A delayed cross-linking water shutoff and profile control agent for oil production and a preparation method thereof

Abstract

The present application relates to the technical field of water plugging and profile control agents, and particularly relates to a delayed cross-linking water plugging and profile control agent for oil production and a preparation method thereof, which comprises the following raw materials in parts by weight: 25-30 parts of modified polyacrylamide, 12-15 parts of a composite cross-linking agent, 8-10 parts of a stabilizer, and 2-3 parts of an oxygen scavenger; by taking sodium-based montmorillonite as a carrier, loading zirconium phytate organic cross-linking agent, and introducing a Schiff base structure, the composite cross-linking agent has good slow-release delayed cross-linking performance through the slow-release effect of nanomaterials, and the problem of premature cross-linking of the existing water plugging and profile control agent, which leads to a decline in plugging effect, is solved, and the plugging performance of the water plugging and profile control agent is further enhanced by synthesizing modified polyacrylamide with a telechelic structure.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of water plugging and profile control agents, in particular to a delayed crosslinking water plugging and profile control agent for oil production and a preparation method thereof. BACKGROUND

[0002] In the process of oil reservoir exploitation, the existence of cracks aggravates the heterogeneity of the reservoir in the horizontal and vertical directions, also causes the displacement medium to rapidly channel along the cracks, reduces the sweep efficiency, and thus affects the oilfield recovery efficiency, so it is necessary to carry out water plugging and profile control, and the most widely used profile control agent system is a polymer crosslinking system, however, due to the too fast crosslinking reaction rate of the traditional profile control agent, for example, a profile control water plugging agent and a preparation method and application thereof disclosed in patent CN116589637A, the profile control water plugging agent has a unique double-network structure of hydrogel material, has good stability, and still maintains good strength under high-temperature and high-salt conditions, but the profile control water plugging agent cannot reach the deep layer of the heterogeneous oil reservoir, that is, the crack-pore composite formation, crosslinking gelation occurs, near-well blockage risk occurs, the profile control water plugging agent cannot migrate to the deep part of the formation, the plugging effect is affected, and the market demand cannot be met. SUMMARY

[0003] The application aims to provide a delayed crosslinking water plugging and profile control agent for oil production and a preparation method thereof, sodium-based montmorillonite is used as a carrier, zirconium phytate organic crosslinking agent is loaded, and a Schiff base structure is introduced, the nano material slow-release effect is used, the composite crosslinking agent has good slow-release and delayed crosslinking performance, the problem that the existing water plugging and profile control agent is crosslinked in advance and the plugging effect is reduced is solved, and the modified polyacrylamide with a telechelic structure is synthesized, and the plugging performance of the water plugging and profile control agent is further improved.

[0004] The application can be achieved by the following technical scheme: a preparation method of a delayed crosslinking water plugging and profile control agent for oil production, which comprises the following steps: weighing the following raw materials: 25-30 parts of modified polyacrylamide, 12-15 parts of a composite crosslinking agent, 8-10 parts of a stabilizing agent and 2-3 parts of an oxygen scavenger, and mixing the modified polyacrylamide, the composite crosslinking agent, the stabilizing agent and the oxygen scavenger to prepare a delayed crosslinking water plugging and profile control agent for oil production.

[0005] The oxygen scavenger is Gaber XH21 oxygen scavenger.

[0006] The stabilizing agent is Lingchuang NW-1 stabilizing agent.

[0007] The modified polyacrylamide is prepared by the following steps:

[0008] Step Al: Hydroquinone and dichloromethane were mixed, stirred at a stirring rate of 180-240 rpm and a temperature of 0-5 °C under argon protection, 2-bromoisobutyryl bromide was added, stirred for 30 min, warmed to room temperature, reacted for 10-12 h, triethylamine was added, stirred for 10-15 min, deionized water was added, the dichloromethane phase was collected by extraction, dried over anhydrous magnesium sulfate, filtered, rotary evaporated, and dried to obtain a double-headed initiator; the double-headed initiator, sodium ascorbate, acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, N,N-dimethylformamide, and deionized water were mixed, stirred at a stirring rate of 180-240 rpm and a temperature of 35-40 °C under nitrogen protection, cuprous bromide was added, reacted for 24 h, rotary evaporated, recrystallized, filtered, and dried to obtain a macroinitiator;

[0009] The amount ratio of hydroquinone, dichloromethane, 2-bromoisobutyryl bromide, triethylamine, and deionized water was 2-2.1 g: 45-50 mL: 5.8-5.9 mL: 0.8-1 mL: 45-50 mL; the amount ratio of the double-headed initiator, sodium ascorbate, acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, N,N-dimethylformamide, deionized water, and cuprous bromide was 0.24-0.25 g: 0.01 g: 3.5-3.6 g: 2-2.1 g: 10-15 mL: 20-25 mL: 0.01-0.02 g;

