A large-pitch diameter measurement-while-drilling screw drill

Abstract

This application discloses a large-diameter measurement-while-drilling (MWD) screw drill bit, comprising: an outer tube assembly including a drive drill bit mechanism and a screw motor mechanism; the drive drill bit mechanism is a hollow structure, with its top end connected to the rotor of the screw motor mechanism; the rotor is also a hollow structure, with its inner cavity communicating with the inner cavity of the drive drill bit mechanism; an inner tube assembly, passing through and confined within the outer tube assembly; the lower end of the inner tube assembly extending into the drive drill bit mechanism; and a sensor module disposed within the inner tube assembly, with each sensor of the sensor module located on the central axis of the inner tube assembly. The large-diameter MWD screw drill bit proposed in this application improves the measurement accuracy of the sensor module by placing it within the inner tube assembly, and by making the outer tube assembly entirely hollow, allows the inner and outer tube assemblies to be separated after coring, achieving continuous and efficient coring.

Description

Technical Field

[0001] This application relates to the field of screw drilling tools, and more particularly to a large-diameter, measurement-while-drilling screw drilling tool. Background Technology

[0002] In the fields of geotechnical engineering, geological and mineral exploration, deep well drilling and shallow oil and gas exploration, the combination of screw drilling tools and wireline coring is commonly used to carry out core extraction operations.

[0003] Screw drills are downhole power drills that rely on the torque generated by the meshing of the rotor and stator driven by drilling fluid to rotate the drill bit and break the rock. If a complete core sample needs to be obtained during the operation, the screw drill must be lifted out first, and then a wireline coring drill is lowered into the well to perform the coring operation. In addition, conventional screw drills are usually equipped with external sensor modules to monitor borehole inclination, azimuth, depth and downhole operating parameters in real time.

[0004] However, the existing core extraction equipment used in conjunction with these devices has limited functionality. While screw drills can perform directional drilling, they cannot simultaneously complete core extraction, which affects the efficiency of core collection. In addition, the external sensor modules are inaccurate and prone to damage. Summary of the Invention

[0005] The main objective of this application is to provide a large-diameter measurement-while-drilling screw drill bit, which aims to solve the problems of low core sampling efficiency in existing screw drill bits, as well as the technical problems of inaccurate measurement and easy damage of external sensor modules.

[0006] To achieve the above objectives, this application provides a large-diameter measurement-while-drilling (MWD) screw drill bit, comprising: an outer tube assembly including a drive drill bit mechanism and a screw motor mechanism; the drive drill bit mechanism is a hollow structure, with its top end connected to the rotor of the screw motor mechanism; the rotor is a hollow structure, with its inner cavity connected to the inner cavity of the drive drill bit mechanism; the rotor drives the drive drill bit mechanism by rotation, and the drive drill bit mechanism cuts the formation to form a core by rotation; an inner tube assembly, inserted into and confined within the outer tube assembly; the lower end of the inner tube assembly extends into the drive drill bit mechanism for receiving and accommodating the core; and a sensor module, located within the inner tube assembly, with each sensor of the sensor module located on the central axis of the inner tube assembly, and the sensor module used to collect borehole trajectory data and downhole operating condition data.

[0007] Optionally, the transmission drill bit mechanism includes a drill bit assembly and a transmission shaft assembly. The transmission shaft assembly includes: a housing, which is cylindrical, with its upper end connected to the stator of the screw motor mechanism; a transmission shaft unit, which is a hollow structure and passes through the housing; the upper end of the transmission shaft unit is connected to the rotor, and the lower end of the transmission shaft unit is connected to the drill bit assembly; a bearing assembly, through which the transmission shaft unit and the lower end of the housing are rotatably connected; a drilling fluid hole, which is radially opened on the side wall of the transmission shaft unit; and drilling fluid between the housing and the transmission shaft unit flows into the inner cavity of the transmission shaft unit through the drilling fluid hole.

