A combined ground shaft and downhole horizontal well drilling method

Abstract

The application discloses a combined well arrangement method of surface vertical shaft and underground horizontal well, comprising the following steps: determining vertical shaft estimated fracturing information and horizontal well estimated fracturing information according to obtained fracturing construction information of surrounding mines; obtaining the width of a working face to be mined and the lateral mining crack range of a mined working face; determining vertical shaft construction information according to the width of the working face to be mined, the lateral mining crack range and the vertical shaft estimated fracturing information; performing fracturing construction on thick and hard roof based on the vertical shaft construction information to obtain a vertical shaft fracturing range; determining horizontal well construction information according to the horizontal well estimated fracturing information and the vertical shaft fracturing range; and performing fracturing construction on a main rock stratum of impact based on the horizontal well construction information; the multiple surface vertical shafts are divided into at least two vertical shaft groups arranged along the tendency of the working face to be mined; the combined well arrangement method can perform omnidirectional fracturing pressure relief on thick and hard roof of an ultra-long working face, and realizes the cooperative prevention and control of rock burst and mine earthquake disaster.

Description

Technical Field

[0001] This invention relates to the technical field of mine roof fracturing and pressure relief methods, specifically to a method for combining surface vertical shafts and underground horizontal shafts. Background Technology

[0002] Thick, hard roofs are one of the main causes of rockbursts and mine tremors. Their high strength and intact structure lead to stress concentration caused by the suspended roof in the low-level goaf, which easily triggers rockbursts. The high-level roof forms a large-scale spatial structure, which is prone to strong mine tremors after instability. Statistics show that 80% of rockbursts and mine tremors in most mining areas are related to the instability of thick, hard roofs.

[0003] In related technologies, surface vertical shaft fracturing methods have significant advantages in regional governance, advanced governance, and pre-fracture weakening of multi-layer thick and hard roofs, and have therefore been widely promoted and applied in the field of mine tremor control. However, for the rockburst and mine tremor disaster problems of ultra-long working faces with a face width ≥350m, the surface vertical shaft fracturing methods in related technologies are still difficult to solve. Based on this, the present invention provides a method for the combined placement of surface vertical shafts and underground horizontal shafts. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in the related art.

[0005] Therefore, embodiments of the present invention propose a method for the combined placement of surface vertical shafts and underground horizontal shafts. This method can achieve comprehensive pre-fracture of the thick and hard roof of ultra-long working faces, reduce fracturing blind zones, and achieve coordinated prevention and control of rockburst and mine earthquake disasters.

[0006] The method for combined surface vertical wells and downhole horizontal wells in this invention includes:

[0007] The method is applicable to the pre-fracture of thick and hard roof in target mines, which include mined faces, unmined faces, and roadways located on both sides of the unmined faces. The thick and hard roof includes rock strata controlled by rock impact and rock strata controlled by seismic activity. The combined shaft layout method includes:

[0008] S1: Based on the fracturing construction information of the surrounding mines, determine the estimated fracturing information of the vertical shaft and the estimated fracturing information of the horizontal shaft for the thick and hard roof.

[0009] S2: Obtain the width of the working face to be mined and the range of lateral mining-induced fractures in the mined working face. Based on the width of the working face to be mined, the range of lateral mining-induced fractures, and the estimated fracturing information of the vertical shaft, determine the vertical shaft construction information. Based on the vertical shaft construction information, perform fracturing operations on the rock strata controlled by impact and the rock strata controlled by seismic activity, and obtain the vertical shaft fracturing range of the surface vertical shaft.

[0010] S3: Determine the horizontal well construction information based on the horizontal well's estimated fracturing information and the vertical well's fracturing range; carry out fracturing operations on the rock strata controlled by the impact based on the horizontal well construction information; the downhole horizontal well is located between the surface vertical well and the roadway.

[0011] The shaft construction information includes the number of surface shafts, which are multiple, and the multiple surface shafts are divided into at least two shaft groups, with the at least two shaft groups arranged at intervals along the dip of the working face to be mined.

[0012] In some embodiments, two adjacent vertical shaft groups are respectively a first vertical shaft group and a second vertical shaft group. The first vertical shaft group includes a plurality of first vertical shafts arranged at intervals along the strike of the working face to be mined, and the second vertical shaft group includes a plurality of second vertical shafts arranged at intervals along the strike of the working face to be mined.

