Surfactant with asymmetric structure as well as preparation method and application of surfactant
By preparing asymmetric structural surfactants, the problems of many components and poor universality in the prior art are solved, and efficient and stable oil displacement effect is achieved, which is suitable for different reservoir conditions.
Patent Information
- Application Number
- CN202311795971.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-25
- Publication Date
- 2025-07-04
AI Technical Summary
In the existing chemical oil-flooding technology, there are many components for binary composite oil-flooding surfactant, severe chromatographic separation, poor oil-water interface arrangement, poor universality, which affects the oil-flooding effect.
Asymmetric structural surfactant is used to prepare a single component surfactant with two different hydrophobic long chains and two hydrophilic groups through a raw material through a two-step catalytic reaction and substitution reaction, and is used in the binary composite flooding of oil fields.
The stability and oil displacement effect of the surfactant are improved, and the interface tension reaches below 1×10-2mN/m, which enhances the close arrangement with the oil-water interface, improves the recovery rate, adapts to different reservoir conditions, and reduces the use concentration and cost.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of chemical enhanced oil recovery, and particularly relates to an asymmetric surfactant, a preparation method thereof and an application thereof. Background Art
[0002] In the process of oil exploitation, the method of relying only on natural energies such as rock expansion, edge water drive, gravity, and natural gas expansion to extract oil is called primary oil recovery, and its recovery rate only reaches 5%-10%. This is the earliest oil exploitation method in oil fields; after primary oil recovery, artificial water injection (gas injection) is used to supplement the energy of the oil reservoir and maintain the formation pressure to continuously extract crude oil, which is called secondary oil recovery, and the oil field recovery rate can be increased to 30%-40%. However, after secondary oil recovery, the water content in the produced fluid is already too high. The water content of old oil fields in China is generally above 80%, and some even reach more than 90%. There is still 60%-70% of the remaining oil remaining underground, and the oil-water distribution in the reservoir has become very complex, increasing the difficulty of oil field exploitation. Therefore, after water flooding, chemical, physical or biological means need to be used to further improve the recovery rate. These new methods are collectively called tertiary oil recovery, specifically including miscible flooding, microbial method, thermal oil recovery method, chemical flooding method, etc. According to the current geological conditions of oil fields in China, the characteristics of reservoir physical properties and the current development status, the geological reserves of oil fields suitable for surfactant flooding in China account for 63%. Therefore, surfactant flooding should be an important direction in the research of tertiary oil recovery in China and also a chemical flooding agent with the greatest development potential.
[0003] At present, in the existing technology, the surfactants used in binary composite flooding in chemical flooding have problems such as many components, serious chromatographic separation, loose arrangement at the oil-water interface, and poor universality, which affect the oil displacement effect in use. Summary of the Invention
[0004] In view of the above problems, the present invention provides an asymmetric surfactant, a preparation method thereof and an application thereof. The surfactant is a single-component, temperature and salt-resistant, stable, and asymmetric structure anionic-nonionic surfactant with a wide carbon chain distribution. Using fatty alcohol and epichlorohydrin as raw materials, intermediates with two different hydrophobic long chains are obtained through two-step catalytic reactions, and then two different hydrophilic groups are introduced through substitution reactions. The surfactant molecule structure has two hydrophobic chains with different carbon chain lengths and two hydrophilic groups at the same time, with high surface activity and stability, and can be used as an oil displacement agent in binary composite flooding in oil fields, with good oil displacement effect.
[0005] The technical solution adopted by the present invention is as follows: an asymmetric surfactant, which uses fatty alcohol and epichlorohydrin as raw materials, obtains an intermediate with two different hydrophobic long chains through two-step catalytic reactions, and then introduces two different hydrophilic groups through substitution reactions. The asymmetric surfactant has the structure shown in Formula I: Formula I; Among them, the structure of R1 is a C6-C10 short carbon chain alkyl chain; the structure of R2 is a C12-C22 long carbon chain alkyl chain; the structure of R3 is one of the two structures of Formula II or Formula III; Formula II; Formula III.
[0006] The fatty alcohol includes short-chain fatty alcohol and long-chain fatty alcohol. The short-chain fatty alcohol is a straight-chain fatty alcohol with 6 to 10 carbon atoms, and its structural general formula is Formula IV. The long-chain fatty alcohol is a straight-chain fatty alcohol with 12 to 22 carbon atoms, and its structural general formula is Formula V; Formula IV; Formula V; The mass ratio of the long-chain fatty alcohol to the short-chain fatty alcohol is 1.5:1 - 2:1, and the mass ratio of the short-chain fatty alcohol to epichlorohydrin is 1:1 - 1:1.2.
[0007] A preparation method of an asymmetric surfactant, for preparing an asymmetric surfactant as described above, includes the following steps: S1: Prepare an intermediate with an asymmetric structure through nucleophilic substitution reaction and ring-opening reaction; S2: Introduce two different hydrophilic groups on the intermediate with an asymmetric structure through substitution reaction; S3: Obtain the asymmetric surfactant through catalytic neutralization reaction.
