Surfactitin derivative, preparation method and application

Abstract

The invention provides a surfactin derivative, the structural formula of which is as shown in formula I: wherein R1 and R2 are groups modified by amino acid; the amino acid is any one of threonine, histidine, arginine, tryptophan, asparaginic acid, leucine, isoleucine, valine, glutamic acid, phenylalanine, methionine, cysteine, tyrosine, alanine, glycine, proline, serine and glutamine; r1 and R2 are the same or different, and R1 and R2 are not OH at the same time. Based on a biosurfactant molecule which is surfactin with excellent surface activity, specific groups in the structure of the biosurfactant molecule are directionally modified to form a new biosurfactant structure, so that the polar characteristic of the biosurfactant is enhanced.

Description

TECHNICAL FIELD

[0001] The application relates to a surfactin derivative, a preparation method and application. BACKGROUND

[0002] Biosurfactin is a kind of amphiphilic peptide produced by microbial metabolism, and its structural characteristics include the combination of a fatty chain and an amino acid sequence. This unique structure endows biosurfactin with various biological properties, such as antifungal, antiviral and anticancer activities. In addition, biosurfactin also has good surface activity, and can reduce the air-water surface tension to 30 mN / m at a low dosage, change the solvent surface / interface properties, reduce the surface / interface tension, and exhibit various effects such as emulsification and demulsification, solubilization, foaming, washing, and wetting property change, and can be applied to many fields of social life such as the medical industry, the cosmetic industry, the petroleum industry, the food industry, nanotechnology and agriculture.

[0003] Compared with chemical surfactants, biosurfactin derivatives have good biological selectivity and strong environmental friendliness, and are good substitutes for chemical surfactants in oil exploitation. The unique structural characteristics of biosurfactin make a single molecule occupy a larger space in the solution, and hydrogen bonds can be formed between peptide rings, between peptide rings and amino acids, and between amino acids in the molecule, so that biosurfactin can form large micelles at a small concentration, and therefore has a low critical micelle concentration. Generally speaking, the larger the micelle, the greater the aggregation number, and the greater the solubilization of crude oil. By forming large micelles, the solubilization effect of crude oil is improved, so that the crude oil is dispersed in the aqueous solution of the surfactant to a certain extent to form an O / W type emulsion (Femina et al, 2021). And biosurfactants can maintain good stability under extreme pH, temperature and salinity conditions, can effectively change the wettability of rock wall surface, and can adapt to complex reservoir environments, and can achieve good enhanced oil recovery effect in oil exploitation. SUMMARY

[0004] Based on the biosurfactant molecule biosurfactin with excellent surface activity, the present application performs directional modification on specific groups in the structure of biosurfactin to form a new structure of biosurfactin and enhance the polarity characteristics of biosurfactin. Based on organic synthesis experiments, the obtained biosurfactin derivative shows excellent surface activity through modification of the exposed carboxyl group in biosurfactin.

[0005] The technical scheme of the present application is as follows:

[0006] 1. A biosurfactin derivative, whose structural formula is shown in formula I:

[0007]

[0008] wherein R1, R2 are both groups modified by an amino acid;

[0009] The amino acid is any one of threonine, histidine, arginine, tryptophan, aspartic acid, leucine, isoleucine, valine, glutamic acid, phenylalanine, methionine, cysteine, tyrosine, alanine, glycine, proline, serine, glutamine;

[0010] R1 and R2 are the same or different, and R1 and R2 are not OH at the same time;

[0011] Preferably,

[0012] The amino acid is any one of threonine, arginine, histidine, aspartic acid, leucine, valine, glutamic acid, alanine, glycine, serine, glutamine.

[0013] 2. The surfactin derivative according to item 1, wherein R1 and R2 are independently selected from:

[0014]

[0015] Preferably,

[0016] R1 and R2 are independently selected from:

[0017]

[0018] 3. The surfactin derivative according to item 1, wherein R1 and R2 are the same.

