Composite system determination method and device, storage medium and shale oil development method

Abstract

The embodiment of the invention provides a compound system determination method and device, a storage medium and a shale oil development method, and belongs to the technical field of shale oil. The determination method comprises the following steps: performing corresponding oil-gas interface tension and liquid-solid interface wettability measurement on a plurality of obtained initial composite nano systems, and screening out a first composite nano system; based on the first composite nano system, calculating parameter values influencing the pore structure, pore size and asphaltene content of the shale reservoir rock, and screening out a second composite nano system; and determining the micro-fluidic sweep efficiency and the core throughput recovery rate of the second composite system to determine the optimal composite nano system. According to the principle from microcosmic to macroscopic and from experiments to mine fields, the optimal composite nano system is screened out through three-stage screening, and the shale oil reservoir development problems that due to the fact that an existing CO2 and chemical additive system is single in screening standard, a displacement relation cannot be established between wells, and the mine field implementation effect is poor are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of shale oil, and specifically to a method and device for determining a composite system, a storage medium, and a shale oil development method. Background Art

[0002] As an important unconventional alternative energy source, shale oil has great development potential. The application of the "hydraulic fracturing + horizontal well" technology has realized the economic development of shale oil. However, due to factors such as poor physical properties of shale oil, complex initial wettability, large proportion of nano-scale pore throats, irregular fracture development, and complex occurrence space, effective gas injection is required during the exploitation of shale oil to achieve secondary development of shale oil. Through experiments and numerical simulations carried out, it has been fully verified that gas injection and energy supplementation in shale oil reservoirs such as CO2, natural gas, and N2 are feasible in terms of improving oil recovery by injecting gas and some necessary chemical systems (enhancing gas injection). Compared with other gases, injecting CO2 can not only effectively supplement the formation energy, but also synergistically modify the crude oil through various mechanisms, increase the fluidity of the crude oil, and thus increase the production. However, the shale bedding fractures in the shale oil reservoir are well-developed, and the fractures between wells are complexly connected. The injected gas is channeled through the high-conductivity fractures between wells, resulting in insignificant pressure rise around the gas injection well, increased gas production in adjacent wells, low gas utilization rate, waste of gas source, and difficulty in effectively entering the shale matrix to achieve crude oil modification and energy supplementation, seriously reducing the development effect. At the same time, the produced gas is likely to cause air pollution or the greenhouse effect.

[0003] To solve the above problems, some existing technologies can improve the wettability and reduce the interfacial tension by adding surfactants, polymers, lime water, modified starch gels, etc. to the injected gas, increase the viscosity of the injected gas or block the channels, thereby slowing down gas channeling. For example, the surfactant-assisted carbon dioxide huff and puff oil recovery method is used for anti-channeling and enhanced production in medium-high permeability or low-permeability heavy oil reservoirs, and the dominant flow channels in medium-low permeability oil reservoirs are blocked by injecting temporary plugging agents. For shale oil reservoirs, chemical agents mainly for plugging will further exacerbate the contradiction of difficult injection, resulting in the risk of inapplicability. For example, the nanofluid-assisted carbon dioxide huff and puff oil recovery method is not a traditional single-well huff and puff process. By distinguishing the injection well and the production well, it is required to establish a displacement relationship between nanofluid and liquid CO2 between the two wells, and the method can only be implemented based on the successful establishment of the displacement relationship. It has obvious limitations for reservoirs where it is difficult to establish a displacement relationship due to reasons such as tight reservoir or large well spacing. Summary of the Invention

[0004] An object of an embodiment of the present invention is to provide a method for determining a composite system for shale oil gas injection development, which can solve the limitations of the existing method for determining a composite system for shale oil gas injection development.

[0005] To achieve the above object, an embodiment of the present invention provides a method for determining a composite system for shale oil gas injection development, characterized in that the method for determining the composite system includes: obtaining a plurality of initial composite nano-systems for synergistically enhancing shale oil recovery by carbon dioxide huff and puff; under preset temperature and pressure conditions, measuring the corresponding oil-gas interfacial tension and liquid-solid interfacial wettability of the obtained plurality of initial composite nano-systems, and screening out a first composite nano-system that meets the preset conditions; based on the experimental core and crude oil after the interaction between the first composite nano-system and CO2, calculating the parameter values affecting the pore structure, pore size and asphaltene content of the shale reservoir rock, and screening out a second composite nano-system; and measuring the microfluidic sweep efficiency and core huff and puff recovery rate of the second composite nano-system to determine the optimal composite nano-system.

