Polymer microsphere profile control agent, method of making and use thereof

Abstract

The application provides a polymer microsphere profile control agent and a preparation method and application thereof, wherein the polymer microsphere profile control agent comprises a core anionic polyacrylamide, a shell anionic hydrophobic association type polyacrylamide and an ionic crosslinking agent; the anionic polyacrylamide is prepared from acrylamide, an anionic monomer, a stable crosslinking agent and a water-soluble emulsifier; and the anionic hydrophobic association type polyacrylamide is prepared from acrylamide, acrylic acid, a surface active monomer and an unstable crosslinking agent. The polymer microsphere profile control agent can be coagulated / dispersed under different temperature or external force conditions, has good deep reservoir migration capacity, temperature resistance and salt resistance and injection property, and improves the plugging capacity of a super-high permeability dominant channel.

Description

Technical Field

[0001] This application relates to the field of oil and gas fields, and in particular to a polymer microsphere profile control agent, its preparation method, and its uses. Background Technology

[0002] During water injection development in oilfields, the problem of injected water flowing along high-permeability channels arises. Chemical profile control technology can be used to block these high-permeability layers, redirecting the fluid flow and improving oil recovery. Traditionally, chemical profile control employs in-situ cross-linked polymer gel systems to block dominant water flow channels. However, because the cross-linking reaction of in-situ cross-linked polymer gel systems occurs underground, the gelation process is affected by various complex conditions such as temperature, salinity, and shear. Under conditions of high temperature, high salinity, and strong shear, it is difficult to form gels with high strength and stability, hindering effective profile control operations. In contrast, the gelation process of polymer microsphere profile control systems is completed in a surface facility, allowing for precise and controllable gelation. Furthermore, its resistance to temperature, salt, and shear is significantly superior to that of in-situ cross-linked polymer gel systems. Therefore, it has been widely used in chemical profile control operations in recent years.

[0003] Polymer microspheres have a small initial particle size (typically in the nanometer to micrometer range), thus exhibiting good deep reservoir migration capabilities. However, due to their size limitations, when high-permeability channels have high permeability and large rock pore throats, polymer microspheres cannot seal these channels and ultimately flow out of the well along with the injected water. Therefore, the poor sealing ability of polymer microspheres in high-permeability water-dominant channels directly restricts their effectiveness in profile control operations in medium-to-high permeability reservoirs, a problem that remains unsolved. Summary of the Invention

[0004] To address the technical problem that polymer microspheres cannot block high-permeability channels with large rock pore throats, this invention provides a polymer microsphere profile control agent that can gradually aggregate at higher temperatures to form larger microsphere aggregates, thereby blocking large pores in high-permeability channels and preventing polymer microsphere migration. Simultaneously, the aggregation of the formed microsphere aggregates is reversible, thus maintaining the excellent deep reservoir migration capability of the polymer microspheres.

[0005] To achieve the above objectives, a first aspect of the present invention is to provide a polymer microsphere profile modifier, the polymer microsphere profile modifier comprising a core and a shell, wherein the core comprises anionic polyacrylamide and the shell comprises anionic hydrophobic associative polyacrylamide.

[0006] Furthermore, in some embodiments of the present invention, the outer shell further includes an ionic crosslinking agent.

[0007] Furthermore, in some embodiments of the present invention, the ionic crosslinking agent includes one or more of chromium acetate, aluminum citrate, and zirconium citrate.

[0008] Furthermore, some embodiments of the present invention provide a polymer microsphere profiler, wherein the anionic polyacrylamide is prepared from acrylamide, anionic monomer, a stabilizing crosslinking agent, and a water-soluble emulsifier; further, the acrylamide mass concentration includes 25-40% by weight, the anionic monomer mass concentration includes 10-30% by weight, the stabilizing crosslinking agent mass concentration includes 0.025-0.14% by weight, and the water-soluble emulsifier mass concentration includes 1.6%-4.8% by weight.

