A high-temperature resistant temporary plugging agent for oil fields and its preparation method

Abstract

The invention discloses a high-temperature resistant temporary plugging agent for oil fields and a preparation method thereof. The temporary plugging agent uses acrylamide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid and castor oil as reaction raw materials, cross-links with a modified cross-linking agent, and is blended and polymerized with a modified filler to prepare the high-temperature resistant temporary plugging agent. The molecular structure of the temporary plugging agent is a grid-shaped polyacrylamide. The polyacrylamide molecular chain contains an amide group, a sulfonic acid group and a carboxyl group. The amide group is an uncharged group and is not easily affected by high-mineralization bottom water. The sulfonic acid group can increase the salt resistance of the temporary plugging agent. The carboxyl group can complex with hydrogen ions in water, thereby causing the grid molecules to hydrate and expand. The side chain contains a polysiloxane segment and a long-chain alkyl group, so that the temporary plugging agent can still be used normally in a high-temperature environment. The long-chain alkyl group forms a hydrophobic microdomain and can be adsorbed to the hydrophobic surface of the formation rock, so that the temporary plugging agent remains stable during construction.

Description

Technical Field

[0001] The invention relates to the technical field of temporary plugging agent preparation, and in particular to a high-temperature resistant temporary plugging agent for oil fields and a preparation method thereof. Background Art

[0002] During drilling and completion operations, when foreign fluids enter the reservoir, they can cause a series of adverse consequences, such as solids migration, clay swelling, and pore blockage caused by fluid incompatibility. These can lead to decreased permeability in the near-wellbore zone and reduced oil production. Temporary plugging with temporary plugging agents is a widely used and easy-to-implement technique for protecting oil and gas reservoirs. Temporary plugging agents are materials that temporarily reduce reservoir permeability, effectively preventing the working fluid from entering non-target reservoirs. As reservoir depth increases, formation temperatures rise. When developing deep and ultra-deep oil and gas resources, conventional temporary plugging agents struggle to withstand high temperatures, rendering them ineffective and preventing effective plugging. Summary of the Invention

[0003] The purpose of the present invention is to provide a high-temperature resistant temporary plugging agent for oil fields and a preparation method thereof, so as to solve the problems of poor stability under high temperature conditions, poor effect of plugging pores and cracks, and insufficient gelling strength.

[0004] The purpose of the present invention can be achieved through the following technical solutions:

[0005] A method for preparing a high-temperature resistant temporary plugging agent for oil fields comprises the following steps:

[0006] Step A1: Tetramethylcyclotetrasiloxane, 1-octene, chloroplatinic acid, and DMF were uniformly mixed, nitrogen was introduced, and the reaction was carried out at a speed of 120-150 r / min and a temperature of 70-80° C. for 3-5 hours to obtain a modified monomer;

[0007] Step A2: octamethylcyclotetrasiloxane, a modified monomer, tetramethyldivinyldisiloxane, tetramethylammonium hydroxide, and dimethyl sulfoxide are mixed, nitrogen is introduced, and the mixture is reacted at a speed of 120-150 r / min and a temperature of 90-95° C. for 10-12 hours to obtain a modified crosslinking agent;

[0008] Step A3: Acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, castor oil, and DMF are uniformly mixed, and a modified crosslinker and a modified filler are added at a speed of 150-200 r / min, a temperature of 20-25° C., and a neutral pH. After stirring for 1-1.5 hours, dicumyl peroxide is added, the temperature is raised to 120-125° C., and the reaction is carried out for 2-3 hours to prepare a high-temperature resistant temporary plugging agent for oil fields.

[0009] Furthermore, the molar ratio of tetramethylcyclotetrasiloxane and 1-octene in step A1 is 1:1, and the amount of chloroplatinic acid used is 1‰ of the mass of 1-octene.

[0010] Furthermore, the molar ratio of octamethylcyclotetrasiloxane, modified monomer, tetramethyldivinyldisiloxane, and tetramethylammonium hydroxide described in step A2 is 1.6:0.8:1:2.

