High-temperature-resistant temporary plugging agent for oil field and preparation method thereof

Abstract

The invention discloses a high-temperature-resistant temporary plugging agent for an oil field and a preparation method thereof.The temporary plugging agent is prepared by taking acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and castor oil as reaction raw materials, cross-linking the reaction raw materials with a modified cross-linking agent and carrying out blending polymerization with a modified filler, the molecular structure of the temporary plugging agent is latticed polyacrylamide, a polyacrylamide molecular chain contains an amide group, a sulfonic acid group and carboxyl, the amide group is an uncharged group and is not easily influenced by high-salinity bottom water, the sulfonic acid group can improve the salt resistance of the temporary plugging agent, and the carboxyl can be complexed with hydrogen ions in water, so that the salt resistance of the temporary plugging agent is improved. A side chain contains a polysiloxane chain segment and a long-chain alkyl group, so that the temporary plugging agent can still be normally used in a high-temperature environment, and the long-chain alkyl group forms a hydrophobic micro-area and can be adsorbed with a hydrophobic surface of stratum rock, so that the temporary plugging agent is kept in a stable state in a construction process.

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, a series of adverse consequences will occur, such as solid phase migration, clay expansion, and fluid incompatibility resulting in precipitation blocking pores, which will lead to a decrease in the permeability of the reservoir near the wellbore and a decrease in the oil layer production capacity. Temporary plugging with temporary plugging agents is an easy-to-implement technology for protecting oil and gas layers and has been widely used. Temporary plugging agents are materials that can temporarily reduce the permeability of reservoirs and can effectively inhibit the working fluid from entering non-target reservoirs. As the depth of the reservoir increases, the formation temperature also increases. When developing deep and ultra-deep oil and gas resources, it is difficult for conventional temporary plugging agents to have a high temperature resistance effect at the same time, which makes the temporary plugging agents ineffective and results in the failure to achieve the plugging effect. 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 by the following technical solutions: A method for preparing a high temperature resistant temporary plugging agent for oil fields, comprising the following steps: Step A1: Tetramethylcyclotetrasiloxane, 1-octene, chloroplatinic acid and DMF are uniformly mixed, nitrogen is introduced for protection, and the reaction is carried out for 3-5 hours at a speed of 120-150 r / min and a temperature of 70-80° C. to obtain a modified monomer; Step A2: octamethylcyclotetrasiloxane, a modified monomer, tetramethyldivinyldisiloxane, tetramethylammonium hydroxide and dimethyl sulfoxide are mixed, nitrogen is introduced for protection, and the reaction is carried out for 10-12 hours at a speed of 120-150 r / min and a temperature of 90-95° C. to obtain a modified crosslinking agent; Step A3: uniformly mix acrylamide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid, castor oil and DMF, add modified crosslinking agent and modified filler at a speed of 150-200 r / min, a temperature of 20-25° C. and a neutral pH, stir for 1-1.5 hours, add diisopropylbenzene peroxide, heat to 120-125° C., react for 2-3 hours, and obtain a high temperature resistant temporary plugging agent for oil fields.

[0005] 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.

[0006] Furthermore, the molar ratio of octamethylcyclotetrasiloxane, modified monomer, tetramethyldivinyldisiloxane and tetramethylammonium hydroxide described in step A2 is 1.6:0.8:1:2.

[0007] Further, the molar ratio of acrylamide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic 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-methylpropane sulfonic acid and castor oil, the amount of the modified filler is 5‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid and castor oil, and the amount of dicumyl peroxide is 3‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid and castor oil.

