PPO / PEO block Gemini stretchable surfactant suitable for high-temperature and high-salinity oil reservoirs and its preparation method

Abstract

This invention relates to the field of surfactant preparation technology, specifically to a PPO / PEO block Gemini extensible surfactant suitable for high-temperature, high-salinity reservoirs and its preparation method. The surfactant uses fatty alcohols as starting materials, and undergoes stepwise addition with propylene oxide (PO) and ethylene oxide (EO) via a potassium hydroxide / 18-crown ether-6 catalytic system to obtain the APOnEOm intermediate. This intermediate is then esterified with a polyethylene glycol bismaleic acid ester linker, and finally sulfonated with sodium bisulfite to obtain sodium polyethylene glycol bismaleic acid diester sulfonate (T-APOnEOm-S). By controlling the PPO / PEO block ratio, the product exhibits excellent temperature and salt resistance, making it suitable for high-temperature, high-salinity reservoirs, and also possesses strong emulsifying ability, reducing the oil-water interfacial tension to 10. ‑3 The product has a strength in the mN / m range, significantly improving oil recovery. The preparation process is mild, and the product properties are adjustable, making it valuable for applications in tertiary oil recovery.

Description

Technical Field

[0001] This invention relates to the field of surfactant preparation technology, specifically to a PPO / PEO block Gemini extensible surfactant suitable for high-temperature and high-salinity oil reservoirs and its preparation method. Background Technology

[0002] Surfactants are a core component of chemical flooding enhanced oil recovery (EOR) technology, exhibiting superior performance in processes such as alkali-surfactant-polymer flooding (ASP) and surfactant-polymer flooding (SP). Surfactants significantly improve oil displacement efficiency and thus substantially increase oil recovery by reducing oil-water interfacial tension, altering rock wettability, and promoting crude oil emulsification and solubilization. Compared to traditional waterflooding, surfactant flooding can increase oil recovery by more than 20%. As secondary oil recovery enters its later stages, chemical flooding technology is expanding from oilfields with reservoir temperatures <50℃ and salinity <1000 mg / L to high-temperature, high-salinity reservoirs, placing higher demands on the performance of surfactants.

[0003] Anionic surfactants, including sulfonates, sulfates, and carboxylates, are most widely used in enhancing oil recovery in conventional reservoirs. Among them, carboxylates, with their carboxylic acid group structure, not only possess natural biodegradability and environmental friendliness but also exhibit good foaming, wetting, and emulsifying properties. However, due to the carboxylic acid group's tendency to precipitate with metal ions and its poor chemical bond stability, they suffer from poor solubility and salt tolerance, and are easily decomposed under strong acid, strong alkali, and high-temperature environments. Sulfate surfactants, with their strongly hydrophilic sulfate ester groups, exhibit excellent interfacial activity, foaming properties, wetting reversal, and emulsifying stability. However, high concentrations of salt ions can shield their charge, disrupt micelle stability, and readily react with calcium... 2+ / Mg 2+ Precipitation occurs, and the SO bonds in sulfate esters are highly polar and have low bond energy, making them prone to hydrolysis and failure at high temperatures. This results in insufficient temperature and salt resistance of sulfate surfactants. Therefore, the optimal development of highly efficient surfactants is key to improving EOR (Excessive Oxidation Rate).

[0004] Compared to other types of surfactants, sulfonate surfactants are unique because of the presence of -SO3 in their molecular structure. -Linked by chemical bonds, these surfactants possess rigid sulfonic acid groups, exhibiting high chemical stability, high interfacial activity, efficient wetting reversal, good emulsification and solubilization capabilities, and strong resistance to acids, alkalis, and temperatures, thus meeting the requirements of tertiary oil recovery technology. However, in high-salt environments, the strong electrostatic interaction between salt ions and sulfonic acid groups can cause surfactant molecules to precipitate or form insoluble precipitates, reducing their salt tolerance and making it difficult to meet the exploitation requirements of high-salinity reservoirs. This limits the application of such surfactants in extreme reservoir environments. Therefore, conventional surfactants cannot adapt to high-temperature and high-salt reservoir environments, necessitating the development of novel surfactants. To address this issue, existing technologies (such as patent CN102040994B) propose solutions using aminosulfonic acid-type amphoteric surfactants in combination, but these combination systems still suffer from poor compatibility and uncontrollable synergistic effects. Summary of the Invention

