Membrane-like viscoelastic composite material having solid-fluid transition characteristics and applications thereof

Abstract

The application discloses a film-shaped viscoelastic composite material with solid-fluid transition characteristics and application thereof. A preparation method of the material comprises the following steps: adding a bio-based Gemini anionic surfactant into a buffer solution, heating and stirring to form a mixed solution, and standing to obtain the film-shaped viscoelastic composite material with solid-fluid transition characteristics; the bio-based Gemini anionic surfactant is a gemini surfactant connected by an amide bond between a bio-based single-chain anionic surfactant and N,N'-diphenyl-1,3-propanediamine. The film-shaped viscoelastic composite material can be applied to oil and gas field development, and the solid-fluid transition characteristics of the film-shaped viscoelastic composite material meet low viscosity flow during injection to realize deep reservoir profile control and flooding by entering deep strata, and high viscoelasticity plugging after injection; the film-shaped viscoelastic composite material is used as a deformable plugging agent and profile control and flooding agent for plugging and profile control and flooding operation in micro-nano pore throat strata.

Description

TECHNICAL FIELD

[0001] The present application relates to a film-shaped viscoelastic composite material with solid-fluid transition characteristics, belonging to the technical field of oil exploitation. BACKGROUND

[0002] In recent years, with the sustained and stable growth of China's economy, the demand for energy such as oil and natural gas has increased rapidly in a geometric pattern. In 2024, China's crude oil production was about 213 million tons, and imported crude oil was about 553 million tons, with a foreign dependence rate of 70.0%, far exceeding the 61.0% red line specified in the "Twelfth Five-Year Plan" for energy development. Therefore, improving the recovery efficiency of crude oil (EOR) is an urgent problem to be solved, and is an important guarantee for promoting the stable and growth of China's crude oil production. At present, with the gradual depletion of easily exploitable oil fields, oil field development has gradually shifted to complex areas such as deep, super heavy oil, shale oil, and high water cut reservoirs, and the difficulty and cost of exploitation have increased significantly. Influenced by the factors of formation heterogeneity, injected water or displacement fluid is prone to "water channeling" along the dominant channel, resulting in reduced sweep efficiency and a large amount of remaining oil remaining in low permeability areas, which seriously affects the development effect of oil fields. At present, profile control and water plugging technology has become the main effective means to improve the development effect of oil field water injection and improve the recovery efficiency of high water cut oil fields.

[0003] Profile control and water plugging technology can improve displacement efficiency and increase recovery by injecting oil field plugging agents into the formation to plug high permeability channels and adjust the flow direction. Therefore, oil field plugging agents are the key chemicals for adjusting reservoir permeability, plugging high permeability layers or fractures, and improving the recovery efficiency of crude oil (EOR). The most widely used plugging agent in oil fields at present is a viscoelastic material with a three-dimensional network structure formed by cross-linking polymer and cross-linking agent at a certain temperature, also known as gel-type plugging agent. The commonly used polymers for gel-type plugging agents are polyacrylamide (HPAM) and partially hydrolyzed polyacrylamide (HPAM); the cross-linking agents mainly include organic cross-linking agents such as aldehydes, phenolic aldehydes, organic ions, etc., inorganic cross-linking agents such as chromium ion system, zirconium ion system, and composite cross-linking agents such as metal ion complexes, which can cause polymer dehydration condensation, cross-linking polymerization or coordination reaction to form a three-dimensional network structure.

