CN118406247B - Silicon-based nano in-situ emulsification drag reducer and preparation method thereof - Google Patents

Abstract

The invention discloses a silicon-based nano in-situ emulsified drag reducer and a preparation method thereof, and relates to the technical field of oilfield chemistry. The preparation method comprises the following steps: taking nano silicon dioxide and oscillating and dispersing it uniformly in an ethanol solution at room temperature, then adding a silane coupling agent, passing nitrogen to deoxygenate, sealing and stirring to react, purifying and drying to obtain modified nano silicon dioxide, then oscillating and dispersing the modified nano silicon dioxide, polyether F127 and sodium alpha-olefin sulfonate in anhydrous ethanol, sealing and stirring to react, purifying and drying to obtain the silicon-based nano in-situ emulsified drag reducer SAP. The preparation method of the silicon-based nano in-situ emulsified drag reducer is simple, the drag reducer is enhanced and quickly dissolved, the preparation and construction costs are low, the interfacial tension between the silicon-based nano in-situ emulsified drag reducer and crude oil can reach the order of ^10-1 mN/m, the wettability of the oil reservoir can be significantly improved, and the adhesion work of crude oil on the rock surface can be effectively reduced. The silicon-based nano in-situ emulsified drag reducer is suitable for medium and low permeability water injection development oil reservoirs including high temperature and high salt, and has a wide range of applications.

Description

Silicon-based nano in-situ emulsified drag reducer and preparation method thereof

Technical Field

The invention relates to the technical field of oilfield chemistry, in particular to a silicon-based nano in-situ emulsified drag reducer and a preparation method thereof.

Background Art

With the advancement of oil development technology, unconventional oil resources such as heavy oil that were difficult to develop in the past have received more and more attention. However, due to the poor fluidity of heavy oil and water, the fingering phenomenon of injected water is serious and the sweep coefficient is low, resulting in a low recovery rate for heavy oil. The recovery rate of conventional water-driven heavy oil is generally 10-20%. Since the development of tertiary oil recovery methods, the oil industry has been looking for new technologies to improve the recovery rate.

Heavy oil has become the focus of residual oil resource development due to its abundant reserves, high viscosity and poor fluidity. Measures to reduce viscosity are necessary to reduce the flow resistance of heavy oil/extra-heavy oil and increase its fluidity. Thermal, dilution, chemical and biological methods are commonly used recovery technologies for heavy oil reservoirs in different scenarios. Steam-based thermal methods, including cyclic steam stimulation (CSS) and steam-assisted gravity drainage (SAGD), are costly and environmentally challenging. Chemical flooding is widely used due to its economic effectiveness. Typically, chemical flooding methods use surfactants, polymers and alkalis, sometimes in combination, to enhance recovery. With the increase in energy demand, oil companies are forced to find new solutions to recover the oil left behind after secondary oil recovery. Therefore, when nanotechnology has become the main means to solve other industrial problems, oil researchers have also begun to pay attention to nanotechnology to seek possible solutions to these problems.

Compared with traditional chemical flooding technology to enhance oil recovery, modified nanoparticle dispersion systems used in chemical flooding have good production and injection enhancement effects. Nanoparticles (NPs) are tiny (1-100nm) particles with excellent penetration and adsorption capabilities, adjustable physicochemical properties and unique thermal properties. Due to their small size, NPs are allowed to pass through tiny pores and narrow throats that larger materials cannot reach, and have good shear resistance, salt resistance and thermal stability, avoiding precipitation in high-temperature and high-mineralization formations. In recent decades, nanotechnology has rapidly become a new dominant technology that can compete with traditional methods technically and economically. The application of nanotechnology in the oil and gas industry provides unprecedented opportunities for the development of more economical, efficient and environmentally friendly oil and gas extraction technologies.

For example, Zargartalebi et al. demonstrated that lower IFTs can be achieved at certain concentrations of nanoparticles. Nguyen et al. designed surfactant/polymer inorganic nanocomposites for enhanced oil recovery in high-temperature, high-salinity offshore reservoirs. The results showed that the nanocomposites were very effective in reducing interfacial tension. In core flooding experiments, an additional 6.2% of oil could be recovered at 92°C and 800 ppm salinity.

It can be seen that compared with the traditional chemical flooding technology to enhance oil recovery, the modified nanoparticle system used in chemical flooding will have a good production increase effect. Therefore, in view of the current low recovery rate of heavy oil reservoirs, designing efficient nanofluid flooding agents to form relatively stable O/W low-viscosity emulsions is the key to solving the problem of low recovery rate of heavy oil reservoirs.

