Salt-resistant functional monomer suitable for high-salt oil field environment and preparation method of salt-resistant functional monomer
By preparing highly salt-resistant functional monomers, the problem of insufficient salt resistance in polymer flooding in high-salt oilfield environments has been solved, achieving high oil recovery and viscosity stability, and making it suitable for high-salt oilfield environments.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 黑龙江吉地油田服务股份有限公司
- Filing Date
- 2026-01-09
- Publication Date
- 2026-05-12
AI Technical Summary
Existing salt-resistant functional monomers and polymers used in high-salt oilfields have drawbacks such as limited salt resistance, high synthesis cost, poor polymerization activity, or poor solubility, making it difficult to effectively improve oil recovery in high-salt environments.
A salt-resistant functional monomer suitable for high-salt oilfield environments was synthesized. A highly salt-resistant and thickening polymer was prepared by combining a specific initiator and monomer. The polymer was formulated using produced wastewater from the oilfield and maintained good solubility.
It improves oil recovery rate, and the polymer maintains high viscosity stability and good solubility in high-salt environments, significantly improving oil displacement efficiency.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of petroleum extraction technology, specifically relating to a salt-resistant functional monomer suitable for high-salt oilfield environments and its preparation method. Background Technology
[0002] With the continued growth of global energy demand and the increasing depletion of easily exploitable oil resources, the efficient development of complex oil reservoirs has become an urgent task for the petroleum industry. Among them, high-salinity oil reservoirs are rich in reserves, but extremely difficult to extract. Polymer flooding, as one of the key technologies for enhancing oil recovery in tertiary oil recovery, works by injecting a high-molecular-weight polymer solution into the oil reservoir to increase the viscosity of the aqueous phase, reduce the water-oil mobility ratio, and expand the swept volume, thereby displacing more residual oil.
[0003] Currently, partially hydrolyzed polyacrylamide (HPAM) is the most widely used polymer in polymer flooding (FLAG) technology, mainly due to its low cost, strong thickening ability, and ease of industrial production. However, the application of HPAM in high-salt reservoir environments faces severe challenges. While existing salt-resistant functional monomers and polymers for high-salt oilfields have shown some effectiveness, they generally suffer from one or more drawbacks, such as limited salt resistance, high synthesis costs, poor polymerization activity, or poor solubility of the final product. Therefore, there is an urgent need in this field for a novel functional monomer with a simple synthesis route, controllable cost, high polymerization activity, and the ability to impart excellent salt and calcium resistance properties to polymers. Such products have a huge market potential. Summary of the Invention
[0004] To address the aforementioned problems, this invention provides a salt-resistant functional monomer suitable for high-salt oilfield environments and its preparation method. The polymer synthesized using this functional monomer exhibits high salt resistance, high viscosity enhancement, high viscosity stability, and the ability to be formulated using produced wastewater from oilfields. Under wastewater conditions, it maintains good solubility, thereby improving oil recovery.
[0005] The technical solution adopted in this invention is as follows: synthesizing a salt-resistant functional monomer suitable for high-salt oilfield environments, and using the functional monomer to synthesize a salt-resistant polymer suitable for high-salt oilfield environments; The components and weight parts of the salt-resistant polymer are as follows: 210-260 parts of acrylamide; 15-30 parts of AMPS; 6-15 parts of AEO-9; 20-50 parts of functional monomer S; 10-20 parts of urea; 0.2-0.3 parts of initiator #1; 0.05-0.15 parts of initiator #2; 0.05-0.15 parts of initiator #3; 0.1-0.3 parts of initiator #4; and water to a total of 1000 parts.
[0006] Furthermore, the #1 initiator is one or more of azobisisobutyronitrile, azobisisoheptanenitrile, or azobisisobutylamidine hydrochloride.
[0007] Furthermore, the #2 initiator is one or more of sodium formate, sodium acetate, or isopropanol.
[0008] Furthermore, the #3 initiator is one or more of ammonium persulfate, potassium persulfate, or sodium persulfate.
[0009] Furthermore, the #4 initiator is one or more of sodium bisulfite, sodium thiosulfate, or triethanolamine.
