Surfactant composition and fatty alcohol copolymer as well as preparation method and application of surfactant composition and fatty alcohol copolymer

Abstract

The invention relates to the field of oil exploitation and oilfield chemical materials, in particular to a fatty alcohol copolymer and surfactant composition as well as a preparation method and application thereof. Wherein the copolymer has a chemical structure as shown in a formula (1); wherein R is selected from a substituted or unsubstituted alkyl group of C14 to C70 and a substituted or unsubstituted alkenyl group of C14 to C70; the substituted substituent is selected from at least one of hydroxyl, halogen, cyano, nitro and amino; x is a positive integer selected from 20-50; and y is a positive integer selected from 20-40. The surfactant containing the fatty alcohol copolymer has the characteristics of good high temperature resistance and salt resistance and low oil / water interfacial tension. # imgabs0 #

Description

Technical Field

[0001] The invention relates to the field of petroleum exploitation and oilfield chemical materials, and in particular to a surfactant composition and a fatty alcohol copolymer, and a preparation method and application thereof. Background Art

[0002] Tertiary oil recovery technology is a general term for various new technologies used after the water flooding stage for reservoirs with different characteristics, typically thermal recovery, chemical flooding, gas miscible flooding, microbial oil recovery, etc. In tertiary oil recovery (EOR) technology, chemical flooding is one of the most studied technologies, including alkaline water flooding, polymer flooding, surfactant flooding, alkali / surfactant / polymer (ASP) ternary composite flooding, foam flooding, etc., among which the flooding technology with surfactant as the core has become the mainstream technology. Commonly used surfactants at home and abroad include anionic surfactants (fatty alcohol polyoxyethylene ether sulfate (AES), petroleum sulfonates, petroleum carboxylates, sodium alkylbenzene sulfonate, etc.), cationic surfactants (cetyl trimethyl ammonium bromide (CTAB)), nonionic surfactants (alkyl polyglycosides (APG), alkylphenol polyoxyethylene ether surfactants, Peregal surfactants, etc.), zwitterionic surfactants (alkyl sulfonated betaines, etc.), Gemini surfactants (xylene didodecyl phosphate, etc.) and natural (bio) surfactants (rhamnosyl esters, trehalose esters, sophoroside esters, saponins, rosins, etc.). Among them, anionic surfactants are the most studied because they show relatively low adsorption losses on sandstones with negative surface charges. Nonionic surfactants are mainly used as auxiliary surfactants to improve the phase behavior of the system and are often used in combination with anionic surfactants. At present, there are few products of surfactants with ultra-low interfacial tension between oil and water, and even fewer that meet the needs of high-temperature and high-salinity reservoirs.

[0003] Therefore, a surfactant composition is needed to make up for the above-mentioned defects of the prior art. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems of poor high temperature resistance and salt resistance and insufficient low oil / water interfacial tension in the prior art, and to provide a surfactant composition and a fatty alcohol copolymer and a preparation method and application thereof.

[0005] In order to achieve the above object, the first aspect of the present invention provides a surfactant composition, wherein the composition comprises a fatty alcohol copolymer, inorganic nanoparticles and an anionic surfactant; wherein the fatty alcohol copolymer has a chemical structure shown in formula (1):

[0006]

[0007] wherein R is selected from substituted or unsubstituted C14 -C 70 Alkyl, substituted or unsubstituted C 14 -C 70 The substituted substituent is selected from at least one of hydroxyl, halogen, cyano, nitro and amino; x / y=0.6-1.2.

[0008] A second aspect of the present invention provides a method for preparing a surfactant composition, the method comprising:

[0009] Mixing a fatty alcohol copolymer, inorganic nanoparticles and anionic surfactant in a solvent, and optionally adding a solubilizer to obtain the surfactant composition;

[0010] The definitions of the fatty alcohol copolymer, inorganic nanoparticles and anionic surfactant are the same as those described in the first aspect of the present invention.

[0011] The third aspect of the present invention provides use of the surfactant composition described in the first aspect of the present invention in petroleum production and oilfield chemical materials.

[0012] The fourth aspect of the present invention provides a fatty alcohol copolymer, wherein the copolymer has a chemical structure shown in formula (1):

[0013] Where R is selected from C 31 -C 66 The definitions of x and y are the same as those described in the first aspect of the present invention.

