Gob-side entry retaining long-distance directional fracturing method

Abstract

The invention discloses a long-distance directional fracturing method for gob-side entry retaining, which comprises the following steps of: excavating a directional drilling machine chamber before a primary stoping side of a working surface of the gob-side entry retaining or before the working surface is stoped by a certain distance, arranging a directional drilling machine for a coal mine in the directional drilling machine chamber, and arranging a directional drilling machine for the coal mine along a gob side of a support body beside the gob-side entry retaining roadway; super-long directional drilling is constructed in a roof rock stratum in the horizontal direction, and dense advanced pressure relief holes in the horizontal direction are formed; the super-long directional drill holes are formed in sequence from top to bottom and cover the whole roof rock stratum needing pressure relief. The problems that in the prior art, drilling equipment needs to be frequently transferred, and the drilling operation speed is low are solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coal mining, and particularly relates to a long-distance directional fracturing method for gob-side entry retaining. BACKGROUND

[0002] As a core technology of non-pillar mining, the gob-side entry retaining technology can significantly reduce the amount of roadway excavation and improve the efficiency of coal mining, and is of great significance to gas control and mine safety production. The core goal is to retain the original roadway to continue to use it as the return airway or transportation roadway of the next working face.

[0003] However, due to the dual effects of excavation and mining dynamic pressure, the mine pressure problem of the retained roadway is extremely prominent. Studies have shown that after the working face is mined, the roof of the goaf collapses from bottom to top, and the main roof will form an "O-X" type break due to periodic pressure, and continue to rotate and sink towards the goaf. Because the collapse of the main roof cannot effectively fill the goaf, the top of the retained roadway goaf is prone to form a cantilever structure, causing the surrounding rock of the gob-side entry retaining to bear a huge pressure, leading to serious deformation of the roadway and restricting the application effect of the technology.

[0004] To weaken the influence of the roof collapse of the goaf on the retained roadway, the current mainstream technology is the roof cutting and pressure relief method, including blasting roof cutting and pressure relief, water pressure fracturing roof cutting and pressure relief, etc. The on-site construction logic is as follows: an advanced directional drilling hole with a specific angle and height is drilled in the roof on the goaf side of the roadway in front of the working face, and then the main roof rock layer above the roadway is cut off by blasting or water pressure fracturing, to ensure that the roof collapses in time after the working face is mined.

[0005] However, the existing technology has the following obvious defects: (1) the drilling equipment needs to be frequently transferred, resulting in low construction efficiency; (2) the drilling operation speed is slow, and the labor intensity of workers is large. Therefore, the existing technology cannot match the advancing speed of the working face, which seriously affects the overall progress and benefit of the gob-side entry retaining project. SUMMARY

[0006] The purpose of the present application is to provide a long-distance directional fracturing method for gob-side entry retaining, which solves the problems of frequent transfer of drilling equipment and slow drilling operation speed in the existing technology.

[0007] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows: a long-distance directional fracturing method for gob-side entry retaining, in which a directional drilling machine chamber is excavated at the working face before a single mining of the working face, a directional drilling machine for coal mines is arranged in the directional drilling machine chamber, a super-long directional drilling hole is drilled in the horizontal direction along the roof rock layer on the goaf side of the support body beside the retained roadway, and a dense advanced pressure relief hole in the horizontal direction is formed; the super-long directional drilling hole is drilled from top to bottom in sequence, covering the entire roof rock layer that needs to be relieved.

[0008] The technical solution of the present invention also has the following characteristics: As a preferred embodiment of the present invention, the method for long-distance directional fracturing along the goaf is implemented according to the following steps: Step 1: According to the design, excavate the directional drilling rig chamber in the coal wall of the roadway in the working face; then install and fix the main unit of the coal mine directional drilling rig in the directional drilling rig chamber, connect the drill rod, power head and hydraulic system, and complete the equipment foundation deployment.

[0009] Step 2: Debug the measurement while drilling (MWD) system to ensure stable signal transmission and accurate data detection; Step 3: Construct the initial borehole and use directional drilling to guide the borehole trajectory into the designed orientation path; Step 4: Control the directional drilling to continue drilling along the designed trajectory by adjusting the drill bit attitude in real time; Step 5: Ensure equipment operation and drilling trajectory accuracy throughout the process, and handle unexpected problems simultaneously; Step 6: When the directional drilling reaches the designed final hole depth, stop drilling, complete the final hole measurement through the MWD system, record the final hole coordinates, depth and other parameters, and confirm whether it meets the design requirements; repeat the above process until the designed number of holes is completed. Step 7: Move the machine to the next directional drilling chamber and repeat the above steps until all the roadways and haulages in the working face have been drilled.