[0005] This invention aims to solve the technical problem of insufficient temperature and salt resistance in existing surfactants during oil extraction, which limits the improvement of oil recovery. It provides a Gemini-type surfactant with excellent temperature and salt resistance. This surfactant maintains ultra-low interfacial tension (on the order of 10⁻³ mN / m) even at 70°C in a high-saltification environment with 9.0% NaCl. The surfactant series developed in this invention not only significantly improves oil recovery but also breaks through the performance bottleneck of traditional surfactants in high-temperature and high-salt environments, achieving a synergistic improvement in both temperature resistance and salt resistance.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A method for preparing PPO / PEO block Gemini stretchable surfactants suitable for high-temperature and high-salinity reservoirs includes the following steps:

[0008] (1) Preparation of APOnEOm: Fatty alcohol is used as a starting material and added to a polymerization reactor. Potassium hydroxide is added as a catalyst and 18-crown ether-6 is added as a complexing agent to carry out propoxylation reaction or propoxylation reaction and ethoxylation reaction to prepare fatty alcohol polyoxypropylene polyoxyethylene ether APOnEOm, where n is 3-30 and m is 0-30; the fatty alcohol includes any one of n-octanol, n-decanol, dodecanol, tetradecylol, and hexadecylol;

[0009] (2) Preparation of linking groups: Maleic anhydride and polyethylene glycol were mixed, anhydrous sodium acetate was added as a catalyst, and the mixture was heated and stirred to obtain linking groups;

[0010] (3) Preparation of T-APOnEOm: The fatty alcohol polyoxypropylene polyoxyethylene ether APOnEOm and the linker are mixed, p-toluenesulfonic acid is added as a catalyst, and molecular sieve is added as a dehydrating agent. The mixture is stirred and reacted in a negative pressure environment to obtain polyethylene glycol bismaleic acid diester T-APOnEOm.

[0011] (4) Preparation of T-APOnEOm-S: The polyethylene glycol bismaleic acid diester T-APOnEOm is mixed with sodium bisulfite aqueous solution, and hexadecyltrimethylammonium bromide is added as a catalyst. The mixture is stirred and reacted to obtain the target product, polyethylene glycol bismaleic acid diester sodium sulfonate, which is a PPO / PEO block Gemini stretching surfactant suitable for high temperature and high salt reservoirs.

[0012] Furthermore, in step (1):

[0013] When m=0, fatty alcohol is used as the starting material and added to the polymerization reactor. Potassium hydroxide is added as a catalyst and 18-crown ether-6 is added as a complexing agent. Propylene oxide is added at 130℃-135℃ to carry out the propoxylation reaction; APOn is prepared.

[0014] When m is 1-30, fatty alcohol is added to the polymerization reactor as the starting material, potassium hydroxide is added as a catalyst, and 18-crown ether-6 is added as a complexing agent. Propylene oxide is added at 130℃-135℃ to carry out the propoxylation reaction; ethylene oxide is added at 125℃-130℃ to carry out the ethoxylation reaction, and fatty alcohol polyoxypropylene polyoxyethylene ether APOnEOm is prepared.

[0015] Furthermore, the mass of potassium hydroxide added is 3‰-5‰ of the total mass of fatty alcohol and propylene oxide;

[0016] The molar ratio of added 18-crown ether-6 to added potassium hydroxide is (1.00-2.00):1.00;

[0017] The molar ratio of added propylene oxide to fatty alcohol is (3.00-30.00):1.00;

[0018] The molar ratio of added ethylene oxide to fatty alcohol is (0.00-30.00):1.00.

[0019] Further, step (2) specifically involves adding maleic anhydride and polyethylene glycol in a molar ratio of (2.00-3.00):1.00 into a flask, adding anhydrous sodium acetate as a catalyst, and stirring at 90-100°C for 1.0-1.2 hours to obtain the linker group;

[0020] The mass of anhydrous sodium acetate added is 1.0%-2.0% of the total mass of maleic anhydride and polyethylene glycol.

[0021] Further, step (3) specifically involves: adding the fatty alcohol polyoxypropylene polyoxyethylene ether APOnEOm and the linker in a molar ratio of (2.00-3.00):1.00 into a flask, adding p-toluenesulfonic acid as a catalyst, and adding molecular sieve as a dehydrating agent, and stirring at 140-150℃ in an environment of -0.7MPa to -1.0MPa for 7-8 hours to obtain polyethylene glycol bismaleic acid diester T-APOnEOm;

[0022] The amount of p-toluenesulfonic acid added is 1.0%-3.0% of the total mass of the linker and APOnEOm;

[0023] Furthermore, the molecular screening uses any one or more of 3A molecular sieves, 4A molecular sieves, and 5A molecular sieves.

[0024] Furthermore, step (4) specifically involves:

[0025] The polyethylene glycol bismaleic acid diester T-APOnEOm prepared in step (3) was added to a flask with sodium bisulfite aqueous solution at a molar ratio of 1.00:(2.00-4.00). Hexadecyltrimethylammonium bromide was added as a catalyst, and the mixture was stirred at 100-110°C for 12-14 hours to prepare polyethylene glycol bismaleic acid diester sodium sulfonate T-APOnEOm-S.

