Branch pore-forming method
By using a stepped drilling process to create multiple directional drilling points on the main hole, the problems of low efficiency and uneven slurry diffusion in traditional branch drilling are solved, thus achieving efficient branch drilling construction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- INNER MONGOLIA RESEARCH INSTITUTE CHINA UNIVERSITY OF MINING AND TECHNOLOGY (BEIJING)
- Filing Date
- 2025-12-23
- Publication Date
- 2026-04-10
AI Technical Summary
Traditional branch drilling methods are inefficient in shallow, narrow spaces, requiring frequent handling of drilling tools while waiting for the slurry to solidify, which leads to uneven slurry diffusion and a sudden increase in formation pressure, damaging the aquitard structure.
A stepped drilling process is adopted, in which the first inclined point is formed on the main hole and the second inclined point is formed. The steps are used as support points for branch drilling to avoid solidification and promote slurry dispersion.
It greatly shortens the drilling time, avoids uneven grout diffusion and damage to the waterproof layer, improves construction efficiency and reduces costs.
Smart Images
Figure CN121827693A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of drilling, in particular to a branch hole making method. BACKGROUND
[0002] The core feature of the short vertical distance short branch hole is accurate steering in a small space. Through the rigid bend joint guide unit and the guide wedge structure, a large angle is realized in the vertical limited space, and the problem that the traditional drilling tool cannot accurately operate in the narrow space of the shallow layer is solved. The branch hole making refers to the technology of drilling one or more branch holes from the basis of the main hole in the short vertical distance short branch directional drilling construction. This technology is usually used for grouting, exploration, construction or resource exploitation under complex geological conditions that require accurate operation, in order to improve the drilling efficiency, reduce the cost or meet the specific engineering needs, such as accurate plugging of grouting of coal seam roof water passage, thin coal seam gas development, etc. SUMMARY
[0003] Therefore, the purpose of the present application is to provide a branch hole making method.
[0004] In order to achieve the above purpose, the present application provides a branch hole making method, comprising: performing first drilling processing along a first direction on the surface layer of the mined area to obtain a main hole; the first direction is perpendicular to the plane where the surface layer is located; performing casing and well cementing processing on the main hole; performing second drilling processing along the first direction to a first build-up point at the end of the main hole, and performing first lateral branch drilling processing along a second direction at the first build-up point to obtain a first lateral branch hole; the second direction is inclined from the first direction to a third direction; the third direction is parallel to the plane where the surface layer is located; performing third drilling processing along the first direction to a second build-up point at the first build-up point; in the first direction, the second distance between the first build-up point and the second build-up point is not greater than the first distance between the end of the main hole and the first build-up point; in response to the build-up index of the second build-up point being greater than a build-up index threshold, performing second lateral branch drilling processing along a fourth direction at the second build-up point to obtain a second lateral branch hole; the fourth direction is inclined from the first direction to a fifth direction; the fifth direction is parallel to the plane where the surface layer is located and opposite to the third direction.
[0005] In some embodiments, in the first direction, the second distance between the first build-up point and the second build-up point is 0.95-1.05m.
[0006] In some embodiments, the build-up index of the second build-up point is greater than a build-up index threshold; the build-up index of the second build-up point is determined according to a coefficient of core rock, a core rate, an RQD value, and a drilling machine thrust force.
[0007] In some embodiments, the build-up index of the second build-up point is calculated by the formula ; wherein k is a coefficient of core rock, c is a core rate, RQD is an RQD value, and f is a drilling machine thrust force.
[0008] In some embodiments, the second distance between the main hole end and the first build-up point in the first direction is greater than 3 m.
[0009] In some embodiments, the deviation rate of the main hole is within 5 ‰.
[0010] In some embodiments, the second build-up point is located in a weathered bedrock aquifer; the weathered bedrock aquifer is located on one side of a Quaternary aquifer close to a coal seam.
[0011] In some embodiments, the method further comprises: in response to the build-up index of the second build-up point being less than or equal to a build-up index threshold, performing a fourth drilling process in the first direction to a third build-up point at the second build-up point; the third distance between the second build-up point and the third build-up point in the first direction is 0.95-1.05 m; in response to the build-up index of the third build-up point being greater than a build-up index threshold, performing a second lateral branch drilling process in the fourth direction at the third build-up point to obtain a second lateral branch hole; or in response to the build-up index of the third build-up point being less than or equal to a build-up index threshold, and the fourth distance between the first build-up point and the third build-up point in the first direction being a distance threshold, performing a hole sealing process on the first lateral branch hole.
