A well-ground two-way communication method and device based on mixed dipole cooperation

Abstract

The application relates to a well-ground bidirectional communication method and device based on mixed dipole cooperation, which comprises an uplink communication device configured to encode and modulate collected downhole data by using a downhole transmitting device, transmit a modulated first time-varying electromagnetic field signal to the ground medium, simultaneously receive the first time-varying electromagnetic field signal by using a first magnetometer, and decode the received first time-varying electromagnetic field signal to realize downhole data uploading communication; and a downlink communication device configured to encode and modulate a control instruction to be transmitted downward by using a ground transmitting device, transmit a modulated second time-varying electromagnetic field signal to the ground medium, simultaneously receive the second time-varying electromagnetic field signal by using a second magnetometer, and decode the received second time-varying electromagnetic field signal to realize control instruction downward transmission communication. The application can be widely applied to the fields of oil and gas well engineering, while-drilling measurement and control and downhole communication.

Description

Technical Field

[0001] This invention belongs to the fields of oil and gas well engineering, drilling monitoring and control and downhole communication technology, and specifically relates to a well-to-surface two-way communication method and device based on hybrid dipole coordination. Background Technology

[0002] Deep oil and gas exploration and development face complex and harsh environments. Downhole automation and intelligent tools need to transmit massive amounts of data to the surface in real time and quickly receive control commands from the surface. Current wireless signal transmission methods while drilling mainly include mud pulse, acoustic transmission, and electromagnetic transmission. Mud pulse transmission has a relatively long range but a low transmission rate and is unsuitable for gas and foam drilling. Acoustic transmission, while unaffected by gases or foams, is susceptible to environmental vibration interference and suffers from impedance matching issues at drill pipe couplings. Without a relay, the actual effective transmission distance is typically limited to less than 1000 meters. Electromagnetic transmission is widely considered to have the potential for rapid two-way communication while drilling, but current technology primarily uses electric field components as carrier waves. The receiving end decodes the signal through the potential difference of the ground-inserted electrodes. Signal transmission is severely attenuated by formation resistivity, resulting in telemetry depths generally less than 3000 meters, and even less than 1000 meters in low-resistivity (<10 Ω·m) water-bearing formations, severely limiting its application.

[0003] During electromagnetic field transmission, the electric field component and the magnetic field component interconvert and propagate. Therefore, in communication methods based on electromagnetic transmission, in addition to transmitting and receiving the electric field component, the magnetic field component can also be used as a new pathway. Furthermore, the relative permeability of non-ferromagnetic strata is close to 1, so the transmission process of the magnetic field component is less affected by the strata, resulting in low dielectric loss, wide coverage, and stable channel. However, existing magnetic dipole transmitting antennas are mainly magnetic induction coil antennas, which are large in size, have weak directivity, leading to rapid attenuation, short transmission distance (<600 meters), and high transmission power, making it difficult to achieve long-distance communication under limited space and power conditions downhole. Existing magnetic field measurement methods (such as induction coils and fluxgate magnetometers) have low sensitivity and are difficult to effectively receive weak magnetic signals transmitted over long distances. Summary of the Invention

[0004] To address the problems of severe electromagnetic wave attenuation due to formation resistivity, insufficient receiver sensitivity, and short transmission distance in existing Electromagnetic Measurement While Drilling (EM-MWD) systems, the present invention aims to provide a well-to-surface bidirectional communication method and device based on hybrid dipole coordination. This method employs a hybrid dipole coordination strategy, which uses electric dipoles for transmission and magnetic dipoles for reception. This strategy overcomes the influence of formation resistivity and provides high-sensitivity reception, enabling long-distance, high-speed bidirectional communication between the well and the surface during drilling.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a well-to-surface bidirectional communication device based on hybrid dipole coordination, comprising: The uplink communication device is configured to encode and modulate the collected downhole data using a downhole transmitter and transmit the modulated first time-varying electromagnetic field signal to the earth medium. At the same time, it uses a first magnetometer to receive the first time-varying electromagnetic field signal and decodes the received first time-varying electromagnetic field signal to realize downhole data uplink communication. The downlink communication device is configured to encode and modulate the control commands to be transmitted using a ground transmitter, and transmit the modulated second time-varying electromagnetic field signal to the ground medium. At the same time, it uses a second magnetometer to receive the second time-varying electromagnetic field signal and decodes the received second time-varying electromagnetic field signal to realize the control command downlink communication.

[0006] Furthermore, the downhole transmitting device includes an insulating short section, which is rigidly connected to the upper drill pipe and the lower drill pipe respectively through a threaded structure. While transmitting drill pipe torque and bearing load, the insulating short section uses its own insulation properties to electrically insulate the upper drill pipe and the lower drill pipe from each other, forming two positive and negative electrodes of an asymmetric electric dipole antenna.

[0007] Furthermore, the interior of the insulating short section is a through-type pressure chamber, and a downhole electronic transmission unit is installed inside the pressure chamber. The downhole electronic transmission unit includes: The first control processing unit is connected to the data acquisition unit deployed near the drill bit via an internal bus. It is used to preprocess and encode the downhole data acquired in real time by the data acquisition unit and to control the transmission. The first power amplifier unit is used to amplify the output signal of the first control processing unit and drive the alternating current, so that the asymmetric electric dipole antenna generates a first time-varying electromagnetic field signal under the excitation of the alternating current. The first power supply unit is used to supply power to the data acquisition unit, the first control processing unit and the first power amplification unit.

[0008] Furthermore, the ground-based launching device includes: The second control processing unit is used to encode and modulate the control commands to be transmitted. The second power amplifier unit is used to amplify the output signal of the second control processing unit and drive the alternating current. An electric dipole antenna is used to generate a second time-varying electromagnetic field signal under alternating current excitation and inject it into the earth medium. The second power supply unit is used to supply power to the second control processing unit, the second power amplification unit, and the electric dipole antenna.

[0009] Furthermore, the first magnetometer and the second magnetometer are atomic magnetometers based on quantum effects; the first magnetometer is deployed within a range of 30-100m from the wellhead, the second magnetometer is deployed inside the insulating short section, and the second magnetometer is externally provided with a temperature-resistant encapsulation and a non-metallic pressure-resistant shell that meet preset requirements.

