A salicylic acid-based gemini surfactant, its preparation method, and its application in oil displacement.

Abstract

This invention discloses a salicylic acid-based gemini surfactant, its preparation method, and its application in oil displacement. Belonging to the field of petrochemical technology, the surfactant is prepared using sulfosalicylic acid as a raw material through a bromination reaction between sulfosalicylic acid and a binder, an esterification reaction with β-cyclodextrin, and an acid-base reaction with sodium hydroxide. The benzene ring structure in the salicylic acid-based gemini surfactant improves its stability and temperature resistance; the gemini structure, with its two anionic groups, repels negatively charged formation rocks, effectively reducing formation adsorption and thus improving interfacial tension; β-cyclodextrin possesses a hydrophilic outer surface and a hydrophobic inner cavity, enabling better adsorption onto rock surfaces and achieving excellent wettability; the acid-base reaction converts the sulfonic acid groups into sodium sulfonate salts, enhancing its salt resistance and allowing it to exert a sustained oil displacement effect in the formation.

Description

Technical Field

[0001] This invention belongs to the field of petrochemical technology, specifically relating to a salicylic acid-based gemini surfactant, its preparation method, and its application in oil displacement. Background Technology

[0002] Surfactant-assisted flooding (SAF) is a method of enhancing oil recovery by adding surfactants and other additives to an aqueous phase. This reduces the interfacial tension between the oil and water by driving a pressure differential, allowing residual oil trapped in rock pores to flow. SAF is a widely applicable and promising chemical flooding technique. Surfactants, due to their unique molecular structure with hydrophilic and lipophilic groups, can effectively reduce the interfacial tension between the displacing phase and the crude oil, forcing oil droplets to deform and reducing resistance as the crude oil flows through pore throats. Surfactants can also adsorb onto the rock surface, causing a wetting reversal where the hydrophilic groups align with the rock, resulting in the shedding of the oil film.

[0003] The most common surfactants used for oil displacement are anionic petroleum sulfonates. Petroleum sulfonates are anionic surfactants synthesized from petroleum distillate oil through processes such as sulfonation, neutralization, and compounding. Currently, oilfields have widely adopted them as chemical flooding agents in tertiary oil recovery. However, they have drawbacks, such as poor performance stability, poor salt tolerance, and susceptibility to adsorption by clay, leading to losses.

[0004] Therefore, in view of the technical problems of poor performance stability, poor salt resistance and easy adsorption by clay to anionic petroleum sulfonate surfactants used for oil displacement, it is necessary to develop a new surfactant that can reduce interfacial tension, reduce formation adsorption, and have excellent wettability and temperature and salt resistance. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a salicylic acid-based gemini surfactant, its preparation method and its application in oil displacement, so as to solve the technical problems of poor performance stability, poor salt resistance and easy adsorption by clay during oil displacement of existing surfactants.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] This invention discloses a method for preparing a salicylic acid-based gemini surfactant, comprising the following steps:

[0008] S1: Mix sulfosalicylic acid, alkaline reagent and solvent evenly, heat and add binding agent, and after heating reaction, obtain intermediate product I;

[0009] S2: After mixing and reacting β-cyclodextrin, catalyst and intermediate product I obtained from S1, intermediate product II is obtained;

[0010] S3: Sodium hydroxide, anhydrous ethanol and intermediate product II obtained from S2 are mixed and reacted, and then filtered, washed and dried to obtain salicylic acid-based gemini surfactant.

[0011] Preferably, in S1, the mass ratio of sulfosalicylic acid: alkaline reagent: solvent is 1:(0.8-1):(2-3); the molar ratio of binder: sulfosalicylic acid is 1:(2.1-2.3).

[0012] Preferably, in S1, the heating reaction temperature is 70–100°C, and the heating reaction time is 2–5 h.

