Polymer microsphere emulsion for profile control and displacement, and preparation method and application thereof

Abstract

The application relates to the technical field of petroleum chemical industry, and particularly discloses a polymer microsphere emulsion for profile control and flooding as well as a preparation method and application thereof. The polymer microsphere emulsion comprises functional polymer microspheres, a thickening agent, a cationic surfactant, salt and water. The polymer microsphere emulsion has good interface participation capacity and weak cross-linking effect. The cation and anion in the functional polymer microsphere structure are mutually attracted, the hydrophobic segments are mutually hydrophobic, and the aromatic rings are mutually pi-pi, so that the spatial morphology presents a dense network, and the polymer microspheres with certain mechanical strength are formed. A large number of sulfonic acid groups in the microsphere structure can act on water molecules to swell, and can also make the microsphere surface carry negative electricity. Under the joint action of the cationic surfactant and the salt, a flexible and adjustable spatial aggregate state is formed, so that the need of step-by-step plugging of water channeling is met.

Description

Technical Field

[0001] This invention belongs to the field of petrochemical technology, specifically relating to a method for preparing and applying a polymer microsphere emulsion for flow regulation. Background Technology

[0002] With the deepening of waterflooding development, the proportion of high water-cut, low-permeability oil and gas fields in my country is increasing year by year. Large amounts of crude oil in medium- and low-permeability reservoirs are difficult to reach and remain trapped in the formation, leading to a significant decrease in well production and a continuous increase in production costs. Polymer microsphere deep-entry regulation technology is a novel regulation technology developed in recent years. This technology mainly utilizes the characteristics of polymer nanospheres, such as small size, good dispersibility in water, easy entry into deep formations, and expansion upon contact with water at reservoir temperatures. These nanospheres migrate, block, deform, and then migrate and block water channels in pore throats until reaching deep formations, progressively blocking dominant water channels to achieve deep-entry regulation, thereby expanding the volume of injected water and improving waterflooding development. However, conventional polymer microspheres become ineffective in high-temperature, high-salinity reservoirs due to dehydration shrinkage and thermal degradation. To ensure the effective functioning of polymer microsphere regulation agents in the formation, the research and development of new, more temperature- and salt-resistant, high-performance polymer microspheres remains a hot topic of interest for many researchers. Summary of the Invention

[0003] The first objective of this invention is to provide a polymer microsphere emulsion for displacement control, specifically employing the following technical solution: a method for preparing a polymer microsphere emulsion for displacement control, wherein, by weight percentage, the polymer microsphere emulsion comprises 10-30% functional polymer microspheres, 0.5%-3% thickener, 1%-8% cationic surfactant, 0%-2% salt, and the balance being water; the functional polymer microspheres are cross-linked polymers, and their structure is shown in simplified formula I:

[0004] In Formula I, x takes any integer from 0 to 3; y takes any integer from 0 to 7; and m, t, r, s, p, q, w, and z take positive integers from 0 to 200.

[0005] The polymer microsphere emulsion provided by this invention possesses excellent interfacial participation ability and weak cross-linking effect. This invention utilizes the mutual attraction between anions and cations in the functional polymer microsphere structure, the hydrophobic interactions between hydrophobic segments, and the π-π interactions between aromatic rings to create a dense network structure, forming polymer microspheres with a certain mechanical strength. The polymer structure contains a large number of sulfonic acid groups, exhibiting strong hydration capabilities. These abundant sulfonic acid groups can attract a large number of water molecules and form hydrogen bonds with them, causing the polymer microspheres to expand. Furthermore, the sulfonic acid groups on the microsphere surface easily lose protons and become negatively charged. Under the combined action of cationic surfactants and salts, the polymer microspheres bridge each other through charge interactions and hydrophobic interactions with the cationic surfactants, reducing the distance between the polymer microspheres and forming a more flexible and adjustable spatial aggregation state. This allows it to meet the requirements of migration, blocking, and deformation through formation pore throats, achieving the effect of progressively blocking dominant water-channeling pathways.

[0006] Preferably, based on the weight percentage of the polymer microsphere emulsion, the optimal dosage range for the cationic surfactant cholestyramine in the polymer microsphere emulsion is 1%-8%, and the optimal dosage range for the polymer microspheres is 10%-30%. The dosage ratio of cholestyramine to polymer microspheres determines the proportion of each functional group; for example, the ratio of anions to cations affects the association morphology of the polymer microspheres. Excessive or insufficient dosage will lead to changes in the association morphology, thereby affecting the blocking effect.

[0007] In some embodiments, the polymer microsphere emulsion further includes a thickener, a cationic surfactant, a salt, and a solvent. The thickener is preferably used in the range of 0.5%-3% by weight of the polymer microsphere emulsion; the cationic surfactant is preferably used in the range of 1%-8% by weight; the salt is preferably used in the range of 0-2% by weight; and the balance is water. The thickener is one or a combination of several of sodium carboxymethyl cellulose, sodium starch phosphate, sodium alginate, and polyvinylpyrrolidone; the cationic surfactant is cholestyramine, as shown in Formula II; and the salt includes one or a combination of several of sodium chloride, potassium chloride, ammonium chloride, and quaternary ammonium salts.

[0008]

[0009] In Equation II, n takes any integer from 2 to 200.

[0010] The inventors discovered that, by weight percentage, when x is 1, y is 7, and m, t, r, s, p, q, w, z are any integers from 100 to 200, the amount of functional polymer microspheres is 12%, the amount of thickener is 0.5%, the amount of cholestyramine is 6%, and the amount of salt is 2%, the polymer microsphere emulsion has a pale yellow and transparent appearance, a particle size of about 110 nm, can separate 23% solids, has a viscosity of 320 mPa·s, and an S element content of 2.6%.

