Gemini quaternary ammonium salt polyether surfactant for oil-displacing agent and preparation method of gemini quaternary ammonium salt polyether surfactant

Abstract

The invention discloses a gemini quaternary ammonium salt polyether surfactant for an oil-displacing agent and a preparation method of the gemini quaternary ammonium salt polyether surfactant. The preparation method comprises the following steps: reacting allyloxy polyoxyethylene ether with heptamethyltrisiloxane under the action of a platinum catalyst to obtain polyether modified trisiloxane; the preparation method comprises the following steps: reacting nano aluminum oxide with gamma-aminopropyltriethoxysilane to obtain aminated nano aluminum oxide; reacting the nano-alumina with benzophenone tetracarboxylic dianhydride under the action of a pyridine catalyst to obtain dicarboxyl nano-alumina; reacting the tertiary amino nano aluminum oxide with 3-dimethylaminopropanol under the action of a p-toluenesulfonic acid catalyst to obtain tertiary amino nano aluminum oxide; reacting the nano-alumina with chloroacetic acid to obtain double quaternized nano-alumina; and then reacting with polyether modified trisiloxane under the action of a dibutyltin dilaurate catalyst, thereby obtaining the product. Through the synergistic effect of the nano aluminum oxide and the polyether modified trisiloxane, the oil displacement efficiency of the oil displacement agent is improved, and meanwhile, the damage to the stratum is also reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of oil displacing agents, and specifically relates to a gemini quaternary ammonium salt polyether surfactant used in oil displacing agents. The invention also relates to a preparation method of the gemini quaternary ammonium salt polyether surfactant used in oil displacing agents. Background Art

[0002] Surfactants can reduce the surface tension of the interface, emulsify oil and water, and increase the charge density, and have good effects in oil field production. Patent CN86107891A reports a surfactant flooding system, which does not contain alcohol and additives, has low interfacial tension and high solubilization parameters. However, the surfactant application concentration of this system is high, not less than 0.5%.

[0003] For example, the document "Synthesis and Performance Study of Double Polyether Co-Modified Trisiloxane Surfactant" reports that polyether-modified trisiloxane has a lower surface tension; the present invention prepares a gemini quaternary ammonium salt polyether surfactant for oil displacement agent by modifying it to solve the problem of low oil displacement efficiency. Summary of the invention

[0004] The purpose of the present invention is to provide a gemini quaternary ammonium salt polyether surfactant for oil displacement agent, which solves the problem that the oil displacement efficiency of the existing surfactant is low.

[0005] Another object of the present invention is to provide a method for preparing a gemini quaternary ammonium salt polyether surfactant for oil displacement agent.

[0006] The first technical solution adopted by the present invention is: a method for preparing a gemini quaternary ammonium salt polyether surfactant for an oil displacement agent, comprising the following steps:

[0007] Step 1, reacting allyloxy polyoxyethylene ether and heptamethyl trisiloxane under the action of a platinum catalyst to obtain polyether-modified trisiloxane;

[0008] Step 2, reacting nano-alumina with γ-aminopropyltriethoxysilane to obtain amino-treated nano-alumina;

[0009] Step 3, reacting the amino nano-alumina and benzophenone tetracarboxylic dianhydride under the action of pyridine catalyst to obtain dicarboxyl nano-alumina;

[0010] Step 4, reacting 3-dimethylaminopropanol and dicarboxyl nano-alumina under the action of p-toluenesulfonic acid catalyst to obtain tertiary amine nano-alumina;

[0011] Step 5, reacting tertiary amine-based nano-alumina with chloroacetic acid to obtain diquaternized nano-alumina;

[0012] Step 6: reacting the diquaternized nano-alumina and the polyether-modified trisiloxane under the action of dibutyltin dilaurate catalyst to obtain a gemini quaternary ammonium salt polyether surfactant.

[0013] The first technical solution of the present invention is also characterized in that:

[0014] Step 1 is specifically as follows: adding allyloxy polyoxyethylene ether to N,N-dimethylformamide solvent, adding platinum catalyst after stirring to dissolve, heating to 70-95°C for activation for 0.4-1h, then continuing to heat to 100-110°C, and then dripping heptamethyl trisiloxane at a constant pressure, reacting at 105-115°C for 4-7h after the dripping, and removing low-boiling substances by reduced pressure distillation to obtain polyether-modified trisiloxane; wherein the mass ratio of allyloxy polyoxyethylene ether, platinum catalyst, and heptamethyl trisiloxane is 1.1-1.3:1:0.01-0.03.

