A method for combining surface vertical wells and downhole horizontal wells

Abstract

This invention discloses a method for combined surface vertical wells and underground horizontal wells, comprising: determining estimated fracturing information for vertical wells and estimated fracturing information for horizontal wells based on fracturing construction information of surrounding mines; obtaining the width of the working face to be mined and the range of lateral mining-induced fractures in the mined working face; determining vertical well construction information 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 wells; performing fracturing construction on the thick and hard roof based on the vertical well construction information; and determining the fracturing range of the surface vertical wells based on the estimated fracturing information of the horizontal wells and the fracturing range of the vertical wells; and performing fracturing construction on the rock strata controlled by rockburst based on the horizontal well construction information. This method for combined surface vertical wells and underground horizontal wells, employing a well layout scheme that coordinates surface vertical wells and underground horizontal wells, can fully fracture and relieve pressure on the thick and hard roof, achieving coordinated prevention and control of rockburst and mine earthquake disasters.

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 wells and underground horizontal wells. 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. Single measures such as underground short-hole fracturing and roof pre-fracture blasting cannot achieve synergistic prevention and control of rockbursts and mine tremors.

[0003] Currently, surface vertical well fracturing measures have significant advantages in regional management, advanced management, and pre-fracture weakening of multi-layered thick and hard roofs, and have been widely promoted and applied in the field of mine tremor control. However, for mines where both rockburst and mine tremor hazards coexist, surface vertical well fracturing measures are prone to creating fracturing blind zones at the regional edges, making it difficult to completely eliminate the risk of rockburst caused by low-to-medium-level roofs. Based on this, this invention provides a method for combined surface vertical well and underground horizontal well layout for zoned prevention and control of rockburst and mine tremors. 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 wells and underground horizontal wells. By coordinating the placement of surface vertical wells and underground horizontal wells, the thick and hard roof can be fully fractured and depressurized, enabling the coordinated prevention and control of rockburst and mine earthquake disasters.

[0006] The method for joint well placement of surface vertical wells and underground horizontal wells in this embodiment of the invention includes: S1: determining the estimated fracturing information of vertical wells and the estimated fracturing information of horizontal wells for the thick and hard roof based on the fracturing construction information of surrounding mines;

[0007] 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 well, determine the vertical well construction information. Based on the vertical well construction information, perform fracturing operations on the seismically controlled rock strata and the impact-controlled rock strata, and obtain the vertical well fracturing range of the surface vertical well. S3: Based on the estimated fracturing information of the horizontal well and the vertical well fracturing range, determine the horizontal well construction information. Based on the horizontal well construction information, perform fracturing operations on the impact-controlled rock strata. The underground horizontal well is located between the surface vertical well and the roadway.

[0008] 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 vertical shaft construction information includes the vertical shaft dip construction position along the dip of the working face to be mined. The arrangement of the vertical shaft dip construction positions is as follows: if the lateral mining 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 surface vertical shaft and the sidewall of the auxiliary haulage roadway is equal to half 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 surface vertical shaft and the sidewall of the auxiliary haulage roadway is greater than half the width of the working face to be mined, so that the vertical shaft fracturing range is arranged alternately with the lateral mining fracture range.

[0009] In some embodiments, the vertical well construction information further includes the vertical well orientation construction location along the direction of the working face to be mined, and the arrangement of the vertical well orientation construction location is as follows: there are multiple surface vertical wells, and the multiple surface vertical wells are arranged along the direction of the working face.

[0010] In some embodiments, the estimated fracturing information for the vertical well includes the estimated width of the fracturing network. The spacing between two adjacent surface vertical wells, the estimated width of the fracturing network, and the periodic fracture step distance of the thick, hard roof of the working face to be mined satisfy the following formula:

[0011] D = (b + d) / 2

[0012] D is the distance between two adjacent vertical wells on the ground, 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.

[0013] In some embodiments, obtaining the vertical well fracturing range in step S2 includes:

[0014] The fracture network expansion of the vertical well is monitored using ground microseismic monitoring to obtain the fracturing range of the vertical well.

[0015] 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.

[0016] 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 inclination 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.

[0017] 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.

