A sealing system and method for cross - seam pressure relief boreholes in the floor of a close - distance coal seam

Abstract

The present invention provides a hole - sealing system for a cross - seam pressure - relief borehole in the floor of a close - distance coal seam. A hole - protecting pipe is installed in the borehole, and a multi - hole perforated pipe is provided at the collecting end of the hole - protecting pipe that penetrates into the coal seam for gas extraction. A polyurethane sealing layer and a cement mortar layer are successively arranged in the borehole along the outer periphery of the hole - protecting pipe in the gas extraction direction from the inside to the outside for sealing the borehole. The present invention also provides a method for sealing a cross - seam pressure - relief borehole in the floor of a close - distance coal seam. By lowering a PVC hole - protecting pipe with a multi - hole perforated pipe for hole protection, the present invention prevents the development of surrounding rock fissures or even borehole collapse caused by the mining influence of the upper coal seam. By pouring fine sand outside the hole - protecting pipe, the present invention enables the surrounding rock fissures generated under mining influence to be timely filled by the sinking of the fine sand, ensuring the extraction concentration and pure extraction volume of pressure - relief gas. The present invention has better gas extraction sealing performance, better extraction effect, effectively reduces the gas content of the coal seam to be extracted, and ensures the mining safety of the coal seam to be extracted.

Description

Technical Field

[0001] The present invention relates to the technical field of mine gas drainage, and particularly relates to a gob-side entry retaining through-layer pressure relief borehole sealing system and method for a close-distance coal seam floor. Background Art

[0002] Under the condition of upper protective layer mining in a close-distance coal seam, in order to prevent a large amount of rapidly inflowing pressure-relieved gas from the protected coal seam into the working face of the protective layer under the influence of mining, causing gas overrun accidents and affecting the tunneling and coal winning safety of the working face of the protective layer, it is necessary to advance the drainage of the pressure-relieved gas in the close-distance protected coal seam. However, the pressure-relieved gas drainage boreholes in the gob-side entry retaining are affected by mining, resulting in fissures in the surrounding rock of the boreholes or even borehole collapse, affecting the drainage quality. Therefore, it is necessary to improve the sealing of the through-layer pressure-relieved gas drainage boreholes in the close-distance coal seam floor. Summary of the Invention

[0003] To solve the above problems, the present invention aims to provide a gob-side entry retaining through-layer pressure relief borehole sealing system and method. By lowering a PVC casing pipe with a multi-hole perforated pipe for hole protection, it prevents the development of fissures in the surrounding rock or even borehole collapse caused by the mining influence of the upper coal seam, solves the problem that the rock mass between the two coal seams is broken and fissured due to the mining influence of the upper coal seam, resulting in an adverse impact on the sealing effect of the through-layer gas drainage borehole during the drainage process, and further leads to a low drainage efficiency.

[0004] To achieve the above object, the technical solution of the present invention is realized as follows:

[0005] A gob-side entry retaining through-layer pressure relief borehole sealing system, which relates to a floor pressure relief borehole. A casing pipe is installed in the borehole. The collecting end of the casing pipe extending into the coal seam is provided with a multi-hole perforated pipe for gas drainage; a polyurethane sealing layer and a cement mortar layer are sequentially arranged in the borehole on the outer periphery of the casing pipe along the gas drainage direction from inside to outside for sealing the borehole.

[0006] Furthermore, it further includes a fine sand layer, and the fine sand layer is located above the cement mortar layer for filling and sealing the fissures in the surrounding rock caused by mining influence.

[0007] Furthermore, the depth of the fine sand layer is 5 m, and the particle size of the fine sand is 0.125 mm to 0.25 mm.

[0008] Furthermore, the casing pipe is a casing pipe of a certain material. The multi-hole perforated pipe is integrally formed with the casing pipe, and the multi-hole perforated pipe is located in the coal seam gas enrichment space and extends 0.5 m into the coal seam.

[0009] Further, it also includes an on-line gas concentration monitoring device. The hole protection pipe is connected to the main mine gas drainage pipeline outside the drill hole. An on-line gas concentration monitoring device is installed on the main mine gas drainage pipeline to monitor the gas concentration in the drill hole, and the on-line gas concentration monitoring device is connected to the ground dispatching center by wire.