[0015] Step 2 is specifically as follows: ultrasonically disperse the nano-alumina into a mixed solvent of anhydrous ethanol and deionized water, add γ-aminopropyltriethoxysilane after mixing evenly, react at 75-90°C for 8-15h, then centrifuge, wash and dry to obtain amino-treated nano-alumina; wherein the mass ratio of nano-alumina to γ-aminopropyltriethoxysilane is 1:1.2-1.5.

[0016] Step 3 is specifically as follows: adding amino nano-alumina and benzophenone tetracarboxylic anhydride to a toluene solvent, stirring evenly and then adding a pyridine catalyst, heating to 75-95° C. and stirring to react for 15-30 hours, and after the reaction, reducing pressure and concentrating to remove the solvent, then washing with ether, dissolving in dichloromethane and recrystallizing and purifying to obtain dicarboxyl nano-alumina; wherein the mass ratio of amino nano-alumina, benzophenone tetracarboxylic anhydride, and pyridine catalyst is 1.3-1.8:1:0.02-0.04.

[0017] Step 4 is specifically as follows: add 3-dimethylaminopropanol and dicarboxyl nano-alumina to N,N-dimethylformamide solvent, stir and mix, then add p-toluenesulfonic acid catalyst, react at 80-95° C. for 8-15 hours, and then perform reduced pressure distillation, filter and dry to obtain tertiary amine nano-alumina; wherein the mass ratio of 3-dimethylaminopropanol, dicarboxyl nano-alumina and p-toluenesulfonic acid catalyst is 2.1-2.3:1:0.04-0.06.

[0018] Step 5 is specifically as follows: adding tertiary amine nano-alumina and chloroacetic acid to an acetone solvent, stirring and mixing, adding a sodium hydroxide solution with a mass fraction of 8 to 15%, reacting at 80 to 120° C. for 2 to 4 hours, filtering and drying after the reaction, and obtaining diquaternized nano-alumina; wherein the mass ratio of tertiary amine nano-alumina to chloroacetic acid is 1:2.1 to 2.6.

[0019] Step 6 is specifically as follows: adding diquaternized nano alumina and polyether modified trisiloxane to N,N-dimethylformamide solvent, stirring and dissolving, adding dibutyltin dilaurate catalyst, reacting at 95-110° C. for 6-10 hours, and then performing reduced pressure distillation, filtering and drying to obtain a gemini quaternary ammonium polyether surfactant for oil displacement agent; wherein the mass ratio of diquaternized nano alumina, polyether modified trisiloxane and dibutyltin dilaurate catalyst is 1.3-1.7:1:0.05-0.07.

[0020] The second technical solution adopted by the present invention is: the gemini quaternary ammonium salt polyether surfactant for oil displacing agent is prepared by adopting the preparation method of the gemini quaternary ammonium salt polyether surfactant for oil displacing agent.

[0021] The beneficial effects of the present invention are as follows: the gemini quaternary ammonium salt polyether surfactant for oil displacement agent and the preparation method thereof improve the oil displacement efficiency through the synergistic effect of nano-alumina and polyether-modified trisiloxane, and the zwitterionic surfactant contained therein is closely arranged on the interface, and the adsorption amount is increased, which is beneficial to increase the surface activity and also reduces the damage to the formation. DETAILED DESCRIPTION

[0022] The present invention is described in detail below in conjunction with specific implementation modes.

[0023] The invention provides a method for preparing a gemini quaternary ammonium salt polyether surfactant for an oil displacement agent. The raw materials used are as follows: allyloxy polyoxyethylene ether (CAS No. 13290-96-5, average molecular weight 400); heptamethyl trisiloxane (purchased from Hubei Baidu Chemical Co., Ltd.); benzophenone tetracarboxylic dianhydride (CAS No. 2421-28-5); N,N-dimethylformamide (analytical grade, purchased from Tianjin Damao Chemical Reagent Factory); pyridine catalyst (CAS No. 110-86-1); chloroacetic acid (CAS No. 79-11-8); acetone (CAS No. 67-64-1); and dibutyltin dilaurate (CAS No. 77-58-7).

[0024] The platinum catalyst is specifically prepared by the following steps: 0.5 g of nano-silica is mixed with 30 mL of ethanol, 20 mL of 3.6 mol / L chloroplatinic acid isopropanol solution is added, refluxed at 50-80° C. for 5-8 h, filtered, washed with deionized water for 3 times, and dried in an oven at 80° C. for 10 min to obtain the platinum catalyst.