[0010] During the reaction, the hydroxyl group in hydroquinone first reacted with the acyl bromide group in 2-bromoisobutyryl bromide to obtain a double-headed initiator, and then the double-headed initiator was used as an initiator, sodium ascorbate and cuprous bromide were used as catalysts, acrylamide and 2-acrylamide-2-methylpropanesulfonic acid were used as monomers to obtain a macroinitiator by an atom transfer radical polymerization method;

[0011]

[0012] Step A2: Dehydroabietic acid and dichloromethane were mixed, stirred at a stirring rate of 140-180 rpm and a temperature of 0-5 °C under nitrogen protection, oxalyl chloride and N,N-dimethylformamide were added, reacted for 3-4 h, and rotary evaporated to obtain intermediate 1; intermediate 1 and dichloromethane were mixed, stirred at a stirring rate of 140-180 rpm and a temperature of 0-5 °C under nitrogen protection, triethylamine and hydroxyethyl methacrylate were added, reacted for 48 h, washed with sodium bicarbonate solution until neutral, dried, rotary evaporated, and dried to obtain intermediate 2;

[0013] The amount ratio of dehydroabietyl acid, dichloromethane, oxalyl chloride and N,N-dimethylformamide is 28-30 g: 160-180 mL: 25-26 g: 0.8-1 mL; the mass fraction of sodium bicarbonate solution is 5%, and the amount ratio of intermediate 1, dichloromethane, triethylamine and hydroxyethyl methacrylate is 24-26 g: 160-180 mL: 14.5-14.8 g: 14.4-14.5 g;

[0014] During the reaction, the carboxyl group in the dehydroabietyl acid reacts with the oxalyl chloride to form an acyl chloride group, and intermediate 1 is prepared; then, under the action of triethylamine, the acyl chloride group in intermediate 1 reacts with the hydroxyl group in hydroxyethyl methacrylate to form an ester group and introduce a double bond, and intermediate 2 is prepared;

[0015]

[0016] Step A3: The macromolecular initiator, sodium ascorbate, intermediate 2, N,N-dimethylformamide and deionized water are mixed, and under the condition of argon protection, stirring speed of 180-200 rpm and temperature of 30-35 °C, cuprous bromide is added and stirred for 10-12 h, rotary evaporation, recrystallization, filtration and drying to prepare the modified polyacrylamide;

[0017] The amount ratio of the macromolecular initiator, sodium ascorbate, intermediate 2, N,N-dimethylformamide, deionized water and cuprous bromide is 4.2-4.5 g: 0.03-0.05 g: 0.8-0.9 g: 10-12 mL: 15-18 mL: 0.02-0.03 g;

[0018] During the reaction, the double bond in intermediate 2 reacts with the end of the macromolecular initiator by the atom transfer radical polymerization method to form a telechelic block structure with a dehydroabietyl acid segment at the end, and the modified polyacrylamide is prepared;

[0019]

[0020] The composite crosslinking agent is prepared by the following steps:

[0021] Step B1: The sodium phytate, zirconium dichloride octahydrate and deionized water are mixed, hydrochloric acid solution is added and stirred to adjust the pH value to 4, and then the stirring speed is 180-240 rpm and the temperature is 80-90 °C, and the reaction is carried out for 1 h, centrifugation, washing, filtration, grinding to prepare the zirconium phytate complex; the sodium-based montmorillonite and deionized water are mixed and ultrasonically dispersed for 10-15 min, and then the stirring speed is 180-240 rpm and the temperature is 50-55 °C, and the zirconium phytate complex and N,N-dimethylformamide are added and stirred for 24 h, centrifugation, washing and drying to prepare the intercalated montmorillonite;

[0022] The mass fraction of hydrochloric acid solution is 30%, and the dosage ratio of sodium phytate, zirconium dichloride octahydrate and deionized water is 9.5-9.7 g: 9.2-9.3 g: 60-70 mL; the dosage ratio of sodium-based montmorillonite, deionized water, zirconium phytate complex and N,N-dimethylformamide is 0.2-0.24 g: 8-10 mL: 1.8-1.9 g: 15-20 mL;

[0023] The sodium-based montmorillonite is sodium-based montmorillonite with a mesh size of 200;

[0024] During the reaction, the zirconium phytate complex is prepared by direct precipitation method through the complexation between the phosphoric acid bond in the phytate and the zirconium ion, and then the zirconium phytate complex is intercalated into the interlayer of the montmorillonite to prepare the intercalated montmorillonite;

[0025] In step B2, the dextran and deionized water are mixed, and under the conditions of light shielding, a stirring speed of 140-180 rpm and room temperature, the sodium periodate is added and reacted for 3-4 h, then the ethylene glycol is added and reacted for 30-40 min, and then the pure water is dialyzed and dried to prepare the oxidized dextran; the tris(hydroxymethyl)aminomethane and hydrochloric acid solution are mixed, and under the conditions of a stirring speed of 140-180 rpm and a temperature of 60-62℃, the intercalated montmorillonite and deionized water are added and reacted for 3-4 h, then the temperature is lowered to room temperature, and the oxidized dextran is added and reacted for 12 h to prepare the composite crosslinking agent;