[0014] A fifth aspect of the present invention provides a method for preparing a fatty alcohol copolymer, the method comprising:

[0015] (1) contacting fatty alcohol ROH with propylene oxide in the presence of a catalyst and a protective gas to carry out a first etherification reaction to obtain a mixture;

[0016] (2) contacting the mixture in step (1) with ethylene oxide, performing a second etherification reaction and performing post-treatment to obtain the fatty alcohol copolymer;

[0017] Where R is selected from C 31 -C 66 of alkyl.

[0018] The sixth aspect of the present invention provides use of the fatty alcohol copolymer described in the fourth aspect of the present invention in a surfactant.

[0019] Through the above technical scheme, the present invention provides a nanoparticle anionic-nonionic composite surfactant. Compared with the prior art, the present invention prepares a nanoparticle anionic-nonionic composite surfactant by combining inorganic nanoparticles with a self-made fatty alcohol-EO-PO copolymer nonionic surfactant and anionic surfactant. Inorganic nanoparticles can not only give the surfactant temperature resistance, but also synergize with anionic surfactants to reduce the oil / water surface tension. Nonionic surfactants are mainly used as auxiliary anionic surfactants to improve the phase behavior of the system and are more tolerant to the high salinity of formation water. The nanoparticle anionic-nonionic composite surfactant prepared by the present invention has ultra-low oil / water interfacial tension under high temperature and high mineralization conditions, thereby increasing the oil washing efficiency.

[0020] The invention has strong temperature resistance and salt resistance. The inorganic nanoparticles can adsorb the surfactant molecules on the interface film, so that the surfactant molecules can be stabilized on the interface, and the shear resistance of the surfactant molecules is enhanced. Under high temperature conditions, the molecular chain is not easy to break, and the system temperature resistance is ≥90°C.

[0021] Nanoparticle anionic-nonionic composite surfactant has ultra-low oil / water interfacial tension, ≤10 -4 mN / m. Anionic surfactants are negatively charged and show relatively low adsorption losses on sandstones with negative charges on the surface. Nonionic surfactants are mainly used as auxiliary anionic surfactants to improve the phase behavior of the system, and are more tolerant to the high salinity of formation water, with a salt resistance of ≥50000mg / L (including Ca and Mg divalent ions ≥2000mg / L). DETAILED DESCRIPTION

[0022] 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.

[0023] As mentioned above, the first aspect of the present invention provides a surfactant composition, wherein the composition comprises a fatty alcohol copolymer (nonionic surfactant), inorganic nanoparticles and anionic surfactant; wherein the fatty alcohol copolymer has a chemical structure shown in formula (1):

[0024]

[0025] wherein R is selected from substituted or unsubstituted C 14 -C 70 Alkyl, substituted or unsubstituted C 14-C 70 The substituted substituent is selected from at least one of hydroxyl, halogen, cyano, nitro and amino; x / y=0.6-1.2.

[0026] In some embodiments of the present invention, preferably, in formula (1), R is selected from substituted or unsubstituted C 14 -C 68 Alkyl, substituted or unsubstituted C 14 -C 68 The substituted substituent is selected from at least one of hydroxyl, halogen and cyano, preferably hydroxyl.

[0027] Preferably, x is selected from a positive integer of 20-50; y is selected from a positive integer of 20-40. More preferably, x is selected from a positive integer of 20-45; y is selected from a positive integer of 25-35.

[0028] In some embodiments of the present invention, preferably, x / y=0.8-0.9.

[0029] According to a more preferred embodiment, R is

[0030]

[0031] In some embodiments of the present invention, preferably, the weight average molecular weight of the copolymer is 2000-4600 g / mol; more preferably 2100-4200 g / mol.

[0032] In some embodiments of the present invention, preferably, the inorganic nanoparticles are selected from at least one of nano-silicon dioxide, nano-aluminum oxide, nano-magnesium carbonate, nano-zinc oxide and nano-titanium oxide, more preferably nano-silicon dioxide and nano-aluminum oxide.

[0033] In some embodiments of the present invention, preferably, the anionic surfactant is selected from at least one of fatty alcohol polyoxyethylene ether sulfate (AES), petroleum sulfonates, petroleum carboxylates, sodium alkyl sulfonates and sodium alkylbenzene sulfonates, more preferably sodium dodecyl sulfonate and / or sodium hexadecylbenzene sulfonate.

[0034] In some embodiments of the present invention, preferably, the mass ratio of the fatty alcohol copolymer to the anionic surfactant is 4:1-1:1, more preferably 2.5:1-1:1.

