阅读说明：本技术 一种双谐振型近钻头信号短传系统 (Double-resonance near-bit signal short transmission system ) 是由 陈庆 江涛 刘昶 胡皓然 杨思谛 余沐阳 李红斌 于 2020-05-25 设计创作，主要内容包括：本发明公开一种双谐振型近钻头信号短传系统,包括：钻头、螺杆总成、第一谐振耦合短节、第二谐振耦合短节以及自适应调频单元；第一谐振耦合短节一端与螺杆总成一端连接；第一谐振耦合短节另一端与钻头连接；第一谐振耦合短节包括第一轴向磁场谐振耦合线圈；第二谐振耦合短节的一端与螺杆总成另一端连接；第二谐振耦合短节包括第二轴向磁场谐振耦合线圈；自适应调频单元通过调节第一、第二轴向磁场谐振耦合线圈的工作频率,以将采集到的钻头处的信息从第一轴向磁场谐振耦合线圈,穿过螺杆总成,通过磁场谐振耦合至第二轴向磁场谐振耦合线圈,实现跨过螺杆总成的非接触式短传。本发明通过双边磁场谐振,增强发射和接收磁场的强度,提高传输效率。(The invention discloses a double-resonance type near-bit signal short transmission system, which comprises: the self-adaptive frequency modulation device comprises a drill bit, a screw assembly, a first resonant coupling short section, a second resonant coupling short section and a self-adaptive frequency modulation unit; one end of the first resonant coupling short section is connected with one end of the screw assembly; the other end of the first resonant coupling short section is connected with a drill bit; the first resonant coupling nipple comprises a first axial magnetic field resonant coupling coil; one end of the second resonant coupling short section is connected with the other end of the screw assembly; the second resonant coupling short section comprises a second axial magnetic field resonant coupling coil; the self-adaptive frequency modulation unit adjusts the working frequency of the first axial magnetic field resonance coupling coil and the second axial magnetic field resonance coupling coil to enable the collected information at the drill bit to pass through the screw assembly from the first axial magnetic field resonance coupling coil and be coupled to the second axial magnetic field resonance coupling coil through magnetic field resonance, and non-contact short transmission crossing the screw assembly is achieved. The invention enhances the strength of the transmitting and receiving magnetic fields and improves the transmission efficiency through bilateral magnetic field resonance.)

1. A dual-resonance near-bit signal short pass system, comprising: the self-adaptive frequency modulation device comprises a drill bit, a screw assembly, a first resonant coupling short section, a second resonant coupling short section and a self-adaptive frequency modulation unit;

one end of the first resonant coupling nipple is connected with one end of the screw assembly;

the other end of the first resonant coupling short section is connected with the drill bit; the first resonant coupling nipple comprises a first axial magnetic field resonant coupling coil;

one end of the second resonant coupling short section is connected with the other end of the screw assembly; the second resonant coupling nipple comprises a second axial magnetic field resonant coupling coil;

the self-adaptive frequency modulation unit is used for adjusting the working frequency of the first axial magnetic field resonance coupling coil and the working frequency of the second axial magnetic field resonance coupling coil so as to enable the acquired information at the drill bit to pass through the screw assembly from the first axial magnetic field resonance coupling coil and be coupled to the second axial magnetic field resonance coupling coil through magnetic field resonance, and therefore non-contact short transmission crossing over the screw assembly is achieved;

the short transmission system adopts KHZ-level medium-frequency magnetic field coupling by means of an axial coupling coil; the magnetic field carrying the information of the drill bit completes signal transmission through the first axial magnetic field resonance coupling coil, the screw assembly and the second axial magnetic field resonance coupling coil, and the transmission process is not influenced by the stratum condition; the short transmission system adopts adjustable resonance drive to enhance coil magnetic field signals and is suitable for various underground working conditions.

2. The dual resonant near-bit signal short propagation system of claim 1, wherein the adaptive frequency modulation unit comprises: the device comprises a first driving module, a first signal modulation module, a first resonance compensation module and a second resonance compensation module; the first driving module, the first signal modulation module, the first resonance compensation module and the second resonance compensation module are positioned in the first resonance coupling short section;

the first signal modulation module is used for sequentially filtering, amplifying and modulating the acquired information at the drill bit; the modulated signal generates a corresponding sinusoidal signal through a first driving module and is transmitted to a first axial magnetic field resonance coupling coil through a first resonance compensation module; and the first axial magnetic field resonance coupling coil sends out a magnetic field signal to pass through the screw assembly, and the magnetic field signal is transmitted to the second resonance coupling short section in a non-contact manner.

