the reaction product no longer changes, stop the reaction, remove the solvent on the upper part of the reaction product to obtain the first emulsion;

[0031] S2, add the first crosslinking agent to the obtained first emulsion and react, stirring until the viscosity of the reaction product no longer changes, to obtain high-temperature resistant unsaturated polyester resin;

[0032] S3. Add the required amount of nano-silica to the high-temperature resistant unsaturated polyester resin, mix evenly, and then react. Stir until the viscosity of the reaction product no longer changes. After cooling to room temperature, crush, grind, and screen to obtain the modified high-temperature resistant unsaturated polyester resin.

[0033] In this invention, rigid polypropylene particles can effectively seal and support fractures, compress the formation around the well, and increase the tangential stress around the well, thereby increasing the formation fracturing pressure on the wellbore and forming a stress cage to prevent fracture propagation. By regulating the tangential stress field around the well and the stress field at the fracture tip, a balance between the wellbore fluid column pressure and the geostress field is established to control leakage and maintain wellbore stability. The film-forming properties of spraying polypropylene onto modified high-temperature resistant unsaturated polyester resin facilitate the formation of a dense, high-strength sealing film on the wellbore while sealing leakage channels. Under the influence of formation temperature, pressure, and fluid conditions, a physicochemical reaction occurs, cementing weak structural surfaces of the rock mass to increase rock mass strength or forming a high-strength structure. This isolates the two pressure systems of the wellbore and the formation, improving the formation's pressure-bearing capacity while stabilizing the wellbore.

[0034] Example 2: As an optimization of the above example, in step S1, the mass ratio of maleic anhydride to ethylene glycol is 1:4, the reaction temperature is 185°C to 195°C, and the reaction time is 1h to 2h.

[0035] Example 3: As an optimization of the above example, in step S2, the first crosslinking agent is a mixture of dimethacrylates and 4-methylstyrene in a molar ratio of 1:2.5 to 3.5.

[0036] Example 4: As an optimization of the above example, in step S2, the mass ratio of the first emulsion to the first crosslinking agent is 100:1 to 1.5, the reaction temperature is 185°C to 195°C, and the reaction time is 1h to 2h.

[0037] Example 5: As an optimization of the above example, in step S3, the mass ratio of nano-silica to high-temperature resistant unsaturated polyester resin is 1:1, the reaction temperature is 185°C to 195°C, and the reaction time is 0.5h to 1h.

[0038] Example 6: As an optimization of the above example, in step S3, the particle size range of the crushing, grinding and screening is 1μm to 50μm.

[0039] Example 7: The preparation method of the modified resin film-forming blocker is carried out according to the following method: 1 to 1.5 parts of polypropylene are sprayed onto 3 to 3.5 parts of modified high-temperature resistant unsaturated polyester resin at 175°C to 185°C. After cooling, the modified resin film-forming blocker is obtained. The modified resin film-forming blocker is obtained according to the following method:

[0040] S1, add 100g maleic anhydride to 400g ethylene glycol, gradually heat to 190℃, react at 190℃ for 1h, stir until the viscosity of the reaction product no longer changes, stop the reaction, remove the solvent on the top of the reaction product to obtain the first emulsion.

[0041] S2, add 2g of the first crosslinking agent to the obtained first emulsion, react at 190℃ for 1h, stir until the viscosity of the reaction product no longer changes, and obtain high temperature resistant unsaturated polyester resin, wherein the first crosslinking agent is a mixture of dimethacrylate and 4-methylstyrene in a molar ratio of 1:3;

[0042] S3, 200g of nano-silica was added to the high-temperature resistant unsaturated polyester resin at 190℃ and mixed evenly. The mixture was then reacted for 0.5h. The mixture was stirred until the viscosity of the reaction product no longer changed. After cooling to room temperature, the mixture was crushed, ground and screened to obtain the reaction product with a particle size range of 10μm to 30μm, thus obtaining the modified high-temperature resistant unsaturated polyester resin.

[0043] S4, at 180℃, 100g of polypropylene is sprayed onto 300g of modified high-temperature resistant unsaturated polyester resin, and after cooling, a modified resin film-forming blocker is obtained.