[0008] Optionally, the inner cavity of the drive shaft unit is provided with a first sealing ring, which is located above the drilling fluid hole; a second sealing ring is sleeved on the outer wall of the inner tube assembly; when the inner tube assembly passes through and is confined within the outer tube assembly, the first sealing ring and the second sealing ring seal against each other, dividing the inner cavity of the drive shaft unit into upper and lower chambers.

[0009] Optionally, the inner wall of the first sealing ring and the outer wall of the second sealing ring are both conical surfaces, and the diameter of the two conical surfaces gradually increases from bottom to top.

[0010] Optionally, there are multiple drilling fluid holes, which are evenly arranged circumferentially around the center line of the drive shaft unit.

[0011] Optionally, the drive shaft unit includes a universal joint and a drive shaft body, both of which are hollow structures. The upper end of the universal joint is connected to the rotor, the lower end of the universal joint is connected to the upper end of the drive shaft body, and the lower end of the drive shaft body is connected to the drill bit assembly. The drive shaft body and the housing are rotatably connected through a bearing assembly. The inner cavities of the drill bit assembly, the universal joint, the drive shaft body, and the rotor are all interconnected.

[0012] Optionally, the bearing assembly includes an upper TC radial bearing, a tandem bearing, and a lower TC radial bearing; the upper end, middle and lower end of the drive shaft body are rotatably connected to the housing via the upper TC radial bearing, the tandem bearing and the lower TC radial bearing, respectively.

[0013] Optionally, the upper part of the inner tube assembly where the sensor module is arranged is the mounting section. The mounting section is equipped with a stabilizer. The outer side of the stabilizer has multiple abutment parts made of elastic material. The multiple abutment parts are arranged circumferentially around the center line of the inner tube assembly. When the stabilizer is located inside the outer tube assembly, the multiple abutment parts abut against the inner wall of the outer tube assembly so that the mounting section and the outer tube assembly are coaxially arranged.

[0014] Optionally, there are two stabilizers, located on the upper and lower sides of the installation section.

[0015] Optionally, the inner tube assembly includes an upper spear spring-locking mechanism for connecting to the retrieval rope, and a lower core-locking mechanism for accommodating and holding the core. The upper spear spring-locking mechanism and the lower core-locking mechanism are respectively connected to the upper and lower ends of the installation section through a screw and a threaded sleeve.

[0016] Compared with the prior art, this application has the following beneficial effects: 1. By setting the rotors of the transmission drill bit mechanism and the screw motor mechanism to a hollow structure, the outer tube assembly is also hollow, with a large-diameter inner cavity that can accommodate a larger-diameter inner tube assembly. This allows for the collection of larger-diameter cores with more complete geological information. Simultaneously, the large-diameter inner cavity reduces mud flow resistance, increases mud discharge, and improves cooling and lubrication, thereby increasing overall efficiency. Furthermore, this invention integrates the core-taking function into the inner tube assembly. By using the lower end of the inner tube assembly to receive and hold the core, the screw drill has a synchronous core-taking function. During continuous core-taking operations, there is no need to repeatedly raise and lower the entire drill set; the core-taking operation can be completed simply by removing the inner tube assembly, thus improving core-taking efficiency.

[0017] 2. By placing the sensor module inside the inner tube assembly, with each sensor located on the central axis of the inner tube assembly, the following advantages are achieved: First, it eliminates the measurement error caused by radially eccentric sensor placement, making the sensor measurement data more accurate and reliable. Second, each sensor is kept away from turbulent flow and sand erosion on the pipe wall, resulting in more stable signal acquisition. Third, it does not occupy the drilling fluid flow channel, reducing resistance during drilling fluid flow. Fourth, the sensor module is protected by the inner tube assembly, reducing the risk of sensor module damage. Fifth, by integrating the sensor module into the screw drill bit, the screw drill bit integrates the core sampling function and measurement while drilling function of the inner tube assembly. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of a large-diameter measurement-while-drilling screw drill bit proposed in an embodiment of this application; Figure 2 This is a schematic diagram of the outer tube assembly structure according to an embodiment of this application; Figure 3 This is a schematic diagram of the transmission drill bit mechanism according to an embodiment of this application; Figure 4 This is a schematic diagram of the transmission shaft unit structure according to an embodiment of this application; Figure 5 This is a schematic diagram of the screw motor mechanism structure according to an embodiment of this application; Figure 6 This is a schematic diagram of the inner tube assembly structure according to an embodiment of this application; Figure 7 This is a schematic diagram of the installation section and the upper spear-catching mechanism in an embodiment of this application; Figure 8 This is a schematic diagram of the lower core retrieval mechanism in an embodiment of this application.