[0013] A vertical plane parallel to the direction of the working face to be mined is defined as a reference plane, and the projections of multiple first shafts on the reference plane and the projections of multiple second shafts on the reference plane are arranged alternately in sequence.

[0014] In some embodiments, the distance between two adjacent first shafts is equal to the distance between two adjacent second shafts.

[0015] In some embodiments, the projections of a plurality of first vertical shafts and a plurality of second vertical shafts onto the reference plane form a plurality of projection areas, which are uniformly arranged along the orientation of the working face to be mined.

[0016] In some embodiments, the estimated fracturing information of the vertical shaft includes the estimated width of the fracturing network. The distance between two adjacent surface vertical shafts, the estimated width of the fracturing network, and the periodic fracture step distance of the thick and hard roof of the working face to be mined satisfy the following formula:

[0017] D = b + d

[0018] D is the distance between two adjacent ground shafts, b is the estimated width of the hydraulic fracturing network, and d is the periodic fracture step distance of the thick and hard roof of the working face to be mined.

[0019] In some embodiments, the number of shaft groups is two.

[0020] In some embodiments, the roadways located on both sides of the working face to be mined are an auxiliary haulage roadway and a haulage roadway, respectively. The auxiliary haulage roadway is closer to the mined working face than the haulage roadway. The first shaft group is closer to the auxiliary haulage roadway than the second shaft group. The shaft construction information also includes the shaft dip position in the direction of the working face to be mined. The arrangement of the shaft dip positions is as follows:

[0021] If the lateral mining-induced fracture range does not extend to the thick, hard roof of the working face to be mined, the distance between the shaft axis of the first vertical shaft and the sidewall of the auxiliary haulage roadway is equal to one-third of the width of the working face to be mined, and the distance between the shaft axis of the second vertical shaft and the sidewall of the haulage roadway is equal to one-third of the width of the working face to be mined; if the lateral mining-induced fracture range extends to the thick, hard roof of the working face to be mined, the distance between the shaft axis of the first vertical shaft and the sidewall of the auxiliary haulage roadway is greater than one-third of the width of the working face to be mined, so that the fracturing range of the vertical shaft and the mining-induced fracture range are arranged at intervals.

[0022] In some embodiments, the underground horizontal shafts are arranged in pairs, with the two underground horizontal shafts arranged in pairs being located close to the auxiliary haulage roadway and the rubber haulage roadway, respectively.

[0023] In some embodiments, the horizontal well estimated fracturing information includes the horizontal well estimated fracturing range. The horizontal well estimated fracturing range, located near the auxiliary haulage roadway, has a first boundary and a second boundary arranged along the dip of the working face to be mined. The first boundary is arranged on the side of the auxiliary haulage roadway near the working face to be mined, and the second boundary is arranged on the side of the auxiliary haulage roadway away from the working face to be mined. The distance between the first boundary and the main side of the auxiliary haulage roadway is six times the width of the auxiliary haulage roadway, and the distance between the second boundary and the secondary side of the auxiliary haulage roadway is twice the width of the auxiliary haulage roadway.

[0024] The estimated fracturing range of the horizontal well located near the haulage roadway has a third boundary and a fourth boundary arranged along the dip of the working face to be mined. The third boundary is located on the side of the haulage roadway closer to the working face to be mined, and the fourth boundary is located on the side of the haulage roadway away from the working face to be mined. The distance between the third boundary and the main side of the haulage roadway is six times the width of the haulage roadway, and the distance between the fourth boundary and the secondary side of the haulage roadway is equal to the width of the haulage roadway.

[0025] The combined surface vertical shaft and underground horizontal shaft layout method of this invention employs surface vertical shafts in the middle of the working face to pre-fracture the rock strata controlled by rockburst and seismic activity. At least two shaft groups are arranged at intervals along the dip of the working face, which increases the coverage of the surface vertical shaft fracture network along the dip of the working face, making it more suitable for pre-fracture and pressure relief in ultra-long working faces (face width ≥ 350m). Simultaneously, underground horizontal shafts are used for pre-fracture in key anti-rockburst areas near the side roadways of the thick, hard roof of the working face, allowing the horizontal shaft fracture network to expand within the rock strata controlled by rockburst. Therefore, this combined surface vertical shaft and underground horizontal shaft layout method can achieve comprehensive and thorough pre-fracture of the thick, hard roof of ultra-long working faces, reducing fracturing blind zones and achieving coordinated prevention and control of rockburst and seismic hazards. Attached Figure Description

[0026] Figure 1 This is a plan view of a method for combining surface vertical wells and downhole horizontal wells according to an embodiment of the present invention.

