Stability-enhancing oil-based foam oil displacement system based on high-temperature-resistant nanoparticles as well as preparation method and application of stability-enhancing oil-based foam oil displacement system

Abstract

The invention belongs to the technical field of oil exploitation, and particularly relates to an oil-based foam oil displacement system based on stability augmentation of high-temperature-resistant nano-particles and a preparation method and application thereof.The stability augmentation oil-based foam oil displacement system is characterized in that 0.5 wt%-1.5 wt% of nano-particles, 0.5 wt%-2 wt% of a nonionic surfactant Span20 and 0.1 wt%-1.0 wt% of a nonionic surfactant JQ-1 are adopted, the half-life period of foam drainage can be 15-22 min under the conditions that the pressure is 1 MPa and the temperature is 100 DEG C, and the stability augmentation oil-based foam oil displacement system is stable. And the half-life period of foam is 9-15 days. The stability-enhancing oil-based foam oil displacement system based on the high-temperature-resistant nano-particles is high in foaming capacity in an oil solvent, the surface tension of the oil solvent can be remarkably reduced, high foaming performance and foam stability are achieved, and the preparation process is simple, green and environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of petroleum extraction technology, specifically to a high-temperature resistant nanoparticle-stabilized oil-based foam flooding system, its preparation method, and its application. Background Technology

[0002] Foam fluids, due to their ability to effectively control gas flow, have been widely used to enhance oil recovery. Depending on the dispersion medium, foams can be classified into oil-based foams and water-based foams. Oil-based foams use gas as the dispersed phase and oil as the continuous phase. Oil-based foams are primarily generated by oil-soluble foaming agents. Unlike traditional water-based foams, oil-based foams do not defoam upon contact with oil and do not exhibit water-sensitive reactions in formations containing clay minerals. Furthermore, oil-based foam recovery processes are simpler, and oil-water separation of the produced fluid is easier. Oil-based foams can also replenish formation energy, and after bursting during migration, the oil-soluble foaming agent can dissolve into the surrounding crude oil, continuing to generate foam upon contact with gas, enabling deep migration.

[0003] In some oilfields in my country, there are numerous low-permeability, water-sensitive oilfields. These oilfields have narrow formation channels and extremely low permeability, making crude oil flow within the formation very difficult. Furthermore, the formations are often composed of water-sensitive strata such as montmorillonite, which expand upon contact with water, further blocking the already narrow channels and hindering oil production operations. Therefore, conventional waterflooding or water-based foam flooding methods are ineffective for these types of reservoirs. Oil-based foam is therefore more suitable for low-permeability and tight reservoirs with permeability below 10 mD and the presence of water-sensitive formations.

[0004] Patent CN108671850A discloses a fluorosilicone surfactant containing a mono-perfluorooctyl group and an oil-based foam displacement agent. Although the foam obtained by this system is relatively stable, the surfactant is fluorinated, which is expensive and difficult to promote on a large scale. Moreover, it is toxic and pollutes the environment, and its use has been banned in oil fields. Wang Qun. Study on the stabilization mechanism of oil-based foam and its control law on CO2 mobility [D]. China University of Petroleum (East China) used a system formed by compounding surfactant Span20 and fluorinated surfactant F-1 at a concentration ratio of 2:1. The foaming volume in diesel was 275 mL, and the half-life of the liquid was 302 s. However, the foam produced by this system had poor stability, short sealing period, and unsatisfactory effect in oilfield regulation and displacement. Its maximum temperature resistance was only 80℃. Wang Z, Li S, Peng D, et al. The effect of interfacial tension on CO2oil-based foam stability under different temperatures and pressures[J]. Fuel, 2023, 341:127755. Similarly, when using fluorinated surfactants to prepare oil-based foam systems, the foam performance decreases significantly when the temperature exceeds 80℃, making it difficult to meet the actual application requirements in oil fields. Summary of the Invention

[0005] The purpose of this invention is to provide a preparation method and application of an oil-based foam flooding system based on high-temperature resistant nanoparticles. The provided oil-based foam flooding system has strong foaming ability in diesel oil, can significantly reduce the surface tension of oil solvents, has strong foaming performance and foam stability, and the preparation process is simple and environmentally friendly.

