Coal mine underground sealing sampling device and method

Abstract

The invention relates to the technical field of undisturbed stratum sampling devices, in particular to a coal mine underground sealing sampling device which comprises an inner drilling barrel, a drilling rod connecting sleeve and an outer drilling barrel, the inner drilling barrel, the drilling rod connecting sleeve and the outer drilling barrel are all of a cylindrical structure, and annular cutting heads are arranged on the lower end opening of the inner drilling barrel and the lower end opening of the outer drilling barrel; a cylinder neck of a hexagonal prism structure is arranged at the top of the inner drilling cylinder, a water passing plate is arranged at the bottom of the drilling rod connecting sleeve, and the water passing plate is detachably and fixedly connected with the cylinder neck through a bolt. The outer drilling barrel is arranged on the outer side of the inner drilling barrel and the outer side of the drilling rod connecting sleeve in a sleeving mode, and a sealing structure is arranged between the circumferential inner wall of the outer drilling barrel and the circumferential outer wall of the inner drilling barrel and the circumferential outer wall of the drilling rod connecting sleeve. Through the innovative structural design and the systematized sealing scheme, the defects that in a traditional sampling method, the integrity of a sample is poor, and gas escapes are overcome.

Description

Technical Field

[0001] This invention relates to the field of undisturbed formation sampling devices, specifically a sealed sampling device and method for underground coal mines. Background Technology

[0002] In coal mine safety mining and gas control, accurate measurement of coal seam gas parameters is the fundamental basis for extraction design. Currently, deep-hole sampling in coal mines mainly relies on sealed sampling devices, the core of which is to obtain coal samples that can truly reflect the original state of the strata.

[0003] In existing technologies, mainstream sealed sampling devices mainly employ two methods: one is based on the principle of negative pressure ejection, directly extracting the gas-powder mixture; the other uses mechanical structures (such as rotary ball valves) to control the sampling channel. Both methods obtain broken powder or fragmented coal samples. The incompleteness of the sample increases its specific surface area, making it easier for gas to escape during sampling and lifting, disrupting the original gas adsorption-desorption equilibrium of the coal body. In addition, mechanical structures such as ball valves are prone to jamming and incomplete closure in pulverized coal environments, exacerbating gas escape and making it difficult to guarantee the accuracy of the measurement results.

[0004] Therefore, there is an urgent need for a new type of sealed sampling device and method for underground coal mines, which can provide an effective solution to the shortcomings of existing technologies. Summary of the Invention

[0005] The purpose of this invention is to provide a sealed sampling device and method for underground coal mines to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A sealed sampling device for underground coal mines includes an inner drill cylinder, a drill rod connecting sleeve, and an outer drill cylinder. All three are cylindrical structures, with annular cutting heads at their lower ends. The top of the inner drill cylinder has a hexagonal prism-shaped neck, and the bottom of the drill rod connecting sleeve has a water-passing plate, which is detachably fixed to the neck by bolts. The outer drill cylinder is sleeved outside the inner drill cylinder and drill rod connecting sleeve, and a sealing structure is provided between the inner circumference of the outer drill cylinder and the outer circumference of the inner drill cylinder and drill rod connecting sleeve. The upper part of the outer drill cylinder has a middle... The intermediate plate is located between the top of the water-passing plate and the inner drill cylinder. The neck of the hexagonal prism structure at the center of the intermediate plate slides in conjunction with the neck of the cylinder. The bottom of the inner circumference of the outer drill cylinder is provided with a pop-out cutter head. The length between the intermediate plate of the outer drill cylinder and the annular cutter head is greater than the length of the inner drill cylinder. When the outer drill cylinder slides to the uppermost end, that is, when the intermediate plate contacts the water-passing plate, the annular cutter head of the inner drill cylinder aligns with the annular cutter head of the outer drill cylinder. When the outer drill cylinder slides to the lowermost end, that is, when the intermediate plate contacts the top of the inner drill cylinder, and when the lower end of the outer drill cylinder extends out of the inner drill cylinder, the pop-out cutter head automatically opens under the action of a spring.

