Instant oil displacement polymer, its preparation method and application

Abstract

The application provides a quick-dissolving oil-displacing polymer and a preparation method and application thereof. The method comprises the following steps: introducing inert gas A into an aqueous solution of an alkenyl monomer including N-[(4-sulfonamide)phenyl] acrylamide to remove oxygen, then introducing inert gas B micro-nano bubbles, and then initiating a polymerization reaction by at least one of the following methods: light initiation, thermal initiation, radiation initiation and redox initiation to obtain a colloid, and then treating the obtained colloid to obtain the quick-dissolving oil-displacing polymer. The introduction of sulfonic acid structural units and structural units with benzene ring structures significantly improves the hydrophilic ability of the side chain of the polymer and the heat resistance of the polymer, and simultaneously significantly improves the long-term viscosity retention rate. The porous structure of the polymer greatly reduces the dissolution time of the polymer. The free radical initiation effect of the micro-nano bubbles can play an auxiliary role in the free radical polymerization, can improve the polymerization efficiency, saves the polymerization cost, and can be used for polymer flooding in high-temperature and high-salt oil reservoirs.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil recovery, and further relates to a fast-dissolving oil displacement polymer, a preparation method and application thereof. BACKGROUND

[0002] Polymer flooding is an important technical means for realizing "increased production and high production" in offshore oilfields. In the development and application process of tertiary oil recovery in offshore oilfields, the special structure of the oil recovery platform and the limitation of available space make it difficult to popularize and apply the polymer injection station and the gap liquid preparation mode used in land oilfields. Although the Chinese invention patent CN204252982U discloses a modular skid-type polymer injection system capable of realizing continuous liquid preparation and online maturation, which is used to replace the existing gap liquid preparation and polymer injection system in land oilfields, shorten the maturation time, and realize the purpose of improving the oil recovery of offshore oilfields. However, the polymer used for offshore injection is prepared by using sewage, and the online maturation time is short, which leads to incomplete dissolution, increased flow resistance, increased working load of the polymer injection pump, and high injection pressure of the polymer injection well. Within a certain time range, the formation will be blocked. Therefore, it is urgent to develop a fast-dissolving oil displacement polymer suitable for offshore polymer flooding. The existing technology for increasing the dissolution speed of the polymer includes introducing water-soluble monomers, adding a dissolving agent, and changing the physical morphology.

[0003] In recent years, technologies capable of efficiently producing micro-nano bubbles have attracted more and more attention. Micro-nano bubbles generally refer to bubbles with a diameter of less than 50 μm. Compared with traditional coarse bubbles (diameter > 50 mm) and fine bubbles (diameter < 5 mm), micro-nano bubbles have a small diameter, and the small size effect is significant. Their mass transfer and heat transfer characteristics and interface properties are significantly different from those of traditional coarse bubbles. For example, micro-nano bubbles greatly increase the total area of vapor-liquid contact due to their small volume, and have a large specific surface area. Therefore, the large specific surface area of micro-nano bubbles can be utilized to introduce them into the synthesis process of traditional oil displacement polyacrylamide to obtain a temperature-resistant and salt-resistant fast-dissolving oil displacement polymer containing micro-nano bubbles, thereby solving the problem of long dissolution time of traditional oil displacement polyacrylamide. At the same time, the introduction of water-soluble functional monomers can significantly reduce the dissolution time of the polymer. SUMMARY

[0004] In order to solve the technical problems existing in the prior art, the present application provides a fast-dissolving oil displacement polymer, a preparation method and application thereof.

[0005] The application prepares a temperature-resistant and salt-resistant instant dissolving oil displacement polymer, aiming at overcoming the problem of long polymer dissolving time in the prior art. By utilizing the small size effect of micro-nano bubbles, the micro-nano bubbles are introduced into the synthesis process of traditional oil displacement polyacrylamide, so that the temperature-resistant and salt-resistant instant dissolving porous polyacrylamide powder particles with uniformly distributed micro-nano bubbles inside and on the surface are obtained. In the powder particle dissolving and ripening process, the micro-nano bubbles are quickly penetrated and swelled by water, so that the dissolving time of the polymer is greatly reduced. Meanwhile, the introduction of water-soluble functional monomers can significantly reduce the dissolving time of the polymer.

[0006] In the application, the micro-nano bubbles with a diameter of 20 nanometers to 50 microns are generated by selecting a suitable gas source. After the system is initiated to become viscous, the micro-nano bubbles are fixed in the system, so that the porous polyacrylamide powder particles with uniformly distributed micro-nano bubbles inside and on the surface are obtained. The existence of the small size bubbles inside and on the surface of the porous polyacrylamide powder particles can make the bubbles quickly penetrated and swelled by water, so that the dissolving time of the polymer is greatly reduced. In the structure of the polymer, the sulfonic acid structural unit with strong hydration capacity and the structural unit with benzene ring structure are introduced, so that the hydrophilic capacity of the side chain of the polymer and the heat resistance of the polymer are significantly improved, the dissolving speed and long-term viscosity retention rate of the polymer are significantly improved, and the polymer can be used as a chemical agent for offshore oil field polymer flooding and high temperature and high salt reservoir polymer flooding.

[0007] Meanwhile, when the average diameter of the micro-nano bubbles in the application is 50 nanometers to 500 nanometers, the micro-nano bubbles are introduced into the free radical solution polymerization system of the alkenyl monomer, so that the cavitation effect is generated. After the cavitation of the micro-nano bubbles in the system, a large number of hydroxyl radicals are generated, which are used to initiate the free radical solution polymerization of the alkenyl monomer. The micro-nano bubbles can assist the free radical polymerization, so that the polymerization efficiency is improved, the polymerization cost is saved, the degradation of the polymer at high temperature caused by the residual initiator is reduced, and the hydrothermal aging stability of the polymer is enhanced.

