A method and system for precise near-distance coal seam gas extraction based on the spatiotemporal evolution of mining-induced fractures

Abstract

This invention discloses a method and system for precise gas extraction from nearby coal seams based on the spatiotemporal evolution of mining-induced fractures, relating to the field of underground coal mine gas extraction technology. The method includes: acquiring the spatiotemporal evolution law of mining-induced fractures during nearby coal seam mining; determining the optimal spatiotemporal layout parameters of extraction boreholes based on the spatiotemporal evolution law, so that the dynamic extraction windows of at least a portion of the extraction boreholes match the spatiotemporal evolution of the gas-enriched zone formed by mining; and performing gas extraction according to the optimal layout parameters. This invention overcomes the spatiotemporal misalignment defect between traditional static borehole layout methods and the real-time development state of mining-induced fractures by dynamically matching the layout of extraction boreholes with the spatiotemporal evolution law of mining-induced fractures. This significantly improves the gas extraction efficiency of nearby coal seam groups and reduces the risk of gas exceeding limits at the working face.

Description

Technical Field

[0001] This invention relates to the field of underground coal mine gas extraction technology, and in particular to a method and system for precise extraction of coal seam gas at close range based on the spatiotemporal evolution of mining-induced fractures. Background Technology

[0002] Mining of closely spaced coal seams is a typical characteristic of many mining areas in my country. These coal seams are characterized by a large number of layers, small interlayer spacing, and are generally soft, poorly permeable, and have high gas content. During the mining of closely spaced coal seams, the mining of the upper coal seam inevitably damages the roof structure of the lower coal seam, while the mining of the lower coal seam further disturbs the overlying collapsed rock mass, resulting in extremely complex dynamic evolution characteristics of the mining stress field and fracture field in both time and space.

[0003] However, existing gas drainage methods, whether pre-drainage through roof and floor rock tunnels or in-seam drainage along the coal seam, determine borehole locations and drainage parameters based on pre-mining static geological conditions. They do not consider the dynamic impact of the complete spatiotemporal evolution of fractures during mining—from initiation, expansion, connection to closure—on gas transport channels and enrichment areas. This "spatiotemporal misalignment" between the drainage scheme and the real-time development of mining-induced fractures is a key reason for the persistently low efficiency of gas drainage from nearby coal seams and the recurring problem of gas exceeding limits at the working face. Summary of the Invention

[0004] In view of the above-mentioned shortcomings in the current technology of underground gas extraction in coal mines, the present invention provides a method and system for precise gas extraction from coal seams at close range based on the spatiotemporal evolution of mining-induced fractures. This method enables dynamic matching between the layout of extraction boreholes and the spatiotemporal evolution law of mining-induced fractures, thereby achieving the effect of precise gas extraction.

[0005] To achieve the above objectives, the embodiments of the present invention adopt the following technical solutions:

[0006] A precise method for near-field coal seam gas extraction based on the spatiotemporal evolution of mining-induced fractures includes:

[0007] To obtain the spatiotemporal evolution of mining-induced fractures during close-range coal seam mining;

[0008] Based on the spatiotemporal evolution law, the optimal arrangement parameters of the extraction boreholes in spatiotemporal space are determined, wherein the optimal arrangement parameters make the dynamic extraction window of at least a portion of the extraction boreholes match the spatiotemporal evolution of the gas enrichment zone formed by mining.

[0009] Gas extraction is performed based on the optimal layout parameters.

[0010] According to one aspect of the present invention, obtaining the spatiotemporal evolution law of the mining-induced fracture specifically includes:

[0011] Construct a physically similar material model and / or a numerical model of the target coal seam;

[0012] Simulate the coal seam mining process and record the dynamic changes in time and space of the damage and fracture development of the overlying and floor strata as the working face advances;

[0013] The dynamic changes of the overlying rock strata include the dynamic changes in the height and range of the caving zone, the delamination fracture zone, and the bending subsidence zone as the working face advances; the dynamic changes of the bottom rock strata include the dynamic changes in the bottom failure zone, the intact rock strata zone, and the confined water uplift zone as the working face advances in depth and range.

