CN111088012A

CN111088012A - Composite surfactant for improving crude oil recovery efficiency and preparation method and application thereof

Info

Publication number: CN111088012A
Application number: CN201811235107.9A
Authority: CN
Inventors: 吴欣悦; 张卫东; 沙鸥; 李应成; 鲍新宁
Original assignee: China Petroleum and Chemical Corp; Sinopec Shanghai Research Institute of Petrochemical Technology
Current assignee: China Petroleum and Chemical Corp; Sinopec Shanghai Research Institute of Petrochemical Technology
Priority date: 2018-10-23
Filing date: 2018-10-23
Publication date: 2020-05-01
Anticipated expiration: 2038-10-23
Also published as: CN111088012B

Abstract

The invention relates to a composite surfactant for improving the recovery ratio of crude oil, a preparation method and application thereof. Mainly solves the problem that the compound oil displacement agent in the prior art is difficult to effectively improve the recovery ratio under the conditions of high temperature, high salinity and medium high permeability oil reservoir. The composite surfactant for improving the crude oil recovery rate comprises a hydroxyalkyl quaternary ammonium salt surfactant shown in a formula (I) and a fatty amide polyether acid salt surfactant shown in a formula (II), wherein the mass ratio of the hydroxyalkyl quaternary ammonium salt surfactant to the fatty amide polyether acid salt surfactant is (100-1) to (100-1); in the formula R₁Is C₁～C₂₀Alkyl of R₂、R₃Is C₁～C₄The fatty group of (a); r₄Is C₈～C₁₆Aliphatic radical of (2), R₅Is H or C₁～C₄The fat base technical proposal of the method better solves the problem and can be used forIn the production of tertiary oil recovery in oil fields.

Description

Composite surfactant for improving crude oil recovery efficiency and preparation method and application thereof

Technical Field

The invention relates to a composite surfactant capable of improving the recovery ratio of crude oil, and a preparation method and application thereof.

Background

Petroleum is an important non-renewable strategic resource, and the demand for petroleum in the world is increasing nowadays. The conventional oil extraction method can only extract one third of the geological reserve of crude oil generally, at present, most oil reservoirs enter the later stage of high-water-content development, the proportion of the oil reservoirs which are difficult to extract, such as medium-high-temperature high-salinity, high-water-content high-extraction, low-permeability and the like in the residual reserve is increased year by year, and the development is very difficult by using the prior art, so that a new extraction technology needs to be developed urgently, the recovery ratio of old oil fields is greatly improved, the utilization ratio of detected resources is greatly improved, and the requirements of economic development and national safety are met.

Surfactant flooding is one of the current major research directions for enhanced oil recovery from tertiary recovery. The surfactant can effectively reduce the oil-water interfacial tension, change the oil reservoir wettability, solubilize the crude oil and reduce the crude oil viscosity, and plays an important role in tertiary oil recovery. The anion and cation compound surfactant is used as a new surfactant mixed system and shows special performance in many fields. The strong electrostatic interaction exists between the cationic surfactant and the anionic surfactant, so that the complex system has lower critical micelle concentration, limited occupied area and better interfacial activity, has good capability of forming microemulsion, and is beneficial to obtaining and stabilizing ultra-low interfacial tension. Meanwhile, the formation of the anion-cation pairs greatly enhances the adsorption resistance and calcium and magnesium ion resistance of the anion-cation compound surfactant, and improves the oil displacement effect of the system in a high-temperature and high-salinity oil reservoir.

At present, the anion-cation compound surfactant is less applied in the third mining. Patent CN103773347A reports a composite surfactant composition composed of alkyl polyoxyethylene ether anionic surfactant containing aromatic rings and tetraalkyl quaternary ammonium salt, and the composition has good interfacial properties for the oil field in south of Henan; korea xia et al (journal of physical chemistry, 2012,28(1), 146-. These efforts have used tetraalkyl/aryl quaternary ammonium cationic surfactants, which have poor solubility in hypersaline water, limiting the use of these formulations in high salt reservoirs. Compared with tetraalkyl quaternary ammonium salt, the introduction of the hydroxyl optimizes the solubility of the surfactant in water, and is beneficial to the blending and use of the oil displacement agent on site. Meanwhile, the polyether acid salt containing fatty amide is used as an anion, and can be applied to high-temperature and high-salinity oil reservoirs under the alkali-free condition, so that the damage to the stratum is reduced.

