Magnetic field sensing system and sensing method based on diamond nitrogen-quantum optical fiber probe

Abstract

The invention relates to the technical field of magnetic field sensors, in particular to a magnetic field sensing system and sensing method based on a diamond nitrogen-quantum optical fiber probe, and a three-component optical fiber quantum probe magnetic field sensor is obtained by assembling three quantum optical fiber probes with the same structure in three mutually orthogonal directions; the three-component optical fiber quantum probe magnetic field sensor and the three-component optical fiber attitude sensor are fixed in the metal sleeve; the three-component optical fiber quantum probe magnetic field sensor and the three-component optical fiber attitude sensor are connected with an optical excitation and collection system, a microwave modulation system, a signal processing and analysis system and a DTS modulation-demodulation instrument in the ground logging truck through an armored optical cable or an armored photoelectric composite cable. According to the invention, an underground, land, aviation and seabed three-component magnetic field data acquisition system can be conveniently constructed, and the system has the advantages of small size, light weight, low cost, high temperature resistance, high pressure resistance, no need of power supply for the sensor, no electronic device and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic field sensors, and in particular to a magnetic field sensing system and a sensing method based on a diamond nitrogen-quantum optical fiber probe. Background Art

[0002] Magnetic field measurement has important applications in numerous fields, including biomedical imaging, geological exploration, and military detection. Traditional magnetic field sensors suffer from limited sensitivity, poor interference immunity, and difficulty in miniaturization. Diamond nitrogen-vacancy color centers (NV centers), as quantum sensors, have attracted widespread attention in recent years due to their high sensitivity and high spatial resolution.

[0003] In recent years, magnetic field sensing has played an increasingly important role in many fields, including scientific research and engineering applications. However, the structure and cost of traditional magnetic field sensors based on sensing principles such as the Hall effect, magnetoresistance effect, and fluxgate still need improvement. Fiber-optic magnetic field sensors are gaining increasing attention due to their light weight, compact size, low cost, and remote controllability. Traditional optical fibers, made of materials such as quartz, are not easily affected by electromagnetic signals. Therefore, fiber-optic magnetic field sensors require specially designed fiber structures and magnetosensitive materials to enable the ambient magnetic field to modulate the physical properties of the light waves in the fiber, such as phase, intensity, and frequency. Summary of the Invention

[0004] The present invention aims to solve the problems of existing magnetic field sensors such as insufficient sensitivity, difficulty in miniaturization, weak anti-interference ability, and high-temperature resistance. It provides a magnetic field sensing system and sensing method based on diamond nitrogen-quantum fiber probe to achieve high-sensitivity, high-precision, miniaturized, and remotely measurable magnetic field detection.

[0005] The technical problem to be solved by the present invention is that traditional optical fiber magnetic field sensors are not easily affected by electromagnetic signals and are difficult to apply well in special environments such as underground, in the air, and on the seabed. The environmental magnetic field cannot modulate the physical properties of light waves in the optical fiber, such as the phase, intensity, and frequency. The purpose of the present invention is to provide a three-component magnetic field sensor and sensing method based on an optical fiber quantum probe with a diamond nitrogen-vacancy color center, so that the environmental magnetic field can modulate the physical properties of light waves in the optical fiber, such as the phase, intensity, and frequency.

[0006] The present invention is achieved through the following technical solutions:

[0007] The magnetic field sensing system based on diamond nitrogen-quantum fiber probes consists of three quantum fiber probes with the same structure, which are assembled in three mutually orthogonal directions to obtain a three-component fiber quantum probe magnetic field sensor. It also includes a three-component fiber attitude sensor fixed behind the three-component fiber quantum probe magnetic field sensor.

[0008] The three-component optical fiber quantum probe magnetic field sensor and the three-component optical fiber attitude sensor can realize the three-component magnetic field signal measurement in a long-distance high-temperature environment, such as a deep underground borehole, through a long-distance armored optical cable or armored optoelectronic composite cable with built-in high-temperature resistant and hydrogen-loss resistant single-mode and multi-mode optical fibers.

