Synthesis method of polyacrylamide for oil displacement

Abstract

The invention belongs to the technical field of polyacrylamide synthesis, and particularly relates to a synthesis method of polyacrylamide for oil displacement. The synthesis method of the polyacrylamide for oil displacement, disclosed by the invention, comprises the following steps: (1) pre-emulsifying 1H, 1H, 2H, 2H-perfluorooctyl acrylate; (2) preparing a water phase; (3) preparing an organic phase solution; (4) polymerization reaction; and (5) post-treatment. According to the synthesis method of polyacrylamide for oil displacement, acrylamide is used as a main monomer, 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt, 1H, 1H, 2H, 2H-octyl perfluoroacrylate and 1-methacryloyloxy adamantane are used as functional monomers, a potassium persulfate solution-sodium hydrogen sulfite solution is used as an initiator system, and the polyacrylamide for oil displacement is synthesized through a one-step method. The polyacrylamide for oil displacement, which is prepared by adopting a water-phase micelle polymerization method, has temperature resistance, salt resistance and shear resistance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of polyacrylamide synthesis, and particularly relates to a synthesis method of polyacrylamide for oil displacement. BACKGROUND

[0002] Polymer flooding is a main technical method for tertiary oil recovery, has clear oil displacement mechanism, relatively simple process, and mature technology, and is an effective technical measure for improving recovery efficiency. The oil displacement mechanism of the polymer is mainly to use the viscosity of the water-soluble polyacrylamide molecular chain to improve the mobility ratio of the displacement fluid, improve the displacement efficiency and swept volume, and thus achieve the purpose of improving the recovery efficiency.

[0003] Since the tertiary oil recovery period is long and the deep oil well temperature is high, the polymer for the tertiary oil recovery must have good viscosity increasing, temperature resistance and salt resistance. In addition, the high-valence metal ions (such as Ca 2+ , Mg 2+ ) in the oil reservoir easily cause phase separation of the PAM, thereby reducing the viscosity increasing effect of the PAM; in addition, the PAM is prone to molecular chain rupture under the action of shearing, thereby causing the viscosity of the solution to be greatly reduced, and thus it is difficult to meet the needs of the deep second and third oil reservoirs under high temperature and high salinity.

[0004] CN104448129B discloses a high-temperature-resistant hydrolytic copolymer for oil fields, a synthesis method and application thereof. The application better solves the problem of poor hydrolytic stability of the polyacrylamide under high temperature and high salinity in the prior art by using the high-temperature-resistant hydrolytic copolymer. However, the molecular structure of the application does not have a surfactant group, only has the function of ordinary polymer oil displacement, cannot reduce the oil-water interfacial tension, cannot emulsify and reduce viscosity, and affects the recovery efficiency.

[0005] At present, the polyacrylamide oil displacement technology has become one of the main measures for improving the recovery efficiency of crude oil. However, the ordinary polyacrylamide has poor salt resistance, temperature resistance and shearing resistance, is not suitable for high-salt oil reservoirs, and after being injected, the viscosity is greatly reduced and the oil displacement effect is poor. Therefore, it is necessary to explore a new synthesis method of polyacrylamide for oil displacement. SUMMARY

[0006] The purpose of the application is to provide a synthesis method of polyacrylamide for oil displacement. The polyacrylamide synthesized by the method has temperature resistance, salt resistance and shearing resistance.

[0007] The synthesis method of the polyacrylamide for oil displacement comprises the following steps: (1) Pre-emulsification of 1H, 1H, 2H, 2H-octyl perfluoropropenoate ① 3-allyloxy-2-hydroxy-1-propane sulfonic acid sodium salt and deionized water are added to a reaction kettle and stirred for reaction; ② Add 1H,1H,2H,2H-octyl perfluoroacrylate dropwise to the above reaction system and continue stirring to prepare a micelle solution; (2) Preparation of aqueous phase Acrylamide was added to the micelle solution prepared in step (1) ② and stirred until completely dissolved. Then sodium hydroxide was added to adjust the pH of the system to 6.5. Nitrogen gas was purged into the reaction system for 17-20 min. Finally, 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid was added and stirred until completely dissolved to prepare an aqueous phase. (3) Preparation of organic phase solution 1-Methacryloxyadamantane was dissolved in n-hexane, heated to 38-40℃ and stirred to dissolve, thus preparing an organic phase solution; (4) Polymerization reaction Add the aqueous phase prepared in step (2) into the reactor, control the reaction temperature of the reactor to 43-45℃, and simultaneously add the organic phase solution and the potassium persulfate solution-sodium bisulfite solution initiator system under stirring to carry out the polymerization reaction. (5) Post-processing After the reaction was complete, the temperature was lowered to 25°C, and then hexane was removed by rotary evaporation under reduced pressure. Finally, the mixture was filtered and spray-dried to prepare polyacrylamide for oil displacement. In step (5), the polyacrylamide for oil displacement is prepared with the following molar ratio of acrylamide, sodium 3-allyloxy-2-hydroxy-1-propanesulfonate, 1H,1H,2H,2H-octyl perfluoroacrylate, and 1-methacryloyloxyadamantane: 72-74 : 24-26 : 0.15-0.25 : 0.6-0.8.

