A spontaneous combustion coal seam goaf gas emission prediction system and method

Abstract

The application discloses a kind of spontaneous combustion coal seam goaf gas emission prediction system and method, it is related to energy exploitation technical field, its technical scheme key points are: the prediction method of the present application reveals the coupling mechanism of spontaneous combustion coal seam mining overburden fissure evolution and gas migration, and spontaneous combustion coal seam gas emission law, spontaneous combustion coal seam mining spontaneous combustion law, spontaneous combustion coal seam goaf gas migration and coal oxidation coupling disaster-causing mechanism.The prediction of the gas emission amount of working face is realized, and the gas emission amount is predicted by selecting appropriate prediction method, specifically by testing gas basic parameters on site, analyzing gas emission source and the like.The determination of spontaneous combustion dangerous area of high-gas coal seam is determined by field testing, numerical simulation and theoretical analysis, and the gas distribution law of goaf under the condition of no extraction is studied, the spontaneous combustion dangerous area of coal seam goaf is divided, and the spontaneous combustion dangerous area is determined.

Description

Technical Field

[0001] This invention relates to the field of energy extraction technology, and more specifically, to a system and method for predicting gas outbursts in goaf areas of spontaneously combusting coal seams. Background Technology

[0002] Coal is the "ballast" for my country's energy security and stable supply, holding a vital strategic position in the national economy. With increasing coal mining depth, high gas levels and high ground temperatures have exacerbated the problem of combined gas and spontaneous combustion hazards in deep coal mines. In recent years, gas explosions caused by spontaneous combustion of coal during mining have occurred frequently. Gas emissions from abandoned coal seams and adjacent layers in goaf areas account for more than 50% of the total gas emissions in the mine. Due to ventilation leaks at the working face, over 95% of spontaneous combustion occurs in goaf areas that are inaccessible or out of sight to personnel. Therefore, spontaneous combustion of coal is the primary ignition source for gas explosions in goaf areas, making goaf areas a significant location for combined coal combustion and gas hazards.

[0003] Xinjiang's coal resources have distinct characteristics. From the perspective of coalification degree, the regional coal quality exhibits a "pyramid" distribution pattern. Most coal seams in Xinjiang's mining areas are shallowly buried, prone to spontaneous combustion, and have severe air leakage, resulting in high porosity and extensive air leakage in the goaf. This allows for a continuous supply of oxygen in the goaf, making the oxygen concentration sufficient to trigger coupled disasters.

[0004] Significant progress has been made in existing research on the causative mechanisms and prevention technologies of combined coal spontaneous combustion and gas explosion disasters in goaf areas. However, the complex coupling relationship between coal spontaneous combustion and gas in goaf areas makes it difficult to accurately reveal the dynamic evolution characteristics under complex environmental conditions. This also limits the effective determination of the location and development degree of coupled disasters. Although some scholars have established relevant numerical models and delineated the danger zones of combined disasters in goaf areas, the effectiveness of these models lacks reasonable verification. Therefore, exploring and analyzing the coupled disaster-causing mechanism of gas migration and coal oxidation in goaf areas of spontaneously combusting coal seams, combined with the actual conditions of the goaf, is of great practical significance for the safe production of coal mines. Summary of the Invention

[0005] The purpose of this invention is to provide a gas outburst prediction system and method for spontaneously combusting coal seams in goaf areas, so as to solve the technical problems existing in the prior art.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution: a system and method for predicting gas outbursts in goaf areas of spontaneously combusting coal seams, wherein the prediction method includes the following steps:

[0007] S1. Gas emission patterns and emission volume prediction in self-igniting coal seam mining faces;

[0008] S2. Coupling pattern of mining-induced overburden fracture evolution, mine pressure distribution and gas migration;

[0009] S3. Spontaneous ignition patterns and early warning methods in the mining of self-igniting coal seams;

[0010] S4. Determination of the degree of spontaneous combustion hazard and the danger zone in the goaf of the spontaneously combusting coal seam.

[0011] The present invention is further configured such that the specific operation of S1 is as follows:

[0012] This study investigates the occurrence patterns of coal seam gas, analyzes the relationship between gas emission and working face ventilation volume, daily advance rate, advance speed, daily output, and geological structure, and studies the gas emission patterns of the working face. Taking into account influencing factors including time, space, and coal seam occurrence conditions, a gas emission prediction model for mining faces is established.

[0013] The present invention is further configured such that the specific operation of S2 is as follows:

[0014] (1) Using methods including theoretical analysis, numerical simulation and engineering practice, we analyze the evolution law of overburden fractures after mining of self-igniting coal seams, the distribution law of mine pressure in the mining area and the distribution law of gas migration and storage in the goaf, and determine the gas enrichment area in the mining area, so as to provide a theoretical basis for depressurized gas extraction.

