Method for directional coring along large-angle curved path

Abstract

The present invention relates to the technical field of geological survey, and provides a method for directional coring along a large-angle curved path, comprising the following steps: S1, selecting an appropriate drilling path on the basis of the depth and span of a river bottom to be traversed, so as to ensure that the drilling path passes through the entire river bottom and reaches a mountain on an opposite bank; S2, using a first coring tool to drill a first borehole section in a downward-inclined direction from a road surface, and during the drilling, a wireline coring mechanism inside the first coring tool continuously cutting off and retrieving core samples; S3, retrieving the first coring tool upon completion of the drilling of the first borehole section, and mounting a casing in the first borehole section; and S4, replacing the first coring tool with a second coring tool, a pilot bit passing through the casing and continuing drilling, the pilot bit continuously changing the drilling direction under the weight of a coring drill rod, and a wireline coring mechanism inside the second coring tool continuously cutting off and retrieving core samples. In the present invention, the drilling direction of the drill bit can be changed during drilling and coring, thereby facilitating directional traversal across deep-cut valleys and retrieval of core samples in mountainous and canyon regions.

Description

Large angle curve directional coring method TECHNICAL FIELD

[0001] The present application relates to the technical field of geological exploration, in particular to a large angle curve directional coring method. BACKGROUND

[0002] Major engineering construction is mostly located in the extremely complex topography and geological conditions of the western mountainous area, and faces the extreme geological environment of high altitude, high buried depth, high stress, high water pressure and large drop, and directional coring drilling faces great challenges.

[0003] Before the construction of large hydropower stations, it is necessary to carry out coring exploration on the river bottom and the opposite mountain to evaluate the engineering geological properties such as foundation bearing capacity and stability, and to provide important basis for the design and construction of the project. At present, for the exploration drilling in high-altitude and large-drop areas, especially in the bottom of deep-cut valley with a depth of thousands of meters, due to the difficulty or even impossibility of moving some large engineering exploration equipment, and the difficulty in effectively building auxiliary platforms on the river surface, the coring of the river bottom and the opposite mountain is very difficult, and it is impossible to ensure that the coring trajectory passes through the specified positions of the river bottom and the opposite mountain in sequence. SUMMARY

[0004] The purpose of the present application is to provide a large angle curve directional coring method, which can change the drilling direction of the drill bit during the drilling and coring process, so as to facilitate the directional crossing of deep-cut valleys in high mountain and valley areas, and to obtain the rock core of the specified area of the river bottom and the opposite mountain, without the need to build auxiliary platforms on the river surface to facilitate the coring process.

[0005] The embodiment of the present application is realized by the following technical scheme: a large-angle curve directional coring method, comprising the following steps: S1, selecting a proper drilling path according to the depth and span of the river bottom to be crossed, to ensure that the drilling path can pass through the entire river bottom and reach the opposite mountain; S2, using a first coring drill to open a first section of borehole in the road surface in an inclined downward direction, and a rope coring mechanism arranged inside the first coring drill continuously cuts and takes out the core during the drilling process, to complete the construction of the first section of borehole; S3, after the first section of borehole is opened, the first coring drill is taken out, and then a casing is installed in the first section of borehole; S4, a second coring drill is replaced, the second coring drill comprises a guide drill bit, a reamer, a stabilizer and a plurality of coring drill rods, the reamer is arranged at the tail of the guide drill bit, the plurality of coring drill rods are connected on the reamer in sequence, the stabilizer is slidably arranged on the coring drill rod connected with the reamer and is detachably connected with the coring drill rod, the outer diameter of the stabilizer is smaller than the outer diameter of the guide drill bit, and the difference between the outer diameter of the coring drill rod and the outer diameter of the guide drill bit is greater than 15 mm, so that the stabilizer can serve as a rotation fulcrum during the drilling process; after the second coring drill is replaced, the guide drill bit of the second coring drill continues to drill through the casing, and the guide drill bit of the second coring drill continuously changes the drilling direction under the weight of the coring drill rod during the drilling process, to complete the opening of a second section of borehole, and a rope coring mechanism arranged inside the second coring drill continuously cuts and takes out the core.

[0006] Further, the size of the first coring drill is greater than the size of the second coring drill.

[0007] Further, the angle between the drilling direction of the first coring drill and the horizontal plane is 60°-75°, and the first section of borehole extends in an inclined downward direction.

[0008] Further, the extension direction of the second section of borehole is arc-shaped, and the inclination angle between the second section of borehole and the horizontal plane gradually decreases from top to bottom until it tends to be horizontal.

