Equivalent discrete model construction method and system for multi-field coupling behavior of porous media

Abstract

The present invention belongs to the field of porous media modeling, and provides an equivalent discrete model construction method and system for the multi-field coupling behavior of porous media. The method includes obtaining porous media particle information and pore structure characteristic parameters; according to the particle size and distribution in the porous media particle information, each particle is mapped to a corresponding site at the center of a truncated octahedron unit cell and connected by a bond, and then the particle component characteristics in the porous media particle information are distributed to the bonds in various directions and regions of the corresponding truncated octahedron unit cell center, and the mineral particles are continuously distributed to the corresponding truncated octahedron unit cells until the cumulative volume fraction of all truncated octahedron unit cells is equal to the experimental measurement value; the pore structure characteristic parameters are randomly distributed to the face centers of each truncated octahedron unit cell of a certain size, and the throat is used to connect the adjacent face centers until the cumulative pore throat volume in all truncated octahedron unit cells reaches the experimental measurement value.

Description

Technical Field

[0001] The present invention belongs to the field of porous medium modeling, and in particular relates to a method and system for constructing an equivalent discrete model of multi-field coupling behavior of porous media. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] During the exploitation of CO2, hydrogen and oil and gas resources, or the geological disposal and service of nuclear waste, the storage medium will be affected by multiple coupling effects such as temperature, stress, seepage and chemistry. As the main channel for material migration in the rock mass, the pores and their conductivity play a vital role in engineering safety and mining efficiency. Therefore, correctly understanding the material migration mechanism of the storage medium is of great significance to strengthening engineering safety design.

[0004] The macroscopic model based on the assumption of continuous medium ignores the microscopic pore structure characteristics of geotechnical media, generalizes the complex microscopic characteristics of geotechnical media by setting macroscopic parameters, and cannot reflect the multiphase seepage, retardation, dispersion, fingering effect and other phenomena at the microscopic scale. Different from the assumption that porous media are ideal continua in traditional macroscopic models, the pore structure model distinguishes the solid phase skeleton in the porous media and the pore space between the solid phase skeletons, and analyzes and calculates the seepage problem based on the complex pore structure in the porous media. The early three-dimensional network model was based on a cubic lattice, and the pore coordination number was constant up to 6, while the pore coordination number of actual porous media may be greater than 6. Based on this, Roof et al. proposed a model with 26 pore coordination numbers, but it seems difficult to achieve physically; Vogel et al. proposed an equivalent pore network model based on rhombic dodecahedron. This method provides the maximum pore coordination of 12 equal-length throats, but the representation of the volume around the pores is poor. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method and system for constructing an equivalent discrete model of the multi-field coupling behavior of porous media, which is based on the equivalent discrete model of truncated octahedron to simulate the thermal-hydraulic-mechanical-chemical multi-field coupling behavior of porous media.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] The first aspect of the present invention provides a method for constructing an equivalent discrete model of multi-field coupling behavior of porous media.

[0008] In one or more embodiments, a method for constructing an equivalent discrete model of multi-field coupled behavior of porous media is provided, comprising:

[0009] Obtaining porous medium particle information and pore structure characteristic parameters; wherein the porous medium particle information includes the size, distribution and composition characteristics of mineral particles;

[0010] According to the size and distribution of mineral particles, each mineral particle is mapped to the center position of a truncated octahedral unit cell and connected by bonds. Then, the composition characteristics of the particles in the porous medium are assigned to the bonds in various directions and regions of the center of the corresponding truncated octahedral unit cell. The mineral particles are continuously assigned to the corresponding truncated octahedral unit cells until the cumulative volume fraction of all unit cells is equal to the experimental measurement value.

[0011] The pore structure characteristic parameters are randomly assigned to the face centers of each truncated octahedral unit cell of a certain size, and the adjacent face centers are connected through throats until the cumulative pore throat volume in all the unit cells reaches the experimentally measured value;

[0012] The deformation and failure of porous media are reflected by the bonds connecting the centers of mineral particles, and the effects of temperature, chemistry and stress on flow in porous media are simulated by changing the flow parameters and pore size / connectivity in the pores.

[0013] A second aspect of the present invention provides an equivalent discrete model construction system for the multi-field coupling behavior of porous media.

