Coal rock microscopic fracture dynamic corrosion seepage analysis method and device

Abstract

The invention provides a coal rock microcosmic fracture dynamic corrosion seepage analysis method and device. The method comprises the steps that initial microcosmic fracture structure image information of coal rock in an initial state and real-time microcosmic fracture structure image information of the coal rock in a supercritical carbon dioxide injection state are obtained; preprocessing the initial microcosmic fracture structure image information and the real-time microcosmic fracture structure image information to obtain initial fracture geometrical morphology information and real-time fracture geometrical morphology information; according to the initial fracture geometrical morphology information and the real-time fracture geometrical morphology information, initial equivalent permeability and real-time equivalent permeability are obtained; and obtaining a target analysis result according to the initial equivalent permeability and the real-time equivalent permeability. According to the scheme, the phase change process of supercritical carbon dioxide, the evolution of a coal body microscopic fracture structure and the microscopic distribution of fluid can be displayed; the dynamic corrosion effect of the supercritical carbon dioxide on the coal fracture structure and the permeability evolution rule are disclosed.

Description

Technical Field

[0001] The present invention relates to the technical field of coal rock micro-crack structure characterization and seepage analysis, and in particular to a method and device for analyzing the dynamic dissolution seepage of coal rock micro-cracks. Background Art

[0002] As a high-quality unconventional clean energy, coalbed methane has abundant resources and huge development potential, and has gradually become an important supplement to conventional natural gas in my country. However, the low permeability of coal seams in my country seriously restricts the efficient extraction of coalbed methane. Increasing the permeability of low-permeability coal seams is the key to improving the extraction efficiency of coalbed methane. The use of supercritical carbon dioxide to fractur e coal seams can not only increase the permeability of coal seams, but also displace coalbed methane and improve the extraction efficiency. Coal is a typical fractured porous medium, in which the pore structure is mainly used as a storage and diffusion medium for coalbed methane, and the permeability is much lower than the fracture structure. The fracture structure is the main channel for coalbed methane migration. Supercritical carbon dioxide injection into coal will transform the microscopic components of the coal body, resulting in changes in the fracture structure, which in turn causes the evolution of permeability and changes in gas production. Therefore, understanding and mastering the dynamic dissolution law and permeability evolution law of coal microfracture structure under supercritical carbon dioxide has important theoretical and engineering significance for the efficient development of coalbed methane. At present, the research on the dissolution effect of supercritical carbon dioxide mostly adopts the acceleration method of static immersion, which cannot intuitively show the phase change process of supercritical carbon dioxide, the evolution of the microscopic fracture structure of the coal body and the microscopic distribution characteristics of the fluid. The invasion of supercritical carbon dioxide into the fracture of the coal body is a hidden dynamic change process caused by the combined action of physical scouring and chemical dissolution, and the dissolution process must be quantitatively characterized. Therefore, in order to reveal the dynamic dissolution effect of supercritical carbon dioxide on the fracture structure of the coal body and the law of permeability evolution, the present invention discloses a method and device for analyzing the dynamic dissolution and seepage of coal rock microscopic fractures to make up for the deficiencies of existing research. Summary of the invention

[0003] The present invention provides a method and device for analyzing dynamic dissolution and seepage of coal rock micro-cracks, which can demonstrate the phase change process of supercritical carbon dioxide, the evolution of coal body micro-crack structure and the microscopic distribution of fluid; and reveal the dynamic dissolution effect of supercritical carbon dioxide on coal body crack structure and the law of permeability evolution.

[0004] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0005] A method for analyzing dynamic dissolution seepage of coal rock micro-cracks, comprising:

[0006] Obtaining initial microscopic fracture structure image information of coal rock in an initial state, and real-time microscopic fracture structure image information of coal rock in a supercritical carbon dioxide injection state;

[0007] Preprocessing the initial microscopic crack structure image information and the real-time microscopic crack structure image information to obtain initial crack geometry information and real-time crack geometry information;

[0008] According to the initial fracture geometry information and the real-time fracture geometry information, an initial equivalent permeability and a real-time equivalent permeability are obtained;

[0009] According to the initial equivalent permeability and the real-time equivalent permeability, a target analysis result is obtained.

[0010] Optionally, preprocessing the initial microscopic crack structure image information and the real-time microscopic crack structure image information to obtain initial crack geometry information and real-time crack geometry information includes:

[0011] Transforming the initial microscopic crack structure image information and the real-time microscopic crack structure image information to obtain first initial processed image information and first real-time processed image information;

[0012] Optimizing the first initially processed image information and the first real-time processed image information to obtain second initially processed image information and second real-time processed image information;

[0013] The second initial processed image information and the second real-time processed image information are measured, extracted and calculated to obtain initial crack geometry information and real-time crack geometry information.

[0014] Optionally, transforming the initial microscopic crack structure image information and the real-time microscopic crack structure image information to obtain first initial processed image information and first real-time processed image information includes:

[0015] The initial microscopic crack structure image information and the real-time microscopic crack structure image information are linearly transformed to obtain first initial processed image information and first real-time processed image information.

