CN111087537B - Multiple cross-linked core-shell polymer microsphere, profile control agent, and preparation method and application thereof - Google Patents

Multiple cross-linked core-shell polymer microsphere, profile control agent, and preparation method and application thereof Download PDF

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CN111087537B
CN111087537B CN201811235043.2A CN201811235043A CN111087537B CN 111087537 B CN111087537 B CN 111087537B CN 201811235043 A CN201811235043 A CN 201811235043A CN 111087537 B CN111087537 B CN 111087537B
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core
agent
profile control
water
linking agent
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CN111087537A (en
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夏燕敏
郭艳
姜建伟
苏智青
许汇
王兰
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China Petroleum and Chemical Corp
Sinopec Shanghai Research Institute of Petrochemical Technology
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Sinopec Shanghai Research Institute of Petrochemical Technology
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    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08FMACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F220/00Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
    • C08F220/02Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
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    • C09K8/508Compositions based on water or polar solvents containing organic compounds macromolecular compounds
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    • C09K8/88Compositions based on water or polar solvents containing organic compounds macromolecular compounds
    • C09K8/887Compositions based on water or polar solvents containing organic compounds macromolecular compounds containing cross-linking agents
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    • C09K2208/00Aspects relating to compositions of drilling or well treatment fluids
    • C09K2208/12Swell inhibition, i.e. using additives to drilling or well treatment fluids for inhibiting clay or shale swelling or disintegrating

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Abstract

The invention relates to a multi-crosslinking core-shell polymer microsphere, a profile control agent, a flooding agent, a preparation method and application thereof, and mainly solves the problems that in the prior art, the polymer microsphere is mainly of a homogeneous structure, the type of a used crosslinking agent is single, only one chemical crosslinking agent is generally introduced, and the microsphere can expand to a certain extent but has poor profile control plugging property on a medium-high permeability reservoir. The invention adopts a multi-crosslinked core-shell polymer microsphere, which comprises a polymer I inner core and a polymer II outer shell; the polymer I and the polymer II respectively and independently comprise an inorganic cross-linking agent structural unit and an organic cross-linking agent structural unit in the molecule, so that the problem is well solved, and the polymer I and the polymer II can be used for the field application of the oil field for improving the recovery ratio.

Description

Multiple cross-linked core-shell polymer microsphere, profile control agent, and preparation method and application thereof
Technical Field
The invention relates to a multi-crosslinked core-shell polymer microsphere, a profile control agent, a preparation method and application thereof.
Background
Oil well water production is a common problem existing in the current oil field development, in particular to an old oil field developed by long-term water injection. Because of the heterogeneity of oil deposit and the difference of oil and water viscosity, the injected water is easy to enter into high permeability strip or crack and bypass the medium and low permeability strip, causing the oil and water to rush and finger along the high permeability layer or crack between the water injection well and the production well, causing the production well to be flooded prematurely, the oil production is reduced, the water content is increased, thereby reducing the sweep coefficient of the injected water and causing the low or no use of the medium and low permeability layer. The wave coefficient of injected water is improved, so that the middle and low permeable layers which are not active or have poorer utilization degree can be utilized, the water drive development effect is improved, and the water control and oil stabilization are realized, which is one of the primary tasks of the water drive oil field. The method can work from two aspects to reduce the water output of the oil well, on one hand, the high permeability layer or the crack is plugged from the water injection well, the water absorption surface of the water injection well is adjusted, the injected water is reduced to protrude into the oil well along the high permeability layer or the crack, the injected water is forced to change the flow direction and enter the medium and low permeability layer, so that the sweep coefficient of the injected water is improved, the water flooding development effect is improved, and the work is called as the profile control of the water injection well; on the other hand, the water outlet layer of the oil well is blocked, and the liquid production profile is adjusted, which is called oil well water blocking.
The pre-crosslinked polyacrylamide particle deep profile control technology can solve the technical problems of non-gelling possibility, difficult preparation and injection, incapability of realizing slug treatment, poor temperature resistance and salt resistance and the like of an underground crosslinking system. Meanwhile, in the implementation process of the technology, the strength and the particle size distribution of the plugging agent are monitored and adjusted through construction, so that the defect caused by unclear understanding of large pores in the stratum can be overcome. The polymer microsphere belongs to the class with smaller particle size in pre-crosslinked acrylamide polymer particles, and has the following advantages as a recognized deep profile control agent: the microsphere can meet the requirements of 'getting in and getting out and getting blocked' at the pore throat part for blocking a water flow channel, can expand when meeting water, does not change when meeting oil, and is a selective blocking agent; the microsphere expansion layer is continuously diluted and peeled off after being washed by injected water for a long time, and finally, oil and water are produced by an oil well, so that pollution and damage to the stratum can be avoided, and a special treatment fluid is not needed to treat the profile control water well in the later stage. The polymer microsphere is prepared by respectively adopting inverse microemulsion, inverse emulsion or inverse suspension polymerization according to the requirements of the particle size from nano level, submicron level to micron level, and some functional monomers are introduced according to the requirements of temperature resistance and salt resistance to improve the performance, but the adopted cross-linking agents are single in variety, diene monomers such as N, N-Methylene Bisacrylamide (MBA), ethylene diacrylate and the like are mostly adopted, and the diene monomers can be polymerized with the monomers such as acrylamide and the like to form a network structure, so that the polymer microsphere is insoluble in water and can absorb a large amount of water, and has certain strength and elasticity. However, the strength and water-swelling property of the crosslinked polymer formed by the crosslinking agent are in contradiction, and cannot be enhanced simultaneously.
In recent years, much research is carried out on the aspect of research on polyacrylamide microsphere profile control and flooding agents in China, and a plurality of colleges and research institutions make better progress and achievement on the aspects of preparation of polyacrylamide microspheres and tertiary oil recovery and oil displacement application, so that polymer microsphere emulsions with various sizes from nano-scale, submicron-scale to micron-scale are prepared, but most of the obtained polymer microsphere structures applied on site are homogeneous, the types of crosslinking agents are single, and the solid content is low; the preparation process of the core-shell structure microspheres reported in a few documents is complex, most researches are focused on researches on reaction mechanism, dynamics, characterization and the like, the basic physical properties such as molecular weight, particle size and the like of the polymer are paid more attention, and few factors which directly influence the application such as the stability of the polymer microspheres under oil reservoir conditions, the expansion performance of the microspheres and the like are considered or the research results are not ideal.
Disclosure of Invention
One of the technical problems to be solved by the invention is that the expansion performance, elasticity and heat-resistant stability of the polymer microsphere cannot be simultaneously enhanced due to the fact that the strength and the water absorption expansion performance of the polymer microsphere are in conflict in the prior art, and the multiple-crosslinked core-shell polymer microsphere is provided and overcomes the conflict between the strength and the water absorption expansion performance of the polymer microsphere in the prior art.
The second technical problem to be solved by the invention is to provide a multiple cross-linked core-shell polymer microsphere profile control and flooding agent corresponding to the first technical problem, which well solves the problem that the expansion performance, elasticity and heat-resistant stability of polymer microspheres cannot be simultaneously enhanced due to the contradiction between the strength and the water absorption expansion performance of the polymer microspheres in the profile control and flooding agent in the prior art, overcomes the contradiction between the strength and the water absorption expansion performance of the polymer microspheres in the prior art, and has the advantage of excellent microsphere expansion performance, elasticity and heat-resistant stability.
