A drilling method suitable for gas extraction and anti-blowout pressure relief

Abstract

The present invention discloses a drilling method suitable for gas extraction and anti-bumping and pressure relief, which relates to the technical field of coal mine composite dynamic disaster prevention and control, and includes the following steps: S1, constructing a directional large-diameter high-position drilling hole in a hard roof rock layer; S2, constructing branch penetration holes in the directional large-diameter high-position drilling hole at preset intervals in sequence; S3, hydraulic strengthening of drilling holes, using high-pressure water to pre-crack hard roof rock layers, gas-containing rock layers and coal seams through directional large-diameter high-position drilling holes and branch penetration holes; S4, the directional drill bit starts to drill a coal seam horizontal hole from the tail of the last branch penetration hole, and uses the backward hydraulic cavitation technology to construct holes at a certain distance on the coal seam horizontal hole; S5, connecting to the extraction system for gas extraction. The drilling hole and drilling strengthening method constructed by the present invention have the dual functions of pressure relief and anti-bumping and extraction and elimination of sudden, which can realize the use of holes to bring lanes, one hole for multiple uses, effectively reduce composite dynamic disasters, and improve the production efficiency of mines.

Description

Technical Field

[0001] The invention relates to the technical field of coal mine composite power disaster prevention and control, and in particular to a drilling method suitable for gas extraction and anti-blowout pressure relief. Background Art

[0002] With the continuous expansion of mining depth and scale, the geological conditions of mine production have become more complex, and the disaster risk has become more serious. In deep mining, new coal-rock composite dynamic disasters, such as coal and gas outbursts and rock bursts, have emerged. Some coal mines have evolved from low-gas to high-gas and rock burst mines. The coal seams have poor permeability, gas is difficult to extract, gas outburst concentration exceeds the limit, and gas outbursts and explosions occur frequently, which seriously affect the safe and efficient production of coal mines. At the same time, the mining process is also faced with rock burst risks such as strong mine pressure, tunnel spalling, roof collapse, support crushing, and large-area suspended roof. Once the energy accumulated in the rock mass is released, it will cause major safety accidents such as casualties of operators and damage to mechanical equipment, which seriously restricts the safe and efficient advancement of mines. Therefore, it is urgent to seek a composite disaster management method that can take into account gas outburst elimination and anti-burst pressure relief, and realize the coordinated management of gas disasters and rock burst disasters.

[0003] However, the existing coal mine complex disaster management and prevention technology requires corresponding disaster management and prevention work for different types of disasters to ensure the safety of mine production, and cannot form coordinated management in time and space. In other words, special control and prevention measures are required for each disaster. Gas and mine pressure management work are separated from each other, and a large number of tunnel projects need to be excavated. The construction of disaster management drilling holes is single and cannot achieve universal and multiplier results. It causes invisible waste of drilling construction efficiency and resources. Drilling holes for a variety of different purposes requires a large workload and high disaster management costs. The management process is complex, time-consuming and labor-intensive, and the production efficiency is low, which is not conducive to mining and excavation succession and safety management. Too much underground construction will inevitably increase the production cost of the mine and reduce the production efficiency of the mine. Therefore, exploring a drilling collaborative management method suitable for gas extraction and anti-blowout pressure relief to achieve "one hole for multiple uses, with a hole to lead the tunnel" has obvious practical significance for improving the production efficiency of the mine. Summary of the invention

[0004] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a drilling method suitable for gas extraction and anti-burst pressure relief, so as to reduce the construction and disaster prevention costs, realize multiple uses of one hole, and achieve coordinated management of gas disasters and rock burst disasters.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A drilling method suitable for gas extraction and anti-blowout pressure relief comprises the following steps:

[0007] S1: Construct a directional large-diameter high-position drill hole in the drilling site near the stop-mining line in the hard roof rock formation, and construct the next directional large-diameter high-position drill hole along the coal seam inclination at a set distance from the first directional large-diameter high-position drill hole, and proceed in sequence until all directional large-diameter high-position drill holes in the hard roof rock formation are constructed.

[0008] S2: construct branch penetration holes. When the directional large-diameter high-position drilling hole is drilled to a set depth and then withdrawn, branch penetration holes are constructed in sequence at preset intervals until the last branch penetration hole on the directional large-diameter high-position drilling hole is constructed.

[0009] S3: Hydraulic enhancement of drilling, using high-pressure water to pre-crack hard roof rock, gas-bearing rock and coal seams through directional large-diameter high-position drill holes and branch penetration holes.