[0011] Furthermore, the molar ratio of acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and castor oil described in step A3 is 15:1:4:2, the amount of the modified crosslinker is 4‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and castor oil, the amount of the modified filler is 5‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and castor oil, and the amount of dicumyl peroxide is 3‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and castor oil.

[0012] Furthermore, the modified filler is prepared by the following steps:

[0013] Step B1: Calcium carbonate is dispersed in ethanol, stirred at a speed of 200-300 r / min and a temperature of 60-70° C., and KH550 and deionized water are added for a reaction of 2-3 hours to prepare pretreated calcium carbonate. The pretreated calcium carbonate, 3,4-epoxy-1-butene, and DMF are uniformly mixed, and reacted at a speed of 200-300 r / min, a temperature of 40-50° C., and a pH of 11-12 for 2-3 hours to modify the calcium carbonate;

[0014] Step B2: caprolactone, modified calcium carbonate, stannous octoate and DMF are mixed uniformly, nitrogen protection is introduced, and the reaction is carried out at a speed of 150-200 r / min and a temperature of 120-125°C for 20-25 hours to obtain a precursor; cellulose, 1-butyl-3-methylimidazole chloride and DMF are mixed uniformly, nitrogen protection is introduced, and 2-bromo-2-methylpropionyl bromide is added at a speed of 120-150 r / min and a temperature of 0-3°C. After reacting for 1-2 hours, the temperature is raised to 20-25°C and the reaction is continued for 3-5 hours to obtain pretreated cellulose;

[0015] Step B3: Disperse the pretreated cellulose in DMF, introduce nitrogen protection, stir and add thiourea at a speed of 150-200 r / min and a temperature of 75-80°C, and react for 20-25 hours. Remove the DMF and add sodium hydroxide solution. React at a temperature of 102-105°C for 1-1.5 hours and adjust the pH value to 2-3 to obtain thiolated cellulose. Mix the thiolated cellulose, precursor, benzophenone and ethanol evenly, and react under 365nm ultraviolet light for 5-10 minutes to obtain a modified filler.

[0016] Furthermore, the amount of KH550 used in step B1 is 1% of the mass of calcium carbonate, and the molar ratio of amino groups on the pretreated calcium carbonate to 3,4-epoxy-1-butene is 1:2.

[0017] Furthermore, the mass ratio of caprolactone, modified calcium carbonate and stannous octoate described in step B2 is 100:10:1, and the amount ratio of cellulose, 1-butyl-3-methylimidazole chloride and 2-bromo-2-methylpropionyl bromide is 1g:20g:12mL.

[0018] Furthermore, the amount ratio of the pretreated cellulose, thiourea and sodium hydroxide solution in step B3 is 0.5 g:25 mmol:100 mL, the mass fraction of the sodium hydroxide solution is 1.5%, the mass ratio of the thiolated cellulose and the precursor is 5:1, and the amount of benzophenone is 5‰ of the modified calcium carbonate.

[0019] The beneficial effects of the present invention are as follows: a high-temperature resistant temporary plugging agent for oil fields disclosed by the present invention uses acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and castor oil as reaction raw materials, is cross-linked with a modified cross-linking agent, and is blended and polymerized with a modified filler to prepare the high-temperature resistant temporary plugging agent; the modified cross-linking agent uses tetramethylcyclotetrasiloxane and 1-octene as raw materials to react, so that the Si-H bond on the tetramethylcyclotetrasiloxane reacts with the double bond on the 1-octene to prepare a modified monomer; the modified monomer and octamethylcyclotetrasiloxane are subjected to ring-opening condensation, and then treated with tetramethyldivinyldisiloxane to form double bond end-capping to prepare the modified cross-linking agent.

