Accurate coal and gas outburst forecasting method based on gas geology study and judgment

Abstract

The invention belongs to the technical field of prevention and treatment of coal and gas outburst disasters in coal mines, and particularly relates to an accurate coal and gas outburst forecasting method based on gas geology study and judgment. Comprising the steps that S100, coal and gas forecasting is carried out according to different conditions, specifically, 1) gas outburst forecasting is carried out before design, well building and mine extension; 2) uncovering a rock reservoir and forecasting gas outburst before coal uncovering; 3) forecasting surrounding rock gas outburst; the coal and gas outburst forecasting method comprises the steps of (1) coal seam gas outburst forecasting, (2) adjacent coal seam gas outburst forecasting, (3) adjacent coal seam gas outburst forecasting, (4) adjacent coal seam gas outburst forecasting, (5) geological abnormal area gas outburst forecasting of the coal seam, (6) coal and gas outburst forecasting of two or more gas geological high-gas potential areas of a coal seam group, (S200) outburst forecasting verification and measure taking and (S300) outburst forecasting relieving.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal mine coal and gas outburst disaster prevention and control, and specifically is an accurate coal and gas outburst prediction method based on gas geological research and judgment. Background Art

[0002] Coal and gas outburst is a gas dynamic phenomenon in mines caused by mining disturbance of gas geological bodies in coal-bearing strata. It is one of the major disasters in underground coal mine production. Experts and scholars at home and abroad have carried out a large number of physical simulation tests, but the mechanism of coal and gas outburst is still at the stage of four hypotheses. The technical basis for preventing and controlling coal and gas outburst in my country is still the comprehensive action hypothesis.

[0003] The applicant's engineering and technical personnel learned from the practice of mining projects and extended the knowledge from the coal seam to coal-bearing strata. They proposed the theory of gas geological zoning and explained the mechanism of coal and gas outburst as follows: during the mining activities in coal-bearing strata, the gas in the coal body near the tunneling and mining working face diffuses and seeps into the mining area, making the coal body in the mining area a low-potential area; the mining disturbance destroys the closure of the geological body where the elastic energy of gas accumulates, and the gas in the high-potential area spontaneously enters the coal body in the low-potential area, squeezing, splitting, destroying and crushing the coal body in the low-potential area, causing coal and gas to protrude into the mining space.

[0004] On this basis, the applicant's engineering and technical personnel proposed the classification of coal and gas outburst types and the distribution of outburst areas, that is, coal and gas outburst types are divided into surrounding rock gas outbursts, adjacent coal seam gas outbursts and gas outbursts in geological anomaly areas of the coal seam. Coal-bearing strata deposits can be divided into source-cap deposits and source-reservoir-cap deposits, with source-reservoir-cap deposits being the main type. Coal seams generate and store gas, which is self-generation and self-storage; under the conditions of source-reservoir-cap deposits, coal seams generate gas and migrate upward to the rock reservoir, which is lower generation and upper storage. Coal seam gas and rock reservoir gas can both cause coal and gas outbursts. This breaks the traditional concept of the four hypotheses that only coal seam gas causes coal and gas outbursts, and makes technical innovations in theory.

[0005] Under the guidance of the new theory "gas geological zoning theory", it is very necessary to predict coal and gas outbursts through gas geological research and judgment based on the classification of coal and gas outburst mine types, regional distribution, determination of gas geological high potential areas, and prediction of surrounding rock gas outbursts. Summary of the invention

[0006] In order to solve the problem of coal and gas outburst prediction based on gas geological judgment, the present invention provides an accurate coal and gas outburst prediction method based on gas geological judgment.

[0007] The present invention adopts the following technical scheme: an accurate coal and gas outburst prediction method based on gas geological analysis, comprising: S100: Coal and gas forecasts are carried out according to different situations, including: 1) Gas outburst prediction before design, mine construction and mine extension; 2) Forecast of gas outburst before uncovering rock reservoirs or coal; 3) Prediction of gas outburst in surrounding rock; 4) Forecast of gas outburst near coal seams; 5) Forecast of gas outburst in the geological anomaly area of ​​the coal seam; 6) Forecast of coal and gas outbursts in two or more gas geological high potential areas of coal seam groups; S200: Highlight forecast verification and take measures; S300: cancelling the prominent forecast.

