Secondary shaft formation construction method based on raise boring process

Abstract

A secondary shaft formation construction method based on a raise boring process. A directional drilling rig (3), a composite drill pipe (5) and a directional drill bit (4) are used for drilling a directional borehole (8), and after the directional borehole (8) is drilled, the composite drill pipe (5) is tripped out, a deviation of the directional borehole (8) is measured, and a raise boring machine (9) is installed; a small raise boring pipe (10) and a reamer bit (11) are connected, and the reamer bit (11) drills along the directional borehole (8) for secondary reaming to form a pilot hole (12); then, the reamer bit (11) is replaced with a small raise boring bit (13), and the small raise boring pipe (10) is tripped out to drive the small raise boring bit (13) to excavate along the pilot hole (12) to form a guide shaft (14); the small raise boring pipe (10) and the small raise boring bit (13) are removed, a large raise boring pipe (15) is tripped into the guide shaft (14) downwardly along a design direction of a vertical / inclined shaft (17), a large raise boring bit (16) is connected, and the raise boring machine (9) drives and lifts the large raise boring bit (16) to excavate along the guide shaft (14) to form a shaft. On the basis of first excavating the guide shaft (14) using the raise boring machine (9), a secondary reaming technology is implemented, so that the influence of a deviation of the directional borehole (8) on shaft formation is effectively eliminated.

Description

Secondary well construction method based on reverse drilling technology Technical Field

[0001] The present invention relates to the technical field of vertical and inclined shaft excavation, and in particular to a secondary well construction method based on a reverse drilling process, which is applicable to pumped storage power stations, conventional hydropower stations or other underground vertical shaft excavation projects. Background Art

[0002] At present, the construction of vertical (inclined) wells in hydropower stations mainly adopts the drilling and blasting method with manual operation. This drilling and blasting method not only generates a lot of noise and dust during the drilling and blasting process, but also the expansion blasting is usually unable to use mechanical drainage and slag removal due to the limitation of working space. It can only be carried out by manual methods, and the efficiency of manual operation is low, which cannot meet the requirements of the construction period. In addition, the surrounding rock structure is easily damaged after blasting, bringing the risk of surrounding rock collapse. In addition, the choice of manual drainage and slag removal is prone to cause safety accidents.

[0003] Raise boring technology has also been used for vertical (or oblique) construction. However, when constructing a vertical shaft using this technology, a raise drill bit is often used to excavate a pilot shaft, creating a slag well. This slag well is then used for manual drilling and blasting to expand the excavation. While this simplifies the construction process, the majority of the work still occurs in manual excavation, which also carries the risk of surrounding rock collapse.

[0004] Some projects have also applied raise boring rigs to the technology of single-stage well completion. The basic process involves directly expanding the well from a pilot hole in a single operation. This method places extremely high demands on the pilot hole's deflection rate, which directly affects the quality of the shaft's formation. If the pilot hole deflects, correction work is required. This correction usually involves withdrawing the rods, grouting, and re-drilling, which increases the project workload. Moreover, excessively deflected shafts cannot be lined, requiring secondary construction correction using manual blasting. These conditions can seriously affect construction efficiency, significantly limiting the application scope of single-stage well completion technology.

[0005] CN104196442A discloses a method for using a raise boring rig in vertical or inclined shaft construction. The method involves drilling a pilot hole downward along the shaft axis in the horizontal excavation area above the upper bend. After the pilot hole is formed, the drill bit is replaced with an excavation cutterhead in the lower bend. The slag guide shaft is then formed by reverse excavation from bottom to top. Although this method utilizes a combined pilot hole and raise boring method, the problem of guide hole deflection still exists during the construction process, making it impossible to prevent subsequent slag guide shaft deflection during construction.

[0006] CN111441718A discloses a high-precision pilot shaft excavation construction method, system, and application for large-section, steep-slope, and long inclined shafts. The method involves first excavating the upper and lower horizontal tunnels using the drill-and-blast method, constructing pilot holes in the upper and lower tunnels, then enlarging the pilot holes. A raise boring rig is then used to drill forward, and finally, the expansion drill bit is replaced at the bottom, followed by reverse drilling to form the pilot shaft. Although multiple drilling passes are employed, the first pass of the raise boring rig directly forwards the original pilot hole, while the second pass uses the same raise boring rig and drill pipe as the first. This approach does not truly address the problem of pilot shaft deviation, which can lead to subsequent deviation in the vertical shaft.