[0027] Figure 2 This is a cross-sectional view of a method for combining surface vertical wells and downhole horizontal wells according to an embodiment of the present invention.

[0028] Figure label:

[0029] 1. Existing working face;

[0030] 2. The working face to be mined;

[0031] 3. Auxiliary transport tunnels;

[0032] 4. Glue transport tunnels;

[0033] 5. Surface vertical shaft; 51. Vertical shaft fracturing range; 52. First vertical shaft; 53. Second vertical shaft; 54. Vertical shaft fracturing point;

[0034] 6. Downhole horizontal well; 61. Horizontal well fracturing point; 62. Estimated fracturing range of horizontal well; 621. First boundary; 622. Second boundary; 623. Third boundary; 624. Fourth boundary. Detailed Implementation

[0035] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0036] like Figure 1 and Figure 2As shown, the combined surface vertical shaft and underground horizontal shaft layout method of this invention is applicable to the pre-fracture of thick and hard roof in a target mine. The target mine includes a mined working face 1, a working face to be mined 2, and roadways located on both sides of the working face to be mined 2. The thick and hard roof includes rock strata controlled by rock impact and rock strata controlled by rock seismic activity. The combined shaft layout method includes:

[0037] S1: Based on the fracturing construction information of surrounding mines, determine the estimated fracturing information of vertical shafts and horizontal shafts for thick and hard roofs.

[0038] S2: Obtain the width of the working face to be mined and the range of lateral mining-induced fractures in the mined working face 1. Based on the width of the working face to be mined, the range of lateral mining-induced fractures, and the estimated fracturing information of the vertical shaft, determine the vertical shaft construction information. Based on the vertical shaft construction information, carry out fracturing construction on the rock strata controlled by impact and the rock strata controlled by mine seismic activity, and obtain the vertical shaft fracturing range 51 of the surface vertical shaft 5.

[0039] S3: Determine the horizontal well construction information based on the horizontal well's estimated fracturing information and the vertical shaft's fracturing range 51. Based on the horizontal well construction information, carry out fracturing construction on the rock strata that are mainly controlled by the impact. The underground horizontal well 6 is located between the surface vertical shaft 5 and the roadway.

[0040] The vertical shaft construction information includes the number of surface vertical shafts 5, which are multiple. The multiple surface vertical shafts 5 are divided into at least two shaft groups, and the at least two shaft groups are arranged at intervals along the dip of the working face 2 to be mined.

[0041] It is known that, due to the limited fracturing coverage of the surface shaft 5, fracturing blind zones are easily formed at the edge of the fracturing coverage of the shaft (i.e., the area near the roadways on both sides of the working face 2 to be mined). This results in insufficient pressure relief in the area of ​​the low roof (i.e. the rock strata that is the main control of the impact) of the working face 2 near the roadways on both sides, making it difficult to completely eliminate the risk of low roof rockburst.

[0042] The combined surface vertical shaft and underground horizontal shaft layout method of this invention employs surface vertical shafts 5 in the middle of the working face 2 to pre-fracture the rock strata controlled by rock bursts and seismic events. At least two shaft groups are arranged at intervals along the dip of the working face 2, which increases the coverage of the fracture network of the surface vertical shafts 5 along the dip of the working face 2, making it more suitable for pre-fracture and pressure relief in ultra-long working faces (width ≥ 350m). Simultaneously, underground horizontal shafts 6 are used for pre-fracture in key anti-rockburst areas near the side roadways of the thick, hard roof of the working face 2, allowing the horizontal shaft fracture network to expand in the rock strata controlled by rock bursts. Therefore, the combined layout method of surface vertical shafts 5 and underground horizontal shafts 6 can achieve comprehensive pre-fracture of the thick, hard roof of ultra-long working faces, reducing fracturing blind zones and achieving coordinated prevention and control of rockburst and seismic events.

[0043] Specifically, such as Figure 1As shown, the target mine includes multiple ultra-long working faces with a face width ≥ 350m. The ultra-long working face that has been mined is the mined working face 1, and the ultra-long working face that has not been mined is the unmined working face 2. There is a coal pillar between the unmined working face 2 and the mined working face 1. The strike of the unmined working face 2 is the direction of coal mining advance, and the dip of the unmined working face 2 is perpendicular to its strike. The combined shaft layout method of this embodiment is applicable to pre-fracture of the thick and hard roof of the unmined working face 2, reducing the risk of rockburst and mine earthquake disasters during the mining of the unmined working face 2.