[0018] In some embodiments, the vertical well construction information includes the number of vertical well fracturing points, wherein the vertical well fracturing points are grouped in pairs, and multiple groups of vertical well fracturing points are provided, with the multiple groups of vertical well fracturing points arranged sequentially at intervals along the extension direction of the surface vertical well; the horizontal well construction information includes the number of horizontal well fracturing points, wherein the horizontal well fracturing points are grouped in pairs, and multiple groups of horizontal well fracturing points are provided, with the multiple groups of horizontal well fracturing points arranged sequentially at intervals along the extension direction of the horizontal well.

[0019] In some embodiments, step S1: determining the estimated vertical well fracturing information and the estimated horizontal well fracturing information for the target mine based on the fracturing construction information of the surrounding mines includes: determining the estimated vertical well fracturing information for the target mine based on the obtained vertical well fracturing construction information of the surrounding mines, and determining the estimated horizontal well fracturing information for the target mine based on the obtained horizontal well fracturing construction information of the surrounding mines.

[0020] The combined surface vertical well and underground horizontal well layout method of this invention uses surface vertical wells to pre-fracture the rock strata controlled by rock bursts and seismic events at the working face, so that the vertical well fracture network can extend to the rock strata controlled by rock bursts and seismic events. At the same time, underground horizontal wells are used to pre-fracture the rock strata controlled by rock bursts near the roadway area. As a result, it is possible to achieve full fracturing and pressure relief of the thick and hard roof of the working face at all levels, preventing the occurrence of pressure relief blind zones. Therefore, it is more suitable for mines where rock bursts and seismic events coexist, and can achieve synergistic prevention and control of rock bursts and seismic events. Attached Figure Description

[0021] Figure 1 This is a plan view of a surface vertical well and a downhole horizontal well according to an embodiment of the present invention.

[0022] Figure 2 This is a cross-sectional view of a surface vertical well and a downhole horizontal well according to an embodiment of the present invention.

[0023] Figure label:

[0024] 1. Existing working face;

[0025] 2. Working face to be mined; 21. Auxiliary haulage roadway; 22. Glue haulage roadway;

[0026] 3. Surface vertical well; 31. Vertical well fracturing range; 32. Vertical well fracturing point;

[0027] 4. Downhole horizontal well; 41. Estimated fracturing range of horizontal well; 411. First boundary; 412. Second boundary; 413. Third boundary; 414. Fourth boundary; 42. Fracturing point of horizontal well. Detailed Implementation

[0028] 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.

[0029] like Figure 1 and Figure 2 As 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:

[0030] S1: Based on the fracturing construction information of surrounding mines, determine the estimated fracturing information of vertical wells and horizontal wells for thick and hard roofs.

[0031] 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 well, determine the vertical well construction information. Based on the vertical well construction information, carry out fracturing construction on the seismically controlled rock strata and the impact-controlled rock strata, and obtain the vertical well fracturing range 31 of the surface vertical well 3.

[0032] S3: Based on the horizontal well fracturing information and the vertical well fracturing range 31, determine the horizontal well construction information, and carry out fracturing construction on the rock strata controlled by the impact based on the horizontal well construction information. The downhole horizontal well 4 is located between the surface vertical well 3 and the roadway.

[0033] It is known that, due to the limited fracturing coverage of the vertical well 3 on the ground, fracturing blind zones are easily formed at the edge of the vertical well fracturing coverage (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.

[0034] The combined surface vertical well and underground horizontal well layout method of this invention uses surface vertical well 3 to pre-fracture the rock strata controlled by rock bursts and seismic events in the working face 2, so that the vertical well fracture network can extend to the rock strata controlled by rock bursts and seismic events. At the same time, underground horizontal well 4 is used to pre-fracture the rock strata controlled by rock bursts near the roadway area. Thus, it is possible to achieve full fracturing and pressure relief of the thick and hard roof of the working face 2 at all levels, preventing the occurrence of pressure relief blind zones. Therefore, it is more suitable for mines where rock bursts and seismic events coexist, and can achieve synergistic prevention and control of rock bursts and seismic events.

[0035] Specifically, such as Figure 1 As shown, the strike of the working face 2 to be mined is the direction of coal mining advance, and the dip of the working face 2 to be mined is perpendicular to its strike; the roadway located on the side of the working face 2 to be mined closer to the already mined working face 1 is the auxiliary haul roadway 21, and the roadway located on the side of the working face 2 to be mined away from the already mined working face 1 is the haul roadway 22. The auxiliary haul roadway 21 and the haul roadway 22 have the same width. The already mined working face 1 and the working face 2 to be mined are parallel and there is a coal pillar between them. The auxiliary haul roadway 21 is closer to the already mined working face 1 than the haul roadway 22.

