Method for simulating seepage of coalbed methane in multiscale pores, apparatus, device, medium, and product

Abstract

The present application relates to the field of natural gas reservoir engineering, and discloses a method for simulating seepage of coalbed methane in multiscale pores, an apparatus, a device, a medium, and a product. The method comprises: acquiring initial information of the rock core of coal rock in a target stratum and medium information of multiple medium units, the medium information comprising basic medium information and a mutual gas flow relationship between the multiple medium units; on the basis of the medium information and the initial information, determining the transmissibility between any two medium units (macroporous pores, mesoporous pores and microporous pores) in the target stratum; on the basis of the transmissibility, constructing a flow continuity model of a corresponding medium unit in a pore grid of the rock core of the coal rock in the target stratum; and on the basis of the flow continuity model, calculating the degree of desorption of a corresponding medium in a numerical model grid of coalbed methane in the target stratum during numerical simulation, the degree of desorption being used for reflecting the multiscale desorption rule of a coalbed methane grid. The method is used for accurately simulating the development effect of coalbed methane.

Description

Methods, apparatus, equipment, media and products for simulating multi-stage pore flow in coal and rock gas

[0001] This application claims priority to Chinese Patent Application No. 202411638000.4, filed on November 15, 2024, entitled “Method, Apparatus, Equipment, Medium and Product for Simulating Multi-level Pore Flow of Coal and Rock Gas”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The embodiments of this application relate to, but are not limited to, the field of natural gas reservoir engineering, and more specifically, to a method, apparatus, equipment, medium, and product for simulating multi-stage pore seepage in coal and rock gas. Background Technology

[0003] Deep coalbed methane (CBM), also known as coal shale gas, is an unconventional natural gas resource. Its extraction differs significantly from traditional oil and gas reservoirs, primarily due to the unique pore structure and seepage mechanism of coal. With increasing energy demand, CBM extraction has become an important area of ​​focus. Effective CBM extraction is closely related to its seepage flow. However, studying CBM seepage presents many difficulties and challenges; therefore, an improved method for simulating CBM seepage flow is urgently needed.

[0004] Currently, seepage simulations of coal gas are typically performed using numerical simulation software, such as Eclipse, Intersect, Computer Modelling Group (CMG), and tNavigator. These software programs usually employ large grid sizes to characterize pressure changes and desorption processes in coal gas reservoirs, essentially simulating the mining process of a specific coal body grid within a coal gas reservoir using macroscopic pressure values. However, complex gas transport processes exist within the coal body grid during development, involving gas flow transport and exchange between different porous media (macropores, mesopores, and micropores). This macroscopic pressure numerical characterization method leads to inaccurate simulations of the development characteristics of coal gas. Summary of the Invention

[0005] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0006] The purpose of this application is to provide a method, apparatus, equipment, medium and product for simulating multi-stage pore flow of coal and rock gas, so as to achieve the effect of accurately simulating the flow mode of coal and rock gas.

[0007] In a first aspect, this application provides a method for simulating seepage between multi-level pores in coal and rock gas, comprising:

[0008] Acquire initial information of coal and rock cores from the target formation and media information of multiple media units. The media information includes basic media information and gas flow relationships between multiple media units.

[0009] Based on medium information and initial information, determine the conductivity between any two medium units in the coal core of the target stratum;

[0010] Based on conductivity, a flow continuity model of the corresponding medium unit in the pore grid of the target stratum coal core is constructed;

[0011] Based on the flow continuity model, the degree of desorption of the corresponding medium in the target formation coal-rock grid is calculated during the numerical simulation. The degree of desorption is used to reflect the multi-level desorption law of the coal-rock gas grid.

[0012] In one possible implementation, the conductivity between any two media units in the target formation coal-rock grid is determined based on media information and initial information, including:

[0013] Based on the pore structure of the coal core of the target stratum, the gas transport flow rate between any two media units is determined according to the medium information and initial information, wherein the gas flows between any two media units.

[0014] The conductivity between two media units is obtained based on the gas transport flow rate between any two media units.

[0015] In one possible implementation, the gas transport flow rate between any two media units satisfies the following formula:

[0016] Among them, Q M-N This represents the gas transport flow rate between any two media units; N1 represents the total number of pores; M and N represent any two media (macropores, mesopores, and micropores); g M-N,tot L represents the shape factor between two dielectric units; M-N,tot Δp represents the characteristic length of the pore throat between two dielectric units. M-N represents the pressure difference between any two media units; m represents the ratio of the number of pores in a single layer of media to the total number of pores.

[0017] In one possible implementation, based on conductivity, a flow continuity model of the corresponding medium element in the pore grid of the target formation coal core is constructed, including:

[0018] Construct a continuity equation for gas transport between different media units;

[0019] Establish the initial gas content in each medium and the conductivity between each medium under the initial conditions;

[0020] Establish the diffusion coefficient and crossflow coefficient in the gas flow equation for each medium diffusing into the fracture medium;

[0021] Based on the gas flow relationships between multiple media units and the diffusion of gas from multiple media units to the cleavage media units in the target coal core, a flow continuity model for the corresponding media in the pore grid of the target coal core is determined. The flow continuity model satisfies the following formula: Gas change per unit time of the corresponding media unit = Gas flow change of the corresponding media unit (inflow - outflow) - Gas diffusion from the corresponding media unit to the cleavage media unit.

[0022] In one possible implementation, the amount of gas diffusing from the corresponding medium unit to the cleavage medium unit is determined by the following method:

[0023] The amount of gas diffused from the corresponding medium unit to the cleavage medium unit is determined based on the gas concentration of the corresponding medium unit, the gas concentration of the cleavage medium unit, and the cross-flow coefficient between the corresponding medium and the cleavage medium unit.

[0024] In one possible implementation, based on a flow continuity model, the degree of desorption of the corresponding medium in the target formation coal-rock grid during the numerical simulation is calculated, including:

[0025] Based on the flow continuity model, the pressure of the corresponding medium is obtained;

[0026] Based on the pressure of the corresponding medium, determine the current amount of adsorbed gas in the corresponding medium;

[0027] Based on the current amount of adsorbed gas in the corresponding medium, determine the degree of desorption in the numerical model of coal and rock gas in the target formation for different media.

[0028] In one possible implementation, the degree of desorption for different media in the target formation coal gas numerical model is determined based on the current amount of adsorbed gas in the corresponding medium, including:

[0029] Determine the initial adsorbed gas quantity and the calculated adsorbed gas quantity of the corresponding medium. The initial adsorbed gas quantity refers to the amount of gas adsorbed by the corresponding medium at the initial pressure, and the target adsorbed gas quantity refers to the amount of gas adsorbed by the corresponding medium at the target pressure.

[0030] The amount of desorbed gas is determined based on the initial amount of adsorbed gas and the target amount of adsorbed gas.

[0031] Based on the amount of desorbed gas, the degree of desorption for different media in the numerical model of coal and rock gas in the target formation is determined.