[0010] S4: Directional drilling technology is used. The directional drill bit starts from the tail of the last branch penetration hole and drills into the horizontal hole of the coal seam along the direction of the coal seam. The horizontal hole of the coal seam is drilled to the target depth and then retreated. Then, the retreat hydraulic hole-making technology is used to construct holes at a certain distance on the horizontal hole of the coal seam.

[0011] S5: The extraction system is connected from the directional large-diameter high-position borehole in the drilling site to extract gas from hard roof rock, gas-containing strata, and coal seam gas.

[0012] Specifically, the diameter range of the directional large-diameter high-position drilling in step S1 is 200-300 mm.

[0013] Specifically, in step S1, the distance between two adjacent directional large-diameter high-position boreholes is equal, and they are at the same horizontal position and parallel in space; the sides of the air inlet lane and the air return lane are located in the pressure relief control area of ​​the directional large-diameter high-position boreholes.

[0014] Specifically, each directional large-diameter high-position drill hole in step S2 is composed of a plurality of other branch penetration holes and a final branch penetration hole, and spatially all branch penetration holes on a directional large-diameter high-position drill hole are located on the same plane.

[0015] Specifically, in step S2, the vertical distance that the branch penetration hole extends into the coal seam is 2 m, the aperture of the branch penetration hole is 150 mm, and the horizontal distance between two adjacent branch penetration holes in the direction of the coal seam is 10 m.

[0016] Specifically, the drilling construction in step S2 adopts a directional drilling process, and the branch through-layer holes adopt a backward construction method.

[0017] Specifically, in step S3, hydraulic fracturing measures can be repeatedly implemented to repeatedly flush the fracture channels, so that the fractures continue to extend and penetrate, forming a multi-level fracture network, and the pressure relief range continues to increase.

[0018] Specifically, in step S4, the diameter of the coal seam horizontal hole is 120 mm, and the coal seam horizontal hole and other branch cross-layer holes are interconnected.

[0019] Specifically, in step S4, the diameter of the cave is 1 m, and the distance between two adjacent caves along the coal seam is 5 m.

[0020] Specifically, the extraction work in step S5 is divided into three stages in terms of time:

[0021] Before mining begins: the constructed directional large-diameter high-position drill holes and branch through-layer holes, coal seam horizontal holes and holes are used to pre-extract coal and gas from the rock strata.

[0022] During mining, gas is extracted from adjacent gas-bearing strata, coal seams, coal in front of the working face, rock pressure relief areas, and gas gushing out during the mining process of the working face.

[0023] After mining is completed, gas can be extracted from the goaf, upper corners and fracture zones in the "three zones" through branch through-holes and directional large-diameter high-position drilling holes.

[0024] Furthermore, the gas gushing out during the mining process of the working face during the mining period includes: gas desorbed from the exposed coal wall, gas desorbed from the coal falling process, and gas desorbed from the abandoned coal.

[0025] Optionally: After gas extraction is completed, high-pressure water is injected into the coal seam through the last branch, so that water enters the cracks to moisten and soften the coal body, further reducing the impact tendency of the coal body, and also playing a role in dust reduction during the mining process.

[0026] The beneficial effects of the present invention are:

[0027] The present invention discloses a drilling method suitable for gas extraction and anti-blowout pressure relief. A high-position directional large-diameter main hole is constructed in the roof of a coal seam, and branch penetration holes are opened on the basis of the main hole. The drilling is hydraulically enhanced to pre-crack hard roof rock layers, gas-containing rock layers and coal seams. Then, a horizontal hole in the coal seam is drilled from the tail of the last branch penetration hole along the direction of the coal seam. The horizontal hole in the coal seam and the branch penetration hole are interconnected. After the horizontal hole in the coal seam is drilled to a predetermined depth, the drill is withdrawn to hydraulically create a hole in sections, and finally the hole is connected to an extraction system for gas extraction.

[0028] The present invention discloses a drilling method suitable for gas extraction and anti-bumping pressure relief. After the constructed borehole is hydraulically enhanced and the hole-making process is improved, a local pressure relief area can be formed around the borehole to reduce the stress concentration inside the coal and rock formations. After the gas is extracted through the borehole, the gas pressure inside the coal and rock is reduced, weakening the driving force of the outburst. In addition to being used as a pressure relief and anti-bumping borehole and a pressure relief and anti-bumping borehole, the borehole can efficiently extract gas from adjacent gas-containing strata, coal seams, pressure relief areas in front of the working face, and gas gushing out during the mining process of the working face. After the mining is completed, the gas in the goaf, upper corners, and fissure zones in the "three zones" can be extracted by replacing the high-extraction lanes with branched through-layer holes and directional large-diameter high-position boreholes. Thereby, the lanes are replaced by holes, and one hole is used for multiple purposes, which can effectively reduce compound dynamic disasters and improve the production efficiency of mines. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A flowchart of the steps of the present invention

