In-situ testing method and device for coal gas diffusion under the influence of external fluid

Abstract

The present invention discloses an in-situ testing method and device for coal body gas diffusion under the influence of an external fluid, relating to the technical field of coal mine gas extraction. The present invention comprises: S1, placing the coal body in a stress loading device; S2, applying a preset stress to the coal body through the stress loading device; S3, injecting methane into a test tank; S4, injecting water into the test tank; S5, desorbing the methane content in the coal body and calculating the diffusion coefficient of the gas in the coal body; and S6, training a neural network using the calculated diffusion coefficient to obtain a diffusion coefficient prediction model. The present invention simulates the coal body environment as a real environment, obtains the diffusion coefficient by changing the moisture, pressure, and methane concentration of the coal body environment, and uses the trained neural network to predict the diffusion coefficient.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mine gas extraction, and more particularly to an in-situ testing method and device for coal body gas diffusion under the influence of an external fluid. Background Art

[0002] During coal seam gas extraction, gas diffusion within the coal body is one of the important links in gas migration during the extraction process. Existing experimental systems are mostly used to measure gas diffusion in granular coal bodies, and fail to implement gas diffusion tests on large coal bodies that take into account the actual ground stress environment. At the same time, with the widespread implementation of deep coal seam hydraulic measures, existing testing systems are also unable to implement coal body gas diffusion tests under the condition of added fluids. To this end, the present invention provides an in-situ testing method and device for coal body gas diffusion under the influence of added fluids, which simulates the environment of the coal body as a real environment, obtains the diffusion coefficient when the moisture, pressure, and methane concentration of the coal body environment are changed, and uses a trained neural network to predict the diffusion coefficient, which is a problem that those skilled in the art urgently need to solve. Summary of the Invention

[0003] In view of this, the present invention provides a method and device for in-situ testing of coal gas diffusion under the influence of an external fluid, so as to achieve the purpose of predicting the diffusion coefficient of methane in coal.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] An in-situ test method for coal gas diffusion under the influence of an external fluid comprises the following steps:

[0006] S1: placing the coal body in a stress loading device; wherein the stress loading device is set in an experimental tank;

[0007] S2 applies a preset stress to the coal body through a stress loading device; wherein the preset stress is the actual ground stress of the coal seam in the test environment;

[0008] S3 injects methane into the experimental tank;

[0009] S4 injects water into the experimental tank;

[0010] S5 desorbs the methane content in the coal and calculates the diffusion coefficient of gas in the coal;

[0011] S6 trains the neural network using the calculated diffusion coefficient to obtain a diffusion coefficient prediction model;

[0012] S7 predicts the diffusion coefficient using the diffusion coefficient prediction model

[0013] Optional, S3 specific steps include:

[0014] Close the fifth, eighth, and tenth valves, and open the first, second, third, and fourth valves;

[0015] The gas in the gas injection pump enters the experimental tank through the second pipe section, the first pipe section, and the upper diffuser in sequence;

[0016] The experimental tank was left to stand for 48 hours to allow the coal to adsorb methane and reach an adsorption equilibrium state.

[0017] Optionally, the specific steps of S4 include:

[0018] Close the second valve, the eighth valve, and the tenth valve, and open the first valve, the fifth valve, the sixth valve, and the seventh valve;

[0019] The water in the water injection pump enters the experimental tank through the fourth pipe section, the third pipe section, the second pipe section, the first pipe section, and the upper diffuser in sequence; the gas pressure of the tank is measured by a pressure gauge.

[0020] Optionally, the specific steps of S6 include:

[0021] S6.1 Obtain the diffusion coefficient corresponding to the coal body obtained in the experiment, and obtain a sample of the coal body diffusion coefficient;

[0022] S6.2 inputs the sample into the convolutional neural network for training to obtain a trained convolutional neural network;

[0023] S6.3 inputs the sample into the trained convolutional neural network, uses the output of the fully connected layer of the trained convolutional neural network as a feature parameter, and normalizes the feature parameter to obtain a feature vector;

[0024] S6.4 inputs the feature vector into a support vector machine for feature recognition to obtain a prediction model for the diffusion coefficient of the sample.