[0012] In some embodiments, the method further comprises: sequentially performing hole sealing processes on the first lateral branch hole and the second lateral branch hole.
[0013] In some embodiments, the main hole is provided in a plurality, and the method further comprises: sequentially performing hole sealing processes on the lateral branch holes corresponding to the main holes in the third direction.
[0014] As can be seen from the above, the branch drilling method provided in this application involves drilling a first hole along a first direction in the surface layer of the mining area after mining to obtain a main hole; the first direction is perpendicular to the plane of the surface layer; casing and cementing are performed on the main hole; a second hole is drilled along the first direction at the end of the main hole to a first directional drilling point; at the first directional drilling point, a first lateral branch hole is drilled along a second direction to obtain a first lateral branch hole; the second direction is inclined from the first direction to a third direction; the third direction is parallel to the plane of the surface layer; a third hole is drilled along the first direction at the first directional drilling point to a second directional drilling point; in the first direction, the first directional drilling point and the... The second distance of the second directional drilling point is not greater than the first distance between the end of the main borehole and the first directional drilling point; in response to the directional drilling index of the second directional drilling point being greater than the directional drilling index threshold, a second lateral branch borehole is drilled at the second directional drilling point along the fourth direction to obtain a second lateral branch hole; the fourth direction is inclined from the first direction to the fifth direction; the fifth direction is parallel to the plane where the surface layer is located and opposite to the third direction. After forming the first directional drilling point on the main borehole, the second directional drilling point is formed downwards. This stepped drilling process can overcome the problem of stagnation in the first lateral branch hole at the first directional drilling point during the curing period, and the second lateral branch hole can be formed at the second directional drilling point without curing, thereby greatly shortening the drilling time. It can also avoid the problem of grout squeezing each other during grouting when the first lateral branch hole and the second lateral branch hole are on the same horizontal plane, resulting in uneven diffusion, some fractures not being fully filled, forming a "grout short circuit" phenomenon; and the sudden increase in local formation pressure, which induces the expansion of micro fractures and even destroys the already formed water-resistant layer structure. Attached Figure Description
[0015] To more clearly illustrate the technical solutions in this application or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0016] Figure 1 This is a flowchart of the branch hole-making method according to an embodiment of this application; Figure 2 This is another schematic flowchart of the branch hole-making method according to an embodiment of this application; Figure 3 This is a schematic diagram of the geological structure of the mining area; Figure 4a This is a schematic diagram of the structure of the first lateral branch borehole according to an embodiment of this application; Figure 4b This is a schematic diagram of the structure of the second lateral branch borehole according to an embodiment of this application; Figure 4c Another schematic view of a two-lateral branch borehole structure; Figure 5 A horizontal distribution projection schematic view of a branch borehole of the present application embodiment; Figure 6 A vertical distribution projection schematic view of a branch borehole of the present application embodiment. DETAILED DESCRIPTION
[0017] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application is further described in detail below with reference to specific embodiments and the accompanying drawings.
[0018] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present application embodiments should be understood as the common meanings understood by those with ordinary skills in the art to which the present application pertains. The terms "first", "second", and similar terms used in the present application embodiments do not represent any order, number, or importance, but are only used to distinguish different components. The terms "include", "contain", and similar terms mean that the elements or objects before the terms encompass the elements or objects listed after the terms and their equivalents, and do not exclude other elements or objects. The terms "connect" or "connected" and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms "upper", "lower", "left", "right", and the like only represent relative positional relationships, and when the absolute positions of the described objects change, the relative positional relationships can also change accordingly.
