Screening method of shale oil reservoir chemical assisted huff-puff / displacement system based on acoustic levitation

Abstract

The invention provides a screening method of a shale oil reservoir chemical-assisted huff and puff / displacement system based on acoustic levitation. The screening method comprises the following steps: selecting a shale oil reservoir chemical-assisted huff and puff / displacement system aqueous solution for testing interfacial tension and high-frequency interface expansion modulus; the high-frequency interface expansion modulus is tested by adopting an acoustic levitation method; and substituting the obtained parameters into a screening formula of the chemically-assisted throughput / displacement system, selecting different systems to repeat the steps, substituting the parameters into the screening formula, and screening a proper chemically-assisted throughput / displacement system according to a calculation result. According to the method, a shale oil reservoir chemical assisted huff-puff / displacement system is screened and evaluated, acoustic levitation is introduced into an evaluation system to test the high-frequency interface expansion modulus, and the interface tension is combined and substituted into a screening formula, so that the effect of different systems on improvement of shale oil reservoir expansion sweep is judged; the method can clarify the quantitative relationship among the parameters, is simple and efficient, can reduce the workload of a screening system, improves the result reliability, and is wide in application range.

Description

Technical Field

[0001] The invention belongs to the technical field of oil reservoir exploitation and relates to a screening method for a shale oil reservoir chemically assisted huff / puff / displacement system based on acoustic suspension. Background Art

[0002] There are various types of shale reservoirs, but the permeability of shale reservoirs is generally low. Large-scale volume fracturing is required before exploitation. The subsequent injected fluid is easy to flow along the fractures during displacement or huff / puff / displacement, resulting in insufficient swept volume of the injected fluid. Chemically assisted carbon dioxide swept huff / puff technology is a method that uses chemical agents to block high-permeability channels and expand the swept volume of the carbon dioxide recovery process, thereby increasing the recovery rate of shale oil. At present, the research on chemical-assisted huff / puff / displacement of shale oil reservoirs is still in the exploratory stage, and there are still technical difficulties in the efficient selection of chemical agents.

[0003] Acoustic levitation is a technology that uses the pressure of sound waves to suspend small particles or droplets in the air. This phenomenon is based on the principle of nonlinear acoustics. By precisely controlling the frequency, phase and amplitude of sound waves, acoustic tweezers can be formed in the air, which can exert enough force on the object to offset gravity, thereby achieving suspension. Acoustic levitation technology usually requires the use of specific equipment, such as ultrasonic transducer arrays, which can generate sound wave fields with specific characteristics. The application areas of acoustic levitation are quite wide, including scientific research, industrial manufacturing, medical and consumer electronics. In recent years, acoustic levitation technology has also been used in the field of chemical-assisted oil recovery, and has achieved good screening and characterization effects.

[0004] CN 110823769A discloses an ultrasonic suspension type liquid surface tension coefficient measurement method and device, the method comprises: suspending a droplet to be measured in a standing field wave, stimulating the droplet to generate a surface vibration mode, and calculating the droplet surface tension coefficient α according to a formula and various parameters; the device comprises an ultrasonic generator, a pair of ultrasonic transducers, and a loudspeaker, the ultrasonic generator outputs two channels of high-power signals with the same frequency to drive a pair of ultrasonic transducers; a pair of ultrasonic transducers are arranged relative to form a standing wave field, which is used to adjust the phase of a pair of ultrasonic transducers by the ultrasonic generator to meet the resonance condition to realize the suspension of the droplet to be measured; the output end of the loudspeaker is arranged on one side of the standing wave field, which is used to stimulate the vibration of the droplet to be measured. The method uses acoustic suspension to test the surface tension, and the surface tension and the interfacial film strength calculated therefrom are important parameters for characterizing the performance of chemically assisted throughput / displacement systems such as surfactants, but the patent does not clarify the guiding role of acoustic suspension technology in system screening and the relationship between various parameters, as well as how to obtain empirical formulas to reduce the workload of screening.

[0005] "Research on the relationship between foam plugging performance and interface properties" (Wang Zhuangzhuang, Li Zhaomin, Li Songyan. Journal of Chemical Engineering of Colleges and Universities, 2016, 30(01): 216-222.) discloses the relationship between interfacial tension, interfacial rheology and foam plugging performance, including: interfacial rheology characterizes the properties of foam liquid film, foam with good plugging performance should have both high viscosity and good elasticity, and interfacial elastic modulus and interfacial viscous modulus jointly affect foam plugging performance; interfacial tension and foam plugging performance are negatively correlated, the smaller the interfacial tension, the more conducive to foam regeneration, and the corresponding larger interfacial modulus, so the foam plugging performance is better. However, the interfacial expansion modulus used in the article is a low-frequency modulus, and the problem of reducing interfacial tension making it easier for droplets / bubbles to pass through pore throats is not considered, and the relationship between the parameters is not quantified.