[0025] Corresponding to the above method, the present invention further discloses an in-situ testing device for coal gas diffusion under the influence of an external fluid, comprising a test tank, a stress loading device, an air injection pump, a water injection pump, a desorption instrument, a waste collection tank, a first air path, a second air path, an axial displacement sensor, a radial displacement sensor, an A / D converter, and a computer;

[0026] The experimental tank, the air injection pump, the water injection pump, and the waste collection tank are connected through a second gas line; the experimental tank and the desorber are connected through a second gas line; the axial displacement sensor and the radial displacement sensor are respectively connected to an A / D converter for communication; the A / D converter is connected to a computer for communication; and the stress loading device is arranged in the cavity of the experimental tank.

[0027] Optionally, the test tank includes a loading tube, an upper pressure head, a lower pressure head, and a tank body; the tank body adopts a sleeve, and the upper pressure head and the lower pressure head are respectively sealed and connected to the upper and lower ends of the tank body; the coal body is arranged in a cavity formed by the tank body, the upper pressure head, and the lower pressure head;

[0028] The upper pressure head includes an upper diffuser and a first air guide channel, and the lower pressure head includes a lower diffuser and a second air guide channel.

[0029] Optionally, both the upper diffuser and the lower diffuser are provided with diffuser ports and a main port, and the plurality of diffuser ports are connected to the main port, wherein the number of the plurality of diffuser ports is greater than or equal to 2;

[0030] The loading pipe penetrates the coal body, and a plurality of through holes are arranged on the pipe body of the loading pipe, wherein the number of the plurality of through holes arranged on the pipe body of the loading pipe is greater than or equal to 2.

[0031] Optionally, the second gas path includes a first pipe segment, a second pipe segment, a third pipe segment, a fourth pipe segment, a fifth pipe segment, a sixth pipe segment, and a seventh pipe segment, wherein each pipe segment is provided with two ports;

[0032] The second port of the first pipe segment, the first port of the second pipe segment, and the first port of the third pipe segment are connected via a tee pipe fitting; the second port of the third pipe segment, the first port of the fourth pipe segment, and the first port of the fifth pipe segment are connected via a tee pipe fitting; the second port of the fifth pipe segment, the first port of the sixth pipe segment, and the first port of the seventh pipe segment are connected via a tee pipe fitting;

[0033] The first port of the first pipe section is connected to the main port of the upper diffuser, the second port of the second pipe section is connected to the air injection module, and the second port of the fourth pipe section is connected to the water injection module, so that the cavity of the experimental tank is in fluid communication with the air injection module and / or the water injection module; the second port of the seventh pipe section is connected to the main port of the lower diffuser to form a gas circulation route of tank body-lower pressure head-second gas path-upper pressure head; the second port of the sixth pipe section is connected to the waste collection tank for collecting waste discharged from the tank body.

[0034] Optionally, the second gas circuit further includes: a first valve, a second valve, a third valve, a fourth valve, a fifth valve, a sixth valve, a seventh valve, an eighth valve, a ninth valve, a tenth valve, an air pressure gauge, and a liquid flow meter;

[0035] The first valve is arranged on the first pipe section, the second valve, the third valve, and the fourth valve are arranged on the second pipe section, the fifth valve, the sixth valve, and the seventh valve are arranged on the fourth pipe section, the eighth valve is arranged on the fifth pipe section, the ninth valve is arranged on the sixth pipe section, and the tenth valve is arranged on the seventh pipe section;

[0036] The second valve, the pressure gauge with the third valve, and the fourth valve are sequentially arranged between the first port and the second port of the second pipe section, and the fifth valve, the sixth valve, and the seventh valve are arranged between the first port and the second port of the fourth pipe section.

