A method for directional drilling layout integrating "pressure relief-extraction-monitoring"

Abstract

This invention belongs to the field of underground coal mine drilling technology, specifically a method for integrated directional drilling layout that combines pressure relief, extraction, and monitoring. It includes: excavating a drilling site near the coal seam in the main roadway of the mining area; and constructing boreholes in the coal seam, the lower part of the caving zone, and the fracture zone in a single operation within the drilling site before the working face roadway excavation. The coal seam boreholes are used to detect the height of the coal seam roof and floor, gas extraction, pressure relief, and monitor drill cuttings volume during roadway excavation and mining; gas extraction is performed via a connection to the extraction pipeline. The lower part of the caving zone boreholes are used for pre-extraction of gas from the coal seam, gas extraction from the goaf after working face mining, and determining the position of the coal seam roof; gas extraction is performed via the extraction pipeline. The fracture zone boreholes are used for gas extraction from the fracture zone after working face mining, with the gas incorporated into the extraction pipeline. This invention pre-depressurizes the coal seam, extends the drilling extraction cycle, monitors the position of the coal seam roof and floor, and maximizes borehole utilization.

Description

Technical Field

[0001] This invention belongs to the field of underground drilling technology in coal mines, specifically a method for directional drilling layout that integrates "pressure relief-extraction-monitoring". Background Technology

[0002] Currently, the common method for dealing with coal and rock gas dynamic hazards is drilling. The location and arrangement of these boreholes have the greatest impact on their extraction and pressure relief effects. Common borehole locations include boreholes within the coal seam and boreholes in fracture zones. Borehole arrangements include in-seam boreholes and cross-seam boreholes. In addition, there are boreholes with different functions at different times. However, due to the tight succession of mining operations in underground coal mines, current gas extraction methods often employ multiple methods simultaneously. However, the coordination and cooperation between these various extraction boreholes can easily create extraction gaps.

[0003] The problem that this invention needs to solve is how to further reveal the laws of coal and rock dynamic disasters, apply their laws and accident principles to generate scientific methods for their early prevention and control, and especially combine the specific characteristics of my country's coal mines to design an inverted "π"-shaped directional borehole layout method that alleviates the tension of mining and tunneling succession, has a long drilling cycle, covers the entire tunneling and mining cycle, and integrates the spatiotemporal three-dimensional coal and rock dynamic disasters. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides an integrated directional drilling layout method that combines pressure relief, extraction, and monitoring.

[0005] The present invention adopts the following technical solution: a directional drilling layout method integrating "pressure relief-extraction-monitoring", including: excavating a drilling site on the side of the main roadway of the mining area close to the coal body, and constructing the coal seam borehole, the lower part of the caving zone borehole and the fracture zone borehole in the drilling site in one go before the working face roadway is excavated. The final hole positions of the coal seam borehole, the lower part of the caving zone borehole and the fracture zone borehole are respectively located in the coal seam, the lower part of the caving zone and the fracture zone.

[0006] This coal seam borehole is used to detect the height of the coal seam roof and floor, gas drainage, pressure relief, and drill cuttings during roadway excavation and mining. It is connected to the drainage pipeline for gas drainage.

[0007] The lower part of the collapse zone is drilled for gas pre-drainage of this coal seam, gas drainage of the goaf after the working face is mined, and determining the location of the coal seam roof. Gas drainage is carried out through the drainage pipeline.

[0008] The fracture zone borehole is used for gas extraction from the fracture zone after the working face has been mined, and the gas is then incorporated into the extraction pipeline.

[0009] In some embodiments, the boreholes in this coal seam are arranged horizontally with a spacing of twice the effective gas extraction radius of the borehole, and the boreholes are arranged within a range of 20m on both sides of the roadway; in the vertical direction, if the coal seam is thin, the boreholes in this coal seam are arranged in the middle of the coal seam; if the coal seam is thick, the boreholes in this coal seam are arranged in two rows, one above the other.

[0010] In some embodiments, the effective extraction area of ​​the borehole below the caving zone is in contact with the coal seam.

[0011] In some embodiments, the effective sampling area is calculated according to the following formula:

[0012] 1) If the roof of the coal seam does not contain gas,

[0013]

[0014] Where c is the height of the lower part of the collapse zone; R is the borehole diameter;

[0015] 2) If the roof of the coal seam contains gas,

[0016]

[0017] in, c ' is the height of the lower part of the collapse zone; d is the distance between the borehole and the roof of the coal seam, 0 < d ≤ 5r.