The third technical problem to be solved by the invention is to provide a preparation method of the multi-crosslinked core-shell polymer microsphere profile control and flooding agent corresponding to the second technical problem, which adopts a reverse emulsion polymerization method to introduce different organic and inorganic crosslinking agents into monomers of a microsphere core or a microsphere shell respectively, so that the core and the shell of the microsphere have controllable expansion rate and better strength, and a long-term effective profile control effect is generated on a medium-high permeability oil reservoir.
The fourth technical problem to be solved by the invention is to provide an application method of the multi-crosslinked core-shell polymer microsphere profile control and flooding agent in oil fields, which is used for solving the second technical problem.
In order to solve one of the technical problems, the invention adopts the following technical scheme: a multiple cross-linked core-shell polymeric microsphere comprising a polymer I core and a polymer II shell; the molecules of the polymer I and the polymer II respectively and independently comprise an inorganic cross-linking agent structural unit and an organic cross-linking agent structural unit.
In the above technical solution, the organic cross-linking agent preferably contains an organic compound having an active functional group, and more preferably, the organic compound having an active functional group is preferably selected from one or more of N, N-methylene bisacrylamide, polyethylene glycol diacrylate, dimethylaminoethyl acrylate, aldehydes having two or more aldehyde groups, trimethylolpropane trimethacrylate, and pentaerythritol triacrylate.
In the above technical solution, the inorganic cross-linking agent is preferably selected from at least one of metal ion salts or compounds, metal ion-containing modified nanomontmorillonite and material containing silicon hydroxyl groups, more preferably the metal ion salts or compounds are selected from alkali metal or alkaline earth metal ion salts or compounds, such as magnesium oxide, the metal ion-containing modified nanomontmorillonite is preferably selected from metal ion-containing organic amine or organic ammonium modified nanomontmorillonite, such as calcium-containing group, sodium-calcium group, lithium-based group, magnesium-based group, aluminum-based metal ion-containing organic ammonium or organic amine modified nanomontmorillonite, and the material containing silicon hydroxyl groups is preferably selected from silica and/or silica sol.
In the technical scheme, the polymer I preferably contains an acrylamide unit and a comonomer I unit in a molecule; the polymer II preferably contains acrylamide units and comonomer II units in the molecule; further preferably: the comonomer I and the comonomer II are independently and randomly selected from one or more than two of nonionic water-soluble monomers, anionic monomers and cationic monomers; more preferably: the nonionic water-soluble monomer is preferably one or more selected from methacrylamide, N-isopropylacrylamide, N-dimethylacrylamide, N-diethylacrylamide, N-methylolacrylamide, N-vinylformamide, N-vinylacetamide, N-vinylpyridine and N-vinylpyrrolidone; the anionic monomer is preferably selected from one or more of 2-acrylamido-2-methylpropanesulfonic acid, acrylic acid, methacrylic acid, itaconic acid, vinylbenzenesulfonic acid, vinylsulfonic acid and/or water-soluble alkali metal, alkaline earth metal and ammonium salt thereof, and the cationic monomer is preferably selected from one or more of dimethyldiallylammonium chloride, acryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride and 2-acrylamido-2-methylpropyltrimethylammonium chloride.
In the above technical solution, the mass ratio of the inorganic cross-linking agent structural unit to the organic cross-linking agent structural unit in the molecule of the polymer I is preferably 1: 1-10: 1; the mass ratio of the inorganic cross-linking agent structural unit to the organic cross-linking agent structural unit in the molecule of the polymer II is preferably 1: 1-20: 1.
in the technical scheme, the initial particle size of the core-shell structure polymer microsphere is preferably 300-1000 nm.
In order to solve the second technical problem, the invention adopts the technical scheme that: a multiple crosslinked core-shell polymer microsphere profile control and flooding agent comprises the core-shell polymer microsphere in any one of the technical schemes for solving the technical problems.
In the above technical scheme, the modifying and flooding agent is preferably an emulsion, and further preferably further comprises an oil phase, a water phase and an emulsifier; more preferably: the content of the core-shell structure polymer microspheres is preferably more than 35% in percentage by mass of the profile control agent; the content of the emulsifier is 2-10%; the mass ratio of the oil phase to the water phase is 1: 1-1: 3. In order to solve the third technical problem, the invention adopts the technical scheme that: a preparation method of a core-shell polymer microsphere profile control and flooding agent comprises the following steps:
(a) uniformly mixing an oil-soluble solvent and a main emulsifier to form an oil phase;
(b) uniformly mixing acrylamide, a comonomer I, a co-emulsifier and a cross-linking agent I in water to prepare a water phase I with the pH value of 3-8; uniformly mixing acrylamide, a comonomer II, a co-emulsifier and a cross-linking agent II in water to prepare a water phase II with the pH value of 3-8, wherein the mass ratio of the water phase I to the water phase II is 1: 9-9: 1;
(c) preparing an emulsion from the water phase I and the oil phase, deoxidizing, adopting a redox initiator, controlling the adding speed of a reducing agent so that the heating speed is less than or equal to 1 ℃/min, and keeping the reaction temperature at the highest temperature of less than or equal to 50 ℃, and then keeping the temperature to continue reacting for at least 0.5 hour after the reaction temperature reaches the highest peak to obtain the core emulsion of the core-shell polymer microsphere profile control and flooding agent;
(d) in the presence of an azo initiator, adding a water phase II into the nuclear emulsion heated to the initiation temperature of the azo initiator, controlling the adding speed of the water phase II to keep the polymerization temperature stable, and finishing the reaction after the reaction is carried out for at least 3 hours to obtain the core-shell polymer microsphere profile control and flooding agent;
wherein the amount of the oil-soluble solvent is 20-50 parts by weight; the total using amount of the water phase I and the water phase II is 30-80 parts, and the mass percentage of the monomers in the corresponding water phase I and the water phase II is 40-70%; the dosage of the cross-linking agent I and the cross-linking agent II is 0.05-4 parts independently, the cross-linking agent I and the cross-linking agent II both comprise an inorganic cross-linking agent and an organic cross-linking agent independently, and the mass ratio of the inorganic cross-linking agent to the organic cross-linking agent in the cross-linking agent I is 1: 1-10: 1; the mass ratio of the inorganic cross-linking agent to the organic cross-linking agent in the cross-linking agent II is 1: 1-20: 1; the total dosage of the main emulsifier and the auxiliary emulsifier is 2-10 parts.
In the above technical solution, it is further preferable that: the content of the core-shell structure polymer microspheres is preferably more than 35% in percentage by mass of the profile control agent.
In the above embodiment, the oil-soluble solvent is preferably at least one selected from aliphatic hydrocarbons, aromatic hydrocarbons and halogenated hydrocarbons, and more preferably one or a mixture of two or more selected from toluene, xylene, isoparaffins, naphthenes and paraffins (e.g., a mixture of petroleum ether, white oil, kerosene, etc.); the hydrophilic-lipophilic balance value of the composite emulsifier consisting of the main emulsifier and the auxiliary emulsifier is preferably 3-9, and further preferably the auxiliary emulsifier is preferably selected from alcohols or salts, and the dosage of the composite emulsifier accounts for 1-30 w.t% of the total mass of the main emulsifier and the auxiliary emulsifier.