[0010] Furthermore, the functional unit S is:
[0011] Furthermore, the preparation method of the functional monomer S includes the following steps: Step 1: Add the solvent p-tert-butylbromobenzene to the reaction vessel. Its molecular formula is:
[0012] Continue adding cyclohexylboronic acid to the reactor, continuously purging with nitrogen gas, then adding palladium catalyst Pd(dppf)Cl2, potassium carbonate solution dissolved in water, and solvent 1,4-dioxane. Heat the reactor to 80-90℃ and stir under reflux for about 12 hours. The reaction formula is:
[0013] After the reaction was completed, the reaction solution was cooled to room temperature, and water and ethyl acetate were added in a ratio of approximately 1:1. Extraction was performed 2-3 times. All organic phases were combined and washed once with saturated sodium chloride solution. The organic phases were then dried with anhydrous sodium sulfate, filtered, and the solvent was removed by rotary evaporation. The intermediate 1 was then purified by silica gel column chromatography using a mixture of petroleum ether and ethyl acetate as the eluent. Step 2: Add intermediate 1 obtained in Step 1 and solvent dichloromethane to the reaction vessel. Slowly add a mixture of nitric acid and sulfuric acid dropwise at a temperature of 0-5℃ to carry out the reaction. The reaction equation is as follows: ; After the reaction, the reaction mixture was quenched in ice water, then extracted with dichloromethane, and purified by recrystallization with a mixture of ethanol and water to obtain intermediate 2. Step 3: Place intermediate 2 obtained in Step 2 into a reaction vessel, add solvent ethanol and catalyst Pd / C, and react by introducing H2 at 2 atmospheres and room temperature. The reaction equation is as follows:
[0014] After the reaction was completed, the solid catalyst was removed by filtration, and the product was purified by recrystallization to obtain intermediate 3. Step 4: Add intermediate 3 obtained in Step 3 to a round-bottom flask and place it in an ice-water bath. Add solvent DCM and a small amount of sodium hydroxide solution. Slowly add acryloyl chloride dropwise, maintaining the temperature at 0-5℃. The reaction equation is:
[0015] After the reaction was completed, the temperature was raised to room temperature and stirring was continued for 2 hours. A small amount of sodium hydroxide solution was added to react with the remaining acryloyl chloride. The mixture was filtered through a separatory funnel, and the organic phase was washed with saturated sodium chloride. After adding anhydrous sodium sulfate, the mixture was filtered and then evaporated at low temperature. After recrystallization and purification, intermediate 4 was obtained. Step 5: Dissolve intermediate 4 obtained in step 4 in anhydrous toluene, add it to a round-bottom flask, and slowly add phosphorus trichloride dropwise to the reaction solution. Heat to 110℃ and react for 8 hours. The reaction formula is:
[0016] After the reaction, the reaction solution was slowly cooled to 0°C, and then slowly poured into a saturated sodium bicarbonate solution with vigorous stirring. The aqueous phase was extracted three times with ethyl acetate, and the combined organic phases were washed with saturated sodium chloride. The organic phase was dried with anhydrous sodium sulfate, filtered, and rotary evaporated to obtain the crude product. The crude product was then purified by silica gel column chromatography (using a mixture of petroleum ether and ethyl acetate as the eluent) to obtain intermediate 5. Step Six: Dissolve intermediate 5 obtained in Step Five in dichloromethane, cool to 0°C in an ice-water bath, and slowly add a solution of acetyl nitrate cooled to 0°C dropwise into the reaction mixture through a dropping funnel while stirring vigorously. Maintain the temperature at 0°C during the addition process. After the addition is complete, continue stirring at 0°C for 3 hours. The reaction equation is:
[0017] After the reaction was completed, the reaction solution was poured into ice water, and the aqueous phase was extracted three times with dichloromethane. The organic phases were combined and washed with ice water, saturated sodium bicarbonate solution, and saturated sodium chloride solution. The organic phase was dried with anhydrous magnesium sulfate and then filtered and rotary evaporated to obtain intermediate 6. Step 7: The intermediate 6 obtained in Step 6 is reacted in a flask with excess stannous chloride under reflux in an ethanol / hydrochloric acid solution. The reaction equation is as follows:
[0018] After the reaction was completed, the solid catalyst was removed by filtration and purified by recrystallization to obtain intermediate 7; Step 8: Dissolve intermediate 7 obtained in Step 7 in dilute hydrochloric acid (HCl) and cool in an ice bath to 0-5°C. While stirring vigorously, slowly add an aqueous solution of NaNO2. After the reaction is complete, add the resulting diazonium salt solution to a sodium sulfite solution while cooling, and then heat appropriately to ensure the reaction is complete. The reaction equation is: After drying and purification, the obtained product yielded intermediate 8; Step 9: Dissolve intermediate 8 obtained in step 8 in dichloromethane, pour the solution into a round-bottom flask, add a small amount of triethylamine, and slowly add acryloyl chloride dropwise at 0°C. After the addition is complete, react for 1-2 hours, then gradually raise the temperature to room temperature and continue stirring for 12 hours. The reaction equation is:
[0019] After the reaction was completed, the reaction solution was poured into a saturated ammonium chloride solution and extracted three times with DCM. The organic phases were combined and washed with saturated sodium bicarbonate solution and sodium chloride solution. Then, the solution was dried with anhydrous sodium sulfate and the solvent was removed by rotary evaporation to obtain the functional monomer S.
