Method for highly efficient gas control in large areas of medium-hard coal seams throughout the whole space and time

Abstract

The present invention relates to a method for highly efficient gas control in a large area of medium-hard coal seams throughout the whole time and space, belonging to the field of coal mine gas control. The method includes the following steps: Step S1, arranging a number of long directional boreholes along the coal seam inside the coal seam; Step S2, arranging a number of high-level directional branch long boreholes at the roof of the coal seam; Step S3, connecting to the gas drainage pipeline for gas drainage. This method realizes the highly efficient control of gas hazards in a large area, ahead of time, throughout the whole time and space from the source by developing the up and down mountain roadways. By means of hydraulic fracturing long directional boreholes, ordinary long directional boreholes, high-level directional branch long boreholes, etc., it can achieve the highly efficient control of gas in the whole time and space in the coal roadway, fracture zone, upper corner, coal face, adjacent seam, goaf during the mining process of medium-hard coal seams, solves the technical problems of the existing gas control methods that cannot be controlled ahead of time in terms of time, cannot cover the whole area in terms of space, and cannot achieve large-area ahead and highly efficient control in terms of efficiency, and reduces the engineering quantity and cost of gas control.

Description

Technical Field

[0001] The present invention belongs to the field of coal mine gas control, and particularly relates to a method for efficiently controlling gas in a large area and throughout the whole time and space in medium-hard coal seams. Background Art

[0002] Gas disasters seriously affect the safe production of coal mines. To achieve safe coal mining in the working face of outburst-prone coal seams, it is necessary to essentially achieve the extraction standard of mining and excavation and the control of gas emission. Further speaking, it is necessary to achieve efficient extraction of gas in the time and space of the mining and excavation working faces.

[0003] In the existing gas control methods, the gas in the coal roadway strip and the mining area can be controlled respectively according to the sequence of mining and excavation time. In terms of time, this method cannot achieve advanced gas control.

[0004] In the existing gas control methods, the gas in the upper corner, the roof mining-induced fracture zone and the goaf of the mining face can be controlled respectively according to the gas source. In terms of space, this method fails to achieve full-time and full-space gas control during the mining and excavation process.

[0005] In the existing gas control methods, cross-layer or along-layer boreholes can be constructed in the mining and excavation roadways to extract gas for gas control. However, the gas control area of this method is small and cannot achieve large-area advanced extraction, resulting in tension or imbalance in the mining and excavation succession of coal mines, and the efficiency is low in terms of gas control efficiency. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a method for efficiently controlling gas in a large area and throughout the whole time and space for medium-hard coal seams to solve the problems existing in the existing gas control process.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A method for efficiently controlling gas in a large area and throughout the whole time and space in medium-hard coal seams, comprising the following steps: S1, arranging a number of long directional boreholes along the seam inside the coal seam; S2, arranging a number of high-position directional branched long boreholes at the roof of the coal seam; S3, connecting to a gas extraction pipeline for gas extraction;

[0009] In step S1, the long directional boreholes along the seam inside the coal seam are divided into hydraulic fracturing directional long boreholes 5 and ordinary directional long boreholes 12. Among them, each ordinary directional long borehole 12 is arranged in the middle between two adjacent hydraulic fracturing directional long boreholes 5 to enhance gas extraction, and each hydraulic fracturing directional long borehole 5 is subjected to segmented hydraulic fracturing;

[0010] In step S2, the high-position directional branched long boreholes at the roof include a main hole 6 and branched holes communicating with the main hole;

[0011] The optimal construction position of the main hole 6 in the dip direction of the coal seam is bounded by the lower coal wall near the mining side of the return airway 3 of the mining face, and the optimal construction position is at an interval of L1. The calculation formula for L1 is as follows:

[0012] L1 = [Y / 3 - h / tan(α + β)] ÷ 2;

[0013] In the formula: α is the dip angle of the coal seam, in °; β is the pressure-relief angle of the overlying strata of the roof, in °; Y is the width of the cutting hole of the mining face, in m; h is the vertical distance between the directional long hydraulic fracturing borehole 5 and the coal seam roof, in m;