[0006] To achieve the above objectives, the present invention provides an oil-based foam displacement system stabilized by high-temperature resistant nanoparticles, comprising 0.5wt%-1.5wt% nanoparticles, 0.5wt%-2wt% nonionic surfactant Span20, 0.1wt%-1.0wt% nonionic surfactant JQ-1, and the balance being an oil solvent. The nonionic surfactant JQ-1 is polyoxyethylene stearate with the molecular formula C. 18 H 37 (OCH2CH2)8OH; The nanoparticles have a particle size of ≤30nm and a water contact angle of 70-150°.

[0007] The oil-based foam flooding system based on high-temperature resistant nanoparticles has a foaming volume of 170mL-230mL, a foam separation half-life of 15min-22min, and a foam half-life of 9d-15d under the conditions of 1MPa and 100℃.

[0008] This invention stabilizes foam by introducing nanoparticles, weakening the ability of gas to pass through the foam liquid film, and improving the viscoelasticity of the system through the contact between the nanoparticles and the foam.

[0009] Preferably, the water contact angle of the nanoparticles is 122°.

[0010] Preferably, the oil solvent is at least one of crude oil, white oil, and diesel oil, and more preferably diesel oil.

[0011] Preferably, the nanoparticles are at least one of fumed silica, nano aluminum oxide, and nano iron oxide.

[0012] This invention provides a method for preparing the oil-based foam flooding system stabilized by high-temperature resistant nanoparticles, comprising the following steps: Add the oil solvent to the stirring cup and introduce CO2 or N2 to ensure that the stirring cup is filled with CO2 or N2. Then add nanoparticles and nonionic surfactant Span20. Stir at 30-50℃ for 30-45 min. Then add nonionic surfactant JQ-1 and stir for 30-45 min to obtain the nanoparticle-stabilized oil-based foam displacement system.

[0013] This invention provides an application of the above-mentioned oil-based foam flooding system based on high-temperature resistant nanoparticles in oil displacement. When the reservoir temperature is less than 50°C, the amount of nanoparticles used is 0.5-1.0 wt%; when the reservoir temperature is 50°C-100°C, the amount of nanoparticles used is 1.0-1.2 wt%; and when the reservoir temperature is greater than 100°C, the amount of nanoparticles used is 1.2-1.5 wt%.

[0014] Compared with the prior art, the advantages and positive effects of the present invention are as follows: (1) The present invention creatively uses two nonionic surfactants, Span20 and JQ-1, to increase the amount of surfactant adsorbed on the gas-liquid surface, thereby having better surface activity and forming a stable oil-based foam structure.

[0015] (2) The present invention creatively adds nanoparticles with a specific water contact angle range to the oil-based foam system. The nanoparticles adsorb onto the foam surface with high adsorption energy, which improves the mechanical strength of the foam and the viscosity of the base liquid, thereby inhibiting the rupture of the liquid film, slowing down the diffusion rate of the gas and the aggregation rate of the foam, achieving a good synergistic effect, and improving the stability and temperature resistance of the foam system.

[0016] (3) The oil-based foam flooding system based on high temperature resistant nanoparticles provided by the present invention has a simple production process, readily available raw materials that do not contain toxic substances, and is harmless to the environment and personnel from production to use, meeting the requirements of green environmental protection.

[0017] (4) The oil-based foam flooding system based on high temperature resistant nanoparticles provided by the present invention has a foam half-life of 15min-22min and a foam half-life of 9d-15d under the conditions of 1MPa and 100℃, which has excellent stability and high temperature resistance. At the same time, it has good compatibility with diesel, kerosene and crude oil in the field, does not produce precipitation and will not cause formation blockage.