[0019] In short-span, short-branch drilling, short vertical distance typically refers to a vertical distance <10m, and short branch typically refers to a radius of curvature <6m. The slant angle is usually 13-17° / m. When drilling branch holes on the foundation of the main hole 21, a solid bottom surface and hole wall support are usually required. Therefore, in traditional branch drilling, one branch hole is often drilled first, and then grout is directly injected into the vertical section for curing. After the previous branch hole has solidified, the next branch hole is drilled, and this process is repeated several times. This method has several problems. One problem is the frequent handling of drilling tools. During the curing period, in order to improve the construction progress or reduce construction costs, drilling tools are usually moved to other areas that need drilling. Another problem is the need to wait for the previous branch hole to solidify before drilling the next branch hole, which usually requires a long waiting time. In addition, since another horizontal branch is constructed in the same aquifer after curing, during subsequent grouting, on the one hand, the grout from the two branches grouting at the same level may squeeze each other, resulting in uneven diffusion and some cracks not being fully filled, forming a "grout short circuit" phenomenon. On the other hand, grouting at the same level may cause a sudden increase in local formation pressure, inducing the propagation of microfractures and even destroying the existing aquitard structure. Therefore, when branching holes are opened on the basis of the main hole 21, there is often a problem of low efficiency in opening branching holes.
[0020] Based on this, the embodiments of this application provide a novel branch drilling process. After the main hole 21 and the previous branch hole (e.g., the left wing horizontal branch hole) are completed, a smaller diameter branch hole is drilled downwards about 1m in the main hole 21, forming a step between the branch hole and the main hole. This step is used as a support point for the next branch hole (e.g., the right wing horizontal branch hole), thus completing the next branch hole (e.g., the right wing horizontal branch hole). This overcomes the problem of the previous branch hole stalling during the curing period, greatly shortening the drilling time. It also promotes the anisotropic dispersion of grout in the three-dimensional injection layer, improving the grout's cohesion at the junctions. Therefore, it can reduce construction costs and achieve cost reduction and efficiency improvement.
[0021] refer to Figure 1 This is a flowchart illustrating a branching borehole creation method provided in an embodiment of this application. The branching borehole creation method may include: S100, a first borehole is drilled along the first direction Y in the surface layer of the mining area after mining to obtain a main hole 21; the first direction Y is perpendicular to the plane where the surface layer is located; S200, the main borehole 21 is subjected to casing installation and cementing. S300, at the end of the main hole 21, a second drilling process is performed along the first direction Y to the first slant point 221. At the first slant point 221, a first lateral branch drilling process is performed along the second direction R1 to obtain the first lateral branch hole 22. The second direction R1 is inclined from the first direction Y to the third direction X1. The third direction X1 is parallel to the plane where the surface layer is located. S400, a third drilling process is performed at the first slant point 221 along the first direction Y to the second slant point 231; in the first direction Y, the second distance between the first slant point 221 and the second slant point 231 is not greater than the first distance between the end of the main hole 21 and the first slant point 221. S500, in response to the inclination index of the second inclination point 231 being greater than the inclination index threshold, a second lateral branch borehole is drilled at the second inclination point 231 along the fourth direction R2 to obtain a second lateral branch hole 23; the fourth direction R2 is inclined from the first direction Y to the fifth direction X2; the fifth direction X2 is parallel to the plane where the surface layer is located and opposite to the third direction X1.
[0022] The branching borehole method provided in this application, which forms a step-like borehole process by creating a first inclined point 221 on the main borehole 21 and then continuing downwards to form a second inclined point 231, overcomes the problem of stagnation in the progress of the first lateral branch hole 22 at the first inclined point 221 during the curing period. It allows the formation of the second lateral branch hole 23 at the second inclined point 231 without the need for curing, thus greatly shortening the borehole time. It also avoids the uneven diffusion caused by the grout squeezing during grouting when the first lateral branch hole 22 and the second lateral branch hole 23 are on the same horizontal plane, resulting in some fractures not being fully filled and forming a "grout short circuit" phenomenon; and the sudden increase in local formation pressure, which can induce micro-fracture expansion and even damage the already formed aquitard structure.