[0036] The sidewall of the auxiliary haulage roadway 21 that is close to the working face 2 to be mined is its main sidewall, and the sidewall of the auxiliary haulage roadway 21 that is far away from the working face 2 to be mined is its secondary sidewall. The sidewall of the rubber haulage roadway 22 that is close to the working face 2 to be mined is its main sidewall, and the sidewall of the rubber haulage roadway 22 that is far away from the working face 2 to be mined is its secondary sidewall.

[0037] In this embodiment of the invention, the surface vertical well 3 and the underground horizontal well 4 are arranged on the thick and hard roof of the working face 2 to be mined in the target mine, and are used to pre-crack and relieve pressure on the thick and hard roof to achieve coordinated prevention and control of rockburst and mine earthquake disasters.

[0038] like Figure 2 As shown, the target mine's thick, hard roof comprises 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 primary rock layer controlled by impact, with a thickness generally not less than 10m. Above the fault zone height, the thickest, most intact, and strongest roof layer is the primary rock layer controlled by seismic activity, with a thickness generally not less than 30m. A vertical shaft 3 on the surface vertically penetrates both the primary seismic and impact rock layers. A horizontal shaft 4 underground is located within the primary impact rock layer and extends along the strike of the working face 2 to be mined.

[0039] 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.

[0040] Optionally, in this embodiment of the invention, the fracturing construction steps for the surface vertical well 3 and the downhole horizontal well 4 are as follows: drilling first, followed by fracturing, wherein drilling is carried out using a drilling rig, and fracturing is carried out using a fracturing pump truck.

[0041] In some embodiments, step S1: determining the estimated vertical well fracturing information and the estimated horizontal well fracturing information for the target mine based on the obtained fracturing construction information of surrounding mines includes:

[0042] Based on the vertical well fracturing construction information of surrounding mines, the estimated vertical well fracturing information for the target mine is determined, and based on the horizontal well fracturing construction information of surrounding mines, the estimated horizontal well fracturing information for the target mine is determined.

[0043] It is understandable that the geological conditions of the surrounding mines should be similar to those of the target mine.

[0044] Therefore, 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 the preset fracturing pressure and fracturing flow rate can be estimated. This allows for the determination of vertical shaft fracturing information such as the estimated width and length of the fracturing network, which in turn facilitates the determination of parameters such as the construction location and spacing of the surface vertical shaft 3 by construction personnel. This provides a basis for determining the vertical shaft construction information, thereby ensuring that the vertical shaft fracturing range 31 can cover the thick and hard roof of the working face 2 to be mined, reducing the pre-fracturing blind zone.

[0045] Based on the horizontal well fracturing construction information of surrounding mines with similar geological conditions, the expansion of the horizontal well fracturing network in the target mine under the preset fracturing pressure and fracturing flow rate can be estimated. This allows for the determination of the estimated fracturing range 41 and other estimated horizontal well fracturing information, which in turn facilitates the determination of parameters such as the construction location and spacing of the underground horizontal well 4 by the construction personnel. This provides a basis for determining the horizontal well construction information, thereby further fracturing the blind area of ​​the surface vertical well 3 through the underground horizontal well 4 fracturing construction, ensuring the comprehensive decompression of the thick hard roof of the working face 2, and achieving coordinated prevention and control of rockburst and mine tremors.

[0046] In some embodiments, the roadways located on both sides of the working face 2 to be mined are auxiliary haulage roadway 21 and haulage roadway 22, respectively. Auxiliary haulage roadway 21 is closer to the mined working face 1 than haulage roadway 22. Vertical shaft construction information includes the vertical shaft dip construction position along the dip of the working face 2 to be mined. The arrangement of the vertical shaft dip construction positions is as follows:

[0047] 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 vertical well 3 and the sidewall of the auxiliary haulage roadway 21 is equal to half the width of the working face to be mined (e.g., Figure 1 (as shown);

[0048] If the lateral mining fracture range extends to the thick, hard roof of the working face 2 to be mined, the distance between the shaft axis of the vertical well 3 and the main side of the auxiliary haulage roadway 21 is greater than half the width of the working face to be mined, so that the vertical well fracturing range 31 and the lateral mining fracture range are arranged alternately.

[0049] It is known that if the vertical well fracturing range 31 intersects with the lateral mining fracture range, it will lead to leakage, which will worsen the vertical well fracturing effect of the surface vertical well 3.