Summary of the invention

In view of this, the present invention proposes a silicon-based nano in-situ emulsified drag reducer and a preparation method thereof. The silicon-based nano in-situ emulsified drag reducer is prepared by reacting nano silicon dioxide modified by a silane coupling agent with polyether F127 and sodium α-olefin sulfonate (AOS). The silicon-based nano in-situ emulsified drag reducer can achieve an interfacial tension with crude oil of the order of 10 ^-1 mN/m, synergistically improve the wettability of the reservoir, reduce the adhesion work of crude oil, and induce the formation of a Pickering emulsion, thereby reducing flow resistance and significantly improving crude oil recovery.

The present invention discloses a method for preparing a silicon-based nano in-situ emulsified drag reducer, comprising the following steps:

Step S1: taking nano-silicon dioxide and dispersing it uniformly in an ethanol solution by oscillation at room temperature, then adding a silane coupling agent, passing nitrogen to remove oxygen, and then sealing and stirring to react, purifying and drying to obtain modified nano-silicon dioxide;

Step S2: uniformly disperse the modified nano-silica, polyether F127 and sodium α-olefin sulfonate in anhydrous ethanol by oscillation, remove oxygen by nitrogen, and then seal and stir to react, purify and dry to obtain the silicon-based nano-in-situ emulsified drag reducer.

An embodiment of the present invention is that the particle size of the nano-silicon dioxide is 20 nm.

An embodiment of the present invention is that, in parts by weight, the ratio of the nano-silicon dioxide to the silane coupling agent is 1:0.5-6.

In one embodiment of the present invention, the silane coupling agent is γ-aminopropyltriethoxysilane.

One embodiment of the present invention is that the reaction conditions of the nano-silicon dioxide and the silane coupling agent are: after nitrogen deoxygenation for 30 minutes, the reaction is sealed and stirred at 100-120° C. for 6-8 hours.

An embodiment of the present invention is that, in parts by weight, the ratio of the modified nano-silica to the polyether F127 is 1:2.5-7.5.

An embodiment of the present invention is that, in parts by weight, the ratio of the modified nano-silica to sodium α-olefin sulfonate is 1:1.25-5.

One embodiment of the present invention is that the degree of polymerization of the polypropylene oxide block in the polyether F127 is n=30, the degree of polymerization of the polyethylene oxide single block is n=40, and the carbon chain range of the sodium α-olefin sulfonate is C _n =14-16.

One embodiment of the present invention is that the reaction conditions of the modified nano-silica, polyether F127 and sodium α-olefin sulfonate are: after nitrogen deoxygenation for 30 minutes, sealed stirring reaction is carried out at 110-120° C. for 3-5 hours.

In addition, the invention also discloses a silicon-based nano in-situ emulsified drag reducer prepared by the method.

The technical effects of the present invention are:

(1) The preparation method of the silicon-based nano in-situ emulsified drag reducer in the present invention is simple, the principle is reliable, the synthesis process is simple, and the drag reducer is enhanced and quickly dissolved. No additional injection system is required, and the water injection system and sewage injection can be directly used, and the preparation and construction costs are low.

(2) The interfacial tension between the silicon-based nano-in-situ emulsified drag reducer and crude oil can reach the order of 10 ^-1 mN/m. The silicon-based nano-in-situ emulsified drag reducer improves the wettability of the reservoir and can effectively reduce the adhesion work of crude oil on the rock surface.

(3) The silicon-based nano-emulsified drag reducer in the present invention can be adsorbed on the oil-water interface under shearing to form a Pickering emulsion. The viscosity of the Pickering emulsion is lower than the viscosity of the oil phase, thereby reducing the flow resistance.

(4) The silicon-based nano-in-situ emulsified drag reducer of the present invention is suitable for medium and low permeability water injection development of oil reservoirs including high temperature and high salinity, and has a wide range of applications.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a reaction flow chart for preparing a silicon-based nano in-situ emulsified drag reducer in the present invention;

FIG2 is an infrared characterization result diagram of the silicon-based nano in-situ emulsified drag reducer of the present invention;

FIG3 is a graph showing the thermogravimetric characterization results of the silicon-based nano in-situ emulsified drag reducer of the present invention;

FIG4 is a microscopic morphology diagram of Example 1 of the present invention;

FIG5 is a microscopic morphology diagram of Example 2 of the present invention;