[0026] The dosage ratio of the dextran, deionized water, sodium periodate and ethylene glycol is 1.1-1.2 g: 8-10 mL: 0.13-0.14 g: 0.34-0.35 mL; the molar concentration of the hydrochloric acid solution is 0.375 mol / L, and the dosage ratio of the tris(hydroxymethyl)aminomethane, hydrochloric acid solution, intercalated montmorillonite, deionized water and oxidized dextran is 2.15-2.2 g: 300-350 mL: 14-15 g: 300-350 mL: 1.8-2 g;

[0027] The dextran is source leaf dextran T-1;

[0028] During the reaction, the adjacent dialdehyde structure in the dextran is oxidized to form an aldehyde group under the action of the sodium periodate to prepare the oxidized dextran, the intercalated montmorillonite is modified by the tris(hydroxymethyl)aminomethane to introduce an amino group on the surface of the intercalated montmorillonite, and then the amino group reacts with the aldehyde group in the oxidized dextran to form a Schiff base structure to prepare the composite crosslinking agent.

[0029] The present application discloses a kind of oil extraction with delayed crosslinking water plugging profile control agent and preparation method thereof, by with sodium-based montmorillonite as carrier, load zirconium phytate organic crosslinking agent, and introduce Schiff base structure, by nanometer material slow-release effect, so that composite crosslinking agent has good slow-release delayed crosslinking performance, solve the existing water plugging profile control agent crosslinking in advance, leading to the problem of plugging effect decline, and by synthesizing modified polyacrylamide with telechelic structure, further strengthen the plugging performance of water plugging profile control agent;Because the surface of composite crosslinking agent is modified with trishydroxymethyl aminomethane and reacts with oxidized dextran, a Schiff base structure is formed on the surface of the composite crosslinking agent, and a large number of hydroxyl groups are introduced, by the coordination between the Schiff base structure and the zirconium phytate structure released by the composite crosslinking agent, and the hydrogen bond interaction between the large number of hydroxyl groups and the modified polyacrylamide, the gel network formed by it has good gel strength under high temperature conditions, and because the modified polyacrylamide is a telechelic block polymer capped with intermediate 2, the hydrophobic groups are located at both ends of the molecular chain, and the association between the hydrophobic groups is less affected by the molecular chain bending shielding, so the hydrophobic association is more obvious, thereby further improving the gel strength under high temperature conditions, thereby showing good plugging effect. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0031] Embodiment 1: A preparation method of an oil extraction with delayed crosslinking water plugging profile control agent, comprising the following steps: weighing the following raw materials: 25 parts of modified polyacrylamide, 12 parts of composite crosslinking agent, 8 parts of stabilizer and 2 parts of oxygen scavenger, mixing the modified polyacrylamide, composite crosslinking agent, stabilizer and oxygen scavenger to obtain an oil extraction with delayed crosslinking water plugging profile control agent.

[0032] The oxygen scavenger is Gaber XH21 oxygen scavenger.

[0033] The stabilizer is Lingchuang NW-1 stabilizer.

[0034] The modified polyacrylamide is prepared by the following steps:

[0035] Step A1: mixed hydroquinone and dichloromethane, stirred and added 2-bromoisobutyryl bromide under the protection of argon, stirring rate was 180 rpm, temperature was 0 ℃, stirred for 30 min, warmed to room temperature, reacted for 10 h, added triethylamine, continued to stir for 10 min, added deionized water, collected dichloromethane phase by extraction, dried over anhydrous magnesium sulfate, filtered, rotary evaporated, dried, to obtain a double-headed initiator; mixed the double-headed initiator, sodium ascorbate, acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, N,N-dimethylformamide and deionized water, stirred and added cuprous bromide under the protection of nitrogen, stirring rate was 180 rpm, temperature was 35 ℃, reacted for 24 h, rotary evaporated, recrystallized, filtered, dried, to obtain a macromolecular initiator;

[0036] The amount ratio of hydroquinone, dichloromethane, 2-bromoisobutyryl bromide, triethylamine and deionized water was 2 g:45 mL:5.8 mL:0.8 mL:45 mL; the amount ratio of the double-headed initiator, sodium ascorbate, acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, N,N-dimethylformamide, deionized water and cuprous bromide was 0.24 g:0.01 g:3.5 g:2 g:10 mL:20 mL:0.01 g;

[0037] Step A2: mixed dehydroabietic acid and dichloromethane, stirred and added oxalyl chloride and N,N-dimethylformamide under the protection of nitrogen, stirring rate was 140 rpm, temperature was 0 ℃, reacted for 3 h, rotary evaporated, to obtain intermediate 1; mixed intermediate 1 and dichloromethane, stirred and added triethylamine and hydroxyethyl methacrylate under the protection of nitrogen, stirring rate was 140 rpm, temperature was 0 ℃, reacted for 48 h, washed with sodium bicarbonate solution until neutral, dried, rotary evaporated, to obtain intermediate 2;