[0008] Furthermore, a piston is slidably installed inside the inner drill barrel, and an exhaust port is provided at the top of the inner drill barrel. A one-way valve for one-way air discharge to the outside is installed on the exhaust port.

[0009] Furthermore, an annular expansion sealing bag is provided at the bottom of the inner circumference of the outer drill barrel. The annular expansion sealing bag is located below the ejected cutter head. A water injection channel is provided on the inner wall of the outer drill barrel. The upper end of the water injection channel is connected to the upper part of the intermediate plate, and the lower end is connected to the annular expansion sealing bag. A one-way valve for one-way liquid inlet to the annular expansion sealing bag is provided at the lower end of the water injection channel.

[0010] Furthermore, an arc-shaped blade groove is formed on the inner circumference of the outer drill barrel, one end of the ejector cutting head is hinged in the blade groove, and the spring is set on the side of the ejector cutting head facing the inner circumference of the blade groove.

[0011] A method for sealed sampling in underground coal mines includes the following steps:

[0012] S1. Reliably connect the drill pipe connecting sleeve to the downhole drill pipe; at this time, the outer drill pipe is at the uppermost end of its stroke, that is, the middle plate is in contact with the water-passing plate, and the annular cutting heads of the inner and outer drill pipes are aligned; then, the entire device is lowered to the target coal seam through the drill pipe, and the drilling rig is started for initial drilling; the torque of the drill pipe is transmitted through the drill pipe connecting sleeve and the cooperating cylinder neck and neck opening, which simultaneously drive the inner and outer drill pipes to rotate and cut together, and the formed complete coal core enters the cavity of the inner drill pipe;

[0013] S2. When the initial drilling is completed and sealing sampling is required, high-pressure water is injected into the device through the drill rod. The high-pressure water acts on the water-passing plate and the middle plate, generating downward pressure, which pushes the outer drill barrel to overcome friction and spring force, sliding downward relative to the inner drill barrel. During this process, the drilling rig continues to rotate and feed. While the outer drill barrel slides downward, its annular cutting head continues to cut the coal seam, causing its bottom to gradually extend and surpass the cutting head of the inner drill barrel. When the outer drill barrel slides to its lowest point, the bottom ejector cutter head automatically springs open under the action of the spring. At this time, the rotation is maintained and the feed stops. The ejected cutter head then cuts and severs the root of the coal core, completing the sampling.

[0014] S3. Stop injecting high-pressure water and stop drilling. The complete coal core sample sealed in the closed chamber formed by the inner drill tube and the outer drill tube after sliding down has been successfully captured. Remove the entire device from the borehole and disassemble it on the ground to obtain the original coal sample that retains pressure and shape.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] 1. This invention achieves the original, intact collection of coal cores through the coordinated drilling of the inner and outer drill barrels, combined with the structure of the annular cutting head. Compared with traditional crushing sampling methods, this invention can obtain cylindrical coal core samples that retain the original bedding structure. After the outer drill barrel slides down, it forms a main sealed cavity with the inner drill barrel. The annular expansion sealing bag immediately seals the bottom of the sample after sampling. The sealing structure between each component ensures the reliability of the seal during relative sliding, effectively preventing gas escape and ensuring the fidelity of the sample. The piston and exhaust port with a one-way valve inside the inner drill barrel constitute an exhaust system. During the coal core entry process, the air in the cavity pushes the piston upward and is discharged through the exhaust port, avoiding the influence of compressed air on the gas content of the coal core and further ensuring the purity of the sample.

[0017] 2. The pop-out cutter head of this invention adopts a mechanical spring drive method. When the outer drill tube is fully extended from the inner drill tube, it automatically pops open to form a cut-out ring. The purely mechanical triggering mechanism does not rely on a complex control system and is adapted to the harsh working environment in coal mines. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the external structure of a sealed sampling device for underground coal mines.