[0020] Furthermore, a method for preparing a salt-resistant polymer synthesized from a salt-resistant functional monomer suitable for high-salt oilfield environments includes the following steps: (1) Mix the functional monomer S and AEO-9 and set aside for later use; (2) Dissolve AMPS in ice water and then neutralize with sodium carbonate; (3) After mixing acrylamide with the monomer prepared in steps (1) and (2) with urea and water, adjust the pH value with 30% sodium hydroxide solution until the pH value is 7.0-7.5; (4) After adjusting the temperature of the solution prepared in step (3) to 4℃-6℃, transfer the solution to an insulated reactor and then introduce nitrogen gas for 30 minutes to remove oxygen. After deoxygenation, add initiator 1 and initiator 2 to the reactor, add initiator 3 after 5 minutes, and add initiator 4 after another 5 minutes. Stop introducing nitrogen gas after the system in the reactor starts to heat up. After the reaction is completed and the temperature stops rising, continue to mature for 4 hours to obtain polymer colloid. (5) The polymer colloid obtained in step (4) is crushed, solid sodium hydroxide is added, and after being fully mixed, it is hydrolyzed at 75°C for 6 hours and then dried at 60°C for 12 hours. After crushing and sieving, particles with a particle size of 400-800μm are obtained. These particles are the finished product of salt-resistant polymer suitable for high-salt oilfield environments.
[0021] The beneficial effects of the present invention are as follows: The present invention provides a salt-resistant functional monomer suitable for high-salt oilfield environments and its preparation method. The polymer synthesized using this functional monomer has the characteristics of high salt resistance, high viscosity, high viscosity stability, and can be formulated using produced wastewater from oilfields. Under wastewater conditions, it can maintain good solubility and viscosity, thereby improving oil recovery rate. Detailed Implementation
[0022] This salt-resistant functional monomer, hereinafter referred to as functional monomer S, is suitable for high-salt oilfield environments. The functional monomer S is: .
[0023] The preparation method of the functional monomer S includes the following steps: Step 1: Add the solvent p-tert-butylbromobenzene to the reaction vessel. Its molecular formula is:
[0024] Continue adding cyclohexylboronic acid to the reactor, continuously purging with nitrogen gas, then adding palladium catalyst Pd(dppf)Cl2, potassium carbonate solution dissolved in water, and solvent 1,4-dioxane. Heat the reactor to 80-90℃ and stir under reflux for about 12 hours. The reaction formula is:
[0025] After the reaction was completed, the reaction solution was cooled to room temperature, and water and ethyl acetate were added in a ratio of approximately 1:1. Extraction was performed 2-3 times. All organic phases were combined and washed once with saturated sodium chloride solution. The organic phases were then dried with anhydrous sodium sulfate, filtered, and the solvent was removed by rotary evaporation. The intermediate 1 was then purified by silica gel column chromatography using a mixture of petroleum ether and ethyl acetate as the eluent. Step 2: Add intermediate 1 obtained in Step 1 and solvent dichloromethane to the reaction vessel. Slowly add a mixture of nitric acid and sulfuric acid dropwise at a temperature of 0-5℃ to carry out the reaction. The reaction equation is as follows: ; After the reaction, the reaction mixture was quenched in ice water, then extracted with dichloromethane, and purified by recrystallization with a mixture of ethanol and water to obtain intermediate 2. Step 3: Place intermediate 2 obtained in Step 2 into a reaction vessel, add solvent ethanol and catalyst Pd / C, and react by introducing H2 at 2 atmospheres and room temperature. The reaction equation is as follows:
[0026] After the reaction was completed, the solid catalyst was removed by filtration, and the product was purified by recrystallization to obtain intermediate 3. Step 4: Add intermediate 3 obtained in Step 3 to a round-bottom flask and place it in an ice-water bath. Add solvent DCM and a small amount of sodium hydroxide solution. Slowly add acryloyl chloride dropwise, maintaining the temperature at 0-5℃. The reaction equation is:
[0027] After the reaction was completed, the temperature was raised to room temperature and stirring was continued for 2 hours. A small amount of sodium hydroxide solution was added to react with the remaining acryloyl chloride. The mixture was filtered through a separatory funnel, and the organic phase was washed with saturated sodium chloride. After adding anhydrous sodium sulfate, the mixture was filtered and then evaporated at low temperature. After recrystallization and purification, intermediate 4 was obtained. Step 5: Dissolve intermediate 4 obtained in step 4 in anhydrous toluene, add it to a round-bottom flask, and slowly add phosphorus trichloride dropwise to the reaction solution. Heat to 110℃ and react for 8 hours. The reaction formula is:
[0028] After the reaction, the reaction solution was slowly cooled to 0°C, and then slowly poured into a saturated sodium bicarbonate solution with vigorous stirring. The aqueous phase was extracted three times with ethyl acetate, and the combined organic phases were washed with saturated sodium chloride. The organic phase was dried with anhydrous sodium sulfate, filtered, and rotary evaporated to obtain the crude product. The crude product was then purified by silica gel column chromatography (using a mixture of petroleum ether and ethyl acetate as the eluent) to obtain intermediate 5. Step Six: Dissolve intermediate 5 obtained in Step Five in dichloromethane, cool to 0°C in an ice-water bath, and slowly add a solution of acetyl nitrate cooled to 0°C dropwise into the reaction mixture through a dropping funnel while stirring vigorously. Maintain the temperature at 0°C during the addition process. After the addition is complete, continue stirring at 0°C for 3 hours. The reaction equation is:
[0029] After the reaction was completed, the reaction solution was poured into ice water, and the aqueous phase was extracted three times with dichloromethane. The organic phases were combined and washed with ice water, saturated sodium bicarbonate solution, and saturated sodium chloride solution. The organic phase was dried with anhydrous magnesium sulfate and then filtered and rotary evaporated to obtain intermediate 6. Step 7: The intermediate 6 obtained in Step 6 is reacted in a flask with excess stannous chloride under reflux in an ethanol / hydrochloric acid solution. The reaction equation is as follows:
[0030] After the reaction was completed, the solid catalyst was removed by filtration and purified by recrystallization to obtain intermediate 7; Step 8: Dissolve intermediate 7 obtained in Step 7 in dilute hydrochloric acid (HCl) and cool in an ice bath to 0-5°C. While stirring vigorously, slowly add an aqueous solution of NaNO2. After the reaction is complete, add the resulting diazonium salt solution to a sodium sulfite solution while cooling, and then heat appropriately to ensure complete reaction. The reaction equation is: After drying and purification, the obtained product yielded intermediate 8; Step 9: Dissolve intermediate 8 obtained in step 8 in dichloromethane, pour the solution into a round-bottom flask, add a small amount of triethylamine, and slowly add acryloyl chloride dropwise at 0°C. After the addition is complete, react for 1-2 hours, then gradually raise the temperature to room temperature and continue stirring for 12 hours. The reaction equation is:
[0031] After the reaction was completed, the reaction solution was poured into a saturated ammonium chloride solution and extracted three times with DCM. The organic phases were combined and washed with saturated sodium bicarbonate solution and sodium chloride solution. Then, the solution was dried with anhydrous sodium sulfate and the solvent was removed by rotary evaporation to obtain the functional monomer S. Example
[0032] A method for preparing a salt-resistant polymer synthesized from a salt-resistant functional monomer suitable for high-salt oilfield environments includes the following steps: (1) Mix 20 parts of functional monomer S and 6 parts of AEO-9 and set aside for later use; (2) Dissolve 15 parts of AMPS in ice water and then neutralize with sodium carbonate; (3) Add 210 parts of acrylamide and the monomer prepared in steps (1) and (2) to 10 parts of urea and 738.7 parts of water and stir evenly. Then adjust the pH value with 30% sodium hydroxide solution until the pH value is 7.0-7.5. The molecular formula of functional monomer S is:
[0033] (4) After adjusting the temperature of the solution prepared in step (3) to 4℃-6℃, transfer the solution to an insulated reactor and then purge with nitrogen for 30 minutes to remove oxygen; after deoxygenation, add 0.2 parts of No. 1 initiator and 0.05 parts of No. 2 initiator to the reactor, add 0.05 parts of No. 3 initiator after 5 minutes, and add 0.1 parts of No. 4 initiator after another 5 minutes. Stop purging with nitrogen after the system in the reactor starts to heat up; after the reaction is complete and the temperature stops rising, continue to mature for 4 hours to obtain polymer colloid; (5) The polymer colloid obtained in step (4) is crushed, solid sodium hydroxide is added, and after being fully mixed, it is hydrolyzed at 75°C for 6 hours and then dried at 60°C for 12 hours. After crushing and sieving, particles with a particle size of 400-800μm are obtained. These particles are the finished product of salt-resistant polymer suitable for high-salt oilfield environments. Example
[0034] A method for preparing a salt-resistant polymer synthesized from a salt-resistant functional monomer suitable for high-salt oilfield environments includes the following steps: (1) Mix 20 parts of functional monomer S and 10 parts of AEO-9 and set aside for later use; (2) Dissolve 15 parts of AMPS in ice water and then neutralize with sodium carbonate; (3) Add 220 parts of acrylamide and the monomer prepared in steps (1) and (2) to 20 parts of urea and 714.7 parts of water and stir evenly. Then adjust the pH value with 30% sodium hydroxide solution until the pH value is 7.0-7.5. The molecular formula of functional monomer S is:
[0035] (4) After adjusting the temperature of the solution prepared in step (3) to 4℃-6℃, transfer the solution to an insulated reactor and then purge with nitrogen for 30 minutes to remove oxygen; after deoxygenation, add 0.2 parts of No. 1 initiator and 0.05 parts of No. 2 initiator to the reactor, add 0.05 parts of No. 3 initiator after 5 minutes, and add 0.1 parts of No. 4 initiator after another 5 minutes. Stop purging with nitrogen after the system in the reactor starts to heat up; after the reaction is complete and the temperature stops rising, continue to mature for 4 hours to obtain polymer colloid; (5) The polymer colloid obtained in step (4) is crushed, solid sodium hydroxide is added, and after being fully mixed, it is hydrolyzed at 75°C for 6 hours and then dried at 60°C for 12 hours. After crushing and sieving, particles with a particle size of 400-800μm are obtained. These particles are the finished product of salt-resistant polymer suitable for high-salt oilfield environments. Example
[0036] A method for preparing a salt-resistant polymer synthesized from a salt-resistant functional monomer suitable for high-salt oilfield environments includes the following steps: (1) Mix 30 parts of functional monomer S and 10 parts of AEO-9 and set aside for later use; (2) Dissolve 20 parts of AMPS in ice water and then neutralize with sodium carbonate; (3) Add 230 parts of acrylamide and the monomer prepared in steps (1) and (2) to 10 parts of urea and 699.55 parts of water and stir evenly. Then adjust the pH value with 30% sodium hydroxide solution until the pH value is 7.0-7.5. The molecular formula of functional monomer S is:
[0037] (4) After adjusting the temperature of the solution prepared in step (3) to 4℃-6℃, transfer the solution to an insulated reactor and then purge with nitrogen for 30 minutes to remove oxygen; after deoxygenation, add 0.25 parts of initiator 1 and 0.1 parts of initiator 2 to the reactor, add 0.1 parts of initiator 3 after 5 minutes, and add 0.2 parts of initiator 4 after another 5 minutes. Stop purging with nitrogen after the system in the reactor starts to heat up; after the reaction is complete and the temperature stops rising, continue to mature for 4 hours to obtain polymer colloid; (5) The polymer colloid obtained in step (4) is crushed, solid sodium hydroxide is added, and after being fully mixed, it is hydrolyzed at 75°C for 6 hours and then dried at 60°C for 12 hours. After crushing and sieving, particles with a particle size of 400-800μm are obtained. These particles are the finished product of salt-resistant polymer suitable for high-salt oilfield environments. Example
[0038] A method for preparing a salt-resistant polymer synthesized from a salt-resistant functional monomer suitable for high-salt oilfield environments includes the following steps: (1) Mix 30 parts of functional monomer S and 10 parts of AEO-9 and set aside for later use; (2) Dissolve 25 parts of AMPS in ice water and then neutralize with sodium carbonate; (3) Add 240 parts of acrylamide and the monomer prepared in steps (1) and (2) to 20 parts of urea and 674.55 parts of water and stir evenly. Then adjust the pH value with 30% sodium hydroxide solution until the pH value is 7.0-7.5. The molecular formula of functional monomer S is:
[0039] (4) After adjusting the temperature of the solution prepared in step (3) to 4℃-6℃, transfer the solution to an insulated reactor and then purge with nitrogen for 30 minutes to remove oxygen; after deoxygenation, add 0.25 parts of initiator 1 and 0.1 parts of initiator 2 to the reactor, add 0.1 parts of initiator 3 after 5 minutes, and add 0.2 parts of initiator 4 after another 5 minutes. Stop purging with nitrogen after the system in the reactor starts to heat up; after the reaction is complete and the temperature stops rising, continue to mature for 4 hours to obtain polymer colloid; (5) The polymer colloid obtained in step (4) is crushed, solid sodium hydroxide is added, and after being fully mixed, it is hydrolyzed at 75°C for 6 hours and then dried at 60°C for 12 hours. After crushing and sieving, particles with a particle size of 400-800μm are obtained. These particles are the finished product of salt-resistant polymer suitable for high-salt oilfield environments. Example
[0040] A method for preparing a salt-resistant polymer synthesized from a salt-resistant functional monomer suitable for high-salt oilfield environments includes the following steps: (1) Mix 40 parts of functional monomer S and 15 parts of AEO-9 and set aside for later use; (2) Dissolve 25 parts of AMPS in ice water and then neutralize with sodium carbonate; (3) Add 250 parts of acrylamide and the monomer prepared in steps (1) and (2) to 10 parts of urea and 659.4 parts of water and stir evenly. Then adjust the pH value with 30% sodium hydroxide solution until the pH value is 7.0-7.5. The molecular formula of functional monomer S is:
[0041] (4) After adjusting the temperature of the solution prepared in step (3) to 4℃-6℃, transfer the solution to an insulated reactor and then purge with nitrogen for 30 minutes to remove oxygen; after deoxygenation, add 0.3 parts of No. 1 initiator and 0.15 parts of No. 2 initiator to the reactor, add 0.15 parts of No. 3 initiator after 5 minutes, and add 0.3 parts of No. 4 initiator after another 5 minutes. Stop purging with nitrogen after the system in the reactor starts to heat up; after the reaction is complete and the temperature stops rising, continue to mature for 4 hours to obtain polymer colloid; (5) The polymer colloid obtained in step (4) is crushed, solid sodium hydroxide is added, and after being fully mixed, it is hydrolyzed at 75°C for 6 hours and then dried at 60°C for 12 hours. After crushing and sieving, particles with a particle size of 400-800μm are obtained. These particles are the finished product of salt-resistant polymer suitable for high-salt oilfield environments. Example
[0042] A method for preparing a salt-resistant polymer synthesized from a salt-resistant functional monomer suitable for high-salt oilfield environments includes the following steps: (1) Mix 50 parts of functional monomer S and 15 parts of AEO-9 and set aside for later use; (2) Dissolve 30 parts of AMPS in ice water and then neutralize with sodium carbonate; (3) Add 260 parts of acrylamide and the monomer prepared in steps (1) and (2) to 20 parts of urea and 624.4 parts of water and stir evenly. Then adjust the pH value with 30% sodium hydroxide solution until the pH value is 7.0-7.5. The molecular formula of functional monomer S is:
[0043] (4) After adjusting the temperature of the solution prepared in step (3) to 4℃-6℃, transfer the solution to an insulated reactor and then purge with nitrogen for 30 minutes to remove oxygen; after deoxygenation, add 0.3 parts of No. 1 initiator and 0.15 parts of No. 2 initiator to the reactor, add 0.15 parts of No. 3 initiator after 5 minutes, and add 0.3 parts of No. 4 initiator after another 5 minutes. Stop purging with nitrogen after the system in the reactor starts to heat up; after the reaction is complete and the temperature stops rising, continue to mature for 4 hours to obtain polymer colloid; (5) The polymer colloid obtained in step (4) is crushed, solid sodium hydroxide is added, and after being fully mixed, it is hydrolyzed at 75°C for 6 hours and then dried at 60°C for 12 hours. After crushing and sieving, particles with a particle size of 400-800μm are obtained. These particles are the finished product of salt-resistant polymer suitable for high-salt oilfield environments.
[0044] The performance of a salt-resistant polymer synthesized from a salt-resistant functional monomer suitable for high-salt oilfield environments according to the present invention is evaluated below: 1. Evaluation of salt resistance The salt-resistant polymers synthesized from salt-resistant functional monomers suitable for high-salt oilfield environments prepared in Examples 1, 2, 3, 4, 5, and 6 above are compared with the salt-resistant properties of ordinary polymers.
[0045] The evaluation method is as follows: Examples 1-6 and ordinary polymers were prepared and diluted to 1000 mg / L with simulated wastewater of different mineralization degrees, and the viscosity was measured with a Brookfield viscometer.
[0046] The viscosity is shown in the table below: (Table 1) Viscosity under different salinity conditions
[0047] As shown in the experimental results in the table above, the salt-resistant polymers synthesized from salt-resistant functional monomers suitable for high-salt oilfield environments exhibit significantly higher salt resistance than ordinary polymers. 2. Molecular weight evaluation The molecular weights of Examples 1-6 were measured using an Ubbelohde viscometer, and the molecular weight distributions are shown in the table below: (Table 2) Molecular weight distribution
[0048] As can be seen from the data in the table above, the salt-resistant polymers synthesized from the salt-resistant functional monomers suitable for high-salt oilfield environments in Examples 1-6 have a molecular weight distribution range between 12 million and 22 million, which is wide and can be easily produced by adjusting the formula.
[0049] 3. Evaluation of oil displacement performance Oil displacement scheme: Artificial core φ2.5×10cm, water flooding to 98% water cut, then switch to polymer flooding, followed by water flooding to 98% water cut, displacement rate of 0.1ml / min, chemical flooding injection volume of 0.6pv, experimental temperature 45℃.
[0050] The polymers used in the polymer flooding were salt-resistant polymers synthesized from salt-resistant functional monomers suitable for high-salt oilfield environments prepared in Examples 1-6, and ordinary intermediate polymers, with a concentration of 1000 mg / L. The prepared polymer solutions were sealed and placed at 45°C for 7 days before the experiment.
[0051] The water used in the experiment was produced wastewater from an oilfield. The table below shows the results of the oil displacement experiment: (Table 3) Results of Oil Displacement Experiment
[0052] As shown in the table above, in the oil displacement experiments after 7 days of storage in Examples 1-6, the recovery rate of polymer flooding was around 20%, which is much higher than that of ordinary polymers. This indicates that after 7 days of storage, the salt-resistant polymer synthesized from salt-resistant functional monomers suitable for high-salt oilfield environments has a better oil displacement efficiency than ordinary polymers.
