Underground coal mine small-diameter near-bit measurement-while-drilling system

Abstract

The utility model discloses an underground coal mine small-diameter near-bit measurement-while-drilling system. The system comprises a drill bit, a near-bit measurement module, a wireless transmitting module, a single-bend screw motor, an adapter, a wireless receiving module, an engineering parameter measurement module, a signal transmission drill rod and an orifice computer which are sequentially connected in series. The near-bit measuring module is used for measuring a drilling track and geological parameters, and the wireless transmitting module is responsible for transmitting data to the wireless receiving module and then transmitting the data to the orifice computer through the signal transmission drill rod; the engineering parameter measuring module comprises a pressure sensor, a torque sensor, a vibration sensor and a temperature sensor and is used for monitoring internal parameters of a drill hole. The measuring module is installed close to the drill bit, the distance between a measuring point and the drill bit is shortened to be within 0.5 m, data measuring lag is effectively reduced, and track control precision is improved. The system adopts a miniaturized and intrinsically safe circuit design, meets the explosion-proof requirement of an underground coal mine, and adapts to the environment of a small-diameter drill hole. The modularized structure simplifies system installation and maintenance and improves work efficiency. By means of the system and method, real-time monitoring of the drilling track, geological parameters and internal parameters can be achieved, and the precision and safety of coal mine underground directional drilling are enhanced.

Description

Technical Field

[0001] The utility model belongs to the technical field of measurement-while-drilling instruments for coal mines underground, and relates to a small-diameter near-bit measurement-while-drilling system for coal mines underground. Background Art

[0002] The directional drilling technology for coal mines underground is a key technical means in the process of mine construction and production. It is used to solve problems such as coal seam gas drainage, water injection, grouting, and drainage, and also plays an important role in ensuring coal mine safety production. The directional drilling system relies on measurement-while-drilling technology to monitor the trajectory and geological conditions of the borehole, so as to adjust the trajectory in time to ensure that the borehole reaches the expected target position.

[0003] Measurement While Drilling (MWD) technology realizes the real-time acquisition and transmission of trajectory parameters and geological data during the drilling process by installing a sensor module inside the drill pipe. This system is widely used in energy industries such as oil and natural gas, but its application in coal mines underground is restricted by various environmental and technical factors. Most existing measurement-while-drilling systems for coal mines use conventional measurement equipment, which is usually installed far from the drill bit (5 - 8 meters away). The measurement data has a lag and it is difficult to timely reflect the actual geological conditions in front of the drill bit, resulting in inaccurate trajectory control during the drilling process. Near-bit measurement-while-drilling is the key to solving this problem, which can greatly reduce the difficulty of borehole trajectory control and improve borehole accuracy. The near-bit measurement-while-drilling devices developed in the existing ground oil field cannot be used in coal mines underground. One reason is that the near-bit measurement-while-drilling devices developed in the oil field do not meet the special explosion-proof requirements in coal mines underground; the other reason is that they generally have a large diameter and a long length, which do not meet the requirements of small-diameter directional drilling in coal mines and seriously affect the build-up rate of the positive displacement motor. Content of the Utility Model

[0004] In view of this, the purpose of the utility model is to solve the above problems and provide a small-diameter near-bit measurement-while-drilling system for coal mines underground.

[0005] To achieve the above purpose, the utility model provides the following technical solutions:

[0006] A small-diameter near-bit measurement-while-drilling system for coal mines underground includes a drill bit, a near-bit measurement module, a wireless transmission module, a single-bend positive displacement motor, a swivel joint, a wireless reception module, an engineering parameter measurement module, a signal transmission drill pipe connected in series in sequence, and a hole mouth computer arranged outside the borehole; a water swivel is provided at the tail end of the signal transmission drill pipe, and high-pressure water is accessed through the water swivel to drive the single-bend positive displacement motor to rotate and drive the drill bit to drill.