[0010] Further, the on-line gas concentration monitoring device transmits the gas concentration data signal to the terminal server through optical fiber, and the ground dispatching center is connected to the terminal server for on-line display of the gas concentration in the drill hole.

[0011] Further, when the gas concentration in the drill hole is low, the dispatching center located on the ground shows a low concentration on-line, indicating poor hole sealing effect.

[0012] Further, the polyurethane plugging layer includes isocyanate and polyether polyol. The polyurethane plugging layer is formed by injecting the isocyanate and polyether polyol packaged in a bladder in a ratio of 1:1 into the drill hole before expansion.

[0013] Further, the cement mortar layer is formed by injecting cement mortar into the drill hole through a grouting pipe and solidifying.

[0014] To achieve the above object, the present invention also provides a method for sealing a short-distance coal seam floor cross-cutting pressure relief drill hole, including the following steps:

[0015] S1. Drill a hole. The hole passes through the coal seam by 0.5 m, drain the accumulated water and coal slag in the drill hole, and lower a hole protection pipe made of the material;

[0016] S2. Inject the isocyanate and polyether polyol packaged in a bladder into the space between the hole protection pipe and the drill hole in a ratio of 1:1 to form a polyurethane plugging layer;

[0017] S3. After the polyurethane plugging layer solidifies, inject cement mortar through the grouting pipe to form a cement mortar layer, and the cement mortar layer is above the polyurethane plugging layer;

[0018] S4. After the cement mortar layer solidifies, pour fine sand with a depth of 5 m and a particle size of 0.125 mm to 0.25 mm into the drill hole to form a fine sand layer, and timely fill and seal the surrounding rock cracks generated by mining influence.

[0019] Beneficial effects: The present invention protects the borehole by lowering a PVC protective borehole pipe with a porous flower pipe, preventing the development of surrounding rock fissures or even borehole collapse caused by the mining influence of the upper coal seam. The present invention also adopts a sealing process of pouring fine sand with a particle size of 0.125 mm to 0.25 mm and a depth of 5 m outside the protective borehole pipe, so that the surrounding rock fissures generated under the mining influence can be filled in time by the sinking of the fine sand, ensuring the drainage concentration and pure drainage volume of the depressurized gas. The present invention improves the gas drainage efficiency, has better sealing performance for gas drainage, better drainage effect, effectively reduces the gas content in the coal seam to be drained, and ensures the mining safety of the coal seam to be drained. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which form a part of the present invention, are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0021] Figure 1 is a schematic structural diagram of a sealing system for a cross-layer pressure relief borehole in the floor of a close-distance coal seam according to an embodiment of the present invention;

[0022] Figure 2 is a flow chart of a method for sealing a cross-layer pressure relief borehole in the floor of a close-distance coal seam according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0024] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0025] Embodiment 1

[0026] See Figure 1 : A sealing system for a cross-layer pressure relief borehole in the floor of a close-distance coal seam, which relates to a floor pressure relief borehole 1, a protective borehole pipe 2 is installed in the borehole 1, and a porous flower pipe 3 for gas drainage 5 is provided at the collection end of the protective borehole pipe 2 extending into the coal seam 4; a polyurethane sealing layer 6 and a cement mortar layer 7 are sequentially provided in the borehole 1 on the outer periphery of the protective borehole pipe 2 along the gas drainage direction from the inside to the outside for sealing the borehole 1.

[0027] In specific implementation, the multi-hole flower pipe of this embodiment can not only improve the gas drainage efficiency, but also buffer the pressure through the pores during drainage, reducing the probability of borehole collapse;

[0028] In addition, it can be understood that when a borehole collapse occurs, the porous filling of cinder, broken rock blocks, etc. in the porous perforated pipe of this embodiment plays a very good buffering effect to prevent large-area collapses; the polyurethane plugging layer and the cement mortar layer of this embodiment can enhance the plugging effect and effectively prevent the development of surrounding rock fissures or even borehole collapses caused by the mining influence of the upper coal seam.