[0019] 4. A method for preparing the surfactin derivative according to any one of items 1 to 3, comprising:

[0020] reacting surfactin represented by formula II, an activating agent, and the amino acid in an organic solvent to obtain the surfactin derivative;

[0021]

[0022] Preferably,

[0023] The amino acid is 1 to 10 molar equivalents, preferably 4 to 6 molar equivalents, relative to 1 molar equivalent of surfactin represented by formula II.

[0024] 5. The method according to item 4, wherein the activating agent is one or two or more of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDCI), dimethylaminopyridine (DMAP), dicyclohexylcarbodiimide (DCC), diisopropylcarbodiimide (DIC).

[0025] Preferably, the activating agent is 1-18 molar equivalents, preferably 4-6 molar equivalents, relative to 1 molar equivalent of surfactin shown in formula II;

[0026] Further preferably,

[0027] The organic solvent is selected from one or more of N,N-dimethylformamide (DMF), methanol, ethanol, dimethyl sulfoxide (DMSO);

[0028] More preferably,

[0029] The reaction temperature is 20-50°C.

[0030] 6. The surfactin derivative of any one of items 1-3, the surfactin derivative prepared by the method of items 4-5 for use in oilfield exploitation.

[0031] 7. The surfactin derivative of any one of items 1-3, the surfactin derivative prepared by the method of items 4-5 for use in the preparation of a wicking agent, a fracturing fluid, a water lock prevention agent for an oil reservoir, a well cleaning fluid, a displacement agent.

[0032] 8. The surfactin derivative of any one of items 1-3, the surfactin derivative prepared by the method of items 4-5 for use in water lock prevention for an oil reservoir, enhanced oil recovery, wellbore cleaning.

[0033] 9. A biosurfactant comprising the surfactin derivative of any one of items 1-3, the surfactin derivative prepared by the method of items 4-5.

[0034] 10. An oil recovery agent comprising the surfactin derivative of any one of items 1-3, the surfactin derivative prepared by the method of items 4-5.

[0035] Technical effects

[0036] The present application mainly provides a surfactin derivative preparation method and application. The design idea is to direct modification of active groups on the hydrophilic ring structure of surfactin, change the structure composition of biological surfactin molecules, and thus obtain surfactin derivatives with significantly improved physical properties.

[0037] According to the structural characteristics of biological surfactin molecules, the present application designs a new molecule with enhanced polarity, i.e., a surfactin derivative, around the polar ring peptide part of the biological surfactin molecule. The active carboxyl group of the ring peptide structure is used as the modification object, and different amino acid compounds are used as modifiers. Through performance evaluation of the product such as surface tension, wettability, interfacial tension, and micro-displacement, different amino acid modified surfactin derivatives with enhanced polarity are obtained. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figures 1-4 Mass spectrum of the surfactin derivative of Example 3 of the present application; wherein Figure 1 Mass spectrum of the surfactin derivative prepared for X1; wherein Figure 2 Mass spectrum of the surfactin derivative prepared for X2; wherein Figure 3 Mass spectrum of the surfactin derivative prepared for X3; wherein Figure 4 Mass spectrum of the surfactin derivative prepared for X4. DETAILED DESCRIPTION

[0039] The present application is further illustrated by the following examples, which should not be construed as limiting the scope of the present application.

[0040] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, illustrative methods and materials are described below. However, if there is a conflict between the present specification and any document incorporated by reference, the present specification controls. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting. The present application is further described by the following non-limiting examples.

[0041] The structural formula of surfactin is shown as formula II.

[0042] The present application does not make any limitation on the source of surfactin as long as it meets the structural formula shown in formula II. The surfactin used in the present application is purified from the metabolic products in the microbial fermentation process. For example, the surfactin used in the present application is purified from the metabolic products in the microbial fermentation process. The present application does not make any limitation on the microbial fermentation of surfactin as long as it meets the requirements of the present application. For example, the microbial fermentation of surfactin can refer to the literature (Wang M, Yu H, Li X, et al. Single-gene regulated non-spore-forming Bacillus subtilis: Construction, transcriptome responses, and applications for producing enzymes and surfactin [J]. Metabolic Engineering, 2020, 62: 235-248.).