[0008] In step (1)①, the mass ratio of sodium 3-allyloxy-2-hydroxy-1-propanesulfonate to deionized water is 0.7-0.8:1, the stirring temperature is 40-45℃, the stirring speed is 300r / min, and the stirring time is 15-17min.

[0009] In step (1) ②, the dropping rate of 1H,1H,2H,2H-octyl perfluoroacrylate is 0.10 g / min, the stirring temperature is 40-45℃, the stirring speed is 300 r / min, and the stirring time is 20-23 min.

[0010] In step (1), sodium 3-allyloxy-2-hydroxy-1-propanesulfonate is an aqueous solution with a mass concentration of 40%, manufactured by Shanghai Jizhi Biochemical Technology Co., Ltd.

[0011] The temperature for stirring reaction in step (2) is 40-45℃, the stirring speed is 300r / min, and the stirring time is 8-10min.

[0012] The temperature for stirring reaction in step (2) is 40-45℃, the stirring speed is 300r / min, and the stirring time is 8-10min.

[0013] The temperature for stirring reaction in step (2) is 40-45℃, the stirring speed is 300r / min, and the stirring time is 8-10min.

[0014] The temperature for stirring reaction in step (2) is 40-45℃, the stirring speed is 300r / min, and the stirring time is 8-10min.

[0015] The mass-volume ratio of 1-methylacryloyloxyadamantane to n-hexane in step (3) is 2:5, g / mL.

[0016] The stirring speed in step (3) is 300r / min, and the stirring time is 3-5min.

[0017] The stirring speed in step (4) is controlled to be 250r / min.

[0018] The organic phase solution, the potassium persulfate solution and the sodium bisulfite solution in the initiator system in step (4) are added at a uniform speed, and the addition is completed in 10h.

[0019] The potassium persulfate solution in step (4) is prepared by uniformly mixing potassium persulfate and deionized water to obtain a potassium persulfate solution with a mass concentration of 2.0%, and then deoxygenated by nitrogen for 5min.

[0020] The sodium bisulfite solution in step (4) is prepared by uniformly mixing sodium bisulfite and deionized water to obtain a sodium bisulfite solution with a mass concentration of 1.0%, and then deoxygenated by nitrogen for 5min.

[0021] In the initiator system in step (4), the volume ratio of the potassium persulfate solution to the sodium bisulfite solution is 1:1.

[0022] The polymerization reaction in step (4) is first carried out at 43-45℃ for 1h, and then at 53-55℃ for 1h.

[0023] The molar amount of the potassium persulfate in the potassium persulfate solution in step (4) accounts for 0.05% of the sum of the molar amounts of acrylamide, 1H, 1H, 2H, 2H-perfluorooctyl acrylate, 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt and 1-methyl methacryloyloxyadamantane.

[0024] The temperature of the reduced pressure rotary evaporation in step (5) is 40 DEG C, the pressure is -0.09 MPa, and the time of the reduced pressure rotary evaporation is 30 min.

[0025] The filtration in step (5) is performed by using a 0.2-micron polyether sulfone folded filter element.

[0026] The inlet temperature of the spray drying in step (5) is 160 DEG C, and the outlet temperature of the spray drying is 75 DEG C.

[0027] Compared with the prior art, the present application has the following beneficial effects: (1) The synthesis method of the oil displacement polyacrylamide disclosed by the present application uses acrylamide as a main monomer, 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt, 1H, 1H, 2H, 2H-perfluorooctyl acrylate and 1-methyl methacryloyloxyadamantane as functional monomers, uses a potassium persulfate solution-sodium bisulfite solution as an initiator system, and adopts a water phase micellar polymerization method to prepare the oil displacement polyacrylamide, which has temperature resistance, salt resistance and shear resistance.