[0010] Secondly, the present invention provides a well-to-surface bidirectional communication method based on hybrid dipole coordination, comprising: The downhole transmitting device encodes and modulates the collected downhole data and transmits the modulated first time-varying electromagnetic field signal to the earth medium. At the same time, the first magnetometer receives the first time-varying electromagnetic field signal and decodes the received first time-varying electromagnetic field signal to realize downhole data uploading and communication. The ground-based transmitter encodes and modulates the control commands to be transmitted, and transmits the modulated second time-varying electromagnetic field signal to the ground medium. At the same time, a second magnetometer receives the second time-varying electromagnetic field signal and decodes the received signal to realize the communication for transmitting control commands.

[0011] Furthermore, the method involves encoding and modulating the collected downhole data using a downhole transmitting device, transmitting the modulated first time-varying electromagnetic field signal to the earth medium, and simultaneously receiving the first time-varying electromagnetic field signal using a first magnetometer and decoding the received signal to achieve downhole data upload communication, including: The collected downhole data is preprocessed using a downhole transmitter to obtain a binary data stream; The binary data stream is encoded and modulated using the 2FSK signal modulation method to obtain the first encoded modulation signal. After enhancing the first coded modulation signal, the first time-varying electromagnetic field signal is transmitted to the earth medium according to the preset two-way communication method; The first time-varying electromagnetic field signal is received using a first magnetometer, and the corresponding original voltage signal is output. The original voltage signal is decoded to recover the original downhole data.

[0012] Furthermore, the decoding process of the original voltage signal to recover the original downhole data includes: The overall energy of the raw voltage signal output by the first magnetometer is evaluated, and the amplitude is normalized. The normalized voltage signal is passed through a circuit with center frequencies of... and The bandpass filter is used to separate the signals, resulting in two frequency channels, where, and These represent the carrier frequencies used in 2FSK signal modulation; The amplitude ratio of the two separated frequency channel signals is calculated, and adaptive amplitude compensation is performed when the amplitude ratio exceeds a preset threshold. The two frequency channel signals after amplitude adaptive compensation are multiplied with the locally generated in-phase and in-frequency carrier signal to achieve spectrum shifting. After the spectrum shifting, the two frequency channel signals are passed through a low-pass filter to extract the baseband signal components of the two frequency channel signals; The amplitude of the two baseband signal components is determined by a decision circuit, and each data bit is determined to be "1" or "0" to obtain the original downhole data.

[0013] Furthermore, the overall energy assessment and amplitude normalization of the raw voltage signal output by the first magnetometer includes: Based on the original voltage signal output by the first magnetometer, the root mean square value of the original voltage signal within a preset time window is calculated, and the amplitude of the original voltage signal is standardized to the target amplitude range according to the root mean square value.

[0014] Furthermore, the calculation of the amplitude ratio of the two separated frequency channel signals, and the adaptive amplitude compensation when the amplitude ratio exceeds a preset threshold, includes: The average amplitude of the two frequency channel signals is monitored and calculated separately, and the amplitude ratio of the two frequency channel signals is calculated. The calculated amplitude ratio is compared with a preset threshold. When the amplitude ratio exceeds the preset threshold, an adaptive compensation mechanism is triggered. Using the average amplitude of the two frequency channel signals as a reference, the frequency channel signal with the weaker amplitude is amplified by gain, while the frequency channel signal with the stronger amplitude is attenuated, so that the two frequency channel signals reach an amplitude balance state. The balance state means that the amplitude ratio of the two frequency channel signals is controlled within a preset range.

[0015] The present invention has the following advantages due to the adoption of the above technical solutions: 1. In uplink communication, this invention employs an asymmetric electric dipole antenna formed by a downhole transmitter integrated into an insulating short section to transmit electromagnetic waves, which are then decoded on the ground using a ground receiving device containing a high-sensitivity magnetometer. In downlink communication, an electrode-based ground transmitter transmits the electromagnetic field, which is decoded by the downhole receiving device based on a high-sensitivity magnetometer. Unlike traditional EM-MWD (Measuring While Drilling) methods, this invention does not rely on the transmission of electromagnetic field signals. Instead, it uses a magnetic field carrier signal transmitted by an electric dipole as the information carrier, and receives the magnetic field signal using a magnetometer. When this magnetic field carrier signal propagates through the formation, its attenuation is weaker than that of the electric field signal, and it has a higher energy density. It is also insensitive to formation resistivity, thus solving the problem of severe attenuation and limited transmission distance of traditional electric field signals in low-resistivity formations.

[0016] 2. This invention proposes an atomic magnetometer as a high-sensitivity magnetometer for both ground-based and downhole receiving devices, replacing traditional induction coil or fluxgate magnetometers. The atomic magnetometer possesses detection sensitivity in the petabyte to femt range, three orders of magnitude higher than induction coils and two to six orders of magnitude higher than conventional fluxgate magnetometers, providing assurance for highly sensitive measurement of weak electromagnetic field signals and increasing transmission and reception distances.

[0017] 3. Based on the bidirectional communication modulation and demodulation mechanism of 2FSK binary frequency shift keying, this invention proposes a two-stage adaptive gain control method. Through the first-stage overall amplitude normalization control and the second-stage adaptive compensation algorithm for dual-frequency carrier signal amplitude balance, the adaptive balance threshold and target are optimized, effectively suppressing the dual-frequency signal amplitude imbalance problem caused by channel frequency selective attenuation, reducing the 2FSK demodulation bit error rate, and increasing the transmission distance.