Disclosure of Invention

The invention aims to solve the technical problems that the composite oil displacement agent in the prior art is poor in temperature resistance and salt resistance, high in use concentration and low in oil displacement efficiency, and provides a temperature-resistant and salt-resistant composite surfactant capable of greatly improving the recovery ratio under the conditions of high-temperature, high-salt and high-permeability oil reservoirs. The composite surfactant can form 10 with crude oil under the conditions of wide concentration range, high temperature, high salinity and high permeability oil reservoir^-2～10^-4mN/m low interfacial tension, thereby improving the oil displacement efficiency of the oil displacement agent.

The invention also provides a preparation method of the composite surfactant for improving the recovery ratio, which is corresponding to one of the technical problems.

The invention also provides the application of the composite surfactant for improving the recovery ratio in oil field oil recovery corresponding to one of the technical problems.

In order to solve one of the above technical problems, the technical scheme adopted by the invention is as follows: the composite surfactant for improving the crude oil recovery rate comprises a hydroxyalkyl quaternary ammonium salt surfactant and a fatty amide polyether acid salt surfactant, wherein the mass ratio of the hydroxyalkyl quaternary ammonium salt surfactant to the fatty amide polyether acid salt surfactant is (100-1) to (100-1);

wherein the molecular general formula of the hydroxyalkyl quaternary ammonium salt surfactant is shown as the formula (I):

the molecular general formula of the fatty amide polyether acid salt surfactant is shown as a formula (II):

in the formula, R₁Is C₁～C₂₀Alkyl of R₂、R₃Is C₁～C₄P is CH₂The number of chain segments is any one integer selected from 1 to 6, X^-Is at least one of an anionic or anionic group; r₄Is C₈～C₁₆Aliphatic radical of (2), R₅Is H or C₁～C₄The fatty group of (a); n is the sum of ethoxy groups, and n is 5-8; m is the addition number of the propoxy groups, and m is 0-10; q is CH₂The number of chain segments is selected from any integer of 1-6; y is selected from-COO^-、-SO₃ ^-At least one of; m is selected from monovalent cations or cationic groups.

In the above technical scheme, R₁Preferably C₁～C₂₀Alkyl of R₂、R₃Preferably C₁～C₄Further preferably R₁Preferably C₁₂、C₁₄、C₁₆、C₁₈Alkyl of R₂、R₃Methyl and ethyl are preferred.

In the above technical solution, p is preferably any one integer of 1 to 6, and more preferably 1, 2, or 3.

In the above technical scheme, R₄Preferably C₈～C₁₆Further preferably C₈、C₉、C₁₂、C₁₅The alkyl of (A), the R₅Is H or C₁～C₄The aliphatic group of (3) is more preferably H, methyl or ethyl.

In the technical proposal, the device comprises a base,said X^-Is preferably selected from-Cl^-、-Br^-、-I^—At least one of (1).

In the above technical solution, M is preferably selected from an ammonium ion or a monovalent metal ion.

In the technical scheme, the mass ratio of the fatty amide polyether acid salt surfactant to the hydroxyalkyl quaternary ammonium salt surfactant is preferably (10-1): 1, and more preferably (5-1): 1.

In the above technical solution, the composite surfactant preferably further comprises injected water; the total mineralization degree of the injected water is preferably 100000-200000 mg/L, and Ca is²⁺+Mg²⁺Preferably 0 to 7000 mg/L.

In the above technical solution, X is^—Is preferably-Cl^—。

In the technical scheme, m is preferably 0-5.

In order to solve the second technical problem, the invention adopts the technical scheme that: a method for preparing the surfactant complex for enhanced oil recovery according to any of the above technical means, which solves the technical problems, comprising the steps of:

according to the required proportion, the hydroxyalkyl quaternary ammonium salt surfactant, the fatty amide polyether acid salt surfactant and the injected water are mixed and stirred uniformly to obtain the composite surfactant.

