Surfactant as well as preparation method and application thereof

Abstract

The invention relates to the field of oilfield development, in particular to a surfactant as well as a preparation method and application thereof. Wherein the structural formula of the surface active agent is # imgabs0 #; wherein R is selected from straight chain or branched chain alkyl, n is an integer of 1-8, and m is an integer of 1-10. According to the surfactant provided by the invention, the solubility of traditional long-chain fatty amido betaine is improved, the liquid preparation difficulty during application and construction of an oil field can be reduced, and the surfactant is more favorable for stripping crude oil in a stratum and improving the plugging capacity on a high-water-seepage flow channel. When the surfactant provided by the invention is applied to oil displacement of an oil field, the oil displacement efficiency can be improved by more than 18% compared with that of water displacement.

Description

Technical Field

[0001] The invention relates to the field of oil field development, and in particular to a surfactant and a preparation method and application thereof. Background Art

[0002] Surfactant flooding technology is a new type of oilfield recovery technology that has gradually emerged in recent years. Its working principle is that after the surfactant for flooding enters the reservoir, it spontaneously emulsifies in the high permeability water flow channel to form a W / O emulsion, and uses the Jamin effect of large-size emulsion droplets and high emulsion viscosity to achieve the blocking of high permeability permeable water flow channels to achieve the purpose of "adjustment", and uses high interfacial activity characteristics to improve oil washing efficiency to achieve the purpose of "displacement". The significant characteristics of surfactant flooding agents are that the higher the water content, the greater the emulsion viscosity, the stronger the ability to block high permeability channels with high water content, and it has good flooding selectivity, and can achieve the effect of "adjustment + displacement" in one system. The ground injection process is simple and low cost, and it has broad application prospects.

[0003] Although the currently known surfactant displacement technology has shown good application effects, it still has certain limitations. Zhang Yao et al. disclosed a block polyether surfactant displacement system in the article "Study on Reservoir Adaptability and Oil Displacement Efficiency of Block Polyether Surfactant Displacement System". In 2017, it was applied on site in the Zhou 16 well area of ​​Jianghan Oilfield. During the peak period, the single well production increased from 3t / d to 8.43t / d, and the comprehensive water content decreased from 93.18% to 86.32%, with significant effects of reducing water and increasing oil. However, the evaluation results show that it only has a good displacement effect on reservoirs with a permeability range of 3.2-10.9, and the displacement effect on reservoirs with a range greater than 35.6 is greatly reduced.

[0004] Wang Yongmei et al. disclosed in the article "Research on Surfactant Flooding and Its Application in Wenliu Oilfield" a flooding system with an anion-non-surfactant as the main component and a composite anion as the auxiliary component. In 2019, it was applied on-site in Wen 16 East Quick of Wenliu Oilfield. The single-well production increased from 6.2t / d to 8.4t / d, and the water content decreased from 80.6% to 72.4%. However, it is a compound of multiple systems, which is easy to be chromatographically separated in the reservoir, and needs to be used together with a viscosity reducer. The system is complex and the cost is high.

[0005] CN202110599274 discloses a salt-resistant anionic and cationic surfactant composition containing polyether segments for flooding. The anionic and cationic surfactant composition is prepared by using the same precursor to prepare structurally similar anionic and cationic surfactants. Under a concentration of 0.1wt%, in the field formation water with a mineralization of 250,000 mg / L and a calcium and magnesium ion content of 2000 mg / L, after aging at 120°C for 72h, the composition can form a 10% bond with underground crude oil. -3~10 - 4 The ultra-low interfacial tension of mN / m can increase the recovery rate by more than 15%. However, since there is a cationic surfactant in the formula, and the surface of sandstone reservoirs generally has negative points, it will cause a large amount of adsorption loss of the cationic surfactant, thus affecting the overall performance of the composition. Summary of the invention

[0006] The purpose of the present invention is to overcome the problems of poor viscosity increasing effect, low interfacial activity and weak emulsification ability of surfactants used for flooding in the prior art, and to provide a surfactant and a preparation method and application thereof.

[0007] In order to achieve the above object, the first aspect of the present invention provides a surfactant, wherein the structural formula of the surfactant is:

[0008] Wherein, R is selected from a straight chain or branched chain alkyl group, n is an integer of 1-8, and m is an integer of 1-10.