[0043]

[0044] The present application provides a surfactin derivative, which has a structural formula as shown in formula I:

[0045]

[0046] wherein R1 and R2 are groups modified by an amino acid;

[0047] The amino acid is any one of threonine, histidine, arginine, tryptophan, aspartic acid, leucine, isoleucine, valine, glutamic acid, phenylalanine, methionine, cysteine, tyrosine, alanine, glycine, proline, serine, or glutamine; R1 and R2 are the same or different, and R1 and R2 are not OH at the same time.

[0048] In some embodiments of the present application, the amino acid is any one of threonine, arginine, histidine, aspartic acid, leucine, valine, glutamic acid, alanine, glycine, serine, or glutamine.

[0049] In some embodiments of the present application, R1 and R2 are independently selected from:

[0050]

[0051] In some embodiments of the present application, R1 and R2 are independently selected from:

[0052]

[0053] In some embodiments of the present application, the surfactin derivative has one of the following structures:

[0054]

[0055] In some embodiments of the present application, R1 and R2 are the same.

[0056] In a specific embodiment of the present application, the positions corresponding to R1 and R2 groups are both modified by an amino acid to obtain a surfactin derivative, which has a structural formula as follows:

[0057] Table 1

[0058]

[0059]

[0060]

[0061]

[0062]

[0063] The present application provides a preparation method of the surfactin derivative, which comprises:

[0064] The surfactin shown in formula II, the activating agent, and the amino acid are dissolved in an organic solvent to react, so as to obtain the surfactin derivative.

[0065]

[0066] In the present application, the reaction conditions such as temperature, molar equivalent of activating agent and reactant can be adjusted by the person skilled in the art according to actual needs, so as to control the reaction process and reaction product, and achieve the purpose of the present application.

[0067] In some embodiments of the present application, the amino acid is 1-10 molar equivalents, preferably 4-6 molar equivalents, relative to 1 molar equivalent of the surfactin shown in formula II; for example, the amino acid can be 1 molar equivalent, 2 molar equivalents, 3 molar equivalents, 4 molar equivalents, 4.1 molar equivalents, 4.2 molar equivalents, 4.3 molar equivalents, 4.4 molar equivalents, 4.5 molar equivalents, 4.6 molar equivalents, 4.7 molar equivalents, 4.8 molar equivalents, 4.9 molar equivalents, 5 molar equivalents, 5.1 molar equivalents, 5.2 molar equivalents, 5.3 molar equivalents, 5.4 molar equivalents, 5.5 molar equivalents, 5.6 molar equivalents, 5.7 molar equivalents, 5.8 molar equivalents, 5.9 molar equivalents, 6 molar equivalents, 7 molar equivalents, 8 molar equivalents, 9 molar equivalents, 10 molar equivalents, or any range therebetween, relative to 1 molar equivalent of the surfactin shown in formula II. In this way, the reaction efficiency and product yield are further improved.

[0068] In the present application, molar equivalent refers to molar equivalent, which is used to describe the amount of substance involved in the reaction. It is usually used to represent the molar ratio of a certain substance to another substance in a chemical reaction. For example, when the surfactin is 1 mole, 2 molar equivalents of amino acid means 2 moles of amino acid.

[0069] In some embodiments of the present application, the activating agent is one or two or more of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDCI), dimethylaminopyridine (DMAP), dicyclohexylcarbodiimide (DCC), and diisopropylcarbodiimide (DIC). In this way, the activation performance of the activating agent is further improved.

