A micro coring drill bit

Abstract

This utility model discloses a micro-coring drill bit, relating to the field of drilling equipment. It includes a drill bit body with circumferentially spaced cutting blades and a pre-reserved coring space at the center of the drill bit body's crown. The drill bit body also has a coring channel, with its inlet end penetrating the center of the drill bit body's crown and its outlet end penetrating the circumferential surface of the drill bit body. A detachable coring head is installed at the inlet end of the coring channel, with its head not lower than the surface of the drill bit body and having coring teeth evenly spaced along its circumference. Core breaking teeth are also installed within the coring channel, located at the outlet end of the coring head. This utility model, by installing a detachable coring head at the center of the drill bit, allows for direct replacement of the coring head when the existing teeth are unable to perform coring operations, ensuring that all cutting teeth on the drill bit can perform coring operations before they become unusable.

Description

Technical Field

[0001] This utility model relates to the field of drilling equipment, and more specifically, to a micro coring drill bit. Background Technology

[0002] In petroleum and geological exploration, rock sampling is necessary to understand the geological conditions of the drilled formations. This involves determining the mineral composition and rock properties of the formations, among other geological analyses. The quality and yield of the core samples directly affect the accuracy of the geological analysis.

[0003] Therefore, in order to facilitate core sampling, various drill bits that can perform coring during drilling have been disclosed, such as: application numbers 202211097760.X, 201320086144.4, and 201320570897.2. These drill bits all have a pre-reserved coring channel in the center of the drill bit, and coring teeth are welded at the opening of the coring channel or on the inner end face of the cutter blade. When the drill bit is drilling, the coring teeth at the opening of the coring channel or on the inner end face of the cutter blade perform coring. The obtained rock core enters the coring channel after breaking and is finally discharged directly from the chip removal channel. However, due to the limited number of coring teeth in this type of drill bit, it is difficult to form a complete core during drilling. Furthermore, the coring teeth are directly welded to the opening of the coring channel or the inner end face of the cutter blade, making them difficult to replace when they are severely worn. The bending angle at the core break point in the coring channel is small, and the lateral space is limited, resulting in secondary damage to the core when it breaks. The high-speed jet generated by the internal fluid channel also damages the core. The outlet of the core discharge channel is too close to the well wall, causing the core to scrape against the well wall during discharge, and the radial resistance generated by the drill bit rotation causes secondary damage to the core. In addition, during the reaming operation, rock cuttings scraping against the well wall can easily enter the core discharge channel from the core discharge outlet, causing blockage of the core discharge channel. Utility Model Content

[0004] The purpose of this invention is to provide a micro coring drill bit. By installing a detachable coring head at the center of the drill bit, when the coring teeth on the coring head are unable to perform coring operations, a new coring head can be directly replaced. This allows the cutting teeth on the drill bit to perform coring operations before they are scrapped, thus extending the service life of the coring drill bit.

[0005] To achieve the purpose of this utility model, the technical solution adopted is as follows: a micro coring drill bit, comprising a drill bit body, wherein the drill bit body has blades arranged at intervals in a circumferential direction, and a coring space is reserved at the center of the crown of the drill bit body; the drill bit body also has a coring channel, the inlet end of the coring channel penetrating through the center of the crown of the drill bit body, and the outlet end of the coring channel penetrating through the circumferential surface of the drill bit body; a detachable coring head is also installed at the inlet end of the coring channel, the head of the coring head is not lower than the surface of the drill bit body, and the head of the coring head also has coring teeth evenly spaced along its circumferential direction; core breaking teeth are also installed in the coring channel, and the core breaking teeth are located at the outlet end of the coring head.

[0006] Furthermore, the number of core-taking teeth is greater than 3.

[0007] Furthermore, the core-retrieving teeth are diamond or wear-resistant teeth that are welded or integrally formed on the head of the core-retrieving head.

[0008] Furthermore, the inlet end of the core sampling channel is a stepped hole, the inner wall of the core sampling head smoothly transitions to the surface of the core sampling channel, and the diameter of the outlet end of the core sampling channel is larger than the diameter of the middle section of the core sampling channel.