[0009] A second aspect of the present invention provides a method for preparing a surfactant, wherein the method comprises the following steps: (1) subjecting monounsaturated fatty acids to sulfation reaction with concentrated sulfuric acid to obtain sulfated fatty acids; (2) contacting the sulfated fatty acid with hydrochloric acid to carry out a hydrolysis reaction to obtain monohydroxystearic acid; (3) Under the action of catalyst I, the monohydroxystearic acid and ethylene oxide are polymerized to obtain polyoxyethylene ether stearic acid; (4) Under the action of catalyst II, the polyoxyethylene ether stearic acid and N,N-dimethyl-1,3-propylenediamine are subjected to acylation reaction to obtain polyoxyethylene ether fatty acid amide propyl dimethylamine; (5) In the presence of a reaction solvent, the polyoxyethylene ether fatty acid amide propyl dimethylamine is subjected to an alkylation reaction with sodium 3-chloro-2-hydroxypropanesulfonate to obtain the surfactant.

[0010] The third aspect of the present invention provides a use of the surfactant described in the first aspect of the present invention or the surfactant prepared according to the method described in the second aspect of the present invention in oil field recovery.

[0011] Through the above technical solution, the beneficial technical effects achieved by the present invention are as follows: 1) The surfactant provided by the present invention increases the solubility of traditional long-chain fatty amide betaine, which can reduce the difficulty of liquid preparation during oil field application construction; 2) The surfactant provided by the present invention increases the ability of spontaneously emulsifying crude oil, and can achieve oil-water emulsification under small amplitude or no disturbance, which is more conducive to stripping formation crude oil and improving the ability to block high-permeability water flow channels; 3) The surfactant provided by the present invention is conducive to the formation of worm-like micelles, which can increase the viscosity of the aqueous solution, reduce the oil-water interfacial tension to below 0.007mN / m, and improve the flooding capability; 4) The preparation method of the surfactant provided by the present invention is simple, the raw material source is wide, the production cost is low, and it is suitable for industrial promotion; 5) The surfactant provided by the present invention is used in oil field flooding, and the oil flooding efficiency can be increased by more than 18% compared with water flooding; 6) The surfactant provided by the present invention is used in oil field flooding, which can greatly improve the adaptability range of the extreme difference in reservoir permeability. DETAILED DESCRIPTION

[0012] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0013] The first aspect of the present invention provides a surfactant, wherein the structural formula of the surfactant is:

[0014] Wherein, R is selected from a straight chain or branched chain alkyl group, n is an integer of 1-8, and m is an integer of 1-10.

[0015] In a preferred embodiment of the present invention, R is selected from C2-C 15 The straight chain or branched chain alkyl group is preferably a straight chain or branched chain alkyl group of C4-C8, and more preferably one of a C4 straight chain alkyl group, a C6 straight chain alkyl group, and a C8 straight chain alkyl group. That is, R is preferably a n-butyl group, a n-hexyl group, or a n-octyl group.

[0016] In a preferred embodiment of the present invention, n can be 1, 2, 3, 4, 5, 6, 7, 8, preferably 4 or 6.

[0017] In a preferred embodiment of the present invention, m can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, preferably 1, 4, 5 or 10.

[0018] In a preferred embodiment of the present invention, the structural formula of the surfactant is one of Formula 1-1 to Formula 1-4:

[0019] Formula 1-1

[0020] Formula 1-2

[0021] Formula 1-3

[0022] Formula 1-4; Among them, C8H 27 -, C4H9- and C6H 13 - are all straight-linked alkyl groups.

[0023] A second aspect of the present invention provides a method for preparing a surfactant, wherein the method comprises the following steps: (1) subjecting monounsaturated fatty acids to sulfation reaction with concentrated sulfuric acid to obtain sulfated fatty acids; (2) contacting the sulfated fatty acid with hydrochloric acid to carry out a hydrolysis reaction to obtain monohydroxystearic acid; (3) Under the action of catalyst I, the monohydroxystearic acid and ethylene oxide are subjected to a condensation reaction to obtain polyoxyethylene ether stearic acid; (4) Under the action of catalyst II, the polyoxyethylene ether stearic acid and N,N-dimethyl-1,3-propylenediamine are subjected to acylation reaction to obtain polyoxyethylene ether fatty acid amide propyl dimethylamine; (5) In the presence of a reaction solvent, the polyoxyethylene ether fatty acid amide propyl dimethylamine is subjected to an alkylation reaction with sodium 3-chloro-2-hydroxypropanesulfonate to obtain the surfactant.