[0038] The amount ratio of dehydroabietic acid, dichloromethane, oxalyl chloride and N,N-dimethylformamide was 28 g:160 mL:25 g:0.8 mL; the mass fraction of sodium bicarbonate solution was 5%; the amount ratio of intermediate 1, dichloromethane, triethylamine and hydroxyethyl methacrylate was 24 g:160 mL:14.5 g:14.4 g;

[0039] Step A3: mixed the macromolecular initiator, sodium ascorbate, intermediate 2, N,N-dimethylformamide and deionized water under the protection of argon, stirring rate was 180 rpm, temperature was 30 ℃, stirred and added cuprous bromide, reacted for 10 h, rotary evaporated, recrystallized, filtered, dried, to obtain a modified polyacrylamide;

[0040] The amount ratio of the macromolecular initiator, sodium ascorbate, intermediate 2, N,N-dimethylformamide, deionized water and cuprous bromide was 4.2 g:0.03 g:0.8 g:10 mL:15 mL:0.02 g.

[0041] The composite crosslinking agent is prepared by the following steps:

[0042] Step B1: sodium phytate, zirconium dichloride octahydrate and deionized water are mixed, stirred and hydrochloric acid solution is added, the pH value is adjusted to 4, the reaction is carried out at a stirring rate of 240 rpm and a temperature of 80℃ for 1h, centrifugation, washing, filtration, grinding, to obtain a zirconium phytate complex; sodium-based montmorillonite and deionized water are mixed and ultrasonic dispersed for 15 min, stirred and added with the zirconium phytate complex and N,N-dimethylformamide at a stirring rate of 180 rpm and a temperature of 55℃, stirred for 24h, centrifugation, washing, drying, to obtain intercalated montmorillonite;

[0043] The mass fraction of hydrochloric acid solution is 30%, the amount ratio of sodium phytate, zirconium dichloride octahydrate and deionized water is 9.5g:9.3g:60mL; the amount ratio of sodium-based montmorillonite, deionized water, zirconium phytate complex and N,N-dimethylformamide is 0.2g:10mL:1.8g:20mL;

[0044] The sodium-based montmorillonite is Wanda 200 mesh sodium-based montmorillonite;

[0045] Step B2: dextran and deionized water are mixed, stirred and added with sodium periodate under light shielding at a stirring rate of 140 rpm and room temperature, the reaction is carried out for 3h, ethylene glycol is further added and the reaction is carried out for 40 min, pure water dialysis, drying, to obtain oxidized dextran; trimethylol aminomethane and hydrochloric acid solution are mixed, stirred and added with intercalated montmorillonite and deionized water at a stirring rate of 140 rpm and a temperature of 60℃, the reaction is carried out for 4h, the temperature is lowered to room temperature, and oxidized dextran is added, the reaction is carried out for 12h, to obtain a composite crosslinking agent;

[0046] The amount ratio of dextran, deionized water, sodium periodate and ethylene glycol is 1.1g:10mL:0.13g:0.34mL; the molar concentration of hydrochloric acid solution is 0.375mol / L, the amount ratio of trimethylol aminomethane, hydrochloric acid solution, intercalated montmorillonite, deionized water and oxidized dextran is 2.2g:300mL:15g:300mL:1.8g;

[0047] The dextran is source leaf dextran T-1.

[0048] Example 2 A preparation method of a delayed crosslinking water plugging profile control agent for oil production, comprising the following steps: weighing the following raw materials: 30 parts of modified polyacrylamide, 12 parts of a composite crosslinking agent, 10 parts of a stabilizer and 3 parts of an oxygen scavenger, mixing the modified polyacrylamide, the composite crosslinking agent, the stabilizer and the oxygen scavenger, to obtain a delayed crosslinking water plugging profile control agent for oil production;

[0049] The oxygen scavenger is Gabriel XH21 oxygen scavenger;

[0050] The stabilizer is Lingchuang NW-1 stabilizer;

[0051] The modified polyacrylamide is prepared by the following steps:

[0052] Step A1: hydroquinone and dichloromethane are mixed, stirring is carried out under the protection of argon at a stirring rate of 180 rpm and a temperature of 5℃, 2-bromoisobutyryl bromide is added, stirring is carried out for 30 min, the temperature is raised to room temperature, reaction is carried out for 12 h, triethylamine is added, stirring is continued for 15 min, deionized water is added, the dichloromethane phase is collected by extraction, dried with anhydrous magnesium sulfate, filtered, rotary evaporated, and dried to obtain a double-headed initiator; the double-headed initiator, sodium ascorbate, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, N,N-dimethylformamide and deionized water are mixed, stirring is carried out under the protection of nitrogen at a stirring rate of 180 rpm and a temperature of 40℃, cuprous bromide is added, reaction is carried out for 24 h, rotary evaporation is carried out, recrystallization is carried out, filtration is carried out, and drying is carried out to obtain a macromolecular initiator;