[0011] The functional polymer microspheres were synthesized by reverse emulsion polymerization. The specific synthesis method is as follows, based on the weight percentage of the polymer emulsion used to prepare the polymer microspheres: (1) Preparation of polymer aqueous phase: Weigh functional monomer III (1%-10%) and dissolve it in deionized water. Add an appropriate amount of NaOH to adjust the solution to neutral. Add polymer structural monomer acrylamide (AM) (10%-30%), crosslinking agent (IV) (0.1%-1%) and complexing agent disodium ethylenediaminetetraacetate (0.05%-0.1%). Stir with a glass rod until completely dissolved to obtain polymer aqueous phase solution (40%-60%).

[0012] (2) Preparation of polymer oil phase: Measure an appropriate amount of white oil (30%-50%) into a beaker, adjust the addition ratio according to the HLB values ​​of Span80 (10%-20%) and Tween80 (1%-8%), and stir appropriately to form a homogeneous and stable oil phase solution (40%-60%).

[0013] (3) Preparation of polymer microspheres: First, the oil phase solution is heated at a low speed (3 kr·min) -1 Stir for 5 minutes, then slowly add the prepared aqueous polymer solution, and then stir at high speed (12 kr·min). -1 Shear emulsify for 5 min, place in a four-necked flask, and stir (300 rpm). -1 Nitrogen gas was passed through the bottle to purge air. After 30 minutes, ammonium persulfate and sodium bisulfite were added dropwise. The mixture was heated in a water bath (65 °C) until the solution became a white, homogeneous emulsion. The product was washed with a large amount of ethanol solution, cured with acetone, and dried in a vacuum drying oven at 50 °C until constant weight was obtained to obtain polymer microspheres.

[0014]

[0015] Equation III, where x is any integer from 0 to 3; and y is any integer from 0 to 7. Formula IV

[0016] Synthesis pathway of functional polymer microspheres (x takes any integer from 0 to 3; y takes any integer from 0 to 7; m, t, r, s, p, q, w, z take positive integers from 0 to 200) The functional monomer III was prepared by the following process: 1-hydroxy-2,5-dioxopyrrolidine-3-sulfonic acid was placed in a 1500 ml single-necked flask, and 4% by mass of potassium iodide catalyst and 500 ml of acetonitrile solution were added. The temperature was lowered to 5 °C, and a solution of bromoalkane was added. The reaction was carried out at room temperature for 24 h, and then the temperature was raised to 70 °C and the reaction was carried out for 72 h. The product was dried by rotary evaporation and recrystallized three times by diethyl ether to obtain a white quaternary ammonium salt solid powder (Formula V), which was then used. In a 1500 ml single-necked flask, a white quaternary ammonium salt solid powder (Formula V) and 500 ml of chloroform solution were added. The catalyst 4-dimethylaminopyridine was added, and the acid-binding agent was sodium acetate solution. The mixture was kept in an ice bath at a temperature below 5°C. A chloroform solution of alkenyl acyl chloride was slowly added dropwise to the flask using a constant-pressure dropping funnel. After the addition was complete, the reaction was allowed to proceed at room temperature for 24 h, followed by a reaction at 40°C for 48 h. The product was evaporated to dryness using a rotary evaporator, and then dissolved completely in dichloroform solution. The product was washed three times with saturated brine, allowed to stand for separation, and the aqueous phase was filtered off. The oil phase was dried using anhydrous magnesium sulfate, filtered, and the solvent was removed below 40°C to obtain an oily liquid. The oily liquid was dissolved in ethanol, stirred thoroughly, and the insoluble matter was filtered off. The product was then purified by recrystallization three times using ethanol-diethyl ether. The solid product was filtered and dried, yielding the amphoteric hydrophobic ionic monomer (Formula III).

[0017]

[0018] In the formula V, y is any integer from 0 to 7. Formula IV The crosslinking agent (Formula IV) is prepared by the following process: 2,5-dihydroxy-1,3-benzenedisulfonic acid solution and 500 ml of chloroform solution are added to a 1500 ml single-necked flask. 4-Dimethylaminopyridine is added as a catalyst, and sodium acetate solution is used as the acid binder. The mixture is kept in an ice bath at a temperature below 5°C. An excess of the chloroform solution containing alkenyl chloride is slowly added dropwise to the flask using a constant-pressure dropping funnel. After the addition is complete, the mixture is reacted at room temperature for 24 h, and then at 40°C for 48 h. The product is evaporated to dryness using a rotary evaporator, and then dissolved completely in dichloroform solution. The mixture is washed three times with saturated brine, allowed to stand for separation, and the aqueous phase is filtered off. The oil phase is dried using anhydrous magnesium sulfate, filtered, and the solvent is removed below 40°C to obtain an oily liquid. The oily liquid is redissolved in ethanol, stirred thoroughly, and the insoluble matter is filtered off. The solvent is removed below 40°C to obtain the crosslinking agent (Formula IV).

[0019] Another objective of this invention is to provide a method for preparing the above-mentioned polymer microsphere emulsion, which includes the following steps: mixing a thickener, a cationic surfactant and a salt and adding the mixture to an aqueous solution of functional polymer microspheres, stirring until homogeneous, to obtain a polymer microsphere emulsion.

[0020] Preferably, the above method further includes the step of adding one or a combination of nonionic surfactants, cationic surfactants, and alcohol solvents as needed.

