Method for detecting small structure of coal seam in local gas control process

Abstract

The application provides a method for detecting small structures in a coal seam in a local gas control process, which comprises the following steps: firstly, three drill holes are constructed according to the requirements of the drill cuttings index method of the local gas control; drilling information is collected by using a detection control device of a drilling machine, including drilling specific work, torque and drilling length of a drill bit; when the drilling specific work suddenly decreases and the torque rising time is relatively long, the construction is stopped, and the relative position of the drill bit entering and passing through the coal seam is determined; then, the angle is changed to construct a second group, a third group, a n-th group of drill holes, and the strike, tendency and dip angle of a fault surface are determined according to the coordinate information of the drill bits on the fault surface; finally, the normal and inverse of the fault are determined according to the y coordinate value of the drill bit on the top of the coal seam. The method excavates the while-drilling information of the gas drilling hole, and can accurately identify small fault structures in the coal seam while preventing and controlling gas disasters.

Description

Technical Field

[0001] This invention relates to the field of mine gas control technology, specifically to a method for detecting small coal seam structures during localized gas control. Background Technology

[0002] Coal seams are not simple, homogeneous rock masses. Faults frequently exist within coal seams, where stress concentration occurs in the surrounding rock. This makes the roof and coal seam highly susceptible to breakage and detachment, increasing the difficulty of support and increasing the risk of accidents such as rockbursts, water inrushes, and gas outbursts. Therefore, it is essential to identify coal seam faults in advance during mining. Current exploration methods mainly include 3D seismic methods, electromagnetic wave methods, and directional drilling. However, 3D seismic methods and electromagnetic wave methods are limited by the excessive disturbance signals during coal mining, making accurate exploration difficult. While directional drilling offers high precision, the specialized drilling work disrupts normal mining operations and significantly increases production costs.

[0003] Methane gas is a byproduct of coal mining, and gas-induced accidents are a major threat to safe coal production. Therefore, gas drainage is often carried out in advance during coal seam mining, adhering to the principle of "regional outburst prevention measures first, supplemented by local outburst prevention measures." In localized gas control, drill cuttings methods are commonly used to predict the outburst risk at coal roadway faces, providing a solid engineering foundation for borehole detection technology. If the geological exploration characteristics of these boreholes can be explored, and the three elements of a fault plane—strike, dip, and dip angle—can be determined through gas boreholes, and the orientation of the fault can be judged, faults can be accurately and economically identified. Summary of the Invention

[0004] This invention proposes a method for detecting small coal seam structures during localized gas control, which can accurately identify small fault structures in coal seams. To achieve the above objective, this invention adopts the following technical solution:

[0005] A method for detecting small coal seam structures during localized gas control includes:

[0006] S1. Install a detection and control device on the hydraulic drilling rig to record the drilling specific power and torque of the hydraulic drilling rig in real time;

[0007] S2. Establish a local rectangular coordinate system in the well:

[0008] According to the requirements of the drill cuttings method for local prevention of coal and gas outbursts in coal roadway excavation, borehole 1 is arranged in the middle of the cross-section of the roadway and parallel to the excavation direction of the hydraulic drilling rig. A local rectangular coordinate system is established underground with the starting point of borehole 1 as the origin O, with the horizontal direction of the working face as the x-axis, the vertical direction as the y-axis, and the excavation extension direction as the z-axis.

[0009] S3. According to the regulations for local prevention of coal and gas outbursts during coal roadway excavation, drill holes 2 and 3 are constructed symmetrically on the left and right sides of the lower end of drill hole 1, parallel to the xz plane. Record the angle α2 between drill hole 2 and the xy plane, the angle α3 between drill hole 3 and the xy plane, the angle β1 between drill hole 1 and the xz plane in step S1, and the drilling lengths l1, l2 and l3 of each drill hole.

[0010] S4. Based on the rectangular coordinate system determined in step S2 and the included angle recorded in step S3, and according to the calculation model, record the relative coordinates of the three boreholes in the coal seam in real time. The calculation model is as follows:

[0011]

[0012] Where x is the projection of the drill bit's coordinates onto the x-axis in the local Cartesian coordinate system downhole;

[0013] y - The projection of the drill bit's coordinates onto the y-axis in the local Cartesian coordinate system downhole;

[0014] z - The projection of the drill bit's coordinates onto the z-axis in the local Cartesian coordinate system;

[0015] l1 - Length of borehole 1 drilled in the coal seam; l2 - Length of borehole 2 drilled in the coal seam; l3 - Length of borehole 3 drilled in the coal seam;

[0016] l - The horizontal distance along the X-axis between boreholes 2 and 3 and borehole 1 in the roadway cross-section.