[0018] Therefore, this invention can be widely applied in the fields of oil and gas well engineering, drilling monitoring and control, and downhole communication technology. Attached Figure Description

[0019] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. In the drawings: Figure 1 This is a schematic diagram of the uplink communication device provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the downlink communication device provided in an embodiment of the present invention; Figure 3 This is a cross-sectional schematic diagram of the insulating short section structure provided in an embodiment of the present invention; Figure 4This is a preferred atomic magnetometer system configuration diagram of the high-sensitivity magnetometer provided in this embodiment of the invention; Figure 5 This is a diagram of a bidirectional communication 2FSK modulation and demodulation method provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of the original received waveform and the waveform of the first bandpass filter preprocessing of the bidirectional communication 2FSK modulated signal provided in the embodiment of the present invention; Figure 7 This is a schematic diagram of the waveforms after filtering and separating the high and low frequency received signals of the bidirectional communication 2FSK provided in this embodiment of the invention; Figure 8 This is a diagram illustrating the adaptive gain control effect of the 2FSK high and low frequency signals in bidirectional communication provided in this embodiment of the invention. Figure 9 This is a schematic diagram of the spectrum shifting waveform of the bidirectional communication 2FSK high and low frequency signals provided in an embodiment of the present invention; Figure 10 This is a schematic diagram of the low-pass filter waveform after spectrum shifting for bidirectional communication 2FSK provided in an embodiment of the present invention; Figure 11 This is a schematic diagram of the demodulated waveform of the bidirectional communication 2FSK signal provided in an embodiment of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0021] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0022] In some embodiments of the present invention, a well-to-surface bidirectional communication method and apparatus based on hybrid dipole coordination is provided. Physically, it consists of two parts: surface equipment and downhole equipment. Time-varying electromagnetic field signals are coupled and transmitted through a communication channel between the drill pipe and the formation. The surface equipment mainly includes a surface receiver for uplink communication and a surface transmitter for downlink communication, deployed around the wellhead. The downhole equipment includes a downhole transmitter for uplink communication and a downhole receiver for downlink communication, integrated inside an insulating short section. The uplink transmitter, together with the upper and lower drill pipes via the downhole insulating short section, forms an asymmetric electric dipole antenna. The downlink transmitter uses surface electrodes to excite the drill string and the formation, forming an electric field transmission loop. Both the uplink and downlink receivers are based on high-sensitivity magnetometers, employing BFSK binary frequency shift keying modulation and demodulation technology and intelligent signal processing methods to ultimately achieve long-distance, high-speed, bidirectional communication while drilling between the well and the surface.

[0023] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0024] Example 1 like Figure 1 , Figure 2 As shown, this embodiment provides a well-to-surface bidirectional communication device based on hybrid dipole coordination, which includes: The uplink communication device 1 is configured to encode and modulate the collected downhole data using the downhole transmitter 11 and transmit the modulated first time-varying electromagnetic field signal to the earth medium. At the same time, the ground receiver 12 performs signal processing such as receiving and decoding the first time-varying electromagnetic field signal to realize the uplink communication of downhole data. The downlink communication device 2 is configured to encode and modulate the control commands to be transmitted using the ground transmitter 21, and then transmit the modulated second time-varying electromagnetic field signal to the ground medium. At the same time, the downhole receiver 22 performs signal processing such as receiving and decoding the second time-varying electromagnetic field signal to realize the downlink communication of control commands.

[0025] Furthermore, such as Figure 3 As shown, the downhole transmitting device 11 includes an insulating short section 110, which is rigidly connected to the upper drill pipe 111 and the lower drill pipe 112 respectively through a threaded structure. While transmitting drill pipe torque and bearing load, the insulating short section 110 uses its own insulation properties to make the upper drill pipe 111 and the lower drill pipe 112 electrically insulated from each other, forming two positive and negative electrodes of an asymmetric electric dipole antenna.

[0026] Furthermore, the insulating sub 110 is a non-magnetic metal and non-metal composite structure made of high-strength, high-insulation composite materials (such as ceramic-reinforced epoxy resin), and its metal ends are machined with API standard threads for connection to the upper drill pipe 111 and the lower drill pipe 112. The insulating sub 110 contains a through-hole pressure chamber, within which a downhole electronic transmission unit is housed. This downhole electronic transmission unit includes: The first control processing unit 113 is connected to the data acquisition unit 114 deployed near the drill bit via an internal bus (such as CAN or SPI). It is used to preprocess and encode the raw downhole data acquired by the data acquisition unit 114 and to control the transmission. The raw downhole data acquired by the data acquisition unit 114 includes geological parameters, engineering parameters, system status parameters, etc. The first power amplifier unit 115 is used to amplify the output signal of the first control processing unit 113 and drive an alternating current. The asymmetric electric dipole antenna generates a first time-varying electromagnetic signal under the excitation of the alternating current and transmits it into the ground medium. The output power of the first power amplifier unit 115 can be adjusted in the range of 10-100W according to the communication distance requirements. The first power supply unit 116 is used to supply power to the first control processing unit 113, the data acquisition unit 114 and the first power amplification unit 115.

[0027] In this embodiment, the downhole transmitting electronic unit couples the output signal of the first power amplification unit 115 to the upper drill pipe 111 and the lower drill pipe 112 of the insulating short section 110 via an insulated feeder, thereby forming an asymmetric electric dipole antenna. During operation, the downhole data acquired in real time by the data acquisition unit 114 is encoded and modulated by the first control processing unit 113. The output signal is amplified and driven by the first power amplification unit 115 and then loaded onto the asymmetric electric dipole antenna to form a modulated first time-varying electromagnetic field. A current loop is formed in the "upper drill string - formation - lower drill string" structure, which excites the asymmetric electric dipole antenna to transmit a low-frequency first time-varying electromagnetic field signal into the surrounding earth medium space.

[0028] Unlike traditional EM-MWD systems that utilize the electric field component, this invention specifically selects the magnetic field component as the information carrier. This magnetic field carrier signal propagates throughout the entire space from the wellbore to the formation and then to the surface via a downhole transmission channel comprised of the drill pipe, drilling fluid, and formation. Since the propagation of a magnetic field in a conductive medium is primarily influenced by its permeability and is insensitive to changes in formation resistivity, and given that the relative permeability of a typical non-ferromagnetic formation medium is approximately 1, the magnetic field component exhibits lower dielectric loss and a slower attenuation rate compared to the electric field component.

