阅读说明：本技术 新型阴阳复合柔性聚合物微球及制备方法 (Novel negative and positive composite flexible polymer microsphere and preparation method thereof ) 是由 苏智青 李应成 沙鸥 夏燕敏 孙慧 许汇 朱益兴 于 2019-10-25 设计创作，主要内容包括：本发明涉及一种新型阴阳复合柔性聚合物微球及制备方法,主要解决现有聚合物微球深度调剖能力及可控性不足的问题,通过采用一种阴阳复合柔性聚合物微球,包括作为内核的聚合物I和作为外壳的聚合物II；其中,所述聚合物I分子链中含有烯酰胺结构单元、阳离子醚化剂结构单元、非离子单体结构单元和长效交联结构单元,所述聚合物II分子链中含有丙烯酰胺结构单元、阴离子单体结构单元、非离子单体结构单元、长效交联结构单元和短期交联结构单元的技术方案,较好地解决了该问题,可用于油田开发中的深度调剖。(The invention relates to a novel yin-yang composite flexible polymer microsphere and a preparation method thereof, which mainly solve the problem that the existing polymer microsphere is insufficient in deep profile control capability and controllability; the polymer I molecular chain contains an acrylamide structural unit, a cationic etherifying agent structural unit, a nonionic monomer structural unit and a long-term crosslinking structural unit, and the polymer II molecular chain contains an acrylamide structural unit, an anionic monomer structural unit, a nonionic monomer structural unit, a long-term crosslinking structural unit and a short-term crosslinking structural unit.)

1. A yin-yang composite flexible polymer microsphere comprises a polymer I as an inner core and a polymer II as an outer shell; the polymer I molecular chain contains an acrylamide structural unit, a cationic etherifying agent structural unit, a nonionic monomer structural unit and a long-term crosslinking structural unit, and the polymer II molecular chain contains an acrylamide structural unit, an anionic monomer structural unit, a nonionic monomer structural unit, a long-term crosslinking structural unit and a short-term crosslinking structural unit.

2. The yin-yang composite flexible polymer microsphere according to claim 1, wherein the yin-yang composite flexible polymer microsphere is obtained by reacting a reaction system comprising the following components in parts by weight:

a kernel part:

(1)5-25 parts of acrylamide;

(2)1-10 parts of a cationic etherifying agent;

(3)1-10 parts of a nonionic monomer;

(4)0.01-0.5 part of long-acting cross-linking agent;

housing portion:

(1)5-25 parts of acrylamide;

(2)1-25 parts of an anionic monomer;

(3)1-10 parts of a nonionic monomer;

(4)0.0001-0.01 part of long-acting crosslinking agent.

(5)0.1-0.5 part of short-term crosslinking agent.

3. The negative-positive composite flexible polymer microsphere according to claim 1 or 2, wherein the anionic monomer is at least one selected from acrylic acid, methacrylic acid, sodium vinyl sulfonate, p-vinyl benzene sulfonic acid, maleic acid, fumaric acid, vinyl benzene sulfonic acid, allyl benzene sulfonic acid, 2-acrylamido-2-methyl propane sulfonic acid and/or alkali metal salts and ammonium salts thereof.

4. The negative-positive composite flexible polymer microsphere according to claim 1 or 2, wherein the cationic etherifying agent is at least one selected from the group consisting of epoxypropyltrimethylammonium chloride, epoxypropylbenzyltrimethylammonium chloride, epoxypropylethoxytrimethylammonium chloride, epoxypropyltrimethylammonium chloride-terminated polyethylene glycol; the non-ionic monomer is at least one selected from methacrylamide, dimethylacrylamide, diethylacrylamide, hydroxymethyl acrylamide, hydroxyethyl acrylamide, dimethylaminopropyl methacrylamide, hydroxymethyl methacrylate, hydroxyethyl methacrylate, dimethylaminoethyl methacrylate and vinyl pyrrolidone.

5. The yin-yang composite flexible polymer microspheres according to claim 1 or 2, wherein the long-acting crosslinking agent is selected from at least one of methylenebisacrylamide, divinylbenzene, N '-methylenebismethacrylamide, N' -m-phenylenedimaleimide; the short-term crosslinking agent is selected from at least one of diallyl phthalate, diallyl cyanoethyl acetate, polyethylene glycol diacrylate, ethylene glycol diacrylate and pentaerythritol triacrylate.

6. The yin-yang composite flexible polymer microsphere according to claim 1 or 2, wherein the reaction system further comprises:

(6)0.0001-0.0005 part of initiator;

(7)10-50 parts of deionized water;

(8)50-90 parts of an oil solvent;

(9) 0.01-0.3 parts of disodium ethylene diamine tetraacetate;

(10)1-10 parts of an emulsifier;

further preferably: the initiator is preferably at least one selected from the group consisting of persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide, benzoyl peroxide, azobisisobutyronitrile, azobisisovaleronitrile, azobisisoheptonitrile, dimethyl azobisisobutyrate, azobisisobutylamidine hydrochloride, 2 '-azo [2- (2-imidazolin-2-yl) propane ] dihydrochloride, azobis (2, 5-dimethyl-6-carboxy) hexanenitrile, and 4, 4' -azobis (4-cyanovaleric acid).

7. The yin-yang composite flexible polymer microsphere according to claim 6, wherein the oil solvent is at least one selected from aliphatic hydrocarbon, aromatic hydrocarbon, mineral oil or vegetable oil; further preferably: the aliphatic hydrocarbon is preferably at least one of cyclohexane, hexane, heptane, octane and isooctane; the aromatic hydrocarbon is preferably at least one selected from the group consisting of benzene, toluene, ethylbenzene, xylene, and cumene; the mineral oil is preferably at least one of liquid paraffin, white oil, gasoline, diesel oil and kerosene; the vegetable oil is preferably at least one selected from peanut oil, soybean oil, sunflower oil and castor oil.

