Drainage method for outburst prevention downward drilling of coal and gas outburst mine
By drilling hydrophobic holes in the lower drilling holes and forming a crack network, the problem of water accumulation in the lower drilling holes is solved, the gas extraction effect of coal seam is improved, and the production of the mine is ensured safely.
Patent Information
- Application Number
- CN202411531709.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-30
- Publication Date
- 2024-12-13
AI Technical Summary
In coal and gas outburst mines, water accumulation often occurs in the lower drilling holes, blocking gas overflow, resulting in poor gas extraction effect of coal seams.
Through drilling and geophysical exploration, water accumulation conditions are determined, hydrophobic holes are drilled and cracked networks are formed using hole-making devices, the diameter of hydrophobic holes is expanded, steel pipes are buried and sealed by two injections and one blocking method to achieve drainage of downward drilling holes.
It significantly reduces the accumulation of water on the downward drilling, eliminates the barrier of gas spillover by the accumulated water, improves the extraction effect of coal seam gas, and enhances the safety of the mine.
Smart Images
Figure CN119122603A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of downward drilling drainage, and in particular to a downward drilling drainage method for preventing coal and gas outburst in a mine. Background Art
[0002] Coal and gas outburst mines are mines with outburst coal seams within the mine field and have experienced outburst accidents or have been identified and assessed to have outburst hazards. They are serious hazards that threaten personnel safety, can cause casualties, trigger gas explosions, and damage production equipment and tunnels, affecting production order. Coal and gas outburst mine prevention measures are divided into regional and local. Regional outburst prevention measures include mining protective layers and pre-extraction of coal seam gas. Local outburst prevention measures include advance drilling and hydraulic punching, etc. These measures are used to reduce the risk of outbursts and ensure safe production in mines.
[0003] Pre-extraction of coal seam gas is to extract the gas in the coal seam in advance by means of downward drilling before coal mining, so as to reduce the gas pressure and gas content in the coal seam. The principle is to use the fluidity of gas and the channel provided by the borehole, under the action of negative pressure or natural pressure difference, to make the gas in the coal seam flow to the borehole, and then transport the gas to the ground for processing through the connected extraction system. Downward drilling is divided into through-layer drilling and along-layer drilling. Through-layer drilling is drilling from the rock tunnel on the top and bottom plates of the coal seam to the coal seam. Simply put, the trajectory of the drilling will pass through different rock layers and finally reach the coal seam. And along-layer drilling is drilling along the plane of the coal seam (including the direction or inclination of the coal seam).
[0004] As the mining of downward drilling holes in coal mines gradually extends and karst fissures on the surface evolve, water will accumulate in most downward drilling holes under the joint guidance of geological structures and fissures. The accumulated water generated during the drilling construction can be drained once through the wind drainage process, but for downward drilling holes with continuous water accumulation, gas overflow will be blocked, the extraction negative pressure will be unbalanced, and the expected extraction effect cannot be achieved. Summary of the invention
[0005] The purpose of the present invention is to provide a method for draining downward boreholes in coal and gas outburst prevention mines to solve the problem that water accumulates in most downward boreholes during the pre-extraction of coal seam gas, thereby blocking gas overflow and causing poor coal seam gas extraction effect.
[0006] To achieve the above object, the basic scheme provided by the present invention is: a method for draining water by drilling downwards to prevent coal and gas outburst in a mine, comprising the following steps:
[0007] S1. Determine the water volume in the downward borehole area through drilling, geophysical exploration and other means;
[0008] S2. According to the water accumulation conditions found, a drainage hole is drilled through the surrounding tunnels at a level 1 to 2 meters below the end of the downward borehole using a drilling rig, and the amount of coal discharged during the drilling process is weighed;
[0009] S3. After the drilling is completed, the drainage hole is drilled and cavitated by the cavitation device to form a fracture network, and the hole expansion drilling is started. The clean water pressure pumped out by the clean water pump of the cavitation device is 3-4Mpa. When the cavitation device drills into the coal seam position, the drilling is stopped, and the power head of the cavitation device is kept rotating. The clean water pressure pumped out by the clean water pump of the cavitation device is increased to 6-7Mpa. The knife arm of the cavitation device is opened to rotate and cut the coal seam to expand the cavitation diameter of the drainage hole to 480-500mm. At the same time, the amount of coal discharged during the cavitation process is weighed. When the knife arm of the cavitation device and the hydraulic force penetrate the coal seam to see the rock layer, the drainage hole cavitation is completed;
[0010] S4. After the hole making is completed, the expected hole making coal volume per meter is calculated by the hole making depth, and then the sum of the actual total coal volume discharged during the drilling and hole making process is divided by the length of the drill rod extension to obtain the actual hole making coal volume per meter. Finally, the expected hole making coal volume per meter is compared with the actual hole making coal volume per meter to analyze the hole making effect. If the actual hole making coal volume per meter is less than the expected hole making coal volume per meter, the hole making effect is poor and the hole making is performed again. Otherwise, the hole making effect is qualified.