[0018] (5) The oil-based foam flooding system based on high-temperature resistant nanoparticles provided by the present invention has good applicability in oil reservoirs at different temperatures and has a good oil washing effect. After the oil-based foam breaks, the flooding system can still generate stable foam after encountering crude oil in the formation, continue to expand the swept volume, and improve the oil displacement effect. Attached Figure Description

[0019] Figure 1 The effect of particle concentration on the half-life of foam exudate at different temperatures; Figure 2 The foaming volume of the oil-based foam displacement system solution stabilized by high-temperature resistant nanoparticles as a function of surfactant concentration is shown in Experiment Example 4 when the nanoparticle concentration is 1 wt%. Figure 3 The change in the liquid fraction half-life of the oil-based foam displacement system solution stabilized by high-temperature resistant nanoparticles with surfactant concentration when the nanoparticle concentration is 1 wt% in Experiment Example 4. Figure 4 This is a graph showing the foam performance of the oil-based foam displacement system solution stabilized by high-temperature resistant nanoparticles when the nanoparticle concentration is 1 wt% in Experiment Example 4. Figure 5 This is a schematic diagram of the foam volume in the initial state of the oil-based foam displacement system stabilized by high-temperature resistant nanoparticles in Example 1. Figure 6 This is a schematic diagram of the foam volume after 1 hour in the oil-based foam displacement system stabilized by high-temperature resistant nanoparticles in Example 1. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other instances that are improved or modified by those skilled in the art are within the scope of protection of the present invention. It should be understood that the embodiments of the present invention are only used to illustrate the technical effects of the present invention, and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the methods used in the embodiments are conventional methods.

[0021] The nonionic surfactant Span20 was purchased from China National Pharmaceutical Group Chemical Reagent Co., Ltd. It is an amber-colored oily solid at room temperature, soluble in isopropanol, xylene and mineral oil, and has excellent foaming properties.

[0022] The polyether-based nonionic surfactant JQ-1 (polyoxyethylene stearate C) 34 H 70 O9), purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., is solid at room temperature, soluble in isopropanol, xylene and mineral oil, and has excellent foaming properties.

[0023] The fumed silica nanoparticles are selected from the H17-H30 series, which are commercially available from Wacker Chemie China Ltd., with a particle size ≤30nm and a contact angle of 70-150°. The nanoparticles have the characteristics of good injectability and strong foam stabilization ability.

[0024] This invention provides an oil-based foam flooding system based on high-temperature resistant nanoparticles, wherein the concentration of nanoparticles is 0.5wt%-1.5wt%, the concentration of nonionic surfactant Span20 is 0.5wt%-2wt%, and the concentration of nonionic surfactant JQ-1 is 0.1wt%-1.0wt%.

[0025] Experimental Example 1: A nanoparticle-stabilized oil-based foam flooding system comprises 1.0 wt% nanoparticles, 1.2 wt% Span20 and 0.2 wt% JQ-1, with the balance being an oil solvent, wherein diesel oil is selected as the oil solvent and fumed silica is selected as the nanoparticles.

[0026] The experimental steps are as follows: Multiple 100mL portions of diesel fuel were poured into a high-speed stirring cup, and CO2 gas was bubbled through the cup for 1 minute to ensure it was filled with CO2. After bubbling, the cup was sealed to minimize the influence of air on the experiment. Nanoparticles with different water contact angles were added to the high-speed stirring cup at a concentration of 1.0wt%, followed by 1.2wt% of Span20. After stirring at 50℃ for 45 minutes, 0.2wt% of JQ-1 was added, and the mixture was stirred for another 45 minutes to prepare foaming agent solutions.