8. The yin-yang composite flexible polymer microsphere according to claim 6, wherein the emulsifier is at least one selected from sorbitan oleate, sorbitan stearate, sorbitan palmitate, sorbitan laurate, fatty alcohol polyoxypropylene polyoxyethylene ether represented by formula (i), (ii), aromatic alcohol polyoxypropylene polyoxyethylene ether represented by formula (iii), fatty acid polyoxypropylene polyoxyethylene ester represented by formula (iii), and fatty amine polyoxypropylene polyoxyethylene ether represented by formula (iv):

wherein R is₁、R₂And R₃Each independently selected from C₁～C₂₈A hydrocarbon group of (a); r₄And R₅From hydrogen atoms or C₁～C₂₈And R is a hydrocarbon group of₄And R₅Cannot be simultaneously hydrogen atoms; m is selected from 0-30; n is 1-40.

9. A method for preparing the yin-yang composite flexible polymer microspheres according to any one of claims 1 to 8, which adopts an emulsion polymerization method or a suspension polymerization method.

10. The method for preparing yin-yang composite flexible polymer microspheres according to claim 9, wherein suspension polymerization is adopted, comprising the following steps:

1) preparation of the inner core part:

a) preparing a water solution with the pH value of 5-10 by using required amounts of acrylamide monomers, anionic monomers, nonionic monomers, long-acting cross-linking agents and water;

b) dissolving required amount of emulsifier in oil solvent to obtain solution, and controlling temperature to be not more than 25 deg.C;

c) b, preparing a required amount of initiator into an aqueous solution, and adding the aqueous solution into the aqueous solution prepared in the step a to obtain a reaction solution;

d) c, adding the reaction solution obtained in the step c into the solution prepared in the step b, and stirring to remove oxygen to obtain a reaction system;

e) raising the temperature of the reaction system to be more than 40 ℃, preferably 50-70 ℃, and carrying out reaction;

f) after the reaction is finished, keeping the temperature at more than 40 ℃, preferably 50-70 ℃, adding a cationic etherifying agent, and reacting at constant temperature for not less than 2 hours to obtain an outer cationized polymer microsphere inner core;

2) preparation of the crust part:

g) preparing a water solution with the pH value of 5-10 by using required amounts of acrylamide monomers, anionic monomers, nonionic monomers, long-acting cross-linking agents, short-term cross-linking agents and water;

h) preparing a required amount of initiator into an aqueous solution, and adding the aqueous solution into the aqueous solution prepared in the step g to obtain a reaction solution;

i) adding the reaction solution obtained in the step g into an outer-layer cationized polymer microsphere inner core system under stirring, and stirring for deoxidizing; and then raising the temperature to more than 40 ℃, preferably 50-70 ℃, carrying out reaction, and cooling after the reaction temperature rise is finished to obtain the yin-yang composite flexible polymer microsphere product.

Technical Field

The invention relates to a micron-sized core-shell structured yin-yang composite flexible polymer microsphere synthesized by a micro-suspension polymerization method. In particular to a micron-sized anion-cation composite flexible polymer microsphere, wherein a cation inner core is obtained by treating a non-ionic surface with a cation etherifying agent, an anion shell is degradable, and the micron-sized anion-cation composite flexible polymer microsphere can be used as a depth profile control agent in tertiary oil recovery.

Background

Petroleum is blood of modern industry, is an important source of energy of modern society, and plays a vital role in economic development. At present, crude oil in China has high dependence on import, and domestic oil fields face a series of problems due to long-term development, and the yield is gradually reduced, so that the safety of national energy strategy is severely restricted. After long-term water injection exploitation of various domestic oil fields, the comprehensive water content of a large amount of medium-high permeability oil reservoirs is more than 90%. In addition, long-term water injection development causes the dispersion of underground residual oil and the complex oil-water distribution condition, so that the water consumption per ton of oil is increased rapidly, the invalid injection proportion is increased, and the development benefit of the oil field is reduced. In the case of a victory field, the extremely high water consumption zone occupies about 15% of the reservoir volume, but consumes 90% of the injected water.

For oil reservoirs in a high water-cut period, profile control and water shutoff are key in the technology for further improving the recovery efficiency. The effective profile control plugging technology can plug underground large pore passages, change the flow field direction, reduce the invalid injection proportion, effectively improve the utilization rate of the oil displacement agent, further improve the recovery ratio and reduce the injection and production cost. The water-soluble polymer gel profile control agent is one of important additives for profile control of oil fields. The polymer microspheres have small particle size, good injectability and stable chemical structure, and are widely applied to deep profile control. The traditional polymer microsphere mainly takes anion as a main component, and larger particles are formed by later water absorption expansion to block the large pore channel. Because the particle size of the microspheres is small, the time required for reaching equilibrium swelling is short, and therefore, the depth profile control capability of the microspheres in a stratum is insufficient.

The polymer microsphere with the cation core-shell polymer microsphere is one of the solutions, the cation core-shell polymer microsphere with the cation core-shell polymer microsphere is formed by constructing the cation core-shell structure of the microsphere in the earlier patent disclosed by the subject matter group, the agglomeration among the microspheres and the adsorption of the microsphere and the stratum are inhibited by the degradable anion shell in the initial stage, so that the microsphere can reach the deep part of the stratum, after the shell is degraded, the exposed cation core can endow the microsphere with strong aggregation capability and adsorption capability with the stratum, and the deep profile control effect is achieved by plugging a large pore channel in the deep part of the stratum.