[0044] Experimental Example 1: The modified resin film-forming blocking agent obtained in Example 7 was subjected to performance testing. The specific process is as follows:

[0045] First, take 10g of modified resin film-forming sealant and add it to 100mL of diesel under continuous stirring. Put the resulting mixture into a high-temperature aging tank, fill the tank with 0.7MPa nitrogen, and place it in a high-temperature roller furnace for aging at 120℃ for 24h.

[0046] The second step is to observe the above mixture. The upper liquid is clear and transparent, indicating that it has good temperature resistance and oil resistance.

[0047] The third step is to filter the above mixture, dry the filter residue at 105°C, and weigh the filter residue at 9.98g, which further demonstrates that it has good temperature resistance and oil resistance.

[0048] Experiment Example 2: The difference between this experiment and Experiment Example 1 is that in the first step, 100mL of diesel fuel is replaced with 100mL of water. The rest of the process is the same, as follows:

[0049] First, take 10g of modified resin film-forming sealant, add it to 100mL of water under continuous stirring, put the resulting mixture into a high-temperature aging tank, fill the tank with 0.7MPa nitrogen, and put it into a high-temperature roller furnace for aging at 120℃ for 24h.

[0050] The second step is to observe the above mixture. The upper liquid is clear and transparent, indicating that it has good temperature resistance and oil resistance.

[0051] The third step is to filter the above mixture, dry the filter residue at 105°C, and weigh the filter residue at 9.99g, which further demonstrates that it has good temperature resistance and oil resistance.

[0052] Experimental Example 3: The modified high-temperature resistant unsaturated polyester resin obtained in step S3 of Example 7 was subjected to performance testing. The specific process is as follows:

[0053] First, take 10g of modified high-temperature resistant unsaturated polyester resin, add it to 100mL of diesel under continuous stirring, put the resulting mixture into a high-temperature aging tank, fill the tank with 1.75MPa nitrogen gas, put it into a high-temperature roller furnace, and age it at 200℃ for 24h.

[0054] The second step is to observe the above mixture. The upper liquid is clear and transparent, indicating that the modified high-temperature resistant unsaturated polyester resin can remain intact in an oily environment at 200℃.

[0055] The third step involves filtering the above mixture, drying the filter residue at 105°C, and weighing the residue at 9.97g. This further demonstrates that the modified high-temperature resistant unsaturated polyester resin can remain intact in an oily environment at 200°C.

[0056] Experiment Example 4: The difference between this experiment and Experiment Example 3 is that in the first step, 100mL of diesel fuel is replaced with 100mL of water. The rest of the process is the same, as follows:

[0057] First, take 10g of modified high-temperature resistant unsaturated polyester resin, add 100mL of water under continuous stirring, put the resulting mixture into a high-temperature aging tank, fill the tank with 1.75MPa nitrogen gas, put it into a high-temperature roller furnace, and age at 200℃ for 24h.

[0058] The second step is to observe the above mixture. The upper liquid is clear and transparent, indicating that the modified high-temperature resistant unsaturated polyester resin has good high-temperature resistance and oil resistance.

[0059] The third step involves filtering the above mixture, drying the filter residue at 105°C, and weighing the residue at 9.98g. This further demonstrates that the modified high-temperature resistant unsaturated polyester resin has good high-temperature resistance and oil resistance.

[0060] Experimental Example 5: The modified resin film-forming blocking agent obtained in Example 7 was subjected to performance testing. The specific process is as follows:

[0061] First, take 10g of modified resin film-forming sealant and add it to 100mL of diesel under continuous stirring. Put the resulting mixture into a high-temperature aging tank, fill the tank with 0.7MPa nitrogen, and place it in a high-temperature roller furnace for aging at 200℃ for 24h.

[0062] The second step is to observe the above mixture. The upper liquid is clear and transparent, indicating that it has good temperature resistance and oil resistance.

[0063] The third step is to filter the above mixture, dry the filter residue at 105°C, and weigh the filter residue at 9.98g, which further demonstrates that it has good temperature resistance and oil resistance.

