Coal mine scour prevention and shock absorption method with ground horizontal well and vertical well arranged in combined mode

Abstract

The invention provides a coal mine scour prevention and shock absorption method with ground horizontal wells and vertical wells arranged in a combined mode, and relates to the technical field of coal mining. By means of the coal mine anti-scour shock-absorbing method for combined arrangement of the ground horizontal well and the vertical well, the advantages of fracturing of the ground horizontal well and the vertical well can be effectively fused, and the defects that single ground vertical well or ground horizontal well arrangement is high in construction cost, limited in coverage range and limited in composite disaster control are overcome; the invention provides a coal mine anti-impact damping technical scheme which is effective and good in economical efficiency. The invention provides a determination basis for comprehensively analyzing and judging fracturing position selection and well shaft arrangement positions of a ground horizontal well and a ground vertical well by combining working face data and open hole logging data, and a method for finely judging and optimizing the fracturing position based on a logging result, and establishes a systematization and standardization basis for designing a ground fracturing overall scheme.

Description

Technical Field

[0001] The invention relates to the technical field of coal mining, and in particular to a method for preventing and reducing shock in a coal mine by jointly arranging a ground horizontal well and a vertical well. Background Art

[0002] The mining conditions of many major coal-producing areas in my country are deep coal seams and overlying multiple layers of thick hard sandstone roof. During the mining of the working face, on the one hand, the overlying thick roof cannot be broken in time, resulting in an increase in the elastic properties of the coal body. On the other hand, the sudden collapse of the thick roof is easy to cause dynamic loads and superimpose with the basic elastic properties of the coal body to induce impact ground pressure disasters, and the sudden breakage of the middle and high roof induces mine earthquake disasters, which poses a serious threat to the safe production of the mine. Surface hydraulic fracturing technology is currently used in the field of fracturing and weakening pre-fracture of the thick hard rock roof of coal mines. It mainly includes two layout methods: horizontal wells and vertical wells. The fracturing section of the horizontal well is horizontal, the length of the fracturing section is large, but the vertical coverage of the rock layer is small. The vertical well is divided into fracturing sections along the vertical direction of the well axis. The fracturing covers more vertical rock layers but the horizontal coverage is small. It is difficult for horizontal wells to accurately obtain the target layer of fracturing before the project is implemented, and the layer will be difficult to adjust after drilling to the horizontal fracturing section. The project implementation risk is high and the requirements for formation stability are high.

[0003] At present, in the field of rock burst and mine-seismic coupling disaster prevention induced by deeply buried multi-layered and thick sandstone roof, on the one hand, there is a lack of effective methods for identifying the main disaster-causing layers or fracturing target rock layers and a clear basis for determining the well axis position; on the other hand, there are difficulties in weakening the target roof due to the large number of vertical layers and large plane range. If a single vertical well or horizontal well arrangement is used for rock pre-cracking, there are problems such as huge engineering workload and high cost, and there is a lack of economical ground fracturing weakening solutions. Summary of the invention

[0004] The invention provides a coal mine anti-shock and shock reduction method by jointly arranging ground horizontal wells and vertical wells, which is used to solve the problems of poor prevention and control effect and poor economy of the existing rock burst and mine earthquake disaster coordinated prevention and control technology.

[0005] The present invention provides a method for preventing and reducing shock in a coal mine by combining ground horizontal wells and vertical wells, comprising: Step S100, determining the distance between two adjacent locations where mine earthquake events occur during mining at the working face, as well as the number of surface vertical wells arranged and the distance between two adjacent surface vertical wells; Step S200, drilling the surface vertical wells based on the number of surface vertical wells and the distance between two adjacent surface vertical wells; Step S300, analyzing the open hole logging data and geological data of the vertical well on the ground to determine the continuous layer for horizontal well fracturing and the thick sandstone layer or sandstone group for vertical well fracturing; Step S400, determining the vertical layer where the surface vertical well and the surface horizontal well are jointly arranged; Step S500, determining the plane position of the well axis of the joint arrangement of the surface vertical well and the surface horizontal well.

