A method for detecting small igneous structures in coal seams underground in coal mines

Abstract

The present invention discloses a method for detecting small igneous structures in coal seams underground in coal mines, which is applicable to detecting small igneous structures existing in coal seams near igneous intrusions, and provides strong support for solving problems such as drill sticking and hole spraying caused by small igneous structures during the process of coal mine gas control. By assuming the diameter of small igneous structures in the coal seam, using directional drilling technology to construct directional boreholes in the coal seam, obtaining the working information of the drill bit in real time, determining the position of the contact point between the drill bit and the igneous rock, and thus gradually determining the position information of small igneous structures in the coal seam, the problem that the position and shape of small igneous structures cannot be accurately detected under existing conditions is solved. Finally, the obtained position information is processed by digital image processing software to obtain the position and shape of small igneous structures in the coal seam. This method is simple and has good effects, and has wide practicability in the technical field.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mine safety, and particularly relates to a method for detecting small igneous rock structures in coal seams underground in coal mines based on directional drilling technology. Background Art

[0002] With the increase of the coal seam mining depth in China, the mining conditions are more complex and changeable. Many coal seams have experienced thermal evolution or contact metamorphism related to igneous rock intrusion. After the igneous rock intrusion, with the influence of formation movement and other effects, some igneous rocks may remain independently in the coal seam, forming small igneous rock structures. The existence of small igneous rock structures will cause the enrichment of gas in the coal seam area, affect the implementation of coal mine regional prevention and control technologies, and increase the difficulty of coal resource recovery. Therefore, it is necessary to detect small igneous rock structures in the coal seam before construction in coal mines with igneous rock intrusion.

[0003] The current geophysical exploration level and geological exploration holes are difficult to achieve precise control, and there are the following defects: (1) The most precise high-resolution three-dimensional seismic exploration on the ground can identify faults with a throw of more than 5m and folds with an amplitude of more than 5m, but the detection accuracy of small igneous rock structures (about 3m) is insufficient; (2) The reflected wave ahead detection determines the distribution of geological structures based on the reflected waves of the wave impedance interface in front of the working face, but there is doubt about whether there is such a wave impedance interface for small igneous rock structures; (3) The transient electromagnetic method detection technology widely used in hydrogeological exploration is not applicable because the conductive characteristics of small igneous rock structures are not clear. Therefore, the current commonly used geological detection means are lacking in the detection level of small igneous rock structures. Summary of the Invention

[0004] Technical Problem: The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for detecting small igneous rock structures in coal seams underground in coal mines with simple method, precise control and good effect.

[0005] Technical Solution: To achieve the above purpose, a method for detecting small igneous rock structures in coal seams underground in coal mines of the present invention includes the following steps:

[0006] Step 1: Assume that the diameter of the small igneous rock structure in the coal seam is about 3m;

[0007] Step 2: Drill a directional borehole from the rock roadway at the coal seam floor into the coal seam;

[0008] Step 3: When the drill bit is blocked or the apex angle and direction angle suddenly change during the drilling process, stop drilling, and calculate the spatial coordinates of the drill bit position at this moment using the existing positioning method of the directional drill bit according to the basic elements of the borehole trajectory;

[0009] Step 4: Taking the drill bit position obtained in Step 3 as the center of the bottom surface of a regular hexahedron, establish a directional regular hexahedron with a side length of about 3m;

[0010] Step 5: Construct directional boreholes from the roadway in the coal seam floor in the directions perpendicular to the other five planes of the regular hexahedron except the bottom surface.

[0011] Step 6: During the process of directional boreholes in the five plane directions, when the drill bits for construction in the five planes are blocked during advancement or the apex angle and azimuth angle suddenly change and drilling stops, calculate the spatial coordinates of the drill bit positions at this moment in the five directions respectively according to the basic elements of the borehole trajectory.

[0012] Step 7: Construct directional boreholes from the roadway in the coal seam floor towards the upper and lower eight corner positions of the regular hexahedron respectively.

[0013] Step 8: During the process of directional boreholes in the corner positions, when the drill bits for construction are blocked during advancement or the apex angle and azimuth angle suddenly change and drilling stops, calculate the spatial coordinates of the drill bit positions at this moment in the eight corner positions respectively according to the basic elements of the borehole trajectory.