[0037] Optionally, the first end of the first gas guiding channel is connected to one end of the loading tube, and the first end of the second gas guiding channel is connected to the other end of the loading tube; the second end of the first gas guiding channel is connected to the first gas collecting port of the first gas circuit, and the second end of the second gas guiding channel is connected to the second gas collecting port of the first gas circuit, and the total port of the first gas circuit is connected to the access port of the desorber.

[0038] It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses a data processing method that improves the accuracy of inspection, thereby achieving the following beneficial effects:

[0039] 1. The coal environment is simulated as a real environment. The diffusion coefficient is obtained by changing the moisture, pressure, and methane concentration of the coal environment. The diffusion coefficient is predicted using a trained neural network.

[0040] 2. Use an air injection pump to inject methane with a pressure equal to the actual coal seam gas pressure into the experimental tank, and use a water injection pump to inject water with an amount richer than the actual coal seam into the experimental tank to simulate the actual gas storage environment of the coal seam. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0042] Figure 1 This is a flow chart of an in-situ testing method for coal gas diffusion under the influence of an external fluid according to the present invention;

[0043] Figure 2 This is a schematic structural diagram of an in-situ testing device for coal gas diffusion under the influence of an external fluid according to the present invention;

[0044] Figure 3 For the present invention Figure 2 A partial enlarged view of the area A marked in FIG;

[0045] In the figure: 11-loading pipe, 12-upper pressure head, 121-upper diffuser, 122-first air guide channel, 13-lower pressure head, 131-lower diffuser, 132-second air guide channel, 14-tank body, 2-air injection pump, 3-water injection pump, 4-waste collection tank, 5-first air path, 611-first pipe section, 612-second pipe section, 613-third pipe section, 614-fourth pipe section, 615-fifth pipe section, 616-sixth pipe section, 617- The seventh pipe section, 621-the first valve, 622-the second valve, 623-the third valve, 624-the fourth valve, 625-the fifth valve, 626-the sixth valve, 627-the seventh valve, 628-the eighth valve, 629-the ninth valve, 620-the tenth valve, 63-the pressure gauge, 64-the liquid flow meter, 7-the axial displacement sensor, 8-the radial displacement sensor, 9-the A / D converter, 10-the computer, 101-the desorption device. DETAILED DESCRIPTION

[0046] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0047] like Figure 1 As shown, the embodiment of the present invention discloses an in-situ test method for coal gas diffusion under the influence of an external fluid, and the specific steps include:

[0048] S1: placing the coal body in a stress loading device; wherein the stress loading device is set in an experimental tank;

[0049] S2 applies a preset stress to the coal body through a stress loading device; wherein the preset stress is the actual ground stress of the coal seam in the test environment;

[0050] S3 injects methane into the experimental tank;

[0051] S4 injects water into the experimental tank;

[0052] S5 desorbs the methane content in the coal and calculates the diffusion coefficient of gas in the coal;

[0053] S6 trains the neural network using the calculated diffusion coefficient to obtain a diffusion coefficient prediction model;

[0054] S7 predicts the diffusion coefficient using the diffusion coefficient prediction model

[0055] Furthermore, the specific steps of S2 include: as the mining depth increases, the stress of the coal body increases under in-situ conditions as the ground temperature of the coal seam increases, the stress loading device can apply pressure to the coal body through the annular pressure system, and the initial pressure and preset pressure of the automatic back pressure valve are set through the pressure setting system to control the pressure of the coal body step by step, thereby accurately simulating the gas diffusion characteristics of the coal seam gas during the extraction process under in-situ conditions.