[0009] Furthermore, in some embodiments of the present invention, the anionic monomer is selected from one or both of acrylic acid or 2-acrylamide-2-methylpropanesulfonic acid.

[0010] Furthermore, in some embodiments of the present invention, the stabilizing crosslinking agent includes N,N'-methylenebisacrylamide; and / or the water-soluble emulsifier monomer is one or a mixture of two or more of Tween 60, Tween 80, OP-10, and Triton X100.

[0011] Furthermore, in some embodiments of the present invention, the anionic hydrophobic associative polyacrylamide is prepared from acrylamide, acrylic acid, surfactant monomer, and unstable crosslinking agent.

[0012] Furthermore, in some embodiments of the present invention, the acrylamide mass concentration includes 25-35% by weight, the acrylic acid mass concentration is 5-10% by weight, the surfactant monomer mass concentration includes 0.1-0.8% by weight, the unstable crosslinking agent mass concentration includes 0.30-1.25% by weight, and the ionic crosslinking agent mass concentration includes 0.10-5% by weight.

[0013] Furthermore, in some embodiments of the present invention, the surfactant monomer includes one or more of fatty alcohol polyoxyethylene ether acrylate, alkyl allyl dimethyl ammonium chloride, and sodium styrene sulfonate, and / or the unstable crosslinking agent includes polyethylene glycol diacrylate.

[0014] Furthermore, in some embodiments of the present invention, the particle size range of the polymer microsphere profile modifier includes 0.4–100 μm.

[0015] A second aspect of the present invention is to provide a method for preparing the above-mentioned polymer microsphere profile modifier, comprising the following steps:

[0016] a. Dissolve acrylamide, anionic monomer, stabilizing crosslinking agent, and water-soluble emulsifier in water to obtain a core solution;

[0017] b. Dissolve acrylamide, acrylic acid, surfactant monomer, and unstable crosslinking agent in water, then add an ionic crosslinking agent to dissolve and obtain the shell solution;

[0018] c. Dissolve the oil-soluble emulsifier in paraffin oil to obtain an oil-phase liquid;

[0019] d. The core solution and shell solution respectively react with the initiator solution in an oil phase to obtain a polymer microsphere profile control emulsion;

[0020] e. After demulsification, washing, and drying, the polymer microsphere profile modifier is obtained.

[0021] Furthermore, in the preparation methods of some embodiments of the present invention, the acrylamide mass concentration in the core solution includes 25-40% by weight, the anionic monomer mass concentration includes 10-30% by weight, the stabilizing crosslinking agent mass concentration includes 0.025-0.14% by weight, and the water-soluble emulsifier mass concentration includes 1.6%-4.8% by weight. The anionic monomer is one or both of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid, the stabilizing crosslinking agent is N,N'-methylenebisacrylamide, and the water-soluble emulsifier monomer is one or more of Tween 60, Tween 80, OP-10, and Triton X100.

[0022] Furthermore, in the preparation methods of some embodiments of the present invention, the mass concentration of acrylamide in the shell solution includes 25-35% by weight, the mass concentration of acrylic acid includes 5-10% by weight, the mass concentration of surfactant monomer includes 0.1-0.8% by weight, the mass concentration of unstable crosslinking agent includes 0.30-1.25% by weight, and the mass concentration of ionic crosslinking agent includes 0.10-5% by weight.

[0023] Furthermore, in the preparation methods of some embodiments of the present invention, the surfactant monomer is one or a mixture of two or more of fatty alcohol polyoxyethylene ether acrylate, alkyl allyl dimethyl ammonium chloride, and sodium styrene sulfonate; the unstable crosslinking agent is polyethylene glycol diacrylate; the ionic crosslinking agent is one of chromium acetate, aluminum citrate, and zirconium citrate; and / or the oil-soluble emulsifier is Span 80.

[0024] A third aspect of the present invention provides the application of the above-mentioned polymer microsphere profile control agent in oilfields.