[0016] Optionally, optimizing the first initially processed image information and the first real-time processed image information to obtain second initially processed image information and second real-time processed image information includes:

[0017] The first initially processed image information and the first real-time processed image information are sequentially subjected to binarization, morphological erosion, morphological thinning and repair processing to obtain second initially processed image information and second real-time processed image information.

[0018] Optionally, measuring, extracting and calculating the second initial processed image information and the second real-time processed image information to obtain initial crack geometry information and real-time crack geometry information includes:

[0019] The second initially processed image information is measured and extracted to obtain the tortuosity fractal dimension of the initial microscopic fracture structure of the coal rock, the fractal dimension, the total area of ​​the fracture, the area of ​​the coal rock sample, the angle between the fracture strike and the north direction, the angle between the fluid flow direction and the fracture, and the maximum fracture length;

[0020] Calculate the ratio of the total area of ​​the cracks in the initial microscopic crack structure of the coal rock to the area of ​​the coal rock sample to obtain the crack ratio of the initial microscopic crack structure of the coal rock;

[0021] The tortuosity fractal dimension, fractal dimension, fracture ratio, angle between fracture strike and north direction, angle between fluid flow direction and fracture and maximum fracture length of the initial microscopic fracture structure of coal rock are taken as initial fracture geometric information.

[0022] Optionally, the second initial processed image information and the second real-time processed image information are measured, extracted and calculated to obtain initial crack geometry information and real-time crack geometry information, further comprising:

[0023] The second real-time processed image information is measured and extracted to obtain the tortuosity fractal dimension of the real-time microscopic fracture structure of the coal rock, the fractal dimension, the total area of ​​the fracture, the area of ​​the coal rock sample, the angle between the fracture strike and the north direction, the angle between the fluid flow direction and the fracture, and the maximum fracture length;

[0024] Calculate the ratio of the total area of ​​the cracks in the real-time microscopic crack structure of the coal rock to the area of ​​the coal rock sample to obtain the crack ratio of the initial microscopic crack structure of the coal rock;

[0025] The tortuosity fractal dimension, fractal dimension, fracture ratio, angle between fracture strike and north direction, angle between fluid flow direction and fracture and maximum fracture length of the real-time microscopic fracture structure of coal rock are taken as real-time fracture geometry information.

[0026] Optionally, obtaining an initial equivalent permeability and a real-time equivalent permeability according to the initial fracture geometry information and the real-time fracture geometry information includes:

[0027] According to the initial fracture geometry information and the real-time fracture geometry information,

[0028] pass

[0029] The initial equivalent permeability and the real-time equivalent permeability are obtained respectively;

[0030] Where k is the equivalent permeability; D Tf is the fractal dimension of tortuosity; D f is the fractal dimension; is the crack ratio; θ1 is the angle between the crack direction and the north direction; θ2 is the angle between the fluid flow direction and the crack; β is the proportionality coefficient; L0 is the characteristic unit length; l max is the maximum crack length.

[0031] The present invention also provides a coal rock micro-crack dynamic dissolution seepage analysis device, comprising:

[0032] An acquisition module, used to acquire initial microscopic fracture structure image information of coal rock in an initial state, and real-time microscopic fracture structure image information of coal rock in a supercritical carbon dioxide injection state;

[0033] A processing module is used to preprocess the initial microscopic fracture structure image information and the real-time microscopic fracture structure image information to obtain initial fracture geometry information and real-time fracture geometry information; obtain initial equivalent permeability and real-time equivalent permeability based on the initial fracture geometry information and the real-time fracture geometry information; obtain target analysis results based on the initial equivalent permeability and the real-time equivalent permeability.

[0034] Optionally, the coal rock micro-crack dynamic dissolution seepage analysis device further includes:

[0035] The state simulation module is used to put the coal rock in a supercritical carbon dioxide injection state.

[0036] Optionally, the state simulation module includes:

[0037] A pressure-resistant chip fixture provided on the stage for fixing the coal-rock sample, wherein the pressure-resistant chip fixture adopts a hollow structure to expose the surface of the coal-rock sample;

[0038] A micro-injection pump, wherein the output end of the micro-injection pump is connected to the inlet end of the pressure-resistant chip fixture, and the suction end of the micro-injection pump is connected to a carbon dioxide liquid gas source through a pressure gauge and a one-way valve;

[0039] A waste liquid collector, the injection end of which is connected to the discharge end of the pressure-resistant chip fixture through a flow sensor;

[0040] The processing module includes: a computer;

[0041] The acquisition module comprises:

[0042] A camera is arranged above the stage, the camera end of the camera corresponds to the hollow structure of the pressure-resistant chip fixture, and the camera is electrically connected to the computer;

[0043] A microscope is arranged at the camera head end of the camera, and an infrared thermal imager is arranged at the lens end of the microscope.