[0008] One of the purposes of the application is to provide an instant dissolving oil displacement polymer.

[0009] The structural formula of the instant dissolving oil displacement polymer comprises a structural unit A, a structural unit B and a structural unit C.

[0010] The structural unit A is The structural unit B is The structural unit C is

[0011] wherein R1, R3, R4 and R5 are independently selected from H or methyl; M2 is H, sodium or potassium.

[0012] In a preferred embodiment of the application,

[0013] The structural formula of the instant dissolving oil displacement polymer further comprises a structural unit D.

[0014] the structural unit D is

[0015] wherein R2 is H or methyl; M1 is H, sodium or potassium.

[0016] In a preferred embodiment of the present application,

[0017] with the total mass of the instant oil displacement polymer being 100%,

[0018] the mass content of the structural unit A is 60-98%; preferably 70-94%;

[0019] the mass content of the structural unit B is 1-25%; preferably 3-20%;

[0020] the mass content of the structural unit C is 1-15%; preferably 3-10%.

[0021] In a preferred embodiment of the present application,

[0022] with the total mass of the instant oil displacement polymer being 100%,

[0023] the mass content of the structural unit A and the structural unit D is 60-98%; preferably 70-94%; wherein the structural unit D accounts for 5-30% of the total mass of the structural unit A and the structural unit D; preferably 8-20%;

[0024] the mass content of the structural unit B is 1-25%; preferably 3-20%;

[0025] the mass content of the structural unit C is 1-15%; preferably 3-10%.

[0026] The second object of the present application is to provide a preparation method of the instant oil displacement polymer, comprising:

[0027] introducing the alkene monomer aqueous solution into inert gas A to remove oxygen, then introducing inert gas B micro-nano bubbles, and then initiating polymerization to obtain a colloid, and then treating the obtained colloid to obtain the instant oil displacement polymer;

[0028] The initiation polymerization is at least one of photo initiation, thermal initiation, radiation initiation, and oxidation-reduction initiation.

[0029] The initiator in the above initiation polymerization can use at least one of the initiators commonly used in the prior art in the field, such as azo initiators, oxidation-reduction initiators, and photo initiators, and the amount of the initiator is a conventional amount, and the person skilled in the art can select the initiator and the amount of the initiator according to the actual situation.

[0030] In the present application, it can be preferred that:

[0031] The amount of the azo initiator is 0.0001% to 0.1% of the total mass of the monomer mixture, the amount of the redox initiator is 0.0002% to 0.3% of the total mass of the monomer mixture, the amount of the photoinitiator is 0.0002% to 0.3% of the total mass of the monomer mixture, the azo initiator is a water-soluble azo initiator, the redox initiator comprises an oxidizing agent and a reducing agent, the reducing agent is at least one of an inorganic reducing agent and an organic reducing agent, and the mass ratio of the oxidizing agent to the reducing agent is (0.1 to 1) : 1;

[0032] The water-soluble azo initiator is at least one of 2,2'-azobis(2-imidazolinopropane) dihydrochloride, 2,2'-azobis(2-imidazolinopropane) dihydrochloride, and 4,4'-azobis(4-cyanopentanoic acid), the oxidizing agent is at least one of benzoyl peroxide, hydrogen peroxide, tert-butyl hydroperoxide, 2,5-dimethyl-2,5-bis(hydroperoxide) hexane, ammonium persulfate, sodium persulfate, and potassium persulfate, the inorganic reducing agent is at least one of ferrous sulfate, ferrous ammonium sulfate, cuprous chloride, potassium sulfite, sodium sulfite, ammonium bisulfite, potassium bisulfite, sodium thiosulfate, potassium thiosulfate, ivory powder, and sodium bisulfite, the organic reducing agent is at least one of N,N-dimethylethanolamine, N,N'-dimethylpiperazine, N,N,N',N'-tetramethylurea, and N,N,N',N'-tetramethylethylenediamine, and the photoinitiator is at least one of 2-hydroxy-2,2-dimethylphenylacetophenone and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone.

[0033] The alkenyl monomer comprises alkenyl monomer A', alkenyl monomer B', and alkenyl monomer C';

[0034] The alkenyl monomer A' is (at least one of acrylamide and methacrylamide); the alkenyl monomer B' is

[0035] The alkenyl monomer C' is (N-[(4-sulfonamide)phenyl]acrylamide);

[0036] wherein R1, R3, R4, and R5 are each independently selected from H or methyl; and M2 is H, sodium, or potassium.

[0037] In a preferred embodiment of the present application,

[0038] The alkenyl monomer further comprises alkenyl monomer D'; the alkenyl monomer D' is (acrylate);

[0039] wherein R2 is H or methyl; M1 is H, sodium or potassium.

[0040] In one preferred embodiment of the present application,

[0041] The mass of the alkenyl monomer A' accounts for 60-98% of the total mass of the alkenyl monomers; preferably 70-94%; the mass of the alkenyl monomer B' accounts for 1-25% of the total mass of the alkenyl monomers; preferably 3-20%; the mass of the alkenyl monomer C' accounts for 1-15% of the total mass of the alkenyl monomers; preferably 3-10%.

[0042] In one preferred embodiment of the present application,

[0043] The mass of the alkenyl monomer A' and the mass of the alkenyl monomer D' together account for 60-98% of the total mass of the alkenyl monomers; preferably 70-94%; the mass of the alkenyl monomer B' accounts for 1-25% of the total mass of the alkenyl monomers; preferably 3-20%; the mass of the alkenyl monomer C' accounts for 1-15% of the total mass of the alkenyl monomers; preferably 3-10%.

[0044] The mass of the alkenyl monomer D' accounts for 5-30% of the total mass of the alkenyl monomer A' and the alkenyl monomer D'; preferably 8-20%.

