Oil displacement system screening method based on monomolecular film characterization and application thereof

Abstract

The invention provides an oil displacement system screening method based on monomolecular film characterization and application thereof, the screening method comprises the following steps: (1) preparing an oil displacement agent aqueous solution, and measuring interfacial tension between the oil displacement agent aqueous solution and crude oil or simulated oil; (2) preparing an oil-displacing agent organic solvent solution, and determining the maximum elastic modulus of an interfacial film by adopting a Langmuir monomolecular film experiment; (3) preparing an oil-displacing agent aqueous solution, and measuring an interface expansion rheological phase angle between the oil-displacing agent aqueous solution and the crude oil or the simulated oil; (4) combining the interfacial tension, the maximum elasticity modulus of the interfacial film and the interfacial expansion rheological phase angle, and proposing the number phi of the interfacial film; and (5) applying the oil-displacing agent to an oil-displacing experiment to obtain the enhanced recovery ratio EOR, fitting to obtain a relational expression between the interfacial film number phi and the enhanced recovery ratio EOR, and screening the oil-displacing system according to the size of the interfacial film number. The screening method provided by the invention has relatively low experimental cost and is suitable for screening large-scale samples.

Description

Technical Field

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

[0002] Surfactant flooding is an important means to improve oil recovery in the tertiary oil recovery stage. The adsorption of surfactants used for oil recovery at the oil-water interface can reduce the interfacial tension between the displacement phase and crude oil, enhance the interaction between the oil and water phases, make the remaining crude oil in the reservoir easy to move and deform, and then emulsify into oil droplets dispersed in the displacement phase under the action of external forces, thereby improving the oil washing efficiency. At the same time, the collision between the emulsified droplets in the displacement phase and the Jamin effect of the droplets in the rock pores will increase the migration resistance of the displacement phase, effectively adjust the mobility ratio of the oil-water two-phase, play a role in profile adjustment, increase the swept system of the displacement phase, and further improve the recovery rate. Both indoor experiments and field experiments have shown that the emulsification of crude oil by surfactants is very beneficial to improving the oil recovery effect (Bryan J, Kantzas A. Journal of Canadian Petroleum Technology, 2009, 48 (02): 37-46.). Among them, the monomolecular adsorption layer formed by the surfactant at the oil-water interface is the prerequisite for the formation of emulsion, and the chemical composition and mechanical properties of the monomolecular adsorption layer determine the interaction between the emulsion droplets and their deformation and migration in the core pores, thus playing a decisive role in the displacement effect.

[0003] The screening of oil displacement systems is a key link in the development of enhanced oil recovery technology. At present, the methods for screening oil displacement systems mainly include: core flooding experimental method for screening oil displacement system technology, visual model seepage method for screening oil displacement system technology, etc. For the core flooding experimental method for screening oil displacement system technology, CN105403557A, Zhang Xiaoran et al. (Oilfield Chemistry, 2017, 34(02): 312-317) usually use cores larger than 30 cm, saturated with water and oil, and then perform water flooding + 0.3PV composite system slug + 0.2PV polymer protection slug + subsequent water flooding, and record the pressure, water content and recovery rate during the oil flooding process. This method can comprehensively evaluate the impact of almost all factors, including the emulsification seepage capacity of the oil displacement system, on the enhanced oil recovery. However, core flooding experiments are costly, long-term, and complex to operate, making it difficult to carry out large-scale sample screening. The technology of screening oil displacement system by visual model seepage method (Wang Fengqin et al. Petroleum Exploration and Development, 2006(02):221-224) uses a visual model with a core pore throat structure to observe the morphology of emulsion seepage in the model and the distribution of oil and water and other intuitive visual results. This method has an intuitive explanation for the study of the process of emulsion passing through the pore throat, the displacement and distribution of residual oil, etc. However, the structure and size of the pore throat are still somewhat different from those of the real formation porous media. The pore size and structure have a significant impact on the displacement effect; in addition, due to the limitations of processing technology and processing materials, the size of the visual model is often small. Affected by the scale effect, the oil displacement effect of different systems is low, and the screening effect of the oil displacement system is not good.

