Comprehensive outburst prevention method based on directional drilling punching-drainage-solidification

Abstract

The invention discloses a comprehensive method for preventing coal outbursts based on directional drilling, punching, extraction and solidification. The method comprises the following steps: firstly, a directional long borehole is constructed from a bottom rock tunnel to a target coal seam, and the distribution of geological structures in the coal tunnel area is detected during the drilling process. Then, the drilling is withdrawn and punching is performed. After the punching is completed, a screen pipe is lowered to construct the next directional long borehole until the directional long borehole in the target area is completed. Subsequently, a negative pressure enhancement hole is constructed in the target area. All directional long boreholes and negative pressure enhancement holes are networked for extraction to eliminate gas internal energy until the extraction meets the standard. Two boreholes near the upper and lower contours of the tunnel are unsealed, and grouting is performed under pressure into the boreholes to reinforce the coal body, thereby improving the strength of the coal body near the tunnel wall. Based on the directional long drilling and punching, the invention greatly increases the pressure relief range of a single hole, realizes pressure relief in the coal body area, coordinates pressure relief by punching, gas extraction and coal body reinforcement, realizes efficient prevention of coal outbursts in the coal seam, and reduces the maintenance cost of the coal tunnel in the later stage.

Description

Technical Field

[0001] The invention relates to the technical field of coal seam coal tunneling and outburst prevention, and in particular to a comprehensive outburst prevention method based on directional drilling and punching-extraction-solidification. Background Art

[0002] After entering deep mining, affected by the high ground stress, high gas pressure and low permeability of coal seams, the prevention and control of coal and gas outburst disasters has become more severe. The threshold for coal and gas outbursts is lower, the scope of impact is wider, and the consequences of the disasters are more serious, threatening the safe production of coal mines.

[0003] According to the hypothesis of the combined effect of coal and gas outburst, the main controlling factors of outburst include ground stress, gas pressure and mechanical strength of coal body. Traditional coal and gas outburst prevention and control technologies mainly target one or two key factors, and fail to fully consider the joint influence of the three factors. For example, the traditional intensive drilling and extraction technology is mainly to eliminate the internal energy of gas, and only prevents outbursts from the perspective of reducing gas pressure. Traditional hydraulic punching or hydraulic cutting technology mainly considers reducing ground stress and eliminating gas internal energy, but the coal body considers the influence of the strength of the coal body itself. In addition, the traditional gas prevention and control method mainly uses through-layer drilling gas extraction to eliminate the danger of coal and gas outbursts. It is a "point-type" outburst elimination method. There is a risk of blind extraction areas between points, which will bury safety hazards for later mining.

[0004] In order to achieve efficient prevention of coal outbursts in deep high-burst coal seams, it is urgent to seek a regional prevention method that comprehensively considers the combined effects of ground stress, gas pressure and coal body strength, so as to achieve safe and efficient excavation of deep coal seam excavation working faces. Summary of the invention

[0005] In view of the above-mentioned technical deficiencies, the purpose of the present invention is to provide a method for extracting pressure-relief gas by using holes instead of tunnels based on ultra-high pressure water jet expansion, which can reduce the construction workload, reduce the cost of gas control, and improve the pressure-relief gas extraction effect of the working face.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] The present invention provides a comprehensive outburst prevention method based on directional drilling punching-drainage-solidification, which specifically comprises the following steps:

[0008] S1. Directional long drilling from the bottom rock tunnel to the target coal seam;

[0009] S2. During the construction of directional long drilling, the relative distance between the roof and floor of the coal seam in the coal roadway area is detected by acoustic wave detection technology to determine the geological structure distribution of the area;

[0010] S3, after the drilling construction is completed, the drilling tool is withdrawn, and the acoustic wave detection equipment is replaced with a high-pressure jet punching device, and the drilling tool is withdrawn and punched to punch out a cylindrical hole with a certain aperture d;

[0011] S4. After the punching is completed, the screen pipe is lowered and the next borehole is constructed at a distance L until all the directional long boreholes designed in the target area are completed;

[0012] S5. Construct several groups of negative pressure enhancement holes from the bottom rock tunnel to the target coal seam;

[0013] S6. All directional long boreholes and negative pressure enhancement holes are networked for extraction to eliminate gas internal energy until the extraction reaches the standard;

[0014] S7: Unseal the two boreholes near the upper and lower contours of the tunnel as grouting holes, inject grouting into the boreholes under pressure to reinforce the coal body and improve the strength of the coal body near the tunnel wall.

