A variable-direction jet slit cutting device and a method for jet slit cutting along coal seams in cross-layer boreholes.

Abstract

This invention belongs to the field of coal mine gas control, and particularly relates to a variable-direction jet slit-cutting device and a method for jet slit-cutting along coal seams through boreholes. The device includes a slitter body and a nozzle base located within the slitter body. The nozzle base is equipped with a nozzle, and the slitter body contains a drive control component for controlling the rotation of the nozzle base around its own axis. The method for jet slit-cutting along coal seams through boreholes mainly involves dynamically adjusting the rotation angle of the nozzle base around its axis during jet slit-cutting construction, based on coal seam strike parameters and the horizontal rotation angle of the drill rod, to ensure that the plane of the slit is parallel to the coal seam plane. This invention can adjust the nozzle angle to slit along the coal seam plane even when the borehole is oblique to the coal seam, and adjusts the nozzle angle in real time as the drill rod rotates, forming a disc-shaped slit parallel to the coal seam plane, improving the permeability enhancement effect of the slit-cutting and reducing the number of boreholes required for slit-cutting.

Description

Technical Field

[0001] This invention belongs to the field of coal mine gas control, and particularly relates to a variable-direction jet slit cutting device and a method for jet slit cutting along coal seams through a cross-layer borehole. Background Technology

[0002] In my country, most high-gas and outburst-prone coal seams are low-permeability coal seams, facing difficulties in gas extraction during gas control. Water jet fracturing can create slots within the coal seam, causing deformation and stress release, thus relieving pressure, increasing permeability, and improving gas extraction efficiency. Simultaneously, water jet fracturing can be used for pre-installed slots in the mine roof to force roof breaking, addressing rockbursts and excessive gas levels in the upper corners of the working face caused by large-area roof overhangs in the goaf.

[0003] Currently, water jet nozzles have various structures. Based on nozzle position and structure, they are generally classified as lateral vertical nozzles, front-end straight nozzles, multi-angle perforation nozzles, and rear-end slag discharge nozzles. Based on nozzle form, they can be divided into straight jet nozzles and rotating jet nozzles. However, existing nozzles are all fixed or rotating around the drill rod axis, only allowing for fixed-angle jet slit cutting based on the nozzle structure. The resulting slits are either disc-shaped perpendicular to the drill rod axis or rectangular slits containing the drill rod axis, with the slit position dependent on the drill rod axis. However, in actual coal mine operations, due to the influence of coal seam occurrence conditions and borehole layout parameters, the percentage of boreholes perpendicularly intersecting the plane of the coal seam near the coal-bearing point is relatively small. Depending on the coal seam dip, strike, borehole dip angle, and borehole azimuth angle, in actual construction, boreholes and coal seams are mostly obliquely intersecting.

[0004] When slotting a borehole at an oblique angle to the coal seam, the slot size is projected onto the plane of the coal seam rather than the actual slot size. This size is smaller or much smaller than the actual slot size. Under the same slotting capacity, the reduced range of influence will lead to unexploded or unfinished mining or an increase in the amount of drilling work. On the other hand, when the coal seam is thin, the slotting range of the borehole cannot continue to improve permeability after reaching the boundary of the top and bottom plates of the working coal seam, which limits the slotting capacity of the slotting device.

[0005] In addition, water jet technology can also be applied to forced roof cutting operations in the goaf of the working face. However, since the angle of the cutting nozzle is fixed, the cutting operation can only form a roof groove perpendicular to the borehole axis. Since the roof cutting operation is generally carried out from the drilling site in front of the working face towards the goaf, the conventional water jet nozzle operation method causes the cut groove to form a normal fault interface in the roof above the working face, which is not conducive to the later development of cracks and collapse of the roof. Summary of the Invention

