An acetylated glucamide surfactant for carbon dioxide flooding and its preparation method and application

Abstract

The present application relates to the field of oil field chemicals and carbon dioxide flooding enhanced oil recovery, disclose a kind of for carbon dioxide flooding to reduce mixed acetylated glucamide surfactant and its preparation method and application, the acetylated glucamide surfactant has the structural formula shown in formula (I):n is the integer of 5-17;The acetylated glucamide surfactant can significantly reduce the minimum miscibility pressure of carbon dioxide and crude oil;Formula (I).

Description

Technical Field

[0001] This invention relates to the fields of oilfield chemicals and carbon dioxide flooding enhanced oil recovery technology, specifically to an acetylated glucosamide surfactant for carbon dioxide flooding demixing, its preparation method, and its application. Background Technology

[0002] During oilfield development, even after using conventional methods to enhance oil recovery, a significant amount of residual oil remains underground. Carbon dioxide flooding is one of the effective techniques for enhancing oil recovery in low-permeability tight reservoirs during tertiary oil recovery, with its core advantage being the ability to achieve both greenhouse gas storage and increased oil and gas production. However, a high minimum miscibility pressure (MMP) generally exists between carbon dioxide and crude oil, making miscibility flooding difficult to achieve under actual reservoir pressure conditions, significantly reducing the oil displacement effect. To reduce the MMP, a common technical approach is to add surfactants and other miscibility-reducing agents to the carbon dioxide.

[0003] Currently, surfactants used for carbon dioxide flooding and miscibility reduction mainly include hydrocarbon-based surfactants, fluorinated surfactants, and silicone-based surfactants. Fluorinated and silicone-based surfactants have good effects in reducing MMP, but their application is limited by problems such as high synthesis costs and persistent environmental pollution. Conventional hydrocarbon-based surfactants, although lower in cost, have poor solubility and dispersibility in supercritical carbon dioxide, are prone to self-aggregation or precipitation, and are difficult to effectively migrate to the carbon dioxide / crude oil interface to exert their miscibility-reducing effect. Existing research shows that by compounding with cosolvents, the solubility and dispersibility of surfactants in carbon dioxide can be improved to some extent. However, the reported miscibility-reducing surfactants generally have insufficient solubility and dispersibility in carbon dioxide. At the same time, the synthesis routes of some products are complex and costly, making them unsuitable for large-scale oilfield applications. In addition, the reduction in minimum miscibility pressure is usually less than 30%, resulting in unsatisfactory effects.

[0004] Therefore, there is an urgent need to invent a carbon dioxide flooding and demixing system that has good solubility and dispersibility in carbon dioxide, significantly reduces MMP, has low synthesis cost, and is environmentally friendly. This is of great significance for promoting the development of carbon dioxide flooding technology in deep tight oil reservoirs. Summary of the Invention

[0005] The purpose of this invention is to overcome the problem that the surfactants used in carbon dioxide flooding have limited ability to reduce the minimum miscibility pressure in carbon dioxide. This invention provides an acetylated glucosamide surfactant for carbon dioxide flooding and its preparation method and application. This acetylated glucosamide surfactant can significantly reduce the minimum miscibility pressure between carbon dioxide and crude oil.

[0006] To achieve the above objectives, a first aspect of the present invention provides an acetylated glucosamide surfactant, wherein the acetylated glucosamide surfactant has the structural formula shown in formula (I): , formula (I); In equation (I), n is an integer between 5 and 17.

[0007] A second aspect of the present invention provides a method for preparing the aforementioned acetylated glucosamide surfactant, wherein the preparation method comprises: (1) D-(+)-gluconate δ-lactone is contacted with the fatty amine shown in formula (II) to carry out a ring-opening amidation reaction to obtain the intermediate product shown in formula (III); (2) In the presence of a catalyst, the intermediate product is contacted with an acetylation reagent to carry out an acetylation reaction; (3) The product after step (2) is eluted and dried to obtain the acetylated glucosamide surfactant shown in formula (I); Equation (II); Formula (III); , formula (I); In equations (I), (II), and (III), n is an integer between 5 and 17.

[0008] A third aspect of the present invention provides the application of the aforementioned acetylated glucosamide surfactant in reducing minimum miscibility pressure using carbon dioxide flooding.