[0029] Preferably, all electronic modules in the downhole transmitting electronic unit are fixed to a high-strength insulating skeleton (such as ceramic or polyetheretherketone, PEEK) within the pressure chamber of the insulating stub 110 in a stacked or side-by-side manner. The pressure chamber of the entire insulating stub adopts a multi-layer sealing design, with thermally conductive insulating adhesive filled between each electronic module and the skeleton to achieve module fixation, heat conduction, and vibration and shock resistance; the two ends of the pressure chamber are statically sealed with metal end caps and O-rings to ensure the overall pressure-bearing capacity of the pressure chamber. To solve the high-temperature problem, key chips (such as power amplifiers) are mounted on heat sinks, and heat is conducted to the metal shell through thermally conductive materials; the entire insulating stub shell is in direct contact with the drilling fluid, utilizing circulating drilling fluid for efficient heat dissipation, ensuring long-term stable operation in the high-temperature environment downhole.

[0030] Furthermore, the ground receiving device 12 specifically includes: The first high-sensitivity magnetometer 120 is deployed in the safe area of ​​the well site to measure and receive the first time-varying electromagnetic field signal emitted by the downhole transmitter and convert it into a first voltage signal; The second control processing unit 121 is used to process the first voltage signal output by the first high-sensitivity magnetometer 120 and restore the original downhole data uploaded by the downhole transmitter 11. The second power supply unit 122 is used to supply power to the first high-sensitivity magnetometer 120 and the second control processing unit 121.

[0031] During operation, the first high-sensitivity magnetometer 120 converts the detected uplink time-varying electromagnetic field signal into a first voltage signal via a shielded signal cable, which is then input to the second control processing unit 121. The second control processing unit 121 employs an adaptive filter to suppress power frequency interference and environmental noise, and performs demodulation to obtain the downhole data transmitted from the well. Simultaneously, the second power supply unit 122 supplies power to both the first high-sensitivity magnetometer 120 and the second control processing unit 121. The placement of the first high-sensitivity magnetometer 120 requires comprehensive consideration of signal strength and background noise interference at the well site; it is generally selected within a range of 30-100 meters from the wellhead, and necessary electromagnetic shielding measures are implemented.

[0032] Furthermore, the first high-sensitivity magnetometer 120 is preferably an atomic magnetometer based on quantum effects, with a sensitivity of 2-20 pT, which is much higher than the 0.1-1 nT sensitivity of existing fluxgate magnetometers and at least 100 times higher than the sensitivity of traditional magnetic induction receiving coils.

[0033] More preferably, in this embodiment, the first high-sensitivity magnetometer 120 is an optically pumped atomic magnetometer. Based on the mechanism of atomic-light interaction, the optically pumped atomic magnetometer selects rubidium atoms as the sensitive atoms for magnetic field measurement. Amplitude-modulated circularly polarized pump light polarizes the atomic ensemble, aligning its spin direction with the light propagation direction. Under the influence of an external magnetic field, the spin magnetic moment of the polarized atom undergoes Larmor precession around the magnetic field direction. The Larmor precession atom undergoes magnetic resonance, and after interacting with light, the polarization state of the light oscillates. Then, linearly polarized probe light is used to detect the projection of the Larmor precession atom's spin magnetic moment onto its polarization direction. Based on the circular birefringence of atoms, a change in the optical rotation angle is generated. The optical rotation angle is acquired by a photodetector and controlled in a closed-loop feedback manner with the modulation frequency of the pump light. When the modulation frequency of the pump light is the same as the frequency of the atom's Larmor precession, the amplitude of the optical rotation angle of the atomic magnetic resonance signal is maximized, thereby achieving highly sensitive magnetic field measurement.

[0034] Specifically, such as Figure 4 As shown, the optically pumped atomic magnetometer includes a light source module, a magnetometer physical module, and a magnetometer control circuit module. The light source module provides pump and probe light; the magnetometer physical module acts as a sensing probe, providing an environment for the interaction of atoms with light and magnetic fields; and the magnetometer control circuit module provides closed-loop feedback control for both the light source module and the magnetometer physical module.

[0035] The light source module includes a pump photonics module and a probe photonics module. The pump photonics module includes a pump laser, a first beam splitter, a pump frequency stabilization optical path module, and a pump control module. The pump laser provides pump light to polarize atoms and excite the Larmor precession of atoms. The first beam splitter is used to split the pump light beam to stabilize the pump light frequency in a closed loop. The pump frequency stabilization optical path module often adopts a saturated absorption optical path or a nonlinear magneto-optical rotation optical path, and uses the pump spectrum after beam splitting to adjust and lock the pump light frequency. The pump control module stabilizes the pump light frequency at the 795nm transition line of the Rb-87 atom's ground state F=2→F' excited state by adjusting parameters such as the temperature and current of the pump laser. The probe photonics module includes a probe laser, a second beam splitter, a probe frequency stabilization optical path module, and a probe control module. Similar to the pump photonics module, it stabilizes the probe light at the 795nm transition line from the ground state F=2 to the excited state F' of the Rb-87 atom by adjusting parameters such as the temperature and current of the probe laser.

[0036] The magnetometer physics module includes a pump light physics module, a probe light physics module, a rubidium atom chamber module, and a photodetector. In the pump light physics module, the frequency-stabilized pump light is first focused by a lens and modulated by an AOM (acousto-optic modulator) to achieve light intensity amplitude modulation. Then, it is converted into circularly polarized light by a quarter-wave plate before entering the rubidium atom chamber module. In the probe light physics module, the frequency-stabilized probe light is converted into linearly polarized light with adjustable light intensity amplitude by a half-wave plate and a polarizer before entering the rubidium atom chamber module. The rubidium atom chamber module includes a vacuum chamber containing rubidium atoms and a chamber heater. The temperature of the chamber heater is measured by the magnetometer control circuit module, which performs closed-loop feedback control to achieve a chamber temperature accuracy of 0.1℃.

