Anisotropic coal-rock adsorption-permeability coupling model and seepage evolution method

Abstract

The present invention relates to the technical field of coal rock seepage evolution information data processing, and in particular provides an anisotropic coal rock adsorption-permeability coupling model and a seepage evolution method; the method comprises: pre-processing the collected raw data of coal rock, identifying the anisotropic characteristics of coal rock, analyzing and calculating according to the anisotropic characteristics, and obtaining the water and gas coal rock deformation characteristic permeability; constructing a permeability coupling model, simulating the seepage evolution process of coal rock, and obtaining the coal rock deformation characteristic permeability; comparing the water and gas coal rock deformation characteristic permeability with the coal rock deformation characteristic permeability to verify the simulation accuracy. The present invention can more accurately predict the permeability changes of coal rock under different conditions, and provides a scientific basis for projects such as coal seam water injection and gas extraction; by considering the anisotropic characteristics of coal rock and the influence of multiple factors, a more accurate permeability coupling model is constructed, which improves the prediction accuracy and practicality of the permeability coupling model.

Description

Technical Field

[0001] The invention relates to the technical field of coal rock seepage evolution information data processing, and in particular to an anisotropic coal rock adsorption-permeability coupling model and a seepage evolution method. Background Art

[0002] Coal rock adsorption-permeability is affected by many factors, including stress, temperature, water content, and slippage effect. For example, with the increase of pore pressure, the adsorption capacity of coal rock increases, resulting in a smaller gas seepage channel and a lower permeability. In addition, the presence of water in the pores of coal rock will form a water film, occupying the effective seepage channel of gas, thereby reducing the permeability; in practical applications, researchers have established different models to describe the variation of coal rock adsorption-permeability. For example, models that consider factors such as stress, adsorption deformation, water content, and water film thickness can better characterize the permeability evolution law of water-bearing coal rock. These models usually need to be verified by experimental data to ensure their accuracy and applicability. Coal rock adsorption-permeability is a complex multi-factor coupling phenomenon, and its research is of great significance for optimizing coalbed methane development, improving gas extraction efficiency, and preventing and controlling coal mine gas disasters.

[0003] Prior art 1, Chinese patent, application number: 202110057078.7 discloses a method for gas drilling arrangement based on true triaxial stress and dynamic changes in permeability, including: anisotropic test of coal rock permeability in undisturbed state; anisotropic test of coal rock permeability in disturbed state; simulation optimization of gas extraction drilling arrangement; establishment of a dynamic anisotropic permeability model under true triaxial stress conditions based on bedding effect; comparison of gas extraction effects and guidance of drilling operations. Through comprehensive experimental testing of the anisotropic permeability of coal and rock masses, the three-dimensional permeability of coal seams and their dynamic changes are obtained, and then the gas flow characteristics around the boreholes are simulated in combination with numerical simulation software. Although the drilling arrangement parameters are optimized to provide a theoretical basis and technical guidance for gas drilling arrangement, the problem of reduced permeability due to the adsorption and expansion effect of coal rock as the pore pressure increases is not taken into account.

[0004] Prior art 2, Chinese patent, application number: 201810376917.X discloses a method for accurately calculating the density of coal rock using CT images, including the following steps: obtaining the overall density of the coal rock through CT scanning, and obtaining the density of the overall coal rock through calibration, and obtaining the accurate mass of the entire coal rock through measurement, and calculating the overall volume of the coal rock sample; obtaining the pore structure characteristics of the coal rock sample through the image features obtained by CT scanning, and extracting the volume of the pore structure according to the CT image, and calculating the real volume V0 of the coal rock; calculating the actual accurate density according to the volume and mass through the density calculation formula; although it solves the problem of how to accurately obtain the accuracy of the density of coal rock through CT scanning data and images, it can also control the accuracy of the obtained results according to needs, meeting the needs of multiple accuracies and multiple component density accuracies; but it does not take into account the problem of moisture affecting adsorption and permeability characteristics.

[0005] Prior art three, Chinese patent, application number: 202110090029.3 discloses a transient testing system for the seepage evolution law of low-permeability coal rock, including a tri-axial core clamp, an upstream fluid supply device, and a downstream fluid circulation device; the upstream fluid supply device includes a plurality of upstream gas standard chambers connected in series, the upstream gas standard chamber at the head end is connected to the gas source, and the upstream gas standard chamber at the tail end is connected to the air inlet port of the tri-axial core clamp; the downstream fluid circulation device includes a plurality of downstream gas standard chambers connected in series, and the downstream gas standard chamber at the head end is connected to the air outlet port of the tri-axial core clamp; although the volume of the upstream and downstream gas standard chambers is adjusted to test the influence of different volumes on the permeability; but it does not take into account the problem that the slippage effect will weaken or disappear as the pressure increases.

[0006] At present, the existing technologies 1, 2 and 3 do not take into account the fact that as the pore pressure increases, the adsorption and expansion effect of coal rock leads to a decrease in permeability, the effect of moisture on adsorption and permeability characteristics, and the slippage effect weakens or disappears as the pressure increases. Therefore, the present invention provides an anisotropic coal rock adsorption-permeability coupling model and a seepage evolution method. Summary of the invention

[0007] The main purpose of the present invention is to provide an anisotropic coal rock adsorption-permeability coupling model and a seepage evolution method to solve the problems in the prior art that the adsorption expansion effect of coal rock leads to a decrease in permeability with the increase of pore pressure, the influence of moisture on adsorption and permeability characteristics, and the slippage effect will weaken or disappear with the increase of pressure.

[0008] In order to achieve the above object, the present invention adopts the following technical scheme:

[0009] In one aspect of the present invention, an anisotropic coal rock adsorption-permeability coupling model and a seepage evolution method are provided, and the anisotropic coal rock adsorption-permeability coupling model and the seepage evolution method include the following steps:

[0010] Collect raw coal rock data, pre-process the raw coal rock data, identify the anisotropic characteristics of coal rock; analyze the anisotropic characteristics, calculate the analysis results, and obtain the water and gas coal rock deformation characteristic permeability;

[0011] Construct a permeability coupling model and set the parameters of the permeability coupling model according to historical experimental data; output the analysis results to the permeability coupling model to simulate the seepage evolution; obtain the characteristic permeability of simulated coal rock deformation;

[0012] The characteristic permeability of coal rock deformation with water and gas is compared with the characteristic permeability of simulated coal rock deformation to verify the accuracy of the permeability coupling model; a comparison permeability threshold is preset. If it is greater than the comparison permeability threshold, the permeability coupling model data is adjusted and the seepage evolution is re-simulated; it is iterated sequentially to obtain the final permeability coupling model.

[0013] In an optional embodiment, the process of obtaining the characteristic permeability of water and gas coal rock deformation includes the following steps:

[0014] Collect raw data of coal and rock to obtain coal and rock image data and microstructure image data; extract the overall characteristics, horizontal and vertical characteristics of coal and rock images; analyze the overall characteristics, horizontal and vertical characteristics of coal and rock images;

[0015] Based on the analysis results, the visualization of the micro- and mesoscopic structures of complex porous media and the description of multi-scale and anisotropy are obtained; the overall fractal dimension and porosity of coal and rock, and the three-dimensional spatial distribution data of anisotropy distribution are calculated based on the characteristic images;

[0016] The coal rocks are grouped and automatically identified according to their reflectivity and morphological parameters; the deformation characteristic permeability of water and gas in the coal rocks is calculated based on the coal rock groupings.

[0017] In an optional implementation, the process of analyzing the overall characteristics, horizontal direction characteristics, and vertical direction characteristics of the coal rock image includes the following steps:

[0018] Obtain the overall density of the coal rock, obtain the density of the entire coal rock through calibration, measure the accurate mass of the entire coal rock, and calculate the overall volume of the coal rock; obtain the pore structure characteristics by acquiring the image features, and extract the volume of the pore structure according to the image;

[0019] The actual accurate density is calculated according to the volume and mass through the density calculation formula, and the coal rock image is sliced ​​horizontally and in the processing direction according to the accurate density to extract the grayscale distribution and texture characteristics in each direction;

[0020] By calculating the grayscale distribution and texture features in each direction, the microscopic properties of coal and rock images and the microscopic properties of complex media are analyzed.

[0021] In an optional implementation, the process of distributing data in a three-dimensional space with anisotropic distribution includes the following steps:

[0022] Preprocess the coal-rock image, smooth the image, segment the image, set the grayscale threshold, and separate the pore part from the matrix part in the coal-rock image;

[0023] Calculate the fractal dimension of coal rock, divide the image into grids of different sizes, count the network grids covering the pore area, calculate the relationship between the grid size, and obtain the fractal dimension; reconstruct the coal rock in three dimensions, calculate it, and obtain the porosity;

[0024] The fractal dimension and porosity data of coal rock are analyzed to obtain the isotropic distribution characteristics and their distribution in three-dimensional space.