[0025] Compared with the prior art, the polymer microsphere profile modifier of the present invention has at least the following advantages:

[0026] (1) It can gradually coalesce under temperature conditions above 40℃, and the coalescing into large aggregates can block the large pores in the high-permeability channel to prevent crossflow;

[0027] (2) The aggregation of aggregates is reversible. Under certain external force conditions, the microspheres that form aggregates can be redispersed. After a period of time, the redispersed microspheres can aggregate again. This feature gives the present invention good deep reservoir migration capability.

[0028] (3) It has good temperature and salt resistance, with salt resistance up to 200,000 mg / L and temperature resistance up to 120℃, and can be used for profile control operations in high-temperature and high-salt oil reservoirs;

[0029] (4) The initial particle size is in the submicron to micron range, and the viscosity of the aqueous dispersion is close to that of water, which gives it good injectability in medium- to high-permeability reservoirs. Attached Figure Description

[0030] Figure 1 This is a microscopic observation image of a polymer microsphere profile modifier according to an embodiment of the present invention. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with specific embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] It should be noted that, in this application, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0033] In this application, "a" and "an" have the meaning of "one or more". In the description of this application, unless otherwise stated, numerical ranges generally include endpoints. Furthermore, it should be understood that all values ​​within the numerical range are within the scope of protection of this invention.

[0034] In some embodiments of the present invention, a polymer microsphere profiler is provided, the polymer microsphere profiler comprising a core and a shell, wherein the core comprises anionic polyacrylamide and the shell comprises anionic hydrophobic associative polyacrylamide.

[0035] In some embodiments of the present invention, the anionic polyacrylamide includes a stabilized anionic polyacrylamide; in other embodiments of the present invention, the anionic polyacrylamide is prepared from acrylamide, an anionic monomer, a stabilizing crosslinking agent, and a water-soluble emulsifier; further, the acrylamide mass concentration includes 25-40% by weight, the anionic monomer mass concentration includes 10-30% by weight, the stabilizing crosslinking agent mass concentration includes 0.025-0.14% by weight, and the water-soluble emulsifier mass concentration includes 1.6%-4.8% by weight.

[0036] In some embodiments of the present invention, the anionic monomer includes one or two of acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid, the stabilizing crosslinking agent includes N,N'-methylenebisacrylamide, and the water-soluble emulsifier monomer includes one or a mixture of two or more of Tween 60, Tween 80, OP-10, and Triton X100.

[0037] In some embodiments of the present invention, the anionic hydrophobic associative polyacrylamide is prepared from acrylamide, acrylic acid, a surfactant monomer, and an unstable crosslinking agent. In other embodiments of the present invention, the surfactant monomer includes one or more of fatty alcohol polyoxyethylene ether acrylate, alkyl allyl dimethyl ammonium chloride, and sodium styrene sulfonate; in still other embodiments of the present invention, the unstable crosslinking agent includes polyethylene glycol diacrylate.

[0038] Furthermore, in some embodiments of the present invention, the acrylamide mass concentration includes 25-35% by weight, the acrylic acid mass concentration is 5-10% by weight, the surfactant monomer mass concentration includes 0.1-0.8% by weight, the unstable crosslinking agent mass concentration includes 0.30-1.25% by weight, and the ionic crosslinking agent mass concentration includes 0.10-5% by weight.

[0039] In some embodiments of the present invention, the outer shell further includes an ionic crosslinking agent, which is added to the outer shell solution in solution form and crosslinks with the anionic polyacrylamide to form a three-dimensional network structure; preferably, in some embodiments of the present invention, the ionic crosslinking agent includes one or more of chromium acetate, aluminum citrate, and zirconium citrate.

[0040] In some embodiments of the present invention, the particle size range of the polymer microsphere profile modifier includes 0.4 to 100 μm, preferably 0.4 to 10 μm.

