Screening method for oil displacement system based on single-molecule membrane characterization and application thereof

Abstract

The application provides a screening method for oil displacement systems based on single-molecule film characterization and application thereof, and the screening method comprises the following steps: (1) preparing an oil displacement agent aqueous solution, and determining the interfacial tension between the oil displacement agent aqueous solution and crude oil or simulated oil; (2) preparing an oil displacement agent organic solvent solution, and determining the maximum elastic modulus of an interfacial film by using a Langmuir single-molecule film experiment; (3) preparing an oil displacement agent aqueous solution, and determining the interfacial extensional rheological phase angle between the oil displacement agent aqueous solution and crude oil or simulated oil; (4) comprehensively considering the interfacial tension, the maximum elastic modulus of the interfacial film and the interfacial extensional rheological phase angle, and proposing an interfacial film number Φ; (5) using the oil displacement agent for oil displacement experiments to obtain enhanced oil recovery (EOR), fitting to obtain a relationship between the interfacial film number Φ and the enhanced oil recovery (EOR), and the oil displacement system can be screened by the size of the interfacial film number. The screening method provided by the application has low experimental cost and is suitable for screening of large-scale samples.

Description

A method for screening oil displacement systems based on monomolecular membrane characterization and its application Technical Field

[0001] This invention belongs to the technical field of oil displacement system screening methods, and relates to a screening and evaluation method for oil displacement systems suitable for improving oil recovery in the field of oil production, and to an oil displacement system screening method based on monomolecular membrane characterization and its application. Background Technology

[0002] Surfactant flooding is an important means of improving oil recovery in the tertiary oil recovery stage. Surfactants used in oil displacement adsorb at the oil-water interface, reducing the interfacial tension between the displacing phase and crude oil, enhancing the interaction between the two phases, making the remaining crude oil in the reservoir easier to move and deform, and then emulsifying it into oil droplets dispersed in the displacing phase under external force, thus improving oil washing efficiency. Simultaneously, the collision between emulsion droplets in the displacing phase and the Jamin effect of droplets in rock pores increase the migration resistance of the displacing phase, effectively regulating the oil-water mobility ratio, playing a profile control role, increasing the sweep capacity of the displacing phase, and further improving the recovery rate. Both indoor and field experiments have shown that the emulsification effect of surfactants on crude oil is highly beneficial to improving oil displacement (Bryan J, Kantzas A. Journal of Canadian Petroleum Technology, 2009, 48(02):37-46.). Among them, the monomolecular adsorption layer formed by surfactants at the oil-water interface is a prerequisite for the formation of emulsions, and the chemical composition and mechanical properties of the monomolecular adsorption layer determine the interaction between emulsion droplets and their deformation and migration in the core pores, thus playing a decisive role in the displacement effect.

[0003] Screening of oil displacement systems is a key step in the development of enhanced oil recovery (EOR) technologies. Currently, methods for screening oil displacement systems mainly include: core flooding experiments and visual model flow methods. For core flooding experiments, CN105403557A and Zhang Xiaoran et al. (Oilfield Chemistry, 2017, 34(02):312-317) typically use cores larger than 30cm, saturated with water and oil, followed by water flooding + 0.3PV composite slug + 0.2PV polymer-protected slug + subsequent water flooding, recording pressure, water cut, and recovery rate during the oil displacement process. This method can comprehensively evaluate the impact of almost all factors, including the emulsification and flow capacity of the oil displacement system, on enhanced oil recovery. However, core flooding experiments are costly, time-consuming, and complex, making large-scale sample screening difficult. The visualization model seepage method for screening oil displacement systems (Wang Fengqin et al., Petroleum Exploration and Development, 2006(02):221-224) utilizes a visualization model with a pore throat structure similar to that of a core sample to observe the morphology of emulsion seepage and the distribution of oil and water within the model, providing intuitive visual results. This method offers an intuitive explanation for the study of emulsion seepage through pore throats, the displacement and distribution of residual oil, and other related issues. However, the structure and size of the pore throat still differ somewhat from those of the actual porous media in the formation, and the size and structure of the pores have a significant impact on the displacement effect. In addition, due to limitations in processing technology and materials, the size of the visualization model is often small, and the scale effect results in low differentiation of the oil displacement effect of different systems, leading to poor screening of oil displacement systems.

