Method and system for establishing reservoir oil phase occurrence state chart based on microfluidic experiment

Abstract

This application belongs to the field of oil and gas exploration and development technology, and relates to a method and system for establishing a reservoir oil phase occurrence state map based on microfluidic experiments. The method and steps are as follows: Microfluidic experiments are conducted on a designed microfluidic chip to obtain the oil-water occurrence state in the microfluidic chip channels; the proportion of each type of oil phase occurrence state is calculated based on the duration of each type of oil phase occurrence state in a preset field of view; an occurrence state database is established based on different influencing factors of oil phase occurrence and the proportion of different oil phase occurrence states; a three-dimensional map is established based on any two influencing factors and oil phase occurrence states; different oil phase occurrence state data from the occurrence state database are plotted onto the three-dimensional map to obtain a three-dimensional distribution map of each oil phase occurrence state; based on the three-dimensional distribution map of each phase oil phase occurrence state, phase regions are divided on a two-dimensional plane coordinate axis to form a microscopic oil phase occurrence state map. This application realizes the visualization and quantitative evaluation of the oil phase occurrence state in tight reservoirs.

Description

Technical Field

[0001] This application belongs to the field of oil and gas exploration and development technology, specifically relating to a method and system for establishing reservoir oil phase occurrence state maps based on microfluidic experiments. Background Technology

[0002] The occurrence state of tight oil in tight reservoirs is complex and diverse. Factors such as flow velocity, temperature, pressure, and pore size determine the occurrence state of crude oil in the reservoir and also affect actual oil and gas exploration. Therefore, clarifying the microscopic occurrence state of tight oil in reservoirs is of great significance for revealing the occurrence mechanism of tight oil and guiding the exploration and development of tight reservoirs.

[0003] Previous methods for characterizing the occurrence state of tight oil mainly relied on indirect observation through physical experiments and imaging techniques. In terms of imaging characterization, relevant studies have used micro / nano CT scanning technology to construct three-dimensional distribution images of tight oil in pores of different sizes, realizing quantitative analysis of the occurrence space of tight oil at the micro / nano scale, and providing intuitive evidence for the study of crude oil distribution characteristics at the pore scale (see reference: Wang Xiujuan, Wang Minglei, Zhao Aibin. Microscopic characteristics of tight oil reservoir in Chang 7 of Yanchang Formation, Ordos Basin [J]. Lithologic Oil and Gas Reservoirs, 2014, 26 (03): 79-83.). In the field of fluid phase state and mobility characterization, some studies combine nuclear magnetic resonance (NMR) technology with displacement experiments. By analyzing the relaxation characteristics and displacement response of the fluid, effective distinctions between mobile and immobile oil in the reservoir have been achieved, providing key parameters for evaluating crude oil extraction efficiency (see: Li Haibo, Guo Hekun, Liu Qiang, et al. Nuclear magnetic resonance experimental study on water-driven oil in tight oil reservoirs [J]. Journal of Central South University (Natural Science Edition), 2014, 45 (12): 4370-4376.). In terms of the characterization of the correlation between pore structure and storage space, high-pressure mercury intrusion and low-temperature adsorption technologies are widely used. By measuring parameters such as pore volume, pore size distribution, and specific surface area of ​​the reservoir, the storage space characteristics of tight oil can be indirectly deduced (see: Jiang Baicai, Guo Hekun, Shen Rui, et al. Study on microscopic pore structure of tight oil reservoirs in the Ordos Basin [J]. Science, Technology and Engineering, 2015, 15 (29): 124-130.).

[0004] However, existing methods for characterizing the occurrence state of tight oil still have significant limitations. On the one hand, existing methods mostly focus on the influence of single factors (such as pore structure, temperature, or pressure) on the occurrence state of tight oil, neglecting the synergistic coupling effect of multiple factors such as flow rate, temperature, pressure, and pore size. On the other hand, existing technologies struggle to accurately define the phase transition boundaries of tight oil under different reservoir conditions, and cannot clearly define the dominant control mechanism of each factor on the occurrence state. These shortcomings make it difficult for existing characterization results to comprehensively and accurately reflect the actual occurrence state of tight oil in reservoirs, hindering in-depth revelation of the occurrence mechanism of tight oil and failing to provide reliable theoretical guidance for the efficient exploration and development of tight reservoirs. Summary of the Invention

[0005] This application addresses the problems existing in the prior art by providing a method and system for establishing a reservoir oil phase occurrence state chart based on microfluidic experiments. It comprehensively considers the coupling effect of multiple factors, combines microfluidic experiments with multi-factor quantitative analysis, and identifies and quantifies three occurrence states of "continuous oil phase, water film oil phase, and isolated oil phase" based on microscopic images to establish a three-phase chart of the fluid occurrence state in tight reservoirs, enabling real-time, dynamic, and visual observation of microscopic displacement processes and occurrence state evolution.

[0006] The first aspect of this application provides a method for establishing a reservoir oil phase occurrence state map based on microfluidic experiments, the steps of which are as follows:

[0007] Fabrication of microfluidic chips with different pore sizes;

[0008] Microfluidic experiments were conducted on the microfluidic chip to obtain the oil-water content in the channels of the microfluidic chip;

[0009] Identify the type of oil phase occurrence state based on the oil-water occurrence state;

[0010] The duration of each type of oil phase occurrence state is measured through a fixed field of view in a microfluidic chip, and the proportion of each type of oil phase occurrence state is calculated based on the duration.

[0011] A database of occurrence states was established, with different influencing factors of oil phase occurrence as independent variables and the proportion of different oil phase occurrence states under different influencing factors as dependent variables.

[0012] Choose any two influencing factors as the X and Y coordinate axes of the plane, and the oil phase occurrence state as the Z coordinate axis to establish a three-dimensional diagram;

[0013] By plotting the data of different oil phase occurrence states under the corresponding influencing factors in the occurrence state database onto a three-dimensional map, a three-dimensional distribution map of the occurrence states of each oil phase is obtained.