[0015] Preferably, the geological structure described in step S2 refers to the area where the coal seam thickness changes, the fault area and the fold area. In the determined geological structure area, the coal output from the punching process is increased by 40% to 80%, further improving the pressure relief effect and the gas extraction effect.

[0016] Preferably, the hole diameter d and the distance L in steps S3 and S4 are optimal drilling hole diameters and optimal drilling hole spacings, and the following relationship is satisfied between the two:

[0017] t0=42.69-16.28p0+74.60L-422.57d+11.05p0L-10.05p0d-40.55Ld+260.87d 2

[0018] Where t0 is the extraction reaching standard time, p0 is the initial gas pressure of coal seam, L is the drilling hole spacing, and d is the optimal hole diameter of punching drilling;

[0019] Under the premise of satisfying the above relationship, when the drilling construction cost is the lowest, the corresponding hole diameter d and distance L are the optimal drilling hole diameter and optimal drilling spacing. The drilling construction cost is calculated as follows:

[0020]

[0021] Where TC is the total cost of punching in a given area, L w is the length of the target area, L b is the length of a single drill hole, L is the drill hole spacing, ρ c is the density of coal, a is the cost of flushing out 1 t of coal, and b is the cost of constructing a 1 m conventional borehole.

[0022] Preferably, the negative pressure enhancement holes in step S5 include several groups, the number of holes in each group is equal to the number of directional long drilling holes, the final hole position is connected with the hole formed by punching the directional long drilling holes, and the spacing between each group of negative pressure enhancement holes is 50 to 100m.

[0023] Preferably, the extraction standard mentioned in step S6 refers to the average residual gas content of the coal seam being less than 8m 3 / t, and the gas pressure at any position of the coal seam in the target area should be less than 0.74MPa. The average residual gas content of the coal seam is obtained by dividing the difference between the total gas reserves and the extracted gas volume in the target area of ​​the coal seam by the volume of the coal body in the target area.

[0024] Preferably, the diameter of the grouting influence range of the grouting borehole described in step S7 is greater than the thickness of the coal seam, so as to construct a safety barrier near the two sides of the tunnel.

[0025] The beneficial effects of the present invention are:

[0026] 1. The present invention uses acoustic wave detection technology to detect the geological structure distribution of the coal roadway area during the construction of directional long boreholes, and specifically increases the coal output of the punching holes at the location of the structural distribution, strengthens the pressure relief and permeability enhancement effect, and realizes the precise elimination of coal roadways. Traditional long boreholes have serious attenuation of the negative pressure due to the long horizontal section, resulting in low negative pressure at locations far from the hole position and poor gas extraction effect. In order to overcome this problem, the present invention proposes to increase the extraction negative pressure at that location by constructing negative pressure enhanced boreholes, improve the extraction effect, and avoid the existence of extraction blind spots.

[0027] 2. The present invention proposes to organically integrate the three methods of punching pressure relief, extraction energy dissipation, and coal body solidification. Through hydraulic punching, the ground stress in the target area is reduced and the elastic potential of the coal body is eliminated. Through gas extraction after hydraulic punching, the gas pressure can be quickly reduced and the gas content can be eliminated. In addition, after the extraction is completed, high-pressure grouting is performed on both sides of the coal roadway through the extraction hole to improve the strength of the coal body, build a safety barrier on both sides of the coal roadway, and resist the residual gas internal energy in the coal. The organic combination of the three technologies can greatly improve the efficiency of coal seam outburst prevention.

[0028] 3. The present invention combines directional long drilling with hydraulic punching, which greatly increases the effective influence range of a single hole, realizes the transformation from traditional "point-type" permeability enhancement to "body-type" permeability enhancement, and greatly reduces the probability of blind areas in the boreholes. In addition, traditional hydraulic punching mainly involves drilling through the rock layer from the bottom rock tunnel to the target coal seam, and the long drilling in the rock layer accounts for more than 80%. These rock layer drillings are useless holes for gas extraction. The method of the present invention can greatly reduce the amount of drilling in the rock layer, greatly increase the ratio of useful holes for gas extraction, and greatly reduce the cost of gas control. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 It is a top view of the positional relationship between two return air channel drilling sites and various directional long boreholes in an embodiment of the present invention.