[0028] (2) The synthesis method of the oil displacement polyacrylamide disclosed by the present application uses acrylamide as a main monomer, 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt as a salt-resistant monomer, 1H, 1H, 2H, 2H-perfluorooctyl acrylate as a shear-resistant monomer, and 1-methyl methacryloyloxyadamantane as a temperature-resistant monomer, and the four kinds of monomers impart excellent performance to the oil displacement polyacrylamide through a polymerization reaction. The side groups of the molecular chain of 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt are "hydroxyl-ether-sodium sulfonate" structures, the ether bond and the hydroxyl group are both hydrophilic groups, can form a hydration layer with water molecules, and the hydration layer can shield Ca 2+ and Mg 2 +The sulfonic acid group in the molecular structure of the 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt can still be 100% ionized under high salinity, so that the molecular chain remains stretched, and thus the prepared polyacrylamide still has high viscosity under high salt conditions. The C-F bond in the molecular structure of the 1H, 1H, 2H, 2H-octyl perfluoroacrylate has high bond energy and strong chemical stability, so that the prepared polyacrylamide has high shear resistance. Since the 1H, 1H, 2H, 2H-octyl perfluoroacrylate has low surface energy, it can reduce the oil-water interfacial tension. The 1-methyl methacryloyloxy adamantane has a highly symmetrical cage-shaped rigid structure and large steric hindrance. At high temperatures, the rigid group limits the rotation, curling and other thermal motion of the molecular chain, reduces the thermal relaxation of the chain segment, thereby maintaining the morphology of the molecular chain and improving the high-temperature resistance of the prepared polyacrylamide. In addition, the 1-methyl methacryloyloxy adamantane and the 1H, 1H, 2H, 2H-octyl perfluoroacrylate have a synergistic effect, so that the polyacrylamide still has a high viscosity retention rate after high-speed shearing. In summary, the 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt is used to ensure the oil carrying capacity of the prepared polyacrylamide under high salinity, the 1H, 1H, 2H, 2H-octyl perfluoroacrylate is used to improve the shear resistance of the prepared polyacrylamide and reduce the oil-water interfacial tension, so that the polymer molecular chain does not break during the seepage process, and the crude oil is easily stripped. The 1-methyl methacryloyloxy adamantane fills the gap in temperature resistance, and has a synergistic effect with the 1H, 1H, 2H, 2H-octyl perfluoroacrylate to further improve the shear resistance and viscosity stability of the prepared polyacrylamide. Thus, the raw materials have a synergistic effect, so that the prepared polyacrylamide has excellent performance.

[0029] (3) The synthesis method of the oil displacement polyacrylamide disclosed in the application uses 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt to form micelles to solubilize 1H, 1H, 2H, 2H-octyl perfluoroacrylate, without the need for additional water-in-oil emulsifiers. Since there is no oil phase continuous phase, the traditional reverse-phase emulsion polymerization process of demulsification and oil removal is directly omitted. The 1-methyl methacryloyloxy adamantane and the initiator system are added synchronously, and the dropping is completed within 10 hours. The dropping rate matches the polymerization reaction kinetics, avoids local enrichment, and ensures that the side chain units are statistically uniform along the main chain. The solvent is n-hexane, which is easy to remove. The reaction conditions are mild and easy to realize industrial production. The various steps have a synergistic effect, and the prepared polyacrylamide has stable performance. DETAILED DESCRIPTION

[0030] Example 1 The synthesis method of the oil displacement polyacrylamide disclosed in the application comprises the following steps: (1) Pre-emulsification of 1H, 1H, 2H, 2H-octyl perfluoroacrylate ①Into the reaction kettle, 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt and deionized water were added and stirred to react; ②1H, 1H, 2H, 2H-octyl perfluoropropenoate was added dropwise into the above reaction system to continue stirring to react, thereby preparing a micellar solution; (2) Preparation of an aqueous phase Acrylamide was added into the micellar solution prepared in step (1) ② and stirred to dissolve completely, then sodium hydroxide was added to adjust the pH value of the system to 6.5, nitrogen was blown into the reaction system for 19 min, and finally 2-[dodecylthio (thiocarbonyl) thio]-2-methylpropionic acid was added and stirred to dissolve completely, thereby preparing an aqueous phase; (3) Preparation of an organic phase solution 1-methylacryloyloxyadamantane was dissolved in n-hexane by heating to 39℃ and stirring to dissolve, thereby preparing an organic phase solution; (4) Polymerization reaction The aqueous phase prepared in step (2) was added into a reaction kettle, the reaction temperature of the reaction kettle was controlled at 44℃, and the organic phase solution and the potassium persulfate-sodium bisulfite initiator system were added into the reaction kettle under stirring to carry out a polymerization reaction; (5) Post-treatment After the reaction was completed, the temperature was lowered to 25℃, then n-hexane was removed by rotary evaporation under reduced pressure, and finally filtration and spray drying were carried out, thereby preparing a polyacrylamide for oil displacement.