[0014] Based on the three-dimensional distribution map of the occurrence state of each oil phase, the phase regions of different oil phase occurrence states are divided on the two-dimensional plane coordinate axis to form a three-phase diagram of the microscopic oil phase occurrence state.

[0015] In some embodiments, the method for fabricating a microfluidic chip is as follows:

[0016] Microfluidic chips with channels are fabricated on glass substrates using microfabrication methods;

[0017] Hydrophilic or hydrophobic treatments are applied to the surface of the channels in the microfluidic chip.

[0018] In some embodiments, a method for conducting microfluidic experiments includes:

[0019] Place the microfluidic chip into the microfluidic visual chamber;

[0020] Distilled water / pure drinking water is injected into the microfluidic visual chamber to completely fill and saturate the microfluidic chip channels with distilled water / pure drinking water.

[0021] Adjust the confining pressure of the microfluidic visual chamber to the preset confining pressure, and adjust the temperature of the microfluidic visual chamber to the preset temperature;

[0022] The oil phase fluid is injected into the microfluidic visual chamber at a set flow rate, allowing the oil phase fluid to enter the microfluidic chip channel containing saturated water.

[0023] Observe the oil and water content in a fixed field of view within the channels of a microfluidic chip.

[0024] In some embodiments, the method for identifying the type of oil phase occurrence state based on the oil-water occurrence state is as follows: if the oil phase exists in a continuous state, the phenomenon of no oil-water mixing is labeled as a continuous oil phase; the linear formation of a thin film by the water phase along the edge of the oil phase is labeled as a water film oil phase; the phenomenon of the oil phase immersing in the water phase to form isolated oil droplets is labeled as an isolated oil phase.

[0025] In some embodiments, the fixed field of view is the central region of the microfluidic chip.

[0026] In some embodiments, the method for calculating the proportion of each type of oil phase occurrence state based on the duration is as follows: the proportion of the duration in the total duration of each type of oil phase occurrence state through the microfluidic chip is taken as the proportion of each type of oil phase occurrence state.

[0027] In some embodiments, a method for forming a microscopic oil phase occurrence state map includes:

[0028] At each data point in the three-dimensional distribution map, the phase of that point is defined according to the dominant state of occurrence at that data point;

[0029] Points representing the same dominant endowment state are projected onto the plane coordinate axis and connected to form a surface, thus forming a phase region;

[0030] Phase regions with different oil-water occurrence states are divided on a two-dimensional plane coordinate axis, and the boundary lines of each phase region are phase boundaries, forming a three-dimensional distribution map of the oil phase occurrence state.

[0031] In some embodiments, the influencing factors include at least two of the following: flow rate, confining pressure, temperature, and pore size.

[0032] A second aspect of this application provides a reservoir oil phase occurrence state chart establishment system, used to implement the reservoir oil phase occurrence state chart establishment method based on microfluidic experiments described in the first aspect of this application, including:

[0033] Microfabrication equipment is used to fabricate microfluidic chips with different pore sizes;

[0034] A microfluidic experimental device is used to conduct microfluidic experiments on microfluidic chips to obtain the oil-water content in the channels of microfluidic chips.

[0035] The identification module is configured to: identify the type of oil phase occurrence state based on the oil-water occurrence state;

[0036] The timing module is used to measure the duration of various types of oil phase occurrence states through a fixed field of view in the microfluidic chip;

[0037] The calculation module is configured to calculate the proportion of each type of oil phase occurrence state based on the duration.

[0038] The database construction module is configured to: establish an occurrence state database with different influencing factors of oil phase occurrence as independent variables and the proportion of different oil phase occurrence states under different influencing factors as dependent variables;

[0039] The 3D plot construction module is configured to: select any two influencing factors as the X and Y coordinate axes of the plane, and the oil phase occurrence state as the Z coordinate axis to create a 3D plot;

[0040] The plot generation module is configured to: project the data of different oil phase occurrence states under the corresponding influencing factors in the occurrence state database onto a three-dimensional map to obtain a three-dimensional distribution map of the oil phase occurrence states of each phase; based on the three-dimensional distribution map of the oil phase occurrence states of each phase, divide the phase regions of different oil phase occurrence states on the two-dimensional plane coordinate axis to form a microscopic oil phase occurrence state plot.

[0041] In some embodiments, the microfluidic experimental apparatus includes:

[0042] Microfluidic visual compartment, used to place microfluidic chips;

[0043] The constant pressure and constant speed pump unit is connected to the fluid inlet of the microfluidic chip and is used to inject distilled water / pure drinking water and oil phase fluid into the microfluidic chip at a set flow rate.

[0044] The temperature and pressure control device is used to adjust the confining pressure of the microfluidic visual chamber to the preset confining pressure and to adjust the temperature of the microfluidic visual chamber to the preset temperature.

[0045] An inverted microscope is used to observe the oil and water content in a fixed field of view within the channels of a microfluidic chip.

[0046] Compared with existing technologies, the advantages and positive effects of this application are as follows: It comprehensively considers the coupling effects of multiple factors (e.g., pore size, temperature, pressure, flow rate, etc.), and based on microfluidic experimental observations, calculates the proportion of each type of oil phase occurrence state according to the duration of different types of oil phase occurrence states in a fixed field of view. Based on the proportion of each type of oil phase occurrence state under different influencing factors, it establishes a three-phase diagram of the tight reservoir fluid occurrence state, enabling real-time, dynamic, and visual observation of the micro-displacement process and the evolution of the occurrence state. Compared to existing methods that only consider the influence of a single factor on occurrence, making it difficult to reflect the phase transition boundary and active control factors, this application reveals for the first time the influence of multi-factor coupling on the occurrence state, establishing a three-phase diagram of the tight reservoir fluid occurrence state, which can intuitively reflect the phase transition boundary and active control factors, achieving visualization and quantitative evaluation of the oil phase occurrence state in tight reservoirs. Attached Figure Description

[0047] Figure 1 This is a schematic flowchart illustrating the method for establishing a reservoir oil phase occurrence state map based on microfluidic experiments according to an embodiment of this application.