[0006] Optionally, the step of, under preset temperature and pressure conditions, measuring the corresponding oil-gas interfacial tension and liquid-solid interfacial wettability of the obtained plurality of initial composite nano-systems, and screening out a first composite nano-system that meets the preset conditions includes: for each initial composite nano-system among the plurality of initial composite nano-systems, controlling an interfacial tension tester, introducing carbon dioxide gas into the initial composite nano-system after mixing with crude oil, and measuring the corresponding oil-gas interfacial tension of the initial composite nano-system; using the self-absorption-nuclear magnetic resonance test method to measure the relative wetting index of each initial composite nano-system and the shale core, and the relative wetting index is used to characterize the corresponding liquid-solid interfacial wettability; and sorting the plurality of initial composite nano-systems according to the liquid-solid interfacial wettability and the oil-gas interfacial tension, and screening out the first composite nano-system.

[0007] Optionally, the step of, based on the experimental core and crude oil after the interaction between the first composite nano-system and CO2, calculating the parameter values affecting the pore structure, pore size and asphaltene content of the shale reservoir rock, and screening out a second composite nano-system includes: for each first composite nano-system, respectively performing the following operations on the experimental core and crude oil after being acted on by CO2 and the experimental core and crude oil after the interaction between the first composite nano-system and CO2: using the digital core reconstructed by CT scanning to calculate the pore structure connectivity volume for characterizing the pore structure of the shale reservoir rock; using nuclear magnetic resonance to calculate the porosity for characterizing the pore size; and using a chromatograph to calculate the asphaltene content of the crude oil after huff and puff for characterizing the asphaltene content. Screening out the second composite nano-system according to the change conditions of the pore structure connectivity volume, porosity and asphaltene content obtained by the two calculations.

[0008] Optionally, the determination of the microfluidic sweep efficiency and core huff and puff recovery rate of the second composite nanosystem to determine the optimal composite nanosystem includes: for each second composite nanosystem, through an injection pump, injecting a medium into the microchannel chip at a constant speed and constant pressure, and simulating the preset temperature and pressure conditions through an confining pressure tracking pump, a circulation pump and a temperature control system, screening out a third composite nanosystem through the sweep efficiency of the second composite nanosystem and CO2 mixture; and for each third composite nanosystem, conducting a huff and puff experiment of the third composite nanosystem and CO2 mixture in a shale core, determining the corresponding huff and puff recovery rate and pressure conduction capacity, and screening out the optimal composite nanosystem.

[0009] Optionally, the determination of the sweep efficiency of the second composite nanosystem and CO2 mixture includes: through a video microscope, recording the development time-lapse images during the process of alternately injecting the second composite nanosystem and CO2 mixture in a microscale channel; based on the development time-lapse images, combining the distance transformation map and the medial axis skeleton map, statistically analyzing the inscribed circle radius on the medial axis skeleton point by point to obtain the pore throat distribution characterizing the microscopic model; using the development time-lapse image at the initial moment as a reference image, comparing it with the development time-lapse image at a preset moment, and adopting a threshold segmentation method to determine the pore throat activation region; combining the medial axis skeleton of the determined pore throat activation region with the distance transformation map, and statistically analyzing the frequency of pore throat radii on the medial axis of the pore throat activation region; calculating the sweep efficiency of pore throats of different sizes according to the ratio of the frequency of pore throat radii on the medial axis of the determined pore throat activation region to the pore throat frequency of the microscopic model; and obtaining the sweep efficiency based on the sweep efficiency of pore throats of different sizes and the proportion of each pore throat in the total pore throats.

[0010] Optionally, the sweep efficiency is represented by the following formula

[0011]

[0012]

[0013] where β i is the activated pore throat frequency of the i-th pore throat interval, η i is the pore throat frequency of the microscopic model of the i-th pore throat interval, A i is the frequency proportion of the i-th pore throat interval in the total pore throats.

[0014] An embodiment of the present invention also provides a method for shale oil gas injection development, which includes: determining an optimal composite nano-system for synergistic CO2 huff and puff development of shale oil according to the above-mentioned method for determining a composite system for shale oil gas injection development; and based on the constructed geological model at the well group scale of the shale oil reservoir, simulating the development of the shale oil reservoir well group by setting the injection slug sequence, slug size, soaking time, soaking times, and alternately injecting the composite nano-system and CO2, and determining the gas injection development strategy for the shale oil reservoir well group.