In the above technical solution, the preparation method of the fatty amide polyether acid salt surfactant preferably includes the following steps:

(a) preparation of fatty amide polyoxyalkylene ether:

reacting the required fatty amide with ethylene oxide and/or propylene oxide in the presence of an alkaline catalyst at a reaction temperature of 85-160 ℃ and a pressure of less than 0.50MPa gauge pressure to obtain the fatty amide polyoxyethylene ether, wherein the dosage of the catalyst is 0.3-3 wt% of the mass of the fatty amide;

(b) preparation of fatty amide polyoxy alkylene etherate:

alkalizing the fatty amide polyoxyalkylene ether synthesized in the step (a) with sodium hydroxide at 45-75 ℃ for 2 hours, then reacting with a sulfonation reagent or a carboxylation reagent at 70-90 ℃ for 2-15 hours, and after the reaction is finished, acidifying, washing with water, and evaporating under reduced pressure to remove the solvent to obtain fatty amide polyoxyalkylene ether acid; wherein the solvent is selected from one of ethanol, isopropanol and benzene;

(c) and (c) carrying out a neutralization reaction on the fatty amide polyoxyalkene ether acid synthesized in the step (b) to obtain the fatty amide polyoxyalkene ether acid salt surfactant.

In the above technical solution, the preparation method of the hydroxyalkyl quaternary ammonium salt surfactant preferably comprises the following steps:

dissolving alkyl dimethylamine in a solvent, and adding potassium hydroxide to adjust the pH value to 9-10. Slowly adding halogenated fatty alcohol according to the proportion at the temperature of 60-80 ℃, and reacting for 10-16 hours. After the reaction is finished, evaporating the solvent to obtain the hydroxyalkyl quaternary ammonium salt surfactant; wherein the solvent is selected from one of ethanol and isopropanol.

In the technical scheme, the preferable range of the dosage of the fatty amide polyether carboxylate is 0.1-0.3 wt%, and the preferable range of the hydroxyalkyl quaternary ammonium salt surfactant is 0.02-0.15 wt%, based on the total mass percentage of the fatty amide polyether carboxylate surfactant, the hydroxyalkyl quaternary ammonium salt surfactant and the injected water.

In order to solve the third technical problem, the invention adopts the technical scheme that: the application of the composite surfactant for improving the recovery ratio of crude oil in any technical scheme solving the technical problem in the oil field recovery.

In the above technical solution, the application method can be used by those skilled in the art according to the prior art, for example, but not limited to, injecting the composite surfactant solution into an oil reservoir to contact with the underground crude oil, and displacing the underground crude oil; or be used together with other oil production agents.

According to the invention, the anion-nonionic and cation composite surfactant is adopted, and after the anion-nonionic and cation surfactants are compounded, electrostatic attraction exists between a hydrophilic group with negative charges in the anion-nonionic surfactant and a hydrophilic group with positive charges in the cation surfactant, so that the problems of loose arrangement of an interface film and the like of the traditional surfactant caused by electrostatic repulsion among the same charges can be solved, the interfacial activity of the compounded agent is enhanced, and the oil displacement efficiency is improved. Meanwhile, the interaction between the anions and cations also enhances the adsorption resistance and calcium and magnesium ion resistance of the composite surfactant, so that the composite surfactant has the possibility of being applied to high-salinity oil reservoirs.

The composite surfactant capable of improving the recovery efficiency can be used for the formation with the temperature of 90 ℃ and the degree of mineralization of 30 multiplied by 10⁴The dynamic interfacial tension between the oil displacement agent aqueous solution and the Jianghang crude oil is measured by using 0.1-0.3 wt% of fatty amide polyoxyethylene ether carboxylate and 0.02-0.15 wt% of hydroxyalkyl ammonium halide to form the composite surfactant oil displacement agent of mg/L Jianghang formation water and crude oil, and can reach 10^-3～10^-4The ultra-low interfacial tension of mN/m can be used for improving the recovery ratio of tertiary oil recovery, and a better technical effect is obtained.

The invention is further illustrated by the following examples.