[0045] In one preferred embodiment of the present application,

[0046] The average diameter of the micro-nano bubbles of the inert gas B is 20 nanometers-50 micrometers; preferably 50 nanometers-20 micrometers.

[0047] The small size effect of the micro-nano bubbles is well reflected in 20 nanometers-50 micrometers, and the mass transfer and heat transfer characteristics and interface properties thereof are obviously different from those of traditional large bubbles, and the micro-nano bubbles have physical and chemical properties that traditional bubbles do not have. The micro-nano bubbles are uniformly distributed in the polymerization solution during the polymerization process, can realize intensified and efficient heat transfer, on the one hand, reduce the fluctuation of colloid performance caused by local polymerization overheating; on the other hand, in the drying process, the micro-nano bubbles on the surface of the colloid can greatly increase the specific surface area, intensify the efficient heat transfer, shorten the drying time, and reduce the energy consumption; on the other hand, the cooling time of the colloid particles is shortened, and the efficiency of the subsequent crushing and screening process is improved.

[0048] In one preferred embodiment of the present application,

[0049] The average diameter of the micro-nano bubbles of the inert gas B is 50 nanometers-500 nanometers; preferably 50 nanometers-200 nanometers.

[0050] When the average diameter of the micro-nano bubbles is 50nm-500nm, the micro-nano bubbles are introduced into the aqueous solution of the alkenyl monomer to start cavitation, and in the aqueous solution of the alkenyl monomer, the formation, growth and collapse of the micro-nano bubbles are called cavitation, because the micro-nano bubbles have a small volume and the buoyancy received in water is far less than that of ordinary bubbles in water, the micro-nano bubbles can stay in water for several minutes or even several hours, and in the cavitation process, when the micro-nano bubbles shrink, the charge density of the double electric layer increases rapidly, and when the gas-liquid interface disappears, the energy accumulated by the high-concentration positive and negative ions is released, at this time, a large number of hydroxyl radicals are generated, thereby initiating the free radical solution polymerization of the alkenyl monomer, which can play a role in assisting the free radical polymerization and can improve the polymerization efficiency and save the polymerization cost.

[0051] Preferably, the micro-nano bubbles are introduced by a micro-nano bubble generator of Model LF-1500 produced by Shandong Micro-bubble Environmental Protection Equipment Co., Ltd., and the diameter of the bubbles is controlled by a rotor flow meter, pressure and the generator; when the gas inlet amount of the micro-nano bubble generator is controlled at 10-200mL / min and the inlet pressure is controlled at 0.2-1MPa, the average diameter of the micro-nano bubbles can be controlled at 50nm-20μm.

[0052] In a preferred embodiment of the present application,

[0053] The mass concentration of the aqueous solution of the alkenyl monomer is 10-50%, preferably 15-35%, and / or,

[0054] The inert gas A and the inert gas B are each independently selected from at least one of nitrogen, argon and helium;

[0055] The pH value of the aqueous solution of the alkenyl monomer is 6-10, preferably 6-9;

[0056] The reaction temperature is -10℃-40℃, preferably 0-25℃;

[0057] The bubble diameter of the inert gas A is 1mm-10mm, and the introduction time is 5min-60min, preferably 20-40min;

[0058] The purpose of introducing the inert gas A is to remove oxygen, and an ordinary nitrogen cylinder is added with a pressure reducing valve with a flow meter, the flow of the pressure reducing valve is controlled at 2-20L / min, preferably 5-15L / min, and the inert gas A with a bubble diameter of 1mm-10mm can be provided;

[0059] After the temperature of the system rises by 0.5℃-1℃, the introduction of the micro-nano bubbles is stopped, and the reaction is continued for 1-6 hours, preferably 2-5 hours;

[0060] The treatment method of the colloid is granulating, hydrolyzing or not, drying, crushing and screening the obtained colloid.

[0061] The third object of the present application is to provide a quick-dissolving oil displacement polymer prepared by the above method.

[0062] The fourth object of the present application is to provide an application of the quick-dissolving oil displacement polymer in oil reservoir exploitation, preferably in high-temperature and high-salinity oil reservoir polymer flooding and offshore oil field polymer flooding.

[0063] The temperature-resistant and salt-resistant quick-dissolving oil displacement polymer can be applied in high-temperature and high-salinity oil reservoir exploitation, especially in offshore oil reservoir as an oil displacement agent for polymer flooding.

[0064] Compared with the prior art, the present application has the following beneficial effects:

[0065] The present application introduces the micro-nano bubbles into the traditional oil displacement polyacrylamide synthesis process by taking advantage of the small size effect of the micro-nano bubbles, so that the porous structure is introduced into the polyacrylamide powder particles, and the contact with water can be quickly penetrated and swelled, thereby greatly reducing the dissolution time of the polymer.

[0066] The present application introduces the sulfonic acid structural unit with strong hydration capacity and the structural unit with benzene ring structure into the structure of the polymer, thereby significantly improving the hydrophilic capacity of the polymer side chain and the heat resistance of the polymer, and significantly reducing the dissolution time of the polymer, and simultaneously significantly improving the long-term viscosity retention rate.

[0067] When the average diameter of the micro-nano bubbles in the present application is 50 nanometers to 500 nanometers, the "cavitation" effect can be achieved to initiate the radical solution polymerization of the alkenyl monomer, which can play an auxiliary role in the radical polymerization, can improve the polymerization efficiency, and save the polymerization cost. At the same time, the degradation of the polymer at high temperature caused by the residual initiator can be reduced, and the hydrothermal aging stability of the polymer is enhanced.