[0006] In summary, the existing methods lack a high-frequency modulus screening system, the intrinsic correlation mechanism between interfacial tension, interfacial rheology and system plugging performance is unclear, and the quantitative correlation between various parameters is not given. These deficiencies cannot meet the screening of chemically assisted huff / puff / displacement systems for shale reservoirs and provide guidance for actual reservoir exploitation. Summary of the invention

[0007] In view of the problems existing in the prior art, the purpose of the present invention is to provide a screening method for chemically assisted throughput / displacement systems for shale oil reservoirs based on acoustic levitation. The method screens and evaluates chemically assisted throughput / displacement systems for shale oil reservoirs, introduces acoustic levitation technology into the evaluation system, and substitutes parameters such as interfacial tension and high-frequency interface expansion modulus into the screening formula to evaluate the advantages and disadvantages of different systems in improving the expansion effect of shale oil reservoirs, thereby reducing the workload of formula screening and improving the reliability of the results.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] The present invention provides a screening method for a shale oil reservoir chemically assisted huff / puff / displacement system based on acoustic levitation, the screening method comprising the following steps:

[0010] (1) Selecting a chemically assisted huff / puff / displacement system aqueous solution to test the interfacial tension γ and the high-frequency interfacial dilation modulus ε respectively; wherein the high-frequency interfacial dilation modulus ε is tested by an acoustic levitation method, selecting the type of acoustic wave, the intensity of the acoustic field and the high-frequency frequency, suspending the droplets and generating high-frequency interfacial dilation and compression, so as to obtain the high-frequency interfacial dilation modulus ε;

[0011] (2) Substituting the parameters obtained in step (1) into the screening formula for chemical-assisted huff / puff / displacement system for shale oil reservoirs;

[0012] (3) Select different chemically assisted throughput / displacement systems and repeat step (1), substitute the obtained parameters into the screening formula described in step (2), and screen a suitable chemically assisted throughput / displacement system based on the calculation results.

[0013] In the present invention, for the exploitation of shale oil reservoirs, especially in the tertiary oil recovery process with high exploitation difficulty, the screening and evaluation of chemical-assisted throughput / displacement systems are indispensable steps; in the present invention, for the screening of chemical-assisted throughput / displacement systems, it is necessary to adopt multiple characterization methods to obtain multiple parameters to cover more oil phase properties, and the high-frequency interface expansion modulus parameters are tested by introducing acoustic levitation into the evaluation system, and then combined with the interface tension parameters, the parameters are substituted into the screening formula of the chemical-assisted throughput / displacement system of the shale oil reservoir, so as to directly judge the advantages and disadvantages of different systems in improving the expansion effect, reduce the workload of formula screening, improve the reliability of the results, and provide a reliable reference for the selection of on-site chemical-assisted throughput / displacement systems in shale oil reservoirs; the method is clear and quantitative, concise and efficient, and widely applicable.

[0014] In the present invention, the chemically assisted throughput / displacement system refers to a chemically assisted throughput system or a chemically assisted displacement system, which indicates the different functions and uses of chemically assisted throughput or assisted displacement in the process of shale oil reservoir exploitation.

[0015] The following are preferred technical solutions of the present invention, but are not intended to be limitations of the technical solutions provided by the present invention. Through the following technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0016] As a preferred technical solution of the present invention, the chemically assisted throughput / displacement system in step (1) includes a surfactant.

[0017] Preferably, the surfactant comprises any one of anionic surfactants, zwitterionic surfactants, anionic-nonionic surfactants or nonionic surfactants, or a combination of at least two thereof. Typical but non-limiting examples of the combination include: a combination of anionic surfactants and zwitterionic surfactants, a combination of zwitterionic surfactants and nonionic surfactants, a combination of anionic surfactants, zwitterionic surfactants and nonionic surfactants, a combination of anionic surfactants, zwitterionic surfactants and nonionic surfactants, a combination of anionic-nonionic surfactants and anionic surfactants, etc.