[0017] h - The vertical distance between borehole 2 or borehole 3 and borehole 1 along the Y-axis in the roadway cross section;

[0018] β1-Drill Hole 1 n 'Angle with the xz plane;

[0019] α2-Drill Hole 2 n 'Angle with the xy plane;

[0020] α3-Drill Hole 3 n 'Angle with the xy plane;

[0021] S5. Determine if the rotational speed and torque of the first drilling group are both abnormal; if so, record the coordinates of the drilling hole at this time (x1). 1 y1 1 z1 1 (x2) 1 y2 1 z2 1 (x3) 1 y3 1 z3 1Based on the coordinates of the three boreholes, the fault dip angle θ1 is calculated and step S6 is executed.

[0022] S6. Drilling the second set of boreholes into the coal seam using a hydraulic drilling rig, including borehole 1', borehole 2', and borehole 3'; wherein, borehole 1' is parallel to the tunneling direction and is outside borehole 1, with an angle of β1 / 2 with borehole 1; borehole 2' and borehole 3' are both parallel to the xz plane; borehole 2' is outside borehole 2, with an angle of a2 / 2 with borehole 2; borehole 3' is outside borehole 3, with an angle of a3 / 2 with borehole 3;

[0023] When the rotational speed and torque of the second set of boreholes are both abnormal, calculate and record the coordinates (x1) of the second set of boreholes. 2 y1 2 z1 2 (x2) 2 y2 2 z2 2 (x3) 2 y3 2 z3 2 Based on the coordinates of the three boreholes, the fault dip angle θ2 is calculated; the calculation model for the borehole coordinates of the second group is the same as the calculation model for the borehole coordinates of the first group in step S4.

[0024] S7. Repeat the operation in S6 to drill groups 3 to n, drilling 1. i Parallel to the tunneling direction and in borehole 1 i-1 On the outside of ', with borehole 1 i-1 The included angle is β1 / 2; Drill hole 2 i 'and drilling 3 i All are parallel to the xz plane; Drill 2 i 'In borehole 2 i-1 On the outside, with borehole 2 i-1 The included angle is a2 / 2; Drill hole 3 i 'In borehole 3 i-1 On the outside, with borehole 3 i-1 The included angle is a3 / 2;

[0025] When the rotational speed and torque of the i-th borehole are both abnormal, calculate and record the borehole coordinates (x1) of the i-th borehole. i y1 i z1 i (x2) i y2 i z2 i (x3) i y3 i z3 i ); where i = 3 to n; and calculate the fault dip angle θ. i ;

[0026] Finally, the average fault dip angle was calculated.

[0027] The calculation model for the borehole coordinates of the i-th group is the same as the calculation model for the borehole coordinates of the 1st group in step S4.

[0028] S8. Connect the xz plane projections of all borehole coordinates in sequence, and plot the fault strike line in MATLAB to obtain the fault strike.

[0029] Preferably, the method further includes the following steps:

[0030] S9. Using MATLAB, draw a true dip line perpendicular to the strike line on the fault plane. The direction in which the projection of the true dip line onto the xz plane points downwards along the plane is the dip direction of the coal seam fault.

[0031] Preferably, the method further includes the following steps:

[0032] S10: For borehole 1 to borehole 1 n 1-1 elongated borehole n’ Continue drilling until all boreholes reach the top of the coal seam and record the coordinates y1~y1. n If y1 n If the value is less than y1, the fault is considered a reverse fault; otherwise, it is considered a normal fault.

[0033] Preferably, the expression for the drilling specific work in step S1 is:

[0034] Where F is the drill bit drilling pressure, M is the drill bit torque, N is the drill bit rotation speed, and V is the drill bit speed. d - Drilling rate, R - Drill bit radius.

[0035] Preferably, the length of the borehole 1 in step S2 should be 8-10m.

[0036] Preferably, in step S3, at least three boreholes should be drilled in the coal body ahead of the near-horizontal, gently inclined coal seam working face, and at least two boreholes should be drilled in the inclined or steeply inclined coal seam. The borehole diameter is 42 mm and the borehole depth is 8 to 10 m.

[0037] Preferably, the final drilling points of boreholes 2 and 3 in step S3 should be located 2 to 4 meters outside the outline of the roadway cross-section on both sides.