[0035] In some embodiments of the present invention, preferably, the mass ratio of the fatty alcohol copolymer to the inorganic nanoparticles is 100-800:1, more preferably 700-750:1.

[0036] In the present invention, the surfactant composition may further contain a solubilizer, which may be a common substance that can promote the dissolution of the fatty alcohol copolymer, the inorganic nanoparticles and the anionic surfactant in a solvent (such as water), and may be selected from Span. There is no particular requirement for the amount of the solubilizer, but preferably, the mass ratio of the solubilizer to the inorganic nanoparticles is 1:0.8-2.5.

[0037] A second aspect of the present invention provides a method for preparing a surfactant composition, the method comprising:

[0038] Mixing a fatty alcohol copolymer, inorganic nanoparticles and anionic surfactant in a solvent, and optionally adding a solubilizer to obtain the surfactant composition;

[0039] The definitions and usage of the fatty alcohol copolymer, inorganic nanoparticles and anionic surfactant are the same as those described in the first aspect of the present invention and will not be described in detail herein.

[0040] In some embodiments of the present invention, preferably, the solvent is deionized water.

[0041] The third aspect of the present invention provides the use of the surfactant composition described in the first aspect of the present invention in oil production and oilfield chemical materials. The surfactant composition of the present invention can be prepared as a 0.1-1 wt% solution for use.

[0042] The fourth aspect of the present invention provides a fatty alcohol copolymer, wherein the copolymer has a chemical structure shown in formula (1):

[0043] Where R is selected from C 31 -C 66 The definitions of x and y are the same as those described in the first aspect of the present invention.

[0044] A fifth aspect of the present invention provides a method for preparing a fatty alcohol copolymer, the method comprising:

[0045] (1) contacting fatty alcohol ROH with propylene oxide in the presence of a catalyst and a protective gas to carry out a first etherification reaction to obtain a mixture;

[0046] (2) contacting the mixture in step (1) with ethylene oxide, performing a second etherification reaction and performing post-treatment to obtain the fatty alcohol copolymer;

[0047] Where R is selected from C 31 -C 66 of alkyl.

[0048] In some embodiments of the present invention, preferably, in step (1), the catalyst is selected from nano-silicon dioxide, nano-aluminum oxide, nano-magnesium carbonate, nano-zinc oxide and nano-titanium oxide, preferably nano-silicon dioxide and nano-aluminum oxide.

[0049] In some embodiments of the present invention, preferably, the amount of the catalyst is 1-3 wt % of the fatty alcohol.

[0050] In some embodiments of the present invention, preferably, the molar ratio of the fatty alcohol to propylene oxide is 1:10-1:55, more preferably 1:12-1:30, and more preferably 1:20-1:30.

[0051] In some embodiments of the present invention, preferably, the temperature of the first etherification reaction is 90-120° C., the pressure is 80-120 Psi, and the time is 2-4 h.

[0052] In some embodiments of the present invention, preferably, in step (2), the amount of ethylene oxide added is 0.85-1.6 times the molar amount of propylene oxide in step (1).

[0053] In some embodiments of the present invention, preferably, the temperature of the second etherification reaction is 120-180° C., the pressure is 80-120 Psi, and the time is 2-4 h.

[0054] In some embodiments of the present invention, preferably, the post-treatment operation includes adjusting the pH to 7-8.

[0055] In some embodiments of the present invention, preferably, the pH value is adjusted by adding an acid; wherein the acid is selected from lactic acid and acetic acid; preferably lactic acid.

[0056] In some embodiments of the present invention, preferably, the pH value is adjusted to 7-8 as a result of adjusting the pH value.

[0057] The sixth aspect of the present invention provides use of the fatty alcohol copolymer described in the fourth aspect of the present invention in a surfactant.

[0058] The present invention will be described in detail below through examples. In the following examples, the oil-water interfacial tension parameters are measured by an SVT 25 ultra-low interfacial tension meter; the raw materials fatty alcohol, inorganic nanoparticles, lactic acid, sodium hexadecylbenzene sulfonate and sodium dodecylbenzene sulfonate are analytically pure commercial products of Aladdin Reagent Co., Ltd.; the raw materials ethylene oxide and propylene oxide are chemically pure commercial products of Sinopharm Chemical Reagent Co., Ltd.