[0048] Figure 2 This is a schematic flowchart of the method for preparing a microfluidic chip according to an embodiment of this application;

[0049] Figure 3 This is a schematic diagram of the method for conducting microfluidic experiments according to an embodiment of this application;

[0050] Figure 4 This is a schematic flowchart of a method for forming a three-phase diagram of the microscopic oil phase occurrence state in an embodiment of this application.

[0051] Figure 5 A structural block diagram of the system for establishing the reservoir oil phase occurrence state diagram described in the embodiments of this application;

[0052] Figure 6 This is a schematic diagram showing the occurrence states of three oil phases in a single channel according to an embodiment of this application: continuous oil phase, water film oil phase, and isolated oil phase.

[0053] Figure 7This is a schematic diagram showing the proportion of different types of oil phase occurrence states under different confining pressures in the embodiments of this application;

[0054] Figure 8 This is a distribution diagram of the occurrence state of the continuous oil phase under various temperature and pressure conditions in the embodiments of this application;

[0055] Figure 9 This is a distribution diagram of the occurrence state of the water film oil phase under various temperature and pressure conditions in the embodiments of this application;

[0056] Figure 10 This is a distribution diagram of the occurrence state of isolated oil phases under various temperature and pressure conditions in the embodiments of this application;

[0057] Figure 11 This is a schematic diagram of the phase region of the continuous oil phase in an embodiment of this application;

[0058] Figure 12 This is a schematic diagram of the phase regions of the water film and oil phase in an embodiment of this application;

[0059] Figure 13 This is a schematic diagram of the phase region of the isolated oil phase in an embodiment of this application;

[0060] Figure 14 This is a three-phase diagram illustrating the microscopic oil phase occurrence state in an embodiment of this application.

[0061] In the figure, 101 is the microfabrication device, 102 is the microfluidic experimental device, 103 is the identification module, 104 is the timing module, 105 is the calculation module, 106 is the database construction module, 107 is the 3D graph construction module, and 108 is the graph generation module. Detailed Implementation

[0062] The present application will now be described in detail with reference to the accompanying drawings through exemplary embodiments. However, it should be understood that, without further description, elements, structures, and features in one embodiment may be advantageously incorporated into other embodiments.

[0063] See Figure 1 The first aspect of this application provides a method for establishing a reservoir oil phase occurrence state map based on microfluidic experiments, the steps of which are as follows:

[0064] S1. Fabricate microfluidic chips with different pore sizes.

[0065] In this embodiment of the application, by preparing microfluidic chips with different pore sizes (e.g., 400×200µm, 200×100µm, 20×10µm), the pore structure characteristics from nanoscale to microscale in dense reservoirs can be accurately simulated, solving the technical problem that traditional physical experiments cannot reproduce the real pore environment of reservoirs.

[0066] In some embodiments of this application, see Figure 2 The method for preparing microfluidic chips is as follows:

[0067] S11. A microfluidic chip with channels is fabricated on a glass substrate using microfabrication methods;

[0068] S12. Perform hydrophilic or hydrophobic treatment on the surface of the pores of the microfluidic chip.

[0069] The wettability (hydrophilic or hydrophobic) of the pore walls in tight reservoirs is one of the key factors determining the oil phase occurrence state. In this embodiment, a microfluidic chip prepared by a combination of glass substrate micromachining and directional hydrophilic / hydrophobic modification of the pore surface can accurately match the core requirements of simulating the oil phase occurrence state of reservoirs. Specifically, on the one hand, by treating the pore surface of the glass chip with hydrophilic or hydrophobic properties, the wettability parameters of the pore wall can be adjusted as needed, making it highly consistent with the actual wettability characteristics of the target reservoir. This solves the technical defects of traditional glass chip surfaces with single wettability, which cannot match the pore characteristics of different types of reservoirs, and significantly improves the simulation accuracy of microfluidic experiments on the real reservoir environment, providing a more realistic experimental platform for observing the oil phase occurrence state. On the other hand, the directional hydrophilic / hydrophobic modified pore surface can generate specific interactions with the oil and water phases. In hydrophilically modified pores, the aqueous phase readily adheres to the wall surface to form a water film, while the oil phase exists as discrete oil droplets or columnar oil streams. In hydrophobically modified pores, the oil phase readily adsorbs onto the wall surface, while the aqueous phase exhibits a discrete distribution. This differentiated occurrence pattern has clear boundaries and distinctive characteristics, effectively solving the problems of blurred oil-water interface and difficulty in accurately identifying the occurrence state in traditional unmodified pores. It significantly improves the observation and identification accuracy of oil phase occurrence types.

[0070] S2. Conduct microfluidic experiments on the microfluidic chip to obtain the oil-water content in the microfluidic chip channels.

[0071] In this embodiment of the application, through microfluidic experiments, the oil-water occurrence state in the microfluidic chip channel can be directly observed, and the distribution morphology, phase boundary and migration law of the oil phase under different pore size conditions can be clearly captured. This provides a direct and reliable observation basis for the identification of the oil phase occurrence state type, and greatly improves the accuracy and objectivity of the occurrence state identification.

[0072] In some embodiments of this application, see Figure 3 Methods for conducting microfluidic experiments include:

[0073] S21. Place the microfluidic chip into the microfluidic visual chamber;

[0074] S22. Inject distilled water / pure drinking water into the microfluidic visual chamber so that the microfluidic chip channels are completely filled with distilled water / pure drinking water and reach a saturated state.

[0075] S23. Adjust the confining pressure of the microfluidic visual chamber to the preset confining pressure, and adjust the temperature of the microfluidic visual chamber to the preset temperature;

[0076] S24. Inject the oil phase fluid into the microfluidic visual chamber at a set flow rate, so that the oil phase fluid enters the microfluidic chip channel containing saturated water.