[0009] The fourth aspect of the present invention provides an application of the aforementioned acetylated glucosamide surfactant and cosolvent compound in reducing minimum miscibility pressure during carbon dioxide flooding.

[0010] Through the above technical solution, the present invention has the following beneficial effects: (1) The acetylated glucosamide surfactant of the present invention can dissolve in supercritical carbon dioxide under low pressure, thereby reducing the minimum miscibility pressure; furthermore, the acetylated glucosamide surfactant of the present invention can dissolve in supercritical carbon dioxide in the presence of a cosolvent and under low pressure, thereby reducing the minimum miscibility pressure.

[0011] (2) The acetylated glucosamide surfactant can reduce the minimum miscibility pressure of Gulong shale oil and carbon dioxide by 42% at a high temperature of 110°C. Attached Figure Description

[0012] Figure 1This is the 1H NMR spectrum of the intermediate product obtained in Example 1 of this invention; Figure 2 This is the 1H NMR spectrum of the acetylated glucosamide surfactant prepared in Example 1 of this invention. Detailed Implementation

[0013] The endpoints and any values ​​of the ranges disclosed herein 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 the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0014] A first aspect of the present invention provides an acetylated glucosamide surfactant, wherein the acetylated glucosamide surfactant has the structural formula shown in formula (I): , formula (I); In equation (I), n is an integer between 5 and 17.

[0015] According to the present invention, in a preferred case, n is an integer from 5 to 15; in a more preferred case, n is an integer from 5 to 13; in an even more preferred case, n is an integer from 5 to 11; for example, in the present invention, it can specifically be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or any intermediate value of any two of the above values.

[0016] In this invention, the inventors discovered that: on the one hand, the acetylated glucosamide surfactant provided by this invention exhibits excellent dispersibility and interfacial activity in supercritical carbon dioxide systems through the synergistic effect between the glycosyl backbone, amide groups, and long-chain alkyl groups; on the other hand, due to its unique molecular structure design, the acetylated glucosamide surfactant effectively weakens intermolecular hydrogen bonding after hydroxyl acetylation, inhibits the self-aggregation behavior of the surfactant in the carbon dioxide system, and improves its solubility and dispersion ability in supercritical carbon dioxide. This allows it to significantly reduce the minimum miscibility pressure of the crude oil-carbon dioxide system even at low addition levels, thereby enhancing the mass transfer capacity between carbon dioxide and crude oil and improving crude oil recovery efficiency; furthermore, the acetylated glucosamide surfactant provided by this invention can also form a synergistic effect with alcohols or esters as co-solvents, further improving the demixing effect of the carbon dioxide flooding system.

[0017] Furthermore, the acetylated glucosamide surfactant has both a glycosyl backbone and ester structure derived from D-(+)-gluconic acid δ-lactone, and a hydrophobic long chain and amide structure derived from fatty amines. After acetylation, the overall polarity of the molecule is regulated, thus possessing both good carbon dioxide affinity and interfacial activity. It is superior to existing conventional surfactant systems in reducing minimum miscibility pressure, improving carbon dioxide mobility, and increasing oil recovery.

[0018] A second aspect of the present invention provides a method for preparing the aforementioned acetylated glucosamide surfactant, wherein the preparation method comprises: (1) D-(+)-gluconate δ-lactone is contacted with the fatty amine shown in formula (II) to carry out a ring-opening amidation reaction to obtain the intermediate product shown in formula (III); (2) In the presence of a catalyst, the intermediate product is contacted with an acetylation reagent to carry out an acetylation reaction; (3) The product after step (2) is eluted and dried to obtain the acetylated glucosamide surfactant shown in formula (I); Equation (II); Formula (III); , formula (I); In equations (I), (II), and (III), n is an integer between 5 and 17.

[0019] According to the present invention, in a preferred embodiment, the acetylated glucosamide surfactant is the product obtained by ring-opening amidation reaction of D-(+)-gluconic acid δ-lactone of formula (IV) and a fatty amine of formula (II) followed by acetylation reaction.

[0020] Formula (IV).

[0021] More preferably, the acetylated glucosamide surfactant is a surfactant obtained by reacting D-(+)-gluconic acid δ-lactone with dodecylamine via ring-opening amidation, followed by complete acetylation with acetic anhydride.