[0014] In one or more embodiments, a system for constructing an equivalent discrete model of multi-field coupled behavior of a porous medium includes:

[0015] An information acquisition module, which is used to obtain porous medium particle information and pore structure characteristic parameters; wherein the porous medium particle information includes the size, distribution and composition characteristics of mineral particles;

[0016] A mineral particle allocation module is used to map each mineral particle to a corresponding site at the center of a truncated octahedral unit cell and connect them through bonds according to the size and distribution of the mineral particles, and then allocate the composition characteristics of the porous medium particles to the bonds in various directions and regions of the center of the corresponding truncated octahedral unit cell, and continuously allocate the mineral particles to the corresponding truncated octahedral unit cells until the cumulative volume fraction of all truncated octahedral unit cells is equal to the experimental measurement value;

[0017] A pore allocation module, which is used to randomly allocate pore structure characteristic parameters to the face centers of each truncated octahedral unit cell of a certain size, and connect adjacent face centers through throats until the cumulative pore throat volume in all unit cells reaches an experimentally measured value;

[0018] A multi-field coupled model building module that is used to reflect the deformation and failure of porous media by connecting the bonds between the centers of mineral particles, and to simulate the effects of temperature, chemistry and stress on flow in porous media by changing the flow parameters and pore size / connectivity in the pores.

[0019] A third aspect of the present invention provides a computer-readable storage medium.

[0020] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps in the method for constructing an equivalent discrete model of multi-field coupling behavior of porous media as described above.

[0021] A fourth aspect of the present invention provides an electronic device.

[0022] An electronic device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps in the method for constructing an equivalent discrete model of multi-field coupling behavior of porous media as described above are implemented.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention utilizes truncated octahedral unit cells to simulate porous media, maps each mineral particle to a corresponding site at the center of a truncated octahedral unit cell according to the size and distribution of the mineral particles and connects them through bonds, and then distributes the compositional characteristics of the porous medium particles to the bonds in various directions and regions of the center of the corresponding truncated octahedral unit cell, and randomly distributes the pore structure characteristic parameters to the face centers of each truncated octahedral unit cell of a certain size, and uses throats to connect adjacent face centers, so that complex pore spaces can be reproduced and the pore structure characteristics of porous media can be better reflected, which provides an important research means for the subsequent efficient simulation of thermal-hydraulic-mechanical-chemical multi-field coupling behavior, can reduce the calculation cost and experimental cost, shorten the experimental data acquisition cycle, and can also obtain experimental data that is difficult to measure in the laboratory, and also lays a foundation for the later simulation of multiphase seepage, blockage, diffusion, fingering effect and other phenomena at the microscopic scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0026] Figure 1 is a schematic diagram of an electronic device according to an embodiment of the present invention;

[0027] Figure 2 It is a flow chart of a method for constructing an equivalent discrete model of multi-field coupling behavior of a porous medium according to an embodiment of the present invention;

[0028] Figure 3 It is a schematic diagram of the equivalent discrete model construction of the multi-field coupling behavior of the porous medium according to the embodiment of the present invention;

[0029] Figure 4(a) is a diagram of a regular unit cell structure;

[0030] Figure 4(b) is a schematic diagram of a truncated octahedron;

[0031] FIG4( c ) is a mechanical topological diagram of a regular unit cell structure;

[0032] Figure 4(d) is a diagram of the mechanical topological structure of a truncated octahedron;

[0033] FIG4( e ) is a physical / chemical topological structure diagram of a regular unit cell structure;

[0034] Figure 4(f) is a diagram of the physical / chemical topological structure of a truncated octahedron;

[0035] Figure 5 It is a schematic diagram of the structure of an equivalent discrete model building system for multi-field coupling behavior of porous media according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0037] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0038] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0039] Terminology explanation:

[0040] Equivalent discrete model: It is a porous media model established by simplifying the geometric shape and spatial connection relationship of the pore space of real porous media. It is also a basic platform for studying pore-level microscopic seepage theory and microstructural characteristics. In porous media, different particle sizes are mapped to the site of the unit cell center according to their size distribution. The larger pore space is regarded as the pore body, which is generally represented by a sphere in the equivalent discrete model; and the narrow space connecting the pore body is regarded as the throat, which is represented by a cylinder with a constant cross section in the equivalent discrete model.

[0041] Coordination number: an important parameter describing the equivalent discrete model, reflecting the connectivity of the pores and representing the number of throats between a single pore and adjacent pores. It is not a function of the spatial coordinates but a topological feature of each pore.