[0044] The above solution of the present invention includes at least the following beneficial effects:

[0045] The above scheme of the present invention obtains the initial microscopic fracture structure image information of the coal rock in the initial state, and the real-time microscopic fracture structure image information of the coal rock in the supercritical carbon dioxide injection state; pre-processes the initial microscopic fracture structure image information and the real-time microscopic fracture structure image information to obtain the initial fracture geometry information and the real-time fracture geometry information; obtains the initial equivalent permeability and the real-time equivalent permeability according to the initial fracture geometry information and the real-time fracture geometry information; obtains the target analysis result according to the initial equivalent permeability and the real-time equivalent permeability; thereby demonstrating the phase change process of supercritical carbon dioxide, the evolution of the microscopic fracture structure of the coal body and the microscopic distribution of the fluid; and reveals the dynamic dissolution effect of supercritical carbon dioxide on the fracture structure of the coal body and the permeability evolution law. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a flow chart of a method for analyzing dynamic dissolution and seepage of coal rock micro-cracks provided by an embodiment of the present invention;

[0047] Figure 2 A module diagram of a water supply scheme determination device provided by an embodiment of the present invention;

[0048] Figure 3 A schematic structural diagram of a device for determining a water supply scheme provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0049] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0050] like Figure 1 As shown, an embodiment of the present invention provides a method for analyzing dynamic dissolution seepage of coal rock micro-cracks, comprising:

[0051] Step 11, obtaining initial microscopic fracture structure image information of the coal rock in an initial state, and real-time microscopic fracture structure image information of the coal rock in a supercritical carbon dioxide injection state;

[0052] Step 12, preprocessing the initial microscopic crack structure image information and the real-time microscopic crack structure image information to obtain initial crack geometry information and real-time crack geometry information;

[0053] Step 13, obtaining an initial equivalent permeability and a real-time equivalent permeability according to the initial fracture geometry information and the real-time fracture geometry information;

[0054] Step 14: Obtain target analysis results based on the initial equivalent permeability and the real-time equivalent permeability.

[0055] In this embodiment, by obtaining initial microscopic fracture structure image information of coal rock in an initial state and real-time microscopic fracture structure image information of coal rock in a supercritical carbon dioxide injection state; preprocessing the initial microscopic fracture structure image information and the real-time microscopic fracture structure image information to obtain initial fracture geometry information and real-time fracture geometry information; obtaining initial equivalent permeability and real-time equivalent permeability based on the initial fracture geometry information and the real-time fracture geometry information; obtaining target analysis results based on the initial equivalent permeability and the real-time equivalent permeability; thereby demonstrating the phase change process of supercritical carbon dioxide, the evolution of coal microscopic fracture structure and the microscopic distribution of fluid; revealing the dynamic dissolution effect of supercritical carbon dioxide on coal fracture structure and the law of permeability evolution.

[0056] The process of obtaining initial microscopic crack structure image information and real-time microscopic crack structure image information:

[0057] The collected coal rock sample 311 is processed into a 20 mm × 20 mm × 2 mm cube by wire cutting, and then the coal rock slice is polished until the cracks in the coal rock are clearly visible and the scratches caused by surface cutting disappear;

[0058] like Figure 3 As shown, a coal rock sample 311 is packaged into a polydimethylsiloxane chip, and then placed in a pressure-resistant chip fixture 310, fixed on a stage 309, and the initial microscopic fracture structure image information of the coal rock is obtained through an infrared thermal imager 307, a microscope 306 and a camera 305 on the stage 309;

[0059] The carbon dioxide from the carbon dioxide liquid gas source 301 is transported to the pressure-resistant chip fixture 310 through the micro-injection pump 304, so that the coal rock sample 311 is in a supercritical carbon dioxide injection state. The supercritical carbon dioxide enters the micro-crack structure of the coal rock sample 311, realizing the dynamic dissolution of the micro-crack structure, and the real-time micro-crack structure image information of the coal rock is obtained through the infrared thermal imager 307, microscope 306 and camera 305 on the stage 309.

[0060] Through the above process, it is possible

[0061] In an optional embodiment of the present invention, step 12 includes:

[0062] Step 121, transforming the initial microscopic crack structure image information and the real-time microscopic crack structure image information to obtain first initial processed image information and first real-time processed image information;

[0063] Step 122, optimizing the first initially processed image information and the first real-time processed image information to obtain second initially processed image information and second real-time processed image information;

[0064] Step 123, measuring, extracting and calculating the second initially processed image information and the second real-time processed image information to obtain initial crack geometry information and real-time crack geometry information.

[0065] In this embodiment, by transforming the initial microscopic crack structure image information and the real-time microscopic crack structure image information, cracks and background can be further distinguished, thereby obtaining high-contrast first initial processed image information and first real-time processed image information, which is convenient for subsequent processing;

[0066] By optimizing the first initial processed image information and the first real-time processed image information, impurities are further removed to obtain second initial processed image information and second real-time processed image information containing only crack structures and matrix, so as to facilitate subsequent processing;

[0067] By measuring, extracting and calculating the second initial processed image information and the second real-time processed image information, initial fracture geometry information and real-time fracture geometry information are obtained, so as to obtain initial equivalent permeability and real-time equivalent permeability according to the initial fracture geometry information and the real-time fracture geometry information;

[0068] The process in this embodiment can be implemented by ImageJ software, and can also be implemented by other software that can implement the above process, which is not limited in this application.

