A staggered floor coal pillar-free multi-mined-out area gas combined extraction arrangement method

Abstract

The application discloses a kind of mislayer position no coal pillar multiple goaf combined gas extraction layout method, belong to coal mining field.This method aims at solving the problem that gas is difficult to realize unified efficient extraction between adjacent multiple goafs of coal pillar working face.By using mislayer position no coal pillar roadway layout mode, the efficient combined extraction of multiple adjacent working face goaf gas is realized.In particular, before coal seam mining, using ground drilling, bedding parallel drainage borehole, through layer borehole and other methods for pre-mining gas pre-extraction;During working face mining, using bedding parallel drainage borehole, high position fissure borehole and other measures to carry out combined extraction on pressure relief gas of adjacent multiple goafs, so as to realize sustainable management of multiple working face and goaf gas.The layout method can comprehensively and comprehensively manage the gas problem of multiple goafs.Compared with the coal and gas co-mining technology of coal pillar roadway layout, it has more obvious advantages in safety, economy and other aspects.

Description

Technical Field

[0001] This invention relates to the field of coal mining, and in particular to a method for arranging gas extraction in multi-goaf areas without coal pillars in staggered strata. Background Technology

[0002] Currently, research on coal and gas co-mining is mainly based on the traditional roadway layout with coal pillars, where the intake and return airways of the working face are located at the same level of the coal seam. Although this layout has achieved some results in coal and gas co-mining, it is difficult to achieve effective gas control relying solely on gas extraction technology. Furthermore, it cannot organically combine multiple adjacent working face goafs to jointly deploy a coal and gas co-mining system. In contrast, the staggered roadway layout places the intake and return airways at different levels of the coal seam. No protective coal pillars are needed between adjacent working faces. The overlying strata movement of multiple adjacent working faces exhibits a similar pattern to that of a single, ultra-long working face, with interconnected fractures developing between goafs. Large, interconnected "O"-shaped fracture zones will form within the overlying strata of multiple adjacent goafs. Therefore, the fracture zones in the overlying strata of two adjacent goafs will inevitably connect, enabling the mutual flow of fluids within the overlying fracture zones.

[0003] In summary, by utilizing the staggered-bed, pillarless roadway layout, the three-dimensional structure of the roadway facilitates the advantages of gas extraction technology and the interconnectedness of multiple adjacent goaf areas. Therefore, it is possible to consider using its unique overburden movement characteristics to unite multiple adjacent working faces into a unified whole to arrange a coal and gas co-mining system, realizing joint gas extraction from goaf areas of multiple adjacent working faces. This provides a new approach to coal and gas co-mining systems, and the unique staggered-bed roadway layout can improve the recovery rate and facilitate the advantages of gas extraction technology. Summary of the Invention

[0004] To address the problem of insufficient gas drainage systems in goaf areas with coal pillars, the present invention proposes a staggered, pillarless, multi-goaf combined gas drainage layout method to solve the problems of traditional roadway layouts failing to organically combine goaf areas of multiple adjacent working faces, making it difficult to effectively manage gas in adjacent goaf areas.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for arranging gas drainage in staggered, pillarless, multi-goaf areas includes the following processes:

[0007] a. Based on the characteristics of overburden development in the first mining of the staggered strata and the subsequent working faces with no coal pillars and multiple goaf areas, determine the height of roof and floor fracture development after mining, analyze the gas enrichment range, and clarify the gas drainage measures.

[0008] b. A number of surface wells are arranged along the strike direction of the working face for the first mining and subsequent working face of the staggered layer. Gas extraction pipelines are installed in the wells, and the end of the well is located in the fracture zone of the goaf, so as to realize the pre-extraction of coal seam gas before mining and the continuous extraction of depressurized gas from multiple goaf areas after mining.

[0009] c. Lay a gas extraction pipeline in the return air side roadway of the staggered working face. The gas pipeline is pre-buried into the depth of the goaf using an alternating stepping method. During the working face mining process, gas is extracted from the goaf and the upper corner.