[0056] The specific steps of S5 include: closing the fourth valve 624, the fifth valve 625, the eighth valve 628, and the tenth valve 620, opening the first valve 621, the second valve 622, and the third valve 623, and turning on the valve switch and the enable switch of the desorber 101, and the free gas in the experimental tank flows into the first gas guide channel 122 and the second gas guide channel 132 through the loading pipe 11, and then flows into the desorber 101 through the pipeline connected to the desorber 101, and the desorber 101 is used to test the experimental tank. The gas in the test tank is desorbed, and the value of the pressure gauge 63 connected to the test tank is recorded as p1. The gas state equation is used to calculate the gas amount X1 in the test tank. The diffusion of gas in the coal is tested using the desorber 101 to obtain the coal diffusion coefficient under the corresponding moisture conditions. The gas in the test tank flows through the upper diffuser 121, the first pipe section 611, and the second pipe section 612, applying pressure to the pressure gauge 63 set in the second pipe section 612. The pressure gauge 63 measures the gas pressure in the test tank. The gas state equation is:

[0057] X1=V1p1T1ρ1 / T0p0ρ0ξ

[0058] Where: X1 is the amount of gas in the experimental tank, V1 is the volume of the experimental tank, T0 is the absolute temperature under standard conditions, p0 is the absolute pressure under standard conditions, T1 is the absolute temperature of the gas in the experimental tank, and ξ is the gas compression coefficient.

[0059] Furthermore, by looping steps S1-S6 and changing the ground stress, gas pressure, and water injection rate, the gas diffusion law of coal seams at different burial depths and under different moisture contents can be obtained.

[0060] Another embodiment is also included, which includes, after S6, discharging and collecting the wastewater and waste gas in the experimental tank after each test, specifically including: closing the second valve 622 and the fifth valve 625, opening the first valve 621, the eighth valve 628, the ninth valve 629, and the tenth valve 620, and the waste gas and waste liquid enter the waste collection tank 4 through the first pipe section 611, the third pipe section 613, the fifth pipe section 615, the sixth pipe section 616 and the seventh pipe section 617 and the sixth pipe section 616.

[0061] Furthermore, the specific steps of S3 include:

[0062] Close the fifth valve 625, the eighth valve 628, and the tenth valve 620, and open the first valve 621, the second valve 622, the third valve 623, and the fourth valve 624;

[0063] The gas in the gas injection pump 2 enters the experimental tank through the second pipe section 612, the first pipe section 611, and the upper diffuser 121 in sequence;

[0064] The experimental tank was left to stand for 48 hours to allow the coal to adsorb methane and reach an adsorption equilibrium state.

[0065] Furthermore, a gas injection pump 2 is used to inject methane with a pressure equal to the actual coal seam gas pressure into the experimental tank to simulate the actual gas occurrence environment of the coal seam;

[0066] Furthermore, the implementation method of S3 can also be achieved by closing the fifth valve 625 and the ninth valve 629, and opening the first valve 621, the second valve 622, the third valve 623, the fourth valve 624, the seventh valve 627, and the eighth valve 628; methane enters the experimental tank in sequence through the second pipe section 612, the first pipe section 611, the upper diffuser 121, and in sequence through the second pipe section 612, the third pipe section 613, the fifth pipe section 615, and the seventh pipe section 617, so that methane can enter the experimental tank through the two channels connected by the upper diffuser 121 and the lower diffuser 131, and then be adsorbed by the coal body.

[0067] Furthermore, the specific steps of S4 include:

[0068] Close the second valve 622, the eighth valve 628, and the tenth valve 620, and open the first valve 621, the fifth valve 625, the sixth valve 626, and the seventh valve 627;

[0069] The water in the water injection pump 3 enters the experimental tank through the fourth pipe section 614, the third pipe section 613, the second pipe section 612, the first pipe section 611, and the upper diffuser 121 in sequence; wherein, the gas pressure of the tank body is measured by the pressure gauge 63.

[0070] Furthermore, a water injection system is used to inject a certain amount of water into the coal body, and the coal body reaches a preset threshold moisture content, and the different moisture contents in the sample are multiple moisture contents between 0% and 60%, wherein the multiple moisture contents are integer moisture contents greater than or equal to 1;

[0071] Furthermore, three moisture contents of 5%, 10%, and 15% are used.