[0042] Reference Figure 1 , a schematic diagram of an electronic device is given. It should be noted that, Figure 1 The electronic device 100 shown is only an example and should not bring any limitation to the functions and scope of use of the embodiments of the present invention.

[0043] like Figure 1 As shown, the electronic device 100 includes a central processing unit (CPU) 101, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 102 or a program loaded from a storage part 108 into a random access memory (RAM) 103. In the RAM 103, various programs and data required for system operation are also stored. The central processing unit 101, the ROM 102, and the RAM 103 are connected to each other via a bus 104. An input / output (I / O) interface 105 is also connected to the bus 104.

[0044] The following components are connected to the I / O interface 105: an input section 106 including a keyboard, a mouse, etc.; an output section 107 including a cathode ray tube (CRT), a liquid crystal display (LCD), etc., and a speaker, etc.; a storage section 108 including a hard disk, etc.; and a communication section 109 including a network interface card such as a local area network (LAN) card, a modem, etc. The communication section 109 performs communication processing via a network such as the Internet. A drive 110 is also connected to the I / O interface 105 as needed. A removable medium 111, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed on the drive 110 as needed, so that a computer program read therefrom is installed into the storage section 108 as needed.

[0045] When the central processing unit 101 in the electronic device of this embodiment executes the program, the following is achieved: Figure 2 The steps in the method of building an equivalent discrete model of the multi-field coupled behavior of porous media are shown.

[0046] Figure 2 is a flow chart of a method for constructing an equivalent discrete model of multi-field coupling behavior of a porous medium in an embodiment of the present invention, combined with Figure 2 and Figure 3 As shown, the equivalent discrete model construction method of the porous medium multi-field coupling behavior in this embodiment may include:

[0047] S201, obtaining porous medium particle information and pore structure characteristic parameters, wherein the porous medium particle information includes the size, distribution and composition characteristics of mineral particles.

[0048] Among them, porous media are composed of particles of different mineral components and pores. The hard (stronger) mineral particles in the porous medium are randomly distributed at the center of the truncated octahedron according to their size. The mineral particles do not contain voids. The mineral particles are hard enough and their size will not change under the action of external forces. Moreover, cracks or new pores are more likely to be generated at the parts where the mineral particles are weakly connected.

[0049] In one or more embodiments, image analysis and fluid intrusion methods are used to obtain porous media particle information and pore structure characteristic parameters.

[0050] Taking Opalinus Clay (OPA), the surrounding rock of the Swiss high-level radioactive waste disposal repository, as an example, the sample was taken from the mud phase about 250 meters from the surface. The porous medium particle information and pore structure characteristic parameters were obtained by image analysis, including the use of X-ray tomography (XCT), focused ion beam nanotomography (FIB-nt) and scanning transmission electron microscopy (STEM) tomography technology, combined with the nitrogen adsorption method in the fluid intrusion method, to determine the mineral composition of the sample, the distribution and content of solid particle components, pore size distribution, pore shape, pore connectivity and other characteristics.

[0051] S202, according to the size and distribution of mineral particles, each mineral particle is mapped to the center position of a truncated octahedral unit cell and connected by bonds, and then the composition characteristics of the particles in the porous medium are assigned to the bonds in various directions and regions of the center of the corresponding truncated octahedral unit cell. The mineral particles are continuously assigned to the corresponding truncated octahedral unit cells until the cumulative volume fraction of all unit cells is equal to the experimental measurement value.

[0052] The anisotropy of the porous medium is represented by the length distances between the square faces of three different truncated octahedron unit cells. When the length distances between the square faces of three different truncated octahedron unit cells are equal, the porous medium is isotropic.

[0053] For example, for the mechanical topology map, carbonate and quartz grain sizes are mapped to sites in the center of the unit cell connected by bonds according to their size distribution. Each site is connected by 14 adjacent bonds. The anisotropy is represented by three different length parameters, S1[m], S2[m], and S3[m], which represent the distances between the square faces of the truncated octahedron. The volume of each unit cell is then V c =S1S2S3 / 2[m 3 ]. Among them, m in S1[m], S2[m] and S3[m] represents the unit dimension, meter.