[0037] The time-varying electromagnetic field signal transmitted from the well to the surface causes rubidium atoms in the rubidium atom chamber module to undergo Larmor precession under the action of pump light. This precession is transmitted through the probe light of the chamber module, and after photodetector conversion, the photoelectric signal is converted into a photoelectric signal. The spectral voltage signal is then processed by the magnetometer control circuit module and fed back to the AOM acousto-optic modulator, thereby achieving closed-loop control of the pump light frequency and ultimately realizing the measurement of the time-varying electromagnetic field signal. Notably, the pump light and probe light entering the chamber module are orthogonal to the direction of the time-varying electromagnetic field to ensure the sensitivity of the magnetic field measurement.

[0038] Furthermore, such as Figure 2 As shown, the downlink communication device 2 includes a ground transmitter 21 and a downhole receiver 22. The ground transmitter 21 encodes and modulates the control commands to be transmitted, and transmits the modulated second time-varying electromagnetic field signal to the earth using an electric dipole antenna. The downhole receiver 22 detects and receives the second time-varying electromagnetic field signal, processes the signal, and transmits the restored control commands to the command execution unit via wired transmission, thus realizing the downlink of control commands.

[0039] Furthermore, the ground-based launching device 21 includes: The third control processing unit 210 is used to encode and modulate the control commands to be transmitted; The second power amplifier unit 211 is used to amplify the power of the output signal of the third control processing unit 210 and drive the alternating current. Electric dipole antenna 212 is used to generate a second time-varying electromagnetic field signal under alternating current excitation and inject it into the earth medium; The third power supply unit 213 is used to supply power to the third control processing unit 210, the second power amplifier unit 211, and the electric dipole antenna 212.

[0040] Among them, the third control processing unit 210 in the ground transmitting device 21 can be multiplexed with the second control processing unit 121 in the ground receiving device 12 in the uplink communication, and the third power supply unit 213 can be multiplexed with the second power supply unit 122.

[0041] Furthermore, the electric dipole antenna 212 includes a ground electrode and a derrick electrode (not shown in the figure). The ground electrode, serving as the negative pole of the electric dipole antenna, is made of corrosion-resistant conductive material and is embedded in the formation at a depth of 1-3 meters to ensure good contact with the formation. The derrick electrode, serving as the positive pole of the electric dipole antenna, is positioned at a predetermined location on the derrick and connected to the wellhead casing via a cable. The distance between the derrick electrode and the ground electrode can be adjusted within the range of 50 meters to 200 meters, depending on the formation conditions and communication requirements.

[0042] During underground communication, the alternating current output by the second power amplifier unit 211 is directly injected into the earth medium between the ground electrode and the derrick electrode. This alternating current forms a loop in the stratum, exciting the generation of a second time-varying electromagnetic field signal dominated by a magnetic field component.

[0043] Furthermore, the downhole receiving device 22 includes: The second high-sensitivity magnetometer 220 is used to detect the second time-varying electromagnetic field signal emitted by the ground transmitter 21 and convert it into a second voltage signal; The fourth control processing unit 221 is used to perform signal processing such as filtering and demodulation on the second voltage signal output by the second high-sensitivity magnetometer 220, and send it to the instruction execution unit 222. The fourth power supply unit 223 is used to supply power to the second high-sensitivity magnetometer 220 and the fourth control processing unit 221.

[0044] The fourth control processing unit 221 in the downhole receiving device 22 can be reused with the first control processing unit 113 in the downhole transmitting device 11 in the uplink communication device 1, the fourth power supply unit 223 can be reused with the first power supply unit 116, and the downhole receiving device 22 is also integrated in the insulating stub 110.

[0045] The fourth power supply unit 223 serves as the common power supply for all downhole modules. Its output is connected to the power input terminals of the fourth control processing unit 221, the first power amplifier unit 115, and the second high-sensitivity magnetometer 220 via an internal power distribution board. The reference ground of all modules is shared at a single point on the internal power distribution board to suppress common-mode interference.

[0046] In downlink communication, the second time-varying electromagnetic field signal generated by the ground transmitter 21 is transmitted through the formation to the downhole insulating sub-section 110, detected by the second high-sensitivity magnetometer 220 and converted into a voltage signal. After adaptive filtering, signal amplification and demodulation by the fourth control processing unit 221, the original data transmitted downlink is restored, realizing the transmission of control commands from the ground to the downhole.

[0047] Furthermore, the first high-sensitivity magnetometer 120 and the second high-sensitivity magnetometer 220 have similar structures, but the difference is that the second high-sensitivity magnetometer 220 is externally equipped with a temperature-resistant encapsulation and a non-metallic pressure-resistant shell to meet the environmental adaptability requirements of high temperature and high pressure downhole.

[0048] In this invention, both bidirectional communication transmitters employ low-frequency electric field excitation; that is, uplink communication uses an asymmetric electric dipole antenna to transmit the electromagnetic field, while downlink communication uses an electric dipole antenna composed of ground electrodes and derrick electrodes to transmit the electromagnetic field, with frequencies not exceeding 200Hz. The receivers utilize a high-sensitivity magnetometer for magnetic field measurement. Based on the near-field propagation characteristics of low-frequency time-varying electromagnetic fields in conductive media, a magnetic field signal, rather than a traditional electric field signal, is chosen as the carrier for information data transmission.

[0049] For low-frequency time-varying electromagnetic fields, the wavelength is at least several kilometers, while the distance between the electric field source and the receiving field in long-distance well-to-ground communication is generally less than the wavelength. Therefore, electric dipoles in the near-field vacuum region... In spherical coordinates, the distribution of electric and magnetic fields can be expressed as: (1) (2) in, The charge density of an electric dipole. Indicates the length of the electric dipole. It is the distance from the source point to the field point. Indicates the attenuation coefficient. The phase constant, ρ is the vacuum permittivity. The electric field strength of a low-frequency time-varying electromagnetic field in the near field. With distance It decays cubically, while the magnetic field strength Distance only The attenuation is quadratic. In reality, electromagnetic fields propagate through conductive media. Considering the losses in the conductive medium, the attenuation rate of the magnetic field component in the conductive strata of the electromagnetic field emitted by the electric dipole is significantly lower than that of the electric field component.