3. The dual resonant near-bit signal short propagation system of claim 2, wherein the adaptive frequency tuning unit further comprises: the second signal demodulation module, the third resonance compensation module and the fourth resonance compensation module; the second signal demodulation module, the third resonance compensation module and the fourth resonance compensation module are positioned in the second resonance coupling short section;

the second axial magnetic field resonance coupling coil induces a magnetic field signal passing through the screw assembly under the resonance frequency; the second axial magnetic field resonance coupling coil, the third resonance compensation module and the fourth resonance compensation module form a resonance loop, and the resonance frequency of the resonance loop is the same as that of the first axial magnetic field resonance coupling coil so as to increase the coupling strength among magnetic fields; the second signal demodulation module analyzes information at the drill bit from the magnetic field signal induced by the second axial magnetic field resonance coupling coil.

4. The dual-resonance type near-bit signal short transmission system according to any one of claims 1 to 3, wherein the first resonance compensation module, the second resonance compensation module, the third resonance compensation module and the fourth resonance compensation module form a resonance matching circuit;

when the first resonant coupling short section transmits a signal, the resonant matching circuit enables the first axial magnetic field resonant coupling coil to work in a resonant signal transmitting state; when the second resonant coupling short section receives signals, the resonant matching circuit enables the second axial magnetic field resonant coupling coil to work in a resonant signal receiving state;

when the second resonant coupling short section transmits a signal, the resonant matching circuit enables the second axial magnetic field resonant coupling coil to work in a resonant signal transmitting state; when the first resonant coupling short section receives a signal, the resonant matching circuit enables the first axial magnetic field resonant coupling coil to work in a resonant signal receiving state; the induction magnetic field intensity is enhanced and the transmission efficiency is improved through double resonance;

during working, the first resonant coupling short section and the second resonant coupling short section are driven and receive signals through the resonant matching circuit, time division multiplexing is achieved, and two-way communication can be achieved.

5. The dual resonance type near bit signal short propagation system according to any one of claims 1 to 3, wherein the screw assembly has a length of 10m-35 m.

6. The dual-resonant near-bit signal short transmission system according to claim 2 or 3, wherein the adaptive frequency modulation unit pre-emits a section of composite waveform in a time division multiplexing manner to find the optimal frequency matching so as to complete the adaptive adjustment of the working frequency according to the downhole working condition.

7. The dual-resonance type near-bit signal short transmission system according to claim 4, wherein the first axial magnetic field resonance coupling coil and the second axial magnetic field resonance coupling coil excite axially-changing magnetic lines of force by alternating current under the cooperation of the resonance matching circuit, and the magnetic lines of force cross over the rotatable screw assembly to realize wireless transmission between the first resonance coupling short section and the second resonance coupling short section.

Technical Field

The invention belongs to the technical field of near-bit measurement wireless short transmission in industries such as oil and gas wells, mines, geological exploration and the like, and particularly relates to a double-resonance near-bit signal short transmission system.

Background

When the petroleum industry is in drilling operation, the instant information of the temperature, the pressure, the geology and other parameters of the stratum and the position of the drilling tool needs to be obtained in time. The logging tool consists of multiple sets of sensors, and is currently typically mounted at the end of the auger stem at a distance of 10-35 m from the drill bit. The data collected by the sensors is not accurate and real-time data at the drill bit, and the data obtained by each sensor is delayed from the current information at the drill bit. In order to more accurately and timely grasp formation information, understand the track of the borehole and the change of the formation information, and timely adjust the drilling work, it is necessary to install the measurement sensing instrument at a position as close to the drill bit as possible. When a measurement sensing instrument is installed near a drill bit, the underground environment is severe, the traditional wired transmission mode cannot be realized, and a set of wireless transmission system is needed to span a 10m-35m rotating screw assembly to realize high-quality wireless transmission of signals.