[0019] Figure 2 A vertical cross-sectional view of a sealed sampling device and method for underground coal mines;

[0020] Figure 3 This is a vertical sectional view of the outer drill barrel;

[0021] Figure 4This is a vertical sectional view of the inner drill barrel and the drill pipe connecting sleeve;

[0022] Figure 5 This is a schematic diagram of the structure of the inner drill barrel and the drill pipe connecting sleeve;

[0023] Figure 6 This is an exploded view of the structure of the inner drill barrel and the drill pipe connecting sleeve.

[0024] Figure 7 A schematic diagram of the structure of the annular expansion sealing bag and the cutting head;

[0025] Figure 8 This is a cross-sectional view of the external drill barrel at the point where the cutter head is ejected.

[0026] In the diagram: 1. Inner drill barrel; 2. Drill rod connecting sleeve; 3. Outer drill barrel; 4. Piston; 5. Neck; 6. Vent hole; 7. Water passage plate; 8. Intermediate plate; 9. Water injection channel; 10. Annular expansion sealing bag; 11. Pop-up cutter head; 12. Spring. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1:

[0029] Please see Figures 1 to 8This embodiment provides a basic implementation of a sealed sampling device for underground coal mines. The device mainly includes an inner drill cylinder 1, a drill rod connecting sleeve 2, and an outer drill cylinder 3. The inner drill cylinder 1, drill rod connecting sleeve 2, and outer drill cylinder 3 are all cylindrical structures. Both the inner drill cylinder 1 and the outer drill cylinder 3 have annular cutting heads at their lower ends for collaborative cutting of the coal seam. The top of the inner drill cylinder 1 has a hexagonal prism-shaped neck 5. The bottom of the drill rod connecting sleeve 2 has a water-passing plate 7, which is detachably fixed to the neck 5 by bolts. The outer drill cylinder 3 is sleeved on the outside of the inner drill cylinder 1 and the drill rod connecting sleeve 2. A sealing structure is provided between the inner circumferential wall of the outer drill cylinder 3 and the outer circumferential wall of the inner drill cylinder 1 and the drill rod connecting sleeve 2 to ensure sealing when the components slide relative to each other. An intermediate plate 8 is fixed to the upper part of the outer drill cylinder 3, and this intermediate plate 8 is located between the water-passing plate 7 and the top of the inner drill cylinder 1. A hexagonal prism-shaped neck is formed at the center of the intermediate plate 8, which slides into contact with the neck 5 at the top of the inner drill barrel 1. This structure allows the outer drill barrel 3 to slide axially relative to the inner drill barrel 1 and the drill rod connecting sleeve 2, while also transmitting torque. A pop-out cutter head 11 is provided at the bottom of the inner circumference of the outer drill barrel 3. The length of the outer drill barrel 3 from the intermediate plate 8 to its bottom annular cutting head is greater than the total length of the inner drill barrel 1.

[0030] Working Principle: In the initial state, the outer drill tube 3 slides to its uppermost position, i.e., the intermediate plate 8 contacts the water-passing plate 7. At this time, the annular cutting head of the inner drill tube 1 aligns with the annular cutting head of the outer drill tube 3, allowing for synchronous drilling and enabling the complete coal core to enter the inner drill tube 1. When sampling is required, high-pressure water is injected through the drill rod. The high-pressure water acts on the upper part of the water-passing plate 7 and the intermediate plate 8, generating downward hydraulic pressure, which pushes the outer drill tube 3 downward against friction. During this process, the drilling rig maintains rotation and feed, and the outer drill tube 3 continues to cut the coal seam, causing its lower end to gradually extend out of the inner drill tube 1. When the outer drill tube 3 slides to its lowermost position, i.e., the intermediate plate 8 contacts the top of the inner drill tube 1, its lower end fully extends out of the inner drill tube 1. At this time, the ejected cutting head 11 automatically springs open under the action of the spring 12. The ejected cutting head forms an enlarged cutting ring, which, under the action of the drilling rig rotation, can cleanly and neatly cut off the root of the coal core. After truncation, the captured intact coal core sample is sealed in a closed chamber formed by the inner drill tube 1 and the sliding outer drill tube 3. This method successfully obtains complete cylindrical coal cores, rather than broken coal fragments, greatly improving the representativeness and gas fidelity of the sample.