[0038] Preferably, the formula for calculating the dip angle θ1 of the interrupted layer in step S5 is as follows:

[0039] Preferably, in the calculation model, the values ​​of β1, α2, and α3 are all within the range of (14.0362°, 29.3578°).

[0040] Preferably, the method further includes the following steps:

[0041] S11: If the coal seam is inclined with an inclination angle of σ, calculate the projection prj of the drill pipe perpendicular to the coal seam strike. Significantly smaller than and If the fault is reversed, it is determined to be a reverse fault; otherwise, it is a normal fault.

[0042] Compared with existing technologies, the advantages of this invention are as follows: Drilling information, including drilling power, torque, and drill bit length, is collected using the drilling rig's detection and control device; construction is stopped when the drilling power suddenly drops and the torque rises over a long period, determining the relative position of the drill bit entering and passing through the coal seam; subsequently, the angle is changed to construct the second, third, ..., nth group of boreholes, and the strike, dip, and inclination of the fault plane are determined based on the coordinate information of these drill bits on the fault plane; finally, the orientation of the fault is determined based on the y-coordinate value of the drill bit at the top of the coal seam. This method utilizes drilling information from gas boreholes, enabling precise identification of small fault structures in coal seams while preventing gas disasters. Attached Figure Description

[0043] Figure 1 A flowchart illustrating methods for detecting small coal seam structures during localized gas control;

[0044] Figure 2 This is a top view of the first set of boreholes.

[0045] Figure 3 This is a rear view of the first set of boreholes.

[0046] Figure 4(a) is a schematic diagram of the reverse fault in the front view;

[0047] Figure 4(b) is a schematic diagram of the normal fault in the front view;

[0048] Figure 5 Explanation of the drawing of fault strike and dip lines;

[0049] Figure 6 This is a schematic diagram for identifying normal and reverse faults in inclined coal seams. Detailed Implementation

[0050] The present invention will now be described in more detail with reference to the accompanying drawings, which illustrate preferred embodiments of the invention. It should be understood that those skilled in the art can modify the invention described herein while still achieving its advantageous effects. Therefore, the following description should be understood as being of general knowledge to those skilled in the art and is not intended to limit the invention.

[0051] like Figures 1-5 As shown, a method for detecting small coal seam structures during localized gas control includes:

[0052] S1. Install a detection and control device (composite sensor) on the hydraulic drilling rig to record the drilling specific power and torque of the hydraulic drilling rig in real time.

[0053] The expression for drilling specific work is: Where F is the drill bit drilling pressure, M is the drill bit torque, N is the drill bit rotation speed, and V is the drill bit speed. d - Drilling rate, R - Drill bit radius.

[0054] S2. Establish a local rectangular coordinate system in the well.

[0055] According to the requirements of the drill cuttings method for local prevention of coal and gas outbursts in coal roadway excavation, borehole 1 is arranged in the middle of the cross-section of the excavated roadway and parallel to the excavation direction. A local rectangular coordinate system is established underground with the starting point of borehole 1 as the origin O, with the horizontal direction of the working face as the x-axis, the vertical direction as the y-axis, and the excavation extension direction as the z-axis.

[0056] The length of borehole 1 should be 8-10m.

[0057] S3. According to the regulations for local prevention of coal and gas outbursts during coal roadway excavation, drill holes 2 and 3 are constructed symmetrically on the left and right sides of the lower end of drill hole 1, parallel to the xz plane. Record the angle α2 between drill hole 2 and the xy plane, the angle α3 between drill hole 3 and the xy plane, the angle β1 between drill hole 1 and the xz plane in step S1, and the drilling lengths l1, l2 and l3 of each drill hole.

[0058] The final drilling points of boreholes 2 and 3 should be located 2 to 4 meters outside the outline of the roadway cross-section on both sides.

[0059] In near-horizontal, gently inclined coal seams, at least three boreholes should be drilled into the coal body ahead. In inclined or steeply inclined coal seams, at least two boreholes should be drilled. The borehole diameter is 42 mm and the depth is 8–10 m.