[0029] It should be noted that the floor cross-measurement pressure relief boreholes of this embodiment are arranged in the gob-side entry retaining. After the working face is mined, the floor cross-measurement pressure relief boreholes are arranged in the gob-side entry retaining roadway, and continuous extraction of the pressure-relieved gas in the protected seam can be achieved.

[0030] In a specific example, it further includes a fine sand layer 8. The fine sand layer 8 is located above the cement mortar layer 7 for filling and plugging. The depth of the fine sand layer 8 is 5m, and the particle size of the fine sand is 0.125mm to 0.25mm.

[0031] It should be noted that the fine sand in this embodiment plays a role in buffering the deformation and extrusion of the surrounding rock generated under the mining influence on the hole protection pipe, and can timely fill the surrounding rock fissures generated under the mining influence.

[0032] In a specific example, the hole protection pipe 2 is a hole protection pipe made of this material. The porous perforated pipe 3 is integrally formed with the hole protection pipe 2. The porous perforated pipe 3 is located in the coal seam gas enrichment space and extends 0.5m below the coal seam floor.

[0033] The borehole of this embodiment passes through the coal seam by 0.5m to precipitate the cinder and fissure seepage water falling under the mining influence of the upper coal seam. A plurality of round holes are designed around the porous perforated pipe, and the gas released in the coal seam with an effective extraction negative pressure of 13Kpa can be effectively extracted through the extraction pipeline.

[0034] In a specific example, it further includes an on-line gas concentration monitoring device 10. The hole protection pipe 2 is connected to the main mine gas extraction pipeline 11 outside the borehole 1. The on-line gas concentration monitoring device 10 is installed on the main mine gas extraction pipeline 11 to monitor the gas concentration in the borehole 1. The on-line gas concentration monitoring device 10 is wired to the ground dispatching center. The on-line gas concentration monitoring device 10 transmits the gas concentration data signal to the terminal server through an optical fiber. The ground dispatching center is connected to the terminal server for on-line display of the gas concentration in the borehole 1. When the gas concentration in the borehole 1 is low, the dispatching center located on the ground shows a low concentration on-line, indicating poor plugging effect.

[0035] In this embodiment, the gas concentration in the floor pressure relief borehole can be monitored at any time through the dispatching center located on the ground.

[0036] It should be noted that when the ground dispatching center monitors that the plugging effect is poor, fine sand can be manually supplemented into the hole in time to achieve the plugging effect.

[0037] In a specific example, the polyurethane sealing layer 6 comprises isocyanate and polyether polyol, and the polyurethane sealing layer 6 is formed by injecting a 1:1 mixture of isocyanate and polyether polyol packed in a sachet into the borehole 1 before expansion.

[0038] In this embodiment, the isocyanate and polyether polyol packed in a sachet are separated from each other before use. When in use, the isocyanate and polyether polyol are mixed in a 1:1 ratio by a device, quickly lowered to a specified position outside the hole protection pipe before expansion, and quickly expand after mixing to achieve the sealing effect.

[0039] In a specific example, the cement mortar layer 7 is formed by injecting cement mortar into the borehole 1 through a grouting pipe 9 and solidifying it.

[0040] Embodiment 2

[0041] To achieve the above object, refer to Figure 2 : This embodiment also provides a method for sealing a cross - layer pressure - relief borehole in the floor of a close - distance coal seam, comprising the following steps:

[0042] S1. Drill a borehole that penetrates the coal seam by 0.5 m, drain the accumulated water and coal slag in the borehole, and lower a hole protection pipe made of this material;

[0043] S2. Inject a 1:1 mixture of isocyanate and polyether polyol packed in a sachet between the hole protection pipe and the borehole to form a polyurethane sealing layer;

[0044] S3. After the polyurethane sealing layer solidifies, inject cement mortar through the grouting pipe to form a cement mortar layer, and the cement mortar layer is above the polyurethane sealing layer;

[0045] S4. After the cement mortar layer solidifies, pour fine sand with a particle size of 0.125 mm - 0.25 mm and a filling depth of 5 m into the borehole to form a fine sand layer, and timely fill and seal the surrounding rock fissures generated by mining influence.