[0027] The test methods for foam volume, foam separation half-life, and foam half-life are as follows: The oil displacement system is transferred to a high-speed stirring cup. Under sealed conditions, the stirring speed is set to 8000 r / min for 3 min. After the stirring stops, the foam is quickly poured into a high-temperature pressure-resistant tube, and the foam volume is recorded as the foam volume. The pressure is maintained at 1 MPa, and the system is transferred to a 100℃ environment. Timing is started simultaneously. The time when half of the liquid has separated from the foam system is recorded as the foam separation half-life. The time when the foam height decreases by half is recorded as the foam half-life. The experimental results are shown in Table 1.

[0028] Table 1 Relationship between water contact angle and liquid separation half-life

[0029] Experiments showed that when using fumed silica with a water contact angle of 122° as nanoparticles, the oil-based foam flooding system based on high-temperature resistant nanoparticles produced a foam volume of 230 mL, a foam half-life of 22 min, and a foam half-life of 15 days. The oil-soluble surfactant system used in the experimental group consisted of polyether surfactants and Span20. These surfactants are inexpensive, environmentally friendly, and meet the practical application needs of oilfields. Crude oil itself has low interfacial tension, which is difficult to further reduce using surfactants. The two surfactants work synergistically to reduce interfacial tension. Simultaneously, the nanoparticles distributed at the gas-liquid interface not only hinder liquid film encounters and inhibit gas diffusion but also increase liquid flow resistance and slow down drainage, thus increasing foam stability.

[0030] When the contact angle of the particles is in the range of 70°-155°, they can be well dispersed in diesel fuel. Beyond this range, they are difficult to disperse and will not be considered in subsequent experiments.

[0031] Two surfactants were prepared in a certain ratio, and nanoparticles were used as stabilizers. The resulting foam had good stability. Therefore, the oil-based foam flooding system based on high-temperature resistant nanoparticles provided by this invention is not only simple to prepare and environmentally friendly, but also produces high-quality oil-based foam.

[0032] Experimental Example 2: A nanoparticle-stabilized oil-based foam flooding system comprises 0.5wt%, 0.7wt%, 0.9wt%, 1.2wt%, or 1.5wt% nanoparticles, 1.2wt% Span20, and 0.2wt% JQ-1, with the balance being an oil solvent. In this experimental example, the nanoparticles are fumed silica with a particle size range of ≤30nm and a water contact angle of 122°. The oil solvent is diesel oil.

[0033] The experimental steps are as follows: 100 mL of the prepared high-temperature resistant nanoparticle-based heated oil-based foam displacement system was transferred to a high-temperature, high-pressure stirrer. The pressure was maintained at 1 MPa, and the temperature was maintained within a 10°C range of 50°C-120°C. The stirring speed was 8000 r / min for 3 min. After stirring stopped, the foam volume was recorded as the foaming volume. Timing was started simultaneously, and the time when half of the foam system had separated was recorded as the separation half-life. The time when the foam height decreased by half was defined as the foam half-life. The temperature was changed to continue measuring the changes in foam properties. The experimental results are as follows: Figure 1 As shown.

[0034] When the ground temperature is 50℃ and the amount of nanoparticles used is 0.5 wt%-1.0 wt%, the foam can maintain good stability and performance, while effectively reducing the amount of nanoparticles used and lowering costs. When the ground temperature is 50℃-100℃, and the amount of nanoparticles is 1.0wt%-1.2wt%, the amount of nanoparticles can be reasonably controlled while ensuring that the foam performance meets the requirements of use, thereby reducing costs. When the ground temperature is above 100℃, the amount of nanoparticles used is 1.2wt%-1.5wt%. Under these conditions, the foam can still maintain good performance. At the same time, avoiding excessive addition of nanoparticles helps to reduce the overall cost.

