Nanometer microgel material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of petroleum, and particularly relates to a nano microgel material as well as a preparation method and application thereof. In hypersalinity formation water, volume expansion is limited, and the volume expansion process is not uniform and uncontrollable. According to the nano microgel material provided by the invention, a sulfonate anion group with excellent salt tolerance is introduced into the microgel, and meanwhile, the cationic functional monomer is added, so that the initial expansion of the microgel in high-salt formation water is slowed down, and the microgel can smoothly enter a deep reservoir with relatively high residual oil content through a narrow pore throat in a near wellbore area. Ester groups in the cationic functional monomers can be gradually hydrolyzed to break bonds, so that cationic groups are separated, sulfonate anion groups are released, the microgel is hydrated and swelled, and the addition amount of the anion and cation functional monomers is controlled, so that the microgel is subjected to volume expansion at a basically constant speed in high-salinity formation water, is blocked and accumulated in the deep part of the formation, and can be used for preparing the high-salinity formation. And the residual oil in the deep stratum of the oil reservoir is displaced, so that the crude oil recovery rate is increased.

Description

Technical Field

[0001] This invention belongs to the field of petroleum technology, specifically relating to a nano-microgel material, its preparation method, and its application. Background Technology

[0002] In the field of tertiary oil recovery technology, in order to improve the recovery rate of oil layers in medium and distant wells with a large remaining oil content, researchers have designed and prepared microgel deep-seated regulation and displacement materials. These materials have small initial particle size, allowing them to pass smoothly through the near-wellbore zone into the deep reservoir. Under the conditions of formation water temperature and salinity, they expand in volume and have a certain degree of viscoelasticity. They can block the narrow pores and throats of the deep reservoir formations, creating resistance to subsequent water injection, thereby expanding the volume of injected water and achieving the goal of reducing water and increasing oil production.

[0003] In existing technologies, acrylamide is used as the main monomer, with the addition of a certain amount of ionic monomers, such as sodium acrylate or sodium 2-acrylamido-2-methylpropanesulfonate, and a crosslinking agent to prepare the microgel. During polymerization, the microgel is dispersed into a large amount of formation water. Due to the repulsive effect of ion ionization, its volume rapidly expands and reaches its maximum value. Subsequently, under the influence of formation water temperature, the amide bonds of the polyacrylamide in the microgel host undergo hydrolysis, forming carboxylate ions, thereby increasing the ion content of the microgel, enhancing the ionization repulsion effect, and gradually expanding its volume. However, this hydrolytic expansion is greatly limited by formation conditions. The higher the formation water temperature, the faster the hydrolysis rate, while in medium- and low-temperature formation water, it becomes very slow, and volume expansion cannot occur even after a long time.

[0004] In highly salinized formation water, especially water with high calcium and magnesium ion content, the carboxylate ions produced by hydrolysis are easily affected by polyvalent metal ions, limiting their volume expansion and making the expansion rate uncontrollable. Existing microgel materials exhibit excessively rapid initial expansion in formation water, followed by very slow expansion. The entire expansion process is uneven and uncontrollable, causing the gel to easily accumulate and stagnate near the wellbore after injection, preventing it from penetrating deeper into the reservoir. Even if it does penetrate deeper, its poor subsequent expansion performance fails to effectively seal the injected water. Furthermore, in highly salinized formation water, volume expansion is limited by high-concentration ions, hindering effective expansion and sealing at deeper reservoir depths. Summary of the Invention

[0005] In view of the aforementioned technical problems, the present invention provides a nano-microgel material and its preparation method. The nano-microgel material can expand uniformly in high-salt formation water in oil fields. It is prepared by one-step mixing of monomer and water, and dynamic continuous UV photopolymerization of reverse microemulsion. The heat of polymerization can be effectively dissipated during the reaction, the polymerization temperature is low, and the premature failure of decomposition functional components in the system is effectively avoided.

[0006] The uniformly expanding nanogel material prepared by this invention can smoothly pass through the pore throat of the near-wellbore zone in oilfields and enter the deep reservoir under the conditions of formation water with a total mineralization of 30,000 mg / L to 120,000 mg / L and an initial average particle size of 150 nm to 300 nm. Under the conditions of formation temperature of 40℃ to 80℃, it reaches the maximum expansion particle size in 5 to 10 days. Moreover, it can achieve a basically uniform growth rate of 5 nm / day to 20 nm / day in average microgel particle size before expanding to the maximum particle size.

