Quantitative traceability measuring method for mixed gas source of working face

Abstract

The invention discloses a quantitative traceability measuring method for a mixed gas source of a working face, and belongs to the technical field of underground gas disaster prevention and control. At least two drill holes are drilled in each drill site upwards adjacent to the coal seam, at least two drill holes are drilled in the coal seam, at least two drill holes are drilled in the drill site downwards adjacent to the coal seam, and at least one coal sample is taken from each drill hole; s2, measuring a methane carbon isotope value (13C), an ethane carbon isotope value (13C), a carbon dioxide carbon isotope value (13C), a methane hydrogen isotope value (2H) and an ethane hydrogen isotope value (2H) of each coal sample; s3, measuring the isotope value of the gas sample of the mixed source gas; and s4, performing quantitative traceability analysis. According to the method, the hydrocarbon same-digit measuring technology is adopted, the symbolic hydrocarbon isotope value of each coal seam is effectively utilized, the proportion of the mixed source gas sample from each coal seam is calculated by establishing a mathematical model, the source of the mixed source gas sample is quantitatively traced, the distinction degree is high, and the accuracy is high.

Description

Technical Field

[0001] This invention relates to the field of coal mine underground gas disaster prevention and control technology, and more specifically, to a method for quantitatively tracing and determining the source of mixed gas in the working face. Background Technology

[0002] The analysis of gas emission and gas source at the working face is crucial for gas control. Traditional statistical analysis and source prediction methods, influenced by factors such as the selected coal seam thickness, gas content, and empirical coefficients, can only predict the proportion of gas sources from adjacent seams, the current coal seam, and the goaf based on experience, and cannot accurately quantify the proportion of gas sources in each coal seam.

[0003] Therefore, it is necessary to improve the existing technology. Summary of the Invention

[0004] The purpose of this invention is to provide a method for quantitatively tracing and determining the source of mixed gas in a working face, aiming to solve at least one of the technical problems existing in the prior art. To achieve the above objective, the technical solution adopted is as follows:

[0005] A method for quantitatively tracing and determining the source of mixed gas in a working face, characterized by the following steps:

[0006] s1. At least three drilling sites shall be selected in the working face roadway. At each drilling site, at least two boreholes shall be drilled upwards into the adjacent coal seam, at least two boreholes shall be drilled into the current coal seam, and at least two boreholes shall be drilled downwards into the adjacent coal seam. At least one coal sample shall be taken from each borehole.

[0007] s2. Calculate the methane carbon isotope values ​​for each coal sample ( 13 C) Ethane carbon isotope value ( 13 C), Carbon dioxide carbon isotope value ( 13 C), Methane hydrogen isotope value ( 2 H) and ethane hydrogen isotope values ​​( 2 H) determination;

[0008] The same type of isotope values ​​in the same coal seam form a small group of data, and the same type of small group of data in different coal seams forms a large group of data. Analyze each large group of data and select two large groups of data. The selection principle is: the difference between the small groups of data in the large group is relatively large and the distribution is relatively uniform.

[0009] The median or mean of each subgroup of data in the first selected large group is used as the first type of indicative isotope value of the corresponding coal seam, that is, the first type of indicative isotope value of the upper adjacent coal seam is A1, the first type of indicative isotope value of this coal seam is B1, and the first type of indicative isotope value of the lower adjacent coal seam is C1.

[0010] The median or mean of each subgroup of data in the selected second group of large data is used as the corresponding second-class characteristic isotope value of the coal seam, that is, the second-class characteristic isotope value of the upper adjacent coal seam is A2, the second-class characteristic isotope value of this coal seam is B2, and the second-class characteristic isotope value of the lower adjacent coal seam is C2.