[0010] d. Parallel drainage boreholes are arranged along the seam in the intake and return airways of the first mining face at the staggered layer position, and parallel drainage boreholes are arranged along the seam in the return airway of the first mining face along the side of the next mining face. At the same time, the intake airway of the next mining face adopts the above-mentioned arrangement of parallel drainage boreholes, and parallel drainage boreholes are arranged along the seam in the direction of the next mining face, forming a three-dimensional gas extraction structure. This can achieve pre-extraction of coal seam gas before mining the first mining face and the next mining face, while further weakening the top coal and ultimately achieving the goal of gas extraction in multiple goaf areas.

[0011] e. Several drilling sites are set up on the side of the return air roadway of the first mining face and the subsequent mining face. The drilling sites are arranged with high-level fracture boreholes into the fracture zone of the goaf. When the working face advances to the vicinity of the extraction borehole, the depressurized gas in the goaf is extracted.

[0012] f. Based on the overburden development characteristics of the multi-goaf area without coal pillars in the staggered strata, a high-speed extraction roadway along the strike is set on the return air side of the continuous working face to realize the extraction of depressurized gas from adjacent multi-goaf areas.

[0013] g. A bottom drainage roadway is set up in the underlying rock strata of the first mining face and the subsequent mining face, and cross-strata boreholes are arranged in a fan shape from the bottom drainage roadway to the mining face to realize the pre-drainage of coal seam gas before mining and the drainage of depressurized gas in adjacent goaf areas after mining.

[0014] The method according to the present invention, preferably, is applicable to the method.

[0015] Specifically, in step a, based on the layout characteristics of the staggered roadway, the overlying rock of the successive working face and the overlying rock of the first mining working face collapse, forming a common collapse of the overall overlying rock structure. The fracture zones of the overlying rock strata of the adjacent goaf areas are interconnected, forming a structure similar to a large "O" shaped ring. The morphology and location of the gas enrichment zone in the goaf areas are analyzed, and joint gas extraction measures for the goaf areas without coal pillars are determined.

[0016] In step b, based on the large "O"-shaped fracture structure of the multi-goaf area without coal pillars in the staggered strata, the location and number of surface wells are determined, so that the surface wells are located within the large "O"-shaped fracture zone. Gas drainage pipelines are installed in the wells, and the borehole ends are located within the fracture zone of the goaf area. The interval between the surface wells is at least 100m. The negative pressure of gas drainage is adjusted according to factors such as the working face advance distance and gas drainage concentration, so as to realize pre-drainage of coal seam gas before mining and continuous drainage of depressurized gas in multi-goaf areas after mining.

[0017] In step c, the gas drainage pipeline is laid in the return air side roadway of the first mining face and the subsequent mining face in the staggered layer. The gas pipeline is pre-buried in the depth of the goaf using an alternating stepping method. The pre-buried gas drainage pipeline penetrates into the goaf to extract gas at a depth of about 30-45m. The extraction port of the pre-buried pipeline is protected by wooden stacks to ensure that the extraction port is in a reliable state and can continuously extract gas from the upper corner of the working face and the goaf.

[0018] In step d, parallel drainage boreholes are constructed and arranged along the seam on one side of the intake and return airways of the first mining face in the staggered layer. The boreholes are arranged in groups of three, with opening heights of 1.4m, 1.9m, and 2.5m from the bottom of the roadway, respectively. The opening orientation is 90° to the coal wall, the designed depth of the boreholes is 160m, the spacing between the boreholes is 1m, the diameter is 325mm, and the interval between each group of boreholes is 150m. Parallel drainage boreholes along the seam are arranged along the side of the subsequent mining face in the return airway of the first mining face. At the same time, the intake airway of the subsequent mining face adopts the above-mentioned arrangement of parallel drainage boreholes along the seam, and parallel drainage boreholes along the seam are arranged towards the side of the subsequent mining face, forming a three-dimensional gas extraction structure. This can realize the pre-extraction of gas from the coal seam before mining in the first mining face and the subsequent mining face, while further weakening the top coal and ultimately achieving the goal of gas extraction from multiple goaf areas.