[0032] Secondly, this application provides a multi-stage pore seepage simulation device for coal and rock gas, comprising:

[0033] The acquisition module is used to acquire the initial information of the target stratum coal core and the medium information of the multiple medium units. The medium information includes basic medium information and the gas flow relationship between the multiple medium units.

[0034] The first determining module is used to determine the conductivity between any two media units in the target formation coal core based on media information and initial information.

[0035] The module is used to construct a flow continuity model of the corresponding medium element in the pore grid of the target formation coal core based on the conductivity.

[0036] The second determination module is used to calculate the degree of desorption of the corresponding medium in the coal and rock grid of the target formation during the numerical simulation based on the flow continuity model. The degree of desorption is used to reflect the multi-level desorption law of the coal and rock gas grid.

[0037] In one possible implementation, the first determining module is specifically used for:

[0038] Based on the pore structure of the coal core of the target stratum, the gas transport flow rate between any two media units is determined according to the medium information and initial information, wherein the gas flows between any two media units.

[0039] The conductivity between two media units is obtained based on the gas transport flow rate between any two media units.

[0040] In one possible implementation, the gas transport flow rate between any two media units satisfies the following formula:

[0041] Among them, Q M-N This represents the gas transport flow rate between any two media units; N1 represents the total number of pores; M represents the first media; N represents the second media; g M-N,tot L represents the shape factor between two dielectric units; M-N,tot Δp represents the characteristic length of the pore throat between two dielectric units. M-N represents the pressure difference between any two media units; m represents the ratio of the number of pores in a single layer of media to the total number of pores.

[0042] In one possible implementation, the building module is specifically used for:

[0043] Construct a continuity equation for gas transport between different media units;

[0044] Establish the initial gas content in each medium and the conductivity between each medium under the initial conditions;

[0045] Establish the diffusion coefficient and crossflow coefficient in the gas flow equation for each medium diffusing into the fracture medium;

[0046] Based on the gas flow relationships between multiple media units and the diffusion of gas from multiple media units to the cleavage media units in the target coal core, a flow continuity model for the corresponding media in the pore grid of the target coal core is determined. The flow continuity model satisfies the following formula: Gas change in the corresponding media unit = Gas change in the corresponding media unit per unit time = Gas flow change in the corresponding media unit (inflow - outflow) - Gas diffusion from the corresponding media unit to the cleavage media unit.

[0047] In one possible implementation, the amount of gas diffusing from the corresponding medium unit to the cleavage medium unit is determined by the following method:

[0048] The amount of gas diffused from the corresponding medium unit to the cleavage medium unit is determined based on the gas concentration of the corresponding medium unit, the gas concentration of the cleavage medium unit, and the cross-flow coefficient between the corresponding medium and the cleavage medium unit.

[0049] In one possible implementation, the second determining module is specifically used for:

[0050] Based on the flow continuity model, the pressure of the corresponding medium is obtained;

[0051] Based on the pressure of the corresponding medium, determine the current amount of adsorbed gas in the corresponding medium;

[0052] Based on the current amount of adsorbed gas in the corresponding medium, determine the degree of desorption in the numerical model of coal and rock gas in the target formation for different media.

[0053] In one possible implementation, the second determining module is used to:

[0054] Determine the initial adsorbed gas quantity and calculate the adsorbed gas quantity for the corresponding medium. The initial adsorbed gas quantity refers to the amount of gas adsorbed by the corresponding medium at the initial pressure, and the target adsorbed gas quantity refers to the amount of gas adsorbed by the corresponding medium at the target pressure.

[0055] The amount of desorbed gas is determined based on the initial amount of adsorbed gas and the target amount of adsorbed gas.

[0056] Based on the amount of desorbed gas, the degree of desorption for different media in the numerical model of coal and rock gas in the target formation is determined.

[0057] Thirdly, this application provides an electronic device, including: a memory and a processor;

[0058] The memory stores the instructions that the computer executes;

[0059] The processor executes computer execution instructions stored in memory, causing the processor to perform the first aspect and / or various possible implementations of the first aspect as described above.

[0060] Fourthly, this application provides a computer-readable storage medium storing computer-executable instructions, which, when executed, are used to implement the first aspect and / or various possible embodiments of the first aspect.

[0061] Fifthly, this application provides a computer program product, including a computer program that, when executed, implements the first aspect and / or various possible implementations of the first aspect.

[0062] Sixthly, this application provides a computer program that, when run on a computer, causes the computer to perform the method described in the first aspect.

[0063] This application provides a method, apparatus, equipment, medium, and product for simulating multi-stage pore flow of coal and rock gas. The application includes: acquiring initial information of a target coal and rock core and medium information of multiple medium units, the medium information including basic medium information and the gas flow relationships between the multiple medium units; determining the conductivity between any two medium units in the target coal and rock core based on the medium information and initial information; constructing a flow continuity model of the corresponding medium unit in the pore grid of the target coal and rock core based on the conductivity; and calculating the degree of desorption of the corresponding medium in the target coal and rock grid during the numerical simulation based on the flow continuity model, the degree of desorption reflecting the multi-stage desorption law of the coal and rock gas grid. This application first determines the conductivity between any two media units in the target coal core based on initial information and media information of multiple media units, thus fully considering the material transfer between different media units in the target coal core. Then, based on the conductivity, a flow continuity model of the corresponding media unit in the pore grid of the target coal core is constructed to improve the accuracy of the constructed flow continuity model. Next, based on the flow continuity model, the degree of desorption of the corresponding medium in the target coal core is determined to accurately simulate the seepage mode of coal gas.

[0064] After reading and understanding the accompanying diagrams and detailed descriptions, the other aspects can be understood. Attached Figure Description

[0065] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0066] Figure 1 is a schematic diagram of the MINC model provided in the embodiment of this application;

[0067] Figure 2 is a simplified schematic diagram of the conventional coal and rock gas extraction model provided in the embodiments of this application;

[0068] Figure 3 is a schematic diagram of the principle of the conventional numerical simulation model provided in the embodiment of this application;

[0069] Figure 4 is a schematic diagram of the actual pressure change process inside coal and rock provided in the embodiments of this application;

[0070] Figure 5 is a schematic diagram of the principle of the coal and rock gas seepage model provided in the embodiment of this application;

[0071] Figure 6 is a schematic diagram of the requirements for the gas transport model between multi-level porous media units inside coal and rock provided in this application;

[0072] Figure 7 is a schematic diagram of the multi-medium connectivity and flow relationship provided in an embodiment of this application;

[0073] Figure 8 is a schematic flowchart of the multi-stage pore seepage simulation method for coal and rock gas provided in this application.