The current near-bit wireless transmission technology comprises sound wave transmission and electromagnetic wave transmission. The structure design of a wireless sound wave transmission mode is complex, and the reflection interference of sound waves in a complex geological environment is serious; magnetic wireless transmission is used more, and mainly adopts Hertz ultra-low frequency electromagnetic wave transmission and electric field coupling modes. The following problems exist in the near-bit signal wireless transmission at present:

the scheme adopts an electric field coupling mode, and has the limitation that a transmitter is basically positioned at the foremost end of a working string, electromagnetic waves transmitted to a stratum by the transmitter form a loop through a screw rod, a drill rod and the stratum, the stability of the intensity of electromagnetic wave energy transmitted into the stratum is difficult to ensure, the contact state of a drill bit and the stratum directly influences the intensity of signals picked up by a receiver, and signal transmission cannot be realized.

The invention application 201910119623.3 in China proposes a wireless short transmission system of a near bit in the well and a control method thereof, and the scheme also adopts a radial electric field coupling mode and needs to form a loop through a screw, a drill rod and a stratum. When the transmission of the measured data is performed in an electric field coupling mode, the transmitting coil, the formation medium and the receiving coil need to form a closed loop. The underground environment is complex and changeable, and the tight contact between the launching device and the stratum medium cannot be ensured, so that the transmission efficiency cannot be ensured.

A near-bit logging system and method based on coupled communication is proposed in patent CN201611168982.0, but it needs a large number of wireless short drill pipes for relay transmission, and is economically inefficient.

In summary, in the technology used by the current near-bit wireless transmission system, the structural design of the wireless acoustic transmission mode is complex, and the reflection interference of the acoustic wave in the complex geological environment is serious; when MHZ-level electromagnetic wave transmission is adopted, the contact state of the drill bit and the stratum can seriously affect the strength of electromagnetic wave signals, and the electromagnetic signals are greatly attenuated and have great limitation. The underground environment is complex and changeable, and the transmission efficiency cannot be guaranteed. The prior art is difficult to realize the high-quality wireless transmission of signals within the range of 10-35 m in length of the screw drill.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to solve the problems that in the prior art used by a near-bit wireless transmission system, the structural design of a wireless sound wave transmission mode is complex, and the reflection interference of sound waves in a complex geological environment is serious; and a radial electric field coupling mode is adopted, a loop needs to be formed through the screw, the drill rod and the stratum, and signals are greatly attenuated. The high-frequency electromagnetic wave of megahertz level is adopted for transmission, the stability of the near-drilling signal can not be ensured, the higher the frequency is, the faster the signal is attenuated in the metal screw, and the signal can not be transmitted accurately. And the technical problems that the underground environment is complex and changeable, and the prior art cannot ensure the high-efficiency transmission of the near-drilling signal.

In order to solve the problems and realize high-efficiency transmission of near-bit signals, the invention provides a double-resonance type near-bit signal short transmission system, wherein the signal transmission takes KHZ-level medium-frequency magnetic field signals as a transmission medium, and belongs to near-field theoretical magnetic field coupling wireless transmission. The method comprises the following steps: the self-adaptive frequency modulation device comprises a drill bit, a screw assembly, a first resonant coupling short section, a second resonant coupling short section and a self-adaptive frequency modulation unit;

the short transmission system adopts KHZ-level medium-frequency magnetic field coupling by means of an axial coupling coil; the magnetic field carrying the information of the drill bit completes signal transmission through the first axial magnetic field resonance coupling coil, the screw assembly and the second axial magnetic field resonance coupling coil, and the transmission process is not influenced by the stratum condition;

the short transmission system adopts self-adaptive adjustable resonance driving to enhance coil magnetic field signals and is suitable for various underground working conditions;

one end of the first resonant coupling nipple is connected with one end of the screw assembly;

the other end of the first resonant coupling short section is connected with the drill bit; the first resonant coupling nipple comprises a first axial magnetic field resonant coupling coil;

one end of the second resonant coupling short section is connected with the other end of the screw assembly; the second resonant coupling nipple comprises a second axial magnetic field resonant coupling coil;

the self-adaptive frequency modulation unit is used for adjusting the working frequency of the first axial magnetic field resonance coupling coil and the working frequency of the second axial magnetic field resonance coupling coil so as to enable the acquired information at the drill bit to pass through the screw assembly from the first axial magnetic field resonance coupling coil and be coupled to the second axial magnetic field resonance coupling coil through magnetic field resonance, and therefore non-contact short transmission crossing over the screw assembly is achieved.