[0004] It can be seen that the currently commonly used oil recovery system screening methods often have problems such as complex operation, long experimental cycle, high cost, and low differentiation of oil recovery effects of different systems; in addition, the currently commonly used screening methods cannot infer the mechanism of action of the displacement agent at the molecular level, and are difficult to use to guide the optimal design of the oil recovery system.

[0005] Therefore, in the art, it is desired to develop an oil displacement system screening method to avoid the problems existing in the prior art. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for screening oil displacement systems based on monomolecular film characterization and its application. The present invention integrates multiple properties such as interfacial tension, interfacial film strength (interfacial film maximum elastic modulus), and interfacial viscoelasticity to obtain interface parameters closely related to displacement effect, solving the problem that the influencing factors of the current indoor evaluation experiment are too complex to effectively screen the oil displacement system; at the same time, this method has a low experimental cost, is suitable for the screening of large-scale samples, and is beneficial to understand the relationship between the molecular structure of the displacement agent and the oil displacement effect, and then used to guide the molecular design of the oil displacement agent.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

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

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

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

[0011] (3) Interface dilation rheological test: Prepare an oil displacement agent aqueous solution and measure the interface dilation rheological phase angle between the oil displacement agent aqueous solution and crude oil or simulated oil;

[0012] (4) Based on the parameters obtained from the interfacial tension test, Langmuir monolayer experimental test and interfacial dilational rheological test, the interfacial tension, the maximum elastic modulus of the interfacial film and the interfacial dilational rheological phase angle are comprehensively considered, and the interfacial film number Φ is proposed: Φ = f(E0, tanθ, γ), which is specifically:

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

[0014] (5) The oil displacement agent is used in oil displacement experiments to obtain the enhanced oil recovery (EOR). Through several groups of experimental fitting, the relationship between the interface film number Φ and the enhanced oil recovery (EOR) is obtained. The oil displacement system can be screened according to the size of the interface film number.

[0015] Surfactant flooding is essentially an interfacial action process. Starting from the interface adsorption layer of the oil displacement system, the present invention provides a method for screening the oil displacement system based on specific interface parameters, which can solve the problem that the influencing factors of the current indoor evaluation experiments are too complex, making it difficult to effectively screen the oil displacement system; in addition, the experiment of screening the oil displacement system based on interface parameters has low cost and is suitable for screening large-scale samples. It is of great value for more efficiently screening binary and ternary composite oil displacement systems with strong ability to improve oil recovery, and is also helpful for understanding the relationship between the molecular structure of the displacement agent and the oil displacement effect, and then used to guide the molecular design of the oil displacement agent.

[0016] Preferably, the interfacial tension in step (1) is measured by a spinning drop interfacial tension meter. For example, the test can be performed with reference to Acta Physico-Chimica Sinica, 2009, 25(1): 41-46).

[0017] Preferably, the interfacial dilation rheological phase angle in step (3) is obtained by droplet shape analysis. The test can be performed with reference to Journal of Tianjin Polytechnic University, 2023, 42(02): 34-41.

[0018] Preferably, step (3) specifically includes the following steps: preparing an oil-displacing agent aqueous solution; determining the interfacial expansion rheological properties between the oil-displacing agent aqueous solution and crude oil or simulated oil by using a droplet shape analysis method, that is, after the oil droplets are formed, the oil droplets are subjected to a sinusoidal periodic disturbance at a certain operating frequency; obtaining an 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, such as Figure 1 The phase tangent is the ratio of the interfacial dilational viscous modulus to the interfacial dilational elastic modulus, and can be used to characterize the viscoelasticity of the interfacial film.

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

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

[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, for example, 5 groups, 6 groups, 7 groups, 8 groups, 9 groups, 10 groups, etc.

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

[0024]

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

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

[0027] The screening method provided by the present invention integrates three test methods, namely, interfacial tension test, Langmuir monomolecular film experiment and interfacial expansion rheology experiment, to obtain key parameters such as ultra-low interfacial tension, interface ultimate elastic modulus (maximum elastic modulus of interfacial film), and interfacial viscoelasticity, respectively, and characterizes the mechanical properties of the chemical adsorption layer from different angles. Among them, ultra-low interfacial tension is closely related to the emulsification and oil film stripping of crude oil by chemicals, and is further related to the oil washing effect; the interface ultimate elastic modulus can characterize the interfacial film strength, and the interfacial viscoelastic parameters involve various relaxation processes of the interface. The two are closely related to the deformation of emulsion droplets and the interaction with rock pore throats, and are further related to the swept volume. The interfacial film number is proposed by combining the three interfacial properties for screening the chemical displacement effect.