[0025] Example 1

[0026] (1) adding allyloxy polyoxyethylene ether to N,N-dimethylformamide solvent, stirring and dissolving, continuously adding platinum catalyst thereto, heating to 70°C for activation for 0.4h, then continuously heating to 100°C, and adding heptamethyl trisiloxane thereto dropwise at a constant pressure, wherein the mass ratio of allyloxy polyoxyethylene ether, platinum catalyst, and heptamethyl trisiloxane is 1.1:1:0.01, reacting at 105°C for 4h after the addition, and removing low-boiling substances by reduced pressure distillation after the addition, to obtain polyether-modified trisiloxane;

[0027] (2) Ultrasonic dispersion of nano-alumina in a mixed solvent of 30 mL of anhydrous ethanol and 10 mL of deionized water, after uniform mixing, adding γ-aminopropyltriethoxysilane, wherein the mass ratio of nano-alumina to γ-aminopropyltriethoxysilane is 1:1.2, reacting at 75° C. for 8 h, after the reaction, centrifuging to obtain a solid, washing the solid with deionized water for 3 times, and drying in an oven at 70° C. for 10 min to obtain amino-modified nano-alumina;

[0028] (3) adding amino nano-alumina and benzophenone tetracarboxylic acid dianhydride to toluene solvent, stirring evenly, and continuing to add pyridine catalyst, wherein the amino nano-alumina, benzophenone tetracarboxylic acid dianhydride, and pyridine catalyst are 1.3:1:0.02, heating to 75° C. and stirring for 15 hours, after the reaction, concentrating under reduced pressure to remove the solvent, dissolving in dichloromethane for recrystallization and purification, to obtain dicarboxyl nano-alumina;

[0029] (4) adding 3-dimethylaminopropanol and dicarboxyl nano-alumina to N,N-dimethylformamide solvent, stirring and mixing, and then continuing to add p-toluenesulfonic acid catalyst, wherein the mass ratio of 3-dimethylaminopropanol, dicarboxyl nano-alumina, and p-toluenesulfonic acid catalyst is 2.1:1:0.04, reacting at 80° C. for 8 hours, and then performing reduced pressure distillation after the reaction, filtering and drying to obtain tertiary amine nano-alumina;

[0030] (5) adding tertiary amine nano-alumina and chloroacetic acid to an acetone solvent, wherein the mass ratio of tertiary amine nano-alumina to chloroacetic acid is 1:2.1, stirring and mixing, adding 2.5 mL of 8% sodium hydroxide solution, reacting at 80° C. for 2 h, filtering and drying after the reaction, to obtain diquaternized nano-alumina;

[0031] (6) Add diquaternized nano-alumina and polyether-modified trisiloxane to N,N-dimethylformamide solvent, stir and dissolve, and continue to add dibutyltin dilaurate catalyst, wherein the mass ratio of diquaternized nano-alumina, polyether-modified trisiloxane and dibutyltin dilaurate catalyst is 1.3:1:0.05, react at 95°C for 6h, and then perform vacuum distillation, filter and dry to obtain a gemini quaternary ammonium polyether surfactant for oil displacement agent.

[0032] Example 2

[0033] (1) adding allyloxy polyoxyethylene ether to N,N-dimethylformamide solvent, stirring and dissolving, continuously adding platinum catalyst thereto, heating to 95° C. for activation for 1 hour, then continuously heating to 110° C., and adding heptamethyl trisiloxane thereto dropwise at a constant pressure, wherein the mass ratio of allyloxy polyoxyethylene ether, platinum catalyst, and heptamethyl trisiloxane is 1.3:1:0.03, reacting at 115° C. for 7 hours after the addition is completed, and then removing low-boiling substances by reduced pressure distillation to obtain polyether-modified trisiloxane;

[0034] (2) Ultrasonic dispersion of nano-alumina in 30 mL of anhydrous ethanol and 10 mL of a mixed solvent, after uniform mixing, adding γ-aminopropyltriethoxysilane, wherein the mass ratio of nano-alumina to γ-aminopropyltriethoxysilane is 1:1.5, reacting at 90° C. for 15 h, after the reaction, centrifuging to obtain a solid, washing the solid with deionized water three times, drying in an oven at 70° C. for 10 min, washing and drying to obtain amino nano-alumina;

[0035] (3) adding amino nano-alumina and benzophenone tetracarboxylic anhydride to a toluene solvent, stirring evenly, and continuing to add a pyridine catalyst, wherein the amino nano-alumina, benzophenone tetracarboxylic anhydride, and pyridine catalyst are 1.8:1:0.04, heating to 95° C. and stirring to react for 30 hours, and after the reaction, concentrating under reduced pressure to remove the solvent, then washing with ether, dissolving in dichloromethane for recrystallization and purification, to obtain dicarboxyl nano-alumina;