[0053] The amount ratio of hydroquinone, dichloromethane, 2-bromoisobutyryl bromide, triethylamine and deionized water is 2g:50mL:5.8mL:1mL:45mL; the amount ratio of the double-headed initiator, sodium ascorbate, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, N,N-dimethylformamide, deionized water and cuprous bromide is 0.24g:0.01g:3.5g:2.1g:10mL:25mL:0.01g;

[0054] Step A2: dehydroabietic acid and dichloromethane are mixed, stirring is carried out under the protection of nitrogen at a stirring rate of 180 rpm and a temperature of 0℃, oxalyl chloride and N,N-dimethylformamide are added, reaction is carried out for 4 h, rotary evaporation is carried out to obtain intermediate 1, intermediate 1 and dichloromethane are mixed, stirring is carried out under the protection of nitrogen at a stirring rate of 140 rpm and a temperature of 5℃, triethylamine and hydroxyethyl methacrylate are added, reaction is carried out for 48 h, sodium bicarbonate solution is used for washing until neutral, drying is carried out, and rotary evaporation is carried out to obtain intermediate 2;

[0055] The amount ratio of dehydroabietic acid, dichloromethane, oxalyl chloride and N,N-dimethylformamide is 28-30g:160mL:26g:0.8mL; the mass fraction of sodium bicarbonate solution is 5%, the amount ratio of intermediate 1, dichloromethane, triethylamine and hydroxyethyl methacrylate is 26g:160mL:14.5g:14.5g;

[0056] Step A3: the macromolecular initiator, sodium ascorbate, intermediate 2, N,N- dimethylformamide and deionized water were mixed, stirring at a speed of 200 rpm under argon protection at a temperature of 30℃, stirring and adding cuprous bromide, reacting for 10 h, rotary evaporation, recrystallization, filtration and drying to obtain modified polyacrylamide;

[0057] The macromolecular initiator, sodium ascorbate, intermediate 2, N,N- dimethylformamide, deionized water and cuprous bromide were used in a ratio of 4.5 g: 0.03 g: 0.9 g: 10 mL: 18 mL: 0.02 g;

[0058] The composite crosslinking agent was prepared by the following steps:

[0059] Step B1: sodium phytate, zirconium dichloride octahydrate and deionized water were mixed, stirring and adding hydrochloric acid solution to adjust the pH value to 4, reacting for 1 h under stirring at a speed of 180 rpm at a temperature of 80℃, centrifugation, washing, filtration, grinding to obtain zirconium phytate complex; sodium-based montmorillonite and deionized water were mixed and ultrasonically dispersed for 10 min, stirring and adding zirconium phytate complex and N,N-dimethylformamide under stirring at a speed of 180 rpm at a temperature of 50℃, stirring for 24 h, centrifugation, washing and drying to obtain intercalated montmorillonite;

[0060] The mass fraction of hydrochloric acid solution was 30%, and the sodium phytate, zirconium dichloride octahydrate and deionized water were used in a ratio of 9.5 g: 9.2 g: 60 mL; the sodium-based montmorillonite, deionized water, zirconium phytate complex and N,N-dimethylformamide were used in a ratio of 0.2 g: 8 mL: 1.8 g: 15 mL;

[0061] The sodium-based montmorillonite was 200 mesh sodium-based montmorillonite;

[0062] Step B2: dextran and deionized water were mixed, stirring and adding sodium periodate under light shielding at a stirring speed of 140 rpm at room temperature, reacting for 3 h, further adding ethylene glycol and continuing to react for 30 min, pure water dialysis and drying to obtain oxidized dextran; tris-hydroxymethyl aminomethane and hydrochloric acid solution were mixed, stirring and adding intercalated montmorillonite and deionized water under stirring at a speed of 140 rpm at a temperature of 60℃, reacting for 3 h, further cooling to room temperature and adding oxidized dextran, and continuing to react for 12 h to obtain the composite crosslinking agent;

[0063] The dextran, deionized water, sodium periodate and ethylene glycol were used in a ratio of 1.1 g: 8 mL: 0.13 g: 0.34 mL; the molar concentration of hydrochloric acid solution was 0.375 mol / L, and the tris-hydroxymethyl aminomethane, hydrochloric acid solution, intercalated montmorillonite, deionized water and oxidized dextran were used in a ratio of 2.15 g: 300 mL: 14 g: 300 mL: 1.8 g.

[0064] The glucan is leaf glucan T-1.

