Steeply inclined seam ground reverse inclined shaft top and bottom coal multi-stage collaborative fracturing and impact eliminating method and system

Abstract

The invention provides a steeply inclined seam ground reverse inclined shaft top and bottom coal multi-stage collaborative fracturing and impact eliminating method and system, and relates to the technical field of steeply inclined seam rock burst ground fracturing. According to the method, a wave velocity abnormal region is determined and a geometric centroid point is obtained through a shock wave CT inversion technology. And according to the geometric centroid point, a vertical section and a reverse inclined section of the fractured well are arranged, and a first perforation point, a second perforation point and a third perforation point are arranged in the reverse inclined section and correspond to a coal seam, a top plate fracturing target layer and a bottom plate fracturing target layer respectively. The multi-stage collaborative fracturing is implemented by injecting the fracturing fluid into each perforation point, and the top and bottom coal clamping structure is directionally weakened, so that the rock burst risk of the steeply inclined coal seam is effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of surface fracturing technology for rockburst in steeply inclined coal seams, and in particular to a method and system for multi-stage coordinated fracturing of the top and bottom coal seams in a reverse inclined shaft for rockburst relief in steeply inclined coal seams. Background Technology

[0002] As coal mining progresses to deeper levels, the "three highs" environment (high temperature, high humidity, and high temperature) at depth leads to the accumulation of high elastic energy in coal and rock masses. This is particularly true under mining conditions with steeply inclined coal seams and hard roofs and floors, where the thick, hard roofs and floors form a "clamping" structure, placing the coal mass in a high-stress state and increasing the risk of rockbursts, posing a serious threat to mine safety. To reduce the severity of rockburst hazards under these conditions and prevent rockburst accidents, surface fracturing technology is used for pre-control of the hard coal and rock masses in steeply inclined coal seams.

[0003] Therefore, it is essential to design a multi-stage coordinated fracturing and shock-absorbing method and system for the top and bottom coal seams of steeply inclined coal seams in reverse inclined shafts. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, the purpose of this invention is to provide a multi-stage coordinated fracturing method and system for top and bottom coal in steeply inclined coal seams. By accurately determining the fracturing control points and implementing multi-stage coordinated fracturing of the roof, coal seam and floor, the method achieves directional weakening of the top and bottom coal holding structure of steeply inclined coal seams, effectively reducing the risk of rockburst.

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

[0006] A method and system for multi-stage coordinated fracturing and shock absorption of the top and bottom coal seams in a steeply inclined coal seam surface reverse inclined shaft, comprising:

[0007] Record the upper and lower elevations, dip angles, thicknesses, and target layers for roof and floor fracturing in the proposed mining area of ​​steeply inclined coal seams, and determine their spatial positions.

[0008] A plane rectangular coordinate system is established with the lower end point of the roof side of the proposed mining area as the origin, which is used to characterize the spatial relationship between the trajectory of the fractured well shaft and the coal body and each fractured target layer.

[0009] By monitoring the coal body using seismic wave CT inversion technology, areas with a wave velocity anomaly coefficient greater than or equal to 0.15 are identified, and the distance between the geometric centroid of the area and the lower surface of the coal seam and the lower elevation of the area to be mined is obtained.

[0010] The vertical section of the fracturing well is drilled in a vertical direction from the ground, and after the vertical section reaches the roof fracturing target layer, the anti-inclined section of the fracturing well is drilled in a direction perpendicular to the coal seam inclination, so that the anti-inclined section passes through the geometric center point and the bottom end is connected with the lower surface of the floor fracturing target layer;

[0011] The perforation section is arranged in the anti-inclined section of the fracturing well along the direction of the coal seam inclination, the geometric center point is set as the first perforation point in the coal seam, the second perforation point is set in the roof fracturing target layer, and the third perforation point is set in the floor fracturing target layer, and the distance between the second perforation point and the upper surface of the coal seam and the distance between the third perforation point and the lower surface of the coal seam are determined according to the thickness of the roof fracturing target layer and the thickness of the floor fracturing target layer;

[0012] The fracturing fluid is injected into the first perforation point, the second perforation point and the third perforation point through the ground high-pressure pump, and multi-stage cooperative fracturing is carried out on the coal seam, the roof fracturing target layer and the floor fracturing target layer to weaken the steeply inclined coal seam roof and floor clamping structure and reduce the rock burst danger.