[0050] If the fracturing fracture does not extend to the thick, hard roof of the working face 2 to be mined, the surface vertical shaft 3 can be arranged along the dip of the working face 2 at the middle position of the working face 2 to be mined. That is, the distance between the shaft axis of the surface vertical shaft 3 and the sidewall of the auxiliary haulage roadway 21 is equal to half the width of the working face to be mined. Therefore, when carrying out the fracturing construction of the surface vertical shaft 3, fracturing can be carried out evenly from the middle area of ​​the working face 2 to both sides, so that the fracturing range 31 of the vertical shaft can completely cover the thick, hard roof of the working face 2 to be mined in the dip direction, thereby improving the fracturing effect.

[0051] If the mining-induced fracture extends to the thick, hard roof of the working face 2 to be mined, the surface vertical shaft 3 needs to be moved away from the auxiliary haulage roadway 21 in a diagonal position according to the boundary position of the lateral mining-induced fracture range. That is, the distance between the shaft axis of the surface vertical shaft 3 and the main side of the auxiliary haulage roadway 21 is greater than half the width of the working face to be mined. This ensures that the vertical shaft fracturing range 31 formed by the fracturing construction of the surface vertical shaft 3 is arranged alternately with the lateral mining-induced fracture range (the two do not affect each other), thereby ensuring the fracturing effect of the surface vertical shaft 3.

[0052] Therefore, by fracturing the vertical well 3 on the ground, the thick hard roof of the working face 2 can be pre-fractured to achieve a better anti-scour effect.

[0053] It is understandable that the main shaft of auxiliary transport roadway 21 and the main shaft of rubber transport roadway 22 form the main shaft of the aforementioned roadway.

[0054] In some embodiments, such as Figure 1 and Figure 2 As shown, the vertical well construction information also includes the vertical well direction construction location along the direction of the working face 2 to be mined. The arrangement of the vertical well direction construction location is as follows: there are multiple surface vertical wells 3, and the multiple surface vertical wells 3 are arranged along the direction of the working face.

[0055] In some embodiments, the vertical well fracturing information includes the estimated width of the fracturing network. The spacing between two adjacent surface vertical wells 3, the estimated width of the fracturing network, and the periodic fracture step distance of the thick and hard roof of the working face 2 satisfy the following formula:

[0056] D = (b + d) / 2

[0057] D is the distance between two adjacent vertical wells 3 on the ground, 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.

[0058] With the above settings, it can be ensured that the fracturing networks of two adjacent surface vertical wells 3 are connected, so that multiple surface vertical well 3 fracturing networks can completely cover the thick and hard roof of the working face 2 to be mined along the direction of the working face 2, thereby achieving a better pre-fracture effect.

[0059] 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.

[0060] like Figure 1 As shown, the estimated width b of the fracture mesh is the dimension of the fracture mesh along the direction of the working face 2 to be mined; the estimated length L of the fracture mesh is the dimension of the fracture mesh along the dip of the working face 2 to be mined.

[0061] In some embodiments, obtaining the vertical well fracturing range 31 in step S2 includes:

[0062] The fracture network expansion of the vertical well 3 was monitored using ground microseismic monitoring to obtain the fracturing range 31 of the vertical well.

[0063] After the fracturing operation of the vertical well 3 on the ground is completed, the fracturing range 31 of the vertical well is determined by the ground microseismic monitoring method, and then the fracturing blind zone of the vertical well 3 on the ground is determined, so as to provide more accurate data support for the fracturing operation of the downhole horizontal well 4.

[0064] In some embodiments, the underground horizontal shafts 4 are arranged in pairs, with the two underground horizontal shafts 4 arranged close to the auxiliary haulage roadway 21 and the rubber haulage roadway 22, respectively.

[0065] After the fracturing operation of the vertical well 3 is completed, the fracturing network of the vertical well extends along the dip of the working face 2 to be mined. The two edges of the fracturing network extend to the auxiliary haulage roadway 21 and the rubber haulage roadway 22 respectively. Fracturing blind zones are easily formed in the low-lying roof of the top area of ​​the auxiliary haulage roadway 21 and the rubber haulage roadway 22. By setting up two underground horizontal wells 4, the low-lying thick and hard roof of the top area of ​​the auxiliary haulage roadway 21 and the rubber haulage roadway 22 can be further fracturing simultaneously, reducing fracturing blind zones and ensuring the anti-scour effect.