[0068] The quick-dissolving oil displacement polymer prepared by the present application is temperature-resistant and salt-resistant, and can be used as an oil displacement agent for polymer flooding in high-temperature and high-salinity oil reservoir exploitation, especially in offshore oil reservoir. It can be quickly dissolved and matured in water with a temperature of 30-65 DEG C, a salinity of 5000-30000 mg / L, and a calcium and magnesium ion content of 500-2000 mg / L. In simulated brine with a temperature of 105 DEG C, a salinity of <30000 mg / L, and a calcium and magnesium ion content of <2000 mg / L, the viscosity retention rate is high after aging for 30 days, and the polymer has good thermal stability. DETAILED DESCRIPTION

[0069] The following specific description of the present application is made in conjunction with specific embodiments, it is necessary to point out that the following examples are only used to further illustrate the present application, and cannot be understood as limiting the scope of protection of the present application, some non-essential improvements and adjustments made by those skilled in the art based on the content of the present application still fall within the scope of protection of the present application.

[0070] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges and values are provided as approximate values, and the ranges and values should be understood to encompass values approximately the same as the stated values. For numerical ranges, the end points of the ranges are included in the ranges, and the individual points within the ranges are included in the ranges.

[0071] The raw materials used in the examples and comparative examples are all conventional commercially available raw materials;

[0072] Acrylamide crystals were purchased from Shandong Nole Biological Technology Co., Ltd.;

[0073] N-[(4-sulfonamide)phenyl]acrylamide was purchased from Beijing Guangwen Fine Chemical Research Institute.

[0074] 2-(Methyl)acrylamide-2-methylpropane sulfonic acid (sodium) was purchased from Inokai Technology Co., Ltd.

[0075] The test method is as follows:

[0076] Dissolution rate: The standard Q / HNYJ 325-2008 "Polyacrylamide Dissolution Rate Test Implementation Details" was used, and the test was carried out in simulated brine with a salinity of 10000 mg / L at 40°C; the specific method is as follows:

[0077] ① In a clean beaker, add 300 g of simulated brine, and add 2-3 drops of 1% indigo blue disulfonic acid sodium;

[0078] ② Accurately weigh 0.3 g of polymer dry powder (accurate to 0.01 g);

[0079] ③ Start stirring, and slowly add the weighed polymer dry powder at a speed of 500 rpm;

[0080] ④ Observe the dissolution state at intervals. If the solution color is evenly distributed, it indicates that it has completely dissolved; if there are still bright spots, continue to observe until the solution is evenly dissolved and the experiment is completed;

[0081] Filter factor: The petroleum and natural gas industry standard Q / HNYJ 310-2007 "Polyacrylamide Filter Factor Test Implementation Details" was used for detection;

[0082] Aging viscosity retention rate: the viscosity of 2500mg / L polymer solution after being placed for a certain number of days is measured in a simulated brine with a temperature of 105℃, a salinity of 30000mg / L, a calcium and magnesium ion content of 800mg / L, and an oxygen content of less than 0.5mg / L, and the aging viscosity retention rate is obtained by the ratio of the viscosity after aging to the initial viscosity.

[0083] Residual monomer content determination: liquid chromatography is used for determination, and reference is made to Q / SH10201572-2017 "Polyacrylamide for Oil Displacement" of Shengli Oil Management Bureau of China Petroleum Group; in the present application, the unreacted monomer contents of acrylamide, 2-(methyl)acrylamide-2-methylpropane sulfonic acid (sodium), and N-[(4-sulfonamide)phenyl]acrylamide in the tested polymer are determined, and when the determined monomer content is below 0.1%, it is considered that the monomer has completely participated in the polymerization reaction.

[0084] Example 1

[0085] 50g of acrylamide, 10g of 2-acrylamido-2-methylpropane sulfonic acid, and 3g of N-[(4-sulfonamide)phenyl]acrylamide are dissolved in 237g of deionized water, and the pH value is adjusted to 7.0, the initial temperature is controlled to 0℃, and the system is deoxygenated by blowing nitrogen gas with a bubble diameter of 1mm-10mm for 20min, then the average diameter of the nitrogen nanobubbles in the system is introduced into the system (the gas inlet pressure is controlled at 0.8MPa, and the gas inlet amount is controlled at 10mL / min), so that the nanobubbles are uniformly present in the system, and the timing is started, then 1.2g of 0.25% 2,2-azobis(2-imidazolinopropane) dihydrochloride aqueous solution, 2.5g of 0.2% ammonium persulfate aqueous solution, and 1.5g of 0.6% sodium bisulfite aqueous solution are added to initiate polymerization, and after the system temperature rises by 0.5℃, the polymerization induction period ends, the timing is stopped, the introduction of nitrogen nanobubbles is stopped, and the reaction continues for 4 hours, after the polymerization is completed, the obtained colloid is granulated, 4.23g of sodium hydroxide is added, and hydrolysis reaction is carried out at 70℃ for 4 hours, and then the product is dried at 50℃ until the solid content reaches 89%, and then it is crushed and sieved to obtain a quick-dissolving oil displacement polymer dry powder product.

[0086] Structure unit A is accounting for 79.3% of the total mass of the polymer;

[0087] Structure unit B is accounting for 15.9% of the total mass of the polymer;

[0088] Structure unit C is accounting for 4.8% of the total mass of the polymer.

[0089] The structure of the obtained polymer is characterized by infrared spectroscopy. The characteristic peaks of the obtained polymer are 3365cm -1 and 1655cm-1 characteristic absorption of acrylamide structural unit, wave number 1190 cm -1 and 1040 cm -1 characteristic absorption of 2-acrylamido-2-methylpropane sulfonic acid structural unit, wave number 1481 cm -1 , 1404 cm -1 and 997 cm -1 characteristic absorption of N-[(4-sulfonamide)phenyl]acrylamide structural unit, proving that the resultant product is a polymer of the three monomers.

[0090] The induction period was calculated, and the drying time, dissolution time, filtration factor, residual monomer content, and aging viscosity retention rate of the instant oil displacement polymer dry powder product were determined. The results are shown in Table 1.