[0021] The present invention relates to the application of polymer microsphere emulsions in the stripping of oil at the interface of water, oil, and rock solids.

[0022] The polymer microsphere emulsion of the present invention is used as an oilfield modifier for regulating and sealing geological oil reservoirs with water content and at the given temperature.

[0023] The polymer microsphere emulsion of the present invention is used to reduce the interfacial tension between the water and oil phases and to reduce the viscosity of heavy oil.

[0024] Compared with traditional oilfield modifiers, the polymer microsphere emulsion provided by this invention can block the dominant water channel in the deep formation step by step to achieve deep modifier, thereby expanding the injected water sweep volume and improving the waterflooding development effect. Attached Figure Description

[0025] Figure 1 This is a graph showing the viscosity-reducing effect of the polymer microsphere emulsion sample in Example 4 of the present invention on the heavy oil sample; Figure 2 This is a diagram showing the effect of the polymer microsphere emulsion sample in Example 4 of the present invention on reducing the interfacial tension of a heavy oil sample. Detailed Implementation

[0026] The following will provide a clear and complete description of the concept and technical effects of the present invention in conjunction with the embodiments, so as to fully understand the purpose, solution and effects of the present invention, but it should not be construed as limiting the scope of implementation of the present invention.

[0027] Example 1: A polymer microsphere emulsion for regulating and driving, by weight percentage, comprises 20% functional polymer microspheres I1, 0.5% sodium carboxymethyl cellulose thickener, 2% cationic surfactant cholestyramine, 0.5% sodium chloride, 0.5% ammonium chloride, and the balance being water. Its preparation method is as follows: the thickener, cationic surfactant, and salt are mixed and added to an aqueous solution of functional polymer microspheres I1, and stirred until homogeneous to obtain polymer microsphere emulsion A1.

[0028] Among them, the functional polymer microspheres I1 are cross-linked polymers (x is 1, y is 2), and their structure is shown in the simplified formula:

[0029] In equation I1, m, t, r, s, p, q, w, and z take positive integers from 0 to 200.

[0030] The functional polymer microspheres I1 are prepared by the following process: synthesized by reverse emulsion polymerization. The specific synthesis method is as follows, based on 100g of the polymer emulsion used to prepare the polymer microspheres: (1) Preparation of polymer aqueous phase: Weigh 5g of functional monomer (III1) and dissolve it in deionized water. Add an appropriate amount of NaOH to adjust the solution to neutral. Add 15g of polymer structural monomer acrylamide (AM), 0.3g of crosslinking agent (IV) and 0.05g of complexing agent disodium ethylenediaminetetraacetate. Stir with a glass rod until completely dissolved to obtain 50g of polymer aqueous phase solution.

[0031] (2) Preparation of polymer oil phase: Measure 30g of white oil into a beaker, adjust the addition ratio according to the HLB values ​​of 15g Span80 and 5g Tween80, and stir appropriately to form 50g of homogeneous and stable oil phase solution.

[0032] (3) Preparation of polymer microspheres: First, the oil phase solution is heated at a low speed (3 kr·min) -1 Stir for 5 minutes, then slowly add the prepared aqueous polymer solution, and then stir at high speed (12 kr·min). -1 Shear emulsify for 5 min, place in a four-necked flask, and stir (300 rpm). -1 Nitrogen gas was passed through the bottle to purge the air. After 30 minutes, ammonium persulfate and sodium bisulfite were added dropwise. The mixture was heated in a water bath (65 °C) until the solution became a white, homogeneous emulsion. The product was washed with a large amount of ethanol solution, cured with acetone, and dried in a vacuum drying oven at 50 °C until constant weight was obtained to obtain functional polymer microspheres I1.

[0033] Formula III1 Formula IV The functional monomer (III1) was prepared by the following process: 217 g of 1-hydroxy-2,5-dioxopyrrolidine-3-sulfonic acid was placed in a 1500 ml single-necked flask, and 4% by mass of potassium iodide catalyst and 500 ml of acetonitrile solution were added. The temperature was lowered to 5 °C, and 147.6 g of bromopropane solution was added. The reaction was carried out at room temperature for 24 h, and then the temperature was raised to 70 °C and the reaction was carried out for 72 h. The product was dried by rotary evaporation and recrystallized three times by diethyl ether to obtain a white quaternary ammonium salt solid powder for later use. 238 g of white quaternary ammonium salt solid powder and 500 ml of chloroform solution were added to a 1500 ml single-necked flask. 4-Dimethylaminopyridine was added as a catalyst, and 98.4 g of sodium acetate solution was added as an acid-binding agent. The mixture was kept in an ice bath at a temperature below 5 °C. A chloroform solution containing 122.6 g of butenyl acyl chloride was slowly added dropwise to the flask using a constant-pressure dropping funnel. After the addition was complete, the reaction was allowed to proceed at room temperature for 24 h, and then at 40 °C for 48 h. The product was evaporated to dryness using a rotary evaporator, and then dissolved completely in dichloroform solution. The product was washed three times with saturated brine, allowed to stand for separation, and the aqueous phase was filtered off. The oil phase was dried with anhydrous magnesium sulfate, filtered, and the solvent was removed below 40 °C to obtain an oily liquid. The oily liquid was dissolved in ethanol, stirred thoroughly, and the insoluble matter was filtered off. The product was then purified by recrystallization three times using ethanol-diethyl ether. The solid product was filtered and dried, yielding the amphoteric hydrophobic ionic monomer (Formula III1).