[0022] According to the present invention, preferably, the fatty amine represented by formula (II) is selected from one or more of acetylamine, octylamine, decylamine, dodecylamine, tetradecylamine, hexadecylamine, and octadecylamine; more preferably, the fatty amine represented by formula (II) is selected from one or more of acetylamine, dodecylamine, tetradecylamine, hexadecylamine, and octadecylamine.

[0023] According to the present invention, in a preferred embodiment, n is an integer from 5 to 15; in a more preferred embodiment, n is an integer from 5 to 13; and in an even more preferred embodiment, n is an integer from 5 to 11.

[0024] According to the present invention, in step (1), the molar ratio of the amount of D-(+)-gluconic acid δ-lactone to the fatty amine of formula (II) is (0.8-1.2):(0.8-1.5), preferably (1-1.1):(0.9-1.2); more preferably 1:(1-1.1).

[0025] In this invention, the fatty amine can be added to the D-(+)-gluconic acid δ-lactone solution by dropping, wherein the dropping rate is 2-6 mL / min, preferably 3-5 mL / min, to avoid excessive local concentration leading to side reactions.

[0026] According to the present invention, in step (1), the conditions for the ring-opening amidation reaction include: a reaction temperature of 40-120°C and a time of 2-24h; preferably, a reaction temperature of 60-90°C and a time of 4-12h; more preferably, a reaction temperature of 70-80°C and a time of 6-8h.

[0027] In this invention, the ring-opening amidation reaction is preferably carried out at a stirring rate of 300-700 r / min.

[0028] According to the present invention, in step (1), the ring-opening amidation reaction is further carried out in the presence of an organic solvent. Preferably, the organic solvent is selected from one or more of methanol, ethanol, isopropanol, tetrahydrofuran, dimethylformamide and dimethyl sulfoxide; preferably ethanol or tetrahydrofuran.

[0029] In this invention, the molar ratio of the amount of D-(+)-glucono-δ-lactone to the amount of the organic solvent is 1:(12-20).

[0030] According to the present invention, the preparation method further includes: in step (1), after the ring-opening amidation reaction is completed, the reaction solution is cooled to room temperature (e.g., 20-25°C) or lower (e.g., 5-10°C), and the generated glycosylamine intermediate crystallizes out from the reaction system; subsequently, the intermediate is obtained by filtration or centrifugation, and washed with an organic solvent to remove unreacted raw materials and impurities. Filtration or centrifugation can be performed using conventional methods in the art, and there are no particular limitations in the present invention.

[0031] According to the present invention, in step (2), preferably, the acetylation agent is selected from one or more of acetic anhydride, acetyl chloride and acetic acid; preferably, acetic anhydride.

[0032] According to the present invention, in step (2), the molar ratio of the intermediate product (glycosylamine intermediate) to the acetylation reagent is 1:(2-10), preferably 1:(3-8); more preferably 1:(4-6).

[0033] According to the present invention, in step (2), the conditions for the acetylation reaction include: a reaction temperature of 25-100°C and a time of 1-24h; preferably, a reaction temperature of 40-80°C and a time of 6-24h; more preferably, a reaction temperature of 50-70°C and a time of 12-24h.

[0034] According to the present invention, in step (2), the acetylation reaction is further carried out in the presence of an organic solvent. Preferably, the organic solvent is selected from one or more of methanol, ethanol, isopropanol, tetrahydrofuran, dimethylformamide and dimethyl sulfoxide; preferably ethanol or tetrahydrofuran.

[0035] In this invention, the amount of the intermediate product (glycosylamine intermediate) used is 0.015-0.03 mol relative to 50 mL of organic solvent.

[0036] According to the present invention, the acetylation reaction can be carried out in the presence of a catalyst, wherein the catalyst is selected from one or more of pyridine, cesium carbonate, triethylamine, etc.

[0037] In this invention, the molar ratio of the intermediate product (glycosylamine intermediate) to the catalyst is 1:(0.1-0.8), preferably 1:(0.2-0.7); more preferably 1:(0.2-0.6).

[0038] According to the present invention, the preparation method further includes: after step (2) is completed, the reaction solution is subjected to desolventization treatment under reduced pressure, and washed and purified with ethyl acetate, petroleum ether or dichloromethane to remove unreacted raw materials and by-products.

[0039] According to the present invention, in step (3), the drying process includes vacuum drying or freeze drying; preferably, the vacuum drying temperature is 40-60°C and the time is 12-24h; or the freeze drying temperature is -50°C to -85°C and the time is 24-48h.