[0019] In step e, four drilling sites are set up for the first mining face and the subsequent mining face. Each drilling site is equipped with six high-level fracture boreholes. The boreholes are located 7-8m above the coal seam roof, with a depth of 500m and a diameter of 203mm. As the working face advances, the pre-arranged high-level fracture boreholes are sequentially drilled into the fracture zone of the goaf to extract the depressurized gas from the goaf.

[0020] In step f, on the return air side of the continuing working face, based on the overburden development characteristics of interconnected multi-goaf areas without coal pillars in the staggered position, the high-speed extraction roadway is set in the upper part of the overburden fracture zone of the continuing working face, that is, within the large "O"-shaped gas enrichment zone, to continuously extract depressurized gas from adjacent multi-goaf areas.

[0021] In step g, a bottom drainage roadway is excavated in the underlying rock strata of the first mining face and the subsequent mining face. The bottom drainage roadway is arranged with cross-strata boreholes distributed in a fan shape towards the working face to realize pre-drainage of coal seam gas before mining and gas drainage from multiple goaf areas.

[0022] Compared with existing technologies, the gas extraction layout method for multiple goaf areas without coal pillars in staggered layers provided by this invention has the following advantages:

[0023] (1) High coal extraction rate. The staggered, pillarless roadway layout eliminates the need for protective coal pillars, reduces coal loss in the mining area, and can significantly improve the top coal release rate, thereby maximizing the recovery of coal resources;

[0024] (2) High borehole utilization rate. The return airway of the staggered working face is arranged along the top of the coal seam, and parallel extraction boreholes are arranged on both sides of the roadway. It can pre-extract gas for the working face and the next working face, and can also be used as pre-splitting boreholes to pre-split and weaken the top coal of the working face and the next working face, thereby increasing the top coal release rate and maximizing the utilization value of the boreholes;

[0025] (3) Achieve sustainable gas management in working faces. Various types of gas drainage boreholes are used to carry out comprehensive drainage of coal seams and adjacent goaf areas in different ways. Different types of boreholes are used reasonably according to the mining stage to ensure continuous and efficient drainage throughout the entire period, and to achieve full-process drainage of gas in goaf areas. Through the comprehensive application and coordination of various drainage methods such as surface boreholes, in-seam parallel drainage boreholes, and cross-seam boreholes, the technical advantages of each method are brought into play, and they support each other to achieve sustainable management of gas in goaf areas. Attached Figure Description

[0026] Figure 1 This is a three-dimensional schematic diagram of the gas extraction layout mode of the multi-goaf area without coal pillars in the staggered layer of the present invention;

[0027] Figure 2 This is a schematic diagram of the surface borehole layout for the multi-goaf area without coal pillars in the staggered strata of the present invention.

[0028] Figure 3 This is a schematic diagram of the surface borehole profile of the multi-goaf area without coal pillars in the staggered strata of the present invention.

[0029] Figure 4 This is a schematic diagram of the planar layout of parallel extraction boreholes in the goaf of the present invention, which is located in a staggered layer without coal pillars.

[0030] Figure 5 This is a schematic diagram of the cross-section of the parallel extraction borehole in the goaf of the present invention, which is located in a staggered layer without coal pillars.

[0031] Figure 6 This is a schematic diagram of the arrangement of parallel extraction boreholes along the bedding plane in the multi-goaf area of ​​the present invention, which is a staggered-layer, pillarless, multi-goaf area.

[0032] Figure 7 This is a schematic diagram of the layout of high-level fracture boreholes in the multi-goaf area without coal pillars in the staggered strata of the present invention.

[0033] Figure 8This is a schematic diagram of the layout of the high-extraction roadway in the multi-goaf area without coal pillars in the staggered layer position according to the present invention.

[0034] Figure 9 This is a schematic diagram of the buried pipe layout in the multi-goaf area without coal pillars in the staggered layer of the present invention.

[0035] Figure 10 This is a schematic diagram of the layout of cross-layer boreholes in the bottom drainage roadway of the multi-goaf area in the staggered layer without coal pillars according to the present invention.