[0028] The schematic diagram of the oil displacement system screening method based on monomolecular film characterization provided by the present invention is as follows: Figure 2 shown.

[0029] In a second aspect, the present invention provides an application of the oil displacement system screening method based on monomolecular film characterization as described in the first aspect in oil displacement system screening.

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

[0031] (1) The present invention proposes an oil displacement system screening method based on the relationship between the key interface parameters of the oil displacement agent monolayer and the displacement effect. During the screening process, the interface composition and mechanical properties of the monolayer of different oil displacement systems can be clarified. The interface film number Φ is proposed by combining the key parameters of different interface testing methods. In essence, it is a screening scheme based on the microscopic 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 the existing core flooding experiments and visualization model seepage method for screening oil recovery systems, the screening method provided by the present invention is free from the influence of injection and production process parameters and size effects, and only uses key interface parameters (interface film number Φ) as indicators for oil recovery system screening, avoiding complex displacement operations, shortening the R&D cycle, reducing R&D costs, and is more suitable for large-scale sample screening. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 These are the sinusoidal periodic curves of interface area and interface tension in the interface dilation rheology experiment.

[0034] Figure 2 A schematic flow chart of the method for screening an oil displacement system based on monomolecular film characterization provided by the present invention.

[0035] Figure 3 This is the relationship between the number of interface films and enhanced oil recovery. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0037] Example 1

[0038] In this embodiment, a method for screening an oil displacement system based on monomolecular film characterization is provided, and the method for screening an oil displacement system comprises the following steps:

[0039] (1) A 0.2% mass concentration of sweet 1-B18 aqueous solution was prepared, and the interfacial tension between the oil displacement agent aqueous solution and the crude oil was measured using a spinning drop interfacial tension meter at a test temperature of 50° C. and a rotation speed of 5000 r / min to be 0.012 mN / m;

[0040] (2) preparing a 0.1% mass concentration of sweet 1-B18 organic solvent solution (wherein the organic solvent is chloroform), dropping it onto the surface of the water tank of the Langmuir film analyzer, and after the organic solvent evaporates, using the Langmuir monomolecular film experiment to measure the maximum elastic modulus of the interfacial film to be 67.53 mN / m;

[0041] (3) A 0.2% mass concentration of sweet 1-B18 aqueous solution was prepared, and an interfacial dilation rheology experiment was performed to perform sinusoidal periodic expansion and compression of the droplet at an operating 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 was 1.2°;

[0042] (4) Combining the above parameters, using the formula Φ = E0 (tanθ) 0.90 / γ 1.12 The calculated interfacial film number is 294.87, and the core flooding experiment shows an enhanced oil recovery of 13.5%.

[0043] Example 2

[0044] In this embodiment, a method for screening an oil displacement system based on monomolecular film characterization is provided, and the method for screening an oil displacement system comprises the following steps:

[0045] (1) preparing a 0.2% mass concentration of sweet 3-B26PS aqueous solution; using a spinning drop interfacial tension meter, setting the test temperature to 50° C. and the rotation speed to 5000 r / min, the interfacial tension between the oil displacement agent aqueous solution and the crude oil was measured to be 0.0025 mN / m;

[0046] (2) preparing a 0.2% mass concentration of sweet 3-B26PS organic solvent solution (wherein the organic solvent is chloroform), dropping it onto the surface of the water tank of the Langmuir film analyzer, and after the organic solvent evaporates, using the Langmuir monomolecular film experiment to measure the maximum elastic modulus of the interfacial film to be 42.70 mN / m;

[0047] (3) A 0.2% mass concentration of sweet 3-B26PS aqueous solution was prepared, and an interfacial dilation rheology experiment was performed to perform sinusoidal periodic expansion and compression of the droplet at an operating 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 was 1.5°;

[0048] (4) Combining the above parameters, using the formula Φ = E0 (tanθ) 0.90 / γ 1.12 The calculated interfacial film number is 1320.68, and the core flooding experiment shows that the enhanced oil recovery is 19.5%.