[0074] Figure 9 is a schematic diagram showing the ratio of the pore diameter of different media to the number of pores in the corresponding media to the total number of pores provided in the embodiments of this application;

[0075] Figure 10 is a schematic diagram of scaling up a media unit according to an embodiment of this application;

[0076] Figure 11 is a schematic diagram of the gas flow relationship between multiple media units provided in the embodiments of this application;

[0077] Figure 12 is a schematic diagram of the Jacobian iteration method solution process provided in the embodiments of this application;

[0078] Figure 13 is a schematic diagram of the distribution ratio of different media in coal and rock provided in the embodiments of this application;

[0079] Figure 14 is a schematic diagram of a simulated single-well model provided in an embodiment of this application;

[0080] Figure 15 is a schematic diagram showing the simulation calculation comparison results of different models provided in the embodiments of this application;

[0081] Figure 16 is a schematic diagram of the connection relationship of four coal and rock media units provided in an embodiment of this application;

[0082] Figure 17 is a schematic diagram provided by an embodiment of this application to illustrate the stepwise pressure drop process of three media units under constant boundary pressure of the cleavage filament over time;

[0083] Figure 18 is a schematic diagram of the multi-stage pore seepage simulation device for coal and rock gas provided in this application;

[0084] Figure 19 is a schematic diagram of the structure of an electronic device provided in an embodiment of this application.

[0085] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments.

[0086] The accompanying drawings are used to provide a further understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application. Detailed Implementation

[0087] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0088] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0089] First, let me explain the terms used in this application:

[0090] The traditional Multiple Interacting Continua (MINC) model is a mathematical model used to describe fluid flow and transport processes in porous media. This model discretizes the matrix mesh of coal and rock into a series of nested volumetric elements, defined according to their distance from cleavages. However, a current limitation of this model is that while the nested volumetric elements are connected sequentially in a "series" manner, in reality, the various porous media elements in coal and rock exhibit "parallel" characteristics, meaning that mass transfer occurs between them. The specific principle is illustrated in Figure 1, which is a schematic diagram of the MINC model provided in an embodiment of this application.

[0091] Fick's Law of Diffusion: A fundamental principle describing the diffusion behavior of matter, proposed by German physicist Adolf Fick in the 19th century. Diffusion refers to the spontaneous movement of matter from a region of high concentration to a region of low concentration, and Fick's Law of Diffusion provides a quantitative description of this process.

[0092] Darcy's Law: A fundamental law describing fluid flow in porous media, derived by French engineer Henri Darcy through experimental research in 1856. This law applies to low-speed flow, i.e. laminar flow, where the fluid flow trajectories are parallel and do not intersect.

[0093] Hagen-Poiseuille's law of analytical flow, also known as Poiseuille's law, is a fundamental equation in fluid mechanics that describes laminar flow of viscous fluids in a circular pipe. This law states that under laminar flow conditions, the flow rate of a fluid through a circular pipe depends on the pressure difference across the pipe, the pipe radius, the viscosity of the fluid, and the length of the pipe.

[0094] It should be noted that the information and data involved in this application (including but not limited to data used for analysis, stored data, and displayed data) are all information and data authorized by the user or fully authorized by all parties. Furthermore, the collection, use, processing, transmission, provision, disclosure, and application of the relevant data all comply with relevant laws, regulations, and standards, and necessary confidentiality measures have been taken. The data does not violate public order and good morals, and corresponding operation access points are provided for users to choose to authorize or refuse.

[0095] To effectively develop coalbed methane resources, conventional numerical simulation technology for coalbed methane is widely used to predict the production capacity of coalbed methane reservoirs, optimize development schemes, and manage the coalbed methane extraction process. Conventional numerical simulation models simplify the matrix and cleavage into two layers: a matrix grid and a cleavage grid. The model assumes that the coal matrix structure is dense and does not participate in gas flow; therefore, it is also called a two-pore, single-permeability model. In this model, the matrix diffuses towards the cleavage, and the cleavage flows towards the cleavage. Conventional numerical simulation models assume that the matrix grid and the cleavage grid each have a pressure, and that the matrix-cleavage relationship instantaneously reaches desorption equilibrium and flow equilibrium. For details, see Figures 2 and 3. Figure 2 is a simplified schematic diagram of the conventional coalbed methane extraction model provided in this embodiment, and Figure 3 is a schematic diagram of the principle of the conventional numerical simulation model provided in this embodiment.

[0096] Optionally, conventional numerical simulation models use macroscopic pressure values ​​to characterize the pressure drop and desorption degree during coal gas extraction. However, in reality, there is an unsteady gas transport process inside the coal, resulting in a unique pressure drop funnel. Figure 4 illustrates the actual pressure change process inside the coal, as provided in this embodiment. As can be seen from Figure 4, while it is generally assumed that there is only one pressure inside the coal, and that desorption is instantaneous during coal gas extraction, in reality, desorption is completed gradually from the outside to the inside through the formation of a pressure drop gradient.

[0097] To address the aforementioned problems, this application provides a method, apparatus, equipment, medium, and product for simulating multi-level pore flow of coal and rock gas. This application improves upon the MINC model by first establishing discrete volumetric units representing three layers of media within the coal (matrix), and then establishing a mathematical model for gas transport between these three volumetric units. This accurately characterizes the non-equilibrium flow of multiple media within the coal and rock. The three layers of media are macroporous, mesoporous, and microporous media, each of which is an independent volumetric unit with independent pressure. Different matrix units are interconnected and all are connected to cleavage units. Flow exists between cleavage units of adjacent grids; matrix units are considered independent (isolated by the cleavage system). The specific principle is illustrated in Figure 5, which is a schematic diagram of the coal and rock gas flow model provided in this embodiment.

[0098] Optionally, since a gas transport model between multi-level porous media units inside coal and rock needs to be established, the traditional coal and rock grid needs to be split into multiple grids to describe the desorption and flow laws between different porous media. Figure 6 shows the characterization requirements for the new model. Figure 6 is a schematic diagram of the requirements for the gas transport model between multi-level porous media units inside coal and rock provided in this application.

[0099] Optionally, the coal and rock gas multi-stage pore flow simulation method, apparatus, equipment, media, and products provided in this application are based on the following conditions: each level of media unit is interconnected and connected to the cleavage unit. The matrix units are considered independent of each other; only single-phase methane flow is considered between each level of media unit, ignoring the effect of temperature on gas viscosity; the starting pressure gradient between each media unit is not considered; the gas flow characteristics between each level of media unit follow the Hagen-Poiseuille analytical flow law (ball-and-stick model) at the microscale; the gas flow between each level of media unit and the cleavage media unit still follows Fick's diffusion law; the gas flow in the cleavage media unit follows Darcy's law. For specific principles, please refer to Figure 7, which is a schematic diagram of the multi-media connectivity and flow relationship provided in the embodiments of this application.

[0100] The technical solutions of this application will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will be described below with reference to the accompanying drawings.

[0101] Figure 8 is a schematic flowchart of the multi-stage pore seepage simulation method for coal and rock gas provided in this application. As shown in Figure 8, the method includes:

[0102] S801. Obtain initial information of the target formation coal core and media information of multiple media units. The media information includes basic media information and gas flow relationships between multiple media units.

