Slow-expansion temperature-resistant polymer microspheres for deep plugging of steam channeling in steam-driven oil reservoirs, preparation method and application thereof

Abstract

The present invention relates to the field of oilfield chemical technology, and specifically relates to slow-expansion temperature-resistant polymer microspheres for deep plugging of steam channeling in steam-driven oil reservoirs, as well as a preparation method and application. The raw materials of the microspheres include the following components: styrene, acrylate, divinylbenzene, silicate, initiator, emulsifier and water. The preparation method includes first mixing water and Tween-80, then adding styrene, n-butyl acrylate, divinylbenzene and silicate, stirring, deoxygenating; finally adding an aqueous solution of the initiator, reacting, and obtaining. The polymer microspheres of the present invention not only have good stability under high temperature conditions, but also have the characteristics of swelling when exposed to water at high temperature (>150°C), and no change in volume when exposed to water at low temperature (<80°C). It has the characteristics of being easy to inject and migrate before expansion, and being able to effectively plug steam channeling after expansion, adapting to the process of steam injection in oil fields, and can be used for deep plugging of steam channeling in steam-driven heavy oil reservoirs.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield chemistry, and in particular relates to slow-expansion temperature-resistant polymer microspheres for deep plugging of steam channeling in steam-driven oil reservoirs, and a preparation method and application thereof. Background Art

[0002] Steam injection production of heavy oil reservoirs is generally divided into two stages: steam stimulation and steam flooding. There are steam channeling problems in both stages, and steam channeling is particularly serious during steam flooding. Steam channeling not only seriously affects the normal production of oil wells, but also greatly reduces the utilization efficiency of steam. Therefore, effective steam channeling control technology is crucial to the sustainable and efficient development of heavy oil reservoirs. After years of technical accumulation, two relatively mature methods, foam injection and plugging agent injection, have been formed for steam channeling control during steam stimulation. Foam injection is mainly used for reservoirs with less severe formation heterogeneity, and plugging agent injection is mainly used to plug steam channeling channels with a permeability range greater than 6. The most commonly used plugging agent for plugging steam channeling is polymer gel, of which synthetic polymer gel can be used in formations with temperatures less than 180°C, and natural polymer gels such as tannin extract can be used in formations with temperatures as high as 200°C or above. Since the formation temperature is relatively low (generally less than 80°C) at the end of each round of steam stimulation, the above-mentioned gelling liquid can be smoothly injected and displaced to a certain part of the formation. Once gelled, these gelling liquids have good temperature resistance and can effectively suppress steam channeling in a new round of steam injection.

[0003] For steam channeling during steam flooding, due to the extremely high formation temperature (greater than 180°C) during continuous steam injection, conventional steam channeling plugging technology is difficult to adapt. For example, the gelling temperature of tannin jelly is less than 5h at a temperature of 120°C; the gelling time of sodium humate jelly is less than 3h at a temperature of 180°C. Because these jellys cross-link too quickly at high temperatures, it is difficult to smoothly inject and displace to the deep formation in formations with temperatures greater than 180°C. In view of the fast gelling of tannin jelly and the difficulty in meeting the injection requirements, the steam channeling during steam flooding can be treated by injecting granular plugging agents. Rigid particles such as rubber powder and wood powder are heat-resistant and can be used to plug steam channeling in reservoirs with perforated completion and high formation permeability, but when the wellbore is completed with a screen or the formation permeability is not high, the injectability of the particles will be limited.

[0004] Chinese invention patent application CN1036269A discloses a method for preparing water-swelling particles for plugging steam channeling in heavy oil thermal recovery. It uses a composite crosslinking agent composed of a heat-stable crosslinking agent and a heat-degradable crosslinking agent to control the expansion rate of the water-swelling body. At low temperatures, due to the high composite crosslinking density, the water-swelling body particles have a low expansion degree and are easy to migrate to deep formations; at high temperatures, due to the chain break formed by the unstable crosslinking agent, the crosslinking density is reduced, and the expansion capacity of the particles is the largest, thereby showing a higher plugging ability. However, due to the presence of these unstable crosslinking chains in the crosslinked polymer, the temperature resistance of the particles is limited, and the above particles are difficult to adapt to the use of 180°C temperature formations.