[0008] Further, the modified filler is prepared by the following steps: Step B1: Calcium carbonate is dispersed in ethanol, and KH550 and deionized water are added under stirring at a speed of 200-300 r / min and a temperature of 60-70° C. to react for 2-3 hours to obtain pretreated calcium carbonate, and the pretreated calcium carbonate, 3,4-epoxy-1-butene and DMF are mixed uniformly, and reacted for 2-3 hours under the conditions of a speed of 200-300 r / min, a temperature of 40-50° C. and a pH value of 11-12 to modify the calcium carbonate; Step B2: uniformly mix caprolactone, modified calcium carbonate, stannous octoate and DMF, introduce nitrogen protection, react for 20-25 hours at a speed of 150-200 r / min and a temperature of 120-125° C. to obtain a precursor, uniformly mix cellulose, 1-butyl-3-methylimidazole chloride and DMF, introduce nitrogen protection, stir and add 2-bromo-2-methylpropionyl bromide at a speed of 120-150 r / min and a temperature of 0-3° C., react for 1-2 hours, then heat to 20-25° C. and continue to react for 3-5 hours to obtain pretreated cellulose; 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., react for 20-25 hours, remove DMF and add sodium hydroxide solution, react for 1-1.5 hours at a temperature of 102-105° C., adjust the pH value to 2-3, and obtain thiolated cellulose. Evenly mix the thiolated cellulose, precursor, benzophenone and ethanol, and react for 5-10 minutes under 365 nm ultraviolet light irradiation to obtain a modified filler.

[0009] 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.

[0010] Furthermore, the mass ratio of the 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.

[0011] 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.

[0012] The beneficial effects of the invention are as follows: the high-temperature resistant temporary plugging agent for oil fields disclosed by the invention uses acrylamide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid and castor oil as reaction raw materials, is cross-linked by a modified cross-linking agent, and is blended and polymerized with a modified filler to obtain the high-temperature resistant temporary plugging agent; the modified cross-linking agent uses tetramethylcyclotetrasiloxane and 1-octene as raw materials for reaction, so that the Si-H bond on the tetramethylcyclotetrasiloxane reacts with the double bond on the 1-octene to obtain 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 obtain the modified cross-linking agent.

[0013] The modified filler is prepared by treating calcium carbonate as a raw material with KH550 so that amino groups are grafted on 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 site on the pretreated cellulose is converted into a thiol group to obtain thiolated cellulose. The thiolated cellulose and the precursor are reacted under ultraviolet light so that the thiol group on the thiolated cellulose is grafted with the double bond on the surface of the precursor to obtain a modified filler.

[0014] 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 high-mineralization 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 the water, thereby causing the grid molecules to hydrate and swell. The side chains contain polysiloxane segments and long-chain alkyl groups, so that the temporary plugging agent can still be used normally in a high-temperature environment. The long-chain alkyl groups form hydrophobic microregions and 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, so that the temporary plugging agent can quickly expand and block the high-permeability areas in the formation. The cellulose on the surface of the modified filler also absorbs water and swells, which can squeeze the adjacent modified filler, so that the temporary plugging agent remains stable during the construction process. DETAILED DESCRIPTION

[0015] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] Embodiment 1, a method for preparing a high temperature resistant temporary plugging agent for oil fields, specifically comprising the following steps: Step A1: Tetramethylcyclotetrasiloxane, 1-octene, chloroplatinic acid and DMF were uniformly mixed, nitrogen was introduced for protection, and the reaction was carried out at a speed of 120 r / min and a temperature of 70° C. for 3 h to obtain a modified monomer; Step A2: octamethylcyclotetrasiloxane, a modified monomer, tetramethyldivinyldisiloxane, tetramethylammonium hydroxide and dimethyl sulfoxide are mixed, nitrogen is introduced for protection, and the reaction is carried out for 10 hours at a speed of 120 r / min and a temperature of 90° C. to obtain a modified crosslinking agent; Step A3: uniformly mix acrylamide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid, castor oil and DMF, add modified crosslinking agent and modified filler at a speed of 150 r / min, a temperature of 20° C. and a neutral pH, stir for 1 hour, add diisopropylbenzene peroxide, raise the temperature to 120° C., react for 2 hours, and obtain a high temperature resistant temporary plugging agent for oil fields.

[0017] 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.

[0018] The molar ratio of octamethylcyclotetrasiloxane, modified monomer, tetramethyldivinyldisiloxane and tetramethylammonium hydroxide described in step A2 is 1.6:0.8:1:2.