[0007] The near-bit measurement module is used to measure the borehole trajectory and geological parameters;

[0008] The wireless transmitting module is used to send the data acquired by the near-drill bit measuring module to the wireless receiving module through wireless transmission;

[0009] The engineering parameter measurement module is provided with a pressure sensor, a torque sensor, a vibration sensor, and a temperature sensor for measuring the annular pressure, vibration, drilling pressure, and temperature parameters inside the borehole;

[0010] The structural parts of the near-drill-bit measurement module, wireless transmission module, adapter, wireless receiving module, and engineering parameter measurement module are all made of non-magnetic steel materials to reduce magnetic interference and ensure the accuracy of the measurement data;

[0011] The signal transmission drill rod is used to transmit the data acquired by the engineering parameter measurement module and the wireless transmission module to the orifice computer.

[0012] Further, the near-drill-bit measurement module includes a measurement outer tube, a battery assembly, a gamma measurement module, an inclination measurement module, and a measurement circuit board; one end of the wireless transmitter module is connected to one end of the measurement outer tube through a straight thread; the other end of the measurement outer tube is provided with a connecting thread for connecting the drill bit; an electronic bin frame is provided in the measurement outer tube, one end of the electronic bin frame is connected to the connecting thread end face of the measurement outer tube, and the other end is connected to the wireless transmitter module, thereby being fixed in the measurement outer tube;

[0013] On the outer circle of the electronic warehouse frame, one side is provided with a waist-shaped groove, the other side is provided with three arc-shaped grooves evenly distributed around the circumference, and the middle of the electronic warehouse frame is provided with a water hole eccentric to the center of the measuring outer tube; the battery assembly is waist-shaped and fixed in the waist-shaped groove; the gamma measurement module, the inclination measurement module, and the measurement circuit board are respectively arranged in the three arc-shaped grooves, so that the battery assembly, the gamma measurement module, the inclination measurement module, and the measurement circuit board are arranged in a ring on the electronic warehouse frame;

[0014] A communication hole is provided in the wireless transmitting module for installing connecting wires between the wireless transmitting module and the battery assembly, the gamma measurement module, the inclination measurement module, and the measuring circuit board; the connecting circuits among the wireless transmitting module, the battery assembly, the gamma measurement module, the inclination measurement module, and the measuring circuit board are intrinsically safe circuits; the measurement data of the gamma measurement module and the inclination measurement module are transmitted through the wireless transmitting module in the form of wireless signals.

[0015] Furthermore, the communication hole includes a transverse hole arranged along the axial direction and an inclined hole arranged obliquely, and an aviation plug assembly is provided in the inclined hole, and the aviation plug assembly is used for electrical connection and sealing the inclined hole.

[0016] Furthermore, the battery assembly, gamma measurement module, inclination measurement module, and measurement circuit board are provided with vibration-damping sealing pads in the radial direction and at both ends to prevent the vibration of the hole bottom from damaging the electronic components.

[0017] Further, the battery assembly includes battery cells, a protection board, and a control circuit board, all of which have a waist-shaped cross-section; the protection board is fixedly provided at both ends of the battery cells, and the control circuit board is fixedly provided outside one of the protection boards;

[0018] The battery cells are composed of a number of series-connected battery groups. Each battery group includes an arc-shaped housing and a battery; the arc-shaped housing includes a coaxial outer arc surface and an inner arc surface, and both ends of the outer arc surface and the inner arc surface are connected by arcs to form a waist-shaped structure; a plurality of circumferentially distributed battery holes are provided between the outer arc surface and the inner arc surface; the battery holes penetrate through both ends of the housing; the batteries are arranged in the battery holes; the batteries in each battery group are connected in parallel and then connected in series with the batteries in adjacent battery groups;

[0019] Arc-shaped channels are provided on both the outer arc surface and the inner arc surface. The arc-shaped channels are parallel to the battery holes and penetrate through both ends of the arc-shaped housing. Conductive wires are provided in the arc-shaped channels, and the batteries are connected to each other and to the control circuit board through the conductive wires.

[0020] Further, a sink is provided at the end of the battery hole, and the conductive wire passes through the sink from the battery hole and enters the arc-shaped channel; a connection hole is also provided on the arc-shaped housing, and a connecting rod that penetrates through the entire battery cell and connects the battery cell, the protection board, and the control circuit board into an integrated body is provided in the connection hole.

[0021] Further, each arc-shaped channel is provided between two adjacent battery holes; there are a plurality of connection holes, and each is located between two adjacent battery holes.