[0091] Example 2

[0092] 55 g of acrylamide, 15 g of 2-acrylamido-2-methylpropane sulfonic acid sodium salt, and 7 g of N-[(4-sulfonamide)phenyl]acrylamide were dissolved in 223 g of deionized water, and the pH value was adjusted to 8.0. The initial temperature was controlled at 10°C, and the system was deoxygenated by bubbling nitrogen gas with a bubble diameter of 1 mm to 10 mm for 20 min. Thereafter, helium nanobubbles with an average diameter of 100 nm were introduced into the system (the gas inlet pressure was controlled at 0.5 MPa, and the gas inlet amount was controlled at 15 mL / min), and the timing was started so that the nanobubbles were uniformly present in the system. Thereafter, 0.2 g of 2-hydroxy-2,2-dimethylphenylacetophenone photoinitiator with a mass concentration of 0.05% and 1.0 g of 2,2-azobis(2-imidazolinopropane) dihydrochloride aqueous solution with a mass concentration of 0.25% were added to the system, and the polymerization was initiated by light irradiation (100 W ultraviolet light irradiation). After the temperature of the system rose by 0.5°C, the polymerization induction period ended, the timing was stopped, and the introduction of helium nanobubbles was stopped. The reaction was continued for 5 hours, and after the polymerization was completed, the obtained colloid was granulated, 6.20 g of sodium hydroxide was added, and a hydrolysis reaction was performed at 70°C for 4 hours. The product was dried at 50°C until the solid content reached 89%, was crushed, and was sieved to obtain an instant oil displacement polymer dry powder product.

[0093] Structural unit A, structural unit C have the same structure as in Example 1, and structural unit B has the structure

[0094] Structural unit A accounts for 71.5% of the total mass of the polymer;

[0095] Structural unit B accounts for 19.5% of the total mass of the polymer;

[0096] Structural unit C accounts for 9% of the total mass of the polymer.

[0097] The induction period was calculated, and the drying time, dissolution time, filtration factor, residual monomer content, and aging viscosity retention rate of the instant oil-displacing polymer dry powder product were determined. The results are shown in Table 1.

[0098] Example 3

[0099] 50 g of acrylamide, 2 g of 2-acrylamido-2-methylpropanesulfonic acid, and 2 g of N-[(4-sulfonamide)phenyl]acrylamide were dissolved in 246 g of deionized water, and the pH was adjusted to 9.0. The initial temperature was controlled at 20°C, and the system was deoxygenated by bubbling nitrogen gas with a bubble diameter of 1 mm to 10 mm for 25 min. Then, nitrogen micro-nano bubbles with an average diameter of 200 nm were introduced into the system (the gas inlet pressure was controlled at 0.3 MPa, and the gas inlet amount was controlled at 20 mL / min), so that the micro-nano bubbles were uniformly present in the system. Timing was started, and then 1.0 g of a 0.25% aqueous solution of 2,2-azobis(2-imidazolinopropane) dihydrochloride, 2 g of a 0.2% aqueous solution of ammonium persulfate, and 1.5 g of a 0.6% aqueous solution of sodium bisulfite were added to initiate polymerization. After the temperature of the system rose by 0.5°C, the polymerization induction period ended, timing was stopped, and the introduction of the nano-bubbles was stopped. The reaction was continued for 3 hours, and after the polymerization was completed, the obtained colloid was granulated, 7.04 g of sodium hydroxide was added, and a hydrolysis reaction was performed at 70°C for 4 hours. The product was dried at 50°C until the solid content reached 89%, was crushed, and was sieved to obtain an instant oil-displacing polymer dry powder product.

[0100] The structures of structural unit A, structural unit B, and structural unit C were the same as in Example 1.

[0101] Structural unit A accounted for 92.6% of the total mass of the polymer.

[0102] Structural unit B accounted for 3.7% of the total mass of the polymer.

[0103] Structural unit C accounted for 3.7% of the total mass of the polymer.

[0104] The induction period was calculated, and the drying time, dissolution time, filtration factor, residual monomer content, and aging viscosity retention rate of the instant oil-displacing polymer dry powder product were determined. The results are shown in Table 1.

[0105] Example 4

[0106] Dissolve 50 g of acrylamide, 10 g of 2-acrylamido-2-methylpropanesulfonic acid, and 3 g of N-[(4-sulfonamido)phenyl]acrylamide in 237 g of deionized water, adjust the pH to 7.0, control the initial temperature to 0°C, and bubble nitrogen gas with a diameter of 1 mm to 10 mm to remove oxygen from the system for 20 min. Then introduce nitrogen nanobubbles with an average diameter of 0.5 microns into the system (the gas inlet pressure is controlled at 0.4 MPa, and the gas inlet amount is controlled at 80 mL / min), start timing, and make the micron bubbles uniformly exist in the system. Then add 1.2 g of 0.25% 2,2-azobis(2-imidazolinopropane) dihydrochloride aqueous solution, 2 g of 0.2% ammonium persulfate aqueous solution, and 1.5 g of 0.6% sodium bisulfite aqueous solution to initiate polymerization. When the system temperature rises by 0.5°C, the polymerization induction period ends, the timing stops, the nanobubbles are stopped, and the reaction continues for 4 hours. After the polymerization is completed, the obtained colloid is granulated, dried at 50°C until the solid content reaches 89%, crushed, and sieved to obtain a quick-dissolving oil-displacing polymer dry powder product.

[0107] The structures of structural unit A, structural unit B, and structural unit C are the same as in Example 1.

[0108] Structural unit A accounts for 79.4% of the total mass of the polymer.

[0109] Structural unit B accounts for 15.9% of the total mass of the polymer.

[0110] Structural unit C accounts for 4.8% of the total mass of the polymer.

[0111] The induction period is calculated, and the drying time, dissolution time, filtration factor, residual monomer content, and aging viscosity retention rate of the quick-dissolving oil-displacing polymer dry powder product are determined. The results are shown in Table 1.