[0010] As a preferred embodiment of the present invention, the directional drilling rig for coal mines can drill a hole up to 1000m in a single operation.

[0011] As a preferred embodiment of the present invention, the hole spacing is 30 cm-50 cm; the holes can be arranged in a single row or multiple rows from top to bottom.

[0012] As a preferred technical solution of the present invention, the boreholes can be arranged in multiple rows from top to bottom.

[0013] As a preferred embodiment of the present invention, the spacing between the drill holes in each row may be the same or different.

[0014] As a preferred embodiment of the present invention, the spacing between the holes in each row may be the same or different.

[0015] As a preferred technical solution of the present invention, a hydraulic fracturing method is adopted, in which water is injected into the borehole, and a cutting seam is formed in the borehole axis by high-pressure water jet, which promotes the formation of a cutting zone through the crack and enhances the pressure relief effect of the hard top plate.

[0016] The beneficial effects of this invention are: (1) This invention provides a method for long-distance directional fracturing along the goaf, which uses a coal mine directional drilling rig to complete long-distance directional drilling of kilometers in one go, avoiding the drawbacks of frequent equipment transfer and repetitive procedures in traditional methods. It reduces the labor intensity of workers and matches the construction speed with the working face advance speed, solving the problems of low efficiency and slow progress in traditional operations, and providing a guarantee for the efficient advancement of goaf-keeping. (2) This invention provides a method for long-distance directional fracturing with roadway retention along the goaf. Directional dense drilling is performed on the roof of the roadway retention area in front of the working face. The dynamic pressure from the working face pushes the boreholes to naturally form a cut, cutting off the pressure transmission path of the roof and achieving pressure relief and roof cutting. No blasting is required throughout the process, fundamentally eliminating the hidden dangers of gas explosions and roof collapse, and significantly improving the construction safety factor. (3) This invention provides a method for long-distance directional fracturing in goaf-retaining roadways. Dense drilling and cutting can reduce the overhang length of the roof on the side of the goaf-retaining roadway and reduce the support load of the roadway side support. This not only reduces the consumption and maintenance costs of support materials, but also allows for the optimization and adjustment of support parameters based on stress, achieving a balance between economy and reliability, and reducing the overall project cost. Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the plan layout of the long-distance directional fracturing method along the goaf of the present invention; Figure 2 This is a schematic diagram of the cross-sectional layout of the long-distance directional fracturing method along the goaf of the present invention; Figure 3 This is a schematic diagram of the longitudinal section layout of the long-distance directional fracturing method along the goaf of the present invention; Figure 4 This diagram shows the effect of roof fracture in the goaf after drilling operations using a long-distance directional fracturing method for leaving a roadway along the goaf, as described in this invention.

[0018] In the diagram: 1. Directional drilling rig chamber; 2. Directional borehole; 3. First-stage mining sidewall; 4. Goaf roadway; 5. Goaf roadway; 6. Goaf area; 7. Directional drilling rig; 8. Borehole spacing; 9. Roof strata; 10. Roadway side support. Detailed Implementation

[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] Example 1 like Figure 1As shown, the present invention discloses a method for long-distance directional fracturing along a goaf-retention roadway. In the first mining operation of the goaf-retention roadway face 3, a directional drilling chamber 1 is excavated before the working face is mined or at a certain distance ahead of the working face. A coal mine directional drilling rig 7 is arranged in the directional drilling chamber 1. Along the goaf 6 side of the roadway 4 and the side support 10 of the roadway 4, ultra-long directional boreholes 2 are drilled horizontally in the roof strata 9 to form dense horizontal pressure relief holes. The ultra-long directional boreholes 2 are drilled sequentially from top to bottom, covering the entire roof strata 9 that need pressure relief. After the working face is pushed forward, the dense horizontal pressure relief holes will form borehole cuts due to dynamic pressure, thereby achieving the purpose of pressure relief.

[0021] This invention's advanced drilling pressure relief method involves drilling dense, vertical boreholes in the roof ahead of the mining face, along the length of the roadway and close to the goaf side, with a hole spacing of 300-500mm. As the working face advances, borehole cuts will form on the goaf side of the roadway, cutting off the pressure transmission between the roof of the roadway and the mined roof portion. This advanced drilling pressure relief method typically eliminates the need for blasting, ensuring high safety. It reduces the overhang length on the goaf side of the roadway, lowers the support pressure on the roadway side supports, optimizes roadway support parameters, and reduces support costs.

