A dual ionic nano-surfactant, and a preparation method and application thereof

Abstract

The application relates to the technical field of oilfield exploitation surfactants, in particular to a dual-ion nano surfactant and a preparation method and application thereof. The dual-ion nano surfactant is of a core-shell structure, the core is nano silicon dioxide, and the shell is an amphiphilic block copolymer. The amphiphilic block copolymer comprises a polystyrene hydrophobic chain segment containing a benzene ring structure and a polyacrylic acid hydrophilic chain segment. The chain length L1 of the polystyrene hydrophobic chain segment and the chain length L2 of the polyacrylic acid hydrophilic chain segment satisfy the relationship L1:L2=(1-100):(0.5-50). The dual-ion nano surfactant is designed as a core-shell structure, the core is nano silicon dioxide, and the shell is a polystyrene hydrophobic chain segment and a polyacrylic acid hydrophilic chain segment, so that the emulsifying effect of the dual-ion nano surfactant on heavy oil is improved, the recovery rate of the heavy oil can be increased to more than 10%, and the long-term stability time of the post-flooding liquid is more than 100 days.

Description

Technical Field

[0001] This application relates to the field of surfactant technology in oilfield exploitation, and in particular to a biionic nanosurfactant, its preparation method, and its application. Background Technology

[0002] Due to the high viscosity and low fluidity of heavy oil, traditional heavy oil reservoir recovery methods, such as steam injection and steam drive, often suffer from high extraction costs, high energy consumption, and high carbon emissions. Given the urgent need for the petroleum industry to accelerate its green and low-carbon transformation and upgrading, it is necessary to vigorously develop new technologies for drag reduction and viscosity reduction in heavy oil cold recovery to improve heavy oil recovery rates while achieving clean and efficient reservoir development throughout the entire process and chain. Currently, chemical displacement, as an emerging EOR (Enhanced Oil Recovery) technology for improving heavy oil recovery rates, can meet the requirements of improving heavy oil recovery rates while achieving clean and efficient reservoir development throughout the entire process and chain. The principle of chemical displacement is to inject surfactants and other chemical flooding agents into the reservoir, which can significantly reduce oil-water interfacial tension, improve reservoir wettability, and enhance crude oil fluidity, thereby improving the recovery efficiency of heavy oil reservoirs. However, existing surfactants used in displacement, such as alkyl sulfonates and petroleum sulfonates, still have shortcomings in addressing the challenges of heavy oil cold recovery, including narrow applicability, simple molecular structure, poor temperature and salt resistance, and weak penetration. This is mainly because the surfactants used in chemical flooding have poor compatibility with the heavy oil matrix, making it difficult for them to deeply adsorb onto the surface of polar components such as asphaltenes in the heavy oil, thus limiting their viscosity-reducing and emulsifying effects. Furthermore, the high temperature and high salinity conditions within the reservoir easily induce aggregation and precipitation between surfactant molecules, behaviors detrimental to viscosity reduction and emulsification, thereby significantly weakening the reservoir displacement performance of chemical flooding. Therefore, developing novel displacement surfactants with novel molecular structures, strong affinity for the heavy oil matrix, resistance to temperature and salt, adsorption resistance, and outstanding penetration capabilities is of paramount importance.

[0003] Due to their unique size and surface-interface effects, nanostructured materials not only possess advantages such as large specific surface area and strong adsorption capacity, but also can be surface-modified with various functional groups, endowing them with excellent amphiphilic and responsive properties. Therefore, nanostructured materials are widely used in the field of oil displacement. At present, the representative technology used in the field of oil displacement is to modify the surface of nano-silica with organic properties to construct novel nano-displacement agents. Examples of these surface organic modifications include: (1) grafting hydrophilic and lipophilic silane coupling agents onto the surface of nano-silica to obtain amphiphilic nano-displacement agents with a particle size of less than 100 nm; (2) using temperature-responsive monomers such as NIPAm to graft and modify nano-silica to prepare intelligent nano-displacement agents with both viscosity reduction and deep displacement functions. However, the emulsification and viscosity reduction capabilities of nanostructured materials at present are limited. Furthermore, small-molecule surfactants containing special functional groups have attracted considerable attention due to their unique chemical structures and functionalities. Currently, amino-containing small-molecule surfactants with molecular weights less than 1000 have been proven to possess excellent penetration and migration capabilities, effectively improving the rheological properties of heavy oil. Additionally, these surfactants containing polar adsorption groups can selectively emulsify polar components such as asphaltenes and gums in heavy oil, thereby enhancing the viscosity-reducing and emulsifying effects of small-molecule surfactants containing special functional groups. However, current small-molecule surfactants containing special functional groups target only a single functional group, resulting in relatively low emulsifying and viscosity-reducing capabilities. Summary of the Invention

[0004] This application provides a biionic nanosurfactant, its preparation method, and its application to solve the following technical problem: how to improve the emulsifying and viscosity-reducing ability of surfactants used in oil reservoirs.

[0005] In a first aspect, this application provides a biionic nanosurfactant, wherein the biionic nanosurfactant has a core-shell structure, with the core being nano-silica and the shell being an amphiphilic block copolymer; wherein the amphiphilic block copolymer includes a polystyrene hydrophobic segment containing a benzene ring structure and a polyacrylic acid hydrophilic segment; the chain length L1 of the polystyrene hydrophobic segment containing the benzene ring structure and the chain length L2 of the polyacrylic acid hydrophilic segment satisfy the relationship: L1:L2=(1~100):(0.5~50).

[0006] Optionally, the degree of polymerization n1 of the polystyrene hydrophobic segment containing the benzene ring structure and the degree of polymerization n2 of the polyacrylic acid hydrophilic segment satisfy the relationship: n1:n2=(1:10)~(10:1).

[0007] Optionally, the particle size of the nano-silica is 5nm to 100nm.

[0008] Optionally, the hydrophilic-lipophilic balance value of the biionic nanosurfactant is 5 to 18.

[0009] Secondly, this application provides a method for preparing the biionic nanosurfactant described in the first aspect, the method comprising:

[0010] Nano-silica and 3-aminopropyltriethoxysilane are mixed to modify the surface of the nano-silica with the 3-aminopropyltriethoxysilane, resulting in surface-modified nano-silica.