[0004] It is well known that for channeling plugging agent, it is required to have good injectivity and plugging effect. Its viscoelasticity (strength) under formation conditions is the most important factor affecting its plugging effect, and the strength of the gel type plugging agent needs to be high to obtain ideal plugging effect. However, good injectivity requires low strength and easy flow of the plugging agent. Different reservoirs also have different requirements for the strength of the plugging agent. Therefore, it is often necessary to introduce various additives to enhance the strength of the gel type plugging agent, thereby resulting in a generally complex formula of the gel type plugging agent. For example, the formula of the water plugging agent developed for Chaoyanggou oilfield is: 0.7% cationic HPAM + 2% calcium lignosulfonate (Ca-Ls) + 0.3% organic chromium + 0.15% sodium bicarbonate (NaHCO) + 0.005% thiourea (Journal of Petroleum and Chemical Industry Colleges, 2017, 30(06): 42-47.); the formula of the plugging agent applied in Qinghai oilfield is: 0.6% quaternary hydrophobic association polymer (AM / AMPS / DMC / NVP) + 0.6% polyphenol aldehyde resin crosslinking agent + 0.2% sodium thiosulfate + 0.3% nano silicon dioxide (Journal of Xi'an Shiyou University (Natural Science Edition), 2025, 40(1): 65-70). However, while obtaining high-strength polymer gel type plugging agent, its dense three-dimensional network structure often leads to the problem of difficulty in breaking the gel after the completion of the plugging operation, thereby causing serious damage to the formation; and the crosslinking agent (such as chromium) will cause environmental pollution. In addition, this three-dimensional network structure also leads to poor flowability of the polymer gel type plugging agent, making the injection process difficult and unable to move smoothly to the deep part of the reservoir to achieve deep reservoir profile control and flooding. SUMMARY

[0005] The purpose of the present application is to overcome the shortcomings of the prior art, and to provide a novel film-shaped viscoelastic composite material with solid-fluid transition characteristics, which can be applied to the field of oil exploitation for profile control and plugging, thereby effectively improving the recovery rate of crude oil.

[0006] The viscoelastic composite material of the present application is obtained by dissolving a specific bio-based Gemini anionic surfactant in a buffer solution, and has a simple formula and is environmentally friendly. The initial viscosity of the mixed solution is very low, and the flowability is good, which ensures good injectivity. The film-shaped viscoelastic composite material is obtained after standing for 5-10 days, and exhibits extremely high viscosity and solid elastic properties, which endow it with good plugging effect. This solid-fluid transition characteristic has important significance in the field of oil exploitation technology as a plugging agent.

[0007] The microstructure of the film-shaped viscoelastic composite material is novel flexible film-shaped, the film spacing is 50-70 nm, and the elastic modulus is 1000-6000 Pa, the structure is formed by weak interactions such as van der Waals force, hydrogen bond and hydrophobic interaction between Gemini anionic surfactant molecules, and is easy to break after the plugging operation is completed, and will not cause damage to the formation.

[0008] The preparation method of the film-shaped viscoelastic composite material with solid-fluid transition characteristics provided by the application is as follows:

[0009] The bio-based Gemini anionic surfactant powder is added to a buffer solution, heated and stirred to form a mixed solution, and then left to obtain the film-shaped viscoelastic composite material with solid-fluid transition characteristics.

[0010] The bio-based Gemini anionic surfactant is a Gemini surfactant formed by connecting a bio-based single-chain anionic surfactant and N,N'-diphenyl-1,3-propanediamine through an amide bond.

[0011] Preferably, the bio-based single-chain anionic surfactant is one of N-lauroyl sarcosine, N-myristoyl sarcosine, N-oleoyl sarcosine, oleoyl-N-beta-hydroxyethyl-glycine and lauroyl-N-beta-hydroxyethyl-glycine.

[0012] In the mixed solution, the concentration of the bio-based Gemini anionic surfactant is 0.01-0.10 mol / L, preferably 0.05-0.10 mol / L.

[0013] In the method, preferably, the buffer solution is a sodium phosphate buffer (NaH2PO4-Na2HPO4) or a potassium phosphate buffer (K2HPO4-KH2PO4).

[0014] The pH of the buffer solution ranges from 5.29 to 6.47.

[0015] In the method, the main role of the buffer solution is that the buffer solution is acidic, which can promote the dissolution of the bio-based Gemini anionic surfactant in the aqueous solution; the amino group -NH2 contained in the bio-based Gemini anionic surfactant is converted into -NH3 + under the acidic environment, part of the bio-based Gemini anionic surfactant is converted into ionic surfactants, and these surfactant molecules and ions are connected together by van der Waals force, hydrogen bond and hydrophobic interaction to assemble into a film-shaped structure, but at the same time, the metal cations contained in the buffer solution and -NH3 +The electrostatic repulsion effect exists, which delays the formation speed of the film sheet structure to a certain extent, so that the mixed solution needs a certain time to form a composite material with high viscosity and elasticity, so as to ensure that the mixed solution has sufficient time to enter the deep part of the oil reservoir to realize deep profile control and flooding; and the pH of the solution is stable.