[0034] The crosslinking agent (Formula IV) (which is applicable to Examples 1-5) is prepared by the following process: 270g of 2,5-dihydroxy-1,3-benzenedisulfonic acid solution and 500ml of chloroform solution are added to a 1500ml single-necked flask. 4-Dimethylaminopyridine catalyst is added, and the acid binder is a solution containing 98.4g of sodium acetate. Under ice bath conditions, the temperature is controlled below 5℃. An excess of 199.1g of chloroform solution containing acryloyl chloride is slowly added dropwise to the flask through a constant pressure dropping funnel. After the addition is complete, the reaction is carried out at room temperature for 24h, and then at 40℃ for 48h. The product is dried by rotary evaporation, and then dichloroform solution is added to fully dissolve it. The product is washed three times with saturated brine, allowed to stand and separate into layers, and the aqueous phase is filtered off. The oil phase is dried with anhydrous magnesium sulfate, filtered, and the solvent is removed below 40℃ to obtain an oily liquid. The oily liquid is redissolved in ethanol, stirred thoroughly, and the insoluble matter is filtered off. The solvent is removed below 40°C to obtain the crosslinking agent (Formula IV).

[0035] Example 2: A polymer microsphere emulsion for regulating and driving, by weight percentage, comprises 25% functional polymer microspheres I2, 1% thickener sodium starch phosphate, 1% cationic surfactant cholestyramine, 1% sodium chloride, 1% potassium chloride, and the balance being water. Its preparation method is as follows: the thickener, cationic surfactant, and salt are mixed and added to an aqueous solution of functional polymer microspheres I2, and stirred until homogeneous to obtain polymer microsphere emulsion A2.

[0036] Among them, the functional polymer microspheres I2 (x = 1, y = 7) are cross-linked polymers, and their structure is shown in the simplified formula:

[0037] In equation I2, m, t, r, s, p, q, w, and z take positive integers from 0 to 200.

[0038] The functional polymer microspheres I2 are prepared by the following process: synthesized by reverse emulsion polymerization. The specific synthesis method is as follows, based on 100g of the polymer emulsion used to prepare the polymer microspheres: (1) Preparation of the aqueous phase of the polymer: Weigh 8g of functional monomer (III2) and dissolve it in deionized water. Add an appropriate amount of NaOH to adjust the solution to neutral. Add 20g of polymer structural monomer acrylamide (AM), 0.5g of crosslinking agent (IV) and 0.08g of complexing agent disodium ethylenediaminetetraacetate. Stir with a glass rod until completely dissolved to obtain 55g of polymer aqueous phase solution.

[0039] (2) Preparation of polymer oil phase: Measure 30g of white oil into a beaker, adjust the addition ratio according to the HLB values ​​of 10g Span80 and 5g Tween80, and stir appropriately to obtain 45g of homogeneous and stable oil phase solution.

[0040] (3) Preparation of polymer microspheres: First, the oil phase solution is heated at a low speed (3 kr·min) -1 Stir for 5 minutes, then slowly add the prepared aqueous polymer solution, and then stir at high speed (12 kr·min). -1 Shear emulsify for 5 min, place in a four-necked flask, and stir (300 rpm). -1 Nitrogen gas was passed through the bottle to purge the air. After 30 minutes, ammonium persulfate and sodium bisulfite were added dropwise. The mixture was heated in a water bath (65 °C) until the solution became a white, homogeneous emulsion. The product was washed with a large amount of ethanol solution, cured with acetone, and dried in a vacuum drying oven at 50 °C until constant weight was obtained to obtain functional polymer microspheres I2.

[0041] Formula III2 The functional monomer (III2) was prepared by the following process: 217 g of 1-hydroxy-2,5-dioxopyrrolidine-3-sulfonic acid was placed in a 1500 ml single-necked flask, and 4% by mass of potassium iodide catalyst and 500 ml of acetonitrile solution were added. The temperature was lowered to 5 °C, and 231.6 g of bromooctane solution was added. The reaction was carried out at room temperature for 24 h, and then the temperature was raised to 70 °C and the reaction was carried out for 72 h. The product was dried by rotary evaporation and recrystallized three times by diethyl ether to obtain a white quaternary ammonium salt solid powder for later use. 308 g of white quaternary ammonium salt solid powder and 500 ml of chloroform solution were added to a 1500 ml single-necked flask. 4-Dimethylaminopyridine was added as a catalyst, and 98.4 g of sodium acetate solution was added as an acid binder. The mixture was kept in an ice bath at a temperature below 5 °C. A chloroform solution containing 122.6 g of butenyl acyl chloride was slowly added dropwise to the flask using a constant-pressure dropping funnel. After the addition was complete, the reaction was allowed to proceed at room temperature for 24 h, and then at 40 °C for 48 h. The product was evaporated to dryness using a rotary evaporator, and then dissolved completely in dichloroform solution. The product was washed three times with saturated brine, allowed to stand for separation, and the aqueous phase was filtered off. The oil phase was dried with anhydrous magnesium sulfate, filtered, and the solvent was removed below 40 °C to obtain an oily liquid. The oily liquid was dissolved in ethanol, stirred thoroughly, and the insoluble matter was filtered off. The product was then purified by recrystallization three times using ethanol-diethyl ether. The solid product was filtered and dried, yielding the functional monomer (Formula III2).