[0064] To further illustrate the effect of the modified resin film-forming blocker prepared in Example 7 above, other performance tests were conducted below.

[0065] (1) Filtration loss test

[0066] A drilling fluid-based slurry with a sodium bentonite content of 4% was prepared. The modified resin film-forming and plugging agent of the present invention was added at 4% of the mass of the drilling fluid-based slurry. Three parallel samples (with the modified resin film-forming and plugging agent of the present invention added) and three blank samples (without the modified resin film-forming and plugging agent of the present invention added) were taken. The API filtration loss after hot rolling at 150°C for 24 hours was tested. The final results are shown in Table 1.

[0067] As can be seen from Table 1, the API filtration loss of drilling fluid-based slurry after hot rolling at 150°C with the modified resin film-forming plugging agent of the present invention is 21 mL to 22 mL, which is much lower than that of the blank example. Therefore, it is shown that the modified resin film-forming plugging agent of the present invention has good temperature resistance and filtration loss reduction performance in water-based mud environment.

[0068] (2) High temperature and high pressure filtration loss test

[0069] Using an oil-based drilling fluid slurry consisting of 80% diesel oil, 3% SP80, 1% cutting agent, 2% organic soil, and 20% brine, the modified resin film-forming and plugging agent of this invention was added at 4% of the mass of the oil-based drilling fluid slurry. Three parallel samples (with the modified resin film-forming and plugging agent of this invention added) and three blank samples (without the modified resin film-forming and plugging agent of this invention added) were taken. The 180℃ HTHP filtration loss was tested after hot rolling at 180℃ for 24 hours. The final results are shown in Table 2.

[0070] As can be seen from Table 2, the HTHP filtration loss of the oil-based drilling fluid slurry after hot rolling at 180°C with the addition of the modified resin film-forming plugging agent of the present invention is 5 mL to 6 mL, which is much lower than that of the blank example. Therefore, it is shown that the modified resin film-forming plugging agent of the present invention can resist the high temperature of 180°C in oil-based mud and can significantly reduce the filtration loss under high temperature and high pressure.

[0071] (3) Blocking strength test

[0072] A drilling fluid-based slurry with a sodium-based bentonite content of 4% was prepared. The modified resin film-forming and plugging agent of this invention was added at 4% of the mass of the drilling fluid-based slurry. Three parallel samples (with the modified resin film-forming and plugging agent of this invention added) and three blank samples (without the modified resin film-forming and plugging agent of this invention added) were taken. Using a GGS71-A type or similar high-temperature and high-pressure filtration analyzer, a filter screen was added to the drilling fluid cup without filter paper. 400g of 40-60 mesh quartz sand was added. With the lower vent valve rod open, the quartz sand was inserted tightly and compacted with a small iron rod. The sample slurry was slowly added to the high-temperature and high-pressure drilling fluid cup (0.5cm to 1cm away from the rim of the cup) using a glass rod. The top cover of the drilling fluid cup was installed and locked. The upper valve rod was opened and the pressure was slowly increased to 0.7MPa and stabilized for 10 min. Then, the pressure was slowly and evenly increased to 5.0MPa and stabilized for 30 min. Its pressure-bearing capacity was measured. The final results are shown in Table 3.

[0073] As can be seen from Table 3, the oil-based drilling fluid slurry containing the modified resin film-forming plugging agent of the present invention can improve the strength of the plugging layer during drilling.

[0074] In summary, this invention utilizes modified high-temperature resistant unsaturated polyester resin and polypropylene as the main raw materials. These materials are generally soluble in organic solvents such as toluene but insoluble in water. In water-based drilling fluids, they form a solid phase to seal micro-fractures and reduce filtration loss. Furthermore, the outer polypropylene layer becomes liquid under formation temperature. The hydrophobicity of polypropylene can adsorb onto the well wall, increasing the bonding performance of the well wall and thus enhancing its strength, stability, and reducing well leakage.

[0075] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

[0076] Table 1

[0077] .