[0008] In some embodiments, in step S100, gas outburst forecasting before design, well construction, and mine extension is performed when the following situations occur: 1) When the gas geological map of the mine is abnormal, a gas outburst forecast is carried out, where the gas geological map abnormalities of the mine include: ① The coal seam has no outcrop, that is, the coal seam does not come out to the surface, there is no escape channel for coal seam gas, and the gas content per ton of coal is less than 10m 3 / t; ② In the same mine, the gas per ton of coal isoline in the deep coal seam is lower than the gas per ton of coal isoline in the shallow coal seam; ③ In the same coal seam, the gas-per-ton contour line is abnormal, and the gas-per-ton contour line in the deep coal seam is lower than that in the shallow coal seam; or in the same coal seam, the gas-per-ton contour line map is chaotic and disordered, which is contrary to the influence of burial depth, structure, space and hydrogeology on coal seam gas; 2) When gas dynamic phenomena or coal and gas outbursts occur near infrastructure and production mines, gas outburst forecasts are carried out, including the following situations: ① Gas dynamic phenomena or outbursts occur continuously in the same coal seam tunnel; ② The location where gas dynamic phenomenon or outburst occurs in the coal seam tunnel, and the gas dynamic phenomenon or outburst occurs again during tunnel maintenance; ③ The amount of gas ejected during the outburst is equal to or greater than twice the amount of gas contained in the outburst coal.

[0009] In some embodiments, in step S100, a gas outburst forecast is performed before uncovering a rock reservoir or coal when the following situations occur: 1) When there is no coal-bearing geological outcrop to expose the reservoir: The upper part of the coal seam is a rock reservoir. When the water pressure in the rock reservoir is ≥0.5MPa, gas outburst prediction is carried out 10m before the minimum normal distance from the coal and rock reservoir. 2) When uncovering coal seams with outcrops: The gas pressure at the coal mining point is calculated as follows: P=g p (H-H0)+P0 Where: P: predicted gas pressure at depth H in the methane zone, MPa; g p : Gas pressure gradient; H: See the elevation of the coal point and predict the depth value in the methane zone; H0: depth of upper boundary of methane zone; P0: gas pressure at the upper boundary of the methane zone, generally 0.2MPa; When P is calculated to be ≥ 0.5MPa, gas outburst prediction is carried out 10m before the minimum normal distance from the coal and rock reservoirs; 3) When uncovering coal in a seam without outcropping: When the water pressure of the rock reservoir is ≥0.5MPa, gas outburst prediction is carried out at the minimum normal distance of 10m from the coal and rock reservoir; 4) When gas outbursts from the underlying coal seam: The underlying coal seam is a raw cap stratum, and the coal seam gas pressure P=g p (H-H0)+P0; When P≥0.5MPa and there is a danger of gas outburst after coal is uncovered, gas outburst prediction shall be carried out 10m before the minimum normal distance from the coal and rock reservoirs; The underlying coal seam is a source-reservoir cap stratum, and the gas pressure of the rock reservoir is equal to the water pressure; When the water pressure is ≥0.5MPa, there is a danger of gas outburst after coal is uncovered, and gas outburst forecast should be carried out before the minimum normal distance of 10m from the coal and rock reservoir.