[0024] In step (1), In a preferred embodiment of the present invention, the monounsaturated fatty acid is selected from C6-C 24 Straight-chain or branched monounsaturated fatty acids, preferably C 14 -C 22 The straight chain or branched monounsaturated fatty acid is preferably one or more of erucic acid, oleic acid, myristic acid, palmitic acid, and ricinoleic acid. In the present invention, the monounsaturated fatty acid refers to a fatty acid containing 1 double bond.

[0025] In a preferred embodiment of the present invention, the mass concentration of the concentrated sulfuric acid is 92%-98.3%, preferably 95%-98.3%.

[0026] In a preferred embodiment of the present invention, the mass ratio of the monounsaturated fatty acid to concentrated sulfuric acid is 1:1-2, preferably 1:1.2-1.6.

[0027] In a preferred embodiment of the present invention, the sulfation reaction is carried out in an ice bath, and the reaction time of the sulfation reaction is 2-10 h, preferably 4-6 h.

[0028] In the present invention, the monounsaturated fatty acid and concentrated sulfuric acid are preferably cooled in an ice bath before the acidification reaction to reduce the temperature to about 0° C. (eg, -5° C. to 5° C.).

[0029] In step (2), In a preferred embodiment of the present invention, the molar concentration of the hydrochloric acid is 1-5 mol / L, preferably 2-4 mol / L.

[0030] In a preferred embodiment of the present invention, the volume ratio of the sulfated fatty acid to hydrochloric acid is 1:1-3, preferably 1:1.5-2.5.

[0031] In a preferred embodiment of the present invention, the reaction temperature of the hydrolysis is 60-110° C., preferably 75-95° C.; the reaction time of the hydrolysis is 20-80 min, preferably 30-60 min.

[0032] In a preferred embodiment of the present invention, after the hydrolysis is completed, sodium hydroxide is first added for neutralization, and then petroleum ether is added for extraction to obtain monohydroxystearic acid.

[0033] In step (3), In a preferred embodiment of the present invention, the catalyst I is selected from sodium hydroxide and / or potassium hydroxide, preferably sodium hydroxide.

[0034] In a preferred embodiment of the present invention, the mass ratio of the monohydroxystearic acid, the catalyst I and the ethylene oxide is 1:0.01-0.1:1-15, preferably 1:0.02-0.05:1-10.

[0035] In a preferred embodiment of the present invention, the order of adding the monohydroxystearic acid, catalyst I and ethylene oxide is: first, the monohydroxystearic acid is heated to melt, and then the catalyst I is added to the molten monohydroxystearic acid, and then the temperature is raised to 110-140° C. under nitrogen protection, and ethylene oxide is added to react.

[0036] In a preferred embodiment of the present invention, the reaction temperature of the polymerization reaction is 110-140° C., preferably 120-130° C.; the reaction pressure is 0.1-0.5 MPa, preferably 0.1-0.3 MPa.

[0037] Among them, in the present invention, the polymerization reaction is carried out in a reactor. As the polymerization reaction proceeds, ethylene oxide is continuously consumed, and nitrogen needs to be continuously introduced to maintain a constant reaction pressure. When it is detected that the pressure in the reactor no longer fluctuates, that is, when nitrogen no longer needs to be introduced, it means that the polymerization reaction has been completed. At this time, heating can be stopped to cool down, thereby obtaining polyoxyethylene ether stearic acid.

[0038] In step (4), In a preferred embodiment of the present invention, the catalyst II is selected from one or more of boric acid, formic acid and acetic acid, preferably boric acid.

[0039] In a preferred embodiment of the present invention, the mass ratio of the polyoxyethylene ether stearic acid, N,N-dimethyl-1,3-propylenediamine and catalyst II is 1:1-1.35:0.005-0.035; preferably 1:1-1.15:0.01-0.02.