[0007] Summary of the Invention

[0008] In order to solve the above problems, the present invention provides a secondary well construction method based on the raise drilling process. This method performs a second expansion construction on the basis of the pilot well dug by the raise drilling rig in the first time, effectively eliminating the influence of the deviation of the pilot hole on the well construction, and avoiding the need for manual blasting to correct the deviation after the traditional method of expanding the hole; it improves construction efficiency and safety, improves the degree of automation of the expansion construction, and effectively prevents the occurrence of safety accidents.

[0009] In order to achieve the above technical features, the purpose of the present invention is achieved as follows: a secondary well construction method based on a reverse drilling process comprises the following steps:

[0010] Step 1, directional drilling construction:

[0011] A tunnel is pre-excavated in the underground rock mass, and a directional drilling rig is arranged and installed on the ground corresponding to the tunnel. A composite drill rod and a directional drill bit are installed on the directional drilling rig. The rig drills into the stratum along the designed direction of the vertical / inclined well and penetrates the stratum. The directional drilling is completed by connecting the tunnel, and then the composite drill rod is withdrawn.

[0012] Step 2, deviation measurement of directional drilling:

[0013] Measure the maximum deviation distance δ between the axis of the directional drilling hole and the designed center axis of the vertical / inclined well;

[0014] Step 3, construction of pilot hole:

[0015] Dismantle the directional drilling rig and install the raise drilling rig, connect the small raise drilling rod and the reaming drill bit, drill the reaming drill bit from top to bottom along the directional drilling direction, perform secondary brushing to form a pilot hole, and ensure that the small raise drilling rod does not retreat;

[0016] Step 4, construction of pilot well:

[0017] Select a small raise drill bit with a radius of r, where r>δ, remove the reaming drill bit and replace it with the small raise drill bit at the end of the small raise drill rod. Retract the small raise drill rod to drive the small raise drill bit to excavate the formation in the reverse direction, and excavate the pilot well in the direction of the pilot hole.

[0018] Step 5, construction of vertical / inclined shafts:

[0019] Remove the small raise drill bit and small raise drill rod, lower the large raise drill rod to the tunnel along the designed direction of the vertical / inclined well, and install the large raise drill bit on the head of the large raise drill rod. Retract the large raise drill rod through the raise drilling rig, drive the large raise drill bit to reversely excavate the stratum along the designed central axis of the vertical / inclined well, and form a vertical / inclined well in one go in line with the designed excavation line of the vertical / inclined well.

[0020] Preferably, before the directional drilling rig is arranged and installed in step 1, concrete is first poured on the ground to form a foundation platform, and then the directional drilling rig is fixed to the foundation platform using anchor bolts, and then all the anchor bolts are completely covered with concrete.

[0021] Preferably, the composite drill rod in step 1 includes multiple directional drill rods and stable drill rods; during drilling, the directional drill rod is installed on the directional drilling rig, the directional drill bit is installed on the head of the directional drill rod, and then the stable drill rod is connected to the tail end of the directional drill bit to form a composite drill rod, and the directional drilling rig is started to drive the composite drill rod to drill into the formation from top to bottom.

[0022] Preferably, when the composite drill rod continues to drill, when the length of the composite drill rod is insufficient, the corresponding directional drill rod and the stable drill rod are fixedly connected to the tail end of the composite drill rod to form a new composite drill rod, and the formation is continued to be drilled in a top-down direction. The directional drill rod and the stable drill rod are repeatedly connected alternately until a directional drill hole connected to the tunnel is obtained, the composite drill rod is withdrawn, and the directional drilling rig is dismantled.

[0023] Preferably, during the downward drilling process of the directional drill rod, a certain deflection will occur at the connection point of the directional drill rod, and the directional drill rod will undergo bending stress deformation due to the influence of pressure. The deflection at the connection point of the directional drill rod and the bending stress deformation of the directional drill rod itself are superimposed, causing the entire directional drill rod to deviate from the central axis of the vertical / inclined well design and form a spiral downward directional drilling.