[0004] It is evident that the commonly used methods for screening oil displacement systems often suffer from problems such as complex operation, long experimental cycle, high cost, and low distinguishability of oil displacement effects between different systems. In addition, the commonly used screening methods cannot infer the mechanism of action of the displacement agent at the molecular level, making it difficult to guide the optimal design of oil displacement systems.

[0005] Therefore, in this field, there is a desire to develop a method for screening oil displacement systems to avoid the problems existing in the prior art. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for screening oil displacement systems based on monomolecular film characterization and its application. This invention integrates multiple properties such as interfacial tension, interfacial film strength (maximum elastic modulus of the interfacial film), and interfacial viscoelasticity to obtain interfacial parameters closely related to the displacement effect. This solves the problem that current indoor evaluation experiments are hampered by overly complex influencing factors, making it difficult to effectively screen oil displacement systems. Furthermore, this method has low experimental costs, is suitable for screening large-scale samples, and is beneficial for understanding the relationship between the molecular structure of the displacement agent and the oil displacement effect, thereby guiding the design of oil displacement agent molecules.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for screening oil displacement systems based on monolayer characterization, the method comprising the following steps:

[0009] (1) Interfacial tension test: Prepare an aqueous solution of the oil displacement agent and measure the interfacial tension between the aqueous solution of the oil displacement agent and crude oil or simulated oil.

[0010] (2) Langmuir monomolecular membrane test: Prepare an oil displacement agent organic solvent solution and drop it onto the surface of the water tank of the Langmuir membrane analyzer. After the organic solvent evaporates, the Langmuir monomolecular membrane experiment (Journal of Atmospheric and Environmental Optics, 2022, 17(01): 171-184) is used to determine the change of surface tension with the average molecular area, obtain the π-A isotherm, and obtain the maximum elastic modulus of the interface membrane;

[0011] (3) Interfacial expansion rheological test: Prepare an aqueous solution of the oil displacement agent and determine the interfacial expansion rheological phase angle between the aqueous solution of the oil displacement agent and crude oil or simulated oil.

[0012] (4) Based on the parameters obtained from interfacial tension testing, Langmuir monolayer experiments, and interfacial expansion rheological experiments, and combining interfacial tension, the maximum elastic modulus of the interfacial film, and the interfacial expansion rheological phase angle, the interfacial film number Φ is proposed: Φ = f(E0, tanθ, γ), specifically as follows:

[0013] Where E0 is the maximum elastic modulus of the interfacial film; θ is the interfacial expansion rheological phase angle; and γ is the interfacial tension.

[0014] (5) The oil displacement agent was used in the oil displacement experiment to obtain the enhanced oil recovery rate (EOR). The relationship between the number of interfacial films (Φ) and the enhanced oil recovery rate (EOR) was obtained by fitting several sets of experiments. The oil displacement system can be screened by the size of the number of interfacial films.

[0015] Surfactant flooding is essentially an interfacial process. This invention, starting from the adsorption layer at the interface of the oil displacement system, provides a method for screening oil displacement systems based on specific interfacial parameters. This method can solve the problem that current indoor evaluation experiments are too complex, making it difficult to effectively screen oil displacement systems. In addition, screening oil displacement systems based on interfacial parameters has low experimental cost and is suitable for screening large-scale samples. It is of great value for more efficient screening of binary and ternary composite oil displacement systems with strong enhanced oil recovery capabilities. At the same time, it is helpful for understanding the relationship between the molecular structure of the displacement agent and the oil displacement effect, and can then be used to guide the design of displacement agent molecules.

[0016] Preferably, the interfacial tension in step (1) is obtained by testing with a rotating drop interfacial tension meter. For example, the test can be performed by referring to the Chinese Journal of Physical Chemistry, 2009, 25(1): 41-46.

[0017] Preferably, the interfacial expansion rheological phase angle in step (3) is obtained by droplet shape analysis. This can be verified by referring to the Journal of Tianjin University of Technology, 2023, 42(02): 34-41.