[0016] In the method, the heating temperature is 60-80 DEG C.

[0017] The stirring rate is 500-1000r / min, and the stirring time is 5-10 minutes.

[0018] The standing time is 10-15 days.

[0019] Preferably, the bio-based Gemini anionic surfactant is prepared by the following method:

[0020] 1) the bio-based single-chain anionic surfactant and the N,N-diphenyl-1,3-propanediamine are added to an organic solvent for refluxing for 24-36h;

[0021] The molar ratio of the bio-based single-chain anionic surfactant to the N,N-diphenyl-1,3-propanediamine is 4:1-2:1;

[0022] The organic solvent is ethanol, tetrahydrofuran, chloroform or N,N-dimethylformamide;

[0023] 2) acetonitrile is added to the system of step 1), and after stirring and refluxing, a white precipitate is separated, and the stirring rate is 800-1200r / min;

[0024] 3) the white precipitate is dissolved in toluene for refluxing, and after ultrasonic water washing, filtration and drying, it is obtained.

[0025] The film sheet viscoelastic composite material provided by the application can be applied to oil and gas field development, and the solid-fluid transition characteristics of the film sheet viscoelastic composite material meet the low viscosity flow during injection to enter the deep part of the formation to realize deep profile control and flooding, and high viscoelasticity plugging after injection.

[0026] The film sheet viscoelastic composite material is used as a deformable plugging agent and profile control and flooding agent for plugging and profile control and flooding operations in micro-nano pore throat formations.

[0027] The most widely used polymer gel plugging agent in oilfield has the technical bottleneck of poor injectivity and difficult gel breaking due to its three-dimensional network structure, and a new type of plugging agent is urgently needed. The reported surfactant viscoelastic materials are generally prepared by compounding two kinds of anionic and cationic surfactants in aqueous solution. Due to the strong electrostatic attraction between anions and cations, ion pairs are formed. Once the two kinds of surfactants are mixed in the aqueous solution, a viscoelastic material with high viscosity and poor flowability is formed. This characteristic leads to problems such as difficulty in injecting into the formation and inability to migrate in the pore, thereby limiting its application in the field of oil exploitation. Although reducing the concentration of the two kinds of surfactants can reduce the viscosity of the system to some extent and improve its flowability, it will also lead to poor viscoelastic properties after entering the formation, which cannot achieve effective plugging effect, resulting in unsatisfactory enhanced oil recovery effect. The film-shaped viscoelastic composite material with solid-liquid transition characteristics has the characteristics of dissolving the environment-friendly bio-based Gemini anionic surfactant in a weak acid buffer solution to obtain an initial solution with very low viscosity, ensuring good injectivity. Further, the weak acid buffer solution provides a proton for the amino group -NH2 of the bio-based Gemini anionic surfactant molecule to be converted into -NH3 + , so that part of the Gemini non-ionic fluorocarbon surfactant is converted into ionic surfactant, and then driven by van der Waals force, hydrogen bonding and hydrophobic interaction, these surfactant molecules and ions are connected together to assemble into a film-like structure, and the metal cations and -NH3 + exist electrostatic repulsion, which will delay the formation speed of the film-like structure to some extent, so the initial solution needs a certain time to form a composite material with high viscoelasticity, thereby ensuring that the initial solution has sufficient time to enter the deep part of the oil reservoir to realize deep profile control and plugging operation. The unique solid-liquid transition characteristics and flexible film-like structure of the present application give it a low initial viscosity for easy injection into the formation, and after smooth migration to the deep part of the oil reservoir, it has high viscoelasticity to achieve plugging effect.