[0026] The concentration of the sodium bisulfite aqueous solution is 30.0-40.0 wt%.

[0027] The amount of hexadecyltrimethylammonium bromide added is 2.0%-4.0% of the mass of polyethylene glycol bismaleic acid diester T-APOnEOm.

[0028] A PPO / PEO block Gemini stretchable surfactant suitable for high-temperature and high-salinity reservoirs, wherein in the surfactant sodium polyethylene glycol bismaleic acid diester sulfonate T-APOnEOm-S, n takes a value of 3-30 and m takes a value of 0-30.

[0029] Furthermore, the surfactant sodium polyethylene glycol bismaleic acid diester sulfonate T-APOnEOm-S maintains the oil-water interfacial tension at the level of 10⁻³ mN / m in a saline solution with a NaCl concentration as high as 9.0 wt%. The surfactant sodium polyethylene glycol bismaleic acid diester sulfonate T-APOnEOm-S maintains the oil-water interfacial tension at 10⁻³ mN / m under conditions of 120°C and 9.0 wt% NaCl. -2The oil-water interfacial tension was maintained at the level of mN / m at 70℃ and 9.0wt% NaCl, reaching a level comparable to 10. -3 The order of magnitude is on the order of mN / m.

[0030] Application of PPO / PEO block Gemini extensible surfactants suitable for high-temperature and high-salinity oil reservoirs, using the surfactants for the recovery of high-temperature and high-salinity oil reservoirs.

[0031] The beneficial effects of this invention are:

[0032] (1) This invention provides a method for preparing a PPO / PEO block Gemini extended surfactant suitable for high-temperature and high-salinity reservoirs. The PPO-PEO block significantly improves the temperature and salt resistance of the surfactant through a synergistic effect of hydrophobic and hydrophilic properties: the PPO block, with its hydrophobic methyl side chain and steric hindrance effect, forms a tight micelle structure at high temperatures, enhancing thermal stability and blocking salt ion penetration; at the same time, the PEO block forms a hydration layer through flexible chains, maintaining molecular hydrophilicity while effectively shielding the electrostatic effects of high-valence salt ions by wrapping anionic groups through a coiled structure. The dynamic balance between the two allows the molecule to maintain structural integrity and solubility under high-temperature and high-salinity conditions, thus exhibiting excellent temperature and salt resistance properties.

[0033] (2) This invention provides the preparation of a PPO / PEO block Gemini stretchable surfactant suitable for high-temperature and high-salt reservoirs. It has excellent salt resistance and can still maintain the oil-water interfacial tension at an ultra-low level of 10-3 mN / m in salt water with NaCl as high as 9.0%.

[0034] (3) This invention provides a method for preparing a PPO / PEO block Gemini extensible surfactant suitable for high-temperature and high-salinity reservoirs. It has excellent temperature resistance and can maintain the oil-water interfacial tension at 10°C at high temperatures and salt concentrations. - 2 The mN / m level can even reach 10 -3 The mN / m level. Attached Figure Description

[0035] Figure 1 This is a flowchart illustrating the preparation method of PPO / PEO block Gemini stretchable surfactants suitable for high-temperature and high-salinity oil reservoirs.

[0036] Figure 2a The T-APO10-S obtained in Example 1 was analyzed by proton nuclear magnetic resonance spectroscopy.

[0037] Figure 2b T-APO10EO2-S nuclear magnetic resonance hydrogen spectrum analysis of the sample prepared in Example 2;

[0038] Figure 2c T-APO10EO4-S nuclear magnetic resonance hydrogen spectrum analysis of the sample prepared in Example 3;

[0039] Figure 2d The T-APO10EO6-S obtained in Example 4 was analyzed by proton nuclear magnetic resonance spectroscopy.

[0040] Figure 2e T-APO10EO8-S prepared in Example 5 was analyzed by proton nuclear magnetic resonance (NMR) spectrum.

[0041] Figure 2f T-APO10EO10-S nuclear magnetic resonance hydrogen spectrum analysis of the sample prepared in Example 6;

[0042] Figure 3 Fourier transform infrared spectroscopy analysis of the T-APO10EOm-S prepared in Examples 1-6. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Preparation methods of PPO / PEO block Gemini stretchable surfactants suitable for high-temperature and high-salinity oil reservoirs, such as... Figure 1 As shown. It includes the following steps:

[0045] (1) Preparation of APOnEOm: Fatty alcohol is used as a starting material and added to a polymerization reactor. Potassium hydroxide is added as a catalyst and 18-crown ether-6 is added as a complexing agent to carry out propoxylation reaction or propoxylation reaction and ethoxylation reaction to prepare fatty alcohol polyoxypropylene polyoxyethylene ether APOnEOm, where n is 3-30 and m is 0-30; In this invention, the fatty alcohol includes any one of n-octanol, n-decanol, dodecanol, tetradecylol, and hexadecylol;

[0046] Specifically, when m=0, fatty alcohol is used as a starting material and added to the polymerization reactor, while potassium hydroxide is added as a catalyst and 18-crown ether-6 as a complexing agent. Propylene oxide is added at 130℃-135℃ to carry out the propoxylation reaction; APOn is prepared.