[0019] The molar ratio of acrylamide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid and castor oil described in step A3 is 15:1:4:2, the amount of the modified cross-linking agent is 4‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid and castor oil, the amount of the modified filler is 5‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid and castor oil, and the amount of diisopropylbenzene peroxide is 3‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid and castor oil.

[0020] The modified filler is prepared by the following steps: Step B1: Calcium carbonate is dispersed in ethanol, and KH550 and deionized water are added under stirring at a speed of 200 r / min and a temperature of 60° C. to react for 2 h to obtain pretreated calcium carbonate. The pretreated calcium carbonate, 3,4-epoxy-1-butene and DMF are mixed uniformly, and reacted for 2 h under the conditions of a speed of 200 r / min, a temperature of 40° C. and a pH value of 11 to modify the calcium carbonate; Step B2: uniformly mix caprolactone, modified calcium carbonate, stannous octoate and DMF, introduce nitrogen protection, react for 20 hours at a speed of 150 r / min and a temperature of 120° C. to obtain a precursor, uniformly mix cellulose, 1-butyl-3-methylimidazole chloride and DMF, introduce nitrogen protection, stir and add 2-bromo-2-methylpropionyl bromide at a speed of 120 r / min and a temperature of 0° C., react for 1 hour, then heat to 20° C. and continue to react for 3 hours to obtain pretreated cellulose; 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 for 1 hour at a temperature of 102°C. Adjust the pH value to 2 to obtain thiolated cellulose. Evenly mix the thiolated cellulose, precursor, benzophenone and ethanol, and react for 5 minutes under 365nm ultraviolet light irradiation to obtain a modified filler.

[0021] The amount of KH550 used in step B1 is 1% of the mass of calcium carbonate, and the molar ratio of the amino group on the pretreated calcium carbonate to 3,4-epoxy-1-butene is 1:2.

[0022] 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.

[0023] 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.

[0024] Embodiment 2, a method for preparing a high temperature resistant temporary plugging agent for oil fields, specifically comprising the following steps: Step A1: Tetramethylcyclotetrasiloxane, 1-octene, chloroplatinic acid and DMF were uniformly mixed, nitrogen was introduced for protection, and the reaction was carried out at a speed of 120 r / min and a temperature of 75° C. for 4 hours to obtain a modified monomer; Step A2: octamethylcyclotetrasiloxane, a modified monomer, tetramethyldivinyldisiloxane, tetramethylammonium hydroxide and dimethyl sulfoxide are mixed, nitrogen is introduced for protection, and the reaction is carried out for 11 hours at a speed of 120 r / min and a temperature of 95° C. to obtain a modified crosslinking agent; Step A3: acrylamide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid, castor oil and DMF are mixed uniformly, and a modified cross-linking agent and a modified filler are added at a rotation speed of 150 r / min, a temperature of 25° C. and a neutral pH. After stirring for 1.3 hours, diisopropylbenzene peroxide is added, the temperature is raised to 125° C., and the reaction is carried out for 2 hours to obtain a high-temperature resistant temporary plugging agent for oil fields.

[0025] 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.

[0026] The molar ratio of octamethylcyclotetrasiloxane, modified monomer, tetramethyldivinyldisiloxane and tetramethylammonium hydroxide described in step A2 is 1.6:0.8:1:2.

[0027] The molar ratio of acrylamide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid and castor oil described in step A3 is 15:1:4:2, the amount of the modified cross-linking agent is 4‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid and castor oil, the amount of the modified filler is 5‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid and castor oil, and the amount of diisopropylbenzene peroxide is 3‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid and castor oil.