[0018] In some embodiments, the horizontal spacing of the boreholes under the caving zone is set to 5m, and the boreholes under the caving zone are arranged within a range of 20m on both sides of the roadway. If the coal seam is thin, the boreholes under the caving zone are constructed within a range of 10m on both sides of the roadway.

[0019] In the vertical direction, the boreholes are arranged in the lower part of the caving zone, and the distance between the boreholes in the lower part of the caving zone and the roof of the coal seam is less than or equal to 5 times the borehole diameter.

[0020] In some embodiments, the fracture zone boreholes are arranged vertically between the caving zone and the height of the fracture zone, with a vertical spacing of 5m to 20m; in the horizontal direction, the distance between the projection of the fracture zone boreholes in the coal seam and the centerline of the roadway increases, with a horizontal spacing of 5m to 25m.

[0021] In some embodiments, the height of the runoff zone is calculated using the following formula:

[0022]

[0023] In the formula, a is the height of the caving zone; h is the coal seam mining height; Kp is the coefficient of caving rock fragmentation; and α is the coal seam dip angle.

[0024] In some embodiments, the fracture zone height is calculated using the following formula:

[0025]

[0026] In the formula, b is the maximum height of the fracture zone; h is the coal seam mining height.

[0027] In some embodiments, the boreholes in the coal seam, the lower part of the caving zone, and the fracture zone are arranged in an inverted "π" shape at the target stratum.

[0028] Compared with existing technologies, this invention addresses the current needs of efficient and intelligent mine construction by providing a more convenient and simpler directional drilling layout method that integrates pressure relief, gas extraction, and monitoring. This drilling layout method draws on the advantages of multi-level branch wells on the surface and directional drilling in underground coal mines, proposing a method that covers the entire timeframe from roadway excavation to face mining, while simultaneously providing functions such as pressure relief, gas extraction, drill cuttings monitoring, and roof and floor position detection.

[0029] This invention stems directly from the critical needs of actual coal mine safety production, directly serves coal mine safety production, and meets the market demands of the coal mining industry and coal mine safety. Coal mine coal and rock dynamic disasters are characterized by their potential and suddenness, and often cause significant damage in a short period of time, making them a key focus and challenge in daily coal mine production. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the inverted "π" shaped directional drilling arrangement method in this invention;

[0031] Figure 2 for Figure 1 Mid-section AA, left view of the borehole;

[0032] Figure 3 for Figure 1 The mid-section BB is a schematic diagram of the borehole front view;

[0033] Figure 4 This is a spatial diagram of the inverted "π"-shaped directional borehole and the goaf during the working face mining period in this invention;

[0034] In the diagram: 1-fracture zone; 2-upper part of caving zone; 3-lower part of caving zone; 4-coal seam; 5-floor plate; 6-Drilling site No. 1; 7-intake airway; 8-working face; 9-hydraulic support; 10-goaf; 11-fracture zone borehole; 12-lower part of caving zone borehole; 13-coal seam borehole; 14-Drilling site No. 2; 15-return airway; 16-intake airway of the next working face; 17-cut-in. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0036] A method for directional drilling that integrates "pressure relief-extraction-monitoring" involves excavating a drilling site 6 in the main roadway of the mining area near the coal seam. Before the working face roadway is excavated, boreholes 13 in the coal seam, 12 in the lower part of the caving zone, and 11 in the fracture zone are constructed in one go within the drilling site. The final positions of the boreholes are located in the coal seam 4, the lower part of the caving zone 3, and the fracture zone 1, respectively. The construction is carried out using drilling rigs with directional capabilities, such as kilometer-level drilling rigs.

[0037] The extraction boreholes are as follows:

[0038] (1) Borehole 13 in this coal seam is used to detect the height of the top and bottom plates of the coal seam, gas extraction, pressure relief and drill cuttings during roadway excavation and mining. It is connected to the extraction pipeline for gas extraction.

[0039] (2) Drill hole 12 at the bottom of the collapse zone for gas pre-drainage of this coal seam, gas drainage of the goaf after the working face is mined, and determination of the location of the coal seam roof. Gas drainage is carried out through the drainage pipeline.