[0009] Further, the outer diameter of the guide drill bit is 99 mm, the outer diameter of the coring drill rod is 72 mm, and the outer diameter of the stabilizer is 97 mm.

[0010] Further, the wall thickness of the coring drill rod is greater than 7.8 mm.

[0011] Further, the outer diameter of the drill bit of the first coring drill is 122 mm, and the outer diameters of the drill rod and the casing are both 114 mm.

[0012] The technical scheme of the embodiment of the present application has at least the following advantages and beneficial effects:

[0013] 1. The first hole and the second hole are drilled in sequence, the drilling path can pass through the river bottom and the designated area of the opposite mountain in sequence under the condition that the starting drilling position is fixed, so that the core in the designated area can be successfully obtained, and the most accurate basis for engineering design and construction is provided.

[0014] 2. The structure of the second coring drill is designed, the outer diameter of the stabilizer is smaller than the outer diameter of the guide drill bit, and the difference between the outer diameter of the coring drill rod and the outer diameter of the guide drill bit is greater than 15mm, so that the stabilizer can be used as a rotating fulcrum during drilling, and under the action of the gravity of the plurality of coring drill rods, the guide drill bit can be tilted upward by a certain angle, so that the drilling direction is changed, and the originally flat hole with constant inclination angle is changed into an arc-shaped hole with changing inclination angle, so as to pass through the designated area of the river bottom of the kilometer-level river channel.

[0015] 3. The coring drill rod with an outer diameter of 72mm is selected, the existing geological coring equipment can be used, and new equipment does not need to be customized and produced, the strength of the coring drill rod is improved by increasing the wall thickness and thread screw of the coring drill rod, and the breaking of the coring drill rod is avoided. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced below, and it should be understood that the following drawings only show some embodiments of the present application, and should not be regarded as a limitation on the scope, and other related drawings can be obtained by those skilled in the art without creative labor on the premise of not paying creative labor.

[0017] Fig. 1 is a structural schematic view of the core path in the river bottom and the opposite mountain;

[0018] Fig. 2 is a structural schematic view of the second coring drill when drilling the second hole;

[0019] Fig. 3 is a structural schematic view of the second coring drill during drilling;

[0020] Fig. 3 is a structural schematic view of the second coring drill during drilling; DETAILED DESCRIPTION

[0021] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present application.

[0023] Embodiment 1

[0024] The following is further illustrated in conjunction with specific embodiments, with reference to FIGS. 1-3, the present application is a large-angle curve directional coring method, comprising the following steps: S1, according to the depth and span of the river bottom 1 to be crossed, select the appropriate drilling path to ensure that the drilling path can pass through the entire river bottom 1 and reach the opposite bank mountain 2, the specific operation mode is: several core positions are selected in the designated area of the river bottom 1 and the lower part of the opposite bank mountain 2 respectively, and a circular arc transition arc path is obtained by connecting the selected core positions in turn, which is the drilling path. Limited by the construction environment, the drilling equipment can only be transported to the relatively flat highway in the high-altitude large-fall area, and before the construction of the hydropower station and the related diversion tunnel and pipeline, it is necessary to find out that the designated area under the river bottom 1 and the designated area of the opposite bank mountain 2 have good engineering geological conditions, therefore, the path needs to be ensured to pass through the designated area of the river bottom 1 and the opposite bank mountain 2 in turn during the drilling process, and the drilling path must include the arc trajectory to ensure that the drilling process can pass through the designated area of the river bottom 1 and the opposite bank mountain 2 in turn under the condition that the starting drilling position is fixed, and the accuracy of the core position is ensured, thereby providing the most accurate basis for the design and construction of the project.

[0025] S2, a first coring drill is used to drill a first section of borehole 3 in the road in an obliquely downward direction, the rope coring mechanism arranged inside the first coring drill continuously cuts and takes out the rock core during the drilling process, and the drilling construction of the first section of borehole 3 is completed; S3, after the first section of borehole 3 is drilled, the first coring drill is taken out, and then a casing is installed in the first section of borehole 3. Since the ground surface layer needs to be first passed through during the drilling process, the stability of the ground surface layer is poor, and therefore the first section of borehole 3 needs to be first constructed to be flat, and the casing needs to be installed in the first section of borehole 3 to improve the stability and avoid collapse of the first section of borehole 3 during the subsequent drilling process. The included angle between the drilling direction of the first coring drill and the horizontal plane is 60°-75°, and therefore the first section of borehole 3 is a hole extending obliquely downward at an angle of 60°-75°, which can extend as close to the river bottom 1 as possible, and can also ensure that the preset drilling path can be met under the condition that the width of the road is limited.