[0072] Furthermore, the implementation method of S3 may also be to close the second valve 622 and the ninth valve 629, and open the first valve 621, the fifth valve 625, the sixth valve 626, the seventh valve 627, the eighth valve 628, and the tenth valve 620;

[0073] The water in the water injection pump 3 enters the experimental tank in sequence through the fourth pipe section 614, the third pipe section 613, the second pipe section 612, the first pipe section 611, the upper diffuser 121 and in sequence through the fourth pipe section 614, the fifth pipe section 615, the seventh pipe section 617, and the lower diffuser 131, so that the water can enter the experimental tank through the two channels connected by the upper diffuser 121 and the lower diffuser 131; wherein, the water injection amount is measured by the liquid flow meter 64 set by the fourth pipe section 614.

[0074] Furthermore, the specific steps of S6 include:

[0075] S6.1 Obtain the diffusion coefficient corresponding to the coal body obtained in the experiment, and obtain a sample of the coal body diffusion coefficient;

[0076] S6.2 inputs the sample into the convolutional neural network for training to obtain a trained convolutional neural network;

[0077] S6.3 inputs the sample into the trained convolutional neural network, uses the output of the fully connected layer of the trained convolutional neural network as a feature parameter, and normalizes the feature parameter to obtain a feature vector;

[0078] S6.4 inputs the feature vector into a support vector machine for feature recognition to obtain a prediction model for the diffusion coefficient of the sample.

[0079] Furthermore, the specific steps of S6.2 include:

[0080] S6.2.1, divide the samples into training and test sets, divide the diffusion coefficient into multiple value intervals, and determine the label category for each value interval;

[0081] S6.2.2, input the sample into the convolutional neural network for training. The forward propagation algorithm is used to obtain the predicted value of the diffusion coefficient of the sample. The predicted value is compared with the true value, and the difference between the two is obtained as the loss function. The true value is the diffusion coefficient corresponding to the sample.

[0082] S6.2.3, use the backpropagation algorithm to calculate the gradient of the loss function with respect to each parameter;

[0083] S6.2.4, use the gradient descent algorithm to update and optimize each parameter of the convolutional neural network according to the gradient and learning rate to obtain the trained convolutional neural network.

[0084] The normalization formula for S6.4 is as follows:

[0085]

[0086] Where x i is the value of the characteristic parameter before normalization, xmax is the maximum value among the characteristic parameters, x min is the minimum value of the characteristic parameter, y i is the value of the normalized feature parameter.

[0087] The specific steps of S6.4 include:

[0088] S6.4.1 Construct a set of feature vectors from the normalized feature parameters;

[0089] S6.4.2 Build a support vector machine, establish a mapping relationship between the feature vector and the effective diffusion coefficient, train the support vector machine, optimize it using a grid search method, and use the trained support vector machine as the prediction model;

[0090] S6.4.3 Input the feature vector into the prediction model for feature recognition to obtain the prediction result of the effective diffusion coefficient of the sample.

[0091] The specific steps in S6.4.2 include:

[0092] S6.4.2.1 Preliminarily determine the parameter range of the support vector machine, which includes the value range of the penalty parameter, insensitivity coefficient, and kernel parameter in the support vector machine;

[0093] S6.4.2.2 Calculate the prediction accuracy of the support vector machine and further subdivide the grid based on the calculated accuracy and parameter range;

[0094] S6.4.2.3 Determine whether the support vector machine has reached the maximum accuracy. If not, repeat step S6.4.2.2. If it has reached the maximum accuracy, terminate the loop and obtain the trained support vector machine.