[0013] Preferably, the perforation section is arranged in the anti-inclined section of the fracturing well along the direction of the coal seam inclination, comprising:

[0014] When perforating along the direction of the coal seam inclination, the phase angle of each perforation point is one hundred and eighty degrees, so that the coal seam, the roof fracturing target layer and the floor fracturing target layer form a basically symmetrical development fracture zone around the first perforation point, the second perforation point and the third perforation point on both sides of the coal seam inclination.

[0015] Preferably, the geometric center point is set as the first perforation point in the coal seam, the second perforation point is set in the roof fracturing target layer, and the third perforation point is set in the floor fracturing target layer, comprising:

[0016] The analytical expressions of the distance between the second perforation point and the upper surface of the coal seam and the distance between the third perforation point and the lower surface of the coal seam are derived through geometric relationship, so that the distance between the second perforation point and the upper surface of the coal seam is a function of the thickness of the roof fracturing target layer, and the distance between the third perforation point and the lower surface of the coal seam is a function of the thickness of the floor fracturing target layer.

[0017] Preferably, the length of the vertical section of the fracturing well and the length of the anti-inclined section of the fracturing well are determined in the following manner:

[0018] In the plane rectangular coordinate system, the upper and lower elevations of the proposed mining area, the positions of the upper surface of the coal seam and the lower surface of the coal seam, the positions of the upper surface of the roof fracturing target layer and the lower surface of the floor fracturing target layer, and the position of the geometric center point in the plane rectangular coordinate system are geometric constraints;

[0019] a geometric triangle relationship is established according to the coal seam inclination, the coal seam thickness, the roof fracturing target layer thickness and the floor fracturing target layer thickness;

[0020] Based on the geometric triangle relationship, the length of the vertical section of the fracturing well and the length of the reverse inclined section of the fracturing well are calculated by using trigonometric functions.

[0021] Preferably, the seismic wave CT inversion technology monitors the coal body region during the mining process of the working face, and determines the abnormal region with a wave speed anomaly coefficient greater than or equal to 0.15 in the coal body region based on the seismic wave data obtained during the mining process of the working face.

[0022] Preferably, the upper elevation of the proposed mining region is 1510 meters, the lower elevation is 1460 meters, the coal seam inclination is 60 degrees, the coal seam thickness is 30 meters, the roof fracturing target layer thickness is 32.1 meters, and the floor fracturing target layer thickness is 28.6 meters.

[0023] Preferably, the distance between the geometric center point and the lower surface of the coal seam is 10 meters, the distance between the geometric center point and the lower elevation of the proposed mining region is 26 meters, the length of the vertical section of the fracturing well is 230 meters, and the length of the reverse inclined section of the fracturing well is 105 meters.

[0024] Preferably, the distance between the second perforation point and the upper surface of the coal seam is 10.7 meters, the distance between the third perforation point and the lower surface of the coal seam is 9.5 meters, and in the plane rectangular coordinate system, the horizontal coordinate of the first perforation point is 38.29 meters, the vertical coordinate is 26 meters, the horizontal coordinate of the second perforation point is 11.89 meters, the vertical coordinate is 41.35 meters, and the horizontal coordinate of the third perforation point is 55.06 meters, the vertical coordinate is 16.25 meters.

[0025] Preferably, after the step of injecting fracturing fluid into the first perforation point, the second perforation point and the third perforation point through a ground high-pressure pump to implement multi-stage collaborative fracturing on the coal seam, the roof fracturing target layer and the floor fracturing target layer, the system further comprises:

[0026] The mine pressure intensity during the mining process of the working face is continuously monitored and compared and analyzed by a mine pressure monitoring means to evaluate the weakening effect of the multi-stage collaborative fracturing on the top and bottom coal clamping structure of the steeply inclined coal seam, and to verify the rationality of the arrangement parameters of the vertical section of the fracturing well, the reverse inclined section of the fracturing well and the first perforation point, the second perforation point and the third perforation point.