[0011] Styrene, pentamethyldiethylenetriamine and the surface-modified nano-silica were mixed, and the mixed solution was then subjected to cyclic freezing, vacuuming and thawing to obtain a mixture.

[0012] 2-bromoisobutyryl bromide, tert-butyl acrylate, copper bromide and the mixture were subjected to in-situ polymerization to obtain block copolymer modified nano-silica containing benzene ring structure p-tert-butylbenzoic acid and polyacrylic acid.

[0013] The block copolymer-modified nano-silica was purified, and then the purified block copolymer-modified nano-silica was hydrolyzed to remove the protecting groups of the block copolymer-modified nano-silica, thereby obtaining a biionic nano-surfactant.

[0014] Optionally, the weight m1 of the nano-silica and the volume V1 of the 3-aminopropyltriethoxysilane satisfy the relationship: m1:V1=(1~20):(1~15), where if the unit of m1 is g, then the unit of V1 is mL.

[0015] The volume V2 of the styrene, the weight m2 of the pentamethyldiethylenetriamine, and the weight m3 of the surface-modified nano silica satisfy the following relationship: V2:m2:m3=(10~100):(0.1~2.0):(1~5), where if the units of m2 and m3 are g, then the unit of V2 is mL;

[0016] The volume V3 of the 2-bromoisobutyryl bromide, the volume V4 of the tert-butyl acrylate, the weight m4 of the copper bromide, and the weight m5 of the mixture satisfy the following relationship: V3:V4:m4:m5=(1~10):(10~100):(0.05~1.00):(1~10).

[0017] Optionally, the temperature of the in-situ polymerization reaction is 80℃~110℃, and the time of the in-situ polymerization reaction is 2h~24h.

[0018] Optionally, the in-situ polymerization reaction of 2-bromoisobutyryl bromide, tert-butyl acrylate, copper bromide, and the mixture to obtain a block copolymer-modified nano-silica containing a benzene ring structure and polyacrylic acid includes the following steps:

[0019] The copper bromide and the mixture are mixed to allow the mixture to undergo a preliminary in-situ polymerization reaction, yielding a primary mixed reactant.

[0020] 2-Bromoisobutyryl bromide, tert-butyl acrylate, and the primary mixed reactant are mixed to allow the primary mixed reactant to undergo an in-situ polymerization reaction, resulting in a block copolymer modified nano-silica containing a benzene ring structure of p-tert-butylbenzoic acid and polyacrylic acid.

[0021] Thirdly, this application provides a heavy oil cold production displacement agent, which includes the biionic nanosurfactant described in the first aspect.

[0022] Optionally, the weight m6 of the biionic nanosurfactant and the total weight m7 of the heavy oil cold production displacement agent satisfy the relationship: m6:m7=(0.05~0.5):100, the operating temperature of the heavy oil cold production displacement agent is 40℃~120℃, and the operating pressure of the heavy oil cold production displacement agent is 5MPa~30MPa.

[0023] The technical solutions provided in this application have the following advantages compared with the prior art:

[0024] This application provides a biionic nanosurfactant with a core-shell structure. The core uses nano-silica, and the nanoparticles increase the specific surface area of ​​the biionic nanosurfactant, enabling it to provide more adsorption sites at the oil-water interface and thus enhancing its emulsifying effect on heavy oil. The outer shell consists of hydrophobic polystyrene segments containing benzene rings and hydrophilic polyacrylic acid segments. These hydrophobic groups facilitate the interaction between the biionic nanosurfactant and polar components such as asphaltene in the oil reservoir. The close bonding of these hydrophilic groups facilitates the formation of stable water-in-oil emulsions between the biionic nanosurfactants and the reservoir, thereby promoting the smooth emulsification and viscosity reduction of the biionic nanosurfactants. In addition, the chain length L1 of the hydrophobic polystyrene segment containing the benzene ring structure and the chain length L2 of the hydrophilic polyacrylic acid segment satisfy the relationship: L1:L2=(1~100):(0.5~50). By finely adjusting the hydrophilic-lipophilic balance of the biionic nanosurfactants by adjusting the chain lengths of the hydrophobic and hydrophilic segments of different lengths, the viscosity reduction and emulsification ability of the biionic nanosurfactants can be improved. Attached Figure Description

[0025] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 Scanning electron microscopy (SEM) image of a biionic nanosurfactant provided in Example 1 of this application;

[0028] Figure 2 Scanning electron microscopy (SEM) image of a biionic nanosurfactant provided in Example 2 of this application;

[0029] Figure 3 This is a schematic flowchart of a method for preparing a biionic nanosurfactant provided in an embodiment of this application;

[0030] Figure 4 This is a detailed flowchart illustrating a method for preparing biionic nanosurfactants, provided in an embodiment of this application. Detailed Implementation

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

[0032] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range; for example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range such as 1, 2, 3, 4, 5, and 6, regardless of the range; in addition, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0033] In this document, terms including "comprising" and the like mean "including but not limited to". Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application are commercially available or can be prepared by existing methods.

[0034] Figure 1 The scanning electron microscope image of a biionic nanosurfactant provided in Embodiment 1 of this application is shown as an example.

[0035] Figure 2 The scanning electron microscope image of a biionic nanosurfactant provided in Embodiment 2 of this application is shown as an example.

[0036] like Figure 1 and Figure 2 As shown, this application provides a biionic nanosurfactant, which has a core-shell structure, with nano-silica as the core and an amphiphilic block copolymer as the shell. The amphiphilic block copolymer includes a polystyrene hydrophobic segment containing a benzene ring and a polyacrylic acid hydrophilic segment. The chain length L1 of the polystyrene hydrophobic segment containing the benzene ring and the chain length L2 of the polyacrylic acid hydrophilic segment satisfy the relationship: L1:L2=(1~100):(0.5~50).