[0005] Another Chinese invention patent application CN103626917A discloses an expandable graphite plugging agent system and injection method for deep plugging of heavy oil reservoir steam flooding, wherein expandable graphite particles are used as materials for plugging steam channeling. Although graphite particles are heat-resistant, the preparation process is complicated, the cost is high, and the practical value is not great.

[0006] In summary, developing a granular plugging agent with good injectability, temperature resistance and high plugging ability for the formation is of great significance to solving the steam channeling problem during steam flooding. Summary of the invention

[0007] Aiming at the shortcomings of poor temperature resistance and poor plugging ability of existing granular plugging agents when used to plug steam channeling in deep steam drive reservoirs, the present invention provides a polymer microsphere which is heat-resistant and can slowly expand at high temperature and a preparation method thereof.

[0008] In order to achieve the purpose of the present invention, the technical solution adopted is as follows:

[0009] The invention discloses a slow-expansion temperature-resistant polymer microsphere for plugging steam channeling in deep steam-driven oil reservoirs. The raw materials of the microsphere include the following components: styrene, n-butyl acrylate, divinylbenzene, silicate, initiator, emulsifier and water.

[0010] Preferably, the particle size of the microspheres is 0.3-2 μm.

[0011] Preferably, the silicate is ethyl orthosilicate.

[0012] Preferably, the initiator is one or more of potassium persulfate, ammonium persulfate and sodium persulfate.

[0013] Preferably, the emulsifier is at least one of Tween-80, Tween-40 and Tween-60.

[0014] Preferably, the mass ratio of styrene to n-butyl acrylate is 1:1-4, preferably 3:7.

[0015] Preferably, the mass of the divinylbenzene is 0.2%-0.8%, preferably 0.4%, of the total mass of styrene and n-butyl acrylate.

[0016] Preferably, the amount of the silicate is 1%-5%, preferably 2%, of the total mass of styrene and n-butyl acrylate.

[0017] According to the present invention, among the above parameters, the amount of water and emulsifier mainly affects the particle size of the cross-linked polymer and the stability of the polymerization reaction; the ratio of styrene and n-butyl acrylate affects the final water absorption and expansion capacity and strength of the polymer microspheres; divinylbenzene affects the strength, heat resistance and water absorption and expansion capacity of the cross-linked polymer; and tetraethyl orthosilicate mainly affects the heat resistance of the polymer and the dispersion stability of the microspheres.

[0018] Another object of the present invention is to provide a method for preparing the above-mentioned polymer microspheres, comprising the following steps:

[0019] (1) Mix water and Tween-80;

[0020] (2) Add styrene, n-butyl acrylate, divinylbenzene and silicate, stir and deoxygenate;

[0021] (3) Add the aqueous solution of the initiator and simultaneously increase the temperature to allow the reaction to proceed.

[0022] Preferably, the stirring speed in step (2) is 400 rpm.

[0023] Preferably, in step (2), nitrogen is passed through to deoxygenate for 30 minutes.

[0024] Preferably, the mass ratio of water in step (1) to the total mass of styrene, n-butyl acrylate, divinylbenzene and silicate in step (2) is 1:1-1:4, and the preferred mass ratio is 1:2.

[0025] Preferably, in step (3), the initiator is added at a rate of 1-2 drops / second and the reaction time is 3 hours.

[0026] Preferably, the temperature is raised to 60° C. in step (3).

[0027] Preferably, the mass concentration of the aqueous solution of the initiator is 1-3%, and the amount thereof is 0.1%-1%, preferably 0.5%, of the total mass of styrene and n-butyl acrylate.