[0025] In an optional embodiment, the process of deforming characteristic permeability comprises the following steps:

[0026] Automatically identify coal and rock based on their reflectivity and morphological parameters; combine coal and rock microscopic grouping with reflectivity and morphological parameters, draw a full component reflectivity map based on the relationship between grayscale value and reflectivity, and obtain the coal and rock component content based on inflection point cutting and division;

[0027] The coal rocks are grouped according to reflectivity and morphological parameters, and the image information is classified into different categories;

[0028] According to the results of coal-rock grouping, the deformation characteristic permeability of water and gas in coal-rock is calculated according to the pore structure of coal-rock and the response under different stress conditions.

[0029] In an optional implementation, the process of deriving the characteristic permeability of simulated coal rock deformation includes the following steps:

[0030] The permeability coupling model parameters are set according to the historical experimental data; the initial permeability of the coal rock is set according to the historical experimental data; and the coefficient of the increase in the pore surface area is set according to the pore structure of the coal rock and the historical experimental data; the volume strain of the coal rock is set according to the deformation data of the coal rock;

[0031] The analysis results are output to the permeability coupling model to simulate the seepage evolution; the relationship between permeability and factors such as effective stress and gas pressure is calculated, and the permeability function of coal rock under different stress conditions is established to obtain the seepage evolution results;

[0032] According to the simulated seepage evolution results, the anisotropic evolution characteristics of coal rock permeability changing with time, stress, gas pressure and other factors are analyzed; the simulation results are compared with historical experimental data, and a comparison threshold is preset. If it is greater than the comparison threshold, the model parameters are optimized.

[0033] In an optional implementation, the process of setting the volume strain of coal rock includes the following steps:

[0034] According to the historical experimental data, the permeability coupling model parameters are selected and set, including the porosity, fractal dimension and fracture inclination of coal and rock; the different porosity and fracture structure parameters in the historical experimental data are analyzed to calculate the initial permeability;

[0035] According to the pore structure of coal rock and historical experimental data, the change of initial permeability and the change of internal pores of coal rock are analyzed to obtain the increase of pore surface area; the coefficient of the increase of pore surface area is set;

[0036] The porosity is analyzed according to the deformation data of coal rock to obtain the law of porosity change with stress; the deformation data of coal rock is obtained by analyzing the change law of stress and porosity of coal rock, and the volume strain of coal rock is set.

[0037] In an optional embodiment, the process of anisotropic evolution characteristics comprises the following steps:

[0038] Extract the characteristics of the simulated seepage evolution results, analyze the changes of coal-rock seepage at different time points, different stress conditions and different gas pressures; draw the curve of permeability change with time, stress and gas pressure, and identify the peak value, valley value and time point of permeability change;

[0039] Preprocess the historical experimental data and extract features; draw the variation curve of the permeability of the historical experimental data with time, stress and gas pressure; compare the variation curve of the historical experimental data with the simulation variation curve; calculate the correlation coefficient, mean square error, mean absolute error and other indicators;

[0040] A comparison threshold is set. If the comparison result exceeds the threshold, the abnormal points exceeding the threshold are identified and analyzed; and the permeability coupling model is adjusted according to the analysis results.

[0041] In an optional implementation, the process of obtaining the final permeability coupling model comprises the following steps:

[0042] Compare the water and gas coal rock deformation characteristic permeability with the simulated coal rock deformation characteristic permeability, calculate the correlation coefficient and mean square error and other indicators; set the accuracy threshold, and perform analysis if it is greater than the accuracy threshold;

[0043] The comparison results are used to analyze the permeability under different stress states and the difference in permeability at micro and macro scales; a comparison permeability threshold is preset, and if it is greater than the comparison permeability threshold, the permeability coupling model parameters are adjusted to perform simulation;

[0044] The threshold of the model parameters after comparison and adjustment is set, and the adjusted model permeability coupling model results are compared with the initial permeability coupling model parameter results. If it is greater than the threshold, the initial permeability, fracture structure parameters, Young's modulus, Poisson's ratio, etc. are adjusted; it is iterated in sequence; and the final permeability coupling model is obtained.

[0045] Another aspect of the present invention provides an anisotropic coal rock adsorption-permeability coupling model system for implementing the permeability evolution method of the anisotropic coal rock adsorption-permeability coupling model, comprising:

[0046] The feature analysis module is responsible for collecting and preprocessing the raw data of coal and rock, identifying the anisotropic characteristics of coal and rock; analyzing the anisotropic characteristics, calculating the analysis results, and obtaining the water and gas coal and rock deformation characteristic permeability;

[0047] The model building module is responsible for building the permeability coupling model and setting the parameters of the permeability coupling model according to historical experimental data; outputting the analysis results to the permeability coupling model to simulate the seepage evolution; and obtaining the characteristic permeability of the simulated coal rock deformation;

[0048] The model update module is responsible for comparing the characteristic permeability of coal rock deformation with the simulated characteristic permeability of coal rock deformation to verify the accuracy of the permeability coupling model; preset a comparison permeability threshold, if it is greater than the comparison permeability threshold, adjust the permeability coupling model data and re-simulate the seepage evolution; iterates in sequence to obtain the final permeability coupling model.

[0049] The present invention collects raw data of coal and rock for preprocessing, identifies the anisotropic characteristics of coal and rock, constructs a permeability coupling model, simulates the seepage evolution process of coal and rock, and obtains the deformation characteristic permeability of coal and rock; adjusts the permeability model according to the deformation characteristic of coal and rock, and obtains the final permeability coupling model; the present invention can more accurately predict the permeability changes of coal and rock under different conditions, and provides a scientific basis for projects such as coal seam water injection and gas extraction; by considering the anisotropic characteristics of coal and rock and the influence of multiple factors, a more accurate permeability coupling model is constructed, which improves the prediction accuracy and practicality of the permeability coupling model. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0051] Figure 1 A flow chart of a seepage evolution method for an anisotropic coal rock adsorption-permeability coupling model provided in Example 1 of the present invention;

[0052] Figure 2 This is a flow chart of deriving water and gas coal rock deformation characteristic permeability of the seepage evolution method of the anisotropic coal rock adsorption-permeability coupling model in Example 2 of the present invention;

[0053] Figure 3 A flow chart for analyzing the overall characteristics, horizontal direction characteristics and vertical direction characteristics of a coal rock image in the seepage evolution method of the anisotropic coal rock adsorption-permeability coupling model in Example 3 of the present invention;

[0054] Figure 4 It is a flow chart of the three-dimensional spatial distribution data of the anisotropic distribution of the seepage evolution method of the anisotropic coal rock adsorption-permeability coupling model in Example 4 of the present invention;

[0055] Figure 5 It is a flow chart of deformation characteristic permeability of the seepage evolution method of the anisotropic coal rock adsorption-permeability coupling model in Example 5 of the present invention;

[0056] Figure 6 A flow chart of deriving the characteristic permeability of simulated coal rock deformation in the seepage evolution method of the anisotropic coal rock adsorption-permeability coupling model in Example 6 of the present invention;

[0057] Figure 7 This is a flow chart of setting the volume strain of coal rock in the seepage evolution method of the anisotropic coal rock adsorption-permeability coupling model in Example 7 of the present invention;

[0058] Figure 8 This is a process diagram for obtaining the seepage evolution result in Example 8 of the present invention;

[0059] Fig. 9 is a process diagram for calculating the seepage rate and the seepage path in Example 9 of the present invention;

[0060] Fig.10 It is a flow chart of anisotropic evolution characteristics of the seepage evolution method of the anisotropic coal rock adsorption-permeability coupling model in Example 10 of the present invention;

[0061] Fig.11This is a flow chart of obtaining the final permeability coupling model of the seepage evolution method of the anisotropic coal rock adsorption-permeability coupling model in Example 11 of the present invention;

[0062] Fig.12 A block diagram of the anisotropic coal rock adsorption-permeability coupling model system provided in Example 12 of the present invention;

[0063] Fig.13 is a block diagram of an electronic device provided in Embodiment 13 of the present invention;

[0064] Fig.14 This is a block diagram of the computer-readable storage medium provided in Example 14 of the present invention. DETAILED DESCRIPTION

[0065] The technical solutions in the embodiments of the present invention will be described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0066] In the following, the terms "first", "second", etc. are used only for convenience of description and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0067] In the present invention, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense, for example, "connection" can be a fixed mechanical connection, or a detachable mechanical connection, or integrated; or, "connection" can be a direct connection, or an indirect connection through an intermediate medium. In addition, unless otherwise clearly specified and limited, the term "coupling" should be understood in a broad sense, for example, "coupling" can be a direct electrical connection, such as physical contact and electrical conduction between two components, and can also be understood as electrical connection between different components in a circuit structure through physical lines such as copper foil or wires on a printed circuit board (PCB) that can transmit electrical signals to transmit electrical signals; or, "coupling" can be an indirect electrical connection between two components through an intermediate medium; or, "coupling" can be an electrical connection between two components in an air-spaced / non-contact manner, for example, two components are electrically connected by capacitive coupling to transmit electrical signals.

