An amphiphilic Janus SiO2 / calcium alginate composite microsphere profile control agent, a preparation method and application thereof

Abstract

The application discloses an amphiphilic Janus SiO2 / calcium alginate composite microsphere profile control agent and a preparation method and application thereof, wherein the preparation method comprises the following steps: adding dry monodisperse SiO2-NH2 microspheres into a modified solvent of an anhydrous ethanol-water system, adding hexamethyldisilazane, and performing reaction under the conditions of a temperature of 80 DEG C and stirring; centrifuging and washing to obtain hydrophobic modified SiO2; adding an oil phase solution containing the hydrophobic modified SiO2 into a sodium alginate aqueous solution to obtain a sodium alginate emulsion; under the condition of stirring, adding a calcium chloride aqueous solution dropwise into the sodium alginate emulsion, adding isopropyl alcohol for solidification, and performing centrifuging and washing to obtain the amphiphilic Janus SiO2 / calcium alginate composite microsphere profile control agent. The application replaces a traditional emulsifier with the amphiphilic Janus SiO2 nanoparticle and replaces a traditional synthetic polymer with calcium alginate, synthesizes the amphiphilic Janus SiO2 / calcium alginate composite microsphere based on a Pickering emulsion polymerization method to serve as a novel profile control agent, is green and environment-friendly, reduces the use of the emulsifier, and reduces the synthesis cost.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field development technology, specifically to an amphiphilic Janus SiO2 / calcium alginate composite microsphere modulator, its preparation method, and its application. Background Technology

[0002] The global demand for crude oil is constantly rising. With increasing difficulties in oil extraction, enhancing oil recovery through flooding technology is crucial for ensuring my country's energy security. Polymer flooding is one of the most effective methods for improving crude oil recovery. The process involves polymer microspheres entering the formation along with injected water. These microspheres migrate and disperse widely in the rock pores. A small number of microspheres migrating within the pores will resist fluid flow, thus affecting the water flow direction; a large number of microspheres will accumulate at the throat, causing blockage and resulting in complete fluid bypass. By adjusting the waterflood profile, the sweep range of injected water in the deeper oil layer can be increased, achieving the goal of "stabilizing oil and controlling water" and improving oil recovery.

[0003] In existing research, polymer microspheres used to enhance oil recovery are mainly acrylamide polymers. Patent CN201810601330.4 discloses a method for preparing polyacrylamide microspheres for profile control, using acrylamide and N,N-dimethylacrylamide as the main monomers, obtained through reverse microemulsion polymerization under the action of a redox composite initiator. To improve the performance of profile control agents and flood control agents, such as strength and oil displacement capacity, many researchers have synthesized inorganic / organic composite microspheres by combining organic and inorganic components. Patent CN202211237355.3 discloses a zwitterionic water-blocking and profile control agent prepared by reverse emulsion polymerization using acrylamide, crosslinking agent, nano-reinforcing agent, and toughening agent as the main reactants. The zwitterionic water-blocking and profile control agent prepared in this invention has good strength after water absorption and swelling, and can be matched with oil layers of different permeability and heterogeneous formations. Patent CN202010467916.3 discloses a nanocomposite polymer and a temperature- and salt-resistant profile control agent containing this nanocomposite polymer. This nanocomposite polymer is mainly formed by the polymerization of inorganic nanosol and acrylamide temperature- and salt-resistant polymeric monomers. By introducing a functional polymer profile control agent formed by the polymerization of temperature- and salt-resistant polymeric monomers with inorganic nanosol, it exhibits strong stability, temperature and salt resistance, and strength. In 2018, in Volume 547, Colloids and Surfaces A: Physicochemical and Engineering Aspects, Tang et al. used γ-methacryloyloxypropyltrimethoxysilane to surface modify nano-silica particles and prepared polyacrylamide / silica composite microspheres via reverse suspension polymerization. Compared with uncomposite polyacrylamide microspheres, these composite microspheres exhibited better dispersion stability, viscoelasticity, and thermal stability, with a 11.54% increase in blocking rate. Patent CN113980169 B discloses a profile control agent for styrene-acrylic emulsions stabilized using amphiphilic Janus SiO2 nanoparticles and its preparation method. This amphiphilic Janus SiO2 nanoparticle-stabilized profile control agent can significantly improve reservoir recovery. However, styrene-acrylic emulsions are synthetic polymers and lack the biodegradability of natural polymers, resulting in permanent damage to the formation.