[0031] Figure 2 It is a front view of the positional relationship between two return air channel drilling sites and various directional long boreholes in an embodiment of the present invention.

[0032] Figure 3 It is a right view of the positional relationship between two return air channel drilling sites and various directional long boreholes in an embodiment of the present invention.

[0033] Description of reference numerals:

[0034] 1. Bottom rock tunnel; 2. Coal seam; 3. Directional long drilling hole; 4. Tunnel contour line; 5. Grouting hole; 6. Grouting hole influence range; 7. Negative pressure enhancement hole. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] A comprehensive outburst prevention method based on directional drilling, punching, extraction and solidification, specifically comprising the following steps:

[0037] S1. Construct a directional long borehole 3 from the bottom rock tunnel 1 to the target coal seam 2. The positional relationship between the two return air tunnel drilling sites and each directional long borehole in this embodiment is shown in FIG. Figure 1-Figure 3 .

[0038] S2. During the construction of the directional long borehole 3, the relative distance between the roof and the floor of the coal seam in the coal roadway area is detected by using the acoustic wave detection technology to determine the geological structure distribution in the area;

[0039] The geological structure described in step S2 refers to the area where the coal seam thickness changes, the fault area and the fold area. In the determined geological structure area, the coal output from the punching process is increased by 40% to 80%, further improving the pressure relief effect and gas extraction effect.

[0040] S3. After the drilling construction is completed, the drilling tool is withdrawn, and the acoustic wave detection equipment is replaced with a high-pressure jet punching device to withdraw the drill and punch out a cylindrical hole with a certain aperture d.

[0041] S4, after the punching is completed, the screen pipe is lowered and the next borehole is constructed at a distance L, until all the directional long boreholes 3 designed in the target area are completed;

[0042] The hole diameter d and the distance L described in steps S3 and S4 are optimal drilling hole diameters and optimal drilling hole spacings, and the following relationship is satisfied between the two:

[0043] t0=42.69-16.28p0+74.60L-422.57d+11.05p0L-10.05p0d-40.55Ld+260.87d 2

[0044] Where t0 is the extraction reaching standard time, p0 is the initial gas pressure of coal seam, L is the drilling hole spacing, and d is the optimal hole diameter of punching drilling;

[0045] Under the premise of satisfying the above relationship, when the drilling construction cost is the lowest, the corresponding hole diameter d and distance L are the optimal drilling hole diameter and optimal drilling spacing. The drilling construction cost is calculated as follows:

[0046]

[0047] Where TC is the total cost of punching in a given area, L w is the length of the target area, L b is the length of a single drill hole, L is the drill hole spacing, ρ c is the density of coal, a is the cost of flushing out 1 t of coal, and b is the cost of constructing a 1 m conventional borehole.

[0048] S5, constructing several groups of negative pressure enhancement holes 7 from the bottom rock tunnel 1 to the target coal seam 2;

[0049] The negative pressure enhancement holes 7 include several groups, the number of holes in each group is equal to the number of directional long drilling holes 3, the final hole position is connected with the hole formed by punching the directional long drilling holes 3, and the spacing between each group of negative pressure enhancement holes 7 is 50 to 100 meters.

[0050] S6, all directional long boreholes 3 and negative pressure enhancement holes 7 are connected to each other for extraction to eliminate gas internal energy until the extraction reaches the standard;

[0051] The extraction standard mentioned above means that the average residual gas content of the coal seam is less than 8m 3 / t, and the gas pressure at any position of the coal seam in the target area should be less than 0.74MPa. The average residual gas content of the coal seam is obtained by dividing the difference between the total gas reserves and the extracted gas volume in the target area of ​​the coal seam by the volume of the coal body in the target area.