[0031] In step (1) ①, the mass ratio of 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt to deionized water was 0.75:1, the stirring reaction temperature was 43℃, the stirring reaction speed was 300 r / min, and the stirring reaction time was 16 min.

[0032] In step (1) ②, the dropping speed of 1H, 1H, 2H, 2H-octyl perfluoropropenoate was 0.10 g / min, the stirring reaction temperature was 43℃, the stirring reaction speed was 300 r / min, and the stirring reaction time was 22 min.

[0033] In step (1), 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt was a 40% mass concentration aqueous solution, and the manufacturer was Shanghai Jizhisheng Biochemical Technology Co., Ltd.

[0034] In step (2), the stirring reaction temperature of acrylamide was 43℃, the stirring reaction speed was 300 r / min, and the stirring reaction time was 9 min.

[0035] The temperature of the stirring reaction in step (2) is 43℃, the stirring speed is 300r / min, and the stirring time is 4min.

[0036] The 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid is added in step (2) as a chain transfer agent.

[0037] The molar amount of the 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid in step (2) accounts for 0.08% of the sum of the molar amounts of the acrylamide, the 1H,1H,2H,2H-perfluorooctyl propenoate, the 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt, and the 1-methylacryloyloxyadamantane.

[0038] The mass-volume ratio of the 1-methylacryloyloxyadamantane to n-hexane in step (3) is 2:5, in g / mL.

[0039] The stirring speed in step (3) is 300r / min, and the stirring time is 4min.

[0040] The stirring speed in the polymerization reaction in step (4) is controlled to be 250r / min.

[0041] The potassium persulfate solution in the initiator system, the organic phase solution, and the sodium bisulfite solution are simultaneously and uniformly added in step (4), and the addition is completed in 10h.

[0042] The potassium persulfate solution in step (4) is prepared by uniformly mixing potassium persulfate and deionized water to obtain a potassium persulfate solution with a mass concentration of 2.0%, and then deoxygenating for 5min by nitrogen.

[0043] The sodium bisulfite solution in step (4) is prepared by uniformly mixing sodium bisulfite and deionized water to obtain a sodium bisulfite solution with a mass concentration of 1.0%, and then deoxygenating for 5min by nitrogen.

[0044] The volume ratio of the potassium persulfate solution to the sodium bisulfite solution in the initiator system in step (4) is 1:1.

[0045] The polymerization reaction in step (4) is first carried out at 44℃ for 1h, and then at 54℃ for 1h.

[0046] The molar amount of the potassium persulfate in the potassium persulfate solution in step (4) accounts for 0.05% of the sum of the molar amounts of the acrylamide, the 1H,1H,2H,2H-perfluorooctyl propenoate, the 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt, and the 1-methylacryloyloxyadamantane.

[0047] The temperature of the reduced pressure rotary evaporation in step (5) is 40℃, the pressure is -0.09 MPa, and the time of the reduced pressure rotary evaporation is 30 min.

[0048] The filtration in step (5) is performed by using a 0.2-micron polyether sulfone folded filter.

[0049] The inlet temperature of the spray drying in step (5) is 160℃, and the outlet temperature of the spray drying is 75℃.

[0050] The polyacrylamide for oil displacement prepared in step (5) uses the polymeric monomers in the following amount relationship: the molar ratio of acrylamide, 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt, 1H, 1H, 2H, 2H-octyl perfluoropropenoate, and 1-methylacryloyloxyadamantane is 73:25:0.20:0.7.