[0007] Therefore, the technical solution provided by the present invention is as follows:

[0008] A uniformly expanding nanogel material in high-salinity oilfield formation water is prepared from the following substances by mass percentage:

[0009] Oil phase 20-30%; oil-soluble surfactant 9-15%; water-soluble surfactant 6-10%; acrylamide 15-25%; anionic functional monomer 1-5%; cationic functional monomer 0.01-0.5%; crosslinking agent 0.0001-0.001%; ​​photoinitiator 0.005-0.05%; cosolvent 0.5-1%; pre-phase transfer agent 1-3%; balance: water.

[0010] Preferably, the composition is as follows: oil phase 25-28%; oil-soluble surfactant 12-14%; water-soluble surfactant 7-9%; acrylamide 20-24%; anionic functional monomer 2-4%; cationic functional monomer 0.1-0.4%; crosslinking agent 0.0004-0.0007%; photoinitiator 0.01-0.03%; cosolvent 0.6-0.8%; pre-phase transfer agent 1.5-2.5%; balance being water.

[0011] The oil phase is selected from one of white oil, naphtha, and liquid paraffin.

[0012] The oil-soluble surfactant is selected from one of sorbitan monostearate, sorbitan monooleate, and sorbitan monopalmitate.

[0013] The water-soluble surfactant is selected from one of the following: polyoxyethylene sorbitan monostearate, polyoxyethylene dehydrated sorbitan monooleate, octylphenol polyoxyethylene ether, nonylphenol polyoxyethylene ether, castor oil polyoxyethylene ether, and fatty alcohol polyoxyethylene ether.

[0014] The anionic functional monomer is selected from one of sodium 2-acrylamido-2-methylpropanesulfonate, sodium allyl sulfonate, and sodium styrene sulfonate.

[0015] The cationic functional monomer is selected from one of methacryloyloxyethyltrimethylammonium chloride and acryloyloxyethyltrimethylammonium chloride.

[0016] The crosslinking agent is selected from one of N,N-methylenebisacrylamide, polyethylene glycol diacrylate, and pentaerythritol triacrylate.

[0017] The photoinitiator is selected from one of 2-hydroxy-2-methyl-1-phenylpropanone, 2-methyl-2-(4-morpholino)-1-[4-(methylthio)phenyl]-1-propanone, benzoin dimethyl ether, benzoin ethyl ether, 2,4-dihydroxybenzophenone, and isopropylthioxanthrone.

[0018] The co-solvent is selected from benzene, toluene, and xylene.

[0019] The pre-phase transfer agent is a water-soluble surfactant with an HLB value ≥ 9, including: alkanolamide, sodium fatty alcohol polyoxyethylene ether sulfate, fatty alcohol polyoxyethylene ether AEO-7 / AEO-9, nonylphenol polyoxyethylene ether NP-10, and octylphenol polyoxyethylene ether OP-10.

[0020] The preparation of a uniformly expanding nanogel material in high-salinity oilfield formation water includes the following steps:

[0021] Step 1) Add the formulated amounts of acrylamide, anionic functional monomer, cationic functional monomer, and crosslinking agent to water, stir to dissolve until the solution is clear, and obtain a monomer solution;

[0022] Step 2) Add the prescribed amount of oil phase to the container, then add the prescribed amounts of oil-soluble surfactant and water-soluble surfactant, and stir to mix evenly;

[0023] Step 3) While stirring, add the monomer solution to the oil phase prepared in Step 2), stirring at a speed of 500-800 rpm, and continue dispersing until the system becomes transparent. Maintain the system conductivity at 0-1 μS / cm by adjusting the ratio of oil-soluble surfactant to water-soluble surfactant. 2 ;

[0024] Step 4) Dissolve the photoinitiator in the amount of cosolvent specified in the formula, add it to the system that has been stirred and dispersed evenly and transparently in Step 3), and continue stirring and dispersing for 10-20 minutes.