[0020] The modified filler is prepared by treating calcium carbonate as a raw material with KH550 so that amino groups are grafted onto the surface to obtain pretreated calcium carbonate. The pretreated calcium carbonate is reacted with 3,4-epoxy-1-butene so that amino groups on the surface of the pretreated calcium carbonate react with epoxy groups on 3,4-epoxy-1-butene to form hydroxyl groups to obtain modified calcium carbonate. Caprolactone and modified calcium carbonate are coated with polycaprolactone on the surface of the modified calcium carbonate under the action of stannous octoate to obtain a precursor. Cellulose is treated with 2-bromo-2-methylpropionyl bromide so that the hydroxyl group at the C6 position on the cellulose molecule reacts with the acyl bromide on the 2-bromo-2-methylpropionyl bromide to obtain pretreated cellulose. The pretreated cellulose is treated with thiourea so that the bromine atom sites on the pretreated cellulose are converted into thiol groups to obtain thiolated cellulose. The thiolated cellulose and the precursor are reacted under ultraviolet light so that the thiol groups on the thiolated cellulose are grafted with double bonds on the surface of the precursor to obtain a modified filler.

[0021] The molecular structure of the temporary plugging agent is a grid-like polyacrylamide, and the polyacrylamide molecular chain contains amide groups, sulfonic acid groups and carboxyl groups. The amide groups are uncharged groups and are not easily affected by highly mineralized bottom water. The sulfonic acid groups can increase the salt resistance of the temporary plugging agent. The carboxyl groups can complex with hydrogen ions in water, thereby causing the grid molecules to hydrate and expand. The side chains contain polysiloxane segments and long-chain alkyl groups, so that the temporary plugging agent can still be used normally in high-temperature environments. The long-chain alkyl groups form hydrophobic microregions that can adsorb to the hydrophobic surface of the formation rock. The addition of castor oil increases the hydroxyl content in the molecule, thereby improving the water absorption of the temporary plugging agent, allowing the temporary plugging agent to expand rapidly and block the high-permeability areas in the formation. The cellulose on the surface of the modified filler also absorbs water and expands, which can squeeze the adjacent modified filler, so that the temporary plugging agent remains stable during construction. DETAILED DESCRIPTION

[0022] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0023] Example 1, a method for preparing a high-temperature resistant temporary plugging agent for oil fields, specifically comprising the following steps:

[0024] Step A1: Tetramethylcyclotetrasiloxane, 1-octene, chloroplatinic acid, and DMF were uniformly mixed, nitrogen was introduced, and the mixture was reacted at a speed of 120 r / min and a temperature of 70° C. for 3 h to obtain a modified monomer;

[0025] Step A2: Octamethylcyclotetrasiloxane, a modified monomer, tetramethyldivinyldisiloxane, tetramethylammonium hydroxide, and dimethyl sulfoxide were mixed, nitrogen was introduced, and the mixture was reacted at a speed of 120 r / min and a temperature of 90° C. for 10 hours to obtain a modified crosslinking agent;

[0026] Step A3: Acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, castor oil, and DMF were uniformly mixed. A modified crosslinker and a modified filler were added at a speed of 150 r / min, a temperature of 20° C., and a neutral pH. After stirring for 1 hour, dicumyl peroxide was added, the temperature was raised to 120° C., and the reaction was carried out for 2 hours to prepare a high-temperature resistant temporary plugging agent for oil fields.

[0027] The molar ratio of tetramethylcyclotetrasiloxane and 1-octene in step A1 is 1:1, and the amount of chloroplatinic acid used is 1‰ of the mass of 1-octene.

[0028] The molar ratio of octamethylcyclotetrasiloxane, modified monomer, tetramethyldivinyldisiloxane, and tetramethylammonium hydroxide described in step A2 is 1.6:0.8:1:2.

[0029] The molar ratio of acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and castor oil described in step A3 is 15:1:4:2, the amount of the modified crosslinker is 4‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and castor oil, the amount of the modified filler is 5‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and castor oil, and the amount of dicumyl peroxide is 3‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and castor oil.