[0036] The attached diagram is labeled as follows: 1. Intake airway of the first mining face; 2. Return airway of the first mining face; 3. Intake airway of the subsequent mining face; 4. Return airway of the subsequent mining face; 5. First mining face; 6. Subsequent mining face; 7. Surface drilling; 8. Parallel drainage borehole along the bedding plane; 9. Goaf buried pipe; 10. High-level drainage roadway along the strike; 11. High-level fracture borehole; 12. Bottom drainage roadway; 13. Cross-bedding borehole. Detailed Implementation

[0037] Specific embodiments of the present invention will be described with reference to the accompanying drawings.

[0038] In this embodiment, the first step is to analyze the overburden of the connecting working face and the first mining working face, which collapse to form a common overburden structure. The fracture zones of the overburden strata in the adjacent goaf areas are interconnected, forming a structure similar to a large "O" shaped ring. The morphology and location of the gas enrichment zone in the goaf areas are analyzed to determine the combined gas drainage measures for the goaf areas without coal pillars. Among the combined gas drainage measures for the goaf areas, surface drilling 7 can be used for pre-drainage of gas before mining and continuous gas drainage during mining. The gas extraction stage and post-mining enhanced extraction; parallel extraction borehole 8 along the seam pre-fractures the top coal, pre-extraction of gas before mining and continuous gas extraction during mining; high-level fracture borehole 11 is applicable to pre-extraction of gas before mining and continuous gas extraction during mining; buried pipe 9 is applicable to continuous gas extraction during mining; high extraction roadway 10 is applicable to continuous gas extraction during mining; bottom extraction roadway 12 and the arranged cross-layer borehole 12 are applicable to pre-extraction of gas before mining, continuous gas extraction during mining and post-mining enhanced extraction.

[0039] The second step involves determining the location and number of surface wells 7 based on the large "O"-shaped fracture structure of the multi-goaf area without coal pillars in the staggered strata, ensuring that the surface wells 7 are located within the large "O"-shaped fracture zone. Gas extraction pipelines are installed in the wells, with the borehole ends located within the goaf fracture zone area. The surface wells 7 are spaced at least 100m apart. The negative pressure of gas extraction is adjusted according to factors such as the working face advance distance and gas extraction concentration to achieve pre-extraction of coal seam gas before mining and continuous extraction of depressurized gas from multi-goaf areas after mining.

[0040] The third step is to lay the gas drainage pipeline at the location of the return air side roadways 2 and 4 of the first mining face 5 and the subsequent working face 6 in the staggered layer. The gas drainage pipeline 9 is pre-buried in the depth of the goaf using an alternating stepping method. The pre-buried gas drainage pipeline 9 penetrates into the goaf about 30-45m deep to extract gas. The extraction pipe opening of the pre-buried pipeline is protected by wooden stacks to ensure that the extraction pipe opening is in a reliable state to continuously extract gas from the upper corner of the working face and the goaf.

[0041] The fourth step involves constructing and arranging parallel drainage boreholes 8 along the seam on one side of the first mining face's intake airway 1 and return airway 2. These boreholes are grouped in sets of three, with opening heights of 1.4m, 1.9m, and 2.5m from the roadway floor, respectively. The opening orientation is 90° to the coal wall, with a designed depth of 160m, a spacing of 1m between holes, and a diameter of 325mm. Each group of boreholes is spaced 150m apart. Parallel drainage boreholes 8 along the seam are also arranged along the side of the next mining face in the return airway 2 of the first mining face. Simultaneously, the intake airway 3 of the next mining face adopts the aforementioned arrangement of parallel drainage boreholes 8, forming a three-dimensional gas extraction structure. This allows for pre-extraction of gas from the coal seam before mining the first mining face 5 and the next mining face 6, while further weakening the top coal and ultimately achieving the goal of gas extraction from multiple goaf areas.