[0044] The roadway located on the side of the working face 2 that is close to the already mined working face 1 is called the auxiliary haul roadway 3, and the roadway located on the side of the working face 2 that is far from the already mined working face 1 is called the rubber haul roadway 4. The auxiliary haul roadway 3 and the rubber haul roadway 4 have the same width. The side of the auxiliary haul roadway 3 that is close to the working face 2 is called the main side, and the side of the auxiliary haul roadway 3 that is far from the working face 2 is called the secondary side. The side of the rubber haul roadway 4 that is close to the working face 2 is called the main side, and the side of the rubber haul roadway 4 that is far from the working face 2 is called the secondary side.

[0045] like Figure 2 As shown, the thick, hard roof consists of multiple rock layers from bottom to top. First, the height of the calculated fault zone is determined by combining theoretical calculations and field measurements. Below the fault zone height, the thickest, most intact, and strongest roof layer is the impact-controlled rock layer, with a thickness generally not less than 10m. Above the fault zone height, the thickest, most intact, and strongest roof layer is the seismic-controlled rock layer, with a thickness generally not less than 30m. The surface vertical shaft 3 vertically penetrates both the seismic-controlled and impact-controlled rock layers. The underground horizontal shaft 4 is located within the impact-controlled rock layer and extends along the strike of the working face 2.

[0046] Optionally, step S1 includes: determining the estimated vertical shaft fracturing information for the target mine based on the obtained vertical shaft fracturing construction information of surrounding mines, and determining the estimated horizontal shaft fracturing information for the target mine based on the obtained horizontal shaft fracturing construction information of surrounding mines.

[0047] It is understandable that the geological conditions of the surrounding mines are similar to those of the target mine.

[0048] Based on the vertical shaft fracturing construction information of surrounding mines with similar geological conditions, the expansion of the vertical shaft fracturing network in the target mine under preset fracturing pressure and preset fracturing flow rate can be estimated, and the estimated width and length of the fracturing network can be determined. This facilitates the construction personnel in determining the construction location and spacing of the surface vertical shaft 5, providing a basis for determining the vertical shaft construction information, thereby ensuring that the vertical shaft fracturing range 51 can cover a large area of ​​the thick and hard roof of the working face 2 to be mined, and improving the pre-fracturing effect.

[0049] Meanwhile, based on the horizontal well fracturing construction information of surrounding mines, the expansion of the fracture network of the underground horizontal well 6 in the target mine under the preset fracturing pressure and preset fracturing flow rate can be estimated, and the estimated fracturing range of the horizontal reinforcement and other horizontal well estimated fracturing information can be determined. This facilitates the construction personnel in determining the construction location, spacing and other parameters of the underground horizontal well 6, providing a basis for determining the horizontal well construction information. Thus, the underground horizontal well 6 fracturing construction can be used to pre-fracture the key anti-scour areas on the top of the roadways on both sides, reducing the fracturing blind zone.

[0050] It is known that the mined working face 1 is a working face that has been mined out, and lateral mining-induced fractures will be generated on the side of the mined working face. Optionally, in step S2, the range of lateral mining-induced fractures in the mined working face 1 can be estimated based on the rock strata movement angle, or detected by means of geophysical exploration, and thus the range of lateral mining-induced fractures in the mined working face can be determined.

[0051] Optionally, in step S2, ground microseismic monitoring is used to monitor the expansion of the fracture network in the ground vertical shaft 5, thereby determining the fracture range 51 of the vertical shaft, providing a basis for the horizontal well construction information in step S3, and fully ensuring the fracturing and pressure relief effect.

[0052] Optionally, the fracturing construction steps for the surface vertical shaft 5 and the underground horizontal shaft 6 in steps S2 and S3 are as follows: first, drilling is carried out using a drilling rig, and then fracturing is carried out using a fracturing pump truck; wherein, the surface vertical shaft 5 is constructed downward from the surface to form the surface vertical shaft 5, and the underground horizontal shaft 6 is constructed upward inclined from the haulage roadway 4 and the auxiliary haulage roadway 3 to form the underground horizontal shaft 6.

