Rock core yielding storage type drill bit and rock core micro-disturbance drilling method

Abstract

This invention belongs to the field of core drilling technology, specifically providing a core pressure-retaining drill bit and a core micro-disturbance drilling method. The drill bit includes a drill rod and a drilling section; the drilling section includes a cutter head and a drill bit, which are connected to the drill rod. The cutter head rotates via an external drilling rig. The drill rod includes a shell, a core storage sleeve, a nozzle, and a slurry guiding assembly; the shell and the core storage sleeve are nested together; the nozzle connects to the guide hole and the cutter head; the slurry guiding assembly includes a guide hole, a guide blind groove, and an overflow hole; the guide hole is interconnected with the cutter head; the guide blind groove is located on the inner wall of the core storage sleeve and is interconnected with the guide hole and the overflow hole; the overflow hole is located on the drill rod and is connected to the drill rod. This invention uses a nozzle to lubricate the cutter head with drilling fluid injected from the drill bit head, and uses a slurry guiding assembly to overflow the drilling fluid from the drill rod, optimizing drilling fluid recovery and reducing fluid flow interference.

Description

Technical Field

[0001] This invention belongs to the field of core drilling technology, and relates to a core pressure-reducing storage drill bit and a core micro-disturbance drilling method. Background Technology

[0002] In drilling, geological exploration, and downhole operations, it is often necessary to drill, sample, or analyze core samples from specific formations. Core drill bits, as a crucial downhole tool, are used to extract core samples from deep rock masses, preventing damage during drilling and ensuring the integrity of the core sample is effectively preserved at the target location. They are the core component for achieving precise and efficient core sampling operations. Traditional core drill bits mostly employ rotary or percussion structures, relying on an external drilling rig to drive their rotation and contact the rock mass for drilling.

[0003] However, existing core drill bits have significant limitations in practical applications. First, in complex formations or under high pressure conditions, traditional drill bits are prone to core damage due to rotational disturbances and internal stress release, resulting in core fragmentation (i.e., "core failure"), which severely affects sampling quality and analytical accuracy. Second, the core storage or retrieval process after drilling is complex, and there is even a risk of failure to retrieve the core successfully, increasing construction time and costs. Furthermore, conventional drill bits have limited adaptability to core expansion; under large stress fluctuations, they are prone to deformation or storage failure, resulting in insufficient reliability.

[0004] In summary, although the industry has made some improvements to the structure and materials of core drill bits, such as adopting gripper-type coring or simpler rigid sleeves, there is still room for improvement in ensuring minimal disturbance during drilling and maintaining the integrity of the core under dynamic stress. Especially in deep wells, ultra-deep wells, or under complex geological conditions, higher demands are placed on the storage reliability, integrity stability, and recyclability of core drill bits. Therefore, there is an urgent need for a new type of core drill bit structure that can effectively solve the problems of core damage, unstable storage, and difficult recovery that are common in existing technologies. Summary of the Invention

[0005] This invention provides a core pressure-reducing storage drill bit, including a drill rod and a drilling section disposed on the drill rod;

[0006] The drilling section includes a cutter head and a drill bit connected to each other. The end of the drill bit away from the cutter head is connected to the drill rod. The cutter head is rotated by the drive of an external drilling machine.

[0007] The drill pipe includes a housing and a core storage sleeve, a nozzle, and a slurry guiding assembly disposed within the housing; the housing and the core storage sleeve are nested together, and the core storage sleeve is positioned at the central axis of the housing; the nozzle is disposed on the drill bit and connects to the guide hole and the cutter head for injecting drilling fluid; the slurry guiding assembly includes a guide hole, a guide blind groove, and an overflow hole; the guide hole is disposed inside the drill bit and communicates with the cutter head; the guide blind groove is disposed on the inner wall of the core storage sleeve and communicates with the guide hole and the overflow hole; the overflow hole is disposed on the side of the drill pipe away from the cutter head and permeates the drill pipe.

[0008] Furthermore, the core storage sleeve is made of high-strength steel, and the thickness of the core storage sleeve is set to 2-3mm, and the yield strength is set to 400-500MPa.

[0009] Furthermore, the outer shell is made of hard steel and the thickness of the outer shell is set to 3-4 mm.

[0010] Furthermore, the drill pipe also includes balls, bearings, counterweights, and a buffer layer;

[0011] The buffer layer is disposed on the inner wall of the core storage sleeve, the counterweight is disposed on the outer wall of the core storage sleeve, and the ball bearing, consisting of balls and bearings, is disposed between the counterweight and the inner wall of the outer shell.