[0008] The specific process of preparing an intermediate with an asymmetric structure through nucleophilic substitution reaction and ring-opening reaction in step S1 is as follows: S11: By weight, respectively take 10 parts of short-chain fatty alcohol, 100 - 200 parts of alkane solvent, 10 - 12 parts of epichlorohydrin, 15 - 20 parts of long-chain fatty alcohol; 0.002 - 0.0066 parts of quaternary ammonium salt catalyst, 0.00075 - 0.002 parts of basic catalyst; S12: Dissolve the short-chain fatty alcohol in the alkane solvent, add the quaternary ammonium salt catalyst, mechanically stir at 30 - 40 °C for 30 min, then raise the temperature to 50 - 60 °C, drip epichlorohydrin with a constant pressure funnel, control to finish dripping within 30 min, and carry out condensation reflux reaction for 2 - 3 h; S13: Dissolve long-chain fatty alcohol in the alkane solvent in step S12. After complete dissolution, add a basic catalyst, stir and mix evenly, then heat up to 60 - 70 °C, carry out condensation reflux reaction for 2 - 3 h. After the reaction is completed, wash with deionized water three times to remove the catalyst, then separate the deionized water, and remove the reaction solvent by vacuum distillation to obtain a light yellow transparent liquid, thus completing the preparation of the asymmetric carbon chain structure intermediate.
[0009] In the said step S11, the alkane solvent includes any one of cyclohexane, n-heptane and n-octane, the quaternary ammonium salt catalyst includes any one of benzyltriethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium hydrogen sulfate, and trimethyloctylammonium chloride, and the basic catalyst includes any one of sodium hydroxide and potassium hydroxide.
[0010] The specific process of introducing two different hydrophilic groups onto the asymmetric structure intermediate through substitution reaction in step S2 is as follows: S21: By weight, respectively take 10 parts of a modifier containing a hydrophilic group, 20 - 25 parts of the light yellow transparent liquid obtained in step S13, 0.003 - 0.007 parts of a quaternary ammonium salt catalyst, and 20 - 30 parts of ethanol. S22: Add the quaternary ammonium salt catalyst to the light yellow transparent liquid obtained in step S13, and stir to dissolve. S23: Dissolve the modifier containing a hydrophilic group in ethanol, slowly drop the ethanol solution into the solution obtained in S22, carry out condensation reflux, the reaction temperature is 50 - 60 °C, and the reaction time is 2 - 3 h to obtain an intermediate solution containing hydroxyl and carboxylate groups.
[0011] In the said step S21, the modifier containing a hydrophilic group includes any one of sodium 3-chloro-2-hydroxypropane sulfonate and sodium 5-chloro-2-hydroxybenzenesulfonate.
[0012] The specific process of obtaining the asymmetric structure surfactant through catalytic neutralization reaction in step S3 is as follows: S31: By weight, respectively take 10 parts of the intermediate solution containing hydroxyl and carboxylate groups obtained in step S23, 0.0001 - 0.0002 parts of ferric nitrate, 0.00008 - 0.0001 parts of 2,2,6,6-tetramethylpiperidine 1-oxide, and 1 - 2 parts of sodium bisulfite. S22: Add ferric nitrate and 2,2,6,6-tetramethylpiperidine 1-oxide to the intermediate solution containing hydroxyl and carboxylate groups obtained in step S23, after reacting at room temperature, add sodium bisulfite for neutralization reaction, remove the reaction solvent by decompression distillation, filter to remove insoluble catalysts and salts, to obtain an asymmetric structure surfactant containing two different hydrophobic chains and two different hydrophilic groups.
[0013] A method for using an asymmetric surfactant as an oil displacement agent in binary composite flooding. Use an asymmetric surfactant as described above. The specific process is as follows: Prepare an aqueous solution of partially hydrolyzed polyacrylamide with a mass fraction of 0.15% - 0.2%; add 0.15% - 0.3% of the asymmetric surfactant to the aqueous solution of partially hydrolyzed polyacrylamide, stir and mix evenly to prepare a binary composite system, and this binary composite system can be used as an oil displacement agent.
[0014] A method for using an asymmetric surfactant as a synergist in petroleum sulfonate binary composite flooding. Prepare an aqueous solution of partially hydrolyzed polyacrylamide with a mass fraction of 0.15% - 0.2%; add 0.15% of the asymmetric surfactant and 0.15% of petroleum sulfonate to the aqueous solution of partially hydrolyzed polyacrylamide, stir evenly to prepare a binary composite system, and this binary composite system can be used as an oil displacement agent.
[0015] The beneficial effects of the present invention are as follows: 1. The surfactant with an asymmetric structure synthesized by the present invention has two hydrophobic chains with different carbon chain lengths and two hydrophilic groups in its molecular structure. Compared with conventional surfactants, in the structure of the synthesized asymmetric surfactant, the two hydrophilic groups are connected together by chemical bonds, and the repulsive force between the hydrophilic groups is greatly weakened due to the chemical bond force. At the same time, the two hydrophobic hydrocarbon chains are in one molecular structure and are more likely to produce strong interactions, and the hydrophobic binding force between the hydrophobic chains is enhanced, making it easier to spontaneously adsorb on the oil-water interface and form a closely arranged structure, thus having higher surface activity, and the interfacial tension reaches 1×10 -2Below mN / m; 2. The product is a synthetic single component, and there will be no problem of product failure caused by chromatographic separation during actual use. The product has a longer shelf life, the binary composite system composed of anionic non-surfactant and polymer has better stability, has no influence on the polymer viscosity, the viscosity retention rate of the system is 99.61%, the interfacial activity is 0.0044 mN / m, and it has good interfacial tension and oil washing effect on crude oil. 3. The sulfonate group in the molecular structure has a similar structure to the commonly used petroleum sulfonate in oil fields, making it have good compatibility with petroleum sulfonate, has no obvious influence on the viscosity of the petroleum sulfonate binary composite system, the viscosity retention rate of the system is 100%, the interfacial activity is 0.0022 mN / m, and it has an obvious enhancement effect on the interfacial activity of the petroleum sulfonate and petroleum sulfonate binary composite system; 4. It can form an associative structure in water under low concentration conditions, the use concentration is lower than that of conventional surfactants, and the economy is better; because the molecule has two hydrophilic groups at the same time, the product also has good solubility under low temperature conditions, and the interfacial activity is not affected; the charge repulsion between the two hydrophilic groups in the molecular structure can improve the salt tolerance of the surfactant, avoid the influence of calcium and magnesium ions in formation water, and can also adjust the solubilization ability and interfacial activity of the product to crude oil by adjusting the carbon number of the two hydrophobic chains, matching the crude oil and reservoir conditions of different reservoirs, and having better universality.