[0006] According to a method for preventing and reducing shock in a coal mine with a combined arrangement of ground horizontal wells and vertical wells provided by the present invention, step S100 comprises: Statistically analyze the locations and layers of multiple mine earthquakes that occurred during mining at the current or adjacent working face, and determine the average distance between two adjacent locations of mine earthquakes; Statistically analyze the periodic pressure step distance during the mining period of the working face, and calculate the average interval distance of large periodic pressure; Statistically analyze the rock formation occurrence column chart and mining layout of the working face to determine the strike length and dip range of the roof rock formation pre-splitting required for the working face; Numerical simulation and engineering analogy methods are used to determine the plane extension range of hydraulic fractures in vertical well fracturing; The average interval distance between two adjacent mine earthquake events and the average interval distance between large-cycle pressure are analyzed and compared along the strike length of the working face to obtain the strike interval distance of the ground vertical well arrangement; and the dip interval distance of the ground vertical well arrangement is determined based on the plane expansion range of the hydraulic fractures of the vertical well fracturing; Determine the number of vertical wells arranged in a single row along the strike, the number of vertical wells arranged in a single row along the dip, and the number of vertical wells on the ground within the extended range.

[0007] According to a method for preventing and reducing shocks in coal mines by jointly arranging ground horizontal wells and vertical wells provided by the present invention, the number of single rows of vertical wells arranged along the strike is equal to the quotient of the strike length for implementing pre-splitting of the roof rock formation and the strike spacing distance of the ground vertical wells.

[0008] According to a method for preventing and reducing shocks in coal mines by jointly arranging ground horizontal wells and vertical wells provided by the present invention, the number of single rows of vertical wells arranged along the inclination is equal to the quotient of the inclination range for implementing pre-splitting of the roof rock formation and the inclination spacing distance of the ground vertical wells.

[0009] According to a method for preventing and reducing shocks in coal mines by jointly arranging ground horizontal wells and vertical wells provided by the present invention, the number of ground vertical wells arranged within the expansion range is equal to the product of the number of single rows of vertical wells arranged along the strike and the number of single rows of vertical wells arranged along the inclination.

[0010] According to a method for preventing and reducing shock in a coal mine with a combined arrangement of ground horizontal wells and vertical wells provided by the present invention, step S300 comprises: According to the open hole logging data, the continuous and complete sandstone layer with high sandstone content is determined as the initial selected fracturing target rock layer; Analyze the brittleness coefficient, fracture strength, and geostress orientation and anisotropy of the target rock formation for fracturing; The open hole logging data is compared with the working face borehole column chart to analyze the reliability and variation of the rock formation. The working face boreholes and vertical well positions are connected in sequence along the working face trend to draw a lithology distribution connection diagram. Combined with the stratum distribution connection diagram in the area, the continuous layers for horizontal well fracturing and the thick sandstone strata or sandstone groups for vertical well fracturing are determined.

[0011] According to a method for preventing and reducing shock in a coal mine with a combined arrangement of ground horizontal wells and vertical wells provided by the present invention, step S400 comprises: Collect the histograms in the planned treatment area of ​​the working face, analyze the rock formation parameters in the planned treatment area, and determine the single-layer sandstone or multi-layer continuous sandstone group with high sandstone content, large thickness, good integrity, high cementation degree and good density as the target rock formation for fracturing; Analyze the hydrogeological conditions of the top rock layer to obtain the height and thickness characteristics of the impermeable layer and aquifer overlying the coal seam, so that the fracturing layer avoids the impermeable layer; Determine the height and range of the collapse zone and the fracture zone according to the observation data of the three-zone structure of the overburden in the mine or adjacent working face, wherein the target rock layer for fracturing is located at the upper part of the collapse zone or the lower part of the fracture zone; Collect and analyze the locations of downhole engineering at the working face, so that the fracturing layer avoids the rock formation fracture zone caused by the downhole engineering; Assess the vertical impact range of the fault or fold according to the seismic exploration results or the actual exposure situation, so that the fracturing layer avoids the fault or the fold; Analyze the sandstone content ratio, natural gamma, anisotropy, resistivity and brittleness coefficient of the rock formation according to the open hole logging data of the surface vertical well, and select rock formations with high sandstone content, low porosity, high resistivity, high density and no developed fractures as the target rock formation for fracturing; According to the differences in the technical characteristics of the control targets, the fracturing layer is selected in the low-lying thick and hard sandstone layer or sandstone group close to the coal seam for the purpose of rock burst disaster prevention and control. In this case, the fracturing layer is single-layer or double-layer, and the rock pre-cracking is required to be as continuous and uniform as possible, and the type of well arrangement is ground horizontal well. For the purpose of mine earthquake disaster control, the middle and high sandstone roof within the fracture zone far away from the coal seam is selected. In this case, the number of fracturing layers is large and widely distributed, and it is required to select key layers for fracturing without considering continuity and uniformity, and the type of well arrangement is vertical well.