[0024] Preferably, the diameter of the directional drilling hole can ensure that the directional drilling rod can move freely up and down inside it, but the diameter is smaller than that of a small reverse well drilling rod; the central axis of the directional drilling hole is spiral and has a certain deviation rate relative to the central axis of the vertical / inclined well design.

[0025] Preferably, the center axis of the pilot well in step 4 is basically coincident with the center axis of the pilot hole, forming a spiral shape, and there is also a certain inclination relative to the center axis of the vertical / inclined well design. However, it is ensured that the radius r of the pilot well is greater than the deviation of the pilot hole, so that the large reverse well drilling rod can be straightly lowered along the center axis of the vertical / inclined well design to the bottom of the tunnel.

[0026] Preferably, the diameter of the large-scale raise well drill rod is larger than the diameter of the small-scale raise well drill rod, and can drive the large-scale raise well drill bit to reversely excavate the stratum from bottom to top.

[0027] Preferably, the large-scale raise well drill bit has a diameter greater than 4 m and can be installed at the end of a large-scale raise well drill rod, and excavates the stratum to form a vertical / inclined well as the large-scale raise well drill rod rises.

[0028] Preferably, the central axis of the vertical / inclined well is substantially coincident with the designed central axis of the vertical / inclined well, and the deflection rate is close to 0.

[0029] Preferably, the diameter of the reaming drill bit in step 3 is between 250 mm and 600 mm.

[0030] Preferably, after the vertical / inclined shaft is formed in step 5, a single hook lifting system is equipped to lower materials and personnel, and the wall is built with integral metal formwork, and concrete is lowered through seamless steel pipes to cast the shaft wall.

[0031] Preferably, the reaming process is a process of breaking a large amount of rock. It is necessary to determine the model of the reaming drill bit and the arrangement of the rock breaking cutters according to the formation rock conditions, and formulate corresponding drilling parameters to achieve the purpose of drilling with the highest efficiency.

[0032] Preferably, the diameter of the large raise drill pipe is selected to ensure that it will not be interfered with by the inner wall of the pilot well during the lowering process inside the pilot well, so that the axis of the large raise drill pipe coincides with the designed center axis of the vertical / inclined well.

[0033] The present invention has the following beneficial effects:

[0034] 1. The construction method of the present invention is used to first excavate a pilot hole using a directional drill and a pilot drill bit. Then, the pilot drill bit is replaced with a small raise drill bit to reversely excavate the stratum to form a pilot well. Finally, a large raise drill rod is placed in the pilot well to ensure that the axis of the large raise drill rod is completely aligned with the designed axis of the vertical / inclined well. Then, a large raise drill bit is used to reversely excavate the stratum a second time to form a vertical shaft. On the one hand, the degree of automation of the hole expansion construction is improved, truly achieving "zero blasting", improving construction efficiency, and effectively preventing the occurrence of safety accidents. On the other hand, the use of the raise drill process to expand and excavate the vertical shaft twice can effectively eliminate the influence of the pilot hole deviation on the vertical shaft to the greatest extent, avoiding the correction methods such as rod withdrawal, grouting, and re-drilling during directional drilling, and solving the problem of manual blasting correction after the raise drill process has been used to expand and excavate the well once, thereby improving construction efficiency.

[0035] 2. In the present invention, by selecting a stable drill rod in combination with a directional drill rod, the accuracy of the constructed directional drilling hole can be guaranteed as much as possible, and the deviation between the directional drilling hole and the designed center axis of the vertical / inclined well can be reduced as much as possible.

[0036] 3. In the present invention, in order to solve the problem of deviation, the subsequent pilot hole, pilot well and secondary reverse well construction process is adopted to overcome the influence of the initial deviation, thereby ensuring the one-time formation of the final vertical / inclined well.

[0037] 4. In this application, by selecting the size of the radius r and the maximum deviation distance δ, it is ensured that the pilot well formed can be drilled along the designed center axis of the vertical / inclined well, so that the size of the pilot well can cover the designed center axis of the vertical / inclined well, thereby exposing the designed center axis of the vertical / inclined well, providing a construction basis for subsequent secondary back-excavation. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The present invention will be further described below with reference to the accompanying drawings and examples.

[0039] FIG1 is a construction flow chart of the present invention.

[0040] FIG2 is a construction diagram of directional drilling according to the present invention.