[0040] In a preferred embodiment of the present invention, the reaction temperature of the acylation reaction is 130-180° C., preferably 140-165° C.; the reaction time of the acylation reaction is 2-12 h, preferably 5-10 h.

[0041] In a preferred embodiment of the present invention, after the acylation reaction is completed, vacuum distillation is first performed, and then recrystallization is performed using ethanol to obtain polyoxyethylene ether fatty acid amide propyl dimethylamine.

[0042] In step (5), In a preferred embodiment of the present invention, the reaction solvent is selected from one or more of isopropanol, water, methanol, and ethanol, preferably isopropanol and water. Further preferably, the volume ratio of isopropanol to water is 1:1.5-2.5.

[0043] In a preferred embodiment of the present invention, the sodium 3-chloro-2-hydroxypropanesulfonate may be a commercially available product, or may be synthesized according to a known method, which is not particularly limited in the present invention.

[0044] In a preferred embodiment of the present invention, the mass ratio of the polyoxyethylene ether fatty acid amide propyl dimethylamine, sodium 3-chloro-2-hydroxypropane sulfonate and the reaction solvent is 1:1-1.5:1-15, preferably 1:1.1-1.3:3-10.

[0045] In a preferred embodiment of the present invention, the reaction temperature of the alkylation reaction is 40-100° C., preferably 50-90° C.; the reaction time of the alkylation reaction is 1-7 h, preferably 3-6 h.

[0046] Among them, in the present invention, after the alkylation reaction is completed, the reaction liquid obtained after the alkylation reaction can be separated and purified to separate the alkylation product to obtain a surfactant, or the reaction liquid containing the surfactant obtained after the alkylation reaction can be directly used as a surfactant for oil recovery.

[0047] The third aspect of the present invention provides a use of the surfactant described in the first aspect of the present invention or the surfactant prepared according to the method described in the second aspect of the present invention in oil field recovery.

[0048] The surfactant provided in the present invention can be injected into the oil reservoir after being diluted with water alone, or can be injected into the oil reservoir after being used in combination with other chemical agents such as polymers, nano-microspheres, etc., which can significantly improve the oil displacement effect and increase the recovery rate.

[0049] The present invention will be described in detail below by way of examples. Wherein, the mass concentration of concentrated sulfuric acid is 98%.

[0050] Preparation of sodium 3-chloro-2-hydroxypropanesulfonate: add 1g of sodium bisulfite, 0.015g of ethylenediaminetetraacetic acid and 3g of water to a reactor equipped with a condenser and a stirrer, raise the temperature to 70°C, slowly add 3g of epichlorohydrin, continue to raise the temperature to 90°C, react for 3h, then stop heating, let stand for 3h, then filter and dry in turn to obtain sodium 3-chloro-2-hydroxypropanesulfonate.

[0051] Example 1 (1) Place erucic acid and concentrated sulfuric acid in an ice bath and cool to 0°C respectively. Then, add 1.6 g of concentrated sulfuric acid to 1 g of erucic acid in an ice bath to carry out sulfation reaction. The reaction is stirred for 6 h to obtain sulfated erucic acid. (2) mixing the sulfated erucic acid and 4 mol / L hydrochloric acid in a volume ratio of 1:2.5, heating to 95° C. for hydrolysis, reacting for 30 min under stirring, then adding NaOH to neutralize excess acid, and extracting with petroleum ether to obtain monohydroxy erucic acid; (3) heating the monohydroxy erucic acid until it is completely melted, adding sodium hydroxide, and then transferring the mixture into a high-pressure reactor, introducing nitrogen to remove the air in the reactor, and then adding ethylene oxide, raising the temperature to 130° C., and conducting a polymerization reaction at 0.3 MPa. During the reaction, the reaction pressure is monitored in real time, and nitrogen is continuously introduced to maintain a constant pressure. When the reaction pressure no longer changes, heating is stopped, and the mixture is cooled to obtain polyoxyethylene ether erucic acid; wherein the mass ratio of monohydroxy erucic acid, sodium hydroxide, and ethylene oxide is 1:0.05:1; (4) Add the above-mentioned polyoxyethylene ether erucic acid, N,N-dimethyl-1,3-propylenediamine and boric acid in a mass ratio of 1:1.15:0.02 into a reactor equipped with a condenser, a stirrer and a temperature measuring device, and carry out an acylation reaction after nitrogen is introduced to replace the air. The reaction is carried out at 165°C for 10 hours. After the reaction is completed, vacuum distillation is first carried out to separate the excess N,N-dimethyl-1,3-propylenediamine, and then recrystallization is carried out with ethanol to obtain polyoxyethylene ether erucic acid amide propyl dimethylamine; (5) The above-mentioned polyoxyethylene ether erucic acid amide propyl dimethylamine, sodium 3-chloro-2-hydroxypropane sulfonate and reaction solvent (a mixture of isopropanol and water in a volume ratio of 1:2.5) are uniformly mixed in a mass ratio of 1:1.3:10 and then subjected to an alkylation reaction at 90°C for 6 hours. After the reaction is completed, the alkylation product is separated to obtain the surfactant polyoxyethylene ether erucic acid amide propyl hydroxysulfonate represented by formula 1-1.