[0012] According to a coal mine anti-shock and shock reduction method for jointly arranging ground horizontal wells and vertical wells provided by the present invention, the rock formation parameters include lithology, natural gamma, coring rate, cementation degree and rock particle size.

[0013] According to a method for preventing and reducing shock in a coal mine by jointly arranging ground horizontal wells and vertical wells provided by the present invention, the distance between the fracturing layer and the waterproof layer is greater than 15m.

[0014] According to a method for preventing and reducing shock in a coal mine with a combined arrangement of ground horizontal wells and vertical wells provided by the present invention, step S500 comprises: Use numerical simulation or engineering analogy methods to evaluate the expansion height, plane length and width of the hydraulic fracture network in the planned treatment area of ​​the working face, and use the hydraulic fracture expansion boundary as the basis for the horizontal and vertical layout spacing of horizontal wells and vertical wells; According to the direction of regional ground stress, hydraulic fractures expand in the direction of maximum principal stress, thus selecting the well axis layout direction, and determining the well axis layout position based on the length and width of the working surface to be covered and the expansion size of the hydraulic fractures.

[0015] The method for preventing and reducing shocks in coal mines by jointly arranging ground horizontal wells and vertical wells provided by the present invention can effectively integrate the advantages of ground horizontal wells and vertical well fracturing through the method for preventing and reducing shocks in coal mines by jointly arranging ground horizontal wells and vertical wells, overcome the defects of high engineering cost, limited coverage and limitations in complex disaster management of single ground vertical wells or ground horizontal wells, and provide an effective and economical technical solution for preventing and reducing shocks in coal mines. In addition, by giving priority to the implementation of ground vertical wells and obtaining regional stratum lithology distribution characteristics through technical means such as logging, an important basis is provided for the selection of target layers for horizontal well fracturing and the well axis layout position, which makes up for the defect that the horizontal well fracturing layer is difficult to determine in advance and dynamically adjust. It proposes a basis for determining the selection of fracturing layers and the well axis layout position of ground horizontal wells and ground vertical wells by combining working face data and open hole logging data for comprehensive analysis, as well as a method for refining the determination of optimized fracturing layers based on logging results, and establishes a systematic and standardized foundation for the overall design of ground fracturing schemes. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is a vertical schematic diagram of the anti-shock and shock-absorbing geological profile of a coal mine in which the ground horizontal wells and vertical wells are jointly arranged provided by the present invention.

[0018] Figure 2 It is a schematic top view of the anti-shock and shock-absorbing geology of a coal mine in which the ground horizontal wells and vertical wells are jointly arranged, as provided by the present invention.

[0019] Figure 3The present invention provides a flow chart of a method for preventing and reducing shock in a coal mine by combining ground horizontal wells and vertical wells.

[0020] Reference numerals: 1. Coal seam; 2. Rock formations caused by rock burst; 3. The first rock formation caused by mine earthquake; 4. The second rock formation caused by mine earthquake; 5. Geological drilling holes; 6. Ground horizontal wells; 7. The horizontal section of the ground horizontal well; 8. Ground vertical wells; 9. The distance between two adjacent ground vertical wells; 10. The distance between two adjacent horizontal vertical wells; 11. The length of the fracturing section of the ground horizontal well; 12. The goaf behind the working face; 13. The goaf lateral to the working face; 14. The coal pillars along the goaf tunnels and sections; 15. The fracture zone affected by mining; 16. The expected plane expansion radius of the fractures in the horizontal wells and vertical wells; 17. The inclined section of the ground horizontal well; 18. Mine earthquake events. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limitations on the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0023] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0024] In the embodiments of the present invention, unless otherwise clearly specified and limited, the first feature being "above" or "below" the second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0025] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0026] like Figures 1 to 3 As shown in the figure, the coal mine anti-shock and shock reduction methods for the joint arrangement of ground horizontal wells and vertical wells include: Step S100, determining the distance between two adjacent locations where mine earthquake events 18 occur during the mining of the working face, as well as the number of surface vertical wells 8 and the distance between two adjacent surface vertical wells 8; Step S200, drilling a surface vertical well 8 based on the number of surface vertical wells 8 and the distance between two adjacent surface vertical wells 8; Step S300, analyzing the open hole logging data and geological data of the vertical well 8 on the ground to determine the continuous layers for horizontal well fracturing and the thick sandstone layers or sandstone groups for vertical well fracturing; Step S400, determining the vertical layer of the joint arrangement of the surface vertical well 8 and the horizontal well; Step S500, determining the plane position of the well axis of the combined arrangement of the ground vertical well 8 and the horizontal well.