[0022] Example 2 like Figures 1 to 4 As shown, the present invention provides a method for long-distance directional fracturing with gob-side entry, which is implemented according to the following steps: Step 1: Directional drilling chamber excavation and drilling rig installation.

[0023] Specifically: According to the design, a directional drilling rig chamber 1 is excavated in the coal wall of the first mining section of the roadway in the working face. The size of the chamber must meet the requirements for equipment installation and operation space. Then, the main unit 7 of the coal mine directional drilling rig is installed and fixed in the directional drilling rig chamber 1, and the drill rod, power head and hydraulic system are connected to complete the equipment foundation deployment.

[0024] Step 2: Debugging of the measurement while drilling system.

[0025] Specifically, the measurement while drilling (MWD) system was debugged to ensure stable signal transmission and accurate data detection, enabling real-time acquisition of key parameters such as azimuth and dip angles of the directional borehole, providing data support for trajectory control.

[0026] Step 3, Drilling and Azimuth Deflection Operation: Construct the initial borehole and use azimuth deflection to guide the borehole trajectory into the designed directional track.

[0027] Specifically: First, a large-diameter drilling bit is used to drill vertically or at a small angle. After drilling to the set depth, the wellhead casing is lowered and cementing is completed to stabilize the borehole wall. Then, the directional drilling tool assembly (including the curved housing motor, MWD probe, etc.) is replaced. By adjusting the angle of the curved motor and applying appropriate drilling pressure and rotation speed, the directional borehole 2 is gradually adjusted inclination and azimuth according to the design curve, deflecting towards the target area until the predetermined build-up rate and guiding parameters are achieved. Step 4, directional drilling construction: The directional borehole 2 is continuously drilled along the designed trajectory by adjusting the attitude of the drill bit in real time.

[0028] Specifically: Torque and drilling pressure are transmitted using drill pipes, and a bending motor drives the drill bit to rotate and break up coal and rock. The MWD system uploads borehole position parameters in real time. During construction, the azimuth, dip angle, tool face angle, and other data fed back by the MWD system are compared and analyzed with the design trajectory. If deviations occur, they are corrected in time by adjusting the tool face angle, drilling parameters (drill pressure, rotation speed), or by using sliding / combined drilling methods. When a single drill pipe reaches its drilling limit, the machine is stopped and the power is turned off. The drill pipe joint is disassembled using a shackler, a new drill pipe is connected, and the equipment is restarted to continue drilling. This process is repeated until the design depth is approached.

[0029] Step 5, Process Monitoring and Maintenance: Ensure the accuracy of equipment operation and drilling trajectory throughout the process, and handle unexpected problems simultaneously.

[0030] Specifically: real-time monitoring of drilling parameters such as drilling pressure, torque, rotation speed, mud flow rate, and density; immediate shutdown and investigation if any abnormality occurs (such as a sudden increase in pressure or a sudden change in torque); re-measurement of the borehole position using the MWD system every 1-3 meters of drilling, comparison with the design trajectory to calculate the deviation value, and adjustment of drilling parameters to ensure that the final borehole landing point is within the allowable range of the target area; regular cleaning of the mud pit to maintain mud performance up to standard and prevent sediment accumulation in the borehole from causing the drill bit to become stuck.

[0031] Step 6, finishing touches on construction.

[0032] Specifically: When directional borehole 2 reaches the designed final depth, drilling is stopped, and the final borehole measurement is completed through the MWD system. The final borehole coordinates, depth, and other parameters are recorded to confirm whether they meet the design requirements. Drilling is repeated according to the above process until the designed number of boreholes is completed. After all boreholes are completed, drill rods, drill bits, and other drilling tools are disassembled, their quantities are collected and counted, the construction site is cleaned up, construction records and technical data are organized, and all construction finishing work is completed.

[0033] Step 7: Move the machine to the next directional drilling chamber 1 and repeat the above steps until the drilling of the entire working face roadway 5 is completed.

[0034] In summary, compared with the prior art, the present invention has the following advantages: (1) This invention provides a method for long-distance directional fracturing along the goaf, which uses a coal mine directional drilling rig to complete long-distance directional drilling of kilometers in one go, avoiding the drawbacks of frequent equipment transfer and repetitive procedures in traditional methods. It reduces the labor intensity of workers and matches the construction speed with the working face advance speed, solving the problems of low efficiency and slow progress in traditional operations, and providing a guarantee for the efficient advancement of goaf-keeping. (2) This invention provides a method for long-distance directional fracturing with roadway retention along the goaf. Directional dense drilling is performed on the roof of the roadway retention area in front of the working face. The dynamic pressure from the working face pushes the boreholes to naturally form a cut, cutting off the pressure transmission path of the roof and achieving pressure relief and roof cutting. No blasting is required throughout the process, fundamentally eliminating the hidden dangers of gas explosions and roof collapse, and significantly improving the construction safety factor. (3) This invention provides a method for long-distance directional fracturing in goaf-retaining roadways. Dense drilling and cutting can reduce the overhang length of the roof on the side of the goaf-retaining roadway and reduce the support load of the roadway side support. This not only reduces the consumption and maintenance costs of support materials, but also allows for the optimization and adjustment of support parameters based on stress, achieving a balance between economy and reliability, and reducing the overall project cost.