[0028] Another object of the present invention is to provide the use of the above polymer microspheres in plugging steam channeling in deep steam flooding reservoirs.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The polymer microspheres prepared by the present invention can only expand after high-temperature treatment. They are easy to inject and move before expansion and can effectively block steam channeling after expansion, which is suitable for the process of steam injection in oil fields. Since the particles are polymerized from a small amount of lipophilic monomer styrene and a large amount of weakly polar monomer butyl acrylate, the microspheres are weakly polar and do not absorb water and expand at normal formation temperatures. However, under the action of high-temperature steam, the ester bond is hydrolyzed to form carboxylic acid, the hydrophilicity of the particles continues to increase, and the particles will absorb water and expand accordingly. The particles are small in size before expansion and are easily carried into the steam channel by steam; after the particles are hydrolyzed and expanded, they can effectively block the steam channeling and enable the steam to be diverted deep.

[0031] (2) Adding a certain amount of tetraethyl orthosilicate as a nano-silica precursor during the polymerization process has two main functions. Part of the tetraethyl orthosilicate is dissolved in the oil-soluble monomer. After the tetraethyl orthosilicate is hydrolyzed to form silica, it can increase the strength and temperature resistance of the polymerized particle-free product; the other part of the tetraethyl orthosilicate is dispersed in water and can be hydrolyzed to form nano-silica. These silica particles are adsorbed on the surface of the polymer particles to prevent the polymer particles from agglomerating and improve the dispersion stability of the polymer particles.

[0032] (3) The present invention improves the stability of the particles by three means: first, adding an appropriate amount of styrene as a comonomer, thereby introducing benzene rings into the polymer, improving the rigidity and temperature resistance of the polymer. Second, adding a specific amount of divinylbenzene during the synthesis makes the cross-linked polymer have a higher cross-linking density and stronger high-temperature stability. In addition, pre-placing silica particles in the polymer particles not only improves the strength of the particles, but also improves the temperature resistance of the particles.

[0033] (4) The polymer microspheres prepared by the present invention have a particle size of 0.3-2 microns, do not absorb water and swell when immersed in water for a long time at 80°C, and have good injection capacity in the formation. After the microspheres are heat treated at 150°C for 10 hours, the ester bonds in the molecules are gradually hydrolyzed to form carboxylate groups, and the microspheres change from weakly polar particles to hydrophilic particles, which absorb water and swell, thereby improving the plugging capacity of the formation. After heat treatment at 250°C for 10 hours, the water absorption and expansion multiple is greater than 15, and the storage modulus is greater than 100Pa. After heat treatment in water at 280°C for 30 days, the storage modulus of the polymer microspheres remains above 90, and the microspheres have good temperature resistance. The microspheres can be used to plug steam channeling in deep steam-driven heavy oil reservoirs.

[0034] (5) The polymer microspheres of the present invention not only have good stability under high temperature conditions, but also have the characteristics of expanding when exposed to water at high temperatures (>150°C) and not changing in volume when exposed to water at low temperatures (<80°C). DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with specific implementation modes.

[0036] Embodiment 1:

[0037] 1) Weigh 1g of Tween-80, add it into a four-necked flask containing 32g of distilled water, and stir until fully dispersed;

[0038] 2) Weigh 13g styrene and 52g n-butyl acrylate, pour into a beaker and stir until fully dispersed;

[0039] 3) Add the liquid from step 2) into a four-necked flask and start the stirring device at a speed of 400 rpm;

[0040] 4) Weigh 0.3g of divinylbenzene and 1.3g of ethyl orthosilicate;

[0041] 5) Add the liquid from step 4) into the four-necked flask from step 3), keep stirring, and introduce nitrogen to react for 30 minutes;

[0042] 6) Place the four-necked flask in step 5) in a 60°C constant temperature water bath and heat until the temperature remains constant;

[0043] 7) Use a separatory funnel to continuously add 0.3 g of potassium persulfate aqueous solution as initiator to the four-necked flask in step 6) at a rate of 2 drops / second and react for 3 hours;

[0044] 8) After the reaction is completed, keep stirring and stop heating. After the temperature drops to 35°C, pour out the contents to obtain a polymer microsphere solution.