[0015] Optionally, the method for shale oil gas injection development further includes: calculating the buried amount of the corresponding CO2 after the process of simulating the development of the shale oil reservoir well group is stable.

[0016] An embodiment of the present invention also provides a control device for determining a composite system for shale oil gas injection development, which includes: a memory, a processor, and a computer program stored on the memory and executable on the processor, and the processor executes the computer program to implement the above-mentioned method for determining a composite system for shale oil gas injection development.

[0017] An embodiment of the present invention also provides a machine-readable storage medium, on which instructions are stored, and the instructions cause the machine to execute the above-mentioned method for determining a composite system for shale oil gas injection development or the above-mentioned method for shale oil gas injection development.

[0018] Through the above technical solutions, the embodiment of the present invention conducts the first-level screening based on the measurement of the oil-gas interfacial tension and liquid-solid interfacial wettability of the composite nano-system; calculates the parameter values affecting the pore structure of the shale reservoir rock, the micro-fracture seepage capacity, the pore size, and the asphaltene content, and conducts the second-level screening; measures the microfluidic sweep efficiency and the core huff and puff recovery rate, and conducts the third-level screening to determine the optimal composite nano-system. According to the principle from micro to macro and from experiment to field, the embodiment of the present invention screens out the optimal composite nano-system through three-level screening, solves the development problems of shale oil reservoirs such as the single screening standard of the existing CO2 and chemical additive system, which leads to the inability to establish a displacement relationship between wells and poor field implementation effects. At the same time, it solves the problem of poor field implementation effects caused by screening composite nanofluids only through displacement evaluation criteria such as interfacial tension and wettability evaluation.

[0019] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent specific implementation part. Description of the Drawings

[0020] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention, and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the embodiments of the present invention, but do not constitute a limitation to the embodiments of the present invention. In the accompanying drawings:

[0021] Figure 1 is a schematic flowchart of a method for determining a composite system for shale oil gas injection development provided by an embodiment of the present invention;

[0022] Figure 2 is a schematic flowchart of a shale oil gas injection development method provided by an embodiment of the present invention;

[0023] Figure 3 is a schematic flowchart of an exemplary shale oil gas injection development method; and

[0024] Figure 4 is a schematic diagram of an exemplary experimental device. Specific Embodiments

[0025] The following details the specific embodiments of the embodiments of the present invention with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the embodiments of the present invention, and are not used to limit the embodiments of the present invention.

[0026] Figure 1 is a schematic flowchart of a method for determining a composite system for shale oil gas injection development provided by an embodiment of the present invention. Please refer to Figure 1 , the method for determining the composite system may include the following steps:

[0027] Step S110: Obtain a plurality of initial composite nano-systems for synergistic carbon dioxide huff and puff development of shale oil.

[0028] Among them, the composite nano-system is a mixture, which may include: nano-particles and a dispersion system (for example, a surfactant). The composite nano-system can also be divided into a composite nano-particle system (i.e., nano-particles) and a composite nano-fluid system (i.e., a mixture of nano-particles and a liquid). Unless otherwise specified hereinafter, in the embodiments of the present invention, the corresponding oil-gas interfacial tension is measured through the composite nano-particle system, and other measurements are performed through the composite nano-liquid system.

[0029] Taking multiple initial composite nano-systems based on simulation as an example, the embodiments of the present invention are explained. For example, 30 parts of 100 ml of prepared surfactant are added to a beaker, and composite systems 1 of SiO2 and Al2O3 nanoparticles with different ratios (1:1, 2:1, 1:2, 1:3, 3:1, etc.) and composite system 2 of SiO2 and ZnO nanoparticles are added respectively. The concentration gradients of composite system 2 of nanoparticles are set to 0.2 wt%, 0.5 wt%, and 1 wt% respectively. 30 initial composite nano-systems can be obtained based on composite system 1 of nanoparticles and composite system 2 of nanoparticles. Among them, multiple copies of each initial composite nano-system can be pre-configured for subsequent multiple determinations.

[0030] Step S120: Under preset temperature and pressure conditions, perform corresponding measurements of oil-gas interfacial tension and liquid-solid interfacial wettability on the obtained multiple initial composite nano-systems, and screen out the first composite nano-system that meets the preset conditions.