[0042] In the fifth step, four drilling sites are set up in the first mining face 5 and the subsequent mining face 6. The drilling sites are equipped with six high-level fracture boreholes 11. The boreholes are located 7-8m above the coal seam roof, with a depth of 500m and a diameter of 203mm. As the working face advances, the pre-arranged high-level fracture boreholes 11 are sequentially drilled into the fracture zone of the goaf to extract the depressurized gas from the goaf.

[0043] The sixth step is to set up the high-expansion roadway 10 on the return air side 4 of the continuing working face, based on the characteristics of the interconnected overburden development of the multi-goaf areas without coal pillars in the staggered position. The high-expansion roadway 10 is set in the upper part of the overburden fracture zone of the continuing working face, that is, within the gas enrichment zone of the large "O"-shaped ring, and continuously extract the depressurized gas from the adjacent multi-goaf areas.

[0044] Step 7: In the underlying rock strata of the first mining face 5 and the subsequent mining face 6, a bottom drainage roadway 1 is excavated. In the bottom drainage roadway, cross-strata boreholes 13 are arranged in a fan shape towards the working face to realize pre-drainage of coal seam gas before mining and gas drainage for depressurization in multiple goaf areas.

Claims

1. A method for arranging gas extraction in staggered, pillarless, multi-goaf areas, characterized in that, The process includes the following: a. Based on the overlying strata development characteristics of the first mining in the staggered strata and the pillarless goaf areas of the subsequent working faces, it is necessary to determine the height of roof and floor fractures after mining, analyze the range of gas enrichment, and clarify the gas drainage measures; b. A number of surface wells are arranged along the strike direction of the working face for the first mining and subsequent working face of the staggered layer. Gas drainage pipelines are installed in the wells, and the end of the well is located in the fracture zone of the goaf, so as to realize the pre-drainage of coal seam gas before mining and the continuous drainage of depressurized gas in adjacent goaf areas after mining. c. When laying gas extraction pipelines in the return air side roadway of the first mining face in the staggered layer, the gas extraction pipelines are pre-buried into the depth of the goaf using an alternating stepping method. During the mining process of the working face, gas in the goaf and the upper corner is extracted at the same time. d. In the intake and return airways of the first mining face at the staggered strata, parallel drainage boreholes are arranged along the strata to one side of the mining face. In the return airway of the first mining face, parallel drainage boreholes are arranged along the side of the next mining face. At the same time, the intake airway of the next mining face adopts the aforementioned arrangement of parallel drainage boreholes along the strata to one side of the next mining face, forming a three-dimensional gas extraction structure. This can achieve pre-drainage of coal seam gas before mining in the first mining face and the next mining face, further weaken the top coal and extract gas from adjacent goaf areas, ultimately achieving pre-drainage of coal seam gas before mining, improving the top coal venting ability during mining and extracting gas from adjacent goaf areas after mining, thus achieving the goal of "one borehole for multiple uses". e. Several drilling sites are set up on the side of the return air roadway of the first mining face and the subsequent mining face. The drilling sites are arranged with high-level fracture boreholes into the fracture zone of the goaf. When the working face advances to the vicinity of the extraction borehole, the depressurized gas in the goaf is extracted. f. Based on the characteristics of overburden development in the multi-goaf area without coal pillars in the staggered strata, a high-speed extraction roadway along the strike is set on the return air side of the continuous working face to realize the extraction of depressurized gas in the adjacent multi-goaf area. g. Set up bottom drainage roadways in the underlying rock strata of the first mining face and the subsequent mining face, and arrange cross-strata boreholes in a fan shape from the bottom drainage roadways toward the working face to realize the pre-drainage of coal seam gas before mining and the drainage of depressurized gas in adjacent goaf areas after mining.

2. The method for combined gas extraction in staggered, pillarless, multi-goaf areas according to claim 1, characterized in that, In step a, based on the staggered roadway layout characteristics, the overlying rock of the successive working face and the overlying rock of the first mining working face collapse, forming a common collapse of the overall overlying rock structure. The fracture zones of the overlying rock strata of the adjacent goaf areas are interconnected, forming a large "O"-shaped fracture structure. By analyzing the morphology and location of the gas enrichment zone in the goaf areas, joint gas extraction measures for adjacent goaf areas without coal pillars are determined.