[0018] Preferably, step (3) specifically includes the following steps: preparing an aqueous solution of the oil displacement agent; determining the interfacial expansion rheological properties between the aqueous solution of the oil displacement agent and crude oil or simulated oil using droplet shape analysis, that is, after the oil droplets are formed, subjecting the oil droplets to sinusoidal periodic perturbation at a certain working frequency; obtaining the interfacial expansion rheological phase angle θ based on the phase difference between the interfacial tension sinusoidal periodic curve and the interfacial area sinusoidal periodic curve, as shown in Figure 1. The tangent of the phase angle is the ratio of the interfacial expansion viscous modulus to the interfacial expansion elastic modulus, which can be used to characterize the viscoelasticity of the interfacial film.

[0019] Preferably, the certain operating frequency is 0.1-0.2Hz, such as 0.1Hz, 0.15Hz, 0.2Hz, etc.

[0020] Preferably, the oil displacement agent in the aqueous solution of the oil displacement agent in steps (1) and (3) and the oil displacement agent organic solvent solution in step (2) includes any one or a combination of at least two of sweet 1-B18, sweet 3-B26PS, anionic non-B26PS, secondary alkylbenzene sulfonate, petroleum sulfonate, AEO9, sodium dodecyl sulfate, and sodium dodecylbenzene sulfonate.

[0021] Preferably, the oil displacement experiment in step (5) includes a core oil displacement experiment.

[0022] Preferably, the number of groups in step (5) is at least 5 groups, such as 5 groups, 6 groups, 7 groups, 8 groups, 9 groups, 10 groups, etc.

[0023] Preferably, the relationship between the number of interfacial films Φ obtained by fitting in step (5) and the enhanced oil recovery rate (EOR) is as follows:

[0024]

[0025] In other words, there is a linear one-to-one correspondence between the number of interfacial films Φ and the enhanced oil recovery (EOR), which can be used as a comprehensive parameter to characterize the interfacial properties of oil displacement chemical agents. The size of the interfacial film number can be used to screen oil displacement systems. The lower the interfacial tension, the higher the interfacial film strength (maximum elastic modulus of the interfacial film), and the better the interfacial viscoelasticity, the larger the value of Φ, and the better the displacement effect of the oil displacement system.

[0026] Preferably, in step (5), when the number of interfacial films reaches 200, the oil displacement system is determined to have a good oil displacement effect.

[0027] The screening method provided by this invention integrates three testing methods: interfacial tension testing, Langmuir monolayer experiments, and interfacial expansion rheological experiments. These methods yield key parameters such as ultra-low interfacial tension, interfacial limiting elastic modulus (maximum elastic modulus of the interfacial film), and interfacial viscoelasticity, characterizing the mechanical properties of the chemical agent adsorption layer from different perspectives. Specifically, ultra-low interfacial tension is closely related to the emulsification and oil film stripping of crude oil by the chemical agent, further affecting the oil washing effect. The interfacial limiting elastic modulus characterizes the interfacial film strength, while the interfacial viscoelastic parameters involve various relaxation processes at the interface. Both are closely related to the deformation of emulsion droplets and their interaction with rock pore throats, further affecting the swept volume. Based on the combined properties of these three interfaces, an interfacial film number is proposed for screening the chemical agent displacement effect.

[0028] Figure 2 shows a schematic flowchart of the oil displacement system screening method based on monomolecular membrane characterization provided by the present invention.

[0029] Secondly, this invention provides an application of the oil displacement system screening method based on monolayer characterization as described in the first aspect in the screening of oil displacement systems.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) This invention proposes a screening method for oil displacement systems based on the relationship between key interface parameters of the oil displacement agent monomolecular film and the displacement effect. During the screening process, the interface composition and mechanical properties of the monomolecular film of different oil displacement systems can be clarified. The number of interface films Φ is proposed by combining the key parameters of different interface testing methods. Essentially, it is a screening scheme based on the micro-interface action mechanism of the oil displacement agent, which facilitates the optimization design of the oil displacement system at the molecular level.

[0032] (2) Compared with existing core flooding experiments and visualization model seepage methods for screening flooding systems, the screening method provided by this invention is free from the influence of injection and production process parameters and size effects. It uses only key interface parameters (interface film number Φ) as indicators to screen flooding systems, avoiding complex displacement operations, shortening the research and development cycle, reducing research and development costs, and is more suitable for large-scale sample screening. Attached Figure Description

[0033] Figure 1 shows the sinusoidal periodic curves of interfacial area and interfacial tension in the interfacial expansion rheological experiment.