[0025] Step 5) Using a constant flow peristaltic pump, the system prepared in Step 4) is dynamically and continuously delivered to the S-type glass photoreactor at a rate of 1-5 mL / min. At the same time, a high-pressure mercury lamp with a power of 1000W-2000W is used to continuously irradiate the system with UV light above the photoreactor. As the system passes through the glass photoreactor, the photoinitiator decomposes in light, and the monomer aqueous solution polymerizes. The heat generated by the polymerization is dissipated in time through heat exchange with the cooling water bath (10-30℃) around the glass photoreactor. The highest temperature of the photoreaction is 15℃-40℃, and the polymerization of the system is always kept in the low temperature range.

[0026] Step 6) Add the pre-phase transfer agent of the prescribed amount to the photopolymerized system of Step 5) while stirring, and continue stirring and dispersing for 10-20 minutes.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] The present invention provides a uniformly expanding nanogel material in high-salt formation water of oilfields. It introduces sulfonate anion groups with excellent salt resistance into the microgel and adds cationic functional monomers. The interaction between the anions and cations restricts the hydration and expansion of sulfonate ions and inhibits the hydrolysis of polyacrylamide to a certain extent. This slows down the initial expansion of the microgel in high-salt formation water and allows it to pass smoothly through the narrow pore throats near the wellbore and enter the deep reservoir with relatively high residual oil content.

[0029] Furthermore, the added cationic functional monomers contain ester groups. Under the influence of temperature and high-salinity formation water, these ester groups can gradually hydrolyze and break bonds, generating small molecules of methacrylic acid and quaternary ammonium salts. This process transforms cations into anions. Simultaneously, during hydrolysis, the cationic groups in the cationic functional monomers detach from the sulfonate anions, releasing anionic groups. The mutual repulsion between the anions causes the microgel to hydrate and expand. By controlling the addition amounts of cationic and anionic functional monomers, the microgel material can achieve uniform expansion in high-salinity formation water in oilfields, sealing and accumulating in deep formations. This causes subsequent water injection to redirect, displacing residual oil in deep formations and improving oil recovery.

[0030] Taking sodium 2-acrylamido-2-methylpropanesulfonate as the anionic functional monomer, N,N-methylenebisacrylamide as the crosslinking agent, and methacryloyloxyethyltrimethylammonium chloride as the cationic functional monomer as an example, the following is a schematic diagram of the free radical copolymerization reaction of acrylamide, anionic functional monomer, crosslinking agent, and cationic functional monomer, and the resulting microgel material undergoing ester bond hydrolysis and cationic group detachment in the high-temperature environment of the formation:

[0031]

[0032] This invention employs a one-step aqueous-monomer mixing reverse microemulsion and dynamic continuous UV photopolymerization method to prepare anionic and cationic functional monomers in a single step, while using a reverse microemulsion. Dynamic continuous UV photopolymerization effectively avoids the premature decomposition and inactivation of cationic functional groups caused by the high temperatures of traditional thermal polymerization. Through heat exchange between the S-shaped glass photoreactor and the surrounding cooling water bath, the entire polymerization process is carried out at low temperatures, ensuring the effectiveness of the functional components in the microgel. Simultaneously, the dynamic continuous photopolymerization process induces disturbance in the system, thereby preventing the aggregation of microgel particles. The microgel material prepared by photopolymerization is more uniform and has a narrower particle size distribution. This results in nanoscale microgel materials that can easily pass through near-wellbore zones and penetrate deep into oil reservoirs. Attached Figure Description

[0033] Figure 1 The infrared spectrum of the nano-microgel material prepared in Example 1;

[0034] Figure 2 This is a schematic diagram of the dynamic continuous photopolymerization experimental device used in an embodiment of the present invention. Detailed Implementation

[0035] Example 1

[0036] This embodiment provides a uniformly expanding nanogel material in high-salinity oilfield formation water, composed of the following substances by mass percentage:

[0037] The oil phase is white oil: 30%;

[0038] The oil-soluble surfactant is sorbitan monostearate: 15%;

[0039] The water-soluble surfactant is polyoxyethylene sorbitan monostearate: 9%;

[0040] Acrylamide: 20%;

[0041] The anionic functional monomer is sodium 2-acrylamido-2-methylpropanesulfonate: 5%;

[0042] The cationic functional monomer is methacryloyloxyethyltrimethylammonium chloride: 0.01%;

[0043] The crosslinking agent is N,N-methylenebisacrylamide: 0.0001%;

[0044] The photoinitiator is 0.005% 2-hydroxy-2-methyl-1-phenylpropanone;

[0045] The co-solvent is benzene: 0.5%;

[0046] The pre-phase transfer agent is alkanolamide: 1%;

[0047] The water is deionized: 19.4849%.