[0009] The three-component optical fiber quantum probe magnetic field sensor and the three-component optical fiber attitude sensor are fixed in a metal sleeve and connected to the logging vehicle through an armored optical cable or an armored optoelectronic composite cable. The metal sleeve is made of non-magnetic titanium alloy or non-magnetic alloy steel material or non-metallic high-temperature resistant and high-strength composite material.

[0010] The logging vehicle is equipped with an optical excitation and collection system, a microwave modulation system, a signal processing and analysis system, a DTS modem, an armored optical cable or an armored optoelectronic composite cable, and a quantum optical fiber probe encapsulated in a metal sleeve.

[0011] The three-component fiber optic quantum probe magnetic field sensor is connected to the optical excitation and collection system, microwave modulation system, and signal processing and analysis system in the logging vehicle through an armored optical cable or an armored optoelectronic composite cable.

[0012] The quantum fiber probe is a special diamond-doped quantum fiber probe based on sol-gel doped diamond nanoparticles containing nitrogen-vacancy color centers; the optical excitation and collection system is used to excite the nitrogen-vacancy color centers in the diamond microstructure and collect the fluorescence emitted; the microwave modulation system is used to apply a microwave field to the nitrogen-vacancy color centers; and the signal processing and analysis system is used to determine the size and distribution of the magnetic field to be measured based on changes in fluorescence intensity.

[0013] The quantum fiber probe uses a single-mode or multimode optical fiber, one end of which is integrated with a diamond microstructure (such as diamond micropillars or microparticles) containing nitrogen-vacancy color centers. The diamond microstructure can be prepared by etching, detonation, ion implantation, and other methods, and fixed to the end of the optical fiber through a specific process (such as immersion or bonding).

[0014] The optical excitation and collection system includes a laser, a fiber coupler, an objective lens, and filters. The laser emits laser light of a specific wavelength (e.g., 532 nm), which is focused by the fiber coupler and objective lens onto the NV color centers in the diamond microstructure, thereby stimulating them to produce fluorescence. This fluorescence is collected by the optical fiber and transmitted to the detection end.

[0015] The microwave modulation system includes a microwave source and a microwave antenna. The microwave antenna can be a U-shaped or Ω-ring structure, fixed to the end of an optical fiber or near a diamond microstructure, and is used to apply a microwave field to the NV color center to achieve electron spin resonance.

[0016] The signal processing and analysis system consists of a photodetector, a signal analyzer, and a computer. The photodetector collects the fluorescence signal and converts it into an electrical signal. The signal analyzer processes and analyzes the electrical signal. The computer calculates the magnitude and distribution of the magnetic field to be measured based on data such as how the fluorescence intensity changes with microwave frequency.

[0017] The sensing method of the magnetic field sensing system based on the diamond nitrogen-quantum fiber probe comprises the following steps:

[0018] 1. Connect the quantum fiber probe encapsulated in the metal sleeve to the armored optical cable, and slowly lower the three-component fiber quantum probe magnetic field sensor to the bottom of a vertical well or a low-angle well via a logging vehicle;

[0019] 2. For high-angle wells or horizontal wells, connect the quantum fiber probe encapsulated in the metal sleeve to the armored optoelectronic composite cable. Then, install a downhole crawler at the tail end of the three-component optical fiber quantum probe magnetic field sensor. Install a DC power supply in the logging vehicle. Use the DC power supply in the logging vehicle and the armored optoelectronic composite cable to drive the downhole crawler to drag the three-component optical fiber quantum probe magnetic field sensor to the end of the horizontal well.