[0037] The chain length L1 of the hydrophobic polystyrene segment containing the benzene ring structure and the chain length L2 of the hydrophilic polyacrylic acid segment satisfy the following relationship: L1:L2 = 1:0.5, 1:1.0, 1:3.0, 1:5.0, 1:10, 1:20, 1:30, 1:40, 1:50, 25:0.5, 25:1.0, 25:3.0, 25:5.0, 25:250, 25:20, 25:30 25:40, 25:50, 50:0.5, 50:1.0, 50:3.0, 50:5.0, 50:500, 50:20, 50:30, 50:40, 50:50, 100:0.5, 100:1.0, 100:3.0, 100:5.0, 100:1000, 100:20, 100:30, 100:40 or 100:50.

[0038] In some optional real-time modes, the degree of polymerization n1 of the polystyrene hydrophobic segment containing the benzene ring structure and the degree of polymerization n2 of the polyacrylic acid hydrophilic segment satisfy the relationship: n1:n2=(1:10)~(10:1);

[0039] In these embodiments, the degree of polymerization n1 of the polystyrene hydrophobic segment containing the benzene ring structure and the degree of polymerization n2 of the polyacrylic acid hydrophilic segment can satisfy the relationship: n1:n2=(1:10)~(10:1). With fine adjustment of the chain lengths of hydrophobic and hydrophilic segments of different lengths, the hydrophilic-lipophilic balance of the biionic nanosurfactant can be further finely adjusted by controlling the weight ratio of the hydrophobic and hydrophilic segments, thereby further improving the viscosity-reducing and emulsifying ability of the biionic nanosurfactant.

[0040] The degree of polymerization n1 of the hydrophobic polystyrene segment containing a benzene ring and the degree of polymerization n2 of the hydrophilic polyacrylic acid segment can satisfy the following relationship: n1:n2 = 1:10, 2:9, 3:8, 4:7, 5:6, 6:5, 7:2, 8:3, 9:2 or 10:1.

[0041] In some optional real-time methods, the particle size of the nano-silica is 5 nm to 100 nm;

[0042] In these embodiments, the particle size of nano-silica can be 5nm to 100nm, which can make the nano-silica have a sufficiently large specific surface area. A sufficiently large specific surface area can provide more adsorption sites for biionic nano-surfactants at the oil-water interface, thereby improving the emulsification effect of biionic nano-surfactants with heavy oil reservoirs.

[0043] The particle size of this nano-silica can be 5nm, 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm or 100nm.

[0044] In some optional embodiments, the hydrophilic-lipophilic balance value of the biionic nanosurfactant is 5 to 18;

[0045] In these methods, the hydrophilic-lipophilic balance value of the biionic nanosurfactant can be 5 to 18, which indicates that the biionic nanosurfactant has a wide range of adjustable hydrophilic-lipophilic balance values, and can be used for displacement of heavy oil reservoirs in a wide range.

[0046] The hydrophilic-lipophilic balance value of this biionic nanosurfactant can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 or 18.

[0047] Figure 3 An exemplary schematic diagram of a method for preparing a biionic nanosurfactant provided in an embodiment of this application is shown.

[0048] Based on a general inventive concept, such as Figure 3As shown in the embodiments of this application, a method for preparing the biionic nanosurfactant is provided, the method comprising:

[0049] S1. Mix nano-silica and 3-aminopropyltriethoxysilane to modify the surface of the nano-silica with the 3-aminopropyltriethoxysilane to obtain surface-modified nano-silica;

[0050] S2. Styrene, pentamethyldiethylenetriamine and the surface-modified nano-silica are mixed, and then the mixed solution is subjected to cyclic freezing, vacuuming and thawing to obtain a mixture;

[0051] S3. 2-Bromoisobutyryl bromide, tert-butyl acrylate, copper bromide and the mixture are subjected to an in-situ polymerization reaction to obtain a block copolymer modified nano-silica containing a benzene ring structure and polyacrylic acid.

[0052] S4. The block copolymer-modified nano-silica is purified, and then the purified block copolymer-modified nano-silica is hydrolyzed to remove the protecting groups of the block copolymer-modified nano-silica, thereby obtaining a biionic nano-surfactant.

[0053] This method is for the preparation of the above-mentioned biionic nanosurfactant. The specific composition of the biionic nanosurfactant can be referred to the above embodiments. Since this method adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here.

[0054] In some optional embodiments, the weight m1 of the nano-silica and the volume V1 of the 3-aminopropyltriethoxysilane satisfy the relationship: m1:V1=(1~20):(1~15), where if the unit of m1 is g, then the unit of V1 is mL;

[0055] The volume V2 of the styrene, the weight m2 of the pentamethyldiethylenetriamine, and the weight m3 of the surface-modified nano silica satisfy the following relationship: V2:m2:m3=(10~100):(0.1~2.0):(1~5), where if the units of m2 and m3 are g, then the unit of V2 is mL;

[0056] The volume V3 of the 2-bromoisobutyryl bromide, the volume V4 of the tert-butyl acrylate, the weight m4 of the copper bromide, and the weight m5 of the mixture satisfy the following relationship: V3:V4:m4:m5=(1~10):(10~100):(0.05~1.00):(1~10);

[0057] In these embodiments, the weight m1 of nano-silica and the volume V1 of 3-aminopropyltriethoxysilane satisfy the relationship: m1:V1=(1~5):(1~10). Sufficient 3-aminopropyltriethoxysilane can effectively modify the surface of nano-silica to ultimately obtain sufficient surface-modified nano-silica. Additionally, the volume V2 of styrene, the weight m2 of pentamethyldiethylenetriamine, and the weight m3 of surface-modified nano-silica satisfy the relationship: V2:m2:m3=(10~100):(0.1~2.0):(1~5). Styrene and pentamethyldiethylenetriamine react with the surface-modified nano-silica... Thorough mixing facilitates the subsequent in-situ polymerization process, ensuring sufficient amounts of benzene-ring-containing p-tert-butylbenzoic acid and polyacrylic acid co-modified block copolymer-modified nano-silica. Furthermore, the volume V3 of 2-bromoisobutyryl bromide, the volume V4 of tert-butyl acrylate, the weight m4 of copper bromide, and the weight m5 of the mixture satisfy the relationship: V3:V4:m4:m5=(1~10):(10~100):(0.05~1.00):(1~10), which promotes the thorough in-situ polymerization reaction, resulting in sufficient amounts of benzene-ring-containing p-tert-butylbenzoic acid and polyacrylic acid co-modified block copolymer-modified nano-silica.