[0103] In this system, the gas can flow between the multiple media units. Taking a multi-media unit comprising macroporous, mesoporous, and microporous media units as an example, it can be considered that gas in the macroporous media unit can flow to the microporous media unit, and similarly, gas in the microporous media unit can flow to the macroporous media unit. Optionally, the gas flow relationships in the other media units are similar to those in the macroporous media unit.

[0104] S802. Based on medium information and initial information, determine the conductivity between any two medium units in the target stratum coal core.

[0105] After obtaining the initial information and media information of the multiple media units of the target formation coal core via S802, it is necessary to determine the conductivity between any two media units within the target formation coal core based on the obtained initial and multiple media unit information. This means that the conductivity between any two media units within the target formation coal core is related to both the media information and the initial information.

[0106] In one implementation, the conductivity between macroporous and microporous media units in the target formation coal core is determined based on the media information of the macroporous and microporous media units and the initial information of the target formation coal core. This means that the conductivity between any two media units is determined by the media information of the corresponding media.

[0107] In another implementation, the conductivity between macroporous and mesoporous media units in the target formation coal core is determined based on the media information of macroporous and mesoporous media units and the initial information of the target formation coal core.

[0108] S803. Based on the conductivity, construct a flow continuity model of the corresponding medium unit in the pore grid of the target stratum coal core.

[0109] After determining the conductivity between any two media elements in S802, a flow continuity model of the corresponding media element in the pore grid of the target formation coal core is constructed based on the determined conductivity. This means that the flow continuity model of the media element in the pore grid of the target formation coal core is based on the conductivity between the corresponding media element and the other media elements.

[0110] For example, if a flow continuity model of macroporous media units in the pore grid of a target formation coal core is constructed, it needs to be based on the conductivity between macroporous and microporous media units and the conductivity between macroporous and mesoporous media units; if a flow continuity model of mesoporous media units in the pore grid of a target formation coal core is constructed, it needs to be based on the conductivity between mesoporous and microporous media units and the conductivity between mesoporous and macroporous media units.

[0111] S804. Based on the flow continuity model, calculate the degree of desorption of the corresponding medium in the target formation coal-rock grid during the numerical simulation. The degree of desorption is used to reflect the multi-stage desorption law of the coal-rock gas grid.

[0112] In this step, it can be understood that after determining the flow continuity model of the corresponding medium through S803, it is necessary to determine the degree of desorption of the corresponding medium in the target formation coal core based on the flow continuity model of the corresponding medium unit. The degree of desorption reflects the multi-stage desorption behavior of the coal-gas grid. This means that the degree of desorption of the corresponding medium in the target formation coal core is related to the flow continuity model of the corresponding medium unit. The closer the constructed flow continuity model is to the actual flow continuity model, the more accurate the determined degree of desorption of the corresponding medium in the target formation coal core will be, and the more accurately the multi-stage desorption behavior of the coal-gas grid can be simulated.

[0113] The coal gas multi-stage pore seepage simulation method provided in this application first determines the conductivity between any two media units in the target coal core based on the initial information of the target formation coal core and the media information of multiple media units, thus fully considering the material transfer between different media units in the target coal core. Then, based on the conductivity, a flow continuity model of the corresponding media unit in the pore grid of the target coal core is constructed to improve the accuracy of the constructed flow continuity model. Next, based on the flow continuity model, the degree of desorption of the corresponding medium in the target coal core is determined to achieve the effect of accurately simulating the seepage mode of coal gas.

[0114] Based on the above embodiments, the conductivity between any two media units in the target stratum coal core is determined based on media information and initial information, including: determining the gas transport flow rate between any two media units based on the pore structure of the target stratum coal core, according to media information and initial information, wherein the gas between any two media units flows into each other; and obtaining the conductivity between the two media units based on the gas transport flow rate between any two media units.

[0115] In this embodiment, it can be understood that determining the conductivity between any two media units in the target coal core requires combining the pore structure obtained from nuclear magnetic resonance or gas adsorption methods of the target coal core. The obtained pore structure is then divided to obtain the pore diameter, total number of pores for each media unit, and the ratio of the number of pores in each media unit to the total number of pores—that is, to obtain the initial information of the target coal core. Under the condition of gas flow between any two media units in the target coal core, the gas transport flow rate between any two media units is determined based on the initial information.

[0116] Optionally, the gas transport flow rate between any two media units satisfies the following formula:

[0117] Among them, Q M-N This represents the gas transport flow rate between any two media units; N1 represents the total number of pores; M represents the first media; N represents the second media; g M-N,tot L represents the shape factor between two dielectric units; M-N,tot Δp represents the throat diameter between two dielectric units. M-N represents the pressure difference between any two media units, and m represents the ratio of the number of pores in a single layer of media to the total number of pores.

[0118] Optionally, the ratio of the pore diameter of different media to the ratio of the number of pores in the corresponding media to the total number of pores is shown in Figure 9. Figure 9 is a schematic diagram of the ratio of the pore diameter of different media to the ratio of the number of pores in the corresponding media to the total number of pores provided in the embodiments of this application.

[0119] After determining the gas transport flow rate between any two dielectric units, the conductivity between the two dielectric units is obtained based on the gas transport flow rate. The conductivity of any two dielectric units satisfies the following formula:

[0120] Among them, T M-N It represents the conductivity of any two dielectric units.

[0121] It should be noted that determining the conductivity between any two media units in the target formation coal core requires scaling up the media units using fractal geometry principles to calculate the conductivity between any two media units following the Hagen–Poiseuille analytical flow law. Figure 10 is a schematic diagram of scaling up the media units according to an embodiment of this application.

[0122] Alternatively, assuming that any two media units are connected by n orifice throats, the gas transport flow rate between any two media units satisfies the following formula:

[0123] Among them, Q M-N Represents the gas transport flow rate between any two media units; L M-N,tot =L M +L N , G is the shape factor of the pores; a is the average cross-sectional area of ​​the pores, in meters. 2 μ represents the viscosity of the gas, in mPa·s; g represents the shape factor of the medium element; L represents the throat diameter of the medium element.

[0124] This application embodiment determines the conductivity between any two media units in the target formation coal core based on medium information and initial information, providing a data basis for accurately simulating coal gas seepage.

[0125] Optionally, based on conductivity, a flow continuity model of the corresponding medium unit in the pore grid of the target stratum coal core is constructed, including: constructing a continuity equation for gas transport between different medium units; establishing the initial gas content in each medium and the conductivity between each medium under initial conditions; establishing the diffusion coefficient and crossflow coefficient in the gas flow equation for each medium diffusing into the fracture medium; and determining the flow continuity model of the corresponding medium in the pore grid of the target stratum coal core based on the gas flow relationship between multiple medium units and the gas diffusion between multiple medium units into the cleavage medium units in the target stratum coal core, wherein the flow continuity model satisfies the following formula: gas change in the corresponding medium unit = gas flow change in the corresponding medium unit (inflow - outflow) - gas amount diffused from the corresponding medium unit to the cleavage medium unit.