[0077] S25. Observe the oil and water content in the fixed field of view in the microfluidic chip channel.

[0078] In this embodiment, on the one hand, the experiment first saturates the chip channels with pure water and then injects oil phase fluid, accurately reproducing the initial state of the real oil-water distribution in tight reservoirs, characterized by "water locking pores and oil phase filling." Simultaneously, by adjusting the confining pressure and temperature of the microfluidic visible chamber to preset parameters, the temperature and pressure conditions of reservoirs at different burial depths can be matched as needed. This solves the technical shortcomings of traditional experiments in simultaneously simulating reservoir temperature and pressure, pore wettability, and oil-water distribution characteristics, significantly improving the accuracy of the experiment in replicating the real reservoir environment. On the other hand, the experimental procedure standardizes key steps such as chip loading, water phase saturation, temperature and pressure control, and oil phase injection flow rate, allowing for precise control and recording of parameters for each operation step. This design effectively avoids problems such as temperature and pressure fluctuations and uneven oil phase injection rates caused by the randomness of traditional experiments, ensuring that different batches of experiments are conducted under the same control conditions. This significantly improves the consistency and repeatability of oil phase occurrence state observation data, providing a stable variable control basis for subsequent calculations of the occurrence state proportion.

[0079] S3. Identify the type of oil phase occurrence state based on the oil-water occurrence state.

[0080] In some embodiments of this application, the method for identifying the type of oil phase occurrence state based on the oil-water occurrence state is as follows: if the oil phase exists in a continuous state, the phenomenon of no oil-water mixing is labeled as a continuous oil phase; the linear formation of a thin film by the water phase along the edge of the oil phase is labeled as a water film oil phase; the phenomenon of the oil phase immersing in the water phase to form isolated oil droplets is labeled as an isolated oil phase.

[0081] In this embodiment, based on the coexistence morphological characteristics of the oil and water phases, the oil phase occurrence states are clearly classified and labeled using "continuous distribution without miscibility," "water phase forming a film along the oil phase edge," and "oil phase as isolated droplets dispersed in the water phase" as core criteria. This identification standard is clear and quantifiable, relying entirely on objective morphological characteristics observed experimentally. It avoids the identification bias caused by differences in human experience in traditional classification methods, significantly improving the consistency and accuracy of occurrence state identification results among different experimental personnel and different batches of experiments, providing a unified and reliable classification basis for subsequent proportion calculations. Simultaneously, the defined three categories of oil phase occurrence states cover the main occurrence forms of oil phase in tight reservoirs within the pore space, and the boundaries between each category are clear and without overlap, enabling comprehensive classification of all oil phase occurrence forms within the observation field. This solves the problems of category omission and blurred boundaries existing in traditional classification methods, ensuring that each oil-water coexistence morphology observed experimentally corresponds to a clear occurrence state type, guaranteeing the completeness and validity of subsequent proportion calculation data.

[0082] S4. Measure the duration of each type of oil phase occurrence state through a fixed field of view in the microfluidic chip, and calculate the proportion of each type of oil phase occurrence state based on the duration.

[0083] In this embodiment, an innovative approach is introduced, using a duration parameter of a fixed field of view to represent the oil phase occurrence state. Based on this parameter, the proportion of different types of oil phase occurrence states is calculated, establishing a standardized quantitative characterization system. This method overcomes the limitations of traditional characterization methods that rely on manual statistics or indirect calculations, effectively avoiding subjective errors and achieving accurate quantification of the proportion of oil phase occurrence states under different influencing factors. This provides high-precision and repeatable basic data support for subsequent database construction and plotting.

[0084] In some embodiments of this application, the fixed field of view is the central region of the microfluidic chip.

[0085] The central region of the microfluidic chip exhibits optimal flow field stability, effectively mitigating abnormal oil phase occurrence caused by fluid disturbances and pressure surges at the chip's inlet and outlet. Furthermore, the pore size uniformity and surface modification consistency in this region are higher than those in the edge regions. In this embodiment, setting the central region of the microfluidic chip as a fixed field of view ensures that oil phase observations of different batches and pore sizes are conducted under the same flow field environment. This overcomes the technical shortcomings of inconsistent observation conditions and lack of data comparability caused by traditional random field selection, significantly improving the accuracy and reliability of the oil phase occurrence ratio calculation results.

[0086] In some embodiments of this application, the method for calculating the proportion of each type of oil phase occurrence state based on the duration is as follows: the proportion of the duration in the total duration of each type of oil phase occurrence state through the microfluidic chip is taken as the proportion of each type of oil phase occurrence state.

[0087] In this embodiment, the duration of the oil phase passing through a fixed field of view is used as the core quantitative indicator. The "time percentage" is directly equated with the "occurrence state percentage," and the calculation is completed entirely based on objective data recorded in real time during the experiment, eliminating the need for manual estimation or judgment of the distribution range of the occurrence state. This solves the data deviation problem caused by subjective judgment differences among observers in traditional manual statistical methods, significantly improving the objectivity and accuracy of the calculation results for the occurrence state percentage of different types of oil phases, providing high-precision data support for subsequent database construction and plotting. Simultaneously, based on the calculation logic of "duration percentage," a unified quantification of the occurrence state percentage under different experimental conditions (such as aperture, temperature, pressure, flow rate, etc.) can be achieved. Regardless of how the chip channel size or fluid parameters are adjusted, the percentage conversion is based on the "total duration," forming a universal and standardized calculation paradigm. This overcomes the limitation of traditional methods where data cannot be compared horizontally due to inconsistent calculation methods, ensuring the consistency and comparability of experimental data from different batches and with different parameters, laying a data foundation for the analysis of occurrence patterns under the coupling effect of multiple factors.

[0088] S5. Using different influencing factors of oil phase occurrence as independent variables and the proportion of different oil phase occurrence states under different influencing factors as dependent variables, establish an occurrence state database.