[0030] The modified filler is prepared by the following steps:

[0031] Step B1: Calcium carbonate was dispersed in ethanol, stirred at a speed of 200 r / min and a temperature of 60° C., and KH550 and deionized water were added for a reaction of 2 h to prepare pretreated calcium carbonate. The pretreated calcium carbonate, 3,4-epoxy-1-butene, and DMF were uniformly mixed, and reacted at a speed of 200 r / min, a temperature of 40° C., and a pH of 11 for 2 h to modify the calcium carbonate;

[0032] Step B2: Caprolactone, modified calcium carbonate, stannous octoate and DMF were mixed uniformly, nitrogen was introduced for protection, and the reaction was carried out at a speed of 150 r / min and a temperature of 120°C for 20 hours to obtain a precursor. Cellulose, 1-butyl-3-methylimidazole chloride and DMF were mixed uniformly, nitrogen was introduced for protection, and 2-bromo-2-methylpropionyl bromide was added at a speed of 120 r / min and a temperature of 0°C. After reacting for 1 hour, the temperature was raised to 20°C and the reaction was continued for 3 hours to obtain pretreated cellulose;

[0033] Step B3: Disperse the pretreated cellulose in DMF, introduce nitrogen protection, stir and add thiourea at a speed of 150 r / min and a temperature of 75°C, and react for 20 hours. Remove DMF and add sodium hydroxide solution, and react at a temperature of 102°C for 1 hour. Adjust the pH value to 2 to obtain thiolated cellulose. Mix the thiolated cellulose, precursor, benzophenone and ethanol evenly, and react for 5 minutes under 365nm ultraviolet light irradiation to obtain a modified filler.

[0034] The amount of KH550 used in step B1 is 1% of the mass of calcium carbonate, and the molar ratio of amino groups on the pretreated calcium carbonate to 3,4-epoxy-1-butene is 1:2.

[0035] The mass ratio of caprolactone, modified calcium carbonate and stannous octoate described in step B2 is 100:10:1, and the amount ratio of cellulose, 1-butyl-3-methylimidazole chloride and 2-bromo-2-methylpropionyl bromide is 1g:20g:12mL.

[0036] The amount ratio of the pretreated cellulose, thiourea and sodium hydroxide solution in step B3 is 0.5g:25mmol:100mL, the mass fraction of the sodium hydroxide solution is 1.5%, the mass ratio of the thiolated cellulose and the precursor is 5:1, and the amount of benzophenone is 5‰ of the modified calcium carbonate.

[0037] Example 2, a method for preparing a high-temperature resistant temporary plugging agent for oil fields, specifically comprising the following steps:

[0038] Step A1: Tetramethylcyclotetrasiloxane, 1-octene, chloroplatinic acid, and DMF were uniformly mixed, nitrogen was introduced, and the mixture was reacted at a speed of 120 r / min and a temperature of 75° C. for 4 h to obtain a modified monomer;

[0039] Step A2: Octamethylcyclotetrasiloxane, a modified monomer, tetramethyldivinyldisiloxane, tetramethylammonium hydroxide, and dimethyl sulfoxide were mixed, nitrogen was introduced, and the mixture was reacted at a speed of 120 r / min and a temperature of 95° C. for 11 hours to obtain a modified crosslinking agent;

[0040] Step A3: Acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, castor oil, and DMF were uniformly mixed. A modified crosslinker and a modified filler were added at a speed of 150 r / min, a temperature of 25° C., and a neutral pH. After stirring for 1.3 hours, dicumyl peroxide was added, the temperature was raised to 125° C., and the reaction was carried out for 2 hours to prepare a high-temperature resistant temporary plugging agent for oil fields.

[0041] The molar ratio of tetramethylcyclotetrasiloxane and 1-octene in step A1 is 1:1, and the amount of chloroplatinic acid used is 1‰ of the mass of 1-octene.

[0042] The molar ratio of octamethylcyclotetrasiloxane, modified monomer, tetramethyldivinyldisiloxane, and tetramethylammonium hydroxide described in step A2 is 1.6:0.8:1:2.