[0012] Furthermore, the bearing is connected to the inner wall of the housing by welding, and the bearing is connected to the counterweight by contact.

[0013] Furthermore, the bearing is configured as a high-precision ball bearing, with a diameter of 20-30 mm and a friction coefficient of 0.01-0.02.

[0014] Furthermore, the buffer layer is configured to buffer a compressible material structure.

[0015] Furthermore, the thickness of the buffer layer is set to 5-10 mm, and the compressive strength is set to 0.1-0.3 MPa.

[0016] Furthermore, the counterweight is made of high-density steel and its weight is set to 5-10 kg.

[0017] As a further aspect of the present invention, a core micro-disturbance drilling method is also provided, comprising the following steps:

[0018] Step 1: Assemble the core pressure storage drill bit as described above, and pre-set the core drill bit in the deep burial stratum. Lower the drill bit through the surface drilling rig and connect it to the external drilling rig through an external thread.

[0019] At this point, the bearing keeps the core storage sleeve relatively stationary through the counterweight, the ball bearings restrict the sleeve from sliding, the drilling fluid is sprayed through the nozzle, and the drill bit begins to drill.

[0020] Step 2: Continue pressurized drilling. The external drilling rig drives the cutter head and drill bit to rotate. High-pressure drilling fluid is sprayed through the nozzle and enters the core storage sleeve through the central retention hole in conjunction with the core.

[0021] The core storage sleeve is kept relatively stationary by bearings and counterweights to prevent the core from being damaged as the drill pipe rotates;

[0022] Drilling fluid is recovered from the drill pipe tail through guide holes, guide blind grooves and overflow holes to complete micro-drilling;

[0023] Step 3: After drilling is completed, the external thread is removed by lifting the upper drilling rig pipe to recover the core drill bit and core.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention uses a nozzle to lubricate the cutting head with drilling fluid pressed from the head of the drill bit, and uses a slurry guide assembly to allow drilling fluid to overflow from the drill pipe, thereby optimizing drilling fluid recovery and reducing fluid flow interference.

[0026] (2) The present invention uses a surface drilling machine to drill cores in deep strata, and can achieve relative stillness of the inner sleeve, reduce core disturbance, and thus prevent further damage to the core during drilling.

[0027] (3) In this invention, a buffer compressible material is covered inside the core storage sleeve assembly to accommodate the expansion of the core after the internal stress is released during deep mining.

[0028] (4) In the parallel operation process, the internal core storage sleeve of the present invention has internal bearings and counterweights that allow the internal sleeve to remain relatively stationary during the rotation of the external drill rod to extract cores, thereby achieving micro-disturbance drilling of cores from deep rock masses.

[0029] (5) The present invention can solve the problems of core damage and pipe jamming caused by existing core drill bits due to rotational disturbance, stress release expansion or poor flow.

[0030] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0031] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0032] Figure 1 This is a schematic front cross-sectional view of a rock core pressure-relief storage drill bit according to an embodiment of the present invention;

[0033] Figure 2 yes Figure 1 A left-view diagram;

[0034] Figure 3 yes Figure 1 A diagram showing the view from the right.

[0035] Figure 4(a) is Figure 1 A schematic diagram of the connection cross-section of the first type of counterweight;

[0036] Figure 4(b) is Figure 1 A schematic diagram of the connection cross-section of the second type of counterweight;

[0037] Figure 4(c) is Figure 1 A schematic diagram of the connection cross-section of the third type of counterweight.

[0038] in:

[0039] 1. Cutting head, 2. Drill bit, 3. Ball bearing, 4. Bearing, 5. Counterweight, 6. Buffer layer, 7. Nozzle, 8. Guide hole, 9. Guide blind groove, 10. Outer shell, 11. Core storage sleeve, 12. Overflow hole, 13. Internal thread, 14. External thread. Detailed Implementation

[0040] To make the above-mentioned objectives, features, and advantages of the present invention clearer and easier to understand, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the accompanying drawings of the present invention are all in a simplified form and use non-precise proportions, and are only used to facilitate and clearly assist in illustrating the implementation of the present invention; the "several" mentioned in the present invention are not limited to the specific number shown in the examples in the accompanying drawings; the orientations or positional relationships indicated by terms such as "front," "middle," "rear," "left," "right," "up," "down," "top," "bottom," and "center" mentioned in the present invention are all based on the orientations or positional relationships shown in the accompanying drawings of the present invention, and do not indicate or imply that the device or component referred to must have a specific orientation, nor should they be construed as limitations on the present invention.