[0019] The reference numerals in the attached drawings are as follows: 1. Outer tube assembly; 2. Transmission drill bit mechanism; 21. Drill bit assembly; 221. Housing; 222. Transmission shaft unit; 2221. Universal joint; 2222. Transmission shaft body; 223. Bearing assembly; 2231. Upper TC radial bearing; 2232. String bearing; 2234. Lower TC radial bearing; 224. Drilling fluid hole; 225. First sealing ring; 226. Second sealing ring; 22. Transmission shaft assembly; 3. Screw motor mechanism; 31. Rotor; 32. Stator; 4. Inner tube assembly; 41. Mounting section; 42. Upper spear-catching mechanism; 43. Lower core-catching mechanism; 44. Screw; 45. Threaded sleeve; 5. Centralizer. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0021] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0022] In this application, unless otherwise expressly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0023] Furthermore, if the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0024] Reference Figures 1-8 This application provides a large-diameter measurement-while-drilling (MWD) screw drill bit, which includes: an outer tube assembly 1, comprising a transmission drill bit mechanism 2 and a screw motor mechanism 3; the transmission drill bit mechanism 2 is a hollow structure, and its top end is connected to the rotor 31 of the screw motor mechanism 3; the rotor 31 is a hollow structure, and its inner cavity is connected to the inner cavity of the transmission drill bit mechanism 2; the rotor 31 drives the transmission drill bit mechanism 2 by rotation, and the transmission drill bit mechanism 2 cuts the formation to form a rock core by rotation; an inner tube assembly 4, which is inserted into and confined within the outer tube assembly 1; the lower end of the inner tube assembly 4 extends into the transmission drill bit mechanism 2 for receiving and accommodating the rock core; and a sensor module, which is located within the inner tube assembly 4, with each sensor of the sensor module located on the central axis of the inner tube assembly 4, and the sensor module is used to collect borehole trajectory data and downhole operating condition data.

[0025] This application proposes a large-diameter measurement-while-drilling (MSD) screw drill bit. Before drilling, the inner tube assembly 4 is lowered into the outer tube assembly 1 via a rope. The inner tube assembly 4 and the outer tube assembly 1 are positioned and locked by the drill bit's own spring clip and suspension mechanism (both spring clips and suspension mechanisms are existing technologies). Then, a surface mud pump delivers high-pressure drilling fluid. When the mud enters the engagement chamber between the stator 32 and the hollow rotor 31 of the screw motor mechanism 3, the pressure difference drives the hollow rotor 31 to rotate, converting the liquid pressure energy into mechanical torque. The rotor 31 is designed with a hollow structure to provide a complete through-channel for the inner tube assembly 4. The rotation drives the transmission drill bit mechanism 2, which cuts the formation to form a core. During drilling, the core enters the core tube of the inner tube assembly 4. The circlip and circlip seat hold the core tightly to prevent it from falling out (the core tube, circlip, and circlip seat are all existing technologies). The inner tube assembly 4 is equipped with a positioning signal and core blockage monitoring mechanism (the positioning signal and core blockage monitoring mechanism are existing technologies) to provide real-time feedback on the core sampling status. When the core tube is full, the entire inner tube assembly 4 is lifted to the ground by a retrieval device. The entire drilling tool does not need to be pulled out, achieving continuous core sampling, significantly shortening the operation time, and improving drilling efficiency.