[0043] The molar ratio of acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and castor oil described in step A3 is 15:1:4:2, the amount of the modified crosslinker is 4‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and castor oil, the amount of the modified filler is 5‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and castor oil, and the amount of dicumyl peroxide is 3‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and castor oil.

[0044] The modified filler is prepared by the following steps:

[0045] Step B1: Calcium carbonate was dispersed in ethanol, stirred at a speed of 300 r / min and a temperature of 65° C., and KH550 and deionized water were added for a reaction of 2 h to prepare pretreated calcium carbonate. The pretreated calcium carbonate, 3,4-epoxy-1-butene, and DMF were uniformly mixed and reacted at a speed of 300 r / min, a temperature of 45° C., and a pH of 11 for 3 h to modify the calcium carbonate;

[0046] Step B2: caprolactone, modified calcium carbonate, stannous octoate and DMF were mixed uniformly, nitrogen was introduced for protection, and the reaction was carried out at a speed of 150 r / min and a temperature of 125°C for 20 hours to obtain a precursor; cellulose, 1-butyl-3-methylimidazole chloride and DMF were mixed uniformly, nitrogen was introduced for protection, and 2-bromo-2-methylpropionyl bromide was added at a speed of 150 r / min and a temperature of 0°C. After reacting for 2 hours, the temperature was raised to 20°C and the reaction was continued for 4 hours to obtain pretreated cellulose;

[0047] Step B3: Disperse the pretreated cellulose in DMF, introduce nitrogen protection, stir and add thiourea at a speed of 150 r / min and a temperature of 80°C, and react for 20 hours. Remove DMF and add sodium hydroxide solution, and react at a temperature of 103°C for 1.5 hours. Adjust the pH value to 2 to obtain thiolated cellulose. Mix the thiolated cellulose, precursor, benzophenone and ethanol evenly, and react for 8 minutes under 365nm ultraviolet light irradiation to obtain a modified filler.

[0048] The amount of KH550 used in step B1 is 1% of the mass of calcium carbonate, and the molar ratio of amino groups on the pretreated calcium carbonate to 3,4-epoxy-1-butene is 1:2.

[0049] The mass ratio of caprolactone, modified calcium carbonate and stannous octoate described in step B2 is 100:10:1, and the amount ratio of cellulose, 1-butyl-3-methylimidazole chloride and 2-bromo-2-methylpropionyl bromide is 1g:20g:12mL.

[0050] The amount ratio of the pretreated cellulose, thiourea and sodium hydroxide solution in step B3 is 0.5g:25mmol:100mL, the mass fraction of the sodium hydroxide solution is 1.5%, the mass ratio of the thiolated cellulose and the precursor is 5:1, and the amount of benzophenone is 5‰ of the modified calcium carbonate.

[0051] Example 3, a method for preparing a high-temperature resistant temporary plugging agent for oil fields, specifically comprising the following steps:

[0052] Step A1: Tetramethylcyclotetrasiloxane, 1-octene, chloroplatinic acid, and DMF were uniformly mixed, nitrogen was introduced, and the mixture was reacted at a speed of 150 r / min and a temperature of 80° C. for 5 h to obtain a modified monomer;

[0053] Step A2: Octamethylcyclotetrasiloxane, a modified monomer, tetramethyldivinyldisiloxane, tetramethylammonium hydroxide, and dimethyl sulfoxide were mixed, nitrogen was introduced, and the mixture was reacted at a speed of 150 r / min and a temperature of 95° C. for 12 hours to obtain a modified crosslinking agent;

[0054] Step A3: Acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, castor oil, and DMF were uniformly mixed. A modified crosslinker and a modified filler were added at a speed of 200 r / min, a temperature of 25° C., and a neutral pH. After stirring for 1.5 hours, dicumyl peroxide was added, the temperature was raised to 125° C., and the reaction was carried out for 3 hours to prepare a high-temperature resistant temporary plugging agent for oil fields.

[0055] The molar ratio of tetramethylcyclotetrasiloxane and 1-octene in step A1 is 1:1, and the amount of chloroplatinic acid used is 1‰ of the mass of 1-octene.