[0014] The branch hole includes a branch hole 7 on the gateway side and a branch hole 8 on the mining side; among them, the horizontal projection length Y3 construction range of the branch hole 7 on the gateway side in the dip direction of the coal seam needs to cover the return airway 3 of the mining face and the gas drainage zone of the return airway of the mining face. The calculation formula is as follows:

[0015] Y3 ≥ L1 + W + Y p ;

[0016] In the formula: L1 is the optimal construction position of the main hole in the dip direction of the coal seam, in m; W is the width of the return airway of the mining face, in m; Y p is the width of the gas drainage zone of the return airway of the mining face, in m;

[0017] The horizontal projection length Y2 of the branch hole 8 on the mining side in the dip direction of the coal seam needs to exceed the re-compacted area of the goaf and be not less than 1 / 3 of the width Y of the cutting hole of the mining face, that is, Y2 ≥ Y / 3.

[0018] Furthermore, in step S2, the optimal construction horizon of the main hole 6 in the vertical direction is arranged at the topmost part of the roof fracture zone, that is, the junction of the roof bending zone and the fracture zone.

[0019] Furthermore, in step S2, the length of the main hole 6 in the strike direction of the coal seam is greater than the length X of the mining face and exceeds 20 m.

[0020] Furthermore, in step S2, in the dip direction of the coal seam, the construction positions of the main holes 6 corresponding to each mining face are all designed according to the optimal construction position L1.

[0021] Furthermore, in step S2, the opening spacing of the branch hole 7 on the gateway side and the branch hole 8 on the mining side in the strike direction of the coal seam is the same as the spacing X1 of the sectional hydraulic fracturing, and the coal hole sections of each branch hole 7 on the gateway side and the coal hole sections of the branch hole 8 on the mining side are distributed in the middle area between two adjacent sectional hydraulic fracturing intervals.

[0022] Furthermore, in step S2, during the construction of each coal roadway side branch hole 7 and the mining side branch hole 8, a hole protection screen pipe is installed throughout each branch hole.

[0023] Furthermore, in step S3, during the driving of the coal roadway, the high-level directional branched long borehole in the roof continues to cover the regional gas. At the same time, the hole protection screen pipe of the coal roadway strip branch hole exposed in the coal roadway is replaced with a drainage pipe, and a tee is installed to lead out a pipeline and bury it in the goaf to drain the gas in the goaf during the mining of the working face and the gas gushing from adjacent seams.

[0024] The beneficial effects of the present invention are as follows:

[0025] This method realizes the efficient treatment of gas hazards in a large area, ahead of schedule, and throughout the whole time and space from the source by developing the up and down mountain roadways. By adopting means such as hydraulic fracturing directional long boreholes, ordinary directional long boreholes, and high-level directional branched long boreholes, it can achieve the efficient treatment of gas in the whole time and space in the coal roadway, fracture zone, upper corner, mining working face, adjacent seams, and goaf during the mining and excavation of medium-hard coal seams, solves the technical problems of the existing gas treatment methods that cannot be treated ahead of schedule in time, cannot cover the whole area in space, and cannot achieve large-area and high-efficiency treatment ahead of schedule in terms of efficiency, reduces the gas treatment workload and cost, and realizes the large-area and high-efficiency gas treatment ahead of schedule throughout the whole time and space.

[0026] Other advantages, objectives, and features of the present invention will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be described in detail preferably with reference to the accompanying drawings, where:

[0028] Figure 1 It is a schematic plan layout diagram of the method for efficient gas treatment in a large area and throughout the whole time and space in medium-hard coal seams;

[0029] Figure 2 It is a schematic diagram of the segmented hydraulic fracturing process of the bedding directional long borehole;

[0030] Figure 3 It is a schematic sectional layout diagram of the high-level directional branched long borehole in the coal seam strike direction;

[0031] Figure 4 It is a schematic sectional layout diagram of the high-level directional branched long borehole in the coal seam dip direction.