[0041] FIG3 is a partial enlarged view of A in FIG2 of the present invention.

[0042] FIG4 is a schematic diagram of the construction of the pilot hole of the present invention.

[0043] FIG5 is a partial enlarged view of B in FIG4 of the present invention.

[0044] FIG6 is a schematic diagram of the construction of the pilot well of the present invention.

[0045] FIG7 is a partial enlarged view of C in FIG6 of the present invention.

[0046] FIG8 is a schematic diagram of the construction of a vertical / inclined shaft according to the present invention.

[0047] In the figure: 1-tunnel, 2-foundation platform, 3-directional drilling rig, 4-directional drill bit, 5-composite drill pipe, 6-vertical / inclined well design center axis, 7-vertical / inclined well design excavation line, 8-directional drilling hole, 9-raise drilling rig, 10-small raise drilling pipe, 11-reaming drill bit, 12-pilot hole, 13-small raise drilling bit, 14-pilot well, 15-large raise drilling pipe, 16-large raise drilling bit, 17-vertical / inclined well. DETAILED DESCRIPTION

[0048] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0049] Example 1:

[0050] Referring to FIG1-8 , the secondary well construction method based on the raise boring process includes the following steps:

[0051] Step 1, construction of directional drilling 8:

[0052] A tunnel 1 is pre-excavated in the underground rock mass, a directional drilling rig 3 is arranged and installed on the ground corresponding to the tunnel 1, a composite drill rod 5 and a directional drill bit 4 are installed on the directional drilling rig 3, and the stratum is drilled into and penetrated along the designed direction of the vertical / inclined well, and the directional drilling 8 is completed by connecting the tunnel 1, and then the composite drill rod 5 is withdrawn;

[0053] Furthermore, preferably, to ensure the installation stability of the directional drilling rig 3 and to ensure the normal subsequent drilling operation, before the directional drilling rig 3 is arranged and installed, concrete is first poured on the ground to form a foundation platform 2, and then the directional drilling rig 3 is fixed to the foundation platform 2 using anchor bolts. After that, all anchor bolts are completely covered with concrete. The above structure ensures the reliability of the fixing of the directional drilling rig 3.

[0054] Furthermore, due to the relatively complex rock structure of the formation, the directional drill bit 4 inevitably deviates during drilling. To minimize the drilling deviation of the directional drill bit 4, the composite drill rod 5 includes multiple directional drill rods and a stabilizer drill rod. During drilling, the directional drill rods are mounted on the directional drilling rig 3, the directional drill bit 4 is mounted on the head of the directional drill rods, and the stabilizer drill rods are connected to the tail end of the directional drill bit 4 to form the composite drill rod 5. The directional drilling rig 3 is then started to drive the composite drill rod 5 to drill the formation from top to bottom. The stabilizer drill rods, in combination with the directional drill rods, can ensure the accuracy of the constructed directional borehole 8 as much as possible, minimizing its deviation from the designed center axis 6 of the vertical / inclined well.

[0055] Preferably, when the composite drill rod 5 becomes insufficient in length during continued drilling, a corresponding directional drill rod and a stabilizer drill rod are fixedly connected to the tail end of the composite drill rod 5 to form a new composite drill rod, and drilling into the formation continues in a top-down direction. The directional drill rod and the stabilizer drill rod are repeatedly connected alternately until a directional borehole 8 connected to the tunnel 1 is obtained. The composite drill rod 5 is then withdrawn and the directional drilling rig 3 is removed. This extension of the composite drill rod 5 enables the construction of vertical / inclined wells of greater length, effectively enhancing its adaptability.

[0056] Further preferably, during the downward drilling process of the directional drill pipe, a certain degree of deflection will occur at the connection point of the directional drill pipe, and the directional drill pipe will be affected by pressure and deformed by bending stress. The deflection at the connection point of the directional drill pipe and the bending stress deformation of the directional drill pipe itself are superimposed, causing the entire directional drill pipe to deviate from the design axis 6 of the vertical / inclined well to form a spiral downward directional drill hole 8. Among them, it is precisely because the deflection of the directional drill hole 8 is unavoidable and cannot be overcome fundamentally, so the use of traditional construction methods will cause the subsequent vertical / inclined well to be deflected, and thus fail to meet the design requirements, resulting in the problem of waste holes. Based on this, in the present invention, in order to solve the deflection problem, the subsequent pilot hole, pilot well and secondary reverse well construction process is adopted to overcome the influence of the initial deviation, thereby ensuring the one-time formation of the final vertical / inclined well 17.