[0040] According to the present invention, the synthesis method of the present invention is not only mild in reaction conditions, widely available in raw materials, and has few side reactions, but also simple in post-processing. The resulting acetylated glucosamide surfactant has a glycosyl skeleton, amide structure, acetyl group and hydrophobic long chain, which can effectively weaken the intermolecular hydrogen bonding, inhibit the aggregation behavior of surfactant in supercritical carbon dioxide, and improve its dispersibility and interfacial activity in carbon dioxide system. It is a novel carbon dioxide demixing and oil displacement surfactant material.

[0041] A third aspect of the present invention provides the application of the aforementioned acetylated glucosamide surfactant in reducing minimum miscibility pressure using carbon dioxide flooding.

[0042] The fourth aspect of the present invention provides an application of the aforementioned acetylated glucosamide surfactant and cosolvent compound in reducing minimum miscibility pressure during carbon dioxide flooding.

[0043] According to the present invention, the cosolvent is an alcohol or an ester; preferably, the alcohol includes one or more of anhydrous ethanol, methanol and pentanol; preferably, the ester includes one or more of ethyl acetate, methyl acetate and ethyl hexanoate.

[0044] According to the present invention, the weight ratio of the acetylated glucosamide surfactant, the cosolvent, and the carbon dioxide is as follows: the weight ratio of carbon dioxide, acetylated glucosamide surfactant, and cosolvent can be 100:(0.1-0.5):(1-5), preferably 100:(0.1-0.5):(3-5); more preferably 100:(0.3-0.5):(4-5).

[0045] The present invention will be described in detail below through embodiments.

[0046] In the following examples and comparative examples: The method for testing minimum miscibility pressure (MMP) involves determining the interfacial tension between the shale oil and CO2 composite system using the pendant drop method, and then determining the minimum miscibility pressure based on the interfacial tension disappearance method. Specifically, a DSA100 interfacial tensiometer (Krüss, Germany) is used for testing. During the test, the shale oil and CO2 composite system are placed in two separate intermediate containers and injected into a visualization autoclave using an ISCO high-pressure pump. The shale oil forms suspended droplets in the autoclave, surrounded by the CO2 composite system as a continuous phase. The interfacial tension test cell is equipped with a sapphire window, a light source, and a high-resolution camera to observe and record the droplet profile changes in real time under high pressure. During the experiment, a constant test temperature is maintained using a temperature control system to ensure the accuracy and repeatability of the measurement results. As the system pressure gradually increases, the morphological changes of the shale oil droplets under different pressure conditions are recorded, and the corresponding interfacial tension values ​​are calculated. When the pressure increases to the point where shale oil droplets can no longer form stable, clear suspended droplets, and the oil phase and CO2 composite system reach a completely miscible state, this pressure is defined as the minimum miscibility pressure of the shale oil / CO2 composite system, at which point the corresponding interfacial tension is 0 mN·m. -1 .

[0047] Molecular structural parameters were determined by infrared spectroscopy. The infrared spectrometer was purchased from ABB Corporation, USA, and its model was FTLA2000-104. Molecular structural parameters were determined by proton nuclear magnetic resonance (NMR) spectrometry. The NMR spectrometer was purchased from Bruker, Switzerland, and its model was Avance300. D-(+)-gluconolactone is a commercially available product of Shanghai Aladdin Biochemical Technology Co., Ltd. Octylamine is a commercially available product of Shanghai Maclean Biochemical Technology Co., Ltd. Decanylamine is a commercially available product of Shanghai Maclean Biochemical Technology Co., Ltd. Dodecylamine is a commercially available product of Shanghai Maclean Biochemical Technology Co., Ltd. Tetradecylamine is a commercially available product of Shanghai Maclean Biochemical Technology Co., Ltd. Hexadecylamine is a commercially available product of Shanghai Maclean Biochemical Technology Co., Ltd. Acetic anhydride is a commercially available product under the brand name of Sinopharm Chemical Reagent Co., Ltd. The ethyl acetate raw material is a commercially available product under the brand name of Sinopharm Chemical Reagent Co., Ltd. The anhydrous ethanol raw material is a commercially available product from Sinopharm Chemical Reagent Co., Ltd., brand name [brand name missing]. Methanol is a commercially available product from Sinopharm Chemical Reagent Co., Ltd., under the brand name [brand name missing]. Isopropanol is a commercially available product from Sinopharm Chemical Reagent Co., Ltd., under the brand name [brand name missing]. Tetrahydrofuran is a commercially available product of Sinopharm Chemical Reagent Co., Ltd., under the brand name [brand name missing]. Petroleum ether is a commercially available product of Sinopharm Chemical Reagent Co., Ltd., under the brand name [brand name missing].