[0041] Example 1:

[0042] See Figures 1 to 3As shown, the present invention provides a core pressure-relief storage drill bit with an embedded self-rotating sleeve, which is installed in the rock and soil by pre-setting an installation position in the deep stratum at the location to be drilled; it includes a drill rod and a drilling section disposed on the drill rod;

[0043] The drilling section includes a cutter head 1 and a drill bit 2 connected to each other. The end of the drill bit 2 away from the cutter head 1 is connected to the drill rod through an internal thread 13. The cutter head 1 is rotated by the drive of an external drilling machine to achieve drilling of deep rock.

[0044] The drill pipe includes a housing 10 and a core storage sleeve 11, a nozzle 7, and a slurry guiding assembly disposed within the housing 10. The housing 10 and the core storage sleeve 11 are nested together, and the core storage sleeve 11 is positioned at the central axis of the housing 10. The nozzle 7 is disposed on the drill bit 2 and connects to the guide hole and the cutter head 1 for injecting drilling fluid. The slurry guiding assembly includes a guide hole 8, a guide blind groove 9, and an overflow hole 12. The guide hole 8 is disposed within the drill bit 2 and is interconnected with the cutter head 1. The guide blind groove 9 is disposed on the inner wall of the core storage sleeve 11 and is interconnected with the guide hole 8 and the overflow hole 12. The overflow hole 12 is disposed on the side of the drill pipe away from the cutter head 1 and is disposed through the drill pipe so that the drilling fluid transported through the guide hole 8 and the guide blind groove 9 overflows from the tail of the drill pipe.

[0045] Preferably, the drill pipe further includes a buffer layer 6, a counterweight 5, balls 3, and a bearing 4;

[0046] The buffer layer 6 is disposed on the inner wall of the core storage sleeve 11, the counterweight 5 is disposed on the outer wall of the core storage sleeve 11, and the ball bearing composed of ball 3 and bearing 4 is disposed between the counterweight 5 and the inner wall of the outer shell 10.

[0047] Preferably, the counterweight 5 has multiple pieces that are spaced apart from each other along the central axis of the core storage sleeve 11.

[0048] Preferably, the ball bearings are provided in multiple sets that are spaced apart from each other along the central axis of the core storage sleeve 11, and each set of ball bearings is provided in multiple pieces arranged in a circumferential array along the core storage sleeve 11.

[0049] Preferably, the bearing 4 is connected to the inner wall of the housing 10 by welding, and the bearing 4 is connected to the counterweight by contact.

[0050] Preferably, the buffer layer 6 is configured as a buffer compressible material structure (specifically, the buffer compressible material is selected from at least one of foam plastic, air cushion material, fiber material, rubber and elastomer material, and composite and new materials) to achieve buffering of the inside of the rock core storage sleeve 11, thereby ensuring the relative stillness between the bearing 4 and the counterweight 5.

[0051] Further preferably, the buffer layer 6 can be configured as a flexible foam material structure (specifically, the flexible foam material is selected from at least one of melamine foam, soft polyurethane foam, polyvinyl chloride foam, and polypropylene foam), and the thickness of the buffer layer 6 is set to 5-10 mm (specifically, in this embodiment, it is preferably set to 8 mm), and the compressive strength is set to 0.1-0.3 MPa (specifically, in this embodiment, it is preferably set to 0.2 MPa), so that it has higher compressibility and buffering capacity than traditional storage materials, which facilitates adaptive compression under core expansion.

[0052] Preferably, the core storage sleeve 11 is a high-strength steel structural component (specifically, the high-strength steel is selected from the NM series), and the thickness of the core storage sleeve 11 is set to 2-3mm (specifically, in this embodiment, it is preferably set to 2.5mm), and the yield strength is set to 400-500MPa (specifically, in this embodiment, it is preferably set to 450MPa).

[0053] Preferably, the outer shell 10 is a hard steel structural component (specifically, the hard steel is selected from at least one of high carbon tool steel, high speed steel, and cemented carbide), and the thickness of the outer shell 10 is set to 3-4 mm (specifically, in this embodiment, it is preferably set to 3.5 mm). It is fixed to the bearing 4 by welding to provide additional support and prevent the cushioning compressible material structural component from being over-compressed and causing failure.