[0023] In some embodiments, in step S100, reference Figure 2 As shown, before conducting the first borehole drilling, a geological survey can be carried out on the mined area. The coal seam 11 in the mined area typically includes a goaf 111. For example... Figure 3As shown, the stratum survey can include surveying and calculating the position, thickness, groundwater distribution, and main key layer position of Quaternary aquifer 15, weathered bedrock aquifer 14, bedrock aquifer 13, and water-conducting fractured zone 12 above coal seam 11 below the surface layer, to determine that water-conducting fractured zone 12 develops into weathered bedrock aquifer 14, and that there is a leakage recharge of Quaternary aquifer 15 to weathered bedrock aquifer 14. Weathered bedrock aquifer 14 is below Quaternary aquifer 15. A main hole 21 is drilled in the surface layer in a first direction Y (i.e., vertical direction) downward in the mining area. The drilling end position of main hole 21 can be in weathered bedrock aquifer 14 or bedrock aquifer 13.
[0024] In some embodiments, a drill bit of a first diameter can be used to drill main hole 21. The deviation rate of main hole 21 can be within 5‰. In this way, wear on the bench can be avoided. The inclination angle (a) and azimuth angle (b) of a point can be measured at intervals (e.g., 10 m or 30 m) from the surface layer orifice of main hole 21 to the build-up bench, and a calculation method such as the tangent method or the average angle method can be used to calculate the cumulative horizontal displacement of the build-up point relative to the orifice by segment superposition. The cumulative horizontal displacement is divided by the measured hole depth, and multiplied by 1000 to obtain the deviation rate at the hole depth of the end hole of main hole 21. For small inclination angles, the cumulative horizontal displacement is also divided by the measured hole depth, and multiplied by 1000 to obtain the deviation rate at the hole depth by the formula: horizontal displacement ≈ hole depth × sin (inclination angle). Generally, when the deviation rate of main hole 21 exceeds 5‰, re-drilling is required until the deviation rate of main hole 21 is within 5‰.
[0025] In some embodiments, in step S200, the casing and cementing process can include lowering a steel casing with a diameter smaller than that of main hole 21 into the stable bedrock section (e.g., weathered bedrock aquifer 14), and then grouting the cement slurry back to the orifice of main hole 21 and waiting for the casing to set. The cement can be a single liquid cement slurry, in which the mass ratio of water to cement can be 0.6:1. Early strength agent can also be included in the cement slurry, which can include 5‰ NaCl by weight of cement and 0.5‰ triethanolamine by weight of cement.
[0026] In some embodiments, in step S300, the end of main hole 21 can be drilled using a second diameter drill bit in the first direction Y, and then the second drilling process can be continued using a third diameter drill bit to the first build-up point 221. Generally, the second diameter can be smaller than the first diameter and smaller than the diameter of the casing (e.g., steel casing); the third diameter is smaller than the second diameter. As shown, the second diameter can be 200 mm, and the third diameter can be 150 mm. Figure 4aAs shown, the first lateral branch hole 22 can be a left wing horizontal branch hole.
[0027] In some embodiments, the first build-up point 221 can be located in the weathered bedrock aquifer 14 or in the bedrock aquifer 13.
[0028] In some embodiments, the second distance between the end of the main hole 21 and the first build-up point 221 in the first direction Y can be greater than 3m. That is, the vertical distance between the first build-up point 221 and the casing can be greater than 3m, for example, 3m, 5m, 7m or 10m, etc.
[0029] In some embodiments, when the first lateral branch drilling process is performed, a device with a rigid elbow guide unit and a whipstock can be used to perform the first lateral branch drilling process. It should be noted that the device and the specific lateral branch drilling method are prior art, and the embodiments of the present application do not involve improvements to the prior art.
[0030] In some embodiments, in step S400, a third drilling process can be performed at the end of the first build-up point 221 in the first direction Y using a third diameter drill to form a second build-up point 231. The first build-up point and the second build-up point 231 can form a step-like connection structure, as shown. Figure 4b The step-like connection structure can avoid drilling a second lateral branch hole 23' before grouting the first lateral branch hole 22 (for example Figure 4c) causes the guide to be located in the first lateral branch hole 22, and the hole wall is not under stress, so the problem of hole making in the second lateral branch hole 23' cannot be solved. In the first direction Y, the second distance (i.e., the vertical distance d / the height of the step-like connection structure) between the first kick-off point 221 and the second kick-off point 231 is 0.95-1.05 m. For example, it can be 0.95 m, 0.97 m, 0.99 m, 1 m, 1.01 m, 1.03 m, and 1.05 m, etc. That is, the vertical distance d between the first kick-off point 221 and the second kick-off point 231 can be 0.95-1.05 m. The second distance of this value is an engineering preferred value set by comprehensively considering the stability of the rock mass, the construction efficiency, and the quality control accuracy. The second distance of this value can meet the mechanical stability requirements of the step-like connection structure. By a height of about 1 m, an effective "shoulder" can be formed in the rock mass, which can provide sufficient contact area to resist the large torque and advancing force when the drill bit drills in the fourth direction R2, prevent the drill tool from slipping or the step-like connection structure from being worn out and collapsed, and also will not increase unnecessary drilling workload due to excessive height, thereby providing a large and stable mechanical support point for subsequent lateral drilling (i.e., performing second lateral branch hole drilling treatment along the fourth direction R2 at the second kick-off point 231).