[0045] Embodiment 2:

[0046] 1) Weigh 1g of Tween-80, add it into a four-necked flask containing 32g of distilled water, and stir until fully dispersed;

[0047] 2) Weigh 19.5g of styrene and 45.5g of n-butyl acrylate, pour into a beaker and stir until fully dispersed;

[0048] 3) Add the liquid from step 2) into a four-necked flask and start the stirring device at a speed of 400 rpm;

[0049] 4) Weigh 0.3g of divinylbenzene and 1.3g of ethyl orthosilicate;

[0050] 5) Add the liquid from step 4) into the four-necked flask from step 3), keep stirring, and introduce nitrogen to react for 30 minutes;

[0051] 6) Place the four-necked flask in step 5) in a 60°C constant temperature water bath and heat until the temperature remains constant;

[0052] 7) Use a separatory funnel to continuously add 0.3 g of potassium persulfate aqueous solution as initiator to the four-necked flask in step 6) at a rate of 2 drops / second and react for 3 hours;

[0053] 8) After the reaction is completed, keep stirring and stop heating. After the temperature drops to 35°C, pour out the contents to obtain a polymer microsphere solution.

[0054] Embodiment 3:

[0055] 1) Weigh 1g of Tween-80, add it into a four-necked flask containing 32g of distilled water, and stir until fully dispersed;

[0056] 2) Weigh 32.5g of styrene and 32.5g of n-butyl acrylate, pour into a beaker and stir until fully dispersed;

[0057] 3) Add the liquid from step 2) into a four-necked flask and start the stirring device at a speed of 400 rpm;

[0058] 4) Weigh 0.3g of divinylbenzene and 1.3g of ethyl orthosilicate;

[0059] 5) Add the liquid from step 4) into the four-necked flask from step 3), keep stirring, and introduce nitrogen to react for 30 minutes;

[0060] 6) Place the four-necked flask in step 5) in a 60°C constant temperature water bath and heat until the temperature remains constant;

[0061] 7) Use a separatory funnel to continuously add 0.3 g of potassium persulfate aqueous solution as initiator to the four-necked flask in step 6) at a rate of 2 drops / second and react for 3 hours;

[0062] 8) After the reaction is completed, keep stirring and stop heating. After the temperature drops to 30-40°C, pour out the contents to obtain a polymer microsphere solution.

[0063] Embodiment 4:

[0064] 1) Weigh 1g of Tween-40, add it into a four-necked flask containing 32g of distilled water, and stir until fully dispersed;

[0065] 2) Weigh 19.6g of styrene and 45.6g of n-butyl acrylate, pour into a beaker and stir until fully dispersed;

[0066] 3) Add the liquid from step 2) into a four-necked flask and start the stirring device at a speed of 400 rpm;

[0067] 4) Weigh 0.3g of divinylbenzene and 1.3g of ethyl orthosilicate;

[0068] 5) Add the liquid from step 4) into the four-necked flask from step 3), keep stirring, and introduce nitrogen to react for 30 minutes;

[0069] 6) Place the four-necked flask in step 5) in a 60°C constant temperature water bath and heat until the temperature remains constant;

[0070] 7) Use a separatory funnel to continuously add 0.3 g of ammonium persulfate aqueous solution as initiator to the four-necked flask in step 6) at a rate of 2 drops / second and react for 3 hours;

[0071] 8) After the reaction is completed, keep stirring and stop heating. After the temperature drops to 30-40°C, pour out the contents to obtain a polymer microsphere solution.