[0016] The following will be further described with reference to the drawings. Brief Description of the Drawings
[0017] Figure 1 It is a chemical reaction flow chart for the preparation of an asymmetric structure surfactant in an embodiment of the present invention.
[0018] Figure 2 It is a graph showing the changes in pressure, water cut and recovery rate during oil displacement by a binary composite system in an embodiment of the present invention. Detailed Embodiments Example 1
[0019] An asymmetric structure surfactant, the asymmetric structure surfactant uses fatty alcohol and epichlorohydrin as raw materials, obtains an intermediate with two different hydrophobic long chains through two-step catalytic reaction, and then introduces two different hydrophilic groups through substitution reaction. The asymmetric structure surfactant has the structure shown in Formula I: Formula I; Among them, the structure of R1 is a C6-C10 short carbon chain alkyl chain; the structure of R2 is a C12-C22 long carbon chain alkyl chain; the structure of R3 is one of the two structures shown in Formula II or Formula III; Formula II; Formula III.
[0020] The fatty alcohols include short-chain fatty alcohols and long-chain fatty alcohols. The short-chain fatty alcohols are straight-chain fatty alcohols with 6 to 10 carbon atoms, and their structural general formula is Formula IV. The long-chain fatty alcohols are straight-chain fatty alcohols with 12 to 22 carbon atoms, and their structural general formula is Formula V; Formula IV; Formula V; The mass ratio of the long-chain fatty alcohol to the short-chain fatty alcohol is 1.5:1 - 2:1, and the mass ratio of the short-chain fatty alcohol to epichlorohydrin is 1:1 - 1:1.2. Example 2
[0021] As Figure 1 shown, a preparation method of an asymmetric surfactant is provided. To prepare an asymmetric surfactant as described above, the method includes the following steps: S1: Prepare an intermediate with an asymmetric structure through a nucleophilic substitution reaction and a ring-opening reaction; S2: Introduce two different hydrophilic groups onto the intermediate with an asymmetric structure through a substitution reaction; S3: Obtain the asymmetric surfactant through a catalytic neutralization reaction.
[0022] The specific process of preparing an intermediate with an asymmetric structure in step S1 through a nucleophilic substitution reaction and a ring-opening reaction is as follows: S11: By weight, respectively take 10 parts of short-chain fatty alcohol, 100 - 200 parts of alkane solvent, 10 - 12 parts of epichlorohydrin, 15 - 20 parts of long-chain fatty alcohol; 0.002 - 0.0066 parts of quaternary ammonium salt catalyst, 0.00075 - 0.002 parts of basic catalyst; S12: Dissolve the short-chain fatty alcohol in the alkane solvent, add the quaternary ammonium salt catalyst, mechanically stir at 30 - 40 °C for 30 min, then raise the temperature to 50 - 60 °C, and dropwise add epichlorohydrin using a constant pressure funnel, controlling to finish dropping within 30 min, and carry out a condensation reflux reaction for 2 - 3 h; S13: Dissolve the long-chain fatty alcohol in the alkane solvent in step S12. After complete dissolution, add the basic catalyst, stir and mix evenly, then raise the temperature to 60 - 70 °C, and carry out a condensation reflux reaction for 2 - 3 h. After the reaction is completed, wash 3 times with deionized water to remove the catalyst, then separate the deionized water, and remove the reaction solvent by vacuum distillation to obtain a light yellow transparent liquid, thus completing the preparation of the asymmetric carbon chain structure intermediate.
[0023] In the step S11, the alkane solvent includes any one of cyclohexane, n-heptane, and n-octane; the quaternary ammonium salt catalyst includes any one of benzyltriethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium hydrogensulfate, and trimethyloctylammonium chloride; the basic catalyst includes any one of sodium hydroxide and potassium hydroxide.
[0024] The specific process of introducing two different hydrophilic groups onto the asymmetric structure intermediate through a substitution reaction in the step S2 is as follows: S21: By weight, respectively take 10 parts of the modifier containing a hydrophilic group, 20 - 25 parts of the light yellow transparent liquid obtained in the step S13, 0.003 - 0.007 parts of the quaternary ammonium salt catalyst, and 20 - 30 parts of ethanol; S22: Add the quaternary ammonium salt catalyst to the light yellow transparent liquid obtained in the step S13 and stir to dissolve; S23: Dissolve the modifier containing a hydrophilic group in ethanol, slowly drop the ethanol solution into the solution obtained in S22, carry out condensation reflux, with the reaction temperature being 50 - 60 °C and the reaction time being 2 - 3 h, to obtain an intermediate solution containing hydroxyl and carboxylate groups.