[0065] A preparation method of the delayed cross-linking water plugging profile control agent for oil extraction, comprising the following steps: weighing the raw materials in the following weight parts: 30 parts of modified polyacrylamide, 15 parts of composite cross-linking agent, 10 parts of stabilizer and 3 parts of oxygen scavenger, mixing the modified polyacrylamide, the composite cross-linking agent, the stabilizer and the oxygen scavenger to prepare a delayed cross-linking water plugging profile control agent for oil extraction;

[0066] The oxygen scavenger is Gaber XH21 oxygen scavenger;

[0067] The stabilizer is Lingchuang NW-1 stabilizer;

[0068] The modified polyacrylamide is prepared by the following steps:

[0069] Step A1: mixing hydroquinone and dichloromethane, stirring under argon protection at a stirring speed of 240 rpm and a temperature of 5℃, adding 2-bromoisobutyryl bromide, stirring for 30 min, increasing the temperature to room temperature, reacting for 12 h, adding triethylamine again, continuing to stir for 15 min, adding deionized water again, extracting and collecting the dichloromethane phase, drying with anhydrous magnesium sulfate, filtering, rotary evaporation, drying to prepare a double-headed initiator; mixing the double-headed initiator, sodium ascorbate, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, N,N-dimethylformamide and deionized water, stirring under nitrogen protection at a stirring speed of 240 rpm and a temperature of 40℃, adding cuprous bromide, reacting for 24 h, rotary evaporation, recrystallization, filtering, drying to prepare a macromolecular initiator;

[0070] The amount ratio of hydroquinone, dichloromethane, 2-bromoisobutyryl bromide, triethylamine and deionized water is 2.1 g: 50 mL: 5.9 mL: 1 mL: 50 mL; the amount ratio of the double-headed initiator, sodium ascorbate, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, N,N-dimethylformamide, deionized water and cuprous bromide is 0.25 g: 0.01 g: 3.6 g: 2.1 g: 15 mL: 25 mL: 0.02 g;

[0071] Step A2: mixing dehydroabietic acid and dichloromethane, stirring under nitrogen protection at a stirring speed of 180 rpm and a temperature of 5℃, adding oxalyl chloride and N,N-dimethylformamide, reacting for 4 h, rotary evaporation to prepare intermediate 1; mixing intermediate 1 and dichloromethane, stirring under nitrogen protection at a stirring speed of 180 rpm and a temperature of 5℃, adding triethylamine and hydroxyethyl methacrylate, reacting for 48 h, washing with sodium bicarbonate solution until neutral, drying, rotary evaporation to prepare intermediate 2;

[0072] Dehydroabietic acid, dichloromethane, oxalyl chloride and N,N-dimethylformamide were used in a ratio of 30 g:180 mL:26 g:1 mL; sodium bicarbonate solution was 5% by mass; intermediate 1, dichloromethane, triethylamine and hydroxyethyl methacrylate were used in a ratio of 26 g:180 mL:14.8 g:14.5 g;

[0073] Step A3: The macromolecular initiator, sodium ascorbate, intermediate 2, N,N-dimethylformamide and deionized water were mixed, stirring was carried out under argon protection at a stirring rate of 200 rpm and a temperature of 35℃, cuprous bromide was added, reaction was carried out for 12 h, rotary evaporation was carried out, recrystallization was carried out, filtration was carried out, and drying was carried out to obtain modified polyacrylamide;

[0074] The macromolecular initiator, sodium ascorbate, intermediate 2, N,N-dimethylformamide, deionized water and cuprous bromide were used in a ratio of 4.5 g:0.05 g:0.9 g:12 mL:18 mL:0.03 g;

[0075] The composite crosslinking agent was prepared by the following steps:

[0076] Step B1: Sodium phytate, zirconium dichloride oxide octahydrate and deionized water were mixed, hydrochloric acid solution was added, the pH value was adjusted to 4, reaction was carried out at a stirring rate of 240 rpm and a temperature of 90℃ for 1 h, centrifugation was carried out, washing was carried out, filtration was carried out, grinding was carried out to obtain a zirconium phytate complex; sodium-based montmorillonite and deionized water were mixed and ultrasonic dispersion was carried out for 15 min, stirring was carried out at a stirring rate of 240 rpm and a temperature of 55℃, the zirconium phytate complex and N,N-dimethylformamide were added, stirring was carried out for 24 h, centrifugation was carried out, washing was carried out, drying was carried out to obtain intercalated montmorillonite;

[0077] The hydrochloric acid solution was 30% by mass; sodium phytate, zirconium dichloride oxide octahydrate and deionized water were used in a ratio of 9.7 g:9.3 g:70 mL; sodium-based montmorillonite, deionized water, the zirconium phytate complex and N,N-dimethylformamide were used in a ratio of 0.24 g:10 mL:1.9 g:20 mL;

[0078] The sodium-based montmorillonite was 200 mesh sodium-based montmorillonite;

[0079] Step B2: Dextran and deionized water were mixed, stirring was carried out in the dark at a stirring rate of 180 rpm and room temperature, sodium periodate was added, reaction was carried out for 4 h, ethylene glycol was further added, reaction was carried out for 40 min, pure water dialysis was carried out, and drying was carried out to obtain oxidized dextran; tris(hydroxymethyl)aminomethane and hydrochloric acid solution were mixed, stirring was carried out at a stirring rate of 180 rpm and a temperature of 62℃, the intercalated montmorillonite and deionized water were added, reaction was carried out for 4 h, the temperature was lowered to room temperature, and oxidized dextran was added, reaction was carried out for 12 h to obtain the composite crosslinking agent;

[0080] The dosage ratio of dextran, deionized water, sodium periodate and ethylene glycol is 1.2 g: 10 mL: 0.14 g: 0.35 mL; the molar concentration of hydrochloric acid solution is 0.375 mol / L, and the dosage ratio of tris-hydroxymethyl aminomethane, hydrochloric acid solution, intercalated montmorillonite, deionized water and oxidized dextran is 2.2 g: 350 mL: 15 g: 350 mL: 2 g;

[0081] The dextran is source leaf dextran T-1.