FIG6 is a microscopic morphology diagram of Example 3 of the present invention;

FIG. 7 is a graph showing the particle size distribution results of Example 1 of the present invention;

FIG8 is a graph showing the particle size distribution results of Example 2 of the present invention;

FIG9 is a graph showing the particle size distribution results of Example 3 of the present invention;

FIG10 is a graph showing the dispersibility test results of the silicon-based nano in-situ emulsified drag reducer of the present invention;

FIG11 is a graph showing the interfacial tension reduction test results of the silicon-based nano in-situ emulsified drag reducer of the present invention;

FIG12 is a graph showing the results of the silicon-based nano in-situ emulsified drag reducer in the present invention in improving rock wettability;

FIG13 is a diagram for evaluating the oil displacement performance of Example 1 of the present invention;

FIG14 is a diagram for evaluating the oil displacement performance of Example 2 of the present invention;

FIG. 15 is a diagram for evaluating the oil displacement performance of Example 3 of the present invention.

DETAILED DESCRIPTION

The present invention will be further described in detail below in conjunction with the examples, but the embodiments of the present invention are not limited thereto. The experimental methods used in the following examples are conventional methods unless otherwise specified; the materials, reagents, etc. used therein are all commercially available unless otherwise specified.

Example 1: Step S1: Add 3 g of silica with a particle size of 20 nm to a 250 mL three-necked flask, then add a mixture of 150 g of ethanol and water (volume ratio of ethanol to water v/v=1/1), and perform ultrasonic oscillation for 30 min to uniformly disperse the nano-silica. Then, add 3 g of γ-aminopropyltriethoxysilane to the three-necked flask containing the nano-silica dispersion under an oil bath at 100° C., pass nitrogen to deoxygenate for 30 min, seal and stir for grafting reaction for 6 h, purify and dry to obtain amino-terminated modified nano-silica;

Step S2: 4 g of the modified nano-silica prepared in step S1 was added to a 250 mL three-necked bottle, and then 30 g of anhydrous ethanol was added, and ultrasonic oscillation was performed for 30 min to fully and evenly disperse the modified nano-silica. Subsequently, 15 g of polyether F127 and 10 g of AOS were added to the three-necked bottle containing the modified nano-silica, and nitrogen was passed to deoxygenate for 30 min. The grafting reaction was sealed and stirred in an oil bath at 120° C. for 3 h, and the silicon-based nano in-situ emulsified drag reducer was obtained by purification and drying.

Example 2: Step S1: 3 g of silica with a particle size of 20 nm was added to a 250 mL three-necked flask, and then a mixture of 150 g of ethanol and water (volume ratio of ethanol to water v/v=1/1) was added, and ultrasonic oscillation was performed for 30 min to make the nano-silica dispersed evenly. Then, 5 g of γ-aminopropyltriethoxysilane was added to the three-necked flask containing the nano-silica dispersion under an oil bath at 100° C., and nitrogen was passed to deoxygenate for 30 min. The grafting reaction was sealed and stirred for 6 h, and then purified and dried to obtain amino-terminated modified nano-silica;

Step S2: 4 g of the modified nano-silica prepared in step S1 was added to a 250 mL three-necked bottle, and then 30 g of anhydrous ethanol was added, and ultrasonic oscillation was performed for 30 min to fully and evenly disperse the modified nano-silica. Subsequently, 15 g of polyether F127 and 10 g of AOS were added to the three-necked bottle containing the modified nano-silica, and nitrogen was passed to deoxygenate for 30 min. The grafting reaction was sealed and stirred in an oil bath at 120° C. for 3 h, and the silicon-based nano in-situ emulsified drag reducer was obtained by purification and drying.

Example 3: Step S1: Add 2 g of silica with a particle size of 20 nm to a 250 mL three-necked flask, then add a mixture of 150 g of ethanol and water (volume ratio of ethanol to water v/v=1/1), and perform ultrasonic oscillation for 30 min to uniformly disperse the nano-silica. Then, add 6 g of γ-aminopropyltriethoxysilane to the three-necked flask containing the nano-silica dispersion under an oil bath at 100° C., pass nitrogen to deoxygenate for 30 min, seal and stir for grafting reaction for 6 h, purify and dry to obtain amino-terminated modified nano-silica.