[0054] Preferably, the bearing 4 is a high-precision ball bearing, and the diameter of the bearing 4 is set to 20-30mm (specifically, in this embodiment, it is preferably set to 25mm) and the coefficient of friction is set to 0.01-0.02 (specifically, in this embodiment, it is preferably set to 0.015), which is used to restrict the rotation of the core storage sleeve 11 during drilling.

[0055] Preferably, the counterweight 5 is a high-density steel structural component (specifically, the high-density steel is selected from at least one of high-density alloy steel, high-strength steel, and AHSS), and the weight of the counterweight 5 is set to 5-10 kg (specifically, in this embodiment, preferably 7 kg), to ensure that the core storage sleeve 11 remains relatively stationary when the external drilling rig rotates. More preferably, as shown in Figures 4(a) to 4(c), when the weight of the counterweight 5 is set differently, the counterweight is arranged with different cross-sectional sizes.

[0056] Preferably, the diameter of the guide hole 8 is set to 50-100mm (specifically, in this embodiment, it is preferably set to 60mm).

[0057] Preferably, the length of the flow guide blind groove 9 is set to 1000-1500mm (specifically, in this embodiment, it is preferably set to 1200mm).

[0058] Preferably, the diameter of the overflow hole 12 is set to 100-150mm (specifically, in this embodiment, it is preferably set to 120mm), and it is located at the tail of the drill pipe to ensure efficient recovery of drilling fluid.

[0059] Preferably, the inner diameter of the core storage sleeve 11 is 50-70mm (specifically, in this embodiment, it is preferably set to 60mm), and it fits tightly with the cushioning compressible material after compression to form a sealed storage chamber.

[0060] As a further embodiment of the present invention, in order to facilitate the connection between the core pressure storage drill bit and the drill rod of an external drilling machine, an external thread 14 is provided at the end of the drill rod away from the drilling section.

[0061] The drill pipe is connected to an external drilling rig via an external thread 14. The drill bit 2 sprays drilling fluid through a nozzle 7. The external drilling rig drives the cutter head 1 to rotate and drill deep into the rock mass. The core enters the core storage sleeve 11 through the central retention hole. The drilling fluid overflows from the tail of the drill pipe through the guide hole 8, the guide blind groove 9, and the overflow hole 12. The core storage sleeve 11 is covered with a buffer layer 6 and is kept relatively stationary by bearings 4 and counterweights 5. The outer shell 10 is fixed to the bearings 4 by welding. The counterweights 5, the buffer compressible material, and the slurry guiding components (composed of the guide hole 8, the guide blind groove 9, and the overflow hole 12) are an independent whole.

[0062] Furthermore, the volume of the sealed storage chamber is determined by the compression range of the cushioning compressible material and the inner diameter of the core storage sleeve 11, and the volume is variable. If enhanced storage stability is required, the compression range can be optimized by adjusting the thickness of the cushioning compressible material (range 5-10 mm).

[0063] Furthermore, the core storage drill bit, through the synergistic action of the bearing 4 and the counterweight 5, ensures that the core storage sleeve 11 remains relatively stationary during drilling, reducing core disturbance; the adaptive compression of the buffer compressible material effectively copes with core expansion and prevents pipe jamming; the guide blind groove 9 and overflow hole 12 optimize drilling fluid recovery and reduce fluid flow interference; the disassembly mechanism of the external thread 14 facilitates recovery and reduces construction costs. The entire drilling process, through the synergistic action of the core and drilling fluid, achieves the formation of a uniform core channel, protects core integrity, and ensures efficient drilling operations and long-term core stability.

[0064] Example 2:

[0065] The method for core micro-drilling using a core pressure-retaining drill bit as described in Example 1 includes the following steps:

[0066] Step 1: Position the core drill bit in the deep stratum and lower it using a surface drilling rig. Connect the grouting pipe to the external drilling rig via the external thread 14. At this time, the bearing 4 keeps the core storage sleeve 11 relatively stationary through the counterweight 5 (7kg), the ball bearing 3 restricts the sleeve from sliding, the drilling fluid is sprayed through the nozzle 7, and the cutter head 1 begins drilling.

[0067] Step 2: Continue pressurized drilling. The external drilling rig rotates the entire external body. High-pressure drilling fluid is injected through nozzle 7 and, together with the core, enters the core storage sleeve 11 through the central retention hole. The core storage sleeve 11 is kept relatively stationary by bearing 4 and counterweight 5 to prevent damage to the core as the drill pipe rotates. The drilling fluid is recovered from the drill pipe tail through guide hole 8, guide blind groove 9, and overflow hole 12, completing micro-disturbance drilling. During this process, the compressibility boundary formed by the buffer compressible material (defined as the buffer compressible material compressibility boundary) partially coincides with the core entry path. The compressibility boundary gradually expands under the continuous action of core expansion and drilling fluid, enhancing storage stability.