[0026] Specifically, the sensor module is located above the screw motor mechanism 3. The sensor module is a DS560LT miniature orientation sensor, which is a sensor specially equipped in the field of screw drill tools and integrates sensors that measure all parameters.

[0027] Furthermore, the transmission drill bit mechanism 2 includes a drill bit assembly 21 and a transmission shaft assembly 22. The transmission shaft assembly 22 includes: a housing 221, which is cylindrical, and the upper end of the housing 221 is connected to the stator 32 of the screw motor mechanism 3; a transmission shaft unit 222, which is a hollow structure and passes through the housing 221; the upper end of the transmission shaft unit 222 is connected to the rotor 31, and the lower end of the transmission shaft unit 222 is connected to the drill bit assembly 21; a bearing assembly 223, which rotatably connects the transmission shaft unit 222 and the lower end of the housing 221; a drilling fluid hole 224, which is opened radially along the side wall of the transmission shaft unit 222; and the drilling fluid between the housing 221 and the transmission shaft unit 222 flows into the inner cavity of the transmission shaft unit 222 through the drilling fluid hole 224.

[0028] By setting the drive shaft unit 222 as a hollow structure, the inner tube assembly 4 can completely pass through the screw motor mechanism 3 from top to bottom, directly reaching the drill bit of the drill bit assembly 21; the upper end of the drive shaft unit 222 is connected to the rotor 31 and the lower end is connected to the drill bit assembly 21. The entire set of rotating parts is arranged coaxially, and the outer shell 221 supports the drive shaft unit 222 through the bearing assembly 223. Therefore, the drive shaft unit 222 rotates smoothly, reducing the eccentric shaking caused by the multi-segment thread splicing, thereby reducing drilling vibration, protecting the integrity of the rock core, and improving drilling efficiency.

[0029] Furthermore, the inner cavity of the drive shaft unit 222 is provided with a first sealing ring 225, which is located above the drilling fluid hole 224; a second sealing ring 226 is sleeved on the outer wall of the inner tube assembly 4; when the inner tube assembly 4 passes through and is confined within the outer tube assembly 1, the first sealing ring 225 and the second sealing ring 226 seal and abut against each other, dividing the inner cavity of the drive shaft unit 222 into upper and lower chambers.

[0030] By setting the first sealing ring 225 and the second sealing ring 226, when the inner tube assembly 4 is placed in the outer tube assembly 1, the drilling fluid flowing between the rotor 31 and the inner tube assembly 4 will not be able to continue to flow downward. At this time, all the drilling fluid will flow between the rotor 31 and the stator 32, thereby preventing the drilling fluid from flowing downward without driving the rotor, improving the output efficiency of the screw motor mechanism 3, and thus improving the core sampling efficiency.

[0031] Furthermore, the inner wall of the first sealing ring 225 and the outer wall of the second sealing ring 226 are both conical surfaces, and the diameter of the two conical surfaces gradually increases from bottom to top.

[0032] By setting the inner wall of the first sealing ring 225 and the outer wall of the second sealing ring 226 as conical surfaces, the sealing effect is improved, thereby preventing drilling fluid from flowing downward between the rotor 31 and the inner tube assembly 4 without driving the rotor, thereby improving the output efficiency of the screw motor mechanism 3.

[0033] Furthermore, there are multiple drilling fluid holes 224, which are evenly arranged circumferentially around the center line of the drive shaft unit 222.

[0034] By arranging multiple drilling fluid holes 224 evenly around the center line of the drive shaft unit 222, the disturbance to the inner tube assembly 4 when the drilling fluid enters the drive shaft unit 222 is reduced, and the inner tube assembly 4 is prevented from grinding the rock core and damaging the integrity of the rock core, thereby improving the core sampling efficiency.