Detailed Description

[ example 1 ]

(a) Preparation of cocoamide polyoxyethylene ether:

adding 260 g (1 mol) of octylphenol and 5 g of potassium hydroxide into a pressure reactor, heating to 80-90 ℃, starting a vacuum system, dehydrating for 1 hour under high vacuum, pumping nitrogen for 3 times, adjusting the reaction temperature of the system to 140 ℃, slowly introducing 268.4 g (6.1 mol) of ethylene oxide, and controlling the pressure to be less than or equal to 0.50 MPa. After the reaction is finished, the temperature is reduced to 90 ℃, low-boiling-point substances are removed in vacuum, and the cocoamide polyoxyethylene (n ═ 6) ether is obtained after neutralization and dehydration after cooling.

(b) Preparation of cocoamide polyoxyethylene ether carboxylate:

adding 80 g (2 mol) of the cocoamide polyoxyethylene (n-6) ether synthesized in the step (a), sodium hydroxide and 500 g of benzene into a reactor, reacting at 65 ℃ for 3 hours, adding 140 g (1.2 mol) of sodium chloroacetate, and heating to 85 ℃ for reacting for 6 hours. And after the reaction is finished, reducing the temperature to 65 ℃, carrying out acidification and water washing, and carrying out reduced pressure evaporation to remove the solvent to obtain the cocoamide polyoxyethylene ether carboxylic acid.

(c) And (c) mixing and uniformly stirring the cocoamide polyoxyethylene ether carboxylic acid synthesized in the step (b) with a proper amount of sodium hydroxide and water to obtain the cocoamide polyoxyethylene ether carboxylate with the pH value of 9-10 and the solid content of 30 wt%.

(d) 269 g (1 mol) of hexadecyl dimethyl tertiary amine and 800 g of ethanol are added into a reactor, and potassium hydroxide is added to adjust the pH value to 9-10. Slowly adding 102 g (1.1 mol) of 3-chloropropanol according to the mixture ratio at the temperature of 60-80 ℃, and reacting for 10-16 hours. After the reaction, the solvent was evaporated to obtain 360 g of hexadecyl dimethyl hydroxyethyl ammonium chloride with a yield of 96%.

(e) Mixing and stirring 0.1 wt% of sodium acetate of the cocoamide polyoxyethylene ether (n ═ 6) synthesized in the step (c), 0.03 wt% of hexadecyl dimethyl hydroxypropyl ammonium chloride synthesized in the step (d) and 99.87 wt% of Jianghan simulated water to obtain the oil-displacing composite surfactant. The interfacial tension between the composite surfactant and the Jianghan dehydrated crude oil at 90 ℃ was measured by a TX500 type rotary droplet interfacial tensiometer, produced by Texas university, USA, as shown in Table 1.

TABLE 1

[ example 2 ]

(a) Preparation of cocoamide polyoxyethylene ether:

adding 260 g (1 mol) of cocamide and 5 g of potassium hydroxide into a pressure reactor, heating to 80-90 ℃, starting a vacuum system, dehydrating for 1 hour under high vacuum, pumping nitrogen for 3 times, adjusting the reaction temperature of the system to 140 ℃, slowly introducing 224.4 g (5.1 mol) of ethylene oxide, and controlling the pressure to be less than or equal to 0.50 MPa. After the reaction is finished, the temperature is reduced to 90 ℃, low-boiling-point substances are removed in vacuum, and the cocoamide polyoxyethylene (n-5) ether is obtained after neutralization and dehydration after cooling.

(b) Preparation of cocoamidooxyethyl ether carboxylate:

adding 80 g (2 mol) of the cocoamide polyoxyethylene (n-5) ether synthesized in the step (a), sodium hydroxide and 500 g of benzene into a reactor, reacting at 65 ℃ for 3 hours, adding 140 g (1.2 mol) of sodium chloroacetate, and heating to 85 ℃ for reacting for 6 hours. And after the reaction is finished, reducing the temperature to 65 ℃, carrying out acidification and water washing, and carrying out reduced pressure evaporation to remove the solvent to obtain the cocoamide polyoxyethylene ether carboxylic acid.

(d) Adding 297 g (1 mol) of octadecyl dimethyl tertiary amine and 800 g of ethanol into a reactor, and adding potassium hydroxide to adjust the pH to 9-10. At the temperature of 60-80 ℃, 88 g (1.1 mol) of 2-chloroethanol is slowly added according to the mixture ratio, and the reaction lasts for 10-16 hours. After the reaction, the solvent was evaporated to obtain 342 g of octadecyl dimethyl hydroxyethyl ammonium chloride with a yield of 96%.