[0112] Example 5

[0113] Dissolve 62.1 g of acrylamide, 14.9 g of sodium acrylate, 20 g of 2-acrylamido-2-methylpropanesulfonic acid, and 3 g of N-[(4-sulfonamido)phenyl] acrylamide in 200 g of deionized water, adjust the pH to 7.0, control the initial temperature to 25°C, and bubble nitrogen gas with a diameter of 1 mm to 10 mm into the system for 40 min to remove oxygen. Then introduce nitrogen gas bubbles with an average diameter of 5 microns into the system (control the gas inlet pressure at 0.2 MPa and the gas inlet amount at 90 mL / min), start timing, and make the nitrogen micron bubbles uniformly exist in the system. Then add 1.2 g of 0.25% 2,2-azobis(2-imidazolinopropane) dihydrochloride aqueous solution, 2.5 g of 0.2% ammonium persulfate aqueous solution, and 1.5 g of 0.6% sodium bisulfite aqueous solution to initiate polymerization. When the system temperature rises by 1.0°C, the polymerization induction period ends, timing is stopped, micron bubbles are stopped, and the reaction continues for 2 hours. After the polymerization is completed, the obtained colloid is granulated, dried at 50°C until the solid content reaches 89%, crushed, and sieved to obtain a quick-dissolving oil-displacing polymer dry powder product.

[0114] The structures of structural unit A, structural unit B, and structural unit C are the same as in Example 1, and the structure of structural unit D is

[0115] Structural unit A accounts for 62.1% of the total mass of the polymer;

[0116] Structural unit B accounts for 20% of the total mass of the polymer;

[0117] Structural unit C accounts for 3% of the total mass of the polymer;

[0118] Structural unit D accounts for 14.9% of the total mass of the polymer.

[0119] Calculate the induction period, and measure the drying time, dissolution time, filtration factor, residual monomer content, and aging viscosity retention rate of the quick-dissolving oil-displacing polymer dry powder product. The measurement results are shown in Table 1.

[0120] Example 6

[0121] Dissolve 48 g of acrylamide, 5 g of sodium methacrylate, 8 g of 2-acrylamido-2-methylpropanesulfonic acid, and 3 g of N-[(4-sulfonamido)phenyl] acrylamide in 236 g of deionized water, adjust the pH to 7.0, control the initial temperature to 0°C, and bubble nitrogen gas with a diameter of 1 mm to 10 mm into the system for 20 min to remove oxygen. Then introduce nitrogen gas bubbles with an average diameter of 20 microns into the system (control the gas inlet pressure at 0.2 MPa and the gas inlet amount at 200 mL / min), start timing, and make the nitrogen micron bubbles uniformly exist in the system. Then add 1.2 g of 0.25% 2,2-azobis(2-imidazolinopropane) dihydrochloride aqueous solution, 2.5 g of 0.2% ammonium persulfate aqueous solution, and 1.5 g of 0.6% sodium bisulfite aqueous solution to initiate polymerization. When the system temperature rises by 0.5°C, the polymerization induction period ends, timing is stopped, micron bubbles are stopped, and the reaction continues for 4 hours. After the polymerization is completed, the obtained colloid is granulated, dried at 50°C until the solid content reaches 89%, crushed, and sieved to obtain a quick-dissolving oil-displacing polymer dry powder product.

[0122] The structures of structural unit A, structural unit B, and structural unit C are the same as in Example 1, and the structure of structural unit D is

[0123] Structural unit A accounts for 75% of the total mass of the polymer;

[0124] Structural unit B accounts for 12.5% of the total mass of the polymer;

[0125] Structural unit C accounts for 4.7% of the total mass of the polymer;

[0126] Structural unit D accounts for 7.8% of the total mass of the polymer.

[0127] Calculate the induction period, and measure the drying time, dissolution time, filtration factor, residual monomer content, and aging viscosity retention rate of the quick-dissolving oil-displacing polymer dry powder product. The measurement results are shown in Table 1.

[0128] Example 7

[0129] Dissolve 52 g of acrylamide, 13 g of sodium acrylate, 18 g of 2-acrylamido-2-methylpropanesulfonic acid, and 7 g of N-[(4-sulfonamido)phenyl] acrylamide in 210 g of deionized water, adjust the pH to 7.0, control the initial temperature to 0°C, deoxygenate the system by blowing 1 mm-10 mm nitrogen gas for 20 min, then introduce 50 nm nitrogen nanobubbles into the system (control the gas inlet pressure to 0.8 MPa and the gas inlet amount to 10 mL / min), make the nanobubbles uniformly exist in the system, start timing, then introduce 1.0 g of 0.25% 2,2-azobis(2-amidinopropane) dihydrochloride aqueous solution, 2 g of 0.2% ammonium persulfate aqueous solution, and 1.5 g of 0.6% sodium bisulfite aqueous solution to initiate polymerization, after the temperature of the system rises by 0.5°C, the polymerization induction period ends, stop timing, stop introducing the nitrogen nanobubbles, and continue to react for 4 hours. After the polymerization is completed, the obtained colloid is granulated, dried at 50°C until the solid content reaches 89%, crushed, and sieved to obtain a dry instant oil-displacing polymer powder product.

[0130] Structural unit A, structural unit B, structural unit C, and structural unit D have the same structures as in Example 5.

[0131] Structural unit A accounts for 57.8% of the total mass of the polymer.

[0132] Structural unit B accounts for 20% of the total mass of the polymer.

[0133] Structural unit C accounts for 7.8% of the total mass of the polymer.

[0134] Structural unit D accounts for 14.4% of the total mass of the polymer.

[0135] The induction period is calculated, and the drying time, dissolution time, filtration factor, residual monomer content, and aging viscosity retention rate of the dry instant oil-displacing polymer powder product are determined. The results are shown in Table 1.