[0004] With the deepening of the concept of green oil recovery, biodegradable materials, such as environmentally friendly polysaccharides, are attracting increasing attention. Currently, commonly used oil-dispatch polysaccharides are mainly xanthan gum and konjac gum; however, their high price limits their application in oil displacement. Chitosan, a non-toxic, harmless, and biodegradable polysaccharide, has attracted researchers' attention. In 2022, the Journal of Applied Science, Vol. 139, published an article by Chen et al., who modified hyperbranched chitosan polymers and used them as oil displacement agents, exploring their biodegradability in ultrapure water, simulated formation water, and wastewater containing bacteria. However, chitosan production processes are complex, and it is prone to deliquescence in humid environments, affecting its stability and durability in practical applications. Furthermore, the brittleness of chitosan inhibits its oil displacement ability.

[0005] The main problems with existing polymer microsphere flood control agents are: (1) The research and application of polymer microsphere flood control agents are limited, mainly focusing on acrylamide-based polymer microspheres. Acrylamide-based polymer microspheres are synthetic microspheres, which do not have the biodegradability of natural polymers and will cause permanent damage to the formation, resulting in poor environmental performance. (2) Acrylamide-based polymer microspheres may experience problems such as weak strength during use. Currently, the main solution is to introduce inorganic components into acrylamide-based polymer microspheres to increase their strength. However, the introduction of inorganic materials makes the synthesis process of polymer microspheres complex and costly. (3) If the introduced inorganic components are not modified, their interfacial activity is poor and their dispersion stability is poor, which will affect the oil displacement performance of the composite microspheres in the reservoir. (4) The biodegradable and environmentally friendly polymer materials that have been studied are costly, have complex synthesis processes, poor stability, and poor application performance.

[0006] Therefore, it is necessary to develop new green and environmentally friendly high-performance composite microsphere modulators. Summary of the Invention

[0007] To overcome the shortcomings of the prior art, the present invention aims to design and synthesize a high-performance, environmentally friendly oil displacement microsphere for improving oil recovery and providing a novel oil displacement material for low-permeability oilfield development. Based on this, the present invention provides an amphiphilic Janus SiO2 / calcium alginate composite microsphere oil displacement agent, its preparation method, and its application, to solve the problems of non-biodegradability, poor stability, and inadequate oil displacement performance of existing microsphere oil displacement agents.

[0008] To achieve the above objectives, the present invention provides a method for preparing an amphiphilic Janus SiO2 / calcium alginate composite microsphere modulator, comprising the following steps:

[0009] S1. Using anhydrous ethanol-water system as the modifying solvent, dry monodisperse SiO2-NH2 microspheres were added to the modifying solvent, and hexamethyldisilazane was added. The reaction was carried out at a temperature of 70-90℃ and under stirring conditions. After centrifugation and washing, hydrophobically modified SiO2 was obtained.

[0010] S2. Add the oil phase solution containing hydrophobically modified SiO2 to the sodium alginate aqueous solution to obtain a sodium alginate emulsion; under stirring conditions, add calcium chloride aqueous solution dropwise to the sodium alginate emulsion, then add isopropanol for curing, and after centrifugation and washing, obtain the amphiphilic Janus SiO2 / calcium alginate composite microsphere modulator.

[0011] As a further preferred technical solution of the present invention, in the modified solvent of step S1, the volume ratio of anhydrous ethanol to water is 6:4-8:2.

[0012] As a further preferred technical solution of the present invention, the average particle size of the monodisperse SiO2-NH2 microspheres in step S1 is 40-60 nm.

[0013] As a further preferred technical solution of the present invention, step S1 specifically includes:

[0014] Monodisperse SiO2-NH2 microspheres were vacuum dried at 60-80℃ for 3-6 hours, added to 150-200 ml of modified solvent, heated to 70-90℃ at 200-300 rpm, and hexamethyldisilazane was added. At this temperature, the mixture was stirred at 200-300 rpm for 2-3 hours. After cooling to room temperature, the microspheres were washed multiple times with anhydrous ethanol, centrifuged at 5500-6500 rpm, and dried in a vacuum drying oven at 60-80℃ for 6-12 hours to obtain hydrophobically modified SiO2.