[0027] A multi-stage collaborative fracturing and rush-in elimination system for steeply inclined coal seam ground reverse inclined well top and bottom coal, comprising:

[0028] A fractured target layer position determination unit is configured to record the upper and lower elevations of a proposed mining area of an acute-inclined coal seam, the coal seam inclination angle, the coal seam thickness, and the roof fractured target layer thickness and the floor fractured target layer thickness, and determine the positions of the roof fractured target layer and the floor fractured target layer in space;

[0029] A coordinate system establishment and wellbore space relationship representation unit is configured to establish a plane rectangular coordinate system with the lower endpoint of the roof side of the proposed mining area as a coordinate origin, and represent the spatial relationship between the wellbore trajectory of a fracturing well and the coal body and each fractured target layer.

[0030] A seismic wave CT inversion and geometric centroid point determination unit is configured to monitor the coal body by using a seismic wave CT inversion technology, determine a region with a wave velocity anomaly coefficient greater than or equal to 0.15, and obtain the distance of the geometric centroid point of the region from the lower surface of the coal seam and the lower elevation of the proposed mining area.

[0031] A fracturing well vertical section and reverse-inclined section construction unit is configured to drill a vertical section of a fracturing well in a vertical direction from the ground, continue drilling in a direction perpendicular to the coal seam inclination after the vertical section reaches the roof fractured target layer, form a reverse-inclined section of the fracturing well, and make the reverse-inclined section pass through the geometric centroid point and have a bottom end connected to the lower surface of the floor fractured target layer.

[0032] A multi-target point perforation section arrangement unit is configured to arrange a perforation section in the reverse-inclined section of the fracturing well along the coal seam inclination direction, set the geometric centroid point as a first perforation point in the coal seam, set a second perforation point in the roof fractured target layer, set a third perforation point in the floor fractured target layer, and determine the distance of the second perforation point from the upper surface of the coal seam and the distance of the third perforation point from the lower surface of the coal seam according to the roof fractured target layer thickness and the floor fractured target layer thickness.

[0033] A multi-stage coordinated fracturing implementation unit is configured to inject fracturing fluid into the first perforation point, the second perforation point and the third perforation point through a ground high-pressure pump, implement multi-stage coordinated fracturing on the coal seam, the roof fractured target layer and the floor fractured target layer, weaken the top and bottom coal clamping structure of the acute-inclined coal seam, and reduce the rock burst risk.

[0034] The present application discloses the following technical effects:

[0035] The present application overcomes the defects of complex structure of steeply inclined coal seam, difficulty of accurately penetrating the dangerous area by the wellbore, and inability to effectively weaken the top and bottom coal clamping structure in the background technology by establishing the spatial relationship model of the top and bottom coal and the fracturing target layer of the roof and floor, and accurately constraining the trajectory of the vertical section and the reverse inclined section of the fracturing well in the plane rectangular coordinate system. The region with a wave velocity anomaly coefficient greater than or equal to 0.15 is obtained by relying on the vibration wave CT inversion technology, and the geometric center point thereof is taken as the fracturing control point, so that the arrangement of the fracturing well is no longer dependent on experience judgment, but is quantitatively positioned based on the real stress abnormal position of the coal body, thereby fundamentally improving the targeting and effectiveness of the fracturing effect on the impact danger source.

[0036] The present application overcomes the problem that the top and bottom coal clamping structure is difficult to be damaged as a whole due to the fracturing of only the coal seam or a single layer in the traditional method by arranging the first perforation point, the second perforation point and the third perforation point in the reverse inclined section of the fracturing well to realize the multi-stage collaborative fracturing of the coal seam, the roof fracturing target layer and the floor fracturing target layer. Since the positions of the perforation points are quantitatively determined based on the layer thickness parameter and the geometric center point, the fracturing fissure can form a through-type weakening zone from inside to outside in the steeply inclined coal seam space, thereby significantly reducing the overall stiffness and energy accumulation capacity of the top and bottom coal, effectively reducing the rock burst danger, and improving the safety and continuity of the mining of the working face. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments. Obviously, the drawings described below only show some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0038] Figure 1 The method flowchart provided for the embodiments of the present application is provided.