In the above technical scheme, the comonomer I and the comonomer II are independently and optionally selected from at least one of a nonionic water-soluble monomer, an anionic monomer and/or a cationic monomer; more preferably: the non-ionic water-soluble monomer is preferably one or more selected from methacrylamide, N-isopropylacrylamide, N-dimethylacrylamide, N-diethylacrylamide, N-methylolacrylamide, N-vinylformamide, N-vinylacetamide, N-vinylpyridine and N-vinylpyrrolidone, the anionic monomer is preferably one or more selected from 2-acrylamido-2-methylpropanesulfonic acid, acrylic acid, methacrylic acid, itaconic acid, vinylbenzenesulfonic acid, vinylsulfonic acid and/or water-soluble alkali metal, alkaline earth metal and ammonium salt thereof, the cationic monomer is preferably selected from dimethyldiallylammonium chloride, acryloyloxyethyltrimethyl ammonium chloride, methacryloyloxyethyltrimethylammonium chloride and 2-acrylamido-2-methylpropyltrimethyl ammonium chloride One or more than two of (1).
In the above technical solution, the organic cross-linking agent is preferably selected from organic compounds containing active functional groups, and more preferably, the organic compounds containing active functional groups are preferably selected from one or more of N, N-methylene bisacrylamide, polyethylene glycol diacrylate, dimethylaminoethyl acrylate, aldehydes containing two or more aldehyde groups, trimethylolpropane trimethacrylate and pentaerythritol triacrylate; the inorganic crosslinking agent is preferably selected from at least one of metal ion salts or compounds, metal ion-containing modified nanomontmorillonite and hydroxyl-containing substances, further preferably the metal ion salts or compounds are selected from alkali metal or alkaline earth metal ion salts or compounds, such as magnesium oxide, the metal ion-containing modified nanomontmorillonite is preferably selected from metal ion-containing organic amine or organic ammonium modified nanomontmorillonite, such as calcium-, sodium-calcium-, lithium-, magnesium-, aluminum-containing metal ion-containing organic ammonium or organic amine modified nanomontmorillonite, and the hydroxyl-containing substances are preferably selected from silica and/or silica sol.
In the technical scheme, the emulsifier is a nonionic lipophilic surfactant or/and a hydrophilic surfactant, such as fatty acid polyoxyethylene ester, alkyl acid polyoxyethylene ether, fatty alcohol polyoxyethylene ether and the like, and the mass ratio of the two surfactants is adjusted, so that the hydrophilic-lipophilic balance value of the emulsifier system is between 3 and 9; in order to increase the stability of the system, some alcohols or salts can be added as co-emulsifiers, and the total dosage of the two is 1-30% w.t% of the emulsifier system.
In the above technical scheme, the oxidant is selected from potassium persulfate, sodium persulfate, ammonium persulfate or benzoyl peroxide; the reducing agent is selected from sodium sulfite, potassium sulfite, sodium bisulfite, potassium bisulfite, sodium thiosulfate, ferrous chloride and the like; the azo compound is selected from 2, 2' -azo [2- (2-imidazolin-2-yl) propane ] dihydrochloride (V044), azobisisobutylamidine hydrochloride (V50), Azobisisobutyronitrile (AIBN), Azobisisoheptonitrile (ABVN), etc.;
in the technical scheme, the deoxygenation in the step (c) can be carried out at the temperature of 5-30 ℃ and the stirring speed of 300-600 rpm, the oxidant and the reducing agent can be preferably added in the form of aqueous solution, and the time for keeping the temperature and continuing the reaction after the temperature reaches the maximum peak is preferably 0.5-1 hour.
In the above technical scheme, if the azo initiator in the step (d) is a water-soluble initiator, the water-soluble azo initiator is preferably added into the water phase II, and if the azo initiator is an oil-soluble azo initiator, an oil-soluble solvent with the total oil phase being less than or equal to 5% is uniformly stirred to prepare a solution, and the solution is added into the formed core emulsion of the microsphere oil displacement agent.
In the technical scheme, the reaction time in the step (d) is preferably 3-6 h.
In the above technical solution, in the step (c): shearing by preferably adopting a homogenizing emulsifying machine, and preparing the water phase I and the oil phase into emulsion, wherein the shearing is preferably carried out at a high speed for 10-30 minutes at 8000-12000 r/min; the oxygen removal time is preferably 0.5 h-1 h; the oxidant in the redox initiator is preferably added in the form of an aqueous solution, and the stirring time after the addition is preferably 5-10 min.
In the above technical solution, in the step (d): preferably, adding an oil-soluble azo initiator and then stirring, wherein the stirring time is preferably 10-30 min; after the reaction is finished, the reaction product is preferably cooled and discharged, and the cooling temperature is preferably room temperature (namely 20-35 ℃).
In order to solve the fourth technical problem, the invention adopts the following technical scheme: the application of the multiple crosslinked core-shell polymer microsphere profile control and flooding agent in oil fields is characterized in that the multiple crosslinked core-shell polymer microsphere profile control and flooding agent is used for solving the second technical problem.
In the above technical scheme, the application is not particularly limited, and those skilled in the art can apply the multiple crosslinked core-shell polymer microsphere profile control and flooding agent prepared by the present invention to field applications for improving recovery efficiency, such as deep profile control and oil displacement for high temperature high salinity and medium high permeability oil reservoir tertiary oil recovery, etc., directly or after being compounded with other oil field chemicals according to the prior art.
The invention relates to a multi-crosslinking core-shell polymer microsphere, a profile control agent and a preparation method thereof, wherein an inverse emulsion polymerization method is adopted, and different organic and inorganic crosslinking agents are respectively introduced into monomers of a microsphere core or a microsphere shell, so that the expansion performance, the elasticity, the heat-resistant stability and the like of the microsphere can be enhanced under the synergistic effect; the core and the shell of the microsphere have controllable expansion rate and better strength and heat-resistant stability, so that the profile control effect on the medium-high permeability reservoir is effective for a long time.
By adopting the technical scheme of the invention, the obtained multiple cross-linked core-shell polymer microspheres and the profile control and flooding agent have the advantages that the initial particle size of the polymer microspheres is adjustable between 300 and 1000nm, the polymer microspheres still have good expansion performance and plugging performance after long-term aging under the oil reservoir condition, can be directly used for field application of improving recovery ratio such as deep profile control and oil displacement for high-temperature high-salt and medium-high-permeability oil-reservoir tertiary oil recovery, and the like, and have a swelling-relieving effect, the plugging rate can reach more than 90 percent, and good technical effects are obtained.
The invention is further illustrated by the following specific examples.