[0031] Preferably, step S120 may include: for each initial composite nano-system among the multiple initial composite nano-systems, control an interfacial tension tester, introduce carbon dioxide gas into the initial composite nano-system after mixing with crude oil, and measure the oil-gas interfacial tension corresponding to the initial composite nano-system; use the self-imbibition-nuclear magnetic resonance test method to measure the relative wetting index of each initial composite nano-system and shale core, and this relative wetting index is used to characterize the corresponding liquid-solid interfacial wettability; and sort the multiple initial composite nano-systems according to the liquid-solid interfacial wettability and the oil-gas interfacial tension, and screen out the first composite nano-system.

[0032] Illustrated by way of example, for the 30 initial composite nano-systems obtained in step S110, under preset temperature and pressure conditions (for example, simulating the temperature and pressure conditions of the actual target layer, which are the temperature and pressure conditions for measurement in the embodiments of the present invention and will not be elaborated further hereinafter), the following operations are respectively performed: 1) Control the syringe of the interfacial tension tester to suck up the crude oil mixed with the initial composite nano-system, place it in the holder, and introduce carbon dioxide gas; control the syringe to drip oil downward, and start measurement when the oil droplet stably discharges. For example, when the oil droplet is in a pear shape, it indicates that the oil droplet stably discharges. Set the time to 500 s and automatically measure the interfacial tension. 2) Use the self-suction-nuclear magnetic resonance test method to measure the relative wetting index of the initial composite nano-system and the shale core. According to the values measured in 1) and 2), the 30 initial composite nano-systems are sorted. For example: If the relative wetting indices vary greatly (for example, the difference between each measured relative wetting index exceeds 0.2), they are sorted with the higher relative wetting index as the priority; if the relative wetting indices vary little, they are sorted with the lower oil-gas interfacial tension as the priority. Then, according to the sorting, the first composite nano-system is selected. For example, the top 6 in the sorting of the 30 initial composite nano-systems are the first composite nano-system. The number of the first composite nano-system can be determined according to the proportion (for example, 1 / 5) based on the number of the initial composite nano-systems, or it can be determined according to the value range of the liquid-solid interfacial wettability and the oil-gas interfacial tension. The embodiments of the present invention do not limit this.

[0033] Step S130: Based on the experimental core and crude oil after the interaction between the first composite nano-system and CO2, calculate the parameter values affecting the pore structure, pore size, and asphaltene content of the shale reservoir rock, and select the second composite nano-system.

[0034] Preferably, step S130 may include: Step S131, for each first composite nano-system, respectively perform the following operations on 1) the experimental core and crude oil under the action of CO2 and 2) the experimental core and crude oil after the interaction between this first composite nano-system and CO2: Use the digital core reconstructed by CT scanning to calculate the pore structure connectivity volume for characterizing the pore structure of the shale reservoir rock; use nuclear magnetic resonance to calculate the porosity for characterizing the pore size; and use a chromatograph analyzer to calculate the asphaltene content of the crude oil after huff and puff for characterizing the asphaltene content; Step S132, select the second composite nano-system based on the changes in the pore structure connectivity volume, porosity, and asphaltene content obtained from the two calculations in 1) and 2).

[0035] Step S130 is used to measure the influence of the composite nano - system on the pore structure and pore size of shale reservoir rocks. A second composite nano - system that can increase the connectivity of the pore structure, improve the porosity, and reduce the degree of asphaltene precipitation is selected. By way of example, for the 6 first composite nano - systems obtained in step S120, the following operations are performed on 1) the experimental core and crude oil under the action of CO2 and 2) the experimental core and crude oil after the interaction between the first composite nano - system and CO2: Using the digital core reconstructed by CT scanning, calculate the pore - structure connectivity volume used to characterize the influence on the pore structure of shale reservoir rocks; using nuclear magnetic resonance, calculate the porosity used to characterize the influence on pore size; using a chromatograph analyzer, calculate the asphaltene content of the crude oil after huff - puff used to characterize the influence on asphaltene content. Then, according to the preset weights, calculate the comprehensive value of the parameter values measured above, rank the 6 first composite nano - systems, and screen out the second composite system. For example, the weight of the percentage change in pore - structure connectivity volume calculated twice is 0.6, the weight of the percentage change in porosity calculated twice is 0.3, and the weight of the percentage change in asphaltene content is 0.1. Calculate the comprehensive value of the parameter values measured for each first composite nano - system, and screen out the second composite system. For example, 3 second composite systems with relatively large comprehensive values.