[0025] In the step S21, the modifier containing a hydrophilic group includes any one of sodium 3-chloro-2-hydroxypropane sulfonate and sodium 5-chloro-2-hydroxybenzenesulfonate.
[0026] The specific process of obtaining the asymmetric surfactant through a catalytic neutralization reaction in the step S3 is as follows: S31: By weight, respectively take 10 parts of the intermediate solution containing hydroxyl and carboxylate groups obtained in the step S23, 0.0001 - 0.0002 parts of iron nitrate, 0.00008 - 0.0001 parts of 2,2,6,6-tetramethylpiperidine oxide, and 1 - 2 parts of sodium bisulfite; S22: Add iron nitrate and 2,2,6,6-tetramethylpiperidine oxide to the intermediate solution containing hydroxyl and carboxylate groups obtained in the step S23, after reacting at room temperature, add sodium bisulfite for neutralization reaction, remove the reaction solvent by reduced pressure distillation, and filter to remove the insoluble catalyst and salt, to obtain an asymmetric surfactant containing two different hydrophobic chains and two different hydrophilic groups. Example 3
[0027] A method for using an asymmetric surfactant, using an asymmetric surfactant as described above as an oil displacement agent in a binary composite flooding process. The specific process is as follows: Prepare an aqueous solution of partially hydrolyzed polyacrylamide with a mass fraction of 0.15%-0.2%; add 0.15%-0.3% of the asymmetric surfactant to the aqueous solution of partially hydrolyzed polyacrylamide, stir and mix evenly to prepare a binary composite system, which can be used as an oil displacement agent. Example 4
[0028] A method for using an asymmetric surfactant, using an asymmetric surfactant as described above as a synergist in a petroleum sulfonate binary composite flooding process. The specific process is as follows: Prepare an aqueous solution of partially hydrolyzed polyacrylamide with a mass fraction of 0.15%-0.2%; add 0.15% of the asymmetric surfactant and 0.15% of petroleum sulfonate to the aqueous solution of partially hydrolyzed polyacrylamide, stir evenly to prepare a binary composite system, which can be used as an oil displacement agent.
[0029] The preparation method of the asymmetric surfactant described in Example 2 was used to prepare the asymmetric surfactant in Example 1, specifically as described in Examples 5-6. The raw materials in Examples 5-6 were all purchased through commercial channels. Among them, fatty alcohol and epichlorohydrin were purchased from Shanghai Macklin Biochemical Co., Ltd., and 3-chloro-2-hydroxypropanesulfonic acid sodium salt and 5-chloro-2-hydroxybenzenesulfonic acid sodium salt were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. The analysis methods and instruments in this example are as follows: The viscosity was measured using a HAKKE MARS 40 Thermo Fisher rheometer; The interfacial activity was measured using a TX500C spinning drop interfacial tension meter; The oil displacement efficiency was measured using a DNQP-1 type oil displacement equipment.
[0030] The reference standard for the evaluation method is: Q / SY1583-2013 "Technical Specification for Surfactants Used in Binary Composite Flooding" Example 5
[0031] In this example, the preparation method of the asymmetric surfactant described in Example 2 was adopted. The specific process is as follows: S1: Add 200 mL of cyclohexane solvent into a three-necked flask. Dissolve 20 g of C6 fatty alcohol in cyclohexane, add 0.004 g of benzyltriethylammonium chloride, and stir mechanically at 30 °C for 30 min. Then raise the temperature to 50 °C, and slowly add 20 g of epichlorohydrin dropwise through a constant-pressure funnel, controlling to finish the dropping within 30 min. Carry out the reaction under reflux condensation for 2 h. Dissolve 30 g of C12 fatty alcohol in cyclohexane. After complete dissolution, add it into the three-necked flask, add 0.0015 g of sodium hydroxide, stir and mix evenly, then raise the temperature to 60 °C, and carry out the reaction under reflux condensation for 2 h. After the reaction is completed, wash with deionized water three times to remove the catalyst, and then separate the intermediate and deionized water through a separatory funnel. Remove the reaction solvent by vacuum distillation to obtain a light yellow transparent liquid, which is the prepared intermediate solution with an asymmetric carbon chain structure; S2: Add 40 g of the light yellow transparent intermediate solution obtained in step S1 into a three-necked flask, dissolve it with the recycled cyclohexane solvent, and add 0.0056 g of benzyltriethylammonium chloride, stir to dissolve. Then dissolve 16 g of 3-chloro-2-hydroxypropanesulfonic acid sodium, a modifier containing a hydrophilic group, in ethanol, and slowly add the 3-chloro-2-hydroxypropanesulfonic acid sodium ethanol solution dropwise to the intermediate solution, carry out the reaction under reflux condensation, with the reaction temperature at 50 °C and the reaction time of 2 h to obtain an intermediate solution containing hydroxyl and carboxylate groups; S3: Add 0.00056 g of iron nitrate and 0.00056 g of 2,2,6,6-tetramethylpiperidine oxide into the intermediate modified with a hydrophilic group obtained in step S2. Oxidize the hydroxyl group in the intermediate structure into a carboxyl group at room temperature, and then add 5.6 g of sodium bisulfite to neutralize the reaction to convert the carboxylic acid group into a carboxylate. Remove the reaction solvent by decompression distillation, and filter to remove the insoluble catalyst and salt to obtain an asymmetric structure surfactant containing two different hydrophobic chains and two different hydrophilic groups. Example 6