[0010] In some embodiments, in step S100, the prediction of gas outburst in surrounding rock includes: 1) Forecast of gas outburst in the surrounding rock of coal seam roof. Forecast of gas outburst in the surrounding rock of coal seam roof includes: ① Gas outburst prediction at excavation working face: When the distance between the rock reservoir and the coal seam is less than 10m, the distance between the rock reservoir floor and the coal seam roof is less than 10m, the gas pressure of the rock reservoir is ≥0.5MPa or the outburst risk index is ≥0.05MPa / m, the surrounding rock gas will outburst along the faults and cracks of the weak surface of the rock formation, and gas outburst prediction should be carried out before excavation; When the rock reservoir is located in the caving zone, the distance between the rock reservoir and the coal seam is ≥10m, but in the caving zone, the gas pressure of the rock reservoir is ≥0.5MPa or the outburst hazard index is ≥0.05MPa / m, and the surrounding rock gas will outburst along the fault zone. Gas outburst prediction should be carried out before excavation; ②Prediction of gas outburst in the surrounding rock of the mining face roof: When the surrounding rock thickness is less than 10m, gas outburst forecast is carried out and the gas exceeding the limit in the upper corner is forecasted; When the surrounding rock thickness is ≥10m, gas outburst forecast is carried out, gas outburst in the upper corner is forecasted, and the return air gas in the mining face is seriously exceeded, and the exceeding time is long; 2) Prediction of gas outburst in the surrounding rock of coal seam floor. Prediction of gas outburst in the surrounding rock of coal seam floor includes: ① Gas outburst prediction at excavation working face: The interlayer distance between the top plate of the rock reservoir and the bottom plate of the coal seam is less than 10m, the gas pressure of the rock reservoir is ≥0.5MPa or the outburst risk index is ≥0.05MPa / m, the gas in the bottom plate surrounding rock will outburst along the faults and cracks of the weak surface of the rock formation, and gas outburst prediction should be carried out before excavation; The interlayer distance between the top plate of the rock reservoir and the bottom plate of the coal seam is ≥10m, the gas pressure of the rock reservoir is ≥0.5MPa or the gas outburst hazard index is ≥0.05MPa / m, and a gas outburst forecast is made before excavation; ②Prediction of gas outburst in the surrounding rock of the bottom plate of the mining face: Mining the working face to determine the depth of the floor damage zone; If the floor rock reservoir is located in the floor damage zone, the rock reservoir gas will all enter the goaf; if it is located in the affected zone, part of the gas will enter the goaf; When the gas pressure of the floor rock reservoir is ≥0.5MPa or the outburst hazard index is ≥0.05, coal and gas outburst will occur in the mining face, and gas outburst prediction should be carried out; The forecast content is: The underlying surrounding rock is thin, and the surrounding rock gas enters the goaf of the mining face, and the upper corner exceeds the limit; The underlying bottom rock reservoir is relatively thick and is located within the bottom plate damage zone. Gas outbursts will occur in the upper corner, and the return air flow gas will seriously exceed the limit for a long time.

[0011] In some embodiments, in step S100, the prediction of gas outburst near the coal seam includes: 1) Forecast of gas outburst in adjacent coal seams above the roof: When the coal seam above the roof is adjacent, the interlayer distance is less than 10m, the gas pressure is ≥0.5MPa or the outburst hazard index is ≥0.05MPa / m, a gas outburst forecast is carried out; 2) Forecast of gas outburst in the adjacent coal seams below the coal seam floor. The forecast of gas outburst in the adjacent coal seams below the coal seam floor includes: ① Gas outburst prediction at excavation working face: For coal seams below the floor, with interlayer spacing less than 10m, gas pressure ≥0.5MPa or outburst hazard index ≥0.05MPa / m, gas outburst forecasting is conducted at small faults and cracks on weak rock surfaces; For coal seams below the floor, with interlayer spacing ≥10 meters, gas pressure ≥0.5MPa or outburst hazard index ≥0.05MPa / m, gas outburst forecasting is conducted at faults; ②Prediction of gas outburst in mining working face: Mining the working face to determine the depth of the floor damage zone; When the underlying coal seam is located within the floor damage zone, a gas outburst forecast is made at the mining face; The forecast content is: The underlying coal seam is relatively thin, and gas from the adjacent coal seam enters the goaf, causing the upper corner to exceed the limit; Or the underlying coal seam is thick and located within the bottom plate damage zone, and the gas in the upper corner is seriously exceeded, which will cause gas outbursts and return air flow gas exceeding the limit.

[0012] In some embodiments, the highlight risk index O b : O b =P0 / He Among them, b : Highlight the risk index; P0: surrounding rock gas pressure; He: effective barrier thickness.

[0013] In some embodiments, in step S100, a gas outburst forecast is performed in the coal seam geological anomaly zone when the following situations occur: Combined with the geological locations of faults, collapse columns and rock walls in the geological report, when drilling to detect the geological locations of coal seams, the gas pressure is measured after top drilling and stuck drilling. The locations where the gas pressure is greater than 0.5MPa are determined to be the gas geological anomaly area of ​​this coal seam. The contour line of 0.5MPa gas pressure in the geological anomaly area is circled, and gas outburst is predicted 20m in advance.

[0014] In some embodiments, in step S100, coal and gas outburst prediction is performed in two or more gas geological high potential areas of a coal seam group when the following situations occur: Outside the mining face of this coal seam, when there are two or more gas geological high potential areas in the coal seam group, that is, more than two gas outburst sources, gas outburst forecast shall be carried out.