[0052]

[0053] Formula 1-1 Example 2 (1) Cool oleic acid and concentrated sulfuric acid to 0°C in an ice bath, then add 1.4 g of concentrated sulfuric acid to 1 g of oleic acid in an ice bath for sulfation reaction. Stir the reaction for 4 h to obtain sulfated oleic acid. (2) mixing the sulfated oleic acid and 2 mol / L hydrochloric acid in a volume ratio of 1:2, heating to 90°C for hydrolysis, reacting for 50 min under stirring, then adding NaOH to neutralize excess acid, extracting with petroleum ether to obtain monohydroxy oleic acid; (3) After the monohydroxy oleic acid is heated until it is completely melted, sodium hydroxide is added, and then the reaction is transferred into a high-pressure reactor, nitrogen is introduced to remove the air in the reactor, and then ethylene oxide is added, the temperature is raised to 125° C., and a polymerization reaction is carried out at 0.2 MPa. During the reaction, the reaction pressure is monitored in real time, and nitrogen is continuously introduced to maintain a constant pressure. After the reaction pressure no longer changes, heating is stopped, and the reaction is cooled to obtain polyoxyethylene ether oleic acid; wherein the mass ratio of monohydroxy oleic acid, sodium hydroxide and ethylene oxide is 1:0.04:4; (4) Add the above-mentioned polyoxyethylene ether oleic acid, N,N-dimethyl-1,3-propylenediamine and boric acid in a mass ratio of 1:1:0.015 to a reactor equipped with a condenser, a stirrer and a temperature measuring device, and carry out an acylation reaction after nitrogen is introduced to replace the air. The reaction is carried out at 145°C for 8 hours. After the reaction is completed, vacuum distillation is first carried out to separate the excess N,N-dimethyl-1,3-propylenediamine, and then recrystallization is carried out with ethanol to obtain polyoxyethylene ether oleic acid amide propyl dimethylamine; (5) The above-mentioned polyoxyethylene ether oleic acid amide propyl dimethylamine, sodium 3-chloro-2-hydroxypropane sulfonate and reaction solvent (a mixture of isopropanol and water in a volume ratio of 1:1.5) are uniformly mixed in a mass ratio of 1:1.1:8 and then subjected to an alkylation reaction at 80°C for 5 hours. After the reaction is completed, the alkylation product is separated to obtain the surfactant polyoxyethylene ether oleic acid amide propyl hydroxysulfobetaine represented by formula 1-2.

[0054]