[0028] The modified filler is prepared by the following steps: Step B1: Calcium carbonate is dispersed in ethanol, and KH550 and deionized water are added under stirring at a speed of 300 r / min and a temperature of 65° C. to react for 2 h to obtain pretreated calcium carbonate. The pretreated calcium carbonate, 3,4-epoxy-1-butene and DMF are mixed evenly, and reacted for 3 h under the conditions of a speed of 300 r / min, a temperature of 45° C. and a pH value of 11 to modify the calcium carbonate; Step B2: uniformly mix caprolactone, modified calcium carbonate, stannous octoate and DMF, introduce nitrogen protection, react for 20 hours at a speed of 150 r / min and a temperature of 125° C. to obtain a precursor, uniformly mix cellulose, 1-butyl-3-methylimidazole chloride and DMF, introduce nitrogen protection, stir and add 2-bromo-2-methylpropionyl bromide at a speed of 150 r / min and a temperature of 0° C., react for 2 hours, then heat to 20° C. and continue to react for 4 hours to obtain pretreated cellulose; Step B3: Disperse the pretreated cellulose in DMF, introduce nitrogen protection, stir and add thiourea at a speed of 150r / min and a temperature of 80°C, and react for 20 hours. Remove DMF and add sodium hydroxide solution. React for 1.5 hours at a temperature of 103°C. Adjust the pH value to 2 to obtain thiolated cellulose. Evenly mix the thiolated cellulose, precursor, benzophenone and ethanol, and react for 8 minutes under 365nm ultraviolet light irradiation to obtain a modified filler.

[0029] The amount of KH550 used in step B1 is 1% of the mass of calcium carbonate, and the molar ratio of the amino group on the pretreated calcium carbonate to 3,4-epoxy-1-butene is 1:2.

[0030] 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.

[0031] 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.

[0032] Embodiment 3, a method for preparing a high temperature resistant temporary plugging agent for oil fields, specifically comprising the following steps: Step A1: Tetramethylcyclotetrasiloxane, 1-octene, chloroplatinic acid and DMF were uniformly mixed, nitrogen was introduced for protection, and the reaction was carried out at a speed of 150 r / min and a temperature of 80° C. for 5 h to obtain a modified monomer; Step A2: octamethylcyclotetrasiloxane, a modified monomer, tetramethyldivinyldisiloxane, tetramethylammonium hydroxide and dimethyl sulfoxide are mixed, nitrogen is introduced for protection, and the reaction is carried out for 12 hours at a speed of 150 r / min and a temperature of 95° C. to obtain a modified crosslinking agent; Step A3: acrylamide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid, castor oil and DMF are uniformly mixed, and a modified cross-linking agent and a modified filler are added at a rotation speed of 200 r / min, a temperature of 25° C. and a neutral pH. After stirring for 1.5 hours, diisopropylbenzene peroxide is added, the temperature is raised to 125° C., and the reaction is carried out for 3 hours to obtain a high-temperature resistant temporary plugging agent for oil fields.

[0033] 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.

[0034] The molar ratio of octamethylcyclotetrasiloxane, modified monomer, tetramethyldivinyldisiloxane and tetramethylammonium hydroxide described in step A2 is 1.6:0.8:1:2.

[0035] The molar ratio of acrylamide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid and castor oil described in step A3 is 15:1:4:2, the amount of the modified cross-linking agent is 4‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid and castor oil, the amount of the modified filler is 5‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid and castor oil, and the amount of diisopropylbenzene peroxide is 3‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid and castor oil.

[0036] The modified filler is prepared by the following steps: Step B1: Calcium carbonate is dispersed in ethanol, and KH550 and deionized water are added under stirring at a speed of 300 r / min and a temperature of 70° C. to react for 3 h to obtain pretreated calcium carbonate, and the pretreated calcium carbonate, 3,4-epoxy-1-butene and DMF are mixed uniformly, and reacted for 3 h under the conditions of a speed of 300 r / min, a temperature of 50° C. and a pH value of 12 to modify the calcium carbonate; Step B2: caprolactone, modified calcium carbonate, stannous octoate and DMF are mixed evenly, nitrogen is introduced for protection, and the reaction is carried out for 25 hours at a speed of 200 r / min and a temperature of 125° C. to obtain a precursor; cellulose, 1-butyl-3-methylimidazole chloride and DMF are mixed evenly, nitrogen is introduced for protection, and 2-bromo-2-methylpropionyl bromide is added at a speed of 150 r / min and a temperature of 3° C. to react for 2 hours, then the temperature is raised to 25° C. and the reaction is continued for 5 hours to obtain pretreated cellulose; 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. React for 1.5 hours at a temperature of 105°C. Adjust the pH value to 3 to obtain thiolated cellulose. Evenly mix the thiolated cellulose, precursor, benzophenone and ethanol, and react for 10 minutes under 365nm ultraviolet light irradiation to obtain a modified filler.