[0014] According to one aspect of the present invention, determining the optimal layout parameters of the extraction borehole based on the spatiotemporal evolution law specifically includes:

[0015] The final location of at least the first type of borehole used for extracting depressurized gas from the adjacent upper layer is determined within the delamination fracture zone;

[0016] The final location of at least the second type of borehole used for extracting depressurized gas from the adjacent layer is determined within the effective depressurization area above the base plate failure zone.

[0017] According to one aspect of the present invention, the physically similar material model is made of sand as aggregate, lime and gypsum as cementing materials, and citric acid as retarder; the numerical model is a FLAC3D discrete element model.

[0018] According to one aspect of the present invention, the final position of the first type of borehole is determined based on the evolution characteristics of the "O"-shaped ring or annular fracture ring formed around the goaf, and the height of the stratum corresponding to the optimal gas extraction concentration and the distance from the working face during the entire process from fracture initiation to closure.

[0019] According to one aspect of the present invention, a borehole imaging instrument is used to inspect the second type of borehole to directly observe the damage and fracture development of rock strata at different depths of the base plate, in order to verify and correct the boundary range of the effective pressure relief area.

[0020] According to one aspect of the invention, it further includes:

[0021] Multiple sets of test boreholes with different layout parameters were constructed, and the multiple sets of test boreholes covered different strata heights and distances from the working face cut-out.

[0022] Continuously monitor the gas extraction parameters of each test borehole throughout the entire mining impact cycle;

[0023] The stratigraphic position and distance corresponding to the borehole with the highest extraction concentration and the longest effective extraction period among the test boreholes are used as the basis for determining the optimal layout parameters.

[0024] According to one aspect of the present invention, the gas extraction parameters include gas concentration and flow rate; the continuous monitoring is performed using a gas parameter measuring instrument for the gas extraction pipeline.

[0025] According to one aspect of the present invention, the method is applied to mining conditions of closely spaced, low-permeability, and high-gas coal seams, and is used to solve the problem of low gas extraction efficiency caused by the superimposed mining stress of multiple coal seams.

[0026] A near-field coal seam gas precision extraction system based on the spatiotemporal evolution of mining-induced fractures includes:

[0027] The acquisition module acquires the spatiotemporal evolution of mining-induced fractures during close-range coal seam mining.

[0028] The parameter module determines the optimal arrangement parameters of the extraction boreholes in time and space according to the spatiotemporal evolution law, wherein the optimal arrangement parameters make the dynamic extraction window of at least a portion of the extraction boreholes match the spatiotemporal evolution of the gas enrichment zone formed by mining.

[0029] The module is used to perform gas extraction based on the optimal layout parameters.

[0030] The advantages of this invention are as follows: By obtaining the spatiotemporal evolution law of mining-induced fractures during close-range coal seam mining, and determining the optimal spatiotemporal arrangement parameters of the drainage boreholes accordingly, the dynamic drainage windows of at least some drainage boreholes can match the spatiotemporal evolution of the gas enrichment zone formed by mining. This effectively overcomes the "spatiotemporal misalignment" defect between traditional drainage schemes and the real-time development state of mining-induced fractures, achieves precise drainage of depressurized gas, significantly improves the gas drainage efficiency of close-range coal seam groups, reduces the risk of gas exceeding limits at the working face, and provides a reliable guarantee for safe mine production. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the process for a precise near-distance coal seam gas extraction method based on the spatiotemporal evolution of mining-induced fractures, as described in this invention.

[0033] Figure 2This is a schematic diagram of the process of a near-distance coal seam gas precision extraction system based on the spatiotemporal evolution of mining-induced fractures, as described in this invention. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] like Figure 1 As shown, a method for precise extraction of gas from nearby coal seams based on the spatiotemporal evolution of mining-induced fractures includes the following steps:

[0037] Step S1: Obtain the spatiotemporal evolution of mining-induced fractures during close-range coal seam mining.