[0027] The method for preventing and damping shocks in coal mines by combining the ground horizontal well 6 and the vertical well provided by the present invention can effectively integrate the advantages of the ground horizontal well 6 and the vertical well, overcome the defects of high engineering cost, limited coverage and limitation of compound disaster management of the single ground vertical well 8 or the ground horizontal well 6, and provide an effective and economical technical solution for preventing and damping shocks in coal mines. It proposes a basis for determining the selection of the fracturing layer and the well axis arrangement position of the ground horizontal well 6 and the ground vertical well 8 by combining the working face data and the open hole logging data for comprehensive analysis, and a method for finely determining and optimizing the fracturing layer based on the logging results of the ground vertical well, and establishes a systematic and standardized foundation for the overall design of the ground fracturing plan.

[0028] In one embodiment of the present invention, step S100 includes: Step S110, statistically analyzing the locations and layers of multiple mine earthquake events 18 during the mining of the current working face or the adjacent working face, and determining the average interval distance between two adjacent locations of the mine earthquake events 18; It should be noted that the mine earthquake events 18 here include not only the previous mine earthquake events 18, but also large-energy microseismic events (1×10 5 J and above).

[0029] Step S120, statistically analyzing the periodic pressure step distance during the mining period of the working face, and calculating the average interval distance of the large periodic pressure; It should be noted here that the periodic pressure step distance refers to the phenomenon that after the initial pressure of the basic top, as the working face continues to advance, the basic top will be exposed for a certain distance, and a fracture and pressure phenomenon will occur, forming a periodic pressure with basically the same fracture distance, and the distance is called the periodic pressure step distance. Large periodic pressure refers to the phenomenon that the pressure has a large impact range, a long duration, and a high support working resistance.

[0030] Step S130, statistically analyzing the rock formation occurrence histogram and mining layout of the working face, and determining the strike length and inclination range of the top rock formation pre-splitting required for the working face; Step S140, using numerical simulation and engineering analogy methods to determine the plane expansion range of hydraulic fractures in vertical well fracturing; Step S150, jointly analyzing and comparing the average interval distance between the locations of two adjacent mine earthquake events 18 and the average interval distance between large-cycle pressure along the strike length of the working face, to obtain the strike interval distance of the surface vertical wells 8; and determining the inclination interval distance of the surface vertical wells 8 based on the plane expansion range of the hydraulic fractures of the vertical well fracturing; Step S160, determining the number of vertical wells arranged in a single row along the strike, the number of vertical wells arranged in a single row along the dip, and the number of vertical wells 8 arranged on the ground within the extended range.

[0031] In one embodiment of the present invention, the number of single rows of vertical wells arranged along the strike is equal to the quotient of the strike length for implementing the pre-splitting of the top rock formation and the strike spacing distance of the vertical wells 8 on the ground.

[0032] In one embodiment of the present invention, the number of single rows of vertical wells arranged along the inclination is equal to the quotient of the inclination range for implementing the pre-splitting of the top rock formation and the inclination spacing distance of the vertical wells 8 arranged on the ground.

[0033] In one embodiment of the present invention, the number of vertical wells 8 arranged on the ground within the extended range is equal to the product of the number of single rows of vertical wells arranged along the strike and the number of single rows of vertical wells arranged along the dip.

[0034] In one embodiment of the present invention, step S300 includes: Step S310, determining a continuous and complete sandstone layer with a high sandstone content as a preliminarily selected target rock layer for fracturing according to open hole logging data; Step S310, analyzing the brittleness coefficient, fracture strength, and geostress orientation and anisotropy of the target rock formation for fracturing in combination with vertical well open hole logging data; It should be noted here that the stronger the brittleness coefficient, the stronger the fracturing ability. Rock formations with too low fracture strength are not suitable for fracturing. Rock formations with many cracks reflected by various anisotropies are not suitable for fracturing.