[0057] Step 2: Deviation measurement of directional drilling hole 8:

[0058] Measure the maximum deviation distance δ between the axis of the directional drilling hole 8 and the vertical / inclined well design axis 6;

[0059] The deviation distance δ is an inevitable deviation of the directional drilling 8. If the deviation distance δ is to be kept small, a lot of time and economic costs will be consumed. However, as long as a small raise drill bit with a radius r>δ is selected and a secondary raise drilling is performed to complete the well, the impact of the directional drilling deviation can be avoided.

[0060] Further preferably, the diameter of the directional drilling hole 8 can ensure that the directional drilling rod can move freely up and down inside it, but the diameter is smaller than the diameter of the small-scale raise drilling rod 10; the central axis of the directional drilling hole 8 is spiral, and has a certain deflection rate relative to the central axis 6 of the vertical / inclined well design;

[0061] Among them, the measurement of the deviation distance δ of the directional drilling 8 is mainly for the purpose of facilitating the subsequent selection of the size of the small well raising drill bit 13, thereby ensuring that during the subsequent construction process using the small well raising drill bit 13, the pilot hole 12 can be formed at one time by the small well raising drill bit 13 to complete the exposure of the vertical / inclined well design center axis 6, so as to facilitate the subsequent arrangement and installation of the small well raising drill rod 10.

[0062] Step 3, construction of pilot hole 12:

[0063] Remove the directional drill 3 and install the raise drill 9, connect the small raise drill rod 10 and the reaming drill bit 11, drill the reaming drill bit 11 from top to bottom along the direction of the directional drilling 8, perform secondary brushing to form the pilot hole 12, and ensure that the small raise drill rod 10 does not retreat;

[0064] Since the pilot hole 12 is mainly drilled with reference to the direction of the directional drilling hole 8, a spiral shape will inevitably be formed during the drilling process of the pilot hole 12, and there will be certain deviations. However, this pilot hole 12 mainly provides a basis for the construction of the subsequent pilot well 14. Although it is consistent with the directional drilling hole 8 and there are still deviations, it will not affect the subsequent reverse well construction process. Based on this, the deviation here does not require additional processing during the specific construction process.

[0065] Step 4, construction of pilot well 14:

[0066] A small raise drill bit 13 with a radius of r is selected, where r>δ is ensured. The reaming drill bit 11 is removed and replaced with the small raise drill bit 13 at the end of the small raise drill rod 10. The small raise drill rod 10 is retracted to drive the small raise drill bit 13 to excavate the formation in the reverse direction, and a pilot well 14 is excavated in the direction of the pilot hole 12.

[0067] Further preferably, in step 4, the central axis of the pilot well 14 is substantially coincident with the central axis of the pilot hole 12, forming a spiral shape, and also having a certain deflection relative to the designed central axis of the vertical / inclined well. However, the radius r of the pilot well 14 is ensured to be greater than the deviation of the pilot hole 12, so that the large raise drill rod 15 can be lowered straight down along the designed central axis 6 of the vertical / inclined well to the bottom of the tunnel 1;

[0068] Based on this, in this application, by selecting the size of the radius r and the maximum deviation distance δ, it is ensured that the formed guide shaft 14 can be drilled out along the vertical / inclined shaft design center axis 6, so that the size of the guide shaft 14 can cover the vertical / inclined shaft design center axis 6, and then expose the vertical / inclined shaft design center axis 6, providing a construction basis for subsequent secondary back-excavation.

[0069] Step 5, construction of vertical / inclined shaft 17:

[0070] The small raise drill bit 13 and the small raise drill rod 10 are removed, and the large raise drill rod 15 is lowered to the tunnel 1 along the vertical / inclined well design direction, and the large raise drill bit 16 is installed on the head of the large raise drill rod 15. The large raise drill rod 15 is retracted by the raise drill rig 9, and the large raise drill bit 16 is driven to reversely excavate the stratum along the vertical / inclined well design center axis 6, and form a vertical / inclined well 17 in one go in line with the vertical / inclined well design excavation line 7.