[0050] Analyzing the characteristics of electric and magnetic field components from the perspective of electromagnetic field energy, the electric field energy density in a conductive medium. With magnetic field energy density satisfy: (3) (4) Typically, the dielectric constant is taken electrical conductivity f=100 Hz, we get =1.8E6× Therefore, in a conductive medium, the magnetic field energy density of a time-varying electromagnetic wave is much greater than the electric field energy density.

[0051] Therefore, based on the above electromagnetic field theory analysis, in the electromagnetic waves excited by electric dipoles, the magnetic field component decays more slowly and has a higher energy density in the near field compared to the electric field component. The signal transmission strategy of hybrid dipole coordination adopted in this invention is more suitable for high-speed long-distance bidirectional communication between wells and the ground.

[0052] Example 2 Based on the well-to-surface bidirectional communication device based on hybrid dipole coordination provided in Embodiment 1, this embodiment provides a well-to-surface bidirectional communication method based on hybrid dipole coordination. It employs a 2FSK binary frequency shift keying modulation scheme, preferably a dual-point carrier frequency, and uses the magnetic field components excited by the downhole asymmetric electric dipole antenna and the ground electrode as the signal carrier. A two-stage adaptive gain control algorithm is applied. The first stage of adaptive gain control normalizes the overall signal amplitude; the second stage of adaptive control equalizes the amplitudes of the two channel frequency signals to address the low signal-to-noise ratio problem caused by well site noise interference, thereby achieving effective demodulation for high-speed, long-distance bidirectional communication between the well and the surface.

[0053] Specifically, it includes the following steps: (1) The downhole transmitting device 11 is used to encode and modulate the collected downhole data and transmit the modulated first time-varying electromagnetic field signal to the earth medium. At the same time, the first high-sensitivity magnetometer 120 is used to receive the first time-varying electromagnetic field signal and decode the received first time-varying electromagnetic field signal to realize the uploading and communication of downhole data. (2) The ground transmitter 21 encodes and modulates the control command to be transmitted and transmits the modulated second time-varying electromagnetic field signal to the ground medium. At the same time, the second high-sensitivity magnetometer 220 receives the second time-varying electromagnetic field signal and decodes the received second time-varying electromagnetic field signal to realize the control command transmission communication.

[0054] Furthermore, step (1) above includes the following steps: (1.1) The downhole data collected by the data acquisition unit 114 is preprocessed by the first control processing unit 113 in the downhole transmitting device 11 to obtain a binary data stream; (1.2) The binary data stream is encoded and modulated using the 2FSK (Binary Frequency Shift Keying) signal modulation method to obtain the first encoded modulation signal; (1.3) After the first coded modulation signal is enhanced by the first power amplifier unit 115, it is loaded onto the asymmetric electric dipole antenna, and the asymmetric electric dipole antenna transmits the first time-varying electromagnetic field signal to the ground medium in accordance with the preset bidirectional communication mode. (1.4) The first high-sensitivity magnetometer 120 in the ground receiving device is used to receive the first time-varying electromagnetic field signal transmitted downhole and output the corresponding first voltage signal; (1.5) The first voltage signal is preprocessed and coherently demodulated using the second control processing unit 121 to recover the original downhole data.

[0055] Furthermore, in step (1.2) above, encoding and modulating the binary data stream using the 2FSK signal modulation method refers to mapping the binary data stream into alternating signals of two characteristic frequencies. Specifically, two different characteristic carrier frequencies within the range of 10-200Hz are used. and These correspond to the logical "1" and "0" in the binary data stream, respectively. By switching between the two carrier frequencies, the encoding and transmission of the raw downhole data are achieved.

[0056] Among them, 2FSK modulation signal The time-domain expression is: (5) in, The signal amplitude, This is the initial phase.

[0057] Furthermore, in the above step (1.3), the preset bidirectional communication mode can be used to perform half-duplex communication for uploading and downloading in an intermittent time-interleaved manner, or it can use different uplink and downlink carrier frequencies to achieve full-duplex bidirectional communication.

[0058] Furthermore, in step (1.5) above, during uplink (or downlink) communication, due to the differences in transmission characteristics of electromagnetic waves of different frequencies in the conductive medium of the stratum, the received signal often exhibits an imbalance between the two carrier frequency signals after 2FSK demodulation, leading to problems such as misjudgment and increased bit error rate during the sampling decision process. Based on this, the present invention employs a two-stage adaptive gain control strategy, namely, overall amplitude normalization control and dual-frequency carrier signal adaptive balance control, to improve the demodulation stability and reliability of the 2FSK signal under long-distance, low signal-to-noise ratio conditions.

[0059] Specifically, it includes the following steps: (1.5.1) Perform an overall energy assessment on the first voltage signal output by the first high-sensitivity magnetometer 120 and normalize its amplitude.

[0060] The specific method is as follows: First, based on the first voltage signal output by the first high-sensitivity magnetometer 120, the root mean square (RMS) value of the first voltage signal within a certain time window is calculated, and the amplitude of the original voltage signal is standardized to a target amplitude range close to unit 1 according to the RMS value, thereby eliminating the influence of different transmission distances and instantaneous channel interference fluctuations on the overall signal amplitude, and providing a stable and consistent input reference for subsequent demodulation.

[0061] (1.5.2) The normalized voltage signal is passed through a circuit with center frequencies of... and The bandpass filter is used to separate the signals, resulting in two frequency channels.

[0062] Among them, the voltage signal received after the first time-varying electromagnetic field signal undergoes transmission attenuation. The time-domain expression is: (6) in, carrier frequency The amplitude of the received signal, carrier frequency The amplitude of the received signal, This is the initial phase.

[0063] (1.5.3) Calculate the amplitude ratio of the two frequency channel signals obtained by separation, and perform adaptive amplitude compensation when the amplitude ratio exceeds the preset threshold.

[0064] The specific method is as follows: First, monitor and calculate the average amplitude of the two frequency channel signals respectively, and then calculate the amplitude ratio of the two frequency channel signals. Secondly, the calculated amplitude ratio is compared with a preset threshold. When the amplitude ratio exceeds the preset threshold, an adaptive compensation mechanism is triggered. The preset threshold is preferably set to ±3.5dB (corresponding to a linear amplitude ratio of approximately 1.5:1 or 0.67:1). Based on the average amplitude of the two frequency channel signals, the weaker frequency channel signal is amplified by gain, while the stronger frequency channel signal is attenuated to achieve amplitude balance between the two frequency channel signals (i.e., the amplitude ratio is as close to 1 as possible, for example, the amplitude ratio can be controlled within 1.2:1 or 1:1.2). Then, subsequent spectrum shifting, low-pass filtering, and sampling decision are performed.

