A method for quickly uncovering coal of crossheading based on alternating high-concentration gas power

Abstract

The application discloses a kind of based on the method for quick crossheading coal uncovering of alternating high concentration gas power, first construction specific layout borehole group, grouping cooperation is carried out to each borehole, and high concentration gas extracted by each group borehole is pressurized, injected into other borehole, and combined with gas extraction, so that alternating pressure gas flow and extraction gas flow appear in borehole, and then coal body around borehole repeatedly bears the effect of expansion and shrinkage, by specific extraction pressurization and injection sequence, the coal body around center hole, first circle borehole and second circle borehole is sequentially cracked by high pressure high concentration gas, positive and negative pressure alternating stress fatigue cracking is carried out, and the process of gas displacement gas is carried out, so as to significantly improve gas extraction efficiency and gas extraction concentration, realize efficient gas extraction and quick crossheading coal uncovering, with wide practicability;In addition, it also has the advantages of simple process, convenient operation and low cost.

Description

Technical Field

[0001] This invention relates to a method for rapid coal seam exposure in a rock face based on alternating high-concentration methane power, belonging to the field of coal seam decompression and mining technology. Background Technology

[0002] In coal and gas outburst mines, the risk of outburst is greatest and the time required for coal uncovering in rock face is longest, making it a difficult point for mine safety and a bottleneck in mining deployment. Due to the complexity of outbursts and the severity of their harm to mine safety, industry professionals worldwide attach great importance to this issue. Currently, the industry has developed various outburst prevention technologies for rock face coal uncovering, including hydraulic perforation, drainage boreholes, pre-gas extraction, metal skeletons, full-face blasting with deep holes, and direct vibration blasting, for coalfields with different geological conditions, different coal seams, and different outburst risks. These technologies have played a certain role in preventing outbursts, but their safety needs improvement, and the construction period required for coal uncovering is too long, seriously affecting mine safety and the normal succession of mining operations. The main reason is that the traditional rock-cutting coal seam exposure technology does not achieve sufficient expansion of coal seam fractures and does not realize regional fracture networking. Moreover, after the implementation of the traditional hydraulically cut rock-cutting coal seam exposure technology, the clay minerals and organic matter in the coal seam are very easy to swell when they come into contact with water. This often makes it difficult for water to be discharged after entering the coal body, blocking the gas flow channel and inhibiting gas desorption, diffusion and infiltration. As a result, the coal seam does not achieve sufficient pressure relief and permeability enhancement before rock-cutting coal seam exposure. Ultimately, this results in high ground stress and gas pressure in the coal body and high gas content, making rock-cutting coal seam exposure highly dangerous.

[0003] Therefore, the research direction required by this application is to provide a new method to effectively reduce the in-situ stress of the coal body before coal seam exposure and to improve gas extraction efficiency by increasing permeability. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a method for rapid coal seam exposure in rock face based on alternating high-concentration methane power. By coordinating boreholes at different levels, the extracted high-concentration methane is injected into other boreholes. By changing the injection and extraction states of the boreholes, high-pressure high-concentration methane fracturing, alternating stress fracturing, and methane-driven methane fracturing are combined, so that the methane in the coal seam requiring rock face exposure is extracted rapidly at a high concentration, thereby achieving rapid and safe rock face exposure.

[0005] To achieve the above objectives, the technical solution adopted by this invention is: a method for rapid coal seam uncovering in a rock face based on alternating high-concentration methane power, the specific steps of which are as follows:

[0006] Step 1: When the minimum normal distance from the coal seam to the Shimen coal face is K, a conventional drilling method is used to drill a group of boreholes through the protective rock pillar into the coal seam. The specific layout of the borehole group is as follows: First, a central hole is drilled towards the center of the coal seam. After completion, multiple boreholes are evenly arranged on a circle with a radius of J, centered on the final position of the central hole, to form the first ring of boreholes. Then, multiple boreholes are evenly arranged on a circle with a radius of L, centered on the final position of the central hole, to form the second ring of boreholes, where J < L. After the construction is completed, a capsule sealing device is used to seal the central hole, the first ring of boreholes, and the second ring of boreholes.