[0069] In an optional embodiment of the present invention, step 121 includes:

[0070] Step 1211, performing linear grayscale transformation on the initial microscopic crack structure image information and the real-time microscopic crack structure image information to obtain first initial processed image information and first real-time processed image information.

[0071] In this embodiment, in order to further distinguish cracks from the background, a linear grayscale transformation is performed on the initial microscopic crack structure image information and the real-time microscopic crack structure image information to enhance the contrast, thereby obtaining a first initial processed image information and a first real-time processed image information with high contrast.

[0072] In an optional embodiment of the present invention, step 122 includes:

[0073] Step 1221, binarization, morphological erosion, morphological refinement and restoration are performed on the first initial processed image information and the first real-time processed image information in sequence to obtain second initial processed image information and second real-time processed image information.

[0074] In this embodiment, the grayscale value of the target crack is set to 1, and the background matrix is ​​set to 0. The first initial processed image information and the first real-time processed image information are sequentially subjected to binarization, morphological corrosion, morphological refinement and repair processing, which can further remove impurities and obtain standard binarized second initial processed image information and second real-time processed image information containing only the crack structure and the matrix, so as to facilitate subsequent measurement extraction and calculation processing to obtain initial crack geometric morphology information and real-time crack geometric morphology information.

[0075] In an optional embodiment of the present invention, step 123 includes:

[0076] Step 1231, measuring and extracting the second initially processed image information to obtain the tortuosity fractal dimension of the initial microscopic fracture structure of the coal rock, the fractal dimension, the total area of ​​the fracture, the area of ​​the coal rock sample, the angle between the fracture strike and the north direction, the angle between the fluid flow direction and the fracture, and the maximum fracture length;

[0077] Calculate the ratio of the total area of ​​the cracks in the initial microscopic crack structure of the coal rock to the area of ​​the coal rock sample to obtain the crack ratio of the initial microscopic crack structure of the coal rock;

[0078] The tortuosity fractal dimension, fractal dimension, fracture ratio, angle between fracture strike and north direction, angle between fluid flow direction and fracture and maximum fracture length of the initial microscopic fracture structure of coal rock are taken as initial fracture geometric information.

[0079] In this embodiment, the tortuosity fractal dimension and fractal dimension of the initial microscopic fracture structure of the coal rock are measured by the box counting dimension method; the total area of ​​the fractures of the initial microscopic fracture structure of the coal rock, the area of ​​the coal rock sample, the angle between the direction of the fracture and the north direction, the angle between the fluid flow direction and the fracture, and the maximum fracture length can be obtained by the measurement function in the ImageJ software; the fracture rate of the initial microscopic fracture structure of the coal rock is the ratio of the total area of ​​the fractures of the initial microscopic fracture structure of the coal rock to the area of ​​the coal rock sample;

[0080] Taking the tortuosity fractal dimension, fractal dimension, fracture ratio, angle between the fracture strike and the north direction, angle between the fluid flow direction and the fracture, and maximum fracture length of the initial micro-fracture structure of coal rock as the initial fracture geometry information can accurately reflect the fracture geometry of the initial micro-fracture structure of coal rock, which is convenient for subsequent calculation of the initial equivalent permeability.

[0081] In an optional embodiment of the present invention, step 123 further includes:

[0082] Step 1232, measuring and extracting the second real-time processed image information to obtain the tortuosity fractal dimension of the real-time microscopic fracture structure of the coal rock, the fractal dimension, the total area of ​​the fracture, the area of ​​the coal rock sample, the angle between the fracture strike and the north direction, the angle between the fluid flow direction and the fracture, and the maximum fracture length;

[0083] Calculate the ratio of the total area of ​​the cracks in the real-time microscopic crack structure of the coal rock to the area of ​​the coal rock sample to obtain the crack ratio of the initial microscopic crack structure of the coal rock;

[0084] The tortuosity fractal dimension, fractal dimension, fracture ratio, angle between fracture strike and north direction, angle between fluid flow direction and fracture and maximum fracture length of the real-time microscopic fracture structure of coal rock are taken as real-time fracture geometry information.

[0085] In this embodiment, the tortuosity fractal dimension and fractal dimension of the real-time microscopic fracture structure of the coal rock are measured by the box counting dimension method; the total area of ​​the fractures in the real-time microscopic fracture structure of the coal rock, the area of ​​the coal rock sample, the angle between the direction of the fracture and the north direction, the angle between the fluid flow direction and the fracture, and the maximum fracture length can be obtained by the measurement function in the ImageJ software; the fracture rate of the real-time microscopic fracture structure of the coal rock is the ratio of the total area of ​​the fractures in the real-time microscopic fracture structure of the coal rock to the area of ​​the coal rock sample;

[0086] Taking the tortuosity fractal dimension, fractal dimension, fracture ratio, angle between fracture strike and north direction, angle between fluid flow direction and fracture and maximum fracture length of the real-time micro-fracture structure of coal rock as real-time fracture geometry information can accurately reflect the fracture geometry of the real-time micro-fracture structure of coal rock, which is convenient for subsequent calculation to obtain real-time equivalent permeability.