[0068] In the embodiments of the present invention, directional terms such as "up", "down", "left" and "right" may be defined including but not limited to the orientation relative to the schematic placement of the components in the drawings. It should be understood that these directional terms may be relative concepts, which are used for relative description and clarification, and may change accordingly according to the change of the orientation of the components in the drawings.

[0069] The embodiments of the present invention can be used in the fields of coal seam data and gas extraction or other mineral resource mining and environmental protection; the key technical features of the embodiments of the present invention are described as follows: by collecting the original data of coal rocks for preprocessing, identifying the anisotropic characteristics of coal rocks, and constructing a permeability coupling model, simulating the seepage evolution process of coal rocks, and obtaining the deformation characteristic permeability of coal rocks; adjusting the permeability model according to the deformation characteristics of coal rocks to obtain the final permeability coupling model; adjusting the mining data according to the simulation results; the present invention can more accurately predict the permeability changes of coal rocks under different conditions, and provide a scientific basis for projects such as coal seam water injection and gas extraction; by considering the anisotropic characteristics of coal rocks and the influence of multiple factors, a more accurate permeability coupling model is constructed, which improves the prediction accuracy and practicality of the permeability coupling model.

[0070] Embodiment 1:

[0071] like Figure 1 As shown, an embodiment of the present invention provides an anisotropic coal rock adsorption-seepage evolution method, comprising the following steps:

[0072] Step S100: Collecting raw data of coal and rock, and pre-processing the raw data of coal and rock to identify the anisotropic characteristics of coal and rock; analyzing the anisotropic characteristics, and calculating the analysis results to obtain the water and gas coal and rock deformation characteristic permeability;

[0073] Among them, anisotropic characteristics include anisotropy of permeability, anisotropy of mechanical properties and anisotropy of pore structure; coal rock raw data include physical properties, structural characteristics and stress state of coal rock;

[0074] Step S200: construct a permeability coupling model, set the permeability coupling model parameters according to historical experimental data; output the analysis results to the permeability coupling model, simulate the seepage evolution thereof; and obtain the simulated coal rock deformation characteristic permeability;

[0075] Among them, the key parameters include initial permeability, fracture structure parameters, Young's modulus, Poisson's ratio, etc.;

[0076] Step S300: Compare the characteristic permeability of coal rock deformation with water and gas with the characteristic permeability of simulated coal rock deformation to verify the accuracy of the permeability coupling model; preset a comparison permeability threshold, if it is greater than the comparison permeability threshold, adjust the permeability coupling model data and re-simulate the seepage evolution; iterate in sequence to obtain the final permeability coupling model.

[0077] In the above embodiment, in step S100, by collecting the original data of coal rock and performing preprocessing, the anisotropic characteristics of the permeability, mechanical properties and pore structure of coal rock can be accurately identified. The anisotropic characteristics of the permeability, mechanical properties and pore structure of coal rock are crucial to understanding the physical properties and structural characteristics of coal rock. In this embodiment, the deformation characteristic permeability of water and gas coal rock can be obtained by analyzing and calculating the anisotropic characteristics. The permeability of coal rock under different conditions is predicted to provide basic data for subsequent simulations and experiments. In step S200, the deformation characteristic permeability of water and gas coal rock is compared with the deformation characteristic permeability of simulated coal rock, and the accuracy of the permeability coupling model can be verified. If the comparison permeability is greater than the preset threshold, the permeability coupling model data is adjusted and the seepage evolution is simulated again. Improve its prediction accuracy and provide a more accurate reference for practical applications. In step S300, the deformation characteristic permeability of water and gas coal rock is compared with the deformation characteristic permeability of simulated coal rock, and the accuracy of the permeability coupling model can be verified. If the contrast permeability is greater than the preset threshold, the permeability coupling model data is adjusted and the seepage evolution is re-simulated. In this embodiment, by identifying anisotropic characteristics, calculating deformation characteristic permeability, and constructing and verifying the permeability coupling model, the accuracy of coal rock permeability prediction can be significantly improved. By simulating seepage evolution and verifying model accuracy, theoretical support and reference can be provided for practical applications such as coalbed methane extraction, coal mine gas disaster prediction and prevention. By adjusting the permeability coupling model data, this embodiment can continuously optimize the model, improve its prediction accuracy, and provide a more accurate reference for practical applications.

[0078] Embodiment 2:

[0079] like Figure 2 As shown, based on Example 1, the process of obtaining the water and gas coal rock deformation characteristic permeability in step S100 provided in the embodiment of the present invention includes the following steps:

[0080] Step S101: Collecting raw data of coal and rock to obtain coal and rock image data and microstructure image data; extracting overall features, horizontal and vertical features of the coal and rock image; analyzing the overall features, horizontal and vertical features of the coal and rock image;

[0081] Step S102: Based on the analysis results, visualization of the micro- and mesoscopic structures of complex porous media and description of multi-scale and anisotropy are obtained; the overall fractal dimension and porosity of the coal rock and the three-dimensional spatial distribution data of the anisotropic distribution are calculated based on the characteristic images;

[0082] Step S103: automatically identifying the coal rocks by grouping them according to their reflectivity and morphological parameters; and calculating the deformation characteristic permeability of water and gas in the coal rocks according to the coal rock groupings.

[0083] In the above embodiment, in step S101, the coal rock original data is collected to obtain the coal rock image data and its microstructure image data, and the overall characteristics, horizontal and vertical characteristics of the coal rock image are extracted, and then these characteristics are analyzed. In-depth understanding of the physical properties of coal rock, such as crack distribution, porosity, etc. This embodiment can provide basic data support for subsequent coal rock identification and evaluation by analyzing the characteristics. In step S102, according to the analysis results, the visualization of the micro and micro structures of complex porous media and the multi-scale, anisotropic description are obtained. At the same time, the overall fractal dimension and porosity of coal rock, as well as the anisotropic distribution data in three-dimensional space are calculated. The overall fractal dimension and porosity of coal rock, as well as the anisotropic distribution data in three-dimensional space describe the complexity and diversity of the internal structure of coal rock, so as to better understand its physical properties, such as permeability and strength. In addition, the relationship between fractal dimension and porosity and permeability also shows the importance of analysis methods in engineering applications. In step S103, the reflectivity and morphological parameters of the coal rock are used for automatic identification, and the deformation characteristic permeability of water and gas in the coal rock is calculated based on the identification results. The subjectivity of the identification of the microscopic components of the coal rock is significantly reduced, and the accuracy and efficiency of the identification are improved. This embodiment can quickly obtain coal rock component information through automatic identification technology, providing a scientific basis for coalbed methane development, gas control, etc.

[0084] Embodiment 3:

[0085] like Figure 3 As shown, based on Example 2, the process of analyzing the overall characteristics, horizontal direction characteristics and vertical direction characteristics of the coal rock image in step S101 provided in the embodiment of the present invention includes the following steps:

[0086] Step S1011: Obtain the overall density of the coal rock. Obtain the density of the entire coal rock through calibration, measure the accurate mass of the entire coal rock, and calculate the overall volume of the coal rock; obtain the pore structure characteristics by acquiring image features, and extract the volume of the pore structure according to the image;

[0087] Step S1012: Calculate the actual accurate density according to the volume and mass through the density calculation formula, slice the coal rock image in the horizontal and processing directions according to the accurate density, and extract the grayscale distribution and texture features in each direction;

[0088] Step S1013: Analyze the microscopic description of the coal and rock images and the microscopic description of the complex medium through grayscale distribution and texture feature calculation in each direction.