[0032] Reference numerals:

[0033] 1 - Development of up and down roadways, 2 - Haulage roadway of the coal mining face, 3 - Return airway of the coal mining face, 4 - Cutting roadway of the coal mining face, 5 - Hydraulic fracturing directional long borehole, 6 - Main hole, 7 - Branch hole on the coal roadway side, 8 - Branch hole on the mining side, 9 - Drainage control area boundary line of the branch hole of the high-level directional branch long borehole, 10 - Coal seam, 11 - Drainage pipeline, 12 - Ordinary directional long borehole, 13 - Front packer, 14 - Rear packer;

[0034] r - Hydraulic fracturing radius, X - Length of the coal mining face, X1 - Spacing of segmented hydraulic fracturing, Y - Width of the cutting roadway of the coal mining face, Y1 - Spacing between two adjacent hydraulic fracturing directional long boreholes, Y2 - Horizontal projection length of the branch hole on the mining side in the dip direction of the coal seam, Y3 - Horizontal projection length of the branch hole on the coal roadway side in the dip direction of the coal seam, Y p - Gas emission zone width of the return airway of the coal mining face, W - Width of the return airway of the coal mining face, L1 - Optimal construction position of the main hole in the dip direction of the coal seam, R - Drainage radius of the coal seam. Specific implementation manners

[0035] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the drawings provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0036] Among them, the drawings are only for illustrative purposes, showing only schematic diagrams, not physical diagrams, and cannot be understood as a limitation to the present invention; in order to better illustrate the embodiments of the present invention, some components in the drawings will be omitted, enlarged or reduced, and do not represent the dimensions of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0037] In the drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc. indicating the orientation or position relationship, it is based on the orientation or position relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only for illustrative purposes and cannot be understood as a limitation to the present invention. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0038] Please refer to Figures 1 to 4 , which is a method for efficient gas control in large areas of medium-hard coal seams throughout the whole space and time, specifically including the following steps:

[0039] Step 1: Reasonably arrange in-seam long directional boreholes along the bedding.

[0040] The in-seam long directional boreholes along the bedding are divided into hydraulic fracturing long directional boreholes 5 and ordinary long directional boreholes 12. First, investigate the hydraulic fracturing influence radius of the in-seam long directional boreholes along the bedding, then design and construct the hydraulic fracturing long directional boreholes 5 in the coal seam according to the hydraulic fracturing influence radius and conduct hydraulic fracturing on the coal seam, and finally design and construct the ordinary long directional boreholes 12 in the middle of two hydraulic fracturing long directional boreholes 5. The specific implementation method is as follows:

[0041] (1) Investigate the hydraulic fracturing influence radius of the long directional boreholes along the bedding

[0042] Since the coal seam thickness and gas content vary in different regions, the hydraulic fracturing radius of the long directional boreholes along the bedding is different. Therefore, first investigate the hydraulic fracturing radius of the long directional boreholes along the bedding, and draw the variation curves of the hydraulic fracturing radius of the long directional boreholes along the bedding in different regions with parameters such as coal seam thickness and gas content for reference when designing the hydraulic fracturing long directional boreholes 5.

[0043] (2) Design and construct the hydraulic fracturing long directional boreholes 5

[0044] According to the magnitudes of parameters such as coal seam thickness and gas content in different regions, by referring to the variation curves of the hydraulic fracturing radius of the long directional boreholes along the bedding in different regions with parameters such as coal seam thickness and gas content, determine the hydraulic fracturing radius r of the long directional boreholes along the bedding in different regions. Design and construct the hydraulic fracturing long directional boreholes 5 in the coal seam according to the determined hydraulic fracturing radius r of the long directional boreholes along the bedding.

[0045] (3) Conduct sectional hydraulic fracturing on the coal seam

[0046] Refer to Figure 1 、 Figure 2 , and according to the capacity of the hydraulic fracturing pump unit, conduct sectional hydraulic fracturing on the coal seam at regular intervals X1 in the coal seam strike direction until the entire directional borehole completes hydraulic fracturing.

[0047] And so on, complete the hydraulic fracturing of the coal seam in the entire gas control area.