[0087] In an optional embodiment of the present invention, step 13 includes:

[0088] According to the initial fracture geometry information and the real-time fracture geometry information,

[0089] pass

[0090] The initial equivalent permeability and the real-time equivalent permeability are obtained respectively;

[0091] Where k is the equivalent permeability; D Tf is the fractal dimension of tortuosity; D f is the fractal dimension; is the crack ratio; θ1 is the angle between the crack direction and the north direction; θ2 is the angle between the fluid flow direction and the crack; β is the proportionality coefficient; L0 is the characteristic unit length; l max is the maximum crack length.

[0092] In this embodiment, according to the initial crack geometry information and the real-time crack geometry information, The initial equivalent permeability and real-time equivalent permeability are obtained respectively, which can accurately reflect the changes in the microscopic fracture structure of coal rock under the supercritical carbon dioxide injection state, thereby causing changes in permeability and changes in fluid distribution laws;

[0093] In this embodiment, β=0.0526; L0 is the characteristic unit length, that is, the length of the coal rock sample. In this embodiment, L0=0.02m.

[0094] In an optional embodiment of the present invention, step 14 includes:

[0095] The initial equivalent permeability and real-time equivalent permeability are used to draw a curve as the target analysis result, so that the curve can reflect the permeability change of the micro-fracture structure of coal rock under the supercritical carbon dioxide injection state, and indirectly reflect the change of fluid distribution law.

[0096] Implementation process of dynamic dissolution and seepage analysis method for coal rock micro-cracks:

[0097] Preparation of coal rock sample 311: The collected coal rock sample 311 is processed into a 20 mm × 20 mm × 2 mm cube by wire cutting, and then the coal rock slice is grinded and polished until the cracks in the coal rock are clearly visible and the scratches caused by surface cutting disappear;

[0098] Construction of analytical device: Figure 3 As shown, the coal rock sample 311 is encapsulated into a polydimethylsiloxane chip, and then placed in a pressure-resistant chip fixture 310 and fixed on a stage 309; a camera 305 is installed on the stage 309 so that the camera of the camera 305 corresponds to the hollow structure of the pressure-resistant chip fixture 310, a microscope 306 is installed at the camera end of the camera 305, an infrared thermal imager 307 is installed at the lens end of the microscope 306, and the camera 305 is electrically connected to a computer 308; the output end of the micro-injection pump 304 is connected to the inlet end of the pressure-resistant chip fixture 310, and the suction end of the micro-injection pump 304 is connected to the carbon dioxide liquid gas source 301 through a pressure gauge 303 and a one-way valve 302; the injection end of the waste liquid collector 313 is connected to the discharge end of the pressure-resistant chip fixture 310 through a flow sensor 312;

[0099] Acquisition of initial microscopic crack structure image information: Acquiring initial microscopic crack structure image information of coal rock through the infrared thermal imager 307, microscope 306 and camera 305 on the stage 309;

[0100] Acquisition of real-time microscopic fracture structure image information: The carbon dioxide from the carbon dioxide liquid gas source 301 is transported to the pressure-resistant chip fixture 310 through the micro-injection pump 304, so that the coal rock sample 311 is in a supercritical carbon dioxide injection state, and the supercritical carbon dioxide enters the microscopic fracture structure of the coal rock sample 311 to achieve dynamic dissolution of the microscopic fracture structure. The real-time microscopic fracture structure image information of the coal rock is obtained through the infrared thermal imager 307, the microscope 306 and the camera 305 on the stage 309;

[0101] Get the initial crack geometry information and real-time crack geometry information:

[0102] Performing linear grayscale transformation on the initial microscopic crack structure image information and the real-time microscopic crack structure image information to obtain first initial processed image information and first real-time processed image information;

[0103] The first initial processed image information and the first real-time processed image information are sequentially subjected to binarization, morphological erosion, morphological thinning and restoration processing to obtain second initial processed image information and second real-time processed image information;

[0104] The second initially processed image information is measured and extracted to obtain the tortuosity fractal dimension, fractal dimension, total area of ​​the cracks, coal rock sample area, angle between the direction of the cracks and the north direction, angle between the fluid flow direction and the cracks, and maximum crack length of the initial microscopic crack structure of the coal rock; the ratio of the total area of ​​the cracks in the initial microscopic crack structure of the coal rock to the area of ​​the coal rock sample is calculated to obtain the crack ratio of the initial microscopic crack structure of the coal rock; the tortuosity fractal dimension, fractal dimension, crack ratio, angle between the direction of the cracks and the north direction, angle between the fluid flow direction and the cracks, and maximum crack length of the initial microscopic crack structure of the coal rock are used as initial crack geometric morphology information;