[0034] Figure 2 is a schematic diagram of the screening method for oil displacement systems based on monomolecular membrane characterization provided by the present invention.

[0035] Figure 3 shows the relationship between the number of interfacial films and the enhanced oil recovery rate. Detailed Implementation

[0036] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0037] Example 1

[0038] This embodiment provides a method for screening oil displacement systems based on monolayer characterization, the method comprising the following steps:

[0039] (1) Prepare a 0.2% (w / w) aqueous solution of sweet 1-B18. Use a rotating drop interfacial tension meter, set the test temperature to 50℃ and the rotation speed to 5000 r / min, and determine the interfacial tension between the oil displacement agent aqueous solution and crude oil to be 0.012 mN / m.

[0040] (2) Prepare a 0.1% (w / w) solution of sweet 1-B18 organic solvent (wherein, the organic solvent is chloroform), and drop it onto the surface of the water tank of the Langmuir membrane analyzer. After the organic solvent evaporates, the maximum elastic modulus of the interfacial membrane is determined to be 67.53 mN / m using the Langmuir monomolecular membrane experiment.

[0041] (3) Prepare a 0.2% (w / w) sweet 1-B18 aqueous solution. Use an interfacial expansion rheological experiment to perform sinusoidal periodic expansion and compression of the droplet at a working frequency of 0.1 Hz. Based on the phase difference between the interfacial tension sinusoidal periodic curve and the interfacial area sinusoidal periodic curve, the phase angle is 1.2°.

[0042] (4) Combining the above parameters, use the formula Φ=E0·(tanθ) 0.90 / γ 1.12 The calculated number of interfacial films was 294.87, and the enhanced oil recovery rate was measured to be 13.5% in the core flooding experiment.

[0043] Example 2

[0044] This embodiment provides a method for screening oil displacement systems based on monolayer characterization, the method comprising the following steps:

[0045] (1) Prepare a 0.2% (w / w) sweet 3-B26PS aqueous solution; use a rotating drop interfacial tensiometer, set the test temperature to 50℃ and the rotation speed to 5000 r / min, and determine the interfacial tension between the oil displacement agent aqueous solution and crude oil to be 0.0025 mN / m;

[0046] (2) Prepare a 0.2% (w / w) solution of sweet 3-B26PS organic solvent (wherein, the organic solvent is chloroform), and drop it onto the surface of the water tank of the Langmuir membrane analyzer. After the organic solvent evaporates, the maximum elastic modulus of the interfacial membrane is determined to be 42.70 mN / m using the Langmuir monomolecular membrane experiment.

[0047] (3) Prepare a 0.2% sweet 3-B26PS aqueous solution. Use an interfacial expansion rheological experiment to perform sinusoidal periodic expansion and compression of the droplet at a working frequency of 0.1 Hz. Based on the phase difference between the interfacial tension sinusoidal periodic curve and the interfacial area sinusoidal periodic curve, the phase angle is 1.5°.

[0048] (4) Combining the above parameters, use the formula Φ=E0·(tanθ) 0.90 / γ 1.12 The calculated number of interfacial films was 1320.68, and the enhanced oil recovery rate measured by the core flooding experiment was 19.5%.

[0049] Example 3

[0050] This embodiment provides a method for screening oil displacement systems based on monolayer characterization, the method comprising the following steps:

[0051] (1) Prepare an aqueous solution of anion-non-B26PS with a mass concentration of 0.2%; use a rotating drop interfacial tensiometer, set the test temperature to 50℃ and the rotation speed to 5000r / min, and determine the interfacial tension between the oil displacement agent aqueous solution and crude oil to be 0.025mN / m;

[0052] (2) Prepare a 0.1% (w / w) solution of anion-non-B26PS organic solvent (chloroform is the organic solvent), drop it onto the surface of the water tank of the Langmuir membrane analyzer, and after the organic solvent evaporates, determine the maximum elastic modulus of the interfacial membrane to be 32.07 mN / m using the Langmuir monomolecular membrane experiment.

[0053] (3) Prepare an aqueous solution of anion-non-B26PS with a mass concentration of 0.2%. Use an interfacial expansion rheological experiment to perform sinusoidal periodic expansion and compression of the droplet at a working frequency of 0.1 Hz. Based on the phase difference between the interfacial tension sinusoidal periodic curve and the interfacial area sinusoidal periodic curve, the phase angle is 11.7°.