[0011] s3. Sample mixed-source gas at the sampling point, and determine the isotope value of the mixed-source gas sample that is of the same type as the first type of characteristic isotope value, denoted as K1, and the isotope value that is of the same type as the second type of characteristic isotope value, denoted as K2;

[0012] s4. According to the law of conservation of mass of the gas mixture, we know that:

[0013] xA1+yB1+zC1+ε1=K1;

[0014] xA² + yB² + zC² + ε² = K²;

[0015] x+y+z=1;

[0016] Where x is the proportion of mixed-source gas sample from the upper adjacent coal seam, y is the proportion of mixed-source gas sample from this coal seam, z is the proportion of mixed-source gas sample from the lower adjacent coal seam, ε1 is the residual value of the isotope value of the same type as the first type of characteristic isotope value, and ε2 is the residual value of the isotope value of the same type as the second type of characteristic isotope value.

[0017] Based on the following mathematical model, solve for the values ​​of x, y, and z:

[0018]

[0019] Preferably, in step s1, each drilling site drills three holes with different depths, and the horizontal projection interval between the final positions of any two adjacent holes is greater than 10m.

[0020] Preferably, in step s1, the distance between the final borehole position of the three boreholes in this coal seam and the working face is greater than 30% of the working face width.

[0021] Preferably, in step s1, the borehole diameter is 100-150 mm.

[0022] Preferably, in step s1, two cylindrical coal samples are taken from each borehole.

[0023] Preferably, in step s2, the method for determining the isotopic values ​​of the coal sample is as follows:

[0024] First, the obtained coal sample is placed in a coal sample container, then the coal sample container is evacuated and left to stand for 1-2 hours. Finally, the isotope values ​​of the gas released from the coal sample in the coal sample container are determined by a stable isotope mass spectrometer.

[0025] Preferably, in step s3, the method for determining the isotopic values ​​of the mixed-source gas sample is as follows:

[0026] A manual sampling method using a gas sampling cylinder and an air bag was employed to collect mixed-source gas samples. At least three samples were taken, and the isotope values ​​of each mixed-source gas sample were determined using a stable isotope mass spectrometer. The average value was then calculated.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. This invention uses carbon-hydrogen isotope determination technology, which can effectively utilize the characteristic carbon-hydrogen isotope values ​​of each coal seam. By establishing a mathematical model, the proportion of mixed-source gas samples from each coal seam can be calculated, realizing quantitative source tracing of mixed-source gas samples with strong discrimination and high accuracy.

[0029] 2. This invention is less affected by coal seam geological conditions and mining, the underground sampling operation is simple, the sampling workload is small, the degree of automation is high, the source of mixed gas samples is highly identifiable and the stability is strong, providing technical support for comprehensive gas control in working faces. Attached Figure Description

[0030] To more clearly illustrate the technical solution of the present invention, the 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.

[0031] Figure 1 This is the design drawing for borehole sampling of each coal seam according to the present invention.

[0032] Figure 2 This is a plan view of the coal seam borehole sampling of this invention.

[0033] In the diagram: 1. Intake airway; 2. Upper adjacent coal seam; 3. This coal seam; 4. Lower adjacent coal seam; 5. High-level borehole pipeline; 6. Buried pipeline in the goaf; 7. Upper corner; 8. Return airway; 9. Cut-off; 10. Support; 11. Goaf. Detailed Implementation

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0035] A preferred embodiment of the present invention provides a method for quantitatively tracing and determining the source of mixed gas in a working face, the method comprising the following steps:

[0036] s1. Sampling borehole design.

[0037] like Figures 1-2 As shown, three drilling sites are selected along the length of the working face in the intake airway 1, and are labeled 1#, 2# and 3# respectively. When the working face is long and the coal seam is thick, the number of sampling drilling sites is increased to five.

[0038] Within drilling site #1: Drill at least two boreholes perpendicular to the coal face upwards into adjacent coal seam 2. Preferably, three boreholes are drilled, each with a different depth, and the horizontal projection interval between the final positions of any two adjacent boreholes is greater than 10m. Drill at least two boreholes horizontally into coal seam 3. Preferably, three boreholes are drilled, each with a different depth, and the horizontal projection interval between the final positions of any two adjacent boreholes is greater than 10m. Furthermore, the distance between the final positions of the three boreholes in coal seam 3 and the working face is greater than 30% of the working face width. Drill at least two boreholes downwards into adjacent coal seam 4. Preferably, three boreholes are drilled, each with a different depth, and the horizontal projection interval between the final positions of any two adjacent boreholes is greater than 10m.