However, the prior art still has certain problems, for example, the cationic polymer is mainly obtained by copolymerization of acrylate derivatives, the price of the cationic monomer is high, and the temperature resistance and salt resistance of the side group are insufficient due to hydrolysis of ester groups in the cationic monomer. Secondly, the cation groups in the cation core mainly act on the groups on the outer layer of the core, and the cation groups in the core have no effect on the aggregation of the microsphere and the adsorption capacity of the microsphere and the stratum, so that the cation monomer has low utilization rate on the aspect of improving the performance of the microsphere. Meanwhile, since cationic monomers have a lower reactivity ratio than acrylamide, the amount of cationic monomers added and the conversion rate during polymerization are also limited, further limiting the cationization degree of the core.

Cationic etherifying agents are commonly used for cationization of macromolecules, and epoxy groups in the cationic etherifying agents are reacted with active groups on macromolecular side chains to introduce cationic groups on the macromolecular side chains. As reported in the literature, Luzhen et al obtain cationic polyacrylamide with high relative molecular mass by treating polymerized high molecular weight polyacrylamide with cationic etherifying agent. The structure formed by the reaction is an ether bond which is more stable relative to ester groups, so that the long-term aging performance is better, and the stability is better.

Disclosure of Invention

One of the technical problems to be solved by the invention is to solve the problem that the existing polymer microsphere is insufficient in depth profile control capability and controllability. Therefore, the invention provides a novel yin-yang composite polymer microsphere with a clear core-shell structure, and the characteristics that the aggregation capacity among microspheres is suddenly increased after underground migration for a certain time and the plugging capacity is obviously enhanced are realized by adjusting the degradation time of a microsphere shell and the agglomeration capacity of a microsphere core.

The second technical problem to be solved by the invention is to provide a preparation method of the yin-yang composite polymer microsphere corresponding to the first technical problem.

In order to solve the problems, the synthesis of the cation inner core adopts a method different from that of a copolymerized cation monomer, the surface of the microsphere inner core is treated by a cation etherifying agent after the non-ion inner core is formed, so that cation side groups enriched on the surface of the microsphere inner core are formed, and meanwhile, the cation side groups obtained by the method have better structural thermal stability and more excellent microsphere performance.

In order to solve one of the problems, the technical scheme adopted by the invention is as follows: a yin-yang composite flexible polymer microsphere comprises a polymer I as an inner core and a polymer II as an outer shell; the polymer I molecular chain contains an acrylamide structural unit, a cationic etherifying agent structural unit, a nonionic monomer structural unit and a long-term crosslinking structural unit, and the polymer II molecular chain contains an acrylamide structural unit, an anionic monomer structural unit, a nonionic monomer structural unit, a long-term crosslinking structural unit and a short-term crosslinking structural unit.

In the technical scheme, the polymer II of the shell can be degraded, and the degradation time is controllable; the polymer I of the core has strong adsorption and aggregation capabilities and is effective for a long time.

In the above technical scheme, the yin-yang composite flexible polymer microsphere is preferably obtained by reacting a reaction system comprising the following components in parts by weight:

a kernel part:

(1)5-25 parts of acrylamide;

(2)1-10 parts of a cationic etherifying agent;

(3)1-10 parts of a nonionic monomer;

(4)0.01-0.5 part of long-acting cross-linking agent;

housing portion:

(1)5-25 parts of acrylamide;

(2)1-25 parts of an anionic monomer;

(3)1-10 parts of a nonionic monomer;

(4)0.0001-0.01 part of long-acting crosslinking agent.

(5)0.1-0.5 part of short-term crosslinking agent.

In the above technical solution, the anionic monomer is preferably at least one selected from acrylic acid, methacrylic acid, sodium vinylsulfonate, p-vinylbenzenesulfonic acid, maleic acid, fumaric acid, vinylbenzenesulfonic acid, allylsulfonic acid, allylbenzenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, and/or alkali metal salts and ammonium salts thereof.

In the above technical solution, the cationic etherifying agent is preferably at least one selected from the group consisting of glycidyl trimethyl ammonium chloride, glycidyl benzyl trimethyl ammonium chloride, glycidyl ethoxy trimethyl ammonium chloride, and glycidyl trimethyl ammonium chloride-terminated polyethylene glycol; the nonionic monomer is preferably at least one selected from methacrylamide, dimethylacrylamide, diethylacrylamide, methylolacrylamide, hydroxyethylacrylamide, dimethylaminopropyl methacrylamide, methylolmethacrylate, hydroxyethyl methacrylate, dimethylaminoethyl methacrylate and vinylpyrrolidone.

In the above technical solution, the long-acting cross-linking agent is preferably at least one selected from methylenebisacrylamide, divinylbenzene, N '-methylenebismethacrylamide, and N, N' -m-phenylenebismaleimide; the short-term crosslinking agent is preferably at least one of diallyl phthalate, diallyl cyanoacetate, polyethylene glycol diacrylate, ethylene glycol diacrylate and pentaerythritol triacrylate.

In the above technical solution, the reaction system preferably further comprises:

(6)0.0001-0.0005 part of initiator;

(7)10-50 parts of deionized water;

(8)50-90 parts of an oil solvent;

(9) 0.01-0.3 parts of disodium ethylene diamine tetraacetate;

(10)1-10 parts of an emulsifier.

In the above technical scheme, the initiator is preferably at least one selected from persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide, benzoyl peroxide, azobisisobutyronitrile, azobisisovaleronitrile, azobisisoheptonitrile, dimethyl azobisisobutyrate, azobisisobutylamidine hydrochloride, 2 '-azo [2- (2-imidazolin-2-yl) propane ] dihydrochloride, azobis (2, 5-dimethyl-6-carboxyl) hexanenitrile, and 4, 4' -azobis (4-cyanopentanoic acid).

In the above technical solution, the oil solvent is preferably at least one selected from aliphatic hydrocarbon, aromatic hydrocarbon, mineral oil or vegetable oil; the aliphatic hydrocarbon is preferably at least one of cyclohexane, hexane, heptane, octane and isooctane; the aromatic hydrocarbon is preferably at least one selected from the group consisting of benzene, toluene, ethylbenzene, xylene, and cumene; the mineral oil is preferably at least one of liquid paraffin, white oil, gasoline, diesel oil and kerosene; the vegetable oil is preferably at least one selected from peanut oil, soybean oil, sunflower oil and castor oil.