[0007] Step 2: First, connect the first and second boreholes to the inlet of the booster pump through pipelines. Connect the outlet of the booster pump to the center hole through pipelines. Start the booster pump and inject the high-concentration gas extracted from the first and second boreholes into the center hole through the booster pump. After the set gas injection time is reached, stop the booster pump and connect the center hole to the gas extraction pipeline network for gas extraction.

[0008] Step 3: Divide the boreholes in the second ring into M groups, grouping each group into N adjacent groups. After the gas extracted from all boreholes in each group is collected, it is pressurized by a booster pump and injected into one of the boreholes in the first ring. Thus, each of the M groups corresponds to one of the M boreholes in the first ring, injecting high-pressure, high-concentration gas. After the set injection time is reached, the booster pump stops working. Then, each of the M groups corresponds to one of the other M boreholes in the first ring that have not been injected with high-concentration gas, and the injection process in this step is repeated until all boreholes in the first ring have completed the injection of high-pressure, high-concentration gas.

[0009] Step 4: First, disconnect the central borehole from the gas extraction pipeline network. Then, connect the first ring of boreholes after the treatment in Step 3 to the inlet of the booster pump through pipelines. Connect the outlet of the booster pump to the central borehole through pipelines. Start the booster pump so that the high-concentration gas extracted from the first ring of boreholes is injected into the central borehole through the booster pump. Stop the booster pump after the set gas injection time is reached.

[0010] Step 5: Divide the boreholes in the second ring into M groups as in Step 3. After the gas extracted from the N-1 adjacent boreholes in each group is combined and pressurized by a booster pump, it is injected into the remaining boreholes in the same group. Stop the booster pump after the set gas injection time is reached.

[0011] Step 6: Regroup the boreholes in the second ring of boreholes in the same manner as in Step 3, and repeat Step 5 until all boreholes in the second ring of boreholes have completed high-pressure, high-concentration gas injection.

[0012] Step 7: After repeating steps 2 to 6 multiple times, connect all boreholes in the borehole group to the gas drainage pipeline network for continuous gas drainage; when the coal seam gas content is less than 8m³... 3When the gas level reaches / t, gas extraction is stopped, and the coal seam is exposed using conventional methods.

[0013] Furthermore, the first ring of drill holes contains 8 holes, and the second ring of drill holes contains 16 holes.

[0014] Furthermore, the values ​​of N and M are both 4.

[0015] Furthermore, in step two, the gas injection pressure is 5–8 MPa, and the gas injection time is 8–10 h.

[0016] Furthermore, in steps three, four, and five, the gas injection pressure is 3–5 MPa, and the gas injection time is 2–3 hours.

[0017] Furthermore, the value of K is 8-10m, the value of J is 2-3m, and the value of L is 5-7m.

[0018] Compared with existing technologies, the method of this invention first constructs a specially arranged group of boreholes to form three different levels of boreholes: a central borehole, a first ring of boreholes, and a second ring of boreholes. These different levels of boreholes are then grouped and coordinated. The high-concentration methane extracted from each group of boreholes is pressurized and injected into other boreholes, combined with methane extraction. This causes alternating pressurized and extracted airflows in each borehole, resulting in the coal body surrounding the boreholes repeatedly undergoing expansion and contraction. Through a specific extraction, pressurization, and injection sequence, the coal body surrounding the central borehole, the first ring of boreholes, and the second ring of boreholes is stabilized. The process involves sequentially performing high-pressure, high-concentration gas fracturing, alternating positive and negative pressure stress fatigue fracturing (i.e., negative pressure during extraction and positive pressure during injection, alternating to achieve alternating positive and negative pressure stress), and gas displacement, thereby significantly improving gas extraction efficiency and concentration. Under alternating high-concentration gas stress, the coal body easily reaches its fatigue limit and fractures, causing the fractures to continuously expand and develop deeper, increasing the borehole's gas extraction radius and thus increasing the total gas extraction volume, improving gas extraction efficiency. In summary, this invention integrates the synergistic processes of gas fracturing, alternating stress fatigue fracturing, and gas displacement, achieving efficient gas extraction and rapid coal seam uncovering, possessing broad applicability. Furthermore, it has the advantages of simple process, convenient operation, and low cost. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the construction layout of the present invention;

[0020] Figure 2 yes Figure 1 Cross-sectional view along the AA direction.