[0009] Furthermore, the outlet end of the coring channel is bent axially toward the drill bit body, and the angle between the central axis of the middle section of the coring channel and the central axis of the outlet end of the coring channel is not less than 150°.

[0010] Furthermore, the outlet end of the core sampling channel is located on the circumferential surface of the connector on the drill bit body, or on the end face of the gauge section of the cutter blade, or at the connection between the circumferential surface of the connector on the drill bit body and the end face of the gauge section of the cutter blade.

[0011] Furthermore, a fluid channel is connected between the internal flow channel on the drill bit body and the core sampling channel, and the outlet end of the fluid channel is tangent to the core sampling channel.

[0012] Furthermore, the diameter of the fluid channel inlet is smaller than the diameter of the fluid channel outlet.

[0013] Furthermore, the outlet of the fluid channel is located behind the broken tooth in the core sample.

[0014] The beneficial effects of this utility model are: 1. In this utility model, the coring head is detachably installed at the inlet end of the coring channel. This allows the coring head to be directly replaced when the coring teeth on the coring head are damaged or severely worn during long-term drilling. The cutting teeth on the drill bit will not be scrapped due to damage or wear of the coring teeth during normal chip cutting. This ensures that the cutting teeth on the drill bit can perform coring operations before they are scrapped, thus extending the service life of the coring drill bit.

[0015] 2. Increasing the number of coring teeth improves the core-forming effect. By setting the coring teeth on the coring head and threading the coring head to the inlet end of the coring channel, the drill bit can select and replace coring heads with different inner diameters according to different strata lithologies, and use different numbers and materials of coring teeth to achieve better coring results.

[0016] 3. By adjusting the diameter and length of the core sampler, the core channel of this invention is made longer, resulting in a longer core length. This allows the core to be broken completely with less force, effectively improving the integrity of the core. Increasing the diameter of the core break point in the core channel makes the core break point in this invention larger, effectively ensuring that the core is not damaged secondary by the internal mechanism of the drill bit when it breaks.

[0017] 4. By making the diameter of the fluid channel inlet end smaller than the diameter of the fluid channel outlet end, the fluid velocity inside the drill bit is effectively reduced, thus reducing secondary damage to the core caused by the fluid.

[0018] 5. By bending the outlet end of the coring channel toward the axis of the drill bit body, the angle between the middle section of the coring channel and the outlet end of the coring head channel is increased, which is beneficial for the breaking and removal of the core. Furthermore, by moving the outlet end of the coring channel away from the well wall, it can not only reduce the secondary damage to the core caused by the core scraping and the radial resistance generated by the drill bit rotation, but also reduce the situation where the coring channel is blocked by rock cuttings scraping the well wall during the drill bit reaming operation and entering the coring channel from the outlet end of the coring head channel in the opposite direction. Attached Figure Description

[0019] The accompanying drawings illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the principles of the present invention. These drawings are included to provide a further understanding of the present invention and are incorporated in and constitute a part of this specification.

[0020] Figure 1 This is a structural diagram of the micro coring drill bit provided by this utility model; Figure 2 This is a structural diagram of the core extractor.

[0021] The attached diagram shows the markings and corresponding component names: 1. Drill bit body; 2. Cutting blades; 3. Core sampling space; 4. Core sampling channel; 5. Core sampling head; 6. Fluid channel; 7. Core break teeth. 51. Core-taking teeth. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, it should be noted that, for ease of description, only the parts relevant to the present invention are shown in the accompanying drawings.

[0023] It should be noted that, where there is no conflict, the embodiments and features described in these embodiments can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0024] like Figure 1 , Figure 2 As shown, the present invention provides a micro coring drill bit, including a drill bit body 1, which includes a crown and a connector. The crown of the drill bit body 1 has multiple blades 2, which are arranged at intervals along the circumference of the drill bit body 1. The inner ends of the multiple blades 2 are equidistant from the center of the drill bit body 1. In this case, the inner ends of the multiple blades 2 together constitute a coring space 3. Alternatively, the blades 2 can be divided into two groups, in which multiple blades 2 in each group are evenly spaced along the circumference of the drill bit body 1. The inner ends of the blades 2 in the two groups are not equidistant from the center of the drill bit body 1, but the inner ends of the multiple blades 2 in the same group are equidistant from the center of the drill bit body 1. In this case, the inner ends of the multiple blades 2 closer to the center of the drill bit body 1 together constitute a coring space 3.