[0105] The second real-time processed image information is measured and extracted to obtain the tortuosity fractal dimension, fractal dimension, total area of ​​the cracks, coal rock sample area, angle between the direction of the cracks and the north direction, angle between the fluid flow direction and the cracks, and maximum crack length of the real-time microscopic crack structure of the coal rock; the ratio of the total area of ​​the cracks in the real-time microscopic crack structure of the coal rock to the area of ​​the coal rock sample is calculated to obtain the crack ratio of the initial microscopic crack structure of the coal rock; the tortuosity fractal dimension, fractal dimension, crack ratio, angle between the direction of the cracks and the north direction, angle between the fluid flow direction and the cracks, and maximum crack length of the real-time microscopic crack structure of the coal rock are used as real-time crack geometric morphology information;

[0106] Obtaining the initial equivalent permeability and the real-time equivalent permeability: According to the initial fracture geometry information and the real-time fracture geometry information, by The initial equivalent permeability and the real-time equivalent permeability are obtained respectively;

[0107] The initial equivalent permeability and real-time equivalent permeability are used to draw a curve as the target analysis result, so that the curve can reflect the permeability change of the micro-fracture structure of coal rock under the supercritical carbon dioxide injection state, and indirectly reflect the change of fluid distribution law.

[0108] Through the above process, the phase change process of supercritical carbon dioxide, the evolution of the microscopic fracture structure of the coal body and the microscopic distribution of the fluid can be demonstrated; the dynamic dissolution effect of supercritical carbon dioxide on the fracture structure of the coal body and the permeability evolution law can be revealed.

[0109] like Figure 2 As shown, an embodiment of the present invention further provides a coal rock micro-crack dynamic dissolution seepage analysis device 20, comprising:

[0110] An acquisition module 21 is used to acquire initial microscopic fracture structure image information of coal rock in an initial state, and real-time microscopic fracture structure image information of coal rock in a supercritical carbon dioxide injection state;

[0111] The processing module 22 is used to preprocess the initial microscopic fracture structure image information and the real-time microscopic fracture structure image information to obtain initial fracture geometry information and real-time fracture geometry information; obtain initial equivalent permeability and real-time equivalent permeability based on the initial fracture geometry information and the real-time fracture geometry information; obtain target analysis results based on the initial equivalent permeability and the real-time equivalent permeability.

[0112] Optionally, the coal rock micro-crack dynamic dissolution seepage analysis device further includes:

[0113] The state simulation module is used to put the coal rock in a supercritical carbon dioxide injection state.

[0114] Optionally, the state simulation module includes:

[0115] A pressure-resistant chip fixture 310 disposed on the stage 309 and used to fix the coal rock sample 311, wherein the pressure-resistant chip fixture 310 adopts a hollow structure to expose the surface of the coal rock sample 311;

[0116] A micro-injection pump 304, wherein the output end of the micro-injection pump 304 is connected to the inlet end of the pressure-resistant chip fixture 310, and the suction end of the micro-injection pump 304 is connected to the carbon dioxide liquid gas source 301 through a pressure gauge 303 and a one-way valve 302;

[0117] A waste liquid collector 313, the injection end of the waste liquid collector 313 is connected to the discharge end of the pressure-resistant chip fixture 310 through a flow sensor 312;

[0118] The processing module includes: a computer 308;

[0119] The acquisition module comprises:

[0120] A camera 305 is disposed above the stage 309, wherein the camera end of the camera 305 corresponds to the hollow structure of the pressure-resistant chip fixture 310, and the camera 305 is electrically connected to the computer 308;

[0121] A microscope 306 is disposed at the camera end of the camera 305 , and an infrared thermal imager 307 is disposed at the lens end of the microscope 306 .

[0122] In this embodiment: the coal rock sample 311 is encapsulated into a polydimethylsiloxane chip, and then placed in a pressure-resistant chip fixture 310, fixed on a stage 309, so as to fix the coal rock sample 311, and image information of the microscopic fracture structure of the coal rock sample 311 is obtained by an infrared thermal imager 307, a microscope 306 and a camera 305, and the image information is transmitted to a computer 308 for processing; the carbon dioxide in the carbon dioxide liquid gas source 301 is injected into the pressure-resistant chip fixture 310 under the action of a micro-injection pump 304, so that the coal rock sample 311 is in a supercritical carbon dioxide injection state, and the supercritical carbon dioxide enters the microscopic fracture structure of the coal rock sample 311, so as to realize dynamic dissolution of the microscopic fracture structure; the input direction of the carbon dioxide is ensured by a one-way valve 302; the pressure is observed by a pressure gauge 303 to ensure the safety of carbon dioxide transportation; and the excess carbon dioxide in the pressure-resistant chip fixture 310 is collected by a waste liquid collector 313.

[0123] Optionally, preprocessing the initial microscopic crack structure image information and the real-time microscopic crack structure image information to obtain initial crack geometry information and real-time crack geometry information includes:

[0124] Transforming the initial microscopic crack structure image information and the real-time microscopic crack structure image information to obtain first initial processed image information and first real-time processed image information;

[0125] Optimizing the first initially processed image information and the first real-time processed image information to obtain second initially processed image information and second real-time processed image information;

[0126] The second initial processed image information and the second real-time processed image information are measured, extracted and calculated to obtain initial crack geometry information and real-time crack geometry information.