[0018] Preferably, the mass concentration of the aqueous solution of the chemically assisted huff / puff system in step (1) is 0.05-5%, for example, 0.05%, 0.1%, 0.3%, 0.5%, 1%, 1.5%, 2%, 3%, 4% or 0.5%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 0.3%.

[0019] In the present invention, the chemical-assisted huff / displacement system aqueous solution is prepared by mixing the chemical-assisted huff / displacement system with shale oil reservoir water, and the mass concentration remains consistent when preparing different chemical-assisted huff / displacement systems.

[0020] As a preferred technical solution of the present invention, the test method of the interfacial tension γ in step (1) includes any one of the hanging ring method, hanging plate method, capillary rise method, bubble pressure method, hanging drop method, spinning drop method or surface laser scattering method.

[0021] As a preferred technical solution of the present invention, the high-frequency interface expansion modulus ε in step (1) is tested using an acoustic suspension device. The type of sound waves is selected, and the droplets are placed in the sound field of the acoustic suspension device to suspend the droplets. The sound field intensity and the high-frequency sound wave frequency are selected. Under the action of the high-frequency sound waves, the droplet interface continuously expands and compresses, and the high-frequency interface expansion modulus ε is monitored and calculated in real time to obtain the high-frequency interface expansion modulus ε.

[0022] As a preferred technical solution of the present invention, the sound wave type includes a sine wave.

[0023] Preferably, the droplet volume is 2 to 10 μL, for example 2 μL, 3 μL, 4 μL, 5 μL, 6 μL, 8 μL or 10 μL, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0024] Preferably, the initial sound wave frequency of the acoustic suspension device is 30 to 40 kHz, for example, 30 kHz, 32 kHz, 34 kHz, 36 kHz, 37 kHz, 38 kHz, 39 kHz or 40 kHz, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 36 to 40 kHz.

[0025] In the present invention, when the acoustic levitation device is initially operated, in order to ensure that the droplets can be suspended, its initial frequency is relatively large, which can reach 30 to 40 kHz. In subsequent tests, the droplets need to be kept moving, expanding, compressing and observable, so the required frequency needs to be reduced, specifically 80 to 120 Hz.

[0026] Preferably, the sound field intensity is 10-50% of the amplitude, for example 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45% or 50%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0027] Preferably, the frequency of the high-frequency sound wave is 80-120 Hz, for example 80 Hz, 85 Hz, 90 Hz, 95 Hz, 100 Hz, 105 Hz, 110 Hz, 115 Hz or 120 Hz, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0028] Preferably, the frequency of the high-frequency interface expansion and compression of the droplets is 80 to 120 Hz, for example 80 Hz, 85 Hz, 90 Hz, 95 Hz, 100 Hz, 105 Hz, 110 Hz, 115 Hz or 120 Hz, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0029] In the present invention, the high frequency in the high frequency sound wave and the high frequency interface dilation modulus is compared with the interface dilation modulus tested by the hanging drop method, which uses a lower frequency of 0.1 to 0.001 Hz.

[0030] As a preferred technical solution of the present invention, in the screening formula of step (2), the interfacial tension γ is converted into the f(γ) function through empirical processing, and the high-frequency interfacial expansion modulus ε is converted into the f(ε) function through empirical processing.

[0031] Preferably, the units of the interfacial tension γ and the high-frequency interfacial extension modulus ε are both mN / m.

[0032] Preferably, the f(γ) function has a maximum value when the interfacial tension γ gradually increases from 0 mN / m, and the f(ε) function increases monotonically when the high-frequency interfacial extension modulus ε gradually increases from 0 mN / m.

[0033] As a preferred technical solution of the present invention, the weights of the two functions f(γ) and f(ε) in the formula are 57% to 72%, for example, 57%, 61%, 64%, 68%, 69% or 72%, and 28% to 43%, for example, 28%, 31%, 34%, 36%, 39% or 43%, etc.; but they are not limited to the listed values, and other unlisted values ​​within their respective numerical ranges are also applicable.

[0034] Preferably, the screening formula in step (2) is expressed as E v(h) =f(γ)×(57%~72%)+f(ε)×(28%~43%); for example, f(γ)×57%+f(ε)×43%, f(γ)×60%+f(ε)×40%, f(γ)×64%+f(ε)×36%, f(γ)×68%+f(ε)×32% or f(γ)×72%+f(ε)×28%, etc., but are not limited to the listed values, and other unlisted values ​​within the respective numerical ranges are equally applicable.