[0035] Furthermore, the drive shaft unit 222 includes a universal joint 2221 and a drive shaft body 2222, both of which are hollow structures. The upper end of the universal joint 2221 is connected to the rotor 31, the lower end of the universal joint 2221 is connected to the upper end of the drive shaft body 2222, and the lower end of the drive shaft body 2222 is connected to the drill bit assembly 21. The drive shaft body 2222 and the housing 221 are rotatably connected through the bearing assembly 223. The inner cavities of the drill bit assembly 21, the universal joint 2221, the drive shaft body 2222, and the rotor 31 are all interconnected.

[0036] By making the inner cavities of the drill bit assembly 21, universal joint 2221, drive shaft body 2222 and rotor 31 interconnected, the inner tube assembly 4 can sequentially pass through the rotor 31, drive shaft body 2222, universal joint 2221 and drill bit assembly 21, so that the inner tube assembly and outer tube assembly can be separated from each other during the core extraction process.

[0037] Furthermore, the bearing assembly 223 includes an upper TC radial bearing 2231, a tandem bearing 2232, and a lower TC radial bearing 2234; the upper end, middle and lower end of the drive shaft body 2222 are rotatably connected to the housing 221 via the upper TC radial bearing 2231, the tandem bearing 2232 and the lower TC radial bearing 2234, respectively.

[0038] By setting corresponding bearings at the upper, middle and lower ends of the drive shaft body 2222, the rotation of the drive shaft body 2222 can be made smoother, further reducing eccentric sway, thereby protecting the integrity of the rock core.

[0039] Specifically, the stationary rings of the upper TC radial bearing 2231 and the lower TC radial bearing 2234 are fixedly connected to the outer shell 221, the moving rings of the upper TC radial bearing 2231 and the lower TC radial bearing 2234 are fixedly connected to the transmission shaft body 2222, the tandem bearing 2232 is sleeved on the transmission shaft body 2222, and the stationary ring of the tandem bearing 2232 is fixedly connected to the outer shell 221.

[0040] Furthermore, the upper part of the inner tube assembly 4 where the sensor module is arranged is the mounting section 41. The mounting section 41 is provided with a stabilizer 5. The outer side of the stabilizer 5 has multiple abutment parts made of elastic material. The multiple abutment parts are arranged circumferentially around the center line of the inner tube assembly 4. When the stabilizer 5 is located inside the outer tube assembly 1, the multiple abutment parts abut against the inner wall of the outer tube assembly 1 so that the mounting section 41 and the outer tube assembly 1 are coaxially arranged.

[0041] By setting the centering device 5, when the inner tube assembly 4 is located inside the outer tube assembly 1, the centering device 5 ensures that all sensors of the sensor module are located on the central axis of the inner tube assembly, thereby eliminating interference when the sensors are radially eccentrically set and improving the accuracy of the measurement data.

[0042] Specifically, the straightener includes multiple elastic strips made of elastic material, which are evenly arranged around the inner tube assembly. The upper and lower ends of the elastic strips are located on the outer wall of the mounting section 41, and the middle part of the elastic strip protrudes from the inside to the outside to form a supporting part (here, the side of the inner tube assembly that is radially away from the center line of the inner tube assembly is the outer side).

[0043] Furthermore, there are two centralizers 5, which are located on the upper and lower sides of the installation section 41.

[0044] Furthermore, the inner tube assembly 4 includes an upper spear spring-locking mechanism 42 for connecting to the retrieval rope, and a lower core-locking mechanism 43 for accommodating and holding the core. The upper spear spring-locking mechanism 42 and the lower core-locking mechanism 43 are respectively connected to the upper and lower ends of the installation section 41 through a screw 44 and a threaded sleeve 45.

[0045] The installation section 41 is connected between the upper spear-catching mechanism 42 and the lower core-catching mechanism 43 via the screw 44 and the threaded sleeve 45. The threaded connection has the advantages of high connection strength and stable axial load, which enables the upper spear-catching mechanism 42, the installation section 41 and the lower core-catching mechanism 43 to maintain the same axis of rotation, control coaxiality, reduce vibration during drilling, protect the integrity of the core and improve core-catching efficiency.