[0011] S5. After the hole making effect is qualified, a steel pipe is buried in the drain hole, and the gap between the outer wall of the steel pipe and the inner wall of the drain hole is blocked by the method of two injections and one blocking;
[0012] S6. After the plugging is completed, the accumulated water in the downward borehole enters the drainage hole after the hole is made through the fracture network, and finally flows out through the steel pipe, completing the drainage of the downward borehole.
[0013] The beneficial effects of the present invention are as follows: by constructing drainage boreholes and performing hole-making fracturing, a drainage hole fracture network is formed, and the accumulated water in the downward boreholes and the compensating water source flow directly into the drainage holes through the fracture network, thereby greatly reducing the accumulated water in the downward boreholes, thereby eliminating the barrier of the accumulated water to the gas overflow, making the extraction negative pressure more balanced, significantly improving the extraction effect of coal seam gas, and making the gas environment in the mine safer.
[0014] Solution 2, which is the preferred basic solution, the relationship between the number of drain holes and the water volume in the downward drilling area is 1m 3 The downward drilling area requires 3 to 5 drainage holes. The number of drainage holes should be accurately planned according to the actual water volume to ensure that the accumulated water can be effectively drained, avoiding the situation where too many drainage holes cause waste of resources or too few drainage holes cause poor drainage effect, and achieving a balance between drainage efficiency and cost.
[0015] Option three is a preferred option of the basic option. In S2, the drain holes are divided into horizontal drain holes and inclined drain holes, and the inclination angle of the inclined drain holes is 2 to 8°. The inclination angle of the inclined drain holes is set to 2 to 8° to facilitate the self-flow of accumulated water under the action of gravity.
[0016] Option 4, which is the preferred option of the basic option, S2, the distance between each of the hydrophobic holes is less than 2 to 3 meters.
[0017] Scheme 5 is the preferred basic scheme. In S4, the expected amount of coal per meter of cavitation is calculated by the following formula:
[0018]
[0019] Where: V is the expected coal output per meter of hole, unit: Kg / m;
[0020] R—hole radius, unit: m;
[0021] L—hole length, unit: m;
[0022] H—hole depth, unit: m;
[0023] ρ—density of coal, unit: Kg / m 3 ;
[0024] π—pi, the value is 3.14.
[0025] Option six is the preferred option of the basic option. In S5, the plugging materials used in the two-injection-one-plugging method are Marisan and cement slurry; the plugging of Marisan enhances the sealing performance, and the cement slurry further consolidates the plugging effect.
[0026] Scheme 7, which is a preferred embodiment of Scheme 6, the two-injection-one-blocking method comprises the following steps:
[0027] Step 1: First, inject the Marisan into the annular space between the outer wall of both ends of the steel pipe and the hydrophobic hole;
[0028] Step 2: After the marisan expands and solidifies, the grouting pipe and the return grouting pipe are passed through the solidified marisan and extended to the annular space between the marisan at both ends of the steel pipe, and one end of the return grouting pipe is located at a higher position in the annular space;
[0029] Step 3: Connect the grouting pipe to the grouting equipment to deliver cement slurry to the annular space between the outer wall of the steel pipe and the inner wall of the drain hole. When the grouting starts, the annular space is gradually filled with cement slurry. When the cement slurry flows out of the return grouting pipe, it means that the grouting is completed.
[0030] Step 4: Finally, cut off the excess parts of the grouting pipe and the return grouting pipe.
[0031] Option 8 is a preferred embodiment of Option 6. The diameter of the steel pipe is 108 mm, the length is 15 to 20 m, and the depth of the hydrophobic hole is 6 to 12 m.
[0032] Option nine is a preferred option of option six. A flange and a valve are preset at one end of the steel pipe exposed outside the drain hole. A flange and a valve are set at the open end of the steel pipe to facilitate the subsequent installation of a water volume monitoring device.