[0048] The preparation method includes the following steps:

[0049] Step 1) Add the formulated amounts of acrylamide, anionic functional monomer, cationic functional monomer, and crosslinking agent to water, stir to dissolve until the solution is clear, and obtain a monomer solution;

[0050] Step 2) Add the prescribed amount of oil phase to the container, then add the prescribed amounts of oil-soluble surfactant and water-soluble surfactant, and stir to mix evenly;

[0051] Step 3) While stirring, add the monomer solution to the oil phase prepared in Step 2), stirring at a speed of 500 rpm, and continue dispersing until the system becomes transparent, maintaining the system conductivity at 0 μS / cm. 2 ;

[0052] Step 4) Dissolve the photoinitiator in the amount of the formula-prescribed cosolvent, add it to the system that has been stirred and dispersed evenly and transparently in Step 3), and continue stirring and dispersing for another 10 minutes.

[0053] Step 5) Using a constant-flow peristaltic pump, the system prepared in Step 4) is dynamically and continuously delivered to the S-shaped glass photoreactor at a rate of 1 mL / min. Simultaneously, a 1000W high-pressure mercury lamp continuously irradiates the photoreactor with UV light. As the system passes through the glass photoreactor, the photoinitiator decomposes in light, and the monomer aqueous solution polymerizes. The heat generated during polymerization is dissipated promptly through heat exchange with a cooling water bath (10℃) surrounding the glass photoreactor. The maximum temperature of the photoreaction is 15℃, and the polymerization process is maintained within a low-temperature range (photopolymerization experimental setup such as...). Figure 2 (as shown);

[0054] Step 6) Add the pre-phase transfer agent of the prescribed amount to the photopolymerized system of Step 5) while stirring, and continue stirring and dispersing for 10 minutes.

[0055] The uniformly expanding nanogel material prepared in this embodiment, in formation water with a total salinity of 30,000 mg / L, has an initial average particle size of 171 nm in the aqueous phase. It can smoothly pass through the pore throat in the near-wellbore zone of the oilfield and enter the deep reservoir. Under a formation temperature of 80℃, it reaches its maximum expansion particle size in 5 days. The specific microgel particle size test results are shown in Table 1.

[0056] Table 1. Average particle size of microgels under different aging times.

[0057]

[0058] The average particle size of the microgels maintained a basically uniform growth rate of 5-20 nm / day.

[0059] The infrared spectrum of the uniformly expanding nano-microgel material prepared in the high-salinity formation water of the oilfield in this embodiment is as follows: Figure 1 As shown.

[0060] Example 2

[0061] This embodiment provides a uniformly expanding nanogel material in high-salinity oilfield formation water, composed of the following substances by mass percentage:

[0062] The oil phase is naphtha: 20%;

[0063] The oil-soluble surfactant is sorbitan monooleate: 9%;

[0064] The water-soluble surfactant is polyoxyethylene dehydrated sorbitan monooleate: 6%;

[0065] Acrylamide: 15%;

[0066] The anionic functional monomer is sodium allyl sulfonate: 1%;

[0067] The cationic functional monomer is acryloyloxyethyltrimethylammonium chloride: 0.5%

[0068] The crosslinking agent is polyethylene glycol diacrylate: 0.001%;

[0069] The photoinitiator was 0.05% 2-methyl-2-(4-morpholino)-1-[4-(methylthio)phenyl]-1-propanone;

[0070] The co-solvent is toluene: 1%;

[0071] The pre-phase transfer agent is sodium fatty alcohol polyoxyethylene ether sulfate: 3%.

[0072] The water is deionized: 44.449%.