[0070] In some embodiments of this application, the activator is 1 to 18 molar equivalents, preferably 4 to 6 molar equivalents, relative to 1 molar equivalent of the surfactant represented by Formula II; for example, relative to 1 molar equivalent of the surfactant represented by Formula II, the activator can be 1 molar equivalent, 2 molar equivalents, 3 molar equivalents, 4 molar equivalents, 5 molar equivalents, 6 molar equivalents, 7 molar equivalents, 8 molar equivalents, 9 molar equivalents, 10 molar equivalents, 11 molar equivalents, 12 molar equivalents, 13 molar equivalents, 14 molar equivalents, 15 molar equivalents, or any range thereof. This further improves the activation effect of the surfactant.

[0071] In some embodiments of this application, the organic solvent is selected from one or more of N,N-dimethylformamide (DMF), methanol, ethanol, and dimethyl sulfoxide (DMSO).

[0072] In some embodiments of this application, the reaction temperature is 20–50°C. For example, the reaction temperature can be 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, or any range thereof.

[0073] This application discloses the application of the aforementioned surfactant derivatives in oilfield development. These surfactant derivatives exhibit low surface tension, low critical micelle concentration, and excellent wetting reversal properties. As effective surfactant components in enhanced oil recovery (EOR) agents, they facilitate water wetting and penetration into the reservoir pores, thereby improving oil production efficiency. They also promote oil droplet coalescence and flow, further enhancing oil recovery. During tertiary oil recovery processes, these surfactant derivatives effectively clean crude oil from the reservoir rock surface, improving washing efficiency. Furthermore, these surfactant derivatives demonstrate strong resistance to high temperatures and salinity, excellent stress resistance, and strong adaptability to underground reservoir environments.

[0074] This application provides the application of the above-mentioned surfactant derivatives in the preparation of permeabilizers, fracturing fluids, reservoir waterproofing agents, oil well cleaning fluids, and displacement agents.

[0075] This application provides the application of the above-mentioned surfactant derivatives in reservoir waterproofing, improving oil recovery, and wellbore cleaning.

[0076] This application provides a bio-based surfactant comprising the above-mentioned surfactant derivative.

[0077] This application provides an oil recovery reagent comprising the aforementioned surfactant derivative. The oil recovery reagent according to embodiments of this application exhibits low surface tension, low critical micelle concentration (CMC), excellent wetting reversal properties, and strong resistance to high temperatures and high salt concentrations. It can be used as a highly efficient surfactant in oil extraction to enhance oil recovery.

[0078] The surface tension of the surfactant derivatives obtained after amino acid modification in this application is significantly reduced, exhibiting strong surface activity, a significantly decreased contact angle, increased hydrophilicity, reduced interfacial tension, and high recovery rate after microscopic displacement. For example, the surfactant derivatives obtained after modification with threonine, arginine, histidine, aspartic acid, leucine, valine, glutamic acid, alanine, glycine, serine, and glutamine have even better overall effects.

[0079] Example 1: A method for preparing a surfactant derivative, comprising the following steps:

[0080] The surfactant in this application is prepared by microbial fermentation, and its preparation is referenced in: Wang M, Yu H, Li X, et al. Single-gene regulated non-spore-forming Bacillus subtilis: Construction, transcriptome responses, and applications for producing enzymes and surfactin[J]. Metabolic Engineering, 2020, 62: 235-248. The synthetic chemical structure of the surfactant molecule is shown in Formula II.

[0081] Weigh 30 mM of surfactant molecular raw material and dissolve it in 20 mL of organic solvent. After stirring to dissolve, add 270 mM EDCI and stir the reaction at 25 °C. Then add 4 molar equivalents of threonine relative to the surfactant molecular raw material and stir the reaction for 9 h to terminate the reaction. The differences in organic solvents are shown in Table 1.

[0082] Transfer the reaction solution to a centrifuge tube, centrifuge, and remove the organic solvent. Redissolve the solution with an equal volume of aqueous solution, then add acid to adjust the pH to strongly acidic conditions, sonicate for 20 minutes, centrifuge, and finally dry to obtain the surfactant derivative.