[0006] To address the above problems, the present invention aims to provide a variable-direction jet slitting device to change the angle between the slit groove and the axis of the slitting device or the borehole axis during the jet slitting process. In addition, the present invention also provides a method for jet slitting along a coal seam in a cross-layer borehole using the above-mentioned device, so as to ensure that when the borehole is oblique to the coal seam, the slit groove of the jet slitting in the borehole is parallel to the coal seam.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is: a variable-direction jet slitting device, comprising: a slitting device body and a nozzle base located inside the slitting device body, wherein the axis of the nozzle base is perpendicular to the axis of the slitting device body, and a nozzle is provided on the side wall of the nozzle base, the nozzle matching a through hole on the surface of the slitting device body; one end of the slitting device body is an open end for introducing a high-pressure fluid medium, the open end being connected to a fluid channel inside the slitting device body, the fluid channel being rotatably connected to the nozzle base through a rotary seal, and a drive control component is also provided inside the slitting device body, the drive control component being used to control the nozzle base to rotate around its own axis;

[0008] Furthermore, the drive control component includes: a motor disposed within the slit cutter body, the output shaft of the motor being fixedly connected to the input end of a transmission mechanism located in a groove on the side wall of the slit cutter body, and the output end of the transmission mechanism being fixedly connected to a nozzle base;

[0009] Furthermore, the drive control component also includes a first angle sensor, a pressure sensor, and a motor controller. The first angle sensor is used to detect the rotation angle of the motor and transmit the signal to the controller outside the entire device. The pressure sensor is used to measure the pressure of the high-pressure fluid medium in the fluid channel and transmit the signal to the controller. The controller controls the rotation speed and rotation direction of the motor through the motor controller.

[0010] Furthermore, sealing bolts are provided between the outer wall of the slit cutter body and the fluid channel;

[0011] Furthermore, the groove is provided with a cover plate, which is fixed to the groove by bolts;

[0012] Furthermore, the non-open end of the slit cutter body is provided with an orienter. The orienter has a cavity inside, one end of which has an opening and an internal thread for threaded connection and fixation to the outer wall of the slit cutter body. The other end of the cavity has a rotating shaft fixedly connected to the orienter. The axis of the rotating shaft coincides with the axis of the orienter. The rotating shaft has a connecting rod that can rotate relative to it. The connecting rod is perpendicular to the rotating shaft and consists of a straight rod section and an annular section. One end of the straight rod section of the connecting rod is provided with a counterweight. The annular section of the connecting rod can rotate relative to the rotating shaft. A second angle sensor is also provided at the connection between the rotating shaft and the connecting rod. The second angle sensor is used to detect the rotation angle of the connecting rod and transmit the signal to the controller.

[0013] Furthermore, a spring retainer is provided inside the cavity of the directional device.

[0014] The present invention also provides a method for jet cutting along a coal seam in a cross-layer borehole using the above-mentioned variable-direction jet cutting device, comprising the following steps:

[0015] Step 1: Drill holes in the coal seam using a drilling rig and drill rod;

[0016] Step 2: Collect coal seam strike parameters, including: coal seam dip, coal seam dip angle, borehole dip angle, and azimuth angle at the point where the borehole encounters coal.

[0017] Step 3: Use a high-pressure pump, high-pressure hose, drilling rig, drill rod, and variable-direction jet slitting device to perform jet slitting in the borehole to create a slit.

[0018] Step 4: During the jet cutting process, based on the coal seam strike parameters collected in Step 2 and the horizontal rotation angle of the drill rod, dynamically adjust the rotation angle of the nozzle base around the axis in the variable-direction jet cutting device to ensure that the plane of the slot is parallel to the coal seam plane.

[0019] Step 5: After the slit is cut, turn off the high-pressure pump, depressurize, adjust the number of drill rods, and proceed to the next slit until all slits are constructed. Then remove the drill rods.

[0020] The beneficial effects of this invention are as follows: This invention can adjust the angle between the nozzle axis and the drill rod axis, and perform slotting along the plane of the coal seam when the borehole is obliquely intersecting the coal seam. The nozzle angle is adjusted in real time as the drill rod rotates, forming a disc-shaped slot parallel to the coal seam plane. This can improve the permeability enhancement effect of slotting in coal seam permeability enhancement and pumping operations, reduce the amount of ineffective slotting work, and thus reduce the number of slotted boreholes. At the same time, it can be used in guide slot controlled fracturing operations, adjusting the slot angle according to the fracturing direction requirements. Attached Figure Description

[0021] Figure 1This is a structural cross-sectional view of a variable-direction jet slit cutting device according to the present invention;

[0022] Figure 2 This is a cross-sectional view of the orienter of the present invention;