Detailed Description
[ example 1 ]
660g of 7# white oil, 70g of SPAN80 and 8g of TWEEN80 are added into a reaction kettle and stirred until the materials are completely and uniformly mixed to form a mixed oil phase; adding 260g of water, 8g of silica sol (40 percent content), 320g of acrylamide, 50g of methacryloyl propyl trimethyl ammonium chloride, 18g of potassium acetate, 0.5g of sodium diethylenetriamine pentaacetate, 12g of urea and 1.0g of methylene bisacrylamide into a container with a certain size, and uniformly stirring and dissolving to obtain a water phase I; adding 280g of water, 10g of CTAB modified nano montmorillonite DK1 (Zhejiang Fenghong clay chemical Co., Ltd.), 300g of acrylamide, 100g of sodium acrylate, 18g of potassium acetate, 0.5g of diethylenetriamine pentaacetic acid sodium, 10g of isopropanol, 12g of urea and 0.8g of methylene bisacrylamide into another container, stirring the solvent uniformly, adding 20g of isopropanol solution dissolved with 2g of azobisisobutyronitrile, stirring and dissolving uniformly to obtain a water phase II; ammonium persulfate and sodium bisulfite are respectively prepared into 2.0 percent and 0.2 percent aqueous solutions for standby. Slowly adding the water phase I into the mixed oil phase, simultaneously starting a homogenizing emulsifying machine, and carrying out high-speed shearing at 8000 rpm for 30 minutes to form milky emulsion which is put into a reaction kettle; controlling the temperature in the reaction kettle at 20 ℃, stirring at a rotating speed of 400rpm, introducing nitrogen to remove oxygen for 0.5h, then dripping 2g of an oxidant aqueous solution, stirring for 10min until the mixture is uniform, then continuously dripping a reducing agent aqueous solution at a certain speed to initiate polymerization, controlling the heat release of the polymerization reaction by the dripping speed of the reducing agent aqueous solution, controlling the temperature rise speed to be less than or equal to 1 ℃/min, raising the temperature to 43 ℃ after about 3 hours, and keeping the temperature to continue the reaction for 0.5h to obtain the core part of the semitransparent multi-crosslinked core-shell polymer microsphere profile control and flooding agent; and (3) heating to 65 ℃, adding the water phase II into the formed nuclear emulsion of the microsphere profile control and flooding agent at a certain speed, controlling the polymerization to stably proceed through the adding speed of the water phase II and the water bath temperature, finishing the reaction after 6 hours, cooling to room temperature, discharging to obtain a semitransparent product, and stably storing for more than 6 months.
The content of the precipitated solid is 36.5 percent, the initial average particle size is 450nm, the total mineralization is 50000mg/L at 95 ℃, and the Ca content is determined by the method of sampling analysis and reference of Q/SH1020 enterprise standard & lt & gt technical conditions for Polymer microsphere deep profile control and flooding agent & gt of China petrochemical group Shengli Petroleum administration2++Mg2+: aging for 5 days, 15 days and 30 days under 1000mg/L saline water, wherein the expansion times of the particle diameters are respectively 3.6 times, 6.4 times and 9.8 times, injecting 0.2 percent polymer 0.5PV after aging for 30 days by using a 1500mD sand filling pipe, and then injecting subsequent water flooding 5PV, and the plugging rate is measured to reach 86 percent.
[ example 2 ]
660g of 5# white oil, 72g of SPAN80 and 5g of TWEEN60 are added into a reaction kettle and stirred until the materials are completely and uniformly mixed to form a mixed oil phase; adding 270g of water, 7g of silica sol (40 percent content), 300g of acrylamide, 80g of methacryloyl propyl trimethyl ammonium chloride, 18g of sodium acetate, 0.5g of ethylene diamine tetraacetic acid disodium salt, 12g of urea and 1.1g of methylene bisacrylamide into a container with a certain size, and uniformly stirring and dissolving to obtain a water phase I; adding 270g of water, 11g of dodecyl dihydroxy ammonium modified nano montmorillonite DK2 (Zhejiang Fenghong clay chemical Co., Ltd.), 300g of acrylamide, 120g of 2-acrylamido-2-methyl sodium propanesulfonate, 18g of sodium acetate, 0.5g of ethylene diamine tetraacetic acid disodium salt, 10g of isopropanol, 12g of urea and 2.0g of polyethylene glycol diacrylate into another container, stirring the solvent uniformly, adding 20g of isopropanol solution in which 2g of azodiisoheptonitrile is dissolved, and stirring and dissolving the mixture uniformly to obtain a water phase II; ammonium persulfate and sodium bisulfite are respectively prepared into 2.0 percent and 0.2 percent aqueous solutions for standby. Slowly adding the water phase I into the mixed oil phase, starting a homogenizing emulsifying machine at the same time, and shearing at a high speed of 10000 r/min for 15 min to form milky white emulsion which is put into a reaction kettle; controlling the temperature in the reaction kettle at 18 ℃, stirring at a rotating speed of 500rpm, introducing nitrogen to remove oxygen for 0.5h, then dripping 2g of an oxidant aqueous solution, stirring for 10min until the mixture is uniform, then continuously dripping a reducing agent aqueous solution at a certain speed to initiate polymerization, controlling the heat release of the polymerization reaction by the dripping speed of the reducing agent aqueous solution, controlling the temperature rise speed to be less than or equal to 1 ℃/min, raising the temperature to 42 ℃ after about 4 hours, preserving the temperature, and continuing the reaction for 0.5h to obtain the core part of the semitransparent multi-crosslinked core-shell polymer microsphere profile control and flooding agent; and (3) heating to 55 ℃, adding the water phase II into the formed nuclear emulsion of the microsphere profile control and flooding agent at a certain speed, controlling the polymerization to stably proceed through the adding speed of the water phase II and the water bath temperature, finishing the reaction after 6 hours, cooling to room temperature, discharging to obtain a milky white product, and stably storing for more than 6 months.
The content of the precipitated solid is 36.5 percent, the initial average grain diameter is 580nm, the total mineralization is 50000mg/L at 95 ℃, and the Ca content is determined by the method of sampling analysis and reference of Q/SH1020 enterprise standard & lt & gt technical conditions for Polymer microsphere deep profile control and flooding agent & gt of China petrochemical group Shengli Petroleum administration2++Mg2+: aging for 5 days, 15 days and 30 days under 1000mg/L saline water, wherein the expansion times of the particle diameters are respectively 4.2 times, 6.7 times and 8.9 times, injecting 0.2 percent polymer 0.5PV after aging for 30 days by using a 1500mD sand filling pipe, and then injecting subsequent water flooding 5PV, and measuring that the plugging rate reaches 87 percent.