[0083] The method for measuring surface tension is as follows:

[0084] When the instrument began testing, the surface tension of pure water was first measured, which was 72 mN / m, and this was designated as control group 1. Then, the surface tension of a 0.1% (w / w) surfactant derivative aqueous solution was measured using the same method. Three parallel tests were conducted, and the average value was recorded as the final surface tension value of the surfactant derivative aqueous solution at that concentration. The surface tension of unmodified surfactant molecules under the same conditions was determined to be 29.8 ± 0.5 mN / m, and this was designated as control group 2.

[0085] The surface tensions of the surfactant derivatives prepared by the applicant using different solvents are shown in Table 2.

[0086] Table 2

[0087] Serial number Solvent Surface tension (mN / m) Control 2 --- 29.8±0.5 S1 Methanol 15.6±0.3 S2 Ethanol 15.0±0.2 S3 Dimethyl sulfoxide (DMSO) 16.8±0.6 S4 N,N-dimethylformamide (DMF) 16.4±0.3

[0088] In organic solvents, condensation reactions can occur, and the surface tension of the obtained surfactant derivatives is superior to that of unmodified surfactant molecules.

[0089] Example 2

[0090] A method for preparing a surfactant derivative, comprising the following steps:

[0091] Weigh 30 mM of surfactant molecular raw material and dissolve it in 20 mL of dimethyl sulfoxide (DMSO). After stirring and dissolving, add 270 mM of activator and stir the reaction at 25 °C. Then add amino acids in an amount equivalent to 4 moles of surfactant molecular raw material, stir the reaction for 9 h, and then terminate the reaction. The differences in activators are shown in Table 3. Transfer the reaction solution to a centrifuge tube, centrifuge, and remove the organic solvent. Redissolve the surfactant with an equal volume of aqueous solution, then add acid to adjust the pH to strongly acidic conditions, sonicate for 20 min, centrifuge, and finally dry to obtain the surfactant derivative.

[0092] The method for determining the surface tension of surfactant derivatives is the same as in Example 1.

[0093] The surface tensions of the surfactant derivatives prepared by the applicant using different activators are shown in Table 3.

[0094] Table 3

[0095]

[0096]

[0097] In Table 3, T5 to T9 are mixtures of the two, with a molar ratio of 1:1 and a total of 270 mM.

[0098] When one or more of the activators DCC, DIC, EDCI, and DMAP are used to obtain surfactant derivatives, their surface tension is significantly reduced compared to unmodified surfactant molecules, exhibiting stronger surface activity. Furthermore, different types of activators affect the surface activity value of the new molecules, with the combination of EDCI / DMAP showing the best results.

[0099] Example 3

[0100] The preparation steps of threonine-modified surfactant derivatives are as follows:

[0101] Weigh 30 mM surfactant molecules and dissolve them in 20 mL of ethanol. After stirring and dissolving, add 270 mM EDCI and stir at 25 °C. Then add threonine in a certain molar equivalent to the surfactant molecules and stir for 9 h to terminate the reaction.

[0102] Transfer the reaction solution to a centrifuge tube, centrifuge, and remove the organic solvent. Redissolve the solution with an equal volume of aqueous solution, then add acid to adjust the pH to strongly acidic conditions, sonicate for 20 minutes, centrifuge, and finally dry to obtain the surfactant derivative.

[0103] The molar equivalents of threonine are shown in Table 4.

[0104] Table 4

[0105]

[0106]

[0107] The mass spectrum in Example 3 is shown below. Figures 1-4 The results show that this application synthesized a surfactant derivative.