In the above technical solution, the emulsifier is preferably at least one selected from fatty alcohol polyoxypropylene polyoxyethylene ether represented by formula (i), aromatic alcohol polyoxypropylene polyoxyethylene ether represented by formula (ii), fatty acid polyoxypropylene polyoxyethylene ester represented by formula (iii), fatty amine polyoxypropylene polyoxyethylene ether represented by formula (iv), sorbitan oleate, sorbitan stearate, sorbitan palmitate, and sorbitan laurate:

wherein R is₁、R₂And R₃Each independently selected from C₁～C₂₈A hydrocarbon group of (a); r₄And R₅From hydrogen atoms or C₁～C₂₈And R is a hydrocarbon group of₄And R₅Cannot be simultaneously hydrogen atoms; m is selected from 0-30; n is 1-40.

In order to solve the second problem, the invention adopts the following technical scheme: a method for preparing the yin-yang composite flexible polymer microsphere according to any one of the above technical solutions, which adopts an emulsion polymerization method or a suspension polymerization method.

In the above technical solution, the preparation method preferably adopts suspension polymerization, and comprises the following steps:

1) preparation of the inner core part:

a) preparing a water solution with the pH value of 5-10 by using required amounts of acrylamide monomers, anionic monomers, nonionic monomers, long-acting cross-linking agents and water;

b) dissolving required amount of emulsifier in oil solvent to obtain solution, and controlling temperature to be not more than 25 deg.C;

c) b, preparing a required amount of initiator into an aqueous solution, and adding the aqueous solution into the aqueous solution prepared in the step a to obtain a reaction solution;

d) c, adding the reaction solution obtained in the step c into the solution prepared in the step b, and stirring to remove oxygen to obtain a reaction system;

e) raising the temperature of the reaction system to be more than 40 ℃, preferably 50-70 ℃, and carrying out reaction;

f) after the reaction is finished, keeping the temperature at more than 40 ℃, preferably 50-70 ℃, adding a cationic etherifying agent, and reacting at constant temperature for not less than 2 hours to obtain an outer cationized polymer microsphere inner core;

2) preparation of the crust part:

g) preparing a water solution with the pH value of 5-10 by using required amounts of acrylamide monomers, anionic monomers, nonionic monomers, long-acting cross-linking agents, short-term cross-linking agents and water;

h) preparing a required amount of initiator into an aqueous solution, and adding the aqueous solution into the aqueous solution prepared in the step g to obtain a reaction solution;

i) adding the reaction solution obtained in the step g into an outer-layer cationized polymer microsphere inner core system under stirring, and stirring for deoxidizing; and then raising the temperature to more than 40 ℃, preferably 50-70 ℃, carrying out reaction, and cooling after the reaction temperature rise is finished to obtain the yin-yang composite flexible polymer microsphere product.

In the above technical scheme, the pH value in the step a) is preferably 7-10.

In the above technical solution, the stirring speed in step d) is preferably 200-500r/min, and the stirring time is preferably not less than 30 min.

In the above technical solution, in the step g), the pH value is preferably 6-10.

In the above technical solution, in the step i), the stirring speed is preferably 200-.

The polyacrylamide polymer microsphere obtained by the technical scheme of the invention has lower plugging rate in the early aging stage and higher plugging rate in the later aging stage, and has better depth profile control effect compared with the polymer microsphere and non-core-shell structure microsphere obtained by the traditional diene cross-linking agent.

The yin-yang composite flexible polymer microspheres obtained by the technical scheme of the invention are dispersed microspheres at the initial stage of injection into a stratum, meanwhile, the adsorption to the stratum is low, the shell is gradually degraded under the action of hot oxygen along with the migration in the stratum, after the electropositive core is exposed, aggregates with larger sizes are formed among the microspheres through electrostatic action, and then large pore canals are blocked in the deep part of the stratum, and meanwhile, the time for the occurrence of the deep profile control capability is controllable through regulating and controlling the structure of the shell, so that the yin-yang composite flexible polymer microspheres can be used for oilfield exploitation as a deep profile control process with higher operability.

In the cation inner core formed by the cation etherifying agent, the cation side group is an ether bond structure, and compared with the cation structure of which the side group is an ester group obtained by the traditional copolymerization, the cation structure of the microsphere obtained by the invention is more stable, and the temperature resistance and salt resistance are better. Meanwhile, the cation structure is obtained by surface treatment after the formation of the inner core, so that cation groups are enriched on the surface of the inner core, and the utilization rate of the cation side group is higher in the aspect of improving the agglomeration and adsorption capacity of the microsphere.