[0039] Figure 2 The technical route schematic diagram provided for the embodiments of the present application is provided.

[0040] Figure 3 The ground reverse inclined well arrangement schematic diagram provided for the embodiments of the present application is provided. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0042] The application aims to provide a method and system for multi-stage collaborative fracturing of top and bottom coal in reverse inclined shaft of steeply inclined coal seam, which is based on seismic wave CT inversion and multi-target point perforation to build a collaborative fracturing system, significantly improving the targeting of fracturing on energy-rich areas, and realizing effective release and overall weakening of the impact risk of steeply inclined coal seam.

[0043] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the application will be further described in detail below in combination with the drawings and specific embodiments.

[0044] Figure 1 The method flowchart provided by the embodiment of the application is shown in Figure 1 The application provides a method and system for multi-stage collaborative fracturing of top and bottom coal in reverse inclined shaft of steeply inclined coal seam, which is characterized by comprising the following steps:

[0045] Step 100: recording the upper and lower elevations, coal seam inclination, coal seam thickness, and thickness of the target layer for fracturing of the roof and floor, determining the positions of the target layer for fracturing of the roof and floor in space;

[0046] Step 200: establishing a plane rectangular coordinate system with the lower endpoint of the roof of the proposed mining area as the coordinate origin, which is used to represent the spatial relationship between the wellbore trajectory of the fracturing well and the coal body and each target layer for fracturing;

[0047] Step 300: monitoring the coal body by seismic wave CT inversion technology, determining the area with a wave velocity anomaly coefficient greater than or equal to 0.15, and obtaining the distance of the geometric center point of the area relative to the lower surface of the coal seam and the lower elevation of the proposed mining area;

[0048] Step 400: drilling a vertical section of the fracturing well from the ground in the vertical direction, and after reaching the target layer for fracturing of the roof in the vertical section, continuing to drill a reverse inclined section of the fracturing well in a direction perpendicular to the inclination of the coal seam, so that the reverse inclined section passes through the geometric center point and the bottom end is connected with the lower surface of the target layer for fracturing of the floor;

[0049] Step 500: arranging a perforation section in the reverse inclined section of the fracturing well along the inclination direction of the coal seam, setting the geometric center point as the first perforation point in the coal seam, setting the second perforation point in the target layer for fracturing of the roof, and setting the third perforation point in the target layer for fracturing of the floor, and determining the distance between the second perforation point and the upper surface of the coal seam and the distance between the third perforation point and the lower surface of the coal seam according to the thickness of the target layer for fracturing of the roof and the thickness of the target layer for fracturing of the floor;

[0050] Step 600: injecting fracturing fluid into the first, second and third perforation points through a ground high-pressure pump, and implementing multi-stage collaborative fracturing on the coal seam, the target layer for fracturing of the roof and the target layer for fracturing of the floor, so as to weaken the clamping structure of the top and bottom coal of the steeply inclined coal seam and reduce the risk of rock burst.

[0051] Figure 2 The method flow chart provided by the embodiment of the present application is shown in the figure, and the technical route of the present application comprises: Figure 2

[0052] The upper and lower elevations of the proposed mining area of the steeply inclined coal seam are a and b respectively, the coal seam inclination angle is α, the coal seam thickness is M, the roof fracturing target layer thickness is L, and the floor fracturing target layer thickness is N;

[0053] A plane rectangular coordinate system is established with the lower endpoint of the roof side of the proposed mining area as the origin o;

[0054] The region with a wave velocity anomaly coefficient An≥0.15 in the coal body region during the mining process is determined through the vibration wave CT inversion technology, the geometric center point of the region is recorded as S1, the distance between the S1 point and the lower surface of the coal seam is recorded as S, and the distance between the S1 point and the lower elevation of the proposed mining area is recorded as H;