[0038] Step S1 specifically includes: First, collecting geological data of the target working face area, including the occurrence state of coal and rock strata, physical and mechanical parameters of each stratum, gas content of the coal seam, and permeability coefficient, etc. Then, based on the above basic data, constructing a physical similarity material model and a numerical model of the target coal seam. The physical similarity material model uses sand as aggregate, lime and gypsum as cementing materials, and citric acid as a retarder, and is made according to a certain geometric similarity ratio to the prototype; the numerical model is established using FLAC3D discrete element software. The model simulates the segmented mining process of the coal seam. By embedding stress boxes and setting displacement observation points in the rock strata, stress data is collected using a YJZA intelligent digital static resistance strain gauge, and displacement data is collected using an XJTUDP three-dimensional optical point measurement system. The entire process is recorded, showing the dynamic changes in time and space of the damage and fracture development of the overlying and floor strata as the working face advances. The recorded dynamic changes specifically include: the dynamic changes in the height and range of the caving zone, delamination fracture zone, and bending subsidence zone in the overlying strata as the working face advances; and the dynamic changes in the depth and range of the floor failure zone, intact strata zone, and confined water uplift zone in the floor strata as the working face advances.

[0039] In practical applications, the collection of basic data may also include mine pressure observation data and gas drainage historical data from adjacent mining areas or existing working faces in the same mining area, to assist in calibrating the boundary conditions and initial parameters of the model. In addition to FLAC3D, the numerical model can also be replaced by discrete element software such as UDEC and 3DEC, or finite element software such as ABAQUS.

[0040] Step S2: Based on the spatiotemporal evolution law, determine the optimal spatiotemporal arrangement parameters of the extraction boreholes so that the dynamic extraction windows of at least a portion of the extraction boreholes match the spatiotemporal evolution of the gas enrichment zone formed by mining.

[0041] Step S2 specifically includes: based on the dynamic changes in the height and range of the caving zone, delamination fracture zone, and bending subsidence zone obtained in step S1 as the working face advances, analyzing the spatiotemporal location of the migration channels and enrichment areas of depressurized gas in the mining-induced fracture field. The final borehole location of the first type of borehole used for extracting depressurized gas from adjacent upper layers is determined within the delamination fracture zone. Furthermore, based on the evolution characteristics of the "O"-shaped or annular fracture rings formed around the goaf, the final borehole location is further determined at the stratum height corresponding to the optimal gas extraction concentration and the distance from the working face throughout the entire process from fracture initiation to closure. Simultaneously, the final borehole location of the second type of borehole used for extracting depressurized gas from adjacent lower layers is determined within the effective depressurization area above the floor failure zone. By means of the above method, the effective extraction periods of the first and second type boreholes coincide in time with the period of large-scale desorption and outflow of gas during mining and decompression, and the final borehole location coincides in space with the gas-rich fracture development zone, thereby achieving spatiotemporal matching between the extraction window and the gas-rich zone.

[0042] In practical applications, the specific location and shape of the "O"-shaped ring or annular fracture ring can be determined by extracting a visual cloud map of the fracture development area from the post-processing module of the numerical simulation in step S1. For coal seams with extremely small interlayer spacing, the final position of the first type of borehole can be appropriately moved upward to avoid fracture penetration areas caused by excessively thin interlayer strata, thus preventing air leakage between the extraction borehole and the goaf.

[0043] Step S3: Perform gas extraction based on the optimal layout parameters.

[0044] Step S3 specifically includes: constructing extraction boreholes and performing gas extraction at the working face according to the optimal layout parameters determined in step S2. During the extraction process, multiple sets of test boreholes with different layout parameters can be constructed in advance, covering different strata heights and distances from the working face cut-in point. Throughout the entire mining impact cycle, a gas parameter measuring instrument in the gas extraction pipeline continuously monitors the gas extraction parameters of each test borehole, including gas concentration and flow rate. The strata height and distance parameters corresponding to the borehole with the highest extraction concentration and longest effective extraction period among all test boreholes are taken as the final verified optimal layout parameters, and the construction plan of subsequent extraction boreholes is adjusted accordingly to achieve closed-loop optimization. For the second type of boreholes for extraction from adjacent lower strata, a borehole imaging instrument is also used to inspect the borehole interior to directly observe the damage and fracture development of rock strata at different depths in the bottom plate, and to verify and correct the effective pressure relief zone boundary range determined in step S2.