[0022] Further, the battery is a rechargeable battery; a charging management circuit, an overvoltage and overcurrent circuit for the battery group, and an undervoltage protection circuit are provided on the control circuit board, and all of them are intrinsically safe circuits; a charging interface, a discharging interface, and a communication interface are provided on the control circuit board.

[0023] Further, the wireless transmission module includes a wireless transmission connector, a protective cover, and a transmitting antenna assembly; a through hole communicating with the water passing hole of the electronic chamber skeleton is provided in the middle of the wireless transmission connector. One end of the wireless transmission connector is connected to one end of the measuring outer tube by a straight thread, and the other end is connected to the single-bend screw motor by a taper thread; the communication hole is provided in the wireless transmission connector, the transmitting antenna assembly is provided in the annular groove, and the protective cover is sleeved on the wireless transmission connector to cover the transmitting antenna assembly therein; a plurality of strip-shaped holes are circumferentially and evenly distributed on the protective cover as channels for wireless signal transmission;

[0024] A fixing ring is provided at the end of the protective cover away from the measuring outer tube. The fixing ring is composed of two halves. The fixing ring is clamped on the wireless transmission connector, and the protective cover is sleeved on the fixing ring and supported by the fixing ring.

[0025] Furthermore, a gap is provided between the transmitting antenna assembly and the protective cover, and the gap is filled with a sealing material.

[0026] The beneficial effects of the present utility model are as follows:

[0027] 1. In the present utility model, the measurement module is designed to be installed close to the drill bit, effectively shortening the distance between the measurement point and the drill bit to within 0.5 m, significantly reducing the lag of measurement data, and enabling the operator to obtain the geological information in front of the drill bit in real time. This design effectively solves the problem of trajectory deviation caused by data lag in the traditional system and greatly improves the trajectory control accuracy during the drilling process.

[0028] 2. The present utility model adopts a lightweight and miniaturized design, enabling the measurement system to operate normally under the condition of small-diameter boreholes. Compared with the large-sized equipment of the traditional measurement-while-drilling system for oil wells, this system greatly reduces the occupied space of the equipment in the borehole, avoids the problem that oversized equipment affects the build-up ability, and ensures greater flexibility during the drilling process.

[0029] 3. The present utility model adopts a modular design, reducing the connection complexity between modules and lowering the risk of failures caused by poor connections. At the same time, the integrated design simplifies the installation and maintenance processes of the system, improves the working efficiency of the equipment, and reduces the downtime and maintenance costs.

[0030] 4. The overall size of the present utility model is small, and it adopts an intrinsically safe circuit design, meeting the special explosion-proof requirements in coal mine underground. It can be directly adapted to the conventional drill tool system in coal mine underground, with strong applicability.

[0031] Other advantages, objectives, and features of the present utility model will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be learned from the practice of the present utility model. The objectives and other advantages of the present utility model can be achieved and obtained through the following specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to make the objectives, technical solutions, and advantages of the present utility model clearer, the present utility model will be described in preferred detail below in conjunction with the drawings, where:

[0033] Figure 1 is a schematic structural diagram of the measurement-while-drilling system for small-diameter near-bit in coal mine underground of the present utility model.

[0034] Figure 2 is a schematic diagram of the near-bit measurement module and the wireless transmission module of the present utility model.

[0035] Figure 3 is Figure 2Layout diagram of the electronic bin skeleton.

[0036] Figure 4 For Figure 2 Schematic diagram of the battery module structure.

[0037] Figure 5 For Figure 4 Schematic diagram of the structure of a single battery cell.

[0038] Figure 6 Schematic diagram of the circuit connection of the battery module.

