A method for coordinated management of multiple hazards in coal mine roof and floor

Abstract

The application discloses a kind of coal mine roof and floor multiple disaster collaborative management method, directional drilling rig is drilled from ground to the direction of coal mine roof, drilling tool enters into coal mine roof, and along the bedding of coal mine roof, horizontal section is formed, casing is lowered into borehole, the way of hydraulic sandblasting perforating and bottom seal drag fracturing is combined, hole is shot on casing, high pressure water is acted on stratum, coal mine roof is fractured, after fracturing construction, upper casing is pulled out, directional drilling rig is used for secondary drilling construction, drilling tool passes through coal seam and enters into aquifer in coal mine floor, grouting is carried out in aquifer.The application is implemented by fracturing to coal mine floor, the method of advanced exploration management to coal mine floor, hydraulic pressure is carried out in coal mine roof, in the process of working face recovery, coal mine roof high stress is effectively released, by advanced exploration management to coal mine floor, grouting reconstruction is carried out to three lime water-bearing layer.

Description

Technical Field

[0001] This invention relates to the field of mine management technology. Specifically, it is a method for the coordinated management of multiple hazards in the roof and floor of coal mines. Background Technology

[0002] Coal is an important natural resource. With the continuous mining of coal resources, the working faces that have not yet been mined face need to face increasingly complex hydrogeological conditions. For these coal mines and mining projects with complex underground hydrogeology, it is necessary to ensure that the aquifer in the coal mine floor is treated before mining, and to prevent the formation of large-area overhang structures above the goaf during mining, which would cause static stress concentration in the coal and rock mass and prevent impact hazards to the working face.

[0003] Currently, surface grouting is the most commonly used technique for maintaining the stability of coal seam aquifers. It can effectively seal the water inflow channels in the floor and, combined with underground hydraulic fracturing of the coal mine roof, reduce the concentration of static stress on the roof. However, underground fracturing and surface grouting not only take up time in underground roadway excavation but also require a certain amount of underground space, resulting in high construction costs. Furthermore, coordinating construction techniques to ensure the stability of the coal mine roof is also a challenge. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to provide a method for the coordinated management of multiple disasters in the roof and floor of coal mines, which reduces construction costs and improves the safety of coal mining.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for coordinated management of multiple disasters in the roof and floor of coal mines, comprising the following steps:

[0006] Step A: Collect hydrogeological information on the roof and floor of the coal mine that need to be treated, and design the location of boreholes;

[0007] Step B: Using a directional drilling rig, drill from the ground toward the coal mine roof. After passing through the straight section and the inclined section, the drill bit enters the coal mine roof and drills along the coal mine roof to form a horizontal section. During the drilling process, casing is lowered into the borehole.

[0008] Step C: After the casing in the horizontal section is lowered, a combination of water jetting and bottom sealing fracturing is used to create holes in the casing, allowing high-pressure water to act on the formation and fracturing the coal mine roof. This cuts through the formation to release stress, and the process is repeated to achieve segmented fracturing of the horizontal section.

[0009] Step D: After the fracturing operation is completed, use a pipe cutter to cut the casing at a suitable position and pull out the entire upper casing;

[0010] Step E: Based on the original borehole, after optimizing the drilling trajectory, a second drilling operation is carried out using a directional drilling rig to reconstruct the directional section, so that the drill bit passes through the coal seam and enters the aquifer in the bottom plate of the coal mine, and drills along the aquifer to form a horizontal open hole section. During the drilling operation, casing is re-inserted into the straight hole section and the directional section of the borehole.

[0011] Step F: Using grouting equipment, grout is injected into the aquifer to fill and reinforce the cracks and water-conducting channels, increase the effective thickness of the aquifer, and block the aquifer channels.

[0012] In the above-mentioned method for coordinated management of multiple disasters in the roof and floor of a coal mine, during step C, when performing segmented fracturing construction, the spacing between each segment is 50m; each segment of hydraulic sandblasting includes two sets of holes, with a spacing between the sets of holes of 20-27m, and each set of holes includes three holes.