[0054] (4) Combining the above parameters, use the formula Φ=E0·(tanθ) 0.90 / γ 1.12 The calculated number of interfacial films was 483.89, and the enhanced oil recovery rate measured by the core flooding experiment was 15.5%.

[0055] Example 4

[0056] This embodiment provides a method for screening oil displacement systems based on monolayer characterization, the method comprising the following steps:

[0057] (1) Prepare a C solution with a mass concentration of 0.2%. 18 Sodium alkylbenzene sulfonate aqueous solution; using a rotating drop interfacial tensiometer, with the test temperature set at 50℃ and the rotation speed at 5000 r / min, the interfacial tension between the oil displacement agent aqueous solution and crude oil was determined to be 0.053 mN / m;

[0058] (2) Prepare a C solution with a mass concentration of 0.1%. 18 Sodium alkylbenzene sulfonate in organic solvent (chloroform) was added dropwise to the surface of the water tank of the Langmuir membrane analyzer. After the organic solvent evaporated, the maximum elastic modulus of the interfacial membrane was determined to be 20.23 mN / m using the Langmuir monomolecular membrane experiment.

[0059] (3) Prepare a C solution with a mass concentration of 0.2%. 18 Sodium alkylbenzene sulfonate aqueous solution was subjected to interfacial expansion rheological experiments. The droplets were sinusoidally expanded and compressed at a working frequency of 0.1 Hz. The phase angle was 15.8° based on the phase difference between the interfacial tension sinusoidal periodic curve and the interfacial area sinusoidal periodic curve.

[0060] (4) Combining the above parameters, use the formula Φ=E0·(tanθ) 0.90 / γ 1.12 The calculated number of interfacial films was 174.25, and the enhanced oil recovery rate was measured to be 9.8% in the core flooding experiment.

[0061] Example 5

[0062] This embodiment provides a method for screening oil displacement systems based on monolayer characterization, the method comprising the following steps:

[0063] (1) Prepare a C solution with a mass concentration of 0.2%. 16-18 Aqueous solution of sodium petroleum sulfonate; using a rotating drop interfacial tensiometer, with the test temperature set at 50℃ and the rotation speed at 5000 r / min, the interfacial tension between the oil displacement agent aqueous solution and crude oil was determined to be 0.024 mN / m;

[0064] (2) Prepare a C solution with a mass concentration of 0.1%. 16-18 A sodium petroleum sulfonate organic solvent solution (of which the organic solvent is chloroform) was dropped onto the surface of the water tank of the Langmuir membrane analyzer. After the organic solvent evaporated, the maximum elastic modulus of the interfacial membrane was determined to be 70.65 mN / m using the Langmuir monomolecular membrane experiment.

[0065] (3) Prepare a C solution with a mass concentration of 0.2%. 16-18 Aqueous sodium petroleum sulfonate was subjected to an interfacial expansion rheological experiment. The droplets were subjected to sinusoidal periodic expansion and compression at a working frequency of 0.1 Hz. The phase angle was 1.1° based on the phase difference between the interfacial tension sinusoidal periodic curve and the interfacial area sinusoidal periodic curve.

[0066] (4) Combining the above parameters, use the formula Φ=E0·(tanθ) 0.90 / γ 1.12 The calculated number of interfacial films was 131.24, and the enhanced oil recovery rate was measured to be 6.5% in the core flooding experiment.

[0067] Example 6

[0068] This embodiment provides a method for screening oil displacement systems based on monolayer characterization, the method comprising the following steps:

[0069] (1) Prepare an AEO9 aqueous solution with a mass concentration of 0.3%; use a rotating drop interfacial tension meter, set the test temperature to 50℃ and the rotation speed to 5000r / min, and determine the interfacial tension between the oil displacement agent aqueous solution and crude oil to be 0.031mN / m;

[0070] (2) Prepare an AEO9 organic solvent solution with a mass concentration of 0.1% (wherein, the organic solvent is chloroform), drop it onto the surface of the water tank of the Langmuir membrane analyzer, and after the organic solvent evaporates, determine the maximum elastic modulus of the interfacial membrane to be 38.95 mN / m using the Langmuir monomolecular membrane experiment.