[0089] Among them, the calculation formula of the overall density of coal rock in step S1011 is:

[0090]

[0091] In the formula, Indicates the overall density of coal rock (in g / cm³), represents the total mass of coal rock (in g), Indicates i The volume of the coal rock (in cm³), Indicates the total number of coal blocks;

[0092] The pore structure volume calculation formula is expressed as:

[0093]

[0094] In the formula, represents the total volume of the pore structure (in cm³), Indicates The volume of solids in the coal rock (in cm³);

[0095] Step S1012 Accurate density calculation formula:

[0096]

[0097] In the formula, Indicates the exact density of coal rock (in g / cm³), represents the total mass of coal rock (in g), Indicates i The volume of solids in the coal rock (in cm³);

[0098] Horizontal and vertical slice processing represents:

[0099] Grayscale distribution means the grayscale distribution of coal rock images in horizontal and vertical directions obtained by image processing technology:

[0100]

[0101]

[0102] In the formula, Indicates horizontal direction The gray value of the position, Indicates vertical direction The gray value of the position, Indicates that the image is The gray value of the position, Represents the width of the coal rock image, Indicates the height of the coal rock image;

[0103] Texture feature representation is the extraction of texture features of coal rock images through methods such as gray level co-occurrence matrix:

[0104]

[0105] In the formula, Represents the gray value in the gray-level co-occurrence matrix and The symbiosis frequency, represents the Kronecker delta function, when = 1 if yes, 0 otherwise. Indicates the offset;

[0106] The microscopic description calculation formula of step S1013 is expressed as:

[0107]

[0108] In the formula, represents the fractal dimension of coal rock, Indicated in scale The number of coverages under Indicates the size of the scale;

[0109] Microscopic description of complex media: anisotropic distribution is expressed through anisotropic parameters Describe the anisotropic characteristics of coal rocks:

[0110]

[0111] In the formula, represents the anisotropy parameter, represents the horizontal variance, Represents the variance in the vertical direction; Through the above formula and steps, the microstructure characteristics of coal rock can be analyzed more accurately, so as to calculate the deformation characteristic permeability of water and gas in coal rock;

[0112] In the above embodiment, step S1011 obtains the overall density of the coal rock, calculates its volume, and obtains image features to obtain pore structure features. A comprehensive understanding of the coal rock sample, including its macroscopic density and microstructure. This embodiment can accurately obtain the mass and volume of the coal rock through calibration and measurement, and then calculate the actual density. In addition, the volume of the pore structure is extracted through image processing technology to further understand the pore distribution of the coal rock. Step S1012 uses the density calculation formula to calculate the actual accurate density of the coal rock based on the volume and mass. According to this accurate density, the coal rock image is sliced ​​in the horizontal and vertical directions to extract the grayscale distribution and texture features in each direction. Not only does it improve the accuracy of density measurement, but it also provides important parameter basis for subsequent image analysis. This embodiment can better describe the microstructure and complex medium characteristics of the coal rock by extracting grayscale distribution and texture features. Step S1013 describes the microscopic and complex medium characteristics of the coal rock image by analyzing the grayscale distribution and texture features in each direction. By using methods such as gray level co-occurrence matrix, the energy, entropy, contrast and other parameters of the coal-rock image are calculated, thereby realizing the recognition and classification of the coal-rock interface. The parameters in this embodiment can effectively distinguish the texture differences between coal and rock, and improve the accuracy and robustness of recognition.

[0113] Embodiment 4:

[0114] like Figure 4 As shown, based on Example 2, the process of distributing data of anisotropic three-dimensional space in step S102 provided in the embodiment of the present invention includes the following steps:

[0115] Step S1021: preprocessing the coal-rock image, smoothing the image, segmenting the image, setting a grayscale threshold, and separating the pore part from the matrix part in the coal-rock image;

[0116] Step S1022: Calculate the fractal dimension of the coal rock, divide the image into grids of different sizes, count the network grids covering the pore area, calculate the relationship between the grid size, and obtain the fractal dimension; perform three-dimensional reconstruction of the coal rock, calculate it, and obtain the porosity;

[0117] Among them, grid division and statistics divide the preprocessed coal rock image into grids of different sizes, and the size of the grid gradually decreases from large to small to form a multi-scale grid system; for each grid size, the number of grids covering the pore area is counted. The pore area refers to the part of the image with a grayscale value lower than the set threshold, which represents the pore structure in the coal rock; fractal dimension calculation: according to the statistical results, the relationship between the grid size and the number of grids covering the pore area is analyzed. The relationship is described by a power law function, that is, the number of grids is proportional to the negative power of the grid size; by fitting the power law function , The grid size is The number of grids covering the pore area is is the fractal dimension, converting the power law relationship into a linear relationship: , C is a constant), the linear relationship is fitted using the least squares method to obtain the fractal dimension; the fractal dimension reflects the complexity and self-similarity of the pore structure, and the larger the value, the more complex the pore structure; three-dimensional reconstruction and porosity calculation: based on the two-dimensional image data of coal rock, a three-dimensional model is generated through interpolation and reconstruction algorithms (data interpolation interpolates the two-dimensional image data in space, fills in the missing information, and forms continuous three-dimensional data; a three-dimensional model is generated using a reconstruction algorithm (such as voxelization or triangulation)) In the three-dimensional model, the ratio of pore volume to total volume is calculated to obtain porosity. Porosity is an important parameter for measuring the proportion of pore space in coal rock, reflecting the gas storage and seepage capacity of coal rock;

[0118] Step S1023: Analyze the fractal dimension and porosity data of the coal rock to obtain the isotropic distribution characteristics and their distribution in three-dimensional space.

[0119] In the above embodiment, step S1021 separates the pore part from the matrix part in the coal rock image by preprocessing the coal rock image, including smoothing and segmentation, setting a grayscale threshold. Through image preprocessing, noise can be removed and important features in the image can be highlighted, making the pore and matrix parts clearer, which is convenient for subsequent analysis and calculation. Step S1022 calculates the fractal dimension of the coal rock, by dividing the image into grids of different sizes, counting the number of grids covering the pore area, and calculating the relationship between the grid size to obtain the fractal dimension. Fractal dimension is an important indicator to describe the complexity of the pore structure of coal rock, which can reflect the self-similarity and complexity of the internal structure of coal rock. In addition, by reconstructing the coal rock in three dimensions, the spatial distribution of pores can be more intuitively displayed, and then the porosity can be calculated. Step S1023 analyzes the fractal dimension and porosity data of the coal rock to obtain the anisotropic distribution characteristics and their distribution in three-dimensional space. This embodiment can reveal the complexity and anisotropic characteristics of the internal structure of coal rock through analysis.

[0120] Embodiment 5:

[0121] like Figure 5 As shown, based on Example 2, the process of deformation characteristic permeability in step S103 provided in the embodiment of the present invention includes the following steps:

[0122] Step S1031: Automatically identify the coal rock according to its reflectivity and morphological parameters; combine the coal rock microscopic grouping and the reflectivity and morphological parameters, draw a full component reflectivity map through the relationship between gray value and reflectivity, and obtain the coal rock component content according to the inflection point cutting division;

[0123] Step S1032: grouping the coal and rock according to the reflectivity and morphological parameters, and classifying the image information into different categories;

[0124] Step S1033: According to the results of coal rock grouping, according to the pore structure of the coal rock and the response under different stress conditions, the deformation characteristic permeability of water and gas in the coal rock is calculated.

[0125] Among them, the deformation characteristic permeability calculation includes:

[0126] Analysis of pore structure and stress response: Based on the grouping results, analyze the pore structure of each group of coal and rock (such as porosity, pore size distribution, connectivity, etc.); combine different stress conditions (such as confining pressure, temperature, etc.) to study the deformation characteristics of coal and rock under stress (such as compression, expansion, crack expansion, etc.);

[0127] Permeability is a parameter that describes the ability of fluids (water and gas) to flow in coal and rock, and is described by Darcy's law. Based on the pore structure and stress response characteristics, a relationship model between permeability and porosity and stress conditions is established. Through experimental data or numerical simulation, the permeability of water under different stress conditions is calculated. The gas permeability calculation formula is:

[0128] ;

[0129] In the formula, is the gas permeability, is the permeability at infinite pressure, is the slip coefficient, For pressure;

[0130] Combined with the calculation results of water and gas permeability, the deformation characteristic permeability of coal rock under different stress conditions is analyzed; through experiments or numerical simulations, the permeability data of water and gas under different stress conditions are obtained; stress-permeability curves are drawn to analyze the law of permeability change with stress; comparative analysis of water and gas permeability shows that the water permeability in low stress areas is higher, the gas permeability is higher (due to the slippage effect), and the permeability difference between water and gas is large; the permeability of water and gas in high stress areas is significantly reduced, but the gas permeability decreases more (the slippage effect is weakened), and the permeability difference between water and gas is reduced; the deformation characteristic permeability is defined as the comprehensive change characteristic of the permeability of coal rock under stress; by fitting experimental data, a mathematical model of deformation characteristic permeability and stress conditions is established, for example:

[0131] ;

[0132] in, is the deformation characteristic permeability, is the initial permeability, is the stress sensitivity coefficient, For stress.