[0015] In some embodiments, step S200 includes: 1) Emphasis on forecast verification; 2) Pressure relief after extraction.

[0016] In some embodiments, step S300 includes: when the gas pressure drops below the allowable value of 0.5MPa and the gas outburst hazard index drops below 0.05MPa / m, excavation continues; during excavation, gas extraction cannot be stopped to prevent the gas accumulation pressure from rising again after extraction is stopped, causing an outburst.

[0017] Compared with the prior art, the present invention makes a method for predicting coal and gas outbursts through gas geological research and judgment based on the type classification of coal and gas outburst mines, regional distribution, determination of gas geological high potential areas, prediction of surrounding rock gas outbursts, etc., which is a key link in preventing and controlling coal and gas outbursts. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0020] like Figure 1 As shown in the figure, an accurate coal and gas outburst prediction method based on gas geological analysis includes: S100: Coal and gas forecasts are carried out according to different situations, including: 1) Gas outburst prediction before design, mine construction and mine extension; 2) Forecast of gas outburst before uncovering rock reservoirs or coal; 3) Prediction of gas outburst in surrounding rock; 4) Forecast of gas outburst near coal seams; 5) Forecast of gas outburst in the geological anomaly area of ​​the coal seam; 6) Forecast of coal and gas outbursts in two or more gas geological high potential areas in coal seam groups.

[0021] S200: Highlight forecast verification and take measures; Step S200 includes: 1) Emphasis on forecast verification; The outstanding forecast verification lies in the accurate testing of gas pressure and other parameters; To test the gas pressure, it is necessary to carry out sealing and pressure resistance tests; to test the gas pressure, concentration, flow rate, etc., select a scientific and reasonable location and make a good design; the gas pressure should take its maximum value.

[0022] 2) Pressure relief after extraction.

[0023] S300: release of the prominent forecast; Step S300 includes: when the gas pressure drops below the allowable value of 0.5MPa and the gas outburst hazard index drops below 0.05MPa / m, continue tunneling; during the tunneling process, gas extraction cannot be stopped to prevent the gas accumulation pressure from rising again after the extraction is stopped, causing an outburst.

[0024] In step S100, gas outburst forecasting is performed before designing, building, or extending a mine when the following situations occur: 1) When the gas geological map of the mine is abnormal, a gas outburst forecast is carried out, where the gas geological map abnormalities of the mine include: ① The coal seam has no outcrop, that is, the coal seam does not come out to the surface, there is no escape channel for coal seam gas, and the gas content per ton of coal is less than 10m 3 / t; ② In the same mine, the gas per ton of coal isoline in the deep coal seam is lower than the gas per ton of coal isoline in the shallow coal seam; ③ In the same coal seam, the gas-per-ton contour line is abnormal, and the gas-per-ton contour line in the deep coal seam is lower than that in the shallow coal seam; or in the same coal seam, the gas-per-ton contour line map is chaotic and disordered, which is contrary to the influence of burial depth, structure, space and hydrogeology on coal seam gas; The above anomalies are manifestations of coal and gas outbursts on the gas geological map of this mine.

[0025] 2) When gas dynamic phenomena or coal and gas outbursts occur near infrastructure and production mines, gas outburst forecasts are carried out, including the following situations: ① Gas dynamic phenomena or outbursts occur continuously in the same coal seam tunnel; ② The location where gas dynamic phenomenon or outburst occurs in the coal seam tunnel, and the gas dynamic phenomenon or outburst occurs again during tunnel maintenance; ③ The amount of gas ejected during the outburst is equal to or greater than twice the amount of gas contained in the outburst coal.

[0026] Such outbursts in adjacent mines are indicative of gas outbursts in rock reservoirs. Such outbursts may also occur in newly built mines near the same floor contour of the coal seam in the absence of large or medium-sized structures.

