Inclined shaft coal seam group combined rapid coal uncovering method

Abstract

The invention discloses an inclined shaft coal seam group combined rapid coal uncovering method, and relates to the technical field of tunnel construction, and the method comprises the following steps: 1, constructing an inclined shaft to a preset position, 2, constructing a directional long drill hole in the bottom of the inclined shaft along the extension direction of the inclined shaft, and penetrating through all coal seam groups; 3, hydraulic fracturing is conducted on the coal seam group, and staged fracturing is conducted on the coal seam group from deep to shallow in the fracturing process; 4, sealing holes for gas extraction and effect inspection; 5, after extraction reaches the standard, grouting is conducted to increase the strength of the coal seam; 6, coal uncovering is carried out; according to the method, gas extraction is carried out on all the coal seams at the same time, a large amount of disaster control time is saved, and a large amount of drilling work amount is saved through construction of directional drilling and implementation of hydraulic fracturing.

Description

Technical Field

[0001] This invention relates to a method for coal seam uncovering in a shaft, specifically a method for rapid coal seam uncovering in a group of coal seams in an inclined shaft. Background Technology

[0002] When carrying out coal seam exposure operations in coal seam groups, conventional single-seam coal seam exposure processes suffer from significant problems such as low operational efficiency and high safety risks due to factors such as the large burial depth of the coal seams, complex occurrence conditions, and abnormal gas outbursts. Traditional coal seam exposure technologies often employ a perforation method along the seam, sequentially carrying out drilling, fracturing, sealing, extraction, and grouting processes. This makes it difficult to achieve simultaneous treatment of the coal seam group, resulting in long exposure cycles, large construction workloads, and mutual interference between multiple coal seams, easily forming gas migration channels and significantly increasing the risk of gas outbursts. In addition, the coal seam spacing is generally small, and they are densely distributed vertically, making it difficult for ordinary boreholes to penetrate all target coal seams, limiting the extraction range and resulting in significantly insufficient efficiency. Therefore, there is an urgent need for a combined coal seam exposure technology that has high construction efficiency, good gas extraction effect, and adaptability to the complex occurrence characteristics of coal seam groups to better meet the current urgent needs of efficient and safe coal mining. Therefore, a method for combined rapid coal seam exposure in inclined shafts is needed to solve the above-mentioned technical problems. Summary of the Invention

[0003] In view of this, the present invention provides a method for joint and rapid coal seam exposure in inclined shafts. Compared with traditional coal seam exposure methods, the present invention simultaneously extracts gas from all coal seams, saving a significant amount of time for disaster management. Furthermore, by constructing directional drilling and implementing hydraulic fracturing, a large amount of drilling work is saved.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A method for rapid coal seam uncovering in a deviated shaft includes the following steps: Step 1: Construct the inclined shaft to the predetermined position; Step 2: Drill a long directional borehole at the bottom of the inclined shaft along the extension direction of the inclined shaft to penetrate all coal seams; Step 3: Hydraulic fracturing of the coal seam group. During the fracturing process, the coal seams are fracturing in stages from deep to shallow. First, the deepest coal seam is fracturing. According to the seam level, a capsule-type packer is set at 1m positions on the top and bottom plates of the coal seam to be fractured. The capsule packers are connected with connecting rods at predetermined intervals and inserted into the borehole. After reaching the predetermined position, high-pressure water is injected into the capsule packer, causing the capsule to expand and seal the borehole, thus forming a single coal seam fracturing section. Then, high-pressure water is injected into the coal seam using a high-pressure water injection pump. After fracturing is completed, the high-pressure water in the capsule packer is drained, the capsule packer shrinks, and the capsule packer is pulled out of the borehole. The fracturing method is then used to complete the fracturing of the next coal seam according to its level, thus gradually completing the fracturing of all coal seams and increasing the extraction radius. Step 4: Insert the extraction pipe and drainage pipe into the bottom of the borehole respectively, and seal the borehole at the borehole opening using a "two-plug-one-injection" sealing process. After sealing, inject high-pressure air into the extraction pipe and drain the water from the borehole through the drainage pipe. After the water is drained, connect the extraction pipe to the mine's extraction system via a flexible extraction hose for extraction. Measure the daily pure gas extraction volume using the extraction system's metering device. Subtract the cumulative extracted gas volume from the total original gas volume in the coal seam and divide by the weight of the coal in the extraction area to obtain the gas content per ton of coal reduced to 8m³. 3 When the methane content is below 8 m³ / t, an effectiveness test is conducted. A directional drilling rig is used to drill holes into the coal seam being drained. During the drilling process, core samples are taken from each coal seam to measure the methane content. The test is completed when the methane content at all core sampling points in all coal seams drops to 8 m³ / t. 3 When the sampling rate is below / t, the sampling can be considered to meet the standard. Step 5: After the extraction meets the standards, in order to further reinforce the fracturing coal body, high-pressure cement slurry is injected into the coal seam in the coal uncovering area through the extraction borehole using a high-pressure grouting pump. The injection pressure of the high-pressure cement slurry is 10MPa. When the pressure of the injected cement slurry suddenly increases, the injection of cement slurry is stopped. Ten days after the cement slurry is injected, it will be fully solidified, and the next coal uncovering work will be carried out. Step Six: Uncover the coal seam.