[0041] This invention also provides a method for preparing the above-mentioned polymer microsphere profile modifier, comprising the following steps:

[0042] a. Dissolve acrylamide, anionic monomer, stabilizing crosslinking agent, and water-soluble emulsifier in water to obtain a core solution;

[0043] b. Dissolve acrylamide, acrylic acid, surfactant monomer, and unstable crosslinking agent in water, then add an ionic crosslinking agent to dissolve and obtain the shell solution;

[0044] c. Dissolve the oil-soluble emulsifier in paraffin oil to obtain an oil-phase liquid;

[0045] d. The core solution and shell solution respectively react with the initiator solution in an oil phase to obtain a polymer microsphere profile control emulsion;

[0046] e. After demulsification, washing, and drying, the polymer microsphere profile modifier is obtained.

[0047] Furthermore, in the preparation method of the polymer microsphere profile modifier in some embodiments of the present invention, the acrylamide mass concentration in the core solution includes 25-40% by weight, the anionic monomer mass concentration includes 10-30% by weight, the stabilizing crosslinking agent mass concentration includes 0.025-0.14% by weight, and the water-soluble emulsifier mass concentration includes 1.6%-4.8% by weight. The anionic monomer is one or both of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid, the stabilizing crosslinking agent is N,N'-methylenebisacrylamide, and the water-soluble emulsifier monomer is one or more of Tween 60, Tween 80, OP-10, and Triton X100.

[0048] Furthermore, in the preparation method of the polymer microsphere profile modifier in some embodiments of the present invention, the acrylamide mass concentration in the shell solution includes 25-35% by weight, the acrylic acid mass concentration includes 5-10% by weight, the surfactant monomer mass concentration includes 0.1-0.8% by weight, and the unstable crosslinking agent mass concentration includes 0.30-1.25% by weight; wherein the surfactant monomer is one or a mixture of two or more of fatty alcohol polyoxyethylene ether acrylate, alkyl allyl dimethyl ammonium chloride, and sodium styrene sulfonate, the unstable crosslinking agent is polyethylene glycol diacrylate, and / or the oil-soluble emulsifier is Span 80.

[0049] Furthermore, in some embodiments of the present invention, the preparation method of the polymer microsphere profile control agent includes the addition of an ionic crosslinking agent to the shell solution, wherein the mass concentration of the ionic crosslinking agent is 0.10–5% by weight. In other embodiments of the present invention, the preparation method of the polymer microsphere profile control agent includes one of chromium acetate, aluminum citrate, and zirconium citrate. In other embodiments of the present invention, the preparation method includes dissolving acrylamide, acrylic acid, a surfactant monomer, and an unstable crosslinking agent in water, adjusting the pH to neutral, and then adding an ionic crosslinking agent to the solution to dissolve and obtain a shell solution. The shell solution contains an acrylamide mass concentration of 25–35%, an acrylic acid mass concentration of 5–10%, a surfactant monomer mass concentration of 0.1–0.8%, an unstable crosslinking agent mass concentration of 0.30–1.25%, and an ionic crosslinking agent mass concentration of 0.10–5%.

[0050] Furthermore, in the preparation method of the polymer microsphere profile modifier in some embodiments of the present invention, the oil-soluble emulsifier is Span 80.

[0051] Furthermore, in the preparation method of the polymer microsphere profile modifier in some embodiments of the present invention, in step d, the oil phase liquid is added to the reactor, and 4 / 5 part of the core solution is added dropwise while mechanically stirring at 800 r / min. After the addition is completed, stirring is continued for 30 min, then the stirring speed is reduced to 300-400 r / min, nitrogen gas is purged into the three-necked flask for 30 min, then the temperature is raised to 60°C, and the initiator solution is added dropwise to initiate the reaction. After the reaction is completed for 40 min, the remaining 1 / 5 part of the core solution is added dropwise to the reactor. After the addition is completed, the shell solution is added dropwise to the reactor. After the shell solution is added dropwise, the initiator solution is added dropwise, and the reaction is terminated after 6 h.