[0015] As a further preferred embodiment of the present invention, the mass ratio of hexamethyldisilazane to silicon dioxide in monodisperse SiO2-NH2 microspheres is 1:1 to 1:6.

[0016] As a further preferred embodiment of the present invention, the monodisperse SiO2-NH2 microspheres in step S1 are prepared by the following steps:

[0017] Mix 50-100 ml of anhydrous ethanol, 2.5-5 ml of concentrated ammonia and 1-2 ml of deionized water, place in an oil bath at 40-50 °C, add 1.5-3 ml of tetraethoxysilane, and react at a stirring speed of 200-300 rpm for 6-12 h to obtain monodisperse SiO2-NH2 microspheres.

[0018] As a further preferred technical solution of the present invention, step S2 specifically includes:

[0019] Prepare 20-30 ml each of 2-4 wt% sodium alginate aqueous solution and 4-8 wt% calcium chloride aqueous solution; add 80-120 ml of oil phase solution containing 150-225 mg of hydrophobically modified SiO2 to the sodium alginate aqueous solution to obtain sodium alginate emulsion.

[0020] Calcium chloride aqueous solution was added dropwise to sodium alginate emulsion at a rate of 0.5-0.8 ml / min, while stirring at a rate of 550-650 rpm; 40-120 ml of isopropanol was added for solidification, centrifuged at 5500-6500 rpm, and then washed several times with anhydrous ethanol to obtain amphiphilic Janus SiO2 / calcium alginate composite microsphere modulator.

[0021] As a further preferred embodiment of the present invention, the oil phase solution is a liquid paraffin solution containing 5 v / v% sorbitan oleate Span 80.

[0022] According to another aspect of the present invention, the present invention also provides an amphiphilic Janus SiO2 / calcium alginate composite microsphere modulator, which is prepared by the above-described method.

[0023] According to another aspect of the present invention, the present invention also provides the application of amphiphilic Janus SiO2 / calcium alginate composite microsphere modulator in crude oil extraction.

[0024] Compared with the prior art, the present invention has the following beneficial technical effects:

[0025] (1) In this invention, amphiphilic Janus SiO2 nanoparticles were used to replace traditional emulsifiers, and amphiphilic Janus SiO2 / calcium alginate composite microspheres were synthesized based on Pickering emulsion polymerization. As a novel modulator, this invention reduces the use of emulsifiers and lowers the synthesis cost.

[0026] (2) This invention uses biodegradable calcium alginate to replace traditional acrylamide-based synthetic polymers, which reduces damage to the formation and avoids pollution caused by the use of white oil in the synthesis process of acrylamide-based polymer microspheres, thus exhibiting excellent environmental performance.

[0027] (3) The amphiphilic Janus SiO2 / calcium alginate composite microsphere modulator of the present invention has the characteristics of high hardness and high strength of the inorganic component SiO2 of the composite microsphere, which increases the strength of the modulator material. The organic component calcium alginate of the composite microsphere has swelling properties, which increases the elasticity and expansion capacity of the material, giving the material excellent strength and elasticity.

[0028] (3) The amphiphilic Janus SiO2 / calcium alginate composite microsphere modifier of the present invention exerts an oil displacement effect through the synergistic effect of calcium alginate and Janus SiO2 nanoparticles. The calcium alginate microspheres have the ability to modulate the profile and can effectively block the pores, thereby adjusting the water drive profile and improving the water drive efficiency. The free Janus SiO2 nanoparticles in the aqueous dispersion have a nano effect, which can reduce the adhesion work required to strip crude oil by changing the wettability of the reservoir rock surface and reducing the oil-water interfacial tension, thereby promoting the stripping of crude oil from the rock surface. Thus, a high-performance new modifier system integrating profile modification and oil displacement performance is constructed. Attached Figure Description

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0030] Figure 1 SEM images of the amphiphilic Janus SiO2 / calcium alginate prepared for Examples 1 and 2 (a is Example 1; b is Example 2).

[0031] Figure 2 The graphs show the relationship between pressure (P) and injected fluid volume (PV) in the driving performance test of Examples 1 and 2 (a is Example 1; b is Example 2).

[0032] Figure 3 The contact angle of the core surface is shown in Figure 1 (a represents the untreated core; b represents the core treated with composite microspheres).