[0059] Example 1

[0060] Synthesis of fatty alcohol copolymers:

[0061] In the presence of 0.354 g potassium hydroxide (catalyst) and nitrogen (protective gas), 35.4 g (fatty alcohol, Cas No. 21129-09-9) was contacted with 92.8 g propylene oxide to carry out a first etherification reaction at a reaction temperature of 90° C., a reaction pressure of 80 psi, and a reaction time of 4 h to obtain a mixture;

[0062] The mixture was contacted with 78.88 g of ethylene oxide to carry out a second etherification reaction at a reaction temperature of 120° C., a reaction pressure of 100 psi, and a reaction time of 4 hours. Lactic acid solution was added to adjust the pH to a range of 7-8 to obtain the fatty alcohol copolymer. The fatty alcohol copolymer has a chemical structure shown in formula (1):

[0063] The content of the reaction substrate in the product after the second etherification reaction (the same below) was analyzed to obtain: x / y=0.8, and the weight average molecular weight was measured by the XPS method to be 3500 g / mol.

[0064] Preparation of surfactant composition:

[0065] 25 g of the fatty alcohol copolymer, 0.035 g of inorganic nanoparticles (nanosilica) and 10 g of anionic surfactant were mixed, 0.035 g of a solubilizer (specifically Span-80) was added, and the mixture was stirred for 1 hour to obtain the surfactant composition.

[0066] Example 2

[0067] Synthesis of fatty alcohol copolymers:

[0068] In the presence of 0.708 g potassium hydroxide (catalyst) and nitrogen (protective gas), 35.4 g (fatty alcohol, Cas No. 19812-64-7) was contacted with 116 g propylene oxide to carry out a first etherification reaction at a reaction temperature of 120° C., a reaction pressure of 120 psi, and a reaction time of 2 h to obtain a mixture;

[0069] The mixture was contacted with 88 g of ethylene oxide to carry out a second etherification reaction at a reaction temperature of 180° C., a reaction pressure of 100 psi, and a reaction time of 4 hours. Lactic acid solution was added to adjust the pH to a range of 7-8 to obtain the fatty alcohol copolymer. The fatty alcohol copolymer has a chemical structure shown in formula (1):

[0070] The content of the reaction substrate in the product after the second etherification reaction was analyzed to obtain: x / y=1, and the weight average molecular weight was measured by the XPS method to be 4000 g / mol.

[0071] Preparation of surfactant composition:

[0072] 25 g of the fatty alcohol copolymer described in Example 2, 0.15 g of inorganic nanoparticles (nanosilica) and 25 g of anionic surfactant (sodium dodecyl sulfate) were mixed, 0.15 g of a solubilizer (specifically Span-80) was added, and stirred for 1 hour to obtain the surfactant composition.

[0073] Example 3

[0074] Synthesis of fatty alcohol copolymers:

[0075] In the presence of 1.06 g potassium hydroxide (catalyst) and nitrogen (protective gas), 35.4 g (fatty alcohol, Cas No. 2774-87-0) was contacted with 58 g propylene oxide to carry out a first etherification reaction at a reaction temperature of 100° C., a reaction pressure of 120 psi, and a reaction time of 2 h to obtain a mixture;

[0076] The mixture was contacted with 70.4 g of ethylene oxide to carry out a second etherification reaction at a reaction temperature of 150° C., a reaction pressure of 120 psi, and a reaction time of 4 hours. Lactic acid solution was added to adjust the pH to a range of 7-8 to obtain the fatty alcohol copolymer.

[0077] The fatty alcohol copolymer has the chemical structure shown in formula (1):

[0078]

[0079] The content of the reaction substrate in the product after the second etherification reaction was analyzed to obtain: x / y=0.625, and the weight average molecular weight was measured by the XPS method to be 4000 g / mol.

[0080] Preparation of surfactant composition:

[0081] 24 g of the fatty alcohol copolymer described in Example 3, 0.048 g of inorganic nanoparticles (nano zinc oxide) and 8 g of anionic surfactant (sodium hexadecylbenzenesulfonate) were mixed, 0.048 g of a solubilizer (specifically Span-80) was added, and the mixture was stirred for 1 hour to obtain the surfactant composition.

[0082] Example 4

[0083] 24 g of the fatty alcohol copolymer described in Example 1, 0.15 g of inorganic nanoparticles (nano zinc oxide) and 6 g of anionic surfactant (sodium hexadecylbenzenesulfonate) were mixed, 0.15 g of a solubilizer (specifically Span-80) was added, and the mixture was stirred for 1 hour to obtain the surfactant composition.