[0013] In the aforementioned method for coordinated management of multiple hazards in coal mine roof and floor, in step B, after passing through the directional drilling section, the drill bit advances along the center of the coal mine roof. The closer the overhang surface above the goaf is to the center, the greater the overhang distance and the more concentrated the stress. Drilling along the coal mine strike at the center of the roof can quickly and effectively release stress and reduce the amount of construction work. In step E, after passing through the directional drilling section, the drill bit advances along one side of the coal mine floor to form the first borehole. Subsequently, the nth borehole parallel to the direction of the first borehole is drilled sequentially towards the other side of the coal mine floor. After the initial construction is completed, grouting is carried out to release the stress on the coal mine roof. The impact of grouting on the strata will not affect the coal mine roof, thus ensuring the safety of the entire construction process. Grouting is first carried out on one side of the coal mine floor. Since the edge of the coal mine floor bears the pressure of the strata and has high stability, the impact on the mining face is small during grouting, and grouting with greater pressure and flow rate can be carried out. As grouting proceeds sequentially, the strength of the bottom layer gradually increases due to the reinforcement layer formed by the previous grouting, and the impact on the strata becomes smaller and smaller, thus ensuring the safety of construction.

[0014] In the above-mentioned method for coordinated management of multiple disasters in the roof and floor of a coal mine, in step B, during the drilling process towards the roof of the coal mine, the borehole adopts three-level diameter and is equipped with three-level casing.

[0015] The above-mentioned method for coordinated management of multiple disasters in the roof and floor of a coal mine involves the following steps: a first-stage borehole with a diameter of 444.5 mm is drilled, and a casing with a diameter of 339.7 mm is installed down to a depth of 5-10 m in the bedrock; a second-stage borehole with a diameter of 311.1 mm is drilled, and a casing with a diameter of 244.5 mm is installed down to a stable sandstone stratum above the coal seam; and a third-stage borehole with a diameter of 215.9 mm is drilled to the final borehole depth, and a casing with a diameter of 139.7 mm is installed.

[0016] In the above-mentioned method for coordinated management of multiple disasters in the roof and floor of a coal mine, in step E, when drilling into the aquifer in the coal mine floor, the first-level opening shares a straight hole section with step B; the second-level opening has a diameter of 215.9 mm, and a casing with a diameter of 177.8 × 8.05 mm is inserted down to the mudstone above the aquifer; the third-level opening is a bare hole drilled in the aquifer with a diameter of 152.4 mm.

[0017] In the above-mentioned method for coordinated management of multiple disasters in the roof and floor of a coal mine, in step B, the drill bit drills into the stable sandstone of the coal mine roof and drills along the bedding; in step E, the drill bit drills into the limestone aquifer and drills along the bedding.

[0018] In the aforementioned method for coordinated management of multiple disasters in the roof and floor of a coal mine, the horizontal drilling direction is parallel to the dip of the strata when drilling is carried out in the roof and floor of the coal mine.

[0019] The technical solution of the present invention achieves the following beneficial technical effects:

[0020] This invention provides a method for simultaneously performing hydraulic fracturing and advanced exploration and treatment of the coal mine floor using a single borehole. By applying hydraulic pressure to the coal mine roof during the working face mining process, the high stress in the coal mine roof is effectively released. Furthermore, by performing advanced exploration and treatment of the coal mine floor, the lime-aquifer is modified by grouting, allowing the grout to spread evenly, forming an effective barrier and sealing the cracks. This fills and reinforces the cracks and water-conducting channels, thereby modifying the lime-aquifer in the No. 6 coal seam floor, increasing the effective thickness of the water-resistant layer, and blocking the water-aquifer channels.

[0021] Compared to traditional methods of underground fracturing and surface grouting, this invention significantly improves construction efficiency and reduces the risks of underground construction. Its technology has a wide range of applications, suitable for coal seam treatment in mines, and has high application value. Attached Figure Description

[0022] Figure 1 A schematic plan view of the coal mine roof and floor treatment according to the present invention;

[0023] Figure 2 A cross-sectional schematic diagram of the coal mine roof and floor treatment method of the present invention. Detailed Implementation

[0024] This embodiment of a method for coordinated management of multiple hazards in the roof and floor of a coal mine includes the following steps:

[0025] I. Geological Parameter Investigation and Analysis

[0026] 1.1. Collect hydrogeological information on the roof and floor of the coal mine that need to be treated, including the tectonic development of the area to be treated, the bedding structure of the coal seam roof and floor, and the thickness of the limestone aquifer.

[0027] 1.2. The hydrogeological characteristics of the coal mine roof and floor were analyzed. The fracturing layer was determined in the coal mine roof, and hydraulic fracturing was carried out by drilling along the stable sandstone layer. In the coal mine floor, the lime-fly ash aquifer was selected as the target layer for grouting treatment, and grouting treatment was carried out along the lime-fly ash target layer in the coal mine floor.