[0023] Figure 3 A schematic diagram of the structure when using the variable-direction jet slitting device of the present invention for slitting operations;

[0024] In the diagram: 1. Slotter body; 2. Nozzle base; 3. Nozzle; 4. Fluid channel; 5. Rotary seal; 6. Sealing bolt; 7. Motor; 8. Front gear; 9. Rear gear; 10. Gear shaft; 11. First angle sensor; 12. Pressure sensor; 13. Motor controller; 14. Cover plate; 15. Bolt; 16. Orienter; 17. Cavity; 18. Rotating shaft; 19. Connecting rod; 20. Counterweight; 21. Second angle sensor; 22. Spring retainer; 23. Coal seam; 24. Drill hole; 25. Drill rig; 26. Drill rod; 27. High-pressure hose; 28. High-pressure pump; 29. ​​Slot; 30. Controller. Detailed Implementation

[0025] The technical solution adopted by the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0026] First, the present invention provides a variable-direction jet slit cutting device, such as... Figure 1 As shown, the variable-direction jet slitting device includes: a slitting device body 1 and a nozzle base 2 located inside the slitting device body 1. The axis of the nozzle base 2 is perpendicular to the axis of the slitting device body 1. A nozzle 3 is provided on the side wall of the nozzle base 2. The nozzle 3 matches the through hole on the surface of the slitting device body 500.

[0027] One end of the slit cutter body 1 is an open end for introducing high-pressure fluid medium. The open end is rotatably connected to the nozzle base 2 through the fluid channel 4 inside the slit cutter body 1. The slit cutter body 1 is also provided with a drive control component, which is used to control the nozzle base 2 to rotate around its own axis.

[0028] Specifically, in this embodiment, a high-pressure fluid medium, such as high-pressure water, is injected into the open end of the slit cutter body 1. After entering the slit cutter body 1, the high-pressure fluid medium passes through the fluid channel 4 and is ejected from the through hole of the slit cutter body 1 through the slit nozzle 3 on the nozzle base 2 to perform jet slit cutting. During the process, the nozzle base 2 can be rotated around its own axis by the drive control component, thus realizing the variable direction jet slit cutting function of the entire device. Since the axis of the nozzle base 2 is parallel to the radial axis of the slit cutter body 1, when the entire device is slitting in the drill hole 24, the relative angle between the slit groove 29 formed by the jet slit and the axis of the slit cutter body 1 can be adjusted by rotating the nozzle base 2.

[0029] In this embodiment, as a preferred technical solution, the slit nozzle base 2 is rotatably connected to the fluid channel 4 through the rotary seal 5. That is, when the slit nozzle base 2 rotates, the rotary seal 5 ensures its connectivity and sealing with the fluid channel 4.

[0030] Furthermore, a sealing bolt 6 is provided between the outer wall of the slit cutter body 1 and the fluid channel 4. The sealing bolt 6 is used to seal the fluid channel 4 after the rotary seal 5 is installed or repaired.

[0031] The drive control component includes: a motor 7 disposed inside the slit cutter body 1, the output shaft of the motor 7 being fixedly connected to the input end of a transmission mechanism located in a groove on the side wall of the slit cutter body 1, and the output end of the transmission mechanism being fixedly connected to the nozzle base 2.

[0032] Specifically, the motor 7 uses a transmission mechanism to transmit the rotational torque of its output shaft, which in turn drives the nozzle base 2 to rotate relative to the radial axis of the slit cutter body 1.

[0033] In this embodiment, the transmission mechanism is preferably a two-stage gear transmission system. The two-stage gear transmission system is provided with a front gear 8 that is keyed to the output shaft of the motor 7. The front gear 8 meshes with a rear gear 9. The rear gear 9 meshes with a gear shaft 10. The gear shaft 10 is fixedly connected to the nozzle base 2 and arranged coaxially.

[0034] When the motor 7 drives the front gear 8 to rotate, the rear gear 9, which meshes with the front gear 8, transmits torque to the gear shaft 10, causing the gear shaft 10 to rotate around its own axis, thereby driving the nozzle base 2 to rotate around its axis.