[0060] S4. Based on the rectangular coordinate system determined in step S2 and the included angle recorded in step S3, record the relative coordinates of the three boreholes in the coal seam in real time:

[0061]

[0062] Where x is the projection of the drill bit's coordinates onto the x-axis in the local Cartesian coordinate system downhole;

[0063] y - The projection of the drill bit's coordinates onto the y-axis in the local Cartesian coordinate system downhole;

[0064] z - The projection of the drill bit's coordinates onto the z-axis in the local Cartesian coordinate system;

[0065] l1 - Length of borehole 1 drilled in the coal seam; l2 - Length of borehole 2 drilled in the coal seam; l3 - Length of borehole 3 drilled in the coal seam;

[0066] l - The horizontal distance between boreholes 2 and 3 and borehole 1 along the X-axis in the roadway cross section;

[0067] h - The vertical distance between borehole 2 or borehole 3 and borehole 1 along the Y-axis in the roadway cross section;

[0068] β1-Drill Hole 1 n 'Angle with the xz plane;

[0069] α2-Drill Hole 2 n 'Angle with the xy plane;

[0070] α3-Drill Hole 3 n 'The angle between the plane and the xy plane.

[0071] S5. Determine if the rotational speed and torque of the first set of boreholes are simultaneously abnormal. If the rotational speed and torque of the drilling device (hydraulic drilling rig) are stable and the cuttings desorption index and cuttings volume are both below the critical value for gas outburst, it can be considered that there is no fault or gas outburst danger ahead of the working face detected by the borehole, and mining work can proceed normally. If the borehole torque rises abnormally and the drill specific power drops abnormally, and this continues for a long time, record the coordinates of the borehole at this time (x1). 1 y1 1 z1 1 (x2) 1 y2 1 z2 1 (x3) 1 y3 1 z3 1 Based on the coordinates of the three boreholes, the fault dip angle θ1 is calculated and step S6 is executed.

[0072] The formula for calculating the fault dip angle θ1 is as follows:

[0073] S6. Drill the second set of boreholes into the coal seam using a hydraulic drilling rig, including borehole 1', borehole 2', and borehole 3'; wherein, borehole 1' is parallel to the tunneling direction and located outside borehole 1, with an angle of β1 / 2 to borehole 1; borehole 2' and borehole 3' are both parallel to the xz plane; borehole 2' is located outside borehole 2, with an angle of a2 / 2 to borehole 2; borehole 3' is located outside borehole 3, with an angle of a3 / 2 to borehole 3, as shown below. Figure 2 As shown.

[0074] When the rotational speed and torque of the second set of boreholes are both abnormal (because the fault is a plane, if the first set of boreholes is abnormal, the following sets will definitely be abnormal), that is, when the boreholes reach the fault plane, calculate and record the coordinates (x1) of the second set of boreholes. 2 y1 2 z1 2 (x2) 2 y2 2 z2 2 (x3) 2 y3 2 z3 2 Based on the coordinates of the three boreholes, the fault dip angle θ2 was calculated.

[0075] The calculation model for the borehole coordinates of Group 2 is the same as that for Group 1 in step S4.

[0076] S7. Repeat the operation in S6 to drill groups 3 to n, drilling 1. i Parallel to the tunneling direction and in borehole 1 i-1 On the outside of ', with borehole 1 i-1 The included angle is β1 / 2; Drill hole 2 i 'and drilling 3 i All are parallel to the xz plane; Drill 2 i 'In borehole 2 i-1 On the outside, with borehole 2 i-1 The included angle is a2 / 2; Drill hole 3 i 'In borehole 3 i-1 On the outside, with borehole 3 i-1 The included angle is a3 / 2.

[0077] When the rotational speed and torque of the i-th borehole are both abnormal, i.e. when the borehole reaches the fault plane, calculate and record the coordinates (x1) of the i-th borehole. i y1 i z1 i (x2) i y2 i z2 i (x3) i y3 i z3 i ); where i = 3 to n; and calculate the fault dip angle θ. i That is, record the borehole coordinates (x1) 3 ,y1 3 ,z1 3 (x2) 3 ,y2 3 z2 3 (x3) 3 ,y3 3 z3 3);(x1 4 ,y1 4 ,z1 4 (x2) 4 ,y2 4 z2 4 (x3) 4 ,y3 4 z3 4 );….(x1 n ,y1 n ,z1 n (x2) n ,y2 n z2 n (x3) n ,y3 n z3 n ).

[0078] Finally, the average fault dip angle was calculated.

[0079] The number of drilling groups n during construction must be at least 5.

[0080] The calculation model for the borehole coordinates of group i is the same as that for group 1 in step S4. In the calculation model, the values ​​of α and β are both in the range of (14.0362°, 29.3578°).