[0039] Reference numerals: 1 - drill bit; 2 - near-bit measurement module; 3 - wireless transmission module; 4 - single-bend screw motor; 5 - adapter; 6 - wireless reception module; 7 - engineering parameter measurement module; 8 - signal transmission drill pipe; 9 - water swivel; 10 - communication cable; 11 - high-pressure water hose; 12 - explosion-proof computer; 201 - electronic bin skeleton; 202 - battery module; 203 - water through-hole; 204 - battery fixing seat; 205 - gamma measurement module; 206 - vibration damping pad; 207 - combined vibration damping pad; 208 - annular vibration damping pad; 209 - inclination measurement module; 210 - vibration damping pad; 211 - measurement circuit board; 212 - measurement circuit board mounting seat; 301 - straight thread; 302 - communication hole; 303 - transmitting antenna assembly; 304 - fixing ring; 305 - taper thread; 2021 - connecting rod; 2022 - protection board; 2023 - battery pack housing; 2024 - protection board; 2025 - control circuit board. Detailed implementation manners

[0040] The following uses specific specific examples to illustrate the implementation manners of the present utility model. Those skilled in the art can easily understand other advantages and effects of the present utility model from the content disclosed in this specification. The present utility model can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present utility model. It should be noted that the drawings provided in the following embodiments only illustrate the basic concept of the present utility model in a schematic manner. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0041] Among them, the drawings are only for illustrative purposes, showing only schematic diagrams, not physical diagrams, and cannot be understood as a limitation to the present utility model; in order to better illustrate the embodiments of the present utility model, some components in the drawings will be omitted, enlarged or reduced, which do not represent the dimensions of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0042] In the attached drawings of the embodiments of the present utility model, the same or similar reference numerals correspond to the same or similar components; in the description of the present utility model, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the attached drawings. This is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the attached drawings are only for illustrative purposes and cannot be construed as a limitation to the present utility model. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0043] Please refer to Figures 1 to 6 , which is a small-diameter near-bit measurement-while-drilling system for underground coal mines, including a drill bit 1, a near-bit measurement module 2, a wireless transmission module 3, a single-bend screw drill motor 4, a sub 5, a wireless reception module 6, an engineering parameter measurement module 7, a signal transmission drill pipe 8 connected in series in sequence, and an explosion-proof computer 12 arranged outside the borehole; a water swivel 9 is arranged at the tail end of the signal transmission drill pipe 8, and high-pressure water passes through the water swivel 9, the signal transmission drill pipe 8, the engineering parameter measurement module 7, the wireless reception module 6, and the sub 5 in sequence to drive the single-bend screw drill motor 4 to drive the drill bit to drill;

[0044] The near-bit measurement module 2 is used to measure the borehole trajectory and geological parameters;

[0045] The wireless transmission module 3 is mainly composed of a receiving antenna, a housing, an electronic compartment, a cable connector, etc., and is used to transmit the data obtained by the near-bit measurement module to the wireless reception module through wireless transmission;

[0046] The structural parts of the near-bit measurement module 2, the wireless transmission module 3, the sub 5, the wireless reception module 6, and the engineering parameter measurement module 7 are all made of non-magnetic steel materials to reduce magnetic interference and ensure the accuracy of measurement data.

[0047] The engineering parameter measurement module 7 is provided with a pressure sensor, a torque sensor, a vibration sensor, and a temperature sensor, and is used to measure the annulus pressure, vibration, drilling pressure, and temperature parameters inside the borehole;

[0048] The signal transmission drill pipe 8 transmits the data obtained by the engineering parameter measurement module 7 and the wireless transmission module 3 to the explosion-proof computer 12 through the internal communication cable 10;

[0049] The near-bit measurement module 2 includes a measurement outer tube, a battery assembly 202, a gamma measurement module 205, an inclination measurement module 209, and a measurement circuit board 211; one end of the wireless transmission module 3 is connected to one end of the measurement outer tube through a straight thread 301; the other end of the measurement outer tube is provided with a taper thread for connecting to the drill bit 1; an electronic chamber skeleton 201 is arranged inside the measurement outer tube, one end of the electronic chamber skeleton 201 is connected to the taper thread end face of the measurement outer tube, and the other end is connected to the wireless transmission module, so as to be fixed inside the measurement outer tube;

[0050] On the outer circle of the electronic chamber skeleton 201, a waist-shaped groove is arranged on one side, and three circumferentially evenly distributed arc-shaped grooves are arranged on the other side. There is a water passage hole in the middle of the electronic chamber skeleton that is eccentric with the center of the measurement outer tube; the battery assembly 202 is waist-shaped and is fixedly installed in the waist-shaped groove through a battery fixing seat 204; the measurement circuit board 211 is installed in one of the arc-shaped grooves through a measurement circuit board mounting seat 212, and the gamma measurement module 205 and the inclination measurement module 209 are respectively installed in the other two arc-shaped grooves, so that the battery assembly 202, the gamma measurement module 205, the inclination measurement module 209, and the measurement circuit board 211 are annularly arranged on the electronic chamber skeleton 201.