[0048] (4) Design and construct the ordinary long directional boreholes 12

[0049] Refer to Figure 1, a common directional long borehole 12 is designed and constructed exactly in the middle between two adjacent hydraulic fracturing directional long boreholes 5, and each common directional long borehole 12 can enhance gas extraction.

[0050] Step 2: Reasonably arrange the roof high-level directional branched long boreholes.

[0051] The roof high-level directional branched long borehole includes a main hole 6 and branched holes communicating with the main hole. The branched holes include a coal roadway side branched hole 7 and a mining side branched hole 8. First, determine the optimal construction position of the main hole 6, and then design and construct the main hole 6, the coal roadway side branched hole 7, and the mining side branched hole 8. The specific implementation method is as follows:

[0052] (1) Determine the optimal construction position of the main hole 6

[0053] The optimal construction position of the main hole 6 mainly includes the optimal construction position in the coal seam dip direction and the optimal construction horizon in the vertical direction, and its determination method is as follows:

[0054] 1) The optimal construction position in the coal seam dip direction

[0055] During the mining process of the working face, after the roof collapses, a bending zone, a fissure zone, and a caving zone will be formed. As mining progresses, an "O"-shaped ring will appear in the goaf behind the working face, and part of the goaf will be compacted. That is, during the entire mining process, there will be an unrelieved pressure zone, a relieved pressure zone, and a compacted zone in the overlying strata of the roof on the side of the return airway 3 of the mining working face close to the mining working face. Therefore, arranging the main hole 6 in the middle of the relieved pressure zone is the optimal position.

[0056] Through theoretical analysis, the horizontal length of the unrelieved pressure area is generally h / tan(α + β), where α is the coal seam dip angle and β is the roof overlying strata pressure relief angle; according to the empirical formula, the re-compacted area of the mined-out area is generally not greater than 1 / 3 of the cutting width Y of the mining working face. From this, it can be obtained that the optimal construction position of the main hole 6 in the coal seam dip direction is bounded by the lower coal wall of the return airway of the mining working face (close to the mining side) and at an interval of L1 distance, and the calculation formula for L1 is: L1 = [Y / 3 - h / tan(α + β)] ÷ 2; in the formula: L1 is the optimal construction position of the main hole in the coal seam dip direction, unit: m; α is the coal seam dip angle, unit: °; β is the roof overlying strata pressure relief angle, unit: °; Y is the cutting width of the working face, unit: m; h is the vertical distance between the hydraulic fracturing directional long borehole 5 and the coal seam roof, unit: m.

[0057] 2) The optimal construction horizon in the vertical direction

[0058] Refer to Figure 3, collect the comprehensive mine columnar section, mine geological exploration boreholes and drilled holes that have been constructed, analyze the lithology and mechanical parameters of the roof rock strata of the coal seam, and according to the "three-zone" theory of the roof, the directional long hydraulic fracturing borehole 5 is arranged at the topmost part of the roof fracture zone, that is, at the junction of the roof bending zone and the fracture zone. This arrangement increases the length of the branch holes (the branch hole 7 on the coal roadway side and the branch hole 8 on the mining side) in the fracture zone and the caving zone, and increases the gas extraction volume. Therefore, the optimal construction horizon h of the main hole 6 in the vertical direction can be obtained by substituting the roof lithology and mechanical parameters into the empirical calculation of the roof fracture zone, which will not be elaborated here.

[0059] (2) Design and construct the main hole 6, the branch hole 7 on the coal roadway side, and the branch hole 8 on the mining side

[0060] 1) Design the main hole

[0061] The designed length of the main hole 6 in the coal seam strike direction is generally greater than the length X of the mining face and exceeds 20 m. In the coal seam dip direction, the main hole 6 of each mining face is designed according to the above method for determining the optimal position of the main hole.

[0062] 2) Design the branch holes

[0063] The branch holes include two types: the branch hole 7 on the coal roadway side and the branch hole 8 on the mining side. The design parameters of each type of branch hole include the horizontal projection length in the coal seam dip direction, the opening spacing or horizontal projection spacing in the coal seam strike direction, and the determination method is as follows:

[0064] ① The branch hole 7 on the coal roadway side

[0065] Refer to Figure 1 、 Figure 3 and Figure 4 , according to the design parameters of the mining face, the horizontal projection length Y3 of the branch hole 7 on the coal roadway side in the coal seam dip direction should cover the return airway 3 of the mining face and the gas drainage zone of the return airway of the mining face, and its calculation formula is: Y3≥L1+W+Y p ; In the formula: W is the width of the return airway of the mining face, with the unit of m; Y p is the width of the gas drainage zone of the return airway of the mining face, with the unit of m.