[0035] Example 3 The present invention provides a method for long-distance directional fracturing with gob-side entry, which is implemented according to the following steps: Step 1: According to the design, excavate the directional drilling rig chamber 1 in the coal wall of the first mining section of the roadway in the working face; then install and fix the main unit 7 of the coal mine directional drilling rig in the directional drilling rig chamber 1, connect the drill rod, power head and hydraulic system, and complete the equipment foundation deployment; Step 2: Debug the measurement while drilling (MWD) system to ensure stable signal transmission and accurate data detection; Step 3: Construct the initial borehole and use directional drilling to guide the borehole trajectory into the designed orientation path; Step 4: Control the directional borehole 2 to continue drilling along the designed trajectory by adjusting the drill bit attitude in real time; Step 5: Ensure equipment operation and drilling trajectory accuracy throughout the process, and handle unexpected problems simultaneously; Step 6: When the directional borehole 2 reaches the designed final depth, stop drilling, complete the final borehole measurement through the MWD system, record the final borehole coordinates and depth parameters, and confirm whether it meets the design requirements; repeat the above process until the designed number of boreholes is completed; the borehole spacing is 30 cm; the boreholes are arranged in a single row from top to bottom. Step 7: Move the machine to the next directional drilling chamber 1 and repeat the above steps until the drilling of the entire working face roadway 5 is completed.

[0036] Example 4 The present invention provides a method for long-distance directional fracturing with gob-side entry, which is implemented according to the following steps: Step 1: According to the design, excavate the directional drilling rig chamber 1 in the coal wall of the first mining section of the roadway in the working face; then install and fix the main unit 7 of the coal mine directional drilling rig in the directional drilling rig chamber 1, connect the drill rod, power head and hydraulic system, and complete the equipment foundation deployment; Step 2: Debug the measurement while drilling (MWD) system to ensure stable signal transmission and accurate data detection; Step 3: Construct the initial borehole and use directional drilling to guide the borehole trajectory into the designed orientation path; Step 4: Control the directional borehole 2 to continue drilling along the designed trajectory by adjusting the drill bit attitude in real time; Step 5: Ensure equipment operation and drilling trajectory accuracy throughout the process, and handle unexpected problems simultaneously; Step 6: When the directional borehole 2 reaches the designed final depth, stop drilling, complete the final borehole measurement through the MWD system, record the final borehole coordinates and depth parameters, and confirm whether it meets the design requirements; repeat the above process until the designed number of boreholes is completed; the borehole spacing is 35 cm; the boreholes are arranged in a single row from top to bottom. Step 7: Move the machine to the next directional drilling chamber 1 and repeat the above steps until the drilling of the entire working face roadway 5 is completed.

[0037] Example 5 The present invention provides a method for long-distance directional fracturing with gob-side entry, which is implemented according to the following steps: Step 1: According to the design, excavate the directional drilling rig chamber 1 in the coal wall of the first mining section of the roadway in the working face; then install and fix the main unit 7 of the coal mine directional drilling rig in the directional drilling rig chamber 1, connect the drill rod, power head and hydraulic system, and complete the equipment foundation deployment; Step 2: Debug the measurement while drilling (MWD) system to ensure stable signal transmission and accurate data detection; Step 3: Construct the initial borehole and use directional drilling to guide the borehole trajectory into the designed orientation path; Step 4: Control the directional borehole 2 to continue drilling along the designed trajectory by adjusting the drill bit attitude in real time; Step 5: Ensure equipment operation and drilling trajectory accuracy throughout the process, and handle unexpected problems simultaneously; Step 6: When directional borehole 2 reaches the designed final depth, stop drilling, complete the final borehole measurement using the MWD system, record the final borehole coordinates and depth parameters, and confirm whether it meets the design requirements; repeat the above process until the designed number of boreholes is completed; the borehole spacing is 40 cm; the boreholes are arranged in multiple rows from top to bottom. Step 7: Move the machine to the next directional drilling chamber 1 and repeat the above steps until the drilling of the entire working face roadway 5 is completed.