[0051] Example 2 The synthesis method of the polyacrylamide for oil displacement in this example 2 is composed of the following steps: (1) Pre-emulsification of 1H, 1H, 2H, 2H-octyl perfluoropropenoate ① 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt and deionized water are added to a reaction kettle for stirring reaction; ② 1H, 1H, 2H, 2H-octyl perfluoropropenoate is added dropwise to the above reaction system for continued stirring reaction to prepare a micellar solution; (2) Preparation of an aqueous phase Acrylamide is added to the micellar solution prepared in step (1) ② for stirring until completely dissolved, then sodium hydroxide is added to adjust the pH value of the system to 6.5, nitrogen gas is passed into the reaction system for 20 min, and finally 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropanoic acid is added for stirring until completely dissolved to prepare an aqueous phase; (3) Preparation of an organic phase solution 1-methylacryloyloxyadamantane is dissolved in n-hexane by heating to 38℃ for stirring and dissolving to prepare an organic phase solution; (4) Polymerization reaction The aqueous phase prepared in step (2) is added to a reaction kettle, the reaction temperature of the reaction kettle is controlled at 45℃, and the organic phase solution and the potassium persulfate solution-sodium bisulfite solution initiator system are simultaneously added under stirring for polymerization reaction; (5) Post-treatment After the reaction is completed, the temperature is lowered to 25℃, then n-hexane is removed by reduced pressure rotary evaporation, and finally filtration and spray drying are performed to prepare the polyacrylamide for oil displacement.

[0052] The mass ratio of 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt to deionized water in step (1) ① is 0.7:1, the stirring reaction temperature is 45°C, the stirring reaction speed is 300 r / min, and the stirring reaction time is 15 min.

[0053] The dropping speed of 1H,1H,2H,2H-octyl perfluoropropenoate in step (1) ② is 0.10 g / min, the stirring reaction temperature is 45°C, the stirring reaction speed is 300 r / min, and the stirring reaction time is 20 min.

[0054] The 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt in step (1) is an aqueous solution with a mass concentration of 40%, and the production manufacturer is Shanghai Jizisheng Chemical Technology Co., Ltd.

[0055] The stirring reaction temperature of adding acrylamide in step (2) is 45°C, the stirring reaction speed is 300 r / min, and the stirring reaction time is 8 min.

[0056] The stirring reaction temperature of adding 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid in step (2) is 45°C, the stirring reaction speed is 300 r / min, and the stirring reaction time is 3 min.

[0057] 2-[Dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid is added as a chain transfer agent in step (2).

[0058] The molar amount of 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid accounts for 0.08% of the sum of the molar amounts of acrylamide, 1H,1H,2H,2H-octyl perfluoropropenoate, 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt, and 1-methylacryloyloxyadamantane in step (2).

[0059] The mass-volume ratio of 1-methylacryloyloxyadamantane to n-hexane in step (3) is 2:5, in g / mL.

[0060] The stirring speed in step (3) is 300 r / min, and the stirring time is 5 min.

[0061] The stirring speed is controlled to be 250 r / min in the polymerization reaction in step (4).

[0062] The potassium persulfate solution in the initiator system and the sodium bisulfite solution are added at a constant speed at the same time as the organic phase solution in step (4), and the addition is completed in 10 h.

[0063] The potassium persulfate solution in step (4) is prepared by uniformly mixing potassium persulfate and deionized water to obtain a potassium persulfate solution with a mass concentration of 2.0%, and then deoxygenating for 5 min by nitrogen.

[0064] The sodium bisulfite solution in step (4) is prepared by mixing sodium bisulfite and deionized water uniformly to obtain a sodium bisulfite solution with a mass concentration of 1.0%, and then deoxygenating for 5 min by nitrogen.

[0065] In the initiation system in step (4), the volume ratio of the potassium persulfate solution to the sodium bisulfite solution is 1:1.

[0066] The polymerization reaction in step (4) is first carried out at 45℃ for 1 h, and then at 55℃ for 1 h.

[0067] In the potassium persulfate solution in step (4), the molar amount of potassium persulfate accounts for 0.05% of the sum of the molar amounts of acrylamide, 1H, 1H, 2H, 2H-octyl perfluoroacrylate, 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt and 1-methyl acryloyloxy adamantane.

[0068] In step (5), the temperature of the reduced pressure rotary evaporation is 40℃, the pressure is -0.09 MPa, and the time of the reduced pressure rotary evaporation is 30 min.

[0069] In step (5), the filtration is carried out by using a 0.2-micron polyether sulfone folded filter element.

[0070] In step (5), the inlet temperature of the spray drying is 160℃, and the outlet temperature of the spray drying is 75℃.

[0071] The oil displacement polyacrylamide prepared in step (5) adopts the following polymerization monomer usage amount relationship: the molar ratio among acrylamide, 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt, 1H, 1H, 2H, 2H-octyl perfluoroacrylate and 1-methyl acryloyloxy adamantane is 74:24:0.15:0.8.