Optionally, the adaptive frequency modulation unit includes: the device comprises a first driving module, a first signal modulation module, a first resonance compensation module and a second resonance compensation module; the first driving module, the first signal modulation module, the first resonance compensation module and the second resonance compensation module are positioned in the first resonance coupling short section;

the first signal modulation module is used for sequentially filtering, amplifying and modulating the acquired information at the drill bit; the modulated signal generates a corresponding sinusoidal signal through a first driving module and is transmitted to a first axial magnetic field resonance coupling coil through a first resonance compensation module; and the first axial magnetic field resonance coupling coil sends out a magnetic field signal to pass through the screw assembly, and the magnetic field signal is transmitted to the second resonance coupling short section in a non-contact manner.

Specifically, the first resonance compensation module is a resonance transmission compensation module in the first resonance coupling short section; the second resonance compensation module is a resonance receiving compensation module in the first resonance coupling short section.

Optionally, the adaptive frequency modulation unit further includes: the second signal demodulation module, the third resonance compensation module and the fourth resonance compensation module; the second signal demodulation module, the third resonance compensation module and the fourth resonance compensation module are positioned in the second resonance coupling short section;

the second axial magnetic field resonance coupling coil induces a magnetic field signal passing through the screw assembly under the resonance frequency; the second axial magnetic field resonance coupling coil, the third resonance compensation module and the fourth resonance compensation module form a resonance loop, and the resonance frequency of the resonance loop is the same as that of the first axial magnetic field resonance coupling coil so as to increase the coupling strength among magnetic fields; the second signal demodulation module analyzes information at the drill bit from the magnetic field signal induced by the second axial magnetic field resonance coupling coil.

Specifically, the third resonance compensation module is a resonance transmission compensation module in the second resonance coupling short section; and the fourth resonance compensation module is a resonance receiving compensation module in the second resonance coupling short section.

Optionally, the first resonance compensation module, the second resonance compensation module, the third resonance compensation module and the fourth resonance compensation module form a resonance matching circuit;

when the first resonant coupling short section transmits a signal, the resonant matching circuit enables the first axial magnetic field resonant coupling coil to work in a resonant signal transmitting state; when the second resonant coupling short section receives signals, the resonant matching circuit enables the second axial magnetic field resonant coupling coil to work in a resonant signal receiving state;

when the second resonant coupling short section transmits a signal, the resonant matching circuit enables the second axial magnetic field resonant coupling coil to work in a resonant signal transmitting state; when the first resonant coupling short section receives a signal, the resonant matching circuit enables the first axial magnetic field resonant coupling coil to work in a resonant signal receiving state; the induction magnetic field intensity is enhanced and the transmission efficiency is improved through double resonance;

during working, the first resonant coupling short section and the second resonant coupling short section are driven and receive signals through the resonant matching circuit, time division multiplexing is achieved, and two-way communication can be achieved.

Optionally, the screw assembly has a length of 10m-35 m.

Optionally, the adaptive frequency modulation unit pre-sends a section of composite waveform in a time division multiplexing manner to find the optimal frequency matching, so as to complete the adaptive adjustment of the working frequency according to the underground working condition.

Optionally, the first axial magnetic field resonant coupling coil and the second axial magnetic field resonant coupling coil are matched with the resonant matching circuit, and alternating current is conducted to excite axially-changed magnetic lines, and the magnetic lines cross over the rotatable screw assembly to realize wireless transmission between the first resonant coupling short section and the second resonant coupling short section.

Generally, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects:

(1) the invention adopts double resonance coupling to realize wireless signal transmission and has simple structure. And a resonant magnetic field coupling mode is adopted, so that the problem of transmission failure caused by the conditions of complex working conditions, drill bit and stratum foundation and the like under the electric field coupling mode is effectively avoided. The strength of the transmitting and receiving magnetic fields is enhanced through bilateral magnetic field resonance, and the transmission efficiency is improved; the working frequency of the coil does not reach the range of electromagnetic waves, the coil transmits in the range of a magnetic field, and a wireless transmission system based on magnetic field coupling cannot be influenced by media such as geology, bottom liquid and the like;

(2) the wireless communication between the first resonant coupling short section and the second resonant coupling short section is realized by modulating and demodulating a magnetic field signal through the coil working frequency self-adaptive frequency modulation unit, and the working frequency self-adaptive adjustment can be completed according to the underground working condition;

(3) the strength of magnetic field coupling is increased in a resonance mode, the wireless transmission distance is long, and the wireless transmission of underground near-bit signals of the screw drilling tool with the length ranging from 10m to 35m can be compatible;

(4) the invention is compatible with the existing logging system, uses the magnetic field resonance coupling mode under the near field theory, and has the advantages of high economic benefit, wide application and convenient disassembly and assembly.