[0021] In the diagram: 1. Rock strata; 2. Coal seam; 3. Tunnel cross-section; 4. Second borehole ring; 5. First borehole ring; 6. Center hole; 7. Booster pump. Detailed Implementation

[0022] The present invention will be further described below.

[0023] like Figure 1 As shown, the specific steps of this invention are as follows:

[0024] Step 1: When the minimum normal distance between the Shimen coal seam and the coal face is 8-10m, a group of boreholes is constructed through the protective rock pillar to reach the coal seam 2 using conventional drilling methods. The specific layout of the borehole group is as follows: First, a central borehole 6 is constructed towards the center of the coal seam 2. After completion, eight boreholes are evenly arranged on a circle with a radius of 2-3m, using the final position of the central borehole 6 as the center, to form the first ring of boreholes 5. Then, sixteen boreholes are evenly arranged on a circle with a radius of 5-7m, using the final position of the central borehole 6 as the center, to form the second ring of boreholes 4. Figure 2 As shown; after construction is completed, a capsule sealing device is used to seal the center hole 6, the first ring of drilled holes 5, and the second ring of drilled holes 4;

[0025] Step 2: First, connect the inlet of the first ring borehole 5 and the second ring borehole 4 to the inlet of the booster pump 7 through pipelines. Connect the outlet of the booster pump 7 to the central hole through a pipeline. Start the booster pump 7 and inject the high-concentration gas extracted from the first ring borehole 5 and the second ring borehole 4 into the central hole 6 through the booster pump 7. The gas injection pressure is 5-8 MPa and the gas injection time is 8-10 hours. After the set gas injection time is reached, stop the booster pump and connect the central hole 6 to the gas extraction pipeline network for gas extraction.

[0026] Step 3: Divide the boreholes in the second ring of boreholes 4 into 4 groups of 4 adjacent boreholes. After the gas extracted from all boreholes in each group is collected, it is pressurized by the booster pump 7 and injected into one of the boreholes in the first ring of boreholes 5. The 4 groups correspond one-to-one, so that 4 boreholes in the first ring of boreholes 5 are injected with high-pressure, high-concentration gas. The gas injection pressure is 3-5 MPa and the gas injection time is 2-3 hours. After the set gas injection time is reached, the booster pump 7 is stopped. The 4 groups are then corresponding one-to-one with the other 4 boreholes in the first ring of boreholes 5 that have not been injected with high-concentration gas, and the injection process in this step is repeated until all boreholes in the first ring of boreholes 4 have been injected with high-pressure, high-concentration gas.

[0027] Step 4: First, disconnect the central hole 6 from the gas extraction pipeline network. Then, connect the first ring of boreholes 5 after the treatment in Step 3 to the inlet of the booster pump 7 through pipelines. Connect the outlet of the booster pump 7 to the central hole 6 through pipelines. The gas injection pressure is 3-5 MPa and the gas injection time is 2-3 hours. Start the booster pump so that the high-concentration gas extracted from the first ring of boreholes 5 is injected into the central hole 6 through the booster pump 7. Stop the booster pump after the set gas injection time is reached.

[0028] Step 5: Divide the boreholes in the second ring of boreholes 4 into M groups in the same manner as in Step 3. After the gas extracted from the N-1 adjacent boreholes in each group is combined, it is pressurized by the booster pump 7 and then injected into the remaining boreholes in the same group. The gas injection pressure is 3-5 MPa and the gas injection time is 2-3 hours. After the set gas injection time is reached, the booster pump 7 is stopped.

[0029] Step 6: Regroup the boreholes in the second ring of boreholes 4 according to the method in Step 3, and repeat Step 5 until all boreholes in the second ring of boreholes 4 have completed high-pressure, high-concentration gas injection.