[0089] In this embodiment, a systematic database of oil phase occurrence states is established, using factors influencing oil phase occurrence (e.g., flow rate, temperature, pressure, pore size, etc.) as independent variables and the proportion of different occurrence states as dependent variables. This database integrates the oil phase occurrence laws under the coupled effects of multiple factors, changing the existing research model that only considers a single factor. It provides a data foundation for comprehensively revealing the reservoir oil phase occurrence mechanism and fills the gap in the existing technology of lacking a unified phase diagram expression system.

[0090] Specifically, the influencing factors include at least two of the following: flow rate, confining pressure, temperature, and pore size.

[0091] S6. Select any two influencing factors as the X and Y coordinate axes of the plane, and the oil phase occurrence state as the Z coordinate axis to establish a three-dimensional diagram.

[0092] In this embodiment, by selecting any two influencing factors (such as pore size-temperature, temperature-pressure, flow rate-pressure, etc.) as planar coordinate axes and the oil phase occurrence state as the Z-axis to construct a three-dimensional graph, the distribution characteristics of the oil phase occurrence state under multi-factor coupling can be intuitively presented. The spatial coordinate system of the three-dimensional graph can accurately correspond to the one-to-one mapping relationship between "combination of influencing factors - occurrence state type". By locating the coordinates and density analysis of data points in three-dimensional space, the proportion range and distribution probability of a specific oil phase occurrence state under different influencing factors can be quantified. This solves the technical problem in traditional technology that the influence law of multiple factors is difficult to express concretely and the interaction mechanism of different factors is vague. It enables researchers to quickly identify the sensitive range of oil phase occurrence state changes with two factors, providing a clear visual analysis carrier for revealing the occurrence mechanism.

[0093] S7. Plot the data of different oil phase occurrence states under the corresponding influencing factors in the occurrence state database onto the three-dimensional map to obtain the three-dimensional distribution map of the occurrence state of each oil phase.

[0094] In this embodiment, the discrete data of "combination of two influencing factors - proportion of oil phase occurrence state" in the occurrence state database are precisely projected onto a three-dimensional coordinate system with the influencing factors as the X and Y axes and the oil phase occurrence state as the Z axis, which can directly generate a three-dimensional spatial distribution map of the oil phase occurrence state. This distribution map can intuitively show the spatial distribution location, proportion gradient and clustering area of ​​various oil phase occurrence states under the coupling effect of different influencing factors. It solves the technical deficiency of traditional databases that can only present isolated data and are difficult to intuitively reflect the correlation between multiple factors and occurrence states, allowing researchers to quickly identify the dominant distribution range and changing trend of occurrence states. In the three-dimensional distribution map, the data points of different oil phase occurrence states show obvious clustering characteristics in space. Data points of the same type of occurrence state form a continuous spatial distribution surface, and the spatial boundary line of different types of data points is the phase transition boundary of the occurrence state. This boundary is generated based on real experimental quantitative data and is objective and accurate. It breaks through the limitations of traditional phase boundary division, which relies on experience and is highly subjective. It provides a clear and quantitative spatial boundary basis for the subsequent division of phase regions with different oil phase occurrence states on a two-dimensional plane, ensuring the scientificity and reliability of the phase region division results.

[0095] S8. Based on the three-dimensional distribution map of the occurrence state of each oil phase, the phase regions of different oil phase occurrence states are divided on the two-dimensional plane coordinate axis to form a three-phase diagram of the microscopic oil phase occurrence state.

[0096] In this embodiment, a three-dimensional distribution map is used to divide phase regions of different occurrence states into a two-dimensional plane, forming a three-phase map of the microscopic oil phase occurrence state. This accurately defines the phase transition boundaries of different oil phase occurrence states and clarifies the dominant control mechanism of various influencing factors on the oil phase occurrence state. Compared with the shortcomings of existing technologies that are difficult to intuitively reflect phase transition boundaries, the map constructed in this application can directly provide visualized theoretical guidance for target area selection and development scheme optimization in tight reservoir exploration and development.

[0097] In some embodiments of this application, see Figure 4 Methods for forming three-phase diagrams of the microscopic oil phase occurrence state include:

[0098] S81. For each data point in the three-dimensional distribution map, define the phase of the point according to the dominant assignment state at that data point.

[0099] S82. Project points representing the same dominant endowment state onto the plane coordinate axis and connect them to form a surface, thus forming a phase region;

[0100] S83. Divide the phase regions with different oil and water occurrence states on the two-dimensional plane coordinate axis. The boundary line of each phase region is the phase boundary, forming a three-phase diagram of the oil phase occurrence state.

[0101] In this embodiment, a systematic process of defining the dominant occurrence state, projecting data points onto a plane, and delineating phase boundaries is employed to construct a three-phase map of the microscopic oil phase occurrence state, thus transforming the reservoir oil phase occurrence law from a three-dimensional data model to a practical two-dimensional map. The final three-phase map visually presents the correspondence between "dual influencing factors and dominant occurrence state" on a two-dimensional plane. Researchers or field technicians can directly and quickly locate the phase region of the target reservoir based on actual parameters (such as any combination of two parameters like pore size, temperature, pressure, and flow velocity) on the map, determining the dominant type of oil phase occurrence. Compared to traditional charts or empirical maps without clear phase region delineation, this application uses the dominant occurrence state of each data point in the three-dimensional distribution map as the core basis, connecting them through projection to form phase regions and delineate phase boundaries, transforming the phase transition law into intuitive and quantifiable two-dimensional boundary lines. It overcomes the shortcomings of traditional technologies that struggle to clearly define critical conditions for phase transitions and rely on empirical judgment for phase region division. It precisely defines the dominant distribution ranges of continuous oil phase, water film oil phase, and isolated oil phase under different combinations of influencing factors, providing a clear quantitative standard for determining the dominant type of oil phase occurrence under specific reservoir conditions.