[0126] In one implementation, it is assumed that i, j, and k represent macroporous media units, mesoporous media units, and microporous media units in the multi-medium system, respectively. Taking the macroporous media unit as an example, Figure 11 is used to explain how to construct a flow continuity model of the macroporous media unit in the pore grid of the target formation coal core. Figure 11 is a schematic diagram of the gas flow relationship between the multi-medium units provided in the embodiment of this application.

[0127] When constructing a flow continuity model for macroporous media elements within the pore grid of a target coal core, in addition to considering the inflow and outflow of gas from microporous and mesoporous media elements into the macroporous media elements, it is also necessary to consider the diffusion of gas from the macroporous media elements into the cleavage media elements. Therefore, the flow continuity model for macroporous media elements within the pore grid of a target coal core per unit time is as follows:

[0128] Among them, V g,iThis represents the amount of adsorbed gas in a macroporous media unit, expressed in m³. 3 ;p i p j p k These represent the pressures of the macroporous, mesoporous, and microporous media units, respectively, in MPa; q im,f This represents the amount of gas desorbed and diffused from the macroporous medium cell to the cleavage medium cell per unit time.

[0129] Optionally, the amount of adsorbed gas in the macroporous media unit is calculated based on the Langmuir adsorption law governing the amount of gas on the surface of the media unit. Specifically, the amount of adsorbed gas in the macroporous media unit satisfies the following formula:

[0130] Among them, f i V represents the percentage of specific surface area of ​​macroporous dielectric cells; L Represents the volume of a Lancet, in meters (m). 3 ;p L This represents flange pressure, with units of MPa; p i,0 The initial pressure of the macroporous media unit, in MPa; p i This represents the pressure of the macroporous medium unit, expressed in MPa.

[0131] Optionally, the construction method of the flow continuity model of other media elements in the pore grid of the target formation coal core is similar to that of macroporous media elements, and will not be repeated in the embodiments of this application.

[0132] The amount of adsorbed gas in the mesoporous medium unit satisfies the following formula:

[0133] The amount of adsorbed gas in the microporous medium unit satisfies the following formula:

[0134] Among them, f j f k These represent the specific surface area ratios of mesoporous and microporous dielectric units, respectively; p j,0 p k,0 These represent the initial pressure of the mesoporous media unit and the initial pressure of the microporous media unit, respectively; p j p k These represent the pressure of the mesoporous medium unit and the pressure of the microporous medium unit, respectively.

[0135] The flow continuity model of mesoporous media elements in the pore grid of the target formation coal core per unit time is as follows:

[0136] The flow continuity model of microporous media elements in the pore grid of the target formation coal core per unit time is as follows:

[0137] This application embodiment constructs a flow continuity model of the corresponding medium unit in the pore grid of the target stratum coal core based on the conductivity, which can improve the accuracy of the flow continuity model and thus achieve a more accurate simulation of coal gas seepage.

[0138] Optionally, the amount of gas diffusing from the corresponding medium unit to the cleaving medium unit is determined as follows: based on the gas concentration of the corresponding medium unit, the gas concentration of the cleaving medium unit, and the crosstalk coefficient between the corresponding medium and the cleaving medium unit, the amount of gas diffusing from the corresponding medium unit to the cleaving medium unit is determined. Here, the amount of gas diffusing from the medium unit to the cleaving medium unit can be understood as a boundary condition.

[0139] Taking a macroporous dielectric cell as an example, this section explains how to determine the amount of gas diffusing from the macroporous dielectric cell to the cleavage dielectric cell. The amount of gas diffusing from the macroporous dielectric cell to the cleavage dielectric cell satisfies the following formula:

[0140] q im,f =V t σD c (C im -C f )

[0141] Where, q im,f V represents the amount of gas that diffuses from the macroporous medium cell to the cleavage medium cell; t σ represents the total volume of a pore grid in the target formation coal core; σ represents the cross-flow coefficient between macroporous media elements and cleavage media elements; C im The gas concentration representing the macroporous dielectric unit; C f The gas concentration represents the cleavage medium unit.

[0142] It should be noted that the method for determining the amount of gas diffused from the other medium units to the cleavage medium units is similar to the method for determining the amount of gas diffused from the macropore medium units to the cleavage medium units, and will not be repeated in the embodiments of this application.

[0143] Optionally, the amount of gas diffusing from the mesoporous medium unit to the cleavage medium unit satisfies the following formula: q jm,f =V t σD c (C jm -C f )

[0144] The amount of gas diffusing from the microporous medium element to the cleavage medium element satisfies the following formula: q km,f =Vt σD c (C km -C f )

[0145] Where, q jm,f The amount of gas that diffuses from the mesoporous medium unit to the cleavage medium unit; q km,f The amount of gas that diffuses from the microporous medium unit to the cleavage medium unit; C jm The gas concentration representing the mesoporous medium unit; C km This represents the gas concentration within the microporous media unit.

[0146] The embodiments of this application consider the amount of gas diffused from multiple media units to cleavage media units when simulating multi-level pore flow of coal gas, which is more conducive to characterizing the pore structure of coal gas reservoirs.

[0147] Based on the above embodiments, the degree of desorption of the corresponding medium in the target formation coal and rock grid during the numerical simulation is calculated based on the flow continuity model, including: obtaining the pressure of the corresponding medium according to the flow continuity model; determining the current amount of adsorbed gas in the corresponding medium based on the pressure of the corresponding medium; and calculating the degree of desorption of the corresponding medium in the target formation coal and rock grid during the numerical simulation based on the current amount of adsorbed gas in the corresponding medium.

[0148] In this embodiment, it can be understood that when calculating the degree of desorption of the corresponding medium in the target formation coal and rock grid during the numerical simulation based on the flow continuity model of the corresponding medium, it is first necessary to determine the pressure of the corresponding medium according to the flow continuity model of the corresponding medium. Then, based on the determined pressure of the corresponding medium, the current amount of adsorbed gas in the corresponding medium is determined. After determining the amount of adsorbed gas in the corresponding medium, the degree of desorption of the corresponding medium in the target formation coal and rock grid during the numerical simulation is calculated based on the amount of adsorbed gas in the corresponding medium.

[0149] Optionally, the pressure of the corresponding medium, determined based on the flow continuity model of the corresponding medium, can be set according to actual needs.

[0150] In one implementation, taking macroporous media units, mesoporous media units, and microporous media units as examples, three flow continuity models are constructed:

[0151] Where i, j, and k represent macroporous dielectric units, mesoporous dielectric units, and microporous dielectric units, respectively.