[0031] In some embodiments, the second kick-off point 231 can be located in the weathered bedrock aquifer 14, and the weathered bedrock aquifer 14 is located on one side of the Quaternary aquifer 15 close to the coal seam 11. The second lateral branch hole 23 can be a right wing lateral branch hole.
[0032] In some embodiments, in step S500, it can be determined whether the second kick-off point 231 meets the requirements and whether the second lateral branch hole drilling treatment can be performed at the second kick-off point 231 to obtain the second lateral branch hole 23 according to the kick-off index. The kick-off index of the second kick-off point 231 can be obtained according to the coefficient of the core rock, the core rate, the RQD value, and the drill push force, etc. When the kick-off index of the second kick-off point 231 is greater than the kick-off index threshold, it is determined that it meets the requirements, and the second lateral branch hole drilling treatment can be performed at the second kick-off point 231 to obtain the second lateral branch hole 23, as shown in FIG. 5B. When the kick-off index of the second kick-off point 231 is not greater than (i.e., less than or equal to) the kick-off index threshold, it is determined that it does not meet the requirements, and the drilling can be continued downward at the second kick-off point 231 that does not meet the requirements to find a new second kick-off point (e.g., a third kick-off point or a fourth kick-off point) that meets the requirements to perform the second lateral branch hole drilling treatment to obtain the second lateral branch hole 23. Figure 4b
[0033] In some embodiments, the second lateral branch drilling process can be performed by using a device with a rigid bend guiding unit and a guide wedge. It should be noted that the device and the specific lateral branch drilling method are prior art, and the embodiments of the present application do not involve improvements to the prior art.
[0034] In some embodiments, the threshold of the build-up index can be obtained according to theoretical simulation and calculation, or obtained according to field test and statistics. Specifically, the threshold of the build-up index obtained according to theoretical simulation and calculation can include: according to the mechanical properties of the drilling assembly (such as drill bit type, drill pipe stiffness), the expected build-up rate (such as 13-17° / m), and the average mechanical properties of the regional stratum (such as rock compressive strength, internal friction angle), the drilling mechanics model or finite element software is used for simulation calculation, and the required minimum lateral support force (i.e. contact reaction force) is back calculated. The minimum lateral support force has corresponding parameters of core lithology corresponding coefficient, coring rate, RQD value and drilling machine thrust force in the simulation calculation, and the threshold of the build-up index can be obtained through the parameters. Specifically, the threshold of the build-up index obtained according to field test and statistics can include: in the typical stratum of the target mining area, a plurality of different coring points are preselected for trial sidetracking. Record the lithology coefficient (k), coring rate (c), RQD value, thrust force (f) of each point, and calculate the DI value. At the same time, the actual effect of subsequent sidetracking at the point (such as build-up success rate, build-up rate, step wear condition) is observed. Then compare the DI value range of the successfully built-up points with the failed points, and an empirical threshold range of the build-up index can be obtained.