[0036] (4) adding 3-dimethylaminopropanol and dicarboxyl nano-alumina to N,N-dimethylformamide solvent, stirring and mixing, and then continuing to add p-toluenesulfonic acid catalyst, wherein the mass ratio of 3-dimethylaminopropanol, dicarboxyl nano-alumina, and p-toluenesulfonic acid catalyst is 2.3:1:0.06, reacting at 95° C. for 15 hours, and then performing reduced pressure distillation after the reaction, filtering and drying to obtain tertiary amine nano-alumina;

[0037] (5) adding tertiary amine nano-alumina and chloroacetic acid to an acetone solvent, wherein the mass ratio of tertiary amine nano-alumina to chloroacetic acid is 1:2.6, stirring and mixing, adding 2.6 mL of a 15% sodium hydroxide solution, reacting at 120° C. for 4 h, filtering and drying after the reaction, to obtain diquaternized nano-alumina;

[0038] (6) Add diquaternized nano-alumina and polyether-modified trisiloxane to N,N-dimethylformamide solvent, stir to dissolve, and continue to add dibutyltin dilaurate catalyst, wherein the mass ratio of diquaternized nano-alumina, polyether-modified trisiloxane and dibutyltin dilaurate catalyst is 1.7:1:0.07, react at 110° C. for 10 h, and then perform reduced pressure distillation, filter and dry to obtain a gemini quaternary ammonium polyether surfactant for oil displacement agent.

[0039] Example 3

[0040] (1) adding allyloxy polyoxyethylene ether to N,N-dimethylformamide solvent, stirring and dissolving, continuously adding platinum catalyst thereto, heating to 82.5°C for activation for 0.7h, then continuously heating to 105°C, and adding heptamethyl trisiloxane thereto dropwise at a constant pressure, wherein the mass ratio of allyloxy polyoxyethylene ether, platinum catalyst, and heptamethyl trisiloxane is 1.2:1:0.02, reacting at 110°C for 5.5h after the addition is completed, and then removing low-boiling substances by reduced pressure distillation to obtain polyether-modified trisiloxane;

[0041] (2) Ultrasonic dispersion of nano-alumina in 30 mL of anhydrous ethanol and 10 mL of a mixed solvent, after uniform mixing, adding γ-aminopropyltriethoxysilane, wherein the mass ratio of nano-alumina to γ-aminopropyltriethoxysilane is 1:1.35, reacting at 82.5° C. for 11.5 h, after the reaction, centrifuging to obtain a solid, washing the solid with deionized water for 3 times, and drying in an oven at 70° C. for 10 min to obtain amino-modified nano-alumina;

[0042] (3) adding amino nano-alumina and benzophenone tetracarboxylic anhydride to a toluene solvent, stirring evenly, and continuing to add a pyridine catalyst, wherein the amino nano-alumina, benzophenone tetracarboxylic anhydride, and pyridine catalyst are 1.55:1:0.03, heating to 85° C. and stirring to react for 22.5 hours, and after the reaction, concentrating under reduced pressure to remove the solvent, then washing with ether, dissolving in dichloromethane for recrystallization and purification, to obtain dicarboxyl nano-alumina;

[0043] (4) adding 3-dimethylaminopropanol and dicarboxyl nano-alumina to N,N-dimethylformamide solvent, stirring and mixing, and then continuing to add p-toluenesulfonic acid catalyst, wherein the mass ratio of 3-dimethylaminopropanol, dicarboxyl nano-alumina, and p-toluenesulfonic acid catalyst is 2.2:1:0.05, reacting at 87.5° C. for 11.5 hours, and then performing reduced pressure distillation after the reaction, filtering and drying to obtain tertiary amine nano-alumina;

[0044] (5) adding tertiary amine nano-alumina and chloroacetic acid to an acetone solvent, wherein the mass ratio of tertiary amine nano-alumina to chloroacetic acid is 1:2.35, stirring and mixing, adding 2.7 mL of 11.5% sodium hydroxide solution, reacting at 100° C. for 3 h, filtering and drying after the reaction, to obtain diquaternized nano-alumina;

[0045] (6) Add diquaternized nano-alumina and polyether-modified trisiloxane to N,N-dimethylformamide solvent, stir and dissolve, and continue to add dibutyltin dilaurate catalyst, wherein the mass ratio of diquaternized nano-alumina, polyether-modified trisiloxane and dibutyltin dilaurate catalyst is 1.5:1:0.06, react at 102.5°C for 8h, and then perform vacuum distillation, filter and dry to obtain a gemini quaternary ammonium polyether surfactant for oil displacement agent.