[0042] Example 3: A polymer microsphere emulsion for regulating and driving, by weight percentage, comprises 30% functional polymer microspheres I3, 2% thickener polyvinylpyrrolidone, 5% cationic surfactant cholestyramine, 0.5% ammonium chloride, and the balance being water. Its preparation method is as follows: the thickener, cationic surfactant, and salt are mixed and added to an aqueous solution of functional polymer microspheres I3, and stirred until homogeneous to obtain polymer microsphere emulsion A3.

[0043] Among them, the functional polymer microspheres I3 (x = 0, y = 7) are cross-linked polymers, and their structure is shown in the simplified formula:

[0044] In Equation I3, m, t, r, s, p, q, w, and z take positive integers from 0 to 200.

[0045] The functional polymer microspheres I3 are prepared by the following process: synthesized by reverse emulsion polymerization. The specific synthesis method is as follows, based on 100g of the polymer emulsion used to prepare the polymer microspheres: (1) Preparation of polymer aqueous phase: Weigh 10g of functional monomer (III3) and dissolve it in deionized water. Add an appropriate amount of NaOH to adjust the solution to neutral. Add 10g of polymer structural monomer acrylamide (AM), 0.8g of crosslinking agent (IV) and 0.1g of complexing agent disodium ethylenediaminetetraacetate. Stir with a glass rod until completely dissolved to obtain 40g of polymer aqueous phase solution.

[0046] (2) Preparation of polymer oil phase: Measure 45g of white oil into a beaker, adjust the addition ratio according to the HLB values ​​of 10g Span80 and 5g Tween80, and stir appropriately to obtain 60g of homogeneous and stable oil phase solution.

[0047] (3) Preparation of polymer microspheres: First, the oil phase solution is heated at a low speed (3 kr·min) -1 Stir for 5 minutes, then slowly add the prepared aqueous polymer solution, and then stir at high speed (12 kr·min). -1 Shear emulsify for 5 min, place in a four-necked flask, and stir (300 rpm). -1 Nitrogen gas was passed through the bottle to purge air. After 30 minutes, ammonium persulfate and sodium bisulfite were added dropwise. The mixture was heated in a water bath (65 °C) until the solution became a white, homogeneous emulsion. The product was washed with a large amount of ethanol solution, cured with acetone, and dried in a vacuum drying oven at 50 °C until constant weight was obtained to obtain functional polymer microspheres I3.

[0048] Formula III3 The functional monomer (III3) was prepared by the following process: 217 g of 1-hydroxy-2,5-dioxopyrrolidine-3-sulfonic acid was placed in a 1500 ml single-necked flask, and 4% by mass of potassium iodide catalyst and 500 ml of acetonitrile solution were added. The temperature was lowered to 5 °C, and 231.6 g of bromooctane solution was added. The reaction was carried out at room temperature for 24 h, and then the temperature was raised to 70 °C and the reaction was carried out for 72 h. The product was dried by rotary evaporation and recrystallized three times by diethyl ether to obtain a white quaternary ammonium salt solid powder for later use. 308 g of white quaternary ammonium salt solid powder and 500 ml of chloroform solution were added to a 1500 ml single-necked flask. 4-Dimethylaminopyridine was added as a catalyst, and 98.4 g of sodium acetate solution was added as an acid-binding agent. The mixture was kept in an ice bath at a temperature below 5 °C. A chloroform solution containing 108.6 g of acryloyl chloride was slowly added dropwise to the flask using a constant-pressure dropping funnel. After the addition was complete, the reaction was allowed to proceed at room temperature for 24 h, and then at 40 °C for 48 h. The product was evaporated to dryness using a rotary evaporator, and then dissolved completely in dichloroform solution. The product was washed three times with saturated brine, allowed to stand for separation, and the aqueous phase was filtered off. The oil phase was dried with anhydrous magnesium sulfate, filtered, and the solvent was removed below 40 °C to obtain an oily liquid. The oily liquid was dissolved in ethanol, stirred thoroughly, and the insoluble matter was filtered off. The product was then purified by recrystallization three times using ethanol-diethyl ether. The solid product was filtered and dried to obtain the functional monomer (Formula III3).

[0049] Example 4: A polymer microsphere emulsion for regulating and driving, by weight percentage, comprises 12% functional polymer microspheres I4, 0.5% sodium carboxymethyl cellulose thickener, 6% cationic surfactant cholestyramine, 1% potassium chloride, 1% ammonium chloride, and the balance being water. Its preparation method is as follows: the thickener, cationic surfactant, and salt are mixed and added to an aqueous solution of functional polymer microspheres I4, and stirred until homogeneous to obtain polymer microsphere emulsion A4.

[0050] Among them, the functional polymer microspheres I4 (x = 1, y = 7) are cross-linked polymers, and their structure is shown in the simplified formula:

[0051] In Equation I4, m, t, r, s, p, q, w, and z take positive integers from 0 to 200.

[0052] The functional polymer microspheres I4 are prepared by the following process: synthesized by reverse emulsion polymerization. The specific synthesis method is as follows, based on 100g of the polymer emulsion used to prepare the polymer microspheres: (1) Preparation of polymer aqueous phase: Weigh 8g of functional monomer (III4) and dissolve it in deionized water. Add an appropriate amount of NaOH to adjust the solution to neutral. Add 25g of polymer structural monomer acrylamide (AM), 0.4g of crosslinking agent (IV) and 0.06g of complexing agent disodium ethylenediaminetetraacetate. Stir with a glass rod until completely dissolved to obtain 40g of polymer aqueous phase solution.

[0053] (2) Preparation of polymer oil phase: Measure 32g of white oil into a beaker, adjust the addition ratio according to the HLB values ​​of 20g Span80 and 8g Tween80, and stir appropriately to obtain 60g of homogeneous and stable oil phase solution.