[0072] Example 3 The synthesis method of the oil displacement polyacrylamide in this example 3 is composed of the following steps: (1) Pre-emulsification of 1H, 1H, 2H, 2H-octyl perfluoroacrylate ① 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt and deionized water are added to a reaction kettle for stirring reaction; ② 1H, 1H, 2H, 2H-octyl perfluoroacrylate is added dropwise to the above reaction system for continuous stirring reaction to prepare a micellar solution; (2) Preparation of aqueous phase Acrylamide was added to the micelle solution prepared in step (1) ② and stirred until completely dissolved. Then sodium hydroxide was added to adjust the pH of the system to 6.5. Nitrogen gas was purged into the reaction system for 17 min. Finally, 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid was added and stirred until completely dissolved to prepare an aqueous phase. (3) Preparation of organic phase solution 1-Methacryloxyadamantane was dissolved in n-hexane and heated to 40°C with stirring to prepare an organic phase solution. (4) Polymerization reaction Add the aqueous phase prepared in step (2) into the reactor, control the reaction temperature of the reactor at 43°C, and simultaneously add the organic phase solution and the potassium persulfate solution-sodium bisulfite solution initiator system under stirring to carry out the polymerization reaction. (5) Post-processing After the reaction was complete, the temperature was lowered to 25°C, and then hexane was removed by rotary evaporation under reduced pressure. Finally, the mixture was filtered and spray-dried to prepare polyacrylamide for oil displacement.

[0073] In step (1)①, the mass ratio of sodium 3-allyloxy-2-hydroxy-1-propanesulfonate to deionized water is 0.8:1, the stirring temperature is 40℃, the stirring speed is 300r / min, and the stirring time is 17min.

[0074] In step (1) ②, the dropping rate of 1H,1H,2H,2H-octyl perfluoroacrylate is 0.10 g / min, the stirring temperature is 40℃, the stirring speed is 300 r / min, and the stirring time is 23 min.

[0075] In step (1), sodium 3-allyloxy-2-hydroxy-1-propanesulfonate is an aqueous solution with a mass concentration of 40%, manufactured by Shanghai Jizhi Biochemical Technology Co., Ltd.

[0076] In step (2), the temperature for adding acrylamide and stirring is 40°C, the stirring speed is 300 r / min, and the stirring time is 10 min.

[0077] In step (2), 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid was added and stirred at a temperature of 40°C, a stirring speed of 300 r / min, and a stirring time of 5 min.

[0078] In step (2), 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid is added as a chain transfer agent.

[0079] The molar amount of 2-[dodecylsulfanyl(thiocarbonyl)thio]-2-methylpropanoic acid in step (2) accounts for 0.08% of the sum of the molar amounts of acrylamide, 1H, 1H, 2H, 2H-perfluorooctyl propenoate, 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt, and 1-methacryloyloxyadamantane.

[0080] The mass-volume ratio of 1-methacryloyloxyadamantane to n-hexane in step (3) is 2:5, and the unit is g / mL.

[0081] The stirring speed in step (3) is 300 r / min, and the stirring time is 3 min.

[0082] The stirring speed in the polymerization reaction in step (4) is controlled to be 250 r / min.

[0083] In step (4), the organic phase solution, the potassium persulfate solution in the initiator system, and the sodium bisulfite solution are added at a constant speed at the same time, and the addition is completed in 10 h.

[0084] In step (4), the potassium persulfate solution is prepared by uniformly mixing potassium persulfate and deionized water to obtain a potassium persulfate solution with a mass concentration of 2.0%, and then deoxygenated by nitrogen for 5 min.

[0085] In step (4), the sodium bisulfite solution is prepared by uniformly mixing sodium bisulfite and deionized water to obtain a sodium bisulfite solution with a mass concentration of 1.0%, and then deoxygenated by nitrogen for 5 min.

[0086] In step (4), the volume ratio of the potassium persulfate solution to the sodium bisulfite solution in the initiator system is 1:1.

[0087] In step (4), the polymerization reaction is first carried out at 43°C for 1 h, and then carried out at 53°C for 1 h.

[0088] The molar amount of potassium persulfate in the potassium persulfate solution in step (4) accounts for 0.05% of the sum of the molar amounts of acrylamide, 1H, 1H, 2H, 2H-perfluorooctyl propenoate, 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt, and 1-methacryloyloxyadamantane.

[0089] In step (5), the temperature of the rotary evaporation under reduced pressure is 40°C, the pressure is -0.09 MPa, and the time of the rotary evaporation under reduced pressure is 30 min.

[0090] In step (5), the filtration is carried out using a 0.2-micron polyether sulfone folded filter.

[0091] In step (5), the inlet temperature of the spray drying is 160°C, and the outlet temperature of the spray drying is 75°C.