[0039] The drilling design in drilling sites #2 and #3 is the same as that in drilling site #1, and will not be repeated here. As can be seen from the above, a total of twenty-seven holes were drilled in the three drilling sites.

[0040] Furthermore, each borehole is constructed using a coal mine directional drilling rig, with a borehole diameter of 100-150 mm, preferably 112 mm in this embodiment. After each borehole reaches the predetermined depth, a core casing is used to collect coal samples, and two cylindrical coal samples are taken, resulting in a total of fifty-four coal samples.

[0041] s2. Determination of the characteristic isotope values ​​of coal samples.

[0042] The methane carbon isotope values ​​of fifty-four coal samples were analyzed. 13 C) Ethane carbon isotope value ( 13 C), Carbon dioxide carbon isotope value ( 13 C), Methane hydrogen isotope value ( 2 H) and ethane hydrogen isotope values ​​( 2 H) determination.

[0043] The specific determination method is as follows: First, put the coal sample into the coal sample container, then evacuate the coal sample container and let it stand for 1-2 hours. Finally, use a stable isotope mass spectrometer to determine the isotope value of the gas released from the coal sample in the coal sample container.

[0044] The five isotope values ​​for each coal sample were obtained through the above steps, and then grouped. Specifically:

[0045] A set of data on similar isotope values ​​from the same coal seam, including: methane carbon isotope values ​​( 13 C) Group data, ethane carbon isotope values ​​( 13C) Group data, carbon dioxide carbon isotope values ​​( 13 C) Group data, methane hydrogen isotope values ​​( 2 H) Group data and ethane hydrogen isotope values ​​( 2 H) Group data, each group of data has eighteen isotope values ​​of the same type.

[0046] Data from similar groups in different coal seams are grouped into one large set of data, which includes: methane carbon isotope values ​​( 13 C) Large group data, ethane carbon isotope values ​​( 13 C) Large-group data, carbon dioxide carbon isotope values ​​( 13 C) Large group data, methane hydrogen isotope values ​​( 2 H) Large group data and ethane hydrogen isotope values ​​( 2 H) Large group data, each large group data includes a small group of similar data from the upper adjacent coal seam, the current coal seam, and the lower adjacent coal seam.

[0047] Analyze each large group of data and select two large groups of data. The selection principle is: the data in each subgroup of the large group of data has a large degree of difference and a relatively uniform distribution.

[0048] The above method was used to analyze a gas-fired coal mine in Shanxi Province. The two selected large sets of data were methane carbon isotope values. 13 C) Large group data and ethane hydrogen isotope values ​​( 2 H) Large group data.

[0049] methane carbon isotope value ( 13 C) Within each subgroup of data, the median or mean was used as the corresponding methane carbon isotope value for the coal seam. 13 C), that is, the methane carbon characteristic isotope value of the adjacent coal seam ( 13 C) is A1, the carbon characterization isotope value of methane in this coal seam ( 13 C) is B1, the methane carbon characterization isotope value of the adjacent coal seam below ( 13 C) is C1;

[0050] Ethane hydrogen isotope value ( 2 For each subgroup of data in the H) large group, the median or mean was used as the corresponding ethane hydrogen isotope value for the coal seam. 2 H), that is, the hydrogen isotope value of ethane from the adjacent coal seam above ( 2 H) is A2, the characteristic hydrogen isotope value of ethane in this coal seam is ( 2 H) is B2, and the characteristic hydrogen isotope value of ethane in the adjacent coal seam below ( 2 H) is C2;

[0051] For specific isotope values ​​in this embodiment, please refer to Tables 1-3:

[0052] Table 1: Determination of Indicative Isotope Values ​​of Upper Adjacent Coal Seams

[0053]

[0054] Table 2: Determination of Indicative Isotope Values ​​of This Coal Seam

[0055]

[0056] Table 3: Determination of Indicative Isotope Values ​​of Lower Adjacent Coal Seams

[0057]

[0058] s3. Isotope values ​​of mixed-source gas samples.