[0071] Further preferably, the diameter of the large raise drill rod 15 is larger than the diameter of the small raise drill rod 10, and can drive the large raise drill bit 16 to reversely excavate the stratum from bottom to top.

[0072] Further preferably, the large raise well drill bit 16 has a diameter greater than 4 m and can be installed at the end of the large raise well drill rod 15 , so as to excavate the stratum to form a vertical / inclined well 17 as the large raise well drill rod 15 rises.

[0073] Further preferably, the central axis of the vertical / inclined shaft 17 substantially coincides with the designed central axis 6 of the vertical / inclined shaft, and the deflection rate is close to 0.

[0074] Further preferably, the diameter of the reaming drill bit 11 in step 3 is between 250 mm and 600 mm.

[0075] More preferably, after the vertical / inclined shaft 17 is formed in step 5, a single-hook lifting system is provided to lower materials and personnel, with integral metal formwork used to build the wall, and seamless steel pipes lowered to lower concrete and cast the shaft wall. This arrangement can effectively support the formed vertical / inclined shaft 17.

[0076] Furthermore, the reaming process involves extensive rock fragmentation, and the type of reaming drill bit and the arrangement of the rock-breaking cutters must be determined based on the rock formation conditions, along with appropriate drilling parameters, to achieve maximum drilling efficiency. The aforementioned drill bit selection enhances adaptability, ensuring compatibility with diverse rock formations.

[0077] Preferably, the diameter of the large raise drill rod 15 is selected to ensure that it is not interfered with by the inner wall of the pilot well 14 during lowering into the pilot well 14, so that the axis of the large raise drill rod 15 coincides with the designed center axis 6 of the vertical / inclined well. This dimensioning ensures that during the final raise well construction, the resulting vertical / inclined well 17 precisely aligns with the designed center axis 6 of the vertical / inclined well, ensuring accurate construction and effectively overcoming the effects of deviations from the original directional drilling 8.

[0078] Example 2:

[0079] The present invention provides a secondary well construction method based on the raise boring process, which adopts the following technical solution. In this solution, the directional drilling and pilot hole expansion drilling directions are forward drilling directions, while the expansion drilling directions of the small raise drill bit 13 and the large raise drill bit 16 are reverse drilling directions. This embodiment uses the raise boring vertical shaft drilling construction as an example for explanation, and the steps are as follows:

[0080] S1: Pre-construction preparation. A tunnel 1 is excavated within the underground rock mass. Before arranging a directional drill rig 3 on the ground corresponding to the tunnel, a foundation platform 2 is first formed by pouring concrete. The directional drill rig 3 is then secured to the foundation platform 2 using anchor bolts. Finally, all anchor bolts are completely capped with concrete.

[0081] S2: According to the use requirements of the directional drilling rig 3, the directional drilling rig 3 is arranged on the ground corresponding to the tunnel 1, and the directional drilling rig 3 is provided. Directional drill bit 4, multiple stable drill rods and directional drill rods;

[0082] S3: Install the directional drill bit 4 on the directional drilling rig 3, connect a stable drill rod to the tail end of the directional drill bit to form a composite drill rod 5, and start the directional drilling rig to drive the composite drill rod 5 to drill into the formation from top to bottom;

[0083] S4: A directional drill rod is fixedly connected to the tail end of the composite drill rod to form a new composite drill rod 5, and the composite drill rod continues to be drilled into the formation in a top-down direction;

[0084] S5: Repeat S4, alternately connecting the directional drill rod and the stable drill rod until a directional drill hole 8 connected to the tunnel is obtained, withdrawing the composite drill rod and dismantling the directional drilling rig;

[0085] S6: Using a measuring instrument to measure the maximum deviation δ of the center axis of the directional drilling hole relative to the design center axis of the shaft is 0.7m, and the radius r of the small raise drill bit 13 is selected to be 1m, which is greater than 0.7m;

[0086] S7: Install the raise drilling rig 9 according to the use requirements of the raise drilling rig, provide a small raise drilling rod 10, Reaming drill bit 11, Small raise well drill bit 13, large raise well drill rod 15 and Large raise drill bit 16;

[0087] S8: Install a reaming drill bit 11 at the end of the small raise drill rod 10, and the raise drill rig 9 drives the small raise drill rod and the reaming drill bit to drill into the formation from top to bottom along the directional drilling direction to reach the tunnel, forming a pilot hole 12;

[0088] S9: Remove the reaming drill bit 11 and assemble the small raise drill bit 13 at the end of the small raise drill rod;

[0089] S10: The small raise drill bit 13 is withdrawn in the direction of the pilot hole 12, driving the small raise drill bit 13 to reversely excavate the stratum to form a pilot well 14. The pilot well radius is 1m. During the construction process, the maximum deviation of the pilot well centerline relative to the designed centerline of the vertical shaft is 0.7m, which is smaller than the pilot well radius and meets the requirements of secondary drilling.