[0036] Step S140: Measure the micro - fluidic sweep efficiency and core huff - puff recovery rate of the second composite nano - system to determine the optimal composite nano - system.

[0037] Preferably, step S140 may include: Step S141, for each second composite nano - system, through an injection pump, inject the medium into the micro - channel chip at a constant speed and constant pressure. Through the confining - pressure tracking pump, circulation pump, and temperature - control system, simulate the preset temperature and pressure conditions, and screen out the third composite nano - system through the sweep efficiency of the second composite nano - system and CO2 mixture; Step S142, for each third composite nano - system, conduct a huff - puff experiment of the third composite nano - system and CO2 mixture in the shale core, determine the corresponding huff - puff recovery rate and pressure - conduction ability, and screen out the optimal composite nano - system.

[0038] Taking an example, for the three types of second composite nanosystems obtained in step S130, a high-temperature and high-pressure microfluidic experimental platform can be used to conduct CO2-composite nanosystem displacement experiments in a microchip to determine the third composite nanosystem with the best sweep efficiency. Among them, the injection pump injects the simulated medium into the microchannel chip at a constant speed and constant pressure. Through the confining pressure tracking pump, circulation pump, temperature control system, etc., the temperature and pressure conditions of the real reservoir are simulated. After the temperature and pressure are stabilized, the composite system of "CO2-second composite nanosystem" is alternately injected through the injection pump. The outlet pressure is controlled by a high-precision backpressure pump. The development time-lapse images of the displacement process in the microscale channel are recorded by a video microscope, and the experimental measurement results are quantitatively analyzed through image processing technology to obtain the sweep efficiency.

[0039] Preferably, the determination of the sweep efficiency of the second composite nanosystem and the CO2 mixture includes: recording, through a video microscope, the development time-lapse images of the process of alternately injecting the second composite nanosystem and the CO2 mixture in the microscale channel; based on the development time-lapse images, combining the distance transformation map and the medial axis skeleton map, statistically calculating the inscribed circle radius on the medial axis point by point to obtain the pore-throat distribution characterizing the microscopic model; using the development time-lapse image at the initial moment as the reference image, comparing it with the development time-lapse image at a preset moment, and determining the pore-throat activated area by means of threshold segmentation; combining the medial axis skeleton of the determined pore-throat activated area with the distance transformation map, and statistically calculating the frequency of the pore-throat radius on the medial axis of the pore-throat activated area; calculating the sweep efficiency of pore-throats of different sizes according to the ratio of the frequency of the pore-throat radius on the medial axis of the determined pore-throat activated area to the pore-throat frequency of the microscopic model; and obtaining the sweep efficiency based on the sweep efficiency of pore-throats of different sizes and the proportion of each pore-throat in the total pore-throats.

[0040] Taking an example, for the three types of second composite nanosystems obtained in step S130, experimental measurements are respectively carried out: 1) Through a video microscope, record the time-lapse images of the development process of alternately injecting the second composite nanosystem and the CO2 mixture in a microscale channel; 2) Statistically characterize the pore-throat distribution of the microscopic model. For example, by combining the distance transformation map and the optimized medial axis skeleton map, the inscribed circle radius on the medial axis skeleton is statistically analyzed point by point, and the frequency distribution characteristics of the pore-throat radius can be quantitatively obtained. According to the conversion coefficient of pixels, the pore-throat distribution is converted from pixels to the actual pore-throat size. 3) Characterize the pore-throat characteristics of the swept area. Using the image comparison method, identify the pore-throat swept area. Take the image of the oil-saturated core at the initial moment as the reference image, and then compare it with the image at a specific moment. The area with obvious differences in the image is the pore-throat swept area, and the threshold segmentation method is used in the difference map to determine the pore-throat swept area. Then, combine the medial axis skeleton of the pore-throat swept area with the distance transformation map, and count the frequency of the pore-throat radius on the medial axis of the swept area, and the swept pore-throat distribution characteristics can be statistically obtained as a histogram of the pore-throat sweep degree. According to the ratio of the frequency of the swept pore-throats to the frequency of the pore-throats in the microscopic model, the sweep efficiency of different-sized pore-throats can be calculated. 4) According to the sweep efficiency of different-sized pore-throats and the proportion of each pore-throat in the total pore-throats, the comprehensive sweep efficiency can be calculated. According to the calculated comprehensive sweep efficiency, the third composite nanosystem can be screened out. For example, two third composite nanosystems with relatively large sweep efficiencies.