[0035] Furthermore, the drive control assembly also includes a first angle sensor 11, a pressure sensor 12, and a motor controller 13. The first angle sensor 11 is used to detect the rotation angle of the motor 7 and transmit the signal to the controller 30 outside the entire device. The pressure sensor 12 is used to measure the pressure of the high-pressure fluid medium in the fluid channel 4 and transmit the signal to the controller 30 outside the entire device. The controller 30 controls the rotation speed and rotation direction of the motor 7 through the motor controller 13.

[0036] In this embodiment, the pressure signal of the high-pressure jet in the fluid channel 4 can be transmitted to the controller 30 for monitoring by the pressure sensor 12 to determine the start-up time of the entire device. After the high-pressure jet reaches the preset pressure, the controller 30 controls the output shaft of the motor 7 to rotate by controlling the motor controller 13, and detects the rotation angle of the motor 7 by the first angle sensor 11 and feeds it back to the controller 30 for correction, thereby achieving the purpose of accurately controlling the rotation angle of the slit nozzle 3.

[0037] Furthermore, the groove is provided with a cover plate 14, which is connected and fixed to the groove 31 by bolts 15, thereby sealing the entire transmission mechanism inside the groove and facilitating maintenance of the transmission mechanism.

[0038] In addition, the other end of the slit cutter body 1 is provided with an orienter 16, such as Figure 2 As shown, the orienter 16 is sleeved on the slit cutter body 1 and fixed to the end of the slit cutter body 1 by a threaded connection;

[0039] Specifically, the orienter 16 has a cavity 17 inside. One end of the cavity 17 has an opening and an internal thread, which is used to connect and fix with the external thread at the end of the slit cutter body 1. The other end of the cavity 17 has a rotating shaft 18 fixedly connected to the orienter 16. The axis of the rotating shaft 18 coincides with the axis of the orienter 16. The end of the rotating shaft 18 has a connecting rod 19 that can rotate relative to it. The connecting rod 19 is perpendicular to the rotating shaft 18. The connecting rod 19 consists of a straight rod section and an annular section. One end of the straight rod section of the connecting rod 19 has a counterweight 20. The annular section of the connecting rod 19 can rotate relative to the rotating shaft 18. A second angle sensor 21 is also provided at the connection between the rotating shaft 18 and the connecting rod 19. The second angle sensor 21 is used to detect the rotation angle of the connecting rod 19 and transmit this signal to the controller 30.

[0040] Specifically, in this embodiment, the orienter 16 is used to detect the attitude of the variable-direction jet slit device in the borehole 24. That is, when the variable-direction jet slit device changes angle in the borehole 24, the connecting rod 19 in the cavity 17 of the orienter 16 rotates around the rotation axis 18 under the influence of the counterweight 20. The second angle sensor 21 is used to detect the rotation angle of the connecting rod 19 and transmit this information to the controller 30, so that the controller 30 can control the jet spray angle of the variable-direction jet slit device according to the attitude of the variable-direction jet slit device in the borehole 24.

[0041] Furthermore, a spring retainer 22 is provided in the cavity 17 of the orienter 16, which is used to limit the second angle sensor 21.

[0042] In addition, such as Figure 3 As shown, the present invention utilizes the aforementioned variable-direction jet slit cutting device to also provide a method for jet slit cutting along a coal seam in a cross-layer borehole. When the coal seam 23 is obliquely intersecting the borehole 24, during jet slit cutting operations within the borehole 24, the slit groove 29 of the jet slit is ensured to be parallel to the coal seam 23. The construction method includes the following steps:

[0043] Step 1: Drill hole 24 in coal seam 23 using drilling rig 25 and drill rod 26;

[0044] Specifically, in this embodiment, the drill rod 26 can be rotated by the drill rig 25 to drill a hole 24 in the coal seam 23. After cleaning the hole 24, the drill rod 26 is withdrawn.

[0045] Step 2: Collect coal seam strike parameters, including: coal seam dip β, coal seam dip angle γ, borehole dip angle δ, and borehole azimuth angle η at the coal-bearing point in borehole 24;

[0046] In step 2, the coal seam strike parameter is selected such that the angle between the actual strike of coal seam 23 and the due north direction is less than 180°.