[0108] The amount of threonine added has a significant impact on the performance of surfactant derivatives. The above threonine-modified surfactant derivatives were characterized using ESI-MS. The mass spectrometry results for threonine added at a concentration of 0.5 molar equivalent are shown in the appendix. Figure 1 , attached Figure 1 The mass-to-charge ratio (m / z) of 1109.69 corresponds to the ion peaks of R1 or R2, which are surfactant derivatives obtained after activation by threonine. Similarly, the mass spectrometry results for adding 1 molar equivalent of threonine are shown in the appendix. Figure 2 , attached Figure 2 The mass-to-charge ratio (m / z) of 1109.68 corresponds to the ion peaks of R1 or R2, which are surfactant derivatives obtained after activation by threonine. The mass spectrometry results for threonine addition at a 2 molar equivalent are shown in the appendix. Figure 3 , attached Figure 3 The mass-to-charge ratios (m / z) of 1109.69 and 1224.72 correspond to at least one of the ion peaks in R1 and R2, which are surfactant derivatives obtained after activation by threonine. The mass spectrometry results when the amount of threonine added is 4 molar equivalents are shown in the appendix. Figure 4 , attached Figure 4 The only value in the equation is the mass-to-charge ratio (m / z) 1224.72 ((M+2H) + The corresponding ion peaks for R1 and R2 indicate that both carboxyl groups in the surfactant are modified with threonine.

[0109] Example 4

[0110] Weigh 30 mM surfactant molecules and dissolve them in 20 mL of ethanol. After stirring and dissolving, add 270 mM EDCI and stir at 25 °C. Then add 4 molar equivalents of threonine relative to the surfactant molecules and stir for 9 h to terminate the reaction.

[0111] Transfer the reaction solution to a centrifuge tube, centrifuge, and remove the organic solvent. Redissolve the solution with an equal volume of aqueous solution, then add acid to adjust the pH to strongly acidic conditions, sonicate for 20 minutes, centrifuge, and finally dry to obtain the surfactant derivative.

[0112] The yield calculation method is as follows:

[0113] Yield = (Mass of product formed / Mass of reactants fed) × 100%

[0114] The surface tension value was measured using the same method as in Example 1.

[0115] The preparation methods for Examples 5 to 21 are the same as those for Example 4, with differences shown in Table 5. The methods for calculating the yield and measuring the surface tension are the same as those for Example 4.

[0116] Table 5

[0117]

[0118] As shown in Table 5, compared with the underived surfactants, the surface tension of the surfactant derivatives after amino acid modification is significantly reduced, exhibiting stronger surface activity.

[0119] Example 22 Wettability Evaluation

[0120] The steps for testing wettability are as follows:

[0121] Clean glass slides were aged in aging oil (shale oil XY4: kerosene: bitumen = 2:5:3) for more than one month at 60℃, and then used to evaluate the wettability of surfactant derivatives by measuring their contact angles. The surfactant derivatives prepared in Examples 1-11 were diluted with distilled water to prepare a 0.1% (w / w) aqueous solution. Before the experiment, excess crude oil on the surface of the aged glass slides was removed, and the slides were soaked in the surfactant derivative aqueous solution for 10 minutes and then dried. The contact angle was measured using an SCI6000E contact angle meter via the seated drop method. The volume of the water droplet injected for each test was 2 μL. The contact angle at a stable state was obtained using the instrument's built-in camera and angle measurement software over the test period. To ensure the accuracy and reliability of the experimental results, at least three sets of contact angles were tested for each sample, and the average value of multiple sets of data was taken as the contact angle value of the surfactant derivative.

[0122] Using this method, the contact angle of the underived surfactant was 25°, designated as control group 2, while the contact angle of pure water was 35°, designated as control group 1. The contact angle test results for the remaining surfactant derivatives are shown in Table 4.

[0123] Example 23: Temperature resistance evaluation.

[0124] The temperature resistance test procedure is as follows:

[0125] The surfactant derivative samples obtained in Examples 4-21 were placed in an oven at 121°C for 100 min. After the temperature dropped to room temperature, an aqueous solution with a mass concentration of 0.1% was prepared using distilled water. The surface tension value of this aqueous solution at 26°C was tested, and the remaining test steps for the surface tension value were the same as in Example 4.