[0081] S8. Connect the xz-plane projections of all borehole coordinates sequentially, and plot the fault strike line in MATLAB to obtain the fault strike. That is, based on coordinates (x2... 1 y2 1 (x3) 1 y3 1 (x2) 2 ,,z2 2 (x3) 2 z3 2 );….(x2 n ,,z2 n (x3) n z3 n The strike line of the fault is drawn and its orientation is determined. Furthermore, the strike line can be optimized using cubic spline interpolation.

[0082] like Figure 5 As shown, AB represents the fault strike, CD represents the fault dip, and θ is the projection of the true dip line onto the XZ plane.

[0083] When determining the strike of a fault within a coal seam, it is necessary to first determine the azimuth of the tunneling face; specifically, the azimuth of the underground local coordinate system established in step S2, thereby obtaining the strike of the fault.

[0084] S9. Using MATLAB, draw a true dip line perpendicular to the strike line on the fault plane. The direction in which the projection of the true dip line onto the xz plane points downwards along the plane is the dip direction of the coal seam fault.

[0085] S10: For borehole 1 to borehole 1 n 1-1 elongated borehole n’ Continue drilling until all boreholes reach the top of the coal seam and record the coordinates y1~y1. n If y1 n If the value is less than y1, the fault is considered a reverse fault; otherwise, it is considered a normal fault.

[0086] S11: As Figure 6 As shown, taking a normal fault as an example, the figure includes the tunneling face 4; coal seam 5; fault zone 6; coal seam floor 7; and coal seam roof 8.

[0087] If the coal seam is inclined with a dip angle of σ, then calculate the projection prj of the drilling length perpendicular to the strike of the coal seam. Less than and If the fault is reversed, it is determined to be a reverse fault; otherwise, it is a normal fault.

[0088] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the protection scope of the present invention.

Claims

1. A method for detecting small coal seam structures during localized gas control, characterized in that, include: S1. Install a detection and control device on the hydraulic drilling rig to record the drilling specific power and torque of the hydraulic drilling rig in real time; S2. Establish a local rectangular coordinate system in the well: According to the requirements of the drill cuttings method for local prevention of coal and gas outbursts in coal roadway excavation, borehole 1 is arranged in the middle of the cross-section of the excavated roadway and parallel to the excavation direction. The starting point of borehole 1 is used as the origin O to establish an underground local rectangular coordinate system with the horizontal direction of the working face as the x-axis, the vertical direction as the y-axis, and the excavation extension direction as the z-axis. S3. According to the regulations for local prevention of coal and gas outbursts during coal roadway excavation, drill holes 2 and 3 are constructed symmetrically on the left and right sides of the lower end of drill hole 1, parallel to the xz plane. Record the angle α2 between drill hole 2 and the xy plane, the angle α3 between drill hole 3 and the xy plane, the angle β1 between drill hole 1 and the xz plane in step S1, and the drilling lengths l1, l2 and l3 of each drill hole. S4. Based on the rectangular coordinate system determined in step S2 and the included angle recorded in step S3, the relative coordinates of the three boreholes in the coal seam are recorded in real time according to the calculation model. The calculation model is as follows: , Where x is the projection of the drill bit's coordinates onto the x-axis in the local Cartesian coordinate system downhole; y - The projection of the drill bit's coordinates onto the y-axis in the local Cartesian coordinate system downhole; z - The projection of the drill bit's coordinates onto the z-axis in the local Cartesian coordinate system; l1 - Length of borehole 1 drilled in the coal seam; l2 - Length of borehole 2 drilled in the coal seam; l3 - Length of borehole 3 drilled in the coal seam; l - The horizontal distance along the X-axis between boreholes 2 and 3 and borehole 1 in the roadway cross-section. h - The vertical distance between borehole 2 or borehole 3 and borehole 1 along the Y-axis in the roadway cross section; β1-Drill Hole 1 n 'Angle with the xz plane; α2-Drill Hole 2 n 'Angle with the xy plane; α3-Drill Hole 3 n 'Angle with the xy plane; S5. Determine if the rotational speed and torque of the first group of boreholes are both abnormal; if an abnormality exists, record the coordinates (x1, y1) of the borehole at this time. 1 y1 1 z1 1 (x2) 1 y2 1 z2 1 (x3) 1 y3 1 z3 1 Based on the coordinates of the three boreholes, the fault dip angle θ1 is calculated and step S6 is executed; S6. Drill the second set of boreholes into the coal seam using a hydraulic drilling rig, including borehole 1', borehole 2', and borehole 3'. Among them, borehole 1' is parallel to the tunneling direction and is outside borehole 1, with an angle of β1 / 2 with borehole 1; borehole 2' and borehole 3' are both parallel to the xz plane; borehole 2' is outside borehole 2, with an angle of a2 / 2 with borehole 2; borehole 3' is outside borehole 3, with an angle of a3 / 2 with borehole 3; When the rotational speed and torque of the second set of boreholes are both abnormal, calculate and record the coordinates (x1) of the second set of boreholes. 2 y1 2 z1 2 (x2) 2 y2 2 z2 2 (x3) 2 y3 2 z3 2 Based on the coordinates of the three boreholes, the fault dip angle θ2 is calculated; the calculation model for the borehole coordinates of the second group is the same as the calculation model for the borehole coordinates of the first group in step S4. S7. Repeat the operation in S6 to drill groups 3 to n, drilling 1. i Parallel to the tunneling direction and in borehole 1 i-1 On the outside of ', with borehole 1 i-1 The included angle is β1 / 2; Drill hole 2 i 'and drilling 3 i All are parallel to the xz plane; Drill 2 i 'In borehole 2 i-1 On the outside, with borehole 2 i-1 The included angle is a2 / 2; Drill hole 3 i 'In borehole 3 i-1 On the outside, with borehole 3 i-1 The included angle is a3 / 2; When the rotational speed and torque of the i-th borehole are both abnormal, calculate and record the borehole coordinates (x1) of the i-th borehole. i y1 i z1 i (x2) i y2 i z2 i (x3) i y3 i z3 i ); where i = 3 ~ n; and calculate the fault dip angle θ. i ; Finally, the average fault dip angle was calculated. ; The calculation model for the borehole coordinates of the i-th group is the same as the calculation model for the borehole coordinates of the 1st group in step S4. S8. Connect the xz plane projections of all borehole coordinates in sequence, and plot the fault strike line in MATLAB to obtain the fault strike.