[0047] When m is 1-30, fatty alcohol is added to the polymerization reactor as the starting material, potassium hydroxide is added as a catalyst, and 18-crown ether-6 is added as a complexing agent. Propylene oxide is added at 130℃-135℃ to carry out the propoxylation reaction; ethylene oxide is added at 125℃-130℃ to carry out the ethoxylation reaction, and fatty alcohol polyoxypropylene polyoxyethylene ether APOnEOm is prepared.

[0048] The added potassium hydroxide is 3‰-5‰ of the total mass of fatty alcohol and propylene oxide;

[0049] The molar ratio of added 18-crown ether-6 to added potassium hydroxide is (1.00-2.00):1.00;

[0050] The molar ratio of added propylene oxide to fatty alcohol is (3.00-30.00):1.00;

[0051] The molar ratio of added ethylene oxide to fatty alcohol is (0.00-30.00):1.00.

[0052] (2) Preparation of linker: Maleic anhydride and polyethylene glycol were added to a flask at a molar ratio of (2.00-3.00):1.00, anhydrous sodium acetate was added as a catalyst, and the mixture was stirred at 90-100℃ for 1.0-1.2 hours to obtain the linker;

[0053] The mass of anhydrous sodium acetate added is 1.0%-2.0% of the total mass of maleic anhydride and polyethylene glycol.

[0054] (3) Preparation of T-APOnEOm: The fatty alcohol polyoxypropylene polyoxyethylene ether APOnEOm and the linker are added to a flask at a molar ratio of (2.00-3.00):1.00. p-Toluenesulfonic acid is added as a catalyst and molecular sieve is added as a dehydrating agent. The mixture is stirred at 140-150℃ in an environment of -0.7MPa to -1.0MPa for 7-8 hours to obtain polyethylene glycol bismaleic acid diester T-APOnEOm.

[0055] The amount of p-toluenesulfonic acid added is 1.0%-3.0% of the total mass of the linker and APOnEOm; the molecular screening uses any one or more of 3A molecular sieve, 4A molecular sieve and 5A molecular sieve.

[0056] (4) Preparation of T-APOnEOm-S: The polyethylene glycol bismaleic acid diester T-APOnEOm prepared in step (3) and sodium bisulfite aqueous solution were added to a flask at a molar ratio of 1.00:(2.00-4.00), and hexadecyltrimethylammonium bromide was added as a catalyst. The mixture was stirred at 100-110℃ for 12-14 hours to prepare polyethylene glycol bismaleic acid diester sodium sulfonate T-APOnEOm-S.

[0057] The concentration of the sodium bisulfite aqueous solution is 30.0-40.0 wt%.

[0058] The amount of hexadecyltrimethylammonium bromide added is 2.0%-4.0% of the mass of polyethylene glycol bismaleic acid diester T-APOnEOm.

[0059] The following are specific examples:

[0060] Example 1: A method for preparing a PPO / PEO block Gemini spreadable surfactant suitable for high-temperature and high-salinity oil reservoirs, the method comprising:

[0061] S1. Take 120.00g of dodecanol as the starting material and add it to the polymerization reactor. At the same time, add 1.50g of potassium hydroxide as a catalyst and 7.07g of 18-crown ether-6 as a complexing agent. Add 374.20g of propylene oxide at 130℃ to carry out the propoxylation reaction, and polymerize to APO10, with the following structural formula:

[0062]

[0063] S2. Add 30.00 g of maleic anhydride and 21.37 g of triethylene glycol to a flask, add 0.54 g of anhydrous sodium acetate as a catalyst, and stir at 95 °C for 1 hour. The reaction is accelerated by heating and introducing a catalyst to obtain the linker group. The structural formula of the linker group is as follows:

[0064]

[0065] S3. Add 60.00g of APO10 and 13.23g of the linker to a flask, add 1.46g of p-toluenesulfonic acid as a catalyst, and add molecular sieve as a dehydrating agent. Stir at 145℃ under negative pressure for 8 hours to obtain T-APO10. The structural formula of T-APO10 is as follows:

[0066]