[0054] (3) Preparation of polymer microspheres: First, the oil phase solution is heated at a low speed (3 kr·min) -1 Stir for 5 minutes, then slowly add the prepared aqueous polymer solution, and then stir at high speed (12 kr·min). -1 Shear emulsify for 5 min, place in a four-necked flask, and stir (300 rpm). -1 Nitrogen gas was passed through the bottle to purge the air. After 30 minutes, ammonium persulfate and sodium bisulfite were added dropwise. The mixture was heated in a water bath (65 °C) until the solution became a white, homogeneous emulsion. The product was washed with a large amount of ethanol solution, cured with acetone, and dried in a vacuum drying oven at 50 °C until constant weight was obtained to obtain functional polymer microspheres I4.

[0055] Formula III4 The functional monomer (III4) was prepared by the following process: 217 g of 1-hydroxy-2,5-dioxopyrrolidine-3-sulfonic acid was placed in a 1500 ml single-necked flask, and 4% by mass of potassium iodide catalyst and 500 ml of acetonitrile solution were added. The temperature was lowered to 5 °C, and 231.6 g of bromooctane solution was added. The reaction was carried out at room temperature for 24 h, and then the temperature was raised to 70 °C and the reaction was carried out for 72 h. The product was dried by rotary evaporation and recrystallized three times by diethyl ether to obtain a white quaternary ammonium salt solid powder for later use. 308 g of white quaternary ammonium salt solid powder and 500 ml of chloroform solution were added to a 1500 ml single-necked flask. 4-Dimethylaminopyridine catalyst and 98.4 g of sodium acetate solution were added as acid binder. The mixture was kept in an ice bath at a temperature below 5 °C. A chloroform solution containing 122.6 g of butenyl acyl chloride was slowly added dropwise to the flask using a constant-pressure dropping funnel. After the addition was complete, the reaction was allowed to proceed at room temperature for 24 h, then at 40 °C for 48 h. The product was evaporated to dryness using a rotary evaporator, and then dissolved completely in dichloroform solution. The product was washed three times with saturated brine, allowed to stand for separation, and the aqueous phase was filtered off. The oil phase was dried with anhydrous magnesium sulfate, filtered, and the solvent was removed below 40 °C to obtain an oily liquid. The oily liquid was dissolved in ethanol, stirred thoroughly, and the insoluble matter was filtered off. The product was then purified by recrystallization three times using ethanol-diethyl ether. The solid product was filtered and dried, yielding the functional monomer (Formula III4).

[0056] Example 5: A polymer microsphere emulsion for regulating and driving, by weight percentage, comprises 16% functional polymer microspheres I5, 2.2% sodium alginate thickener, 7.5% cationic surfactant cholestyramine, 0.5% sodium chloride salt, 1% quaternary ammonium salt, and the balance being water. Its preparation method is as follows: the thickener, cationic surfactant, and salt are mixed and added to an aqueous solution of functional polymer microspheres I5, and stirred until homogeneous to obtain polymer microsphere emulsion A5.

[0057] Among them, the functional polymer microspheres I5 (x = 2, y = 4) are cross-linked polymers, and their structure is shown in the simplified formula:

[0058] In Equation I5, m, t, r, s, p, q, w, and z take positive integers from 0 to 200.

[0059] The functional polymer microspheres I5 are prepared by the following process: synthesized by reverse emulsion polymerization. The specific synthesis method is as follows, based on 100g of the polymer emulsion used to prepare the polymer microspheres: (1) Preparation of the aqueous phase of the polymer: Weigh 10g of functional monomer (III5) and dissolve it in deionized water. Add an appropriate amount of NaOH to adjust the solution to neutral. Add 22g of polymer structural monomer acrylamide (AM), 0.65g of crosslinking agent (IV) and 0.09g of complexing agent disodium ethylenediaminetetraacetate. Stir with a glass rod until completely dissolved to obtain 50g of the aqueous phase solution of the polymer.

[0060] (2) Preparation of polymer oil phase: Measure 37g of white oil into a beaker, adjust the addition ratio according to the HLB values ​​of 10g Span80 and 3g Tween80, and stir appropriately to form 50g of homogeneous and stable oil phase solution.

[0061] (3) Preparation of polymer microspheres: First, the oil phase solution is heated at a low speed (3 kr·min) -1 Stir for 5 minutes, then slowly add the prepared aqueous polymer solution, and then stir at high speed (12 kr·min). -1 Shear emulsify for 5 min, place in a four-necked flask, and stir (300 rpm). -1 Nitrogen gas was passed through the bottle to purge the air. After 30 minutes, ammonium persulfate and sodium bisulfite were added dropwise. The mixture was heated in a water bath (65 °C) until the solution became a white, homogeneous emulsion. The product was washed with a large amount of ethanol solution, cured with acetone, and dried in a vacuum drying oven at 50 °C until constant weight was obtained to obtain functional polymer microspheres I5.