[0055] The vertical section of the fracturing well is drilled downward from the ground and arranged, after reaching the roof fracturing target layer, the reverse inclined section of the fracturing well is drilled perpendicular to the coal seam inclination and arranged, the reverse inclined section passes through the S1 point and the bottom end is connected with the lower surface of the floor fracturing target layer, the length of the vertical section of the fracturing well is L1, and the length of the reverse inclined section of the fracturing well is L2;

[0056] Perforation operation is performed in the reverse inclined section of the fracturing well, perforation is performed along the inclination direction, and the phase angle is 180°;

[0057] The perforation points of the reverse inclined section in the coal seam, the roof and the floor fracturing target layer are S1, S2 and S3 respectively, the distance between the S2 point and the upper surface of the coal seam is recorded as h1, the distance between the S3 point and the lower surface of the coal seam is recorded as h2, and the coordinates of the S1, S2 and S3 points are (x1, y1), (x2, y2) and (x3, y3) respectively;

[0058] The fracturing liquid is pumped into the coal seam, the roof and the floor fracturing target layer using the ground high-pressure pump, and the fracturing process is completed.

[0059] Specifically, the main steps of the embodiment are:

[0060] a. The upper and lower elevations of the proposed mining area of the steeply inclined coal seam are a and b respectively, the coal seam 4 inclination angle is α, the coal seam 4 thickness is M, the roof fracturing target layer 3 thickness is L, and the floor fracturing target layer 5 thickness is N;

[0061] b. A plane rectangular coordinate system is established with the lower endpoint of the roof side of the proposed mining area as the origin o;

[0062] ​c. Through the shock wave CT inversion technology, the region 6 in which the coal body regional wave velocity anomaly coefficient An is greater than or equal to 0.15 during the mining process of the working face is determined, the geometric center point of the region is recorded as S1, the distance between the S1 point and the lower surface of the coal seam 4 is recorded as S, and the distance between the S1 point and the lower surface of the coal seam 4 is recorded as H;

[0063] d. Drilling from the ground downward and arranging the vertical section 1 of the fracturing well, after reaching the roof fracturing target layer 3, drilling perpendicular to the coal seam 4 and arranging the reverse inclined section 2 of the fracturing well, the reverse inclined section 2 passes through the S1 point and the bottom end is connected with the lower surface of the floor fracturing target layer 5, the length of the vertical section 1 of the fracturing well is L1, and the length of the reverse inclined section 2 of the fracturing well is L2;

[0064] e. Perforating operation is performed in the reverse inclined section 2 of the fracturing well, and perforating is performed along the direction of inclination, and the phase angle is 180°;

[0065] f. The perforating points of the reverse inclined section 2 in the coal seam 4, the roof 3 and the floor 5 fracturing target layer are S1, S2 and S3 respectively, the distance between the S2 point and the upper surface of the coal seam 4 is h1, the distance between the S3 point and the lower surface of the coal seam 4 is h2, and the coordinates of the S1, S2 and S3 points are (x1, y1), (x2, y2) and (x3, y3) respectively.

[0066] g. The fracturing liquid is pumped into the coal seam 4, the roof 3 and the floor 5 fracturing target layer by using the ground high-pressure pump, and the fracturing process is completed.

[0067] Wherein, , , , , , .

[0068] Next, taking the ground reverse inclined well roof and floor coal multi-stage collaborative fracturing of an urgent inclined coal seam in Gansu as an example, the present application is further described in combination with the drawings:

[0069] As shown in Figure 3 , the technical specific steps of the embodiment are:

[0070] a. The upper and lower elevations of the proposed mining area of the urgent inclined coal seam are +1510m and +1460m respectively, the inclination angle of the coal seam 4 is 60°, the thickness of the coal seam 4 is 30m, the thickness of the roof fracturing target layer 3 is 32.1m, and the thickness of the floor fracturing target layer 5 is 28.6m;