[0067] S4. Add 30.00g of T-APO10 and 14.52g of 35% sodium bisulfite aqueous solution to a flask, add 0.90g of hexadecyltrimethylammonium bromide as a catalyst, and stir at 104℃ for 14 hours to obtain the final product T-APO10-S, with the following structural formula:

[0068]

[0069] Example 2: A method for preparing a PPO / PEO block Gemini spreadable surfactant suitable for high-temperature and high-salinity oil reservoirs, the method comprising:

[0070] S1. Take 120.00g of dodecanol as the starting material and add it to the polymerization reactor. At the same time, add 1.50g of potassium hydroxide as a catalyst and 7.07g of 18-crown ether-6 as a complexing agent. Add 374.20g of propylene oxide at 130℃ to carry out the propoxylation reaction, and then add 56.77g of ethylene oxide at 125℃ to carry out the ethoxylation reaction, polymerizing to APO10EO2. The structural formula of APO10EO2 is as follows:

[0071]

[0072] S2. Add 30.00 g of maleic anhydride and 21.37 g of triethylene glycol to a flask, add 0.54 g of anhydrous sodium acetate as a catalyst, and stir at 95 °C for 1 hour. The reaction is accelerated by heating and introducing a catalyst to obtain the linker group. The structural formula of the linker group is as follows:

[0073]

[0074] S3. Add 60.00g of APO10EO2 and 11.87g of the linker to a flask, add 1.44g of p-toluenesulfonic acid as a catalyst, and add molecular sieve as a dehydrating agent. Stir at 145℃ under negative pressure for 8 hours to obtain T-APO10EO2. The structural formula of the T-APO10EO2 reactant is as follows:

[0075]

[0076] S4. Add 30.00 g of T-APO10EO2 and 13.26 g of 35% sodium bisulfite aqueous solution to a flask, add 0.90 g of hexadecyltrimethylammonium bromide as a catalyst, and stir at 104 °C for 14 hours to obtain the final product T-APO10EO2-S. The structural formula of T-APO10EO2-S is as follows:

[0077]

[0078] Example 3: A method for preparing a PPO / PEO block Gemini spreadable surfactant suitable for high-temperature and high-salinity oil reservoirs, the method comprising:

[0079] S1. Take 120.00g of tetradecyl alcohol as the starting material and add it to the polymerization reactor. At the same time, add 1.40g of potassium hydroxide as a catalyst and 6.60g of 18-crown ether-6 as a complexing agent. Add 325.23g of propylene oxide at 130℃ to carry out the propoxylation reaction. Then, add 99.00g of ethylene oxide at 125℃ to carry out the ethoxylation reaction. The polymer is APO10EO4, and the structural formula of APO10EO4 is as follows:

[0080]

[0081] S2. Add 30.00g of maleic anhydride and 21.37g of triethylene glycol to a flask, add 0.54g of anhydrous sodium acetate as a catalyst, and stir at 95°C for 1 hour. The reaction is accelerated by heating and introducing a catalyst to obtain the linker group. The structural formula of the linker group reactant is as follows:

[0082]

[0083] S3. Add 60.00g of APO10EO4 and 8.53g of the linker to a flask, add 1.37g of p-toluenesulfonic acid as a catalyst, and add molecular sieve as a dehydrating agent. Stir at 145℃ under negative pressure for 8 hours to obtain T-APO10EO4. The structural formula of T-APO10EO4 is as follows:

[0084]

[0085] S4. Add 30.00 g of T-APO10EO4 and 11.89 g of 35% sodium bisulfite aqueous solution to a flask, add 0.90 g of hexadecyltrimethylammonium bromide as a catalyst, and stir at 104 °C for 14 hours to obtain the final product T-APO10EO4-S. The structural formula of T-APO10EO4-S is as follows:

[0086]

[0087] Example 4: A method for preparing a PPO / PEO block Gemini spreadable surfactant suitable for high-temperature and high-salinity oil reservoirs, the method comprising:

[0088] S1. Take 120.00g of tetradecyl alcohol as the starting material and add it to the polymerization reactor. At the same time, add 1.40g of potassium hydroxide as a catalyst and 6.60g of 18-crown ether-6 as a complexing agent. Add 325.23g of propylene oxide at 130℃ to carry out the propoxylation reaction. Then, add 149.00g of ethylene oxide at 125℃ to carry out the ethoxylation reaction, and polymerize to APO10EO6. The structural formula of APO10EO6 is as follows:

[0089]

[0090] S2. Add 30.00 g of maleic anhydride and 21.37 g of triethylene glycol to a flask, add 0.54 g of anhydrous sodium acetate as a catalyst, and stir at 95 °C for 1 hour. The reaction is accelerated by heating and introducing a catalyst to obtain the linker group. The structural formula of the linker group is as follows:

[0091]

[0092] S3. Add 60.00 g of APO10EO6 and 7.86 g of the linker to a flask, add 1.40 g of p-toluenesulfonic acid as a catalyst, and add molecular sieve as a dehydrating agent. Stir at 145 °C under negative pressure for 8 hours to obtain T-APO10EO6. The structural formula of T-APO10EO6 is as follows:

[0093]

[0094] S4. Add 30.00g of T-APO10EO6 and 11.03g of 35% sodium bisulfite aqueous solution to a flask, add 0.90g of hexadecyltrimethylammonium bromide as a catalyst, and stir at 104℃ for 12 hours to obtain the final product T-APO10EO6-S. The structural formula of T-APO10EO6-S is as follows:

[0095]

[0096] Example 5: A method for preparing a PPO / PEO block Gemini extensible surfactant suitable for high-temperature and high-salinity oil reservoirs, the method comprising:

[0097] S1. 120g of cetyl alcohol was added to a polymerization reactor as a starting material, along with 1.30g of potassium hydroxide as a catalyst and 6.15g of 18-crown ether-6 as a complexing agent. 287.60g of propylene oxide was added at 130℃ to initiate a propoxylation reaction, followed by 227.10g of ethylene oxide at 125℃ for ethoxylation, polymerizing to APO10EO8. The structural formula of APO10EO8 is as follows:

[0098]

[0099] S2. Add 30.00 g of maleic anhydride and 21.37 g of triethylene glycol to a flask, add 0.54 g of anhydrous sodium acetate as a catalyst, and stir at 95 °C for 1 hour. The reaction is accelerated by heating and introducing a catalyst to obtain the linker group. The structural formula of the linker group is as follows:

[0100]

[0101] S3. Add 60.00g of APO10EO8 and 7.10g of the linker to a flask, add 1.35g of p-toluenesulfonic acid as a catalyst, and add molecular sieve as a dehydrating agent. Stir at 145℃ under negative pressure for 8 hours to obtain T-APO10EO8. The structural formula of T-APO10EO8 is as follows:

[0102]

[0103] S4. Add 30.00g of T-APO10EO8 and 10.10g of 35% sodium bisulfite aqueous solution to a flask, add 0.90g of hexadecyltrimethylammonium bromide as a catalyst, and stir at 104℃ for 14 hours to obtain the final product T-APO10EO8-S. The structural formula of T-APO10EO8-S is as follows:

[0104]

[0105] Example 6: A method for preparing a PPO / PEO block Gemini spreadable surfactant suitable for high-temperature and high-salinity reservoirs, the method comprising:

[0106] S1. 120g of cetyl alcohol was added to a polymerization reactor as a starting material, along with 1.30g of potassium hydroxide as a catalyst and 6.15g of 18-crown ether-6 as a complexing agent. 287.60g of propylene oxide was added at 130℃ to initiate a propoxylation reaction, followed by 218.20g of ethylene oxide at 125℃ for ethoxylation. The resulting polymer was APO10EO10, with the following structural formula:

[0107]

[0108] S2. Add 30.00 g of maleic anhydride and 21.37 g of triethylene glycol to a flask, add 0.54 g of anhydrous sodium acetate as a catalyst, and stir at 95 °C for 1 hour. The reaction is accelerated by heating and introducing a catalyst to obtain the linker group. The structural formula of the linker group is as follows:

[0109]

[0110] S3. Add 60.00g of APO10EO10 and 6.60g of the linker to a flask, add 1.34g of p-toluenesulfonic acid as a catalyst, and add molecular sieve as a dehydrating agent. Stir at 145℃ under negative pressure for 8 hours to obtain T-APO10EO10. The structural formula of T-APO10EO10 is as follows:

[0111]

[0112] S4. Add 30.00 g of T-APO10EO10 and 9.45 g of 35% sodium bisulfite aqueous solution to a flask, add 0.90 g of hexadecyltrimethylammonium bromide as a catalyst, and stir at 104 °C for 14 hours to obtain the final product T-APO10EO10-S. The structural formula of T-APO10EO10-S is as follows:

[0113]

[0114] As shown in Figures 2-3, the target products of Examples 1-6 were analyzed by 1H NMR and Fourier transform infrared spectroscopy, confirming that the synthesized product was the target product. Analysis of Figure 2 shows that the characteristic signal observed at position a is attributed to the -(CH3)- group of the fatty alcohol; the characteristic signal observed at position b is attributed to the -(CH3)-, -(CH2)-, and -(CH2(CH3))- groups of the hydrophobic portion of the PPO block; the chemical shift detected at position c is identified as corresponding to the -(CH2-CH2-O)- group; the obvious peak at position d is attributed to the -CH(NaHSO3)- group; and position e is attributed to the -(CH-C=O)- group.