[0048] Example 1 This embodiment illustrates the preparation of an acetylated glucosamide surfactant using the method of the present invention.

[0049] The synthetic route for preparing acetylated glucosamide surfactant in this embodiment includes: (1) (2)

[0051] Specific preparation methods include: (1) First, D-(+)-glucono-δ-lactone (15 g, i.e., 0.08 mol) was dissolved in anhydrous ethanol (50 g, i.e., 1.08 mol). While stirring at a stirring rate of 500 r / min, dodecylamine (15.6 g, i.e., 0.08 mol) was added dropwise to the above solution at a dropping rate of 4 mL / min. The reaction was carried out at 75 °C for 8 h. After the reaction was completed, the reaction solution was cooled to room temperature, and then further cooled to 5 °C. After a large amount of white solid precipitated in the system, intermediate product A was obtained by vacuum filtration. The obtained solid was washed three times with ethanol and dried under vacuum at 50 °C for 12 h to obtain white powdery glycosylamine intermediate product A, labeled as GL-12.

[0052] (2) The obtained intermediate product A (10.00 g, i.e., 0.028 mol) was added to anhydrous tetrahydrofuran (50 mL), and acetic anhydride (15.31 g, i.e., 0.15 mol) was added under stirring conditions at a stirring rate of 600 r / min. Triethylamine (1.5 g, i.e., 0.015 mol) was added as a catalyst, and the reaction was carried out at 60 °C for 18 h.

[0053] (3) After the reaction was completed, the solvent and unreacted acetic anhydride were removed by rotary evaporation under reduced pressure. The product was then washed and purified three times with ethyl acetate and petroleum ether to remove unreacted raw materials and byproducts. The product was then placed in a vacuum drying oven and dried under vacuum at 50°C for 24 h to obtain a brownish-yellow, high-viscosity, oily acetylated glucosamide surfactant, labeled AC-GL-12, where n corresponds to the acetylated glucosamide surfactant shown in formula (I), and n is 11.

[0054] Figure 1 This is the 1H NMR spectrum of the intermediate product obtained in Example 1 of this invention; from Figure 1 It can be observed that GL-12 exhibits a characteristic signal of amide protons at approximately δ 7.8 ppm, indicating that GL forms an amide bond after reacting with dodecylamine. Simultaneously, multiple signals are observed in the δ range of 3.3-5.0 ppm, mainly attributed to the hydroxyl protons in the gluconic acid chain and the protons on their adjacent carbon atoms. The strong peak at Δ 1.2-1.4 ppm corresponds to the methylene proton in the dodecyl chain, and the peak near δ 0.85 ppm corresponds to the terminal methyl proton. These characteristic peaks indicate that the GL-12 molecule simultaneously possesses a gluconic acid backbone and a long alkyl chain structure, demonstrating the successful synthesis of GL-12.

[0055] Figure 2 This is the 1H NMR spectrum of the acetylated glucosamide surfactant prepared in Example 1 of this invention; from Figure 2It can be observed that the hydroxyl-related signal in AC-GL-12 significantly weakens in the δ range of 3.3-5.0 ppm, while a new strong peak appears in the δ range of 1.9-2.2 ppm, which is attributed to the methyl proton in the acetyl group. According to the spectrum integration results, this region corresponds to approximately 15 protons, indicating that 5 acetyl groups have been introduced into the molecule, demonstrating that the hydroxyl group in GL-12 has been effectively acetylated. Furthermore, AC-GL-12 still retains the amide proton signal and characteristic peaks of the long alkyl chain, indicating that the acetylation process did not destroy the amide bond or dodecyl chain structure.

[0056] Example 2 This embodiment illustrates the preparation of an acetylated glucosamide surfactant using the method of the present invention.

[0057] The acetylated glucosamide surfactant was prepared using the same method as in Example 1, except that in step (1), "dodecylamine" was replaced with "hexylamine".