[0045] In practical applications, the number and group of test boreholes can be flexibly adjusted according to the length of the working face and the complexity of geological conditions. Generally, each group of test boreholes consists of 3 to 5 boreholes at different strata heights. The gas parameter measuring instrument for the gas drainage pipeline can be a CJZ70 type gas drainage comprehensive parameter measuring instrument. During long-term drainage of the completed drainage boreholes, the gas parameters of each borehole can be periodically remeasured. When a continuous decrease in the drainage concentration is found, combined with the current advancement position of the working face and the fracture closure law revealed in step S1, it can be promptly determined whether the borehole has entered the fracture closure zone, thereby stopping the drainage of the borehole in a timely manner to avoid ineffective drainage and waste of resources.

[0046] The advantages of this embodiment are as follows: Step S1, employing a combination of physical similarity simulation and numerical simulation, accurately obtains the spatiotemporal evolution law of mining-induced fractures during close-range coal seam mining, providing a reliable theoretical basis for subsequent borehole layout; Step S2, by spatiotemporally matching the final borehole position with the characteristics of the delamination fracture zone, the effective pressure relief area of ​​the floor, and the "O" ring, fundamentally overcomes the spatiotemporal misalignment problem between traditional static borehole layout and dynamic fracture development; Step S3, by using multiple sets of experimental borehole monitoring and closed-loop optimization adjustment, enables the final extraction scheme to accurately capture the spatiotemporal window of pressure relief gas enrichment, significantly improving gas extraction concentration and effective extraction cycle, greatly enhancing the gas extraction efficiency of close-range coal seam groups, effectively reducing the risk of gas exceeding limits at the working face, and ensuring safe mine production. Furthermore, the method of this invention is not dependent on the geological conditions of a specific mining area and can be widely applied to gas extraction projects under various close-range, low-permeability, high-gas coal seam group mining conditions.

[0047] Example 2

[0048] A method for precise extraction of coal seam gas in close proximity based on the spatiotemporal evolution of mining-induced fractures, the method comprising the following steps:

[0049] Step S1: Obtain the spatiotemporal evolution of mining-induced fractures during close-range coal seam mining.

[0050] Step S1 specifically includes: First, collecting geological data of the target working face area, including the occurrence state of coal and rock strata, physical and mechanical parameters of each stratum, gas content of the coal seam, and permeability coefficient, etc. Then, based on the above basic data, a three-dimensional numerical model of the target coal seam is established using FLAC3D discrete element software. In the numerical model, the Mohr-Coulomb model is used for the block constitutive model, and the Coulomb Slip Model is used for the joint constitutive model to accurately simulate the mechanical response of the strata under mining operations. The coal seam is excavated segment by segment in the model to simulate the gradual advancement of the working face, and monitoring and recording points are set at different strata heights of the roof and floor strata to record stress and displacement changes at each monitoring point in real time. Through dynamic analysis of the data from each monitoring point as the working face advances, the dynamic changes in the height and range of the caving zone, delamination fracture zone, and bending subsidence zone in the overlying strata as the working face advances are obtained, as well as the dynamic changes in the depth and range of the floor failure zone, intact strata zone, and confined water conduction zone in the floor strata as the working face advances.

[0051] In practical applications, the collection of basic data can also refer to geological data and mine pressure observation data from adjacent mining areas or existing working faces in the same mining area, which are used to calibrate and verify the key parameters of the numerical model. In addition to FLAC3D, discrete element software such as UDEC and 3DEC can also be used as alternatives for numerical simulation. To further improve the reliability of the obtained patterns, after the numerical simulation is completed, a small number of verification boreholes can be drilled on-site at typical profile locations. A borehole imaging instrument can be used to inspect the top and bottom rock strata, and the actual fracture development morphology observed on-site can be compared and verified with the numerical simulation results.

[0052] Step S2: Based on the spatiotemporal evolution law, determine the optimal spatiotemporal arrangement parameters of the extraction boreholes so that the dynamic extraction windows of at least a portion of the extraction boreholes match the spatiotemporal evolution of the gas enrichment zone formed by mining.