[0078] Table 2

[0079] .

[0080] Table 3

[0081] 。

Claims

1. A modified resin film-forming blocking agent, characterized in that... The raw materials, by weight, comprise 3 to 3.5 parts of modified high-temperature resistant unsaturated polyester resin and 1 to 1.5 parts of polypropylene, and are obtained by the following method: 1 to 1.5 parts of polypropylene are sprayed onto 3 to 3.5 parts of modified high-temperature resistant unsaturated polyester resin at 175°C to 185°C, and after cooling, a modified resin film-forming blocking agent is obtained. The modified high-temperature resistant unsaturated polyester resin is prepared by the following method: S1, add the required amount of maleic anhydride to ethylene glycol for reaction, stir until the viscosity of the reaction product no longer changes, stop the reaction, remove the solvent on the top of the reaction product to obtain the first emulsion, wherein the mass ratio of maleic anhydride to ethylene glycol is 1:4, the reaction temperature is 185℃ to 195℃, and the reaction time is 1h to 2h. S2, add the first crosslinking agent to the obtained first emulsion and react, stirring until the viscosity of the reaction product no longer changes, to obtain a high-temperature resistant unsaturated polyester resin, wherein the first crosslinking agent is a mixture of dimethacrylate and 4-methylstyrene in a molar ratio of 1:2.5 to 3.5, the mass ratio of the first emulsion to the first crosslinking agent is 100:1 to 1.5, the reaction temperature is 185℃ to 195℃, and the reaction time is 1h to 2h; S3. The required amount of nano-silica is added to the high-temperature resistant unsaturated polyester resin and mixed evenly. The mixture is stirred until the viscosity of the reaction product no longer changes. After cooling to room temperature, it is crushed, ground and screened to obtain the modified high-temperature resistant unsaturated polyester resin. The mass ratio of nano-silica to high-temperature resistant unsaturated polyester resin is 1:

1. The reaction temperature is 185℃ to 195℃ and the reaction time is 0.5h to 1h.

2. The modified resin film-forming blocking agent according to claim 1, characterized in that... In step S3, the particle size range of the crushing, grinding and screening is 1 μm to 50 μm.

3. A method for preparing a modified resin film-forming blocking agent, characterized in that... The process is as follows: 1 to 1.5 parts of polypropylene are sprayed onto 3 to 3.5 parts of modified high-temperature resistant unsaturated polyester resin at 175°C to 185°C. After cooling, a modified resin film-forming blocker is obtained. The modified high-temperature resistant unsaturated polyester resin is prepared according to the following method: S1, add the required amount of maleic anhydride to ethylene glycol for reaction, stir until the viscosity of the reaction product no longer changes, stop the reaction, remove the solvent on the top of the reaction product to obtain the first emulsion, wherein the mass ratio of maleic anhydride to ethylene glycol is 1:4, the reaction temperature is 185℃ to 195℃, and the reaction time is 1h to 2h. S2, add the first crosslinking agent to the obtained first emulsion and react, stirring until the viscosity of the reaction product no longer changes, to obtain a high-temperature resistant unsaturated polyester resin, wherein the first crosslinking agent is a mixture of dimethacrylate and 4-methylstyrene in a molar ratio of 1:2.5 to 3.5, the mass ratio of the first emulsion to the first crosslinking agent is 100:1 to 1.5, the reaction temperature is 185℃ to 195℃, and the reaction time is 1h to 2h; S3. The required amount of nano-silica is added to the high-temperature resistant unsaturated polyester resin and mixed evenly. The mixture is stirred until the viscosity of the reaction product no longer changes. After cooling to room temperature, it is crushed, ground and screened to obtain the modified high-temperature resistant unsaturated polyester resin. The mass ratio of nano-silica to high-temperature resistant unsaturated polyester resin is 1:

1. The reaction temperature is 185℃ to 195℃ and the reaction time is 0.5h to 1h.

4. The preparation method of the modified resin film-forming blocking agent according to claim 3, characterized in that... In step S3, the particle size range of the crushing, grinding and screening is 1 μm to 50 μm.