[0058] As a result, the acetylated glucosamide surfactant shown in formula (I) was prepared, where n is 5.

[0059] Example 3 This embodiment illustrates the preparation of an acetylated glucosamide surfactant using the method of the present invention.

[0060] The acetylated glucosamide surfactant was prepared using the same method as in Example 1, except that in step (1), "dodecylamine" was replaced with "tetradecylamine".

[0061] As a result, the acetylated glucosamide surfactant shown in formula (I) was prepared, where n is 13.

[0062] Example 4 This embodiment illustrates the preparation of an acetylated glucosamide surfactant using the method of the present invention.

[0063] The acetylated glucosamide surfactant was prepared using the same method as in Example 1, except that in step (1), "dodecylamine" was replaced with "hexadecylamine".

[0064] As a result, the acetylated glucosamide surfactant shown in formula (I) was prepared, where n is 15.

[0065] Example 5 This embodiment illustrates the preparation of an acetylated glucosamide surfactant using the method of the present invention.

[0066] The acetylated glucosamide surfactant was prepared using the same method as in Example 1, except that in step (1), "dodecylamine" was replaced with "octadecylamine".

[0067] As a result, the acetylated glucosamide surfactant shown in formula (I) was prepared, where n is 17.

[0068] Example 6 This embodiment illustrates the preparation of an acetylated glucosamide surfactant using the method of the present invention.

[0069] The acetylated glucosamide surfactant was prepared using the same method as in Example 1, except that in step (1), "dodecylamine" was replaced with "octylamine".

[0070] As a result, the acetylated glucosamide surfactant shown in formula (I) was prepared, where n is 7.

[0071] Example 7 This embodiment illustrates the preparation of an acetylated glucosamide surfactant using the method of the present invention.

[0072] The acetylated glucosamide surfactant was prepared using the same method as in Example 1, except that in step (1), "dodecylamine" was replaced with "decylamine".

[0073] As a result, the acetylated glucosamide surfactant shown in formula (I) was prepared, where n is 9.

[0074] Comparative Example 1 The acetylated glucosamide surfactant was prepared using the same method as in Example 1, except that in step (1), "dodecylamine" was replaced with "pentylamine".

[0075] As a result, the acetylated glucosamide surfactant shown in formula (I) was prepared, where n is 4.

[0076] Comparative Example 2 The acetylated glucosamide surfactant was prepared using the same method as in Example 1, except that in step (1), "dodecylamine" was replaced with "eicosamine".

[0077] As a result, the acetylated glucosamide surfactant shown in formula (I) was prepared, where n is 19.

[0078] Comparative Example 3 A polyether surfactant is used, specifically dodecyl alcohol random polyether, also known as lauryl alcohol random polyether or dodecyl alcohol polyoxyethylene polyoxypropylene ether. In this invention, it is commercially available, with the trade code CPE-1500 and a molecular weight of 1500, purchased from Haian Petrochemical Plant in Jiangsu Province.

[0079] Comparative Example 4 A polyether surfactant is used, specifically butanol random polyether, which belongs to the n-butanol polyoxyethylene polyoxypropylene ether, BPE series. In this invention, it is commercially available, with the trade code BPE-1500 and a molecular weight of 1500, purchased from Haian Petrochemical Plant in Jiangsu Province.

[0080] Comparative Example 5 A polyether surfactant is used, specifically glycerol random polyether, which belongs to the glycerol random polyether, GPE series. In this invention, it is commercially available, with the trade code GPE-3000 and a molecular weight of 3000, purchased from Haian Petrochemical Plant in Jiangsu Province.

[0081] Application Example 1 This application example illustrates the effect of the acetylated glucosamide surfactant prepared in Example 1 of the present invention on reducing the minimum miscibility pressure of the carbon dioxide-crude oil system.

[0082] First, the acetylated glucosamide surfactant prepared in Example 1 was added to an intermediate container. Then, carbon dioxide was introduced into the intermediate container and pressurized to a supercritical state, allowing the surfactant to fully dissolve and disperse in the supercritical carbon dioxide system (the mass ratio of carbon dioxide to acetylated glucosamide surfactant was 1:0.005). Next, the mixed system was pressurized and introduced into a high-pressure interfacial tension measuring instrument, placing the test chamber in a carbon dioxide atmosphere. Gulong shale oil was then added using a spin-drop method to test the changes in interfacial tension of the carbon dioxide-crude oil system under different pressure conditions.