[0052] Furthermore, in the preparation method of the polymer microsphere profile modifier in some embodiments of the present invention, the volume ratio of the oil phase liquid to the total aqueous solutions of the core and shell is 5:5 to 7:3, the initiator solution is a 1% (w / w) ammonium persulfate solution, the amount of ammonium persulfate added to the core solution is 0.05% to 0.30% of the total mass of acrylamide and anionic monomers, and the amount of ammonium persulfate added to the shell solution is 0.04% to 0.22% of the total mass of acrylamide, acrylic acid, and surfactant monomers.

[0053] Furthermore, in the preparation method of the polymer microsphere profile modifier in some embodiments of the present invention, in step e, the reacted emulsion is poured into an organic solvent, such as anhydrous ethanol at 10 times or more the volume of the emulsion to break the emulsion, the precipitate is washed with anhydrous ethanol and dried to obtain the polymer microsphere profile modifier product.

[0054] Furthermore, in some embodiments of the present invention, the particle size range of the polymer microsphere profile modifier is 0.4–100 μm, preferably 0.4–10 μm.

[0055] The following description, in conjunction with specific embodiments, further illustrates the specific implementation of the present invention, but does not limit the invention to the scope of the described embodiments. It should be understood that the endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values; the ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of various ranges, the endpoint values ​​of various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered as part of the technical solution of this invention.

[0056] [Expansion Rate Determination]: Accurately weigh 1.0 g of dried, finely ground polymer microsphere profile control agent and place it in a 500 mL beaker. Then add 450 mL of water or salt water and allow the polymer microspheres to fully absorb water at room temperature until they are saturated. Filter the unabsorbed water using a cloth bag until there are virtually no water droplets. Measure the weight of the polymer microsphere gel after it has fully absorbed water and calculate the expansion rate according to formula (1).

[0057] Expansion rate = (m2-m1) / m1×100% (1)

[0058] m1: Mass of the polymer microspheres before water absorption, in grams

[0059] m2: Mass of the polymer microsphere gel after water absorption, in grams

[0060] The initial particle size distribution of the microspheres was determined using a Malvern Mastersize2000 laser particle size analyzer. Anhydrous ethanol was used as the dispersion medium during the measurement to prevent the polymer microspheres from absorbing water and swelling, which would affect the test results. The aggregation performance of the polymer microspheres was tested using a static in-bottle experiment. When the polymer microspheres aggregated in the bottle and no liquid flowed down when the bottle was inverted, it was determined that the polymer microspheres had aggregated.

[0061] Example 1

[0062] 10g acrylamide, 2g acrylic acid, 3g 2-acrylamide-2-methylpropanesulfonic acid, 0.045g N,N'-methylenebisacrylamide, and 0.8g Tween 60 were dissolved in 25g water, and the pH was adjusted to neutral to obtain the core solution. 5g acrylamide, 1g acrylic acid, 0.1g fatty alcohol polyoxyethylene ether acrylate, and 0.06g polyethylene glycol diacrylate were dissolved in 12g water, and the pH was adjusted to neutral. Then, 0.1g chromium acetate was added to the solution to obtain the shell solution. 9g Span 80 was dissolved in 70mL paraffin oil to obtain the oil phase liquid. The oil phase liquid was added to a three-necked flask, and 4 / 5 of the core solution was added dropwise while mechanically stirring at 800 rpm. After the addition was complete, stirring was continued for 30min. Then, the stirring speed was reduced to 300–400 rpm, nitrogen gas was purged into the three-necked flask for 30min, and then the temperature was raised to 60℃, and 1.2mL of the core solution was added dropwise. The reaction was initiated with 1% ammonium persulfate solution. After 40 min of reaction, the remaining 1 / 5 of the core solution was added dropwise to a three-necked flask. After the addition was complete, the shell solution was added dropwise to the three-necked flask. After the addition of the shell solution was complete, 0.5 mL of 1% ammonium persulfate solution was added dropwise. The reaction was then stopped after 6 h. The emulsion after the reaction was poured into 1200 mL of anhydrous ethanol to break the emulsion. The precipitate was washed with anhydrous ethanol and dried to obtain 19.2 g of white powder product.