[0028] The present application has the following beneficial technical effects:

[0029] (1) The film-shaped viscoelastic composite material with solid-liquid transition characteristics for oil and gas fields has a simple preparation method and formula, and is prepared by dissolving a specific bio-based Gemini anionic surfactant in a buffer solution. The initial solution has very low viscosity and good flowability, and is converted into a viscoelastic composite material with extremely high viscosity and solid characteristic elastic properties after standing for 10-15 days, showing solid-liquid transition characteristics.

[0030] (2) The oil and gas field film-shaped viscoelastic composite material with solid-fluid conversion characteristics is green and environmentally friendly, can realize low viscosity flow during injection, smoothly migrate to the deep part of the oil reservoir, and high viscoelasticity plugging after the migration, and can be used as a deformable plugging agent and a profile control agent for plugging and profile control operation in a micro-nano pore throat formation.

[0031] (3) The oil and gas field film-shaped viscoelastic composite material with solid-fluid conversion characteristics has a microstructure of a film-shaped structure with flexibility, and the film sheets are connected by weak intermolecular interaction, which can ensure that the structure can be deformed and pass through the oil reservoir pores, and the structure is not easy to be damaged, and has good shear resistance, and can ensure that the structure is destroyed by injecting an alkaline solution after the plugging operation is completed, so as to realize gel breaking and avoid damage to the formation.

[0032] (4) The oil and gas field film-shaped viscoelastic composite material with solid-fluid conversion characteristics can simply adjust the concentration of the bio-based Gemini anionic surfactant to control the size of the viscosity and elasticity, so as to ensure that the viscoelastic composite material meets the performance requirements of different oil reservoirs for different viscosity and elasticity sizes when used for oil field plugging and profile control.

[0033] (5) The film-shaped viscoelastic composite material with solid-fluid conversion characteristics has novel and unique structure and performance, enriches the existing surfactant viscoelastic composite material research field, and expands the application in the field of oil exploitation. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 It is a solid-fluid conversion characteristic picture of the film-shaped viscoelastic composite material of the embodiment 1 of the present application.

[0035] Figure 2 It is a microstructure photo of the film-shaped viscoelastic composite material of the embodiment 1 of the present application.

[0036] Figure 3 It is the viscoelasticity of the film-shaped viscoelastic composite material of the embodiment 1 of the present application.

[0037] Figure 4 It is the shear resistance of the film-shaped viscoelastic composite material of the embodiment 1 of the present application.

[0038] Figure 5 It is the small-angle X-ray scattering (SAXS) curve of the film-shaped viscoelastic composite material of the embodiment 1 of the present application.

[0039] Figure 6 It is the plugging performance of the film-shaped viscoelastic composite material of the embodiment 1 of the present application.

[0040] Figure 7 It is the oil displacement effect of the film-shaped viscoelastic composite material of the embodiment 1 of the present application.

[0041] Figure 8 Microstructure photograph of the film-like viscoelastic composite material of Example 2 of the present application.

[0042] Figure 9 Small-angle X-ray scattering (SAXS) curve of the film-like viscoelastic composite material of Example 2 of the present application.

[0043] Figure 10 Viscoelasticity of the film-like viscoelastic composite material of Example 2 of the present application.

[0044] Figure 11 Solid-liquid transition characteristic picture of the film-like viscoelastic composite material of Example 3 of the present application.

[0045] Figure 12 Microstructure photograph of the film-like viscoelastic composite material of Example 3 of the present application.

[0046] Figure 13 Viscoelasticity of the film-like viscoelastic composite material of Example 3 of the present application.

[0047] Figure 14 Small-angle X-ray scattering (SAXS) curve of the film-like viscoelastic composite material of Example 3 of the present application. DETAILED DESCRIPTION

[0048] The experimental methods used in the following examples are conventional methods unless otherwise specified.

[0049] The materials, reagents, etc. used in the following examples can be obtained from commercial channels unless otherwise specified.

[0050] The film-like viscoelastic composite material referred to in the present application refers to a functional material formed by dissolving a bio-based Gemini anionic surfactant in a buffer solution, and its microstructure is a flexible film-like network, which has both the elasticity of a solid and the deformation ability of a fluid.