[0058] The weight m1 of the nano-silica can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20; the volume V1 of the 3-aminopropyltriethoxysilane can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15.

[0059] The volume V2 of the styrene can be 10, 20, 30, 40, 50, 60, 70, 80, 90 or 100; the weight m2 of the pentamethyldiethylenetriamine can be 0.1, 0.2, 0.3, 0.4, 0.5, 1.0, 1.5 or 2.0; and the weight m3 of the surface-modified nano-silica can be 1, 2, 3, 4 or 5.

[0060] The volume V3 of the 2-bromoisobutyryl bromide can be 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10; the volume V4 of the tert-butyl acrylate can be 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100; the weight m4 of the copper bromide can be 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.60, 0.70, 0.80, 0.90, or 1.00; and the weight m5 of the mixture can be 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.

[0061] In some optional embodiments, the temperature of the in-situ polymerization reaction is 80°C to 110°C, and the time of the in-situ polymerization reaction is 2h to 24h.

[0062] In these embodiments, the temperature of the in-situ polymerization reaction can be 80°C to 110°C, and the time of the in-situ polymerization reaction can be 2h to 24h, which can promote the in-situ polymerization reaction to proceed fully in order to obtain sufficient amount of block copolymer modified nano-silica containing benzene ring structure p-tert-butylbenzoic acid and polyacrylic acid.

[0063] The temperature for this in-situ polymerization reaction can be 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, or 110℃.

[0064] The in-situ polymerization reaction can take 2 hours, 4 hours, 6 hours, 8 hours, 12 hours, 16 hours, 20 hours, or 24 hours.

[0065] Figure 4 A detailed flowchart illustrating a method for preparing biionic nanosurfactants provided in an embodiment of this application is shown by way of example.

[0066] In some alternative implementations, such as Figure 4 As shown, the in-situ polymerization reaction of 2-bromoisobutyryl bromide, tert-butyl acrylate, copper bromide, and the mixture to obtain a block copolymer-modified nano-silica containing a benzene ring structure and polyacrylic acid includes the following steps:

[0067] S301. Mix copper bromide and the mixture to allow the mixture to undergo a preliminary in-situ polymerization reaction, thereby obtaining a primary mixed reactant;

[0068] S302. Mix 2-bromoisobutyryl bromide, tert-butyl acrylate and the primary mixed reactant to carry out an in-situ polymerization reaction of the primary mixed reactant to obtain a block copolymer modified nano-silica containing benzene ring structure p-tert-butylbenzoic acid and polyacrylic acid.

[0069] In these embodiments, copper bromide and the mixture are first added and mixed to induce the mixture to undergo a preliminary in-situ polymerization reaction. Then, 2-bromoisobutyryl bromide, tert-butyl acrylate and the primary mixture that has undergone the preliminary in-situ polymerization reaction are further subjected to an in-situ polymerization reaction to obtain sufficient amount of block copolymer modified nano-silica containing benzene ring structure p-tert-butylbenzoic acid and polyacrylic acid.

[0070] Based on a general inventive concept, embodiments of this application provide a heavy oil cold production displacement agent, which includes the biionic nanosurfactant.

[0071] The heavy oil cold production displacement agent is based on the above-mentioned biionic nano-surfactant. The specific composition of the biionic nano-surfactant can be referred to the above embodiments. Since the heavy oil cold production displacement agent adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.

[0072] In some optional embodiments, the weight m6 of the biionic nanosurfactant and the total weight m7 of the heavy oil cold production displacement agent satisfy the relationship: m6:m7=(0.05~0.5):100, the operating temperature of the heavy oil cold production displacement agent is 40℃~120℃, and the operating pressure of the heavy oil cold production displacement agent is 5MPa~30MPa.

[0073] In these embodiments, the weight m6 of the biionic nano-surfactant and the total weight m7 of the heavy oil cold production displacement agent satisfy the relationship: m6:m7=(0.05~0.5):100, which can ensure that there is a sufficient amount of biionic nano-surfactant in the heavy oil cold production displacement agent to effectively complete the cold production displacement of heavy oil. In addition, the operating temperature of the heavy oil cold production displacement agent can be 40℃~120℃, and the operating pressure of the heavy oil cold production displacement agent can be 5MPa~30MPa, which can ensure that the heavy oil cold production displacement process is fully carried out, so as to effectively improve the viscosity reduction and emulsification performance of the heavy oil cold production displacement agent through the biionic nano-surfactant.

[0074] The weight m6 of this biionic nanosurfactant can be 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45 or 0.50.

[0075] The operating temperature of this heavy oil cold recovery displacement agent can be 40℃, 60℃, 80℃, 100℃ or 120℃.

[0076] The operating pressure of this heavy oil cold extraction displacement agent can be 5 MPa, 10 MPa, 15 MPa, 20 MPa, 25 MPa or 30 MPa.

[0077] The present application is further illustrated below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to industry standards; if no corresponding industry standard exists, they are performed according to general international standards, conventional conditions, or conditions recommended by the manufacturer.

[0078] Example 1

[0079] A method for preparing biionic nanosurfactants, comprising:

[0080] (1) Preparation of nano-silica:

[0081] based on The method for preparing nano-silica is as follows:

[0082] 1) Experimental materials: Tetraethyl orthosilicate (TEOS, purity ≥98%, analytical grade), anhydrous ethanol (EtOH, ≥99.7%, analytical grade), deionized water, ammonia (28wt%, analytical grade).

[0083] 2) Experimental equipment: three-necked flask (500mL), constant temperature magnetic stirrer, N2 gas bottle, condenser, dropping funnel.