[0082] Comparative Example 1 This comparative example is compared with Example 3, the composite crosslinking agent in the preparation process of the delayed crosslinking water plugging profile control agent of Example 3 is replaced by the intercalated montmorillonite of Example 3, and the other steps are the same.

[0083] Comparative Example 2 This comparative example is compared with Example 3, the intermediate 2 in the preparation process of the modified polyacrylamide of Example 3 is removed, and the other steps are the same.

[0084] Take the oil extraction delayed crosslinking water plugging profile control agent prepared in Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2, mix 6.5 g of the delayed crosslinking water plugging profile control agent with 1000 mL of injection water, the injection water has a salinity of 6000 mg / L and a pH of 6.5, measure the gelation time and gelation strength of the mixture under the condition that the temperature is 65°C, shear the mixture at a shear rate of 40 rad / s for 24 h, stand for 30 min, then measure the gelation strength of the mixture again, calculate the gelation strength retention rate of the mixture after shearing, and use a man-made core with a length of 6 cm, a diameter of 2.5 cm, a porosity of 28.80% and a permeability of 756*10 -3 μm -2 Drive the core with water at a flow rate of 0.5 mL / min and a temperature of 50°C, and measure the plugging rate and residual resistance coefficient of the core, and the test results are shown in the following Table 1.

[0085] Table 1 Test Results

[0086] Test item Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Gelling time (h) 75.5 75.4 75.6 79.4 75.4 Gelling strength (mPa·s) 17277 17354 17580 15253 17074 Retention rate of gelling strength after shearing (%) 94.21 94.19 94.52 91.04 94.28 Plugging rate (%) 97.04 97.18 97.63 92.32 96.87 Residual drag coefficient 42.41 42.62 42.97 38.31 41.90

[0087] As can be seen from the test results in the table, when Example 1, Example 2 and Example 3 are compared with Comparative Example 1 and Comparative Example 2, the composite crosslinking agent in the preparation process of the delayed crosslinking water plugging profile control agent of Example 3 is replaced by the intercalated montmorillonite of Example 3 in Comparative Example 1, which leads to a decrease in the strength of the gel after gelation due to the lack of Schiff base structure and hydroxyl groups, and the intermediate 2 in the preparation process of the modified polyacrylamide of Example 3 is removed in Comparative Example 2, which leads to a decrease in the strength of the gel after gelation due to the lack of telechelic block structure.

[0088] In the description, references to "one embodiment," "an example," "certain examples" etc. mean that the particular feature, structure, material, or characteristic being described is included in at least one embodiment or example of the application. The appearances of an item in various examples or embodiments is not necessarily indicative of a frequency of occurrence in the various examples or embodiments. Moreover, descriptions of well-known methods associated are omitted so as not to obscure the disclosure.

[0089] The foregoing merely illustrates the principles of the application. Various modifications and adaptations will occur to those skilled in the art after consideration of the preceding description. All such modifications and adaptations employing the principles of the application are intended to be within the scope of the claims.