[0095] like Figure 2 As shown, corresponding to the above method, the present invention also discloses an in-situ test device for coal gas diffusion under the influence of an external fluid, comprising: an experimental tank, a stress loading device, an air injection pump 2, a water injection pump 3, a desorber 101, a waste collection tank 4, a first air path 5, a second air path, an axial displacement sensor 7, a radial displacement sensor 8, an A / D converter 9, and a computer 10;

[0096] The experimental tank, the air injection pump 2, the water injection pump 3, and the waste collection tank 4 are connected through a second gas path. The experimental tank and the desorber 101 are connected through a second gas path. The axial displacement sensor 7 and the radial displacement sensor 8 are respectively connected to the A / D converter 9 for communication, and the A / D converter 9 is connected to the computer 10 for communication. The stress loading device is arranged in the cavity of the experimental tank.

[0097] Furthermore, the center lines of the coal body, the loading pipe 11, the upper pressure head 12, the upper diffuser 121, the lower pressure head 13, the lower diffuser 131 and the experimental tank are collinear; the stress loading device adopts a coal body clamp, which is used to clamp the coal body and apply stress to the coal body; the axial displacement sensor 7 is used to collect axial stress data and send it to the A / D converter 9, and the radial displacement sensor 8 is used to collect radial stress data and send it to the A / D converter 9. The A / D converter 9 is used to send the collected axial stress data and radial stress data to the computer 10.

[0098] Furthermore, a thermometer is included, which is used to collect the temperature data in the test tank and send it to the A / D converter 9, and the A / D converter 9 is used to send the collected temperature data to the computer 10.

[0099] Furthermore, the experimental tank includes a loading pipe 11, an upper pressure head 12, a lower pressure head 13, and a tank body 14; the tank body 14 adopts a sleeve, and the upper pressure head 12 and the lower pressure head 13 are respectively sealed and connected to the upper and lower ends of the tank body 14; the coal body is arranged in the cavity formed by the tank body 14, the upper pressure head 12, and the lower pressure head 13;

[0100] The upper pressure head 12 includes an upper diffuser 121 and a first air guide channel 122 , and the lower pressure head 13 includes a lower diffuser 131 and a second air guide channel 132 .

[0101] Furthermore, the upper diffuser 121 and the lower diffuser 131 are both provided with diffuser ports and a main port, and the plurality of diffuser ports are connected to the main port, wherein the number of the plurality of diffuser ports is greater than or equal to 2;

[0102] The loading pipe 11 penetrates the coal body, and a plurality of through holes are arranged on the pipe body of the loading pipe 11 , wherein the number of the plurality of through holes arranged on the pipe body of the loading pipe 11 is greater than or equal to 2.

[0103] Furthermore, the diffusion openings of the upper diffuser 121 and the diffusion openings of the lower diffuser 131 respectively coincide with the upper end surface and the lower end surface of the coal body to be tested.

[0104] Further, such as Figure 3 As shown, the second gas path includes a first pipe segment 611, a second pipe segment 612, a third pipe segment 613, a fourth pipe segment 614, a fifth pipe segment 615, a sixth pipe segment 616, and a seventh pipe segment 617, wherein each pipe segment is provided with two ports;

[0105] The second port of the first pipe segment 611, the first port of the second pipe segment 612, and the first port of the third pipe segment 613 are connected via a tee pipe fitting. The second port of the third pipe segment 613, the first port of the fourth pipe segment 614, and the first port of the fifth pipe segment 615 are connected via a tee pipe fitting. The second port of the fifth pipe segment 615, the first port of the sixth pipe segment 616, and the first port of the seventh pipe segment 617 are connected via a tee pipe fitting.

[0106] The first port of the first pipe section 611 is connected to the main port of the upper diffuser 121, the second port of the second pipe section 612 is connected to the gas injection module, and the second port of the fourth pipe section 614 is connected to the water injection module, so that the cavity of the experimental tank is fluidically connected to the gas injection module and / or the water injection module; the second port of the seventh pipe section 617 is connected to the main port of the lower diffuser 131 to form a gas circulation route of the tank body 14-lower pressure head 13-second gas path-upper pressure head 12; the second port of the sixth pipe section 616 is connected to the waste collection tank 4, which is used to collect waste discharged from the tank body 14.