[0030] Figure 2 Schematic diagram of the cross-sectional arrangement of the boreholes in the direction of the coal seam in the present invention

[0031] Figure 3 Schematic diagram of the cross-sectional arrangement of the boreholes in the coal seam dip direction in the present invention

[0032] Figure 4 Schematic diagram of the drilling plane layout in the present invention

[0033] Reference numerals:

[0034] 1-adjacent layer; 2-directional large-diameter high-position drilling hole; 3-hard roof rock stratum fracturing section fissure; 4-bend lower layer zone; 5-fracture zone; 6-collapse zone; 7-bottom plate; 8-branch through-layer hole gas-bearing rock stratum fissure; 9-working face; 10-branch through-layer hole coal seam section fissure; 11-hole; 12-coal seam; 13-gas-bearing rock layer; 14-last branch through-layer hole; 15-drilling site; 16-hard roof rock layer; 17-other branch through-layer holes; 18-coal seam horizontal hole; 19-entry tunnel; 20-return air tunnel; 21-tunnel roof pressure relief area; 22-cutting eye; 23-directional large-diameter high-position drilling hole roof pressure relief and anti-bumping control area DETAILED DESCRIPTION

[0035] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0036] like Figures 1 to 4 As shown, the present invention provides a drilling method suitable for gas extraction and anti-blowout pressure relief, comprising the following steps:

[0037] S1: Construct a directional large-diameter high-position drill hole in the drilling site near the stop-mining line in the hard roof rock formation, and construct the next directional large-diameter high-position drill hole along the coal seam inclination at a set distance from the first directional large-diameter high-position drill hole, and proceed in sequence until all directional large-diameter high-position drill holes in the hard roof rock formation are constructed.

[0038] S2: construct branch penetration holes. When the directional large-diameter high-position drilling hole is drilled to a set depth and then withdrawn, branch penetration holes are constructed in sequence at preset intervals until the last branch penetration hole on the directional large-diameter high-position drilling hole is constructed.

[0039] S3: Hydraulic enhancement of drilling, using high-pressure water to pre-crack hard roof rock, gas-bearing rock and coal seams through directional large-diameter high-position drill holes and branch penetration holes.

[0040] S4: Directional drilling technology is used. The directional drill bit starts from the tail of the last branch penetration hole and drills into the horizontal hole of the coal seam along the direction of the coal seam. The horizontal hole of the coal seam is drilled to the target depth and then retreated. Then, the retreat hydraulic hole-making technology is used to construct holes at a certain distance on the horizontal hole of the coal seam.

[0041] S5: The extraction system is connected from the directional large-diameter high-position borehole in the drilling site to extract gas from hard roof rock, gas-containing strata, and coal seam gas.

[0042] Specifically, the final hole position of the directional large-diameter high-position drilling in step S1 is 10m in front of the coal wall roof of the working face, which can effectively eliminate the risk of rock burst caused by the stress concentration area in front of the coal wall roof of the working face.

[0043] Specifically, in step S1, the vertical distance between the directional large-diameter high-position borehole and the top of the gas-containing formation is 2 m.

[0044] Specifically, in step S1, according to the actual geological conditions, the diameter range of the directional large-diameter high-position drilling hole is 200-300 mm to meet the anti-blowout and pressure relief requirements of the hard roof rock layer.

[0045] Specifically, in step S1, the distance between two adjacent directional large-diameter high-position drill holes is equal, and they are at the same horizontal position and parallel in space.

[0046] Specifically, in step S1, the sides of the air inlet tunnel and the air return tunnel are located in the pressure relief control area of ​​the nearest directional large-diameter high-position drilling hole.

[0047] Specifically, in step S1, the rock properties of the hard roof strata are stable, the directional large-diameter high-position drilled holes constructed are not easy to collapse, and the rock strata of the tunnel side and the roof strata can be depressurized.

[0048] Specifically, in step S2, all branch through-layer holes on a directional large-diameter high-position borehole in space are located on the same plane.

[0049] Specifically, in step S2, the vertical distance that the branch penetration hole extends into the coal seam is 2 m, the aperture of the branch penetration hole is 150 mm, and the horizontal distance between two adjacent branch penetration holes in the direction of the coal seam is 10 m.

[0050] Specifically, each directional large-diameter high-position drill hole in step S2 is composed of a plurality of other branch penetration holes and a final branch penetration hole.