[0046] Specifically, one end of the screw 44 is connected to the upper spear-catching mechanism 42 or the lower core-catching mechanism 43, the threaded sleeve 45 is connected to the installation section 41, the screw 44 is threadedly connected to the threaded sleeve 45, the threaded sleeve has a threaded hole that extends to the screw body, and an anti-loosening screw is installed in the threaded hole.

[0047] In addition, all screw drill bits except those mentioned above are existing technologies, such as: The upper spear-retrieval mechanism 42 also includes a deployment and retrieval component, a spear-clamp suspension and positioning component, and a positioning signal component. The deployment and retrieval component includes a spearhead and a spearhead holder, and is used for deploying ropes and retrieving the entire inner tube assembly. The spear-clamp suspension and positioning component includes a spear-clamp frame and a spear-clamp plate, and is used to open the spear-clamp and lock it in the outer tube spear-clamp chamber after the inner tube assembly is deployed, thereby suspending and fixing the inner tube assembly. In addition, during the retrieval of the inner tube assembly, the spear-clamp is unlocked by retracting the retrieval tube. The positioning signal component relies on the vibration feedback generated by the spear-clamp settling to provide a signal feedback that the inner tube assembly has been deployed.

[0048] The lower core retrieval mechanism 43 also includes an adjustment and straightening component and a core clamping and retrieval component. The adjustment and straightening component is located inside the inner tube assembly and is used to ensure that the core enters the core tube smoothly. The core clamping and retrieval component includes a core tube, a retaining spring, a retaining spring seat, etc. The core clamping and retrieval component is used to hold the core tightly by the retaining spring during drilling and to prevent the core from falling off during retrieval.

[0049] The outer tube assembly also includes a spring clip suspension and positioning mechanism, which includes a spring clip stop, a spring clip chamber, and a suspension ring. After the inner tube assembly is placed in place, the inner tube spring clip opens and engages with the spring clip chamber, relying on the suspension ring to support the entire weight of the inner tube assembly. The spring clip stop restricts the upward displacement of the spring clip, thereby achieving axial fixation of the inner tube assembly.

[0050] In addition, the outer pipe assembly around the installation section 41 is called the probe outer pipe. The probe outer pipe is a non-magnetic pressure-bearing cylinder, which isolates the electromagnetic interference of the well wall and drill string metal to the measuring sensor. An insulated antenna is formed below the probe outer pipe. The insulated antenna is used to transmit electromagnetic pulse measurement signals. That is, the insulated antenna acts as the transmitting carrier. The downhole monitoring data collected by the sensor module is transmitted to the formation through the insulated antenna. The signal is transmitted to the ground receiving device along the transmission channel between the drill string and the formation, completing the transmission of downhole measurement data to the ground.

[0051] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A large-diameter measuring-while-drilling screw tool, characterized in that, include: The outer tube assembly (1) includes a transmission drill bit mechanism (2) and a screw motor mechanism (3); the transmission drill bit mechanism (2) is a hollow structure, and the top end of the transmission drill bit mechanism (2) is connected to the rotor (31) of the screw motor mechanism (3); the rotor (31) is a hollow structure, and the inner cavity of the rotor (31) and the inner cavity of the transmission drill bit mechanism (2) are interconnected; the rotor (31) drives the transmission drill bit mechanism (2) by rotation, and the transmission drill bit mechanism (2) cuts the strata to form a rock core by rotation; The inner tube assembly (4) is detachably inserted and confined within the outer tube assembly (1); the lower end of the inner tube assembly (4) extends into the transmission drill bit mechanism (2) for receiving and accommodating the rock core. The sensor module is located inside the inner tube assembly (4). Each sensor of the sensor module is located on the central axis of the inner tube assembly (4). The sensor module is used to collect borehole trajectory data and downhole working condition data.