[ example 3 ]
Firstly, 680g of 120# solvent oil and 78g of SPAN60 are added into a reaction kettle, and stirred until the mixture is completely and uniformly mixed to be used as a mixed oil phase; adding 270g of water, 15g of silica sol (40%), 300g of acrylamide, 110g of acryloyloxyethyl trimethyl ammonium chloride, 20g of sodium acetate, 1.0g of disodium ethylenediamine tetraacetic acid, 15g of isopropanol, 10g of urea and 2.1g of pentaerythritol triacrylate into a container with a certain size, and uniformly stirring and dissolving to obtain a water phase I; adding 270g of water, 7g of octadecyl dimethyl benzyl ammonium chloride modified nano montmorillonite DK4 (Zhejiang Fenghong clay chemical Co., Ltd.), 300g of acrylamide, 150g of sodium vinylbenzene sulfonate, 20g of sodium acetate, 0.5g of ethylene diamine tetraacetic acid disodium salt and 12g of urea into another container, stirring the solvent uniformly, adding 20g of isopropanol solution in which 2g of azodiisoheptanonitrile and 1.0g of divinylbenzene are dissolved, and stirring and dissolving the mixture uniformly to obtain a water phase II; ammonium persulfate and sodium bisulfite are respectively prepared into 2.0 percent and 0.2 percent aqueous solutions for standby. Slowly adding the water phase I into the mixed oil phase, starting a homogenizing emulsifying machine, and carrying out high-speed shearing at 9000 r/min for 25 min to form milky emulsion, and putting the milky emulsion into a reaction kettle; controlling the temperature in the reaction kettle at 25 ℃, stirring at 520rpm, introducing nitrogen to remove oxygen for 0.5h, then dripping 2g of oxidant aqueous solution, stirring for 10min until the oxidant aqueous solution is uniform, then continuously dripping reducing agent aqueous solution at a certain speed to initiate polymerization, controlling the heat release of the polymerization reaction by the dripping speed of the reducing agent aqueous solution, controlling the temperature rise speed to be less than or equal to 1 ℃/min, raising the temperature to 41 ℃ after about 3.5 hours, preserving the temperature and continuing the reaction for 0.5 hour to obtain the core part of the semitransparent multi-crosslinked core-shell polymer microsphere profile control and flooding agent; heating to 52 ℃, adding the water phase II into the formed nuclear emulsion of the microsphere profile control and flooding agent at a certain speed, controlling the polymerization to stably proceed through the adding speed of the water phase II and the water bath temperature, finishing the reaction after 7 hours, cooling to room temperature, discharging to obtain a milky white product, and stably storing for more than 6 months.
The content of the precipitated solid is 37.9 percent, the initial average particle size is 530nm, the total mineralization is 50000mg/L at 95 ℃, and the Ca content is determined by the method of sampling analysis and reference of Q/SH1020 enterprise standard & lt & gt technical conditions for Polymer microsphere deep profile control and flooding agent & gt of China petrochemical group Shengli Petroleum administration2++Mg2+: aging in 1000mg/L salineAfter 5 days, 15 days and 30 days, the expansion times of the particle diameters are respectively 4.6 times, 6.8 times and 9.3 times, a 1500mD sand filling pipe is used for injecting 0.5PV of 0.2 percent polymer after aging for 30 days, and then the subsequent water drive 5PV is injected, and the plugging rate is measured to reach 91 percent.
[ example 4 ]
660g of kerosene, 70g of SPAN80 and 8g of TWEEN80 are added into a reaction kettle and stirred until the kerosene, the SPAN and the TWEEN are completely and uniformly mixed to form a mixed oil phase; adding 260g of water, 9g of silica sol (40 percent content), 350g of acrylamide, 100g of methacryloyl propyl trimethyl ammonium chloride, 25g of sodium acetate, 1.0g of ethylene diamine tetraacetic acid disodium salt, 20g of isopropanol, 15g of urea and 1.0g of methylene bisacrylamide into a container with a certain size, and uniformly stirring and dissolving to obtain a water phase I; adding 270g of water, 12g of dioctadecylamine benzyl modified nano montmorillonite DK3 (Zhejiang Fenghong clay chemical Co., Ltd.), 300g of acrylamide, 120g of sodium methacrylate, 25g of sodium acetate, 1.0g of disodium ethylenediaminetetraacetate, 15g of isopropanol, 10g of urea, 1.8g of pentaerythritol triacrylate and 2g of 2, 2' -azo [2- (2-imidazoline-2-yl) propane ] dihydrochloride into another container, and uniformly stirring and dissolving the mixture to obtain a water phase II; ammonium persulfate and sodium bisulfite are respectively prepared into 2.0 percent and 0.2 percent aqueous solutions for standby. Slowly adding the water phase I into the mixed oil phase, simultaneously starting a homogenizing emulsifying machine, and shearing at a high speed of 11000 r/min for 12 min to form milky white emulsion which is put into a reaction kettle; controlling the temperature in the reaction kettle at 22 ℃, controlling the stirring speed to 480rpm, introducing nitrogen to remove oxygen for 0.5h, then dripping 2g of oxidant aqueous solution, stirring for 10min until the mixture is uniform, then continuously dripping reducing agent aqueous solution at a certain speed to initiate polymerization, controlling the heat release of the polymerization reaction by the dripping speed of the reducing agent aqueous solution, controlling the temperature rise speed to be less than or equal to 1 ℃/min, keeping the temperature for about 4.5 hours, then raising the temperature to 44 ℃, and continuing the reaction for 0.5 hour to obtain the core part of the translucent multiple-crosslinked core-shell polymer microsphere profile control and flooding agent; heating to 52 ℃, adding the water phase II into the formed nuclear emulsion of the microsphere profile control and flooding agent at a certain speed, controlling the polymerization to be stably carried out by the adding speed of the water phase II and the water bath temperature, finishing the reaction after 7.5h, cooling to room temperature, discharging to obtain a milky white product, and stably storing for more than 6 months.
The content of the precipitated solid is 38.2 percent, the initial average particle size is 780nm, the total mineralization is 50000mg/L at 85 ℃, and the Ca content is determined by the method of sampling analysis and reference of Q/SH1020 enterprise standard & lt & gt technical conditions for Polymer microsphere deep profile control and flooding agent & gt of China petrochemical group Shengli Petroleum administration2++Mg2+: aging for 5 days, 15 days and 30 days under 1000mg/L saline water, wherein the expansion times of the particle diameters are respectively 4.3, 7.0 and 9.8 times, injecting 0.2 percent polymer 0.5PV after aging for 30 days by using a 1500mD sand filling pipe, and then injecting subsequent water flooding 5PV, and the plugging rate is 91 percent.
[ example 5 ]
670g of 3# white oil, 72g of SPAN80 and 5g of OP10 are added into a reaction kettle and stirred until the materials are completely and uniformly mixed to form a mixed oil phase; adding 270g of water, 10g of silica sol (40 percent content), 340g of acrylamide, 100g of dimethyl diallyl ammonium chloride, 22g of sodium acetate, 0.8g of disodium ethylene diamine tetraacetate, 12g of urea and 1.8g of methylene bisacrylamide into a container with a certain size, and uniformly stirring and dissolving to obtain a water phase I; adding 270g of water, 15g of caprolactam modified nano montmorillonite DK5 (Zhejiang Fenghong clay chemical Co., Ltd.), 300g of acrylamide, 130g of 2-acrylamido-2-methyl sodium propanesulfonate, 22g of sodium acetate, 0.8g of ethylene diamine tetraacetic acid disodium salt, 20g of isopropanol, 10g of urea and 2.0g of polyethylene glycol diacrylate into another container, stirring the solvent uniformly, adding 20g of isopropanol solution in which 2g of azobisisoheptonitrile is dissolved, and stirring and dissolving the mixture uniformly to obtain a water phase II; ammonium persulfate and sodium bisulfite are respectively prepared into 2.0 percent and 0.2 percent aqueous solutions for standby. Slowly adding the water phase I into the mixed oil phase, starting a homogenizing emulsifying machine at the same time, and shearing at a high speed of 10000 r/min for 18 min to form milky white emulsion which is put into a reaction kettle; controlling the temperature in the reaction kettle at 26 ℃, stirring at the rotation speed of 550rpm, introducing nitrogen to remove oxygen for 0.5h, then dripping 2g of oxidant aqueous solution, stirring for 10min to be uniform, then continuously dripping reducing agent aqueous solution at a certain speed to initiate polymerization, controlling the heat release of the polymerization reaction by the dripping speed of the reducing agent aqueous solution, controlling the temperature rise speed to be less than or equal to 1 ℃/min, raising the temperature to 42 ℃ after about 3.8 hours, preserving the temperature and continuing the reaction for 0.5 hour to obtain the core part of the semitransparent multi-crosslinked core-shell polymer microsphere profile control and flooding agent; heating to 52 ℃, adding the water phase II into the formed nuclear emulsion of the microsphere profile control and flooding agent at a certain speed, controlling the polymerization to stably proceed through the adding speed of the water phase II and the water bath temperature, finishing the reaction after 7h, cooling to room temperature, discharging to obtain a semitransparent product, and stably storing for more than 6 months.