[0027] In step S100, a gas outburst forecast is performed before uncovering the rock reservoir or coal when the following situations occur: 1) When there is no coal-bearing geological outcrop to expose the reservoir: The upper part of the coal seam is a rock reservoir. When the water pressure in the rock reservoir is ≥0.5MPa, gas outburst prediction is carried out 10m before the minimum normal distance from the coal and rock reservoir. 2) When uncovering coal seams with outcrops: The gas pressure at the coal mining point is calculated as follows: P=g p (H-H0)+P0 Where: P: predicted gas pressure at depth H in the methane zone, MPa; g p : Gas pressure gradient; H: See the elevation of the coal point and predict the depth value in the methane zone; H0: depth of upper boundary of methane zone; P0: gas pressure at the upper boundary of the methane zone, generally 0.2MPa; When P is calculated to be ≥ 0.5MPa, gas outburst prediction is carried out 10m before the minimum normal distance from the coal and rock reservoirs; 3) When uncovering coal in a seam without outcropping: When the water pressure of the rock reservoir is ≥0.5MPa, gas outburst prediction is carried out at the minimum normal distance of 10m from the coal and rock reservoir; 4) When gas outbursts from the underlying coal seam: The underlying coal seam is a raw cap stratum, and the coal seam gas pressure P=g p (H-H0)+P0; When P≥0.5MPa and there is a danger of gas outburst after coal is uncovered, gas outburst prediction shall be carried out 10m before the minimum normal distance from the coal and rock reservoirs; The underlying coal seam is a source-reservoir cap stratum, and the gas pressure of the rock reservoir is equal to the water pressure; When the water pressure is ≥0.5MPa, there is a danger of gas outburst after coal is uncovered, and gas outburst forecast should be carried out before the minimum normal distance of 10m from the coal and rock reservoir.

[0028] In step S100, the prediction of gas outburst in surrounding rock includes: 1) Forecast of gas outburst in the surrounding rock of coal seam roof. Forecast of gas outburst in the surrounding rock of coal seam roof includes: ① Gas outburst prediction at excavation working face: When the distance between the rock reservoir and the coal seam is less than 10m, the distance between the rock reservoir floor and the coal seam roof is less than 10m, the gas pressure of the rock reservoir is ≥0.5MPa or the outburst risk index is ≥0.05MPa / m, the surrounding rock gas will outburst along the faults and cracks of the weak surface of the rock formation, and gas outburst prediction should be carried out before excavation; When the rock reservoir is located in the caving zone, the distance between the rock reservoir and the coal seam is ≥10m, but in the caving zone, the gas pressure of the rock reservoir is ≥0.5MPa or the outburst hazard index is ≥0.05MPa / m, and the surrounding rock gas will outburst along the fault zone. Gas outburst prediction should be carried out before excavation; ②Prediction of gas outburst in the surrounding rock of the mining face roof: When the surrounding rock thickness is less than 10m, gas outburst forecast is carried out and the gas exceeding the limit in the upper corner is forecasted; When the surrounding rock thickness is ≥10m, gas outburst forecast is carried out, gas outburst in the upper corner is forecasted, and the return air gas in the mining face is seriously exceeded, and the exceeding time is long; 2) Prediction of gas outburst in the surrounding rock of coal seam floor. Prediction of gas outburst in the surrounding rock of coal seam floor includes: ① Gas outburst prediction at excavation working face: The interlayer distance between the top plate of the rock reservoir and the bottom plate of the coal seam is less than 10m, the gas pressure of the rock reservoir is ≥0.5MPa or the outburst risk index is ≥0.05MPa / m, the gas in the bottom plate surrounding rock will outburst along the faults and cracks of the weak surface of the rock formation, and gas outburst prediction should be carried out before excavation; The interlayer distance between the top plate of the rock reservoir and the bottom plate of the coal seam is ≥10m, the gas pressure of the rock reservoir is ≥0.5MPa or the gas outburst hazard index is ≥0.05MPa / m, and a gas outburst forecast is made before excavation; ②Prediction of gas outburst in the surrounding rock of the bottom plate of the mining face: Mining the working face to determine the depth of the floor damage zone; If the floor rock reservoir is located in the floor damage zone, the rock reservoir gas will all enter the goaf; if it is located in the affected zone, part of the gas will enter the goaf; When the underlying floor rock reservoir is thick, that is, the gas pressure of the floor rock reservoir is ≥0.5MPa or the outburst hazard index is ≥0.05, coal and gas outburst may occur in the mining face, and gas outburst prediction should be carried out; The forecast content is: The underlying surrounding rock is thin, and the surrounding rock gas enters the goaf of the mining face, and the upper corner exceeds the limit; The underlying bottom rock reservoir is relatively thick and is located within the bottom plate damage zone. Gas outbursts will occur in the upper corner, and the return air flow gas will seriously exceed the limit for a long time.