Step S2: 4 g of the modified nano-silica prepared in step S1 was added to a 250 mL three-necked bottle, and then 30 g of anhydrous ethanol was added, and ultrasonic oscillation was performed for 30 min to fully and evenly disperse the modified nano-silica. Subsequently, 15 g of polyether F127 and 10 g of AOS were added to the three-necked bottle containing the modified nano-silica, and nitrogen was passed to deoxygenate for 30 min. The grafting reaction was sealed and stirred in an oil bath at 120° C. for 3 h, and the silicon-based nano in-situ emulsified drag reducer was obtained by purification and drying.

In order to better illustrate the technical effects of the present invention, performance evaluations are provided below for relevant embodiments or comparative examples.

1. Infrared characterization of silicon-based nano-in-situ emulsified drag reducer:

The entire reaction process for preparing the silicon-based nano in-situ emulsified drag reducer is shown in FIG1 . The molecular formula of the product can be seen in FIG1 . On this basis, the silicon-based nano in-situ emulsified drag reducer products in Examples 1, 2, and 3 and the unmodified nano-silica were subjected to infrared characterization tests, and the results are shown in FIG2 . As can be seen in FIG2 , the absorption peaks near 429 cm ^-1 and 1633 cm ^-1 are the stretching vibration absorption peaks of Si-OH and surface water, respectively, the absorption peaks near 1107 cm ^-1 and 803 cm ^-1 are the antisymmetric and symmetric stretching vibration absorption peaks of Si-O-Si, respectively, and the bending vibration peak near 473 cm ^-1 is the Si-O-Si. In the results of all the examples, the transmittance at 3429 cm ^-1 increased slightly, indicating that Si-OH decreased and γ-aminopropyltriethoxysilane was successfully grafted. The new peaks near 2921, 2852 and 1466 cm ^-1 were the stretching vibration peaks and bending vibration peaks of -R, _-CH3 , _-CH2- and -CH-, respectively. The peak near 1487 cm ^-1 was the stretching vibration absorption peak of C—N in γ-aminopropyltriethoxysilane. By comparison, it was found that the vibration peaks of the products of Examples 1, 2 and 3 at around 1107 cm ^-1 were significantly enhanced and broadened, which was attributed to the characteristic absorption peaks of _-SO3 on AOS and _-CH2 -O- _CH2- on F127 at around 1178 and 1103 cm ^-1 , respectively.

2. Thermogravimetric characterization of silicon-based nano-in-situ emulsified drag reducer:

The silicon-based nano in-situ emulsified drag reducer products and unmodified nano silicon dioxide in Examples 1, 2, and 3 were subjected to thermogravimetric tests, and the results are shown in Figure 3. As can be seen in Figure 3, the unmodified nano SiO ₂ has a small amount of mass loss before 200°C, mainly due to the evaporation of water molecules on its surface and the decomposition of hydroxyl groups, and the mass remains basically unchanged after the temperature is greater than 200°C. The heat loss of the products of each example mainly occurs at 250-550°C, mainly due to the high-temperature decomposition of organic matter grafted on its surface.

3. Microstructure and particle size distribution test of silicon-based nano-in-situ emulsified drag reducer:

The microscopic morphologies of Examples 1, 2, and 3 are shown in Figures 4 to 6, respectively, and the particle size distributions of the three are shown in Figures 7 to 9, respectively. It can be seen that relative to the average particle size of 20 nm of the nano-silica before modification, the particle sizes of the products of Examples 1, 2, and 3 are mainly distributed in the range of 30 to 50 nm, proving that polyether F127 and AOS were successfully grafted onto the surface of the nano-silica.

4. Dispersion performance test:

Although there are a large number of hydroxyl groups (-OH) on the surface of nano-silicon dioxide, the overall performance of the particles is still hydrophobic. The nano-silicon dioxide is closely arranged to form a hydrophobic skeleton, and the hydrophilicity can be significantly improved by modifying and grafting corresponding groups. Examples 1, 2, and 3 were added to formation water (mineralization 6×10 ⁴ mg/L, Ca ²⁺ and Mg ²⁺ concentrations of 2×10 ³ mg/L, respectively), and respectively prepared into solutions with a mass concentration of 0.3%, and the nano-silicon dioxide before modification was added to the formation water in the same proportion as the control group, and the dispersion was observed. The results are shown in Figure 10. In Figure 10, from left to right are the solutions of Example 1, Example 2, and Example 3. After Examples 1, 2, and 3 were hydrophilically modified, the surfaces were connected with polyether F127 and AOS, and the hydrophilicity was significantly increased, and the dispersion and swelling properties in the aqueous phase were significantly increased.