[0073] The preparation method includes the following steps:

[0074] Step 1) Add the formulated amounts of acrylamide, anionic functional monomer, cationic functional monomer, and crosslinking agent to water, stir to dissolve until the solution is clear, and obtain a monomer solution;

[0075] Step 2) Add the prescribed amount of oil phase to the container, then add the prescribed amounts of oil-soluble surfactant and water-soluble surfactant, and stir to mix evenly;

[0076] Step 3) While stirring, add the monomer solution obtained in Step 1) to the oil phase prepared in Step 2), stirring at 800 rpm, and continue dispersing until the system becomes transparent, maintaining a system conductivity of 1 μS / cm. 2 ;

[0077] Step 4) Dissolve the photoinitiator in the amount of the formula-prescribed cosolvent, add it to the system that has been stirred and dispersed evenly and transparently in Step 3), and continue stirring and dispersing for another 20 minutes.

[0078] Step 5) Using a constant-flow peristaltic pump, the system prepared in Step 4) is dynamically and continuously delivered to the S-shaped glass photoreactor at a rate of 5 mL / min. Simultaneously, a 2000W high-pressure mercury lamp continuously irradiates the photoreactor with UV light. As the system passes through the glass photoreactor, the photoinitiator decomposes in the light, and the monomer aqueous solution polymerizes. The heat generated during polymerization is dissipated promptly through heat exchange with a cooling water bath (30℃) surrounding the glass photoreactor. The maximum temperature of the photoreaction is 40℃, and the polymerization process is maintained within a low-temperature range (photopolymerization experimental setup such as...). Figure 2 (as shown);

[0079] Step 6) Add the amount of pre-phase-transfer agent in the formula to the photopolymerized system in Step 5) while stirring, and continue stirring and dispersing for 20 minutes.

[0080] The uniformly expanding nanogel material prepared in this embodiment, in formation water with a total salinity of 120,000 mg / L, has an initial average particle size of 285 nm in the aqueous phase. It can smoothly pass through the pore throat in the near-wellbore zone of the oilfield and enter the deep reservoir. Under a formation temperature of 40℃, it reaches its maximum expansion particle size in 10 days. The specific microgel particle size test results are shown in Table 2.

[0081] Table 2. Average particle size of microgels under different aging times.

[0082]

[0083] The average particle size of the microgels maintained a basically uniform growth rate of 5-20 nm / day.

[0084] Example 3

[0085] This embodiment provides a uniformly expanding nanogel material in high-salinity oilfield formation water, prepared from the following substances by mass percentage:

[0086] The oil phase is liquid paraffin: 25%;

[0087] The oil-soluble surfactant is sorbitan monopalmitate: 13%;

[0088] The water-soluble surfactant is octylphenol polyoxyethylene ether: 8%;

[0089] Acrylamide: 25%;

[0090] The anionic functional monomer is sodium styrene sulfonate: 3%;

[0091] The cationic functional monomer is methacryloyloxyethyltrimethylammonium chloride: 0.1%;

[0092] The crosslinking agent is pentaerythritol triacrylate: 0.0005%;

[0093] The photoinitiator was benzoin dimethyl ether: 0.01%;

[0094] The co-solvent is xylene: 0.7%;

[0095] The pre-phase transfer agent is fatty alcohol polyoxyethylene ether AEO-7: 2%;

[0096] The water is deionized: 23.1895%.

[0097] The preparation method includes the following steps:

[0098] Step 1) Add the formulated amounts of acrylamide, anionic functional monomer, cationic functional monomer, and crosslinking agent to water, stir to dissolve until the solution is clear, and obtain a monomer solution;

[0099] Step 2) Add the prescribed amount of oil phase to the container, then add the prescribed amounts of oil-soluble surfactant and water-soluble surfactant, and stir to mix evenly;

[0100] Step 3) While stirring, add the monomer solution obtained in Step 1) to the oil phase prepared in Step 2), stirring at a speed of 600 rpm, and continue dispersing until the system becomes transparent, maintaining the system conductivity at 0.5 μS / cm. 2 ;

[0101] Step 4) Dissolve the photoinitiator in the amount of cosolvent specified in the formula, add it to the system that has been stirred and dispersed evenly and transparently in Step 3), and continue stirring and dispersing for another 15 minutes.