[0126] The test results are shown in Table 6. The surface tension of the underived surfactant was 27-30 mN / m, and it was recorded as the control group. The surface tension of pure water was 72 mN / m. The results are shown in Table 6.

[0127] Table 6

[0128]

[0129]

[0130] As shown in Table 6, compared with the underived surfactants, the surfactant derivatives, after modification with various amino acids, exhibited significantly reduced contact angles and increased hydrophilicity. The surface tension values ​​of the surfactant derivatives in Examples 1-18 can be as low as 15-16 mN / m, and their surface activity is relatively stable, meaning that the surfactant derivatives are heat resistant to ≥120℃.

[0131] Example 24 Interfacial Tension Test

[0132] The surfactant derivatives prepared in Examples 4-21 were dissolved in distilled water to form a 0.1% (w / w) aqueous solution, and the interfacial tension was measured using a TX500C rotating drop interfacial tension meter. The internal phase crude oil in the test system was from Changqing Oilfield. The instrument temperature was set to 45℃, the drop rotation speed was 5000 rpm, and the interfacial tension value was recorded every 10 minutes for a total test duration of 2 hours. The test results are shown in Table 7. The interfacial tension of the underived surfactant was 2.9-3.1 mN / m, designated as control group 2. The interfacial tension of the pure water was 72 mN / m, designated as control group 1.

[0133] Table 7

[0134]

[0135]

[0136] As shown in Table 7, at the same concentration, the interfacial tension of unmodified surfactants is 2.9-3.1 mN / m, while after amino acid modification, the interfacial tension of surfactant derivatives can be reduced to 0.1-0.2 mN / m.

[0137] Example 25 Evaluation of Microscopic Displacement Effect

[0138] The experimental method for microscopic displacement is as follows:

[0139] Microscopic displacement experiments were conducted on the surfactant derivatives prepared in Examples 4-21. Saturated simulated oil (prepared from crude oil and kerosene in a specific ratio, with a viscosity of approximately 200 mPa·s) was injected into the microscopic model and aged at 90°C for 12 hours. To construct the microscopic displacement model, water displacement was first performed using a constant flow pump at a rate of 50 μL / min for 10 minutes. Then, surfactant derivatives (0.1% by mass) were injected at a rate of 25 μL / min for 30 minutes. After the set time, the displacement device was allowed to stand for 12 hours, and then the surfactant derivatives were injected again for 15 minutes at a rate of 120 μL / min.

[0140] After displacement was completed, the micro-recovery rate of the surfactant derivatives was calculated. The results are shown in Table 6. The recovery rate of the underived surfactant was 50%, designated as control group 2, and the recovery rate of the test pure water was 23%, designated as control group 1. The results are shown in Table 8.

[0141] Using this assay, the recovery rate after microscopic displacement of surfactant derivatives exceeded 60%, while the recovery rate after microscopic displacement of surfactant was approximately 50%. Compared to the recovery rate after microscopic displacement of surfactant, surfactant derivatives improved the recovery rate by about 10%, resulting in enhanced oil film stripping performance.

[0142] Table 8

[0143] Example Recovery rate (%) Example 4 70 Example 5 69 Example 6 68 Example 7 50 Example 8 67 Example 9 69 Example 10 52 Example 11 68 Example 12 69 Example 13 48 Example 14 51 Example 15 47 Example 16 50 Example 17 68 Example 18 69 Example 19 52 Example 20 70 Example 21 69 Control 1 (water) 23 Control 2 50

[0144] Using this assay, the recovery rate after microscopic displacement of surfactant derivatives was above 60%, while the recovery rate after microscopic displacement of surfactant was approximately 50%. Compared to the recovery rate after microscopic displacement of surfactant, surfactant derivatives increased the recovery rate by 10-20%, and improved the oil film stripping effect.