[0035] Experimental Example 3: Injection Method of Nanoparticle-Stabilized Oil-Based Foam Displacement System Experimental Group 1: During the experiment, the confining pressure of the model was set to 8 MPa, and the back pressure was set to 7.5 MPa. The saturated crude oil in the microscopic model was injected at a rate of 0.20 mL / min. -1 Nitrogen-driven experiments were performed, and the experiment was stopped after injecting 2.0 PV. Experimental Group 2: During the experiment, the confining pressure of the model was set to 8 MPa and the back pressure to 7.5 MPa. The micro-model was saturated with crude oil, and then the oil displacement system was injected into the formation in the form of a gas-liquid sluice, followed by a flow rate of 0.20 mL / min. -1The experiment was stopped after nitrogen flooding and injection of 2.0 PV. The gas-liquid slug was used to displace the oil displacement system carried by nitrogen. The oil displacement system, which was diluted with a small amount of diesel, was injected into the formation. The volume ratio of the oil displacement system to nitrogen was 5:1, and the slug volume was 0.2 PV.

[0036] Experimental Group 3: During the experiment, the confining pressure of the model was set to 8 MPa, and the back pressure was set to 7.5 MPa. The micro-model was saturated with crude oil. Subsequently, the oil displacement system and gas were simultaneously injected into a foam generator to obtain oil-based foam. After stabilization, the oil-based foam was injected into the formation. The injection rate was 0.20 mL / min. -1 The experiment was stopped after injecting 2.0 PV of oil-based foam.

[0037] The oil displacement systems in Experimental Groups 2 and 3 consist of diesel oil, 1.2 wt% Span20, 0.2 wt% JQ-1, and 0.5 wt% nanoparticles (particle size ≤ 30 nm, water contact angle 122°).

[0038] In Experiment 1, conventional gas drive caused gas channeling at 0.3 PV. After the gas channeling channel was formed, the recovery rate decreased rapidly. Continuing to increase the gas injection volume did not change the recovery rate, and the final recovery rate was only 45.37%.

[0039] In Experiment 2, the oil displacement system was injected into the model in the form of a slug. After the oil displacement system came into contact with the formation crude oil, gas was injected into the model. The gas and the crude oil containing surfactants came into contact with each other and produced a certain amount of foam. As the foam accumulated in the channels, the affected area could be expanded and the recovery rate could be improved. The final recovery rate was 69.21%.

[0040] In Experiment 3, after the injection of oil-based foam, the foam migrated within the channels, displacing the crude oil. Upon rupture of the foam within the channels, the surfactant came into contact with the surrounding crude oil. When gas came into contact with crude oil containing oil-soluble foaming agents, oil-based foam rapidly formed under shear force, blocking the gas channel and causing the liquid flow to redirect, increasing the sweep efficiency and improving the recovery rate to 72.95%. This indicates that oil-based foam injection has a good effect on oil displacement.

[0041] Experiment Example 4: A nanoparticle-stabilized oil-based foam flooding system comprises 1 wt% nanoparticles, 0.4-1.8 wt% Span20 and 0-0.25 wt% JQ-1, with the balance being an oil solvent. In this experimental example, the nanoparticles are fumed silica with a particle size range of ≤30 nm and a water contact angle of 122°. The oil solvent is diesel oil.

[0042] The preparation method and the test method for the liquid precipitation half-life of the foam-driven oil displacement system are the same as those in Experimental Example 1, and the results are as follows: Figure 2 , 3 As shown in Figure 4, the foam volume and stability significantly increase with increasing Span20 and JQ-1 mass fractions, indicating a synergistic effect between the two in promoting the formation and stabilization of oil-based foams. In the lower Span20 and JQ-1 mass fraction range, the generated foam volume is small and the half-life is short, indicating insufficient interfacial activity to effectively support the foam structure. With increasing Span20 content, interfacial activity enhances, and the foam volume increases significantly. Simultaneously, with the appropriate addition of JQ-1, the foam film strength improves, the liquid-liquid half-life is significantly prolonged, and foam stability is enhanced. Under the conditions of 0.7–1.8 wt% Span20 and 0.1–0.25 wt% JQ-1, the liquid-liquid half-life can reach a medium-to-high level of 20–50 min, indicating that the system possesses better oil displacement foam performance under these conditions. The above trends indicate that there is a good synergistic mechanism between nanoparticles and surfactant systems. When the contact angle of nanoparticles is 122°, it is beneficial for them to be adsorbed at the oil-water interface and enhance the stability of the foam film, thereby inhibiting liquid discharge and foam rupture, and achieving a dual improvement in foam volume and half-life.