[0031] Example 2:

[0032] In this embodiment, the structure of the inner drill barrel 1 is further optimized. A piston 4 is slidably installed inside the inner drill barrel 1. An exhaust port 6 is provided at the top of the inner drill barrel 1, and a one-way valve that only allows gas to be discharged to the outside is installed on the exhaust port 6.

[0033] Working principle: During the initial drilling, piston 4 is located at the bottom of inner drill tube 1. As the coal core enters the cavity of inner drill tube 1, the air in the cavity pushes piston 4 upward and is discharged through the one-way valve on exhaust port 6, thus avoiding the influence of air on the gas concentration of the sample during the core drilling process.

[0034] Example 3:

[0035] Based on Embodiment 1 or 2, this embodiment further includes an annular expansion sealing bag 10 at the bottom of the inner circumference of the outer drill barrel 3, located below the ejected cutter head 11. A water injection channel 9 is machined on the inner wall of the outer drill barrel 3. The upper end of the water injection channel 9 connects to the space above the intermediate plate 8, and the lower end connects to the interior of the annular expansion sealing bag 10. A one-way valve is provided at the lower end of the water injection channel 9, allowing only liquid to flow into the annular expansion sealing bag 10.

[0036] Working principle: While high-pressure water is injected through the drill pipe and pushes the outer drill barrel 3 down, some of the high-pressure water will open the one-way valve at the lower end of the water injection channel 9 and be injected into the annular expansion sealing bag 10.

[0037] The annular expansion sealing bag 10 expands rapidly and tightly wraps the coal core, thereby immediately sealing the bottom of the sample after it is extracted and broken upwards, which also prevents air from affecting the gas concentration of the sample.

[0038] Example 4:

[0039] In this embodiment, an arc-shaped blade groove is formed on the inner circumference of the outer drill barrel 3. One end of the ejector cutting head 11 is mounted in the blade groove via a hinge shaft. A spring 12 is disposed on the side of the ejector cutting head 11 facing the inner circumference of the blade groove.

[0040] Working principle: When the lower end of the outer drill barrel 3 does not extend beyond the inner drill barrel 1, its inner wall constrains the ejected cutter head 11, causing it to retract into the blade groove, and the spring 12 is in a compressed state. When the outer drill barrel 3 slides down until its lower end fully extends beyond the inner drill barrel 1, the constraint is released, the compressed spring 12 quickly releases its elastic force, ejecting the ejected cutter head 11 outward, causing it to rotate around the hinge axis, forming an effective cut-off ring.

Claims

1. A sealed sampling device for underground coal mines, characterized in that, Includes an inner drill barrel (1), a drill pipe connecting sleeve (2), and an outer drill barrel (3): The inner drill cylinder (1), drill rod connecting sleeve (2), and outer drill cylinder (3) are all cylindrical structures. The lower end of the inner drill cylinder (1) and the outer drill cylinder (3) are provided with an annular cutting head. The top of the inner drill cylinder (1) is provided with a hexagonal prism-shaped neck (5). The bottom of the drill rod connecting sleeve (2) is provided with a water-passing plate (7). The water-passing plate (7) and the neck (5) are detachably fixedly connected by bolts. The outer drill cylinder (3) is sleeved on the outside of the inner drill cylinder (1) and the drill rod connecting sleeve (2). A sealing structure is provided between the inner circumference of the outer drill cylinder (3) and the outer circumference of the inner drill cylinder (1) and the drill rod connecting sleeve (2). The upper part of the outer drill cylinder (3) is provided with a middle plate (8). The middle plate (8) is located between the water-passing plate (7) and the top of the inner drill cylinder (1). The neck of the hexagonal prism-shaped structure at the center of the middle plate (8) is slidably fitted with the neck (5). The bottom of the inner circumference of the outer drill tube (3) is provided with a pop-out cutter head (11). The length between the middle plate (8) and the annular cutter head of the outer drill tube (3) is greater than the length of the inner drill tube (1). When the outer drill tube (3) slides to the uppermost end, that is, when the middle plate (8) contacts the water-passing plate (7), the annular cutter head of the inner drill tube (1) is aligned with the annular cutter head of the outer drill tube (3). When the outer drill tube (3) slides to the lowermost end, that is, when the middle plate (8) contacts the top of the inner drill tube (1), when the lower end of the outer drill tube (3) extends out of the inner drill tube (1), the pop-out cutter head (11) automatically opens under the action of the spring (12).