[0028] II. Drilling Layout and Positioning

[0029] 2.1. Considering the dip and dip angle of the underground coal seam, the direction of the horizontal holes in the coal mine roof and the coal mine floor should be kept as parallel as possible to the dip of the strata to reduce the difficulty of drilling. The drilling should be arranged according to the diffusion law of the grouting slurry.

[0030] III. Coal Mine Roof Fracturing Construction

[0031] 3.1 Using a directional drilling rig, drilling is performed from the ground toward the coal mine roof. After passing through the straight section and the directional drilling section, the drilling tool enters the coal mine roof. After passing through the directional drilling section, the drilling tool drills along the center of the coal mine roof and drills along the layers of the coal mine roof to form a horizontal section. During the drilling process, casing is lowered into the borehole.

[0032] The drilling employed a three-stage borehole diameter system, each paired with a three-stage casing. The first-stage borehole had a diameter of 444.5 mm, with a casing of 339.7 mm running down to a depth of 5–10 m within the bedrock. The second-stage borehole had a diameter of 311.1 mm, with a casing of 244.5 mm running down to a stable sandstone stratum above the coal seam. The third-stage borehole had a diameter of 215.9 mm, and after reaching the final borehole depth, a casing of 139.7 mm was run down.

[0033] 3.2. After the casing in the horizontal section is lowered, a combination of hydraulic blasting perforation and bottom-sealed fracturing is employed. Hydraulic blasting perforation involves supplying high-pressure water through a continuous tubing system to the perforation device, achieving high-speed jet cutting and creating holes in the casing. This allows the high-pressure water to act on the formation, fracturing the coal mine roof and releasing stress. This process is repeated sequentially to achieve segmented fracturing of the horizontal section. Both the hydraulic blasting perforation equipment and the bottom-sealed fracturing equipment are existing technologies.

[0034] When carrying out segmented fracturing construction, the interval between each segment is 50m. Each segment of hydraulic sandblasting perforation includes two sets of holes with a spacing of 20-27m between sets. It is necessary to avoid the casing coupling. Each set of holes includes three holes. In the horizontal segment, 40 sets of fractures are initially formed to cut the formation to the maximum extent and effectively release high stress.

[0035] IV. Sleeve Cutting and Removal Construction

[0036] 4.1 After the coal mine roof fracturing construction is completed, before constructing the coal mine floor grouting treatment hole, the trajectory needs to be re-optimized to construct the second opening using the same straight hole section. Therefore, two inclined sections need to be constructed, and one pipe cutting and pulling operation is required. Successfully completing the pipe cutting and pulling operation is the basis for the next step of the coal mine floor horizontal branch hole construction procedure.

[0037] 4.2. Use a mechanical internal cutter to cut the pipe. A mechanical internal cutter is a special tool for cutting pipe from the inside of the downhole tubing string. It can cut at any point except for couplings. During the cutting operation, a retractable retrieval spear can be attached to the upper part of the internal cutter. After the cutting is completed, the upper part of the tubing string can be pulled out in one go.

[0038] V. Construction of Coal Mine Floor Grouting Treatment

[0039] 5.1 After the casing is cut and pulled out, the trajectory is re-optimized for the construction of the directional drilling section, so that the borehole passes through the main coal seam of No. 6 coal seam and enters the lime-aquifer. The borehole is drilled along the lime-aquifer to form a horizontal bare hole section. After the main hole is completed, the construction of the horizontal branch hole begins. During the drilling process, the casing is re-inserted into the straight hole section and the directional drilling section. When drilling into the aquifer in the coal mine floor, the first-stage opening shares a straight hole section with step B; the second-stage opening has a diameter of 215.9 mm, and a casing with a diameter of 177.8 × 8.05 mm is inserted down to the mudstone above the aquifer; the third-stage opening is a bare hole drilled in the aquifer with a diameter of 152.4 mm.

[0040] 5.2. After the drilling tool passes through the directional drilling section, it drills along one side of the coal mine floor to form the first borehole. Then, it drills the nth borehole parallel to the direction of the first borehole in sequence to the other side of the coal mine floor. After each borehole is completed, grouting equipment is used to inject grout into the aquifer to fill and reinforce the cracks and water channels, increase the effective thickness of the aquifer, and block the aquifer channels.