[0047] Step 3: Use the high-pressure pump 28, high-pressure hose 27, drilling rig 25, drill rod 26 and variable-direction jet slitting device to perform jet slitting in the borehole 24 to construct the slit groove 29;

[0048] Specifically, in this embodiment, a high-pressure hose 27 can be used to connect the open end of the slit cutter body 1 to the high-pressure pump 28, and the entire variable-direction jet slit cutter device can be fixed on the drill rod 26 of the drill rig 25. The drill rod 26 can be inserted into the borehole 24 until the variable-direction jet slit cutter device reaches the designed slit position.

[0049] When the high-pressure water injected into the variable-direction jet cutting device through the high-pressure pump 28 reaches the pressure of the jet cutting, the variable-direction jet cutting device is started and the drill rod 26 is rotated to begin constructing the slot 29 in the coal seam 23.

[0050] Step 4: During the jet cutting process, based on the coal seam direction parameters collected in Step 2 and the rotation of the drill rod 26 in Step 3, dynamically adjust the rotation angle B of the nozzle base 2 of the variable direction jet cutting device around the axis to ensure that the plane of the slot 29 is parallel to the plane of the coal seam 23.

[0051] Specifically, when drill pipe 26 rotates clockwise, it generates a rotation angle. At that time, the angle K of the axis of nozzle 3 relative to the horizontal plane satisfies the following formula:

[0052]

[0053] In formula (1): K is the angle of inclination of the axis of nozzle 3 relative to the horizontal plane;

[0054] The angle produced when drill rod 26 rotates clockwise is... Cycles between 0° and 360°;

[0055] δ is the drilling inclination angle, with the horizontal plane at the opening point of borehole 24 as the reference. When the final point of borehole 24 is on the horizontal plane, the drilling inclination angle δ is positive, and when the final point is below the horizontal plane, the drilling inclination angle δ is negative. |δ| represents the absolute value of the drilling inclination angle δ.

[0056] The pseudo-dip angle C of the coal seam corresponding to the axis of nozzle 3 satisfies the following formula:

[0057]

[0058] In formula (2): C is the pseudo dip angle of the coal seam corresponding to the axis of nozzle 3;

[0059] β represents the dip of the coal seam at the coal-bearing point in borehole 24;

[0060] γ is the dip angle of the coal seam at the coal-bearing point in borehole 24;

[0061] η is the borehole azimuth angle;

[0062] According to formulas (1)-(2), in order to ensure that the plane of the slot 29 is parallel to the plane of the coal seam 23, when the drill rod 26 rotates clockwise and generates an angle... At that time, the rotation angle B of the nozzle base 2 about its axis and the rotation angle of the drill rod 26 are... Satisfy the following formula:

[0063]

[0064] In this embodiment, the coal seam orientation parameters collected in step 2 can be input into the controller 30. The controller 30 controls the motor 7 to dynamically adjust the rotation angle B of the nozzle base 2 around the axis according to the formula (3) and the first angle sensor 11, pressure sensor 12 and motor controller 13.

[0065] Step 5: After the slit is cut, turn off the high-pressure pump 28, depressurize and adjust the number of drill rods 26, and cut the slit at the next position until all slits 29 are completed, then remove the drill rods 26.

[0066] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, are covered within the scope of protection of the present invention.

Claims

1. A variable-direction jet slit cutting device, comprising: The slit cutter body (1) and the nozzle base (2) located inside the slit cutter body (1) are provided with a nozzle (3) on the side wall of the nozzle base (2) and the nozzle (3) is matched with the through hole inside the slit cutter body (1). One end of the slit cutter body (1) is an open end for introducing high pressure fluid medium. The open end is connected to the fluid channel (4) inside the slit cutter body (1). The fluid channel (4) is rotatably connected to the nozzle base (2) through a rotary seal (5). The slit cutter body (1) is characterized in that a drive control component is also provided inside the slit cutter body (1). The drive control component is used to control the nozzle base (2) to rotate around its own axis. The drive control component includes: a motor (7) disposed in the slit cutter body (1), the output shaft of the motor (7) being fixedly connected to the input end of a transmission mechanism located in a groove on the side wall of the slit cutter body (1), and the output end of the transmission mechanism being fixedly connected to the nozzle base (2); The transmission mechanism is a two-stage gear transmission system. The two-stage gear transmission system is provided with a front gear (8) that is keyed to the output shaft of the motor (7). The front gear (8) meshes with the rear gear (9). The rear gear (9) meshes with the gear shaft (10). The gear shaft (10) is fixedly connected to the nozzle base (2) and arranged coaxially. The drive control assembly further includes: a first angle sensor (11), a pressure sensor (12), and a motor controller (13). The first angle sensor (11) is used to detect the rotation angle of the motor (7) and transmit the signal to the controller (30) outside the entire device. The pressure sensor (12) is used to detect the pressure of the high-pressure fluid medium in the fluid channel (4) and transmit the signal to the controller (30). The controller (30) controls the rotation speed and rotation direction of the motor (7) through the motor controller (13).