[0040] (3) 11 holes in the fracture zone are used for gas extraction in the fracture zone after the working face is mined, and the gas is incorporated into the extraction pipeline.

[0041] The target strata of several of the main boreholes are in the shape of an inverted "π". The boreholes in this coal seam control the roadway and the surrounding area, and the borehole table in the lower part of the caving zone and the fracture zone spreads outward.

[0042] 1) Drilling layout for this coal seam:

[0043] 13 boreholes were drilled in this coal seam to control gas levels in the roadway excavation section and the coal seam on both sides of the roadway. Based on the determination of the effective gas extraction radius of a kilometer-long borehole, and with a safety factor, the effective gas extraction radius of the kilometer-long borehole was set at 2.5m. Horizontally, the borehole spacing was set at 5m, and the boreholes were arranged within a 20m range on both sides of the roadway. Vertically, if the coal seam thickness was less than 4m, the boreholes were arranged in the middle of the coal seam; if the coal seam thickness was greater than 4m, two rows of boreholes should be installed, one above the other.

[0044] 2) Drilling arrangement in the lower part of the collapse zone:

[0045] Borehole 12, located in the lower part of the caving zone, requires pre-drainage of gas from the coal seam before roadway excavation. Therefore, the effective drainage area of ​​the borehole must be in contact with the coal seam. The permeability of the rock roof is much lower than that of the coal seam, resulting in a smaller effective gas drainage radius for the borehole within the rock strata. According to the pressure relief zone theory, the pressure relief range around a circular borehole is 3 to 5 times the borehole diameter. Therefore, the area above the coal seam roof, 5 times the borehole diameter, is defined as the effective drainage range for pre-drainage of gas from the coal seam using rock strata boreholes, referred to as the lower part of the caving zone. Boreholes arranged within this range can pre-drain gas from the coal seam. The range is shown in the following formula.

[0046]

[0047] Where c is the height of the lower part of the collapse zone, in meters; and R is the borehole diameter, in meters.

[0048] If the roof of the coal seam contains gas, the maximum effective gas extraction area of ​​the borehole in the rock strata is shown in the following formula:

[0049]

[0050] in, It is the height of the lower part of the collapse zone, in meters (m). d It is the distance between the borehole and the roof of the coal seam, in meters, where 0 < d ≤ 5r.

[0051] In the horizontal direction, the borehole spacing is set at 5m, and the boreholes are arranged within a 20m range on both sides of the roadway. If the coal seam is thin, rock boreholes can be drilled only within a 10m range on both sides of the roadway. In the vertical direction, a row of horizontal boreholes is arranged below the caving zone, and the distance between the boreholes and the roof of the coal seam is less than or equal to 5 times the borehole diameter.

[0052] 3) Drilling arrangement within the fracture zone

[0053] Borehole 11 in the fracture zone is mainly used to collect gas that has escaped from the goaf into the rock strata during the working face mining period. If the borehole in the fracture zone is too far from the roof, it cannot extract a large amount of gas; if it is too close to the roof, it will collapse with the collapse of the caving zone. Therefore, determining the height of the caving zone and the fracture zone is a prerequisite for the layout of boreholes in the fracture zone.

[0054] The height of the collapse zone is calculated using the following formula:

[0055]

[0056] In the formula, a The height of the collapse zone, in meters (m). h The coal seam mining height is in meters (m). Kp The coefficient of fragmentation of the collapsed rock; α The dip angle of the coal seam is (°).

[0057] The fracture zone height is the height from the top of the coal seam to the upper part of the fracture zone. The formula for calculating the maximum height of the upper part of the fracture zone in a medium-hard roof is as follows:

[0058]

[0059] In the formula, b The maximum height of the fracture zone is in meters (m). h The height of the coal seam being mined is in meters (m).

[0060] In the vertical direction, the fracture zone boreholes are arranged between the caving zone and the fracture zone height, with a vertical spacing of 5m to 20m. In the horizontal direction, the distance between the projection of the kilometer-long borehole into the coal seam and the centerline of the roadway increases progressively, with a horizontal spacing of 5m to 25m.