[0033] Option 10 is a preferred option of Option 6. The water-cement ratio of the cement slurry is 1:2. During the grouting process, the gap between the steel pipe and the drain hole can be better filled to ensure the sealing effect. BRIEF DESCRIPTION OF THE DRAWINGS
[0034] Figure 1 It is a structural schematic diagram of a downward drilling hole and a drainage hole in a downward drilling drainage method for preventing coal and gas outburst in a mine according to the present invention;
[0035] Figure 2 It is a schematic diagram of the state of hole making in a downward drilling drainage method for preventing coal and gas outburst in a mine according to the present invention. DETAILED DESCRIPTION
[0036] The present invention is further described in detail below through specific embodiments:
[0037] like Figure 1 to Figure 2 A method for draining water from downward drilling holes in a coal and gas outburst mine, comprising the following steps:
[0038] S1. Determine the water volume in the downward borehole area through drilling, geophysical exploration and other means;
[0039] S2. According to the water accumulation situation, use a drilling rig to drill drainage holes through the surrounding tunnels at a horizontal position 2m below the end of the downward drilling hole. The relationship between the number of drainage holes and the water volume in the downward drilling area is 1m 3 The water volume in the downward drilling area requires four drainage holes, which are divided into horizontal drainage holes and inclined drainage holes. The inclination angle of the inclined drainage holes is 7°, and the spacing between each drainage hole is less than 2m. At the same time, the amount of coal discharged during the drilling process is weighed;
[0040] S3. After the drilling is completed, the drainage hole is drilled and cavitated by the cavitation device to form a fracture network, and the hole expansion drilling is started. The clean water pressure pumped out by the clean water pump of the cavitation device is 3Mpa. When the cavitation device drills into the coal seam position, the drilling is stopped, and the power head of the cavitation device is kept rotating. The clean water pressure pumped out by the clean water pump of the cavitation device is increased to 6Mpa. The knife arm of the cavitation device is opened to rotate and cut the coal seam to expand the cavitation diameter of the drainage hole to 500mm. At the same time, the amount of coal discharged during the cavitation process is weighed. When the knife arm of the cavitation device and the hydraulic force penetrate the coal seam to see the rock layer, the drainage hole cavitation is completed;
[0041] S4. After the cave is built, the expected amount of coal per meter is calculated by the cave depth. The expected amount of coal per meter is calculated by the following formula:
[0042]
[0043] Where: V is the expected coal output per meter of hole, unit: Kg / m;
[0044] R—hole radius, unit: m;
[0045] L—hole length, unit: m;
[0046] H—hole depth, unit: m;
[0047] ρ—density of coal, unit: Kg / m 3 ;
[0048] π—pi, the value is 3.14;
[0049] Then, the sum of the actual total coal volume discharged during the drilling and cavitation process is divided by the length of the drill rod extension to obtain the actual cavitation coal volume per meter. Finally, the expected cavitation coal volume per meter is compared with the actual cavitation coal volume per meter to analyze the cavitation effect. If the actual cavitation coal volume per meter is less than the expected cavitation coal volume per meter, the cavitation effect is poor and cavitation should be carried out again. Otherwise, the cavitation effect is qualified.
[0050] S5. After the hole making effect is qualified, a steel pipe is buried in the drain hole, and the gap between the outer wall of the steel pipe and the inner wall of the drain hole is blocked by the two-injection-one-blocking method. The diameter of the steel pipe is 108mm, the length is 15m, and the depth of the drain hole is 12m. A flange and a valve are preset at one end of the steel pipe exposed outside the drain hole. The blocking materials used in the two-injection-one-blocking method are Marisan and cement slurry. The water-cement ratio of the cement slurry is 1:2. The two-injection-one-blocking method includes the following steps:
[0051] Step 1: First, inject the Marisan into the annular space between the outer wall of both ends of the steel pipe and the hydrophobic hole;
[0052] Step 2: After the marisan expands and solidifies, the grouting pipe and the return grouting pipe are passed through the solidified marisan and extended to the annular space between the marisan at both ends of the steel pipe, and one end of the return grouting pipe is located at a higher position in the annular space;
[0053] Step 3: Connect the grouting pipe to the grouting equipment to deliver cement slurry to the annular space between the outer wall of the steel pipe and the inner wall of the drain hole. When the grouting starts, the annular space is gradually filled with cement slurry. When the cement slurry flows out of the return grouting pipe, it means that the grouting is completed.
[0054] Step 4: Finally, cut off the excess parts of the grouting pipe and the return grouting pipe;
[0055] S6. After the plugging is completed, the accumulated water in the downward borehole enters the drainage hole after the hole is made through the fracture network, and finally flows out through the steel pipe, completing the drainage of the downward borehole.
[0056] The above is only an embodiment of the present invention, and the common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several deformations and improvements can be made without departing from the structure of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.