[0015] (2) Based on the physical simulation test of the evolution law of overburden fractures caused by mining, study the spatiotemporal variation law of stress field and deformation field in the mining area, and study the evolution law of overburden fractures caused by mining after mining of Jurassic coal seam;

[0016] (3) Analyze the relationship between coal body fracture evolution and gas seepage, study the mechanism of action of mining fracture field on gas flow, the flow law of gas in mining coal and rock fracture field, determine the gas enrichment area in the mining area, and provide a theoretical basis for depressurized gas extraction.

[0017] The present invention is further configured such that the specific operation of S3 is as follows:

[0018] (1) Test the thermal properties of coal under different conditions, including thermal conductivity, oxygen diffusion coefficient, permeability, specific heat capacity and porosity;

[0019] (2) Determine the exothermic intensity of coal oxidation and analyze the influence of factors including particle size, temperature and degree of coal metamorphism;

[0020] (3) Analyze the oxygen consumption rate, heat release intensity and gas generation rate of coal seams at different temperatures, and study the conditions, influencing factors and characteristic parameters of spontaneous combustion of coal seams;

[0021] (4) Establish a natural fire early warning indicator system, study multi-source information fusion early warning methods, and realize early warning of natural fire.

[0022] The present invention is further configured such that the specific operation of S4 is as follows:

[0023] (1) Measure and analyze the relevant parameters and their variation laws during the entire process of spontaneous combustion of coal, and study the early characteristic parameters of spontaneous combustion of coal seams;

[0024] (2) Establish a seepage model for the goaf area, divide the heat dissipation zone, oxidation zone and asphyxiation zone of the goaf area of ​​high gas coal seam, and determine the dangerous area of ​​spontaneous combustion of high gas coal seam.

[0025] (3) Study the distribution patterns of oxygen concentration field and air leakage intensity field in the goaf, analyze the influence of boundary condition changes including gas extraction method and extraction intensity on oxygen concentration field and air leakage intensity field, and thus study the influence of boundary conditions including gas extraction method and extraction intensity on coal spontaneous combustion hazard zone in goaf.

[0026] The present invention further provides a gas emission prediction system for goaf areas of spontaneously combusting coal seams. The system executes the above-mentioned method to predict the amount of gas emission in goaf areas of spontaneously combusting coal seams and to determine the spontaneous combustion hazard zone of high-gas coal seams.

[0027] In summary, the present invention has the following beneficial effects:

[0028] The prediction method of this invention reveals the coupling mechanism between the evolution of overlying rock fissures and gas migration in spontaneously combusting coal seams, as well as the gas emission law of spontaneously combusting coal seams, the spontaneous combustion law of spontaneously combusting coal seams, and the disaster-causing mechanism of gas migration and coal oxidation in goaf areas of spontaneously combusting coal seams.

[0029] To predict the amount of gas emitted from the working face, the method involves testing basic gas parameters on-site, analyzing the sources of gas emission, and selecting an appropriate prediction method.

[0030] In addition, the study investigates the spontaneous combustion hazard zone of high-gas coal seams by conducting field tests, numerical simulations, and theoretical analyses. Under conditions of no extraction, the study explores the distribution pattern of gas in the goaf, delineates the spontaneous combustion hazard zone of the coal seam goaf, and determines the spontaneous combustion hazard zone. Attached Figure Description

[0031] Figure 1 This is a technical roadmap for the research and prediction method in the embodiments of the present invention;

[0032] Figure 2 This invention relates to the numerical model mesh generation and gas concentration distribution under U-shaped ventilation in this embodiment.

[0033] Figure 3This is a schematic diagram of the coal spontaneous combustion experimental platform in an embodiment of the present invention.

[0034] Figure 4 This is a diagram showing the oxygen concentration, air leakage intensity, floating coal thickness, and spontaneous combustion hazard zone division in the goaf of this invention. Detailed Implementation

[0035] The following is in conjunction with the appendix Figure 1-4 The present invention will be described in further detail below.

[0036] Example: A method for predicting gas outbursts in goaf areas of spontaneously combusting coal seams

[0037] 1. Gas emission patterns and prediction in goaf areas of spontaneously combusting coal seams

[0038] (1) Select Kuqa Yushuling Coal Mine as a typical mine, and analyze the relevant geological parameters such as gas pressure, gas content and coal seam permeability coefficient of spontaneously combusting coal seam through on-site investigation or actual measurement, and analyze the gas occurrence law of spontaneously combusting coal seam.

[0039] (2) Study on the gas emission pattern in the goaf of spontaneously combusting coal seam. Based on the survey and the gas occurrence pattern of the test working face of spontaneously combusting coal seam, the gas emission and mine pressure of the test working face were observed. The main factors included the daily advance of the working face, the initial pressure step distance, the periodic pressure step distance, the operation procedure, the air volume, the advance speed, the gas emission, and the recovery rate. The relationship between the gas emission and the influencing factors such as the mine pressure, operation procedure, air volume, output, advance, and recovery rate was analyzed to study the gas emission pattern of the working face of spontaneously combusting coal seam.