The content of the precipitated solid is 38.5 percent, the initial average particle size is 620nm, and the total mineralization is 80000mg/L at 85 ℃ and Ca2++Mg2+: aging for 5 days, 15 days and 30 days under 3000mg/L saline water, wherein the expansion times of particle diameters are respectively 4.7 times, 6.2 times and 9.6 times, injecting 0.2 percent polymer 0.5PV after aging for 30 days by using a 1500mD sand filling pipe, and then injecting subsequent water flooding 5PV, and the plugging rate is determined to reach 89 percent.
[ example 6 ]
Firstly, 680g of 90# solvent oil and 75g of SPAN80 are added into a reaction kettle, and stirred until the mixture is completely and uniformly mixed to form a mixed oil phase; adding 280g of water, 9g of silica sol (40 percent content), 320g of acrylamide, 120g of dimethyl diallyl ammonium chloride, 25g of potassium acetate, 0.7g of sodium diethylenetriamine pentaacetate, 20g of isopropanol, 15g of urea and 1.9g of pentaerythritol triacrylate into a container with a certain size, and uniformly stirring and dissolving to obtain a water phase I; adding 270g of water, 12g of octadecyl dimethyl benzyl ammonium chloride modified nano montmorillonite DK4 (Zhejiang Fenghong clay chemical Co., Ltd.), 350g of acrylamide, 90g of sodium vinylsulfonate, 25g of sodium acetate, 0.8g of divinylbenzene, 12g of urea, 20g of isopropanol, 1.8g of pentaerythritol triacrylate and 2g of azo diisobutyl amidine hydrochloride (V50) into another container, and uniformly stirring and dissolving the mixture to obtain a water phase II; ammonium persulfate and sodium bisulfite are respectively prepared into 2.0 percent and 0.2 percent aqueous solutions for standby. Slowly adding the water phase I into the mixed oil phase, starting a homogenizing emulsifying machine, and shearing at a high speed of 9000 r/min for 20 min to form milky emulsion, and putting the milky emulsion into a reaction kettle; controlling the temperature in the reaction kettle at 18 ℃, stirring at a rotating speed of 500rpm, introducing nitrogen to remove oxygen for 0.5h, then dripping 2g of oxidant aqueous solution, stirring for 10min to be uniform, then continuously dripping reducing agent aqueous solution at a certain speed to initiate polymerization, controlling the heat release of the polymerization reaction by the dripping speed of the reducing agent aqueous solution, controlling the temperature rise speed to be less than or equal to 1 ℃/min, raising the temperature to 43 ℃ after about 3.5 hours, preserving the temperature and continuing the reaction for 0.5 hour to obtain the core part of the semitransparent multi-crosslinked core-shell polymer microsphere profile control and flooding agent; heating to 50 ℃, adding the water phase II into the formed nuclear emulsion of the microsphere profile control and flooding agent at a certain speed, controlling the polymerization to be stably carried out through the adding speed of the water phase II and the water bath temperature, finishing the reaction after 6.5 hours, cooling to room temperature, discharging to obtain a semitransparent product, and stably storing for more than 6 months.
The content of the precipitated solid is 38.8 percent, the initial average particle size is 630nm, the total mineralization is 50000mg/L at 85 ℃, and the Ca content is determined by the method of sampling analysis and reference of Q/SH1020 enterprise standard & lt & gt technical conditions for Polymer microsphere deep profile control and flooding agent & gt of China petrochemical group Shengli Petroleum administration2++Mg2+: aging for 5 days, 15 days and 30 days under 5000mg/L saline water, wherein the expansion times of the particle diameters are respectively 4.6 times, 6.7 times and 9.6 times, injecting 0.2 percent polymer 0.5PV after aging for 30 days by using a 1500mD sand filling pipe, and then injecting subsequent water flooding 5PV, and the plugging rate is measured to reach 86 percent.
The embodiment shows that the multi-crosslinking core-shell polymer microsphere profile control agent obtained by the invention has the initial particle size of 500-1000 submicron and the solid content of 35-40%, can effectively block a 1500mD high-permeability sand-packed pipe after being aged for a period of time under the condition of a high-temperature and high-salt oil reservoir, is injected with 0.5PV with the concentration of 0.2% after being aged for 30 days, is injected with the subsequent water drive 5PV, and has the blocking rate of more than 85%.
[ COMPARATIVE EXAMPLE 1 ]
660g of 7# white oil, 70g of SPAN80 and 8g of TWEEN80 are added into a reaction kettle and stirred until the materials are completely and uniformly mixed to form a mixed oil phase; adding 260g of water, 8g of silica sol (40 percent content), 320g of acrylamide, 50g of methacryloyl propyl trimethyl ammonium chloride, 18g of potassium acetate, 0.5g of sodium diethylenetriamine pentaacetate, 12g of urea and 1.0g of methylene bisacrylamide into a container with a certain size, and uniformly stirring and dissolving to obtain a water phase I; adding 280g of water, 10g of CTAB modified nano montmorillonite DK1 (Zhejiang Fenghong clay chemical Co., Ltd.), 300g of acrylamide, 100g of sodium acrylate, 18g of potassium acetate, 0.5g of diethylenetriamine pentaacetic acid sodium, 10g of isopropanol, 12g of urea and 0.8g of methylene bisacrylamide into another container, stirring the solvent uniformly, adding 20g of isopropanol solution dissolved with 2g of azobisisobutyronitrile, stirring and dissolving uniformly to obtain a water phase II; ammonium persulfate and sodium bisulfite are respectively prepared into 2.0 percent and 0.2 percent aqueous solutions for standby. Slowly adding the water phase I into the mixed oil phase, simultaneously starting a homogenizing emulsifying machine, and carrying out high-speed shearing at 8000 rpm for 30 minutes to form milky emulsion which is put into a reaction kettle; controlling the temperature in the reaction kettle at 20 ℃, stirring at the rotating speed of 400rpm, introducing nitrogen to remove oxygen for 0.5h, then dripping 2g of oxidant aqueous solution, stirring for 10min to be uniform, then adding 20g of reducing agent aqueous solution at a higher speed to initiate polymerization, quickly raising the temperature to 45 ℃, and carrying out heat preservation reaction for 3h to obtain the core part of the opaque multi-crosslinked core-shell polymer microsphere profile control and flooding agent; and (3) completely adding the water phase II into the formed nuclear emulsion of the microsphere profile control and flooding agent, stirring for 30min until the system is uniform, heating to 65 ℃, controlling the polymerization temperature through the water bath temperature, finishing the reaction after 6h, cooling to room temperature, discharging to obtain an opaque product, and layering and settling appear in the next day.