[0035] Step S310, compare the open hole logging data with the working face borehole column chart, analyze the reliability and variation of the rock layer above the coal seam, connect the working face boreholes and vertical well positions in sequence along the working face trend, draw a lithology distribution connection diagram, and determine the continuous layer for horizontal well fracturing and the thick sandstone layer or sandstone group for vertical well fracturing in combination with the stratum distribution connection diagram in the area to be treated by the working face.

[0036] In one embodiment of the present invention, step S400 includes: Step S410, collecting a histogram in the area to be treated on the working face, analyzing the rock formation parameters in the area to be treated, and determining a single-layer sandstone or a multi-layer continuous sandstone group with high sandstone content, large thickness, good integrity, high cementation degree, and good density as a fracturing target rock formation; It should be noted here that the rock formation parameters include lithology, natural gamma, coring rate, cementation degree and rock particle size. Of course, the specific types of rock formation parameters are not limited to these, and may also include other parameters.

[0037] Step S420, analyzing the hydrogeological conditions of the top rock layer, obtaining the height and thickness characteristics of the impermeable layer and the aquifer overlying the coal seam 1, so that the fracturing layer avoids the impermeable layer; It should be noted here that the fracturing layer is generally a sandstone layer with strong water content. When arranging the fracturing layer, the main impermeable layer must be avoided. The distance between the fracturing layer and the impermeable layer should be greater than 15m to avoid fracturing to destroy the impermeable layer and form a vertical water channel in the formation.

[0038] Step S430, determining the height and range of the collapse zone and the fracture zone according to the structural observation data of the "three zones of overburden" of the mine or the adjacent working face, wherein the target rock layer for fracturing is located at the upper part of the collapse zone or the lower part of the fracture zone; Step S440, collecting and analyzing the locations of the working face where the downhole engineering has been implemented, so that the fracturing layer avoids the rock formation fracture zone caused by the downhole engineering; It should be noted here that the underground engineering here includes but is not limited to water exploration and drainage holes, blasting holes, and medium and low-level hydraulic fracturing holes.

[0039] Step S450, evaluating the vertical impact range of the fault or fold according to the seismic exploration results or the actual exposure situation, so that the fracturing layer avoids the fault or fold; When arranging the fracturing layers, the above-mentioned geological structures must be avoided and a spacing of no less than 10m must be reserved.

[0040] Step S460, analyzing the sandstone content ratio, natural gamma, anisotropy, resistivity and brittleness coefficient of the rock formation according to the open hole logging data of the surface vertical well 8, and selecting a rock formation with high sandstone content, low porosity, high resistivity, high density and no crack development as a target rock formation for fracturing; Step S470, according to the differences in the technical characteristics of the control targets, the fracturing layer is selected in the low-lying thick hard sandstone layer or sandstone group close to the coal seam 1 for the purpose of rock burst disaster prevention and control. In this case, the fracturing layer is a single layer or a double layer, and the rock formation pre-cracking is required to be as continuous and uniform as possible, and the type of well arrangement is a ground horizontal well; for the purpose of mine earthquake disaster control, a medium-to-high-level sandstone roof within the fracture zone far away from the coal seam is selected. In this case, the number of fracturing layers is large and widely distributed, and it is required to select key layers for fracturing without considering continuity and uniformity, and the type of well arrangement is a vertical well.

[0041] It should be noted here that horizontal well drilling under shallow burial depth conditions is restricted by the water-to-vertical ratio (horizontal section length / horizontal section vertical depth), and the water-to-vertical ratio is generally not greater than 2.

[0042] In one embodiment of the present invention, step S500 includes: Step S510, using numerical simulation or engineering analogy method to evaluate the extension height, plane length and width of the hydraulic fracture network in the regional formation, and using the hydraulic fracture extension boundary as the basis for the plane and vertical arrangement spacing of horizontal wells and vertical wells; Step S520, according to the regional ground stress direction, the hydraulic fracture expands in the direction of the maximum principal stress as the dominant direction, so as to select the well axis layout direction, and determine the well axis layout position according to the length and width of the working surface to be covered and the expansion size of the hydraulic fracture.