[0033] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0034] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0035] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which this invention pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0036] This invention employs a Pickering emulsion-ionic polymerization method, which is simpler to operate than traditional emulsion polymerization, produces purer products, and the emulsion is less affected by factors such as pH and oil phase composition, thus making the reaction process easier to control. Non-toxic hexamethyldisilazane is used to hydrophobically modify nano-SiO2, and Janus SiO2 particles act as Pickering particles to stabilize the W / O emulsion, while the W / O emulsion also serves as the reaction site for ionic crosslinking. Calcium alginate is selected as the main polymer modifier matrix, reducing damage to the formation and thus achieving a green modifier system that synergistically enhances oil displacement with Janus SiO2 particles.

[0037] Amphiphilic Janus SiO2 nanoparticles exhibit better interfacial activity and stability compared to uniformly surfaced nano-SiO2. When used as an oil displacement agent in the field of enhanced oil recovery in low-permeability reservoirs, they not only possess high strength, excellent high-temperature resistance, and environmental friendliness, but also enhance the oil displacement capacity of traditional modulators.

[0038] This invention uses amphiphilic Janus SiO2 nanoparticles as emulsifiers to stabilize emulsions and synthesizes amphiphilic Janus SiO2 nanoparticle / calcium alginate composite microspheres. The amphiphilic Janus SiO2 nanoparticles improve the strength and toughness of the modulating and displacing material, while calcium alginate improves the elasticity and expansibility of the modulating and displacing material. The surface activity of the amphiphilic Janus SiO2 nanoparticles enhances the injectability and oil displacement ability of the modulating and displacing agent, while calcium alginate improves the blocking and profile control performance of the modulating and displacing agent, thus realizing a high-performance modulating and displacing system with synergistic oil displacement.

[0039] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described in detail below through specific embodiments.

[0040] Example 1

[0041] The preparation method of the amphiphilic Janus SiO2 / calcium alginate composite microsphere modulator provided in this embodiment is as follows:

[0042] S1. Mix 50 ml of anhydrous ethanol, 2.5 ml of concentrated ammonia and 1 ml of deionized water, add 1.5 ml of tetraethoxysilane to the mixture in an oil bath at 45 °C and stirring at 200 rpm. After 12 h, monodisperse SiO2-NH2 microspheres with an average particle size of 54 nm are obtained.

[0043] S2. The product obtained in S1 was vacuum dried at 60°C for 6 hours and added to a mixture of 150 ml of anhydrous ethanol and water (volume ratio 6:4). The mixture was heated to 80°C at 200 rpm and 0.5 g of hexamethyldisilazane was added. The mixture was stirred at 200 rpm at 60°C for 3 hours. After cooling to room temperature, the product was washed three times with anhydrous ethanol, centrifuged at 6000 rpm, and then dried in a vacuum drying oven at 70°C for 12 hours to obtain hydrophobically modified SiO2.

[0044] S3. Prepare 20 ml of 2 wt% sodium alginate aqueous solution and 20 ml of 4 wt% calcium chloride aqueous solution respectively. Add 80 ml of oil phase solution containing 150 mg of hydrophobically modified SiO2 to the 2 wt% sodium alginate aqueous solution to obtain sodium alginate emulsion.

[0045] S4. Add the calcium chloride aqueous solution dropwise to the sodium alginate emulsion obtained in S3 at a rate of 0.5 ml / min, while stirring the sodium alginate emulsion at a rate of 600 rpm.

[0046] S5. Add 80 ml of isopropanol for curing, centrifuge at 6000 rpm, and wash three times with anhydrous ethanol to obtain the amphiphilic Janus SiO2 / calcium alginate composite microsphere revegetative agent (hereinafter referred to as composite microsphere revegetative agent). The obtained product is as follows: Figure 1 As shown in (a), this is a SEM image of the amphiphilic Janus SiO2 / calcium alginate composite microspheres. The composite material is regularly spherical with a particle size of approximately 2-5 μm.