[0040] (3) Dynamic prediction of gas emission in goaf of spontaneously combusting coal seam. Based on previous observation data and theoretical analysis, the dynamic prediction of gas emission in mining faces of high-gas, spontaneously combusting coal seams is studied by applying grey theory or neural network methods.

[0041] 2. Coupling mechanism of mining-induced overburden fracture evolution, mine pressure distribution and gas migration

[0042] After coal seam mining, the overlying strata of the goaf will form a dynamically changing fracture zone, and the concentration distribution of gas in different areas of the mining fracture zone is also different. The distribution of fractures in the goaf, the distribution of mine pressure and the gas migration pattern are closely related to depressurization gas drainage and other projects, and are one of the main bases for the layout parameters of depressurization gas drainage.

[0043] (1) On-site observation and numerical simulation study of gas flow field distribution in goaf. Monitoring tubes were installed in the goaf to study the distribution of gas concentrations under gas extraction conditions; FLUENT software was used to calculate and analyze the distribution of gas and oxygen concentrations in the goaf under conditions of air leakage and gas extraction (e.g., Figure 2 (As shown).

[0044] (2) Based on field observation and numerical simulation analysis, theoretical analysis is conducted on the surrounding rock activity law, coal seam permeability evolution law and gas migration law under mine pressure, and reasonable gas extraction volume, extraction time and extraction negative pressure parameters are determined, and gas extraction technology suitable for goaf mining and adjacent layers of self-igniting coal seam is optimized and developed.

[0045] 3. Spontaneous Ignition Patterns and Early Warning Methods in Mining Jurassic Self-Ignition Coal Seams

[0046] (1) Testing of thermal properties of Jurassic coal seams. The laboratory used a coal permeability coefficient measuring device, a double-volume diffusion coefficient measuring device, a thermal conductivity measuring device, and a porosity measuring instrument to measure the thermal properties of Jurassic coal seams, such as thermal conductivity, specific heat capacity, oxygen diffusion coefficient, air permeability coefficient, and porosity.

[0047] (2) Experimental study on the spontaneous combustion law of Jurassic coal seams. By simulating the spontaneous combustion parameters of loose coal in contact with oxygen during the natural heating process through a coal spontaneous combustion test bench, such as spontaneous combustion period, oxygen consumption rate, gas generation rate, heat release intensity, and limiting parameters such as floating coal thickness, oxygen concentration, particle size, and air leakage intensity, the control factors and gas indicators of coal seam spontaneous combustion were analyzed. Through coal programmed heating oxidation experiments, the oxidation process of coal under different particle size conditions was measured, the relationship between coal particle size and coal spontaneous combustion was analyzed, and the spontaneous combustion law of Jurassic coal seams was studied, laying the foundation for coal spontaneous combustion prediction.

[0048] (3) Research on multi-source information fusion early warning method for spontaneous coal combustion. Based on experimental and field observation data, a multi-source information fusion early warning model for spontaneous coal combustion is established based on information fusion methods such as fuzzy clustering and pattern recognition. A multi-source information fusion monitoring and early warning method for spontaneous coal combustion is studied, which integrates diverse spontaneous coal combustion characteristic information such as temperature and gas from different monitoring systems and monitoring locations to determine the degree of spontaneous coal combustion and the location of ignition. The monitoring process, processing method and discrimination mechanism of spontaneous coal combustion characteristic information parameters are also studied.

[0049] 4. Determination of the degree of spontaneous combustion hazard and the danger zone in the goaf of spontaneously combusting coal seams.

[0050] (1) Gas distribution pattern and qualitative and quantitative test in the goaf. A bundled tube monitoring system was set up in the underground goaf to measure the oxygen concentration distribution at different locations in the goaf, analyze the gas seepage pattern in the goaf, calculate the leakage intensity contour, and analyze the leakage intensity field.

[0051] (2) Determination and prediction of spontaneous combustion hazard zones in the goaf of the working face. Based on the actual mining conditions and spontaneous combustion characteristics of the coal seam in the test working face, and considering influencing factors such as gas drainage, appropriate monitoring methods were selected and reasonable point layout was determined. By analyzing the index gases in the goaf during coal seam mining, parameters such as the thickness of floating coal, air leakage velocity, oxygen concentration, and particle size distribution under actual conditions were determined, and spontaneous combustion hazard zones in different coal seam goafs were divided (e.g., Figure 4 As shown in the figure, the possibility of spontaneous combustion and the time of spontaneous ignition are determined based on the progress of the working face.