[0066] Preferably, the opening spacing of the branch hole 7 on the coal roadway side in the coal seam strike direction is the same as the spacing X1 of the sectional hydraulic fracturing, and the coal hole sections of the branch hole 7 on the coal roadway side should be distributed in the middle area of the sectional hydraulic fracturing as much as possible, that is, the coal hole sections of the branch hole 7 on the coal roadway side are located in the middle of X1. The construction length of the branch hole 7 on the coal roadway side is controlled by the end hole point, and the spacing between the end hole points of two adjacent branch holes 7 on the coal roadway side is less than or equal to 2 times the extraction radius R of the coal seam.

[0067] ② The branch hole 8 on the mining side

[0068] Refer to Figure 1 、 Figure 3 and Figure 4 According to the design parameters of the coal mining face, the horizontal projection length Y2 of the extraction side branch hole 8 in the coal seam dip direction should exceed the re-compacted area of the goaf. According to the empirical formula, the re-compacted area of the mined goaf is generally not less than 1 / 3 of the cut width Y of the coal mining face, that is, Y2≥Y / 3.

[0069] The opening spacing of the extraction side branch hole 8 in the coal seam strike direction is the same as the spacing X1 of the segmented hydraulic fracturing, and the coal hole section of the extraction side branch hole 8 should be distributed in the middle area of the segmented hydraulic fracturing as much as possible, that is, the coal hole section of the extraction side branch hole 8 is located in the middle of X1. The construction length of the extraction side branch hole 8 is also controlled by the end hole point, and the distance between the end hole points of two adjacent extraction side branch holes 8 is less than or equal to 2 times the gas extraction radius R of the coal seam.

[0070] 3) Construction of the main hole and branch holes

[0071] After the construction parameters of the main hole and branch holes are designed, the construction is carried out according to the design parameters. First, construct the main hole. When the main hole construction reaches the predetermined depth, the branch holes (the gateway side branch hole 7 and the extraction side branch hole 8) are constructed in a retreating manner from the bottom of the main hole to the hole mouth at intervals of X1.

[0072] To ensure the gas extraction effect, during the construction of each branch hole (the gateway side branch hole 7 and the extraction side branch hole 8), a hole protection screen pipe is installed throughout the hole in each branch hole.

[0073] Step 3: Connect to the extraction pipeline 11 for gas extraction.

[0074] Refer to Figure 1 According to the outburst prevention requirements, the in-seam directional long boreholes and the high-level directional branch long boreholes in the coal seam roof of each coal mining face are separately divided into 1 extraction unit, and are separately connected to the extraction pipeline for gas extraction volume measurement. Then, according to the gas extraction volume, the gas extraction compliance judgment is carried out. Coal roadway driving operations can only be carried out after the gas extraction in the coal roadway strip area meets the standards; mining operations can only be carried out after the gas extraction in the mining area meets the standards.