[0026] S4, the second coring drill 5 is replaced, the guide drill bit 51 of the second coring drill 5 continues to drill through the casing, the guide drill bit 51 of the second coring drill 5 continuously changes the drilling direction under the weight of the coring drill rod 54 during the drilling process, the drilling of the second section of borehole 4 is completed, and the rope coring mechanism arranged inside the second coring drill 5 continuously cuts and takes out the rock core. The extension direction of the second section of borehole 4 is arc-shaped, and the oblique angle between the second section of borehole 4 and the horizontal plane gradually decreases from top to bottom until it tends to be horizontal.

[0027] The size of the first coring drill is greater than that of the second coring drill 5, so that the second coring drill 5 can smoothly pass through the first section of borehole 3 and has a certain activity space. The first coring drill is a common coring drill in the prior art, the outer diameter of the selected drill bit is 122 mm, the outer diameter of the drill rod is 114 mm, and the outer diameter of the installed casing is 114 mm, which is the same as the outer diameter of the drill rod.

[0028] The second coring drilling tool 5 comprises a pilot bit 51, a reamer 52, a stabilizer 53 and a plurality of coring drill pipes 54, the reamer 52 is arranged at the tail of the pilot bit 51, the plurality of coring drill pipes 54 are connected in sequence on the reamer 52, the stabilizer 53 is slidingly installed on the coring drill pipe 54 connected with the reamer 52 and is detachably connected with the coring drill pipe 54, the outer diameter of the stabilizer 53 is smaller than the outer diameter of the pilot bit 51, and the difference between the outer diameter of the coring drill pipe 54 and the outer diameter of the pilot bit 51 is greater than 15 mm. In the prior art, the diameter of the stabilizer 53 is usually equal to the diameter of the pilot bit 51, so as to facilitate the righting of the pilot bit 51 and constrain the pilot bit 51 from swinging, but in the embodiment, the second coring drilling tool 5 needs to complete a curved trajectory, so the inclination angle between the advancing direction of the pilot bit 51 and the horizontal plane needs to be gradually reduced during drilling, so that the coring drill pipe 54 can pass through the designated area below the kilometer riverbed and reach the designated area at the bottom of the opposite mountain 2, and the coring process of the above-mentioned designated area is realized. Therefore, in the embodiment, the outer diameter of the stabilizer 53 is reduced, so that the stabilizer 53 can act as a rotating fulcrum in the borehole, and the plurality of coring drill pipes 54 will move downward under the action of their own gravity and be attached to the inner wall of the second borehole 4, so that the pilot bit 51 is raised upward, so that the inclination angle between the second borehole 4 obtained in the subsequent drilling process and the horizontal plane is gradually reduced, so that the drilling trajectory is consistent with the drilling path designed in step S1.

[0029] Specifically, in the embodiment, the outer diameter of the pilot bit 51 of the second coring drilling tool 5 is 99 mm, the outer diameter of the stabilizer 53 is 97 mm, which is smaller than the outer diameter of the pilot bit 51. Since the advancing direction of the pilot bit 51 needs to be changed during drilling in the embodiment, the outer diameter of the stabilizer 53 is reduced, so that the center position of the stabilizer 53 can act as a rotating fulcrum in the second borehole 4. The outer diameter of the coring drill pipe 54 is 72 mm, and the difference between the outer diameter of the coring drill pipe 54 is 27 mm, so that the coring drill pipe 54 can act as a rotating fulcrum in the second borehole 4, and press downward to be attached to the hole wall of the second borehole 4, while the pilot bit 51 has an upward turning space, so as to achieve the predetermined drilling trajectory. Since the coring drill pipe 54 matched with the geological coring equipment has a fixed specification, the coring drill pipe 54 with an outer diameter of 72 mm can be applied to the existing geological coring equipment without the need for custom production of new equipment, thereby reducing the cost of equipment.

[0030] The guide drill bit 51 with an outer diameter of 99 mm is usually configured with a coring drill rod 54 with an outer diameter of 89 mm. In this embodiment, the outer diameter of the coring drill rod 54 is reduced, and thus the wall thickness is increased to 8.8 mm-9.3 mm, which is greater than the wall thickness of a conventional coring drill rod 54, i.e., 7.8 mm. Meanwhile, the length and pitch of the internal and external threads of the coring drill rod 54 are optimized accordingly to improve the overall strength of the combination of multiple coring drill rods 54. Compared with the conventional coring drill rod 54, the maximum torque and tensile strength are improved, and the coring drill rod 54 is less likely to break.