[0084] 3) Experimental conditions: Dissolve 20 mL of TEOS in 50 mL of anhydrous ethanol (molar concentration 0.5 mol / L) to obtain an anhydrous ethanol solution of TEOS;

[0085] Under nitrogen protection, 300 mL of anhydrous ethanol was added to a three-necked flask, followed by stirring and the addition of 5 mL of deionized water and 5 mL of ammonia (28% by mass). The temperature was raised to 40 °C. Anhydrous ethanol solution of TEOS was slowly added dropwise over 2 hours using a constant-pressure dropping funnel, and the reaction was continued for 6 hours. The mixture was then separated by filtration and washed three times with 100 mL of anhydrous ethanol each time. After drying under vacuum at 70 °C for 12 hours, white powdery nano-silica with a particle size of 15 nm–25 nm was obtained.

[0086] (2) Initiator introduced onto the surface of nano-silica:

[0087] S1. Nano-silica and 3-aminopropyltriethoxysilane are mixed to modify the surface of the nano-silica with 3-aminopropyltriethoxysilane, resulting in surface-modified nano-silica; the specific experimental procedure is as follows:

[0088] 1) Experimental materials: nano-silica prepared in step (1), 3-aminopropyltriethoxysilane (APTES, purity ≥98%), toluene (purity ≥99.5%, analytical grade), and anhydrous ethanol.

[0089] 2) Experimental equipment: three-necked flask (250mL), constant temperature magnetic stirrer, N2 gas bottle, condenser.

[0090] 3) Experimental conditions: Under N2 protection, 10 g of nano-silica (particle size 20 nm) was dispersed in 100 mL of anhydrous toluene and ultrasonically dispersed for 30 min. 5 mL of APTES was added, and the mixture was heated to reflux (115 °C) and reacted for 12 h. The mixture was then filtered, washed three times successively with toluene and anhydrous ethanol, and dried under vacuum at 70 °C for 12 h to obtain 9.5 g of APTES-modified nano-silica.

[0091] (3) Surface in-situ polymerized grafted block copolymers:

[0092] S2. Styrene, pentamethyldiethylenetriamine and surface-modified nano-silica are mixed, and then the mixed solution is subjected to cyclic freezing, vacuuming and thawing to obtain a mixture;

[0093] S3. 2-Bromoisobutyryl bromide, tert-butyl acrylate, copper bromide, and a mixture thereof were subjected to an in-situ polymerization reaction to obtain a block copolymer-modified nano-silica containing a benzene ring structure and polyacrylic acid. The specific experimental procedure is as follows:

[0094] 1) Experimental materials: APTES-modified nano silica, styrene (St, purity ≥99%), tert-butyl acrylate (t-BA, purity ≥98%), 2-bromoisobutyryl bromide (BIBB, purity ≥98%), pentamethyldiethylenetriamine (PMDETA, purity ≥99%), anhydrous toluene, CuBr (purity ≥99.9%).

[0095] 2) Experimental equipment: Schlenk flask (250mL), refrigeration circulation device, vacuum pump, thermostatic magnetic stirrer, N2 gas cylinder.

[0096] 3) Experimental conditions: Under N2 protection, 5g of APTES-modified nano-silica, 50mL of St and 0.5g of PMDETA in toluene solution were added to a Schlenk flask. The mixture was then subjected to a freeze-vacuum-thaw cycle, repeated three times. 0.2g of CuBr was then added, and an in-situ polymerization reaction was initiated at 90℃ for 6 hours. The reaction product was cooled to room temperature, and N2 was introduced into the Schlenk flask. 5mL of BIBB in toluene solution and 50mL of t-BA were then added, and the in-situ polymerization reaction continued at 90℃ for 12 hours, yielding a milky white suspension. This milky white suspension was then extracted and separated sequentially with dilute hydrochloric acid, deionized water, and toluene. The solvent was removed by rotary evaporation, and the mixture was then vacuum dried to obtain 7.2g of PS-b-PtBA-modified nano-silica.

[0097] (4) Hydrolysis protecting groups:

[0098] S4. The block copolymer-modified nano-silica was purified, and then the purified block copolymer-modified nano-silica was hydrolyzed to remove the protecting groups, yielding a biionic nano-surfactant; the specific experimental procedure is as follows:

[0099] 1) Experimental materials: PS-b-PtBA modified nano-silica, hydrochloric acid (36wt%~38wt%), anhydrous ethanol.

[0100] 2) Experimental equipment: single-necked round-bottom flask (250mL), thermostatic magnetic stirrer, condenser.

[0101] 3) Experimental conditions: 5g of PS-b-PtBA modified nano-silica was dispersed in 100mL of anhydrous ethanol, and 25mL of concentrated hydrochloric acid was added. The mixture was refluxed at 80℃ for 48h. After filtration, the nano-silica was washed three times with anhydrous ethanol and dried under vacuum at 70℃ for 24h to obtain 5.6g of PS-b-PAA block copolymer modified nano-silica, i.e., a twin-type nano-surfactant.

[0102] (5) Product purification and characterization:

[0103] 1) Experimental materials: Gemini nanosurfactant, acetone (≥99.5%, analytical grade), deionized water.

[0104] 2) Experimental equipment: high-speed centrifuge, vacuum drying oven.

[0105] 3) Experimental conditions: The crude product was dispersed in a large amount of acetone (product weight: acetone volume = 1:20, g / mL), sonicated for 30 min, centrifuged at high speed (10000 rpm) for 30 min, the supernatant was discarded, washed 3 times with deionized water, and dried under vacuum at 70℃ for 24 h to obtain 5.6 g of purified Gemini nanosurfactant.

[0106] Example 2

[0107] A method for preparing biionic nanosurfactants, comprising:

[0108] (1) Preparation of nano-silica: Same as in Example 1.

[0109] (2) Initiator introduced onto the surface of nano-silica:

[0110] 1) Experimental materials: nano silica, 3-aminopropyltriethoxysilane (APTES, purity ≥98%), toluene (purity ≥99.5%, analytical grade), anhydrous ethanol.

[0111] 2) Experimental equipment: three-necked flask (250mL), constant temperature magnetic stirrer, N2 gas bottle, condenser.

[0112] 3) Experimental conditions: Under N2 protection, 20 g of nano-silica (particle size 40 nm) was dispersed in 200 mL of anhydrous toluene and ultrasonically dispersed for 60 min. 10 mL of APTES was added, and the mixture was heated to reflux (120 °C) and reacted for 18 h. The mixture was then filtered, washed three times successively with toluene and anhydrous ethanol, and dried under vacuum at 80 °C for 18 h to obtain 19.0 g of APTES-modified nano-silica.