[0062] Formula III5 The functional monomer (III5) was prepared by the following process: 217 g of 1-hydroxy-2,5-dioxopyrrolidine-3-sulfonic acid was placed in a 1500 ml single-necked flask, and 4% by mass of potassium iodide catalyst and 500 ml of acetonitrile solution were added. The temperature was lowered to 5 °C, and 181.2 g of bromopentane solution was added. The reaction was carried out at room temperature for 24 h, and then the temperature was raised to 70 °C and the reaction was carried out for 72 h. The product was dried by rotary evaporation and recrystallized three times by diethyl ether to obtain a white quaternary ammonium salt solid powder for later use. 266 g of white quaternary ammonium salt solid powder and 500 ml of chloroform solution were added to a 1500 ml single-necked flask. 4-Dimethylaminopyridine was added as a catalyst, and 98.4 g of sodium acetate solution was added as an acid-binding agent. The mixture was kept in an ice bath at a temperature below 5 °C. A chloroform solution containing 141.6 g of pentenoyl chloride was slowly added dropwise to the flask using a constant-pressure dropping funnel. After the addition was complete, the reaction was allowed to proceed at room temperature for 24 h, and then at 40 °C for 48 h. The product was evaporated to dryness using a rotary evaporator, and then dissolved completely in dichloroform solution. The product was washed three times with saturated brine, allowed to stand for separation, and the aqueous phase was filtered off. The oil phase was dried using anhydrous magnesium sulfate, filtered, and the solvent was removed below 40 °C to obtain an oily liquid. The oily liquid was dissolved in ethanol, stirred thoroughly, and the insoluble matter was filtered off. The product was then purified by recrystallization three times using ethanol-diethyl ether. The solid product was filtered and dried, yielding the functional monomer (Formula III5).

[0063] Effect Experiment The polymer microsphere emulsions from Examples 1-5 were taken and their appearance, density, dispersion performance, separable solids, morphology of separable solids, initial particle size (D50), viscosity, capillary viscosity of dispersion, and sulfur content were measured according to national standards GB / T 4472-2011, GB / T 6682-2008, industry standards SN / T 3005-2011, SY / T 5862-2020, and Jiangxi Lianshi Environmental Protection Technology Co., Ltd.'s enterprise standard Q / JXLS 007-2022. The results are shown in Table 1. Based on the comparison with the indicators of Jiangxi Lianshi Environmental Protection Technology Co., Ltd.'s enterprise standard Q / JXLS 007-2022, from the appearance perspective, examples A1-A4 meet the standard, while A5 presents as a milky white liquid, failing to meet the appearance requirements. Regarding density, all examples of polymer microsphere emulsions meet the standard. In terms of dispersibility, examples A1 and A5 exhibit poor dispersibility with flocculent matter, while other examples meet the requirements. Regarding separable solids, example A1 is below the 23% standard, and the separable solids of A1 and A5 are clumped together, failing the standard, while other examples meet the standard. Regarding particle size, only A3 and A4 meet the standard (80≤D50<130). Regarding viscosity and sulfur content, all examples meet the standard. Through comparison of all indicators, example 4 is the preferred formulation among the five examples, meeting the standard. Table 1 shows the performance of the polymer microsphere emulsion for driving and regulation.

[0064] The present invention will be further described in detail below through specific embodiment 4. Embodiment 4 is only descriptive and not limiting, and cannot be used to limit the scope of protection of the present invention.

[0065] The viscosity reduction ratio (VRR) is used to evaluate the viscosity-reducing ability of polymer microemulsions for heavy oil.

[0066]

[0067] In this formula, η0 is the initial viscosity of the heavy oil, η e The viscosity of the heavy oil after the addition of the blended emulsion.

[0068] A sample of heavy oil (density 0.94 g·cm³ at 25℃) was taken at 60℃. 3A mixture of 11200 mPa·s (viscosity 11200 mPa·s, surface tension 39 mN / m) and white oil at a volume ratio of 6:1, totaling 30 mL, yielded a heavy oil sample for testing. The apparent viscosity was measured to be 4300 mPa·s using a rotational viscometer, and the oil-water interfacial tension was measured to be 86.0 mN / m using the ring method. The test emulsion was added dropwise to the above heavy oil sample, stirred thoroughly, and the apparent viscosity and oil-water interfacial tension were tested multiple times. In Example 4, when 3.0 mL of emulsion was added, the viscosity of the heavy oil sample decreased from 4300 mPa·s to 2000 mPa·s, a viscosity reduction rate of 53%. The oil-water interfacial tension decreased from the initial 86.0 mN / m to 30.7 mN / m, a reduction of 64.3%. Figure 1 , 2 As shown.

[0069] The above description is merely a preferred embodiment of the present invention. The present invention is not limited to the above-described embodiments. Any embodiment that achieves the technical effects of the present invention using the same means should fall within the protection scope of the present invention. Within the protection scope of the present invention, various modifications and variations can be made to the technical solutions and / or implementation methods.

Claims

1. A polymer microsphere emulsion for modulating and driving, characterized in that: By weight percentage, the polymer microsphere emulsion consists of 10-30% functional polymer microspheres, 0.5%-3% thickener, 1%-8% cholestyramine, 0%-2% salt, and the balance being water. The functional polymer microspheres are cross-linked polymers, and their structure is shown in simplified formula I: Equation I, Where x is any integer from 0 to 3; y is any integer from 0 to 7; m, t, r, s, p, q, w, z are positive integers from 0 to 200; x and y are not 0; The structural formula of the cholestyramine is shown in Formula II below: In Equation II, n takes any integer from 2 to 200.

2. The polymer microsphere emulsion for modulating and driving according to claim 1, characterized in that: The thickener is one or a combination of several of sodium carboxymethyl cellulose, sodium starch phosphate, sodium alginate, and polyvinylpyrrolidone.

3. The polymer microsphere emulsion for modulating displacement according to claim 1, characterized in that: The salt includes one or a combination of several of sodium chloride, potassium chloride, ammonium chloride, and quaternary ammonium salts.