[0005] Furthermore, the hydraulic fracturing radius in step three is 15m.

[0006] Furthermore, the high-pressure water in step three is 20 MPa, and the water injection volume is ≥150 m³. 3 The fracturing radius is 18~22m.

[0007] Furthermore, small holes are drilled in the wall of the extraction tube in step four.

[0008] Furthermore, the drilling locations in step four are respectively 5m, 10m, and 15m outside the extraction drilling holes.

[0009] Furthermore, in step five, the cement slurry is prepared in the following ratio: cement: water glass: water = 1:1:0.5.

[0010] The beneficial effects of this invention are as follows: (1) This invention, through the joint exposure of coal seams, allows for simultaneous gas extraction from all coal seams, saving a significant amount of time in disaster management; (2) By constructing directional drilling and implementing hydraulic fracturing, the present invention can realize gas extraction in the coal seam area with a single borehole, which saves a lot of drilling work compared with ordinary borehole construction in single coal seam. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of the overall structure of the present invention; In the figure: 1- Inclined shaft; 2- Coal seam group; 3- Directional long borehole. Detailed Implementation

[0013] 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.

[0014] Please see the appendix Figure 1 This invention provides a method for rapid coal seam uncovering in a deviated shaft, comprising the following steps: Step 1: Construct the inclined shaft 1 to the predetermined position; Step 2: Drill a long directional borehole 3 at the bottom of the inclined shaft 1 along the extension direction of the inclined shaft 1 to penetrate all coal seams; Step 3: Hydraulic fracturing of the coal seam group. During the fracturing process, the coal seams are fracturing in stages from deep to shallow. First, the deepest coal seam is fracturing. According to the seam level, a capsule-type packer is set at 1m positions on the top and bottom plates of the coal seam to be fractured. The capsule packers are connected with connecting rods at predetermined intervals and inserted into the borehole. After reaching the predetermined position, high-pressure water is injected into the capsule packer, causing the capsule to expand and seal the borehole, thus forming a single coal seam fracturing section. Then, high-pressure water is injected into the coal seam using a high-pressure water injection pump. After fracturing is completed, the high-pressure water in the capsule packer is drained, the capsule packer shrinks, and the capsule packer is pulled out of the borehole. The fracturing method is then used to complete the fracturing of the next coal seam according to its level, thus gradually completing the fracturing of all coal seams and increasing the extraction radius. Step Four: Sealing the Borehole for Gas Drainage and Effectiveness Verification: The extraction pipe and drainage pipe are respectively inserted to the bottom of the borehole. A "two-plug-one-injection" sealing process is used at the borehole opening. After sealing, high-pressure air is injected into the extraction pipe, and water is drained from the borehole through the drainage pipe. After the water is drained, the extraction pipe is connected to the mine's gas extraction system via a flexible extraction hose for drainage. The daily pure gas extraction volume is measured using the metering device of the extraction system. The total original gas volume in the coal seam is subtracted from the cumulative extracted gas volume, and then divided by the weight of the coal in the extraction area to obtain the gas content per ton of coal reduced to 8m³. 3 When the methane content is below 8 m³ / t, an effectiveness test is conducted. A directional drilling rig is used to drill holes into the coal seam being drained. During the drilling process, core samples are taken from each coal seam to measure the methane content. The test is completed when the methane content at all core sampling points in all coal seams drops to 8 m³ / t. 3 When the sampling rate is below / t, the sampling can be considered to meet the standard. Step 5: After the extraction meets the standards, in order to further reinforce the fracturing coal body, a high-pressure grouting pump is used to inject high-pressure cement slurry into the coal seam in the coal exposure area through the extraction borehole. The injection pressure of the high-pressure cement slurry is 10MPa. When the pressure of the injected cement slurry suddenly increases, the injection of cement slurry is stopped. Ten days after the cement slurry is injected, it will be fully solidified, and the next coal exposure work will be carried out.

[0015] Step Six: Uncover the coal seam.

[0016] Preferably, the hydraulic fracturing radius in step three is 15m.

[0017] Preferably, the high-pressure water in step three is 20 MPa, and the water injection volume is ≥150 m³ / h. 3 The fracturing radius is 18~22m.