[0092] The oil displacement polyacrylamide prepared in step (5) has a molar ratio of 72:26:0.25:0.6 for acrylamide, 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt, 1H, 1H, 2H, 2H-octyl perfluoropropenoate and 1-adamantyl methacrylate.

[0093] Comparative Example 1 The oil displacement polyacrylamide prepared in step (5) has a molar ratio of 72:26:0.25:0.6 for acrylamide, 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt, 1H, 1H, 2H, 2H-octyl perfluoropropenoate and 1-adamantyl methacrylate.

[0094] Comparative Example 2 The oil displacement polyacrylamide prepared in step (5) has a molar ratio of 72:26:0.25:0.6 for acrylamide, 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt, 1H, 1H, 2H, 2H-octyl perfluoropropenoate and 1-adamantyl methacrylate.

[0095] Comparative Example 3 The oil displacement polyacrylamide prepared in step (5) has a molar ratio of 72:26:0.25:0.6 for acrylamide, 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt, 1H, 1H, 2H, 2H-octyl perfluoropropenoate and 1-adamantyl methacrylate.

[0096] The oil displacement polyacrylamide prepared in step (5) has a molar ratio of 72:26:0.25:0.6 for acrylamide, 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt, 1H, 1H, 2H, 2H-octyl perfluoropropenoate and 1-adamantyl methacrylate.

[0097] The oil displacement polyacrylamides prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests, wherein the shear viscosity retention rate was determined according to Section 7.10 of the Enterprise Standard Q / SH CG0159-2025 of China Petroleum and Chemical Corporation, the brine used was Brine IV, and the sample was prepared according to Type V polymer; the thermal stability was tested according to Section 7.13 of the Enterprise Standard Q / SH CG0159-2025, wherein the brine used was Brine IV, the sample was prepared according to Type V polymer, the thermal aging temperature was 115℃, and the thermal aging time was 30 days and 90 days, respectively; and the results are shown in Table 1 below: Table 1 Performance test results of the oil displacement polyacrylamides of Examples 1-3 and Comparative Examples 1-3

[0098] As can be seen from Table 1, the viscosity retention rate of the oil displacement polyacrylamides prepared in Examples 1-3 is significantly higher than that of Comparative Examples 1-3, and both the shear resistance and the thermal aging performance of the oil displacement polyacrylamides prepared in Examples 1-3 are significantly better than those of Comparative Examples 1-3. The oil displacement polyacrylamide prepared in Comparative Example 1 lacks 1H, 1H, 2H, 2H-octyl perfluoroacrylate in the raw materials, the oil displacement polyacrylamide prepared in Comparative Example 2 lacks 1-methylacryloyloxyadamantane in the raw materials, and the oil displacement polyacrylamide prepared in Comparative Example 3 lacks 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt in the raw materials, all of which result in a significant decrease in the shear resistance and the aging resistance of the prepared oil displacement polyacrylamides. Therefore, when preparing polyacrylamide, the three functional monomers, 1-methylacryloyloxyadamantane, 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt, and 1H, 1H, 2H, 2H-octyl perfluoroacrylate, are used in combination with acrylamide to enable the prepared oil displacement polyacrylamide to have good temperature resistance, salt resistance, and shear resistance.

[0099] The above description is only a preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed with the preferred embodiment as above, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes, without departing from the technical solution of the present application. Any modification, change, and modification of the above embodiments according to the technical essence of the present application are still within the scope of the technical solution of the present application.

Claims

1. A method for synthesizing polyacrylamide for oil displacement, characterized in that: It consists of the following steps: (1) Pre-emulsification of 1H,1H,2H,2H-octyl perfluoroacrylate ① Add sodium 3-allyloxy-2-hydroxy-1-propanesulfonate and deionized water to the reaction vessel and stir to react; ② Add 1H,1H,2H,2H-octyl perfluoroacrylate dropwise to the above reaction system and continue stirring to prepare a micelle solution; (2) Preparation of aqueous phase Acrylamide was added to the micelle solution prepared in step (1) ② and stirred until completely dissolved. Then sodium hydroxide was added to adjust the pH of the system to 6.