[0053] 4. Evaluation of emulsifying ability The emulsifying ability of salt-resistant polymers synthesized from salt-resistant functional monomers suitable for high-salt oilfield environments prepared in Examples 1, 2, 3, 4, 5, and 6 above was compared with that of ordinary polymers.
[0054] A 5000 mg / L mother liquor was prepared using clean water from a water sample from an oilfield, and a 1000 mg / L target liquor was prepared using produced wastewater from the same oilfield. This was mixed with the dehydrated crude oil from the same oilfield at a 1:1 ratio and placed into a 25 ml colorimetric tube. After preheating at 45°C, the tube was shaken 300 times by hand and placed in a 45°C water bath for 1 hour. The water separation rate was then observed and calculated.
[0055] (Table 4) Results of Emulsification Experiment
[0056] As shown in the table above, after emulsification for 1 hour, the water separation rate of Examples 1-6 was all below 5%, which is better than that of ordinary polymers. It can more easily drive out the remaining oil in the rock pores, thereby improving the recovery rate.
Claims
1. A salt-resistant functional monomer suitable for high-salinity oilfield environments, characterized in that: The molecular structure is shown in the figure below, hereinafter referred to as functional monomer S. The functional monomer S is: 。 2. The method for preparing salt-resistant functional monomers suitable for high-salinity oilfield environments according to claim 1, characterized in that: The preparation method of the functional monomer S includes the following steps: Step 1: Add the solvent p-tert-butylbromobenzene to the reaction vessel. Its molecular formula is: Continue adding cyclohexylboronic acid to the reactor, continuously purging with nitrogen gas, then adding palladium catalyst Pd(dppf)Cl2, potassium carbonate solution dissolved in water, and solvent 1,4-dioxane. Heat the reactor to 80-90℃ and stir under reflux for about 12 hours. The reaction formula is: After the reaction was completed, the reaction solution was cooled to room temperature, and water and ethyl acetate were added in a ratio of approximately 1:
1. Extraction was performed 2-3 times. All organic phases were combined and washed once with saturated sodium chloride solution. The organic phases were then dried with anhydrous sodium sulfate, filtered, and the solvent was removed by rotary evaporation. The intermediate 1 was then purified by silica gel column chromatography using a mixture of petroleum ether and ethyl acetate as the eluent. Step 2: Add intermediate 1 obtained in Step 1 and solvent dichloromethane to the reaction vessel. Slowly add a mixture of nitric acid and sulfuric acid dropwise at a temperature of 0-5℃ to carry out the reaction. The reaction equation is as follows: ； After the reaction, the reaction mixture was quenched in ice water, then extracted with dichloromethane, and purified by recrystallization with a mixture of ethanol and water to obtain intermediate 2. Step 3: Place intermediate 2 obtained in Step 2 into a reaction vessel, add solvent ethanol and catalyst Pd / C, and react by introducing H2 at 2 atmospheres and room temperature. The reaction equation is as follows: After the reaction was completed, the solid catalyst was removed by filtration, and the product was purified by recrystallization to obtain intermediate 3. Step 4: Add intermediate 3 obtained in Step 3 to a round-bottom flask and place it in an ice-water bath. Add solvent DCM and a small amount of sodium hydroxide solution. Slowly add acryloyl chloride dropwise, maintaining the temperature at 0-5℃. The reaction equation is: After the reaction was completed, the temperature was raised to room temperature and stirring was continued for 2 hours. A small amount of sodium hydroxide solution was added to react with the remaining acryloyl chloride. The mixture was filtered through a separatory funnel, and the organic phase was washed with saturated sodium chloride. After adding anhydrous sodium sulfate, the mixture was filtered and then evaporated at low temperature. After recrystallization and purification, intermediate 4 was obtained. Step 5: Dissolve intermediate 4 obtained in step 4 in anhydrous toluene, add it to a round-bottom flask, and slowly add phosphorus trichloride dropwise to the reaction solution. Heat to 110℃ and react for 8 hours. The reaction formula is: After the reaction, the reaction solution was slowly cooled to 0°C, and then slowly poured into a saturated sodium bicarbonate solution with vigorous stirring. The aqueous phase was extracted three times with ethyl acetate, and the combined organic phases were washed with saturated sodium chloride. The organic phase was dried with anhydrous sodium sulfate, filtered, and rotary evaporated to obtain the crude product. The crude product was then purified by silica gel column chromatography (using a mixture of petroleum ether and ethyl acetate as the eluent) to obtain intermediate 5. Step Six: Dissolve intermediate 5 obtained in Step Five in dichloromethane, cool to 0°C in an ice-water bath, and slowly add a solution of acetyl nitrate cooled to 0°C dropwise into the reaction mixture through a dropping funnel while stirring vigorously. Maintain the temperature at 0°C during the addition