[0035] In some embodiments, in the process of continuing drilling downward at the second non-compliant build-up point 231 to find a new compliant build-up point, the new compliant second build-up point 231 can be found in units of 0.95-1.05 m and with the condition that the distance between the new build-up point and the first build-up point 221 is within the distance threshold. It can be understood that if the second build-up index is less than the build-up index threshold, the drilling continues downward in units of 0.95-1.05 m, and it is determined whether the build-up index of the new build-up point meets the requirements. If it still does not meet the requirements when the distance threshold (which can be determined according to the actual situation of the stratum) is exceeded, the first lateral branch borehole is subjected to sealing treatment. That is, the method further comprises: in response to the build-up index of the second build-up point 231 being less than or equal to the build-up index threshold, performing fourth drilling treatment in the first direction Y to a third build-up point at the second build-up point 231; in the first direction Y, a third distance between the second build-up point 231 and the third build-up point is 0.95-1.05 m; in response to the build-up index of the third build-up point being greater than the build-up index threshold, performing second lateral branch drilling treatment in the fourth direction R2 at the third build-up point to obtain a second lateral branch borehole 23; or in response to the build-up index of the third build-up point being less than or equal to the build-up index threshold, and in the first direction Y, a fourth distance between the first build-up point 221 and the third build-up point is a distance threshold, the first lateral branch borehole 22 is subjected to sealing treatment.
[0036] In some embodiments, the method can further comprise: in response to the build-up index of the third build-up point being less than or equal to the build-up index threshold, performing fifth drilling treatment in the first direction Y to a fourth build-up point at the third build-up point; in the first direction Y, a distance between the third build-up point and the fourth build-up point can be 0.95-1.05 m; in response to the build-up index of the fourth build-up point being greater than the build-up index threshold, performing second lateral branch drilling treatment in the fourth direction R2 at the fourth build-up point to obtain a second lateral branch borehole 23; or in response to the build-up index of the fourth build-up point being less than or equal to the build-up index threshold, and in the first direction Y, a fifth distance between the first build-up point 221 and the fourth build-up point is a distance threshold, the first lateral branch borehole 22 is subjected to sealing treatment.
[0037] In some embodiments, the distance threshold can be determined according to actual conditions, for example, based on stratum homogeneity and in-hole safety. Exemplarily, the distance threshold can be about 3m, but in implementation, it can be dynamically adjusted. The stratum homogeneity evaluation can include: if it is judged according to geological prospecting data and drilled cores that the current stratum is a thick and uniform weak fracture zone (such as thick mudstone, fault fracture zone), and it is predicted that the lithology will not be significantly improved in a short time, even if only 2m is drilled and a qualified point is not found, the hole can be sealed in advance, because it is meaningless and high-risk to continue drilling. If the stratum is an alternating layer (such as thin sandstone, mudstone interbed), drilling 3m of the drilling distance can have passed through multiple lithology layers, and if a qualified point is still not found, it means that the whole region of the vertical section does not meet the deflecting condition, and the first lateral branch hole 22 needs to be sealed. The in-hole safety risk control can include: if abnormal slurry return, large torque, and jumping drilling and other in-hole complex conditions are found during drilling, even if 3m is not reached, it should be terminated in advance, and the first lateral branch hole 22 is sealed to ensure safety. Avoid long-term blind drilling in broken strata, causing well wall collapse, blockage, and other accidents. In addition, if the drilling depth is large and the well deviation has exceeded the standard (deviation rate > 5‰), it should also be terminated in advance, and the first lateral branch hole 22 is sealed. Avoid further drilling down to aggravate the hole deviation, and subsequent deflecting difficulty.
[0038] In some embodiments, the horizontal distribution projection of the sorted grouting hole can be as shown in Figure 5 The vertical distribution projection of the sorted grouting hole can be as shown in Figure 6 After the drilling is completed, the first lateral branch hole 22 and the second lateral branch hole 23 can be sequentially sealed. Among them, after the first lateral branch hole 22 starts grouting, the second lateral branch hole 23 is grouted. For multiple adjacent main holes 21, the first lateral branch hole 22 and the second lateral branch hole 23 corresponding to the main hole 21 close to the center of the goaf 111 are selected to start grouting. That is, the facing hole is drilled first and the sequence is grouted, and the outside hole is drilled later and the sequence is grouted.
