A coring bit for pressure-maintained coring of friable coal seams

Abstract

The utility model discloses a coring bit for fragile coal seam pressure maintaining coring, relates to pressure maintaining coring structure technical field, including drill bit body, the bottom end of drill bit body includes coring cavity, and the upper end of coring cavity is linked with pressure maintaining cavity, wherein, the outer wall profile of coring cavity is gradually larger from bottom to top and is the streamline structure, and the bottom of flow channel is higher than the bottom of coring cavity, the utility model discloses the outer wall profile of coring cavity is gradually larger from bottom to top and is the streamline structure, make the bottom of flow channel higher than the bottom of coring cavity, reach the problem of little core blocking and grinding and prevent the purpose that liquid enters the inside of tool and erodes and pollutes sample.

Description

Technical Field

[0001] This utility model relates to the field of pressure-maintaining coring structure technology, specifically to a coring drill bit for pressure-maintaining coring of fragile coal seams. Background Technology

[0002] Core drilling is a technique used in geological exploration to obtain formation samples. Core drilling tools drill into the formation to obtain samples that can be used for analysis, providing data support for geological research and resource assessment. In coal seam exploration, core drilling is the primary method for obtaining coal seam samples, which can reflect information such as coal quality, seam thickness, and distribution. However, the physical characteristics of coal seams place high demands on core drilling operations. Coal seams are brittle and easily eroded during drilling, leading to sample loss and contamination. Furthermore, coal seam samples are prone to breakage and fragmentation during retrieval to the surface, resulting in a low core recovery rate.

[0003] In coal seam coring operations, conventional PDC coring bits suffer from the following structural and performance issues: the bit's shape easily causes coal seam debris generated during drilling to accumulate inside the tool, leading to core blockage and grinding problems; the water-tightening effect of the bit's flow channels is poor, allowing liquid to enter the tool and erode and contaminate the sample; furthermore, coal seams are fragile, and samples are easily damaged by drill vibration when entering the tool. These factors collectively make it difficult to effectively apply commonly used coring techniques in coal seams, increasing the difficulty of coring, reducing the core yield, and affecting the efficiency and quality of coal seam coring operations.

[0004] In view of the above, this application is hereby submitted. Utility Model Content

[0005] The purpose of this invention is to provide a core drilling bit for pressure-maintaining core sampling in fragile coal seams. By setting the outer wall contour of the core sampling cavity to a streamlined structure that gradually increases in size from bottom to top, the bottom of the flow channel is higher than the bottom of the core sampling cavity. This solves the problem in the prior art where the shape of the drill bit body easily causes coal seam debris generated during drilling to gather inside the tool, resulting in core blockage and poor water-proofing effect of the drill bit flow channel arrangement, allowing liquid to enter the tool and erode and contaminate the sample.

[0006] This utility model embodiment is achieved through the following technical solution: This utility model embodiment provides a core drilling bit for pressure-maintaining core sampling in fragile coal seams, including a drill bit body, the bottom end of the drill bit body including a core sampling cavity, and the upper end of the core sampling cavity communicating with a pressure-maintaining cavity; The outer wall of the heart-harvesting cavity has a streamlined structure that gradually increases in size from bottom to top, and the bottom of the flow channel is higher than the bottom of the heart-harvesting cavity.

[0007] Optionally, the heart-harvesting cavity includes an upper cavity and a lower cavity, with the upper end of the upper cavity connected to a pressure-holding cavity and its bottom connected to the lower cavity; The inner diameter of the lower cavity is smaller than that of the upper cavity, and the inner diameter of the upper cavity is smaller than that of the pressure-holding cavity. The central axes of the upper cavity, lower cavity, and pressure-holding cavity coincide.

[0008] Optionally, at least two ribs are provided on the outer side of the drill bit body, with a gap between adjacent ribs.

[0009] Optionally, four prisms are provided, and the four prisms are arranged in a circular array along the outer wall contour of the heart-removal cavity.