[0046] Example 4

[0047] (1) adding allyloxy polyoxyethylene ether to N,N-dimethylformamide solvent, stirring and dissolving, continuously adding platinum catalyst thereto, heating to 70°C for activation for 0.4h, then continuously heating to 100°C, and adding heptamethyl trisiloxane thereto dropwise at a constant pressure, wherein the mass ratio of allyloxy polyoxyethylene ether, platinum catalyst, and heptamethyl trisiloxane is 1.1:1:0.01, reacting at 105°C for 4h after the addition, and removing low-boiling substances by reduced pressure distillation after the addition, to obtain polyether-modified trisiloxane;

[0048] (2) Ultrasonic dispersion of nano-alumina in 30 mL of anhydrous ethanol and 10 mL of a mixed solvent, after uniform mixing, adding γ-aminopropyltriethoxysilane, wherein the mass ratio of nano-alumina to γ-aminopropyltriethoxysilane is 1:1.2, reacting at 75° C. for 8 h, after the reaction, centrifuging to obtain a solid, washing the solid with deionized water for 3 times, and drying in an oven at 70° C. for 10 min to obtain amino-modified nano-alumina;

[0049] (3) adding amino nano-alumina and benzophenone tetracarboxylic anhydride to a toluene solvent, stirring evenly, and continuing to add a pyridine catalyst, wherein the amino nano-alumina, benzophenone tetracarboxylic anhydride, and pyridine catalyst are 1.8:1:0.04, heating to 95° C. and stirring to react for 30 hours, and after the reaction, concentrating under reduced pressure to remove the solvent, then washing with ether, dissolving in dichloromethane for recrystallization and purification, to obtain dicarboxyl nano-alumina;

[0050] (4) adding 3-dimethylaminopropanol and dicarboxyl nano-alumina to N,N-dimethylformamide solvent, stirring and mixing, and then continuing to add p-toluenesulfonic acid catalyst, wherein the mass ratio of 3-dimethylaminopropanol, dicarboxyl nano-alumina, and p-toluenesulfonic acid catalyst is 2.3:1:0.06, reacting at 95° C. for 15 hours, and then performing reduced pressure distillation after the reaction, filtering and drying to obtain tertiary amine nano-alumina;

[0051] (5) adding tertiary amine nano-alumina and chloroacetic acid to an acetone solvent, wherein the mass ratio of tertiary amine nano-alumina to chloroacetic acid is 1:2.35, stirring and mixing, adding 2.8 mL of 11.5% sodium hydroxide solution, reacting at 100° C. for 3 h, filtering and drying after the reaction, to obtain diquaternized nano-alumina;

[0052] (6) Add diquaternized nano-alumina and polyether-modified trisiloxane to N,N-dimethylformamide solvent, stir and dissolve, and continue to add dibutyltin dilaurate catalyst, wherein the mass ratio of diquaternized nano-alumina, polyether-modified trisiloxane and dibutyltin dilaurate catalyst is 1.5:1:0.06, react at 102.5°C for 8h, and then perform vacuum distillation, filter and dry to obtain a gemini quaternary ammonium polyether surfactant for oil displacement agent.

[0053] Example 5

[0054] (1) adding allyloxy polyoxyethylene ether to N,N-dimethylformamide solvent, stirring and dissolving, continuously adding platinum catalyst thereto, heating to 95° C. for activation for 1 hour, then continuously heating to 110° C., and adding heptamethyl trisiloxane thereto dropwise at a constant pressure, wherein the mass ratio of allyloxy polyoxyethylene ether, platinum catalyst, and heptamethyl trisiloxane is 1.3:1:0.03, reacting at 115° C. for 7 hours after the addition is completed, and then removing low-boiling substances by reduced pressure distillation to obtain polyether-modified trisiloxane;

[0055] (2) Ultrasonic dispersion of nano-alumina in a mixed solvent of 30 mL of anhydrous ethanol and 10 mL of deionized water, after uniform mixing, adding γ-aminopropyltriethoxysilane, wherein the mass ratio of nano-alumina to γ-aminopropyltriethoxysilane is 1:1.5, reacting at 90° C. for 15 h, after the reaction, centrifuging to obtain a solid, washing the solid with deionized water for 3 times, and drying in an oven at 70° C. for 10 min to obtain amino-modified nano-alumina;