[0072] Embodiment 5:

[0073] 1) Weigh 1g of Tween-80, add it into a four-necked flask containing 32g of distilled water, and stir until fully dispersed;

[0074] 2) Weigh 19.4g styrene and 45.4g n-butyl acrylate, pour into a beaker and stir until fully dispersed;

[0075] 3) Add the liquid from step 2) into a four-necked flask and start the stirring device at a speed of 400 rpm;

[0076] 4) Weigh 0.3g of divinylbenzene and 1.3g of ethyl orthosilicate;

[0077] 5) Add the liquid from step 4) into the four-necked flask from step 3), keep stirring, and introduce nitrogen to react for 30 minutes;

[0078] 6) Place the four-necked flask in step 5) in a 60°C constant temperature water bath and heat until the temperature remains constant;

[0079] 7) Use a separatory funnel to continuously add 0.3 g of sodium persulfate aqueous solution as initiator to the four-necked flask in step 6) at a rate of 2 drops / second and react for 3 hours;

[0080] 8) After the reaction is completed, keep stirring and stop heating. After the temperature drops to 30-40°C, pour out the contents to obtain a polymer microsphere solution.

[0081] Embodiment 6:

[0082] 1) Weigh 1g of Tween-60, add it into a four-necked flask containing 32g of distilled water, and stir until fully dispersed;

[0083] 2) Weigh 19.7g styrene and 46g n-butyl acrylate, pour into a beaker and stir until fully dispersed;

[0084] 3) Add the liquid from step 2) into a four-necked flask and start the stirring device at a speed of 400 rpm;

[0085] 4) Weigh 0.3g of divinylbenzene and 0.7g of ethyl orthosilicate;

[0086] 5) Add the liquid from step 4) into the four-necked flask from step 3), keep stirring, and introduce nitrogen to react for 30 minutes;

[0087] 6) Place the four-necked flask in step 5) in a 60°C constant temperature water bath and heat until the temperature remains constant;

[0088] 7) Use a separatory funnel to continuously add 0.3 g of potassium persulfate aqueous solution as initiator to the four-necked flask in step 6) at a rate of 2 drops / second and react for 3 hours;

[0089] 8) After the reaction is completed, keep stirring and stop heating. After the temperature drops to 30-40°C, pour out the contents to obtain a polymer microsphere solution.

[0090] Embodiment 7:

[0091] 1) Weigh 1g of Tween-80, add it into a four-necked flask containing 32g of distilled water, and stir until fully dispersed;

[0092] 2) Weigh 19g styrene and 44.2g n-butyl acrylate, pour into a beaker and stir until fully dispersed;

[0093] 3) Add the liquid from step 2) into a four-necked flask and start the stirring device at a speed of 400 rpm;

[0094] 4) Weigh 0.3 g of divinylbenzene and 3.1 g of ethyl orthosilicate;

[0095] 5) Add the liquid from step 4) into the four-necked flask from step 3), keep stirring, and introduce nitrogen to react for 30 minutes;

[0096] 6) Place the four-necked flask in step 5) in a 60°C constant temperature water bath and heat until the temperature remains constant;

[0097] 7) Use a separatory funnel to continuously add 0.3 g of potassium persulfate aqueous solution as initiator to the four-necked flask in step 6) at a rate of 2 drops / second and react for 3 hours;

[0098] 8) After the reaction is completed, keep stirring and stop heating. After the temperature drops to 30-40°C, pour out the contents to obtain a polymer microsphere solution.

[0099] Comparative Example 1

[0100] The difference from the embodiment is that no ethyl orthosilicate is added. The specific preparation is as follows:

[0101] 1) Weigh 1g of Tween-80, add it into a four-necked flask containing 32g of distilled water, and stir until fully dispersed;

[0102] 2) Weigh 13g styrene and 52g n-butyl acrylate, pour into a beaker and stir until fully dispersed;

[0103] 3) Add the liquid from step 2) into a four-necked flask and start the stirring device at a speed of 400 rpm;

[0104] 4) Weigh 0.3 g of divinylbenzene and add it to the four-necked flask in step 3), keep stirring, and introduce nitrogen to react for 30 minutes;

[0105] 5) Place the four-necked flask in step 4) in a 60°C constant temperature water bath and heat until the temperature remains constant;

[0106] 6) Use a separatory funnel to continuously add 0.3 g of potassium persulfate aqueous solution as initiator to the four-necked flask in step 5) at a rate of 2 drops / second and react for 3 hours;

[0107] 7) After the reaction is completed, keep stirring and stop heating. After the temperature drops to 35°C, pour out the contents to obtain a polymer microsphere solution.