[0115] Salt tolerance test: An aqueous solution containing 0.3 wt% surfactant was precisely prepared. The salt concentration was adjusted by adding different masses of NaCl. Under constant temperature of 45℃, the dynamic interfacial tension between the surfactant and liquid paraffin was measured using a rotating drop interfacial tension meter to evaluate the ability and stability to achieve ultra-low interfacial tension under different salinity conditions.

[0116] Temperature resistance test: An aqueous solution containing 0.3 wt% surfactant was precisely prepared, and the salt concentration was adjusted to 9.0% by adding a certain mass of NaCl. Under different temperature conditions, the dynamic interfacial tension between the surfactant and liquid paraffin was measured using a rotating drop interfacial tension meter to evaluate the ability and stability to achieve ultra-low interfacial tension under different temperature conditions.

[0117] Table 1 shows the oil-water interfacial tension of the surfactants prepared in Examples 1-6 at different salt concentrations at 45°C.

[0118]

[0119] The salt tolerance test results are shown in Table 1. The interfacial tension (IFT) of the T-APOnEm-S surfactant-liquid paraffin-salt water system showed a regular change with salinity. With increasing NaCl concentration, the IFT first decreased and then increased, with the synthesized T-APOnEm-S surfactants all reaching 10⁻³ mN / m. Notably, T-APO10EO4-S stably maintained an ultra-low oil-water interfacial tension of 10⁻³ mN / m in 3%-7% NaCl, while T-APO10EO8-S also exhibited excellent interfacial activity in 7%-11% NaCl, maintaining an oil-water interfacial tension level of 10⁻³ mN / m. These results indicate that T-APOnEOm-S possesses stable temperature resistance.

[0120] Table 2 shows the interfacial tension of the surfactants prepared in Examples 1-6 at different temperatures in 9% NaCl.

[0121]

[0122] The results of the temperature resistance test are shown in Table 2. The results show that the interfacial tension (IFT) of T-APOnEOm-S (n=10; m=0,2,4,6) increases monotonically with increasing temperature, while the IFT of T-APOnEOm-S (n=10; m=8,10) shows a trend of first decreasing and then increasing. At 70℃, T-APO10EO8-S and T-APO10EO10-S maintain an ultra-low oil-water interfacial tension of 10⁻³ mN / m, while T-APO10EO10-S maintains 10⁻² mN / m even at 120℃. These results indicate that T-APOnEOm-S has stable temperature resistance.

[0123] The Gemini sulfonate surfactant containing PPO-PEO blocks provided by this invention exhibits significant advantages due to its intramolecular synergistic design: its PPO segments construct a high-temperature resistant hydrophobic framework, the PEO segments enhance solubility, and the unique double-chain Gemini structure further achieves extremely low critical micelle concentration, ultra-low interfacial tension, and high-temperature and high-salt stability. It can integrate multiple functions without compounding, avoiding performance fluctuations, increased costs, and environmental risks caused by compounding, and providing a more efficient and stable monomer solution for harsh reservoir conditions.

[0124] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing PPO / PEO block Gemini stretchable surfactants suitable for high-temperature and high-salinity oil reservoirs, characterized in that, Includes the following steps: (1) Preparation of APOnEOm: Fatty alcohol is used as the starting material and added to the polymerization reactor. Potassium hydroxide is added as a catalyst and 18-crown ether-6 is added as a complexing agent to carry out propoxylation and ethoxylation reactions to prepare fatty alcohol polyoxypropylene polyoxyethylene ether APOnEOm. n takes the value of 3-30 and m takes the value of 1-30. (2) Preparation of linking groups: Maleic anhydride and polyethylene glycol were mixed, anhydrous sodium acetate was added as a catalyst, and the mixture was heated and stirred to obtain linking groups; (3) Preparation of T-APOnEOm: The fatty alcohol polyoxypropylene polyoxyethylene ether APOnEOm and the linker are mixed, p-toluenesulfonic acid is added as a catalyst, and molecular sieve is added as a dehydrating agent. The mixture is stirred and reacted in a negative pressure environment to obtain polyethylene glycol bismaleic acid diester T-APOnEOm. (4) Preparation of T-APOnEOm-S: The polyethylene glycol bismaleic acid diester T-APOnEOm is mixed with sodium bisulfite aqueous solution, and hexadecyltrimethylammonium bromide is added as a catalyst. The mixture is stirred and reacted to obtain the target product, polyethylene glycol bismaleic acid diester sodium sulfonate, which is a PPO / PEO block Gemini stretching surfactant suitable for high temperature and high salt reservoirs.