[0136] Comparative Example 1

[0137] The difference between Comparative Example 1 and Example 1 is that no micro-nano inert gas bubbles are introduced.

[0138] Except that no micro-nano inert gas bubbles are introduced into the system, the raw materials, amounts, process, and preparation method of Comparative Example 1 are the same as those of Example 1.

[0139] A dry polymer powder product is obtained.

[0140] The induction period is calculated, and the drying time, dissolution time, filtration factor, residual monomer content, and aging viscosity retention rate of the dry polymer powder product are determined. The results are shown in Table 1.

[0141] Comparative Example 2

[0142] The difference between Comparative Example 2 and Example 1 is that 3 g of acrylamide is used to replace the equivalent amount of N-[(4-sulfonamido)phenyl] acrylamide, and Comparative Example 2 does not contain N-[(4-sulfonamido)phenyl] acrylamide.

[0143] Except for the above two differences, the raw materials, amounts, processes, and preparation methods of Comparative Example 2 are the same as those of Example 1.

[0144] The polymer dry powder product is obtained.

[0145] The induction period is calculated, and the drying time, dissolution time, filtration factor, residual monomer content, and aging viscosity retention rate of the temperature-resistant and salt-resistant instant porous polymer dry powder product are determined. The results are shown in Table 1.

[0146] Comparative Example 3

[0147] The difference between Comparative Example 3 and Example 1 is that no micro-nano inert gas bubbles are introduced into the system, and the amount of initiator is increased. 3.0 g of 2,2-azobis(2-imidazolinopropane) dihydrochloride aqueous solution with a mass concentration of 0.25% is added to the system, and redox initiators (3.0 g of ammonium persulfate aqueous solution with a mass concentration of 0.2% and 5 g of sodium bisulfite aqueous solution with a mass concentration of 0.6%) are used to initiate polymerization.

[0148] Except for the above two differences, the raw materials, amounts, processes, and preparation methods of Comparative Example 3 are the same as those of Example 1.

[0149] The polymer dry powder product is obtained.

[0150] The induction period is calculated, and the drying time, dissolution time, filtration factor, residual monomer content, and aging viscosity retention rate of the polymer dry powder product are determined. The results are shown in Table 1.

[0151] Table 1: Performance test results of Examples 1-7 and Comparative Examples 1-3

[0152]

[0153] As can be seen from the data in Table 1, by introducing micro-nano bubbles into the system, the average diameter of the micro-nano bubbles is 50 nm to 20 μm, and the instant oil-displacing polymer dry powder product obtained has a porous structure. The drying time at 50°C is 8.5-11.5 h, which is significantly lower than the drying time of 48 h at 50°C of Comparative Examples 1 and 3, proving that by introducing micro-nano bubbles into the system, the drying time of the system can be greatly shortened, which is of great significance for reducing production energy consumption.

[0154] The induction period of Examples 1-4, 7 and Comparative Example 2 is significantly lower than that of Examples 5-6 in which 5-micron and 20-micron bubbles are introduced and Comparative Example 1 in which no micro-nano bubbles are introduced, and is equivalent to that of Comparative Example 3 in which no micro-nano bubbles are introduced but the amount of initiator is increased, proving that the introduction of inert gas bubbles with an average diameter of 50-500 nm into the system has a good induction polymerization effect, can partially replace the traditional initiator, and reduces the use cost of the initiator.

[0155] Examples 1-7 and Comparative Example 2 all introduce micro-nano bubbles into the system, and the dissolution time is 8-16 min, which is much less than the dissolution time of 100-102 min of Comparative Examples 1 and 3, proving that after the introduction of micro-nano bubbles, the dissolution time of the obtained polymer dry powder is shorter, and the dissolution performance is greatly improved.

[0156] From the dissolution time and filtration factor data, it can be seen that by introducing micro-nano bubbles into the system and introducing sulfonamide groups with strong hydration capacity, the solubility of the copolymer is significantly improved, and a porous polymer dry powder product is obtained, and the dissolution speed is greatly improved.

[0157] The viscosity retention rate of Examples 1-7 is better than that of Comparative Examples 1-3, indicating that the introduction of structural units with benzene ring structure into the system and the introduction of micro-nano bubbles after polymerization can produce polymer products containing micro-nano porous structure, and the viscosity retention rate is higher, which can greatly improve the long-term thermal stability of the polymer chain.

Claims

1. A fast-dissolving oil displacement polymer, characterized in that: The structural formula of the fast-dissolving oil displacement polymer includes structural unit A, structural unit B and structural unit C; Wherein, the structural unit A is ; The structural unit B is ; The structural unit C is ; R1, R3, R4, and R5 are each independently selected from H or methyl; M2 is H, sodium, or potassium. The mass content of structural unit A is 60-98%; The mass content of structural unit B is 1-25%; The mass content of the structural unit C is 1-15%; The fast-dissolving oil displacement polymer is obtained by free radical solution polymerization of alkenyl monomers, and inert gas B micro-nano bubbles are introduced in the polymerization reaction; the inert gas B is selected from at least one of nitrogen, argon and helium; the average diameter of the micro-nano bubbles of the inert gas B is 50 nanometers to 20 micrometers.

2. The fast-dissolving oil displacement polymer as described in claim 1, characterized in that: The structural formula of the fast-dissolving oil displacement polymer also includes structural unit D; The structural unit D is ; R2 is H or methyl; M1 is H, sodium or potassium.

3. The fast-dissolving oil displacement polymer as described in claim 1, characterized in that: With the total mass of the readily soluble oil displacement polymer being 100%, The mass content of structural unit A is 70-94%; The mass content of structural unit B is 3-20%; The mass content of the structural unit C is 3~10%.