[0052] S7: Unseal two boreholes near the upper and lower contour lines 4 of the tunnel as grouting holes 5, inject grouting into the boreholes under pressure to reinforce the coal body, and improve the strength of the coal body near the tunnel side; the diameter of the grouting influence range 6 of the grouting boreholes is greater than the thickness of the coal seam, so as to construct a safety barrier near the two sides of the tunnel.

[0053] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A comprehensive outburst prevention method based on directional drilling, punching, extraction and solidification, characterized in that: The specific steps include: S1, constructing a directional long borehole (3) from the bottom rock tunnel (1) to the target coal seam (2); S2. During the construction of the directional long drilling hole (3), the relative distance between the roof and the floor of the coal seam in the coal roadway area is detected by using the acoustic wave detection technology to determine the geological structure distribution of the area; S3, after the drilling construction is completed, the drilling tool is withdrawn, and the acoustic wave detection equipment is replaced with a high-pressure jet punching device, and the drilling tool is withdrawn and punched to punch out a cylindrical hole with a certain aperture d; S4, after the punching is completed, the screen pipe is lowered and the next borehole is constructed at a distance L, until all the directional long boreholes (3) designed in the target area are completed; S5, constructing a plurality of groups of negative pressure enhancement holes (7) from the bottom rock tunnel (1) toward the target coal seam (2); S6. All directional long boreholes (3) and negative pressure enhancement holes (7) are connected to conduct drainage to eliminate gas internal energy until the drainage reaches the standard; S7: Unseal two drill holes near the upper and lower contour lines (4) of the tunnel as grouting holes (5), inject grout under pressure into the drill holes to reinforce the coal body, and improve the strength of the coal body near the tunnel wall.

2. A comprehensive outburst prevention method based on directional drilling, punching, extraction and solidification as claimed in claim 1, characterized in that: The geological structure described in step S2 refers to the area where the coal seam thickness changes, the fault area and the fold area. In the determined geological structure area, the coal output from the punching process is increased by 40% to 80%, further improving the pressure relief effect and gas extraction effect.

3. A comprehensive outburst prevention method based on directional drilling, punching, extraction and solidification as claimed in claim 1, characterized in that: The hole diameter d and the distance L described in steps S3 and S4 are optimal drilling hole diameters and optimal drilling hole spacings, and the following relationship is satisfied between the two: t0=42.69-16.28p0+74.60L-422.57d+11.05p0L -10.05p0d-40.55Ld+260.87d 2 Where t0 is the extraction reaching standard time, p0 is the initial gas pressure of coal seam, L is the drilling distance, and d is the optimal hole diameter of punching drilling; Under the premise of satisfying the above relationship, when the drilling construction cost is the lowest, the corresponding hole diameter d and distance L are the optimal drilling hole diameter and optimal drilling spacing. The drilling construction cost is calculated as follows: Where TC is the total cost of punching in a given area, L w is the length of the target area, L b is the length of a single drill hole, L is the drill hole spacing, ρ c is the density of coal, a is the cost of flushing out 1 t of coal, and b is the cost of constructing a 1 m conventional borehole.

4. A comprehensive outburst prevention method based on directional drilling, punching, extraction and solidification as claimed in claim 1, characterized in that: The negative pressure enhancement holes (7) described in step S5 include several groups, the number of holes drilled in each group is equal to the number of directional long drilling holes (3), the final hole position is connected with the hole formed by punching the directional long drilling holes (3), and the spacing between each group of negative pressure enhancement holes (7) is 50 to 100 meters.

5. A comprehensive outburst prevention method based on directional drilling, punching, extraction and solidification as claimed in claim 1, characterized in that: The extraction standard mentioned in step S6 refers to the average residual gas content of the coal seam being less than 8m 3 / t, and the gas pressure at any position of the coal seam in the target area should be less than 0.74MPa. The average residual gas content of the coal seam is obtained by dividing the difference between the total gas reserves and the extracted gas volume in the target area of ​​the coal seam by the volume of the coal body in the target area.

6. A comprehensive outburst prevention method based on directional drilling, punching, extraction and solidification as claimed in claim 1, characterized in that: The diameter of the grouting influence range (6) of the grouting hole (5) described in step S7 is greater than the thickness of the coal seam, so as to construct a safety barrier near the two sides of the tunnel.

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