[0152] The above three equations can be simplified into three linear equations:

[0153] Rewrite the above three linear equations in matrix form:

[0154] The pressures of macroporous, mesoporous, and microporous media units are obtained by solving the equations using the Jacobi iteration method. The solution principle is as follows: the flow continuity model is represented in matrix form; the matrix flow continuity model is decomposed into diagonal, lower triangular, and upper triangular matrices; an initial solution vector of the flow continuity model is set; based on the initial solution vector, the solution vector of the flow continuity model is iteratively updated until a preset convergence condition is met. Optionally, the specific solution process is shown in Figure 12, which is a schematic diagram of the Jacobi iteration method solution process provided in the embodiment of this application.

[0155] Optionally, the amount of adsorbed gas in the corresponding medium can be calculated based on the pressure of the corresponding medium. The formula for the amount of adsorbed gas in the corresponding medium has been described in the previous embodiments and will not be repeated here.

[0156] After determining the current adsorbed gas quantity of the corresponding medium, the degree of desorption of the corresponding medium in the target formation coal-rock grid during the numerical simulation is calculated based on the current adsorbed gas quantity of the corresponding medium. This calculation, based on the current adsorbed gas quantity of the corresponding medium, includes: determining the initial adsorbed gas quantity and the target adsorbed gas quantity of the corresponding medium, where the initial adsorbed gas quantity refers to the amount of gas adsorbed by the corresponding medium at the initial pressure, and the target adsorbed gas quantity refers to the amount of gas adsorbed by the corresponding medium at the target pressure; determining the desorbed gas quantity based on the initial and target adsorbed gas quantities; and calculating the degree of desorption of the corresponding medium in the target formation coal-rock grid during the numerical simulation based on the desorbed gas quantity.

[0157] This application embodiment calculates the degree of desorption of the corresponding medium in the target formation coal and rock grid during numerical simulation based on a flow continuity model, which can accurately simulate coal and rock gas seepage.

[0158] Next, taking a block in the eastern Ordos Basin as an example, the specific implementation method of the coal and rock gas multi-stage pore seepage simulation method provided in this application will be described. The method includes the following steps:

[0159] Step S1: Collect several coal cores from the Deep 8 coal block and perform CT scanning electron microscopy, high-pressure isothermal adsorption (HP-IA) or nuclear magnetic resonance imaging experiments to obtain the approximate distribution ratio of microporous media units, macroporous media units, and mesoporous media units in the coal rock of this block. Figure 13 is a schematic diagram of the distribution ratio of different media in the coal rock provided in the embodiment of this application. As shown in Figure 13, it can be seen that the Deep 8 coal sample has more macroporous media units and microporous media units, and fewer mesoporous media units. Among them, the pore size of macroporous media units is greater than 20 nm, the pore size of microporous media units is less than 2 nm, and the pore size of mesoporous media units is greater than 2 nm and less than 20 nm. Optionally, it can also be seen from Figure 13 that the proportions of macroporous media units, microporous media units, and mesoporous media units in the Deep 8 coal sample are approximately 25%, 70%, and 5%, with average inner diameter radii of 100 nm, 0.5 nm, and 15 nm, respectively.

[0160] Step S2: Collect several coal cores from the Deep 8 coal block, conduct isothermal adsorption experiments of methane under formation conditions, obtain Langmuir adsorption curves with different adsorption amounts under different pressures, and give initial conditions according to the calculation formula of adsorbed gas amount.

[0161] Step S3: Input the experimental data obtained in S1 into the coalbed methane numerical simulation software to obtain the conductivity between different medium units in a grid;

[0162] Step S4: Calculate the amount of adsorbed gas in a multi-medium unit within a grid based on the experimental data from S1-S3; then import this calculation process into the numerical simulation of single-well production. In the numerical simulation of single-well production, an extended multi-medium model is introduced based on the traditional dual-pore single-permeability model to simulate the non-equilibrium seepage process within the matrix. This allows for the calculation of the pressure drop and desorption degree of microporous, macroporous, and mesoporous media in the coal matrix as the cleavage pressure continuously decreases. This better fits the extraction process of deep coalbed methane, simulates and predicts the production capacity of deep coalbed methane, optimizes development strategies, and improves extraction efficiency.

[0163] Taking the JS6-7P01 well as an example, a single-well model was established for simulation. The specific principle is shown in Figure 14, which is a schematic diagram of the simulated single-well model provided in this embodiment. The coal seam in the JS6-7P01 well is characterized as a dry coal seam with low initial water content in the coal cleavage. The water extracted initially all came from the flowback fluid injected during fracturing. The porosity and permeability of the coal bedrock are extremely low, serving only as a site for adsorbed gas. The average porosity of the cleavage is 0.9%, the average permeability is 0.05 mD, and the average initial water saturation is 10.0%. The Langmuir isotherm adsorption curve of the coal matrix, based on indoor experimental results, shows a maximum adsorption capacity of no more than 30 m³. 3 / t, the density of coal and rock is approximately 1420 kg / m³.3 The ratio of the original adsorbed gas to the free gas is approximately 7:3.

[0164] Optionally, the model provided in this application can be compared with conventional models. In the conventional dual-pore single-permeability model, the matrix contains only one pressure; in the conventional dual-pore single-permeability + MINC model, the matrix contains two pressures, namely macroporous media units and microporous media units, but the microporous media units are not connected to the cleavage media units; in the conventional dual-pore single-permeability + improved multi-media flow model, the matrix contains two pressures, namely macroporous media units and microporous media units, and the microporous media units are connected to the cleavage media units. The specific comparison results are shown in Figure 15, which is a schematic diagram illustrating the simulation calculation comparison results of different models provided in the embodiments of this application. As can be seen from the bottom hole flowing pressure in Figure 15, when simulating constant gas production, the improved multi-medium seepage model, which considers the connection between macroporous, mesoporous, and microporous media units and coal cleavage, can effectively improve the gas supply and stability of coal and rock to cleavage in the later stage of a single well. Moreover, this model has the highest historical fitting rate, and the later flowing pressure fitting rate is over 90%, while the fitting rates of conventional dual-pore single-seepage and MINC models are both less than 70%.

[0165] Taking a coal and rock grid around a well as an example, we extract and analyze the connection relationship of the four media units inside it, as well as the decrease of the partial pressure of each media unit.

[0166] Figure 16 is a schematic diagram illustrating the connection relationship of four coal-rock media units provided in an embodiment of this application. Figure 17 is a schematic diagram illustrating the stepwise pressure drop process of three media units under constant cleavage boundary pressure over time, provided in an embodiment of this application. As can be seen from Figure 17, Figure 17 shows the stepwise pressure drop process of three media units—cleavage media unit, macroporous media unit, mesoporous media unit, and microporous media unit—under constant cleavage boundary pressure over time. It can be seen that the MINC model can simulate the stepwise pressure drop and desorption process inside the coal-rock relatively well.