[0071] b. Taking the lower end point of the roof of the proposed mining area as the origin o, a plane rectangular coordinate system is established;

[0072] c. Determine the region 6 in which the wave velocity anomaly coefficient An≥0.15 in the coal body region during the mining process of the working face by the shock wave CT inversion technology, record the geometric center point of the region as S1, and record the distance between the S1 point and the lower surface of the coal seam 4 as 10 m, and the distance from the lower surface to the target layer 5 of the coal seam 4 as 26 m;

[0073] d. Drilling and arranging the vertical section 1 of the fracturing well from the ground, after reaching the target layer 3 of the roof fracturing, drilling and arranging the reverse inclined section 2 of the fracturing well perpendicular to the coal seam 4, the reverse inclined section 2 passes through the S1 point and the bottom end is connected with the lower surface of the target layer 5 of the floor fracturing, the length of the vertical section 1 of the fracturing well is 230 m, and the length of the reverse inclined section 2 of the fracturing well is 105 m;

[0074] e. Perforating operation is performed in the reverse inclined section 2 of the fracturing well, and perforating is performed along the direction of inclination, and the phase angle is 180°;

[0075] f. The perforating points of the reverse inclined section 2 in the target layers of the coal seam 4, the roof 3 and the floor 5 are S1, S2 and S3 respectively, the distance between the S2 point and the upper surface of the coal seam 4 is 10.7 m, the distance between the S3 point and the lower surface of the coal seam 4 is 9.5 m, and the coordinates of the S1, S2 and S3 points are (38.29, 26), (11.89, 41.35) and (55.06, 16.25) respectively.

[0076] g. The fracturing liquid is pumped into the target layers of the coal seam 4, the roof 3 and the floor 5 by using the ground high-pressure pump, and the fracturing process is completed.

[0077] The mine pressure monitoring shows that after the coal seam, the roof and the floor are cooperatively fractured, the mine pressure intensity during the mining process of the working face is obviously reduced, and the correctness of the reverse inclined well arrangement method and the parameters of the reverse inclined coal multi-stage cooperative fracturing and shock elimination method of the steeply inclined coal seam ground are verified. By using the above fracturing inclined well arrangement method, it has important significance for reducing the instability of the “clamping” structure of the steeply inclined coal seam roof and floor and ensuring the safe and efficient mining of the steeply inclined coal seam.

[0078] The beneficial effects of the present application are as follows:

[0079] (1) The present application considers the “clamping” structure of the steeply inclined coal seam during mining, and respectively fractures the coal seam, the roof and the floor;

[0080] (2) The method of the present application is accurate and reasonable, and has feasibility, correctness and universality.

[0081] Each embodiment in the specification is described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same and similar parts of each embodiment can be referred to each other. For the system disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and the related parts are referred to the method part.

[0082] The principles and implementations of the present application are described in the specific examples herein, and the above examples are only used to help understand the method of the present application and its core idea; at the same time, for those skilled in the art, according to the idea of the present application, there will be changes in specific implementation and application range. In view of the above, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A method for multi-stage coordinated fracturing and shock reduction of top and bottom coal seams in a steeply inclined coal seam with reverse inclination at the surface, characterized in that, include: Record the upper and lower elevations, dip angles, thicknesses, and target layers for roof and floor fracturing in the proposed mining area of ​​steeply inclined coal seams, and determine their spatial positions. A plane rectangular coordinate system is established with the lower end point of the roof side of the proposed mining area as the origin, which is used to characterize the spatial relationship between the trajectory of the fractured well shaft and the coal body and each fractured target layer. By monitoring the coal body using seismic wave CT inversion technology, areas with a wave velocity anomaly coefficient greater than or equal to 0.15 are identified, and the distance between the geometric centroid of the area and the lower surface of the coal seam and the lower elevation of the area to be mined is obtained. The vertical section of the fracturing well is formed by drilling vertically from the ground. After the vertical section reaches the target layer of the top plate fracturing, the fracturing well continues to be formed in the direction perpendicular to the dip of the coal seam. The anti-inclination section passes through the geometric centroid and its bottom end is connected to the lower surface of the target layer of the bottom plate fracturing. Perforated sections are arranged along the dip direction of the coal seam within the anti-cliff section of the fractured well. The geometric centroid in the coal seam is set as the first perforation point, the second perforation point is set in the target layer of the roof fracture, and the third perforation point is set in the target layer of the floor fracture. The distance between the second perforation point and the upper surface of the coal seam and the distance between the third perforation point and the lower surface of the coal seam are determined according to the thickness of the target layer of the roof fracture and the thickness of the target layer of the floor fracture. Fracturing fluid is injected into the first, second, and third perforation points using a ground-based high-pressure pump to perform multi-stage coordinated fracturing on the coal seam, the roof fracturing target layer, and the floor fracturing target layer, thereby weakening the top and bottom coal clamping structure of the steeply inclined coal seam and reducing the risk of rockburst.