[0061] This invention involves constructing several directional multi-branch boreholes in the intake and return airway of the longwall face. These directional boreholes horizontally cover the entire roadway and a 20m wide area around it. Vertically, the final borehole positions of the main boreholes are arranged from top to bottom in the fracture zone, the bottom of the caving zone, and the coal seam itself. The coal seam boreholes branch off from the main boreholes to explore the roof and floor of the coal seam. The boreholes at the bottom of the caving zone branch downwards to penetrate deeper into the coal seam, while the boreholes in the fracture zone branch upwards and downwards to expand the extraction range. Before roadway excavation, the boreholes in the coal seam and the lower part of the caving zone are used for pressure relief, monitoring the position of the coal seam roof and floor, and pre-extracting coal seam gas. After longwall mining, the boreholes in the fracture zone extract gas from the fracture zone, and the boreholes in the lower part of the caving zone are used as buried pipes to extract gas from the goaf, thus achieving a multi-purpose effect with a single borehole. By employing the borehole layout method of the present invention, the coal seam can be depressurized in advance, the borehole extraction cycle can be extended, and the position of the top and bottom plates of the coal seam can be monitored, thereby maximizing the utilization rate of the boreholes.

[0062] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for directional drilling layout integrating "pressure relief-extraction-monitoring", characterized in that, include: In the mining area, a drilling site (6) is excavated on the side of the main roadway close to the coal body. Before the working face roadway is excavated, a drilling site is constructed in one go for the coal seam (13), the lower part of the caving zone (12), and the fracture zone (11). The final positions of the drilling site (13), the lower part of the caving zone (12), and the fracture zone (11) are located in the coal seam (4), the lower part of the caving zone (3), and the fracture zone (1), respectively. The borehole (13) in this coal seam is used to detect the height of the top and bottom plates of the coal seam, gas drainage, pressure relief and drill cuttings during roadway excavation and mining. It is connected to the drainage pipeline for gas drainage. The lower part of the collapse zone is drilled (12) for gas pre-drainage of this coal seam, gas drainage of the goaf after the working face is mined, and determining the position of the coal seam roof. Gas drainage is carried out through the drainage pipeline. The fracture zone borehole (11) is used for gas extraction from the fracture zone after the working face is mined, and the gas is incorporated into the extraction pipeline. In the horizontal direction, the borehole spacing of the coal seam borehole (13) is set to twice the effective gas extraction radius of the borehole, and the boreholes are arranged within a range of 20m on both sides of the roadway; in the vertical direction, if the coal seam thickness is less than 4m, the borehole (13) of the coal seam is arranged in the middle of the coal seam; if the coal seam thickness is greater than 4m, the borehole (13) of the coal seam is arranged in two rows, one above the other. The effective extraction area of ​​the lower borehole (12) in the caving zone is in contact with the coal seam (4); The effective extraction area is calculated according to the following formula: 1) If the roof of the coal seam does not contain gas, in, c It is the height of the lower part of the collapse zone; R It is the borehole diameter; 2) If the roof of the coal seam contains gas, in, c 'It is the height of the lower part of the collapse zone;' d It is the distance between the borehole and the roof of the coal seam, 0 < d ≤ 5R; In the horizontal direction, the spacing of the boreholes (12) in the lower part of the caving zone is set at 5m, and the boreholes (12) in the lower part of the caving zone are arranged within a range of 20m on both sides of the roadway; in the vertical direction, they are arranged in the lower part of the caving zone, and the distance between the boreholes (12) in the lower part of the caving zone and the top plate of the coal seam is less than or equal to 5 times the borehole diameter. The fracture zone boreholes (11) are arranged vertically between the caving zone and the fracture zone height, with a vertical spacing of 5m to 20m; in the horizontal direction, the distance between the projection of the fracture zone boreholes (11) in the coal seam and the center line of the roadway increases, with a horizontal spacing of 5m to 25m. The height of the collapse zone is calculated using the following formula: In the formula, a is the height of the caving zone; h is the coal seam mining height; K p α is the coefficient of fragmentation of the caving rock; α is the dip angle of the coal seam; The fracture zone height is calculated using the following formula: In the formula, b is the maximum height of the fracture zone; h is the coal seam mining height.

2. The integrated directional drilling layout method for "pressure relief-extraction-monitoring" according to claim 1, characterized in that, The boreholes (13) in the coal seam, the lower part of the caving zone (12), and the fracture zone (11) are arranged in an inverted "π" shape at the target stratum.

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