The micron-sized negative and positive composite flexible polymer microsphere is synthesized by adopting micro-suspension polymerization, and the problems of low reactivity ratio, poor aging resistance of a cationic side group, high price of a cationic monomer and the like in the traditional cationic polyacrylamide microsphere synthesis process by adopting cationic monomer copolymerization are solved. Meanwhile, the surface enrichment of cationic groups in the cationic inner core of the core-shell microsphere is realized, and the utilization rate of the cationic groups is further improved. The cationic structure in the polymer microsphere is not generated by the copolymerization of the traditional cationic monomer of acrylate or acrylamide derivatives, but is polymerized into a nonionic acrylamide core, and then a cationic etherifying agent is adopted to carry out post-treatment on the surface of the core to form a cationic layer, so that the cationic structure unit is only enriched on the surface of the microsphere core, and a large number of cationic groups do not exist in the core. The utilization rate of the cationic groups which can obviously adsorb the stratum and endow strong aggregation among the microspheres with the method is greatly improved. Meanwhile, the microspheres also have low-adsorption degradable shells, after the microspheres are transported in an underground oil reservoir for a certain time, the shells are degraded, the cation cores are exposed, and then the purpose of deep profile control is achieved due to strong plugging capability of the microspheres and the stratum and the aggregation among the microspheres. The composite flexible polymer microsphere comprises the following structural units, namely an acrylamide structural unit, an anionic monomer structural unit, a cationic etherifying agent structural unit, a nonionic monomer structural unit, a long-acting crosslinking structural unit and a short-term crosslinking structural unit. The long-acting crosslinking structure unit, the short-term crosslinking agent structure unit and the polymer chain form a crosslinking structure. Wherein the long-acting crosslinking structural unit, the short-term crosslinking agent structural unit, the acrylamide structural unit, the anionic monomer structural unit and the nonionic monomer structural unit form a degradable shell structure on the surface of the microsphere. The long-acting cross-linking structural unit, the acrylamide structural unit, the anion monomer structural unit, the cation etherifying agent structural unit and the nonionic monomer structural unit form a long-acting core structure together, and the method is applicable to deep profile control in oilfield development.

By adopting the technical scheme of the invention, the obtained yin-yang composite flexible polymer microspheres have long-acting stability, have better blocking rate after long-term aging, and can still keep more than 92.5 percent of blocking rate after aging for 120 days at 70 ℃, thereby obtaining better technical effect.

The invention is further illustrated by the following examples.

Detailed Description

[ example 1 ]

25 parts of acrylamide, 0.5 part of disodium ethylene diamine tetraacetate, 1 part of tert-butyl acrylamide and 0.2 part of methylene bisacrylamide are dissolved in 30 parts of deionized water to prepare a solution, and the pH value is adjusted to be between 6 and 10. 0.0125 part of azobisisobutyl ether hydrochloride is dissolved in 1 part of deionized water to prepare aqueous solution, and then the aqueous solution is added into the monomer solution to be uniformly stirred.

6 parts of sorbitan oleate and 4 parts of fatty alcohol-polyoxyethylene ether are dissolved in 50 parts of 5# white oil to prepare an oil solution, and the oil solution is added into a reaction kettle and stirred at the speed of 200 r/min. Slowly adding the above water solution into the reaction kettle under stirring, continuously stirring for 30min, controlling the temperature in the kettle to be 20 ℃ in water bath, and introducing nitrogen to remove oxygen.

Continuously stirring, heating the water bath at the speed of 200r/min until the temperature in the kettle is 50 ℃, and keeping the temperature of the water bath constant until the spontaneous temperature in the kettle is increased. After the reaction is finished, controlling the constant temperature in the reaction kettle at 70 ℃ through water bath, dropwise adding 1 part of epoxypropyltrimethylammonium chloride into the reaction kettle, and reacting for 2 hours at the constant temperature to obtain the polymer microsphere core with the cationized outer layer. Taking a small amount of reaction system, precipitating and washing with ethanol for three times, and drying for later use.

20 parts of acrylamide, 2 parts of 2-acrylamide-2-methylpropanesulfonic acid, 1 part of tert-butyl acrylamide, 0.002 part of methylene bisacrylamide and 0.018 part of polyethylene glycol diacrylate are dissolved in 20 parts of deionized water to prepare a solution, and the pH value is adjusted to be between 6 and 10. 0.0075 parts of azobisisobutyl ether hydrochloride is dissolved in 1 part of deionized water to prepare a water solution, and then the water solution is added into the monomer solution to be uniformly stirred. Slowly adding the aqueous solution into a reaction system after the polymerization of the core part is finished, continuously stirring at the speed of 200r/min, introducing nitrogen to remove oxygen, and heating the temperature in the kettle to 50 ℃ through a water bath. And continuously stirring until the spontaneous temperature rise in the kettle is finished, controlling the water bath temperature to be 50 ℃, and discharging after the temperature in the kettle is reduced to be the same as the water bath temperature, thus obtaining the target polymer microsphere product.

The dry powder of the microspheres purified after the first step of the reaction in example 1 was dispersed in deionized water, and the zeta potential thereof was measured as # 1 in table 1. The microsphere emulsion finally obtained in example 1 was dispersed in simulated formation water with a mineralization of 6000mg/L, aged at 70 ℃ for various times, and then injected into a 2000md core, and the plugging rate was measured, as shown in # 1 in Table 2. As shown in # 1 in Table 1, in example 1, only 1 part of the cationic etherifying agent was added, and the zeta potential of the core was equivalent to that of the microspheres obtained by copolymerizing 2.5 parts of the cationic monomer used in the comparative example. This is because in the method of the present invention, the cationic etherifying agent is gathered on the surface of the inner core, and the cationic side group is gathered on the surface, which results in higher utilization rate of the cationic group. Meanwhile, as shown in table 2, the plugging rates of the microsphere samples obtained in examples 1, 2 and 3# and the microsphere samples obtained in comparative examples 1, 2 and 3# after aging for 60 days are equivalent, and both the plugging rates are obtained from the aggregation capability of the microspheres and the adsorption capability of the microspheres to rocks, which are endowed by the exposed cation cores after the shells are degraded. In contrast, the plugging rate of the sample obtained in the example is slightly higher. However, when the aging test is continued for 120 days, the difference shows, because the cationic monomer side group adopted in the comparative example contains degradable ester group, after the continuous aging degradation, the cationic side group falls off from the main chain structure of the microsphere, so that the aggregation capability and the adsorption capability to rocks of the microsphere are reduced, and the sample obtained in the embodiment is prepared by adopting the cationic etherifying agent with more stable molecular structure, so that the cationic side group has better heat resistance, and has better blocking rate after long-term aging.