4. A method for preparing a polymer microsphere emulsion for modulating displacement as described in any one of claims 1-3, characterized in that, The process includes the following steps: mixing a thickener, cholestyramine, and salt, then adding the mixture to an aqueous solution of functional polymer microspheres and stirring until homogeneous to obtain a polymer microsphere emulsion; The functional polymer microspheres are prepared by the following methods, based on the weight percentage of the polymer emulsion used to prepare the polymer microspheres: (1) Preparation of the aqueous phase of the polymer: Weigh 1%-10% of functional monomer III and dissolve it in deionized water. Add an appropriate amount of NaOH to adjust the solution to neutral. Add 10%-30% of polymer structural monomer acrylamide (AM), 0.1%-1% of crosslinking agent IV and 0.05%-0.1% of complexing agent disodium ethylenediaminetetraacetate. Stir with a glass rod until completely dissolved to obtain a polymer aqueous phase solution of 40%-60%. (2) Preparation of polymer oil phase: Measure an appropriate amount of white oil (30%-50%) into a beaker, adjust the addition ratio according to the HLB values ​​of Span80 (10%-20%) and Tween80 (1%-8%), and stir appropriately to form a homogeneous and stable oil phase solution of 40%-60%; (3) Preparation of polymer microspheres: First, the oil phase solution was heated at 3 kr·min -1 Stir for 5 minutes, then slowly add the prepared aqueous polymer solution, and then stir at a high speed of 12 kr·min. -1 Shear emulsify for 5 min, then transfer to a four-necked flask and stir at 300 rpm. -1 Nitrogen gas was passed through the bottle to purge the air. After 30 minutes, ammonium persulfate and sodium bisulfite were added dropwise. The mixture was heated in a water bath at 65°C until the solution became a white, homogeneous emulsion. The product was washed with ethanol solution, cured with acetone, and dried in a vacuum oven at 50°C until constant weight to obtain polymer microspheres. In Equation III, x takes any integer from 0 to 3; y takes any integer from 0 to 7; and neither x nor y is 0. Formula IV.

5. The preparation method according to claim 4, characterized in that, The functional monomer III is prepared by the following method: 1-Hydroxy-2,5-dioxopyrrolidine-3-sulfonic acid was placed in a 1500 ml single-necked flask, along with 4% (w / w) potassium iodide catalyst and 500 ml acetonitrile solution. The temperature was lowered to 5°C, and a solution of bromoalkane was added. The reaction was carried out at room temperature for 24 h, then the temperature was raised to 70°C and reacted for 72 h. The product was evaporated to dryness and recrystallized three times from diethyl ether to obtain a white quaternary ammonium salt solid powder, formula V, which was set aside. In another 1500 ml single-necked flask, white quaternary ammonium salt solid powder, formula V, and 500 ml chloroform solution were added, along with 4-dimethylaminopyridine catalyst and sodium acetate solution as the acid binder. The reaction was carried out under ice bath conditions, with the temperature controlled below 5°C. A solution of alkenyl acyl chloride in chloroform was slowly added dropwise to a flask using a constant pressure dropping funnel. After the addition was complete, the mixture was allowed to react at room temperature for a period of time, and then reacted at 40°C for 48 hours. The product was dried by rotary evaporation, and then dissolved completely in dichloroform. The product was washed multiple times with saturated brine, allowed to stand and separate into layers, and the aqueous phase was filtered off. The oil phase was dried with anhydrous magnesium sulfate, filtered, and the solvent was removed below 40°C to obtain an oily liquid. The oily liquid was dissolved in ethanol, stirred thoroughly, and the insoluble matter was filtered off. The product was then purified by recrystallization three times using ethanol-diethyl ether. The solid product was filtered and dried to obtain an amphoteric hydrophobic ionic monomer, i.e., functional monomer III. In equation V, y is any integer from 0 to 7, and y is not 0.

6. The preparation method according to claim 4, characterized in that, The crosslinking agent IV is prepared by the following method: In a 1500 ml single-necked flask, add 2,5-dihydroxy-1,3-benzenedisulfonic acid solution and 500 ml chloroform solution, add 4-dimethylaminopyridine catalyst, and sodium acetate solution as acid binder. Under ice bath conditions, the temperature is controlled below 5°C. Take an excess of alkenyl chloride chloroform solution and slowly add it dropwise to the flask through a constant pressure dropping funnel. After the addition is complete, react at room temperature for 24 h, and then react at 40°C for 48 h. After the product is dried by rotary evaporation, add dichloroform solution to dissolve it completely. Wash with saturated brine three times, let stand to separate the layers and filter off the aqueous phase. Take the oil phase and dry it with anhydrous magnesium sulfate. Filter and remove the solvent below 40°C to obtain an oily liquid. Redissolve the oily liquid in ethanol, stir thoroughly, filter off the insoluble matter, and remove the solvent below 40°C to obtain crosslinking agent IV. Formula IV.

7. The application of the polymer microsphere emulsion according to any one of claims 1-3 or the polymer microsphere emulsion prepared by the method according to any one of claims 4-6 in the stripping of oil at the interface of water, oil, and rock solids.

8. The polymer microsphere emulsion as described in any one of claims 1-3 or the polymer microsphere emulsion prepared by the method described in any one of claims 4-6 is used as an oilfield regulating agent for regulating and sealing geological reservoirs with water content and at the given temperature.

9. The polymer microsphere emulsion according to any one of claims 1-3 or the polymer microsphere emulsion prepared by the method according to any one of claims 4-6 is used to reduce the interfacial tension between the water and oil phases and to reduce the viscosity of heavy oil.

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