[0025] The drill bit body 1 is also provided with a core sampling channel 4. The inlet end of the core sampling channel 4 passes through the center of the crown of the drill bit body 1, and the central axis of the inlet end of the core sampling channel 4 is on the same straight line as the central axis of the core sampling space 3. The outlet end of the core sampling channel 4 passes through the circumference of the drill bit body 1, so that the rock core obtained by the drill bit during drilling can be discharged through the core sampling channel 4. At the same time, in order to ensure that the drill bit can achieve core sampling during drilling, a core sampling head 5 is also installed at the inlet end of the core sampling channel 4. The core sampling head 5 cuts the formation rock during the drilling process to form a rock core that matches the inner diameter of the core sampling head 5. The core sampling head 5 is installed at the inlet end of the core sampling channel 4 in a detachable manner, which not only makes the installation of the core sampling head 5 more convenient, but also allows the core sampling head 5 to be replaced directly after replacement, effectively avoiding the direct scrapping of the drill bit due to damage to the core sampling head 5 but without damage to the cutting teeth on the drill bit.

[0026] To ensure the cutting of the formation rock by the core sampler 5, during installation, the head of the core sampler 5 must be no lower than the crown surface of the drill bit body 1. The head of the core sampler 5 is provided with core teeth 51 evenly spaced along its circumference. The core teeth 51 can be integrally formed with the core sampler 5, or they can be welded onto the core sampler 5. During installation, to avoid uncuttable formation rock between the outer wall of the core sampler 5 and the inner wall of the core space 3, the maximum diameter of the largest annular ring formed by the multiple core teeth 51 on the core sampler 5 is matched to the maximum diameter of the core space 3. After installation, the core teeth 51 on the core sampler 5 are located at the middle of the height of the inner end of the cutter wing 2, or at the upper edge of the inner end of the cutter wing 2, or higher than the upper edge of the inner end of the cutter wing 2. During the drilling process, the core sampler 5 simultaneously cuts the formation rock, forming a core sample that matches the inner diameter of the core sampler 5.

[0027] Taking the depth direction of the core-taking space 5 as a reference, the end of the core-taking space 5 near the core-taking channel 5 is the bottom, and the end of the core-taking space 5 near the inner end of the blade 2 is the top. In this utility model, the height of the core-taking teeth 51 on the core-taking head 5 is higher than half the height of the core-taking space 5. Since the core-taking space 5 is composed of the inner ends of multiple blades 2, that is, the distance between the core-taking teeth 51 and the cutting teeth on the blade 2 is not greater than half the height of the inner end of the blade 2. This makes the height difference between the core-taking teeth 51 and the cutting teeth on the inner end of the blade 2 effectively reduce the cutting intensity of the core-taking teeth 51 and avoid the phenomenon of core-taking teeth 51 falling off and the drill bit removing the core.

[0028] Since the central axis of the inlet end of the core sampling channel 4 is on the same straight line as the central axis of the drill bit body 1, and the outlet end of the core sampling channel 4 passes through the circumference of the drill bit body 1, the inlet end and the middle section of the core sampling channel 4 in this invention are bent. To ensure that the rock core formed by the core cutting head 5 can be smoothly discharged along the core sampling channel 4, the transition between the inlet end and the middle section of the core sampling channel 4 is arc-shaped, and the angle between the inlet end and the middle section of the core sampling channel 4 is greater than 120°. Simultaneously, to ensure core extraction... The core formed by the cutting of the head 5 can be smoothly discharged along the core sampling channel 4. The core sampling channel 4 is also equipped with core breaking teeth 7. The core breaking teeth 7 and the core breaking teeth 51 form the core channel. The core breaking teeth 7 are located at the inlet end of the core sampling channel 4 and are located behind the installation end of the core head 5. After the core head 5 cuts the formation rock into a cylindrical shape, the core breaking teeth 7 squeeze the cylindrical core when it approaches the core breaking teeth 7, breaking the cylindrical core. This allows the broken core to be smoothly discharged along the core sampling channel 4.