5. Nitrogen gas was purged into the reaction system for 17-20 min. Finally, 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid was added and stirred until completely dissolved to prepare an aqueous phase. (3) Preparation of organic phase solution 1-Methacryloxyadamantane was dissolved in n-hexane, heated to 38-40℃ and stirred to dissolve, thus preparing an organic phase solution; (4) Polymerization reaction Add the aqueous phase prepared in step (2) into the reactor, control the reaction temperature of the reactor to 43-45℃, and simultaneously add the organic phase solution and the potassium persulfate solution-sodium bisulfite solution initiator system under stirring to carry out the polymerization reaction. (5) Post-processing After the reaction was completed, the temperature was lowered to 25°C, and then hexane was removed by rotary evaporation under reduced pressure. Finally, the mixture was filtered and spray-dried to prepare polyacrylamide for oil displacement. In step (5), the polyacrylamide for oil displacement is prepared with the following molar ratio of acrylamide, sodium 3-allyloxy-2-hydroxy-1-propanesulfonate, 1H,1H,2H,2H-octyl perfluoroacrylate, and 1-methacryloyloxyadamantane: 72-74 : 24-26 : 0.15-0.25 : 0.6-0.

8.

2. The method for synthesizing polyacrylamide for oil displacement according to claim 1, characterized in that: In step (1)①, the mass ratio of sodium 3-allyloxy-2-hydroxy-1-propanesulfonate to deionized water is 0.7-0.8:1, the stirring temperature is 40-45℃, the stirring speed is 300r / min, and the stirring time is 15-17min. In step (1) ②, the dropping rate of 1H,1H,2H,2H-octyl perfluoroacrylate is 0.10 g / min, the stirring temperature is 40-45℃, the stirring speed is 300 r / min, and the stirring time is 20-23 min; In step (1), sodium 3-allyloxy-2-hydroxy-1-propanesulfonate is an aqueous solution with a mass concentration of 40%.

3. The method for synthesizing polyacrylamide for oil displacement according to claim 1, characterized in that: In step (2), the temperature for adding acrylamide and stirring the reaction is 40-45℃, the stirring speed is 300r / min, and the stirring time is 8-10min. In step (2), the temperature for adding 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid and stirring is 40-45℃, the stirring speed is 300r / min, and the stirring time is 3-5min. In step (2), the molar amount of 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid accounts for 0.08% of the sum of the molar amounts of acrylamide, 1H,1H,2H,2H-perfluoroacrylate octyl ester, sodium 3-allyloxy-2-hydroxy-1-propanesulfonate and 1-methacryloyloxyadamantane.

4. The method for synthesizing polyacrylamide for oil displacement according to claim 1, characterized in that: In step (3), the mass-to-volume ratio of 1-methacryloyloxyadamantane to n-hexane is 2:5, with units of g / mL; In step (3), the stirring speed is 300 r / min and the stirring time is 3-5 min.

5. The method for synthesizing polyacrylamide for oil displacement according to claim 1, characterized in that: In step (4), the stirring speed is controlled at 250 r / min during the polymerization reaction; In step (4), the organic phase solution, potassium persulfate solution and sodium bisulfite solution in the initiator system are added dropwise at the same rate and the addition is completed in 10 hours.

6. The method for synthesizing polyacrylamide for oil displacement according to claim 1, characterized in that: The potassium persulfate solution mentioned in step (4) is prepared by mixing potassium persulfate and deionized water evenly to obtain a potassium persulfate solution with a mass concentration of 2.0%, and then purging with nitrogen gas for 5 minutes to remove oxygen. The sodium bisulfite solution mentioned in step (4) is prepared by mixing sodium bisulfite with deionized water to obtain a sodium bisulfite solution with a mass concentration of 1.0%, and then purging with nitrogen gas for 5 minutes to remove oxygen.

7. The method for synthesizing polyacrylamide for oil displacement according to claim 1, characterized in that: In the initiation system described in step (4), the volume ratio of potassium persulfate solution to sodium bisulfite solution is 1:1; The polymerization reaction described in step (4) is first carried out at 43-45℃ for 1 hour, and then at 53-55℃ for 1 hour; In step (4), the molar amount of potassium persulfate in the potassium persulfate solution is 0.05% of the sum of the molar amounts of acrylamide, 1H,1H,2H,2H-octyl perfluoroacrylate, sodium 3-allyloxy-2-hydroxy-1-propanesulfonate, and 1-methacryloyloxyadamantane.

8. The method for synthesizing polyacrylamide for oil displacement according to claim 1, characterized in that: The vacuum rotary evaporation in step (5) is carried out at a temperature of 40°C, a pressure of -0.09 MPa, and a time of 30 min. The filtration described in step (5) is performed using a 0.2-micron polyethersulfone pleated filter cartridge.

9. The method for synthesizing polyacrylamide for oil displacement according to claim 1, characterized in that: In step (5), the inlet temperature of the spray dryer is 160°C and the outlet temperature of the spray dryer is 75°C.

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