[0090] S11: Lower the large raise drill rod 15 vertically along the designed central axis of the vertical shaft to the tunnel 1, and install the large raise drill bit 16 at the end of the large raise drill rod 15;

[0091] S12: retracting the large raise drill rod 15 to drive the large-sized raise drill bit 16 to excavate the stratum from bottom to top along the designed direction of the vertical shaft to form a vertical shaft, with the boundary line of the vertical shaft substantially coinciding with the designed boundary line of the vertical shaft;

[0092] S13: After the raise boring rig has expanded the well for the second time, it is equipped with a single hook lifting system to lower materials and personnel, use integral metal formwork to build the wall, and use seamless steel pipes to lower concrete and cast the well wall.

Claims

1. A secondary well construction method based on reverse drilling technology, characterized in that: The following steps are involved: Step 1, construction of directional drilling (8): A tunnel (1) is excavated in advance in an underground rock mass, a directional drilling machine (3) is arranged and installed on the ground corresponding to the tunnel (1), a composite drill rod (5) and a directional drill bit (4) are installed on the directional drilling machine (3), the stratum is drilled and penetrated along the designed direction of the vertical / inclined well, and the tunnel (1) is connected to complete the construction of the directional drilling hole (8), and then the composite drill rod (5) is withdrawn; Step 2, deviation measurement of directional drilling (8): Measuring the maximum deviation distance δ between the axis of the directional drilling hole (8) and the vertical / inclined well design center axis (6); Step 3, construction of pilot hole (12): The directional drilling machine (3) is disassembled and the well raising machine (9) is installed, the small well raising drill rod (10) and the hole reaming drill bit (11) are connected, the hole reaming drill bit (11) is drilled from top to bottom along the direction of the directional drilling hole (8), a secondary hole brushing is performed to form a pilot hole (12), and the small well raising drill rod (10) is ensured not to be withdrawn; Step 4, construction of pilot well (14): A small-sized raise-well drill bit (13) with a radius of r is selected, wherein r>δ is ensured, the reamer drill bit (11) is disassembled and the small-sized raise-well drill bit (13) is replaced and installed at the end of the small-sized raise-well drill rod (10), and the small-sized raise-well drill rod (10) is withdrawn to drive the small-sized raise-well drill bit (13) to reversely excavate the formation, and excavate in the direction of the pilot hole (12) to form a pilot well (14); Step 5, construction of vertical / inclined shaft (17): The small well drilling bit (13) and the small well drilling rod (10) are disassembled, and the large well drilling rod (15) is lowered into the tunnel (1) along the design direction of the vertical / inclined well, and the large well drilling bit (16) is installed at the head of the large well drilling rod (15). The large well drilling rod (15) is withdrawn by the well drilling machine (9), and the large well drilling bit (16) is driven to reversely excavate the stratum along the design center axis (6) of the vertical / inclined well, and the vertical / inclined well (17) is formed in one step in line with the design excavation line (7) of the vertical / inclined well.

2. The secondary well construction method based on reverse drilling technology according to claim 1 is characterized in that: Before the directional drilling rig (3) is arranged and installed in step 1, concrete is first poured on the ground to form a foundation platform (2), and then the directional drilling rig (3) is fixed to the foundation platform (2) using anchor bolts, and then all the anchor bolts are completely covered with concrete.

3. The secondary well construction method based on reverse drilling technology according to claim 1 is characterized in that: In step 1, the composite drill rod (5) comprises a plurality of directional drill rods and a stable drill rod; during drilling, the directional drill rod is installed on a directional drilling machine (3), a directional drill bit (4) is installed on the head of the directional drill rod, and then the stable drill rod is connected to the tail end of the directional drill bit (4) to form the composite drill rod (5), and the directional drilling machine (3) is started to drive the composite drill rod (5) to drill into the formation from top to bottom.