[0010] Optionally, multiple PDC teeth are arranged on the outer surface of each prism plate.

[0011] Optionally, the bottom end of the single prism is flush with the bottom end of the core extraction cavity.

[0012] Optionally, the single prism plate is streamlined along the outer contour of the heart-harvesting cavity.

[0013] Optionally, the single prism plate includes a first inclined plate, a vertical plate and a second inclined plate, with the bottom end of the first inclined plate flush with the bottom end of the core extraction cavity; The bottom of the vertical plate is connected to the top of the first inclined plate, and its top is connected to the bottom of the second inclined plate.

[0014] Optionally, the PDC gear is disposed on the outer surface of the first inclined plate and the vertical plate.

[0015] Optionally, the PDC tooth has an outwardly convex arc-shaped structure, and there is a gap between two adjacent PDC teeth.

[0016] Compared with the prior art, the embodiments of this utility model have the following advantages and beneficial effects: 1. The coring drill bit for pressure-maintaining coring in fragile coal seams provided in this embodiment of the invention allows the coring cavity to directly contact the formation during drilling to obtain samples. Due to the streamlined outer wall profile of the coring cavity, drilling debris is automatically pushed outwards, preventing it from entering the tool and thus reducing the problems of core clogging and grinding. Simultaneously, the bottom of the flow channel is higher than the bottom of the coring cavity, optimizing the flow channel arrangement, improving the water-proofing effect, and effectively preventing liquid from entering the tool and eroding and contaminating the sample. After the sample is formed in the coring cavity, it is transferred to the pressure-maintaining cavity through communication with it. The pressure-maintaining cavity maintains internal pressure, preventing external liquid from entering and thus protecting the sample from contamination.

[0017] 2. In this embodiment of the utility model, by setting the inner diameter of the lower cavity to be smaller than that of the upper cavity, when the sample is transferred from the lower cavity to the upper cavity, the space restriction on the sample is reduced due to the larger inner diameter of the upper cavity, thereby reducing breakage caused by friction and compression. At the same time, this size difference also helps to form a buffer area, making the sample more stable during the transfer process and reducing breakage caused by sudden pressure changes or impacts.

[0018] 3. In this embodiment of the utility model, by setting multiple prism plates, the gaps between the prism plates can serve as fluid channels to guide the liquid and debris generated during drilling to flow outward, thereby reducing the contamination of the drill bit by debris and liquid. At the same time, the prism plates increase the structural strength of the drill bit, improve the stability of operation, and reduce the risk of sample breakage due to vibration.

[0019] In general, the embodiments of this utility model provide a core drilling bit for pressure-maintaining core sampling in fragile coal seams. By setting the outer wall contour of the core sampling cavity to a streamlined structure that gradually increases in size from bottom to top, the bottom of the flow channel is higher than the bottom of the core sampling cavity, thereby reducing the problems of core blockage and core grinding and preventing liquid from entering the tool and eroding and contaminating the sample. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the drill bit body structure in the prior art; Figure 2 This is a cross-sectional view of a coring drill bit used for pressure-maintaining coring in fragile coal seams, as described in this embodiment of the present invention. Figure 3 This is a three-dimensional structural diagram of a coring drill bit used for pressure-maintaining coring in fragile coal seams, as described in this utility model embodiment. Figure 4 This is a top view of a coring drill bit used for pressure-maintaining coring in fragile coal seams, as described in this embodiment of the present invention.