[0020] 3. Connect the single-mode optical fiber in the armored optical cable or armored optoelectronic composite cable at the wellhead to the optical excitation and collection system, microwave modulation system, and signal processing and analysis system in the logging vehicle; connect the multi-mode optical fiber in the armored optical cable or armored optoelectronic composite cable at the wellhead to the signal input terminal of the DTS modem instrument in the logging vehicle;

[0021] 4. Start the optical excitation and collection system, microwave modulation system, and signal processing and analysis system in the logging vehicle to perform system self-checks and comprehensive tests on the three-component fiber optic quantum probe magnetic field sensor at the bottom of the well to ensure that the three-component fiber optic quantum probe magnetic field sensor at the bottom of the well can collect the correct three-component magnetic field signal downhole and the three-component attitude signal of the magnetic field sensor;

[0022] 5. After the three-component fiber optic quantum probe magnetic field sensor is lowered to the bottom of a vertical well or a low-angle well, or to the end of a high-angle well or a horizontal well, the three-component fiber optic quantum probe magnetic field sensor begins to collect three-component magnetic field signals in the well. The three-component fiber optic attitude sensor collects three-component attitude data of the three-component fiber optic quantum probe magnetic field sensor at each magnetic field data collection position in the well. At the same time, the electric winch in the logging vehicle is started to slowly and uniformly lift the three-component fiber optic quantum probe magnetic field sensor to the wellhead.

[0023] 6. While the three-component fiber optic quantum probe magnetic field sensor is being slowly and uniformly lifted to the wellhead, the three-component magnetic field data of the entire well section is continuously collected. The three-component fiber optic attitude sensor collects the three-component attitude data of the three-component fiber optic quantum probe magnetic field sensor at each magnetic field data collection moment. The multimode optical fiber in the armored optical cable or armored optoelectronic composite cable and the DTS modem instrument in the logging vehicle synchronously measure the temperature on the armored optoelectronic composite cable.

[0024] 7. After completing the three-component magnetic field data acquisition of the entire well section in step S6, it is first necessary to correct the temperature drift of the three-component optical fiber quantum probe magnetic field sensor (5) according to the temperature at the location measured by the DTS modulation and demodulation instrument (10); then it is necessary to pre-process the three-component magnetic field raw data collected in the entire well section by rotating and converting the three-component attitude data recorded at each three-component magnetic field data acquisition location. The processing steps are as follows: (1) According to the inclination angle of the three-component optical fiber quantum probe magnetic field sensor (5) recorded by the three-component optical fiber attitude sensor (6) at each magnetic field data acquisition location, the vertical component H of the three-component magnetic field raw data at that location is converted into the value of the rotation angle. Z (2) according to the azimuth angle of the three-component optical fiber quantum probe magnetic field sensor (5) recorded by the three-component optical fiber attitude sensor (6) at each magnetic field data acquisition position, a horizontal component H of the three-component magnetic field raw data that has been rotated to a direction perpendicular to the ground plane at that position X (3) according to the azimuth of the three-component optical fiber quantum probe magnetic field sensor (5) recorded by the three-component optical fiber attitude sensor (6) at each magnetic field data acquisition position, the position has been rotated to another horizontal component H of the three-component magnetic field raw data in the direction perpendicular to the ground plane Y Rotate to the north-south direction;

[0025] 8. After completing the rotation preprocessing of the three-component magnetic field data of the entire well section in step 7, it is also necessary to rotate the vertical magnetic field component H perpendicular to the ground plane according to the well trajectory data. Z and two horizontal magnetic field components H parallel to the east-west and north-south directions respectively X and H Y Project them onto the well trajectory perpendicular to the ground, and assign the original measured depth value of the three-component magnetic field data of each measurement position to the vertical depth value after projection;

[0026] 9. Finally, the three-component magnetic field data (H Z ,H X ,H Y ) Comprehensive interpretation based on the magnetic parameters of the formation rocks or minerals passed by the well trajectory;

[0027] 10. In the absence of an active electrical source (power supply electrode) or magnetic source (coil inputting alternating current) in the air, on the ground, or in the same well or adjacent well, the three-component magnetic field data (H Z ,H X ,H Y ) analysis and interpretation to identify the distribution characteristics and patterns of highly magnetic abnormal geological bodies or highly magnetic abnormal ore bodies (such as pyrite, hematite, vanadium-titanium magnetite, etc.) in the underground strata along the well trajectory;