[0055] Formula 1-2 Example 3 (1) Myristic acid and concentrated sulfuric acid were placed in an ice bath and cooled to 0°C, and then 1.2 g of concentrated sulfuric acid was added to 1 g of myristic acid in an ice bath to carry out a sulfation reaction. The mixture was stirred for 4 h to obtain sulfated myristic acid. (2) mixing the sulfated myristic acid and 2 mol / L hydrochloric acid in a volume ratio of 1:1.5, heating to 75° C. for hydrolysis, reacting for 30 min under stirring, then adding NaOH to neutralize excess acid, and extracting with petroleum ether to obtain monohydroxy myristic acid; (3) After the monohydroxymyristic acid is heated until it is completely melted, sodium hydroxide is added, and then the mixture is transferred into a high-pressure reactor, nitrogen is introduced to remove the air in the reactor, and then ethylene oxide is added, the temperature is raised to 120° C., and a polymerization reaction is carried out at 0.1 MPa. During the reaction, the reaction pressure is monitored in real time, and nitrogen is continuously introduced to maintain a constant pressure. After the reaction pressure no longer changes, heating is stopped, and the mixture is cooled to obtain polyoxyethylene ether myristic acid; wherein the mass ratio of monohydroxymyristic acid, sodium hydroxide and ethylene oxide is 1:0.03:10; (4) Add the above-mentioned polyoxyethylene ether myristic acid, N,N-dimethyl-1,3-propylenediamine and boric acid in a mass ratio of 1:1:0.01 into a reactor equipped with a condenser, a stirrer and a temperature measuring device, and carry out an acylation reaction after nitrogen is introduced to replace the air. The reaction is carried out at 140° C. for 5 hours. After the reaction is completed, vacuum distillation is first carried out to separate the excess N,N-dimethyl-1,3-propylenediamine, and then recrystallization is carried out with ethanol to obtain polyoxyethylene ether myristic acid amide propyl dimethylamine; (5) The above-mentioned polyoxyethylene ether myristic acid amide propyl dimethylamine, sodium 3-chloro-2-hydroxypropane sulfonate and reaction solvent (a mixture of isopropanol and water in a volume ratio of 1:1.5) are uniformly mixed in a mass ratio of 1:1.1:3 and then subjected to an alkylation reaction at 50°C for 6 hours. After the reaction is completed, the alkylation product is separated to obtain the surfactant polyoxyethylene ether myristic acid amide propyl hydroxysulfobetaine represented by formula 1-3.

[0056]

[0057] Formula 1-3 Example 4 (1) Palmitoleic acid and concentrated sulfuric acid were cooled to 0°C in an ice bath respectively, and then 1.5 g of concentrated sulfuric acid was added to 1 g of palmitoleic acid in an ice bath to carry out sulfation reaction. The reaction was stirred for 5.5 h to obtain sulfated palmitoleic acid. (2) mixing the sulfated palmitoleic acid and 3 mol / L hydrochloric acid in a volume ratio of 1:2.5, heating to 85° C. for hydrolysis, reacting for 45 min under stirring, then adding NaOH to neutralize excess acid, and extracting with petroleum ether to obtain monohydroxypalmitoleic acid; (3) After the monohydroxypalmitoleic acid is heated until it is completely melted, sodium hydroxide is added, and then the mixture is transferred into a high-pressure reactor, nitrogen is introduced to remove the air in the reactor, and then ethylene oxide is added, the temperature is raised to 120° C., and a polymerization reaction is carried out at 0.1 MPa. During the reaction, the reaction pressure is monitored in real time, and nitrogen is continuously introduced to maintain a constant pressure. When the reaction pressure no longer changes, heating is stopped to obtain polyoxyethylene ether palmitoleic acid; wherein the mass ratio of monohydroxypalmitoleic acid, sodium hydroxide and ethylene oxide is 1:0.05:5; (4) Add the above-mentioned polyoxyethylene ether palmitoleic acid, N,N-dimethyl-1,3-propylenediamine and boric acid in a mass ratio of 1:1:0.02 to a reactor equipped with a condenser, a stirrer and a temperature measuring device, and carry out an acylation reaction after nitrogen is introduced to replace the air. The reaction is carried out at 140° C. for 5 hours. After the reaction is completed, vacuum distillation is first carried out to separate the excess N,N-dimethyl-1,3-propylenediamine, and then recrystallization is carried out with ethanol to obtain polyoxyethylene ether palmitoleic acid amide propyl dimethylamine; (5) The above-mentioned polyoxyethylene ether oleic acid amidopropyl dimethylamine, sodium 3-chloro-2-hydroxypropane sulfonate and reaction solvent (a mixture of isopropanol and water in a volume ratio of 1:1.5) are uniformly mixed in a mass ratio of 1:1.1:4 and then subjected to an alkylation reaction at 50°C for 3 hours. After the reaction is completed, the alkylation product is separated to obtain the surfactant polyoxyethylene ether palmitoleic acid amidopropyl hydroxysulfonate represented by formula 1-4.