The content of precipitated solid is 36.5 percent and the initial average grain diameter is 520nm by the measurement method of the standard polymer microsphere deep profile control and flooding agent technical condition of the enterprise standard of Q/SH1020 China petrochemical group Shengli Petroleum administration for sampling analysis reference, but the particle size dispersion index is multimodal and obviously widened. Ca at 95 ℃ and a total degree of mineralization of 50000mg/L2++Mg2+: aging for 5 days, 15 days and 30 days under 1000mg/L saline water, wherein the expansion times of the particle diameters are respectively 3.6 times, 6.4 times and 9.8 times, injecting 0.2 percent polymer 0.5PV after aging for 30 days by using a 1500mD sand filling pipe, and then injecting subsequent water flooding 5PV, and measuring that the plugging rate reaches 56 percent.
[ COMPARATIVE EXAMPLE 2 ]
660g of 7# white oil, 70g of SPAN80 and 8g of TWEEN80 are added into a reaction kettle and stirred until the materials are completely and uniformly mixed to form a mixed oil phase; adding 260g of water, 320g of acrylamide, 50g of methacryl propyl trimethyl ammonium chloride, 18g of potassium acetate, 0.5g of sodium diethylenetriamine pentaacetate, 12g of urea and 1.0g of methylene bisacrylamide into a container with a certain size, and uniformly stirring and dissolving to obtain a water phase I; adding 280g of water, 300g of acrylamide, 100g of sodium acrylate, 18g of potassium acetate, 0.5g of sodium diethylenetriaminepentaacetate, 10g of isopropanol, 12g of urea and 0.8g of methylene bisacrylamide into another container, stirring the solvent uniformly, adding 20g of isopropanol solution dissolved with 2g of azobisisobutyronitrile, and stirring and dissolving uniformly to obtain a water phase II; ammonium persulfate and sodium bisulfite are respectively prepared into 2.0 percent and 0.2 percent aqueous solutions for standby. Slowly adding the water phase I into the mixed oil phase, simultaneously starting a homogenizing emulsifying machine, and carrying out high-speed shearing at 8000 rpm for 30 minutes to form milky emulsion which is put into a reaction kettle; controlling the temperature in the reaction kettle at 20 ℃, stirring at a rotating speed of 400rpm, introducing nitrogen to remove oxygen for 0.5h, then dripping 2g of an oxidant aqueous solution, stirring for 10min until the mixture is uniform, then continuously dripping a reducing agent aqueous solution at a certain speed to initiate polymerization, controlling the heat release of the polymerization reaction by the dripping speed of the reducing agent aqueous solution, controlling the temperature rise speed to be less than or equal to 1 ℃/min, raising the temperature to 43 ℃ after about 3 hours, and keeping the temperature to continue the reaction for 0.5h to obtain the core part of the semitransparent multi-crosslinked core-shell polymer microsphere profile control and flooding agent; and (3) heating to 65 ℃, adding the water phase II into the formed nuclear emulsion of the microsphere profile control and flooding agent at a certain speed, controlling the polymerization to stably proceed through the adding speed of the water phase II and the water bath temperature, finishing the reaction after 6 hours, cooling to room temperature, discharging to obtain a semitransparent product, and stably storing for more than 6 months.
The content of the precipitated solid is 36.5 percent, the initial average grain diameter is 520nm, the total mineralization is 50000mg/L at 95 ℃, and the Ca content is determined by the method of sampling analysis and reference of Q/SH1020 enterprise standard & lt & gt technical conditions for Polymer microsphere deep profile control and flooding agent & gt of China petrochemical group Shengli Petroleum administration2++Mg2+: aging for 5 days, 15 days and 30 days under 1000mg/L saline water, wherein the expansion times of the particle diameters are respectively 3.2 times, 6.8 times and 7.8 times, injecting 0.2 percent polymer 0.5PV after aging for 30 days by using a 1500mD sand filling pipe, and then injecting subsequent water flooding 5PV, and the plugging rate is measured to be 62 percent.
From the examples and comparative examples, the inventors have surprisingly found that the technical scheme of the present invention, which adopts a specific core-shell preparation process and introduces different organic and inorganic cross-linking agents into the monomer of the microsphere core or shell, is far superior to the conventional microsphere preparation process and the technical scheme of a single cross-linking agent in terms of product stability, particle size expansion factor and blocking rate, and is greatly beyond the expectation of those skilled in the art.

Claims (15)

1. A core-shell polymer microsphere profile control and flooding agent comprises core-shell polymer microspheres; the oil-water displacement agent is characterized in that the displacement agent is emulsion, and the displacement agent also comprises an oil phase, a water phase and an emulsifier; wherein the core-shell polymer microsphere comprises a polymer I inner core and a polymer II outer shell; the molecules of the polymer I and the polymer II independently comprise an inorganic cross-linking agent structural unit and an organic cross-linking agent structural unit;
wherein the inorganic cross-linking agent is selected from one of dodecyl dihydroxy ammonium modified nano-montmorillonite, hexadecyl trimethyl ammonium bromide modified nano-montmorillonite, octadecyl dimethyl benzyl ammonium chloride modified nano-montmorillonite, dioctadecyl benzyl modified nano-montmorillonite and caprolactam modified nano-montmorillonite;
the mass ratio of the inorganic cross-linking agent structural unit to the organic cross-linking agent structural unit in the molecule of the polymer I is 1: 1-10: 1; the mass ratio of the inorganic cross-linking agent structural unit to the organic cross-linking agent structural unit in the molecule of the polymer II is 1: 1-20: 1;
the polymer I molecule contains an acrylamide unit and a comonomer I unit; the molecule of the polymer II contains an acrylamide unit and a comonomer II unit; the comonomer I and the comonomer II are independently and randomly selected from one or more than two of nonionic water-soluble monomers, anionic monomers and cationic monomers;
the preparation method of the core-shell polymer microsphere profile control and flooding agent comprises the following steps:
(a) uniformly mixing an oil-soluble solvent and a main emulsifier to form an oil phase;
(b) uniformly mixing acrylamide, a comonomer I, a co-emulsifier and a cross-linking agent I in water to prepare a water phase I with the pH value of 3-8; uniformly mixing acrylamide, a comonomer II, a co-emulsifier and a cross-linking agent II in water to prepare a water phase II with the pH value of 3-8, wherein the mass ratio of the water phase I to the water phase II is 1: 9-9: 1;
(c) preparing an emulsion from the water phase I and the oil phase, deoxidizing, adopting a redox initiator, controlling the adding speed of a reducing agent so that the heating speed is less than or equal to 1 ℃/min, and keeping the reaction temperature at the highest temperature of less than or equal to 50 ℃, and then keeping the temperature to continue reacting for at least 0.5 hour after the reaction temperature reaches the highest peak to obtain the core emulsion of the core-shell polymer microsphere profile control and flooding agent;
(d) and (2) in the presence of an azo initiator, adding the water phase II into the core emulsion heated to the initiation temperature of the azo initiator, controlling the adding speed of the water phase II to keep the polymerization temperature stable, and finishing the reaction after the reaction is carried out for at least 3 hours to obtain the core-shell polymer microsphere profile control and flooding agent.