[0107] Further, such as Figure 3 As shown, the second gas circuit further includes: a first valve 621, a second valve 622, a third valve 623, a fourth valve 624, a fifth valve 625, a sixth valve 626, a seventh valve 627, an eighth valve 628, a ninth valve 629, a tenth valve 620, an air pressure gauge 63, and a liquid flow meter 64;

[0108] The first valve 621 is provided on the first pipe section 611 , the second valve 622 , the third valve 623 , and the fourth valve 624 are provided on the second pipe section 612 , the fifth valve 625 , the sixth valve 626 , and the seventh valve 627 are provided on the fourth pipe section 614 , the eighth valve 628 is provided on the fifth pipe section 615 , the ninth valve 629 is provided on the sixth pipe section 616 , and the tenth valve 620 is provided on the seventh pipe section 617 ;

[0109] The second valve 622, the pressure gauge 63 with the third valve 623, and the fourth valve 624 are sequentially arranged between the first port and the second port of the second pipe section 612, and the fifth valve 625, the sixth valve 626, and the seventh valve 627 are arranged between the first port and the second port of the fourth pipe section 614.

[0110] Furthermore, the valve is used to control the on-off of the pipe section.

[0111] Furthermore, the first end of the first gas guide channel 122 is connected to one end of the loading tube 11, and the first end of the second gas guide channel 132 is connected to the other end of the loading tube 11; the second end of the first gas guide channel 122 is connected to the first gas collecting port of the first gas circuit 5, and the second end of the second gas guide channel 132 is connected to the second gas collecting port of the first gas circuit 5, and the total port of the first gas circuit 5 is connected to the access port of the desorber 101.

[0112] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0113] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An in-situ testing device for coal gas diffusion under the influence of an external fluid, characterized in that: It includes an experimental tank, a stress loading device, an air injection pump, a water injection pump, a desorption instrument, a waste collection tank, a first air path, a second air path, an axial displacement sensor, a radial displacement sensor, an A / D converter, and a computer; The experimental tank, the air injection pump, the water injection pump, and the waste collection tank are connected via a second gas line; the experimental tank and the desorber are connected via a second gas line; the axial displacement sensor and the radial displacement sensor are respectively connected to an A / D converter for communication; and the A / D converter is connected to a computer for communication; and a stress loading device is disposed in the cavity of the experimental tank; The experimental tank includes a loading pipe, an upper pressure head, a lower pressure head, and a tank body. The tank body adopts a sleeve, and the upper pressure head and the lower pressure head are sealed and connected to the upper and lower ends of the tank body respectively. The coal body is placed in the cavity formed by the tank body, the upper pressure head, and the lower pressure head. The upper pressure head includes an upper diffuser and a first air guide channel, and the lower pressure head includes a lower diffuser and a second air guide channel; Both the upper diffuser and the lower diffuser are provided with diffuser ports and a main port, and multiple diffuser ports are connected to the main port; The loading pipe penetrates the coal body, and a plurality of through holes are arranged on the pipe body of the loading pipe; The second gas path includes a first pipe segment, a second pipe segment, a third pipe segment, a fourth pipe segment, a fifth pipe segment, a sixth pipe segment, and a seventh pipe segment, wherein each pipe segment is provided with two ports; The second port of the first pipe segment, the first port of the second pipe segment, and the first port of the third pipe segment are connected via a tee pipe fitting; the second port of the third pipe segment, the first port of the fourth pipe segment, and the first port of the fifth pipe segment are connected via a tee pipe fitting; the second port of the fifth pipe segment, the first port of the sixth pipe segment, and the first port of the seventh pipe segment are connected via a tee pipe fitting; The first port of the first pipe segment is connected to the main port of the upper diffuser, the second port of the second pipe segment is connected to the air injection module, and the second port of the fourth pipe segment is connected to the water injection module, so that the cavity of the experimental tank is in fluid communication with the air injection module and / or the water injection module; the second port of the seventh pipe segment is connected to the main port of the lower diffuser; and the second port of the sixth pipe segment is connected to the waste collection tank. The second gas circuit also includes: a first valve, a second valve, a third valve, a fourth valve, a fifth valve, a sixth valve, a seventh valve, an eighth valve, a ninth valve, a tenth valve, an air pressure gauge, and a liquid flow meter; The first valve is arranged on the first pipe section, the second valve, the third valve, and the fourth valve are arranged on the second pipe section, the fifth valve, the sixth valve, and the seventh valve are arranged on the fourth pipe section, the eighth valve is arranged on the fifth pipe section, the ninth valve is arranged on the sixth pipe section, and the tenth valve is arranged on the seventh pipe section; The second valve, the air pressure gauge equipped with the third valve, and the fourth valve are sequentially arranged between the first port and the second port of the second pipe section; the fifth valve, the liquid flow meter equipped with the sixth valve, and the seventh valve are sequentially arranged between the first port and the second port of the fourth pipe section; The first end of the first gas guiding channel is connected to one end of the loading tube, and the first end of the second gas guiding channel is connected to the other end of the loading tube; the second end of the first gas guiding channel is connected to the first gas collecting port of the first gas circuit, the second end of the second gas guiding channel is connected to the second gas collecting port of the first gas circuit, and the total port of the first gas circuit is connected to the access port of the desorber.