[0053] Step S2 specifically includes: based on the dynamic changes in the height and range of the caving zone, delamination fracture zone, and bending subsidence zone obtained through numerical simulation in step S1 as the working face advances, and combined with the stress and displacement data of each monitoring point in the numerical model, analyzing the formation timing and spatial location of gas migration channels during the mining and depressurization process. The final borehole location of the first type of borehole used for extracting depressurized gas from adjacent layers is determined to be within the delamination fracture zone. Based on the evolution characteristics of the "O"-shaped or annular fracture rings formed around the goaf, the final borehole location is determined in terms of stratigraphic height to be in the middle and upper part of the delamination fracture zone, and in terms of distance from the working face to be within the interval where the fractures are fully developed and have not yet closed, so that the effective extraction period of the borehole coincides with the period of large-scale accumulation of depressurized gas. At the same time, the final position of the second type of borehole used for extracting gas from adjacent layers will be determined within the effective pressure relief area above the floor failure zone, so that the final position of the borehole avoids the area where a through-crack has formed in the floor failure zone, and prevents air leakage from the goaf during the extraction process.

[0054] In practical applications, the specific stratum height at the end of the first type of borehole can be determined based on the stratum with the highest fracture density in the fracture development zone cloud map output by numerical simulation. For the second type of borehole used for extraction from adjacent lower strata, a safety distance of not less than 2m should be maintained between its end point and the bottom boundary of the floor failure zone to ensure the sealing of the extraction borehole and the extraction effect.

[0055] Step S3: Perform gas extraction based on the optimal layout parameters.

[0056] Step S3 specifically includes: constructing extraction boreholes and performing gas extraction at the working face according to the optimal layout parameters determined in step S2. During the extraction process, multiple sets of test boreholes with different layout parameters are constructed in advance. These test boreholes cover different strata heights and distances from the working face cut-in point. Throughout the entire mining impact cycle, a gas parameter measuring instrument in the gas extraction pipeline continuously monitors the gas extraction parameters of each test borehole, including gas concentration and flow rate. The strata height and distance parameters corresponding to the borehole with the highest extraction concentration and longest effective extraction period are taken as the final verified optimal layout parameters. Based on this, the construction plan for subsequent extraction boreholes is adjusted to achieve closed-loop optimization. For the second type of boreholes extracting from adjacent lower strata, a borehole imaging instrument is also used to inspect the borehole interior to directly observe the damage and fracture development of rock strata at different depths in the floor, verifying and correcting the effective pressure relief zone boundary range determined in step S2.

[0057] In practical applications, the number of test boreholes is generally set to 2 to 3 groups, with each group containing 3 to 4 boreholes at different strata heights, covering the main strata variation range with a smaller amount of drilling work. When the monitoring results of the test boreholes show that the extraction effect of a borehole at a certain stratum height is significantly better than that of other strata, the final position of all subsequent extraction boreholes can be uniformly adjusted to that stratum height to achieve batch and precise extraction.

[0058] The advantages of this embodiment are: It utilizes numerical simulation to obtain the spatiotemporal evolution of mining-induced fractures, eliminating the cumbersome processes of material preparation, molding, and drying, significantly shortening the work cycle in the initial pattern acquisition phase and reducing experimental material and labor costs. Furthermore, by supplementing the numerical simulation with a small number of field verification boreholes, the reliability of the pattern acquisition is ensured while avoiding the need for large-scale physical simulation experiments. This embodiment is particularly suitable for mines with relatively clear geological conditions and abundant historical mining data available for model calibration, achieving the same precise extraction effect as the previous embodiment at a lower implementation cost.

[0059] Example 3

[0060] A near-field coal seam gas precision extraction system based on the spatiotemporal evolution of mining-induced fractures includes:

[0061] Module M1 is used to obtain the spatiotemporal evolution of mining-induced fractures during close-range coal seam mining.

[0062] Parameter module M2 determines the optimal arrangement parameters of the extraction boreholes in time and space according to the spatiotemporal evolution law, wherein the optimal arrangement parameters make the dynamic extraction window of at least a portion of the extraction boreholes match the spatiotemporal evolution of the gas enrichment zone formed by mining.

[0063] Module M3 is used to perform gas extraction based on the optimal layout parameters.

[0064] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for precise extraction of gas from nearby coal seams based on the spatiotemporal evolution of mining-induced fractures, characterized in that, include: To obtain the spatiotemporal evolution of mining-induced fractures during close-range coal seam mining; Based on the spatiotemporal evolution law, the optimal arrangement parameters of the extraction boreholes in spatiotemporal space are determined, wherein the optimal arrangement parameters make the dynamic extraction window of at least a portion of the extraction boreholes match the spatiotemporal evolution of the gas enrichment zone formed by mining. Gas extraction is performed based on the optimal layout parameters.