[0053] Optionally, such as Figure 2 As shown, during the fracturing operation of surface shaft 5, two fracturing points 54 are first formed in the lowest rock stratum using a perforation technique. These two fracturing points 54 form a group, with a spacing of 18m to 25m, preferably 20m, between them. A fracturing section is formed between the two fracturing points 54 in the same group. Water fracturing is then performed on these two fracturing points 54. Afterwards, a bridge plug technique is used to seal the fracturing section, thus completing the fracturing operation for the lowest rock stratum. Subsequently, the same method is used to perform vertical well fracturing on multiple rock strata from bottom to top, allowing the fracturing network to be distributed across the rock strata primarily controlled by impact and seismic activity.

[0054] During the fracturing operation of downhole horizontal well 4, two horizontal well fracturing points 61 are first formed at the end of downhole horizontal well 6 furthest from its wellhead using a perforation process. The two horizontal well fracturing points 61 form a group, and the distance between the two horizontal well fracturing points 61 in the same group is 18m to 25m, preferably 20m. A horizontal well fracturing section is formed between the two horizontal well fracturing points 61 in the same group. Water injection fracturing is performed on the group of horizontal well fracturing points 61. Then, the horizontal fracturing section is sealed using a bridge plug process, thus completing the fracturing operation of this section of the horizontal well. Subsequently, multiple horizontal fracturing sections are constructed sequentially along the direction close to the wellhead using the same construction method, thereby achieving fracturing operation of the rock strata that are mainly impacted, reducing fracturing blind zones, and reducing the risk of low-level roof rockburst.

[0055] In some embodiments, such as Figure 1 As shown, the two adjacent vertical shaft groups are the first vertical shaft group 52 and the second vertical shaft group 53. The first vertical shaft group 52 includes multiple first vertical shafts 52 arranged at intervals along the direction of the working face 2 to be mined. The second vertical shaft group 53 includes multiple second vertical shafts 53 arranged at intervals along the direction of the working face 2 to be mined. The vertical plane parallel to the direction of the working face 2 to be mined is defined as the reference plane. The projections of multiple first vertical shafts 52 on the reference plane and the projections of multiple second vertical shafts 53 on the reference plane are arranged alternately in sequence.

[0056] With the above arrangement, the multiple first shafts 52 of the first shaft group and the multiple second shafts 53 of the second shaft group are staggered and arranged in a three-flower shape. The fracturing network formed by the first shaft 52 and the fracturing network formed by the second shaft 53 are staggered and arranged, which can reduce the number of ground shafts 5 while ensuring the coverage of the fracturing network on the top of the working face 2 to be mined. In other words, it can reduce construction costs while ensuring the pre-fracture effect.

[0057] It is understandable that the reference plane is set vertically and parallel to the orientation of the working face 2 to be mined.

[0058] Optionally, in step S3, based on the shaft construction information, fracturing construction is carried out on the thick and hard roof of the working face 2 to be mined to form a surface shaft 5; when constructing the two shaft groups, an alternating construction method is adopted.

[0059] In some embodiments, such as Figure 1 As shown, the distance between two adjacent first shafts 52 is equal to the distance between two adjacent second shafts 53.

[0060] In some embodiments, such as Figure 2 As shown, the projections of multiple first vertical shafts 52 and multiple second vertical shafts 53 onto the reference plane form multiple projection areas, which are evenly distributed along the direction of the working face 2 to be mined.

[0061] Specifically, the projection of the first vertical shaft 52 onto the vertical plane forms a first projection area, and the projection of the second vertical shaft 53 onto the vertical plane forms a second projection area. Multiple first and second projection areas are arranged alternately along the strike of the working face 2 to be mined, with equal spacing between each first projection area and any two adjacent second projection areas. In other words, the line connecting the first vertical shaft 52 and the two adjacent second vertical shafts 53 forms an isosceles triangle. This further improves the uniformity of the distribution of the first and second vertical shafts 52 and 53 at the top of the working face 2 to be mined, thereby improving the uniformity of the fracture network distribution, enhancing the pre-fracture effect, and ensuring the prevention and control of rockbursts and mine earthquakes.

[0062] In some embodiments, the estimated fracturing information for vertical shafts includes the estimated width of the fracturing network. The distance between two adjacent surface vertical shafts 5, the estimated width of the fracturing network, and the periodic fracture step distance of the thick and hard roof of the working face 2 to be mined satisfy the following formula:

[0063] D = b + d

[0064] D is the distance between two adjacent ground shafts 5, b is the estimated width of the hydraulic fracturing network, and d is the periodic fracture step distance of the thick and hard roof of the working face 2 to be mined.