[0039] The branch hole forming method provided by the embodiments of the present application can overcome the problem of stagnation of progress during the setting of the first lateral branch hole 22 at the first build-up point 221, and the second lateral branch hole 23 can be formed at the second build-up point 231 without setting, so as to greatly shorten the hole forming time. The phenomenon of "slurry short circuit" can be avoided, in which the slurry of the first lateral branch hole 22 and the second lateral branch hole 23 extrude each other when they are at the same level, causing uneven diffusion, partial fractures not being filled sufficiently, and local formation of the water-resisting layer structure. In addition, after the second lateral branch hole 23 is completed, grouting is performed according to the sequence of hole forming, which can further promote the dispersion of the slurry in three-dimensional injection layers in all directions, and improve the healing degree of the slurry at the intersection. The time cost can be greatly reduced, the construction cost can be reduced, and the cost reduction and benefit increase can be realized.
[0040] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to suggest that the scope of the disclosure (including the claims) is limited to these examples; under the idea of the present disclosure, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the embodiments of the present disclosure as described above, which are not provided in details for the sake of brevity.
[0041] Although the present disclosure has been described in conjunction with the specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description.
[0042] The embodiments of the present disclosure are intended to cover all such alternatives, modifications and variations as falling within the broad scope of the appended claims. Accordingly, any omission, modification, equivalent replacement, improvement, etc. made in the spirit and principle of the embodiments of the present disclosure shall be included in the protection scope of the present disclosure.
Claims
1. A method for creating branched holes, characterized in that, include: The first borehole is drilled along the first direction in the surface layer of the mining area after mining to obtain the main borehole; The first direction is perpendicular to the plane containing the Earth's surface layer; The main borehole is then casing and cemented. At the end of the main borehole, a second borehole is drilled along the first direction to the first deflection point. At the first deflection point, a first lateral branch borehole is drilled along the second direction to obtain a first lateral branch hole. The second direction is inclined from the first direction to a third direction. The third direction is parallel to the plane where the surface layer is located. A third borehole is drilled along the first direction from the first directional drilling point to the second directional drilling point; in the first direction, the second distance between the first directional drilling point and the second directional drilling point is not greater than the first distance between the end of the main hole and the first directional drilling point; In response to the inclination index of the second inclination point being greater than the inclination index threshold, a second lateral branch borehole is drilled at the second inclination point along the fourth direction to obtain a second lateral branch hole; the fourth direction is inclined from the first direction to the fifth direction; the fifth direction is parallel to the plane where the surface layer is located and opposite to the third direction.
2. The branching hole-making method according to claim 1, characterized in that, In the first direction, the second distance between the first inclination point and the second inclination point is 0.95-1.05m.
3. The branching hole-making method according to claim 1, characterized in that, The build-up index of the second build-up point is greater than the build-up index threshold; the build-up index of the second build-up point is obtained based on the coefficient of the core lithology, the core sampling rate, the RQD value, and the drilling rig thrust.
4. The branching hole-making method according to claim 3, characterized in that, The inclination index of the second inclination point is expressed by the formula Calculate; where k is the coring lithology correspondence coefficient, c is the coring rate, RQD is the RQD value, and f is the drilling rig propulsion force.
5. The branching hole-making method according to claim 1, characterized in that, In the first direction, the second distance between the end of the main hole and the first inclined point is greater than 3m.
6. The branching hole-making method according to claim 1, characterized in that, The deviation rate of the main hole is within 5‰.
7. The branching hole-making method according to claim 1, characterized in that, The second inclination point is located within a weathered bedrock aquifer; the weathered bedrock aquifer is located on the side of the Quaternary aquifer near the coal seam.
8. The branching hole-making method according to claim 1, characterized in that, The method further includes: in response to the inclination index of the second inclination point being less than or equal to the inclination index threshold, performing a fourth drilling process along the first direction at the second inclination point to a third inclination point; in the first direction, the third distance between the second inclination point and the third inclination point is 0.95-1.05m; If the directional index of the third directional drilling point is greater than the directional index threshold, a second lateral branch drilling process is performed at the third directional drilling point along the fourth direction to obtain a second lateral branch hole; or if the directional index of the third directional drilling point is less than or equal to the directional index threshold, and the fourth distance between the first directional drilling point and the third directional drilling point in the first direction is a distance threshold, then the first lateral branch hole is sealed.
9. The branching hole-making method according to claim 1, characterized in that, The method further includes: sequentially sealing the first lateral branch hole and the second lateral branch hole.
10. The branching hole-making method according to claim 1, characterized in that, The method further includes: sealing the lateral branch holes corresponding to the main holes in sequence according to the third direction.