[0133] In the above embodiment, step S1031 uses the reflectivity and morphological parameters of coal rock for automatic identification, draws a full component reflectivity diagram through the relationship between gray value and reflectivity, and obtains the coal rock component content based on the inflection point cutting division. The subjectivity of human operation is reduced, and the accuracy and efficiency of identification are improved. Step S1032 The automated identification technology reduces the differences caused by traditional manual measurement, improves the test speed and efficiency, and enables the coal rock measurement results to be applied to coal classification, coal processing and utilization and other fields. By combining image processing technology with reflectivity and morphological parameters, it is possible to achieve rapid and accurate determination of the microscopic components of coal rock, reducing the labor intensity of the operator. Step S1033 Based on the results of coal rock grouping, combined with the pore structure of coal rock and the response under different stress conditions, the deformation characteristic permeability of water and gas in coal rock is calculated.

[0134] Embodiment 6:

[0135] like Figure 6 As shown, based on Example 1, the process of deriving the characteristic permeability of simulated coal rock deformation in step S200 provided in the embodiment of the present invention includes the following steps:

[0136] Step S201: setting permeability coupling model parameters according to historical experimental data; setting the initial permeability of coal rock according to historical experimental data; setting the coefficient of pore surface area increase according to the pore structure of coal rock and historical experimental data; setting the volume strain of coal rock according to the deformation data of coal rock;

[0137] Step S202: Output the analysis results to the permeability coupling model to simulate the seepage evolution; calculate the relationship between permeability and factors such as effective stress and gas pressure, establish the permeability function of coal rock under different stress conditions, and obtain the seepage evolution results;

[0138] Step S203: According to the simulated seepage evolution results, the anisotropic evolution characteristics of coal rock permeability changing with time, stress, gas pressure and other factors are analyzed; the simulation results are compared with historical experimental data, and a comparison threshold is preset. If it is greater than the comparison threshold, the model parameters are optimized.

[0139] In the above embodiment, the permeability coupling model parameters are set in step S201 through historical experimental data, including the initial permeability of coal rock, the coefficient of the increase in pore surface area, and the volume strain of coal rock. The setting of the initial permeability of coal rock, the coefficient of the increase in pore surface area, and the volume strain of coal rock helps to establish an initial model framework for subsequent simulation and analysis. The coefficient of the increase in pore surface area is set according to the pore structure of coal rock and historical experimental data, which can more accurately reflect the deformation characteristics of coal rock under different stress conditions. In step S202, the analysis results are output to the permeability coupling model to simulate the seepage evolution, and the relationship between permeability and factors such as effective stress and gas pressure is calculated to establish a permeability function formula for each single under different stress conditions. This embodiment can reveal the law of change of coal rock permeability with time, stress, gas pressure and other factors by simulating the seepage evolution process, thereby providing theoretical support for understanding the behavior of coal rock in actual engineering. In step S203, according to the simulated seepage evolution results, the anisotropic evolution characteristics of the coal rock permeability with time, stress, gas pressure and other factors are analyzed, and the simulation results are compared with the historical experimental data. If the difference between the simulation results and the experimental data exceeds a preset threshold, the model parameters are optimized. This embodiment improves the accuracy and reliability of the model and ensures that the model can better reflect the physical behavior of the actual coal rock.

[0140] Embodiment 7:

[0141] like Figure 7 As shown, based on Example 6, the process of setting the volume strain of coal rock in step S201 provided in the embodiment of the present invention includes the following steps:

[0142] Step S2011: According to the historical experimental data, the permeability coupling model parameters are selected and set, and the parameters include the porosity, fractal dimension and fracture inclination of the coal rock; different porosities and fracture structure parameters in the historical experimental data are analyzed to calculate the initial permeability;

[0143] Step S2012: According to the pore structure of the coal rock and historical experimental data, the change of the initial permeability and the change of the internal pores of the coal rock are analyzed to obtain the increase of the pore surface area; and the coefficient of the increase of the pore surface area is set;

[0144] Step S2013: Analyze the porosity according to the deformation data of the coal rock to obtain the law of porosity change with stress; analyze the change law of stress and porosity of the coal rock to obtain the coal rock deformation data, and set the volume strain of the coal rock.

[0145] Among them, step S2011 selects and sets the permeability coupling model parameters, and selects key parameters related to coal rock permeability according to historical experimental data, including porosity , fractal dimension D f and crack inclination Etc. Parameters are important indicators for describing the internal structural characteristics of coal and rock;

[0146] Based on the selected parameters, the initial permeability is calculated using the permeability coupling model , the fractal permeability model can be expressed as:

[0147] ;

[0148] in, , , is the model constant, is the porosity, D f is the fractal dimension.

[0149] By analyzing different porosity and fracture structure parameters in historical experimental data, the accuracy of the model is verified, and the parameters are adjusted to improve the reliability of the calculation results;

[0150] Step S2012 analyzes the initial permeability change and the increase in pore surface area. According to the pore structure of coal rock, the initial permeability is analyzed. The relationship with the change of porosity; the increase of pore surface area is calculated by the change of porosity. , the relationship between pore surface area and porosity can be expressed by the following formula:

[0151] ;

[0152] in, is the initial pore surface area, is the initial porosity, is the empirical coefficient;

[0153] According to experimental data, the coefficient of the increase in pore surface area is set , to reflect the effect of pore structure on permeability changes;

[0154] Step S2013 analyzes the law of porosity change with stress, and analyzes the porosity according to the deformation data of coal rock. With stress The porosity will decrease with the increase of stress. This relationship can be obtained by fitting the experimental data. Using the experimental data, a mathematical model of porosity change with stress is established, using the exponential decay model:

[0155] ;

[0156] in, is the initial porosity, is the attenuation coefficient, for stress;

[0157] Combining the changing laws of stress and porosity, the deformation data of coal rock is analyzed. The deformation data can be described by strain, and the relationship between strain and stress is expressed by Hooke's law. According to the deformation data, the volume strain of coal rock is set. , the volume strain is calculated by the following formula:

[0158] ;

[0159] in, Initial volume.

[0160] In the above embodiment, step S2011 calculates the initial permeability by selecting and setting the permeability coupling model parameters, such as porosity, fractal dimension, and fracture inclination. An initial permeability model is established using historical experimental data, and the model can reflect the permeability characteristics of coal rock under specific conditions. In addition, by analyzing different porosity and fracture structure parameters, the influence of these parameters on permeability can be quantitatively understood. Step S2012 obtains the increase in pore surface area by analyzing the internal pore changes of coal rock, and sets the corresponding coefficient. The permeability model is refined to consider the influence of changes in pore structure on permeability. The increase in pore surface area may lead to changes in permeability, and this change can be quantified by setting coefficients. Step S2013 obtains the law of porosity change with stress by analyzing the deformation data of coal rock, and sets the volume strain of coal rock in combination with the change law of stress and porosity. The deformation characteristics of coal rock under stress state and its influence on permeability are revealed. The deformation characteristics of coal rock under stress will affect the changes in its porosity and permeability. Through analysis in this embodiment, the behavior of coal rock in actual engineering applications can be better understood, thereby optimizing the development strategy of coalbed methane.

[0161] Embodiment 8:

[0162] like Figure 8 As shown, based on Example 6, the process of obtaining the seepage evolution result in step S202 provided by the present invention includes the following steps:

[0163] Step S2021: According to historical experimental data, set initial conditions and parameters: initial permeability , the coefficient of increase in pore surface area , coal rock volume strain , the influence coefficient of gas pressure on permeability , initial gas pressure , initial effective stress ;

[0164] Step S2022: establishing a relationship between permeability and effective stress, and establishing a relationship between permeability and gas pressure;

[0165]

[0166]

[0167] in: represents the permeability after the effective stress changes, Indicates the current effective stress; represents the permeability after the gas pressure changes, Indicates the current gas pressure;

[0168] Step S2023: Calculate the current permeability by comprehensively considering the relationship between permeability and multiple factors , according to the current permeability, the seepage rate and the seepage path are calculated; the stress conditions and the gas pressure are updated, and the permeability and the seepage rate are calculated repeatedly until a stable state or a preset time is reached; .

[0169] In the above embodiment, step S2021 sets the initial conditions and parameters, and through historical experimental data, ensures that the initial conditions and parameters of the model have actual physical meaning, providing reliable data support for the calculation. Step S2022 establishes the relationship between permeability, effective stress, and gas pressure, mathematizes physical phenomena, and provides a theoretical basis for subsequent calculations; permeability is associated with changes in effective stress and gas pressure to provide a basis for dynamic changes in subsequent calculations. Step S2023 comprehensively considers the relationship between permeability and multiple factors, calculates the current permeability, and calculates the seepage rate and seepage path based on the current permeability to achieve dynamic simulation; by continuously updating stress conditions and gas pressure, repeatedly calculating permeability and seepage rate until a stable state or preset time is reached, ensures the accuracy and reliability of the simulation results; through iterative calculations, analyzes the stability of the system, and provides a reference for practical engineering applications.