[0066] Optionally, the length of the downhole horizontal well 4 is 500m to 800m.

[0067] When the strike length of the working face 2 to be mined is greater than the length of the downhole horizontal well 4, multiple downhole horizontal wells 4 can be set along the strike of the working face 2 to be mined, so that the horizontal well fracturing network can completely cover the strike of the working face 2 to be mined, and prevent the occurrence of fracturing blind zones.

[0068] In some embodiments, such as Figure 1 As shown, the horizontal well estimated fracturing information includes the horizontal well estimated fracturing range 41. The horizontal well estimated fracturing range 41 arranged near the auxiliary haulage roadway 21 has a first boundary 411 and a second boundary 412 arranged along the dip of the working face 2 to be mined. The first boundary 411 is arranged on the side of the auxiliary haulage roadway 21 close to the working face 2 to be mined, and the second boundary 412 is arranged on the side of the auxiliary haulage roadway 21 away from the working face 2 to be mined. The distance D1 between the first boundary 411 and the main side of the auxiliary haulage roadway 21 is six times the width of the auxiliary haulage roadway 21, and the distance D2 between the second boundary 412 and the secondary side of the auxiliary haulage roadway 21 is twice the width of the auxiliary haulage roadway 21.

[0069] The horizontal well near the haulage roadway 22 has a pre-fracturing range 41 with a third boundary 413 and a fourth boundary 414 arranged along the dip of the working face 2 to be mined. The third boundary 413 is arranged on the side of the haulage roadway 22 near the working face 2 to be mined, and the fourth boundary 414 is arranged on the side of the haulage roadway 22 away from the working face 2 to be mined. The distance D3 between the third boundary 413 and the main side of the haulage roadway 22 is six times the width of the haulage roadway 22, and the distance D4 between the fourth boundary 414 and the secondary side of the haulage roadway 22 is equal to the width of the haulage roadway 22.

[0070] The roadway is a key area for rockburst prevention. Based on the distribution range of stress concentration areas in the surrounding rock and the roof cutting and pressure relief requirements of the roadway, the prevention areas (i.e., pre-splitting areas) of the main sidewall of auxiliary haulage roadway 21, the secondary sidewall of auxiliary haulage roadway 21, the main sidewall of rubber haulage roadway 22, and the secondary sidewall of rubber haulage roadway 22 can be determined. In addition, since auxiliary haulage roadway 21 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 21 is greater than that in rubber haulage roadway 22. Therefore, the prevention area of ​​the secondary sidewall of auxiliary haulage roadway 21 is larger than that of the secondary sidewall of rubber haulage roadway 22.

[0071] By imposing the above restrictions on the estimated fracturing range 41 of the horizontal well, the prevention and control requirements of the main side of the auxiliary haulage roadway 21, the secondary side of the auxiliary haulage roadway 21, the main side of the rubber haulage roadway 22, and the secondary side of the rubber haulage roadway 22 can be met, thereby fully pre-fracturing the low-lying thick and hard roof near the roadway area to ensure the anti-scour effect.

[0072] Optionally, if a single horizontal well cannot fracture and cover the aforementioned area, the number of underground horizontal wells can be increased. In other words, multiple underground horizontal wells can be set at the top of the auxiliary haulage roadway 21 or the haulage roadway 22 along the dip of the working face to be mined. The shaft axes of the multiple underground horizontal wells are arranged in parallel to ensure that the fracturing network of the underground horizontal wells can completely cover the aforementioned prevention and control area.

[0073] In some embodiments, the vertical well construction information includes the number of vertical well fracturing points 32, which are arranged in groups of two or more, and the multiple groups of vertical well fracturing points 32 are arranged sequentially at intervals along the extension direction of the vertical well 3 on the ground; the horizontal well construction information includes the number of horizontal well fracturing points 42, which are arranged in groups of two or more, and the multiple groups of horizontal well fracturing points 42 are arranged sequentially at intervals along the extension direction of the horizontal well.

[0074] Specifically, such as Figure 2As shown, during the fracturing operation of vertical well 3 on the surface, a set of vertical well fracturing points 32 targeting the lowest rock layer was first formed using a perforation process. A vertical fracturing section was formed between the two vertical well fracturing points 32 in this set. Water fracturing was then performed on the two vertical well fracturing points 32 in this set. Afterwards, a bridge plug technique was used to seal the vertical fracturing section, thus completing the vertical well fracturing targeting the lowest rock layer. Subsequently, the same method was used to perform vertical well fracturing on multiple rock layers from bottom to top, including the rock layers controlled by impact and the rock layers controlled by seismic activity.