[0058]

[0059] Formula 1-4 Comparative Example 1 (1) Add erucic acid, N,N-dimethyl-1,3-propylenediamine and boric acid in a mass ratio of 1:1.15:0.015 into a reactor equipped with a condenser, a stirrer and a temperature measuring device, introduce nitrogen to replace the air, and then carry out an acylation reaction at 145°C for 8 hours; after the reaction is completed, first perform vacuum distillation to separate the excess N,N-dimethyl-1,3-propylenediamine, and then recrystallize it with ethanol to obtain erucic acid amide propyl dimethylamine; (2) The above-mentioned erucamidopropyl dimethylamine, sodium 3-chloro-2-hydroxypropanesulfonate and reaction solvent (a mixture of isopropanol and water in a volume ratio of 1:2.5) are uniformly mixed in a mass ratio of 1:1.3:10 and then subjected to an alkylation reaction at 90°C for 6 hours. After the reaction is completed, the alkylation product is separated to obtain the surfactant erucamidopropyl hydroxysulfonobetaine represented by formula 1-5.

[0060]

[0061] Formula 1-5 Test Example 1 0.3 g of the surfactants prepared in Examples 1-4 and Comparative Example 1 were added to 100 g of formation water (mineralization of 42 g / L, calcium and magnesium ion content of 2 g / L) from a block of Changqing Oilfield to obtain test samples, and the solubility of the surfactants was observed.

[0062] Among them, it can be seen from the observation that the surfactants prepared in Examples 1-4 can be completely dissolved in the formation water and have good solubility. However, the surfactant prepared in Comparative Example 1 cannot be completely dissolved in the formation water and has poor solubility.

[0063] With reference to SY / T 6424-2014 composite flooding system performance test method, the viscosity of the test sample was tested at 50°C, and the interfacial tension between the sample and crude oil from a block of Changqing Oilfield (reservoir temperature is 50°C) was tested. With reference to GB T 6369-2008 surfactant emulsifying power determination colorimetric method, the emulsifying power of the test sample was tested. The test results are shown in Table 1.

[0064] Table 1 project Interfacial tension, mN / m Viscosity at 50℃, mPa.s Emulsifying power, % Example 1 0.0015 7.33 93.7 Example 2 0.0007 4.24 85.4 Example 3 0.0034 2.35 97.6 Example 4 0.0062 1.87 92.4 Comparative Example 1 0.035 1.03 45.3 As can be seen from Table 1, the surfactant provided in the present invention can significantly increase the viscosity of the water phase, and at the same time can significantly reduce the oil-water interfacial tension, emulsify crude oil, and the emulsification power is above 85.4%.

[0065] Test Example 2 The oil recovery experiment was carried out by simulating the reservoir conditions of a block in Changqing Oilfield. The experimental method referred to the performance test method of composite oil recovery system SY / T 6424-2014, and the oil recovery efficiency of the surfactants prepared in different embodiments and comparative examples at an effective concentration of 0.3% was investigated. The test results are shown in Table 2.

[0066] Table 2 project The improvement of oil displacement efficiency compared with water displacement, % Example 1 26.5 Example 2 24.1 Example 3 18.3 Example 4 19.3 Comparative Example 1 3.2 It can be seen from Table 2 that, under the same conditions, compared with water flooding, the oil flooding efficiency of the surfactant aqueous solution prepared in the present invention can be increased by at least 18.3%.

[0067] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A surfactant, characterized in that The structural formula of the surfactant is: Wherein, R is selected from a straight chain or branched chain alkyl group, n is an integer of 1-8, and m is an integer of 1-10.

2. The surfactant according to claim 1, wherein The R is selected from C2-C 15 The straight chain or branched alkyl group is preferably a C4-C8 straight chain or branched alkyl group, and more preferably one of a C4 straight chain alkyl group, a C6 straight chain alkyl group, and a C8 straight chain alkyl group.

3. The surfactant according to claim 2, wherein The structural formula of the surfactant is one of Formula 1-1 to Formula 1-4: Formula 1-1 Formula 1-2 Formula 1-3 Formula 1-4; Among them, C8H 27 -, C4H9- and C6H 13 - are all straight-linked alkyl groups.