[0102] Step 5) Using a constant-flow peristaltic pump, the system prepared in Step 4) is dynamically and continuously delivered to the S-shaped glass photoreactor at a rate of 3 mL / min. Simultaneously, a 1500W high-pressure mercury lamp continuously irradiates the photoreactor with UV light. As the system passes through the glass photoreactor, the photoinitiator decomposes in the light, and the monomer aqueous solution polymerizes. The heat generated during polymerization is dissipated promptly through heat exchange with a cooling water bath (20℃) surrounding the glass photoreactor. The highest temperature of the photoreaction is 25℃, and the polymerization process is maintained within a low-temperature range (photopolymerization experimental setup such as...). Figure 2 (as shown);

[0103] Step 6) Add the pre-phase-transfer agent of the prescribed amount to the photopolymerized system of Step 5) while stirring, and continue stirring and dispersing for 15 minutes.

[0104] The uniformly expanding nanogel material prepared in this embodiment, in formation water with a total salinity of 80,000 mg / L, has an initial average particle size of 215 nm in the aqueous phase. It can smoothly pass through the pore throat in the near-wellbore zone of the oilfield and enter the deep reservoir. Under a formation temperature of 60℃, it reaches its maximum expansion particle size in 7 days. The specific microgel particle size test results are shown in Table 3.

[0105] Table 3. Average particle size of microgels under different aging times.

[0106]

[0107] The average particle size of the microgels maintained a basically uniform growth rate of 5-20 nm / day.

[0108] Example 4

[0109] This embodiment provides a uniformly expanding nanogel material in high-salinity oilfield formation water, prepared from the following substances by mass percentage:

[0110] The oil phase is white oil: 28%;

[0111] The oil-soluble surfactant is sorbitan monostearate: 15%;

[0112] The water-soluble surfactant is nonylphenol polyoxyethylene ether: 7%;

[0113] Acrylamide: 23%;

[0114] The anionic functional monomer is sodium 2-acrylamido-2-methylpropanesulfonate: 4%;

[0115] The cationic functional monomer is acryloyloxyethyltrimethylammonium chloride: 0.3%;

[0116] The crosslinking agent is N,N-methylenebisacrylamide: 0.0004%;

[0117] The photoinitiator is 2,4-dihydroxybenzophenone: 0.03%;

[0118] The co-solvent is toluene: 0.8%;

[0119] The pre-phase transfer agent is nonylphenol polyoxyethylene ether NP-10: 1%;

[0120] The water is deionized: 20.8696%.

[0121] The preparation method includes the following steps:

[0122] Step 1) Add the formulated amounts of acrylamide, anionic functional monomer, cationic functional monomer, and crosslinking agent to water, stir to dissolve until the solution is clear, and obtain a monomer solution;

[0123] Step 2) Add the prescribed amount of oil phase to the container, then add the prescribed amounts of oil-soluble surfactant and water-soluble surfactant, and stir to mix evenly;

[0124] Step 3) While stirring, add the monomer solution obtained in Step 1) to the oil phase prepared in Step 2), stirring at a speed of 700 rpm, and continue dispersing until the system becomes transparent, maintaining the system conductivity at 0.3 μS / cm. 2 ;

[0125] Step 4) Dissolve the photoinitiator in the amount of the formula-prescribed cosolvent, add it to the system that has been stirred and dispersed evenly and transparently in Step 3), and continue stirring and dispersing for 12 minutes.

[0126] Step 5) Using a constant-flow peristaltic pump, the system prepared in Step 4) is dynamically and continuously delivered to the S-shaped glass photoreactor at a rate of 4 mL / min. Simultaneously, a 1800W high-pressure mercury lamp continuously irradiates the photoreactor with UV light. As the system passes through the glass photoreactor, the photoinitiator decomposes in the light, and the monomer aqueous solution polymerizes. The heat generated during polymerization is dissipated promptly through heat exchange with a cooling water bath (25℃) surrounding the glass photoreactor. The highest temperature of the photoreaction is 32℃, and the polymerization process is maintained within a low-temperature range (photopolymerization experimental setup such as...). Figure 2 (as shown);

[0127] Step 6) Add the pre-phase transfer agent of the specified amount to the photopolymerized system of Step 5) while stirring, and continue stirring and dispersing for 12 minutes.

[0128] The uniformly expanding nanogel material prepared in this embodiment in high-salinity oilfield formation water has an initial average particle size of 162 nm in the aqueous phase. It can smoothly pass through the pore throat in the near-wellbore zone of the oilfield and enter the deep reservoir. Under the formation temperature of 70℃, it reaches the maximum expansion particle size in 6 days. The specific microgel particle size test results are shown in Table 4.