[0052] (3) Impact of gas extraction on the degree and area of ​​spontaneous combustion hazard in the goaf. By comparing the on-site gas extraction parameters and the gas monitoring data in the goaf, the parameter relationship between extraction and the degree and area of ​​spontaneous combustion hazard in the goaf was determined. Fluent fluid calculation software was used to simulate the degree and area of ​​hazard in the goaf under extraction conditions. By setting different extraction parameters (extraction pressure, extraction flow rate), the changes in the concentration of oxygen, gas, carbon monoxide and other gases and air pressure in the goaf were simulated, and the relationship between gas extraction and spontaneous combustion hazard area was analyzed.

[0053] Example 2: A gas outburst prediction system for goaf areas of spontaneously combusting coal seams

[0054] Based on the method described in Example 1, a corresponding prediction system is established and mounted on a chip or computer storage device to predict the amount of gas emission in the goaf of spontaneously combusting coal seams and to determine the risk zone of spontaneous combustion in high-gas coal seams.

[0055] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A method for predicting gas outbursts in goaf areas of spontaneously combusting coal seams, characterized by: The prediction method includes the following steps: S1. Gas emission patterns and emission volume prediction in self-igniting coal seam mining faces; S2. Coupling pattern of mining-induced overburden fracture evolution, mine pressure distribution and gas migration; S3. Spontaneous ignition patterns and early warning methods in the mining of self-igniting coal seams; S4. Determination of the degree of spontaneous combustion hazard and the danger zone in the goaf of the spontaneously combusting coal seam.

2. The method for predicting gas outburst in goaf areas of spontaneously combusting coal seams according to claim 1, characterized in that: The specific operation of S1 is as follows: This study investigates the occurrence patterns of coal seam gas, analyzes the relationship between gas emission and working face ventilation volume, daily advance rate, advance speed, daily output, and geological structure, and studies the gas emission patterns of the working face. Taking into account influencing factors including time, space, and coal seam occurrence conditions, a gas emission prediction model for mining faces is established.

3. The method for predicting gas outburst in goaf areas of spontaneously combusting coal seams according to claim 1, characterized in that: The specific operation of S2 is as follows: (1) Using methods including theoretical analysis, numerical simulation and engineering practice, we analyze the evolution law of overburden fractures after mining of self-igniting coal seams, the distribution law of mine pressure in the mining area and the distribution law of gas migration and storage in the goaf, and determine the gas enrichment area in the mining area, so as to provide a theoretical basis for depressurized gas extraction. (2) Based on the physical simulation test of the evolution law of overburden fractures caused by mining, study the spatiotemporal variation law of stress field and deformation field in the mining area, and study the evolution law of overburden fractures caused by mining after mining of Jurassic coal seam; (3) Analyze the relationship between coal body fracture evolution and gas seepage, study the mechanism of action of mining fracture field on gas flow, the flow law of gas in mining coal and rock fracture field, determine the gas enrichment area in the mining area, and provide a theoretical basis for depressurized gas extraction.

4. The method for predicting gas outburst in goaf areas of spontaneously combusting coal seams according to claim 1, characterized in that: The specific operation of S3 is as follows: (1) Test the thermal properties of coal under different conditions, including thermal conductivity, oxygen diffusion coefficient, permeability, specific heat capacity and porosity; (2) Determine the exothermic intensity of coal oxidation and analyze the influence of factors including particle size, temperature and degree of coal metamorphism; (3) Analyze the oxygen consumption rate, heat release intensity and gas generation rate of coal seams at different temperatures, and study the conditions, influencing factors and characteristic parameters of spontaneous combustion of coal seams; (4) Establish a natural fire early warning indicator system, study multi-source information fusion early warning methods, and realize early warning of natural fire.

5. The method for predicting gas outbursts in goaf areas of spontaneously combusting coal seams according to claim 1, characterized in that: The specific operation of S4 is as follows: (1) Measure and analyze the relevant parameters and their variation laws during the entire process of spontaneous combustion of coal, and study the early characteristic parameters of spontaneous combustion of coal seams; (2) Establish a seepage model for the goaf area, divide the heat dissipation zone, oxidation zone and asphyxiation zone of the goaf area of ​​high gas coal seam, and determine the dangerous area of ​​spontaneous combustion of high gas coal seam. (3) Study the distribution patterns of oxygen concentration field and air leakage intensity field in the goaf, analyze the influence of boundary condition changes including gas extraction method and extraction intensity on oxygen concentration field and air leakage intensity field, and thus study the influence of boundary conditions including gas extraction method and extraction intensity on coal spontaneous combustion hazard zone in goaf.

6. A gas outburst prediction system for goaf areas of spontaneously combusting coal seams, characterized in that: The system executes the method described in any one of claims 1-5 to predict the gas emission in the goaf of a spontaneously combusting coal seam and to determine the spontaneous combustion hazard zone of a high-gas coal seam.

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