[0049] Example 3

[0050] In this embodiment, a method for screening an oil displacement system based on monomolecular film characterization is provided, and the method for screening an oil displacement system comprises the following steps:

[0051] (1) preparing an aqueous solution of an anion-non-B26PS solution with a mass concentration of 0.2%; using a spinning drop interfacial tension meter, setting the test temperature to 50° C. and the rotation speed to 5000 r / min, the interfacial tension between the oil displacement agent aqueous solution and the crude oil was measured to be 0.025 mN / m;

[0052] (2) preparing an anion-non-B26PS organic solvent solution (wherein the organic solvent is chloroform) with a mass concentration of 0.1%, and dropping it onto the surface of the water tank of the Langmuir film analyzer. After the organic solvent evaporates, the maximum elastic modulus of the interfacial film is measured by the Langmuir monomolecular film experiment to be 32.07 mN / m;

[0053] (3) An aqueous solution of anionic non-B26PS with a mass concentration of 0.2% was prepared, and an interfacial dilation rheology experiment was performed to perform sinusoidal periodic expansion and compression of the droplet at an operating frequency of 0.1 Hz. The phase angle was obtained to be 11.7° based on the phase difference between the interfacial tension sinusoidal periodic curve and the interfacial area sinusoidal periodic curve;

[0054] (4) Combining the above parameters, using the formula Φ = E0 (tanθ) 0.90 / γ 1.12 The calculated interfacial film number is 483.89, and the core flooding experiment shows an enhanced oil recovery of 15.5%.

[0055] Example 4

[0056] In this embodiment, a method for screening an oil displacement system based on monomolecular film characterization is provided, and the method for screening an oil displacement system comprises the following steps:

[0057] (1) Prepare C with a mass concentration of 0.2% 18 Aqueous solution of sodium secondary alkylbenzene sulfonate; using a spinning drop interfacial tension meter, setting the test temperature to 50°C and the rotation speed to 5000r / min, the interfacial tension between the oil displacement agent aqueous solution and the crude oil was measured to be 0.053mN / m;

[0058] (2) Prepare C with a mass concentration of 0.1% 18 A solution of sodium secondary alkylbenzene sulfonate in an organic solvent (wherein the organic solvent is chloroform) is added dropwise to the surface of a water tank of a Langmuir film analyzer. After the organic solvent evaporates, the maximum elastic modulus of the interfacial film is measured by a Langmuir monomolecular film experiment to be 20.23 mN / m.

[0059] (3) Prepare C with a mass concentration of 0.2% 18 For the aqueous solution of sodium secondary alkylbenzene sulfonate, the interfacial dilation rheology experiment was used to perform sinusoidal periodic expansion and compression of the droplet at an operating 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, using the formula Φ = E0 (tanθ) 0.90 / γ 1.12 The calculated interfacial film number is 174.25, and the core flooding experiment measured an enhanced oil recovery of 9.8%.

[0061] Example 5

[0062] In this embodiment, a method for screening an oil displacement system based on monomolecular film characterization is provided, and the method for screening an oil displacement system comprises the following steps:

[0063] (1) Prepare C with a mass concentration of 0.2% 16-18 Sodium petroleum sulfonate aqueous solution; using a spinning drop interfacial tension meter, set the test temperature to 50°C and the rotation speed to 5000r / min, the interfacial tension between the oil displacement agent aqueous solution and the crude oil was measured to be 0.024mN / m;

[0064] (2) Prepare C with a mass concentration of 0.1% 16-18 Sodium petroleum sulfonate organic solvent solution (wherein the organic solvent is chloroform) is added dropwise to the surface of the water tank of the Langmuir film analyzer. After the organic solvent evaporates, the maximum elastic modulus of the interface film is measured by Langmuir monomolecular film experiment to be 70.65 mN / m;

[0065] (3) Prepare C with a mass concentration of 0.2% 16-18 For the aqueous solution of sodium petroleum sulfonate, an interfacial dilation rheology experiment was used to perform sinusoidal periodic expansion and compression of the droplet at an operating 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 was 1.1°.

[0066] (4) Combining the above parameters, using the formula Φ = E0 (tanθ) 0.90 / γ 1.12 The calculated interfacial film number is 131.24, and the core flooding experiment measured an enhanced oil recovery of 6.5%.