[0127] Optionally, transforming the initial microscopic crack structure image information and the real-time microscopic crack structure image information to obtain first initial processed image information and first real-time processed image information includes:

[0128] The initial microscopic crack structure image information and the real-time microscopic crack structure image information are linearly transformed to obtain first initial processed image information and first real-time processed image information.

[0129] Optionally, optimizing the first initially processed image information and the first real-time processed image information to obtain second initially processed image information and second real-time processed image information includes:

[0130] The first initially processed image information and the first real-time processed image information are sequentially subjected to binarization, morphological erosion, morphological thinning and repair processing to obtain second initially processed image information and second real-time processed image information.

[0131] Optionally, measuring, extracting and calculating the second initial processed image information and the second real-time processed image information to obtain initial crack geometry information and real-time crack geometry information includes:

[0132] The second initially processed image information is measured and extracted to obtain the tortuosity fractal dimension of the initial microscopic fracture structure of the coal rock, the fractal dimension, the total area of ​​the fracture, the area of ​​the coal rock sample, the angle between the fracture strike and the north direction, and the angle between the fluid flow direction and the fracture;

[0133] Calculate the ratio of the total area of ​​the cracks in the initial microscopic crack structure of the coal rock to the area of ​​the coal rock sample to obtain the crack ratio of the initial microscopic crack structure of the coal rock;

[0134] The tortuosity fractal dimension, fractal dimension, fracture ratio, the angle between the fracture strike and the north direction, and the angle between the fluid flow direction and the fracture of the initial microscopic fracture structure of coal rock are taken as the initial fracture geometry information.

[0135] Optionally, the second initial processed image information and the second real-time processed image information are measured, extracted and calculated to obtain initial crack geometry information and real-time crack geometry information, further comprising:

[0136] The second real-time processed image information is measured and extracted to obtain the tortuosity fractal dimension of the real-time microscopic fracture structure of the coal rock, the fractal dimension, the total area of ​​the fracture, the area of ​​the coal rock sample, the angle between the fracture strike and the north direction, and the angle between the fluid flow direction and the fracture;

[0137] Calculate the ratio of the total area of ​​the cracks in the real-time microscopic crack structure of the coal rock to the area of ​​the coal rock sample to obtain the crack ratio of the initial microscopic crack structure of the coal rock;

[0138] The tortuosity fractal dimension, fractal dimension, fracture ratio, the angle between the fracture strike and the north direction, and the angle between the fluid flow direction and the fracture of the real-time microscopic fracture structure of coal rock are taken as real-time fracture geometry information.

[0139] Optionally, obtaining an initial equivalent permeability and a real-time equivalent permeability according to the initial fracture geometry information and the real-time fracture geometry information includes:

[0140] According to the initial fracture geometry information and the real-time fracture geometry information,

[0141] pass

[0142] The initial equivalent permeability and the real-time equivalent permeability are obtained respectively;

[0143] Where k is the equivalent permeability; D Tf is the fractal dimension of tortuosity; D f is the fractal dimension; is the crack ratio; θ1 is the angle between the crack direction and the north direction; θ2 is the angle between the fluid flow direction and the crack; β is the proportionality coefficient; L0 is the characteristic unit length; l max is the maximum crack length.

[0144] It should be noted that the device is a device corresponding to the above method, and all implementation methods in the above method embodiments are applicable to the embodiments of the device and can achieve the same technical effects.

[0145] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for analyzing dynamic dissolution seepage of coal rock micro-cracks, characterized in that: include: Obtaining initial microscopic fracture structure image information of coal rock in an initial state, and real-time microscopic fracture structure image information of coal rock in a supercritical carbon dioxide injection state; Preprocessing the initial microscopic crack structure image information and the real-time microscopic crack structure image information to obtain initial crack geometry information and real-time crack geometry information; According to the initial fracture geometry information and the real-time fracture geometry information, an initial equivalent permeability and a real-time equivalent permeability are obtained; According to the initial equivalent permeability and the real-time equivalent permeability, a target analysis result is obtained.

2. The method for analyzing dynamic dissolution and seepage of coal rock micro-cracks according to claim 1, characterized in that: Preprocessing the initial microscopic crack structure image information and the real-time microscopic crack structure image information to obtain initial crack geometry information and real-time crack geometry information includes: Transforming the initial microscopic crack structure image information and the real-time microscopic crack structure image information to obtain first initial processed image information and first real-time processed image information; Optimizing the first initially processed image information and the first real-time processed image information to obtain second initially processed image information and second real-time processed image information; The second initial processed image information and the second real-time processed image information are measured, extracted and calculated to obtain initial crack geometry information and real-time crack geometry information.

3. The method for analyzing dynamic dissolution and seepage of coal rock micro-cracks according to claim 2, characterized in that: The initial microscopic crack structure image information and the real-time microscopic crack structure image information are transformed to obtain first initial processed image information and first real-time processed image information, including: The initial microscopic crack structure image information and the real-time microscopic crack structure image information are linearly transformed to obtain first initial processed image information and first real-time processed image information.