[0065] With the above settings, it can be ensured that the multiple staggered first shafts 52 and second shafts 53 fully cover the thick and hard roof of the working face 2 along the direction of the working face 2 to be mined, thereby achieving a better pre-splitting effect.

[0066] Optionally, the periodic breaking distance of the thick, hard roof plate of the working face 2 to be mined is obtained according to the formula for the ultimate breaking distance.

[0067] like Figure 1 As shown, the estimated width b of the fracture network of the surface shaft 5 is the dimension of the fracture network of the surface shaft 5 along the direction of the working face 2 to be mined, and the estimated length L of the fracture network is the dimension of the fracture network of the surface shaft 5 along the dip of the working face 2 to be mined.

[0068] In some embodiments, the number of shaft groups is two.

[0069] In this embodiment of the invention, by staggering the two shaft groups, it can be ensured that the fracturing network of the surface shaft 5 fully covers the thick, hard roof of the working face 2 to be mined in all directions. In other embodiments, when the width of the ultra-long working face reaches a certain value, more than two shaft groups can also be set up to ensure that the fracturing network of the surface shaft 5 can fully cover the thick, hard roof of the working face 2 to be mined in all directions.

[0070] In some embodiments, the roadways located on both sides of the working face 2 to be mined are auxiliary haulage roadway 3 and rubber haulage roadway 4, respectively. Auxiliary haulage roadway 3 is closer to the mined working face 1 than rubber haulage roadway 4. The first vertical shaft group 52 is closer to the auxiliary haulage roadway 3 than the second vertical shaft group 53. The vertical shaft construction information also includes the vertical shaft dip position in the direction of the working face 2 to be mined. The arrangement of the vertical shaft dip positions is as follows:

[0071] If the lateral mining fracture does not extend to the thick, hard roof of the working face 2 to be mined, the distance between the shaft axis of the first vertical shaft 52 and the sidewall of the auxiliary haulage roadway 3 is equal to one-third of the width of the working face to be mined, and the distance between the shaft axis of the second vertical shaft 53 and the sidewall of the haulage roadway 4 is equal to one-third of the width of the working face to be mined.

[0072] If the lateral mining-induced fracture range extends to the thick and hard roof of the working face 2 to be mined, the distance between the shaft axis of the first vertical shaft 52 and the main side of the auxiliary haulage roadway 3 is greater than one-third of the width of the working face to be mined, so that the vertical shaft fracturing range 51 and the mining-induced fracture range are arranged alternately.

[0073] It is known that if the fracturing range 51 of the vertical shaft intersects with the range of the mining-induced fracture, leakage will occur, resulting in a deterioration of the fracturing effect of the surface vertical shaft 5.

[0074] If the lateral mining-induced fracture does not extend to the top of the working face 2 to be mined, the first vertical shaft group 52 and the second vertical shaft group 53 divide the working face 2 into three equal parts along its dip. That is, the distance between the shaft axis of the first vertical shaft 52 and the sidewall of the auxiliary haulage roadway 3 is equal to one-third of the width of the working face to be mined, and the distance between the shaft axis of the second vertical shaft 53 and the sidewall of the haulage roadway 4 is equal to one-third of the width of the working face to be mined (e.g., Figure 1 (As shown); This ensures that the fracturing network of the ground shaft 5 can cover the thick and hard roof of the working face 2 in all directions, thus improving the fracturing effect.

[0075] If the lateral mining-induced fracture extends to the top of the working face 2 to be mined, the first shaft group 52 and the second shaft group 53 need to be moved away from the already mined working face 1. That is, the distance between the shaft axis of the first shaft 52 and the sidewall of the auxiliary haulage roadway 3 is greater than one-third of the width of the working face to be mined. This will ensure that the vertical shaft fracturing range 51 formed by the fracturing construction of the surface shaft 5 has a certain gap with the lateral mining-induced fracture range, thus ensuring the fracturing effect of the surface shaft 5.

[0076] In some embodiments, such as Figure 1 As shown, the underground horizontal shafts 6 are arranged in pairs, with the two pairs of underground horizontal shafts 6 located near the auxiliary haulage roadway 3 and the rubber haulage roadway 4, respectively.

[0077] By setting up two underground horizontal wells 6, the key prevention and control areas at the top of the auxiliary haulage roadway 3 and the rubber haulage roadway 4 can be fracturing simultaneously to prevent the formation of fracturing blind spots and ensure the anti-scour effect.