[0108] Comparative Example 2 (low divinylbenzene dosage)

[0109] 1) Weigh 1g of Tween-80, add it into a four-necked flask containing 32g of distilled water, and stir until fully dispersed;

[0110] 2) Weigh 19.4g styrene and 45.4g n-butyl acrylate, pour into a beaker and stir until fully dispersed;

[0111] 3) Add the liquid from step 2) into a four-necked flask and start the stirring device at a speed of 400 rpm;

[0112] 4) Weigh 0.1g of divinylbenzene and 1.3g of ethyl orthosilicate;

[0113] 5) Add the liquid from step 4) into the four-necked flask from step 3), keep stirring, and introduce nitrogen to react for 30 minutes;

[0114] 6) Place the four-necked flask in step 5) in a 60°C constant temperature water bath and heat until the temperature remains constant;

[0115] 7) Use a separatory funnel to continuously add 0.3 g of potassium persulfate aqueous solution as initiator to the four-necked flask in step 6) at a rate of 2 drops / second and react for 3 hours;

[0116] 8) After the reaction is completed, keep stirring and stop heating. After the temperature drops to 35°C, pour out the contents to obtain a polymer microsphere solution.

[0117] Test Example 1

[0118] Evaluation of expansion performance and temperature stability

[0119] The polymer microspheres obtained in Examples 1-7 and the products obtained in Comparative Examples 1-2 were used to examine their expansion properties in water and their temperature stability.

[0120] The specific implementation process is as follows: 5 g of the microsphere solutions corresponding to Examples 1-7 and Comparative Examples 1-2 were weighed and placed in water respectively, and evaluated at 80° C. and 250° C. for 30 days to observe the performance changes. The specific experimental results are shown in Table 1.

[0121] Table 1 Performance indicators of microspheres corresponding to Examples 1-7 and Comparative Examples 1-2

[0122]

[0123] It can be seen from Table 1 that after 30 days of high temperature evaluation, the volumes of the samples of Examples 1-7 hardly change in 80°C water, and the expansion multiples are stable in 250°C water, indicating that the polymer microspheres do not expand when exposed to water at low temperatures (<80°C), but expand when exposed to water at high temperatures (>150°C), and have good stability under high temperature conditions.

[0124] The sample of Comparative Example 1, in which no ethyl orthosilicate was added to the reactants, produced microspheres that expanded in 80°C water and had poor stability in 250°C water. After 20 days, the microspheres broke and lost their plugging performance.

[0125] The sample of Comparative Example 2 has a low amount of divinylbenzene in the reactants, and the obtained microspheres are similar to those of Comparative Example 1, and the expansion multiple in 80°C water is greatly increased. The expansion multiple in 250°C water is reduced, and the stability is very poor. After 5 days, the microspheres rupture and lose their plugging performance.

[0126] Test Example 2

[0127] High temperature plugging capability evaluation

[0128] Test method: 5g of microsphere solution was placed in water, the solution was sealed in ampoules and placed in an oven at 250°C for aging for 10h and in an oven at 280°C for aging for 30 days. After the polymer microspheres were expanded, the storage modulus of the expanded microspheres was measured at room temperature using an Anton Paar MCR92 rheometer. The larger the storage modulus of the microspheres, the higher the microsphere strength and the better the plugging performance. The evaluation results are shown in Table 2.