[0063] The initial particle size of the product is 0.5–98.6 μm, the median particle size is 18.3 μm, the expansion rate of the product under clean water conditions is 43 g / g, the expansion rate in 1% sodium chloride solution is 29 g / g, the expansion rate in 10% sodium chloride solution is 12 g / g, the expansion rate in 20% sodium chloride solution is 10 g / g, the expansion rate in 1% calcium chloride solution is 19 g / g, and the expansion rate in 1% magnesium chloride solution is 23 g / g.

[0064] Example 2

[0065] 10g acrylamide, 3g acrylic acid, 0.06g N,N'-methylenebisacrylamide, and 0.7g GOP-10 were dissolved in 27g water, and the pH was adjusted to neutral to obtain the core solution. 6.2g acrylamide, 0.8g acrylic acid, 0.08g sodium styrene sulfonate, and 0.10g polyethylene glycol diacrylate were dissolved in 13g water, and the pH was adjusted to neutral. Then, 0.06g aluminum citrate was added to the solution to obtain the shell solution. 8.5g Span 80 was dissolved in 80mL of paraffin oil to obtain the oil phase liquid. The oil phase liquid was added to a three-necked flask, and 4 / 5 of the core solution was added dropwise while mechanically stirring at 800 rpm. After the addition was complete, stirring was continued for 30min. Then, the stirring speed was reduced to 300–400 rpm, nitrogen gas was purged into the three-necked flask for 30min, and then the temperature was raised to 60℃, and 1.5mL of the core solution was added dropwise. The reaction was initiated with 1% ammonium persulfate solution. After 40 min of reaction, the remaining 1 / 5 of the core solution was added dropwise to a three-necked flask. After the addition was complete, the shell solution was added dropwise to the three-necked flask. After the addition of the shell solution was complete, 0.8 mL of 1% ammonium persulfate solution was added dropwise. The reaction was then stopped after 6 h. The emulsion after the reaction was poured into 1500 mL of anhydrous ethanol to break the emulsion. The precipitate was washed with anhydrous ethanol and dried to obtain 18.6 g of white powder product.

[0066] The initial particle size of the product is 0.4–89.7 μm, with a median particle size of 14.6 μm. The product's expansion rate is 39 g / g in water, 25 g / g in 1% sodium chloride solution, 9 g / g in 10% sodium chloride solution, 6 g / g in 20% sodium chloride solution, 14 g / g in 1% calcium chloride solution, and 17 g / g in 1% magnesium chloride solution.

[0067] Example 3

[0068] 10g acrylamide, 4g 2-acrylamide-2-methylpropanesulfonic acid, and 0.018g... N,N'-methylenebisacrylamide, 0.2g Triton X100, and 1.0g Tween 80 were dissolved in 26g of water, and the pH was adjusted to neutral to obtain the core solution. 4g acrylamide, 2g acrylic acid, 0.08g alkylallyl dimethyl ammonium chloride, and 0.21g polyethylene glycol diacrylate were dissolved in 14g of water, and the pH was adjusted to neutral. Then, 0.12g zirconium citrate was added to the solution to obtain the shell solution. 12.3g Span 80 was dissolved in 65mL of paraffin oil to obtain the oil phase liquid. The oil phase liquid was added to a three-necked flask, and 4 / 5 of the core solution was added dropwise while mechanically stirring at 800 rpm. After the addition was complete, stirring was continued for 30min. Then, the stirring speed was reduced to 300–400 rpm, nitrogen gas was purged into the three-necked flask for 30min, and then the temperature was raised to 60℃, and 2.5mL of the core solution was added dropwise. The reaction was initiated with 1% ammonium persulfate solution. After 40 min of reaction, the remaining 1 / 5 of the core solution was added dropwise to a three-necked flask. After the addition was complete, the shell solution was added dropwise to the three-necked flask. After the addition of the shell solution was complete, 0.4 mL of 1% ammonium persulfate solution was added dropwise. The reaction was then stopped after 6 h. The emulsion after the reaction was poured into 1800 mL of anhydrous ethanol to break the emulsion. The precipitate was washed with anhydrous ethanol and dried to obtain 19.3 g of white powder product.