[0075] Similarly, during the fracturing operation of the downhole horizontal well 4, a set of horizontal well fracturing points 42 far from the wellhead is first formed. A horizontal fracturing section is formed between the two horizontal well fracturing points 42 in this set. Water injection is performed on the two horizontal well fracturing points 42 in this set for fracturing. Then, the horizontal fracturing section is sealed using a bridge plug technique, thus completing the fracturing operation of this section of the horizontal well. Afterward, multiple horizontal fracturing sections are constructed sequentially along the direction close to the wellhead using the same construction method, thereby achieving fracturing operation on the rock strata that are impacting the main controlling rock layer, reducing the fracturing blind zone, and reducing the risk of low-level roof rockburst.

[0076] Optionally, the distance between two vertical well fracturing points 32 in the same group is 18m to 25m, preferably 20m.

[0077] Optionally, the distance between two horizontal well fracturing points 42 in the same group is 18m to 25m, preferably 20m.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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, wherein the target mine includes a mined working face, a working face to be mined, and roadways located on both sides of the working face to be mined, and 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: S1: Based on the fracturing construction information of the surrounding mines, determine the estimated fracturing information of the vertical wells and the estimated fracturing information of the horizontal wells 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 well, determine the vertical well construction information. Based on the vertical well construction information, perform fracturing operations on the seismically controlled rock strata and the impact-controlled rock strata, and obtain the vertical well fracturing range of the surface vertical well. S3: Based on the estimated fracturing information of the horizontal well and the fracturing range of the vertical well, determine the construction information of the horizontal well, and carry out fracturing construction on the rock strata controlled by the impact based on the construction information of the horizontal well. The downhole horizontal well is located between the surface vertical well and the roadway. 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 vertical shaft construction information includes the vertical shaft dip construction positions along the dip of the working face to be mined, and the arrangement of the vertical shaft dip construction 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 vertical well and the sidewall of the auxiliary haulage roadway is equal to half the width of the working face to be mined. If the lateral mining fracture range extends to the thick and hard roof of the working face to be mined, the distance between the shaft axis of the vertical well and the sidewall of the auxiliary haulage roadway is greater than half the width of the working face to be mined, so that the fracturing range of the vertical well and the lateral mining fracture range are arranged at intervals. 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. 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.

2. The method for combined surface vertical wells and downhole horizontal wells according to claim 1, characterized in that, The vertical well construction information also includes the vertical well direction construction location along the direction of the working face to be mined. The arrangement of the vertical well direction construction location is as follows: there are multiple surface vertical wells, and the multiple surface vertical wells are arranged along the direction of the working face to be mined.

3. 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 wells includes the estimated width of the fracturing network. The spacing between two adjacent surface vertical wells, 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) / 2 D is the distance between two adjacent vertical wells on the ground, 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.

4. The method for combining surface vertical wells and downhole horizontal wells according to claim 1, characterized in that, In step S2, obtaining the vertical well fracturing range includes: The fracture network expansion of the vertical well is monitored using ground microseismic monitoring to obtain the fracturing range of the vertical well.

5. The method for combined surface vertical wells and downhole horizontal wells according to any one of claims 1-4, characterized in that, The vertical well construction information includes the number of vertical well fracturing points. The vertical well fracturing points are grouped in pairs, and there are multiple groups of vertical well fracturing points. The multiple groups of vertical well fracturing points are arranged sequentially at intervals along the extension direction of the surface vertical well. The horizontal well construction information includes the number of horizontal well fracturing points. The horizontal well fracturing points are grouped in pairs, and there are multiple groups of horizontal well fracturing points. The multiple groups of horizontal well fracturing points are arranged sequentially at intervals along the extension direction of the horizontal well.

6. The method for combining surface vertical wells and downhole horizontal wells according to any one of claims 1-4, characterized in that, Step S1: Based on the fracturing operation information of surrounding mines, determine the estimated fracturing information for vertical wells and horizontal wells for the target mine, including: Based on the obtained vertical well fracturing construction information of surrounding mines, the estimated vertical well fracturing information for the target mine is determined, and based on the obtained horizontal well fracturing construction information of surrounding mines, the estimated horizontal well fracturing information for the target mine is determined.

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