2. The sealed sampling device for underground coal mines according to claim 1, characterized in that: A piston (4) is slidably installed inside the inner drill barrel (1), and an exhaust hole (6) is provided at the top of the inner drill barrel (1). A one-way valve for one-way air discharge to the outside is installed on the exhaust hole (6).

3. The sealed sampling device for underground coal mines according to claim 1, characterized in that: The bottom of the inner circumference of the outer drill barrel (3) is also provided with an annular expansion sealing bag (10), which is located below the ejected cutter head (11). The inner wall of the outer drill barrel (3) is provided with a water injection channel (9). The upper end of the water injection channel (9) is connected to the upper part of the intermediate plate (8), and the lower end is connected to the annular expansion sealing bag (10). The lower end of the water injection channel (9) is provided with a one-way valve for one-way liquid inlet to the annular expansion sealing bag (10).

4. The underground sealed sampling device for coal mines according to claim 1, characterized in that: The outer drill barrel (3) has an arc-shaped blade groove on its inner circumference. One end of the ejector cutting head (11) is hinged in the blade groove. The spring (12) is located on the side of the ejector cutting head (11) facing the inner circumference of the blade groove.

5. A method for sealed sampling in underground coal mines, applicable to the sealed sampling device for underground coal mines as described in any one of claims 1-4, characterized in that... Includes the following steps: S1. Reliably connect the drill pipe connecting sleeve (2) to the downhole drill pipe; at this time, the outer drill pipe (3) is at the uppermost end of its stroke, that is, the middle plate (8) is in contact with the water-passing plate (7), and the annular cutting heads of the inner and outer drill pipes are aligned; then, the entire device is lowered to the target coal seam through the drill pipe, and the drilling rig is started for initial drilling; The torque of the drill rod is transmitted through the drill rod connecting sleeve (2) and the cooperating cylinder neck (5) and neck opening, which simultaneously drive the inner drill cylinder (1) and the outer drill cylinder (3) to rotate and cut together, and the complete coal core is formed and enters the cavity of the inner drill cylinder (1); S2. When the initial drilling is completed and sealing sampling is required, high-pressure water is injected into the device through the drill rod. The high-pressure water acts on the water-passing plate (7) and the middle plate (8), generating downward pressure, which pushes the outer drill barrel (3) to overcome friction and spring force and slide downward relative to the inner drill barrel (1). During this process, the drilling machine continues to rotate and feed. While the outer drill barrel (3) slides downward, its annular cutting head continues to cut the coal seam, so that its bottom gradually extends and surpasses the cutting head of the inner drill barrel (1). When the outer drill barrel (3) slides to its lowest stroke, the bottom pop-out cutting head (11) automatically pops open under the action of the spring (12). At this time, the rotation is stopped and the feed is stopped. The pop-out cutting head then cuts and cuts off the root of the coal core, completing the sampling. S3. Stop injecting high-pressure water and stop drilling. The complete coal core sample sealed in the closed chamber formed by the inner drill cylinder (1) and the outer drill cylinder (3) after sliding down has been successfully captured. The entire device is lifted out of the borehole and disassembled on the ground to obtain the original coal sample with pressure and shape preservation.

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