[0051] The solid-liquid transition characteristic referred to in the present application refers to the characteristic of the film-like viscoelastic composite material of the present application in transitioning from the initial solution low-viscosity flow state (low elastic modulus, high fluidity) to the solid state (high elastic modulus, low fluidity), which is achieved by the protons released by the acidic buffer solution regulating the self-assembly of the solution to form a film-like structure.

[0052] The bio-based Gemini anionic surfactant referred to in the present application refers to a double-chain surfactant covalently connected by two hydrophobic chains and two hydrophilic head groups through a rigid linker (amide bond).

[0053] Examples 1-2,

[0054] 2.10 g of N-myristoylsarcosine and 0.51 g of N,N-diphenyl-1,3-propanediamine were added to 500 mL of ethanol and stirred at reflux for 24 hours at room temperature; then 500 mL of acetonitrile was added, and the acetonitrile and the above solution were stirred and refluxed to separate a white solid precipitate; the obtained precipitate was dissolved in 200 mL of toluene and refluxed for 2 hours, and then the product was ultrasonically washed with water and filtered. The process was repeated three times and dried to obtain a white powdery solid of a bio-based Gemini anionic surfactant.

[0055] The white powdery solid of the bio-based Gemini anionic surfactant was added to the NaH2PO4-Na2HPO4 buffer solution with a pH of 5.29 to prepare an initial solution with a concentration of 0.1 mol / L. Its viscosity was 9.21 mPa·s. Figure 1 As shown in the figure, the fluidity is good. The temperature is controlled at 65℃, the stirring rate is 800r / min, the stirring is carried out for 5 minutes, and then the mixture is allowed to stand at room temperature for 10 days.

[0056] The viscoelastic composite material prepared in this embodiment is as follows Figure 1 As shown, the reagent bottle is fluid when tilted, but basically does not flow when tilted after standing for 10 days, indicating its solid properties ( Figure 1 After adding 0.1 mol / L NaOH solution to the reagent bottle, the viscoelastic composite material loses its solid properties and becomes a fluid liquid, demonstrating its excellent gel-breaking performance.

[0057] The microstructure photo of the viscoelastic composite material prepared in this example is shown in FIG. Figure 2 As shown, the membrane-like structure can be clearly seen from the electron microscope photo, and the membrane is folded, indicating that it has good "flexibility", thus ensuring that it can be deformed through micro-nanoscale pore throats.

[0058] The rheological properties of the viscoelastic composite material prepared in this embodiment are as follows: Figure 3 As shown in the figure, it can be seen that it has high viscoelasticity, with an elastic modulus of 5000Pa and a viscous modulus of 700Pa. The thixotropy test results are shown in the figure. Figure 4 As shown in the figure, with the increase of shear rate, the viscosity of the composite material decreases significantly; when the shear effect is removed, the upward curve and the downward curve of the solution basically coincide, with only a small difference at low shear rates, indicating that the viscosity gradually returns to its original state and the microstructure does not change, proving that the structure of the composite material of the present invention is not easily destroyed under shear action and has good shear resistance.

[0059] Small angle X-ray scattering results ( Figure 5) proves that the distance between the diaphragms of the viscoelastic composite material prepared in this embodiment is 49.92 nm, and the diaphragms are connected by weak intermolecular interactions. Therefore, after the diaphragms are deformed through the pore throats, the weak intermolecular interactions between the diaphragms will be rebuilt, which is why it has shear resistance.

[0060] Further high permeability core plugging experiments and low permeability fracture core oil displacement experiments were designed to clarify the plugging effect and oil displacement performance of the membrane-like viscoelastic composite material with solid-fluid transition characteristics of the present invention.