[0056] The molar ratio of octamethylcyclotetrasiloxane, modified monomer, tetramethyldivinyldisiloxane, and tetramethylammonium hydroxide described in step A2 is 1.6:0.8:1:2.

[0057] The molar ratio of acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and castor oil described in step A3 is 15:1:4:2, the amount of the modified crosslinker is 4‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and castor oil, the amount of the modified filler is 5‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and castor oil, and the amount of dicumyl peroxide is 3‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and castor oil.

[0058] The modified filler is prepared by the following steps:

[0059] Step B1: Calcium carbonate was dispersed in ethanol, stirred at a speed of 300 r / min and a temperature of 70°C, and KH550 and deionized water were added for a reaction of 3 hours to prepare pretreated calcium carbonate. The pretreated calcium carbonate, 3,4-epoxy-1-butene, and DMF were uniformly mixed and reacted at a speed of 300 r / min, a temperature of 50°C, and a pH of 12 for 3 hours to modify the calcium carbonate;

[0060] Step B2: caprolactone, modified calcium carbonate, stannous octoate and DMF were mixed uniformly, nitrogen was introduced for protection, and the reaction was carried out at a speed of 200 r / min and a temperature of 125°C for 25 hours to obtain a precursor; cellulose, 1-butyl-3-methylimidazole chloride and DMF were mixed uniformly, nitrogen was introduced for protection, and 2-bromo-2-methylpropionyl bromide was added at a speed of 150 r / min and a temperature of 3°C. After reacting for 2 hours, the temperature was raised to 25°C and the reaction was continued for 5 hours to obtain pretreated cellulose;

[0061] Step B3: Disperse the pretreated cellulose in DMF, introduce nitrogen protection, stir and add thiourea at a speed of 200 r / min and a temperature of 80°C, and react for 25 hours. Remove DMF and add sodium hydroxide solution, and react at a temperature of 105°C for 1.5 hours. Adjust the pH value to 3 to obtain thiolated cellulose. Mix the thiolated cellulose, precursor, benzophenone and ethanol evenly, and react for 10 minutes under 365nm ultraviolet light irradiation to obtain a modified filler.

[0062] The amount of KH550 used in step B1 is 1% of the mass of calcium carbonate, and the molar ratio of amino groups on the pretreated calcium carbonate to 3,4-epoxy-1-butene is 1:2.

[0063] The mass ratio of caprolactone, modified calcium carbonate and stannous octoate described in step B2 is 100:10:1, and the amount ratio of cellulose, 1-butyl-3-methylimidazole chloride and 2-bromo-2-methylpropionyl bromide is 1g:20g:12mL.

[0064] The amount ratio of the pretreated cellulose, thiourea and sodium hydroxide solution in step B3 is 0.5g:25mmol:100mL, the mass fraction of the sodium hydroxide solution is 1.5%, the mass ratio of the thiolated cellulose and the precursor is 5:1, and the amount of benzophenone is 5‰ of the modified calcium carbonate.

[0065] Comparative Example 1: Compared with Example 1, castor oil was not added in this comparative example, and the remaining steps were the same.

[0066] Comparative Example 2: Compared with Example 1, this comparative example uses N,N-methylenebisacrylamide instead of the modified cross-linking agent.

[0067] Comparative Example 3: Compared with Example 1, this comparative example does not add thiolated cellulose, and the remaining steps are the same.

[0068] The temporary plugging agents prepared in Examples 1-3 and Comparative Examples 1-3 were fully absorbed with distilled water and then added to a bentonite-based slurry (4% by mass bentonite, 0.3% by mass sodium carbonate, and the balance water). The amount of the temporary plugging agent added was 3%. A sand bed plugging test was conducted at a pressure of 1 MPa to test the plugging ability of the temporary plugging agent on a 40-mesh sand bed at temperatures of 25°C, 80°C, and 180°C. The test results, as reflected by the penetration depth, are shown in Table 1 below.