[0056] (3) adding amino nano-alumina and benzophenone tetracarboxylic anhydride to a toluene solvent, stirring evenly, and continuing to add a pyridine catalyst, wherein the amino nano-alumina, benzophenone tetracarboxylic anhydride, and pyridine catalyst are 1.55:1:0.03, heating to 85° C. and stirring to react for 22.5 hours, and after the reaction, concentrating under reduced pressure to remove the solvent, then washing with ether, dissolving in dichloromethane for recrystallization and purification, to obtain dicarboxyl nano-alumina;

[0057] (4) adding 3-dimethylaminopropanol and dicarboxyl nano-alumina to N,N-dimethylformamide solvent, stirring and mixing, and then continuing to add p-toluenesulfonic acid catalyst, wherein the mass ratio of 3-dimethylaminopropanol, dicarboxyl nano-alumina, and p-toluenesulfonic acid catalyst is 2.2:1:0.05, reacting at 87.5° C. for 11.5 hours, and then performing reduced pressure distillation after the reaction, filtering and drying to obtain tertiary amine nano-alumina;

[0058] (5) adding tertiary amine nano-alumina and chloroacetic acid to an acetone solvent, wherein the mass ratio of tertiary amine nano-alumina to chloroacetic acid is 1:2.1, stirring and mixing, adding 2.5 mL of 8% sodium hydroxide solution, reacting at 80° C. for 2 h, filtering and drying after the reaction, to obtain diquaternized nano-alumina;

[0059] (6) Add diquaternized nano-alumina and polyether-modified trisiloxane to N,N-dimethylformamide solvent, stir and dissolve, and continue to add dibutyltin dilaurate catalyst, wherein the mass ratio of diquaternized nano-alumina, polyether-modified trisiloxane and dibutyltin dilaurate catalyst is 1.3:1:0.05, react at 95°C for 6h, and then perform vacuum distillation, filter and dry to obtain a gemini quaternary ammonium polyether surfactant for oil displacement agent.

[0060] Comparative Example 1

[0061] The difference between this comparative example and Example 2 is that no diquaternized nano-alumina is added, and the remaining steps and raw materials are the same as those of Example 2.

[0062] Add allyloxy polyoxyethylene ether to N,N-dimethylformamide solvent, stir to dissolve, continue to add platinum catalyst, heat to 95°C for activation for 1 hour, then continue to heat to 110°C, and add heptamethyltrisiloxane dropwise at constant pressure, wherein the mass ratio of allyloxy polyoxyethylene ether, platinum catalyst and heptamethyltrisiloxane is 1.3:1:0.03. After the addition is completed, react at 115°C for 7 hours, and then remove low-boiling substances by reduced pressure distillation to obtain polyether-modified trisiloxane.

[0063] Comparative Example 2

[0064] The difference between this comparative example and Example 2 is that no nano-alumina is added, and the remaining steps and raw materials are the same as Example 2.

[0065] (1) adding allyloxy polyoxyethylene ether to N,N-dimethylformamide solvent, stirring and dissolving, continuously adding platinum catalyst thereto, heating to 95° C. for activation for 1 hour, then continuously heating to 110° C., and adding heptamethyl trisiloxane thereto dropwise at a constant pressure, wherein the mass ratio of allyloxy polyoxyethylene ether, platinum catalyst, and heptamethyl trisiloxane is 1.3:1:0.03, reacting at 115° C. for 7 hours after the addition is completed, and then removing low-boiling substances by reduced pressure distillation to obtain polyether-modified trisiloxane;

[0066] (2) γ-aminopropyl triethoxysilane and benzophenone tetracarboxylic acid dianhydride are stirred evenly, and pyridine catalyst is added thereto, wherein the ratio of γ-aminopropyl triethoxysilane, benzophenone tetracarboxylic acid dianhydride and pyridine catalyst is 1.8:1:0.04, and the temperature is raised to 95° C. and stirred for reaction for 30 hours. After the reaction, the solvent is removed by concentration under reduced pressure, and then washed with ether, dissolved in dichloromethane and recrystallized and purified to obtain a dicarboxyl monomer;

[0067] (4) adding 3-dimethylaminopropanol and dicarboxyl monomer to N,N-dimethylformamide solvent, stirring and mixing, and then continuing to add p-toluenesulfonic acid catalyst thereto, wherein the mass ratio of 3-dimethylaminopropanol, dicarboxyl monomer, and p-toluenesulfonic acid catalyst is 2.3:1:0.06, reacting at 95° C. for 15 hours, and then performing reduced pressure distillation after the reaction, filtering and drying to obtain a tertiary amine monomer;