[0061] In the plugging performance test, the plugging rate is used to evaluate the plugging performance of the plugging agent. The plugging rate is a key indicator for measuring the system's ability to plug high-permeability channels in the formation. It indicates the plugging strength of the membrane-like viscoelastic composite material with solid-fluid transition properties after injection. The specific steps are as follows:

[0062] (1) Fill the water tank with prepared simulated water, mix and stir the bio-based Gemini anionic surfactant and buffer solution, and then put them into the chemical tank; (2) Inject simulated water at a certain speed for water drive until the pressure at the front end of the core holder is stable, and calculate the permeability of the artificial core with a stable pressure reading. Then inject a mixed solution of bio-based Gemini anionic surfactant and buffer solution at the same injection rate as the water injection rate until it can be collected at the outlet end to ensure that the solution is evenly filled in the entire core. Finally, seal the injection end and the tail end. (3) After standing for 10 days, open both ends of the core holder to release the pressure, open the water bottle to start the second water drive, keep the injection rate the same as before, and continue to inject until the pressure is stable. Calculate the data curve of pressure change with injection volume and calculate the core permeability and gel plugging rate after gel plugging. The results are as follows Figure 6 shown.

[0063] The calculation shows that the plugging rate of the system for a 1000 mD core is 98.55%, indicating that the membrane-like viscoelastic composite material with solid-fluid transition characteristics of the present invention has a good plugging effect.

[0064] The low-permeability fracture core test is used to test the enhanced oil recovery performance of the film-shaped viscoelastic composite material with solid-fluid transition characteristics of the present application. The specific experimental steps are as follows: (1) first, the treated core is placed in the core holder to start saturating the crude oil, and the core oil saturation and saturation volume are recorded and calculated. After the core is saturated with crude oil and aging is completed, the core is taken out and prepared into a fracture. The prepared fracture core is placed in the core holder; (2) the water tank is opened to start the crude oil displacement experiment at a flow rate of 0.2 mL / min. The recovery rate and pressure change data are recorded; (3) after the tail end stops producing oil, the water tank is closed, and the prepared bio-based Gemini anionic surfactant and buffer solution mixed system is injected. After the required PV solution is injected, the core holder injection end and tail end are sealed. After 10 days of standing, the subsequent water flooding experiment is continued, and the crude oil recovery rate and pressure change data are recorded. The experiment is stopped when there is no oil production at the tail end.

[0065] The core displacement experiment results are shown in Figure 7 . For the fracture core with a fracture opening of 0.2 mm and a core permeability of 10 mD, the first water flooding pressure is about 216 kPa, and the recovery rate of the first water flooding is 7.56%. The displaced crude oil is mainly the aged oil present in the fracture. After injecting the bio-based Gemini anionic surfactant and buffer solution mixed system, the solution mainly flows along the dominant pore channel into the core gap, and the injection pressure also increases, reaching 520 kPa at 1 PV. After the solution is converted into a viscoelastic composite material, the second water flooding is carried out. At this time, due to the plugging of the viscoelastic composite material in the fracture, the simulated water begins to enter the small pores that have not been reached, resulting in a sharp increase in pressure and an increase in recovery rate. Finally, the recovery rate is improved by 24.23%. The results show that the film-shaped viscoelastic composite material of the present application has good plugging and oil displacement effect.

[0066] The viscoelastic composite material system is prepared according to the above formula and method. The only difference is that the bio-based Gemini anionic surfactant white powder solid is added to the NaH2PO4-Na2HPO4 buffer solution with a pH of 5.29 to prepare an initial solution with a concentration of 0.05 mol / L, which is Example 2. In this example, the viscosity of the initial solution is 5.32 mPa@s, and after 10 days of standing, the final viscoelastic composite material is still film-shaped Figure 8 . However, the distance between the films is 69.16 nm Figure 9 . The elastic modulus and viscous modulus are 1000 and 600 Pa Figure 10 , respectively. This shows that by changing the concentration of the bio-based Gemini anionic surfactant, the viscoelasticity of the viscoelastic composite material can be effectively adjusted, and the solid-fluid transition characteristics are given.

[0067] Example 3,

[0068] 4.06 g of lauroyl-N-β-hydroxyethyl-glycine and 1.20 g of N,N-diphenyl-1,3-propylenediamine were added to 500 mL of ethanol and stirred at reflux for 24 hours at room temperature; then 500 mL of acetonitrile was added, and the above solution was stirred and refluxed with acetonitrile to separate a white solid precipitate; the obtained precipitate was dissolved in 200 mL of toluene and refluxed for 2 hours, and then the product was ultrasonically washed with water and filtered. The process was repeated three times and dried to obtain a white powdery solid of a bio-based Gemini anionic surfactant.