[0170] In summary, each step of this embodiment is to ensure the accuracy and reliability of the model, and ultimately achieve accurate simulation and analysis of the seepage evolution process by setting initial conditions and parameters, establishing a mathematical model, dynamic calculation and iterative updating.

[0171] Embodiment 9:

[0172] like Fig. 9 As shown, based on Example 8, the process of calculating the seepage rate and the seepage path in step S2023 provided in the embodiment of the present invention includes the following steps:

[0173] Step S20231: Acquire pore structure data through micro-CT scanning, construct a pore network model, and calculate micro-permeability; calculate macro-permeability by combining the geological model and measured data; couple the micro-permeability and macro-permeability to calculate the comprehensive permeability;

[0174] Step S20232: Initialize the grid division according to the complexity of the geological structure, calculate the error estimation value of each unit, determine whether the grid needs to be refined, calculate the pressure field, and set the boundary conditions according to the boundary conditions of the geological structure; calculate the seepage rate of each unit in combination with the multi-scale permeability calculation results, and correct the seepage rate according to the error estimation results;

[0175] Step S20233: Collect historical experimental data and numerical simulation results, construct a training data set, use a convolutional neural network to train a path prediction model, use the trained path prediction model to predict the flow path of the fluid, and adjust the calculation parameters according to the prediction results; calculate the convergence error of each iteration to determine whether the convergence conditions are met.

[0176] Wherein, step S20231: coupling of microscopic permeability and macroscopic permeability:

[0177] Micro permeability calculation, micro permeability The calculation is based on the Darcy's law of pore geometry and fluid flow. The specific formula can be expressed as:

[0178] ;

[0179] Where: is the porosity; is the pore radius; is the tortuosity (characterizing the complexity of the path of fluid flow in the pores);

[0180] Macro permeability The calculation formula is expressed as:

[0181] ;

[0182] Where: For flow; is the fluid viscosity; is the flow path length; is the cross-sectional area; is the pressure difference;

[0183] Comprehensive penetration rate calculate:

[0184] ;

[0185] In the formula, is the weight coefficient, which is usually determined based on experimental data or experience.

[0186] Step S20232: Correction of the seepage rate:

[0187] Pressure field calculation, according to Darcy's law, seepage rate Calculated by the following formula:

[0188] ;

[0189] In the formula, is the comprehensive penetration rate; is the fluid viscosity; is the pressure difference;

[0190] Error estimation and mesh refinement. In numerical simulation, the error estimate Calculated by the following formula:

[0191] ;

[0192] In the formula, is the calculated value, is a reference value (such as experimental data or high-precision calculation results); if the error exceeds the preset threshold, the grid needs to be refined;

[0193] Seepage rate correction: According to the error estimation results, the seepage rate Corrected by the following formula:

[0194] ;

[0195] In the formula, is the correction factor, which is determined based on experimental data or experience.

[0196] In the above embodiment, step S20231 uses micro-CT scanning to obtain pore structure data. Through high-resolution micro-CT scanning, the pore structure data inside the rock can be accurately obtained, providing a basis for the construction of the pore network model. The pore network model is constructed to calculate the microscopic permeability. The pore network model can simulate the microscopic pore structure inside the rock, calculate the microscopic permeability, and reflect the permeability of the rock at the microscopic scale; combine the geological model and the measured data to calculate the macroscopic permeability; by combining the geological model and the measured data, the permeability of the rock at the macroscopic scale can be calculated, reflecting the permeability of the entire geological body at the macroscopic scale; the microscopic permeability and the macroscopic permeability are coupled to calculate the comprehensive permeability. By coupling the microscopic and macroscopic permeabilities, a comprehensive permeability can be obtained, reflecting the comprehensive effect of the permeability of the rock at different scales. Step S20232 can decompose complex geological structures into multiple units through reasonable grid division, which is convenient for numerical calculation; calculate the error estimate of each unit to determine whether the grid needs to be refined; through error estimation, the rationality of grid division can be determined, and the grid can be refined when necessary to improve the calculation accuracy; calculate the pressure field and set boundary conditions; by calculating the pressure field, the pressure distribution of the fluid in the geological structure can be simulated, and the accuracy of the calculation can be ensured by combining the boundary conditions; combine the multi-scale permeability calculation results to calculate the seepage rate of each unit; by combining the multi-scale permeability calculation results, the seepage rate of each unit can be calculated to reflect the flow characteristics of the fluid at different scales; according to the error estimation results, the seepage rate is corrected; through the error estimation results, the seepage rate is corrected to improve the accuracy of the calculation results. Step S20233 collects historical experimental data and numerical simulation results to construct a training data set; by collecting historical data and simulation results, a training data set is constructed to provide data support for subsequent model training; a convolutional neural network is used to train a path prediction model; by training a path prediction model through a convolutional neural network, the accuracy of predicting the flow path of the fluid can be improved; the flow path of the fluid is predicted using the trained path prediction model, and the calculation parameters are adjusted according to the prediction results; by predicting the flow path of the fluid, the calculation parameters can be optimized to improve the calculation efficiency and accuracy; the convergence error of each iteration is calculated to determine whether the convergence condition is met; by calculating the convergence error, it can be determined whether the calculation meets the convergence condition to ensure the reliability of the calculation results. These steps work together to ensure the accuracy and reliability of the calculation of the seepage rate and the seepage path.

[0197] Embodiment 10:

[0198] like Fig.10 As shown, based on Example 6, the process of anisotropic evolution characteristics in step S203 provided in this embodiment of the present invention includes the following steps:

[0199] Step S2031: extract the characteristics of the simulated seepage evolution results, analyze the changes of coal rock seepage at different time points, different stress conditions and different gas pressures; draw the change curve of permeability with time, stress and gas pressure, and identify the peak value, valley value and time point of permeability change;

[0200] Step S2032: preprocess the historical experimental data and extract features; draw the variation curve of the permeability of the historical experimental data with time, stress and gas pressure; compare the variation curve of the historical experimental data with the simulation variation curve; calculate the correlation coefficient, mean square error, mean absolute error and other indicators;

[0201] Step S2033: setting a comparison threshold. If the comparison result exceeds the threshold, identifying and analyzing the abnormal points exceeding the threshold; and adjusting the permeability coupling model according to the analysis result.

[0202] In the above embodiment, step S2031 analyzes the changes of coal rock seepage at different time points, different stress conditions and different gas pressures by simulating the feature extraction of the seepage evolution results. Plot the curve of permeability change with time, stress and gas pressure, and identify the peak value, valley value and time point of permeability change. Step S2032 involves the preprocessing and feature extraction of historical experimental data, and then plots the change curve of permeability of historical experimental data with time, stress and gas pressure. Compare these change curves with the simulated change curves, and calculate the correlation coefficient, mean square error, mean absolute error and other indicators. Through the indicators, the accuracy of the simulation model can be evaluated to verify the effectiveness of the model. Step S2033 sets a comparison threshold. If the comparison result exceeds the threshold, the abnormal points exceeding the threshold are identified and analyzed. The permeability coupling model is adjusted according to the analysis results. This embodiment finds potential problems in the model and improves the accuracy and applicability of the model by adjusting the model parameters.

[0203] Embodiment 11:

[0204] like Fig.11 As shown, based on Example 1, the process of obtaining the final permeability coupling model in step S300 provided in the embodiment of the present invention includes the following steps:

[0205] Step S301: Compare the water and gas coal rock deformation characteristic permeability with the simulated coal rock deformation characteristic permeability, calculate the correlation coefficient and mean square error and other indicators; set the accuracy threshold, and perform analysis if it is greater than the accuracy threshold;

[0206] Step S302: Analyze the permeability under different stress states and the difference in permeability at micro and macro scales based on the comparison results; preset a comparison permeability threshold, and if it is greater than the comparison permeability threshold, adjust the permeability coupling model parameters and perform simulation;

[0207] Step S303: setting a threshold value for the model parameters after comparison and adjustment, comparing the adjusted model permeability coupling model result with the initial permeability coupling model parameter result, if it is greater than the threshold value, adjusting the initial permeability, fracture structure parameters, Young's modulus, Poisson's ratio, etc.; iterating in sequence; obtaining the final permeability coupling model.

[0208] In the above embodiment, in step S301, the accuracy of the model can be evaluated by comparing the characteristic permeability of coal rock deformation with the characteristic permeability of simulated coal rock deformation, calculating the correlation coefficient and the mean square error and other indicators. If the accuracy is higher than the set threshold, the reason is further analyzed. The accuracy of the model is verified and its reliability in practical applications is ensured. In step S302, the permeability differences under different stress states and the permeability differences at micro and macro scales are analyzed, which helps to understand the permeability characteristics of coal rock under different conditions. By presetting the comparison permeability threshold, if a large difference is found, the permeability coupling model parameters are adjusted for simulation. In step S303, the threshold of the adjusted model parameters is set, and the adjusted model results are compared with the first permeability coupling model results. If the difference is large, the initial permeability, fracture structure parameters, Young's modulus, Poisson's ratio and other parameters are continued to be adjusted. The iterative process gradually optimizes the model, and finally obtains a more accurate permeability coupling model. The prediction accuracy of the model is improved, which provides an important reference for engineering practice.