[0041] This invention targets isolated working faces or working faces with stress concentration. It achieves effective treatment of isolated working faces by separately applying hydraulic pressure to the coal mine roof and conducting advanced exploration and treatment of the coal mine floor using a multi-purpose single-hole technique. Furthermore, through optimization of the construction sequence and process, by releasing the stress in the coal mine roof before grouting, the stress in the roof is already released and will not be affected by the grouting, thus preventing stress concentration or uneven stress distribution. This ensures the safety of the coal mine and the entire construction process, greatly improving construction safety. The method is simple, effective, and highly operable, effectively enhancing the water hazard prevention capabilities of mine engineering.

[0042] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of the claims of this patent application.

Claims

1. A coal mine roof and floor multi-disaster collaborative management method, characterized in that, The method comprises the following steps: Step A: collect hydrogeological information of coal mine roof and coal mine floor needing treatment, and design drilling arrangement position; Step B: use the directional drilling machine to drill from the ground to the direction of the coal mine roof, after passing through the straight hole section and the build-up section, the drilling tool enters into the coal mine roof and drills along the coal mine roof to form a horizontal section, and a casing is lowered into the drilling hole during the drilling construction; the drilling tool drills along the central position of the coal mine roof after passing through the build-up section; Step C: after the casing in the horizontal section is lowered, a combination of hydraulic sand jet perforation and bottom seal drag fracturing is used to perforate holes on the casing, so that high-pressure water acts on the stratum to perform fracturing construction on the coal mine roof, realize cutting stratum and releasing stress, and the construction is repeated in sequence to realize segmented fracturing construction of the horizontal section; the interval of each segment is 50 m; the hydraulic sand jet perforation of each segment includes two groups of holes, and the interval of the groups is 20-27 m, and each group of holes includes three holes; Step D: after the fracturing construction is completed, the casing is cut at a suitable position by using a pipe cutting machine, and the upper casing is pulled out; Step E: on the basis of the original drilling hole, the drilling trajectory is optimized, and the directional drilling machine is used for secondary drilling construction to re-construct the build-up section, so that the drilling tool penetrates through the coal seam and enters into the aquifer in the coal mine floor, and a horizontal open hole section is formed by drilling along the aquifer; during the drilling construction, the casing is lowered into the straight hole section and the build-up section; the drilling tool drills along one side of the coal mine floor to form a first drilling hole, and then a nth drilling hole parallel to the first drilling hole is drilled in the direction of the other side of the coal mine floor, and grouting construction is performed after the construction of each drilling hole is completed; Step F: use the grouting equipment to grout into the aquifer to fill and reinforce the fissures and water-conducting channels, increase the effective thickness of the aquiclude and block the aquifer channel.

2. The coal mine roof and floor multi-disaster collaborative management method according to claim 1, characterized in that, In step B, during drilling in the direction of the coal mine roof, the drilling hole adopts three levels of hole diameters, respectively matched with three levels of casings.

3. The coal mine roof multi-disaster collaborative management method according to claim 2, characterized in that, The first opening hole diameter is 444.5 mm, a casing with a diameter of 339.7 mm is lowered into the stratum, and the depth is 5-10 m; the second opening hole diameter is 311.1 mm, a casing with a diameter of 244.5 mm is lowered into the stratum, and the depth is the upper stable sandstone layer of the coal seam; the third opening hole diameter is 215.9 mm, and a casing with a diameter of 139.7 mm is lowered into the stratum after drilling to the final hole depth.

4. The coal mine roof and floor multi-disaster collaborative management method according to claim 3, characterized in that, In step E, when drilling into the aquifer in the coal mine floor, the first opening hole shares a straight hole section with step B; the second opening hole diameter is 215.9 mm, a casing with a diameter of 177.8*8.05 mm is lowered into the stratum, and the depth is the upper mudstone of the aquifer; the third opening hole is a bare hole drilled in the aquifer, and the hole diameter is 152.4 mm.

5. The coal mine roof multi-disaster collaborative management method according to claim 1, characterized in that, In step B, the drilling tool drills along the stratum in the stable sandstone in the coal mine roof; in step E, the drilling tool drills along the stratum in the three-lime aquifer.

6. The coal mine roof multi-disaster collaborative management method according to claim 1, characterized in that, When drilling in the coal mine roof and the coal mine floor, the horizontal drilling direction is parallel to the stratum inclination.

Images