[0029] In this invention, the number of core-taking teeth 51 on the core-taking head 5 is greater than three, which effectively improves the stability of core forming compared to the three core-taking teeth on existing core-taking drill bits. In this invention, to extend the lifespan of the core-taking teeth 51 as much as possible, the core-taking teeth 51 can be made of diamond or wear-resistant teeth welded to the head of the core-taking head 5. Of course, other materials can also be used for the core-taking teeth 51 while ensuring their lifespan. When the core-taking teeth 51 and the core-taking head 5 are an integral structure, the material of the core-taking head 5 is the same as the material of the core-taking teeth 51 to ensure the wear resistance of the core-taking teeth 51. In this invention, the number of core-taking teeth 51 on the core-taking head 5 can be adjusted according to actual conditions.

[0030] In this invention, by installing a core head 5 at the inlet end of the core sampling channel 4 and fixing the core teeth 51 on the core head 5, not only is the diameter of the obtained core smaller and the core diameter ratio increased, making it easier for the core to detach from the bottom of the well, increasing the core return rate, and preventing core blockage and settling, but also the encapsulation degree of the core teeth 51 is improved, making the core teeth 51 more secure.

[0031] To ensure that the rock core formed by the coring head 5 can smoothly enter the coring channel 4, the inlet end of the coring channel 4 can be designed as a stepped hole, with the internal thread that engages with the coring head 5 formed on the wall of the stepped hole at the inlet end of the coring channel 4. When the coring head 5 is installed at the inlet end of the coring channel 4, the inner wall of the coring head 5 smoothly transitions with the hole wall of the coring channel 4, thus allowing the rock core formed by the coring head 5 to smoothly enter the coring channel 4. Of course, without affecting the smooth entry of the rock core formed by the coring head 5 into the coring channel 4, the inner diameter of the coring head 5 can also be smaller than the diameter of the coring channel 4 after installation.

[0032] In this invention, to prevent secondary damage to the core sample due to collision with the well wall when discharged through the core sampling channel 4, the outlet end of the core sampling channel 4 is designed to be inclined towards the connection end of the drill bit body 1. Therefore, the core sampling channel 4 has a three-section structure: the inlet end is used to install the core sampler, the middle section is used to transport the core sample, and the outlet end is used to discharge the core sample. Furthermore, the inlet end and the middle section of the core sampling channel 4 are bent, and the middle section and the outlet end are also bent. The angle between the central axis of the middle section and the central axis of the outlet end of the core sampling channel 4 is not less than 150°. This design effectively prevents the core sample from directly colliding with the well wall after being discharged through the core sampling channel 4, thus preventing premature damage to the core sample.

[0033] To prevent damage to the core sample delivered through the coring channel 4 due to the relative movement between the outer surface of the drill bit body 1 and the well wall during drilling, the exit end of the coring channel 4 is preferably located behind the gauge section of the cutter wings 2. It should be noted that, based on the drilling direction of the drill bit (the front of the drill bit body 1), the end of the drill bit body 1 connected to the universal joint is at the rear. During drilling, the diameter of the well wall is larger than the diameter of the annulus formed by the gauge sections of the multiple cutter wings 2. At this time, the diameter of the portion of the drill bit body 1 located behind the gauge sections of the cutter wings 2 is smaller than the diameter of the annulus formed by the multiple gauge sections of the cutter wings 2. This creates an annular space between the portion behind the gauge sections of the cutter wings 2 and the well wall during drilling, and the core sample delivered through the coring channel 4 enters this annular space. This effectively prevents damage to the core sample during drilling, ensuring the quality of the core sample.