[0129] Table 2 Viscosity of gelling liquid and storage modulus of gel

[0130]

[0131] It can be seen from Test Example 2 that the storage modulus of the microspheres corresponding to Examples 1-7 is greater than 100Pa after heat treatment at 250°C for 10h and water swelling, and the storage modulus remains above 90 after heat treatment in 280°C water for 30 days, and has good plugging ability. Among them, the microsphere storage modulus corresponding to Example 2 of the preferred component is the largest, and the plugging strength is the highest. The preferred concentration is: the mass ratio of styrene and n-butyl acrylate in the monomer is 3:7, the amount of divinylbenzene is 0.4% of the total mass of the monomer, and the amount of tetraethyl orthosilicate is 2% of the total mass of the monomer. It can be seen from Comparative Examples 1 and 2 that when the amount of divinylbenzene and tetraethyl orthosilicate is too small, the strength of the microspheres is greatly reduced, and the plugging ability is insufficient.

Claims

1. Slow-expansion temperature-resistant polymer microspheres for deep plugging of steam channeling in steam-driven oil reservoirs, characterized in that: The raw materials of the microspheres are composed of the following components: styrene, n-butyl acrylate, divinylbenzene, silicate, initiator, emulsifier and water; the mass of the divinylbenzene is 0.2%-0.8% of the total mass of styrene and n-butyl acrylate; The silicate is ethyl orthosilicate; The emulsifier is at least one of Tween-80, Tween-40 and Tween-60.

2. The polymer microsphere according to claim 1, characterized in that The particle size of the microspheres is 0.3-2 μm.

3. The polymer microsphere according to claim 1, characterized in that The initiator is one or more of potassium persulfate, ammonium persulfate and sodium persulfate.

4. The polymer microsphere according to claim 1, characterized in that The mass ratio of styrene to n-butyl acrylate is 1:1-4.

5. The polymer microsphere according to claim 1, characterized in that The mass ratio of styrene to n-butyl acrylate is 3:

7.

6. The polymer microsphere according to claim 1, characterized in that The mass of the divinylbenzene is 0.4% of the total mass of styrene and n-butyl acrylate.

7. The polymer microsphere according to claim 1, characterized in that The amount of the silicate used is 1%-5% of the total mass of styrene and n-butyl acrylate.

8. The polymer microsphere according to claim 1, characterized in that The amount of the silicate used is 2% of the total mass of styrene and n-butyl acrylate.

9. A method for preparing polymer microspheres according to any one of claims 1 to 8, characterized in that: The steps include: (1) Mix water and emulsifier; (2) Add styrene, n-butyl acrylate, divinylbenzene and silicate, stir and deoxygenate; (3) Add the aqueous solution of initiator and react to obtain the product.

10. The preparation method according to claim 9, characterized in that: The stirring speed in step (2) is 400 rpm.

11. The preparation method according to claim 9, characterized in that: The deoxygenation in step (2) is carried out by passing nitrogen gas for 25-35 minutes.

12. The preparation method according to claim 9, characterized in that: The ratio of the mass of water in step (1) to the total mass of styrene, n-butyl acrylate, divinylbenzene and silicate in step (2) is 1:1-1:

4.

13. The preparation method according to claim 9, characterized in that: In step (3), the initiator is added at a rate of 1-2 drops / second and the reaction time is 2-4 hours.

14. The preparation method according to claim 9, characterized in that: Before adding the aqueous solution of the initiator in step (3), the system temperature is first raised to 55-65°C.

15. The preparation method according to claim 9, characterized in that: The mass concentration of the aqueous solution of the initiator in step (3) is 1-3%, and the amount thereof is 0.1%-1% of the total mass of styrene and n-butyl acrylate.

16. The preparation method according to claim 9, characterized in that: The amount of the aqueous solution of the initiator used in step (3) is 0.5% of the total mass of styrene and n-butyl acrylate.

17. Use of the polymer microspheres according to any one of claims 1 to 8 in plugging steam channeling in deep steam flooding reservoirs.

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