3. The method for joint gas extraction in staggered, pillarless, multi-goaf areas according to claim 1, characterized in that, In step b, the location and number of surface wells are determined based on the large "O"-shaped fracture structure of the multi-goaf area without coal pillars in the staggered strata, so that the surface wells are located within the large "O"-shaped fracture zone. Gas drainage pipelines are installed in the wells, and the borehole ends are located within the fracture zone of the goaf area. The interval between the surface wells is at least 100m. The negative pressure of gas drainage is adjusted according to factors such as the working face advance distance and gas drainage concentration, so as to achieve pre-drainage of coal seam gas before mining and continuous drainage of depressurized gas in adjacent multi-goaf areas after mining.

4. The method for joint gas extraction layout in staggered, pillarless, multi-goaf areas according to claim 1, characterized in that, In step c, gas extraction pipelines are laid at the return air side roadway of the first mining face and the subsequent mining face in the staggered layer. The gas pipelines are pre-buried in the depth of the goaf using an alternating stepping method. The pre-buried gas extraction pipelines penetrate 30-45m into the goaf for gas extraction. At the same time, in order to protect the extraction pipe opening of the pre-buried pipeline, wooden stacks can be used for protection to ensure that the extraction pipe opening is in a reliable state and to continuously extract gas from the upper corner of the working face and the goaf.

5. The method for joint gas extraction in staggered, pillarless, multi-goaf areas according to claim 1, characterized in that, In step d, parallel extraction boreholes are constructed and arranged along the bedding plane on one side of the intake and return airway of the first mining face at the staggered location. The boreholes are grouped in sets of three, with opening heights of 1.4m, 1.9m, and 2.5m from the roadway floor, respectively. The opening orientation is at a 90° angle to the coal wall, the designed borehole depth is 160m, the borehole spacing is 1m, and the diameter is 325mm. Each group of boreholes is spaced 150m apart. Parallel extraction boreholes are also arranged along the side of the connecting working face in the return airway of the first mining face, simultaneously connecting... The same in-seam parallel drainage borehole arrangement is used in the intake airway of the continuing working face. In-seam parallel drainage boreholes are arranged on the side of the continuing working face to form a three-dimensional gas drainage structure. This can realize the pre-drainage of coal seam gas before mining in the first mining face and the continuing working face, further weaken the top coal and drain the gas from the adjacent goaf, and finally achieve the goal of pre-drainage of coal seam gas before mining, improving the top coal venting ability during mining and draining the gas from the adjacent goaf after mining, thus achieving the goal of "one borehole for multiple uses".

6. The method for joint gas extraction layout in staggered, pillarless, multi-goaf areas according to claim 1, characterized in that, In step e, four drilling sites will be set up in the first mining face and the subsequent mining face, and six high-level fracture boreholes will be arranged in each drilling site. The boreholes are located at 7-8m above the coal seam roof, with a depth of 500m and a diameter of 203mm. As the working face advances, the pre-arranged high-level fracture boreholes will gradually penetrate into the fracture zone of the goaf to realize the extraction of depressurized gas in the goaf of this working face.

7. The method for joint gas extraction in staggered, pillarless, multi-goaf areas according to claim 1, characterized in that, In step f, on the return air side of the continuing working face, based on the overburden development characteristics of interconnected multi-goaf areas without coal pillars in the staggered position, the high-speed extraction roadway is set in the upper part of the overburden fracture zone of the continuing working face, that is, within the range of the large "O"-shaped gas enrichment zone, so as to realize the continuous extraction of depressurized gas from adjacent multi-goaf areas.

8. The method for joint gas extraction layout in staggered, pillarless, multi-goaf areas according to claim 1, characterized in that, In step g, a bottom drainage roadway is excavated in the underlying rock strata of the first mining face and the subsequent mining face. The bottom drainage roadway is arranged with cross-strata boreholes distributed in a fan shape towards the working face to realize pre-drainage of coal seam gas before mining and continuous drainage of depressurized gas in adjacent goaf areas after mining.

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