[0059] High-level borehole pipeline 5 serves as the first sampling point. A manual sampling method using a gas sampling cylinder and airbag is employed to collect mixed-source gas samples. At least three samples are taken; in this embodiment, three samples are preferably taken. The methane carbon isotope value of each mixed-source gas sample is determined using a stable isotope mass spectrometer. 13 C) and ethane hydrogen isotope values ​​( 2 The average of the three methane carbon isotope values ​​(¹³C) obtained (H) is recorded as the first sampling point K1. The three ethane hydrogen isotope values ​​obtained (H) are recorded as the average of the three methane carbon isotope values ​​(¹³C). 2 H) Take the average value and denote it as the second sampling point K2.

[0060] Samples were taken at the locations of buried pipeline 6 (second sampling point) and upper corner 7 (third sampling point) in the goaf area. The values ​​of K1 and K2 were measured and calculated using the same method as described above, as shown in Table 4.

[0061] Table 4: Data Measurement Table for Mixed Source Gas Samples

[0062]

[0063] s4. Quantitative traceability analysis.

[0064] According to the law of conservation of mass in a gas mixture:

[0065] xA1+yB1+zC1+ε1=K1;

[0066] xA² + yB² + zC² + ε² = K²;

[0067] x+y+z=1;

[0068] Where x is the proportion of the mixed-source gas sample originating from the upper adjacent coal seam, y is the proportion of the mixed-source gas sample originating from this coal seam, z is the proportion of the mixed-source gas sample originating from the lower adjacent coal seam, ε1 is the residual value of the methane carbon characteristic isotope value (13C), and ε2 is the residual value of the ethane hydrogen characteristic isotope value (13C). 2 The residual value of H).

[0069] Using MATLAB software, establish the following mathematical model and solve for the values ​​of x, y, and z:

[0070]

[0071] In this embodiment, both ε1 and ε2 are 0.01.

[0072] Substituting the data from Tables 1-3, we get:

[0073] -38.879x-36.668y-32.439z+0.01=K1;

[0074] -16.889x-15.341y-13.239z+0.01=K2;

[0075] x+y+z=1;

[0076]

[0077] Substitute the data from Table 4 into the table to obtain the x, y, and z values ​​for each position, as shown in Table 5.

[0078] Table 5: Proportion of Mixed Source Gas Samples

[0079]

[0080] Table 5 shows that the gas in the high-level borehole pipeline 5 mainly originates from the upper adjacent coal seam 2 and the local coal seam 3, with the upper adjacent coal seam 2 being the main source (62.44%). This is mainly due to the development of fractures during mining. Under the negative pressure of extraction, the gas from the upper adjacent coal seam 2 and the local coal seam 3 near the high-level borehole migrates upwards through these fractures. The gas in the goaf buried pipeline 6 mainly originates from the upper adjacent coal seam 2 and the local coal seam 3, with the local coal seam 3 accounting for 57.35% and the lower adjacent coal seam 4 having the largest share at 12.43%. This is mainly due to mining activities. Roof fractures affected the upper adjacent coal seam 2, and under the influence of mining activities, fractures developed downwards, extending to the lower adjacent coal seam 4. The gas from the lower adjacent coal seam 4 gradually migrates towards the working face of the local coal seam 3. The gas in the upper corner of the seven locations mainly originates from this coal seam, accounting for 74.24%. The gas in the upper adjacent coal seam 2 and the lower adjacent coal seam 4 is relatively higher because the fractures are close to the working face and their development is delayed. As the roof gradually collapses with the advancement of the working face, the gas in the upper adjacent coal seam 2 is relatively higher.