[0083] The minimum miscibility pressure (MMP) of the system was determined using the interfacial tension disappearance method. The results showed that, compared with the pure carbon dioxide flooding system, the acetylated glucosamide surfactant prepared in Example 1 could reduce the minimum miscibility pressure of the carbon dioxide-Gulong shale oil system by 17.9%, indicating that the surfactant can effectively improve the interfacial interaction between carbon dioxide and crude oil.

[0084] Application Example 2-7 The surfactants prepared in Examples 2-7 were tested using the same method as in Application Example 1 to reduce the minimum miscibility pressure of the carbon dioxide-crude oil system. The results are shown in Table 1.

[0085] Compare and contrast examples 1-5 The surfactants prepared in Comparative Examples 1-5 were tested using the same method as in Application Example 1 to reduce the minimum miscibility pressure of the carbon dioxide-crude oil system. The results are shown in Table 1.

[0086] Table 1

[0087] Application Example 8 This application example illustrates the synergistic effect of the acetylated glucosamide surfactant prepared in Example 1 and the anhydrous ethanol compound system on reducing the minimum miscibility pressure of the carbon dioxide-crude oil system.

[0088] First, the acetylated glucosamide surfactant obtained in Example 1 was added to an intermediate container along with anhydrous ethanol. Then, carbon dioxide was introduced into the intermediate container and pressurized to a supercritical state, allowing the surfactant, co-solvent anhydrous ethanol, and supercritical carbon dioxide to fully mix and form a homogeneous system (the mass ratio of carbon dioxide, acetylated glucosamide surfactant, and co-solvent was 1:0.005:0.05). Next, the resulting mixture was pressurized and introduced into a high-pressure interfacial tension measuring instrument, placing the test chamber in a carbon dioxide atmosphere. Gulong shale oil was then added using a spin-drop method to test the changes in interfacial tension of the carbon dioxide-crude oil system under different pressure conditions.

[0089] The minimum miscibility pressure (MMP) of the system was determined using the interfacial tension disappearance method. The results showed that, compared with the pure carbon dioxide flooding system, the combination of acetylated glucosamide surfactant and anhydrous ethanol could reduce the minimum miscibility pressure of the carbon dioxide-Gulong shale oil system by 42.9%, which was significantly better than the demixing effect of using surfactant or anhydrous ethanol alone.

[0090] Application Example 9-14 The surfactants prepared in Examples 2-7 were tested using the same method as in Application Example 8 to reduce the minimum miscibility pressure of the carbon dioxide-crude oil system. The results are shown in Table 2.

[0091] Compare and contrast with example 6-10 The surfactants prepared in Comparative Examples 1-5 were tested using the same method as in Application Example 8 to reduce the minimum miscibility pressure of the carbon dioxide-crude oil system. The results are shown in Table 2.

[0092] Comparative Application Example 11 This comparative application example illustrates the effect of anhydrous ethanol on reducing the minimum miscibility pressure of a carbon dioxide-crude oil system.

[0093] First, anhydrous ethanol was added to an intermediate container. Then, carbon dioxide was introduced into the intermediate container and pressurized to bring the carbon dioxide to a supercritical state, ensuring thorough mixing of the anhydrous ethanol and supercritical carbon dioxide. Next, the resulting mixture was pressurized and introduced into a high-pressure interfacial tension measuring instrument, immersing the test chamber in a carbon dioxide atmosphere. Gulong shale oil was then added using a spin-drop method to test the changes in interfacial tension of the carbon dioxide-crude oil system under different pressure conditions.

[0094] The minimum miscibility pressure (MMP) of the system was determined using the interfacial tension disappearance method. The results showed that anhydrous ethanol could reduce the minimum miscibility pressure of the carbon dioxide-Gulong shale oil system by 21.4% compared with the pure carbon dioxide flooding system. The results are shown in Table 2. This indicates that ethanol, as a co-solvent, can enhance the interaction between carbon dioxide and crude oil and improve the dissolution and extraction capabilities of carbon dioxide for crude oil.