[0078] Optionally, the length of the underground horizontal well 6 is 500m to 800m. When the strike length of the working face 2 to be mined is greater than the length of the underground horizontal well 6, multiple underground horizontal wells 6 can be set along the strike of the working face 2 to ensure that the fracturing network of the underground horizontal well 6 can completely cover the extension direction of the auxiliary haulage roadway 3 and the haulage roadway 4, and achieve all-round pre-fracture of the key prevention and control area at the top of the roadway.

[0079] In some embodiments, such as Figure 1 As shown, the horizontal well estimated fracturing information includes the horizontal well estimated fracturing range 62. The horizontal well estimated fracturing range 62 arranged near the auxiliary haulage roadway 3 has a first boundary 621 and a second boundary 622 arranged along the dip of the working face 2 to be mined. The first boundary 621 is arranged on the side of the auxiliary haulage roadway 3 near the working face 2 to be mined, and the second boundary 622 is arranged on the side of the auxiliary haulage roadway 3 away from the working face 2 to be mined. The distance D1 between the first boundary 621 and the main side of the auxiliary haulage roadway 3 is six times the width of the auxiliary haulage roadway 3, and the distance D2 between the second boundary 622 and the secondary side of the auxiliary haulage roadway 3 is twice the width of the auxiliary haulage roadway 3.

[0080] The horizontal well near the haulage roadway 4 has a pre-estimation fracturing range 62 with a third boundary 623 and a fourth boundary 624 arranged along the dip of the working face 2 to be mined. The third boundary 623 is arranged on the side of the haulage roadway 4 near the working face 2 to be mined, and the fourth boundary 624 is arranged on the side of the haulage roadway 4 away from the working face 2 to be mined. The distance D3 between the third boundary 623 and the main side of the haulage roadway 4 is six times the width of the haulage roadway 4, and the distance D4 between the fourth boundary 624 and the secondary side of the haulage roadway 4 is equal to the width of the haulage roadway 4.

[0081] Since the top area of ​​the roadway is a key area for preventing rockburst, based on the distribution range of stress concentration areas in the surrounding rock and the need for roof cutting and pressure relief, the prevention areas (i.e., pre-splitting areas) of the main sidewall of auxiliary haulage roadway 3, the secondary sidewall of auxiliary haulage roadway 3, the main sidewall of rubber haulage roadway 4, and the secondary sidewall of rubber haulage roadway 4 can be determined. In addition, since auxiliary haulage roadway 3 is an open roadway and is affected by the lateral overhang of the mined working face 1, the stress concentration of the surrounding rock in auxiliary haulage roadway 3 is greater than that in rubber haulage roadway 4. Therefore, the prevention area of ​​the secondary sidewall of auxiliary haulage roadway 3 is larger than that of the secondary sidewall of rubber haulage roadway 4.

[0082] By imposing the above restrictions on the fracturing range of horizontal wells, the prevention and control requirements of the auxiliary haulage roadway 3 main side, auxiliary haulage roadway 3 secondary side, rubber haulage roadway 4 main side and rubber haulage roadway 4 secondary side can be met, thereby fully pre-fracturing the low-lying thick and hard roof near the roadway area and reducing the risk of rockburst and mine earthquake disasters.

[0083] Optionally, if a single horizontal well cannot fracture and cover the above-mentioned area, the number of underground horizontal wells 6 can be increased. In other words, multiple underground horizontal wells 6 can be set at the top of the auxiliary haulage roadway 3 or the haulage roadway 4 along the dip of the working face 2 to be mined, and the shaft axes of the multiple underground horizontal wells 6 can be arranged in parallel.