[0051] A communication hole 302 is arranged inside the wireless transmission module 3 for installing the connecting wires between the wireless transmission module 3 and the battery assembly 202, the gamma measurement module 205, the inclination measurement module 209, and the measurement circuit board 211; the connection circuit between the wireless transmission module 3, the battery assembly 202, the gamma measurement module 205, the inclination measurement module 209, and the measurement circuit board 211 is an intrinsically safe circuit; the measurement data of the gamma measurement module 205 and the inclination measurement module 209 are transmitted out in the form of wireless signals through the wireless transmission module 3.

[0052] Among them, the communication hole includes a horizontal hole arranged along the axial direction and an inclined hole arranged obliquely. An aviation plug assembly is arranged in the inclined hole, and the aviation plug assembly is used for electrical connection and sealing the inclined hole.

[0053] The wireless transmission module 3 includes a wireless transmission connector, a protective cover, and a transmitting antenna assembly 303; a through hole communicating with the water passage hole 203 of the electronic chamber skeleton 201 is arranged in the middle of the wireless transmission connector. The wireless transmission connector is connected to one end of the outer tube 1 through a straight thread 301, and the other end is connected to the single-bend screw motor through a taper thread 305; the communication hole 302 is arranged inside the wireless transmission connector, the transmitting antenna assembly 303 is arranged in an annular groove, and the protective cover is sleeved on the wireless transmission connector to cover the transmitting antenna assembly 303 inside; a plurality of strip-shaped holes are evenly distributed on the circumference of the protective cover as the channels for wireless signal transmission.

[0054] A fixing ring 304 is provided at one end of the protective cover away from the measuring outer tube. The fixing ring 304 is composed of two halves and is clamped on the wireless transmitting connector. The protective cover is sleeved on the fixing ring 304 and supported by the fixing ring 304.

[0055] The communication hole 302 includes a horizontal hole arranged axially and an inclined hole arranged obliquely. An aviation plug component is arranged in the inclined hole, and the aviation plug component is used for electrical connection and sealing the inclined hole.

[0056] A gap is provided between the transmitting antenna assembly 303 and the protective cover, and the gap is filled with a sealing material. Vibration damping pads 206, vibration damping pads 210, combined vibration damping pads 207, and annular vibration damping pads 208 are respectively arranged radially and at both ends of the battery assembly 202, the gamma measurement module 205, the inclination measurement module 209, and the measurement circuit board 211 to prevent vibration at the bottom of the hole from damaging electronic components.

[0057] The battery pack 202 includes battery cells with a waist-shaped cross-section, a protection board 2022, a protection board 2024, and a control circuit board 2025; the protection board 2022 and the protection board 2024 are respectively fixedly arranged at both ends of the battery cells, and the control circuit board 2025 is fixedly arranged outside the protection board 2024;

[0058] The battery cells are composed of 4 series-connected battery groups. Each battery group includes a battery group housing 2023 and a battery; the battery group housing 2023 includes a coaxial outer arc surface and an inner arc surface, and both ends of the outer arc surface and the inner arc surface are connected by arcs to form a waist-shaped structure; 4 circumferentially evenly distributed battery holes are provided between the outer arc surface and the inner arc surface, and the number of battery holes can be changed according to the size of the included angle at both ends of the arc surface; the battery holes penetrate through both ends of the housing; the batteries are arranged in the battery holes; the batteries are connected in parallel in groups of 4 and then in series, and the nodes of the two battery groups are respectively connected to the control circuit board 2025 through wires; the number of batteries connected in parallel can be adjusted according to the actual space.