[0081] Based on the source ratio of mixed gas samples, analyze the key points of disaster prevention and control during the working face mining period, and take targeted preventive measures, such as grouting behind the working face wall, grouting the bottom plate cracks, grouting the roof plate cracks, sealing the goaf, adjusting the depth of buried pipes in the goaf, increasing the negative pressure of the extraction system, and increasing the number of high-level boreholes, to guide the safe mining of the working face.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for quantitatively tracing and determining the source of mixed gas in a working face, characterized in that, The method includes the following steps: s1. At least three drilling sites shall be selected in the working face roadway. At each drilling site, at least two boreholes shall be drilled upwards into the adjacent coal seam, at least two boreholes shall be drilled into the current coal seam, and at least two boreholes shall be drilled downwards into the adjacent coal seam. At least one coal sample shall be taken from each borehole. s2. Calculate the methane carbon isotope values ​​for each coal sample ( 13 C) Ethane carbon isotope value ( 13 C), Carbon dioxide carbon isotope value ( 13 C), Methane hydrogen isotope value ( 2 H) and ethane hydrogen isotope values ​​( 2 H) determination; The same type of isotope values ​​in the same coal seam form a small group of data, and the same type of small group of data in different coal seams forms a large group of data. Analyze each large group of data and select two large groups of data. The selection principle is: the difference between the small groups of data in the large group is relatively large and the distribution is relatively uniform. The median or mean of each subgroup of data in the first selected large group is used as the first type of indicative isotope value of the corresponding coal seam, that is, the first type of indicative isotope value of the upper adjacent coal seam is A1, the first type of indicative isotope value of this coal seam is B1, and the first type of indicative isotope value of the lower adjacent coal seam is C1. The median or mean of each subgroup of data in the selected second group of large data is used as the corresponding second-class characteristic isotope value of the coal seam, that is, the second-class characteristic isotope value of the upper adjacent coal seam is A2, the second-class characteristic isotope value of this coal seam is B2, and the second-class characteristic isotope value of the lower adjacent coal seam is C2. s3. Sample mixed-source gas at the sampling point, and determine the isotope value of the mixed-source gas sample that is of the same type as the first type of characteristic isotope value, denoted as K1, and the isotope value that is of the same type as the second type of characteristic isotope value, denoted as K2; s4. According to the law of conservation of mass of the gas mixture, we know that: xA1+yB1+zC1+ε1=K1; xA² + yB² + zC² + ε² = K²; x+y+z=1; Where x is the proportion of mixed-source gas sample from the upper adjacent coal seam, y is the proportion of mixed-source gas sample from this coal seam, z is the proportion of mixed-source gas sample from the lower adjacent coal seam, ε1 is the residual value of the isotope value of the same type as the first type of characteristic isotope value, and ε2 is the residual value of the isotope value of the same type as the second type of characteristic isotope value. Based on the following mathematical model, solve for the values ​​of x, y, and z:

2. The method for quantitatively tracing and determining the source of mixed gas in a working face according to claim 1, characterized in that, In step s1, three boreholes are drilled at each drilling site. The three boreholes have different depths, and the horizontal projection interval between the final positions of any two adjacent boreholes is greater than 10m.

3. The method for quantitatively tracing and determining the source of mixed gas in a working face according to claim 1, characterized in that, In step s1, the distance between the final borehole position of the three boreholes in this coal seam and the working face is greater than 30% of the working face width.

4. The method for quantitatively tracing and determining the source of mixed gas in a working face according to claim 1, characterized in that, In step s1, the borehole diameter is 100-150mm.

5. The method for quantitatively tracing and determining the source of mixed gas in a working face according to claim 1, characterized in that, In step s1, two cylindrical coal samples are taken from each borehole.

6. The method for quantitatively tracing and determining the source of mixed gas in a working face according to claim 1, characterized in that, In step s2, the method for determining the isotopic values ​​of the coal sample is as follows: First, the obtained coal sample is placed in a coal sample container, then the coal sample container is evacuated and left to stand for 1-2 hours. Finally, the isotope values ​​of the gas released from the coal sample in the coal sample container are determined by a stable isotope mass spectrometer.

7. The method for quantitatively tracing and determining the source of mixed gas in a working face according to claim 1, characterized in that, In step s3, the method for determining the isotopic values ​​of the mixed-source gas sample is as follows: A manual sampling method using a gas sampling cylinder and an air bag was employed to collect mixed-source gas samples. At least three samples were taken, and the isotope values ​​of each mixed-source gas sample were determined using a stable isotope mass spectrometer. The average value was then calculated.

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