[0065] (1.5.4) Multiply the two frequency channel signals after amplitude adaptive compensation with the locally generated in-phase and in-frequency carrier signal to achieve spectrum shifting.

[0066] Among them, for carrier frequency is and When demodulating the two frequency channel signals, they are respectively compared with the local carrier. and The resulting spectrum shift after multiplication is expressed as: (7) (8) (1.5.5) The multiplied signals of the two frequency channels are passed through a low-pass filter to remove high-frequency components and out-of-band noise, and the baseband signal components of the two frequency channels are extracted.

[0067] Among them, after low-pass filtering, the carrier frequency and carrier frequency The amplitude envelopes of the corresponding two baseband signal components are respectively and .

[0068] (1.5.6) The decision circuit is used to make a decision on the amplitude of the two baseband signal components, and each data bit is determined to be "1" or "0", thereby restoring the original downhole parameters.

[0069] When comparing the amplitudes of two received signals using a decision circuit, the decision method is as follows: like If so, then the symbol is determined to be a frequency. corresponding bits ; like If so, then the symbol is determined to be a frequency. corresponding bits This allows us to decode and obtain the original binary data information.

[0070] Furthermore, in step (2) above, the downlink communication process is similar to the uplink communication process in step (1). The difference is that in the downlink communication process, the ground transmitter encodes the control command and transmits the second time-varying electromagnetic field signal to the earth medium through the electric dipole antenna. The downhole receiver receives and processes the second time-varying electromagnetic field signal and sends the recovered control command to the command execution unit.

[0071] Example 3 This embodiment combines Figures 5 to 11The 2FSK signal modulation and demodulation method integrating adaptive gain control strategy in the well-to-ground two-way communication method based on hybrid dipole coordination proposed in Example 2 will be described in detail.

[0072] like Figure 5 The diagram illustrates a two-way communication 2FSK modulation and demodulation method. It employs coherent demodulation, using two high-quality-factor bandpass filters to separate the original received signal. and Frequency components, where the center frequencies of the two bandpass filters are respectively and ;and , The original data is then restored through spectrum shifting, low-pass filtering, and digital decision circuitry. Finally, the data is transmitted to the ground industrial control computer for display and storage via a standard interface.

[0073] like Figure 6 The image shows the time-domain waveform of the 2FSK modulated signal output by the first high-sensitivity magnetometer 120 at the receiving end, and the result after the first bandpass filtering. The received signal first enters the second control processing unit 121. After completing low-noise amplification and analog-to-digital conversion, the first-stage adaptive gain control is executed. This stage statistically analyzes the energy of the received signal within a preset time window, calculates the root mean square (RMS) value of the signal, and normalizes the overall amplitude of the signal to stabilize the signal amplitude within a preset target range, thereby providing a consistent input condition for subsequent demodulation.

[0074] After overall amplitude normalization, the signal is fed into a high-frequency bandpass filter and a low-frequency bandpass filter, whose center frequencies correspond to the two characteristic frequencies of 2FSK, respectively. The filtering results are as follows: Figure 7 As shown, due to the influence of formation frequency selective attenuation, the high-frequency channel and the low-frequency channel may still have inconsistent amplitudes after filtering.

[0075] Therefore, a second-level adaptive gain control is implemented, with the following effect: Figure 8 As shown, this stage monitors the signal amplitudes of the high-frequency and low-frequency channels in real time, calculates the average amplitude of the two channels, and compares them. When the amplitude ratio of the two channels exceeds a preset threshold (preferably ±3.5 dB), an adaptive channel balance compensation mechanism is triggered. During the compensation process, the average amplitude of the two channels is used as a reference level. Gain amplification is applied to the channel with the weaker amplitude, while attenuation is applied to the channel with the stronger amplitude, so that the two channel signals reach an amplitude balance state before entering subsequent processing.

[0076] After channel amplitude balancing is completed, the signals of the two frequency channels are coherently multiplied with locally generated in-phase and in-frequency carriers to achieve spectrum shifting. The result is as follows: Figure 9As shown, through spectrum shifting operations, effective information is transferred to the vicinity of low-frequency or DC components, while high-frequency components will be suppressed in subsequent processing.

[0077] Subsequently, the signal is passed through a low-pass filter to remove high-frequency noise and harmonic components, yielding the baseband signals for the corresponding two frequency channels, as shown below. Figure 10 As shown in the figure, after low-pass filtering and adaptive gain balancing, the baseband signal amplitude is stable and the noise suppression effect is obvious.

[0078] Finally, for the two frequency channel signals, symbol determination is completed by amplitude comparison, thereby recovering the original binary data stream. The demodulation result is as follows: Figure 11 As shown. By Figure 11 It can be seen that after introducing the adaptive gain control strategy, the demodulated output symbol boundary is clear, and the system demodulation stability and reliability are significantly improved.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A well-to-surface two-way communication device based on hybrid dipole coordination, characterized in that, include: The uplink communication device is configured to encode and modulate the collected downhole data using a downhole transmitter and transmit the modulated first time-varying electromagnetic field signal to the earth medium. At the same time, it uses a first magnetometer to receive the first time-varying electromagnetic field signal and decodes the received first time-varying electromagnetic field signal to realize downhole data uplink communication. The downlink communication device is configured to encode and modulate the control commands to be transmitted using a ground transmitter, and transmit the modulated second time-varying electromagnetic field signal to the ground medium. At the same time, it uses a second magnetometer to receive the second time-varying electromagnetic field signal and decodes the received second time-varying electromagnetic field signal to realize the control command downlink communication. The downhole transmitting device includes an insulating short section, which is rigidly connected to the upper drill pipe and the lower drill pipe respectively through a threaded structure. While transmitting drill pipe torque and bearing load, the insulating short section uses its own insulation properties to make the upper drill pipe and the lower drill pipe electrically insulated from each other, forming two positive and negative electrodes of an asymmetric electric dipole antenna. The ground-based transmitting device includes: a second control processing unit for encoding and modulating control commands to be transmitted; a second power amplification unit for amplifying the output signal of the second control processing unit and driving an alternating current; an electric dipole antenna for generating a second time-varying electromagnetic field signal under alternating current excitation and injecting it into the ground medium; and a second power supply unit for supplying power to the second control processing unit, the second power amplification unit, and the electric dipole antenna. Specifically, when encoding and modulating the collected downhole data or control commands to be transmitted, the 2FSK signal modulation method is used; when decoding the received first time-varying electromagnetic field signal and the second time-varying electromagnetic field signal, the 2FSK signal demodulation method and a two-level adaptive gain control strategy are used. The two-level adaptive gain control strategy includes overall amplitude normalization control and dual-frequency carrier signal adaptive balance control.