[0069] The initial particle size of the product is 0.3–79.5 μm, with a median particle size of 8.5 μm. The product's expansion rate is 54 g / g in water, 37 g / g in 1% sodium chloride solution, 21 g / g in 10% sodium chloride solution, 16 g / g in 20% sodium chloride solution, 27 g / g in 1% calcium chloride solution, and 32 g / g in 1% magnesium chloride solution.

[0070] Example 4

[0071] The 0.5g microsphere profile control agent obtained in Example 2 was dispersed in 50ml of water to obtain a dispersion. The dispersion was then transferred to a 100mL glass bottle and sealed. The bottle was placed in an oven at a certain temperature for aging. At regular intervals, the bottle was removed and inverted to observe whether the liquid flowed from the bottom to the top. If the liquid did not flow to the top, it was determined that the polymer microspheres had aggregated; otherwise, it was determined that no aggregation had occurred. As shown in Tables 1 and 2, the polymer microsphere profile control agent did not aggregate below 40℃, but aggregated above 40℃, and the aggregation time decreased with increasing temperature. Furthermore, the salinity of water also had a significant impact on the aggregation time of the polymer microsphere profile control agent; aggregation occurred more quickly under high salinity conditions, and divalent salts had a more significant effect on the aggregation time of the polymer microspheres.

[0072] Table 1. Aggregation properties of microspheres under different temperature conditions

[0073]

[0074] Note: All water salinity is 1% sodium chloride.

[0075] Table 2 Aggregation properties of microspheres under different mineralization conditions

[0076]

[0077]

[0078] Note: Aging temperature is 90℃.

[0079] Example 5

[0080] The product from Example 1 was used in a sand-filled pipe displacement experiment. The permeability of the sand-filled pipe was 1285×10⁻⁶. -3 μm 2 5420×10 -3 μm 2 10862×10 -3 μm 2 The sand-filled tube was 30 cm long and 2.5 cm in diameter. The sample from Example 1 was prepared into a suspension of polymer microspheres with a mass concentration of 0.3% using a 1% sodium chloride solution. The suspension was injected into the sand-filled tube at an injection rate of 0.3 mL / min, with an injection volume of 0.5 PV. The suspension was allowed to stand at 90°C for 5 days. Subsequently, water-drive measurements were performed to determine the sealing rate of the polymer microspheres in the sand-filled tube.

[0081] The results showed that the polymer microspheres had a permeability of 1285 × 10⁻⁶. -3 μm 2 5420×10 -3 μm 2 10862×10 -3 μm 2 The plugging rates in the sand-filled pipes were 99.2%, 98.7%, and 91.6%, respectively. The polymer microspheres showed high plugging rates in all sand-filled pipes and could effectively plug high-permeability and ultra-high-permeability water flow channels.

[0082] Example 6

[0083] Long-term stability was evaluated using the sample from Example 3. The sample was prepared as a 1% dispersion and placed in a high-pressure, temperature-resistant sealed container. The salinity was 200,000 mg / L (prepared with sodium chloride), and the temperature was 120°C. After 90 days of aging, the sample was removed and observed under a microscope. The microstructure of the sample is shown below. Figure 1As shown, the sample did not undergo hydration decomposition and instead appeared as irregular clumps formed by the aggregation of microspheres, proving that the sample had good stability.