[0041] Preferably, the sweep efficiency is expressed by the following formula

[0042]

[0043]

[0044] where, β i is the frequency of the swept pore-throats in the i-th pore-throat interval, η i is the frequency of the pore-throats in the microscopic model in the i-th pore-throat interval, A i is the proportion of the frequency of the i-th pore-throat interval in the total pore-throats.

[0045] Continuing with the above example, select the prepared core and dry it in an oven (for example, 6 h), cool the core, perform a vacuum treatment on the core, and saturate it with shale oil; measure the wet weight of the core, place the core in a core holder, and ensure that the artificial fracture section is horizontal. For the two selected third composite nanosystems, the following operations are respectively carried out: Pressurize the composite system of "CO2 - third composite nanosystem", and alternately inject it into the fractured core in small slugs continuously. After soaking the well for a period of time, produce from the injection well. Record the along-path pressure monitoring data and the recovery data. Sort according to the cyclic steam stimulation recovery and the pressure conduction effect, and screen out the optimal composite nanosystem.

[0046] Accordingly, based on the measurement of the oil-gas interfacial tension and liquid-solid interfacial wettability of the composite nano-system, the first-level screening is carried out in the embodiment of the present invention; the parameter values affecting the pore structure, pore size and asphaltene content of the shale reservoir rock are calculated to carry out the second-level screening; the measurement of the microfluidic sweep efficiency and core huff and puff recovery rate is carried out for the third-level screening to determine the optimal composite nano-system. According to the principle from microcosm to macrocosm and from experiment to field, the optimal composite nano-system is screened through three-level screening in the embodiment of the present invention, which solves the development problems of shale oil reservoirs such as the existing CO2 and chemical additive systems with a single screening criterion, resulting in the inability to establish a displacement relationship between wells and poor field implementation effects. At the same time, it solves the problem of poor field implementation effects caused by screening composite nanofluids only through displacement evaluation criteria such as interfacial tension and wettability evaluation.

[0047] Figure 2 It is a schematic flow chart of the shale oil gas injection development method provided by the embodiment of the present invention. Please refer to Figure 2 The shale oil gas injection development method may include the following steps:

[0048] Step S210: According to the above-mentioned determination method of the composite system for shale oil gas injection development, determine the optimal composite nano-system for synergistic CO2 huff and puff development of shale oil.

[0049] Please refer to Figure 3 For example, through three-level screening, the optimal composite nano-system is screened out, including: based on the measurement of the oil-gas interfacial tension and liquid-solid interfacial wettability of the composite nano-system, the first-level screening is carried out; the parameter values affecting the pore structure, pore size and asphaltene content of the shale reservoir rock are calculated to carry out the second-level screening; the measurement of the microfluidic sweep efficiency and core huff and puff recovery rate is carried out for the third-level screening to determine the optimal composite nano-system.

[0050] Step S220: Based on the constructed geological model of the shale oil reservoir at the well group scale, by setting the injection slug sequence, slug size, soaking time, soaking times, and alternately injecting the composite nano-system and CO2, simulate the development of the shale oil reservoir well group to determine the gas injection development strategy of the shale oil reservoir well group.

[0051] Combined with Figure 4The experimental device shown is used as an example to illustrate that based on the constructed geological model at the well group scale of the shale oil reservoir, considering factors such as the reservoir temperature and pressure system, reservoir type, and fluid characteristics, inputting the relevant parameters of the above-mentioned optimal composite nano-system, formulating relevant policies such as different sizes, different sequential slugs, soaking time, and soaking times, and evaluating the huff and puff effect. For example, first inject a large slug of the optimal composite nano-system to boost the pressure and fill the voids, and improve the local wettability of fractures, bedding planes, etc.; then inject a certain amount of CO2 for soaking and diffusion; then inject a post-composite nano-system to boost the pressure, and finally perform single-well backflow and blowout, recover and recycle the injection of the composite nano-system.

[0052] Preferably, the method for injecting gas into shale oil further includes: after the process of simulating the development of the shale oil reservoir well group is stable, calculating the corresponding CO2 storage capacity.

[0053] As an example, after the temperature and pressure of the above experimental device are stable, use the production system shunted on the injection system to measure the volume of the produced CO2 respectively. The calculation method of the CO2 storage capacity can be: CO2 storage capacity = CO2 injection volume - CO2 production volume. Using the above formula, calculate the influence of nano-particle anti-channeling on CO2 storage. (CO2 storage capacity of the composite nano-system - CO2 storage capacity of the single medium) / CO2 injection volume = CO2 storage improvement rate.