[0069] Table 1

[0070]

[0071] It can be seen from Table 1 that the present application has a good plugging effect and can still remain stable under high temperature conditions.

[0072] The above contents are merely examples and explanations of the concept of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a high-temperature resistant temporary plugging agent for oil fields, characterized by: The specific steps include: Step A1: Tetramethylcyclotetrasiloxane, 1-octene, chloroplatinic acid and DMF are uniformly mixed, and nitrogen is introduced to react to obtain a modified monomer; Step A2: octamethylcyclotetrasiloxane, a modified monomer, tetramethyldivinyldisiloxane, tetramethylammonium hydroxide, and dimethyl sulfoxide are mixed, and nitrogen is introduced to react to obtain a modified crosslinking agent; Step A3: uniformly mixing acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, castor oil, and DMF, stirring, and adding a modified crosslinking agent and a modified filler. After stirring, dicumyl peroxide is added, and the temperature is raised to react to prepare a high-temperature resistant temporary plugging agent for oil fields; The modified filler is prepared by the following steps: Step B1: Calcium carbonate is dispersed in ethanol, stirred, and KH550 and deionized water are added for a reaction of 2-3 hours to prepare pretreated calcium carbonate, and the pretreated calcium carbonate, 3,4-epoxy-1-butene, and DMF are mixed and reacted to modify the calcium carbonate; Step B2: Caprolactone, modified calcium carbonate, stannous octoate, and DMF are uniformly mixed, and nitrogen is introduced to react to obtain a precursor. Cellulose, 1-butyl-3-methylimidazole chloride, and DMF are uniformly mixed, and nitrogen is introduced to protect the mixture. 2-bromo-2-methylpropionyl bromide is added with stirring and reacted to obtain pretreated cellulose. Step B3: Disperse the pretreated cellulose in DMF, introduce nitrogen protection, stir and add thiourea to react, remove DMF and add sodium hydroxide solution to react, adjust the pH to acidic to obtain thiolated cellulose, and mix the thiolated cellulose, precursor, benzophenone and ethanol to react to obtain a modified filler.

2. The method for preparing a high-temperature resistant temporary plugging agent for oil fields according to claim 1, characterized in that: The molar ratio of tetramethylcyclotetrasiloxane and 1-octene in step A1 is 1:

1.

3. The method for preparing a high-temperature resistant temporary plugging agent for oil fields according to claim 1, characterized in that: The molar ratio of octamethylcyclotetrasiloxane, modified monomer, tetramethyldivinyldisiloxane, and tetramethylammonium hydroxide described in step A2 is 1.6:0.8:1:

2.

4. The method for preparing a high-temperature resistant temporary plugging agent for oil fields according to claim 1, characterized in that: The molar ratio of acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and castor oil described in step A3 is 15:1:4:2, the amount of the modified crosslinker is 4‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and castor oil, and the amount of the modified filler is 5‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and castor oil.

5. The method for preparing a high-temperature resistant temporary plugging agent for oil fields according to claim 1, characterized in that: The amount of KH550 used in step B1 is 1% of the mass of calcium carbonate, and the molar ratio of amino groups on the pretreated calcium carbonate to 3,4-epoxy-1-butene is 1:

2.

6. The method for preparing a high-temperature resistant temporary plugging agent for oil fields according to claim 1, characterized in that: The mass ratio of caprolactone, modified calcium carbonate and stannous octoate described in step B2 is 100:10:1, and the amount ratio of cellulose, 1-butyl-3-methylimidazole chloride and 2-bromo-2-methylpropionyl bromide is 1g:20g:12mL.

7. The method for preparing a high-temperature resistant temporary plugging agent for oil fields according to claim 1, characterized in that: The amount ratio of the pretreated cellulose, thiourea and sodium hydroxide solution in step B3 is 0.5 g:25 mmol:100 mL, and the mass ratio of the thiolated cellulose to the precursor is 5:

1.

8. A high-temperature resistant temporary plugging agent for oil fields, characterized by: Prepared according to any one of claims 1 to 7.

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