[0031] The stabilizer 53 is slidingly arranged on the coring drill rod 54 and detachably connected with the coring drill rod 54. Specifically, when the stabilizer 53 is in a disassembled state relative to the coring drill rod 54, the stabilizer 53 can reciprocally slide along the axis of the coring drill rod 54. When the stabilizer 53 is in a connected state relative to the coring drill rod 54, the stabilizer 53 is fixed at a suitable position in the axial direction of the coring drill rod 54. In this embodiment, the stabilizer 53 is provided with connecting bolts, and the coring drill rod 54 is provided with a plurality of threaded holes for inserting the connecting bolts. During drilling, due to the influence of the geological environment, the hardness of the geological environment inside changes, and the actual trajectory inevitably deviates from the theoretical trajectory. When deviation occurs, the position of the overall rotation fulcrum of the second coring drilling tool 5 needs to be changed. The stabilizer 53 is detachably installed on the coring drill rod 54 by means of bolt connection, so that the position of the overall structure rotation fulcrum can be adjusted, thereby the drilling direction of the guide drill bit 51 can be adjusted according to the actual situation on site. It can be understood that the monitoring of the actual trajectory can refer to the prior art. When the deviation between the actual trajectory and the theoretical trajectory exceeds the expected threshold, the second coring drilling tool 5 can be taken out as a whole, the position of the stabilizer 53 in the axial direction of the coring drill rod 54 is adjusted, and then the second coring drilling tool 5 is put back in for continuous coring drilling. When the deviation between the actual trajectory and the theoretical trajectory is within the expected threshold, the second coring drilling tool 5 can be continuously drilled without being taken out.

[0032] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Various modifications and changes can be made by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A high-angle curve directional coring method characterized by, It comprises the following steps: S1. Selecting a proper drilling path according to the depth and span of the river bottom (1) to be crossed, ensuring that the drilling path can pass through the entire river bottom (1) and reach the opposite mountain (2); S2. Using a first coring drill to drill a first section of borehole (3) in the road surface in an obliquely downward direction, and a rope coring mechanism arranged inside the first coring drill continuously cuts and takes out the rock core during the drilling process, thereby completing the construction of the first section of borehole (3); S3. After the first section of borehole (3) is drilled, the first coring drill is removed, and then a casing is installed in the first section of borehole (3); S4. Replacing a second coring drill (5), which comprises a guide drill bit (51), a reamer (52), a stabilizer (53), and a plurality of coring drill rods (54), the reamer (52) is arranged at the tail of the guide drill bit (51), the plurality of coring drill rods (54) are connected in sequence on the reamer (52), the stabilizer (53) is slidably arranged on the coring drill rod (54) connected with the reamer (52) and is detachably connected with the coring drill rod (54), the outer diameter of the stabilizer (53) is smaller than the outer diameter of the guide drill bit (51), and the difference between the outer diameter of the coring drill rod (54) and the outer diameter of the guide drill bit (51) is greater than 15 mm, so that the stabilizer (53) can serve as a rotation fulcrum during the drilling process; After the second coring drill (5) is replaced, the guide drill bit (51) of the second coring drill (5) continues to drill through the casing, and the guide drill bit (51) of the second coring drill (5) continuously changes the drilling direction under the weight of the coring drill rod (54) during the drilling process, thereby completing the drilling of the second section of borehole (4), and a rope coring mechanism arranged inside the second coring drill (5) continuously cuts and takes out the rock core.

2. The large angle curve directional coring method of claim 1, wherein: The size of the first coring drill is greater than that of the second coring drill (5).

3. The large angle curve directional coring method of claim 1, wherein: The angle between the drilling direction of the first coring drill and the horizontal plane is 60°-75°, and the first section of borehole (3) extends obliquely downward.

4. The large angle curve directional coring method of claim 1, wherein: The extension direction of the second section of borehole (4) is arc-shaped, and the inclination angle between the second section of borehole (4) and the horizontal plane gradually decreases from top to bottom until it tends to be horizontal.

5. The large angle curve directional coring method of claim 1, wherein: The outer diameter of the guide drill bit (51) is 99 mm, the outer diameter of the coring drill rod (54) is 72 mm, and the outer diameter of the stabilizer (53) is 97 mm.

6. The large angle curve directional coring method of claim 5, wherein: The wall thickness of the coring drill rod (54) is greater than 7.8 mm.

7. The large angle curve directional coring method of claim 5, wherein: The outer diameter of the drill bit of the first coring drill is 122 mm, the outer diameter of the drill rod and the outer diameter of the casing are both 114 mm.

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