[0113] (3) Surface in-situ polymerized grafted block copolymers:

[0114] 1) Experimental materials: APTES-modified nano silica, styrene (St, purity ≥99%), tert-butyl acrylate (t-BA, purity ≥98%), 2-bromoisobutyryl bromide (BIBB, purity ≥98%), pentamethyldiethylenetriamine (PMDETA, purity ≥99%), anhydrous toluene, CuBr (purity ≥99.9%).

[0115] 2) Experimental equipment: Schlenk flask (250mL), refrigeration circulation device, vacuum pump, thermostatic magnetic stirrer, N2 gas cylinder.

[0116] 3) Experimental conditions: Under N2 protection, 8g of APTES-modified nano-silica, 80mL of St and 1.0g of PMDETA in toluene solution were added to a Schlenk flask. The mixture was then subjected to a freeze-vacuum-thaw cycle, repeated three times. 0.5g of CuBr was then added, and an in-situ polymerization reaction was initiated at 100℃ for 12h. The reaction product was cooled to room temperature, and N2 was introduced into the Schlenk flask. 8mL of BIBB in toluene solution and 20mL of t-BA were then added, and the in-situ polymerization reaction continued at 100℃ for 6h, yielding a milky white suspension. This milky white suspension was then extracted and separated sequentially with dilute hydrochloric acid, deionized water, and toluene. The solvent was removed by rotary evaporation, and the mixture was then vacuum dried to obtain 13.5g of PS-b-PtBA-modified nano-silica.

[0117] (4) Hydrolysis protecting groups:

[0118] S4. The block copolymer-modified nano-silica was purified, and then the purified block copolymer-modified nano-silica was hydrolyzed to remove the protecting groups, yielding a biionic nano-surfactant; the specific experimental procedure is as follows:

[0119] 1) Experimental materials: PS-b-PtBA modified nano-silica, hydrochloric acid (36wt%~38wt%), anhydrous ethanol.

[0120] 2) Experimental equipment: single-necked round-bottom flask (250mL), thermostatic magnetic stirrer, condenser.

[0121] 3) Experimental conditions: 8g of PS-b-PtBA modified nano-silica was dispersed in 150mL of anhydrous ethanol, and 40mL of concentrated hydrochloric acid was added. The mixture was refluxed at 80℃ for 36h. After filtration, the nano-silica was washed three times with anhydrous ethanol and dried under vacuum at 80℃ for 36h to obtain 9.2g of PS-b-PAA block copolymer modified nano-silica, i.e., a twin-type nano-surfactant.

[0122] (5) Product purification and characterization:

[0123] 1) Experimental materials: Gemini nanosurfactant, acetone (≥99.5%, analytical grade), deionized water.

[0124] 2) Experimental equipment: high-speed centrifuge, vacuum drying oven

[0125] 3) Experimental conditions: The crude product was dispersed in a large amount of acetone (product weight: acetone volume = 1:30, g / mL), sonicated for 45 min, centrifuged at high speed (12000 rpm) for 30 min, the supernatant was discarded, washed 4 times with deionized water, and dried under vacuum at 80℃ for 36 h to obtain 8.5 g of purified Gemini nanosurfactant.

[0126] Example 3

[0127] A method for preparing biionic nanosurfactants, comprising:

[0128] (1) Preparation of nano-silica: Same as in Example 1.

[0129] (2) Initiator introduced onto the surface of nano-silica:

[0130] 1) Experimental materials: nano silica, 3-aminopropyltriethoxysilane (APTES, purity ≥98%), toluene (purity ≥99.5%, analytical grade), anhydrous ethanol.

[0131] 2) Experimental equipment: three-necked flask (250mL), constant temperature magnetic stirrer, N2 gas bottle, condenser.

[0132] 3) Experimental conditions: Under N2 protection, 15 g of nano-silica (particle size 60 nm) was dispersed in 150 mL of anhydrous toluene and ultrasonically dispersed for 45 min. 8 mL of APTES was added, and the mixture was heated to reflux (115 °C) and reacted for 15 h. The mixture was filtered, washed three times successively with toluene and anhydrous ethanol, and dried under vacuum at 75 °C for 15 h to obtain 14.2 g of APTES-modified nano-silica.

[0133] (3) Surface in-situ polymerized grafted block copolymers:

[0134] 1) Experimental materials: APTES-modified nano silica, styrene (St, purity ≥99%), tert-butyl acrylate (t-BA, purity ≥98%), 2-bromoisobutyryl bromide (BIBB, purity ≥98%), pentamethyldiethylenetriamine (PMDETA, purity ≥99%), anhydrous toluene, CuBr (purity ≥99.9%).

[0135] 2) Experimental equipment: Schlenk flask (250mL), refrigeration circulation device, vacuum pump, thermostatic magnetic stirrer, N2 gas cylinder.

[0136] 3) Experimental conditions: Under N2 protection, 6g of APTES-modified nano-silica, 60mL of St, and 0.8g of PMDETA in toluene solution were added to a Schlenk flask. The mixture was then subjected to a freeze-vacuum-thaw cycle, repeated three times. 0.3g of CuBr was then added, and in-situ polymerization was initiated at 95℃ for 8 hours. The reaction product was cooled to room temperature, and N2 was introduced into the Schlenk flask. 6mL of BIBB in toluene solution and 30mL of t-BA were then added, and in-situ polymerization continued at 95℃ for another 8 hours, yielding a milky white suspension. This suspension was then extracted sequentially with dilute hydrochloric acid, deionized water, and toluene. The solvent was removed by rotary evaporation, and the mixture was then vacuum dried to obtain 11.5g of PS-b-PtBA-modified nano-silica.

[0137] (4) Hydrolysis protecting groups:

[0138] 1) Experimental materials: PS-b-PtBA modified nano-silica, hydrochloric acid (36wt%~38wt%), anhydrous ethanol.