[0038] Example 6 The present invention provides a method for long-distance directional fracturing with gob-side entry, which is implemented according to the following steps: Step 1: According to the design, excavate the directional drilling rig chamber 1 in the coal wall of the first mining section of the roadway in the working face; then install and fix the main unit 7 of the coal mine directional drilling rig in the directional drilling rig chamber 1, connect the drill rod, power head and hydraulic system, and complete the equipment foundation deployment; Step 2: Debug the measurement while drilling (MWD) system to ensure stable signal transmission and accurate data detection; Step 3: Construct the initial borehole and use directional drilling to guide the borehole trajectory into the designed orientation path; Step 4: Control the directional borehole 2 to continue drilling along the designed trajectory by adjusting the drill bit attitude in real time; Step 5: Ensure equipment operation and drilling trajectory accuracy throughout the process, and handle unexpected problems simultaneously; Step 6: When the directional borehole 2 reaches the designed final depth, stop drilling, complete the final borehole measurement through the MWD system, record the final borehole coordinates and depth parameters, and confirm whether it meets the design requirements; repeat the above process until the designed number of boreholes is completed; the borehole spacing is 50 cm; the boreholes are arranged in multiple rows from top to bottom. Step 7: Move the machine to the next directional drilling chamber 1 and repeat the above steps until the drilling of the entire working face roadway 5 is completed.

[0039] The foregoing description illustrates and describes several preferred embodiments of the invention. However, as previously stated, it should be understood that the invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the invention should be within the protection scope of the appended claims.

Claims

1. A method for long-distance directional fracturing with goaf retention, characterized in that, In the first mining of the working face along the goaf (3), a directional drilling chamber (1) is excavated before the working face is mined or at a certain distance ahead of the working face. A coal mine directional drilling rig (7) is arranged in the directional drilling chamber (1). Along the goaf (6) side of the goaf support (10) of the goaf roadway (4), ultra-long directional boreholes (2) are drilled in the horizontal direction in the roof rock layer (9) to form dense advance pressure relief holes in the horizontal direction. The ultra-long directional boreholes (2) are drilled sequentially from top to bottom to cover the entire roof rock layer (9) that needs pressure relief.

2. The method for long-distance directional fracturing along the goaf as described in claim 1, characterized in that, The specific steps are as follows: Step 1: According to the design, excavate the directional drilling chamber (1) in the coal wall of the first mining side (3) of the roadway in the working face; then install and fix the main unit (7) of the coal mine directional drilling rig in the directional drilling chamber (1), connect the drill rod, power head and hydraulic system, and complete the equipment foundation deployment; Step 2: Debug the measurement while drilling (MWD) system to ensure stable signal transmission and accurate data detection; Step 3: Construct the initial borehole and use directional drilling to guide the borehole trajectory into the designed orientation path; Step 4: Control the directional drilling (2) to continue drilling along the designed trajectory by adjusting the drill bit attitude in real time; Step 5: Ensure equipment operation and drilling trajectory accuracy throughout the process, and handle unexpected problems simultaneously; Step 6: When the directional drilling (2) reaches the designed final hole depth, stop drilling, complete the final hole measurement through the MWD system, record the final hole coordinates and depth parameters, and confirm whether it meets the design requirements; repeat the above process until the designed number of holes is completed. Step 7: Move the machine to the next directional drilling chamber (1) and repeat the above steps until the drilling of the entire working face roadway (5) is completed.

3. The method for long-distance directional fracturing along the goaf as described in claim 2, characterized in that, The directional drilling rig used in coal mines can drill holes up to 1000m long in a single operation.

4. The method for long-distance directional fracturing along the goaf as described in claim 3, characterized in that, The spacing between the boreholes is 30 cm to 50 cm; the boreholes can be arranged in a single row or multiple rows from top to bottom.

5. The method for long-distance directional fracturing along the goaf as described in claim 4, characterized in that, Multiple rows of boreholes can be arranged from top to bottom.

6. The method for long-distance directional fracturing along the goaf as described in claim 6, characterized in that, The spacing between the boreholes in each row may be the same or different.

7. The method for long-distance directional fracturing along the goaf as described in claim 6, characterized in that, The spacing between the holes in each row may be the same or different.

8. The method for long-distance directional fracturing along the goaf as described in claim 7, characterized in that, Hydraulic fracturing is used to inject water into the borehole and use high-pressure water jets to create a cutting groove along the borehole axis, which promotes the formation of a cut band through the fracture and enhances the pressure relief effect on the hard top plate.

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