[0047] The modulating performance test of the composite microsphere modulating agent prepared in this embodiment:

[0048] Based on oilfield core samples, the original oil-bearing and water-saturation levels of the formation were established by injecting saturated water and saturated oil into the cores, simulating the original formation state. Then, by injecting simulated water and composite microsphere flooding agents into the cores, three stages were conducted: waterflooding, composite microsphere flooding, and subsequent waterflooding. The oil displacement performance was analyzed, such as... Figure 2 As shown in (a). By Figure 2 It can be seen that in the water-drive stage (0-1 PV), the pressure is relatively low and stable; in the composite microsphere flooding stage (1-2 PV), it can be seen that after injecting the synthesized composite microsphere modulator, the injection pressure significantly increases to about 4 MPa, and a step-like pattern appears, indicating that the composite microsphere modulator performs a process of sealing, migration, and re-sealing of the core pores; in the subsequent water-drive stage (2-3 PV), it can be observed that the pressure increases to 4.5 MPa, but shows a gradual trend. Figure 2 The pressure indicates that the composite microsphere modulator has good modulator performance for core samples.

[0049] Example 2

[0050] The preparation method of the amphiphilic Janus SiO2 / calcium alginate composite microsphere modulator provided in this embodiment is as follows:

[0051] S1. Mix 100ml anhydrous ethanol, 5ml concentrated ammonia and 2ml deionized water, add 3ml tetraethoxysilane to the mixture in an oil bath at 45℃ and stirring at 300rpm. After 12h, monodisperse SiO2-NH2 microspheres with an average particle size of 45nm are obtained.

[0052] S2. The product obtained in S1 was vacuum dried at 80℃ for 3 hours, added to a mixture of 200 ml anhydrous ethanol and water (volume ratio 6:4), heated to 90℃ at 200 rpm, and 0.6 g of hexamethyldisilazane was added. The mixture was stirred at 200 rpm at 80℃ for 3 hours, then cooled to room temperature, washed three times with anhydrous ethanol, centrifuged at 6500 rpm, and then dried in a vacuum drying oven at 80℃ for 6 hours to obtain hydrophobically modified SiO2.

[0053] S3. Prepare 30 ml each of 4 wt% sodium alginate aqueous solution and 8 wt% calcium chloride aqueous solution. Add 120 ml of oil phase solution containing 225 mg of hydrophobically modified SiO2 to the 4 wt% sodium alginate aqueous solution to obtain sodium alginate emulsion.

[0054] S4. Add the calcium chloride aqueous solution dropwise to the sodium alginate emulsion obtained in S3 at a rate of 0.8 ml / min, while stirring the sodium alginate emulsion at a rate of 650 rpm.

[0055] S5. Add 100 ml of isopropanol for curing, centrifuge at 6000 rpm, and wash three times with anhydrous ethanol to obtain the amphiphilic Janus SiO2 / calcium alginate composite microsphere revegetative agent (hereinafter referred to as the composite microsphere revegetative agent). The obtained product is as follows: Figure 1 (b) shows a SEM image of Janus SiO2 / calcium alginate composite microspheres. The composite material is regularly spherical with a particle size of approximately 10 μm.

[0056] The modulating performance test of the composite microsphere modulating agent prepared in this embodiment:

[0057] Based on oilfield core samples, the original oil-bearing and water-saturation levels of the formation were established by injecting saturated water and saturated oil into the cores, simulating the original formation state. Then, by injecting simulated water and composite microsphere flooding agents into the cores, three stages were conducted: waterflooding, composite microsphere flooding, and subsequent waterflooding. The oil displacement performance was analyzed, such as... Figure 2 As shown in (b). Figure 2It can be seen that in the waterflooding stage (0-1 PV), the pressure is relatively low and stable; in the composite microsphere flooding stage (1-2 PV), it can be seen that after the injection of the synthesized composite microsphere modulator, the injection pressure significantly increases to about 4 MPa, and a step-like pattern appears, indicating that the composite microsphere modulator performs a process of sealing, migration, and resealing of the core pores; in the subsequent waterflooding stage (2-3 PV), it can be observed that the pressure increases to 4.3 MPa, but shows a gradual trend. Figure 2 The pressure indicates that the composite microsphere modulator has modulatory properties for core samples. Figure 3 The change in contact angle indicates that the core sample treated with the composite microsphere modulator ( Figure 3 (b) Make the untreated core oil-wetted (greater than 90°) Figure 3 In step a), the water becomes wet (less than 90°), effectively reducing the oil-water interfacial tension and exhibiting oil displacement properties. This demonstrates that the present invention successfully constructs a high-performance novel profile control and oil displacement system integrating profile control and oil displacement performance.