[0059] An outer arc channel and an inner arc channel are respectively arranged on the outer arc surface and the inner arc surface. The outer arc channel and the inner arc channel are both parallel to the battery holes and penetrate through both ends of the battery group housing 2023. Each outer arc channel and inner arc channel is arranged between two adjacent battery holes. Wires are arranged in the outer arc channel and the inner arc channel, and the batteries are connected to each other and to the control circuit board 5 through wires. A sinking groove 3 is provided at the end of the battery hole, and the wire passes through the sinking groove from the battery hole into the outer arc channel and the inner arc channel.

[0060] A connection hole is also provided on the battery group housing 2023. A connecting rod 2021 that penetrates the entire battery unit and connects the battery unit, the protection board, and the control circuit board 5 into one body is arranged in the connection hole, and the connecting rod 2021 plays a role in fixed connection.

[0061] There are three connecting holes, each of which is located between two adjacent battery holes. A connecting rod 2021 is installed in each connecting hole.

[0062] Among them, the battery is a rechargeable lithium battery. The control circuit board 5 is provided with a charging management circuit, an overvoltage and overcurrent circuit for the battery pack, an undervoltage protection circuit, etc., which are used to monitor the voltage and play a role in circuit protection, and all of them are intrinsically safe circuits to meet the special explosion-proof requirements in coal mines; the control circuit board 5 is provided with a charging interface, a discharging interface, a communication interface, etc., and the battery can be charged.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the present technical solution, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A small-diameter near-bit measurement-while-drilling system for underground coal mines, characterized in that: It includes a drill bit, a near-bit measurement module, a wireless transmission module, a single-bend screw motor, a sub, a wireless reception module, an engineering parameter measurement module, a signal transmission drill pipe connected in series successively, and a hole mouth computer arranged outside the borehole; a water swivel is provided at the tail end of the signal transmission drill pipe, and high-pressure water is introduced through the water swivel to drive the single-bend screw motor to rotate and drive the drill bit to drill. The near-bit measurement module is used to measure the borehole trajectory and geological parameters. The wireless transmission module is used to wirelessly transmit the data obtained by the near-bit measurement module to the wireless reception module. Pressure sensors, torque sensors, vibration sensors, and temperature sensors are arranged in the engineering parameter measurement module, which are used to measure the annulus pressure, vibration, weight on bit, and temperature parameters inside the borehole. The structural parts of the near-bit measurement module, wireless transmission module, sub, wireless reception module, and engineering parameter measurement module are all made of non-magnetic steel materials. The signal transmission drill pipe is used to transmit the data obtained by the engineering parameter measurement module and the wireless transmission module to the hole mouth computer.

2. The small-diameter near-bit measurement-while-drilling system for underground coal mines according to claim 1, wherein: The near-bit measurement module includes a measurement outer pipe, a battery assembly, a gamma measurement module, an inclination measurement module, and a measurement circuit board; one end of the wireless transmission module is connected to one end of the measurement outer pipe through a straight thread; a connecting thread is provided at the other end of the measurement outer pipe for connecting the drill bit; an electronic chamber skeleton is arranged inside the measurement outer pipe, one end of the electronic chamber skeleton is connected to the end face of the connecting thread of the measurement outer pipe, and the other end is connected to the wireless transmission module, so as to be fixed inside the measurement outer pipe. On the outer circle of the electronic chamber skeleton, a waist-shaped groove is provided on one side, and three arc-shaped grooves evenly distributed in the circumferential direction are provided on the other side. A water passing hole eccentric to the center of the measurement outer pipe is arranged in the middle of the electronic chamber skeleton; the battery assembly is waist-shaped and is fixedly arranged in the waist-shaped groove; the gamma measurement module, the inclination measurement module, and the measurement circuit board are respectively arranged in the three arc-shaped grooves, so that the battery assembly, the gamma measurement module, the inclination measurement module, and the measurement circuit board are arranged annularly on the electronic chamber skeleton. A communication hole is arranged inside the wireless transmission module for installing the connecting wires between the wireless transmission module and the battery assembly, the gamma measurement module, the inclination measurement module, and the measurement circuit board; the connection circuit between the wireless transmission module, the battery assembly, the gamma measurement module, the inclination measurement module, and the measurement circuit board is an intrinsically safe circuit; the measurement data of the gamma measurement module and the inclination measurement module are transmitted by the wireless transmission module in the form of wireless signals.