[0032] This example adopts the preparation method of an asymmetric structure surfactant described in Example 2, and the specific process is as follows: S1: Add 200 mL of n - heptane solvent into a three - necked flask. Dissolve 20 g of C8 fatty alcohol in n - heptane, add 0.0084 g of tetrabutylammonium chloride, and stir mechanically at 30 °C for 30 min. Then raise the temperature to 55 °C, and slowly add 22 g of epichlorohydrin dropwise through a constant - pressure funnel, controlling to finish the dropping within 30 min. Carry out the reaction under reflux condensation for 2 h. Dissolve 36 g of C18 fatty alcohol in n - heptane. After complete dissolution, add it into the three - necked flask, add 0.0028 g of sodium hydroxide, stir and mix evenly, then raise the temperature to 65 °C, and carry out the reaction under reflux condensation for 2 h. After the reaction is completed, wash with deionized water three times to remove the catalyst, then separate the intermediate and deionized water through a separatory funnel, and remove the reaction solvent by vacuum distillation to obtain a light - yellow transparent liquid, which is the prepared intermediate solution with an asymmetric carbon - chain structure; S2: Add 40 g of the light - yellow transparent intermediate solution obtained in step S1 into a three - necked flask, dissolve it with the recycled n - heptane solvent, add 0.0087 g of tetrabutylammonium chloride, and stir to dissolve. Then dissolve 18 g of 3 - chloro - 2 - hydroxypropanesulfonic acid sodium, a modifier containing a hydrophilic group, in ethanol, and slowly add the ethanol solution of 3 - chloro - 2 - hydroxypropanesulfonic acid sodium dropwise to the intermediate solution, carry out the reaction under reflux condensation, with the reaction temperature at 55 °C and the reaction time of 2 h to obtain an intermediate solution containing hydroxyl and carboxylate groups; S3: Add 0.0008 g of ferric nitrate and 0.0008 g of 2,2,6,6 - tetramethylpiperidine - 1 - oxide into the intermediate modified with a hydrophilic group obtained in step S2. Oxidize the hydroxyl group in the intermediate structure into a carboxyl group at room temperature, then add 8.7 g of sodium bisulfite to neutralize the reaction and convert the carboxylic acid group into a carboxylate group. Remove the reaction solvent by decompression distillation, filter to remove the insoluble catalyst and salts to obtain an asymmetric - structure surfactant containing two different hydrophobic chains and two different hydrophilic groups. Example 7
[0033] This example adopts the preparation method of an asymmetric - structure surfactant described in Example 2. The specific process is as follows: S1: Add 200 mL of n - octane solvent into a three - necked flask. Dissolve 20 g of C10 fatty alcohol in n - octane, add 0.013 g of tetrabutylammonium hydrogensulfate, and stir mechanically at 30 °C for 30 min. Then raise the temperature to 60 °C, and slowly add 24 g of epichlorohydrin dropwise through a constant - pressure funnel, controlling to finish the dropping within 30 min. Carry out the reaction under reflux condensation for 3 h. Dissolve 40 g of C22 fatty alcohol in n - octane. After complete dissolution, add it into the three - necked flask, add 0.004 g of potassium hydroxide, stir and mix evenly, then raise the temperature to 70 °C, and carry out the reaction under reflux condensation for 3 h. After the reaction is completed, wash with deionized water three times to remove the catalyst, then separate the intermediate and deionized water through a separatory funnel, and remove the reaction solvent by vacuum distillation to obtain a light - yellow transparent liquid, which is the prepared intermediate solution with an asymmetric carbon - chain structure.
[0034] S2: Add 40 g of the light yellow transparent intermediate solution obtained in step S1 into a three-necked flask, dissolve it using the recycled n-octane solvent, add 0.012 g of tetrabutylammonium hydrogen sulfate, and stir to dissolve; then dissolve 20 g of 5-chloro-2-hydroxybenzenesulfonate sodium, a modifier containing a hydrophilic group, in ethanol, slowly drip the 5-chloro-2-hydroxybenzenesulfonate sodium ethanol solution into the intermediate solution, carry out condensation reflux, with a reaction temperature of 60 °C and a reaction time of 3 h, to obtain an intermediate solution containing hydroxyl and carboxylate groups.
[0035] S3: Add 0.0008 g of iron nitrate and 0.00096 g of 2,2,6,6-tetramethylpiperidine 1-oxyl into the intermediate modified with a hydrophilic group obtained in step S2, oxidize the hydroxyl group in the intermediate structure into a carboxyl group at room temperature, then add 12 g of sodium bisulfite to neutralize the reaction to convert the carboxylic acid group into a carboxylate, remove the reaction solvent by decompression distillation, filter to remove insoluble catalysts and salts, to obtain an asymmetric surfactant containing two different hydrophobic chains and two different hydrophilic groups.