[0022] The attached diagram shows the markings and corresponding component names: 1-Core extraction cavity, 2-Pressure holding cavity, 3-Flow channel, 4-Upper cavity, 5-Lower cavity, 6-Rhomboid plate, 7-Outer wall, 8-PDC gear, 9-First inclined plate, 10-Vertical plate, 11-Second inclined plate. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can typically be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0025] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0026] In the description of this utility model, it should be noted that the terms "first", "second", "third", etc. are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance. Example

[0027] Reference Figure 1 As shown, in the prior art, the bottom contour of the core-taking cavity 1 converges inward, and the bottom of the flow channel 3 is usually flush with the bottom of the core-taking cavity 1. Debris and liquid easily enter the core-taking cavity 1, leading to core blockage and grinding problems. Liquid can also enter the tool, eroding and contaminating the sample. To solve the above problems, this utility model embodiment provides a core-taking drill bit for pressure-maintaining core taking in fragile coal seams, in conjunction with reference to... Figure 2 and Figure 3 As shown, the drill bit body includes a core-taking cavity 1 at its bottom end, and the upper end of the core-taking cavity 1 is connected to a pressure-holding cavity 2. The outer wall 7 of the core-taking cavity 1 has a streamlined structure that gradually increases in size from bottom to top, and the bottom of the flow channel 3 is higher than the bottom of the core-taking cavity 1.

[0028] Specifically, the core-taking chamber 1 is located at the bottom end of the drill bit body and is the part that directly contacts the formation and obtains the sample. Its outer wall 7 is designed with a streamlined structure that gradually increases in size from bottom to top, which helps to reduce the accumulation of debris inward and avoid core clogging and grinding problems. The pressure-holding chamber 2 is located at the upper end of the core-taking chamber 1 and is connected to the core-taking chamber 1. Its main function is to maintain internal pressure and prevent external liquid from entering, thereby protecting the sample from contamination. The flow channel 3 is set inside the core-taking chamber 1, and its bottom is higher than the bottom of the core-taking chamber 1. This structure optimizes the arrangement of the flow channel 3, prevents external liquid from entering in reverse, improves the water-proofing effect, and prevents liquid from entering the tool and eroding and contaminating the sample.

[0029] During drilling, the core sample chamber 1 directly contacts the formation to obtain a sample. Due to the streamlined outer wall 7 of the core sample chamber 1, drilling debris is automatically pushed outwards, preventing it from entering the tool and reducing core clogging and grinding issues. Simultaneously, the bottom of the flow channel 3 is higher than the bottom of the core sample chamber 1, improving water isolation and preventing liquid from entering the tool and contaminating the sample. After the sample is formed in the core sample chamber 1, it is transferred to the pressure-holding chamber 2 through communication with it. The pressure-holding chamber 2 maintains internal pressure, preventing external liquid from entering and thus protecting the sample from contamination.

[0030] In addition, coal seams are fragile, and samples are easily damaged by drill bit vibration when entering the tool. To solve this problem, the core sampling cavity 1 of this utility model embodiment includes an upper cavity 4 and a lower cavity 5. The upper end of the upper cavity 4 is connected to the pressure holding cavity 2, and its bottom is connected to the lower cavity 5. The inner diameter of the lower cavity 5 is smaller than the inner diameter of the upper cavity 4, and the inner diameter of the upper cavity 4 is smaller than the inner diameter of the pressure holding cavity 2. The central axes of the upper cavity 4, the lower cavity 5, and the pressure holding cavity 2 coincide.

[0031] In this embodiment of the invention, the lower cavity 5 is the part that directly contacts the formation during the coring process and is responsible for obtaining the sample. It allows the sample to form and be collected during drilling. The upper cavity 4 is located above the lower cavity 5 and serves to receive the sample transferred from the lower cavity 5 and provide a temporary storage space for the sample until it is transferred to the pressure-holding cavity 2. The pressure-holding cavity 2 is located above the coring cavity 1 and serves to maintain internal pressure, prevent external liquid from entering, thereby protecting the sample from contamination and ensuring stable sample transfer. In this embodiment of the invention, by setting the inner diameter of the lower cavity 5 to be smaller than that of the upper cavity 4, when the sample is transferred from the lower cavity 5 to the upper cavity 4, the larger inner diameter of the upper cavity 4 reduces the space restriction on the sample, thereby reducing breakage caused by friction and compression. At the same time, this dimensional difference also helps to form a buffer zone, making the sample transfer more stable and reducing breakage caused by sudden pressure changes or impacts. Coal seam samples are more prone to breakage when disturbed, and this structural dimensional difference setting can reduce the disturbance of the sample during the transfer process, ensuring that the sample remains as original as possible during coring. The central axes of the upper cavity 4, lower cavity 5 and pressure holding cavity 2 are aligned, ensuring the straightness and stability of the sample during the transfer process, reducing the sample offset and vibration during the transfer process, thereby improving the integrity of the sample and the accuracy of coring.