[0209] Embodiment 12:

[0210] like Fig.12 As shown, based on Examples 1 to 11, the anisotropic coal rock adsorption-permeability coupling model system provided in the embodiments of the present invention comprises:

[0211] Feature analysis module 1 is responsible for collecting raw data of coal and rock, pre-processing the raw data of coal and rock, identifying the anisotropic characteristics of coal and rock; analyzing the anisotropic characteristics, calculating the analysis results, and obtaining the water and gas coal and rock deformation characteristic permeability;

[0212] Among them, anisotropic characteristics include anisotropy of permeability, anisotropy of mechanical properties and anisotropy of pore structure; coal rock raw data include physical properties, structural characteristics and stress state of coal rock;

[0213] Model building module 2 is responsible for building a permeability coupling model, setting the parameters of the permeability coupling model according to historical experimental data; outputting the analysis results to the permeability coupling model, simulating the seepage evolution; and deriving the characteristic permeability of the simulated coal rock deformation;

[0214] Among them, the key parameters include initial permeability, fracture structure parameters, Young's modulus, Poisson's ratio, etc.;

[0215] Model updating module 3 is responsible for comparing the characteristic permeability of coal rock deformation with water and gas with the simulated characteristic permeability of coal rock deformation to verify the accuracy of the permeability coupling model; preset a comparison permeability threshold, if it is greater than the comparison permeability threshold, adjust the permeability coupling model data and re-simulate the seepage evolution; iterate in sequence to obtain the final permeability coupling model.

[0216] In the above embodiment, the feature analysis module 1 provides basic data for analysis and modeling by collecting raw data such as physical properties, structural characteristics and stress states of coal rocks; preprocesses the collected raw data to eliminate noise and outliers to ensure the accuracy and reliability of the data; analyzes the anisotropic characteristics of coal rocks, including the anisotropy of permeability, the anisotropy of mechanical properties and the anisotropy of pore structure, to deeply understand the characteristics of coal rocks in different directions; calculates the permeability of coal rocks under different stress states based on the analysis results of the anisotropic characteristics, reflecting the permeability of coal rocks in different directions. Through feature analysis, the permeability and mechanical properties of coal rocks in different directions can be deeply understood, providing a scientific basis for model construction; accurate feature analysis results provide high-quality input data for the construction of the permeability coupling model, which helps to improve the accuracy and reliability of the model. Model construction module 2 sets the parameters of the permeability coupling model according to historical experimental data, and constructs a model that can simulate the characteristic permeability of coal rock deformation; inputs the output results of the characteristic analysis module into the permeability coupling model, simulates the seepage evolution, and obtains the simulated coal rock deformation characteristic permeability; by setting key parameters such as initial permeability, fracture structure parameters, Young's modulus, Poisson's ratio, etc., the rationality and accuracy of the model are ensured. Through model construction, the deformation characteristics and permeability changes of coal rock under different stress states can be simulated, providing theoretical support for practical engineering applications; by referring to historical experimental data, the model parameters can be optimized to improve the prediction ability and practicality of the model. Model update module 3 compares the characteristic permeability of coal rock deformation with the simulated characteristic permeability of coal rock deformation to verify the accuracy of the permeability coupling model; according to the comparison results, a comparison permeability threshold is preset. If it is greater than the threshold, the permeability coupling model data is adjusted, and the seepage evolution is simulated again until the preset accuracy is reached; through multiple iterations, the model parameters are continuously optimized to ensure the accuracy and reliability of the final permeability coupling model. Through the model update module, the model parameters can be continuously optimized, the accuracy and reliability of the permeability coupling model can be improved, and the effectiveness of the model in practical applications can be ensured; through iterative optimization, the prediction results of the final permeability coupling model under different stress states can be ensured to be highly consistent with the actual measurement results, thereby improving the reliability and practicality of the model.

[0217] In summary, the various modules of this embodiment work together to ensure the accuracy and reliability of the anisotropic coal rock adsorption-permeability coupling model. Through the organic combination of the three modules of feature analysis, model construction and model update, it is possible to deeply understand the anisotropic characteristics of coal rock, build a high-precision permeability coupling model, and provide reliable theoretical support in practical engineering applications.

[0218] Fig.13 A block diagram of an exemplary electronic device suitable for implementing embodiments of the present invention is shown.

[0219] The electronic device may include a central processing unit / microprocessor / main control chip, etc. 4; a storage medium 5, coupled to the central processing unit / microprocessor / main control chip, etc. 4, and storing computer executable instructions therein, for performing the steps of each method of an embodiment of the present invention when executed by the processor.

[0220] The central processing unit / microprocessor / main control chip 4 may include but is not limited to, for example, one or more processors or microprocessors.

[0221] The storage medium 5 may include, but is not limited to, for example, random access memory (RAM), read-only memory (ROM), flash memory, EPROM memory, EEPROM memory, registers, computer storage media (such as hard disk, floppy disk, solid state drive, removable disk, CD-ROM, DVD-ROM, Blu-ray disc, etc.).

[0222] In addition, the electronic device may also include (but not limited to) a data bus 6, an input / output bus / external bus / device bus 7, a display 8, and input / output devices 9 (eg, keyboard, mouse, speaker, etc.).

[0223] The central processing unit / microprocessor / main control chip etc. 4 can communicate with external devices ( 8 , 9 etc.) through the I / O bus 7 via a wired or wireless network (not shown).

[0224] The storage medium 5 may also store at least one computer executable instruction for executing the various functions and / or method steps in the embodiments described in the present technology when executed by the central processing unit / microprocessor / main control chip 4.

[0225] In one embodiment, the at least one computer executable instruction may also be compiled into or constitute a software product, wherein one or more computer executable instructions are executed by a processor to perform the various functions and / or method steps in the embodiments described in the present technology.

[0226] Fig.14 A schematic diagram of a computer-readable storage medium according to an embodiment of the present invention is shown.

[0227] like Fig.14 As shown, instructions are stored on a non-transitory computer-readable storage medium 11, and the instructions are, for example, computer-readable instructions 10. When the computer-readable instructions 10 are executed by the processor, the various methods described above can be executed. Non-transitory computer-readable storage media include, but are not limited to, for example, volatile memory and / or non-volatile memory. Volatile memory may include, for example, random access memory (RAM) and / or cache memory (cache), etc. Non-transitory non-volatile memory may include, for example, read-only memory (ROM), hard disk, flash memory, etc. For example, the non-transitory computer-readable storage medium 11 can be connected to a computing device such as a computer, and then, when the computing device runs the computer-readable instructions 10 stored on the computer-readable storage medium 11, the various methods described above can be performed.

[0228] In the several embodiments provided by the present invention, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0229] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0230] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0231] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for executing all or part of the steps of the various embodiments of the present invention through a computer device (which can be a personal computer, server, or network device, etc.). The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (full name in English: Read-Only Memory, English abbreviation: ROM), random access memory (full name in English: Random Access Memory, English abbreviation: RAM), disk or optical disk, etc. Various media that can store program codes.