2. The method for preparing the PPO / PEO block Gemini stretchable surfactant suitable for high-temperature and high-salinity reservoirs according to claim 1, characterized in that, In step (1): fatty alcohol is added to the polymerization reactor as a starting material, potassium hydroxide is added as a catalyst, and 18-crown ether-6 is added as a complexing agent. Propylene oxide is added at 130℃-135℃ to carry out propoxylation reaction, and then ethylene oxide is added at 125℃-130℃ to carry out ethoxylation reaction to prepare fatty alcohol polyoxypropylene polyoxyethylene ether APOnEOm.

3. The method for preparing the PPO / PEO block Gemini stretchable surfactant suitable for high-temperature and high-salinity reservoirs according to claim 2, characterized in that, The added potassium hydroxide is 3‰-5‰ of the total mass of fatty alcohol and propylene oxide; The molar ratio of added 18-crown ether-6 to added potassium hydroxide is (1.00-2.00):1.00; The molar ratio of added propylene oxide to fatty alcohol is (3.00-30.00):1.00; The molar ratio of added ethylene oxide to fatty alcohol is (1.00-30.00):1.

00.

4. The method for preparing the PPO / PEO block Gemini stretchable surfactant suitable for high-temperature and high-salinity reservoirs according to claim 1, characterized in that, Step (2) specifically involves adding maleic anhydride and polyethylene glycol in a molar ratio of (2.00-3.00):1.00 into a flask, adding anhydrous sodium acetate as a catalyst, and stirring at 90-100°C for 1.0-1.2 hours to obtain the linker group; The mass of anhydrous sodium acetate added is 1.0%-2.0% of the total mass of maleic anhydride and polyethylene glycol.

5. The method for preparing the PPO / PEO block Gemini stretchable surfactant suitable for high-temperature and high-salinity reservoirs according to claim 1, characterized in that, Step (3) specifically involves adding the fatty alcohol polyoxypropylene polyoxyethylene ether APOnEOm and the linker to a flask at a molar ratio of (2.00-3.00):1.00, adding p-toluenesulfonic acid as a catalyst, and adding molecular sieve as a dehydrating agent. The mixture is stirred at 140-150℃ in an environment of -0.7MPa to -1.0MPa for 7-8 hours to obtain polyethylene glycol bismaleic acid diester T-APOnEOm. The amount of p-toluenesulfonic acid added is 1.0%-3.0% of the total mass of the linker and APOnEOm.

6. The method for preparing the PPO / PEO block Gemini stretchable surfactant suitable for high-temperature and high-salinity reservoirs according to claim 5, characterized in that, The molecular screening uses any one or more of 3A molecular sieve, 4A molecular sieve, and 5A molecular sieve.

7. The method for preparing the PPO / PEO block Gemini stretchable surfactant suitable for high-temperature and high-salinity reservoirs according to claim 1, characterized in that, Step (4) is as follows: The polyethylene glycol bismaleic acid diester T-APOnEOm prepared in step (3) was added to a flask with sodium bisulfite aqueous solution at a molar ratio of 1.00:(2.00-4.00). Hexadecyltrimethylammonium bromide was added as a catalyst, and the mixture was stirred at 100-110°C for 12-14 hours to prepare polyethylene glycol bismaleic acid diester sodium sulfonate T-APOnEOm-S. The concentration of the sodium bisulfite aqueous solution is 30.0-40.0 wt%; the amount of hexadecyltrimethylammonium bromide added is 2.0%-4.0% of the mass of polyethylene glycol bismaleic acid diester T-APOnEOm.

8. A PPO / PEO block Gemini stretchable surfactant suitable for high-temperature, high-salinity oil reservoirs, prepared by the method described in any one of claims 1-7, characterized in that, In the surfactant sodium polyethylene glycol bismaleic acid diester sulfonate T-APOnEOm-S, n takes a value of 3-30, and m takes a value of 1-30.

9. The PPO / PEO block Gemini stretchable surfactant suitable for high-temperature and high-salinity reservoirs according to claim 8, characterized in that, The surfactant, sodium polyethylene glycol bismaleic acid diester sulfonate T-APOnEOm-S, maintained the oil-water interfacial tension at 10 ppm under conditions of 120°C and 9.0 wt% NaCl. -2 The oil-water interfacial tension was maintained at the level of mN / m at 70℃ and 9.0wt% NaCl, reaching a level comparable to 10. -3 The order of magnitude is on the order of mN / m.

10. The application of the PPO / PEO block Gemini stretchable surfactant suitable for high-temperature and high-salinity reservoirs according to claim 8, characterized in that, The surfactant is used for the recovery of oil from high-temperature, high-salinity reservoirs.

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