[0054] For N c [-] unit cell model, particles are continuously allocated until their cumulative volume fraction equals the measured value, which is used to determine the construction of the truncated octahedron, that is:

[0055]

[0056] In the formula, r i [m] is the particle radius and f[-] is the measured particle volume percentage. Different length ratios between S1, S2 and S3 result in different length parameters in the equations used to simulate the anisotropy of porous media. For isotropy, S1 = S2 = S3.

[0057] S203, randomly assigning pore structure characteristic parameters to the face centers of each truncated octahedral unit cell of a determined size, and connecting adjacent face centers using throats until the cumulative pore throat volumes in all truncated octahedral unit cells reach an experimentally measured value.

[0058] Among them, in the physical / chemical topological structure diagram, sites and bonds are used to describe the connection between pores and throats. The sites on the unit surface are connected by bonds that act as conduits for transport species (as shown in Figures 4(e) and 4(f)). These sites can represent pores with volume or pore intersections without volume, while bonds can give properties to pores or throats. When bonds give throat properties, these throats can be designed as cylinders with volume, or have no volume and serve only as channels in the connecting network. There are three ways to connect pores and throats:

[0059] Both pores and throats occupy volume: pores are generally represented by spheres, while throats are represented by cylinders of constant cross-section.

[0060] Pores take up volume, throats do not: Pores are treated as spheres that take up space, while throats are not given actual volume and exist only as channels connecting pores.

[0061] Throats take up volume, pores do not: The throat is considered a cylinder that takes up space, while the pores have no volume and are simply nodes where the throat changes direction.

[0062] S204 reflects the deformation and damage of porous media by connecting the bonds at the centers of mineral particles, simulates the flow in porous media through pores, and the effects of temperature, chemistry and stress on the flow. It simulates the effects of temperature, chemistry and stress on the flow in porous media by adjusting the flow parameters in the pores (such as viscosity, free diffusion coefficient, etc.) and pore size / connectivity. Among them, the changed pore structure will in turn affect the mechanical behavior of the material.

[0063] In the specific implementation process, the throat can be represented by different shapes to reflect the actual situation.

[0064] Specifically, the pores and throats in the equivalent discrete model of the multi-field coupling behavior of the porous medium affect the material migration behavior of the porous medium. The material migration behavior of the porous medium is affected by the thermal-hydraulic-mechanical-chemical multi-field coupling, which includes:

[0065] Temperature affects the diffusion coefficient of the substance itself in the fluid, chemistry affects the pore size through which the substance passes, mechanics affects the change in pore size or the number of throats, and the change in pore size and the increase in throats affect the change in the stiffness matrix of the bond.

[0066] The mechanical behavior of porous media is reflected by the interaction of solid particles distributed in the center of the unit cell. The mechanical behaviors of solid particles such as tension, compression, shear and destruction are simulated by setting beam elements connecting the centers of adjacent unit cells. The existence of pores is represented by reducing the stiffness matrix of the bonds (i.e., beam elements) at the corresponding positions.

[0067] In order to consider the effect of confining pressure load on material migration, the mechanical response of OPA is simulated as shown in the mechanical topology diagrams of Figure 4(c) and Figure 4(d). Since OPA is anisotropic, different elastic moduli and Poisson's ratios are assigned to mechanical bonds in different directions according to experimental data, as shown in Table 1. Only the elastic response is studied here to evaluate the effect of confining pressure on the reaction mass transport characteristics through OPA. In addition to the physical properties, there are two distinguishable types of elements in the geometry: elements with square boundaries have longer lengths, while elements representing hexagonal boundaries have shorter lengths. In this work, all longer length bonds are assigned to have an area of ​​A4 = 0.106S i 2 Circular cross section, while all shorter length bonds are assigned an area of ​​A6 = 0.358S i 2 In this case, the relationship between the displacement u and the reaction force F of the adjacent unit cell center nodes is given by the standard equation F = Ku, where K is the symmetrical 12×12 beam stiffness matrix K, which is calculated as follows:

[0068]

[0069]

[0070]

[0071]

[0072]

[0073] Where β = 4,6, representing two types of bonds, A4 = 0.106Si 2 , A6=0.358S i 2 , b= / / and ⊥, indicating different directions. Since only the effect of structural response on the transmission process is considered, the change of pore radius due to strain caused by confining pressure can be expressed as in, is the initial radius, ε is the strain, l ij is the length of the structural element across the surface where the pore is located.