[0030] Step 7: After repeating steps 2 to 6 multiple times, connect all boreholes in the borehole group to the gas drainage pipeline network for continuous gas drainage; when the coal seam gas content is less than 8m³... 3 When the gas level reaches / t, gas extraction is stopped, and the coal seam is exposed using conventional methods.

[0031] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for rapid cross-cut coal uncovering based on alternating high-concentration gas power, characterized in that, The specific steps are as follows: Step one: when the minimum normal distance of the working face of the stone gate coal uncovering to the coal seam is K, a conventional drilling method is used to drill a group of holes through the protective rock pillar to the coal seam, and the specific arrangement of the drilling group is as follows: a central hole is first drilled to the center of the coal seam, and after the completion, a plurality of holes are uniformly arranged on the circumference of a circle with a radius J to form a first circle of holes with the terminal hole position of the central hole as the center; then a plurality of holes are uniformly arranged on the circumference of a circle with a radius L to form a second circle of holes with the terminal hole position of the central hole as the center; and J < L; after the construction is completed, a capsule hole sealer is used to seal the central hole, the first circle of holes and the second circle of holes; Step two: the first circle of holes and the second circle of holes are first connected to the inlet of a booster pump through a pipeline, the outlet of the booster pump is connected to the central hole through a pipeline, the booster pump is started, the high-concentration gas extracted from the first circle of holes and the second circle of holes is converged and then injected into the central hole through the boosting effect of the booster pump, the booster pump is stopped after a set injection time, and the central hole is connected to a gas extraction pipeline network for gas extraction; Step three: the holes in the second circle of holes are divided into M groups, each group containing N adjacent holes; the gas extracted from all the holes in each group is converged and then injected into one of the holes in the first circle of holes through the boosting effect of the booster pump, and then the M groups are one-to-one corresponding to the M holes in the first circle of holes so that the M holes are injected with high-pressure high-concentration gas, the booster pump is stopped after a set injection time; the M groups are one-to-one corresponding to the other M holes in the first circle of holes which are not injected with high-concentration gas, and the injection process of this step is repeated until all the holes in the first circle of holes complete the high-pressure high-concentration gas injection process; Step four: the central hole is first disconnected from the gas extraction pipeline network, and the first circle of holes treated in step three is connected to the inlet of the booster pump through a pipeline, the outlet of the booster pump is connected to the central hole through a pipeline, the booster pump is started, the high-concentration gas extracted from the first circle of holes is injected into the central hole through the boosting effect of the booster pump, and the booster pump is stopped after a set injection time; Step five: the holes in the second circle of holes are divided into M groups according to the method of step three, and the gas extracted from N-1 adjacent holes in each group is converged and then injected into the remaining hole in the group through the boosting effect of the booster pump; the booster pump is stopped after a set injection time; Step six: the holes in the second circle of holes are re-grouped according to the method of step three, and step five is repeated until all the holes in the second circle of holes complete the high-pressure high-concentration gas injection; Step seven, after repeating steps two to six for several times, all the drill holes in the drill hole group are connected to the gas extraction pipe network for continuous gas extraction; when the coal seam gas content is less than 8 m 3 / t, the gas extraction is stopped, and the coal seam is opened according to the conventional coal uncovering method.

2. The method for fast cross-cut coal uncovering based on alternating high-concentration gas power according to claim 1, characterized in that, The number of the first circle of holes is 8, and the number of the second circle of holes is 16.

3. The method for fast cross-cut coal uncovering based on alternating high-concentration gas power according to claim 2, characterized in that, The values of N and M are both 4.

4. The method for fast cross-cut coal uncovering based on alternating high-concentration gas power according to claim 1, characterized in that, The injection pressure in step two is 5-8 MPa, and the injection time is 8-10 h.

5. The method for fast cross-cut coal uncovering based on alternating high-concentration gas power according to claim 1, characterized in that, The injection pressure in steps three, four and five is 3-5 MPa, and the injection time is 2-3 h.

6. The method for fast cross-cut coal uncovering based on alternating high-concentration gas power according to claim 1, characterized in that, The value of K is 8-10 m, the value of J is 2-3 m, and the value of L is 5-7 m.

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