[0084] Example 5

[0085] 24 g of the fatty alcohol copolymer described in Example 2, 0.072 g of inorganic nanoparticles (nano zinc oxide) and 12 g of anionic surfactant (sodium hexadecylbenzenesulfonate) were mixed, 0.072 g of a solubilizer (specifically Span-80) was added, and the mixture was stirred for 1 hour to obtain the surfactant composition.

[0086] Example 6

[0087] 24 g of the fatty alcohol copolymer described in Example 3, 0.15 g of inorganic nanoparticles (nano zinc oxide) and 8 g of anionic surfactant (sodium hexadecylbenzenesulfonate) were mixed, 0.072 g of a solubilizer (specifically Span-80) was added, and the mixture was stirred for 1 hour to obtain the surfactant composition.

[0088] Comparative Example 1

[0089] A surfactant composition was prepared in the same manner as in Example 1, except that the fatty alcohol copolymer and the inorganic nanoparticles were not used, to obtain a reference surfactant composition.

[0090] Comparative Example 2

[0091] A surfactant composition was prepared in the same manner as in Example 1, except that the fatty alcohol copolymer was replaced with isomeric tridecanol polyoxyethylene ether (nonionic surfactant) to obtain a reference surfactant composition.

[0092] Comparative Example 3

[0093] A surfactant composition was prepared in the manner of Example 1, except that no inorganic nanoparticles were used, to obtain a reference surfactant composition.

[0094] Comparative Example 4

[0095] A surfactant composition was prepared in the same manner as in Example 1, except that no inorganic nanoparticles and anionic surfactant were used, to obtain a reference surfactant composition.

[0096] Test Example 1

[0097] The surfactant composition described in Examples 1-6 was dissolved in 50000 mg / L formation water, stirred for 1 hour, and prepared into 0.1 wt% and 0.5 wt% solutions. The oil-water interfacial tension test conditions were measured using an SVT 25 ultra-low interfacial tension meter: test temperature 90°C, formation water salinity 50000 mg / L. The test results are shown in Table 1.

[0098] Table 1

[0099]

[0100] Test Example 2

[0101] The nanoparticle anionic-nonionic composite surfactant described in Example 1 was selected, and surfactant samples of different concentrations were prepared with formation water. The oil-water interfacial tension was tested using an SVT 25 ultra-low interfacial tension meter at a temperature of 90° C. (external oil bath heating). The test results are shown in Table 2.

[0102] Table 2

[0103]

[0104] Test Example 3

[0105] The oil-water interfacial tension between the surfactant composition described in Example 1 and Comparative Examples 1-4 (prepared into 0.1 wt% solution with formation water) and Daqing crude oil was measured using an SVT 25 ultra-low interfacial tension meter. Test conditions: test temperature 90°C, formation water salinity 50000 mg / L.

[0106] The oil-water interfacial tension between the surfactant composition solution of Example 1 and Comparative Examples 1-4 and Daqing crude oil was measured using a SVT 25 ultra-low interfacial tension meter. Test conditions: test temperature 90°C, formation water salinity 50000 mg / L. Test results are shown in Table 3.

[0107] Table 3

[0108] Sample (0.1wt%) <![CDATA[Interfacial tension (10 -4 mN / m)]]> Example 1 1.05 Comparative Example 1 401.59 Comparative Example 2 73.21 Comparative Example 3 15.17 Comparative Example 4 668.11

[0109] By comparing the data in Tables 1-3, it can be seen that the surfactant compositions prepared by Examples 1-6 of the technical solution of the present invention have lower oil-water interfacial tension than the surfactants prepared by Comparative Examples 1-4, and the lowest one can reach 1.05×10 - 4 mN / m, with significantly better technical results.

[0110] At the same time, compared with the prior art (CN112708410A, CN108285781B and literature: Ma Jiangbo, Li Jianxun, Li Gang, et al. Screening and evaluation of surfactant flooding system for low-temperature, high-salinity and low-permeability oil reservoirs [J]. Oilfield Chemistry, 2022, 39(04): 682-687.), the surfactant composition prepared by Examples 1-11 of the technical solution of the present invention can still maintain its oil-water interfacial tension at 10 when the system temperature is ≥90°C. -4 mN / m level, which is impossible to achieve with the prior art. Therefore, the technical solution of the present invention has significantly better technical effects in terms of temperature resistance.