Claims

1. A method for preparing a delayed crosslinking water shut-off and profile control agent for oil production, characterized in that: The process includes the following steps: Weigh the following raw materials by weight: 25-30 parts modified polyacrylamide, 12-15 parts composite crosslinking agent, 8-10 parts stabilizer and 2-3 parts oxygen scavenger, mix the modified polyacrylamide, composite crosslinking agent, stabilizer and oxygen scavenger to prepare an oil production delayed crosslinking water shut-off and profile control agent. The modified polyacrylamide is prepared by the following steps: Step A1: Hydroquinone and dichloromethane are mixed and stirred under argon protection at a stirring rate of 180-240 rpm and a temperature of 0-5℃. 2-Bromoisobutyryl bromide is added and stirred for 30 min. The mixture is then heated to room temperature and reacted for 10-12 h. Triethylamine is added and stirring is continued for 10-15 min. Deionized water is then added, and the dichloromethane phase is extracted and collected. The phase is dried over anhydrous magnesium sulfate, filtered, rotary evaporated, and dried to obtain the bi-headed initiator. The bi-headed initiator, sodium ascorbate, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, N,N-dimethylformamide, and deionized water are mixed and stirred under nitrogen protection at a stirring rate of 180-240 rpm and a temperature of 35-40℃. Cuprous bromide is added and stirred for 24 h. The mixture is then rotary evaporated, recrystallized, filtered, and dried to obtain the macromolecular initiator. Step A2: Dehydroabsic acid and dichloromethane were mixed and stirred under nitrogen protection at a stirring speed of 140-180 rpm and a temperature of 0-5℃. Oxaloyl chloride and N,N-dimethylformamide were added and the mixture was reacted for 3-4 hours. The mixture was then rotary evaporated to obtain intermediate 1. Intermediate 1 was mixed with dichloromethane and stirred under nitrogen protection at a stirring speed of 140-180 rpm and a temperature of 0-5℃. Triethylamine and hydroxyethyl methacrylate were added and the mixture was reacted for 48 hours. The mixture was washed with sodium bicarbonate solution until neutral, dried, and rotary evaporated to obtain intermediate 2. Step A3: Mix macromolecular initiator, sodium ascorbate, intermediate 2, N,N-dimethylformamide and deionized water. Under argon protection, with a stirring rate of 180-200 rpm and a temperature of 30-35℃, stir and add cuprous bromide. React for 10-12 hours, rotary evaporate, recrystallize, filter, and dry to obtain modified polyacrylamide. The composite crosslinking agent is prepared by the following steps: Step B1: Sodium phytate, zirconium dichloride octahydrate, and deionized water were mixed, stirred, and hydrochloric acid solution was added to adjust the pH to 4. The mixture was reacted for 1 hour at a stirring speed of 180-240 rpm and a temperature of 80-90℃. After centrifugation, washing, filtration, and grinding, the zirconium phytate complex was obtained. Sodium-based montmorillonite and deionized water were mixed and ultrasonically dispersed for 10-15 minutes. The mixture was stirred at a stirring speed of 180-240 rpm and a temperature of 50-55℃, and the zirconium phytate complex and N,N-dimethylformamide were added. The mixture was stirred for 24 hours, centrifuged, washed, and dried to obtain intercalated montmorillonite. Step B2: Mix dextran and deionized water, stir at 140-180 rpm in the dark at room temperature, add sodium periodate, and react for 3-4 hours. Then add ethylene glycol and continue the reaction for 30-40 minutes. Dialyze with pure water and dry to obtain oxidized dextran. Mix tris(hydroxymethyl)aminomethane and hydrochloric acid solution, stir at 140-180 rpm at 60-62℃, add intercalated montmorillonite and deionized water, and react for 3-4 hours. Then cool to room temperature, add oxidized dextran, and continue the reaction for 12 hours to obtain the composite crosslinking agent. The delayed crosslinking water-blocking and profile control agent prepared by this method has a shear strength retention rate of 94.52% and a gel strength of 17580 mPa·s. In step A1: the ratio of hydroquinone, dichloromethane, 2-bromoisobutyryl bromide, triethylamine, and deionized water is 2-2.1g: 45-50mL: 5.8-5.9mL: 0.8-1mL: 45-50mL; the ratio of bis-headed initiator, sodium ascorbate, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, N,N-dimethylformamide, deionized water, and cuprous bromide is 0.24-0.25g: 0.01g: 3.5-3.6g: 2-2.1g: 10-15mL: 20-25mL: 0.01-0.02g. In step B2: the ratio of dextran, deionized water, sodium periodate, and ethylene glycol is 1.1-1.2g: 8-10mL: 0.13-0.14g: 0.34-0.35mL; the molar concentration of hydrochloric acid solution is 0.375mol / L; and the ratio of tris(hydroxymethyl)aminomethane, hydrochloric acid solution, intercalated montmorillonite, deionized water, and oxidized dextran is 2.15-2.2g: 300-350mL: 14-15g: 300-350mL: 1.8-2g.

2. The preparation method of a delayed crosslinking water shut-off and profile control agent for oil production according to claim 1, characterized in that: In step A2: the ratio of dehydroabsic acid, dichloromethane, oxaloyl chloride, and N,N-dimethylformamide is 28-30g: 160-180mL: 25-26g: 0.8-1mL; the sodium bicarbonate solution has a mass fraction of 5%; and the ratio of intermediate 1, dichloromethane, triethylamine, and hydroxyethyl methacrylate is 24-26g: 160-180mL: 14.5-14.8g: 14.4-14.5g.

3. The preparation method of a delayed crosslinking water shut-off and profile control agent for oil production according to claim 1, characterized in that: In step A3: the ratio of macromolecular initiator, sodium ascorbate, intermediate 2, N,N-dimethylformamide, deionized water and cuprous bromide is 4.2-4.5g: 0.03-0.05g: 0.8-0.9g: 10-12mL: 15-18mL: 0.02-0.03g.

4. The preparation method of a delayed crosslinking water shut-off and profile control agent for oil production according to claim 1, characterized in that: In step B1: the hydrochloric acid solution has a mass fraction of 30%, and the ratio of sodium phytate, zirconium dichloride octahydrate, and deionized water is 9.5-9.7g: 9.2-9.3g: 60-70mL; the ratio of sodium montmorillonite, deionized water, zirconium phytate complex, and N,N-dimethylformamide is 0.2-0.24g: 8-10mL: 1.8-1.9g: 15-20mL.

5. A delayed crosslinking water shut-off and profile control agent for oil production, characterized in that: Prepared according to any one of the preparation methods described in claims 1-4.

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