[0084] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0085] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0086] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0087] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0088] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0089] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for combining surface vertical wells and downhole horizontal wells, characterized in that, The method is applicable to the pre-fracture of thick and hard roof in target mines, which include mined faces, unmined faces, and roadways located on both sides of the unmined faces. The thick and hard roof includes rock strata controlled by rock impact and rock strata controlled by seismic activity. The combined shaft layout method includes: S1: Based on the fracturing construction information of the surrounding mines, determine the estimated fracturing information of the vertical shaft and the estimated fracturing information of the horizontal shaft for the thick and hard roof. S2: Obtain the width of the working face to be mined and the range of lateral mining-induced fractures in the mined working face. Based on the width of the working face to be mined, the range of lateral mining-induced fractures, and the estimated fracturing information of the vertical shaft, determine the vertical shaft construction information. Based on the vertical shaft construction information, perform fracturing operations on the rock strata controlled by impact and the rock strata controlled by seismic activity, and obtain the vertical shaft fracturing range of the surface vertical shaft. S3: Determine the horizontal well construction information based on the horizontal well's estimated fracturing information and the vertical well's fracturing range; carry out fracturing operations on the rock strata controlled by the impact based on the horizontal well construction information; the downhole horizontal well is located between the surface vertical well and the roadway. The shaft construction information includes the number of surface shafts, which are multiple and divided into at least two shaft groups. The at least two shaft groups are arranged at intervals along the dip of the working face to be mined. Two adjacent shaft groups are designated as a first shaft group and a second shaft group. The first shaft group includes multiple first shafts arranged at intervals along the strike of the working face to be mined, and the second shaft group includes multiple second shafts arranged at intervals along the strike of the working face to be mined. A vertical plane parallel to the direction of the working face to be mined is defined as a reference plane, and the projections of multiple first vertical shafts on the reference plane and the projections of multiple second vertical shafts on the reference plane are arranged alternately in sequence. The number of vertical shaft groups is two. The roadways located on both sides of the working face to be mined are an auxiliary haulage roadway and a haulage roadway, respectively. The auxiliary haulage roadway is closer to the mined working face than the haulage roadway. The first shaft group is closer to the auxiliary haulage roadway than the second shaft group. The shaft construction information also includes the shaft dip positions in the direction of the working face to be mined. The arrangement of the shaft dip positions is as follows: If the lateral mining fracture does not extend to the thick, hard roof of the working face to be mined, the distance between the shaft axis of the first vertical shaft and the sidewall of the auxiliary haulage roadway is equal to one-third of the width of the working face to be mined, and the distance between the shaft axis of the second vertical shaft and the sidewall of the haulage roadway is equal to one-third of the width of the working face to be mined. If the lateral mining fracture range extends to the thick, hard roof of the working face to be mined, the distance between the shaft axis of the first vertical shaft and the main side of the auxiliary haulage roadway is greater than one-third of the width of the working face to be mined, so that the vertical shaft fracturing range and the lateral mining fracture range are arranged at intervals.

2. The method for combining surface vertical wells and downhole horizontal wells according to claim 1, characterized in that, The distance between two adjacent first vertical shafts is equal to the distance between two adjacent second vertical shafts.

3. The method for combining surface vertical wells and downhole horizontal wells according to claim 2, characterized in that, The projections of multiple first vertical shafts and multiple second vertical shafts onto the reference plane form multiple projection areas, which are evenly arranged along the direction of the working face to be mined.

4. The method for combining surface vertical wells and downhole horizontal wells according to claim 2, characterized in that, The estimated fracturing information for the vertical shaft includes the estimated width of the fracturing network. The distance between two adjacent surface vertical shafts, the estimated width of the fracturing network, and the periodic fracture step distance of the thick and hard roof of the working face to be mined satisfy the following formula: D=b+d D is the distance between two adjacent ground shafts, b is the estimated width of the hydraulic fracturing network, and d is the periodic fracture step distance of the thick and hard roof of the working face to be mined.

5. The method for combining surface vertical wells and downhole horizontal wells according to claim 1, characterized in that, The underground horizontal wells are arranged in pairs, with the two underground horizontal wells arranged close to the auxiliary haulage roadway and the rubber haulage roadway, respectively.

6. The method for combining surface vertical shafts and downhole horizontal shafts according to claim 5, characterized in that, The horizontal well estimated fracturing information includes the horizontal well estimated fracturing range. The horizontal well estimated fracturing range arranged near the auxiliary haulage roadway has a first boundary and a second boundary arranged along the dip of the working face to be mined. The first boundary is arranged on the side of the auxiliary haulage roadway close to the working face to be mined, and the second boundary is arranged on the side of the auxiliary haulage roadway away from the working face to be mined. The distance between the first boundary and the main side of the auxiliary haulage roadway is six times the width of the auxiliary haulage roadway, and the distance between the second boundary and the secondary side of the auxiliary haulage roadway is twice the width of the auxiliary haulage roadway. The estimated fracturing range of the horizontal well located near the haulage roadway has a third boundary and a fourth boundary arranged along the dip of the working face to be mined. The third boundary is located on the side of the haulage roadway closer to the working face to be mined, and the fourth boundary is located on the side of the haulage roadway away from the working face to be mined. The distance between the third boundary and the main side of the haulage roadway is six times the width of the haulage roadway, and the distance between the fourth boundary and the secondary side of the haulage roadway is equal to the width of the haulage roadway.

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