[0018] Preferably, small holes are drilled in the wall of the extraction tube in step four.

[0019] Preferably, the drilling positions in step four are located 5m, 10m, and 15m outside the extraction drilling holes, respectively.

[0020] Preferably, the cement slurry mix ratio in step five is cement:water glass:water = 1:1:0.5.

[0021] If a single coal seam is exposed, measures need to be implemented for each coal seam according to the exposure procedure, which takes a long time. This invention, by jointly exposing coal seam group 2, allows for simultaneous gas extraction from all coal seams, saving a significant amount of disaster management time. By constructing directional drilling and implementing hydraulic fracturing, gas extraction in the exposed area can be achieved with a single borehole, saving a large amount of drilling work compared to ordinary boreholes for single coal seam construction.

[0022] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on these embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still combine, add, delete, or otherwise adjust the features of the various embodiments of the present invention according to the circumstances without conflict or creative effort, thereby obtaining different technical solutions that do not fundamentally depart from the concept of the present invention. These technical solutions also fall within the scope of protection of the present invention.

Claims

1. A method for rapid coal seam uncovering in a inclined shaft, characterized in that, Includes the following steps: Step 1: Construct the inclined shaft (1) to the predetermined position; Step 2: Drill a long directional borehole (3) at the bottom of the inclined shaft (1) along the extension direction of the inclined shaft (1) to penetrate all coal seam groups (2); Step 3: Hydraulic fracturing of coal seam group (2) is carried out. During the fracturing process, the fracturing of coal seam group (2) is carried out in stages from deep to shallow. First, the fracturing of the deepest coal seam is carried out. According to the stratum of the coal seam, a capsule-type packer is set at 1m position on the top and bottom plates of the coal seam to be fractured. The capsule packer is connected with a connecting rod at a set interval and sent into the borehole. After reaching the predetermined position, high-pressure water is injected into the capsule-type packer to make the capsule expand and seal the borehole, thereby forming a single coal seam fracturing section. Then, high-pressure water is injected into the coal seam using a high-pressure water injection pump. After the fracturing is completed, the high-pressure water in the capsule-type packer is drained, the capsule-type packer shrinks, and the capsule-type packer is pulled out from the borehole. According to the stratum of the next coal seam to be fractured, the fracturing is completed by the above fracturing method, and then the fracturing of all coal seams is gradually completed to achieve the purpose of increasing the extraction radius. Step 4: Insert the extraction pipe and drainage pipe into the bottom of the borehole respectively, and seal the borehole using a "two-plug-one-injection" sealing process at the borehole opening. After sealing, inject high-pressure air into the extraction pipe and drain the water from the borehole through the drainage pipe. After the water is drained, connect the extraction pipe to the mine's extraction system via a flexible extraction hose for extraction. Measure the daily pure gas extraction volume using the extraction system's metering device. Subtract the cumulative extracted gas volume from the total original gas volume in the coal seam and divide by the weight of the coal in the extraction area to obtain the gas content per ton of coal reduced to 8m³. 3 When the methane content is below 8 m³ / t, an effectiveness test is conducted. A directional drilling rig is used to drill holes into the coal seam being drained. During the drilling process, core samples are taken from each coal seam to measure the methane content. The test is completed when the methane content at all core sampling points in all coal seams drops to 8 m³ / t. 3 When the sampling rate is below / t, the sampling can be considered to meet the standard. Step 5: After the extraction meets the standards, in order to further reinforce the fracturing coal body, high-pressure cement slurry is injected into the coal seam in the coal uncovering area through the extraction borehole using a high-pressure grouting pump. The injection pressure of the high-pressure cement slurry is 10MPa. When the pressure of the injected cement slurry suddenly increases, the injection of cement slurry is stopped. Ten days after the cement slurry is injected, it will be fully solidified, and the next coal uncovering work will be carried out. Step Six: Uncover the coal seam.

2. The method for rapid coal seam uncovering in a inclined shaft according to claim 1, characterized in that, The hydraulic fracturing radius in step three is 15m.

3. The method for rapid coal seam uncovering in a inclined shaft according to claim 1, characterized in that, The high-pressure water used in step three is 20MPa, and the water injection volume is ≥150m³. 3 The fracturing radius is 18~22m.

4. The method for rapid coal seam uncovering in a inclined shaft according to claim 1, characterized in that, Small holes are drilled in the wall of the extraction pipe in step four.

5. The method for combined rapid coal seam uncovering in an inclined shaft according to claim 1, characterized in that, In step four, the drilling locations are 5m, 10m, and 15m outside the extraction drilling holes, respectively.

6. The method for combined rapid coal seam uncovering in an inclined shaft according to claim 1, characterized in that, The cement slurry mix ratio in step five is cement:water glass:water = 1:1:0.5.

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