2. The large-diameter measurement-while-drilling screw drill bit as described in claim 1, characterized in that, The transmission drill bit mechanism (2) includes a drill bit assembly (21) and a transmission shaft assembly (22), the transmission shaft assembly (22) including: The outer casing (221) is cylindrical, and the upper end of the outer casing (221) is connected to the stator (32) of the screw motor mechanism (3); The drive shaft unit (222) is a hollow structure and is installed inside the outer shell (221); the upper end of the drive shaft unit (222) is connected to the rotor (31), and the lower end of the drive shaft unit (222) is connected to the drill bit assembly (21). The bearing assembly (223) is used to rotatably connect the lower end of the drive shaft unit (222) and the housing (221); Drilling fluid hole (224) is opened radially on the side wall of the drive shaft unit (222); drilling fluid between the outer shell (221) and the drive shaft unit (222) flows into the inner cavity of the drive shaft unit (222) through drilling fluid hole (224).

3. The large-diameter measurement-while-drilling screw drill bit as described in claim 2, characterized in that, The inner cavity of the drive shaft unit (222) is provided with a first sealing ring (225), which is located above the drilling fluid hole (224); a second sealing ring (226) is sleeved on the outer wall of the inner tube assembly (4); when the inner tube assembly (4) passes through and is confined within the outer tube assembly (1), the first sealing ring (225) and the second sealing ring (226) seal and abut against each other, dividing the inner cavity of the drive shaft unit (222) into two non-communicating chambers.

4. The large-diameter measurement-while-drilling screw drill bit as described in claim 3, characterized in that, The inner wall of the first sealing ring (225) and the outer wall of the second sealing ring (226) are both conical surfaces, and the diameter of the two conical surfaces gradually increases from bottom to top.

5. The large-diameter measurement-while-drilling screw drill bit as described in claim 2, characterized in that, There are multiple drilling fluid holes (224), and the multiple drilling fluid holes (224) are evenly arranged around the center line of the drive shaft unit (222).

6. The large-diameter measurement-while-drilling screw drill bit as described in claim 2, characterized in that, The drive shaft unit (222) includes a universal shaft (2221) and a drive shaft body (2222), both of which are hollow structures. The upper end of the universal shaft (2221) is connected to the rotor (31), the lower end of the universal shaft (2221) is connected to the upper end of the drive shaft body (2222), and the lower end of the drive shaft body (2222) is connected to the drill bit assembly (21). The drive shaft body (2222) and the outer shell (221) are rotatably connected by a bearing assembly (223). The inner cavities of the drill bit assembly (21), universal joint (2221), drive shaft body (2222), and rotor (31) are all interconnected.

7. The large-diameter measurement-while-drilling screw drill bit as described in claim 6, characterized in that, The bearing assembly (223) includes an upper TC radial bearing (2231), a tandem bearing (2232), and a lower TC radial bearing (2234); the upper end, middle and lower end of the drive shaft body (2222) are rotatably connected to the housing (221) through the upper TC radial bearing (2231), the tandem bearing (2232) and the lower TC radial bearing (2234), respectively.

8. The large-diameter measurement-while-drilling screw drill bit as described in claim 1, characterized in that, The upper part of the inner tube assembly (4) where the sensor module is arranged is the mounting section (41). The mounting section (41) is provided with a stabilizer (5). The outside of the stabilizer (5) has multiple abutment parts made of elastic material. The multiple abutment parts are arranged circumferentially around the center line of the inner tube assembly (4). When the stabilizer (5) is located inside the outer tube assembly (1), the multiple abutment parts abut against the inner wall of the outer tube assembly (1) so that the mounting section (41) and the outer tube assembly (1) are coaxially arranged.

9. The large-diameter measurement-while-drilling screw drill bit as described in claim 8, characterized in that, There are two straighteners (5), which are located on the upper and lower sides of the installation section (41).

10. The large-diameter measurement-while-drilling screw drill bit as described in claim 8, characterized in that, The inner tube assembly (4) includes an upper spear spring-locking mechanism (42) for connecting to the retrieval rope, and a lower core-locking mechanism (43) for accommodating and holding the core. The upper spear spring-locking mechanism (42) and the lower core-locking mechanism (43) are respectively connected to the upper and lower ends of the installation section (41) through a screw (44) and a threaded sleeve (45).

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