process. After the addition is complete, continue stirring at 0°C for 3 hours. The reaction equation is: After the reaction was completed, the reaction solution was poured into ice water, and the aqueous phase was extracted three times with dichloromethane. The organic phases were combined and washed with ice water, saturated sodium bicarbonate solution, and saturated sodium chloride solution. The organic phase was dried with anhydrous magnesium sulfate and then filtered and rotary evaporated to obtain intermediate 6. Step 7: The intermediate 6 obtained in Step 6 is reacted in a flask with excess stannous chloride under reflux in an ethanol / hydrochloric acid solution. The reaction equation is as follows: After the reaction was completed, the solid catalyst was removed by filtration and purified by recrystallization to obtain intermediate 7; Step 8: Dissolve intermediate 7 obtained in Step 7 in dilute hydrochloric acid (HCl) and cool in an ice bath to 0-5°C. While stirring vigorously, slowly add an aqueous solution of NaNO2. After the reaction is complete, add the resulting diazonium salt solution to a sodium sulfite solution while cooling, and then heat appropriately to ensure complete reaction. The reaction equation is: After drying and purification, the obtained product yielded intermediate 8; Step 9: Dissolve intermediate 8 obtained in step 8 in dichloromethane, pour the solution into a round-bottom flask, add a small amount of triethylamine, and slowly add acryloyl chloride dropwise at 0°C. After the addition is complete, react for 1-2 hours, then gradually raise the temperature to room temperature and continue stirring for 12 hours. The reaction equation is: After the reaction was completed, the reaction solution was poured into a saturated ammonium chloride solution and extracted three times with DCM. The organic phases were combined and washed with saturated sodium bicarbonate solution and sodium chloride solution. Then, the solution was dried with anhydrous sodium sulfate and the solvent was removed by rotary evaporation to obtain the functional monomer S.
3. The application of the salt-resistant functional monomer suitable for high-salinity oilfield environments according to claim 1, characterized in that: The functional monomer S is used to synthesize a salt-resistant polymer suitable for high-salt oilfield environments. The components and weight parts of the salt-resistant polymer suitable for high-salt oilfield environments are as follows: 210-260 parts of acrylamide; 15-30 parts of AMPS; 6-15 parts of AEO-9; 20-50 parts of functional monomer S; 10-20 parts of urea; 0.2-0.3 parts of initiator #1; 0.05-0.15 parts of initiator #2; 0.05-0.15 parts of initiator #3; 0.1-0.3 parts of initiator #4; and water to a total of 1000 parts.
4. The application of the salt-resistant functional monomer suitable for high-salinity oilfield environments according to claim 3, characterized in that: The initiator #1 is one or more of azobisisobutyronitrile, azobisisoheptanenitrile, or azobisisobutylamidine hydrochloride.
5. The application of the salt-resistant functional monomer suitable for high-salinity oilfield environments according to claim 3, characterized in that: The #2 initiator is one or more of sodium formate, sodium acetate, or isopropanol.
6. The application of the salt-resistant functional monomer suitable for high-salinity oilfield environments according to claim 3, characterized in that: The #3 initiator is one or more of ammonium persulfate, potassium persulfate, or sodium persulfate.
7. The application of the salt-resistant functional monomer suitable for high-salinity oilfield environments according to claim 3, characterized in that: The #4 initiator is one or more of sodium bisulfite, sodium thiosulfate, or triethanolamine.
8. The application of the salt-resistant functional monomer suitable for high-salinity oilfield environments according to any one of claims 3-7, characterized in that: The method for preparing the salt-resistant polymer includes the following steps: (1) Mix the functional monomer S and AEO-9 and set aside for later use; (2) Dissolve AMPS in ice water and then neutralize with sodium carbonate; (3) After mixing acrylamide with the monomer prepared in steps (1) and (2) with urea and water, adjust the pH value with 30% sodium hydroxide solution until the pH value is 7.0-7.5; (4) After adjusting the temperature of the solution prepared in step (3) to 4℃-6℃, transfer the solution to an insulated reactor and then introduce nitrogen gas for 30 minutes to remove oxygen. After deoxygenation, add initiator 1 and initiator 2 to the reactor, add initiator 3 after 5 minutes, and add initiator 4 after another 5 minutes. Stop introducing nitrogen gas after the system in the reactor starts to heat up. After the reaction is completed and the temperature stops rising, continue to mature for 4 hours to obtain polymer colloid. (5) The polymer colloid obtained in step (4) is crushed, solid sodium hydroxide is added, and after being fully mixed, it is hydrolyzed at 75°C for 6 hours and then dried at 60°C for 12 hours. After crushing and sieving, particles with a particle size of 400μm-800μm are obtained. These particles are the finished product of salt-resistant polymer suitable for high-salt oilfield environments.