[0043] It should be noted that the well axis layout needs to avoid the goaf 12 behind the working face and the side of the working face. The distance between the well axis and the goaf can be calculated by the displacement angle of the fractured rock caused by the working face mining, the height of the three-zone development, etc. The well axis plane layout needs to avoid the influence range of geological structure and underground engineering to avoid the risk of drilling leakage.

[0044] The following takes a coal mine working face that uses a combined arrangement of ground vertical wells 8 and ground horizontal wells 6 for anti-shock and shock reduction as an example to introduce a coal mine anti-shock and shock reduction method using a combined arrangement of ground vertical wells 8 and ground horizontal wells 6.

[0045] like Figure 1 and Figure 2 As shown, the coal mine anti-shock and shock reduction method of the combined arrangement of the ground horizontal well 6 and the vertical well includes: By counting all the mine earthquakes / high energy events that occurred during the mining of the working face, the spacing of the ground vertical wells 8 along the strike of the working face is obtained, and the spacing of the ground vertical wells 8 and the number of ground vertical wells 8 are determined according to the dip width and strike length of the working face. After the implementation of the ground vertical well 8 drilling project, the open hole logging of the ground vertical well 8 is carried out and the open hole logging data is analyzed. At the same time, the geological data of the area near the ground vertical well 8, such as the working face geological borehole 5 column chart, geological structure, etc., are analyzed. The vertical layer of the joint arrangement of the ground vertical well 8 and the ground horizontal well 6 is determined by combining the obtained logging interpretation results with the analysis of geological data such as the working face borehole column chart. According to the mining layout conditions and geological conditions of the working face, the well axis plane position of the joint arrangement of the vertical well and the ground horizontal well 6 is determined by predicting the expansion size of the hydraulic fracture.

[0046] According to the mining events of adjacent working faces or working faces with similar conditions, 18 or large-energy microseismic events (1×10 5J and above) to locate the position and layer, and it was found that the average interval between the locations of each adjacent mine earthquake event 18 in the area was about 400m. The periodic pressure step during the working face mining was statistically analyzed, and the average interval distance of the large periodic pressure was calculated. According to the mining layout of the working face, the strike length is 1700m, the dip length is 300m, and one side of the empty tunnel is the lateral goaf 13 of the working face. According to the measurement, the width of the goaf 12 behind the working face and the mining-affected fracture zone 15 is about 20m. Through numerical simulation and engineering analogy methods in this area, it was obtained that the plane radius of the hydraulic fracture expansion under fixed construction parameters is about 140m, and the vertical radius is about 20m. The number of vertical wells in a single row arranged along the strike of ground vertical wells = 1700 (strike length for pre-splitting of the roof rock formation) / 400 (strike interval distance for arrangement of ground vertical wells) = 4.25 (rounded to an integer of 4), the number of vertical wells in a single row arranged along the dip = 300 (dip range for pre-splitting of the roof rock formation) / 280 (dip interval distance for arrangement of ground vertical wells) ≈ 1 (rounded to an integer of 1), and the number of ground vertical wells arranged on the working face is 4*1=4.

[0047] Collect the column chart of the area to be treated in the working face, analyze the regional rock strata lithology, natural gamma, coring rate, cementation degree, rock particle size and other parameters, select a single layer of thick sandstone or a multi-layer continuous sandstone group (rock burst disaster rock layer 2, the first mine earthquake disaster rock layer 3, the second mine earthquake disaster rock layer 4) with high sandstone content, large thickness, good integrity, high cementation degree and good density as the target rock layer for fracturing. According to the structural observation data of the "three zones of overburden" in the mine or adjacent working face, determine the collapse zone and the fracture zone, the distance between the fracturing section and the water layer is not less than 15m, and the target strata for fracturing are selected from the upper part of the collapse zone and the lower part of the fracture zone. The well axis layout needs to avoid the underground engineering implementation area and the geological structure area, and the spacing is not less than 10m. According to the vertical well open hole logging data, further select and determine the target rock layer for fracturing (rock burst disaster rock layer 2, the first mine earthquake disaster rock layer 3, the second mine earthquake disaster rock layer 4). According to the determined rock burst disaster stratum 2 and mine earthquake disaster stratum (first mine earthquake disaster stratum 3 and second mine earthquake disaster stratum 4), the ground horizontal well 6 is selected to pre-crack the rock burst disaster stratum 2, and the vertical well is used to pre-crack the mine earthquake disaster stratum (first mine earthquake disaster stratum 3 and second mine earthquake disaster stratum 4). The rock burst disaster stratum 2 of the working face is about 400m, so the horizontal section length is designed not to exceed 800m. In order to cover the 1600m length of the working face without leaving a blind area for fracturing, 2 ground horizontal wells 6 are required to pre-crack the rock burst disaster stratum 2 at a lower level, and 4 vertical wells are arranged to pre-crack the mine earthquake disaster stratum (first mine earthquake disaster stratum 3 and second mine earthquake disaster stratum 4) at a higher level.