[0032] Furthermore, in conjunction with reference Figure 2 , Figure 3 and Figure 4 As shown, at least two ribs 6 are provided on the outer side of the drill bit body, with a gap between adjacent ribs 6. The gap between the ribs 6 can serve as a fluid channel, guiding the liquid and debris generated during drilling to flow outward, thereby reducing the contamination of the drill bit interior by debris and liquid. At the same time, the ribs 6 increase the structural strength of the drill bit, improve operational stability, and reduce the risk of sample breakage due to vibration.

[0033] It should be noted that the number of prism plates 6 is not limited here. Specifically, it can be set according to the dimensions of the outer side of the drill bit body, such as three, four, or five plates. The gap between adjacent prism plates 6 can be the same or different. Exemplarily, in this embodiment of the present invention, in conjunction with reference to... Figure 3 and Figure 4 As shown, four prism plates 6 are provided, and the four prism plates 6 are arranged in a ring array along the outline of the outer wall 7 of the core extraction cavity 1. This structure can form four fluid channels.

[0034] In a preferred embodiment of this invention, the bottom end of the single prism plate 6 is flush with the bottom end of the core-taking cavity 1. Specifically, the prism plate 6 is a protruding structure on the outside of the drill bit body, used to withstand wear and impact during drilling. Setting the bottom end of the prism plate 6 to be flush with the bottom end of the core-taking cavity 1 helps to maintain the balance and stability of the drill bit. The plate provides additional structural support, enhancing the strength and durability of the drill bit body.

[0035] More preferably, the single prism plate 6 is arranged in a streamlined shape along the outer contour of the core cavity 1, that is, multiple prism plates 6 can form a conical structure, which can reduce the surface area of ​​the drill bit in contact with the formation, thereby reducing the frictional resistance during drilling and increasing the drilling speed.

[0036] For example, in conjunction with reference Figure 2 and Figure 3 As shown, the single-piece prism plate 6 includes a first inclined plate 9, a vertical plate 10, and a second inclined plate 11. The bottom end of the first inclined plate 9 is flush with the bottom end of the core-taking cavity 1. The bottom of the vertical plate 10 is connected to the top of the first inclined plate 9, and its top is connected to the bottom of the second inclined plate 11. Specifically, the first inclined plate 9 helps maintain the balance of the drill bit and ensures that fluid and debris can be smoothly discharged. The inclination angle of the first inclined plate 9 helps guide the fluid and debris to flow outward, reducing the accumulation of debris inside the drill bit. The vertical plate 10 provides structural support, enhances the overall strength of the prism plate 6, and also helps guide and discharge the fluid. The inclination of the second inclined plate 11 helps to further guide the fluid and debris to flow outward, reduce fluid resistance, and improve fluid discharge efficiency.

[0037] Furthermore, referring to Figure 2 As shown, multiple PDC teeth 8 are arranged on the outer surface of each prism plate 6. The PDC teeth 8 can be cutting elements made of polycrystalline diamond material, which has extremely high hardness and wear resistance. They are arranged on the outer surface of each prism plate 6 to form the cutting edge of the drill bit. The high hardness and wear resistance of the PDC teeth 8 enable them to effectively cut formations, including hard rock and fragile coal seams, and improve drilling efficiency.

[0038] It should be noted that the number, shape, size, and gap between two adjacent PDC teeth 8 are not limited here. They can be set according to actual needs, as long as sufficient drilling strength can be achieved.