[0074] Table 1 Mechanical response input parameters

[0075]

[0076]

[0077] The equation for the migration of substances through pores includes convection terms, diffusion terms with double layer effects, and adsorption terms, reflecting that chemistry will change the size of pores through which substances can pass, and factors such as concentration difference, pressure difference, and double layer thickness affect the material migration process.

[0078] Specifically, assume that the two end nodes of the pore in the pore network model are i and j, and their volume is V ij , the surface area is S ij , then the material transport equation through each pore includes convection terms, diffusion terms with double electrical layer effects, and adsorption terms:

[0079]

[0080] where q ij (c i -c j ) is the convection term caused by velocity, q ij is the flow rate of a single hole, calculated by the following formula:

[0081]

[0082] where F ij is the diffusion term affected by the double electric layer, including the free diffusion part and the diffusion part in the double electric layer, calculated by the following formula:

[0083] F ij =F free,ij +F DL,ij

[0084]

[0085]

[0086] Where m[-] is the pore shape factor (when the cross-section is circular, triangular and square, m is 0.5, 0.6 and 0.5623 respectively); G ij is the shape factor; r ij is the initial pore radius; μ[Pa·s] is the fluid viscosity; l ij [m] is the pore length; P i and P j [Pa] are the pressures at pores i and j respectively; F free，ij is the free pore water diffusion flow; F DL，ij is the diffusion flow in DDL; f free is the fraction of free pore water in the total pore volume, which can be calculated by Get;d DL is the double diffusion layer (DDL) thickness; f DL is the volume fraction of the double layer solution, which can be calculated by the difference between the total pore volume and the free pore water volume; c DL is the concentration of the substance in the double layer [mol / m 3 ];c i -c j [kg / m 3 ] is the concentration difference between nodes; D w [m 2 / s] is the molecular diffusion coefficient; β[m -1 ] coefficient can be obtained by β = S ij / V ij Given; in compacted clay materials, if the DDL thickness is larger than the pore size, the corresponding anions cannot enter the pores.

[0087] The Arrehnius equation describes the effect of temperature on the diffusion coefficient in the fluid during the diffusion process. The Arrehnius equation is as follows:

[0088]

[0089] d DL =2κ -1

[0090]

[0091]

[0092]

[0093] c free (XX -1 )+q=0

[0094]

[0095]

[0096]

[0097] where A is the (empirical) diffusion coefficient; Q is the activation energy of diffusion in free water; T is the absolute temperature [K]; I is the dimensionless ionic strength, and ε is the water dielectric constant [78.3×8.85419×10 -12 F / m, 298K], F is the Faraday constant [96485C / mol], R is the gas constant [8.3145J / (mol×K)]; k The charge number of Y is [-]; is the electrostatic potential [V], c D,k is the concentration of substance k in the molecular sieve [mol / L]; q is the surface charge [molc / L]; CEC is the cation exchange capacity [molc / kg]; A s is the specific surface area [m 2 / g].

[0098] The effective model size and boundary conditions in the simulation method of thermal-hydraulic-mechanical-chemical multi-field coupled behavior of porous media are set as follows:

[0099] The size of the numerical simulation model is 0≤X1≤N×S1, 0≤X2≤N×S2, 0≤X3≤N×S3, S1, S2, S3 are the unit sizes in the three coordinate directions, N is the number of units in each coordinate direction, and in the same pore size distribution curve, 50 random allocations are made to the model, and the variance of the permeability or diffusivity calculated under different allocation conditions is calculated. It is found from trial calculations that when N increases to 20, the calculated variance is reduced to less than 10%, so the simulation results are based on the average value of 50 random allocations when N=20.

[0100] For the material transport simulation, the initial concentration of all nodes is assumed to be zero. The boundary conditions reflect the specific experimental setup, in which concentrations c0 and c1 are specified on two opposite boundaries, while the other four boundaries do not allow material to pass through. The selection of these two boundaries depends on the macroscopic transport properties analyzed. Specifically, for the calculation of the macroscopic transport properties parallel to the clay bedding direction (1, 0, 0), the boundary conditions of D1 are: the concentration of all nodes on the plane X1=0 is c0; the concentration of all nodes on the plane X1=20S1 is c1; the flux is zero at all nodes on the planes X2=0, X2=20S2, X3=0, X3=20S3. When used to calculate the macroscopic transport properties (0, 1, 0) perpendicular to the clay bedding direction, the boundary conditions of D2 are: the concentration at all nodes on the plane X2 = 0 is c0; the concentration at all nodes on the plane X2 = 20S2 is c1; the flux at all nodes on the planes X1 = 0, X1 = 20S1, X3 = 0, X3 = 20S3 is zero.