(5) The short transmission system adopts KHZ-level medium-frequency magnetic field coupling by means of an axial coupling coil; the magnetic field carrying the information of the drill bit completes signal transmission through the transmitting coil, the screw assembly and the receiving coil, and the transmission process is not influenced by the stratum condition; the short transmission system adopts adjustable resonance drive to enhance coil magnetic field signals and is suitable for various underground working conditions.

Drawings

FIG. 1 is a schematic diagram of a dual-resonance type near-bit signal short transmission system provided by the present invention.

Fig. 2 is a schematic diagram of the adaptive frequency modulation unit according to the present invention.

Fig. 3 is a schematic structural diagram of a first resonant coupling sub provided by the invention.

Fig. 4 is a schematic structural diagram of a second resonant coupling sub provided by the present invention.

FIG. 5 is a schematic diagram of the system operation of the short-range near bit signal provided by the present invention.

The same reference numbers are used throughout the drawings to refer to the same elements or structures, including: the drill bit comprises a drill bit 1, a first coil driving modulation and demodulation module 2, a first axial magnetic field resonance coupling coil 3, a screw assembly 4, a second axial magnetic field resonance coupling coil 5, a second coil driving modulation and demodulation module 6, a first resonance coupling short section 7, a second resonance coupling short section 8, a first power supply module 71, a first driving module 72, a first control module 73, a first signal modulation module 74, a first signal demodulation module 75, a first resonance compensation module 76, a second resonance compensation module 77, a second power supply module 81, a second driving module 82, a second control module 83, a second signal modulation module 84, a second signal demodulation module 85, a third resonance compensation module 86 and a fourth resonance compensation module 87.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

The invention aims to solve the problems and the defects in the prior art, provides a double-resonance type near-bit signal short transmission system, realizes the wireless transmission of underground near-bit signals, and has no influence of media such as stratum, bottom liquid and the like on the wireless communication. By adopting a double-resonance time-sharing multiplexing two-way communication system based on magnetic field coupling and a self-adaptive frequency modulation unit, a near bit signal can penetrate through a rotatable screw rod with the length of 10m-35m, and wireless transmission of the near bit signal is realized.

In order to achieve the above object, the technical solution of the present invention is realized as follows:

the invention discloses a double-resonance type near-bit signal short transmission system, which comprises the following components: the double-resonance type signal time-sharing multiplexing bidirectional communication system based on magnetic field coupling comprises a first resonance coupling short section and a second resonance coupling short section; a coil working frequency self-adaptive frequency modulation unit; the double-resonance time-sharing multiplexing two-way communication system based on magnetic field coupling is composed of a near-bit well logging sensing instrument, a first resonance coupling short section and a second resonance coupling short section, wherein the first resonance coupling short section and the second resonance coupling short section are respectively arranged at two ends of a screw assembly; the first resonant coupling short section and the second resonant coupling short section are driven and receive signals through the resonant circuit during working, time division multiplexing is achieved, and two-way communication can be achieved. The coil working frequency self-adaptive frequency modulation unit pre-sends a section of composite waveform through a time division multiplexing bidirectional system to find the optimal frequency matching, then the control module adjusts the driving frequency, and the working frequency self-adaptive adjustment is completed according to the underground working condition.

The first resonant coupling short section and the second resonant coupling short section are respectively provided with an axial magnetic field resonant coupling coil, a coil driving module, a signal modulation and demodulation module and a control module; the coil is matched with the resonant matching circuit, alternating current is conducted to excite the magnetic force lines which are changed axially, and the magnetic force lines cross over the rotatable screw assembly to achieve wireless transmission between the first resonant coupling short section and the second resonant coupling short section. The axially wound coil is used as a magnetic antenna, and wireless transmission based on magnetic field coupling cannot be influenced by the contact state of the drill bit, the screw and the stratum.