[0013] Preferably, in S1, the heating temperature is 50-60°C; the alkaline reagent is potassium hydroxide or sodium hydroxide; the solvent is dimethylformamide or anhydrous ethanol; and the binding agent is 1,3-dibromopropane, 1,4-dibromobutane, or 1,6-dibromohexane.

[0014] Preferably, in S2, the mass ratio of intermediate product I to β-cyclodextrin is 1:(1.5-2.5); the mass of the catalyst is 0.03% to 0.05% of the sum of the masses of intermediate product I and β-cyclodextrin; and the catalyst is concentrated sulfuric acid, phosphoric acid, or benzenesulfonic acid.

[0015] Preferably, in S2, the temperature of the mixing reaction is 60–80°C, and the mixing reaction time is 5–8 hours.

[0016] Preferably, in S3, the mass ratio of sodium hydroxide to intermediate product II is (0.3-0.5):1; and the mass ratio of anhydrous ethanol to intermediate product II is (20-25):1.

[0017] Preferably, in S3, the temperature of the mixing reaction is 40–60°C, and the mixing reaction time is 13–15 h.

[0018] The present invention also discloses a salicylic acid-based gemini surfactant prepared by the above preparation method.

[0019] The present invention also discloses the application of the above-mentioned salicylic acid-based gemini surfactant in oil displacement.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This invention discloses a method for preparing a salicylic acid-based gemini surfactant using sulfosalicylic acid as a raw material. This method is environmentally friendly, and the benzene ring structure improves the surfactant's stability and temperature resistance. The gemini structure is imparted to the surfactant through the bromination reaction of sulfosalicylic acid with a linker, which helps to better reduce interfacial tension. Further esterification with β-cyclodextrin, which has a hydrophilic outer surface and a hydrophobic inner cavity, allows the surfactant to better adsorb onto rock surfaces, achieving excellent wettability. An acid-base reaction with sodium hydroxide converts the sulfonic acid groups into sodium sulfonate salts, enhancing the surfactant's salt resistance, thus producing the salicylic acid-based gemini surfactant. The gemini structure of this salicylic acid-based gemini surfactant gives it two anionic groups, which repel negatively charged formation rocks, effectively reducing the amount of adsorption in the formation. The salicylic acid-based gemini surfactant provided by this invention solves the technical problems of existing surfactants in oil displacement, such as poor performance stability, poor salt resistance, and easy adsorption by clay, resulting in losses. It has structural and performance advantages in oil displacement and is suitable for the field of oil displacement.

[0022] This invention discloses a salicylic acid-based gemini surfactant prepared by the above-mentioned method. This salicylic acid-based gemini surfactant has temperature and salt resistance, excellent wettability and strong resistance to formation adsorption, and can exert a long-lasting oil displacement effect in the formation.

[0023] The present invention also discloses the application of the above-mentioned salicylic acid-based gemini surfactant in oil displacement. When applied in oil displacement, the salicylic acid-based gemini surfactant has low toxicity, strong stability and temperature resistance. The linking groups in the salicylic acid-based gemini surfactant cause the functional groups in the surfactant to appear in multiples, giving it good temperature resistance and low interfacial tension. Adding a small amount to the injection water can expand the oil displacement sweep volume, which has a significant advantage in tertiary oil recovery chemical flooding. Attached Figure Description

[0024] Figure 1 This is a diagram illustrating the reaction mechanism for the preparation of the salicylic acid-based gemini surfactant disclosed in Example 1 of this invention. Detailed Implementation

[0025] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. 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 should fall within the scope of protection of the present invention.

[0026] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0027] The present invention will now be described in further detail with reference to the accompanying drawings:

[0028] This invention discloses a method for preparing a salicylic acid-based gemini surfactant, comprising the following steps:

[0029] S1: Add sulfosalicylic acid, basic reagent and solvent to a three-necked flask, stir well, heat to a certain temperature, add binding agent, raise to a certain temperature and react for a certain time to obtain intermediate product I;

[0030] S2: Add β-cyclodextrin, catalyst and intermediate product I obtained from S1 into a three-necked flask, react at a certain temperature for a certain time to obtain intermediate product II;

[0031] S3: Sodium hydroxide, anhydrous ethanol and intermediate product II obtained from S2 were added to a three-necked flask and reacted at a certain temperature for a certain time. After filtration, washing and drying, the oil-dispatch salicylic acid-based gemini surfactant was obtained.