[0101] For the mechanical simulation, the boundary conditions perpendicular to the clay bedding direction are: compressive pressure is applied on X0 and X1; in the X2 direction, the displacement of all nodes on the planes X2=0 and X2=20S2 is zero; in the X3 direction, the displacement of all nodes on the planes X3=0 and X3=20S3 is also zero.

[0102] In particular, according to an embodiment of the present application, the process described above with reference to the flowchart can be implemented as a computer software program. For example, an embodiment of the present application includes a computer program product, which includes a computer program carried on a computer readable medium, the computer program including a computer program for executing Figure 2 In such an embodiment, the computer program can be downloaded and installed from the network through the communication part 109, and / or installed from the removable medium 111. When the computer program is executed by the central processing unit 101, various functions defined in the apparatus of the present application are executed.

[0103] in, Figure 2 The computer program instructions corresponding to the method shown may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce a manufactured product including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0104] A person skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium, and when the program is executed, it can include the processes of the embodiments of the above-mentioned methods. The storage medium can be a disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM), etc.

[0105] Figure 5 Schematic diagram of the structure of an equivalent discrete model construction system for multi-field coupling behavior of porous media in an embodiment of the present invention. Figure 2 The equivalent discrete model construction method of the multi-field coupling behavior of porous media corresponds to Figure 5 As shown, the equivalent discrete model construction system of the porous medium multi-field coupling behavior in this embodiment may include:

[0106] The information acquisition module 301 is used to acquire the porous medium particle information and pore structure characteristic parameters; wherein the porous medium particle information includes the size, distribution and composition characteristics of the particles;

[0107] The mineral particle allocation module 302 is used to map each mineral particle to a corresponding site at the center of a truncated octahedron unit cell and connect them through bonds according to the size and distribution of the mineral particles, and then allocate the composition characteristics of the porous medium particles to the bonds in various directions and regions of the center of the corresponding truncated octahedron unit cell, and continuously allocate the mineral particles to the corresponding truncated octahedron unit cells until the cumulative volume fraction of all truncated octahedron unit cells is equal to the experimental measurement value;

[0108] A pore allocation module 303, which is used to randomly allocate pore structure characteristic parameters to the face centers of each truncated octahedral unit cell of a certain size, and connect adjacent face centers through throats until the cumulative pore throat volume in all units reaches the experimental measurement value;

[0109] The multi-field coupling model building module 304 is used to reflect the deformation and damage of porous media by connecting the bonds at the centers of mineral particles, simulate the flow in porous media through pores, and the effects of temperature, chemistry and stress on the flow. The effects of temperature, chemistry and stress on the flow in porous media are simulated by adjusting the flow parameters (such as viscosity, free diffusion coefficient, etc.) and pore size / connectivity in the pores, wherein the changed pore structure will in turn affect the mechanical behavior of the material.

[0110] Figure 5 The specific implementation process of modules 301 to 304 in the equivalent discrete model construction system for the multi-field coupling behavior of porous media shown in FIG. Figure 2The specific implementation process of steps S201 to 204 is the same as that of FIG. 1 and will not be described in detail here.