[0068] (5) adding a tertiary amine monomer and chloroacetic acid to an acetone solvent, wherein the mass ratio of the tertiary amine monomer to the chloroacetic acid is 1:2.6, stirring and mixing, adding 2.6 mL of a 15% sodium hydroxide solution, reacting at 120° C. for 4 h, filtering and drying after the reaction, to obtain a diquaternary ammonium monomer;

[0069] (6) Add diquaternized nano-alumina and polyether-modified trisiloxane to N,N-dimethylformamide solvent, stir to dissolve, and continue to add dibutyltin dilaurate catalyst, wherein the mass ratio of diquaternized nano-alumina, polyether-modified trisiloxane and dibutyltin dilaurate catalyst is 1.7:1:0.07, react at 110° C. for 10 h, and then perform reduced pressure distillation, filter and dry to obtain a gemini quaternary ammonium polyether surfactant for oil displacement agent.

[0070] Comparative Example 3

[0071] The difference between this comparative example and Example 2 is that the diquaternized nano-alumina is replaced by commercially available nano-alumina, and the remaining steps and raw materials are the same as those of Example 2.

[0072] (1) adding allyloxy polyoxyethylene ether to N,N-dimethylformamide solvent, stirring and dissolving, continuously adding platinum catalyst thereto, heating to 95° C. for activation for 1 hour, then continuously heating to 110° C., and adding heptamethyl trisiloxane thereto dropwise at a constant pressure, wherein the mass ratio of allyloxy polyoxyethylene ether, platinum catalyst, and heptamethyl trisiloxane is 1.3:1:0.03, reacting at 115° C. for 7 hours after the addition is completed, and then removing low-boiling substances by reduced pressure distillation to obtain polyether-modified trisiloxane;

[0073] (2) Add commercially available nano-alumina and polyether-modified trisiloxane to N,N-dimethylformamide solvent, stir and dissolve, and continue to add dibutyltin dilaurate catalyst, wherein the mass ratio of diquaternized nano-alumina, polyether-modified trisiloxane and dibutyltin dilaurate catalyst is 1.7:1:0.07, react at 110°C for 10 hours, and then perform vacuum distillation, filter and dry to obtain a gemini quaternary ammonium salt polyether surfactant for oil displacement agent.

[0074] The performance of the gemini quaternary ammonium salt polyether surfactant used for oil displacement agent prepared in Examples 1 to 5 and Comparative Examples 1 to 3 is now tested;

[0075] The formula of the oil displacement agent is: 10% of gemini quaternary ammonium salt polyether surfactant, 30% of ethanol, 2% of sodium sulfite and 58% of deionized water.

[0076] The oil displacement agent solution was prepared by using simulated injection water, and then it was evacuated for 2-3 hours to remove the dissolved gas and eliminate the adverse effect of dissolved gas on the imbibition oil recovery effect. The core saturated with oil was wiped of the floating oil on the surface and placed in an imbibition bottle with oil displacement agent for imbibition oil recovery. The oil discharge from the core was recorded, and the imbibition recovery rate and imbibition rate were calculated. The interfacial tension of the oil displacement system was measured by a spinning drop interfacial tension meter. The results are shown in Table 1 below:

[0077] Table 1 Performance test results

[0078] project Recovery rate (%) Oil-water interfacial tension mN / m Imbibition rate (% / h) Example 1 95.2 0.010 12.56 Example 2 97.5 0.008 13.65 Example 3 96.3 0.009 13.12 Example 4 95.1 0.011 12.89 Example 5 94.8 0.012 12.88 Comparative Example 1 76.9 0.025 8.65 Comparative Example 2 80.8 0.021 9.52 Comparative Example 3 85.6 0.018 9.81

[0079] As can be seen from Table 1, compared with Comparative Examples 1 to 3, Examples 1 to 5 of the present invention have better recovery rates and higher imbibition rates, and by adding the gemini quaternary ammonium salt polyether surfactant, the oil-water interfacial tension can be effectively reduced and the recovery rate can be improved.

Claims

1. A method for preparing a gemini quaternary ammonium salt polyether surfactant for an oil displacement agent, characterized in that: The following steps are involved: Step 1, reacting allyloxy polyoxyethylene ether and heptamethyl trisiloxane under the action of a platinum catalyst to obtain polyether-modified trisiloxane; Step 2, reacting nano-alumina with γ-aminopropyltriethoxysilane to obtain amino-treated nano-alumina; Step 3, reacting the amino nano-alumina and benzophenone tetracarboxylic dianhydride under the action of pyridine catalyst to obtain dicarboxyl nano-alumina; Step 4, reacting 3-dimethylaminopropanol and dicarboxyl nano-alumina under the action of p-toluenesulfonic acid catalyst to obtain tertiary amine nano-alumina; Step 5, reacting tertiary amine-based nano-alumina with chloroacetic acid to obtain diquaternized nano-alumina; Step 6: reacting the diquaternized nano-alumina and the polyether-modified trisiloxane under the action of dibutyltin dilaurate catalyst to obtain a gemini quaternary ammonium salt polyether surfactant.