[0032] In S1, the basic reagent is potassium hydroxide or sodium hydride; the solvent is dimethylformamide or anhydrous ethanol; the binding agent is 1,3-dibromopropane, 1,4-dibromobutane, or 1,6-dibromohexane; the molar ratio of binding agent to sulfosalicylic acid is 1:(2.1–2.3); the mass of the basic reagent is 0.8–1 times the mass of sulfosalicylic acid; the mass of the solvent is 2–3 times the mass of sulfosalicylic acid; the binding agent is added at 50–60°C, and the reaction is carried out at a reaction temperature of 70–100°C for 2–5 hours.

[0033] In S2, the catalyst is concentrated sulfuric acid, phosphoric acid, or benzenesulfonic acid; the molar ratio of intermediate product I to β-cyclodextrin is 1:(1-1.3); the mass of the catalyst is 0.03% to 0.05% of the sum of the masses of intermediate product I and β-cyclodextrin; the reaction is carried out at a reaction temperature of 60-80℃ for 5-8 hours.

[0034] In S3, the mass of sodium hydroxide is 0.3 to 0.5 times the mass of intermediate product II; the mass of anhydrous ethanol is 20 to 25 times the mass of intermediate product II; the reaction temperature is 40 to 60℃; and the reaction time is 13 to 15 hours.

[0035] Example 1

[0036] A method for preparing a salicylic acid-based gemini surfactant includes the following steps:

[0037] S1: Add 5.08g of sulfosalicylic acid, 4.06g of potassium hydroxide and 10.16g of dimethylformamide to a three-necked flask, stir well, heat to 50℃, add 10.25g of 1,6-dibromohexane, heat to 70℃ and react for 2h to obtain intermediate product I;

[0038] S2: Add 7.5g of β-cyclodextrin, 0.0037g of concentrated sulfuric acid and 5g of intermediate product I obtained from S1 to a three-necked flask, and react at 60℃ for 5h to obtain intermediate product II;

[0039] S3: Add 2g of intermediate product II obtained in S2 to a three-necked flask, add 0.75g of sodium hydroxide and 40g of anhydrous ethanol, react at 40℃ for 13h, filter, wash and dry to obtain salicylic acid-based gemini surfactant.

[0040] See Figure 1 This is a schematic diagram of the preparation reaction mechanism of the salicylic acid-based gemini surfactant disclosed in Example 1 of this invention. As can be seen from the diagram, the salicylic acid-based gemini surfactant uses sulfosalicylic acid as a raw material, making it environmentally friendly. Furthermore, the benzene ring structure improves the surfactant's stability and temperature resistance. The bromination reaction between sulfosalicylic acid and the binder imparts a gemini structure to the surfactant, which is beneficial for reducing interfacial tension. Further esterification with β-cyclodextrin, which has a hydrophilic outer surface and a hydrophobic inner cavity, allows the surfactant to better adsorb onto the rock surface, achieving excellent wettability. The acid-base reaction with sodium hydroxide converts the sulfonic acid group into a sodium sulfonate salt, enhancing the surfactant's salt resistance, thus obtaining the salicylic acid-based gemini surfactant.

[0041] Example 2

[0042] A method for preparing a salicylic acid-based gemini surfactant includes the following steps:

[0043] S1: Add 5.08g of sulfosalicylic acid, 4.06g of potassium hydroxide and 10.16g of dimethylformamide to a three-necked flask, stir well, heat to 55℃, add 10.25g of 1,6-dibromohexane, heat to 80℃ and react for 2h to obtain intermediate product I;

[0044] S2: Add 7.5g of β-cyclodextrin, 0.0037g of concentrated sulfuric acid and 5g of intermediate product I obtained from S1 to a three-necked flask, and react at 60℃ for 5h to obtain intermediate product II;

[0045] S3: Add 2g of intermediate product II obtained in S2 to a three-necked flask, add 0.75g of sodium hydroxide and 45g of anhydrous ethanol, react at 40℃ for 13h, filter, wash and dry to obtain salicylic acid-based gemini surfactant.