3. The measurement-while-drilling system for small-diameter near-bit in coal mine according to claim 2, characterized in that: The communication hole includes a horizontal hole arranged axially and an inclined hole arranged obliquely. An aviation plug assembly is arranged in the inclined hole, and the aviation plug assembly is used for electrical connection and sealing the inclined hole.

4. The measurement-while-drilling system for small-diameter near-bit in coal mine according to claim 2, characterized in that: Vibration damping and sealing gaskets are provided on the radial direction and both ends of the battery assembly, the gamma measurement module, the inclination measurement module, and the measurement circuit board to prevent vibration at the bottom of the hole from damaging electronic components.

5. The measurement-while-drilling system for small-diameter near-bit in coal mine according to claim 2, wherein: The battery assembly includes battery cells, a protection board, and a control circuit board, all of which have a waist-shaped cross-section; the protection board is fixedly arranged at both ends of the battery cells, and the control circuit board is fixedly arranged outside one of the protection boards. The battery unit is composed of a number of serially connected battery packs. Each battery pack includes an arc-shaped housing and a battery. The arc-shaped housing includes an outer arc surface and an inner arc surface arranged coaxially. The two ends of the outer arc surface and the inner arc surface are connected by arcs to form a waist-shaped structure. A plurality of battery holes are evenly distributed circumferentially between the outer arc surface and the inner arc surface. The battery holes penetrate through both ends of the housing. The batteries are arranged in the battery holes. The batteries in each battery pack are connected in parallel and then connected in series with the batteries in adjacent battery packs. Arc-shaped channels are provided on both the outer arc surface and the inner arc surface. The arc-shaped channels are parallel to the battery holes and penetrate through both ends of the arc-shaped housing. Wires are provided in the arc-shaped channels. The batteries are connected to each other and to the control circuit board through the wires.

6. The downhole small-diameter near-bit measurement-while-drilling system for coal mines according to claim 5, wherein: A sink is provided at the end of the battery hole. The wire passes through the sink from the battery hole and enters the arc-shaped channel. A connection hole is also provided on the arc-shaped housing. A connecting rod is provided in the connection hole, which penetrates through the entire battery unit and connects the battery unit, the protection board, and the control circuit board into an integrated body.

7. The measurement-while-drilling system for small-diameter near-bit in coal mine underground according to claim 6, wherein: Each arc-shaped channel is provided between two adjacent battery holes. There are multiple connection holes, and each is located between two adjacent battery holes.

8. The measurement-while-drilling system with a small-diameter near-bit for underground coal mines according to claim 5, characterized in that: The battery is a rechargeable battery. The control circuit board is provided with a charging management circuit, an overvoltage and overcurrent circuit for the battery pack, and an undervoltage protection circuit, and all are intrinsically safe circuits. The control circuit board is provided with a charging interface, a discharging interface, and a communication interface.

9. The measurement-while-drilling system with a small diameter near-bit for underground coal mines according to claim 2, characterized in that: The wireless transmission module includes a wireless transmission connector, a protective cover, and a transmitting antenna assembly. A through hole communicating with the water hole of the electronic chamber skeleton is provided in the middle of the wireless transmission connector. One end of the wireless transmission connector is connected to one end of the measuring outer tube through a straight thread, and the other end is connected to the single-bend screw motor through a taper thread. The communication hole is provided in the wireless transmission connector. The transmitting antenna assembly is provided in the annular groove. The protective cover is sleeved on the wireless transmission connector to cover the transmitting antenna assembly therein. A plurality of strip-shaped holes are evenly distributed circumferentially on the protective cover as channels for wireless signal transmission. A fixing ring is provided at the end of the protective cover away from the measuring outer tube. The fixing ring is composed of two halves. The fixing ring is clamped on the wireless transmission connector, and the protective cover is sleeved on the fixing ring and supported by the fixing ring.

10. The measurement-while-drilling system for small-diameter near-bit in coal mine according to claim 9, wherein: A gap is provided between the transmitting antenna assembly and the protective cover, and the gap is filled with a sealing material.

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