[0036] Perform an interfacial activity test on the performance of the asymmetric surfactants prepared in Examples 5 - 7. The measurement method is as follows: Prepare a surfactant dilution solution using simulated mineralized water with a mass concentration of 0.3%, use a TX500C rotating drop interfacial tensiometer to conduct an interfacial tension test, fill the measuring tube with the sample to be tested using a syringe; use a micro syringe to suck up dehydrated crude oil and inject it into the measuring tube to form a suitable oil droplet, avoiding the presence of air bubbles; set the test temperature of the interfacial tensiometer to the corresponding reservoir temperature, adjust the rotation speed to 5000 revolutions per minute, and start the instrument to conduct an interfacial tension test. The test results are shown in Table 1: Table 1 Interfacial Surfactant Test Results experimental group active agent active agent concentration % crude oil source temperature °C salinity mg / L interfacial tension mN / m 1 Example 5 0.3 Yumen Oilfield 30 14000 0.006 2 Example 6 0.3 Yumen Oilfield 30 14000 0.004 3 Example 7 0.3 Yumen Oilfield 30 14000 0.003 4 Example 5 0.3 Jiangsu Oilfield 74 20000 0.0008 5 Example 6 0.3 Jiangsu Oilfield 74 20000 0.0005 6 Example 7 0.3 Jiangsu Oilfield 74 20000 0.0003 Results and Analysis: As can be seen from Table 1, the synthesized asymmetric surfactants have good interfacial activity towards Yumen crude oil and Jiangsu crude oil, with the interfacial tension reaching below 1×10 -2 mN / m, meeting the standard requirements of Q / SY1583 - 2013 "Technical Specifications for Surfactants Used in Binary Composite Flooding", indicating that the synthesized asymmetric surfactants have good interfacial activity towards crude oils from different regions; it can also be seen from Table 1 that the higher the temperature, the better the interfacial activity of the surfactant; from Example 5 to Example 7, the carbon chain length of the synthesized asymmetric surfactants gradually increases, and the ability to reduce the oil-water interfacial activity is better, indicating that the long carbon chain has a stronger interaction with the crude oil, and the asymmetric surfactant with a wide carbon chain distribution is more likely to form an ultra-low interfacial tension.
[0037] Example 7 was selected to obtain a binary system composed of an asymmetric surfactant and a polymer, and the viscosity retention rate and interfacial activity of the binary composite system were evaluated. The specific process is as follows: Preparation of simulated mineralized water: The formula of the simulated brine is 11.14 grams of sodium chloride, 1.54 grams of calcium chloride, 0.42 g of magnesium chloride, 1.08 g of sodium bicarbonate, and 1.80 grams of sodium sulfate in every 1 L of solution; Preparation of polymer mother liquor: Add 300.00 g of simulated injection water to a clean beaker, and slowly add 3.00 g of polyacrylamide under mechanical stirring. Stir for 2 h until completely dissolved to obtain a 1% polyacrylamide mother liquor; Preparation of binary composite system: Take 1 100 mL beaker, prepare a 0.15% polyacrylamide dilution with simulated mineralized water, and add 0.3% of the asymmetric surfactant prepared in Example 3 to the base liquid respectively. Stir and mix evenly, and use a HAKKE MARS 40 Thermo Fisher rheometer for viscosity testing. Testing conditions: 30 °C, 7.34 s -1 , and test the interfacial activity of the binary composite system. The testing method is the same as above; Preparation of polymer blank: Take 1 100 mL beaker, prepare a 0.15% polyacrylamide dilution with simulated mineralized water, stir and mix evenly, and use a HAKKE MARS 40 Thermo Fisher rheometer for viscosity testing. Testing conditions: 30 °C, 7.34 s -1 . The experimental results are shown in Table 2: Table 2 Test results of binary composite system Experimental results and analysis: As can be seen from Table 2, the asymmetric surfactant and polyacrylamide synthesized in the present invention have good compatibility. The mixed system is uniform without precipitation, has no obvious effect on the polymer viscosity. The viscosity retention rate of the system is 99.61%, and the interfacial activity is 0.0044 mN / m, fully meeting the standard requirements of Q / SY1583-2013 "Technical Specification for Surfactants Used in Binary Composite Flooding", and can be used as an oil displacement agent in oilfield binary composite flooding.
[0038] A binary system composed of petroleum sulfonate and polymer used in the oilfield was used to evaluate the viscosity retention rate and interfacial surfactant of the binary composite system. The specific process method is as follows: The preparation of simulated mineralized water and polymer mother liquor is the same as that described above for evaluating the viscosity retention rate and interfacial activity of the binary composite system; Preparation of binary composite system: Take 1 100 mL beaker, prepare a 0.15% polyacrylamide dilution with simulated mineralized water, and add 0.3% petroleum sulfonate to the base liquid respectively. Stir and mix evenly, and use a HAKKE MARS 40 Thermo Fisher rheometer for viscosity testing. Testing conditions: 30 °C, 7.34 s -1, and test the interfacial activity of the binary composite system. The test method is the same as the interfacial activity test described above.
[0039] Prepare the polymer blank for the evaluation of the viscosity retention rate and interfacial activity test of the binary composite system as described above. The experimental results are shown in Table 3: Table 3 Test Results of Petroleum Sulfonate Binary Composite System Experimental Results and Analysis: As can be seen from Table 3, the use of petroleum sulfonate in the oil field has no obvious effect on the viscosity of the polymer. The viscosity retention rate of the system is 99.23%, but the interfacial activity is only 0.062 mN / m, and the ultra-low interfacial tension cannot be achieved.
[0040] Select the binary system composed of the asymmetric surfactant, petroleum sulfonate and polymer obtained in Example 7 to evaluate the viscosity retention rate and interfacial activity of the binary composite system. The specific process is as follows: The preparation of simulated formation water and polymer mother liquor is the same as the evaluation of the viscosity retention rate and interfacial activity test of the binary composite system described above; Preparation of Binary Composite System: Take a 100 mL beaker, prepare a 0.15% polyacrylamide dilution with simulated formation water, and add 0.15% of the asymmetric surfactant prepared in Example 3 and 0.15% of petroleum sulfonate to the base liquid respectively, stir and mix evenly, and use a HAKKE MARS 40 Thermo Fisher rheometer for viscosity testing. Test conditions: 30 °C, 7.34 s -1 , and test the interfacial activity of the binary composite system. The test method is the same as the interfacial activity test described above.