[0167] In summary, this application provides a method for characterizing the adsorption and desorption of deep coalbed methane in complex multi-scale media. The specific steps include the following three steps: taking the desorption process of a coal-rock grid as an example, the pressure drop process of the partial pressures of the three media units within the coal-rock is characterized. The process is as follows: First, the initial conditions and conduction relationships of each media unit are given. The initial conditions are the initial pressure and initial amount of adsorbed gas in each media unit, and the conduction relationship is the conductivity between every two media units. Then, boundary conditions (the diffusion amount from each media unit to the cleavage medium) are given, and a system of difference equations is written using a numerical simulator for iterative solution.

[0168] Optionally, the coalbed methane multi-level pore flow simulation method provided in this application embodiment can more finely delineate the pore structure inside the coalbed methane, including microporous media units, mesoporous media units, and macroporous media units, thereby more accurately simulating the mass transfer behavior of gas between pores of different scales. It can also describe the interactions between different pore media unit scales, such as methane migration from microporous media units to macroporous media units, and the impact of these processes on overall coalbed methane production. It can be adjusted and optimized for specific coal seam conditions to adapt to different mining technologies and management strategies, providing support for practical engineering design and decision-making. Optionally, through a deep understanding of complex multi-scale media units, this application embodiment can improve the safety and controllability of the coalbed methane extraction process and reduce unexpected hazards during extraction. With further technological maturity and market expansion, it is expected that the method provided in this application embodiment will drive the development of related industrial chains in the coming years.

[0169] The following are embodiments of the apparatus described in this application, which can be used to execute the embodiments of the method described in this application. For details not disclosed in the apparatus embodiments of this application, please refer to the embodiments of the method described in this application.

[0170] Figure 18 is a schematic diagram of the structure of the coal and rock gas multi-stage pore seepage simulation device provided in this application. As shown in Figure 18, the coal and rock gas multi-stage pore seepage simulation device 1800 provided in this embodiment includes:

[0171] The acquisition module 1801 is used to acquire the initial information of the target stratum coal core and the medium information of the multiple medium units. The medium information includes the basic information of the medium and the gas flow relationship between the multiple medium units.

[0172] The first determining module 1802 is used to determine the conductivity between any two media units in the target stratum coal core based on media information and initial information.

[0173] Module 1803 is used to construct a flow continuity model of the corresponding medium element in the pore grid of the target formation coal core based on the conductivity.

[0174] The second determining module 1804 is used to calculate the degree of desorption of the corresponding medium in the target formation coal and rock grid during the numerical simulation based on the flow continuity model. The degree of desorption is used to reflect the multi-level desorption law of the coal and rock gas grid.

[0175] In one possible implementation, the first determining module 1802 is specifically used for:

[0176] Based on the pore structure of the coal core of the target stratum, the gas transport flow rate between any two media units is determined according to the medium information and initial information, wherein the gas flows between any two media units.

[0177] The conductivity between two media units is obtained based on the gas transport flow rate between any two media units.

[0178] In one possible implementation, the gas transport flow rate between any two media units satisfies the following formula:

[0179] Among them, Q M-N This represents the gas transport flow rate between any two media units; N1 represents the total number of pores; M represents the first media; N represents the second media; g M-N,tot L represents the shape factor between two dielectric units; M-N,tot Δp represents the characteristic length of the pore throat between two dielectric units. M-N represents the pressure difference between any two media units; m represents the ratio of the number of pores in a single layer of media to the total number of pores.

[0180] In one possible implementation, the construction module 1803 is specifically used for:

[0181] Construct a continuity equation for gas transport between different media units;

[0182] Establish the initial gas content in each medium and the conductivity between each medium under the initial conditions;

[0183] Establish the diffusion coefficient and crossflow coefficient in the gas flow equation for each medium diffusing into the fracture medium;

[0184] Based on the gas flow relationships between multiple media units and the diffusion of gas from multiple media units to the cleavage media units in the target coal core, a flow continuity model for the corresponding media in the pore grid of the target coal core is determined. The flow continuity model satisfies the following formula: Gas change in the corresponding media unit = Gas flow change in the corresponding media unit (inflow - outflow) - Gas diffusion from the corresponding media unit to the cleavage media unit.

[0185] In one possible implementation, the amount of gas diffusing from the corresponding medium unit to the cleavage medium unit is determined by the following method:

[0186] The amount of gas diffused from the corresponding medium unit to the cleavage medium unit is determined based on the gas concentration of the corresponding medium unit, the gas concentration of the cleavage medium unit, and the cross-flow coefficient between the corresponding medium and the cleavage medium unit.

[0187] In one possible implementation, the second determining module 1804 is specifically used for:

[0188] Based on the flow continuity model, the pressure of the corresponding medium is obtained;

[0189] Based on the pressure of the corresponding medium, determine the current amount of adsorbed gas in the corresponding medium;

[0190] Based on the current amount of adsorbed gas in the corresponding medium, determine the degree of desorption of different media in the target formation coal core.

[0191] In one possible implementation, the second determining module 1804 is used to:

[0192] Determine the initial adsorbed gas quantity and the target adsorbed gas quantity of the corresponding medium. The initial adsorbed gas quantity refers to the amount of gas adsorbed by the corresponding medium at the initial pressure, and the target adsorbed gas quantity refers to the amount of gas adsorbed by the corresponding medium at the target pressure.

[0193] The amount of desorbed gas is determined based on the initial amount of adsorbed gas and the target amount of adsorbed gas.

[0194] Based on the amount of desorbed gas, the degree of desorption for different media in the numerical model of coal and rock gas in the target formation is determined.

[0195] The coal and rock gas multi-stage pore seepage simulation device provided in this embodiment can execute the method provided in the above method embodiment. Its implementation principle and technical effect are similar, and will not be described in detail here.

[0196] It should be noted that the division of the various modules in the above device is merely a logical functional division. In actual implementation, they can be fully or partially integrated into a single physical entity, or they can be physically separated. Furthermore, these modules can be implemented entirely in software via processing element calls; they can be fully implemented in hardware; or some modules can be implemented by processing element calls to software, while others are implemented in hardware. For example, a processing module can be a separate processing element, or it can be integrated into a chip within the device. Alternatively, it can be stored as program code in the device's memory, and its functions can be called and executed by a processing element. The implementation of other modules is similar. Moreover, these modules can be fully or partially integrated together, or they can be implemented independently. The processing element here can be an integrated circuit with signal processing capabilities. During implementation, each step of the above method or each of the above modules can be completed through integrated logic circuits in the hardware of the processor element or through software instructions.

[0197] For example, these modules can be one or more integrated circuits configured to implement the above methods, such as one or more Application Specific Integrated Circuits (ASICs), one or more Digital Signal Processors (DSPs), or one or more Field Programmable Gate Arrays (FPGAs). As another example, when a module is implemented by calling program code through a processing element, that processing element can be a general-purpose processor, such as a Central Processing Unit (CPU) or other processor capable of calling program code. Furthermore, these modules can be integrated together to implement a System-On-a-Chip (SOC).