[ example 2 ]

25 parts of acrylamide, 0.5 part of disodium ethylene diamine tetraacetate, 1 part of tert-butyl acrylamide and 0.2 part of methylene bisacrylamide are dissolved in 30 parts of deionized water to prepare a solution, and the pH value is adjusted to be between 6 and 10. 0.0125 part of azobisisobutyl ether hydrochloride is dissolved in 1 part of deionized water to prepare aqueous solution, and then the aqueous solution is added into the monomer solution to be uniformly stirred.

6 parts of sorbitan oleate and 4 parts of fatty alcohol-polyoxyethylene ether are dissolved in 50 parts of 5# white oil to prepare an oil solution, and the oil solution is added into a reaction kettle and stirred at the speed of 200 r/min. Slowly adding the above water solution into the reaction kettle under stirring, continuously stirring for 30min, controlling the temperature in the kettle to be 20 ℃ in water bath, and introducing nitrogen to remove oxygen.

Continuously stirring, heating the water bath at the speed of 200r/min until the temperature in the kettle is 50 ℃, and keeping the temperature of the water bath constant until the spontaneous temperature in the kettle is increased. After the reaction is finished, controlling the constant temperature in the reaction kettle at 70 ℃ through water bath, dropwise adding 2.5 parts of epoxypropyltrimethylammonium chloride into the reaction kettle, and reacting for 2 hours at the constant temperature to obtain the polymer microsphere core with the cationized outer layer. Taking a small amount of reaction system, precipitating and washing with ethanol for three times, and drying for later use.

20 parts of acrylamide, 2 parts of 2-acrylamide-2-methylpropanesulfonic acid, 1 part of tert-butyl acrylamide, 0.001 part of methylene bisacrylamide and 0.019 part of polyethylene glycol diacrylate are dissolved in 20 parts of deionized water to prepare a solution, and the pH value is adjusted to be between 6 and 10. 0.0075 parts of azobisisobutyl ether hydrochloride is dissolved in 1 part of deionized water to prepare a water solution, and then the water solution is added into the monomer solution to be uniformly stirred. Slowly adding the aqueous solution into a reaction system after the polymerization of the core part is finished, continuously stirring at the speed of 200r/min, introducing nitrogen to remove oxygen, and heating the temperature in the kettle to 50 ℃ through a water bath. And continuously stirring until the spontaneous temperature rise in the kettle is finished, controlling the water bath temperature to be 50 ℃, and discharging after the temperature in the kettle is reduced to be the same as the water bath temperature, thus obtaining the target polymer microsphere product.

The dry powder of the microspheres purified after the first step of the reaction in example 2 was dispersed in deionized water, and the zeta potential of the dry powder was measured and shown in # 2 in table 1. The microsphere emulsion finally obtained in example 2 was dispersed in simulated formation water with a mineralization of 6000mg/L, aged at 70 ℃ for various times, and then injected into a 2000md core, and the plugging rate was measured, as shown in # 2 in Table 2. As shown in # 2 of Table 1, in example 2, 2.5 parts of a cationic etherifying agent was added, and the zeta potential of the core was larger than that of the microsphere obtained by copolymerizing 5 parts of the cationic monomer used in comparative example 3. This is because in the method of the present invention, the cationic etherifying agent is gathered on the surface of the inner core, and the cationic side group is gathered on the surface, which results in higher utilization rate of the cationic group. Meanwhile, the plugging rate law is the same as that of the previous microsphere sample shown in table 2, the plugging rate of the microsphere sample obtained in example 2 is equivalent to that of the microsphere samples obtained in comparative examples 1, 2 and 3# after aging for 60 days, but the plugging rate of the microsphere sample obtained in example 2 is better when the aging experiment is continued for 120 days.

[ example 3 ]

25 parts of acrylamide, 0.5 part of disodium ethylene diamine tetraacetate, 1 part of tert-butyl acrylamide and 0.2 part of methylene bisacrylamide are dissolved in 30 parts of deionized water to prepare a solution, and the pH value is adjusted to be between 6 and 10. 0.0125 part of azobisisobutyl ether hydrochloride is dissolved in 1 part of deionized water to prepare aqueous solution, and then the aqueous solution is added into the monomer solution to be uniformly stirred.

6 parts of sorbitan oleate and 4 parts of fatty alcohol-polyoxyethylene ether are dissolved in 50 parts of 5# white oil to prepare an oil solution, and the oil solution is added into a reaction kettle and stirred at the speed of 200 r/min. Slowly adding the above water solution into the reaction kettle under stirring, continuously stirring for 30min, controlling the temperature in the kettle to be 20 ℃ in water bath, and introducing nitrogen to remove oxygen.

Continuously stirring, heating the water bath at the speed of 200r/min until the temperature in the kettle is 50 ℃, and keeping the temperature of the water bath constant until the spontaneous temperature in the kettle is increased. After the reaction is finished, controlling the constant temperature in the reaction kettle at 70 ℃ through water bath, dropwise adding 5 parts of epoxypropyltrimethylammonium chloride into the reaction kettle, and reacting for 2 hours at the constant temperature to obtain the polymer microsphere core with the cationized outer layer. Taking a small amount of reaction system, precipitating and washing with ethanol for three times, and drying for later use.

Dissolving 20 parts of acrylamide, 2 parts of 2-acrylamide-2-methylpropanesulfonic acid, 1 part of tert-butyl acrylamide, 0.0006 part of methylene bisacrylamide and 0.0194 part of polyethylene glycol diacrylate in 20 parts of deionized water to prepare a solution, and adjusting the pH value to be between 6 and 10. 0.0075 parts of azobisisobutyl ether hydrochloride is dissolved in 1 part of deionized water to prepare a water solution, and then the water solution is added into the monomer solution to be uniformly stirred. Slowly adding the aqueous solution into a reaction system after the polymerization of the core part is finished, continuously stirring at the speed of 200r/min, introducing nitrogen to remove oxygen, and heating the temperature in the kettle to 50 ℃ through a water bath. And continuously stirring until the spontaneous temperature rise in the kettle is finished, controlling the water bath temperature to be 50 ℃, and discharging after the temperature in the kettle is reduced to be the same as the water bath temperature, thus obtaining the target polymer microsphere product.