Through the above performance tests, it can be seen that in Examples 1, 2, and 3, silicon-based nano in-situ emulsified drag reducers with polyether F127 and AOS grafted on the surface of nano-silicon dioxide are successfully prepared.

5. Emulsification system viscosity performance test:

Prepare mineralized water with a mineralization degree of 6×10 ⁴ mg/L (Ca ²⁺ and Mg ²⁺ concentrations of 2×10 ³ mg/L, respectively), and prepare the products in Examples 1, 2, and 3 into solutions with a mass concentration of 0.3%. In a 50 mL measuring cylinder, the solution and dehydrated crude oil (viscosity of 723.7 mPa·s at a shear rate of 7.34 s ^-1 at 75 °C) were mixed and sealed at a water-oil volume ratio of 5:5, 6:4, 7:3, 8:2 (water content of 50%, 60%, 70%, and 80%) to prepare an emulsion system with a total volume of 30 mL, and then stirred for 30 minutes in a 75 °C water bath to observe the emulsification. After stirring, the apparent viscosity of the emulsion was tested with a DV-III viscometer at 75 °C and a shear rate of 7.34 s ^-1 . The specific results are shown in Table 1.

Table 1 Viscosity of emulsion formed by nano drag reduction and oil displacement agent solution and crude oil

From the results in Table 1, it can be seen that the silicon-based nano-emulsified drag reducer can be adsorbed on the oil-water interface under shear induction, and can form Pickering emulsions under the conditions of water content of 50-80%. Since the viscosity of Pickering emulsion is lower than that of crude oil, it has the function of improving crude oil viscosity and increasing crude oil recovery.

6. Test on interfacial tension reduction performance of silicon-based nano-in-situ emulsified drag reducer:

The interfacial tension (IFT) of crude oil (viscosity 723.7 mPa·s) after being dripped into the formation water solution of each embodiment was measured by using a Kruess SDT spinning drop interfacial tension meter, wherein the mass concentration of each embodiment in the formation water was 0.3%, and crude oil was dripped into the formation water as a control group for measurement, and the interfacial tension of the control group was measured to be 21.6 mN/m, and the measurement results of the remaining embodiments are shown in FIG11. It can be seen that the IFT of the system after the crude oil is mixed with the three embodiment solutions can be reduced to 1.25~1.46 mN/m, proving that the silicon-based nano in-situ emulsified drag reducer in the present invention has a good interfacial tension reduction effect.

7. Test on the rock wettability improvement performance of silicon-based nano-in-situ emulsified drag reducer:

At 75°C, the oil-wet rock slices were immersed in a solution of 0.3% mass concentration prepared by the silicon-based nano-in-situ emulsified drag reducer in Examples 1, 2, and 3 and formation water (mineralization 6×10 ⁴ mg/L, Ca ²⁺ and Mg ²⁺ concentrations of 2×10 ³ mg/L, respectively) for 24 hours. The initial contact angle between the rock slice surface-simulated water-crude oil was 134°. The improvement of wettability was evaluated by measuring the contact angle between the oil-wet rock slice surface-simulated water-crude oil. The results are shown in FIG12. As can be seen from FIG12, after immersion for 24 hours, the contact angle between the oil-wet rock slice surface-simulated water-crude oil decreased from 134° to 43°~48°, indicating that the silicon-based nano-in-situ emulsified drag reducer can improve the oil-wet surface of the rock into a water-wet surface, and the wettability improvement effect is obvious.

8. Oil displacement performance test:

The oil displacement capacity of the emulsified system with a mass concentration of 0.3% configured in formation water (mineralization 6×10 ⁴ mg/L, Ca ²⁺ and Mg ²⁺ concentrations of 2×10 ³ mg/L, respectively) in Example 1 under 75°C was studied using a homogeneous core. The gas permeability of the homogeneous core is 400mD; the diameter is 2.5cm, and the length is 5cm; the injection rate during the displacement process is 0.5mL/min. The experimental results are shown in Figure 13. The recovery rate in the front water flooding stage is 50.312%; then the emulsified system solution of the product in Example 1 with a total concentration of 0.3% is injected. During the injection process, the injection pressure first decreases and then increases. O/W type emulsion production is observed at the core outlet, indicating that the silicon-based nano-drag reduction and enhanced oil displacement agent emulsifies with crude oil to form a low-viscosity emulsion, improves the mobility ratio during the displacement process, and ultimately increases the recovery rate by 20.13%.