[0071] (3) Prepare an AEO9 aqueous solution with a mass concentration of 0.3%. Use an interfacial expansion rheological experiment to perform sinusoidal periodic expansion and compression of the droplet at a working frequency of 0.1 Hz. Based on the phase difference between the interfacial tension sinusoidal periodic curve and the interfacial area sinusoidal periodic curve, the phase angle is 3.2°.

[0072] (4) Combining the above parameters, use the formula Φ=E0·(tanθ) 0.90 / γ 1.12 The calculated number of interfacial films was 142.14, and the enhanced oil recovery rate was measured to be 7.1% in the core flooding experiment.

[0073] Example 7

[0074] This embodiment provides a method for screening oil displacement systems based on monolayer characterization, the method comprising the following steps:

[0075] (1) Prepare a sodium dodecyl sulfate aqueous solution with a mass concentration of 0.3%; use a rotating drop interfacial tension meter, set the test temperature to 50℃ and the rotation speed to 5000r / min, and determine the interfacial tension between the oil displacement agent aqueous solution and crude oil to be 0.083mN / m;

[0076] (2) Prepare a sodium dodecyl sulfate organic solvent solution with a mass concentration of 0.1% (wherein, the organic solvent is chloroform), and drop it onto the surface of the water tank of the Langmuir membrane analyzer. After the organic solvent evaporates, the maximum elastic modulus of the interfacial membrane is determined to be 25.75 mN / m using the Langmuir monomolecular membrane experiment.

[0077] (3) Prepare a sodium dodecyl sulfate aqueous solution with a mass concentration of 0.3%. Use an interfacial expansion rheological experiment to perform sinusoidal periodic expansion and compression of the droplet at a working frequency of 0.1 Hz. Based on the phase difference between the interfacial tension sinusoidal periodic curve and the interfacial area sinusoidal periodic curve, the phase angle is 12.6°.

[0078] (4) Combining the above parameters, use the formula Φ=E0·(tanθ) 0.90 / γ 1.12 The calculated number of interfacial films was 108.54, and the enhanced oil recovery rate was measured to be 4.5% in the core flooding experiment.

[0079] Example 8

[0080] This embodiment provides a method for screening oil displacement systems based on monolayer characterization, the method comprising the following steps:

[0081] (1) Prepare a sodium dodecylbenzenesulfonate aqueous solution with a mass concentration of 0.2%; use a rotating drop interfacial tension meter, set the test temperature to 50℃ and the rotation speed to 5000r / min, and determine the interfacial tension between the oil displacement agent aqueous solution and crude oil to be 0.052mN / m;

[0082] (2) Prepare a sodium dodecylbenzenesulfonate organic solvent solution with a mass concentration of 0.1% (wherein, the organic solvent is chloroform), and drop it onto the surface of the water tank of the Langmuir membrane analyzer. After the organic solvent evaporates, the maximum elastic modulus of the interfacial membrane is determined to be 16.25 mN / m using the Langmuir monomolecular membrane experiment.

[0083] (3) Prepare a sodium dodecylbenzenesulfonate aqueous solution with a mass concentration of 0.2%. Use an interfacial expansion rheological experiment to perform sinusoidal periodic expansion and compression of the droplet at a working frequency of 0.1 Hz. Based on the phase difference between the interfacial tension sinusoidal periodic curve and the interfacial area sinusoidal periodic curve, the phase angle is 7.5°.

[0084] (4) Combining the above parameters, use the formula Φ=E0·(tanθ)0.90 / γ 1.12 The calculated number of interfacial films was 71.82, and the enhanced oil recovery rate measured by the core flooding experiment was 2.0%.

[0085] The interface properties, interfacial film number, and enhanced oil recovery (EOR) of the above embodiments are shown in Table 1, and the relationship between interfacial film number and EOR is illustrated in Figure 3. It can be seen that the higher the interfacial film number, the higher the EOR. When the interfacial film number is below 200, the EOR increases rapidly with the interfacial film number; however, when the interfacial film number reaches 200, the EOR is approximately 13%; further increases in the interfacial film number result in a slow increase in EOR. Based on this, an interfacial film number of 200 is used as the standard for evaluating the oil displacement effect of chemical agents, and systems with an interfacial film number of 200 can produce good oil displacement effects. This result indicates that the comprehensive parameter of interfacial film number, proposed by considering multiple interfacial characteristics, can be used to guide the screening of chemical agents.