[0029] In step S100, the prediction of gas outburst near the coal seam includes: 1) Forecast of gas outburst in adjacent coal seams above the roof: When the coal seam above the roof is adjacent, the interlayer distance is less than 10m, the gas pressure is ≥0.5MPa or the outburst hazard index is ≥0.05MPa / m, a gas outburst forecast is carried out; 2) Forecast of gas outburst in the adjacent coal seams below the coal seam floor. The forecast of gas outburst in the adjacent coal seams below the coal seam floor includes: ① Gas outburst prediction at excavation working face: For coal seams below the floor, with interlayer spacing less than 10m, gas pressure ≥0.5MPa or outburst hazard index ≥0.05MPa / m, gas outburst forecasting is conducted at small faults and cracks on weak rock surfaces; For coal seams below the floor, with interlayer spacing ≥10 meters, gas pressure ≥0.5MPa or outburst hazard index ≥0.05MPa / m, gas outburst forecasting is conducted at faults; ②Prediction of gas outburst in mining working face: Mining the working face to determine the depth of the floor damage zone; When the underlying coal seam is located within the floor damage zone, a gas outburst forecast is made at the mining face; The forecast content is: The underlying coal seam is relatively thin, and gas from the adjacent coal seam enters the goaf, causing the upper corner to exceed the limit; Or the underlying coal seam is thick and located within the bottom plate damage zone, and the gas in the upper corner is seriously exceeded, which will cause gas outbursts and return air flow gas exceeding the limit.

[0030] Among them, the prominent risk index O b : O b =P0 / He Among them, b : Highlight the risk index; P0: surrounding rock gas pressure; He: effective barrier thickness.

[0031] In step S100, a gas outburst forecast is performed in the coal seam geological anomaly area when the following situations occur: Combined with the geological locations of faults, collapse columns and rock walls in the geological report, when drilling to detect the geological locations of coal seams, the gas pressure is measured after top drilling and stuck drilling. The locations where the gas pressure is greater than 0.5MPa are determined to be the gas geological anomaly area of ​​this coal seam. The contour line of 0.5MPa gas pressure in the geological anomaly area is circled, and gas outburst is predicted 20m in advance.

[0032] In step S100, coal and gas outburst forecasting is performed in two or more gas geological high potential areas of the coal seam group when the following situations occur: Outside the mining face of this coal seam, when there are two or more gas geological high potential areas in the coal seam group, that is, more than two gas outburst sources, gas outburst forecast shall be carried out.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An accurate coal and gas outburst prediction method based on gas geological analysis, characterized in that: include: S100: Coal and gas forecasting according to different situations, including: 1) Gas outburst prediction before design, mine construction and mine extension; 2) Prediction of gas outburst before uncovering rock reservoirs or coal; 3) Prediction of gas outburst in surrounding rock; 4) Forecast of gas outburst near coal seams; 5) Forecast of gas outburst in the geological anomaly area of ​​the coal seam; 6) Forecast of coal and gas outbursts in two or more gas geological high potential areas of coal seam groups; S200: Highlight forecast verification and take measures; S300: cancelling the prominent forecast.

2. The accurate coal and gas outburst prediction method based on gas geological analysis according to claim 1 is characterized in that: In step S100, gas outburst forecasting is performed before designing, building a well, or extending a mine when the following situations occur: 1) When the gas geological map of the mine is abnormal, a gas outburst forecast is carried out, where the gas geological map abnormalities of the mine include: ① The coal seam has no outcrop, that is, the coal seam does not come out to the surface, there is no escape channel for coal seam gas, and the gas content per ton of coal is less than 10m 3 / t; ② In the same mine, the gas per ton of coal isoline in the deep coal seam is lower than the gas per ton of coal isoline in the shallow coal seam; ③ In the same coal seam, the gas-per-ton contour line is abnormal, and the gas-per-ton contour line in the deep coal seam is lower than that in the shallow coal seam; or in the same coal seam, the gas-per-ton contour line map is chaotic and disordered, which is contrary to the influence of burial depth, structure, space and hydrogeology on coal seam gas; 2) When gas dynamic phenomena or coal and gas outbursts occur near infrastructure and production mines, gas outburst forecasts should be carried out, including the following situations: ① Gas dynamic phenomena or outbursts occur continuously in the same coal seam tunnel; ② The location where gas dynamic phenomenon or outburst occurs in the coal seam tunnel, and gas dynamic phenomenon or outburst occurs again during tunnel maintenance; ③ The amount of gas ejected during the outburst is equal to or greater than twice the amount of gas contained in the outburst coal.