2. The variable-direction jet slit cutting device according to claim 1, characterized in that, A sealing bolt (6) is provided between the outer wall of the slit cutter body (1) and the fluid channel (4).

3. The variable-direction jet slit cutting device according to claim 2, characterized in that, The groove is provided with a cover plate (14), which is fixed to the groove by bolts (15).

4. The variable-direction jet slit cutting device according to claim 3, characterized in that, The non-open end of the slit cutter body (1) is provided with an orienter (16). The orienter (16) has a cavity (17) inside. One end of the cavity (17) is open and has an internal thread for threaded connection and fixation to the outer wall of the slit cutter body (1). The other end of the cavity (17) has a rotating shaft (18) fixedly connected to the orienter (16). The axis of the rotating shaft (18) coincides with the axis of the orienter (16). The rotating shaft (18) is provided with a connecting rod that can rotate relative to it. 19), the connecting rod (19) is perpendicular to the rotating shaft (18), the connecting rod (19) is composed of a straight rod section and an annular section, one end of the straight rod section of the connecting rod (19) is provided with a counterweight (20), the annular section of the connecting rod (19) can rotate relative to the rotating shaft (18), and a second angle sensor (21) is also provided at the connection between the rotating shaft (18) and the connecting rod (19). The second angle sensor (21) is used to detect the rotation angle of the connecting rod (19) and transmit this signal to the controller (30).

5. The variable-direction jet slit cutting device according to claim 4, characterized in that, The cavity (17) of the directional device (16) is provided with a spring retainer (22).

6. A method for jet-cutting along a coal seam in cross-layer drilling using the variable-direction jet-cutting device according to any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Drill holes (24) in the coal seam (23) using a drilling rig (25) and drill rod (26); Step 2: Collect coal seam strike parameters, which include: coal seam dip β, coal seam dip angle γ, borehole dip angle δ, and azimuth angle η at the coal-bearing point of borehole (24); Step 3: Use a high-pressure pump (28), a high-pressure hose (27), a drill (25), a drill rod (26), and a variable-direction jet slitting device to perform jet slitting in the borehole (24) to construct a slit groove (29); Step 4: During the jet cutting process, based on the coal seam strike parameters collected in Step 2 and the rotation angle of the drill pipe (26), The rotation angle B of the nozzle base (2) of the variable direction jet cutting device around the axis is dynamically adjusted to ensure that the plane of the slot (29) is parallel to the plane of the coal seam (23); Step 5: After the slit is cut, turn off the high pressure pump (28), depressurize and adjust the number of drill rods (26) to cut the slit at the next position until all the slots (29) at all positions are completed and remove the drill rods (26). In step 4, the rotation angle B of the nozzle base (2) around the axis and the rotation angle of the drill rod (26) are... Satisfy the following formula: In formula (1): The angle produced when the drill rod (26) rotates clockwise, i.e. Cycles between 0° and 360°; β represents the dip of the coal seam at the point where the coal was encountered in borehole (24); γ is the dip angle of the coal seam at the point where coal is encountered in borehole (24); δ is the drilling inclination angle, and the horizontal plane at the opening point of the borehole (24) is used as the reference. When the end point of the borehole (24) is on the horizontal plane, the drilling inclination angle δ is positive, and when the end point of the borehole (24) is below the horizontal plane, the drilling inclination angle δ is negative. |δ| represents the absolute value of the drilling inclination angle δ. η is the borehole azimuth angle.

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