[0054] Based on experimental verification, by using the synergistic effect of the selected composite nano-system and CO2, the embodiments of the present invention can significantly restore the formation energy by means of the nano-composite fluid restricting the seepage ability of single CO2 in the fracturing fractures, reduce the amount of asphaltene precipitation by means of the synergistic extraction effect of the nano-composite fluid and CO2, and improve the CO2 sweep efficiency by 20% by means of the mobility control and synergistic diffusion effect of the nano-composite fluid on CO2; multi-medium injection reduces the CO2 consumption by 30%.

[0055] Optimizing the combination of the composite nano-system and the CO2 slug can significantly improve problems such as low oil production rate, small pressure recovery, and bottlenecks in CO2 huff and puff.

[0056] The embodiments of the present invention also provide a control device for determining a composite system for shale oil gas injection development. The control device includes: a memory, a processor, and a computer program stored on the memory and executable on the processor. The processor executes the computer program to implement the above-mentioned method for determining a composite system for shale oil gas injection development.

[0057] The embodiments of the present invention also provide a machine-readable storage medium, on which instructions are stored, and the instructions enable the machine to execute the above-mentioned method for determining a composite system for shale oil gas injection development or the above-mentioned method for shale oil gas injection development.

[0058] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of an all-hardware embodiment, an all-software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0059] The present application is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to the embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram, as well as the combination of flows and / or blocks in the flowchart and / or block diagram, can be realized by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the functions specified in Figure 1 one or more of the flows Figure 1 or blocks or the combination of blocks.

[0060] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including instruction means that implement the functions specified in Figure 1 one or more of the flows Figure 1 or blocks or the combination of blocks.

[0061] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in Figure 1 one or more of the flows Figure 1 or blocks or the combination of blocks.

[0062] In a typical configuration, a computing device includes one or more processors (CPUs), an input / output interface, a network interface, and a memory.

[0063] The memory may include non-permanent memory in the form of computer-readable media, random access memory (RAM), and / or non-volatile memory, such as read-only memory (ROM) or flash memory (flash RAM). The memory is an example of computer-readable media.

[0064] A computer-readable medium includes permanent and non-permanent, removable and non-removable media that can implement information storage by any method or technology. The information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette tapes, magnetic tape magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to store information that can be accessed by a computing device. As defined herein, a computer-readable medium does not include transitory computer-readable media, such as modulated data signals and carrier waves.

[0065] It should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0066] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the scope of the claims of the present application.

Claims

1. A method for determining a composite system for shale oil gas injection development, characterized in that, The determination method of the composite system includes: Obtaining a plurality of initial composite nano-systems for synergistic CO2 huff and puff development of shale oil; Under preset temperature and pressure conditions, measuring the corresponding oil-gas interfacial tension and liquid-solid interfacial wettability of the obtained plurality of initial composite nano-systems, and screening out the first composite nano-system that meets the preset conditions; Based on the experimental core and crude oil after the interaction between the first composite nano-system and CO2, calculating the parameter values affecting the pore structure, pore size and asphaltene content of the shale reservoir rock, and screening out the second composite nano-system; and Measuring the microfluidic sweep efficiency and core huff and puff recovery rate of the second composite nano-system to determine the optimal composite nano-system.

2. The determination method of the composite system according to claim 1, wherein The step of, under preset temperature and pressure conditions, measuring the corresponding oil-gas interfacial tension and liquid-solid interfacial wettability of the obtained plurality of initial composite nano-systems, and screening out the first composite nano-system that meets the preset conditions includes: For each initial composite nano-system among the plurality of initial composite nano-systems, controlling an interfacial tension tester, introducing carbon dioxide gas into the initial composite nano-system after mixing with crude oil, and measuring the oil-gas interfacial tension corresponding to the initial composite nano-system; Using the self-absorption-nuclear magnetic resonance test method to measure the relative wetting index of each initial composite nano-system and the shale core, and the relative wetting index is used to characterize the corresponding liquid-solid interfacial wettability; and Sorting the plurality of initial composite nano-systems according to the liquid-solid interfacial wettability and the oil-gas interfacial tension, and screening out the first composite nano-system.