[0086] Table 1

[0087]

[0088] The applicant declares that the present invention illustrates the method for screening oil displacement systems based on monomolecular membrane characterization and its application through the above embodiments. However, the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for screening oil displacement systems based on monomolecular membrane characterization, characterized in that, The oil displacement system screening method includes the following steps: (1) preparing an aqueous solution of the oil displacement agent and measuring the interfacial tension between the aqueous solution of the oil displacement agent and crude oil or simulated oil; (2) preparing an organic solvent solution of the oil displacement agent, adding it dropwise to the surface of the water tank of the Langmuir membrane analyzer, and after the organic solvent evaporates, using the Langmuir monomolecular membrane experiment to measure the change in surface tension with the area occupied by the average molecule, obtaining the π-A isotherm, and obtaining the maximum elastic modulus of the interfacial membrane; (3) preparing an aqueous solution of the oil displacement agent and measuring the interfacial expansion rheological phase angle between the aqueous solution of the oil displacement agent and crude oil or simulated oil; (4) combining the interfacial tension, the maximum elastic modulus of the interfacial membrane, and the interfacial expansion rheological phase angle, proposing the number of interfacial membranes Φ: Specifically ;in, This represents the maximum elastic modulus of the interface film. The phase angle of the interface expansion rheometry; (5) The oil displacement agent was used in the oil displacement experiment to obtain the enhanced oil recovery rate (EOR). The relationship between the number of interfacial films (Φ) and the enhanced oil recovery rate (EOR) was obtained by fitting several sets of experiments. The oil displacement system can be screened by the size of the number of interfacial films.

2. The method for screening oil displacement systems based on monomolecular membrane characterization according to claim 1, characterized in that, The interfacial tension mentioned in step (1) is obtained by testing with a rotating drop interfacial tension meter.

3. The method for screening oil displacement systems based on monomolecular membrane characterization according to claim 1, characterized in that, The interface expansion rheological phase angle mentioned in step (3) is obtained by droplet shape analysis.

4. The method for screening oil displacement systems based on monomolecular membrane characterization according to claim 3, characterized in that, Step (3) specifically includes the following steps: preparing an aqueous solution of the oil displacement agent; using droplet shape analysis to determine the interfacial expansion rheological properties between the aqueous solution of the oil displacement agent and crude oil or simulated oil, that is, after the oil droplet is formed, the oil droplet is subjected to sinusoidal periodic perturbation at a certain working frequency; and obtaining the interfacial expansion rheological phase angle based on the phase difference between the interfacial tension sinusoidal periodic curve and the interfacial area sinusoidal periodic curve.

5. The method for screening oil displacement systems based on monomolecular membrane characterization according to claim 4, characterized in that, The specified operating frequency is 0.1-0.2 Hz.

6. The method for screening oil displacement systems based on monomolecular membrane characterization according to claim 1, characterized in that, The oil displacement agent in the aqueous solution of the oil displacement agent in steps (1) and (3) and the oil displacement agent organic solvent solution in step (2) includes any one or a combination of at least two of sweet 1-B18, sweet 3-B26PS, anionic non-B26PS, secondary alkylbenzene sulfonate, petroleum sulfonate, AEO9, sodium dodecyl sulfate, and sodium dodecylbenzene sulfonate.

7. The method for screening oil displacement systems based on monomolecular film characterization according to claim 1, characterized in that, The oil displacement experiment described in step (5) includes core oil displacement experiment.

8. The method for screening oil displacement systems based on monomolecular membrane characterization according to claim 1, characterized in that, The number of groups mentioned in step (5) is at least 5 groups.

9. The method for screening oil displacement systems based on monomolecular membrane characterization according to claim 1, characterized in that, The relationship between the number of interfacial films Φ obtained from the fitting in step (5) and the enhanced oil recovery rate (EOR) is as follows: 。 10. The method for screening oil displacement systems based on monomolecular membrane characterization according to claim 1, characterized in that, When the number of interfacial films reaches 200, the oil displacement system is judged to have a good oil displacement effect.

11. The application of the oil displacement system screening method based on monomolecular membrane characterization as described in any one of claims 1-10 in the screening of oil displacement systems.

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