[0039] More preferably, the PDC tooth 8 is disposed on the outer surface of the first inclined plate 9 and the vertical plate 10. The PDC tooth 8 has an outwardly convex arc-shaped structure, and there is a gap between two adjacent PDC tooth 8s. The outwardly convex arc-shaped structure helps to improve cutting efficiency, while reducing the impact and vibration on the formation, and also helps to extend the service life of the drill bit. The function of the PDC tooth 8 disposed on the first inclined plate 9 is to drill downwards quickly, and the function of the PDC tooth 8 disposed on the outer surface of the vertical plate 10 is to trim the well wall and maintain a constant inner diameter. As a preferred embodiment of this utility model, in order to improve processing efficiency, the gap between two adjacent PDC tooth 8s with the same function can be set to be equal, and the shape and size of each PDC tooth 8 can be set to be the same.

[0040] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model. It should be noted that the structures or components illustrated in the accompanying drawings are not necessarily drawn to scale, and descriptions of well-known components, processing techniques, and processes are omitted to avoid unnecessarily limiting the utility model.

Claims

1. A coring drill bit for pressure-maintaining coring in fragile coal seams, comprising a drill bit body, characterized in that, The bottom end of the drill bit body includes a core-taking cavity (1), and the upper end of the core-taking cavity (1) is connected to a pressure-holding cavity (2). The outer wall (7) of the core extraction cavity (1) has a streamlined structure that gradually increases in size from bottom to top, and the bottom of the flow channel (3) is higher than the bottom of the core extraction cavity (1). The core extraction cavity (1) includes an upper cavity (4) and a lower cavity (5). The upper end of the upper cavity (4) is connected to the pressure-holding cavity (2), and its bottom is connected to the lower cavity (5). The inner diameter of the lower cavity (5) is smaller than the inner diameter of the upper cavity (4), and the inner diameter of the upper cavity (4) is smaller than the inner diameter of the pressure-holding cavity (2).

2. A coring drill bit for pressure-maintaining coring in fragile coal seams according to claim 1, characterized in that, The central axes of the upper cavity (4), lower cavity (5) and pressure-holding cavity (2) coincide.

3. A coring drill bit for pressure-maintaining coring in fragile coal seams according to claim 1, characterized in that, The drill bit body has at least two ribs (6) on its outer side, and there is a gap between two adjacent ribs (6).

4. A coring drill bit for pressure-maintaining coring in fragile coal seams according to claim 3, characterized in that, The prism plate (6) is provided in four pieces, and the four prism plates (6) are arranged in a ring array along the outline of the outer wall (7) of the heart-taking cavity (1).

5. A coring drill bit for pressure-maintaining coring in fragile coal seams according to claim 3, characterized in that, Multiple PDC teeth (8) are arranged on the outer surface of each prism plate (6).

6. A coring drill bit for pressure-maintaining coring in fragile coal seams according to claim 3, characterized in that, The bottom end of the single prism plate (6) is flush with the bottom end of the core extraction cavity (1).

7. A coring drill bit for pressure-maintaining coring in fragile coal seams according to claim 5, characterized in that, The single prism plate (6) is arranged in a streamlined shape along the outer contour of the core extraction cavity (1).

8. A coring drill bit for pressure-maintaining coring in fragile coal seams according to claim 7, characterized in that, The single prism plate (6) includes a first inclined plate (9), a vertical plate (10), and a second inclined plate (11), with the bottom end of the first inclined plate (9) being flush with the bottom end of the core extraction cavity (1); The bottom of the vertical plate (10) is connected to the top of the first inclined plate (9), and its top is connected to the bottom of the second inclined plate (11).

9. A coring drill bit for pressure-maintaining coring in fragile coal seams according to claim 8, characterized in that, The PDC gear (8) is disposed on the outer surface of the first inclined plate (9) and the vertical plate (10).

10. A coring drill bit for pressure-maintaining coring in fragile coal seams according to claim 9, characterized in that, The PDC tooth (8) has an outwardly convex arc-shaped structure, and there is a gap between two adjacent PDC teeth (8).

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