3. The determination method of the composite system according to claim 1, characterized in that, The step of, based on the experimental core and crude oil after the interaction between the first composite nano-system and CO2, calculating the parameter values affecting the pore structure, pore size and asphaltene content of the shale reservoir rock, and screening out the second composite nano-system includes: For each first composite nano-system, respectively perform the following operations on the experimental core and crude oil under the action of CO2 and the experimental core and crude oil after the interaction between the first composite nano-system and CO2: Using the digital core reconstructed by CT scanning to calculate the pore structure connectivity volume for characterizing the pore structure of the shale reservoir rock; Using nuclear magnetic resonance to calculate the porosity for characterizing the pore size; and Using a chromatograph analyzer to calculate the asphaltene content of the crude oil after huff and puff for characterizing the asphaltene content; Screening out the second composite nano-system according to the changes in the pore structure connectivity volume, porosity and asphaltene content obtained by the two calculations.

4. The determination method of the composite system according to claim 1, characterized in that The step of measuring the microfluidic sweep efficiency and core huff and puff recovery rate of the second composite nano-system to determine the optimal composite nano-system includes: For each second composite nano-system, through an injection pump, injecting the medium into the microchannel chip at a constant speed and constant pressure, simulating the preset temperature and pressure conditions through a confining pressure tracking pump, a circulation pump and a temperature control system, and screening out the third composite nano-system through the sweep efficiency of the second composite nano-system and the CO2 mixture; and For each third composite nano-system, a huff-n-puff experiment of the third composite nano-system and CO2 mixture is carried out in a shale core to determine the corresponding huff-n-puff recovery rate and pressure conduction capacity, so as to screen out the optimal composite nano-system.

5. The determination method of the composite system according to claim 4, characterized in that The determination of the sweep efficiency of the second composite nano-system and CO2 mixture includes: Using a video microscope to record the developed time-lapse images during the process of alternately injecting the second composite nano-system and CO2 mixture in a micro-scale channel; Based on the developed time-lapse images, combining the distance transformation map and the medial axis skeleton map, statistically analyzing the inscribed circle radii on the medial axis point by point to obtain the pore-throat distribution characterizing the microscopic model; Taking the developed time-lapse image at the initial moment as the reference image, comparing it with the developed time-lapse image at a preset moment, and using threshold segmentation to determine the pore-throat mobilized area; Combining the medial axis skeleton of the determined pore-throat mobilized area with the distance transformation map, and statistically analyzing the frequency of pore-throat radii on the medial axis of the pore-throat mobilized area; Calculating the sweep efficiency of pore-throats of different sizes according to the ratio of the frequency of pore-throat radii on the medial axis of the determined pore-throat mobilized area to the pore-throat frequency of the microscopic model; and Obtaining the sweep efficiency based on the sweep efficiency of pore-throats of different sizes and the proportion of each pore-throat in all pore-throats.

6. The determination method of the composite system according to claim 5, wherein The sweep efficiency is expressed by the following formula Among them, β i is the frequency of the exploited pore throats in the i-th pore throat interval, η i is the frequency of the pore throats in the microscopic model of the i-th pore throat interval, A i is the proportion of the frequency of the i-th pore throat interval in the total pore throats.

7. A method for shale oil development by gas injection, characterized in that, The shale oil gas injection development method includes: Determining the optimal composite nano-system for synergistic CO2 huff-n-puff development of shale oil according to the determination method of the composite system for shale oil gas injection development described in any one of claims 1-6; and Based on the constructed geological model at the well group scale of the shale oil reservoir, simulating the development of the shale oil reservoir well group by setting the injection slug sequence, slug size, shut-in time, shut-in times, and alternately injecting the composite nano-system and CO2, so as to determine the gas injection development strategy of the shale oil reservoir well group.

8. The shale oil gas injection development method according to claim 7, characterized in that The shale oil gas injection development method further includes: Calculating the corresponding CO2 storage capacity after the process of simulating the development of the shale oil reservoir well group becomes stable.

9. A control device for determining a composite system for shale oil gas injection development, characterized in that, The control device includes: a memory, a processor, and a computer program stored on the memory and executable on the processor. The processor executes the computer program to implement the determination method of the composite system for shale oil gas injection development described in any one of claims 1-6.

10. A machine-readable storage medium, characterized in that, Instructions are stored on the machine-readable storage medium, and the instructions cause the machine to execute the determination method of the composite system for shale oil gas injection development described in any one of claims 1-6 or the shale oil gas injection development method described in any one of claims 7-8.

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