2. The method for detecting small coal seam structures during localized gas control according to claim 1, characterized in that, It also includes the following steps: S9. Using MATLAB, draw a true dip line perpendicular to the strike line on the fault plane. The direction in which the projection of the true dip line onto the xz plane points downwards along the plane is the dip direction of the coal seam fault.

3. The method for detecting small coal seam structures during localized gas control according to claim 2, characterized in that, It also includes the following steps: S10: For borehole 1 to borehole 1 n 1~1 elongated drilling n’ Continue drilling until all boreholes reach the top of the coal seam and record the coordinates y1~y1. n If y1 n If the value is less than y1, the fault is considered a reverse fault; otherwise, it is considered a normal fault.

4. The method for detecting small coal seam structures during localized gas control according to claim 3, characterized in that, The expression for the drilling specific work in step S1 is: ; Where F is the drill bit drilling pressure, M is the drill bit torque, N is the drill bit rotation speed, and V is the drill bit speed. d - Drilling rate, R - Drill bit radius.

5. The method for detecting small coal seam structures during localized gas control according to claim 3, characterized in that, In step S2, the length of borehole 1 should be 8-10 m.

6. The method for detecting small coal seam structures during localized gas control according to claim 1, characterized in that, In step S3, at least three boreholes should be drilled in the coal body ahead of the near-horizontal, gently inclined coal seam working face, and at least two boreholes should be drilled in the inclined or steeply inclined coal seam. The borehole diameter is 42 mm and the depth is 8-10 m.

7. The method for detecting small coal seam structures during localized gas control according to claim 1, characterized in that, In step S3, the final drilling points of boreholes 2 and 3 should be located 2 to 4 meters outside the outline of the roadway cross-section on both sides.

8. The method for detecting small coal seam structures during localized gas control according to claim 1, characterized in that, Step S5: The formula for calculating the dip angle θ1 of the interrupted layer is as follows: .

9. The method for detecting small coal seam structures during localized gas control according to claim 1, characterized in that, In the calculation model, the values ​​of β1, α2, and α3 are all in the range of (14.0362°, 29.3578°).

10. The method for detecting small coal seam structures during localized gas control according to claim 1, characterized in that, It also includes the following steps: S11: If the coal seam is inclined with a dip angle of σ, calculate the projection of the drilling length perpendicular to the strike of the coal seam. , Less than and If the fault is positive, it is determined to be a reverse fault; otherwise, it is a normal fault.

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