[0067] Example 6

[0068] In this embodiment, a method for screening an oil displacement system based on monomolecular film characterization is provided, and the method for screening an oil displacement system comprises the following steps:

[0069] (1) A 0.3% AEO9 aqueous solution was prepared; a spinning drop interfacial tension meter was used, the test temperature was set to 50° C., the rotation speed was set to 5000 r / min, and the interfacial tension between the oil displacement agent aqueous solution and the crude oil was measured to be 0.031 mN / m;

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

[0071] (3) A 0.3% AEO9 aqueous solution was prepared, and an interfacial dilation rheology experiment was performed to perform sinusoidal periodic expansion and compression of the droplet at an operating frequency of 0.1 Hz. The phase angle was 3.2° based on the phase difference between the interfacial tension sinusoidal periodic curve and the interfacial area sinusoidal periodic curve.

[0072] (4) Combining the above parameters, using the formula Φ = E0 (tanθ) 0.90 / γ 1.12 The calculated interfacial film number is 142.14, and the core flooding experiment measured an enhanced oil recovery of 7.1%.

[0073] Example 7

[0074] In this embodiment, a method for screening an oil displacement system based on monomolecular film characterization is provided, and the method for screening an oil displacement system comprises the following steps:

[0075] (1) preparing a sodium dodecyl sulfate aqueous solution with a mass concentration of 0.3%; using a spinning drop interfacial tension meter, setting the test temperature to 50° C. and the rotation speed to 5000 r / min, the interfacial tension between the oil displacement agent aqueous solution and the crude oil was measured to be 0.083 mN / m;

[0076] (2) preparing a sodium dodecyl sulfate organic solvent solution (wherein the organic solvent is chloroform) with a mass concentration of 0.1%, dropping the solution onto the surface of a water tank of a Langmuir film analyzer, and after the organic solvent evaporates, using a Langmuir monolayer test to measure the maximum elastic modulus of the interfacial film to be 25.75 mN / m;

[0077] (3) preparing a sodium dodecyl sulfate aqueous solution with a mass concentration of 0.3%, and using an interfacial dilation rheology experiment to perform sinusoidal periodic expansion and compression on the droplet at an operating frequency of 0.1 Hz, the phase angle was obtained to be 12.6° based on the phase difference between the interfacial tension sinusoidal periodic curve and the interfacial area sinusoidal periodic curve;

[0078] (4) Combining the above parameters, using the formula Φ = E0 (tanθ) 0.90 / γ 1.12 The calculated interfacial film number is 108.54, and the core flooding experiment measured an enhanced oil recovery of 4.5%.

[0079] Example 8

[0080] In this embodiment, a method for screening an oil displacement system based on monomolecular film characterization is provided, and the method for screening an oil displacement system comprises the following steps:

[0081] (1) preparing a sodium dodecylbenzene sulfonate aqueous solution with a mass concentration of 0.2%; using a spinning drop interfacial tension meter, setting the test temperature to 50° C. and the rotation speed to 5000 r / min, the interfacial tension between the oil displacement agent aqueous solution and the crude oil was measured to be 0.052 mN / m;

[0082] (2) preparing a 0.1% sodium dodecylbenzene sulfonate organic solvent solution (wherein the organic solvent is chloroform), dropping the solution onto the surface of a water tank of a Langmuir film analyzer, and after the organic solvent evaporates, using a Langmuir monolayer test to measure the maximum elastic modulus of the interfacial film to be 16.25 mN / m;

[0083] (3) preparing a sodium dodecylbenzene sulfonate aqueous solution with a mass concentration of 0.2%, and using an interfacial expansion rheology experiment to perform sinusoidal periodic expansion and compression on the droplet at an operating frequency of 0.1 Hz, the phase angle was obtained to be 7.5° based on the phase difference between the interfacial tension sinusoidal periodic curve and the interfacial area sinusoidal periodic curve;

[0084] (4) Combining the above parameters, using the formula Φ = E0 (tanθ)0.90 / γ 1.12 The calculated interfacial film number is 71.82, and the core flooding experiment shows an enhanced oil recovery of 2.0%.