[0068] Step 3: After drilling is completed, the external thread 14 is removed by lifting the upper drilling rig pipe to recover the core drill bit and core; the grouting pipe is also recovered to reduce material waste.

[0069] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A core pressure-reducing storage drill bit, characterized in that, Includes drill pipe and drilling section mounted on drill pipe; The drilling section includes a cutter head (1) and a drill bit (2) connected to each other. The end of the drill bit (2) away from the cutter head (1) is connected to the drill rod. The cutter head (1) is rotated by the drive of an external drilling machine. The drill pipe also includes balls (3), bearings (4), counterweights (5) and a buffer layer (6); The buffer layer (6) is disposed on the inner wall of the core storage sleeve (11), the counterweight (5) is disposed on the outer wall of the core storage sleeve (11), and the ball bearing composed of ball (3) and bearing (4) is disposed between the counterweight (5) and the inner wall of the outer shell (10). The drill pipe includes a housing (10) and a core storage sleeve (11), a nozzle (7), and a slurry guiding assembly disposed within the housing (10); the housing (10) and the core storage sleeve (11) are nested together, and the core storage sleeve (11) is located at the central axis of the housing (10); the nozzle (7) is disposed on the drill bit (2) and connects to the guide hole and the cutter head (1) for injecting drilling fluid; the slurry guiding assembly includes The drill bit (2) has a guide hole (8), a guide blind groove (9), and an overflow hole (12). The guide hole (8) is located inside the drill bit (2) and is interconnected with the cutter head (1). The guide blind groove (9) is located between the bearing (4) and the counterweight (5) and is interconnected with the guide hole (8) and the overflow hole (12). The overflow hole (12) is located on the side of the drill rod away from the cutter head (1) and is connected to the drill rod. The steps for core micro-drilling using a core pressure-relief storage drill bit are as follows: Step 1: Assemble the core pressure storage drill bit and pre-set the core drill bit in the deep stratum. Lower the drill bit through the surface drilling rig and connect it to the external drilling rig through an external thread. At this point, the bearing keeps the core storage sleeve relatively stationary through the counterweight, the ball bearings restrict the slippage of the core storage sleeve, the drilling fluid is sprayed through the nozzle, and the drill bit begins to drill. Step 2: Continue pressurized drilling. The external drilling rig drives the cutter head and drill bit to rotate. High-pressure drilling fluid is sprayed through the nozzle and enters the core storage sleeve through the central retention hole in conjunction with the core. The core storage sleeve is kept relatively stationary by bearings and counterweights to prevent the core from being damaged as the drill pipe rotates; Drilling fluid is recovered from the drill pipe tail through guide holes, guide blind grooves and overflow holes to complete micro-drilling; Step 3: After drilling is completed, the external thread is removed by lifting the upper drilling rig pipe to recover the core drill bit and core.

2. The core pressure-relief storage drill bit according to claim 1, characterized in that, The core storage sleeve (11) is made of high-strength steel and has a thickness of 2-3 mm and a yield strength of 400-500 MPa.

3. The core pressure-relief storage drill bit according to claim 1 or 2, characterized in that, The outer shell (10) is a hard steel structural component, and the thickness of the outer shell (10) is set to 3-4 mm.

4. The core pressure-relief storage drill bit according to claim 3, characterized in that, The bearing (4) is connected to the inner wall of the outer shell (10) by welding, and the bearing (4) is connected to the counterweight by contact.

5. The core pressure-relief storage drill bit according to claim 4, characterized in that, The bearing (4) is a high-precision ball bearing, and the diameter of the bearing (4) is set to 20-30mm and the coefficient of friction is set to 0.01-0.

02.

6. The core pressure-relief storage drill bit according to claim 5, characterized in that, The buffer layer (6) is configured as a buffer compressible material structure.

7. The core pressure-relief storage drill bit according to claim 6, characterized in that, The thickness of the buffer layer (6) is set to 5-10 mm and the compressive strength is set to 0.1-0.3 MPa.

8. The core pressure-relief storage drill bit according to claim 6 or 7, characterized in that, The counterweight (5) is a high-density steel structural component, and the weight of the counterweight (5) is set to 5-10 kg.

Images