4. The fast-dissolving oil displacement polymer as described in claim 2, characterized in that: With the total mass of the readily soluble oil displacement polymer being 100%, The mass content of structural unit A and structural unit D is 60-98%; wherein structural unit D accounts for 5-30% of the total mass of structural unit A and structural unit D. The mass content of structural unit B is 1-25%; The mass content of the structural unit C is 1-15%.

5. The fast-dissolving oil displacement polymer as described in claim 4, characterized in that: With the total mass of the readily soluble oil displacement polymer being 100%, The mass content of structural unit A and structural unit D is 70-94%; among which structural unit D accounts for 8-20% of the total mass of structural unit A and structural unit D. The mass content of structural unit B is 3-20%; The mass content of the structural unit C is 3~10%.

6. A method for preparing the fast-dissolving oil displacement polymer as described in any one of claims 1 to 5, characterized in that... The method includes: Inert gas A is introduced into an aqueous solution of alkenyl monomer to remove oxygen, followed by the introduction of inert gas B micro-nano bubbles, and then a polymerization reaction is initiated to obtain a colloid. After processing the obtained colloid, the fast-dissolving oil-displacing polymer is obtained. The polymerization initiation method is at least one of photoinitiation, thermal initiation, radiation initiation, and redox initiation; The alkenyl monomers include alkenyl monomer A', alkenyl monomer B' and alkenyl monomer C'; The alkenyl monomer A' is The alkenyl monomer B' is ; The alkenyl monomer C' is ; R1, R3, R4, and R5 are each independently selected from H or methyl; M2 is H, sodium, or potassium.

7. The method for preparing the fast-dissolving oil displacement polymer as described in claim 6, characterized in that: The alkenyl monomer further includes an alkenyl monomer D'; the alkenyl monomer D' is... ; R2 is H or methyl; M1 is H, sodium or potassium.

8. The method for preparing the fast-dissolving oil displacement polymer as described in claim 6, characterized in that: Alkenyl monomer A' accounts for 60-98% of the total mass of alkenyl monomers; alkenyl monomer B' accounts for 1-25% of the total mass of alkenyl monomers; and alkenyl monomer C' accounts for 1-15% of the total mass of alkenyl monomers.

9. The method for preparing the fast-dissolving oil displacement polymer as described in claim 8, characterized in that: Alkenyl monomer A' accounts for 70-94% of the total mass of alkenyl monomers; alkenyl monomer B' accounts for 3-20% of the total mass of alkenyl monomers; and alkenyl monomer C' accounts for 3-10% of the total mass of alkenyl monomers.

10. The method for preparing the fast-dissolving oil displacement polymer as described in claim 7, characterized in that: The sum of the masses of alkenyl monomers A' and D' accounts for 60-98% of the total mass of alkenyl monomers; the mass of alkenyl monomer B' accounts for 1-25% of the total mass of alkenyl monomers; and the mass of alkenyl monomer C' accounts for 1-15% of the total mass of alkenyl monomers. The mass of alkenyl monomer D' accounts for 5 to 30% of the total mass of alkenyl monomer A' and alkenyl monomer D'.

11. The method for preparing the fast-dissolving oil displacement polymer as described in claim 10, characterized in that: The sum of the masses of alkenyl monomers A' and D' accounts for 70-94% of the total mass of alkenyl monomers; the mass of alkenyl monomer B' accounts for 3-20% of the total mass of alkenyl monomers; and the mass of alkenyl monomer C' accounts for 3-10% of the total mass of alkenyl monomers. The mass of alkenyl monomer D' accounts for 8 to 20% of the total mass of alkenyl monomer A' and alkenyl monomer D'.

12. The method for preparing the fast-dissolving oil displacement polymer as described in claim 6, characterized in that: The inert gas B has micro- and nano-bubbles with an average diameter of 50 nanometers to 20 micrometers.

13. The method for preparing the fast-dissolving oil displacement polymer as described in claim 12, characterized in that: The inert gas B has micro- and nano-bubbles with an average diameter of 50 nanometers to 500 nanometers.

14. The method for preparing the fast-dissolving oil displacement polymer as described in claim 13, characterized in that: The inert gas B has micro- and nano-bubbles with an average diameter of 50 nanometers to 200 nanometers.

15. The method for preparing the fast-dissolving oil displacement polymer as described in claim 6, characterized in that: The mass concentration of the alkenyl monomer aqueous solution is 10-50%; and / or, The inert gas A and inert gas B are each independently selected from at least one of nitrogen, argon, and helium; and / or, The pH of the aqueous solution of the alkenyl monomer is 6-10; and / or, The reaction temperature is -10℃ to 40℃; and / or, The bubble diameter of inert gas A is 1 mm to 10 mm; the introduction time is 5 min to 60 min; and / or, After the system temperature is increased by 0.5℃~1℃, the introduction of micro / nano bubbles is stopped, and the reaction continues for 1 hour~6 hours; and / or, The colloid processing method involves granulating, hydrolyzing or not hydrolyzing, drying, pulverizing, and sieving the obtained colloid.

16. The method for preparing the fast-dissolving oil displacement polymer as described in claim 15, characterized in that: The mass concentration of the alkenyl monomer aqueous solution is 15-35%; and / or, The pH of the aqueous solution of the alkenyl monomer is 6-9; and / or, The reaction temperature is 0~25℃; and / or, The inert gas A is introduced for 20-40 minutes; and / or, After the system temperature rises by 0.5℃~1℃, stop introducing micro-nano bubbles and continue the reaction for 2 to 5 hours.

17. A fast-dissolving oil displacement polymer prepared by the method according to any one of claims 6 to 16.

18. The application of a fast-dissolving oil displacement polymer as described in any one of claims 1 to 5 or a fast-dissolving oil displacement polymer prepared by any one of claims 6 to 16 in oil reservoir development.

19. The application of the fast-dissolving oil displacement polymer as described in claim 18, characterized in that: Applications in polymer flooding in high-temperature and high-salinity reservoirs and offshore oilfields.

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