[0041] Prepare the polymer blank for the evaluation of the viscosity retention rate and interfacial activity test of the binary composite system as described above;. The experimental results are shown in Table 4: Table 4 Test Results of Mixed Surfactant Binary Composite System Test Results and Analysis: As can be seen from Table 4, the asymmetric surfactant and petroleum sulfonate synthesized in the present invention have good synergistic effects. The mixed surfactant and polyacrylamide have good compatibility. The mixed system is uniform without precipitation, and has no obvious effect on the viscosity of the polymer. The viscosity retention rate of the system is 100%, and the interfacial activity is 0.0022 mN / m, which fully meets the standard requirements of Q / SY 1583-2013 "Technical Specification for Surfactants for Binary Composite Flooding", and can be used as an oil displacement agent in the binary composite flooding of oil fields.
[0042] Evaluate the oil displacement efficiency of the binary composite system prepared from the mixed surfactant and polymer obtained above, and use a DNQP-1 type oil displacement equipment for enhanced oil recovery testing. The specific process is as follows: Core water saturation: After purchasing the core according to the design, dry it in an oven at 105 °C for 24 h, weigh the dry weight of the core, then evacuate and saturate the core with simulated water, weigh the core after saturation with water, and divide the mass difference of the core before and after saturation with water by the density of the simulated water to obtain the pore volume of the core; Measuring permeability: Place the saturated core in a core holder, saturate it with water at a rate of 1 mL / min, and measure the water-phase permeability of the core tube after the injection pressure stabilizes; Saturating with oil: Place the core tube in an oven at 30 °C and saturate it with the on-site dehydrated crude oil at a rate of 0.1 mL / min until the produced liquid contains no water. Record the water production, calculate the amount of saturated oil, and then age it overnight; Water flooding: After aging, perform water flooding at a rate of 0.2 mL / min, record the water production and oil production of the core tube, measure the produced liquid of the core tube, and end the water flooding when the comprehensive water cut reaches over 98%; Injecting the binary composite system: Inject the designed binary composite system at a rate of 0.2 mL / min, with an injection volume of 1 PV, and record the changes in the produced liquid, water cut, and oil content of the core tube; Subsequent water flooding: Displace at a rate of 0.2 mL / min, record the water content and oil content of the core tube, calculate the recovery rate, and end the water flooding when the comprehensive water cut reaches over 98%.
[0043] The experimental results are as Figure 2 shown, as Figure 2 shown in the figure, the changes in pressure, water cut, and recovery rate during the displacement process of 0.15% polymer + 0.15% surfactant prepared in Example 7 + 0.15% petroleum sulfonate are shown.
[0044] Experimental results and analysis: The equilibrium pressure during the water flooding process is 0.3 MPa; the injection pressure gradually increases during the injection process of the binary composite system of 0.15% polymer + 0.15% surfactant prepared in Example 7 + 0.15% petroleum sulfonate. After injecting 1 PV, the pressure increases to 1.15 MPa; during the subsequent water flooding, the pressure gradually decreases, and the equilibrium pressure is 0.36 MPa. The water flooding recovery rate reaches 31.57%. Injecting 1 PV of the binary composite system of 0.15% polymer + 0.15% surfactant prepared in Example 7 + 0.15% petroleum sulfonate increases the recovery rate by 21.06%, and there is an obvious water cut funnel; during the subsequent water flooding, the cumulative increase in the recovery rate is 27.64%. The indoor physical simulation experiment shows that the asymmetric structure surfactant and petroleum sulfonate synthesized in the present invention have good gain effects, and the binary composite system composed of the polymer has good oil displacement effects, and can be used as an oil displacement agent in the binary composite flooding of oil fields.
[0045] The above examples are only illustrative of the present invention and do not constitute a limitation on the scope of protection of the present invention. Any design identical or similar to the present invention falls within the scope of protection of the present invention. The reagent raw materials or methods not described in detail in the present invention are all prior arts and will not be further described in the present invention.
Claims
1. An asymmetric surfactant, characterized in that: The asymmetric structure surfactant uses fatty alcohol and epichlorohydrin as raw materials, and obtains an intermediate with two different hydrophobic long chains through two-step catalytic reactions, and then introduces two different hydrophilic groups through substitution reactions. The asymmetric structure surfactant has the structure shown in Formula I: Formula I; Among them, the structure of R1 is a C6-C10 short carbon chain alkyl chain; the structure of R2 is a C12-C22 long carbon chain alkyl chain; the structure of R3 is one of the two structures of Formula II or Formula III; Formula II; Formula III.
2. The asymmetric surfactant according to claim 1, characterized in that: The fatty alcohol includes short-chain fatty alcohol and long-chain fatty alcohol. The short-chain fatty alcohol is a straight-chain fatty alcohol with 6 to 10 carbon atoms, and its structural general formula is Formula IV. The long-chain fatty alcohol is a straight-chain fatty alcohol with 12 to 22 carbon atoms, and its structural general formula is Formula V; Formula IV; Formula V; The mass ratio of the long-chain fatty alcohol to the short-chain fatty alcohol is 1.5:1 - 2:1, and the mass ratio of the short-chain fatty alcohol to epichlorohydrin is 1:1 - 1:1.