3. The accurate coal and gas outburst prediction method based on gas geological analysis according to claim 1 is characterized in that: In step S100, a gas outburst forecast is performed before uncovering a rock reservoir or coal when the following situations occur: 1) When there is no coal-bearing geological outcrop to expose the reservoir: The upper part of the coal seam is a rock reservoir. When the water pressure in the rock reservoir is ≥0.5MPa, gas outburst prediction is carried out 10m before the minimum normal distance from the coal and rock reservoir. 2) When uncovering coal seams with outcrops: The gas pressure at the coal mining point is calculated as follows: P=g p (H-H0)+P0 Where: P: predicted gas pressure at depth H in the methane zone, MPa; g p : Gas pressure gradient; H: See the elevation of the coal point and predict the depth value in the methane zone; H0: depth of upper boundary of methane zone; P0: gas pressure at the upper boundary of the methane zone, generally 0.2MPa; When P is calculated to be ≥ 0.5MPa, gas outburst prediction is carried out 10m before the minimum normal distance from the coal and rock reservoirs; 3) When uncovering coal in a seam without outcropping: When the water pressure of the rock reservoir is ≥0.5MPa, gas outburst prediction is carried out at the minimum normal distance of 10m from the coal and rock reservoir; 4) When gas outbursts from the underlying coal seam: The underlying coal seam is a raw cap stratum, and the coal seam gas pressure P=g p (H-H0)+P0; When P≥0.5MPa and there is a danger of gas outburst after coal is uncovered, gas outburst prediction shall be carried out 10m before the minimum normal distance from the coal and rock reservoirs; The underlying coal seam is a source-reservoir cap stratum, and the gas pressure of the rock reservoir is equal to the water pressure; When the water pressure is ≥0.5MPa, there is a danger of gas outburst after coal is uncovered, and gas outburst forecast should be carried out before the minimum normal distance of 10m from the coal and rock reservoir.

4. The accurate coal and gas outburst prediction method based on gas geological analysis according to claim 1 is characterized in that: In step S100, the prediction of gas outburst in surrounding rock includes: 1) Forecast of gas outburst in the surrounding rock of coal seam roof. Forecast of gas outburst in the surrounding rock of coal seam roof includes: ① Gas outburst prediction at excavation working face: When the distance between the rock reservoir and the coal seam is less than 10m, the distance between the rock reservoir floor and the coal seam roof is less than 10m, the gas pressure of the rock reservoir is ≥0.5MPa or the outburst risk index is ≥0.05MPa / m, the surrounding rock gas will outburst along the faults and cracks of the weak surface of the rock formation, and gas outburst prediction should be carried out before excavation; When the rock reservoir is located in the caving zone, the distance between the rock reservoir and the coal seam is ≥10m, but in the caving zone, the gas pressure of the rock reservoir is ≥0.5MPa or the outburst hazard index is ≥0.05MPa / m, and the surrounding rock gas will outburst along the fault zone. Gas outburst prediction should be carried out before excavation; ②Prediction of gas outburst in the surrounding rock of the mining face roof: When the surrounding rock thickness is less than 10m, gas outburst forecast is carried out and the gas exceeding the limit in the upper corner is forecasted; When the surrounding rock thickness is ≥10m, gas outburst forecast is carried out, gas outburst in the upper corner is forecasted, and the return air gas in the mining face is seriously exceeded, and the exceeding time is long; 2) Prediction of gas outburst in the surrounding rock of coal seam floor. Prediction of gas outburst in the surrounding rock of coal seam floor includes: ① Gas outburst prediction at excavation working face: The interlayer distance between the top plate of the rock reservoir and the bottom plate of the coal seam is less than 10m, the gas pressure of the rock reservoir is ≥0.5MPa or the outburst risk index is ≥0.05MPa / m, the gas in the bottom plate surrounding rock will outburst along the faults and cracks of the weak surface of the rock formation, and gas outburst prediction should be carried out before excavation; The interlayer distance between the top plate of the rock reservoir and the bottom plate of the coal seam is ≥10m, the gas pressure of the rock reservoir is ≥0.5MPa or the gas outburst hazard index is ≥0.05MPa / m, and a gas outburst forecast is made before excavation; ②Prediction of gas outburst in the surrounding rock of the bottom plate of the mining face: Mining the working face to determine the depth of the floor damage zone; If the floor rock reservoir is located in the floor damage zone, the rock reservoir gas will all enter the goaf; if it is located in the affected zone, part of the gas will enter the goaf; When the gas pressure of the floor rock reservoir is ≥0.5MPa or the outburst hazard index is ≥0.05, coal and gas outburst will occur in the mining face, and gas outburst prediction should be carried out; The forecast content is: The underlying surrounding rock is thin, and the surrounding rock gas enters the goaf of the mining face, and the upper corner exceeds the limit; The underlying bottom rock reservoir is relatively thick and is located within the bottom plate damage zone. Gas outbursts will occur in the upper corner, and the return air flow gas will seriously exceed the limit for a long time.