[0035] Preferably, the screening formula is further assigned values ​​according to experimental data and experience, and the final screening formula is

[0036] As a preferred technical solution of the present invention, the chemically assisted huff / puff / displacement system in step (3) includes any one of anionic surfactants, zwitterionic surfactants, anionic-nonionic surfactants or nonionic surfactants, or a combination of at least two thereof. Typical but non-limiting examples of the combination include: a combination of anionic surfactants and zwitterionic surfactants, a combination of zwitterionic surfactants and nonionic surfactants, a combination of anionic surfactants, zwitterionic surfactants and nonionic surfactants, a combination of anionic surfactants, zwitterionic surfactants and nonionic surfactants, a combination of anionic surfactants, zwitterionic surfactants and nonionic surfactants, a combination of anionic-nonionic surfactants and anionic surfactants, etc.

[0037] As a preferred technical solution of the present invention, when step (3) is tested using different chemically assisted throughput / displacement systems, the calculated result E after substituting into the screening formula is v(h) The larger it is, the better its ability to assist in expanding the impact.

[0038] As a preferred technical solution of the present invention, the screening method comprises the following steps:

[0039] (1) Selecting a chemically assisted huff / displacement system aqueous solution to test the interfacial tension γ and the high-frequency interface dilation modulus ε respectively; wherein the chemically assisted huff / displacement system comprises any one of anionic surfactants, zwitterionic surfactants, anionic-nonionic surfactants or nonionic surfactants or a combination of at least two; the mass concentration of the chemically assisted huff / displacement system aqueous solution is 0.05-5%; the test method of the interfacial tension γ comprises any one of the hanging ring method, hanging plate method, capillary rise method, bubble pressure method, hanging drop method, spinning drop method or surface laser scattering method; the high-frequency interface dilation modulus ε The tensile modulus ε is tested by using an acoustic suspension device, selecting an acoustic wave type, which includes a sine wave, placing a droplet in the acoustic field of the acoustic suspension device so that the droplet is suspended, the initial acoustic wave frequency of the acoustic suspension device is 30-40kHz, the droplet volume is 2-10μL, the acoustic field intensity and the high-frequency acoustic wave frequency are selected, the acoustic field intensity is 10-50% of the amplitude, the high-frequency acoustic wave frequency is 80-120Hz, the droplet interface is continuously expanded and compressed under the action of the high-frequency acoustic wave, the frequency of the droplet high-frequency interface expansion and compression is 80-120Hz, real-time monitoring and calculation are performed to obtain the high-frequency interface expansion modulus ε;

[0040] (2) Substituting the parameters obtained in step (1) into the screening formula of the chemical-assisted huff / puff / displacement system for shale oil reservoirs; the interfacial tension γ is converted into the f(γ) function through empirical processing, and the high-frequency interface dilation modulus ε is converted into the f(ε) function through empirical processing, the units of the interfacial tension γ and the high-frequency interface dilation modulus ε are both mN / m, the f(γ) function has a maximum value when the interfacial tension γ gradually increases from 0 mN / m, and the f(ε) function increases monotonically when the high-frequency interface dilation modulus ε gradually increases from 0 mN / m; the weights of the f(γ) and f(ε) functions in the screening formula are 57% to 72% and 28% to 43%, respectively; the screening formula is expressed as E v(h) =f(γ)×(57%~72%)+f(ε)×(28%~43%); the screening formula is further assigned values ​​according to experimental data and experience, and the final screening formula is:

[0041]

[0042] (3) Select a different chemically assisted throughput / displacement system to repeat step (1), wherein the chemically assisted throughput / displacement system includes a surfactant, wherein the surfactant includes any one of anionic surfactants, zwitterionic surfactants, anionic-nonionic surfactants, or nonionic surfactants, or a combination of at least two thereof; substitute the obtained parameters into the screening formula of step (2), and screen a suitable chemically assisted throughput / displacement system according to the calculation results. The larger the calculation result, the better its ability to expand the spread.