In the double-resonance type signal time-sharing multiplexing bidirectional communication system based on magnetic field coupling, when the first resonance coupling short section transmits a signal, the resonance matching circuit enables the axial coupling coil to work in a resonance signal transmitting state; when the second resonant coupling short section receives signals, the resonant matching circuit enables the axial coupling coil to work in a resonant signal receiving state; when the second resonant coupling short section transmits signals, the resonant matching circuit enables the axial coupling coil to work in a resonant signal transmitting state. When the first resonant coupling short section receives a signal, the resonant matching circuit enables the axial coupling coil to work in a resonant signal receiving state; through two syntonizations, reinforcing magnetic field intensity improves transmission efficiency.

The invention discloses a double-resonance type near-bit signal short transmission system, which comprises the following components: the double-resonance type signal time-sharing multiplexing bidirectional communication system based on magnetic field coupling comprises a first resonance coupling short section and a second resonance coupling short section; a coil working frequency self-adaptive adjusting system;

the double-resonance time-sharing multiplexing two-way communication system based on magnetic field coupling is composed of a near-bit well logging sensing instrument, a first resonance coupling short section and a second resonance coupling short section, wherein the first resonance coupling short section and the second resonance coupling short section are respectively arranged at two ends of a screw assembly; the first resonant coupling short section and the second resonant coupling short section are driven and receive signals through the resonant circuit during working, time division multiplexing is achieved, and two-way communication can be achieved.

The coil working frequency self-adaptive adjusting unit finds the optimal frequency matching by pre-sending a section of composite waveform through the time-sharing multiplexing bidirectional system, then the control module adjusts the driving frequency, and the working frequency self-adaptive adjustment is completed according to the underground working condition.

As shown in fig. 1, the present invention provides a dual-resonance type near-bit signal short transmission system: the self-adaptive frequency modulation device comprises a drill bit 1, a screw assembly 4, a first resonant coupling short section 7 and a second resonant coupling short section 8 which are respectively arranged at two ends of the screw assembly, and a self-adaptive frequency modulation unit; the first resonant coupling nipple 7 is positioned between the screw assembly 4 and the drill bit 1; the first resonant coupling nipple 7 is provided with a first coil driving modulation and demodulation module 2 and a first axial magnetic field resonant coupling coil 3; and a second axial magnetic field resonance coupling coil 5 and a second coil driving modulation and demodulation module 6 are installed on the second resonance coupling short section 8. Under the matching of the resonant matching circuit of the first axial magnetic field resonant coupling coil 3 and the second axial magnetic field resonant coupling coil 5, alternating current is conducted to excite axially-changed magnetic lines, and the magnetic lines cross the screw assembly 4 to realize wireless transmission between the first resonant coupling short section 7 and the second resonant coupling short section 8; the first coil drives the modulation and demodulation module 2, the second coil drives the modulation and demodulation module 6, the resonance matching circuit and the magnetic field axial coupling coil form the self-adaptive frequency modulation unit.

The first resonant coupling nipple 7 is detachably mounted, one end of the first resonant coupling nipple is fixedly connected with the lower part of the screw assembly 4 through an upper metal buckle, and the other end of the first resonant coupling nipple is connected with the drill bit 1 through a lower metal buckle; the second resonant coupling short section 8 is detachably mounted and is mounted above the screw assembly 4 through an upper metal buckle;

coupling coils in the first resonant coupling short section and the second resonant coupling short section are axially wound and are respectively provided with an impedance matching circuit, namely the corresponding first coil drives the modulation and demodulation module and the second coil drives the modulation and demodulation module to work at the same resonant frequency point;

the self-adaptive frequency modulation unit adopts a coil working frequency self-adaptive adjustment system, realizes underground data information wireless transmission by modulating and demodulating weak magnetic field signals, adjusts driving frequency through a control module to achieve optimal matching, and completes frequency self-adaptive adjustment;

and the signal demodulation module in the self-adaptive frequency modulation unit analyzes data information such as pressure, temperature and the like of the underground drill bit and uploads the data information to the ground data center in other transmission modes according to a communication protocol.

The double-resonance type near-bit signal short transmission system provided by the invention is provided with an axially-mounted coupling coil, a coil driving module, a signal modulation and demodulation module and a control module, achieves wireless transmission of an underground near-bit signal on a double-magnetic coupling resonance mechanism, realizes real-time and accurate wireless transmission of the signal across a 10-35 m screw drill, and is not influenced by media such as stratum, well bottom liquid and the like.