[0111] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for constructing an equivalent discrete model of multi-field coupling behavior of porous media, characterized in that: include: Obtaining porous medium particle information and pore structure characteristic parameters; wherein the porous medium particle information includes particle size, distribution and composition characteristics; According to the size and distribution of particles, each particle is mapped to the center position of a truncated octahedral unit cell and connected by bonds. Then, the composition characteristics of the particles in the porous medium are assigned to the bonds in various directions and regions of the center of the corresponding truncated octahedral unit cell. The mineral particles are continuously assigned to the corresponding truncated octahedral unit cells until the cumulative volume fraction of all unit cells is equal to the experimental measurement value. The pore structure characteristic parameters are randomly assigned to the face centers of each truncated octahedral unit cell of a certain size, and the adjacent face centers are connected through throats until the cumulative pore throat volume in all the unit cells reaches the experimentally measured value; Reflect the deformation and failure of porous media by connecting the bonds between the centers of mineral particles, and simulate the effects of temperature, chemistry and stress on flow in porous media by changing the flow parameters and pore size / connectivity in the pores; The pores and throats in the equivalent discrete model of the multi-field coupled behavior of the porous medium affect the material migration behavior of the porous medium; The material migration behavior of the porous medium is affected by the thermal-hydraulic-mechanical-chemical multi-field coupling, which includes: Temperature affects the diffusion coefficient of the substance itself in the fluid, chemistry affects the size of the pores through which the substance passes, mechanics affects the change in the size of the pores or the number of throats, and the change in the pore size and the increase in throats affect the change in the stiffness matrix of the bond; The effective model size and boundary conditions in the simulation method of thermal-hydraulic-mechanical-chemical multi-field coupled behavior of porous media are set as follows: The size of the numerical simulation model is 0≤X1≤N×S1, 0≤X2≤N×S2, 0≤X3≤N×S3, where S1, S2, and S3 are the unit sizes in the three coordinate directions, and N is the number of units in each coordinate direction.

2. The method for constructing an equivalent discrete model of multi-field coupling behavior of porous media according to claim 1, characterized in that: The anisotropy of the porous medium is represented by the length distances between the square faces of three different truncated octahedral unit cells.

3. The method for constructing an equivalent discrete model of multi-field coupling behavior of porous media according to claim 2, characterized in that: When the length distances between the square faces of three different truncated octahedral unit cells are equal, the porous medium is isotropic.

4. The method for constructing an equivalent discrete model of multi-field coupling behavior of porous media according to claim 1, characterized in that: Image analysis and fluid intrusion methods are used to obtain porous media particle information and pore structure characteristic parameters.

5. An equivalent discrete model construction system for multi-field coupling behavior of porous media, characterized in that: include: An information acquisition module, which is used to obtain porous medium particle information and pore structure characteristic parameters; wherein the porous medium particle information includes the size, distribution and composition characteristics of the particles; A mineral particle allocation module is used to map each particle to a corresponding site at the center of a truncated octahedral unit cell and connect them through bonds according to the particle size and distribution in the porous medium particle information, and then allocate the particle component characteristics in the porous medium particle information to the bonds in various directions and regions of the center of the corresponding truncated octahedral unit cell, and continuously allocate mineral particles to the corresponding truncated octahedral unit cells until the cumulative volume fraction of all truncated octahedral unit cells is equal to the experimental measurement value; A pore allocation module, which is used to randomly allocate pore structure characteristic parameters to the face centers of each truncated octahedral unit cell of a certain size, and connect adjacent face centers through throats until the cumulative pore throat volume in all units reaches the experimentally measured value; Multi-field coupled model building modules for reflecting deformation and failure of porous media by connecting the bonds between the centers of mineral particles, simulating flow in porous media through pores, the effects of temperature, chemistry and stress on flow, and simulating the effects of temperature, chemistry and stress on flow in porous media by affecting flow parameters and pore size / connectivity in pores; The pores and throats in the equivalent discrete model of the multi-field coupled behavior of the porous medium affect the material migration behavior of the porous medium; The material migration behavior of the porous medium is affected by the thermal-hydraulic-mechanical-chemical multi-field coupling, which includes: Temperature affects the diffusion coefficient of the substance itself in the fluid, chemistry affects the size of the pores through which the substance passes, mechanics affects the change in the size of the pores or the number of throats, and the change in the pore size and the increase in throats affect the change in the stiffness matrix of the bond; The effective model size and boundary conditions in the simulation method of thermal-hydraulic-mechanical-chemical multi-field coupled behavior of porous media are set as follows: The size of the numerical simulation model is 0≤X1≤N×S1, 0≤X2≤N×S2, 0≤X3≤N×S3, where S1, S2, and S3 are the unit sizes in the three coordinate directions, and N is the number of units in each coordinate direction.

6. The equivalent discrete model construction system for multi-field coupling behavior of porous media according to claim 5, characterized in that: The anisotropy of the porous medium is represented by the length distances between the square faces of three different truncated octahedral unit cells.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps in the method for constructing an equivalent discrete model of multi-field coupling behavior of porous media as described in any one of claims 1 to 4 are implemented.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps in the method for constructing an equivalent discrete model of multi-field coupling behavior of porous media as described in any one of claims 1 to 4 are implemented.

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