[0034] To ensure that the core can enter the annular space through the outlet end of the core sampling channel 4, the outlet end of the core sampling channel 4 can be located directly on the circumferential surface of the joint on the drill bit body 1, or the outlet end of the core sampling channel 4 can be located at the connection between the circumferential surface of the joint on the drill bit body 1 and the end face of the diameter-maintaining section of the cutter wing 2, or the outlet end of the core sampling channel 4 can be located on the end face of the diameter-maintaining section of the cutter wing 2. To ensure that the core will not be damaged secondary due to collision with the well wall, the position of the outlet end of the core sampling channel 4 can be adjusted according to the actual situation.

[0035] In this invention, to ensure that the rock core formed by the cutting of the core head 5 can be smoothly discharged along the core channel 4, a fluid channel 6 is connected between the inner flow channel on the drill bit body 1 and the core channel 4. The fluid channel 6 can transport the mud entering the inner flow channel on the drill bit body 1 to the core channel 4 and flow along the core channel 4. This not only allows the rock core to be transported to the outside of the drill bit body 1 by the flowing mud when it enters the rear section of the core channel 4, but also creates a negative pressure at the inlet end of the core channel 4 and inside the core head 5. This negative pressure can apply a force to the rock core formed by the cutting to the rear end of the core channel 4, so that the rock core formed after being broken by the breaking teeth can move smoothly to the rear end of the core channel 4, avoiding the rock core formed after being broken by the breaking teeth from being directly blocked in the core head 5.

[0036] To prevent the mud entering the rear section of the coring channel 4 through the fluid channel 6 from impacting and damaging the core, the outlet end of the fluid channel 6 is designed to be tangent to the rear section of the coring channel 4. This allows the mud entering the rear section of the coring channel 4 through the fluid channel 6 to flow along the borehole wall of the coring channel 4 as much as possible, thereby effectively preventing the mud delivered by the fluid channel 6 from directly impacting the core and minimizing damage to the core.

[0037] To ensure that the core can be smoothly delivered from the drill bit body 1 through the rear section of the core sampling channel 4, the core sampling channel 4 is designed such that the diameter of the outlet end of the core sampling channel 4 is larger than the diameter of the middle section of the core sampling channel 4, and the diameter of the middle section of the core sampling channel 4 is larger than the diameter of the inlet end of the core sampling channel 4. This provides sufficient space within the core sampling channel 4 for the part corresponding to the core breakage tooth 7 to allow the micro core to break completely. At the same time, the diameter of the outlet end of the core sampling channel 4 can gradually increase from the direction of core discharge, making the discharge of the core from the core sampling channel 4 smoother.

[0038] To further reduce the impact of mud on the core, the diameter of the inlet end of fluid channel 6 can be made smaller than the diameter of the outlet end of fluid channel 6 during the design process, thereby reducing the mud flow rate in fluid channel 6 and further reducing the mud scouring of the core.

[0039] In this invention, the inlet end of the core sampling channel 4 is the front, and the outlet end of the core sampling channel 4 is the rear. In the design of the fluid channel 6, the outlet of the fluid channel 6 is located behind the core breaking teeth 7, so that the core is broken by the core breaking teeth 7 and then transported by mud, avoiding the impact of mud on the core forming quality when the core is not broken.

[0040] To facilitate the installation and removal of the core-retrieving head 5, an internal thread is provided at the inlet end of the core-retrieving channel 4, and an external thread that meshes with the internal thread is provided on the outer circular surface of the core-retrieving tooth 51, so that the core-retrieving head 5 can be installed at the inlet end of the core-retrieving channel 4 by means of threaded connection, making the installation and removal of the core-retrieving head 5 more convenient.