[0046] Example 3

[0047] A method for preparing a salicylic acid-based gemini surfactant includes the following steps:

[0048] S1: Add 5.08g of sulfosalicylic acid, 4.47g of potassium hydroxide and 12.70g of dimethylformamide to a three-necked flask, stir well, heat to 55℃, add 9.50g of 1,4-dibromobutane, heat to 80℃ and react for 3h to obtain intermediate product I;

[0049] S2: Add 10g of β-cyclodextrin, 0.0060g of phosphoric acid and 5g of intermediate product I obtained in S1 to a three-necked flask and react at 70℃ for 6h to obtain intermediate product II;

[0050] S3: Add 2g of intermediate product II obtained in S2 to a three-necked flask, add 0.8g of sodium hydroxide and 45g of anhydrous ethanol, react at 50℃ for 14h, filter, wash and dry to obtain salicylic acid-based gemini surfactant.

[0051] Example 4

[0052] A method for preparing a salicylic acid-based gemini surfactant includes the following steps:

[0053] S1: Add 5.08g of sulfosalicylic acid, 5.08g of sodium hydride and 15.24g of anhydrous ethanol to a three-necked flask, stir well, heat to 60℃, add 9.29g of 1,3-dibromopropane, heat to 90℃ and react for 4h to obtain intermediate product I.

[0054] S2: Add 10g of β-cyclodextrin, 0.0075g of benzenesulfonic acid and 5g of intermediate product I obtained in S1 to a three-necked flask and react at 80℃ for 7h to obtain intermediate product II;

[0055] S3: Add 2g of intermediate product II obtained in S2 to a three-necked flask, add 1g of sodium hydroxide and 45g of anhydrous ethanol, react at 60℃ for 14h, filter, wash and dry to obtain salicylic acid-based gemini surfactant.

[0056] Example 5

[0057] A method for preparing a salicylic acid-based gemini surfactant includes the following steps:

[0058] S1: Add 5.08g of sulfosalicylic acid, 5.08g of sodium hydride, and 10.16g of anhydrous ethanol to a three-necked flask, stir well, heat to 60℃, add 9.29g of 1,3-dibromopropane, and raise the temperature to 100℃ to react for 5 hours.

[0059] Intermediate product I was obtained;

[0060] S2: Add 12.5g of β-cyclodextrin, 0.0088g of benzenesulfonic acid and 5g of intermediate product I obtained in S1 to a three-necked flask and react at 80℃ for 8h to obtain intermediate product II;

[0061] S3: Add 2g of intermediate product II obtained in S2 to a three-necked flask, add 1g of sodium hydroxide and 50g of anhydrous ethanol, react at 46℃ for 15h, filter, wash and dry to obtain salicylic acid-based gemini surfactant.

[0062] Application effect test of the salicylic acid-based gemini surfactant prepared by this invention:

[0063] 1. Interface tension test

[0064] A 0.3% solution of oil displacement surfactant was prepared using distilled water. The interfacial tension between kerosene and the oil displacement surfactant solution was measured using a TX-500 rotating interfacial tensiometer. The measurement was performed three times consecutively, and the average value was taken. The interfacial tension test results are shown in Table 1.

[0065] 2. Capillary self-priming test

[0066] The aged capillary was removed and soaked in kerosene for 30 seconds to remove the asphalt deposited on the inner surface. Then, the residual kerosene was dried with nitrogen and dried at 60°C. The prepared oil-wetted capillary was vertically inserted into the oil-displacing surfactant solution, and the liquid level in the capillary was recorded. The test results are shown in Table 1.