2.
3. A method for preparing an asymmetric surfactant, for preparing an asymmetric surfactant as described in claim 1, characterized in that: It includes the following steps: S1: Prepare an intermediate with an asymmetric structure through nucleophilic substitution reaction and ring-opening reaction; S2: Introduce two different hydrophilic groups on the intermediate with an asymmetric structure through substitution reaction; S3: Obtain the asymmetric structure surfactant through catalytic neutralization reaction.
4. The preparation method of an asymmetric surfactant according to claim 3, characterized in that: The specific process of preparing an intermediate with an asymmetric structure in step S1 through nucleophilic substitution reaction and ring-opening reaction is as follows: S11: By weight, respectively take 10 parts of short-chain fatty alcohol, 100 - 200 parts of alkane solvent, 10 - 12 parts of epichlorohydrin, 15 - 20 parts of long-chain fatty alcohol; 0.002 - 0.0066 parts of quaternary ammonium salt catalyst, 0.00075 - 0.002 parts of basic catalyst; S12: Dissolve the short-chain fatty alcohol in the alkane solvent, add the quaternary ammonium salt catalyst, mechanically stir at 30 - 40 °C for 30 min, then raise the temperature to 50 - 60 °C, and drip epichlorohydrin with a constant pressure funnel, control to finish dripping within 30 min, and carry out condensation reflux reaction for 2 - 3 h; S13: Dissolve the long-chain fatty alcohol in the alkane solvent in step S12. After complete dissolution, add the basic catalyst, stir and mix evenly, then raise the temperature to 60 - 70 °C, carry out condensation reflux reaction for 2 - 3 h. After the reaction is completed, wash 3 times with deionized water to remove the catalyst, then separate the deionized water, and remove the reaction solvent by vacuum distillation to obtain a light yellow transparent liquid, completing the preparation of the asymmetric carbon chain structure intermediate.
5. The preparation method of an asymmetric surfactant according to claim 4, characterized in that: In step S11, the alkane solvent includes any one of cyclohexane, n-heptane, and n-octane, the quaternary ammonium salt catalyst includes any one of benzyltriethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium hydrogen sulfate, and trimethyloctylammonium chloride, and the basic catalyst includes any one of sodium hydroxide and potassium hydroxide.
6. The preparation method of an asymmetric surfactant according to claim 4, characterized in that: The specific process of introducing two different hydrophilic groups on the intermediate with an asymmetric structure in step S2 through substitution reaction is as follows: S21: By weight, respectively take 10 parts of the modifier containing hydrophilic groups, 20 - 25 parts of the light yellow transparent liquid obtained in step S13, 0.003 - 0.007 parts of quaternary ammonium salt catalyst, and 20 - 30 parts of ethanol; S22: Add a quaternary ammonium salt catalyst to the pale yellow transparent liquid obtained in step S13 and stir to dissolve it. S23: Dissolve the modifier containing a hydrophilic group in ethanol, slowly drop the ethanol solution into the solution obtained in S22, carry out condensation reflux, with the reaction temperature at 50 - 60 °C and the reaction time at 2 - 3 h, to obtain an intermediate solution containing hydroxyl and sodium carboxylate groups.
7. The preparation method of an asymmetric surfactant according to claim 6, wherein: In the said step S21, the modifier containing a hydrophilic group includes any one of sodium 3 - chloro - 2 - hydroxypropane sulfonate and sodium 5 - chloro - 2 - hydroxybenzenesulfonate.
8. The preparation method of an asymmetric surfactant according to claim 8, wherein: The specific process of obtaining the surfactant with an asymmetric structure through a catalytic neutralization reaction in step S3 is as follows: S31: By weight, respectively take 10 parts of the intermediate solution containing hydroxyl and sodium carboxylate groups obtained in step S23, 0.0001 - 0.0002 parts of ferric nitrate, 0.00008 - 0.0001 parts of 2,2,6,6 - tetramethylpiperidine oxide, and 1 - 2 parts of sodium bisulfite. S22: Add ferric nitrate and 2,2,6,6 - tetramethylpiperidine oxide to the intermediate solution containing hydroxyl and sodium carboxylate groups obtained in step S23, after reacting at room temperature, add sodium bisulfite for neutralization reaction, remove the reaction solvent by decompression distillation, and filter to remove the insoluble catalyst and salts, to obtain a surfactant with an asymmetric structure containing two different hydrophobic chains and two different hydrophilic groups.
9. A method for applying an asymmetric surfactant, using an asymmetric surfactant as described in claim 1 as an oil displacement agent in a binary composite flooding process, characterized in that: The specific process is as follows: Prepare an aqueous solution of partially hydrolyzed polyacrylamide with a mass fraction of 0.15% - 0.2%; add 0.15% - 0.3% of the said surfactant with an asymmetric structure to the aqueous solution of partially hydrolyzed polyacrylamide, and stir and mix evenly to prepare a binary composite system, which can be used as an oil displacement agent.
10. A method for applying an asymmetric surfactant, which uses an asymmetric surfactant as described in claim 1 as a synergist in the binary composite flooding of petroleum sulfonate, is characterized in that: Prepare an aqueous solution of partially hydrolyzed polyacrylamide with a mass fraction of 0.15% - 0.2%; add 0.15% of the said surfactant with an asymmetric structure and 0.15% of petroleum sulfonate to the aqueous solution of partially hydrolyzed polyacrylamide, and stir evenly to prepare a binary composite system, which can be used as an oil displacement agent.