[0139] 2) Experimental equipment: single-necked round-bottom flask (250mL), thermostatic magnetic stirrer, condenser.

[0140] 3) Experimental conditions: 6g of PS-b-PtBA modified nano-silica was dispersed in 120mL of anhydrous ethanol, and 30mL of concentrated hydrochloric acid was added. The mixture was refluxed at 85℃ for 30h. After filtration, the nano-silica was washed three times with anhydrous ethanol and dried under vacuum at 75℃ for 30h to obtain 7.2g of PS-b-PAA block copolymer modified nano-silica, i.e., a twin-type nano-surfactant.

[0141] (5) Product purification and characterization:

[0142] 1) Experimental materials: Gemini nanosurfactant, acetone (≥99.5%, analytical grade), deionized water.

[0143] 2) Experimental equipment: high-speed centrifuge, vacuum drying oven.

[0144] 3) Experimental conditions: The crude product was dispersed in a large amount of acetone (product weight: acetone volume = 1:25, g / mL), sonicated for 40 min, centrifuged at high speed (11000 rpm) for 25 min, the supernatant was discarded, washed 4 times with deionized water, and dried under vacuum at 75℃ for 30 h to obtain 6.8 g of purified Gemini nanosurfactant.

[0145] Comparative Example 1

[0146] Based on the content disclosed in Example 1, the following modifications are made:

[0147] Nano-silica was used directly as a displacement agent for cold oil recovery.

[0148] Comparative Example 2

[0149] Based on the content disclosed in Example 1, the following modifications are made:

[0150] The biionic nanosurfactant has a core-shell structure, with nano-silica as the core and hydrophobic polystyrene segments containing benzene rings as the shell.

[0151] Comparative Example 3

[0152] Based on the content disclosed in Example 1, the following modifications are made:

[0153] The dual-ionic nanosurfactant has a core-shell structure, with nano-silica as the core and hydrophilic polyacrylic acid segments as the shell.

[0154] Relevant experimental and effect data:

[0155] 1. Experiments on the displacement effect of different biionic nanosurfactants:

[0156] The biionic nanosurfactant obtained in Example 1 was prepared into an aqueous solution with a mass concentration of 0.2%, and then mixed with heavy oil (viscosity of 50000 mPa·s) at a volume ratio of 1:10, with the shear rate controlled at 500 s. -1 Emulsification reduced the viscosity of the heavy oil to 800 mPa·s, and the emulsion droplet size was 1.0 μm–2.0 μm. Using the emulsified heavy oil droplets as a displacement fluid (displacement temperature 80℃, salinity 100,000 mg / L), the heavy oil recovery rate increased by 22% at a dosage of 0.2 PV, and the long-term stability of the post-displacement fluid was >120 days.

[0157] The biionic nanosurfactant obtained in Example 2 was prepared into an aqueous solution with a mass concentration of 0.1%, and then mixed with heavy oil (viscosity of 100,000 mPa·s) at a volume ratio of 1:15, with the shear rate controlled at 800 s. -1 Emulsification reduced the viscosity of the heavy oil to 300 mPa·s, and the emulsion droplet size was 0.5 μm–1.1 μm. Using the emulsified heavy oil droplets as a displacement agent (displacement temperature 120℃, salinity 200,000 mg / L), the heavy oil recovery rate increased by 18% at a dosage of 0.1 PV, and the long-term stability of the post-displacement fluid was >150 days.

[0158] 2. The biionic nanosurfactants obtained in each example and comparative example were first prepared into aqueous solutions with a mass concentration of 0.1%, and then mixed with heavy oil (viscosity of 100,000 mPa·s) at a volume ratio of 1:15, controlling the shear rate at 800 s. -1 Emulsification was performed, and then the emulsified heavy oil droplets were used as displacement heavy oil (displacement temperature 120℃, salinity 200000mg / L). The percentage increase in heavy oil recovery for each biionic nanosurfactant group and the long-term stability time of the displacement fluid were calculated at a dosage of 0.1PV. The results are shown in Table 1.

[0159] Table 1 shows the heavy oil recovery rate and long-term stability time of the post-displacement fluid obtained from the various examples and comparative examples using biionic nanosurfactants.

[0160]

[0161] As shown in Table 1, the biionic nanosurfactant provided in this application is designed with a core-shell structure, using nano-silica as the core and polystyrene hydrophobic segments and polyacrylic acid hydrophilic segments containing benzene rings as the shell. This can improve the emulsification effect of the biionic nanosurfactant on heavy oil, thereby increasing the recovery rate of heavy oil to more than 10%, and the long-term stability of the post-displacement fluid is more than 100 days.

[0162] Another embodiment of this application provides a biionic nanosurfactant that uses nano-silica as the core and polystyrene hydrophobic segments containing benzene rings and polyacrylic acid hydrophilic segments as the shell. Based on the nano-size effect of nano-silica and the synergistic effect of the surface chemical structure of the amphiphilic block copolymer, the biionic surfactant can better penetrate into the heavy oil layer of heavy oil reservoirs and accumulate on the surface of pores to exert a deeper viscosity-reducing effect. In addition, based on the nano-size effect of nano-silica and the surface bonding effect of the surface chemical structure of the amphiphilic block copolymer, the biionic nanosurfactant can be endowed with better temperature and salt resistance, thereby enabling the biionic nanosurfactant to adapt to the extreme conditions of heavy oil reservoirs.

[0163] In addition, this application provides a biionic nanosurfactant that combines the high specific surface area and modifiability of nanocarriers such as nano-silica with the amphiphilicity and functionality of amphiphilic block copolymers. First, the surface of nano-silica is organically modified, and then amphiphilic block copolymers with lipophilic and hydrophilic groups are simultaneously grafted onto its surface to form a novel nanosurfactant with a core-shell twin structure. This nanosurfactant can combine the affinity of heavy oil matrix, emulsification and viscosity reduction performance and deep penetration ability, and is expected to significantly improve the efficiency of cold oil recovery and displacement.

[0164] In addition, this application provides a biionic nanosurfactant that uses nano-silica as the core. Nano-silica can be used as a nanoparticle carrier to prolong the adsorption and retention time of the biionic nanosurfactant on the pore surface of underground reservoirs, thereby enabling the biionic nanosurfactant to continuously release active substances and significantly improve the durability of the viscosity reduction effect.