[0046] The advantages of the method for sealing a cross - layer pressure - relief borehole in the floor of a close - distance coal seam in this embodiment compared with the above - mentioned sealing system for a cross - layer pressure - relief borehole in the floor of a close - distance coal seam relative to the prior art are the same, and will not be elaborated here.

[0047] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A borehole sealing system for cross - layer pressure relief of the floor of a close - distance coal seam, which relates to the floor pressure - relief borehole (1), and is characterized in that A protection hole pipe (2) is installed in the drill hole (1). A porous perforated pipe (3) is provided at the collection end of the protection hole pipe (2) that penetrates into the coal seam (4) for gas drainage (5). In the drill hole (1) on the outer periphery of the protection hole pipe (2) along the gas drainage direction from inside to outside, a polyurethane plugging layer (6) and a cement mortar layer (7) are successively provided for plugging the drill hole (1). A fine sand layer (8) is further included. The fine sand layer (8) is located above the cement mortar layer (7) for filling and plugging the surrounding rock fissures generated by mining influence. The polyurethane plugging layer (6) includes isocyanate and polyether polyol. The polyurethane plugging layer (6) is formed by injecting the isocyanate and polyether polyol in a 1:1 ratio in a bladder package into the drill hole (1) before expansion to form the polyurethane plugging layer (6).

2. The borehole sealing system for cross - seam pressure relief drilling in the floor of a close - distance coal seam according to claim 1, wherein The depth of the fine sand layer (8) is 5 m, and the particle size of the fine sand is 0.125 mm to 0.25 mm.

3. The borehole sealing system for cross - seam pressure relief drilling in the floor of a close - distance coal seam according to claim 1, wherein, The hole protection pipe (2) is a hole protection pipe made of the material. The porous perforated pipe (3) is integrally formed with the hole protection pipe (2). The porous perforated pipe (3) is located in the coal seam gas enrichment space and extends 0.5 m below the coal seam floor.

4. The borehole sealing system for cross - seam pressure relief drilling in the floor of a close - distance coal seam according to claim 1, characterized in that, A gas concentration on-line monitoring device (10) is further included. The protection hole pipe (2) is connected to a mine gas drainage main pipeline (11) outside the drill hole (1). The gas concentration on-line monitoring device (10) is installed on the mine gas drainage main pipeline (11) for monitoring the gas concentration in the drill hole (1). The gas concentration on-line monitoring device (10) is connected to the ground dispatching center by wire.

5. The borehole sealing system for cross - seam pressure relief drilling in the floor of a close - distance coal seam according to claim 4, characterized in that, The gas concentration on-line monitoring device (10) transmits the gas concentration data signal to the terminal server through an optical fiber. The ground dispatching center is connected to the terminal server for on-line displaying the gas concentration in the drill hole (1).

6. The borehole sealing system for cross - seam pressure relief drilling in the floor of a close - distance coal seam according to claim 5, characterized in that, When the gas concentration in the drill hole (1) is low, the dispatching center located on the ground displays a low concentration on-line, indicating poor hole plugging effect.

7. The borehole sealing system for cross - seam pressure relief drilling in the floor of a close - distance coal seam according to claim 1, wherein, The cement mortar layer (7) is formed by injecting cement mortar into the drill hole (1) through a grouting pipe (9) and solidifying.

8. A method for sealing boreholes of cross - layer pressure relief in the floor of a close - distance coal seam, characterized in that, It includes the following steps: S1. Drill a hole through the coal seam for 0.5 m, drain the water and coal slag in the hole, and lower a hole protection pipe made of the material; S2. Inject the isocyanate and polyether polyol in a bladder package into the space between the protection hole pipe and the drill hole in a 1:1 ratio to form a polyurethane plugging layer; S3. After the polyurethane plugging layer solidifies, inject cement mortar through the grouting pipe to form a cement mortar layer, and the cement mortar layer is above the polyurethane plugging layer; S4. After the cement mortar layer solidifies, pour fine sand with a depth of 5 m and a particle size of 0.125 mm to 0.25 mm, and fill it into the drill hole to form a fine sand layer, and timely fill and plug the surrounding rock fissures generated by mining influence.

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