[0043] Compared with the prior art, the present invention has at least the following beneficial effects:

[0044] (1) The method of the present invention is used to screen and evaluate the chemical-assisted huff / displacement system of shale oil reservoirs. The high-frequency interface dilation modulus is tested by introducing acoustic levitation into the evaluation system, and the interface tension parameter is combined and substituted into the screening formula of the chemical-assisted huff / displacement system of shale oil reservoirs to judge the advantages and disadvantages of different systems in improving the expansion effect of shale oil reservoirs, thereby providing a reliable reference for the selection of on-site chemical-assisted huff / displacement systems of shale oil reservoirs;

[0045] (2) The method of the present invention is clear and quantitative, simple and efficient, can effectively reduce the workload of formula screening, improve the reliability of the results, and has a wide range of applications. DETAILED DESCRIPTION

[0046] In order to better illustrate the present invention and facilitate understanding of the technical solution of the present invention, the present invention is further described in detail below. However, the following embodiments are only simple examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0047] The specific implementation of the present invention provides a method for screening a chemically assisted huff / puff / displacement system for shale oil reservoirs based on acoustic levitation, the screening method comprising the following steps:

[0048] (1) Selecting a chemically assisted huff / puff / displacement system aqueous solution to test the interfacial tension γ and the high-frequency interfacial dilation modulus ε respectively; wherein the high-frequency interfacial dilation modulus ε is tested by an acoustic levitation method, selecting the type of acoustic wave, the intensity of the acoustic field and the high-frequency frequency, suspending the droplets and generating high-frequency interfacial dilation and compression, so as to obtain the high-frequency interfacial dilation modulus ε;

[0049] (2) Substituting the parameters obtained in step (1) into the screening formula for chemical-assisted huff / puff / displacement system for shale oil reservoirs;

[0050] (3) Select different chemically assisted throughput / displacement systems and repeat step (1), substitute the obtained parameters into the screening formula described in step (2), and screen a suitable chemically assisted throughput / displacement system based on the calculation results.

[0051] The following are typical but non-limiting embodiments of the present invention:

[0052] Embodiment 1:

[0053] This embodiment provides a screening method for a shale oil reservoir chemical-assisted displacement system based on acoustic levitation, the screening method comprising the following steps:

[0054] (1) Selecting a chemically assisted displacement system aqueous solution to test the interfacial tension γ and high-frequency interfacial expansion modulus ε; wherein the chemically assisted displacement system comprises sodium dodecylbenzene sulfonate, octadecylhydroxysulfobetaine, and sodium lauryl polyoxypropylene (10) ether sulfate; the mass concentration of the chemically assisted displacement system aqueous solution is 0.3%; the test method of the interfacial tension γ is a rotating drop method; the high-frequency interfacial expansion modulus ε is tested using an acoustic suspension device, the acoustic wave type is selected as a sine wave, and the droplet is placed in an acoustic suspension device with an initial acoustic wave frequency of 38.22kHz to suspend the droplet, the droplet volume is 5 μL, the acoustic field intensity and high-frequency acoustic wave frequency are selected, the acoustic field intensity is 25% of the amplitude, the high-frequency acoustic wave frequency is 100 Hz, the droplet interface is continuously expanded and compressed under the action of the high-frequency acoustic wave, the frequency of the droplet high-frequency interface expansion and compression is 100 Hz, real-time monitoring and calculation are performed to obtain the high-frequency interfacial expansion modulus ε;

[0055] (2) Substituting the parameters obtained in step (1) into the screening formula of chemical-assisted displacement system for shale oil reservoirs; the interfacial tension γ is converted into the f(γ) function through empirical processing, and the high-frequency interface expansion modulus ε is converted into the f(ε) function through empirical processing, the units of the interfacial tension γ and the high-frequency interface expansion modulus ε are both mN / m, the f(γ) function has a maximum value when the interfacial tension γ gradually increases from 0mN / m, and the f(ε) function increases monotonically when the high-frequency interface expansion modulus ε gradually increases from 0mN / m; the weights of the two functions f(γ) and f(ε) in the formula are 64% and 36%, respectively; the screening formula is expressed as E v(h) =f(γ)×64%+f(ε)×36%; the screening formula is further assigned values ​​according to experimental data and experience, and the final screening formula is:

[0056] (3) Conduct a double-tube parallel displacement experiment to verify the screening effect: The core used in the experiment is a shale core with a core length of 6 cm and a cross-sectional area of ​​4.91 cm 2 The water-gas permeability of the core is 0.08mD, and the porosity is 12.3%. The high-permeability core is fractured by the Brazilian splitting method, and the low-permeability core is not treated. The experimental oil is simulated oil (viscosity is 2.3mPa·s at 70℃), and the experimental water is simulated formation water (mineralization 13071mg / L). The chemical-assisted displacement systems are sodium dodecylbenzene sulfonate, octadecyl hydroxysulfobetaine, and sodium lauryl polyoxypropylene (10) ether sulfate, and an aqueous solution with a mass concentration of 0.3% is prepared. The initial CO2 drive to gas-liquid volume ratio>2000, 0.3PV chemical-assisted displacement system, and CO2 drive to gas-liquid volume ratio>2000 are carried out in sequence. The low-permeability diversion rate at the end of the initial CO2 drive and the highest low-permeability diversion rate during the drive are recorded, and the core expansion sweep effect v=highest low-permeability diversion rate during the drive / low-permeability diversion rate at the end of the initial CO2 drive is calculated.