2. The agent of claim 1, wherein the organic cross-linking agent is selected from the group consisting of organic compounds containing reactive functional groups.
3. The core-shell polymer microsphere profile control agent according to claim 2, wherein the organic compound containing active functional groups is selected from one or more of N, N-methylene bisacrylamide, polyethylene glycol diacrylate, dimethylaminoethyl acrylate, aldehydes containing two or more aldehyde groups, trimethylolpropane trimethacrylate and pentaerythritol triacrylate.
4. The core-shell polymer microsphere profile control agent according to claim 1, wherein the nonionic water-soluble monomer is selected from one or more of methacrylamide, N-isopropylacrylamide, N-dimethylacrylamide, N-diethylacrylamide, N-methylolacrylamide, N-vinylformamide, N-vinylacetamide, N-vinylpyridine and N-vinylpyrrolidone; the anionic monomer is selected from one or more of 2-acrylamido-2-methylpropanesulfonic acid, acrylic acid, methacrylic acid, itaconic acid, vinylbenzenesulfonic acid, vinylsulfonic acid and/or water-soluble alkali metal, alkaline earth metal and ammonium salt thereof, and the cationic monomer is selected from one or more of dimethyldiallylammonium chloride, acryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride and 2-acrylamido-2-methylpropyltrimethylammonium chloride.
5. The core-shell polymer microsphere profile control agent according to claim 1, wherein the initial particle size of the core-shell polymer microsphere is 300-1000 nm.
6. The core-shell polymer microsphere profile control agent according to claim 5, wherein the content of the core-shell polymer microspheres is more than 35% in terms of the total mass percentage of the profile control agent; the content of the emulsifier is 2-10%; the mass ratio of the oil phase to the water phase is 1: 1-1: 3.
7. a preparation method of a core-shell polymer microsphere profile control and flooding agent comprises the following steps:
(a) uniformly mixing an oil-soluble solvent and a main emulsifier to form an oil phase;
(b) uniformly mixing acrylamide, a comonomer I, a co-emulsifier and a cross-linking agent I in water to prepare a water phase I with the pH value of 3-8; uniformly mixing acrylamide, a comonomer II, a co-emulsifier and a cross-linking agent II in water to prepare a water phase II with the pH value of 3-8, wherein the mass ratio of the water phase I to the water phase II is 1: 9-9: 1;
(c) preparing an emulsion from the water phase I and the oil phase, deoxidizing, adopting a redox initiator, controlling the adding speed of a reducing agent so that the heating speed is less than or equal to 1 ℃/min, and keeping the reaction temperature at the highest temperature of less than or equal to 50 ℃, and then keeping the temperature to continue reacting for at least 0.5 hour after the reaction temperature reaches the highest peak to obtain the core emulsion of the core-shell polymer microsphere profile control and flooding agent;
(d) in the presence of an azo initiator, adding a water phase II into the nuclear emulsion heated to the initiation temperature of the azo initiator, controlling the adding speed of the water phase II to keep the polymerization temperature stable, and finishing the reaction after the reaction is carried out for at least 3 hours to obtain the core-shell polymer microsphere profile control and flooding agent;
wherein the amount of the oil-soluble solvent is 20-50 parts by weight; the total using amount of the water phase I and the water phase II is 30-80 parts, and the mass percentage of the monomers in the corresponding water phase I and the water phase II is 40-70%; the dosage of the cross-linking agent I and the cross-linking agent II is 0.05-4 parts independently, the cross-linking agent I and the cross-linking agent II both comprise an inorganic cross-linking agent and an organic cross-linking agent independently, and the mass ratio of the inorganic cross-linking agent to the organic cross-linking agent in the cross-linking agent I is 1: 1-10: 1; the mass ratio of the inorganic cross-linking agent to the organic cross-linking agent in the cross-linking agent II is 1: 1-20: 1; the total dosage of the main emulsifier and the auxiliary emulsifier is 2-10 parts; the comonomer I and the comonomer II are independently and optionally selected from at least one of nonionic water-soluble monomers, anionic monomers and/or cationic monomers; the inorganic cross-linking agent is selected from dodecyl dihydroxy ammonium modified nano-montmorillonite, hexadecyl trimethyl ammonium bromide modified nano-montmorillonite, octadecyl dimethyl benzyl ammonium chloride modified nano-montmorillonite, dioctadecyl amine benzyl modified nano-montmorillonite and caprolactam modified nano-montmorillonite.
8. The preparation method of the core-shell polymer microsphere profile control agent according to claim 7, wherein the content of the core-shell polymer microsphere is more than 35% by mass of the profile control agent.
9. The method for preparing the core-shell polymer microsphere profile control agent according to claim 7, wherein the oil-soluble solvent is at least one selected from aliphatic hydrocarbon, aromatic hydrocarbon and halogenated hydrocarbon.
10. The preparation method of the core-shell polymer microsphere profile control agent according to claim 9, wherein the hydrophilic-lipophilic balance value of the composite emulsifier composed of the main emulsifier and the co-emulsifier is between 3 and 9.
11. The method for preparing the core-shell polymer microsphere profile control agent according to claim 10, wherein the co-emulsifier is selected from alcohols or salts, and the amount of the co-emulsifier is 1 to 30 w.t% of the total mass of the main emulsifier and the co-emulsifier.
12. The method of claim 7, wherein the non-ionic water-soluble monomer is selected from one or more of methacrylamide, N-isopropylacrylamide, N-dimethylacrylamide, N-diethylacrylamide, N-methylolacrylamide, N-vinylformamide, N-vinylacetamide, N-vinylpyridine, and N-vinylpyrrolidone, the anionic monomer is selected from one or more of 2-acrylamido-2-methylpropanesulfonic acid, acrylic acid, methacrylic acid, itaconic acid, vinylbenzenesulfonic acid, vinylsulfonic acid, and/or water-soluble alkali metal, alkaline earth metal, and ammonium salt thereof, and the cationic monomer is selected from one or more of dimethyldiallylammonium chloride, and mixtures thereof, One or more of acryloyloxyethyltrimethyl ammonium chloride, methacryloyloxyethyltrimethylammonium chloride and 2-acrylamido-2-methylpropyltrimethyl ammonium chloride.
13. The method for preparing the core-shell polymer microsphere profile control agent according to claim 7, wherein the organic crosslinking agent is selected from organic compounds containing active functional groups.
14. The method for preparing the core-shell polymer microsphere profile control agent according to claim 13, wherein the organic compound containing active functional groups is one or more selected from N, N-methylene bisacrylamide, polyethylene glycol diacrylate, dimethylaminoethyl acrylate, aldehydes containing two or more aldehyde groups, trimethylolpropane trimethacrylate and pentaerythritol triacrylate.
15. The use of the core-shell polymer microsphere profile control agent as defined in any one of claims 1 to 6 in oil fields.
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