2. The method for multi-stage coordinated fracturing and shock reduction of top and bottom coal seams in steeply inclined coal seams according to claim 1, characterized in that, A perforated section is arranged along the dip direction of the coal seam within the anti-inclination section of the fractured well, including: When perforating along the dip direction of the coal seam, the phase angle of each perforation point is 180 degrees, so that a fracture zone is formed in the coal seam, the target layer of roof fracturing, and the target layer of floor fracturing, which is basically symmetrically spread on both sides of the dip direction of the coal seam around the first perforation point, the second perforation point, and the third perforation point.

3. The method for multi-stage coordinated fracturing and shock reduction of top and bottom coal seams in steeply inclined coal seams according to claim 1, characterized in that, The geometric centroid in the coal seam is set as the first perforation point, the second perforation point is set in the target layer for roof fracturing, and the third perforation point is set in the target layer for floor fracturing, including: Analytical expressions for the distance between the second perforation point and the upper surface of the coal seam and the distance between the third perforation point and the lower surface of the coal seam are derived through geometric relationships, so that the distance between the second perforation point and the upper surface of the coal seam is used as a function of the thickness of the target layer for roof fracturing, and the distance between the third perforation point and the lower surface of the coal seam is used as a function of the thickness of the target layer for floor fracturing.

4. The method for multi-stage coordinated fracturing and shock reduction of top and bottom coal seams in steeply inclined coal seams according to claim 1, characterized in that, The methods for determining the length of the vertical section and the reverse inclination section of the fractured well include: In the plane rectangular coordinate system, the upper and lower elevations of the proposed mining area, the positions of the upper and lower surfaces of the coal seam, the positions of the upper and lower surfaces of the roof fracturing target layer and the lower surface of the floor fracturing target layer, and the position of the geometric centroid in the plane rectangular coordinate system are used as geometric constraints. A geometric trigonometric relationship is established based on the coal seam dip angle, the coal seam thickness, the target layer thickness for roof fracturing, and the target layer thickness for floor fracturing. Based on the aforementioned geometric trigonometric relationship, the length of the vertical section and the length of the anti-inclination section of the fractured well are calculated using trigonometric functions.

5. The method for multi-stage coordinated fracturing and shock reduction of top and bottom coal seams in steeply inclined coal seams according to claim 1, characterized in that, The aforementioned seismic wave CT inversion technology monitors the coal seam area during the mining process and uses the seismic wave data obtained during the mining process to determine abnormal areas within the coal seam area where the wave velocity anomaly coefficient is greater than or equal to 0.

15.

6. The method for multi-stage coordinated fracturing and shock reduction of top and bottom coal seams in steeply inclined coal seams according to claim 1, characterized in that, The upper elevation of the proposed mining area is 1510 meters, the lower elevation is 1460 meters, the coal seam dip angle is 60 degrees, the coal seam thickness is 30 meters, the roof fracturing target layer thickness is 32.1 meters, and the floor fracturing target layer thickness is 28.6 meters.