2. The method for precise extraction of coal seam gas from a nearby coal seam based on the spatiotemporal evolution of mining-induced fractures according to claim 1, characterized in that, The acquisition of the spatiotemporal evolution law of the mining-induced fracture specifically includes: Construct a physically similar material model and / or a numerical model of the target coal seam; Simulate the coal seam mining process and record the dynamic changes in time and space of the damage and fracture development of the overlying and floor strata as the working face advances; The dynamic changes of the overlying rock strata include the dynamic changes in the height and range of the caving zone, the delamination fracture zone, and the bending subsidence zone as the working face advances; the dynamic changes of the bottom rock strata include the dynamic changes in the bottom failure zone, the intact rock strata zone, and the confined water uplift zone as the working face advances in depth and range.

3. The method for precise extraction of coal seam gas from a nearby location based on the spatiotemporal evolution of mining-induced fractures according to claim 2, characterized in that, The determination of the optimal layout parameters of the extraction boreholes based on the spatiotemporal evolution law specifically includes: The final location of at least the first type of borehole used for extracting depressurized gas from the adjacent upper layer is determined within the delamination fracture zone; The final location of at least the second type of borehole used for extracting depressurized gas from the adjacent layer is determined within the effective depressurization area above the base plate failure zone.

4. The method for precise extraction of coal seam gas from a nearby location based on the spatiotemporal evolution of mining-induced fractures according to claim 2, characterized in that, The physical similarity material model is made with sand as aggregate, lime and gypsum as cementing materials, and citric acid as a retarder; the numerical model is a FLAC3D discrete element model.

5. The method for precise extraction of coal seam gas from a nearby location based on the spatiotemporal evolution of mining-induced fractures according to claim 3, characterized in that, The final location of the first type of borehole is determined based on the evolution characteristics of the "O"-shaped ring or annular fracture ring formed around the goaf. During the entire process from fracture initiation to closure, the location is determined by the stratum height corresponding to the optimal gas extraction concentration and the distance from the working face.

6. The method for precise extraction of coal seam gas from a nearby location based on the spatiotemporal evolution of mining-induced fractures according to claim 3, characterized in that, A borehole imaging instrument was used to inspect the second type of borehole to directly observe the damage and fracture development of rock strata at different depths of the base plate, in order to verify and correct the boundary range of the effective pressure relief area.

7. The method for precise extraction of coal seam gas from a nearby location based on the spatiotemporal evolution of mining-induced fractures according to claim 5, characterized in that, Also includes: Multiple sets of test boreholes with different layout parameters were constructed, and the multiple sets of test boreholes covered different strata heights and distances from the working face cut-out. Continuously monitor the gas extraction parameters of each test borehole throughout the entire mining impact cycle; The stratigraphic position and distance corresponding to the borehole with the highest extraction concentration and the longest effective extraction period among the test boreholes are used as the basis for determining the optimal layout parameters.

8. The method for precise extraction of coal seam gas from a nearby location based on the spatiotemporal evolution of mining-induced fractures according to claim 7, characterized in that, The gas extraction parameters include gas concentration and flow rate; the continuous monitoring is performed using a gas parameter measuring instrument for the gas extraction pipeline.

9. The method for precise extraction of coal seam gas from a nearby location based on the spatiotemporal evolution of mining-induced fractures according to claim 1, characterized in that, The method is applied to mining conditions of closely spaced, low-permeability, and high-gas coal seams, and is used to solve the problem of low gas extraction efficiency caused by the superimposed mining stress of multiple coal seams.

10. A near-distance coal seam gas precision extraction system based on the spatiotemporal evolution of mining-induced fractures, characterized in that, The near-distance coal seam gas precision extraction method based on the spatiotemporal evolution of mining-induced fractures as described in any one of claims 1 to 9 includes: The acquisition module acquires the spatiotemporal evolution of mining-induced fractures during close-range coal seam mining. The parameter module determines the optimal arrangement parameters of the extraction boreholes in time and space according to the spatiotemporal evolution law, wherein the optimal arrangement parameters make the dynamic extraction window of at least a portion of the extraction boreholes match the spatiotemporal evolution of the gas enrichment zone formed by mining. The module is used to perform gas extraction based on the optimal layout parameters.

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