The oil displacement capacity of the emulsified system with a mass concentration of 0.3% configured in formation water (mineralization 6×10 ⁴ mg/L, Ca ²⁺ and Mg ²⁺ concentrations of 2×10 ³ mg/L, respectively) in Example 2 under 75°C was studied using a homogeneous core. The gas permeability of the homogeneous core is 400mD; the diameter is 2.5cm, and the length is 5cm; the injection rate during the displacement process is 0.5mL/min. The experimental results are shown in Figure 14. The recovery rate in the front water flooding stage is 41.385%; then the emulsified system solution of the product in Example 2 with a total concentration of 0.3% was injected. During the injection process, the injection pressure first decreased and then increased. O/W type emulsion production was observed at the core outlet, indicating that the silicon-based nano-drag reduction and enhanced oil displacement agent emulsified with crude oil to form a low-viscosity emulsion, which improved the mobility ratio during the displacement process and ultimately increased the recovery rate by 23.15%.

The oil displacement capacity of the emulsified system with a mass concentration of 0.3% configured in formation water (mineralization 6×10 ⁴ mg/L, Ca ²⁺ and Mg ²⁺ concentrations of 2×10 ³ mg/L, respectively) in Example 3 under 75°C was studied using a homogeneous core. The gas permeability of the homogeneous core is 400mD; the diameter is 2.5cm, and the length is 5cm; the injection rate during the displacement process is 0.5mL/min. The experimental results are shown in Figure 15. The recovery rate in the front water flooding stage is 32.385%; then the emulsified system solution of the product in Example 3 with a total concentration of 0.3% was injected. During the injection process, the injection pressure first decreased and then increased. O/W type emulsion production was observed at the core outlet, indicating that the silicon-based nano-drag reduction and enhanced oil displacement agent emulsified with crude oil to form a low-viscosity emulsion, which improved the mobility ratio during the displacement process and ultimately increased the recovery rate by 24.55%.

The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the embodiments of the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims (9)

1. A method for preparing a silicon-based nano in-situ emulsified drag reducer, characterized in that it comprises the following steps: Step S1: taking nano-silicon dioxide and oscillating and dispersing it uniformly in an ethanol solution at room temperature, then adding a silane coupling agent, passing nitrogen to remove oxygen, and then sealing and stirring to react, purifying and drying to obtain modified nano-silicon dioxide, wherein the silane coupling agent is γ-aminopropyltriethoxysilane; Step S2: uniformly disperse the modified nano-silica, polyether F127 and sodium α-olefin sulfonate in anhydrous ethanol by oscillation, remove oxygen by nitrogen, and then seal and stir to react, purify and dry to obtain the silicon-based nano-in-situ emulsified drag reducer. 2. The method for preparing a silicon-based nano in-situ emulsified drag reducer according to claim 1, characterized in that the particle size of the nano silicon dioxide is 20 nm. 3. The method for preparing a silicon-based nano in-situ emulsified drag reducer according to claim 1, characterized in that the ratio of the nano silicon dioxide to the silane coupling agent is 1:0.5-6 in parts by weight. 4. The method for preparing a silicon-based nano-in-situ emulsified drag reducer according to claim 1, characterized in that the reaction conditions of the nano-silicon dioxide and the silane coupling agent are: after nitrogen deoxygenation for 30 minutes, the reaction is sealed and stirred at 100-120° C. for 6-8 hours. 5. The method for preparing a silicon-based nano in-situ emulsified drag reducer according to claim 1, characterized in that the ratio of the modified nano silicon dioxide to the polyether F127 is 1:2.5-7.5 in parts by weight. 6. The method for preparing a silicon-based nano in-situ emulsified drag reducer according to claim 1, characterized in that the ratio of the modified nano silicon dioxide to sodium α-olefin sulfonate is 1:1.25-5 in parts by weight. 7. The method for preparing a silicon-based nano in-situ emulsified drag reducer according to claim 1, characterized in that: the degree of polymerization of the polypropylene oxide block in the polyether F127 is n=30, the degree of polymerization of the polyethylene oxide single block is n=40, and the carbon chain range of the α-olefin sodium sulfonate is C _n =14-16. 8. The method for preparing a silicon-based nano in-situ emulsified drag reducer according to claim 1, characterized in that the reaction conditions of the modified nano-silica, polyether F127, and sodium α-olefin sulfonate are: after nitrogen deoxygenation for 30 minutes, the reaction is sealed and stirred at 110-120°C for 3-5 hours. 9. A silicon-based nano in-situ emulsified drag reducer, characterized in that it is prepared by the method according to any one of claims 1 to 8.