(e) Mixing and stirring 0.1 wt% of sodium acetate of the cocoamide polyoxyethylene ether (n ═ 5) synthesized in the step (c), 0.02 wt% of octadecyl dimethyl hydroxyethyl ammonium chloride synthesized in the step (d) and 99.88 wt% of Jianghan simulated water to obtain the oil-displacing composite surfactant. The interfacial tension between the composite surfactant and the Jianghan dehydrated crude oil at 90 ℃ was measured by a TX500 type rotary droplet interfacial tensiometer, produced by Texas university, USA, as shown in Table 2.

TABLE 2

[ example 3 ]

(a) Preparation of stearic acid amide polyoxyethylene ether:

adding 326 g (1 mol) of stearidonamide and 5 g of potassium hydroxide into a pressure reactor, heating to 80-90 ℃, starting a vacuum system, dehydrating for 1 hour under high vacuum, pumping nitrogen for 3 times, adjusting the reaction temperature of the system to 140 ℃, slowly introducing 356.4 g (8.1 mol) of ethylene oxide, and controlling the pressure to be less than or equal to 0.50 MPa. After the reaction is finished, the temperature is reduced to 90 ℃, low-boiling-point substances are removed in vacuum, and after cooling, neutralization and dehydration are carried out, thus obtaining the stearidonic acid amide polyoxyethylene (n-8) ether.

(b) Preparation of stearic acid amide polyoxyethylene ether carboxylate:

adding 80 g (2 mol) of stearidonic acid amide polyoxyethylene (n-8) ether synthesized in the step (a), sodium hydroxide and 600 g of benzene into a reactor, reacting at 65 ℃ for 3 hours, adding 140 g (1.2 mol) of sodium chloroacetate, and heating to 85 ℃ for reaction for 6 hours. And after the reaction is finished, reducing the temperature to 65 ℃, acidifying, washing with water, and evaporating under reduced pressure to remove the solvent to obtain the stearic acid amide polyoxyethylene ether carboxylic acid.

(c) And (c) uniformly mixing and stirring the stearic acid amide polyoxyethylene ether carboxylic acid synthesized in the step (b) with a proper amount of sodium hydroxide and water to obtain stearic acid amide polyoxyethylene ether carboxylate with the pH value of 9-10 and the solid content of 30 wt%.

(d) And (c) mixing and stirring 1.0 wt% of stearic acid amide polyoxyethylene ether (n ═ 8) sodium acetate synthesized in the step (c), 0.3 wt% of hexadecyl dimethyl hydroxypropyl ammonium chloride synthesized in the example 1 and 98.7 wt% of Jianghan simulated water to obtain the oil-displacing composite surfactant. The interfacial tension between the composite surfactant and the Jianghan dehydrated crude oil at 90 ℃ was measured by a TX500 type rotary droplet interfacial tensiometer, produced by Texas university, USA, as shown in Table 3.

TABLE 3

[ example 4 ]

(a) 241 g (1 mol) of tetradecyldimethyl tertiary amine and 800 g of ethanol are added into a reactor, and potassium hydroxide is added to adjust the pH to 9-10. At the temperature of 60-80 ℃, 88 g (1.1 mol) of 2-chloroethanol is slowly added according to the mixture ratio, and the reaction lasts for 10-16 hours. After the reaction, the solvent was distilled off to obtain 309 g of tetradecyldimethylhydroxyethylammonium chloride with a yield of 96%.

(b) Mixing and stirring 0.16 wt% of stearic acid amide polyoxyethylene ether (n ═ 8) sodium acetate synthesized in the embodiment 3, 0.08 wt% of tetradecyl dimethyl hydroxypropyl ammonium chloride synthesized in the step (a) and 99.76 wt% of Jianghan simulated water to obtain the oil-displacing composite surfactant. The interfacial tension between the composite surfactant and the Jianghan dehydrated crude oil at 90 ℃ was measured by a TX500 type rotary droplet interfacial tensiometer, produced by Texas university, USA, as shown in Table 4.