[0129] Table 4. Average particle size of microgels under different aging times.

[0130]

[0131] The average particle size of the microgels maintained a basically uniform growth rate of 5-20 nm / day.

[0132] Example 5

[0133] This embodiment provides a uniformly expanding nanogel material in high-salinity oilfield formation water, composed of the following substances by mass percentage:

[0134] The oil phase is liquid paraffin: 27%;

[0135] The oil-soluble surfactant is sorbitan monooleate: 15%;

[0136] The water-soluble surfactant is castor oil polyoxyethylene ether: 8%;

[0137] Acrylamide: 18%;

[0138] The anionic functional monomer is sodium allyl sulfonate: 2%;

[0139] The cationic functional monomer is methacryloyloxyethyltrimethylammonium chloride: 0.07%;

[0140] The crosslinking agent is polyethylene glycol diacrylate: 0.0007%;

[0141] The photoinitiator was isopropylthioxanthone: 0.02%;

[0142] The co-solvent is xylene: 0.7%;

[0143] The pre-phase transfer agent is octylphenol polyoxyethylene ether OP-10: 2%;

[0144] The water is deionized: 27.2093%.

[0145] Preparation method:

[0146] Step 1) Add the formulated amounts of acrylamide, anionic functional monomer, cationic functional monomer, and crosslinking agent to water, stir to dissolve until the solution is clear, and obtain a monomer solution;

[0147] Step 2) Add the prescribed amount of oil phase to the container, then add the prescribed amounts of oil-soluble surfactant and water-soluble surfactant, and stir to mix evenly;

[0148] Step 3) While stirring, add the monomer solution obtained in Step 1) to the oil phase prepared in Step 2), stirring at a speed of 500 rpm, and continue dispersing until the system becomes transparent, maintaining the system conductivity at 0.1 μS / cm. 2 ;

[0149] Step 4) Dissolve the photoinitiator in the amount of the formula-prescribed cosolvent, add it to the system that has been stirred and dispersed evenly and transparently in Step 3), and continue stirring and dispersing for another 10 minutes.

[0150] Step 5) Using a constant-flow peristaltic pump, the system prepared in Step 4) is dynamically and continuously delivered to the S-shaped glass photoreactor at a rate of 2 mL / min. Simultaneously, a 1000W high-pressure mercury lamp continuously irradiates the photoreactor with UV light. As the system passes through the glass photoreactor, the photoinitiator decomposes in light, and the monomer aqueous solution polymerizes. The heat generated during polymerization is dissipated promptly through heat exchange with a cooling water bath (12℃) surrounding the glass photoreactor. The highest temperature of the photoreaction is 18℃, and the polymerization process is maintained within a low-temperature range (photopolymerization experimental setup such as...). Figure 2 (as shown);

[0151] Step 6) Add the amount of pre-phase-transfer agent in the formula to the photopolymerized system in Step 5) while stirring, and continue stirring and dispersing for 20 minutes.

[0152] The uniformly expanding nanogel material prepared in this embodiment, in formation water with a total salinity of 100,000 mg / L, has an initial average particle size of 206 nm in the aqueous phase. It can smoothly pass through the pore throat in the near-wellbore zone of the oilfield and enter the deep reservoir. Under a formation temperature of 50℃, it reaches its maximum expansion particle size in 8 days. The specific microgel particle size test results are shown in Table 5.

[0153] Table 5. Average particle size of microgels under different aging times.

[0154]

[0155] The average particle size of the microgels maintained a basically uniform growth rate of 5-20 nm / day.

Claims

1. A nano-microgel material, characterized in that, The preparation method includes the following steps: S1: Acrylamide, anionic functional monomer, cationic functional monomer, and crosslinking agent are added to water to obtain a monomer solution; S2: Add oil-soluble surfactants and water-soluble surfactants to the oil phase to obtain a mixed oil phase; S3: Add the monomer solution described in S1 to the mixed oil phase described in S2 to obtain a homogeneous and transparent system; S4: Dissolve the photoinitiator with a co-solvent and add it to the homogeneous and transparent system described in S3 to obtain a mixed system; S5: The mixed system described in S4 is transported to a photoreactor and continuously irradiated with light to carry out the reaction, thereby obtaining a photopolymerization system; S6: Add the pre-phase-transfer agent to the photopolymerization system described in S5 to obtain nano-microgel materials.