[0069] The white powdery solid of the bio-based Gemini anionic surfactant was added to the pH 6.15 NaH2PO4-Na2HPO4 buffer solution to prepare an initial solution with a concentration of 0.1 mol / L, and its viscosity was 8.65 mPa@s. Figure 11 As shown in the middle left figure, it has good fluidity. The temperature is controlled to 80℃, the stirring rate is 900r / min, stirring for 10 minutes, and then standing at room temperature for 15 days. The viscoelastic composite material prepared in this embodiment is obtained, as shown in FIG. Figure 11 As shown in the middle right image, the material exhibits fluidity when tilted, but becomes virtually non-fluid when tilted after 15 days, demonstrating its solid properties. Adding 0.1 mol / L NaOH solution to the material causes the viscoelastic composite to lose its solid properties and become a fluid, demonstrating its excellent gel-breaking properties.

[0070] The microstructure photo of the viscoelastic composite material prepared in this example is shown in FIG. Figure 12 As shown, the membrane-like structure can be clearly seen from the electron microscope photo, and the membrane is folded, indicating that it has good "flexibility", thus ensuring that it can be deformed through micro-nanoscale pore throats.

[0071] The rheological properties of the viscoelastic composite material prepared in this embodiment are as follows: Figure 13 As shown, it can be seen that it has high viscoelasticity, with an elastic modulus of 2000 Pa and a viscous modulus of 1000 Pa. Small angle X-ray scattering results ( Figure 14 ) proves that the distance between the diaphragms of the viscoelastic composite material prepared in this embodiment is 58.42 nm.

Claims

1. A method for preparing a film-like viscoelastic composite material having solid-fluid transition properties, comprising the following steps: The bio-based Gemini anionic surfactant is added to a buffer solution, heated and stirred to form a mixed solution, and allowed to stand to obtain a membrane-like viscoelastic composite material with solid-fluid transition properties; The bio-based Gemini anionic surfactant is a Gemini surfactant that is connected to a bio-based single-chain anionic surfactant and N,N'-diphenyl-1,3-propanediamine through an amide bond; The bio-based single-chain anionic surfactant is one of N-lauroyl sarcosine, N-myristoyl sarcosine, N-oleoyl sarcosine, oleoyl-N-hydroxyethyl-glycine and lauroyl-N-hydroxyethyl-glycine.

2. The preparation method according to claim 1, wherein: The buffer solution is a sodium phosphate buffer or a potassium phosphate buffer with a pH range of 5.29-6.

47.

3. The preparation method according to claim 1 or 2, characterized in that: In the mixed solution, the concentration of the bio-based Gemini anionic surfactant is 0.01-0.10 mol / L.

4. The preparation method according to claim 1 or 2, characterized in that: The heating temperature is 60-80°C; The stirring rate is 500-1000 r / min and the time is 5-10 minutes; The standing time is 10-15 days.

5. The preparation method according to claim 1 or 2, characterized in that: The bio-based Gemini anionic surfactant is prepared by the following method: 1) Add a bio-based single-chain anionic surfactant and N,N-diphenyl-1,3-propanediamine to an organic solvent and reflux for 24-36 hours; The molar ratio of the bio-based single-chain anionic surfactant to the N,N-diphenyl-1,3-propylenediamine is 4:1-2:1; The organic solvent is ethanol, tetrahydrofuran, chloroform or N,N-dimethylformamide; 2) adding acetonitrile to the system of step 1), stirring and refluxing to separate a white precipitate, wherein the stirring rate is 800 to 1200 r / min; 3) The white precipitate is dissolved in toluene and refluxed, then ultrasonically washed, filtered, and dried to obtain the product.

6. A film-like viscoelastic composite material having solid-fluid transition properties prepared by the method according to any one of claims 1 to 5.

7. Use of the membrane-like viscoelastic composite material according to claim 6 in oil and gas field development.

8. The use according to claim 7, characterized in that: The diaphragm-shaped viscoelastic composite material is used as a deformable plugging agent and displacement agent for plugging and displacement operations in micro-nano-scale pore throat formations.

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