[0051] Specifically, in step S2, the branch penetration holes are constructed using a backward construction method. After the directional large-diameter high-position drilling hole is drilled to a predetermined depth, the drill begins to be withdrawn. When the drill is withdrawn to a branch point reserved for the directional large-diameter high-position drilling hole, the elbow of the drill bit rotates downward at a set angle at a low speed. The branch penetration holes sequentially pass through the hard roof rock layer and the gas-containing rock layer until the designed branch hole depth in the coal seam is reached. Then the drill is withdrawn to continue constructing the branch penetration hole at the next reserved branch point.

[0052] Specifically, the drilling construction in step S2 adopts a directional drilling process. The drilling route of the drill rod can be accurately controlled by the operating console to construct according to the set trajectory, and branch holes can be opened at the predetermined position of the directional large-diameter high-position drilling hole. The drilling route can be obtained in real time by the positioning system of the drill bit.

[0053] Specifically, in step S3, parameters such as hydraulic fracturing time, water pressure, water injection volume, etc. are based on the impact range of hydraulic fracturing to meet the pressure relief requirements and ensure safe mining.

[0054] Specifically, in step S3, hydraulic fracturing measures can be repeatedly implemented to repeatedly flush the fracture channels, so that the fractures continue to extend and penetrate, forming a multi-level fracture network, and the pressure relief range continues to increase.

[0055] Specifically, in step S3, the fracture networks around each borehole are interconnected to form a weakened pressure-relieving energy-absorbing zone, relieve stress concentration, and effectively prevent and control rock bursts; fracturing makes the original fractures more developed and the new fractures generated play a role in increasing the permeability of gas-containing strata and coal seams, strengthens the gas flow capacity, and is conducive to gas extraction and sudden relief.

[0056] Specifically, in step S4, the diameter of the coal seam horizontal hole is 120 mm, and the coal seam horizontal hole and other branch cross-layer holes are interconnected.

[0057] Specifically, the final hole position of the coal seam horizontal hole in step S4 is located 10m in front of the coal wall of the working face, which can effectively eliminate the risk of protrusion caused by the stress concentration area in front of the working face.

[0058] Specifically, the hydraulic cavitation technology in step S4 uses a 10-20MPa jet water pressure to perform high-pressure hydraulic impact on the coal seam around the borehole to expand the borehole diameter. After the coal slag and gas are discharged with the return water, holes are formed on the basis of the borehole, releasing the stress of the coal seam. The permeability of the coal seam around the hole is enhanced. Under the effect of pressure relief and permeability enhancement, the gas is quickly transported from the cracks to the borehole and discharged through the extraction pipeline, which is beneficial to extraction.

[0059] Specifically, in step S4, the diameter of the cave is 1 m, and the distance between two adjacent caves along the coal seam is 5 m.

[0060] Specifically, in step S4, a backward hydraulic hole-making process is adopted. After the horizontal hole of the coal seam is drilled to the expected depth, the hydraulic hole-making process is carried out during the process of withdrawing the drill. When the drill is withdrawn to the predetermined hole-making position of the horizontal hole of the coal seam, the drill is stopped and a high-pressure hydraulic punching operation is performed. After the hole-making is completed, the drill is continued to be withdrawn, and the process is repeated in sequence until the construction of all holes is completed.

[0061] Specifically, the extraction work in step S5 is divided into three stages in terms of time:

[0062] Before mining begins: the constructed directional large-diameter high-position drill holes and branch through-layer holes, coal seam horizontal holes and holes can relieve pressure and prevent impact on the coal and rock masses. After hydraulic strengthening, the drill holes can again relieve pressure, eliminate sudden impacts and prevent impacts. Under the action of the negative pressure of extraction, the gas inside the coal and rock formations seeps into the drill holes through the cracks and is continuously recovered. After pre-extraction of the coal seam gas, the gas pressure and content of the coal seam are reduced, preventing sudden impact accidents during excavation of the working face.

[0063] During mining, the adjacent gas-containing strata are depressurized due to mining, causing the original hydraulic cracks to expand and extend and penetrate the coal seam. As mining work continues to advance, a depressurization zone is formed in the coal and rock mass in front of the working face. In this area, the coal and rock mass cracks are developed and the permeability is significantly enhanced. At this time, the drilling holes can efficiently extract the gas from the adjacent gas-containing strata, the coal seam, the coal in front of the working face, the rock mass depressurization zone, and the gas gushing out during the mining process of the working face.

[0064] After mining is completed, gas can be extracted from the goaf, upper corners and fracture zones in the "three zones" through branch through-layer holes and directional large-diameter high-position drilling holes, effectively reducing gas hazards.