[0232] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An anisotropic coal rock adsorption-permeability coupling model and permeability evolution method, characterized in that: The following steps are involved: Collect raw coal rock data, pre-process the raw coal rock data, identify the anisotropic characteristics of coal rock; analyze the anisotropic characteristics, calculate the analysis results, and obtain the water and gas coal rock deformation characteristic permeability; The process of deforming characteristic permeability includes the following steps: Automatically identify coal and rock based on their reflectivity and morphological parameters; combine coal and rock microscopic grouping with reflectivity and morphological parameters, draw a full component reflectivity map based on the relationship between grayscale value and reflectivity, and obtain the coal and rock component content based on inflection point cutting and division; The coal rocks are grouped according to reflectivity and morphological parameters, and the image information is classified into different categories; Based on the results of coal-rock grouping, the deformation characteristic permeability of water and gas in coal-rock is calculated according to the pore structure of coal-rock and the response under different stress conditions; The deformation characteristic permeability calculation process includes: analyzing the pore structure of each group of coal rocks according to the grouping results; combining different stress conditions to study the deformation characteristics of coal rocks under stress; the pore structure includes porosity, pore size distribution, and connectivity; the stress conditions include confining pressure and temperature, and the deformation characteristics include compression, expansion, and crack expansion; According to the pore structure and stress response characteristics, the relationship model between permeability, porosity and stress conditions is established; the permeability of water under different stress conditions is calculated; the specific gas permeability calculation formula is: ； In the formula, is the gas permeability, is the permeability at infinite pressure, is the slip coefficient, For pressure; Analyze the deformation characteristic permeability of coal rock under different stress conditions; define deformation characteristic permeability as the comprehensive change characteristics of coal rock permeability under stress; establish a mathematical model of deformation characteristic permeability and stress conditions: ； in, is the deformation characteristic permeability, is the initial permeability, is the stress sensitivity coefficient, for stress; Construct a permeability coupling model and set the parameters of the permeability coupling model according to historical experimental data; output the analysis results to the permeability coupling model to simulate the seepage evolution; obtain the characteristic permeability of simulated coal rock deformation; The process of obtaining the seepage evolution results includes the following steps: According to historical experimental data, set initial conditions and parameters: initial permeability , the coefficient of increase in pore surface area , coal rock volume strain , the influence coefficient of gas pressure on permeability , initial gas pressure , initial effective stress ; Establish the relationship between permeability and effective stress, and establish the relationship between permeability and gas pressure; ； ； in: represents the permeability after the effective stress changes, Indicates the current effective stress; represents the permeability after the gas pressure changes, Indicates the current gas pressure; Considering the relationship between permeability and multiple factors, calculate the current permeability , according to the current permeability, the seepage rate and the seepage path are calculated; the stress conditions and the gas pressure are updated, and the permeability and the seepage rate are calculated repeatedly until a stable state or a preset time is reached; ； The characteristic permeability of coal rock deformation with water and gas is compared with the characteristic permeability of simulated coal rock deformation to verify the accuracy of the permeability coupling model; a comparison permeability threshold is preset. If it is greater than the comparison permeability threshold, the permeability coupling model data is adjusted and the seepage evolution is re-simulated; it is iterated sequentially to obtain the final permeability coupling model.

2. The anisotropic coal rock adsorption-permeability coupling model and permeability evolution method according to claim 1, characterized in that: The process of obtaining the characteristic permeability of coal rock deformation for water and gas includes the following steps: Collect raw data of coal and rock to obtain coal and rock image data and microstructure image data; extract the overall characteristics, horizontal and vertical characteristics of coal and rock images; analyze the overall characteristics, horizontal and vertical characteristics of coal and rock images; Based on the analysis results, the visualization of the micro- and meso-structure of complex porous media and the description of multi-scale and anisotropic properties are obtained; Calculate the overall fractal dimension and porosity of coal rock and the three-dimensional spatial distribution data of anisotropic distribution according to the characteristic image; The coal rocks are grouped and automatically identified according to their reflectivity and morphological parameters; the deformation characteristic permeability of water and gas in the coal rocks is calculated based on the coal rock groupings.

3. The anisotropic coal rock adsorption-permeability coupling model and permeability evolution method according to claim 2, characterized in that: The process of analyzing the overall characteristics, horizontal and vertical characteristics of coal rock images includes the following steps: Obtain the overall density of the coal rock, obtain the density of the entire coal rock through calibration, measure the accurate mass of the entire coal rock, and calculate the overall volume of the coal rock; obtain the pore structure characteristics by acquiring the image features, and extract the volume of the pore structure according to the image; The actual accurate density is calculated according to the volume and mass through the density calculation formula, and the coal rock image is sliced ​​horizontally and in the processing direction according to the accurate density to extract the grayscale distribution and texture characteristics in each direction; By calculating the grayscale distribution and texture features in each direction, the microscopic properties of coal and rock images and the microscopic properties of complex media are analyzed.

4. The anisotropic coal rock adsorption-permeability coupling model and permeability evolution method according to claim 2, characterized in that: The process of distributing data in three-dimensional space with anisotropic distribution includes the following steps: Preprocess the coal-rock image, smooth the image, segment the image, set the grayscale threshold, and separate the pore part from the matrix part in the coal-rock image; Calculate the fractal dimension of coal rock, divide the image into grids of different sizes, count the network grids covering the pore area, calculate the relationship between the grid size, and obtain the fractal dimension; Reconstruct the coal rock in three dimensions, calculate it and get the porosity; The fractal dimension and porosity data of coal rock are analyzed to obtain the isotropic distribution characteristics and their distribution in three-dimensional space.

5. The anisotropic coal rock adsorption-permeability coupling model and permeability evolution method according to claim 1, characterized in that: The process of deriving the characteristic permeability of simulated coal rock deformation includes the following steps: The permeability coupling model parameters are set according to the historical experimental data; the initial permeability of the coal rock is set according to the historical experimental data; and the coefficient of the increase in the pore surface area is set according to the pore structure of the coal rock and the historical experimental data; the volume strain of the coal rock is set according to the deformation data of the coal rock; The analysis results are output to the permeability coupling model to simulate the seepage evolution; the relationship between permeability and effective stress and gas pressure factors is calculated, and the permeability function of coal rock under different stress conditions is established to obtain the seepage evolution results; According to the simulated seepage evolution results, the anisotropic evolution characteristics of coal rock permeability with time, stress and gas pressure factors are analyzed; the simulation results are compared with historical experimental data, and a comparison threshold is preset. If it is greater than the comparison threshold, the model parameters are optimized.

6. The anisotropic coal rock adsorption-permeability coupling model and permeability evolution method according to claim 5, characterized in that: The process of setting the volume strain of coal rock includes the following steps: According to the historical experimental data, the permeability coupling model parameters are selected and set, including the porosity, fractal dimension and fracture inclination data of the coal rock; the different porosity and fracture structure parameters in the historical experimental data are analyzed to calculate the initial permeability; According to the pore structure of coal rock and historical experimental data, the change of initial permeability and the change of internal pores of coal rock are analyzed to obtain the increase of pore surface area; the coefficient of the increase of pore surface area is set; The porosity is analyzed according to the deformation data of coal rock to obtain the law of porosity change with stress; the deformation data of coal rock is obtained by analyzing the change law of stress and porosity of coal rock, and the volume strain of coal rock is set.

7. The anisotropic coal rock adsorption-permeability coupling model and permeability evolution method according to claim 5, characterized in that: The process of anisotropic evolution features includes the following steps: Extract the characteristics of the simulated seepage evolution results, analyze the changes of coal-rock seepage at different time points, different stress conditions and different gas pressures; draw the curve of permeability change with time, stress and gas pressure, and identify the peak value, valley value and time point of permeability change; Preprocess historical experimental data and extract features; Draw the variation curve of permeability of historical experimental data with time, stress and gas pressure; compare the variation curve of historical experimental data with the simulation variation curve; calculate the correlation coefficient, mean square error and mean absolute error index; Set a comparison threshold. If the comparison result exceeds the threshold, identify and analyze the abnormal points that exceed the threshold. And adjust the permeability coupling model according to the analysis results.

8. The anisotropic coal rock adsorption-permeability coupling model and permeability evolution method according to claim 1, characterized in that: The process of obtaining the final permeability coupling model includes the following steps: Compare the water and gas coal rock deformation characteristic permeability with the simulated coal rock deformation characteristic permeability, calculate the correlation coefficient and mean square error index; set the accuracy threshold, and perform analysis if it is greater than the accuracy threshold; The comparative results will be used to analyze the permeability under different stress states and to analyze the difference in permeability at micro and macro scales; A contrast permeability threshold is preset, and if it is greater than the contrast permeability threshold, the permeability coupling model parameters are adjusted to perform simulation; The threshold of the model parameters after comparison and adjustment is set, and the adjusted model permeability coupling model results are compared with the initial permeability coupling model parameter results. If it is greater than the threshold, the initial permeability, fracture structure parameters, Young's modulus, and Poisson's ratio are adjusted; it is iterated in sequence; and the final permeability coupling model is obtained.

9. An anisotropic coal rock adsorption-permeability coupling model system for implementing the anisotropic coal rock adsorption-permeability coupling model and permeability evolution method according to any one of claims 1 to 8, characterized in that: include: The feature analysis module is responsible for collecting and preprocessing the raw data of coal and rock to identify the anisotropic characteristics of coal and rock; Analyze the anisotropic characteristics, calculate the analysis results, and obtain the water and gas coal rock deformation characteristic permeability; The model building module is responsible for building the permeability coupling model and setting the parameters of the permeability coupling model according to historical experimental data; outputting the analysis results to the permeability coupling model to simulate the seepage evolution; and obtaining the characteristic permeability of the simulated coal rock deformation; The model update module is responsible for comparing the characteristic permeability of coal-rock deformation with water and gas with the characteristic permeability of simulated coal-rock deformation to verify the accuracy of the permeability coupling model; A comparative permeability threshold is preset. If it is greater than the comparative permeability threshold, the permeability coupling model data is adjusted and the seepage evolution is re-simulated; the process is iterated sequentially to obtain the final permeability coupling model.

Images