TABLE 4

[ example 5 ]

(a) Preparation of stearic acid amide polyoxyethylene ether:

adding 326 g (1 mol) of stearidonamide and 5 g of potassium hydroxide into a pressure reactor, heating to 80-90 ℃, starting a vacuum system, dehydrating for 1 hour under high vacuum, pumping nitrogen for 3 times, adjusting the reaction temperature of the system to 140 ℃, slowly introducing 268.4 g (6.1 mol) of ethylene oxide, and controlling the pressure to be less than or equal to 0.50 MPa. After the reaction is finished, the temperature is reduced to 90 ℃, low-boiling-point substances are removed in vacuum, and after cooling, neutralization and dehydration are carried out, thus obtaining the stearidonic acid amide polyoxyethylene (n ═ 6) ether.

(b) Preparation of stearic acid amide polyoxyethylene ether carboxylate:

adding 80 g (2 mol) of stearidonic acid amide polyoxyethylene (n-6) ether synthesized in the step (a), sodium hydroxide and 500 g of benzene into a reactor, reacting at 65 ℃ for 3 hours, adding 140 g (1.2 mol) of sodium chloroacetate, and heating to 85 ℃ for reaction for 6 hours. And after the reaction is finished, reducing the temperature to 65 ℃, acidifying, washing with water, and evaporating under reduced pressure to remove the solvent to obtain the stearic acid amide polyoxyethylene ether carboxylic acid.

(d) And (c) mixing and stirring 0.03 wt% of stearic acid amide polyoxyethylene ether (n ═ 6) sodium acetate synthesized in the step (c), 0.01 wt% of hexadecyl dimethyl hydroxypropyl ammonium chloride synthesized in the example 1 and 99.96 wt% of Jianghan simulated water to obtain the oil-displacing composite surfactant. The interfacial tension between the composite surfactant and the Jianghan dehydrated crude oil at 90 ℃ was measured by a TX500 type rotary droplet interfacial tensiometer, produced by Texas university, USA, as shown in Table 5.

TABLE 5

[ example 6 ]

(a) Preparation of stearic acid amide polyoxyethylene ether:

adding 326 g (1 mol) of stearidonamide and 5 g of potassium hydroxide into a pressure reactor, heating to 80-90 ℃, starting a vacuum system, dehydrating for 1 hour under high vacuum, pumping nitrogen for 3 times, adjusting the reaction temperature of the system to 140 ℃, and slowly introducing 179.8 g (3.1 mol) of propylene oxide; after the reaction of the propylene oxide is finished, 312.4 g (7.1 mol) of ethylene oxide is slowly introduced, and the pressure is controlled to be less than or equal to 0.50 MPa. After the reaction is finished, the temperature is reduced to 90 ℃, low-boiling-point substances are removed in vacuum, and after cooling, neutralization and dehydration are carried out, thus obtaining the stearidonic acid amide polyoxyethylene polyoxypropylene (n-7, m-3) ether.

(b) Preparation of stearic acid amide polyoxyethylene ether carboxylate:

adding 80 g (2 mol) of stearidonic acid amide polyoxyethylene polyoxypropylene (n-7, m-3) ether synthesized in the step (a), sodium hydroxide and 800 g of benzene into a reactor, reacting at 65 ℃ for 3 hours, adding 140 g (1.2 mol) of sodium chloroacetate, and heating to 85 ℃ for reaction for 6 hours. And after the reaction is finished, reducing the temperature to 65 ℃, acidifying, washing with water, and evaporating under reduced pressure to remove the solvent to obtain the stearic acid amide polyoxyethylene polyoxypropylene ether carboxylic acid.

(c) And (c) mixing the stearidonic acid amide polyoxyethylene polyoxypropylene ether carboxylic acid synthesized in the step (b) with a proper amount of sodium hydroxide and water, and uniformly stirring to obtain the stearidonic acid amide polyoxyethylene polyoxypropylene ether carboxylic acid salt with the pH value of 9-10 and the solid content of 30 wt%.

(d) Adding 297 g (1 mol) of hexadecyl diethyl tertiary amine and 800 g of ethanol into a reactor, and adding potassium hydroxide to adjust the pH to 9-10. Slowly adding 102 g (1.1 mol) of 3-chloropropanol according to the mixture ratio at the temperature of 60-80 ℃, and reacting for 10-16 hours. After the reaction, the solvent was distilled off to obtain 386 g of hexadecyldiethylhydroxyethylammonium chloride with a yield of 96%.