2. The well-to-surface bidirectional communication device based on hybrid dipole coordination as described in claim 1, characterized in that, The insulating short section contains a through-type pressure chamber, within which a downhole electronic transmission unit is installed. The downhole electronic transmission unit includes: The first control processing unit is connected to the data acquisition unit deployed near the drill bit via an internal bus. It is used to preprocess and encode the downhole data acquired in real time by the data acquisition unit and to control the transmission. The first power amplifier unit is used to amplify the output signal of the first control processing unit and drive the alternating current, so that the asymmetric electric dipole antenna generates a first time-varying electromagnetic field signal under the excitation of the alternating current. The first power supply unit is used to supply power to the data acquisition unit, the first control processing unit and the first power amplification unit.

3. The well-to-surface bidirectional communication device based on hybrid dipole coordination as described in claim 1, characterized in that, The first magnetometer and the second magnetometer are atomic magnetometers based on quantum effects; the first magnetometer is deployed within a range of 30-100m from the wellhead, the second magnetometer is deployed inside the insulating short section, and the second magnetometer is externally provided with a temperature-resistant encapsulation and a non-metallic pressure-resistant shell that meet preset requirements.

4. A well-to-surface bidirectional communication method based on hybrid dipole coordination, implemented using a well-to-surface bidirectional communication device based on hybrid dipole coordination as described in any one of claims 1 to 3, characterized in that, include: The downhole transmitting device encodes and modulates the collected downhole data and transmits the modulated first time-varying electromagnetic field signal to the earth medium. At the same time, the first magnetometer receives the first time-varying electromagnetic field signal and decodes the received first time-varying electromagnetic field signal to realize downhole data uploading and communication. The ground-based transmitter encodes and modulates the control commands to be transmitted, and transmits the modulated second time-varying electromagnetic field signal to the ground medium. At the same time, a second magnetometer receives the second time-varying electromagnetic field signal and decodes the received signal to realize the communication for transmitting control commands.

5. The well-to-surface bidirectional communication method based on hybrid dipole coordination as described in claim 4, characterized in that, The method involves encoding and modulating the collected downhole data using a downhole transmitting device, transmitting the modulated first time-varying electromagnetic field signal to the earth medium, and simultaneously receiving the first time-varying electromagnetic field signal using a first magnetometer and decoding the received signal to achieve downhole data upload communication, including: The collected downhole data is preprocessed using a downhole transmitter to obtain a binary data stream; The binary data stream is encoded and modulated using the 2FSK signal modulation method to obtain the first encoded signal. After enhancing the first coded signal, the first time-varying electromagnetic field signal is transmitted to the earth medium according to the preset two-way communication method; The first time-varying electromagnetic field signal is received using a first magnetometer, and the corresponding original voltage signal is output. The original voltage signal is decoded to recover the original downhole data.

6. The well-to-surface bidirectional communication method based on hybrid dipole coordination as described in claim 5, characterized in that, The decoding process of the original voltage signal to recover the original downhole data includes: The overall energy of the raw voltage signal output by the first magnetometer is evaluated, and the amplitude is normalized. The normalized voltage signal is passed through a circuit with center frequencies of... and The bandpass filter is used to separate the signals, resulting in two frequency channels, where, and These represent the carrier frequencies used in 2FSK signal modulation; The amplitude ratio of the two separated frequency channel signals is calculated, and adaptive amplitude compensation is performed when the amplitude ratio exceeds a preset threshold. The two frequency channel signals after amplitude adaptive compensation are multiplied with the locally generated in-phase and in-frequency carrier signal to achieve spectrum shifting. After the spectrum shifting, the two frequency channel signals are passed through a low-pass filter to extract the baseband signal components of the two frequency channel signals; The amplitude of the two baseband signal components is determined by a decision circuit, which determines whether each data bit is "1" or "0", thus obtaining the original downhole data.

7. The well-to-surface bidirectional communication method based on hybrid dipole coordination as described in claim 6, characterized in that, The process of performing an overall energy assessment and amplitude normalization on the raw voltage signal output by the first magnetometer includes: Based on the original voltage signal output by the first magnetometer, the root mean square value of the original voltage signal within a preset time window is calculated, and the amplitude of the original voltage signal is standardized to the target amplitude range according to the root mean square value.

8. The well-to-surface bidirectional communication method based on hybrid dipole coordination as described in claim 6, characterized in that, The calculation of the amplitude ratio of the two separated frequency channel signals, and the adaptive amplitude compensation when the amplitude ratio exceeds a preset threshold, includes: The average amplitude of the two frequency channel signals is monitored and calculated separately, and the amplitude ratio of the two frequency channel signals is calculated. The calculated amplitude ratio is compared with a preset threshold. When the amplitude ratio exceeds the preset threshold, an adaptive compensation mechanism is triggered. Using the average amplitude of the two frequency channel signals as a reference, the frequency channel signal with the weaker amplitude is amplified by gain, while the frequency channel signal with the stronger amplitude is attenuated, so that the two frequency channel signals reach an amplitude balance state. The balance state means that the amplitude ratio of the two frequency channel signals is controlled within a preset range.

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