[0067] 3. Temperature and salt resistance test

[0068] 100g of a 0.3% oil-displacing surfactant solution was prepared using distilled water. After sealing, the solution was aged in a 130℃ oven for 48 hours. After cooling, the sample solution was taken out for interfacial tension and capillary self-absorption tests. A 0.3% oil-displacing surfactant solution with a NaCl concentration of 1.0wt% was prepared, and the sample solution was used for interfacial tension and capillary self-absorption tests. The test results are shown in Table 1.

[0069] Table 1. Interfacial tension, capillary self-absorption, and temperature and salt resistance test data of the salicylic acid-based gemini surfactants prepared in Examples 1-5.

[0070]

[0071] Table 1 shows the interfacial tension, capillary self-absorption, and temperature and salt resistance test data of the salicylic acid-based gemini surfactants prepared in Examples 1-5 of this invention. As can be seen from the test results in Table 1, the salicylic acid-based gemini surfactants used for oil displacement can maintain low interfacial tension and high capillary self-absorption height even after high-temperature aging and high salinity. This indicates that the salicylic acid-based gemini surfactants used for oil displacement have temperature and salt resistance, excellent wettability, and strong resistance to formation adsorption, and can exert a long-lasting oil displacement effect in the formation.

[0072] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing a salicylic acid-based gemini surfactant, characterized in that, Includes the following steps: S1: Sulfosalicylic acid, alkaline reagent and solvent are mixed and stirred evenly, heated and then a binding agent is added. After heating and reaction, intermediate product I is obtained; the binding agent is 1,3-dibromopropane, 1,4-dibromobutane or 1,6-dibromohexane. S2: After mixing and reacting β-cyclodextrin, catalyst and intermediate product I obtained from S1, intermediate product II is obtained; S3: Sodium hydroxide, anhydrous ethanol and intermediate product II obtained from S2 are mixed and reacted, and then filtered, washed and dried to obtain salicylic acid-based gemini surfactant; the temperature of the mixing reaction is 40~60℃ and the mixing reaction time is 13~15h.

2. The method for preparing salicylic acid-based gemini surfactant according to claim 1, characterized in that, In S1, the mass ratio of sulfosalicylic acid: alkaline reagent: solvent is 1:(0.8~1):(2~3); the molar ratio of binder: sulfosalicylic acid is 1:(2.1~2.3).

3. The method for preparing salicylic acid-based gemini surfactant according to claim 1, characterized in that, In S1, the temperature of the heating reaction is 70~100℃, and the heating reaction time is 2~5h.

4. The method for preparing salicylic acid-based gemini surfactant according to claim 1, characterized in that, In S1, the heating temperature is 50~60℃; the alkaline reagent is potassium hydroxide or sodium hydroxide; and the solvent is dimethylformamide or anhydrous ethanol.

5. The method for preparing salicylic acid-based gemini surfactant according to claim 1, characterized in that, In S2, the mass ratio of intermediate product I to β-cyclodextrin is 1:(1.5~2.5); the mass of the catalyst is 0.03%~0.05% of the sum of the masses of intermediate product I and β-cyclodextrin; the catalyst is concentrated sulfuric acid, phosphoric acid or benzenesulfonic acid.

6. The method for preparing salicylic acid-based gemini surfactant according to claim 1, characterized in that, In S2, the temperature of the mixing reaction is 60~80℃, and the mixing reaction time is 5~8h.

7. The method for preparing salicylic acid-based gemini surfactant according to claim 1, characterized in that, In S3, the mass ratio of sodium hydroxide to intermediate product II is (0.3~0.5):1; the mass ratio of anhydrous ethanol to intermediate product II is (20~25):

1.

8. The salicylic acid-based gemini surfactant prepared by any one of claims 1 to 7.

9. The application of the salicylic acid-based gemini surfactant according to claim 8 in oil displacement.

Images