[0057] The test results of interfacial tension and high-frequency interfacial dilation modulus, the calculation results of the screening formula, and the core enlargement sweep effect when different chemical-assisted displacement systems are used in Example 1 are shown in Table 1.

[0058] Table 1

[0059]

[0060] According to the data results in Table 1, E v(h) It is linearly related to the expansion effect, and its linear relationship can be summarized as E v(h) =1.786v-18.863, R 2 =0.9815, prove E v(h) Can effectively screen and expand the affected system.

[0061] Embodiment 2:

[0062] This embodiment provides a screening method for a shale oil reservoir chemically assisted throughput system based on acoustic levitation, the screening method comprising the following steps:

[0063] (1) Selecting a chemically assisted throughput system aqueous solution to test the interfacial tension γ and high-frequency interface expansion modulus ε; wherein the chemically assisted throughput system comprises sodium dodecyl sulfate + octadecylbenzene hydroxysulfobetaine (1:1), octylphenol polyoxyethylene (10) ether, and tetradecyl alcohol polyoxypropylene (10) polyoxyethylene (5) ether sodium sulfate; the mass concentration of the chemically assisted throughput system aqueous solution is 0.2%; the test method of the interfacial tension γ is the spinning drop method; the high-frequency interface expansion modulus ε is tested using an acoustic suspension device, the acoustic wave type is selected as a sine wave, and the droplet is placed in an acoustic suspension device with an initial acoustic wave frequency of 35.2kHz to suspend the droplet, the droplet volume is 3μL, the acoustic field intensity and high-frequency acoustic wave frequency are selected, the acoustic field intensity is 30% of the amplitude, the high-frequency acoustic wave frequency is 110Hz, the droplet interface is continuously expanded and compressed under the action of the high-frequency acoustic wave, and the frequency of the droplet high-frequency interface expansion and compression is 110Hz, and the high-frequency interface expansion and compression is obtained by real-time monitoring and calculation;

[0064] (2) Substitute the parameters in step (1) into the screening formula of chemical-assisted throughput system for shale oil reservoirs; the interface tension γ is converted into the f(γ) function through empirical processing, and the high-frequency interface expansion modulus ε is converted into the f(ε) function through empirical processing. The units of the interface tension γ and the high-frequency interface expansion modulus ε are both mN / m. The f(γ) function has a maximum value when the interface tension γ gradually increases from 0mN / m, and the f(ε) function increases monotonically when the high-frequency interface expansion modulus ε gradually increases from 0mN / m. The weights of the two functions f(γ) and f(ε) in the formula are 64% and 36%, respectively. The screening formula is expressed as E v(h) =f(γ)×64%+f(ε)×36%; the screening formula is further assigned values ​​according to experimental data and experience, and the final screening formula is:

[0065] (3) Conduct a dual-tube parallel throughput experiment to verify the screening effect: The core used in the experiment is a shale core with a core length of 5.8 cm and a cross-sectional area of ​​4.91 cm 2The core water and gas permeability is 0.05mD, and the porosity is 11.8%. The high permeability core is fractured by the Brazilian splitting method, and the low permeability core is not treated. The experimental oil is simulated oil (viscosity is 2.2mPa·s at 80℃), and the experimental water is simulated formation water (mineralization 9857mg / L). The double-tube parallel cores share one injection and discharge port, and the other ends are connected to each other by pipelines.

[0066] The chemical-assisted huff and puff systems were selected as sodium dodecyl sulfate + octadecylbenzene hydroxysulfobetaine (1:1), octylphenol polyoxyethylene (10) ether, and tetradecyl alcohol polyoxypropylene (10) polyoxyethylene (5) ether sodium sulfate, and a 0.2% aqueous solution was prepared. The following were carried out in sequence: in the first stage, 0.5PV of CO2 was injected, the well was held for 12 hours, and the gas output was released until it was less than 5mL / min; in the second stage, 0.5PV of CO2 was injected, 0.2PV of the chemical-assisted huff and puff system was injected, the well was held for 12 hours, and the gas output was less than 5mL / min. The high permeability gas output at the end of the first stage and the end of the second stage was recorded, and the core expansion sweep effect was calculated as high permeability gas output at the end of the first stage / high permeability gas output at the end of the second stage.