2. The method for preparing a gemini quaternary ammonium salt polyether surfactant for oil displacement agent as claimed in claim 1, characterized in that, The step 1 is specifically as follows: adding allyloxy polyoxyethylene ether to N,N-dimethylformamide solvent, adding platinum catalyst after stirring to dissolve, heating to 70-95° C. for activation for 0.4-1h, then continuing to heat to 100-110° C., and then dripping heptamethyl trisiloxane at a constant pressure, reacting at 105-115° C. for 4-7h after the dripping, and removing low-boiling substances by reduced pressure distillation to obtain polyether-modified trisiloxane; wherein the mass ratio of allyloxy polyoxyethylene ether, platinum catalyst, and heptamethyl trisiloxane is 1.1-1.3:1:0.01-0.

03.

3. The method for preparing a gemini quaternary ammonium salt polyether surfactant for oil-displacing agent as claimed in claim 1, characterized in that, The step 2 is specifically as follows: ultrasonically dispersing nano-alumina into a mixed solvent of anhydrous ethanol and deionized water, adding γ-aminopropyltriethoxysilane after mixing evenly, reacting at 75-90° C. for 8-15 hours, then centrifuging, washing and drying to obtain amino-treated nano-alumina; wherein the mass ratio of nano-alumina to γ-aminopropyltriethoxysilane is 1:1.2-1.

5.

4. The method for preparing a gemini quaternary ammonium salt polyether surfactant for oil-displacing agent as claimed in claim 1, characterized in that, The step 3 is specifically as follows: adding amino nano-alumina and benzophenone tetracarboxylic anhydride to a toluene solvent, stirring evenly and then adding a pyridine catalyst, heating to 75-95° C. and stirring for reaction for 15-30 hours, and concentrating under reduced pressure after the reaction to remove the solvent, then washing with ether, dissolving in dichloromethane for recrystallization and purification to obtain dicarboxyl nano-alumina; wherein the mass ratio of amino nano-alumina, benzophenone tetracarboxylic anhydride, and pyridine catalyst is 1.3-1.8:1:0.02-0.

04.

5. The method for preparing a gemini quaternary ammonium salt polyether surfactant for oil-displacing agent as claimed in claim 1, characterized in that, The step 4 is specifically as follows: adding 3-dimethylaminopropanol and dicarboxyl nano-alumina to N,N-dimethylformamide solvent, stirring and mixing, adding p-toluenesulfonic acid catalyst, reacting at 80-95° C. for 8-15 hours, and then performing reduced pressure distillation, filtering and drying to obtain tertiary amine nano-alumina; wherein the mass ratio of 3-dimethylaminopropanol, dicarboxyl nano-alumina and p-toluenesulfonic acid catalyst is 2.1-2.3:1:0.04-0.

06.

6. The method for preparing a gemini quaternary ammonium salt polyether surfactant for oil-displacing agent as claimed in claim 1, characterized in that, The step 5 is specifically as follows: adding tertiary amine nano-alumina and chloroacetic acid to an acetone solvent, stirring and mixing, adding a sodium hydroxide solution with a mass fraction of 8 to 15%, reacting at 80 to 120° C. for 2 to 4 hours, filtering and drying after the reaction, to obtain diquaternized nano-alumina; wherein the mass ratio of tertiary amine nano-alumina to chloroacetic acid is 1:2.1 to 2.

6.

7. The method for preparing a gemini quaternary ammonium salt polyether surfactant for oil-displacing agent as claimed in claim 1, characterized in that, The step 6 is specifically as follows: adding diquaternized nano alumina and polyether modified trisiloxane to N,N-dimethylformamide solvent, stirring and dissolving, adding dibutyltin dilaurate catalyst, reacting at 95-110° C. for 6-10 hours, and then performing reduced pressure distillation, filtering and drying to obtain a gemini quaternary ammonium polyether surfactant for oil displacement agent; wherein the mass ratio of diquaternized nano alumina, polyether modified trisiloxane and dibutyltin dilaurate catalyst is 1.3-1.7:1:0.05-0.

07.

8. The gemini quaternary ammonium salt polyether surfactant for oil displacing agent prepared by the preparation method of the gemini quaternary ammonium salt polyether surfactant for oil displacing agent as claimed in claim 1.