Claims
1. A method for draining water by drilling downwards in a coal and gas outburst mine, characterized in that: The following steps are involved: S1. Determine the water volume in the downward borehole area through drilling, geophysical exploration and other means; S2. According to the water accumulation conditions found, a drainage hole is drilled through the surrounding tunnels at a level 1 to 2 meters below the end of the downward borehole using a drilling rig, and the amount of coal discharged during the drilling process is weighed; S3. After the drilling is completed, the drainage hole is drilled and cavitated by the cavitation device to form a fracture network, and the hole expansion drilling is started. The clean water pressure pumped out by the clean water pump of the cavitation device is 3-4Mpa. When the cavitation device drills into the coal seam position, the drilling is stopped, and the power head of the cavitation device is kept rotating. The clean water pressure pumped out by the clean water pump of the cavitation device is increased to 6-7Mpa. The knife arm of the cavitation device is opened to rotate and cut the coal seam to expand the cavitation diameter of the drainage hole to 480-500mm. At the same time, the amount of coal discharged during the cavitation process is weighed. When the knife arm of the cavitation device and the hydraulic force penetrate the coal seam to see the rock layer, the drainage hole cavitation is completed; S4. After the hole making is completed, the expected hole making coal volume per meter is calculated by the hole making depth, and then the sum of the actual total coal volume discharged during the drilling and hole making process is divided by the length of the drill rod extension to obtain the actual hole making coal volume per meter. Finally, the expected hole making coal volume per meter is compared with the actual hole making coal volume per meter to analyze the hole making effect. If the actual hole making coal volume per meter is less than the expected hole making coal volume per meter, the hole making effect is poor and the hole making is performed again. Otherwise, the hole making effect is qualified. S5. After the hole making effect is qualified, a steel pipe is buried in the drain hole, and the gap between the outer wall of the steel pipe and the inner wall of the drain hole is blocked by the method of two injections and one blocking; S6. After the plugging is completed, the accumulated water in the downward borehole enters the drainage hole after the hole is made through the fracture network, and finally flows out through the steel pipe, completing the drainage of the downward borehole.
2. A method for draining water by drilling downwards to prevent coal and gas outburst in a mine according to claim 1, characterized in that: The relationship between the number of drainage holes and the water volume in the downward drilling area is 1m 3 The downward drilling area requires 3 to 5 drainage holes to meet the water demand.
3. A method for draining water by drilling downwards to prevent coal and gas outburst in a mine according to claim 1, characterized in that: In S2, the hydrophobic holes are divided into horizontal hydrophobic holes and inclined hydrophobic holes, and the inclined hydrophobic holes have an inclination angle of 2 to 8 degrees.
4. A method for draining water by drilling downwards to prevent coal and gas outburst in a mine according to claim 1, characterized in that: In S2, the distance between each of the hydrophobic holes is less than 2 to 3 m.
5. A method for draining water by drilling downwards to prevent coal and gas outburst in a mine according to claim 1, characterized in that: In S4, the expected amount of coal per meter of cavitation is calculated by the following formula: Where: V is the expected coal output per meter of hole, unit: Kg / m; R—hole radius, unit: m; L—hole length, unit: m; H—hole depth, unit: m; ρ—density of coal, unit: Kg / m 3 ; π—pi, the value is 3.
14.
6. A method for draining water by drilling downwards to prevent coal and gas outburst in a mine according to claim 1, characterized in that: In S5, the plugging materials used in the two-injection-one-plugging method are Marisan and cement slurry.
7. A method for draining water by drilling downwards to prevent coal and gas outburst in a mine according to claim 6, characterized in that: The two-injection-one-blocking method comprises the following steps: Step 1: First, inject the Marisan into the annular space between the outer wall of both ends of the steel pipe and the hydrophobic hole; Step 2: After the marisan expands and solidifies, the grouting pipe and the return grouting pipe are passed through the solidified marisan and extended to the annular space between the marisan at both ends of the steel pipe, and one end of the return grouting pipe is located at a higher position in the annular space; Step 3: Connect the grouting pipe to the grouting equipment to deliver cement slurry to the annular space between the outer wall of the steel pipe and the inner wall of the drain hole. When the grouting starts, the annular space is gradually filled with cement slurry. When the cement slurry flows out of the return grouting pipe, it means that the grouting is completed. Step 4: Finally, cut off the excess parts of the grouting pipe and the return grouting pipe.
8. A method for draining water by drilling downwards to prevent coal and gas outburst in a mine according to claim 1, characterized in that: In S5, the diameter of the steel pipe is 108 mm, the length is 15 to 20 m, and the depth of the hydrophobic hole is 6 to 12 m.
9. A method for draining water by drilling downwards to prevent coal and gas outburst in a mine according to claim 8, characterized in that: A flange and a valve are preset at one end of the steel pipe exposed outside the drain hole.
10. A method for draining water by drilling downwards to prevent coal and gas outburst in a mine according to claim 6, characterized in that: The water-cement ratio of the cement slurry is 1:2.