4. A method for preparing a surfactant, characterized in that: The method comprises the following steps: (1) subjecting monounsaturated fatty acids to sulfation reaction with concentrated sulfuric acid to obtain sulfated fatty acids; (2) contacting the sulfated fatty acid with hydrochloric acid to carry out a hydrolysis reaction to obtain monohydroxystearic acid; (3) Under the action of catalyst I, the monohydroxystearic acid and ethylene oxide are polymerized to obtain polyoxyethylene ether stearic acid; (4) Under the action of catalyst II, the polyoxyethylene ether stearic acid and N,N-dimethyl-1,3-propylenediamine are subjected to acylation reaction to obtain polyoxyethylene ether fatty acid amide propyl dimethylamine; (5) In the presence of a reaction solvent, the polyoxyethylene ether fatty acid amide propyl dimethylamine is subjected to an alkylation reaction with sodium 3-chloro-2-hydroxypropanesulfonate to obtain the surfactant.

5. The preparation method according to claim 4, wherein: The monounsaturated fatty acid is selected from C8-C 36 Straight-chain or branched monounsaturated fatty acids, preferably C 12 -C 22 A straight-chain or branched monounsaturated fatty acid, further preferably one or more of erucic acid, oleic acid, myristic acid, palmitoleic acid, and ricinoleic acid; Preferably, the mass concentration of the concentrated sulfuric acid is 92%-98.3%, preferably 95%-98.3%; Preferably, the mass ratio of the monounsaturated fatty acid to concentrated sulfuric acid is 1:1-2, preferably 1:1.2-1.6; Preferably, the sulfation reaction is carried out in an ice bath, and the reaction time of the sulfation reaction is 2-10 h, preferably 4-6 h.

6. The preparation method according to claim 4 or 5, wherein: The concentration of the hydrochloric acid is 1-5 mol / L, preferably 2-4 mol / L; Preferably, the volume ratio of the sulfated fatty acid to hydrochloric acid is 1:1-3, preferably 1:1.5-2.5; Preferably, the reaction temperature of the hydrolysis is 60-110°C, preferably 75-95°C; the reaction time of the hydrolysis is 20-80min, preferably 30-60min; Preferably, after the hydrolysis reaction is completed, sodium hydroxide is first added for neutralization, and then petroleum ether is added for extraction to obtain the monohydroxystearic acid.

7. The preparation method according to any one of claims 4 to 6, wherein: The catalyst I is selected from sodium hydroxide and / or potassium hydroxide, preferably sodium hydroxide; Preferably, the mass ratio of monohydroxystearic acid, catalyst I and ethylene oxide is 1:0.01-0.08:1-15, preferably 1:0.02-0.05:1-10; Preferably, the reaction temperature of the polymerization reaction is 110-140° C., preferably 120-130° C.; the reaction pressure is 0.1-0.5 MPa, preferably 0.1-0.3 MPa.

8. The preparation method according to any one of claims 4 to 7, wherein: The catalyst II is selected from one or more of boric acid, formic acid, and acetic acid, preferably boric acid; Preferably, the mass ratio of the polyoxyethylene ether stearic acid, N,N-dimethyl-1,3-propylenediamine and catalyst II is 1:1-1.35:0.005-0.035; preferably 1:1-1.15:0.01-0.02; Preferably, the reaction temperature of the acylation reaction is 130-180°C, preferably 140-165°C; the reaction time is 2-12h, preferably 5-10h; Preferably, after the acylation reaction is completed, vacuum distillation is first performed, and then recrystallization is performed using ethanol to obtain the polyoxyethylene ether fatty acid amide propyl dimethylamine.

9. The preparation method according to any one of claims 4 to 8, wherein: The reaction solvent is selected from one or more of isopropanol, water, methanol, and ethanol, preferably isopropanol and water; further preferably, the volume ratio of isopropanol to water is 1:1.5-2.5; Preferably, the mass ratio of the polyoxyethylene ether fatty acid amide propyl dimethylamine, sodium 3-chloro-2-hydroxypropane sulfonate and the reaction solvent is 1:1-1.5:1-15, preferably 1:1.1-1.3:3-10; Preferably, the reaction temperature of the alkylation reaction is 40-100° C., preferably 50-90° C.; the reaction time is 1-7 h, preferably 3-6 h.

10. Use of the surfactant according to any one of claims 1 to 3 or the surfactant prepared by the method according to any one of claims 4 to 9 in oil field flooding.

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