[0014] Step 9: Input the spatial coordinates of the 14 drill bit positions recorded in Step 3, Step 6 and Step 8 into digital image processing software to obtain the position and shape of the small igneous rock structures.

[0015] In Step 9, if the obtained position and shape of the small igneous rock structures are not satisfactory, adjust the azimuth of the directional boreholes, repeat Steps 5 - 9 to obtain a satisfactory position and shape of the small igneous rock structures.

[0016] In Step 6, the basic elements of the borehole trajectory include the hole - mouth coordinates, the apex angle and azimuth angle of the borehole axis, and the borehole depth.

[0017] Beneficial effects: Due to the adoption of the above - mentioned technical solution, the present invention is applicable to detecting small igneous rock structures existing in the coal seam near igneous rock intrusions, and provides strong support for solving problems such as drill sticking and hole spraying caused by small igneous rock structures during the process of coal mine gas control. It can accurately obtain the shape and position of small igneous rock structures in the coal seam, improve the detection level. Since the existence of small igneous rock structures will cause the enrichment of gas in the coal seam area, it affects the implementation of coal mine regional prevention and control technologies and increases the difficulty of coal resource recovery. Therefore, it is necessary to detect small igneous rock structures in the coal seam before construction in coal mines with igneous rock intrusions. The present invention uses directional drilling technology to construct directional boreholes in the coal seam, obtains the working information of the drill bit in real - time, and determines the position of the contact point between the drill bit and the igneous rock. Thus, gradually determine the position information of small igneous rock structures in the coal seam. Finally, the obtained position information is processed through digital - shape processing software to obtain the position and shape of small igneous rock structures in the coal seam. This method is simple and has good effects, and has wide practicability in the technical field. Description of the Drawings

[0018] Figure 1Schematic diagram of directional drilling for construction on six faces of a hexahedron according to the present invention.

[0019] Figure 2 Schematic diagram of directional drilling for construction on eight vertices of a directional hexahedron according to the present invention.

[0020] Figure 3 Spatial coordinate schematic diagram of the drilling trajectory.

[0021] In the figure: 1. Directional regular hexahedron; 2. Floor rock roadway; 3. Coal seam floor; 4. Coal seam roof; 5 - 10. Directional drill holes for construction on six faces of the directional hexahedron; 11 - 18. Directional drill holes for construction on eight vertices of the directional hexahedron. Detailed implementation method

[0022] The present invention will be further described below in combination with the embodiments in the accompanying drawings:

[0023] A method for detecting small igneous rock structures in coal seams based on directional drilling technology according to the present invention comprises the following specific steps:

[0024] Step 1: Assume that the diameter of small igneous rock structures in the coal seam is about 3m;

[0025] Step 2: Drill a directional drill hole 5 from the already constructed floor rock roadway 2 of the coal seam into the coal seam;

[0026] Step 3: Since the hardness of igneous rock is generally greater than that of coal, when the drill bit is blocked or the apex angle and azimuth angle change suddenly during drilling, it indicates that the drill bit has encountered igneous rock. Stop drilling, and according to the basic elements of the drilling trajectory, calculate the spatial coordinates of the drill bit position at this moment using the existing positioning method of the directional drill bit; the basic elements of the drilling trajectory include the hole mouth coordinates, the apex angle and azimuth angle of the drilling axis, and the drilling depth.

[0027] Step 4: Take the drill bit position recorded in Step 3 as the center of the bottom surface of a regular hexahedron, and establish a directional regular hexahedron with a side length of about 3m;

[0028] Step 5: Drill directional drill holes 6, 7, 8, 9, 10 from the floor rock roadway 2 of the coal seam in directions perpendicular to the other five planes of the regular hexahedron except the bottom surface, as Figure 1 shown;

[0029] Step 6: During the process of drilling the five - plane - direction directional drill holes 6, 7, 8, 9, 10, when the drill bits for construction on the five planes are blocked or the apex angle and azimuth angle change suddenly during forward movement and stop drilling, calculate the spatial coordinates of the drill bit positions at this moment in the five directions respectively according to the basic elements of each drilling trajectory, as Figure 3 shown;