[0058] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and various changes or modifications can be made to these embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is defined only by the appended claims.

Claims

1. A method for preparing an amphiphilic Janus SiO2 / calcium alginate composite microsphere modulator, characterized in that, Includes the following steps: S1. Using anhydrous ethanol-water system as the modifying solvent, dry monodisperse SiO2-NH2 microspheres were added to the modifying solvent, and hexamethyldisilazane was added. The reaction was carried out at a temperature of 70-90℃ and under stirring conditions. After centrifugation and washing, hydrophobically modified SiO2 was obtained. S2. Add the oil phase solution containing hydrophobically modified SiO2 to the sodium alginate aqueous solution to obtain a sodium alginate emulsion; under stirring conditions, add calcium chloride aqueous solution dropwise to the sodium alginate emulsion, then add isopropanol for curing, and after centrifugation and washing, obtain the amphiphilic Janus SiO2 / calcium alginate composite microsphere modulator.

2. The preparation method of the amphiphilic Janus SiO2 / calcium alginate composite microsphere modulator according to claim 1, characterized in that, In the modified solvent of step S1, the volume ratio of anhydrous ethanol to water is 6:4-8:

2.

3. The preparation method of the amphiphilic Janus SiO2 / calcium alginate composite microsphere modulator according to claim 1, characterized in that, The average particle size of the monodisperse SiO2-NH2 microspheres in step S1 is 40-60 nm.

4. The preparation method of the amphiphilic Janus SiO2 / calcium alginate composite microsphere modulator according to claim 1, characterized in that, Step S1 specifically includes: Monodisperse SiO2-NH2 microspheres were vacuum dried at 60-80℃ for 3-6 hours, added to 150 ml of modified solvent, heated to 70-90℃ at 200-300 rpm, and hexamethyldisilazane was added. At this temperature, the mixture was stirred at 200-300 rpm for 2-3 hours. After cooling to room temperature, the microspheres were washed several times with anhydrous ethanol, centrifuged at 5500-6500 rpm, and dried in a vacuum drying oven at 60-80℃ for 6-12 hours to obtain hydrophobically modified SiO2.

5. The preparation method of the amphiphilic Janus SiO2 / calcium alginate composite microsphere modulator according to claim 4, characterized in that, The mass ratio of hexamethyldisilazane to silica in monodisperse SiO2-NH2 microspheres is 1:1 to 1:

6.

6. The preparation method of the amphiphilic Janus SiO2 / calcium alginate composite microsphere modulator according to claim 1, characterized in that, The monodisperse SiO2-NH2 microspheres in step S1 are prepared through the following steps: Mix 50-100 ml of anhydrous ethanol, 2.5-5 ml of concentrated ammonia and 1-2 ml of deionized water, place in an oil bath at 40-50 °C, add 1.5-3 ml of tetraethoxysilane, and react at a stirring speed of 200-300 rpm for 6-12 h to obtain monodisperse SiO2-NH2 microspheres.

7. The preparation method of the amphiphilic Janus SiO2 / calcium alginate composite microsphere modulator according to claim 1, characterized in that, Step S2 specifically includes: Prepare 20-30 ml each of 2-4 wt% sodium alginate aqueous solution and 4-8 wt% calcium chloride aqueous solution; add 80-120 ml of oil phase solution containing 150-225 mg of hydrophobically modified SiO2 to the sodium alginate aqueous solution to obtain sodium alginate emulsion. Calcium chloride aqueous solution was added dropwise to sodium alginate emulsion at a rate of 0.5-0.8 ml / min, while stirring at a rate of 550-650 rpm; 40-120 ml of isopropanol was added for solidification, centrifuged at 5500-6500 rpm, and then washed several times with anhydrous ethanol to obtain amphiphilic Janus SiO2 / calcium alginate composite microsphere modulator.

8. The preparation method of the amphiphilic Janus SiO2 / calcium alginate composite microsphere modulator according to claim 7, characterized in that, The oil phase solution is a liquid paraffin solution containing 5 v / v% Span 80.

9. A Janus SiO2 / calcium alginate composite microsphere modulator, characterized in that, It is prepared by the method described in any one of claims 1-8.

10. The application of the amphiphilic Janus SiO2 / calcium alginate composite microsphere modulator as described in claim 9 in crude oil extraction.

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