[0102] The method for establishing reservoir oil phase occurrence state charts based on microfluidic experiments described in this application achieves a breakthrough in reservoir oil phase occurrence state from qualitative observation to quantitative modeling, and from single-factor analysis to multi-factor coupled characterization, through microfluidic chip simulation, quantitative characterization of occurrence state, and multi-dimensional chart construction. The constructed three-phase chart can intuitively reflect phase transition boundaries and active control factors, realizing the visualization and quantitative evaluation of oil phase occurrence state in tight reservoirs.

[0103] A second aspect of this application provides a system for establishing a reservoir oil phase occurrence state map, used to implement the method for establishing a reservoir oil phase occurrence state map described in the first aspect of this application. See also... Figure 5 The reservoir oil phase occurrence state map establishment system 100 includes:

[0104] Microfabrication equipment 101 is used to prepare microfluidic chips with different pore sizes;

[0105] The microfluidic experimental device 102 is used to conduct microfluidic experiments on microfluidic chips to obtain the oil-water content state in the channels of microfluidic chips.

[0106] The identification module 103 is configured to: identify the type of oil phase occurrence state based on the oil-water occurrence state;

[0107] The timing module 104 is used to measure the duration of various types of oil phase occurrence states through a fixed field of view in the microfluidic chip;

[0108] The calculation module 105 is configured to calculate the proportion of each type of oil phase occurrence state based on the duration.

[0109] The database construction module 106 is configured to: establish an occurrence state database with different influencing factors of oil phase occurrence as independent variables and the proportion of different oil phase occurrence states under different influencing factors as dependent variables.

[0110] The 3D graph construction module 107 is configured to: select any two influencing factors as the X and Y coordinate axes of the plane, and the oil phase occurrence state as the Z coordinate axis to build a 3D graph;

[0111] The plot generation module 108 is configured to: project the data of different oil phase occurrence states under the corresponding influencing factors in the occurrence state database onto a three-dimensional map to obtain a three-dimensional distribution map of the oil phase occurrence states of each phase; based on the three-dimensional distribution map of the oil phase occurrence states of each phase, divide the phase regions of different oil phase occurrence states on the two-dimensional plane coordinate axis to form a microscopic oil phase occurrence state plot.

[0112] The microfabrication device 101 can prepare microfluidic chips with different pore sizes, enabling precise simulation of the pore structure characteristics of different types of reservoirs (such as small-pore tight reservoirs, medium-pore conventional reservoirs, and large-pore fractured reservoirs). Compared with the limitations of traditional experiments that rely on natural cores, standardized chips offer strong repeatability, avoiding experimental errors caused by the inhomogeneity of the pore structure of natural cores, and providing a unified and controllable experimental platform for the subsequent precise observation of the oil phase occurrence state.

[0113] The microfluidic experimental device 102 can intuitively present the microscopic morphology of the oil-water occurrence state in the chip channel (such as continuous oil phase state, water film oil phase state, continuous oil phase state, etc.) by fluid driving, temperature and pressure control and microscopic observation of the microfluidic chip.

[0114] The identification module 103 accurately distinguishes different oil phase occurrence types based on the observed oil-water occurrence characteristics, avoiding subjective errors in manual identification.

[0115] The timing module 104 and the calculation module 105 work together to quantify the proportion of different states by measuring the duration of each type of oil phase occurrence over a fixed field of view, thus achieving a leap from "qualitative description" to "quantitative analysis." Compared to the rough classification of oil phase occurrence states in traditional methods, the quantitative data of this system better reflects the true laws of reservoir oil phase occurrence, providing accurate data support for reservoir evaluation.

[0116] The database construction module 106 establishes a structured reservoir occurrence state database by using influencing factors of oil phase occurrence (such as pore size, temperature, pressure, and flow rate) as independent variables and the proportion of oil phase occurrence states under different influencing factors as dependent variables. This database enables the classified storage, rapid retrieval, and cross-comparison of multiple sets of experimental data, solving the problems of scattered and difficult-to-reuse traditional experimental data, and providing a data foundation for subsequent in-depth research on reservoir oil phase occurrence mechanisms.

[0117] The 3D map construction module 107 and the map generation module 108 work together to project database data onto a 3D coordinate system (with the two influencing factors as the X and Y axes and the oil phase occurrence state as the Z axis) to form a 3D distribution map. This map visually displays the distribution characteristics of the oil phase occurrence state under the coupled effects of different influencing factors. Furthermore, it divides the phase regions in a 2D plane to generate a microscopic oil phase occurrence state map. This map can be directly used to guide the evaluation and development scheme design of actual reservoirs. For example, the map can quickly determine the dominant oil phase occurrence state of a target reservoir under specific temperature, pressure, and porosity conditions, providing a visual and operable technical basis for improving oil and gas recovery.

[0118] In some embodiments of this application, the micromachining device 101 adopts existing conventional micromachining equipment (including cutting machines, lithography machines, etc.).

[0119] In some embodiments of this application, the microfluidic experimental apparatus 102 includes a microfluidic viewing chamber, a constant pressure and constant speed pump unit, a temperature and pressure control unit, and an inverted microscope. The microfluidic viewing chamber is used to hold the microfluidic chip. The constant pressure and constant speed unit is connected to the fluid inlet of the microfluidic chip and is used to inject distilled water / pure drinking water and oil phase fluid into the microfluidic chip at a set flow rate. The temperature and pressure control unit is used to adjust the confining pressure of the microfluidic viewing chamber to a preset confining pressure and to adjust the temperature of the microfluidic viewing chamber to a preset temperature. The inverted microscope is used to observe the oil-water distribution state in a fixed field of view within the channels of the microfluidic chip.

[0120] In this embodiment of the application, the microfluidic experimental device 102 can intuitively present the microscopic morphology of the oil and water occurrence state in the chip channel (such as continuous oil phase state, water film oil phase state, continuous oil phase state, etc.) by fluid driving, temperature and pressure control and microscopic observation of the microfluidic chip.