[0030]

[0031] The horizontal distance of point A = L A ·sinθ

[0032] Where:

[0033] X0, Y0, Z0 - coordinates of the orifice;

[0034] X A 、Y A 、Z A - coordinates of point A on the axis of the borehole;

[0035] θ, α - vertical angle and azimuth angle of the axis of the borehole;

[0036]

[0037] Step 7: Construct directional boreholes 11, 12, 13, 14, 15, 16, 17, and 18 from the rock roadway (2) at the bottom of the coal seam in the directions of the eight corner positions of the regular hexahedron, as Figure 2 shown;

[0038] Step 8: During the construction of the directional boreholes at the eight corner positions, when the drill bit is blocked during the forward movement of each construction or the vertical angle or the direction angle changes suddenly, when the drilling stops, calculate the coordinates of the drill bit at this moment, and calculate the spatial coordinates of the drill bit positions at the eight corner positions at this moment according to the basic elements of the borehole trajectory. The eight corner positions calculated at this time are the actual positions where the directional drill bit contacts the igneous rock. Being ahead of or lagging behind the preset positions 11, 12, 13, 14, 15, 16, 17, and 18, the positions in the figure only serve to give a direction for the directional drilling. Therefore, which point to stop at specifically should be determined according to the actual situation;

[0039] Step 9: Input the 14 drill bit coordinate data obtained in Step 3, Step 6, and Step 8 into digital image processing software to obtain the position and shape of the small igneous rock structure.

[0040] If you are not satisfied with the obtained position and shape of the small igneous rock structure, you can readjust the azimuth of the directional borehole and repeat Steps 5 - 9 to obtain a satisfactory position and shape of the small igneous rock structure.

Claims

1. A method for detecting small igneous structures in coal seams underground in coal mines, characterized in that , including the following steps: Step 1: Assume that the diameter of the igneous rock small structure in the coal seam is 3m; Step 2: Construct a directional borehole (5) from the roadway in the rock at the coal seam floor (2) into the coal seam; Step 3: When the drill bit is blocked or the apex angle and azimuth angle suddenly change during drilling, stop drilling, and calculate the spatial coordinates of the drill bit position at this moment using the existing positioning method of the directional drill bit according to the basic elements of the borehole trajectory; Step 4: Taking the drill bit position obtained in Step 3 as the center of the bottom surface of a regular hexahedron, establish a directional regular hexahedron with a side length of 3m; Step 5: Construct directional boreholes from the roadway in the rock at the coal seam floor (2) in the directions perpendicular to the other five planes of the regular hexahedron except the bottom surface; Step 6: During the process of directional boreholes in the five plane directions, when the drill bits for construction in the five planes are blocked or the apex angle and azimuth angle suddenly change during advancement and stop drilling, calculate the spatial coordinates of the drill bit positions at this moment in the five directions respectively according to the basic elements of the borehole trajectory; Step 7: Construct directional boreholes from the roadway in the rock at the coal seam floor (2) in the directions of the upper and lower eight corner positions of the regular hexahedron respectively; Step 8: During the process of directional boreholes in the eight corner positions, when the drill bit for each construction is blocked or the apex angle or azimuth angle suddenly changes during advancement and stops drilling, calculate the spatial coordinates of the drill bit positions at this moment in the eight corner positions respectively according to the basic elements of the borehole trajectory; Step 9: Input the 14 spatial coordinates of the drill bit positions recorded in Step 3, Step 6, and Step 8 into digital image processing software to obtain the position and shape of the igneous rock small structure.

2. The method for detecting small igneous rock structures in coal seams underground in coal mines according to claim 1, wherein: In Step 9, if the obtained position and shape of the igneous rock small structure are not satisfactory, adjust the azimuth of the directional borehole, and repeat Steps 5 - 9 to obtain a satisfactory position and shape of the igneous rock small structure.

3. A method for detecting small igneous rock structures in coal seams underground in coal mines according to claim 1, characterized in that: In Step 6, the basic elements of the borehole trajectory include the hole mouth coordinates, the apex angle and azimuth angle of the borehole axis, and the borehole depth.

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