The dry powder of the microspheres purified after the first step of the reaction in example 3 was dispersed in deionized water, and the zeta potential thereof was measured as indicated by # 3 in table 1. The microsphere emulsion finally obtained in example 3 was dispersed in simulated formation water with a mineralization of 6000mg/L, aged at 70 ℃ for various times, and then injected into a 2000md core, and the plugging rate was measured, as shown in # 3 in Table 2. As shown in # 3 of Table 1, in example 3, 5 parts of the cationic etherifying agent was added, and the zeta potential of the core was much larger than that of the microspheres obtained by copolymerizing 5 parts of the cationic monomer used in comparative example 3. This is because in the method of the present invention, the cationic etherifying agent is gathered on the surface of the inner core, and the cationic side group is gathered on the surface, which results in higher utilization rate of the cationic group. Meanwhile, the plugging rate rule is the same as that described above, and as shown in table 2, the microsphere sample obtained in example 3 has the highest cationic group content on the surface of the core and good thermal stability of the cationic side group, so that the microsphere sample has the best plugging capability after aging for 60 days and 120 days.

[ COMPARATIVE EXAMPLE 1 ]

25 parts of acrylamide, 1 part of methacryloyloxyethyl trimethyl ammonium chloride, 0.5 part of ethylene diamine tetraacetic acid disodium, 1 part of tert-butyl acrylamide and 0.2 part of methylene bisacrylamide are dissolved in 30 parts of deionized water to prepare a solution, and the pH value is adjusted to be between 6 and 10. 0.0125 part of azobisisobutyl ether hydrochloride is dissolved in 1 part of deionized water to prepare aqueous solution, and then the aqueous solution is added into the monomer solution to be uniformly stirred.

6 parts of sorbitan oleate and 4 parts of fatty alcohol-polyoxyethylene ether are dissolved in 50 parts of 5# white oil to prepare an oil solution, and the oil solution is added into a reaction kettle and stirred at the speed of 200 r/min. Slowly adding the above water solution into the reaction kettle under stirring, continuously stirring for 30min, controlling the temperature in the kettle to be 20 ℃ in water bath, and introducing nitrogen to remove oxygen.

Continuously stirring, heating the water bath at the speed of 200r/min until the temperature in the kettle is 50 ℃, and keeping the temperature of the water bath constant until the spontaneous temperature in the kettle is increased. Taking a small amount of reaction system, precipitating and washing with ethanol for three times, and drying for later use.

20 parts of acrylamide, 2 parts of 2-acrylamide-2-methylpropanesulfonic acid, 1 part of tert-butyl acrylamide, 0.002 part of methylene bisacrylamide and 0.018 part of polyethylene glycol diacrylate are dissolved in 20 parts of deionized water to prepare a solution, and the pH value is adjusted to be between 6 and 10. 0.0075 parts of azobisisobutyl ether hydrochloride is dissolved in 1 part of deionized water to prepare a water solution, and then the water solution is added into the monomer solution to be uniformly stirred. Slowly adding the aqueous solution into a reaction system after the polymerization of the core part is finished, continuously stirring at the speed of 200r/min, introducing nitrogen to remove oxygen, and heating the temperature in the kettle to 50 ℃ through a water bath. And continuously stirring until the spontaneous temperature rise in the kettle is finished, controlling the water bath temperature to be 50 ℃, and discharging after the temperature in the kettle is reduced to be the same as the water bath temperature, thus obtaining the target polymer microsphere product.

The dry powder of the microspheres purified after the first step of the reaction in comparative example 1 was dispersed in deionized water, and the zeta potential thereof was measured as # 4 in table 1. The microsphere emulsion finally obtained in comparative example 1 was dispersed in simulated formation water with a mineralization of 6000mg/L, aged at 70 ℃ for various times, and then injected into a 2000md core, and the plugging rate was measured, as shown in # 4 in Table 2. As shown in # 4 in Table 1, in comparative example 1 in which 1 part of the cationic monomer was added, the zeta potential was 11.3mV, which was much lower than that of the product obtained in example 1 in which the same cationic etherifying agent was added. At the same time, the blocking rate after 120 days of aging is also less than for the corresponding example 1 sample due to degradation of the cationic side groups after long-term aging.

[ COMPARATIVE EXAMPLE 2 ]

25 parts of acrylamide, 2.5 parts of methacryloyloxyethyl trimethyl ammonium chloride, 0.5 part of ethylene diamine tetraacetic acid disodium, 1 part of tert-butyl acrylamide and 0.2 part of methylene bisacrylamide are dissolved in 30 parts of deionized water to prepare a solution, and the pH value is adjusted to be between 6 and 10. 0.0125 part of azobisisobutyl ether hydrochloride is dissolved in 1 part of deionized water to prepare aqueous solution, and then the aqueous solution is added into the monomer solution to be uniformly stirred.

6 parts of sorbitan oleate and 4 parts of fatty alcohol-polyoxyethylene ether are dissolved in 50 parts of 5# white oil to prepare an oil solution, and the oil solution is added into a reaction kettle and stirred at the speed of 200 r/min. Slowly adding the above water solution into the reaction kettle under stirring, continuously stirring for 30min, controlling the temperature in the kettle to be 20 ℃ in water bath, and introducing nitrogen to remove oxygen.

Continuously stirring, heating the water bath at the speed of 200r/min until the temperature in the kettle is 50 ℃, and keeping the temperature of the water bath constant until the spontaneous temperature in the kettle is increased. Taking a small amount of reaction system, precipitating and washing with ethanol for three times, and drying for later use.