[0043] Example 1 A high-temperature resistant nanoparticle-stabilized oil-based foam flooding system comprises 1.0 wt% nanoparticles, 1.2 wt% Span20 and 0.2 wt% JQ-1, with the balance being an oil solvent, wherein diesel oil is selected as the oil solvent and fumed silica is selected as the nanoparticles.

[0044] Multiple 100mL portions of diesel fuel were poured into a high-speed stirring cup, and CO2 gas was bubbled through the cup for 1 minute to ensure it was filled with CO2. After bubbling, the cup was sealed to minimize the influence of air on the experiment. Nanoparticles with different water contact angles were added to the high-speed stirring cup at a concentration of 1.0wt%, followed by the addition of 1.2wt% Span20. After stirring at 50℃ for 45 minutes, 0.2wt% JQ-1 was added, and the mixture was stirred for another 45 minutes to obtain an oil-based foam flooding system stabilized by high-temperature resistant nanoparticles.

[0045] The foam volumes in the initial state and after 1 hour are respectively as follows: Figure 5 , 6 As shown. Comparative Example 1 An oil-based foam displacement system differs from Example 1 in that an equal amount of Span 80 is used instead of Span 20, while all other conditions remain the same. Experimental results show that the foaming effect and liquid discharge half-life are inferior to those of Span 20. This is because the oleic acid chain in the Span 80 molecule has a long carbon chain and an unsaturated double bond structure, resulting in a lower degree of molecular order at the gas-liquid interface, leading to insufficient interfacial film strength and thus accelerating the liquid film drainage process. Secondly, the significant polarity difference between Span 80 and the polyether surfactant JQ-1 results in a weak synergistic effect at the interface, failing to form a dense interfacial film, thus causing the foaming capacity and liquid discharge half-life to be inferior to those of Span 20.

[0046] Comparative Example 2 An oil-based foam flooding system differs from Example 1 in that an equal amount of OP-10 is used instead of JQ-1, while all other conditions remain the same. Experimental results show that the foaming effect and liquid separation half-life are inferior to those of JQ-1. This is because OP-10 has extremely low solubility in diesel oil, and most of it precipitates out and cannot participate in interfacial adsorption. JQ-1 contains siloxane segments, which can reduce the gas-oil interfacial tension to below 5 mN / m, while OP-10 does not have this ability. The high interfacial energy makes it difficult for the foam to stabilize. OP-10 is prone to dehydration and gelation above 50°C, losing its surface activity, resulting in inferior foaming ability and liquid separation half-life compared to JQ-1.

[0047] Comparative Example 3 An oil-based foam flooding system differs from Example 1 in that JQ-1 is added at a concentration of 1.5 wt%, while other conditions remain the same. Experimental results show that the foaming effect and liquid half-life are both inferior to the 0.2 wt% JQ-1 solution. This is because when the concentration of the foaming agent in diesel fuel exceeds the critical micelle concentration, the Marangoni effect weakens, making the foam unstable. The polyether segments of high-concentration Q-1 repel each other, resulting in disordered interfacial film arrangement and decreased mechanical strength. JQ-1 covers too much interfacial space, and the excessively high concentration thickens the liquid film but inhibits gas diffusion, increases foam brittleness, hinders nanoparticle adsorption, and loses its foam stabilizing effect.