[0048] like Figure 1As shown in the figure, based on the open hole logging data, the continuous and complete sandstone layer with high sandstone content is determined as the initial selected fracturing target rock layer, and then the brittleness coefficient, fracture strength, ground stress orientation and anisotropy of the fracturing target rock layer are analyzed, and the rock layer that is not suitable for arranging fracturing layers is eliminated. Finally, the lithology reflected by the ground vertical well 8 and the geological borehole 5 of the working face is connected and drawn in sequence. Figure 1 The rock formation connection diagram is used to guide the acquisition of rock burst disaster stratum 2, the first mining shock stratum and the second mining shock stratum, and further optimize the determination of the fracturing stratum.

[0049] like Figure 1 and Figure 2 As shown, according to the estimated horizontal well and vertical well fracture plane expansion radius 16 obtained in the above steps, the horizontal well axis layout is designed to be the distance between the mining-affected fracture zone 15 and the working face boundary as the hydraulic fracture network size, and the well axis length needs to be arranged outside the mining fracture influence zone of the working face.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preventing and reducing shock in coal mines by combining horizontal wells and vertical wells on the ground, characterized in that: include: Step S100, determining the distance between two adjacent locations where mine earthquake events occur during mining at the working face, as well as the number of surface vertical wells arranged and the distance between two adjacent surface vertical wells; Step S200, drilling the surface vertical wells based on the number of surface vertical wells and the distance between two adjacent surface vertical wells; Step S300, analyzing the open hole logging data and geological data of the vertical well on the ground to determine the continuous layer for horizontal well fracturing and the thick sandstone layer or sandstone group for vertical well fracturing; Step S400, determining the vertical layer where the surface vertical well and the surface horizontal well are jointly arranged; Step S500, determining the plane position of the well axis of the joint arrangement of the surface vertical well and the surface horizontal well.

2. The method for preventing and reducing shock in coal mines by combining horizontal wells and vertical wells on the ground according to claim 1 is characterized in that: The step S100 includes: Statistically analyze the locations and vertical layers of multiple mine earthquakes that occurred during mining at the current or adjacent working face, and determine the average distance between two adjacent locations of mine earthquakes; Statistically analyze the periodic pressure step distance during the mining period of the working face, and calculate the average interval distance of large periodic pressure; Statistically analyze the rock formation occurrence column chart and mining layout of the working face to determine the strike length and dip range of the roof rock formation pre-splitting required for the working face; Numerical simulation and engineering analogy methods are used to determine the plane extension range of hydraulic fractures in vertical well fracturing; The average interval distance between two adjacent mine earthquake events and the average interval distance between large-cycle pressure are analyzed and compared along the strike length of the working face to obtain the strike interval distance of the ground vertical well arrangement; and the dip interval distance of the ground vertical well arrangement is determined based on the plane expansion range of the hydraulic fractures of the vertical well fracturing; Determine the number of vertical wells arranged in a single row along the strike, the number of vertical wells arranged in a single row along the dip, and the number of vertical wells on the ground within the extended range.

3. The method for preventing and reducing shock in coal mines by combining horizontal wells and vertical wells on the ground according to claim 2 is characterized in that: The number of single rows of vertical wells arranged along the strike is equal to the quotient of the strike length for implementing the pre-splitting of the top rock formation and the strike spacing distance of the vertical wells arranged on the ground.

4. The method for preventing and reducing shock in coal mines by combining horizontal wells and vertical wells on the ground according to claim 2 is characterized in that: The number of single rows of vertical wells arranged along the inclination is equal to the quotient of the inclination range for implementing the pre-splitting of the top rock formation and the inclination spacing distance of the vertical wells arranged on the ground.