[0065] Furthermore, the gas gushing out during the mining process of the working face includes: gas desorbed from the exposed coal wall, gas desorbed during the coal falling process, and gas desorbed from the abandoned coal.

[0066] Optionally: After the gas extraction is completed, high-pressure water can be injected into the coal seam through the last branch, so that the water enters the cracks to moisten and soften the coal body, and further reduce the impact tendency of the coal body. At the same time, it can also play a role in dust reduction during the mining process.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A drilling method suitable for gas extraction and anti-blowout pressure relief, characterized in that: The following steps are involved: S1: construct a directional large-diameter high-position drill hole in the drilling site near the stop-mining line in the hard roof rock formation, and construct the next directional large-diameter high-position drill hole along the coal seam inclination at a set distance from the first directional large-diameter high-position drill hole, and continue in sequence until all directional large-diameter high-position drill holes in the hard roof rock formation are constructed; S2: construct branch penetration holes. When each directional large-diameter high-position drilling hole is drilled to a set depth and then drilled back, branch penetration holes are constructed in sequence at preset distances until the last branch penetration hole on the directional large-diameter high-position drilling hole is constructed; S3: Hydraulic drilling enhancement, using high-pressure water to pre-crack hard roof rock, gas-bearing rock and coal seams through directional large-diameter high-position drill holes and branch penetration holes; S4: Directional drilling technology is used. The directional drill bit starts from the tail of the last branch penetration hole and drills into the coal seam horizontal hole along the coal seam direction. The coal seam horizontal hole is drilled to the target depth and then retreated. Then, retreat hydraulic cavitation technology is used to construct holes at a certain interval on the coal seam horizontal hole. S5: Connect the extraction system from the directional large-diameter high-position borehole in the drilling site to extract gas from hard roof rock, gas-containing rock, and coal seam; The extraction work can be divided into three stages in terms of time, including: pre-extraction of coal and gas inside the rock formation through directional large-diameter high-position drilling holes and branch through-layer holes, horizontal holes and holes in the coal seams constructed before the start of mining; extraction of gas from adjacent gas-containing rock formations and coal seams, coal in front of the working face, rock mass pressure relief areas, and gas gushing out during the mining process of the working face during mining; extraction of gas from the goaf, upper corners, and fracture zones in the "three zones" through branch through-layer holes and directional large-diameter high-position drilling holes after the mining is completed.

2. A drilling method suitable for gas extraction and anti-blowout pressure relief according to claim 1, characterized in that: In the step S1, the diameter of the directional large-diameter high-position drilling hole ranges from 200 to 300 mm.

3. A drilling method suitable for gas extraction and anti-blowout pressure relief according to claim 1, characterized in that: In step S1, the distance between two adjacent directional large-diameter high-position boreholes is equal, and they are at the same horizontal position and parallel in space; the sides of the air inlet lane and the air return lane are located in the pressure relief control area of ​​the directional large-diameter high-position boreholes.

4. A drilling method suitable for gas extraction and anti-blowout pressure relief according to claim 1, characterized in that: In step S2, each branch penetration hole of a directional large-diameter high-position drill hole is composed of a plurality of other branch penetration holes and a final branch penetration hole. In space, all branch penetration holes of a directional large-diameter high-position drill hole are located on the same plane.

5. A drilling method suitable for gas extraction and anti-blowout pressure relief according to claim 1, characterized in that: In step S2, the vertical distance that the branch penetration hole extends into the coal seam is 2m, the diameter of the branch penetration hole is 150mm, and the horizontal distance between two adjacent branch penetration holes in the direction of the coal seam is 10m.

6. A drilling method suitable for gas extraction and anti-blowout pressure relief according to claim 1, characterized in that: In step S2, the drilling construction adopts a directional drilling process, and the branch penetration holes adopt a backward construction method.

7. A drilling method suitable for gas extraction and anti-blowout pressure relief according to claim 1, characterized in that: In step S3, hydraulic fracturing measures may be repeatedly implemented to repeatedly flush the fracture channels, so that the fractures are continuously extended, expanded and connected, forming a multi-level fracture network, and the pressure relief range is continuously increased.

8. A drilling method suitable for gas extraction and anti-blowout pressure relief according to claim 1, characterized in that: In the step S4, the diameter of the coal seam horizontal hole is 120 mm, and the coal seam horizontal hole is interconnected with other branch penetration holes except the last branch penetration hole.

9. A drilling method suitable for gas extraction and anti-blowout pressure relief according to claim 1, characterized in that: In step S4, the hole diameter is 1 m, and the distance between two adjacent holes along the coal seam is 5 m.

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