[0067] The test results of interfacial tension and high-frequency interfacial dilation modulus, the calculation results of the screening formula, and the core enlargement effect when different chemical-assisted throughput systems are used in Example 2 are shown in Table 2.

[0068] Table 2

[0069]

[0070]

[0071] According to the data results in Table 2, E v(h) It is linearly related to the expansion effect, and its linear relationship can be summarized as E v(h) =0.7068v-6.7822, R 2 =0.9498, prove E v(h) Can effectively screen and expand the affected system.

[0072] From the above embodiments, it can be seen that the present invention screens and evaluates the chemical-assisted throughput / displacement system for shale oil reservoirs, introduces acoustic levitation into the evaluation system to test the high-frequency interface expansion modulus, combines the interface tension parameter, and substitutes it into the screening formula for the chemical-assisted throughput / displacement system for shale oil reservoirs, so as to judge the advantages and disadvantages of different systems in improving the expansion effect of shale oil reservoirs; the method clarifies the quantitative relationship between interface tension, high-frequency interface expansion modulus and shale oil reservoir expansion, is simple and efficient, can reduce the workload of using the core experiment screening system, improve the reliability of the results, and has a wide range of applications.

[0073] The applicant declares that the present invention illustrates the detailed method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed method, that is, it does not mean that the present invention must rely on the above-mentioned detailed method to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the method of the present invention, addition of auxiliary steps, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A screening method for chemically assisted huff / puff / displacement system in shale oil reservoirs based on acoustic levitation, characterized in that: The screening method comprises the following steps: (1) Selecting a chemically assisted huff / puff / displacement system aqueous solution to test the interfacial tension γ and the high-frequency interfacial dilation modulus ε respectively; wherein the high-frequency interfacial dilation modulus ε is tested by an acoustic levitation method, selecting the type of acoustic wave, the intensity of the acoustic field and the high-frequency frequency, suspending the droplets and generating high-frequency interfacial dilation and compression, so as to obtain the high-frequency interfacial dilation modulus ε; (2) Substituting the parameters obtained in step (1) into the screening formula of the chemical-assisted huff / puff / displacement system for shale oil reservoirs; (3) Select different chemically assisted throughput / displacement systems and repeat step (1), substitute the obtained parameters into the screening formula described in step (2), and screen a suitable chemically assisted throughput / displacement system based on the calculation results.

2. The screening method according to claim 1, characterized in that The chemically assisted huff / puff / displacement system in step (1) includes a surfactant; Preferably, the surfactant comprises any one or a combination of at least two of anionic surfactants, zwitterionic surfactants, nonionic surfactants or anionic-nonionic surfactants; Preferably, the mass concentration of the chemically assisted huff / puff / displacement system aqueous solution in step (1) is 0.05-5%, preferably 0.3%.

3. The screening method according to claim 1 or 2, characterized in that The test method of the interfacial tension γ in step (1) includes any one of a hanging ring method, a hanging plate method, a capillary rise method, a bubble pressure method, a hanging drop method, a spinning drop method or a surface laser scattering method.

4. The screening method according to any one of claims 1 to 3, characterized in that The high-frequency interface expansion modulus ε described in step (1) is tested using an acoustic levitation device. The type of sound waves is selected, and the droplets are placed in the sound field of the acoustic levitation device to suspend the droplets. The sound field intensity and the frequency of the high-frequency sound waves are selected. Under the action of the high-frequency sound waves, the droplet interface continuously expands and compresses, and the high-frequency interface expansion modulus ε is obtained by real-time monitoring and calculation.

5. The screening method according to claim 4, characterized in that The sound wave type includes a sine wave; Preferably, the droplet volume is 2 to 10 μL, preferably 5 μL; Preferably, the initial sound wave frequency of the acoustic suspension device is 30 to 40 kHz, preferably 36 to 40 kHz; Preferably, the sound field intensity is 10-50% of the amplitude; Preferably, the frequency of the high-frequency sound wave is 80 to 120 Hz; Preferably, the frequency of the high-frequency interface expansion and compression of the droplets is 80 to 120 Hz.