5. The method for preventing and reducing shock in coal mines by combining horizontal wells and vertical wells on the ground according to claim 2, characterized in that: The number of vertical wells arranged on the ground within the extended range is equal to the product of the number of single rows of vertical wells arranged along the strike and the number of single rows of vertical wells arranged along the dip.

6. The method for preventing and reducing shock in coal mines by combining horizontal wells and vertical wells on the ground according to any one of claims 1 to 5, characterized in that: The step S300 includes: According to the open hole logging data, the continuous and complete sandstone layer with high sandstone content is determined as the initial selected fracturing target rock layer; Combined with vertical well open hole logging data, the brittleness coefficient, fracture strength, and geostress orientation and anisotropy of the target rock formation for fracturing are analyzed; The open hole logging data is compared with the working face borehole column chart to analyze the reliability and variation of the rock layer above the coal seam. The working face boreholes and vertical well positions are connected in sequence along the working face trend to draw a lithology distribution connection diagram. Combined with the stratum distribution connection diagram in the area to be treated by the working face, the continuous layers for horizontal well fracturing and the thick sandstone strata or sandstone groups for vertical well fracturing are determined.

7. The method for preventing and reducing shock in coal mines by combining horizontal wells and vertical wells on the ground according to any one of claims 1 to 5, characterized in that: The step S400 includes: Collect the histograms in the planned treatment area of ​​the working face, analyze the rock formation parameters in the planned treatment area, and determine the single-layer sandstone or multi-layer continuous sandstone group with high sandstone content, large thickness, good integrity, high cementation degree and good density as the target rock formation for fracturing; Analyze the hydrogeological conditions of the top rock layer to obtain the height and thickness characteristics of the impermeable layer and aquifer overlying the coal seam, so that the fracturing layer avoids the impermeable layer; Determine the height and range of the collapse zone and the fracture zone according to the observation data of the three-zone structure of the overburden in the mine or adjacent working face, wherein the target rock layer for fracturing is located at the upper part of the collapse zone or the lower part of the fracture zone; Collect and analyze the locations of downhole engineering at the working face, so that the fracturing layer avoids the rock formation fracture zone caused by the downhole engineering; Assess the vertical impact range of the fault or fold according to the seismic exploration results or the actual exposure situation, so that the fracturing layer avoids the fault or the fold; Analyze the sandstone content ratio, natural gamma, anisotropy, resistivity and brittleness coefficient of the rock formation according to the open hole logging data of the surface vertical well, and select rock formations with high sandstone content, low porosity, high resistivity, high density and no developed fractures as the target rock formation for fracturing; According to the differences in the technical characteristics of the control targets, the fracturing layer is selected in the low-lying thick and hard sandstone layer or sandstone group close to the coal seam for the prevention and control of rock burst disasters. In this case, the fracturing layer is single-layer or double-layer, and the rock pre-cracking is required to be as continuous and uniform as possible, and the type of well arrangement is ground horizontal well; for the control target of mine earthquake disasters, the middle and high sandstone roof within the fracture zone far away from the coal seam is selected. In this case, the number of fracturing layers is large and widely distributed, and it is required to select key layers for fracturing without considering continuity and uniformity, and the type of well arrangement is vertical well.

8. The method for preventing and reducing shock in coal mines by combining horizontal wells and vertical wells on the ground according to claim 7, characterized in that: The rock formation parameters include lithology, natural gamma, coring rate, cementation degree and rock grain size.

9. The method for preventing and reducing shock in coal mines by combining horizontal wells and vertical wells on the ground according to claim 7, characterized in that: The distance between the fracturing layer and the water-proof layer is greater than 15 m.

10. The method for preventing and reducing shock in coal mines by combining horizontal wells and vertical wells on the ground according to any one of claims 1 to 5, characterized in that: The step S500 includes: Use numerical simulation or engineering analogy methods to evaluate the expansion height, plane length and width of the hydraulic fracture network in the planned treatment area of ​​the working face, and use the hydraulic fracture expansion boundary as the basis for the horizontal and vertical layout spacing of horizontal wells and vertical wells; According to the direction of regional ground stress, hydraulic fractures expand in the direction of maximum principal stress, thus selecting the well axis layout direction, and determining the well axis layout position based on the length and width of the working surface to be covered and the expansion size of the hydraulic fractures.

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