[0048] Comparative Example 4 An oil-based foam flooding system differs from Example 1 in that it does not use Span20, while all other conditions are the same. Experimental results show that the foaming effect and the liquid separation half-life are not as good as those with Span20. Span20 is the core emulsifier responsible for constructing the oil-water microemulsion environment. The short-chain structure of Span20 rapidly coats the bubble core, and its absence leads to a doubling of the bubble merging rate. Without Span20, JQ-1 cannot effectively adsorb at the interface in the heterogeneous system.

[0049] Comparative Example 5 An oil-based foam flooding system differs from Example 1 in that it does not use JQ-1, while all other conditions are the same. Experimental results show that the foaming effect and the liquid separation half-life are not as good as those with JQ-1. JQ-1 can effectively reduce interfacial tension, and high interfacial energy leads to accelerated bubble coalescence. The polyether structure of JQ-1 remains flexible at high temperatures, which is significantly better than using Span20 alone.

[0050] Comparative Example 6 An oil-based foam-driven oil displacement system differs from Example 2 in that CO2 was not introduced before adding fumed silica nanoparticles, while other conditions remained the same. Experimental results showed that the foaming effect was not as good as when CO2 was introduced. When the foam was exposed to air, the moisture on its liquid film surface continuously evaporated. This caused localized thinning of the liquid film, significantly reducing the foaming effect. The oil displacement systems provided in Example 1 and Comparative Example 6 were foamed under the foaming conditions of Example 2, maintained at 50°C and 1 MPa, and the foam volume and liquid half-life were measured.

[0051] Table 2 Statistical Results

Claims

1. A high temperature resistant nanoparticle stabilized oil-based foam flooding system, characterized in that, The nanoparticles are 0.5wt%-1.5wt%, the non-ionic surfactant Span20 is 0.5wt%-2wt%, the non-ionic surfactant JQ-1 is 0.1wt%-1.0wt%, and the rest is the oil solvent; The nonionic surfactant JQ-1 is a polyoxyethylene stearate with the molecular formula C 18 H 37 (OCH2CH2)8OH; The nanoparticles have a particle size of ≤30nm and a water contact angle of 70-150°. The oil-based foam flooding system based on the high-temperature-resistant nanoparticles has a foaming volume of 170mL-230mL, a foam liquid drainage half-life of 15min-22min, and a foam half-life of 9d-15d under the conditions of 1MPa and 100℃.

2. The oil-based foam flooding system based on the high-temperature-resistant nanoparticles according to claim 1, wherein the nanoparticles have a water contact angle of 122°.

3. The oil-based foam flooding system based on the high-temperature-resistant nanoparticles according to claim 1, wherein the oil solvent is at least one of crude oil, white oil, and diesel oil.

4. The oil-based foam flooding system based on the high-temperature-resistant nanoparticles according to claim 1, wherein the nanoparticles are at least one of fumed silica, nano-aluminum oxide, and nano-magnetite. The method comprises the following steps: The oil solvent is added into a stirring cup, and CO2 or N2 is introduced to ensure that the stirring cup is filled with CO2 or N2, then the nanoparticles and the non-ionic surfactant Span20 are added, and after stirring at 30-50℃ for 30-45min, the non-ionic surfactant JQ-1 is added, and after stirring for 30-45min, the oil-based foam flooding system based on the nanoparticles is obtained.

6. The oil-based foam flooding system based on the high-temperature-resistant nanoparticles according to any one of claims 1-4 or prepared by the method of claim 5, and application of the oil-based foam flooding system in oil displacement.

5. A method of preparing a high temperature resistant nanoparticle stabilized oil-based foam flooding system according to any one of claims 1 to 4, characterized in that, 7. The application according to claim 6, wherein when the reservoir temperature is less than 50℃, the amount of the nanoparticles is 0.5-1.0wt%; when the reservoir temperature is 50℃-100℃, the amount of the nanoparticles is 1.0-1.2wt%; and when the reservoir temperature is greater than 100℃, the amount of the nanoparticles is 1.2-1.5wt%. ​ ​ ​ ​

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