[0111] 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 composition, wherein: The composition comprises a fatty alcohol copolymer, inorganic nanoparticles and an anionic surfactant; wherein the fatty alcohol copolymer has a chemical structure shown in formula (1): wherein R is selected from substituted or unsubstituted C 14 -C 70 Alkyl, substituted or unsubstituted C 14 -C 70 The substituted substituent is selected from at least one of hydroxyl, halogen, cyano, nitro and amino; x / y=0.6-1.

2.

2. The composition according to claim 1, wherein In formula (1), R is selected from substituted or unsubstituted C 14 -C 68 Alkyl, substituted or unsubstituted C 14 -C 68 The substituted substituent is selected from at least one of hydroxyl, halogen and cyano, preferably hydroxyl; x is selected from a positive integer of 20-50; y is selected from a positive integer of 20-40; Preferably, x is selected from a positive integer of 20-45; y is selected from a positive integer of 25-35; Preferably, x / y=0.8-0.9; Preferably, the weight average molecular weight of the copolymer is 2000-4600 g / mol; more preferably 2100-4200 g / mol.

3. The composition according to claim 1 or 2, wherein The inorganic nanoparticles are selected from at least one of nano-silicon dioxide, nano-aluminum oxide, nano-magnesium carbonate, nano-zinc oxide and nano-titanium oxide, more preferably nano-silicon dioxide and / or nano-aluminum oxide; Preferably, the anionic surfactant is selected from at least one of fatty alcohol polyoxyethylene ether sulfate, petroleum sulfonate, petroleum carboxylate, sodium alkyl sulfonate and sodium alkyl benzene sulfonate, more preferably sodium dodecyl sulfonate and / or sodium hexadecyl benzene sulfonate; Preferably, the mass ratio of the fatty alcohol copolymer to the anionic surfactant is 4:1-1:1, more preferably 1:1-2.5:1; Preferably, the mass ratio of the fatty alcohol copolymer to the inorganic nanoparticles is 100-800:1, preferably 700-750:

1.

4. A method for preparing a surfactant composition, the method comprising: Mixing a fatty alcohol copolymer, inorganic nanoparticles and anionic surfactant in a solvent, and optionally adding a solubilizer to obtain the surfactant composition; Wherein, the fatty alcohol copolymer, inorganic nanoparticles and anionic surfactant are the same as defined in any one of claims 1-3.

5. The method according to claim 4, wherein: The mass ratio of the solubilizer to the inorganic nanoparticles is 1:0.8-2.

5.

6. Use of the surfactant composition according to any one of claims 1 to 3 in petroleum production and oilfield chemical materials.

7. A fatty alcohol copolymer, wherein: The copolymer has a chemical structure shown in formula (1): Where R is selected from C 31 -C 66 The definitions of x and y are the same as those in claim 1 or 2.

8. A method for preparing a fatty alcohol copolymer, the method comprising: (1) contacting fatty alcohol ROH with propylene oxide in the presence of a catalyst and a protective gas to carry out a first etherification reaction to obtain a mixture; (2) contacting the mixture in step (1) with ethylene oxide, performing a second etherification reaction and performing post-treatment to obtain the fatty alcohol copolymer; Where R is selected from C 31 -C 66 of alkyl.

9. The method according to claim 8, wherein: In step (1), the catalyst is selected from at least one of sodium hydroxide, potassium hydroxide and lithium hydroxide, preferably potassium hydroxide; Preferably, the protective gas is selected from at least one of nitrogen, argon and neon, more preferably nitrogen; Preferably, the catalyst is used in an amount of 1-3 wt % of the fatty alcohol; Preferably, the molar ratio of the fatty alcohol to propylene oxide is 1:10-1:55, more preferably 1:12-1:30, and more preferably 1:20-1:30; Preferably, the temperature of the first etherification reaction is 90-120°C; the pressure is 80-120Psi; and the time is 2-4h; Preferably, in step (2), the molar amount of ethylene oxide added is 0.85-1.6 times the molar amount of propylene oxide added in step (1); Preferably, the temperature of the second etherification reaction is 130-180°C; the pressure is 80-120Psi; and the time is 2-4h; Preferably, the post-treatment operation includes adjusting the pH to 7-8; Preferably, the pH value is adjusted by adding an acid, wherein the acid is selected from lactic acid and / or acetic acid, preferably lactic acid.

10. Use of the fatty alcohol copolymer according to claim 7 in the preparation of a surfactant.

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