20 parts of acrylamide, 2 parts of 2-acrylamide-2-methylpropanesulfonic acid, 1 part of tert-butyl acrylamide, 0.002 part of methylene bisacrylamide and 0.018 part of polyethylene glycol diacrylate are dissolved in 20 parts of deionized water to prepare a solution, and the pH value is adjusted to be between 6 and 10. 0.0075 parts of azobisisobutyl ether hydrochloride is dissolved in 1 part of deionized water to prepare a water solution, and then the water solution is added into the monomer solution to be uniformly stirred. Slowly adding the aqueous solution into a reaction system after the polymerization of the core part is finished, continuously stirring at the speed of 200r/min, introducing nitrogen to remove oxygen, and heating the temperature in the kettle to 50 ℃ through a water bath. And continuously stirring until the spontaneous temperature rise in the kettle is finished, controlling the water bath temperature to be 50 ℃, and discharging after the temperature in the kettle is reduced to be the same as the water bath temperature, thus obtaining the target polymer microsphere product.

The dry powder of the microspheres purified after the first step of the reaction in comparative example 2 was dispersed in deionized water, and the zeta potential thereof was measured as # 5 in Table 1. The microsphere emulsion finally obtained in comparative example 2 was dispersed in simulated formation water with a mineralization of 6000mg/L, aged at 70 ℃ for various times, and then injected into a 2000md core, and the plugging rate was measured, as shown in # 5 in Table 2. As shown in # 5 in Table 1, in comparative example 2, 2.5 parts of cationic monomer was added, and the zeta potential was only 17.6mV, which is lower than that of the product obtained by adding only 1 part of cationic etherifying agent in example 1, because the cationic groups are concentrated on the surface of the microsphere core after the cationic etherifying agent is treated in the later stage, and the cationic monomer obtained by copolymerization is uniformly distributed in the whole microsphere. Meanwhile, due to the degradation of the cation side group after long-term aging, the plugging rate after 120 days of aging is less than that of the corresponding sample in example 2, and due to the fact that the higher the cation content is, the more serious the degradation is, the plugging rate after 120 days of aging is even lower than that of the sample obtained in comparative example 1.

[ COMPARATIVE EXAMPLE 3 ]

25 parts of acrylamide, 5 parts of methacryloyloxyethyl trimethyl ammonium chloride, 0.5 part of ethylene diamine tetraacetic acid disodium, 1 part of tert-butyl acrylamide and 0.2 part of methylene bisacrylamide are dissolved in 30 parts of deionized water to prepare a solution, and the pH value is adjusted to be between 6 and 10. 0.0125 part of azobisisobutyl ether hydrochloride is dissolved in 1 part of deionized water to prepare aqueous solution, and then the aqueous solution is added into the monomer solution to be uniformly stirred.

6 parts of sorbitan oleate and 4 parts of fatty alcohol-polyoxyethylene ether are dissolved in 50 parts of 5# white oil to prepare an oil solution, and the oil solution is added into a reaction kettle and stirred at the speed of 200 r/min. Slowly adding the above water solution into the reaction kettle under stirring, continuously stirring for 30min, controlling the temperature in the kettle to be 20 ℃ in water bath, and introducing nitrogen to remove oxygen.

Continuously stirring, heating the water bath at the speed of 200r/min until the temperature in the kettle is 50 ℃, and keeping the temperature of the water bath constant until the spontaneous temperature in the kettle is increased. Taking a small amount of reaction system, precipitating and washing with ethanol for three times, and drying for later use.

20 parts of acrylamide, 2 parts of 2-acrylamide-2-methylpropanesulfonic acid, 1 part of tert-butyl acrylamide, 0.002 part of methylene bisacrylamide and 0.018 part of polyethylene glycol diacrylate are dissolved in 20 parts of deionized water to prepare a solution, and the pH value is adjusted to be between 6 and 10. 0.0075 parts of azobisisobutyl ether hydrochloride is dissolved in 1 part of deionized water to prepare a water solution, and then the water solution is added into the monomer solution to be uniformly stirred. Slowly adding the aqueous solution into a reaction system after the polymerization of the core part is finished, continuously stirring at the speed of 200r/min, introducing nitrogen to remove oxygen, and heating the temperature in the kettle to 50 ℃ through a water bath. And continuously stirring until the spontaneous temperature rise in the kettle is finished, controlling the water bath temperature to be 50 ℃, and discharging after the temperature in the kettle is reduced to be the same as the water bath temperature, thus obtaining the target polymer microsphere product.

The dry powder of the microspheres purified after the first step of the reaction in comparative example 3 was dispersed in deionized water, and the zeta potential thereof was measured as # 6 in Table 1. The microsphere emulsion finally obtained in comparative example 3 was dispersed in simulated formation water with a mineralization of 6000mg/L, aged at 70 ℃ for various times, and then injected into a 2000md core, and the plugging rate was measured, as shown in # 6 in Table 2. As shown in # 6 in Table 1, in comparative example 3, 5 parts of cationic monomer was added, and the zeta potential was only 22.4mV, which is lower than that of the product obtained by adding only 2.5 parts of cationic etherifying agent in example 2, because the cationic groups are concentrated on the surface of the microsphere core after the cationic etherifying agent treatment, and the cationic monomer obtained by copolymerization is uniformly distributed throughout the microsphere. Meanwhile, due to the degradation of the cation side group after long-term aging, the plugging rate after 120 days of aging is smaller than that of the corresponding sample in example 3, and because the cation content is the highest, the degradation is the heaviest, and the plugging rate after 120 days of aging is the lowest.

TABLE 1 zeta potential of the inner core of the polymeric microspheres obtained in examples and comparative examples

Numbering	1	2	3	4	5	6
							Zeta potential mV	18.2	28.8	39.1	11.3	17.6	22.4

TABLE 2 TABLE 1 blocking rate of the polymeric microspheres obtained in examples and comparative examples after long-term aging