[0165] Furthermore, the present application provides a method for preparing a biionic nanosurfactant. This method is simple in process, uses widely available and inexpensive raw materials, and meets the requirements for cost-effectiveness optimization. It has broad application prospects in the field of heavy oil extraction.

[0166] Furthermore, the method for preparing a biionic nanosurfactant provided in this application embodiment can precisely control the core size of nano-silica within the range of 5nm to 100nm, as well as the chain length of the amphoteric block copolymer containing benzene ring-structured hydrophobic segments of polystyrene and hydrophilic segments of polyacrylic acid (the chain length of the benzene ring-structured hydrophobic segments of polystyrene is 1kDa to 100kDa, and the chain length of the polyacrylic acid hydrophilic segments is 0.5kDa to 50kDa), and the degree of polymerization n1 of polystyrene hydrophobic segments and n2 of polyacrylic acid hydrophilic segments satisfy the relationship n1:n2 = 1:10 to 10:1. This yields a twin-type nanosurfactant with an adjustable HLB value within the range of 5 to 18, thus adapting to the needs of different heavy oil reservoirs.

[0167] Furthermore, the embodiments of this application provide a heavy oil cold production displacing agent. The emulsion obtained by displacing heavy oil with this heavy oil cold production displacing agent does not show significant changes in particle size and viscosity, and the water content of the emulsion remains above 90%, which can exhibit excellent dynamic and static stability. This breaks through the bottleneck of conventional surfactants being prone to agglomeration and oil separation, which undoubtedly extends the effective action time of the displacing system.

[0168] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed in this application.

Claims

1. A biionic nanosurfactant, characterized in that, The biionic nanosurfactant has a core-shell structure, with nano-silica as the core and an amphiphilic block copolymer as the shell; wherein, the amphiphilic block copolymer includes a polystyrene hydrophobic segment containing a benzene ring structure and a polyacrylic acid hydrophilic segment; the chain length L1 of the polystyrene hydrophobic segment containing a benzene ring structure and the chain length L2 of the polyacrylic acid hydrophilic segment satisfy the relationship: L1:L2=(1~100):(0.5~50).

2. The biionic nanosurfactant according to claim 1, characterized in that, The degree of polymerization n1 of the polystyrene hydrophobic segment containing the benzene ring structure and the degree of polymerization n2 of the polyacrylic acid hydrophilic segment satisfy the following relationship: n1:n2=(1:10)~(10:1).

3. The dual-ionic nanosurfactant according to claim 1, characterized in that, The particle size of the nano-silica is 5nm to 100nm.

4. The biionic nanosurfactant according to claim 1, characterized in that, The hydrophilic-lipophilic balance value of the biionic nanosurfactant is 5 to 18.

5. A method for preparing a biionic nanosurfactant as described in any one of claims 1 to 4, characterized in that, The method includes: Nano-silica and 3-aminopropyltriethoxysilane are mixed to modify the surface of the nano-silica with the 3-aminopropyltriethoxysilane, resulting in surface-modified nano-silica. Styrene, pentamethyldiethylenetriamine and the surface-modified nano-silica were mixed, and the mixed solution was then subjected to cyclic freezing, vacuuming and thawing to obtain a mixture. 2-bromoisobutyryl bromide, tert-butyl acrylate, copper bromide and the mixture were subjected to in-situ polymerization to obtain block copolymer modified nano-silica containing benzene ring structure p-tert-butylbenzoic acid and polyacrylic acid. The block copolymer-modified nano-silica was purified, and then the purified block copolymer-modified nano-silica was hydrolyzed to remove the protecting groups of the block copolymer-modified nano-silica, thereby obtaining a biionic nano-surfactant.

6. The method according to claim 5, characterized in that, The weight m1 of the nano-silica and the volume V1 of the 3-aminopropyltriethoxysilane satisfy the following relationship: m1:V1=(1~20):(1~15), where if the unit of m1 is g, then the unit of V1 is mL. The volume V2 of the styrene, the weight m2 of the pentamethyldiethylenetriamine, and the weight m3 of the surface-modified nano silica satisfy the following relationship: V2:m2:m3=(10~100):(0.1~2.0):(1~5), where if the units of m2 and m3 are g, then the unit of V2 is mL; The volume V3 of the 2-bromoisobutyryl bromide, the volume V4 of the tert-butyl acrylate, the weight m4 of the copper bromide, and the weight m5 of the mixture satisfy the following relationship: V3:V4:m4:m5=(1~10):(10~100):(0.05~1.00):(1~10).

7. The method according to claim 5, characterized in that, The in-situ polymerization reaction is carried out at a temperature of 80℃ to 110℃ and for a duration of 2h to 24h.

8. The method according to claim 5, characterized in that, The in-situ polymerization reaction of 2-bromoisobutyryl bromide, tert-butyl acrylate, copper bromide, and the mixture to obtain block copolymer-modified nano-silica containing a benzene ring structure and polyacrylic acid includes the following steps: The copper bromide and the mixture are mixed to allow the mixture to undergo a preliminary in-situ polymerization reaction, yielding a primary mixed reactant. 2-Bromoisobutyryl bromide, tert-butyl acrylate, and the primary mixed reactant are mixed to allow the primary mixed reactant to undergo an in-situ polymerization reaction, resulting in a block copolymer modified nano-silica containing a benzene ring structure of p-tert-butylbenzoic acid and polyacrylic acid.

9. A heavy oil cold-production displacement agent, characterized in that, The heavy oil cold recovery displacement agent includes the biionic nanosurfactant as described in any one of claims 1 to 4.

10. The heavy oil cold recovery displacement agent according to claim 9, characterized in that, The weight m6 of the dual-ionic nano-surfactant and the total weight m7 of the heavy oil cold production displacement agent satisfy the following relationship: m6:m7=(0.05~0.5):

100. The operating temperature of the heavy oil cold production displacement agent is 40℃~120℃, and the operating pressure of the heavy oil cold production displacement agent is 5MPa~30MPa.

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