6. The screening method according to any one of claims 1 to 5, characterized in that In the screening formula of step (2), the interfacial tension γ is converted into the f(γ) function through empirical processing, and the high-frequency interfacial expansion modulus ε is converted into the f(ε) function through empirical processing; Preferably, the units of the interfacial tension γ and the high-frequency interfacial expansion modulus ε are both mN / m; Preferably, the f(γ) function has a maximum value when the interfacial tension γ gradually increases from 0 mN / m, and the f(ε) function increases monotonically when the high-frequency interfacial extension modulus ε gradually increases from 0 mN / m.

7. The screening method according to claim 6, characterized in that The weights of the two functions f(γ) and f(ε) in the screening formula are 57% to 72% and 28% to 43% respectively; Preferably, the screening formula in step (2) is expressed as E v(h) =f(γ)×(57%~72%)+f(ε)×(28%~43%); Preferably, the screening formula is further assigned values ​​according to experimental data and experience, and the final screening formula is 8. The screening method according to any one of claims 1 to 7, characterized in that The chemically assisted huff / puff / displacement system in step (3) includes a surfactant; Preferably, the surfactant includes any one of anionic surfactants, zwitterionic surfactants, anionic-nonionic surfactants or nonionic surfactants, or a combination of at least two thereof.

9. The screening method according to any one of claims 1 to 8, characterized in that Step (3) When testing with different chemical-assisted throughput / displacement systems, the calculated result E after substituting into the screening formula is v(h) The larger it is, the better its ability to assist in expanding the impact.

10. The screening method according to any one of claims 1 to 9, characterized in that The screening method comprises the following steps: (1) Selecting a chemically assisted huff / displacement system aqueous solution to test the interfacial tension γ and the high-frequency interface dilation modulus ε respectively; wherein the chemically assisted huff / displacement system comprises any one of anionic surfactants, zwitterionic surfactants, anionic-nonionic surfactants or nonionic surfactants or a combination of at least two; the mass concentration of the chemically assisted huff / displacement system aqueous solution is 0.05-5%; the test method of the interfacial tension γ comprises any one of the hanging ring method, hanging plate method, capillary rise method, bubble pressure method, hanging drop method, spinning drop method or surface laser scattering method; the high-frequency interface dilation modulus ε The tensile modulus ε is tested by using an acoustic suspension device, selecting an acoustic wave type, which includes a sine wave, placing a droplet in the acoustic field of the acoustic suspension device so that the droplet is suspended, the initial acoustic wave frequency of the acoustic suspension device is 30-40kHz, the droplet volume is 2-10μL, the acoustic field intensity and the high-frequency acoustic wave frequency are selected, the acoustic field intensity is 10-50% of the amplitude, the high-frequency acoustic wave frequency is 80-120Hz, the droplet interface is continuously expanded and compressed under the action of the high-frequency acoustic wave, the frequency of the droplet high-frequency interface expansion and compression is 80-120Hz, real-time monitoring and calculation are performed to obtain the high-frequency interface expansion modulus ε; (2) Substituting the parameters obtained in step (1) into the screening formula of the chemical-assisted huff / puff / displacement system for shale oil reservoirs; the interfacial tension γ is converted into the f(γ) function through empirical processing, and the high-frequency interface dilation modulus ε is converted into the f(ε) function through empirical processing, the units of the interfacial tension γ and the high-frequency interface dilation modulus ε are both mN / m, the f(γ) function has a maximum value when the interfacial tension γ gradually increases from 0 mN / m, and the f(ε) function increases monotonically when the high-frequency interface dilation modulus ε gradually increases from 0 mN / m; the weights of the f(γ) and f(ε) functions in the screening formula are 57% to 72% and 28% to 43%, respectively; the screening formula is expressed as E v(h) =f(γ)×(57%~72%)+f(ε)×(28%~43%); the screening formula is further assigned values ​​according to experimental data and experience, and the final screening formula is: (3) Select a different chemically assisted throughput / displacement system to repeat step (1), wherein the chemically assisted throughput / displacement system includes a surfactant, wherein the surfactant includes any one of anionic surfactants, zwitterionic surfactants, anionic-nonionic surfactants, or nonionic surfactants, or a combination of at least two thereof; substitute the obtained parameters into the screening formula of step (2), and screen a suitable chemically assisted throughput / displacement system according to the calculation results. The larger the calculation result, the better its ability to assist in expanding the spread.

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