2. The nano-microgel material according to claim 1, characterized in that, The anionic functional monomer is selected from one of sodium 2-acrylamido-2-methylpropanesulfonate, sodium allyl sulfonate, and sodium styrene sulfonate.

3. The nano-microgel material according to claim 1, characterized in that, The cationic functional monomer is selected from one of methacryloyloxyethyltrimethylammonium chloride and acryloyloxyethyltrimethylammonium chloride.

4. The nano-microgel material according to claim 1, characterized in that, The crosslinking agent is selected from one of N,N-methylenebisacrylamide, polyethylene glycol diacrylate, and pentaerythritol triacrylate.

5. The nano-microgel material according to claim 1, characterized in that, The amounts of reactants involved, by mass percentage, are as follows: Oil phase 20-30%; oil-soluble surfactant 9-15%; water-soluble surfactant 6-10%; acrylamide 15-25%; anionic functional monomer 1-5%; cationic functional monomer 0.01-0.5%; crosslinking agent 0.0001-0.001%; ​​photoinitiator 0.005-0.05%; cosolvent 0.5-1%; pre-phase transfer agent 1-3%; balance: water.

6. The nano-microgel material according to claim 1, characterized in that, The amounts of reactants involved, by mass percentage, are as follows: Oil phase 25-28%; oil-soluble surfactant 12-14%; water-soluble surfactant 7-9%; acrylamide 20-24%; anionic functional monomer 2-4%; Cationic functional monomer 0.1-0.4%; crosslinking agent 0.0004-0.0007%; photoinitiator 0.01-0.03%; cosolvent 0.6-0.8%; pre-phase transfer agent 1.5-2.5%; balance water.

7. The nano-microgel material according to claim 1, characterized in that, The oil phase is selected from one of white oil, naphtha, and liquid paraffin.

8. The nano-microgel material according to claim 1, characterized in that, The oil-soluble surfactant is selected from one of sorbitan monostearate, sorbitan monooleate, and sorbitan monopalmitate.

9. The nano-microgel material according to claim 1, characterized in that, The water-soluble surfactant is selected from one of the following: polyoxyethylene sorbitan monostearate, polyoxyethylene dehydrated sorbitan monooleate, octylphenol polyoxyethylene ether, nonylphenol polyoxyethylene ether, castor oil polyoxyethylene ether, and fatty alcohol polyoxyethylene ether.

10. The nano-microgel material according to claim 1, characterized in that, The photoinitiator is selected from one of 2-hydroxy-2-methyl-1-phenylpropanone, 2-methyl-2-(4-morpholino)-1-[4-(methylthio)phenyl]-1-propanone, benzoin dimethyl ether, benzoin ethyl ether, 2,4-dihydroxybenzophenone, and isopropylthioxanthrone.

11. The nano-microgel material according to claim 1, characterized in that, The co-solvent is selected from benzene, toluene, and xylene.

12. The nano-microgel material according to claim 1, characterized in that, The pre-phase transfer agent is a water-soluble surfactant with an HLB value ≥ 9.

13. The nano-microgel material according to claim 12, characterized in that, The water-soluble surfactant with an HLB value ≥ 9 is selected from one of the following: alkanolamide, sodium lauryl alcohol polyoxyethylene ether sulfate, lauryl alcohol polyoxyethylene ether AEO-7, lauryl alcohol polyoxyethylene ether AEO-9, nonylphenol polyoxyethylene ether NP-10, and octylphenol polyoxyethylene ether OP-10.

14. The nano-microgel material according to claim 1, characterized in that, During the addition of S3 to the monomer solution, the conductivity of the system remains at 0-1 μs / cm. 2 .

15. The nano-microgel material according to claim 1, characterized in that, The S5 mixing system is delivered at a rate of 1-5 mL / min.

16. The nano-microgel material according to claim 1, characterized in that, The reaction temperature of S5 is 15-40℃.

17. A regulating drive system, characterized in that, It includes the nanomicrogel material according to any one of claims 1-16.

18. The application of the nano-microgel material as described in any one of claims 1-16 or the modulating drive system as described in claim 17 in oil fields.

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