7. The method for multi-stage coordinated fracturing and shock reduction of top and bottom coal seams in steeply inclined coal seams according to claim 6, characterized in that, The distance between the geometric centroid and the lower surface of the coal seam is 10 meters, and the distance between the centroid and the lower elevation of the proposed mining area is 26 meters. The length of the vertical section of the fractured well is 230 meters, and the length of the anti-inclination section of the fractured well is 105 meters.

8. The method for multi-stage coordinated fracturing and shock reduction of top and bottom coal seams in steeply inclined coal seams according to claim 6, characterized in that, The distance between the second perforation point and the upper surface of the coal seam is 10.7 meters, and the distance between the third perforation point and the lower surface of the coal seam is 9.5 meters. In the plane rectangular coordinate system, the x-coordinate of the first perforation point is 38.29 meters and the y-coordinate is 26 meters, the x-coordinate of the second perforation point is 11.89 meters and the y-coordinate is 41.35 meters, and the x-coordinate of the third perforation point is 55.06 meters and the y-coordinate is 16.25 meters.

9. The method for multi-stage coordinated fracturing and shock reduction of top and bottom coal seams in steeply inclined coal seams according to claim 1, characterized in that, After the step of injecting fracturing fluid into the first, second, and third perforation points via a ground high-pressure pump to perform multi-stage coordinated fracturing on the coal seam, the roof fracturing target layer, and the floor fracturing target layer, the method further includes: The mining pressure intensity during the working face mining process is continuously monitored and compared using mining pressure monitoring methods to evaluate the weakening effect of the multi-stage synergistic fracturing on the top and bottom coal clamping structure of steeply inclined coal seams, and to verify the rationality of the arrangement parameters of the vertical section of the fracturing well, the anti-inclination section of the fracturing well, and the first, second, and third perforation points.

10. A multi-stage coordinated fracturing and shock-absorbing system for the top and bottom coal seams of a steeply inclined coal seam in a reverse-angled shaft, characterized in that... include: The target layer location determination unit is used to record the upper and lower elevations, dip angle, thickness, roof fracturing target layer thickness, and floor fracturing target layer thickness of the proposed mining area of ​​steeply inclined coal seams, and to determine the spatial location of the roof fracturing target layer and floor fracturing target layer. The coordinate system establishment and wellbore spatial relationship characterization unit is used to establish a plane rectangular coordinate system with the lower end point of the roof side of the proposed mining area as the coordinate origin, and is used to characterize the spatial relationship between the fracture wellbore trajectory and the coal body and each fracture target layer; The seismic wave CT inversion and geometric centroid point determination unit is used to monitor the coal body through seismic wave CT inversion technology, determine the area with a wave velocity anomaly coefficient greater than or equal to 0.15, and obtain the distance of the geometric centroid point of the area relative to the lower surface of the coal seam and the lower elevation of the area to be mined. The vertical and anti-slope sections of the fracturing well are constructed by drilling vertically from the ground to form the vertical section of the fracturing well. After the vertical section reaches the target layer of the top plate fracturing, the fracturing well continues to be drilled in a direction perpendicular to the dip of the coal seam to form the anti-slope section of the fracturing well. The anti-slope section passes through the geometric centroid and its bottom end is connected to the lower surface of the target layer of the bottom plate fracturing. A multi-target perforation section arrangement unit is used to arrange perforation sections along the dip direction of the coal seam in the anti-cliff section of the fracturing well. The geometric centroid point in the coal seam is set as the first perforation point, the second perforation point is set in the target layer of the roof fracturing, and the third perforation point is set in the target layer of the floor fracturing. The distance between the second perforation point and the upper surface of the coal seam and the distance between the third perforation point and the lower surface of the coal seam are determined according to the thickness of the target layer of the roof fracturing and the thickness of the target layer of the floor fracturing. The multi-stage coordinated fracturing unit is used to inject fracturing fluid into the first perforation point, the second perforation point, and the third perforation point through a ground high-pressure pump to carry out multi-stage coordinated fracturing of the coal seam, the roof fracturing target layer, and the floor fracturing target layer, so as to weaken the top and bottom coal clamping structure of the steeply inclined coal seam and reduce the risk of rockburst.

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