2. A method for in-situ testing of coal gas diffusion under the influence of an external fluid, using the in-situ testing device for coal gas diffusion under the influence of an external fluid according to claim 1, characterized in that: The method specifically comprises the following steps: S1: placing the coal body in a stress loading device; wherein the stress loading device is set in an experimental tank; S2 applies a preset stress to the coal body through a stress loading device; wherein the preset stress is the actual ground stress of the coal seam in the test environment; S3 injects methane into the experimental tank; S4 injects water into the experimental tank; S5 desorbs the methane content in the coal and calculates the diffusion coefficient of gas in the coal; S6 trains the neural network using the calculated diffusion coefficient to obtain a diffusion coefficient prediction model; S7 predicts the diffusion coefficient using the diffusion coefficient prediction model; The specific steps of S4 include: Close the second valve, the eighth valve, and the tenth valve, and open the first valve, the fifth valve, the sixth valve, and the seventh valve; The water in the water injection pump enters the experimental tank through the fourth pipe section, the third pipe section, the first pipe section, and the upper diffuser in sequence.

3. The in-situ testing method for coal gas diffusion under the influence of an external fluid according to claim 2, characterized in that: The specific steps of S3 include: Close the fifth, eighth, and tenth valves, and open the first, second, third, and fourth valves; The gas in the gas injection pump enters the experimental tank through the second pipe section, the first pipe section, and the upper diffuser in sequence; The experimental tank was left to stand for 48 hours to allow the coal to adsorb methane and reach an adsorption equilibrium state; Among them, the gas pressure of the tank is measured by a pressure gauge.

4. The in-situ testing method for coal gas diffusion under the influence of an external fluid according to claim 2, characterized in that: The specific steps of S6 include: S6.1 Obtain the diffusion coefficient corresponding to the coal body obtained in the experiment, and obtain a sample of the coal body diffusion coefficient; S6.2 inputs the sample into the convolutional neural network for training to obtain a trained convolutional neural network; S6.3 inputs the sample into the trained convolutional neural network, uses the output of the fully connected layer of the trained convolutional neural network as a feature parameter, and normalizes the feature parameter to obtain a feature vector; S6.4 inputs the feature vector into a support vector machine for feature recognition to obtain a prediction model for the diffusion coefficient of the sample.

Images