[0121] Specifically, the microfluidic visual chamber uses a transparent quartz glass body and a sealing cover, with a sealing ring used between the body and the cover. Inside the chamber, there are slot-type fixing platforms that accommodate microfluidic chips of different sizes. The fixing platform is equipped with adjustable positioning buckles to ensure that the microfluidic chips do not shift or leak during the experiment.

[0122] Specifically, the constant pressure and constant speed pump unit includes a constant pressure and constant speed pump and a fluid delivery channel. The inlet of the constant pressure and constant speed pump is connected to the fluid delivery channel, and the outlet of the constant pressure and constant speed pump is connected to the fluid inlet of the microfluidic chip through a pipeline. The fluid delivery channel adopts a dual-fluid channel design. The first fluid channel is connected to a distilled water / purified drinking water storage tank, and the second fluid channel is connected to an oil phase fluid storage tank. An electromagnetic reversing valve is equipped between the two channels to achieve single fluid injection or alternating dual fluid injection.

[0123] Specifically, the temperature and pressure control device includes a confining pressure adjustment module, a temperature adjustment module, and a control unit.

[0124] The confining pressure adjustment module includes: a high-pressure nitrogen cylinder, which is connected to the confining pressure interface of the microfluidic visual chamber via a gas supply pipeline; a pressure regulating valve, which is located on the gas supply pipeline; and a pressure sensor, which is located at the confining pressure interface and is used to detect the confining pressure of the microfluidic visual chamber.

[0125] The temperature control module includes: a heating element located at the bottom of the microfluidic visual chamber for heating the microfluidic visual chamber; and a temperature sensor located inside the microfluidic visual chamber for detecting the temperature of the microfluidic visual chamber.

[0126] The control unit is connected to the pressure regulating valve, the heating element, the pressure sensor, and the temperature sensor respectively. The control unit is configured to: open the pressure regulating valve when adjusting the confining pressure; close the pressure regulating valve when the confining pressure received from the pressure sensor reaches the preset confining pressure; control the heating element to heat when adjusting the temperature; and stop heating the heating element when the temperature received from the temperature sensor reaches the preset temperature.

[0127] The reservoir oil phase occurrence state map establishment system described in this application, through multi-module collaborative linkage, breaks through the technical bottleneck of "macroscopic experiments as the main method, vague microscopic characterization, low data quantification, and insufficient map practicality" in traditional reservoir oil phase occurrence state research, and realizes accurate characterization, quantitative analysis, visual modeling and standardized map output of reservoir oil phase occurrence state.

[0128] To verify the effectiveness of the method and system for establishing reservoir oil phase occurrence state maps based on microfluidic experiments described in the above embodiments of this application, the following specific embodiments are used for illustration.

[0129] Example: A microfluidic chip with a pore size of 200×100µm is used as an example.

[0130] A glass microfluidic chip with pores of 200×100µm and a size of 76mm×76mm was fabricated. The microfluidic chip was placed in a microfluidic viewing chamber, which was then sealed. The initial temperature was set to 25℃ and the initial confining pressure to 3MPa.

[0131] Adjust the inverted microscope to the fixed field of view of the microfluidic chip. First, saturate the channels with water at a flow rate of 1 ml / min, then inject No. 0 kerosene at a flow rate of 0.05 ml / min. Record the fluid state using image acquisition and analysis software (e.g., CapStudio). Under experimental conditions of a flow rate of 0.05 ml / min, a temperature of 25℃, a confining pressure of 3 MPa, and a pore size of 200 × 100 µm, observe and identify the oil-water state types in the microfluidic chip channels within the fixed field of view, namely continuous oil phase, water film oil phase, and isolated oil phase (see [reference]). Figure 6 ).

[0132] Under a fixed field of view, the duration for which the continuous oil phase, the water film oil phase, and the isolated oil phase pass through the fixed field of view is measured. The proportion of the continuous oil phase, the water film oil phase, and the isolated oil phase in the total duration is calculated based on the duration (see [reference]). Figure 7 ), which serves as quantitative data for the assigned state.

[0133] Temperature and confining pressure were selected as the two influencing factors for the experiment. The experiment was repeated under different temperature and pressure combinations of 25~80℃ and 3~8MPa. Based on the oil phase occurrence state data under different experimental conditions, an oil phase occurrence state database was established (as shown in Table 1).

[0134] Table 1. Percentage of oil phase occurrence states under different temperature and pressure conditions

[0135]

[0136] Temperature was chosen as the X-axis, confining pressure as the Y-axis, and oil phase occurrence state as the Z-axis. Data on the three types of oil phase occurrence states under various temperature and pressure conditions were plotted on a 3D graph to create distribution maps of the continuous oil phase occurrence states (see...). Figure 8 Distribution diagram of the occurrence state of the water film and oil phase (see) Figure 9 Distribution diagram of the occurrence state of isolated oil phases (see) Figure 10 The phase at each data point is defined based on the dominant occurrence state. Points representing the same dominant occurrence state are projected onto a plane coordinate axis and connected to form a surface, creating a phase region of continuous oil phase (see [link]). Figure 11 Phase regions of water film and oil phase (see...) Figure 12 Phase regions of isolated oil phases (see...) Figure 13 ).

[0137] On a two-dimensional plane coordinate axis, three regions are divided into "continuous oil phase region," "water film oil phase region," and "isolated oil phase region." Within each region, the content of the dominant occurrence state is indicated by color. The boundary lines between the phase regions are the phase boundaries, ultimately forming a three-phase diagram of the microscopic oil phase occurrence state (see...). Figure 14 ), Figure 14 In the diagram, A represents the continuous oil phase region, B represents the water film oil phase region, and C represents the isolated oil phase region.

[0138] The above embodiments are used to explain this application, not to limit it. Any modifications and changes made to this application within the spirit and scope of the claims shall fall within the protection scope of this application.