4. The method for analyzing dynamic dissolution and seepage of coal rock micro-cracks according to claim 2, characterized in that: Optimizing the first initially processed image information and the first real-time processed image information to obtain second initially processed image information and second real-time processed image information, including: The first initially processed image information and the first real-time processed image information are sequentially subjected to binarization, morphological erosion, morphological thinning and repair processing to obtain second initially processed image information and second real-time processed image information.

5. The method for analyzing dynamic dissolution and seepage of coal rock micro-cracks according to claim 2, characterized in that: The second initial processed image information and the second real-time processed image information are measured, extracted and calculated to obtain initial crack geometry information and real-time crack geometry information, including: The second initially processed image information is measured and extracted to obtain the tortuosity fractal dimension of the initial microscopic fracture structure of the coal rock, the fractal dimension, the total area of ​​the fracture, the area of ​​the coal rock sample, the angle between the fracture strike and the north direction, the angle between the fluid flow direction and the fracture, and the maximum fracture length; Calculate the ratio of the total area of ​​the cracks in the initial microscopic crack structure of the coal rock to the area of ​​the coal rock sample to obtain the crack ratio of the initial microscopic crack structure of the coal rock; The tortuosity fractal dimension, fractal dimension, fracture ratio, angle between fracture strike and north direction, angle between fluid flow direction and fracture and maximum fracture length of the initial microscopic fracture structure of coal rock are taken as initial fracture geometric information.

6. The method for analyzing dynamic dissolution and seepage of coal rock micro-cracks according to claim 5, characterized in that: The second initial processed image information and the second real-time processed image information are measured, extracted and calculated to obtain initial crack geometry information and real-time crack geometry information, further comprising: The second real-time processed image information is measured and extracted to obtain the tortuosity fractal dimension of the real-time microscopic fracture structure of the coal rock, the fractal dimension, the total area of ​​the fracture, the area of ​​the coal rock sample, the angle between the fracture strike and the north direction, the angle between the fluid flow direction and the fracture, and the maximum fracture length; Calculate the ratio of the total area of ​​the cracks in the real-time microscopic crack structure of the coal rock to the area of ​​the coal rock sample to obtain the crack ratio of the initial microscopic crack structure of the coal rock; The tortuosity fractal dimension, fractal dimension, fracture ratio, angle between fracture strike and north direction, angle between fluid flow direction and fracture and maximum fracture length of the real-time microscopic fracture structure of coal rock are taken as real-time fracture geometry information.

7. The method for analyzing dynamic dissolution and seepage of coal rock micro-cracks according to claim 1, characterized in that: According to the initial fracture geometry information and the real-time fracture geometry information, an initial equivalent permeability and a real-time equivalent permeability are obtained, including: According to the initial fracture geometry information and the real-time fracture geometry information, pass The initial equivalent permeability and the real-time equivalent permeability are obtained respectively; Where k is the equivalent permeability; D Tf is the fractal dimension of tortuosity; D f is the fractal dimension; is the crack ratio; θ1 is the angle between the crack direction and the north direction; θ2 is the angle between the fluid flow direction and the crack; β is the proportionality coefficient; L0 is the characteristic unit length; l max is the maximum crack length.

8. A device for analyzing dynamic dissolution and seepage of coal rock micro-cracks, characterized in that: include: An acquisition module, used to acquire initial microscopic fracture structure image information of coal rock in an initial state, and real-time microscopic fracture structure image information of coal rock in a supercritical carbon dioxide injection state; A processing module is used to preprocess the initial microscopic fracture structure image information and the real-time microscopic fracture structure image information to obtain initial fracture geometry information and real-time fracture geometry information; obtain initial equivalent permeability and real-time equivalent permeability based on the initial fracture geometry information and the real-time fracture geometry information; obtain target analysis results based on the initial equivalent permeability and the real-time equivalent permeability.

9. The device for analyzing dynamic dissolution and seepage of coal rock micro-cracks according to claim 8, characterized in that: Also includes: The state simulation module is used to put the coal rock in a supercritical carbon dioxide injection state.

10. The device for analyzing dynamic dissolution and seepage of coal rock micro-cracks according to claim 9, characterized in that: The state simulation module comprises: A pressure-resistant chip fixture provided on the stage for fixing the coal-rock sample, wherein the pressure-resistant chip fixture adopts a hollow structure to expose the surface of the coal-rock sample; A micro-injection pump, wherein the output end of the micro-injection pump is connected to the inlet end of the pressure-resistant chip fixture, and the suction end of the micro-injection pump is connected to a carbon dioxide liquid gas source through a pressure gauge and a one-way valve; A waste liquid collector, the injection end of which is connected to the discharge end of the pressure-resistant chip fixture through a flow sensor; The processing module includes: a computer; The acquisition module comprises: A camera is arranged above the stage, the camera end of the camera corresponds to the hollow structure of the pressure-resistant chip fixture, and the camera is electrically connected to the computer; A microscope is arranged at the camera head end of the camera, and an infrared thermal imager is arranged at the lens end of the microscope.

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