Claims

1. A polymer microsphere profile modifier, characterized in that, The polymer microsphere profile control agent includes a core and a shell, wherein the core comprises anionic polyacrylamide and the shell comprises anionic hydrophobic associative polyacrylamide; The anionic polyacrylamide is prepared from acrylamide, anionic monomer, stabilizing crosslinking agent, and water-soluble emulsifier; the anionic hydrophobic associative polyacrylamide is prepared from acrylamide, acrylic acid, surfactant monomer, and unstable crosslinking agent. The anionic monomer is selected from one or both of acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid; the stabilizing crosslinking agent includes N,N'-methylenebisacrylamide; The surfactant monomer includes one or more of fatty alcohol polyoxyethylene ether acrylate, alkyl allyl dimethyl ammonium chloride, and sodium styrene sulfonate, and the unstable crosslinking agent includes polyethylene glycol diacrylate.

2. The polymer microsphere profile control agent according to claim 1, characterized in that, The outer shell also includes an ionic crosslinking agent, which includes one or more of chromium acetate, aluminum citrate, and zirconium citrate.

3. The polymer microsphere profile control agent according to claim 1 or 2, characterized in that, The anionic polyacrylamide contains 25-40% by weight acrylamide, the anionic monomer contains 10-30% by weight acrylamide, the stabilizing crosslinking agent contains 0.025-0.14% by weight acrylamide, the water-soluble emulsifier contains 1.6%-4.8% by weight acrylamide, and the remainder is water.

4. The polymer microsphere profile control agent according to claim 3, characterized in that, The water-soluble emulsifier monomer is one or a mixture of two or more of Tween 60, Tween 80, OP-10, and Triton X100.

5. The polymer microsphere profile control agent according to claim 2, characterized in that, The shell contains 25-35% by weight acrylamide, 5-10% by weight acrylic acid, 0.1-0.8% by weight surfactant monomer, 0.30-1.25% by weight unstable crosslinking agent, 0.10-5% by weight ionic crosslinking agent, and the remainder is water.

6. The polymer microsphere profile control agent according to any one of claims 1 to 2, characterized in that, The particle size range of the polymer microsphere profile modifier includes 0.4–100 μm and 0.4–10 μm.

7. A method for preparing a polymer microsphere profile modifier as described in any one of claims 1 to 6, comprising the following steps: a. Dissolve acrylamide, anionic monomer, stabilizing crosslinking agent, and water-soluble emulsifier in water to obtain a core solution; b. Dissolve acrylamide, acrylic acid, surfactant monomer, and unstable crosslinking agent in water, then add an ionic crosslinking agent to dissolve and obtain the shell solution; c. Dissolve the oil-soluble emulsifier in paraffin oil to obtain an oil-phase liquid; d. The core solution and shell solution respectively react with the initiator solution in an oil phase to obtain a polymer microsphere profile control emulsion; e. After demulsification, washing, and drying, the polymer microsphere profile modifier is obtained.

8. The method for preparing the polymer microsphere profile modifier according to claim 7, characterized in that, The core solution contains 25-40% by weight acrylamide, 10-30% by weight anionic monomer, 0.025-0.14% by weight a stable crosslinking agent, and 1.6-4.8% by weight a water-soluble emulsifier. The anionic monomer is one or both of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid; the stable crosslinking agent is N,N'-methylenebisacrylamide; and the water-soluble emulsifier monomer is one or more of Tween 60, Tween 80, OP-10, and Triton X100; and / or The shell solution contains 25-35% by weight acrylamide, 5-10% by weight acrylic acid, 0.1-0.8% by weight surfactant monomer, 0.30-1.25% by weight unstable crosslinking agent, and 0.10-5% by weight ionic crosslinking agent; wherein the surfactant monomer is one or a mixture of two or more of fatty alcohol polyoxyethylene ether acrylate, alkyl allyl dimethyl ammonium chloride, and sodium styrene sulfonate; the unstable crosslinking agent is polyethylene glycol diacrylate; the ionic crosslinking agent is one of chromium acetate, aluminum citrate, and zirconium citrate; and / or the oil-soluble emulsifier is Span 80.

9. The application of a polymer microsphere profile control agent as described in any one of claims 1 to 6 in oilfields.

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