[0028] 11. Under the stimulation of an active electrical source (power supply electrode) or magnetic source (coil inputting alternating current) deployed in the air, on the ground, in the same well or in a nearby well, the three-component magnetic field data (H Z ,H X ,H Y ) analysis and interpretation, and identify the distribution characteristics and laws of high electromagnetic anomaly geological bodies along the well trajectory generated by rocks or minerals in the downhole strata under the excitation of active source electric field or active source magnetic field.

[0029] The NV color center effect refers to the phenomenon in diamond where a carbon atom is replaced by a nitrogen atom, with a missing carbon atom surrounding the nitrogen atom. The main advantage of NV color centers is that the solid-state spin of diamond nitrogen vacancy (NV-) color centers can simultaneously meet the requirements of high sensitivity and high spatial resolution magnetic detection. NV atomic magnetometers also feature small size, long spin coherence time, a wide operating temperature range, high stability, and fast startup time.

[0030] The ground state of the NV color center is the triplet state, corresponding to the three states Ms = 0 and Ms = ±1. Among them, the +1 and -1 states are degenerate doublet states in the absence of a magnetic field (equivalent to overlapping together). When there is a magnetic field, the degenerate doublet states will separate.

[0031] The wavelength corresponding to the energy of the ground and excited states of an NV center is 637 nm. Therefore, when a laser with a wavelength less than 637 nm is irradiated upon an NV center, electrons in the ground state absorb energy and transition to an excited state. However, since excited state electrons are unstable, they undergo a transition, generating radiation (luminescence) back to the ground state. However, electrons in the excited state Ms = ±1 do not return completely back to the original path. Some transition directly to the ground state, while others undergo a radiationless transition, decaying to a metastable state through internal cross-relaxation, and then transitioning back to the ground state again. This process does not emit radiation (i.e., no luminescence). For NV centers, the transition of NV spins between the ground and excited states is conserved. However, transitions through metastable states are not conserved. Since transitions through metastable states are radiationless, the greater the probability of transitions through metastable states, the weaker the fluorescence. Therefore, we can determine the electron spin state of the NV color center by the intensity of fluorescence.

[0032] In a non-magnetic field environment, under the scanning of the continuous spectrum, the ground state electrons of the NV color center first transition from the ground state to the ground state. Since it is a non-magnetic field environment, Ms = ±1 is a degenerate doublet state at this time, and the transition will occur at a frequency of 2.87 GHz. The continuous spectrum will only produce a peak at 2.87 GHz. When in an environment with a magnetic field, due to the effect of the magnetic field, the two states of the degenerate doublet state will separate, and the energy difference between them is 2γB. They are symmetrically distributed with 2.87 GHz as the center, so under the action of the continuous spectrum, two peaks will appear. These two peaks are symmetrically distributed relative to 2.87 GHz. Therefore, when measuring, you only need to know the distance between the two peaks. Since γ is a known quantity, you can get the magnitude of the magnetic field B.

[0033] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0034] 1. High sensitivity: Utilizing the quantum properties of NV color centers and combining them with fiber optic technology, highly sensitive detection of extremely weak magnetic fields can be achieved, with the minimum detectable magnetic field strength reaching the nanotesla level.

[0035] 2. Miniaturization and portability: The entire sensor system has a compact structure, small size, light weight, easy to carry and operate, and can be used in a variety of complex environments and confined spaces;

[0036] 3. Strong anti-interference ability: Fiber optic transmission has good electromagnetic shielding performance, which can effectively reduce the impact of external electromagnetic interference on magnetic field measurement and improve measurement accuracy and stability;

[0037] 4. Remote measurement and real-time monitoring: By transmitting optical signals through optical fibers, remote measurement and real-time monitoring can be achieved, making it easier to detect magnetic fields in hazardous environments or inaccessible areas.