5. The accurate coal and gas outburst prediction method based on gas geological analysis according to claim 1 is characterized in that: In step S100, the prediction of gas outburst near the coal seam includes: 1) Forecast of gas outburst in adjacent coal seams above the roof: When the coal seam above the roof is adjacent, the interlayer distance is less than 10m, the gas pressure is ≥0.5MPa or the outburst hazard index is ≥0.05MPa / m, a gas outburst forecast is carried out; 2) Forecast of gas outburst in the adjacent coal seams below the coal seam floor. The forecast of gas outburst in the adjacent coal seams below the coal seam floor includes: ① Gas outburst prediction at excavation working face: For coal seams below the floor, with interlayer spacing less than 10m, gas pressure ≥0.5MPa or outburst hazard index ≥0.05MPa / m, gas outburst forecasting is conducted at small faults and cracks on weak rock surfaces; For coal seams below the floor, with interlayer spacing ≥10 meters, gas pressure ≥0.5MPa or outburst hazard index ≥0.05MPa / m, gas outburst forecasting is conducted at faults; ②Prediction of gas outburst in mining working face: Mining the working face to determine the depth of the floor damage zone; When the underlying coal seam is located within the floor damage zone, a gas outburst forecast is made at the mining face; The forecast content is: The underlying coal seam is relatively thin, and gas from the adjacent coal seam enters the goaf, causing the upper corner to exceed the limit; Or the underlying coal seam is thick and located within the bottom plate damage zone, and the gas in the upper corner is seriously exceeded, which will cause gas outbursts and return air flow gas exceeding the limit.

6. The accurate coal and gas outburst prediction method based on gas geological analysis according to claim 4 or 5 is characterized in that: The protruding risk index O b : O b =P0 / He Among them, b : Highlight the risk index; P0: surrounding rock gas pressure; He: effective barrier thickness.

7. The accurate coal and gas outburst prediction method based on gas geological analysis according to claim 1 is characterized in that: In step S100, a gas outburst forecast is performed in the coal seam geological anomaly zone when the following situations occur: Combined with the geological locations of faults, collapse columns and rock walls in the geological report, when drilling to detect the geological locations of coal seams, the gas pressure is measured after top drilling and stuck drilling. The locations where the gas pressure is greater than 0.5MPa are determined to be the gas geological anomaly area of ​​this coal seam. The contour line of 0.5MPa gas pressure in the geological anomaly area is circled, and gas outburst is predicted 20m in advance.

8. The accurate coal and gas outburst prediction method based on gas geological analysis according to claim 1 is characterized in that: In step S100, coal and gas outburst prediction is performed in two or more gas geological high potential areas of the coal seam group when the following situations occur: Outside the mining face of this coal seam, when there are two or more gas geological high potential areas in the coal seam group, that is, more than two gas outburst sources, gas outburst forecast shall be carried out.

9. The accurate coal and gas outburst prediction method based on gas geological analysis according to claim 1 is characterized in that: The step S200 includes: 1) Emphasis on forecast verification; 2) Pressure relief after extraction.

10. The accurate coal and gas outburst prediction method based on gas geological analysis according to claim 1 is characterized in that: The step S300 includes: when the gas pressure drops below the allowable value of 0.5MPa and the gas outburst hazard index drops below 0.05MPa / m, continue tunneling; during the tunneling process, gas extraction cannot be stopped to prevent the gas accumulation pressure from rising again after the extraction is stopped, causing an outburst.

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