[0075] During the coal roadway driving process, the high-level directional branch long boreholes in the roof continue to extract the gas in the designed coverage area. At the same time, the hole protection screen pipe of the coal roadway strip branch hole exposed in the coal roadway is replaced with an extraction pipe and a tee is installed, and a pipeline is led out and buried in the goaf to extract the gas in the goaf and the gas gushing from adjacent layers during the coal mining face mining. Thus, the large-area and full-time and space high-efficiency gas control during the mining and excavation process of medium-hard coal seams is realized. This method only takes one working face as an example, and other working faces can be analogized according to the mining and excavation succession.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the present technical solution, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A method for efficient gas control in a large area of medium-hard coal seams throughout the whole space and time, characterized in that It includes the following steps: S1. Set a number of in-seam directional long boreholes inside the coal seam; S2. Set a number of roof high-level directional branched long boreholes at the roof of the coal seam; S3. Connect to the gas drainage pipeline for gas drainage. In step S1, the in-seam directional long boreholes are divided into hydraulic fracturing directional long boreholes (5) and ordinary directional long boreholes (12). Among them, each ordinary directional long borehole (12) is arranged exactly in the middle between two adjacent hydraulic fracturing directional long boreholes (5) to enhance gas drainage, and each hydraulic fracturing directional long borehole (5) is subjected to segmented hydraulic fracturing. In step S2, the roof high-level directional branched long borehole includes a main hole (6) and branched holes communicating with the main hole. The optimal construction position of the main hole (6) in the dip direction of the coal seam is bounded by the lower coal wall near the mining side of the return airway (3) of the mining face and is spaced at a distance of L1 as the optimal construction position. The calculation formula for L1 is: L1 = [Y / 3 - h / tan(α + β)] ÷ 2; In the formula: α is the coal seam dip angle, in °; β is the roof overburden pressure relief angle, in °; Y is the cutting width of the mining face, in m; h is the vertical distance between the hydraulic fracturing directional long borehole (5) and the coal seam roof, in m. The branched hole includes a gateway side branched hole (7) and a mining side branched hole (8); among them, the horizontal projection length Y3 construction range of the gateway side branched hole (7) in the dip direction of the coal seam needs to cover the return airway (3) of the mining face and the gas drainage zone of the return airway of the mining face. Its calculation formula is: Y3 ≥ L1 + W + Y p ; Where: L1 is the optimal construction position of the main hole in the dip direction of the coal seam, with the unit of m; W is the width of the return airway of the coal mining face, with the unit of m; Y p is the width of the gas drainage zone of the return airway of the coal mining face, with the unit of m; The horizontal projection length (Y2) of the mining side branched hole (8) in the dip direction of the coal seam needs to exceed the re-compacted area of the goaf and be not less than 1 / 3 of the cutting width (Y) of the mining face, that is, Y2 ≥ Y / 3.

2. The method for highly efficient gas control in large areas of medium-hard coal seams throughout the whole space and time according to claim 1, characterized in that: In step S2, the optimal construction horizon of the main hole (6) in the vertical direction is arranged at the topmost part of the roof fracture zone, that is, the junction of the roof bending zone and the fracture zone.

3. The method for highly efficient gas control in large areas of medium-hard coal seams throughout the whole time and space according to claim 1, characterized in that: In step S2, the length of the main hole (6) in the strike direction of the coal seam is greater than the length (X) of the mining face and exceeds 20 m.

4. The method for highly efficient gas control in large areas of medium-hard coal seams throughout the whole space and time according to claim 1, characterized in that: In step S2, in the dip direction of the coal seam, the construction position of the main hole (6) corresponding to each mining face is designed according to the optimal construction position L1.

5. The high-efficiency gas control method for large areas of medium-hard coal seams in all time and space according to claim 1, characterized in that: In step S2, the opening spacing of the gateway side branched hole (7) and the mining side branched hole (8) in the strike direction of the coal seam is the same as the spacing (X1) of the segmented hydraulic fracturing, and the coal hole sections of each gateway side branched hole (7) and the mining side branched hole (8) are distributed in the middle area between two adjacent segmented hydraulic fracturing intervals.

6. The method for highly efficient gas control in large areas of medium-hard coal seams throughout the whole space and time according to claim 1, characterized in that: In step S2, during the construction of each gateway side branched hole (7) and mining side branched hole (8), a hole protection screen pipe is installed throughout the branched hole.

7. The method for highly efficient gas control in large areas of medium-hard coal seams throughout the whole space and time according to claim 1, characterized in that: In step S3, during the gateway driving process, the roof high-level directional branched long borehole continues to cover the regional gas, and at the same time, the hole protection screen pipe of the gateway strip branched hole exposed in the gateway is replaced with a drainage pipe and a tee is installed, and a pipeline is led out and buried in the goaf to drain the gas in the goaf and the gas gushing from adjacent layers during the mining of the working face.

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