[0095] Table 2

[0096] As can be seen from the above results, the inventors believe that the reason is that anhydrous ethanol can improve the dispersibility of surfactants in supercritical carbon dioxide and weaken their aggregation behavior, while acetylated glucosamide surfactants can further reduce the interfacial tension between carbon dioxide and crude oil. The two form a synergistic effect, thereby significantly improving the mass transfer efficiency and miscibility between carbon dioxide and crude oil.

[0097] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An acetylated glucosamide surfactant, characterized in that, The acetylated glucosamide surfactant has the structural formula shown in formula (I): Equation (I); In equation (I), n is an integer between 5 and 17.

2. The acetylated glucosamide surfactant according to claim 1, wherein, n is an integer from 5 to 15; preferably, n is an integer from 5 to 13; more preferably, n is an integer from 5 to 11.

3. A method for preparing the acetylated glucosamide surfactant according to claim 1 or 2, characterized in that, The preparation method includes: (1) D-(+)-gluconate δ-lactone is contacted with the fatty amine shown in formula (II) to carry out a ring-opening amidation reaction to obtain the intermediate product shown in formula (III); (2) In the presence of a catalyst, the intermediate product is contacted with an acetylation reagent to carry out an acetylation reaction; (3) The product after step (2) is eluted and dried to obtain the acetylated glucosamide surfactant shown in formula (I); Equation (II); Formula (III); Equation (I); In equations (I), (II), and (III), n is an integer between 5 and 17.

4. The preparation method according to claim 3, wherein, The fatty amine represented by formula (II) is selected from one or more of octylamine, decylamine, dodecylamine, tetradecylamine and hexadecylamine, preferably dodecylamine; And / or, the acetylation agent is selected from one or more of acetic anhydride, acetyl chloride and acetic acid, preferably acetic anhydride; And / or, the catalyst is selected from one or more of pyridine, cesium carbonate and triethylamine, preferably triethylamine.

5. The preparation method according to claim 3, wherein, In step (1), the conditions for the ring-opening amidation reaction include: a reaction temperature of 40-120°C and a time of 2-24 h; preferably, a reaction temperature of 60-90°C and a time of 4-12 h. And / or, the ring-opening amidation reaction is carried out at a stirring rate of 300-700 r / min; And / or, in step (2), the conditions for the acetylation reaction include: a reaction temperature of 25-100°C and a time of 1-24 h; preferably, a reaction temperature of 40-80°C and a time of 6-24 h; And / or, in step (3), the drying process includes vacuum drying or freeze drying; Preferably, the vacuum drying conditions include: a temperature of 40-60°C and a time of 12-24 h; Preferably, the freeze-drying conditions include a temperature of -50°C to -85°C and a time of 24-48 h.

6. The preparation method according to claim 3, wherein, In step (1), the molar ratio of the D-(+)-gluconic acid δ-lactone to the fatty amine shown in formula (II) is (0.8-1.2):(0.8-1.5), preferably (1-1.1):(0.9-1.2); more preferably 1:(1-1.1). And / or, in step (2), the molar ratio of the intermediate product to the acetylation reagent is 1:(2-10), preferably 1:(3-8); more preferably 1:(4-6). And / or, in step (2), the molar ratio of the intermediate product to the catalyst is 1:(0.1-0.8), preferably 1:(0.2-0.7); more preferably 1:(0.2-0.6).

7. The preparation method according to any one of claims 3-6, wherein, The preparation method further includes being carried out in the presence of an organic solvent; Preferably, the organic solvent is selected from one or more of methanol, ethanol, isopropanol, tetrahydrofuran, dimethylformamide, and dimethyl sulfoxide; preferably ethanol or tetrahydrofuran.

8. The use of the acetylated glucosamide surfactant of claim 1 or 2 in reducing minimum miscibility pressure by carbon dioxide drive.

9. The application of the acetylated glucosamide surfactant and cosolvent compound according to claim 1 or 2 in reducing minimum miscibility pressure in carbon dioxide drive.

10. The application according to claim 9, wherein, The co-solvent is an alcohol or an ester; Preferably, the alcohols include one or more of anhydrous ethanol, methanol, and pentanol; Preferably, the esters include one or more of ethyl acetate, methyl acetate, and ethyl hexanoate; And / or, the weight ratio of the acetylated glucosamide surfactant, cosolvent, and carbon dioxide is 100:(0.1-0.5):(1-5), preferably 100:(0.1-0.5):(3-5), and more preferably 100:(0.3-0.5):(4-5).

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