(d) And (3) mixing and stirring 0.06 wt% of stearic acid amide polyoxyethylene polyoxypropylene ether (n is 7, m is 3) sodium acetate synthesized in the step (c), 0.02 wt% of hexadecyl diethyl hydroxypropyl ammonium chloride synthesized in example 1 and 99.92 wt% of Jianghan simulated water to obtain the oil-displacing composite surfactant. The interfacial tension between the composite surfactant and the Jianghan dehydrated crude oil at 90 ℃ was measured by a TX500 type rotary droplet interfacial tensiometer, produced by Texas university, USA, as shown in Table 6.

TABLE 6

[ COMPARATIVE EXAMPLE 1 ]

Nonyl phenol polyoxyethylene ether (n ═ 5) sodium acetate 0.1 wt%, octadecyl dimethyl hydroxyethyl ammonium chloride 0.02 wt% and Jianghan simulated water 99.88 wt% are mixed and stirred to obtain the oil-displacing composite surfactant. The interfacial tension between the composite surfactant and the Jianghan dehydrated crude oil at 90 ℃ was measured by a TX500 type rotary droplet interfacial tensiometer, produced by Texas university, USA, as shown in Table 7.

TABLE 7

[ COMPARATIVE EXAMPLE 2 ]

Stearic acid amide polyoxyethylene polyoxypropylene ether (n is 7, m is 3) sodium acetate 0.06 wt%, hexadecyl trimethyl ammonium chloride 0.02 wt% and Jianghan simulated water 99.92 wt% are mixed and stirred to obtain the oil displacement composite surfactant. The interfacial tension between the composite surfactant and the Jianghan dehydrated crude oil at 90 ℃ was measured by a TX500 type rotary droplet interfacial tensiometer, produced by Texas university, USA, as shown in Table 8.

TABLE 8

Claims

1. The composite surfactant for improving the crude oil recovery rate comprises a hydroxyalkyl quaternary ammonium salt surfactant and a fatty amide polyether acid salt surfactant, wherein the mass ratio of the hydroxyalkyl quaternary ammonium salt surfactant to the fatty amide polyether acid salt surfactant is (100-1) to (100-1);

in the formula, R₁Is C₁～C₂₀Alkyl of R₂、R₃Is C₁～C₄P is CH₂The number of chain segments is any one integer selected from 1 to 6, X^—Is an anionic or anionic group; r₄Is C₈～C₁₆Aliphatic radical of (2), R₅Is H or C₁～C₄The fatty group of (a); n is the sum of ethoxy groups, and n is 5-8; m is the addition number of the propoxy groups, and m is 0-10; q is CH₂The number of chain segments is selected from any integer of 1-6; y is selected from-COO^—、-SO₃ ^—At least one of; m is selected from monovalent cations or cationic groups.

2. The enhanced oil recovery composite surfactant of claim 1, wherein R is₁Is C₁₂、C₁₄、C₁₆、C₁₈Alkyl of R₂、R₃Are methyl and ethyl.

3. The enhanced oil recovery composite surfactant according to claim 1, wherein p is 1, 2, or 3.

4. The enhanced oil recovery composite surfactant of claim 1, wherein R is₄Is C₈、C₉、C₁₂、C₁₅Alkyl of R₅H, methyl and ethyl.

5. The enhanced oil recovery composite surfactant according to claim 1, wherein m is 0-5.

6. The composite surfactant for improving the recovery efficiency of crude oil according to claim 1, wherein the mass ratio of the fatty amide polyether acid salt surfactant to the hydroxyalkyl quaternary ammonium salt surfactant is (10-1): 1, and more preferably (5-1): 1.

7. The enhanced oil recovery composite surfactant of claim 1, further comprising injection water.

8. The enhanced oil recovery composite surfactant according to claim 7, wherein the total mineralization of injected water is 300000mg/L, Ca²⁺+Mg²⁺Is 0 to 7000 mg/L.

9. A method for preparing the surfactant complex for enhanced oil recovery according to any one of claims 1 to 8, comprising the steps of:

10. Use of the complex surfactant for enhanced oil recovery according to any one of claims 1 to 7 in oil recovery in an oil field.