[0037] The amount of KH550 used in step B1 is 1% of the mass of calcium carbonate, and the molar ratio of the amino group on the pretreated calcium carbonate to 3,4-epoxy-1-butene is 1:2.

[0038] 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.

[0039] 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.

[0040] Comparative Example 1: Compared with Example 1, castor oil was not added in this comparative example, and the remaining steps were the same.

[0041] Comparative Example 2: Compared with Example 1, this comparative example uses N,N-methylenebisacrylamide instead of the modified cross-linking agent.

[0042] Comparative Example 3: Compared with Example 1, no thiolated cellulose was added in this comparative example, and the remaining steps were the same.

[0043] The temporary plugging agents prepared in Examples 1-3 and Comparative Examples 1-3 fully absorbed distilled water and were added to bentonite-based slurry (4% by mass bentonite, 0.3% by mass sodium carbonate, and the balance being water). The amount of the temporary plugging agent added was 3%. Under a pressure of 1 MPa, a sand bed plugging experiment was carried out to detect 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 were shown in Table 1 below through the intrusion depth reaction.

[0044] Table 1

[0045] 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.

[0046] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described 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 protection scope of the present invention.

Claims

1. A method for preparing a high temperature resistant temporary plugging agent for oil fields, characterized in that: The specific steps include: Step A1: Tetramethylcyclotetrasiloxane, 1-octene, chloroplatinic acid and DMF are uniformly mixed, nitrogen is introduced for protection, and a reaction is carried out to obtain a modified monomer; Step A2: octamethylcyclotetrasiloxane, a modified monomer, tetramethyldivinyldisiloxane, tetramethylammonium hydroxide and dimethyl sulfoxide are mixed, nitrogen is introduced for protection, and a reaction is carried out to prepare a modified crosslinking agent; Step A3: uniformly mix acrylamide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid, castor oil and DMF, stir and add a modified crosslinking agent and a modified filler, stir and add diisopropylbenzene peroxide, heat and react to obtain a high temperature resistant temporary plugging agent for oil fields.

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 to 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-methylpropane sulfonic acid and castor oil described in step A3 is 15:1:4:2, the amount of the modified crosslinking agent is 4‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid and castor oil, and the amount of the modified filler is 5‰ of the total mass of acrylamide, acrylic acid, 2-acrylamide-2-methylpropane sulfonic 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 modified filler is prepared by the following steps: Step B1: Disperse calcium carbonate in ethanol, stir and add KH550 and deionized water, react for 2-3 hours to obtain pretreated calcium carbonate, and mix the pretreated calcium carbonate, 3,4-epoxy-1-butene and DMF to react to modify the calcium carbonate; Step B2: uniformly mixing caprolactone, modified calcium carbonate, stannous octoate and DMF, passing nitrogen gas for protection, and reacting to obtain a precursor; uniformly mixing cellulose, 1-butyl-3-methylimidazole chloride and DMF, passing nitrogen gas for protection, stirring and adding 2-bromo-2-methylpropionyl bromide, and reacting 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, mix the thiolated cellulose, precursor, benzophenone and ethanol to react, and obtain a modified filler.

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

2.

7. The method for preparing a high temperature resistant temporary plugging agent for oil fields according to claim 5, 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.

8. The method for preparing a high temperature resistant temporary plugging agent for oil fields according to claim 5, 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.

9. A high temperature resistant temporary plugging agent for oil fields, characterized in that: Prepared according to any one of the preparation methods described in claims 1-8.

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