[0041] In this invention, during drilling, the cutting teeth on the cutter blades 2 cut the formation rock. At this time, the part corresponding to the center of the drill bit and the core sampling space 3 is not cut by the cutting teeth on the cutter blades 2. As the drill bit advances, the uncut part at the center of the drill bit enters the core sampling space 3. When the uncut part comes into contact with the core sampling teeth 51 on the core sampling head 5, the uncut part is cut by the core sampling teeth 51 on the core sampling head 5 as the drill bit advances. With the cutting of the core sampling teeth 51, a cylindrical rock core is formed inside the core sampling head 5. As the drill bit continues to advance, the cylindrical core... As the core penetrates deeper into the core sampler 5, when the cylindrical core comes into contact with the core breakage tooth 7, the core breakage tooth 7 compresses the center of the cylindrical core and breaks it. Simultaneously, during drilling, the mud entering the internal flow channel on the drill bit body 1 enters the rear end of the core sampling channel 4 through the fluid channel 6, creating a negative pressure at the inlet end of the core sampling channel 4. This causes the broken core to move towards the rear section of the core sampling channel 4. Once the core has entered the rear section of the core sampling channel 4, the mud inside the core sampling channel 4 pushes the core out of the drill bit body 1.

[0042] When the core-retrieving teeth 51 on the core-retrieving head 5 are worn and the core-retrieving head 5 needs to be replaced, simply remove the damaged core-retrieving head 5 and then screw the new core-retrieving head 5 into the inlet end of the core-retrieving channel 4.

[0043] Those skilled in the art should understand that the above embodiments are merely for clearly illustrating the present invention and are not intended to limit the scope of the present invention. Those skilled in the art can make other changes or modifications based on the above disclosure, and these changes or modifications still fall within the scope of the present invention.

Claims

1. A micro-coring drill bit, characterized in that, The system includes a drill bit body (1), which has blades (2) arranged at intervals in a circumferential direction, and a core sampling space (3) reserved at the center of the crown of the drill bit body (1); the drill bit body (1) is also provided with a core sampling channel (4), the inlet end of the core sampling channel (4) penetrates the center of the crown of the drill bit body (1), and the outlet end of the core sampling channel (4) penetrates the circumferential surface of the drill bit body (1); the inlet end of the core sampling channel (4) is also equipped with a detachable core head (5), the head of the core head (5) is not lower than the surface of the drill bit body (1), and the head of the core head (5) is also provided with core teeth (51) evenly spaced along its circumferential direction; the core sampling channel (4) is also equipped with a core breakage tooth (7), which is located at the outlet end of the core head (5).

2. The micro coring bit of claim 1, wherein, The number of core-taking teeth (51) is greater than 3.

3. The micro-coring drill bit according to claim 1 or 2, characterized in that, The core-taking teeth (51) are diamond or wear-resistant teeth welded to the head of the core-taking head (5).

4. The micro coring drill bit according to claim 1, characterized in that, The inlet end of the core extraction channel (4) is a stepped hole, and the inner wall of the core extraction head (5) smoothly transitions with the surface of the core extraction channel (4).

5. The micro-coring drill bit according to claim 1 or 4, characterized in that, The outlet end of the core sampling channel (4) is bent axially toward the drill bit body (1), and the angle between the central axis of the middle section of the core sampling channel (4) and the central axis of the outlet end of the core sampling channel (4) is not less than 150°.

6. The micro coring drill bit according to claim 5, characterized in that, The diameter of the outlet end of the core sampling channel (4) is larger than the diameter of the middle section of the core sampling channel (4).

7. The micro coring drill bit according to claim 5, characterized in that, The outlet end of the core sampling channel (4) is located on the circumferential surface of the joint on the drill bit body (1), or on the end face of the gauge section of the cutter wing (2), or at the connection between the circumferential surface of the joint on the drill bit body (1) and the end face of the gauge section of the cutter wing (2).

8. The micro coring drill bit according to claim 1, characterized in that, The inner flow channel on the drill bit body (1) is connected to the core sampling channel (4) by a fluid channel (6), and the outlet end of the fluid channel (6) is tangent to the core sampling channel (4).

9. The micro-coring drill bit according to claim 8, characterized in that, The diameter of the inlet end of the fluid channel (6) is smaller than the diameter of the outlet end of the fluid channel (6).

10. The micro-coring drill bit according to claim 8, characterized in that, The outlet of the fluid channel (6) is located behind the core break tooth (7).

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