Claims

1. A method for establishing a reservoir oil phase occurrence state map based on microfluidic experiments, characterized in that, The steps include: Fabrication of microfluidic chips with different pore sizes; Microfluidic experiments were conducted on a microfluidic chip to obtain the oil-water content in the chip's channels. The methods included: placing the microfluidic chip into a microfluidic viewing chamber; injecting distilled water / purified drinking water into the chamber until the chip channels were completely filled and saturated; adjusting the confining pressure and temperature of the chamber to a preset level; injecting an oil phase fluid into the chamber at a set flow rate, allowing the fluid to enter the water-saturated channels; and observing the oil-water content in a fixed field of view within the microfluidic chip channels. The type of oil phase occurrence is determined based on the oil-water occurrence state. The method for determining the type of oil phase occurrence based on the oil-water occurrence state is as follows: if the oil phase exists in a continuous state and there is no phenomenon of oil-water mixing, it is labeled as a continuous oil phase; if the water phase forms a thin film along the edge of the oil phase, it is labeled as a water film oil phase; if the phenomenon of the oil phase immersing in the water phase to form isolated oil droplets is labeled as an isolated oil phase. The duration of each type of oil phase occurrence state is measured through a fixed field of view in a microfluidic chip, and the proportion of each type of oil phase occurrence state is calculated based on the duration. A database of occurrence states was established, with different influencing factors of oil phase occurrence as independent variables and the proportion of different oil phase occurrence states under different influencing factors as dependent variables. Choose any two influencing factors as the X and Y coordinate axes of the plane, and the oil phase occurrence state as the Z coordinate axis to establish a three-dimensional diagram; By plotting the data of different oil phase occurrence states under the corresponding influencing factors in the occurrence state database onto a three-dimensional map, a three-dimensional distribution map of the occurrence states of each oil phase is obtained. Based on the three-dimensional distribution map of the occurrence state of each oil phase, the phase regions of different oil phase occurrence states are divided on the two-dimensional plane coordinate axis to form a three-phase diagram of the microscopic oil phase occurrence state.

2. The method for establishing a reservoir oil phase occurrence state chart based on microfluidic experiments as described in claim 1, characterized in that, The method for fabricating microfluidic chips is as follows: Microfluidic chips with channels are fabricated on glass substrates using microfabrication methods; Hydrophilic or hydrophobic treatments are applied to the surface of the channels in the microfluidic chip.

3. The method for establishing a reservoir oil phase occurrence state chart based on microfluidic experiments as described in claim 1, characterized in that, The fixed field of view is the central region of the microfluidic chip.

4. The method for establishing a reservoir oil phase occurrence state chart based on microfluidic experiments as described in claim 1, characterized in that, The method for calculating the proportion of each type of oil phase occurrence state based on the duration is as follows: the proportion of the duration in the total duration of each type of oil phase occurrence state through the microfluidic chip is taken as the proportion of each type of oil phase occurrence state.

5. The method for establishing a reservoir oil phase occurrence state map based on microfluidic experiments as described in claim 1, characterized in that, Methods for forming three-phase diagrams depicting the microscopic oil phase occurrence state include: At each data point in the three-dimensional distribution map, the phase of that point is defined according to the dominant state of occurrence at that data point; Points representing the same dominant endowment state are projected onto the plane coordinate axis and connected to form a surface, thus forming a phase region; Phase regions with different oil-water occurrence states are divided on a two-dimensional plane coordinate axis, and the boundary lines of each phase region are phase boundaries, forming a three-phase diagram of the oil phase occurrence state.

6. The method for establishing a reservoir oil phase occurrence state map based on microfluidic experiments as described in claim 1, characterized in that, The influencing factors include at least two of the following: flow rate, confining pressure, temperature, and orifice size.

7. A system for establishing a reservoir oil phase occurrence state chart, used to implement the method for establishing a reservoir oil phase occurrence state chart based on microfluidic experiments as described in any one of claims 1 to 6, characterized in that, include: Microfabrication equipment is used to fabricate microfluidic chips with different pore sizes; A microfluidic experimental device is used to conduct microfluidic experiments on microfluidic chips to obtain the oil-water content in the channels of microfluidic chips. The identification module is configured to: identify the type of oil phase occurrence state based on the oil-water occurrence state; The timing module is used to measure the duration of various types of oil phase occurrence states through a fixed field of view in the microfluidic chip; The calculation module is configured to calculate the proportion of each type of oil phase occurrence state based on the duration. The database construction module is configured to: establish an occurrence state database with different influencing factors of oil phase occurrence as independent variables and the proportion of different oil phase occurrence states under different influencing factors as dependent variables; The 3D plot construction module is configured to: select any two influencing factors as the X and Y coordinate axes of the plane, and the oil phase occurrence state as the Z coordinate axis to create a 3D plot; The plot generation module is configured to: project the data of different oil phase occurrence states under the corresponding influencing factors in the occurrence state database onto a three-dimensional map to obtain a three-dimensional distribution map of the oil phase occurrence states of each phase; based on the three-dimensional distribution map of the oil phase occurrence states of each phase, divide the phase regions of different oil phase occurrence states on the two-dimensional plane coordinate axis to form a microscopic oil phase occurrence state plot.

8. The reservoir oil phase occurrence state map establishment system as described in claim 7, characterized in that, The microfluidic experimental device includes: Microfluidic visual compartment, used to place microfluidic chips; The constant pressure and constant speed pump unit is connected to the fluid inlet of the microfluidic chip and is used to inject distilled water / pure drinking water and oil phase fluid into the microfluidic chip at a set flow rate. The temperature and pressure control device is used to adjust the confining pressure of the microfluidic visual chamber to the preset confining pressure and to adjust the temperature of the microfluidic visual chamber to the preset temperature. An inverted microscope is used to observe the oil and water content in a fixed field of view within the channels of a microfluidic chip.

Images