[0198] Figure 19 is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. As shown in Figure 19, the electronic device 1900 provided in this embodiment may include: a processor 1901, and a memory 1902 communicatively connected to the processor, wherein:

[0199] The memory stores the instructions that the computer executes;

[0200] The processor executes computer execution instructions stored in memory to implement the method described in the foregoing method embodiments.

[0201] It should be understood that processor 1901 can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. A general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in the application can be directly manifested as execution by a hardware processor, or execution by a combination of hardware and software modules within the processor. Memory 1902 may include high-speed random access memory (RAM), and may also include non-volatile memory (NVM), such as at least one disk storage device, or a USB flash drive, external hard drive, read-only memory, disk, or optical disc, etc.

[0202] Optionally, the electronic device 1900 may also include a communication interface 1903. In specific implementations, if the communication interface 1903, memory 1902, and processor 1901 are implemented independently, they can be interconnected via a bus to complete communication. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc., but this does not imply that there is only one bus or one type of bus.

[0203] Optionally, in a specific implementation, if the communication interface 1903, memory 1902, and processor 1901 are integrated on a single chip, then the communication interface 1903, memory 1902, and processor 1901 can communicate through an internal interface.

[0204] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed, are used to implement the methods described in any of the foregoing embodiments.

[0205] It is understood that the computer-readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read Only Memory (EEPROM), Erasable Programmable Read Only Memory (EPROM), Programmable Read Only Memory (PROM), Read Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium can be any available medium accessible to a general-purpose or special-purpose computer.

[0206] An exemplary computer-readable storage medium is coupled to a processor, enabling the processor to read information from and write information to the computer-readable storage medium. Of course, the computer-readable storage medium can also be a component of the processor. The processor and the computer-readable storage medium can reside in an ASIC. Alternatively, the processor and the computer-readable storage medium can exist as discrete components in an electronic device.

[0207] The integrated modules implemented as software functional modules described above can be stored in a computer-readable storage medium. These software functional modules, stored in a computer-readable storage medium, include several instructions to cause an electronic device (which may be a personal computer, server, or network device, etc.) or processor to execute some steps of the methods described in the various embodiments of this application.

[0208] This application also provides a computer program product, including a computer program that, when executed, implements the method described in any of the foregoing embodiments.

[0209] This application also provides a computer program that, when run on a computer, causes the computer to execute the method steps as described in the above method embodiments. The specific implementation and technical effects are similar and will not be repeated here.

[0210] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are all optional embodiments, and the actions and modules involved are not necessarily essential to this application.

[0211] It should be further noted that although the steps in the flowchart are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowchart may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the sub-steps or stages of other steps.

[0212] In the above embodiments, the descriptions of each embodiment have their own emphasis. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments. The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as these combinations of technical features do not contradict each other, they should be considered within the scope of this specification.

[0213] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the following claims.

[0214] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

[0215] The above is a detailed description of the preferred embodiments of this application, but this application is not limited to the embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of this application, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A method for simulating multi-stage pore flow in coal and rock gas, comprising: The initial information of the target formation coal core and the medium information of multiple medium units are obtained. The medium information includes basic medium information and the gas flow relationship between multiple medium units. Based on the medium information and the initial information, determine the conductivity between any two medium units in the target formation coal core; Based on the conductivity, a flow continuity model of the corresponding medium element in the pore grid of the target stratum coal core is constructed; Based on the flow continuity model, the degree of desorption of the corresponding medium in the target formation coal-rock grid is calculated during the numerical simulation. The degree of desorption is used to reflect the multi-stage desorption law of the coal-rock gas grid.

2. The method according to claim 1, wherein determining the conductivity between any two media units in the target formation coal core based on the media information and the initial information comprises: Based on the pore structure of the target stratum coal core, and according to the medium information and the initial information, the gas transport flow rate between any two medium units is determined, wherein the gas between any two medium units flows into each other. The conductivity between the two media units is obtained based on the gas transport flow rate between any two media units.

3. The method according to claim 2, wherein the gas transport flow rate between any two media units satisfies the following formula: in, Q M-N N1 represents the gas transport flow rate between any two media units; N1 represents the total number of pores. M and N represent any two media (macropores, mesopores, and micropores); g M-N,tot L represents the shape factor between two dielectric units; M-N,tot Represents the throat characteristic length between two dielectric units; Δ p M-N Represents the pressure difference between any two media units; m represents the ratio of the number of pores in a single layer of medium to the total number of pores.

4. The method according to any one of claims 1 to 3, wherein constructing a continuous flow model of the corresponding medium element in the target formation pore grid based on the conductivity comprises: Construct a continuity equation for gas transport between different media units; Establish the initial gas content in each medium and the conductivity between each medium under the initial conditions; Establish the diffusion coefficient and crossflow coefficient in the gas flow equation for each medium diffusing into the fracture medium; Based on the gas flow relationships between the multiple media units and the diffusion of gas from the multiple media units to the cleavage media units in the target coal core, a flow continuity model for the corresponding medium in the pore grid of the target coal core is determined. The flow continuity model satisfies the following formula: gas change per unit time of the corresponding media unit = gas flow change of the corresponding media unit (inflow - outflow) - amount of gas diffused from the corresponding media unit to the cleavage media unit.

5. The method according to claim 4, wherein the amount of gas diffused from the corresponding medium unit to the cleavage medium unit is determined by the following method: The amount of gas diffused from the corresponding medium unit to the cleavage medium unit is determined based on the gas concentration of the corresponding medium unit, the gas concentration of the cleavage medium unit, and the cross-flow coefficient between the corresponding medium and the cleavage medium unit.

6. The method according to any one of claims 1 to 3, wherein calculating the degree of desorption of the corresponding medium in the target formation coal-rock grid during the numerical simulation based on the flow continuity model includes: Based on the aforementioned flow continuity model, the pressure of the corresponding medium is obtained; Based on the pressure of the corresponding medium, determine the current amount of adsorbed gas in the corresponding medium; Based on the current amount of adsorbed gas in the corresponding medium, the degree of desorption of the corresponding medium in the target formation coal and rock grid during the numerical simulation is calculated.

7. A multi-stage pore flow simulation device for coal and rock gas, comprising: The acquisition module is used to acquire the initial information of the target stratum coal core and the medium information of the multiple medium units. The medium information includes basic medium information and the gas flow relationship between the multiple medium units. The first determining module is used to determine the conductivity between any two media units in the target stratum coal core based on the medium information and the initial information. A construction module is used to construct a flow continuity model of the corresponding medium unit in the pore grid of the target stratum coal core based on the conductivity. The second determining module is used to calculate the degree of desorption of the corresponding medium in the target formation coal-rock grid during the numerical simulation based on the flow continuity model. The degree of desorption is used to reflect the multi-level desorption law of the coal-rock gas grid.

8. An electronic device, comprising: Memory, processor; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory, causing the processor to perform the method as described in any one of claims 1-6.

9. A computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the method as claimed in any one of claims 1-6.

10. A computer program product comprising a computer program that, when executed by a processor, implements the method of any one of claims 1-6.

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