[0145] Example 26 Evaluation of Crude Oil Stripping Effect on Wall

[0146] The wall-mounted crude oil stripping effect of Examples 4-21 was evaluated, with sodium dodecyl sulfonate (SDS) and sodium cocoyl glycinate (YCO2) serving as control groups. Each surfactant derivative and the control group were prepared into 0.1% (w / w) aqueous solutions. First, quartz plates were incubated at 95°C for 24 hours. After cooling to room temperature, excess oil film on the quartz plate surface was removed, and the plates were immersed in the surfactant derivative aqueous solution (0.1% (w / w)) for 20 minutes. Then, the change in adhesion force between the oil film surface and the probe was tested in an aqueous environment using atomic force microscopy (FM-Nanoview Op-AFM) to obtain ZF curves. The improvement in wall-mounted crude oil stripping efficiency of each surfactant derivative compared to the two chemical surfactants was calculated. The results are shown in Table 9.

[0147] Table 9

[0148]

[0149]

[0150] As shown in Table 9, under the same conditions, the crude oil stripping rate of the surfactant derivative was more than 40% higher than that of the two chemical surfactants. The surfactant derivative exhibits higher efficiency in stripping oil films, which is beneficial for improving crude oil recovery.

[0151] Although the present invention has been disclosed above with reference to embodiments, it is not intended to limit the present invention. Anyone skilled in the art may make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope of the appended patent application.

Claims

1. A surfactant derivative, the structural formula of which is shown in Formula I: in, R1 and R2 are both groups modified by amino acids; The amino acid is any one of threonine, histidine, arginine, tryptophan, aspartic acid, leucine, isoleucine, valine, glutamic acid, phenylalanine, methionine, cysteine, tyrosine, alanine, glycine, proline, serine, and glutamine. R1 and R2 may be the same or different, and when R1 and R2 are different, OH is formed. Preferably, The amino acid is any one of threonine, arginine, histidine, aspartic acid, leucine, valine, glutamic acid, alanine, glycine, serine, and glutamine.

2. The surfactant derivative according to claim 1, wherein R1 and R2 are independently selected from: or -OH; Preferably, R1 and R2 are independently selected from: Or -OH.

3. The surfactant derivative according to claim 1, wherein R1 and R2 are the same.

4. A method for preparing the surfactant derivative according to any one of claims 1 to 3, comprising: The surfactant, activator, and amino acid shown in Formula II are dissolved in an organic solvent and reacted to obtain the surfactant derivative. Preferably, The amino acid is in the amount of 1 to 10 molar equivalents relative to the surfactant represented by Formula II, preferably 4 to 6 molar equivalents.

5. The method according to claim 4, wherein, The activator is one or more of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDCI), dimethylaminopyridine (DMAP), dicyclohexylcarbodiimide (DCC), and diisopropylcarbodiimide (DIC); Preferably, the activator is in the amount of 1 to 18 molar equivalents relative to 1 molar equivalent of the surfactant represented by Formula II, and more preferably 4 to 6 molar equivalents; More preferably, The organic solvent is selected from one or more of N,N-dimethylformamide (DMF), methanol, ethanol, and dimethyl sulfoxide (DMSO); More preferably, The reaction temperature is 20–50℃.

6. The application of the surfactant derivatives according to any one of claims 1 to 3, and the surfactant derivatives prepared by the method according to claims 4 to 5, in oilfield exploitation.

7. The application of the surfactant derivatives according to any one of claims 1 to 3, and the surfactant derivatives prepared by the method according to claims 4 to 5, in the preparation of permeabilizers, fracturing fluids, reservoir waterproofing agents, oil well cleaning fluids, and displacement agents.

8. The application of the surfactant derivatives according to any one of claims 1 to 3, and the surfactant derivatives prepared by the method according to claims 4 to 5, in reservoir waterproofing, improving oil recovery, and wellbore cleaning.

9. A bio-based surfactant comprising the surfactant derivative of any one of claims 1 to 3, or the surfactant derivative prepared by the method of claims 4 to 5.

10. An oil recovery reagent comprising the surfactant derivative of any one of claims 1 to 3, or the surfactant derivative prepared by the method of claims 4 to 5.

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