[0038] 5. Multi-field application: The sensor system has a wide range of application prospects and can meet the needs of high-precision magnetic field measurement in multiple fields such as biomedicine, geological exploration, military, and industry;

[0039] 6. This invention utilizes a fiber-optic magnetic field sensor based on a fiber-optic quantum probe of diamond nitrogen-vacancy color centers, which can be used to conveniently construct a three-component magnetic field data acquisition system for downhole, land, air, and seabed locations. This fiber-optic magnetic field sensor offers advantages such as small size, light weight, low cost, high temperature and high voltage resistance, no power supply required, and no electronic components connected to the fiber-optic magnetic field sensor. A three-channel, highly sensitive DSS modem instrument, located remotely from the fiber-optic magnetic field sensor, directly measures the three-component magnetic field signals downhole, on the ground, in the air, and on the seabed.

[0040] The present invention relates to a magnetic field sensing system and sensing method based on a diamond nitrogen-quantum fiber probe. The diamond-fiber probe can measure physical quantities such as the magnetic field, temperature, and microwave field around the probe by exciting the nitrogen-vacancy color center and collecting fluorescence. The NV color center emits fluorescence under laser excitation, and its fluorescence intensity is related to the electron spin state. When a microwave field of a specific frequency is applied, the electron spin state of the NV color center undergoes a resonant transition, resulting in a change in the fluorescence intensity. Under the action of an external magnetic field, the energy level of the NV color center undergoes Zeeman splitting, causing the resonant frequency to shift. By measuring the curve of the fluorescence intensity changing with the microwave frequency and combining it with the Zeeman splitting formula, the size and direction of the external magnetic field can be determined.

[0041] The magnetic field sensing system and sensing method based on diamond nitrogen-quantum fiber probe can be applied to the following fields:

[0042] 1. Biomedical imaging: It can be used to detect weak magnetic field signals in biological tissues, such as magnetocardiography and magnetoencephalography, to achieve non-invasive detection of human physiological functions;

[0043] 2. Geological exploration: Detecting underground magnetic field anomalies, searching for mineral resources, oil and gas fields, etc., with the advantages of high sensitivity and high resolution;

[0044] 3. Military detection: used to detect magnetic field signals generated by military targets such as mines and submarines to improve detection accuracy and reliability;

[0045] 4. Industrial detection: monitor the magnetic field distribution of motors, transformers and other equipment to achieve fault diagnosis and status monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the examples. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be considered as limiting the scope. A person of ordinary skill in the art can also derive other relevant drawings based on these drawings without inventive effort. In the drawings:

[0047] Figure 1 Schematic diagram of the quantum fiber probe structure;

[0048] Figure 2 This is a schematic diagram of the structure of a three-component fiber quantum probe magnetic field sensor;

[0049] Figure 3 Schematic diagram of a three-component optical fiber quantum probe magnetic field sensor collecting three-component magnetic field data downhole;

[0050] Figure 4 Schematic diagram of a three-component fiber optic quantum probe magnetic field sensor collecting three-component magnetic field data in a horizontal well.

[0051] Markings and corresponding parts names in the accompanying drawings:

[0052] 1-Quantum fiber probe, 1a-Fiber cladding, 1b-Fiber core, 1c-Diamond microstructure, 2-Optical excitation and collection system, 3-Microwave modulation system, 4-Signal processing and analysis system, 5-Three-component fiber quantum probe magnetic field sensor, 6-Three-component fiber attitude sensor, 7-Armored optical cable, 8-Metal sleeve, 9-Logging vehicle, 10-DTS modem instrument, 11-Downhole crawler, 12-DC power supply, 13-Armored optoelectronic composite cable. DETAILED DESCRIPTION

[0053] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with examples and drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0054] The quantum fiber probe 1 is a specially made diamond-doped quantum fiber probe based on sol-gel doped diamond nanoparticles containing nitrogen-vacancy color centers; the optical excitation and collection system 2 is used to excite the nitrogen-vacancy color centers in the diamond microstructure and collect the fluorescence emitted by them; the microwave modulation system 3 is used to apply a microwave field to the nitrogen-vacancy color centers; and the signal processing and analysis system 4 is used to determine the size and distribution of the magnetic field to be measured based on changes in fluorescence intensity.