4. The secondary well construction method based on reverse drilling technology according to claim 3 is characterized in that: During the process of the composite drill rod (5) continuing to drill, when the length of the composite drill rod (5) is insufficient, a corresponding directional drill rod and a stable drill rod are fixedly connected to the tail end of the composite drill rod (5) to form a new composite drill rod, and the formation is continued to be drilled in a top-down direction, and the directional drill rod and the stable drill rod are repeatedly connected alternately until a directional drill hole (8) connected to the tunnel (1) is obtained, the composite drill rod (5) is withdrawn, and the directional drilling machine (3) is dismantled.

5. The secondary well construction method based on reverse drilling technology according to claim 4 is characterized in that: During the downward drilling process of the directional drill pipe, a certain degree of deflection will occur at the connection of the directional drill pipe, and the directional drill pipe will be subjected to bending stress deformation due to the pressure. The deflection at the connection of the directional drill pipe and the bending stress deformation of the directional drill pipe itself are superimposed, causing the entire directional drill pipe to deviate from the designed central axis (6) of the vertical / inclined well to form a spiral downward directional drilling hole (8).

6. The secondary well construction method based on reverse drilling technology according to claim 5 is characterized in that: The diameter of the directional drilling hole (8) can ensure that the directional drilling rod can move freely up and down inside it, but the diameter is smaller than the diameter of the small reverse drilling rod (10); the central axis of the directional drilling hole (8) is spiral and has a certain deviation rate relative to the central axis (6) of the vertical / inclined well design.

7. The secondary well construction method based on reverse drilling technology according to claim 6 is characterized in that: In step 4, the central axis of the pilot well (14) is substantially coincident with the central axis of the pilot hole (12), forming a spiral shape, and there is also a certain inclination relative to the central axis (6) of the vertical / inclined well design. However, it is ensured that the radius r of the pilot well (14) is greater than the deviation of the pilot hole (12), so that the large reverse well drilling rod (15) can be straightly lowered along the central axis (6) of the vertical / inclined well design to the tunnel (1) at the bottom.

8. The secondary well construction method based on reverse drilling technology according to claim 1 or 6, characterized in that: The large-scale raise well drilling rod (15) has a diameter greater than that of the small-scale raise well drilling rod (10), and can drive the large-scale raise well drilling bit (16) to reversely excavate the stratum from bottom to top.

9. The secondary well construction method based on reverse drilling technology according to claim 8 is characterized in that: The large-scale raise well drill bit (16) has a diameter greater than 4 m and can be installed at the end of a large-scale raise well drill rod (15). As the large-scale raise well drill rod (15) rises, the strata are excavated to form a vertical / inclined well (17).

10. The secondary well construction method based on reverse drilling technology according to claim 8, characterized in that: The central axis of the vertical / inclined shaft (17) is substantially coincident with the designed central axis of the vertical / inclined shaft (6), and the deflection rate is close to zero.

11. The secondary well construction method based on reverse drilling technology according to claim 8, characterized in that: In step 3, the diameter of the reaming drill bit (11) is between 250 mm and 600 mm.

12. The secondary well construction method based on reverse drilling technology according to claim 1, characterized in that: After the vertical / inclined shaft (17) is formed in step 5, a single hook lifting system is provided to lower materials and personnel, and the wall is built with integral metal formwork, and concrete is lowered through seamless steel pipes to cast the shaft wall.

13. The secondary well construction method based on reverse drilling technology according to claim 1 is characterized in that: The hole expansion process is a process of breaking a large amount of rock. It is necessary to determine the model of the hole expansion drill bit and the layout of the rock breaking cutters according to the formation rock conditions, and formulate corresponding drilling parameters to achieve the purpose of drilling with the highest efficiency.

14. The secondary well construction method based on reverse drilling technology according to claim 1, characterized in that: The diameter size of the large-scale raise well drilling rod (15) is selected to ensure that it will not be interfered by the inner wall of the guide well (14) during the lowering process inside the guide well (14), so that the axis of the large-scale raise well drilling rod (15) coincides with the central axis (6) of the vertical / inclined well design.

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