[0085] The interface properties, interface film number, and enhanced oil recovery of the above examples are shown in Table 1. The relationship between the interface film number and enhanced oil recovery is shown in Figure 3 . It can be seen that the larger the interface film number, the higher the enhanced oil recovery. When the interface film number is below 200, the recovery rate increases rapidly with the interface film number; when the interface film number reaches 200, the enhanced oil recovery rate is about 13%; the interface film number continues to increase, and the recovery rate increases slowly. Based on this, the interface film number of 200 is used as the standard for evaluating the oil recovery effect of chemical agents, and the system with an interface film number of 200 can produce a good oil recovery effect. The results show that the comprehensive parameter interface film number proposed by integrating various aspects of interface characteristics can be used to guide the screening of chemical agents.

[0086] Table 1

[0087]

[0088] The applicant declares that the present invention uses the above-mentioned embodiments to illustrate the oil displacement system screening method based on monomolecular film characterization and its application, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the raw materials selected by 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 film characterization, characterized in that: The oil displacement system screening method comprises the following steps: (1) preparing an oil displacing agent aqueous solution and measuring the interfacial tension between the oil displacing agent aqueous solution and crude oil or simulated oil; (2) preparing an organic solvent solution of an oil displacement agent, dripping it onto the surface of a water tank of a Langmuir film analyzer, and after the organic solvent evaporates, using a Langmuir monolayer test to measure the change in surface tension with the average molecular area, obtaining a π-A isotherm, and obtaining the maximum elastic modulus of the interfacial film; (3) preparing an oil-displacing agent aqueous solution and measuring the interfacial dilation rheological phase angle between the oil-displacing agent aqueous solution and crude oil or simulated oil; (4) Based on the 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), which is specifically: Where, E0 is the maximum elastic modulus of the interfacial film; θ is the interface expansion rheological phase angle; γ is the interfacial tension; (5) The oil displacement agent is used in oil displacement experiments to obtain the enhanced oil recovery (EOR). Through several groups of experimental fitting, the relationship between the interface film number Φ and the enhanced oil recovery (EOR) is obtained. The oil displacement system can be screened according to the size of the interface film number.

2. The method for screening oil displacement systems based on monomolecular film characterization according to claim 1, characterized in that: The interfacial tension in step (1) is measured using a spinning drop interfacial tension meter.

3. The method for screening an oil displacement system based on monomolecular film characterization according to claim 1 or 2, characterized in that: The interface expansion rheological phase angle in step (3) is obtained by testing using a droplet shape analysis method; Preferably, step (3) specifically includes the following steps: preparing an oil-displacing agent aqueous solution; determining the interfacial expansion rheological properties between the oil-displacing agent aqueous solution and crude oil or simulated oil by a droplet shape analysis method, that is, after the oil droplets are formed, the oil droplets are subjected to a sinusoidal periodic disturbance at a certain operating 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.

4. The method for screening oil displacement systems based on monomolecular film characterization according to claim 3, characterized in that: The certain operating frequency is 0.1-0.2 Hz.

5. The method for screening an oil displacement system based on monomolecular film characterization according to any one of claims 1 to 4, characterized in that: The oil-displacing agent in the oil-displacing agent aqueous solution in step (1) and step (3) and the oil-displacing agent in the oil-displacing agent organic solvent solution in step (2) includes any one of sweet 1-B18, sweet 3-B26PS, anion non-B26PS, secondary alkylbenzene sulfonate, petroleum sulfonate, AEO9, sodium dodecyl sulfate, and sodium dodecylbenzene sulfonate, or a combination of at least two thereof.

6. The method for screening an oil displacement system based on monomolecular film characterization according to any one of claims 1 to 5, characterized in that: The oil displacement experiment in step (5) includes a core oil displacement experiment.

7. The method for screening an oil displacement system based on monomolecular film characterization according to any one of claims 1 to 6, characterized in that: The number of groups in step (5) is at least 5 groups.

8. The method for screening an oil displacement system based on monomolecular film characterization according to any one of claims 1 to 7, characterized in that: The relationship between the interfacial film number Φ obtained by fitting in step (5) and the enhanced oil recovery EOR is:

9. The method for screening an oil displacement system based on monomolecular film characterization according to any one of claims 1 to 8, characterized in that: When the number of interfacial films reaches 200, the oil displacement system is judged to have a good oil displacement effect.

10. Use of the method for oil displacement system screening based on monomolecular film characterization as claimed in any one of claims 1 to 9 in oil displacement system screening.

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