[0055] Figure 1A schematic diagram of the quantum fiber probe structure is shown. The quantum fiber probe 1 utilizes a single-mode or multimode optical fiber, comprising an outer fiber cladding 1a and an inner fiber core 1b. One end of the probe is integrated with a diamond microstructure 1c (such as a diamond micropillar or microparticle) containing a nitrogen-vacancy color center. The diamond microstructure 1c can be fabricated through methods such as etching, detonation, and ion implantation, and then secured to the end of the optical fiber using a specific process (such as immersion or bonding).

[0056] The optical excitation and collection system 2 includes a laser, a fiber coupler, an objective lens, and filters. The laser emits laser light at a specific wavelength (e.g., 532 nm) and focuses it through the fiber coupler and objective lens onto the NV color centers in the diamond microstructure, exciting them to produce fluorescence. This fluorescence is collected by the optical fiber and transmitted to the detection end.

[0057] The microwave modulation system 3 includes a microwave source, a microwave antenna, etc. The microwave antenna can be in a U-shaped or Ω-ring structure, fixed to the end of the optical fiber or near the diamond microstructure, and is used to apply a microwave field to the NV color center to achieve electron spin resonance.

[0058] The signal processing and analysis system 4 consists of a photodetector, a signal analyzer, and a computer. The photodetector collects the fluorescence signal and converts it into an electrical signal. The signal analyzer processes and analyzes the electrical signal. The computer calculates the magnitude and distribution of the magnetic field to be measured based on data such as the variation of fluorescence intensity with microwave frequency.

[0059] Figure 2 A schematic structural diagram of a three-component fiber optic quantum probe magnetic field sensor 5 is shown. The three-component fiber optic quantum probe magnetic field sensor 5 is obtained by assembling three quantum fiber optic probes 1 with the same structure in three mutually orthogonal directions. The three-component fiber optic quantum probe magnetic field sensor 5 is based on a diamond nitrogen-vacancy color center fiber optic quantum probe, and also includes a three-component fiber optic attitude sensor 6 fixed behind the three-component fiber optic quantum probe magnetic field sensor 5.

[0060] The three-component fiber quantum probe magnetic field sensor 5 and the three-component fiber attitude sensor 6 can achieve three-component magnetic field signal measurement in a long-distance high-temperature environment, such as a deep underground borehole, through a long-distance armored optical cable 7 or armored optical fiber composite cable 13 with built-in high-temperature and hydrogen-loss resistant single-mode and multi-mode optical fibers. The three-component fiber quantum probe magnetic field sensor 5 and the three-component fiber attitude sensor 6 are fixed in a metal sleeve 8 and connected to the logging vehicle 9 via the armored optical cable 7 or armored optical fiber composite cable 13. The metal sleeve 8 is made of non-magnetic titanium alloy, non-magnetic alloy steel material, or non-metallic high-temperature resistant and high-strength composite material.

[0061] Figure 3 This is a schematic diagram of a three-component optical fiber quantum probe magnetic field sensor 5 collecting three-component magnetic field data underground.

[0062] The magnetic field sensing system based on the diamond nitrogen-quantum fiber probe includes: an optical excitation and collection system 2 installed in a logging vehicle 9, a microwave modulation system 3, a signal processing and analysis system 4, an armored optical cable 7, a quantum fiber probe 1 encapsulated in a metal sleeve 8, and a DTS modem 10. The three-component fiber quantum probe magnetic field sensor 5 is connected to the optical excitation and collection system 2, microwave modulation system 3, and signal processing and analysis system 4 in the logging vehicle 9 via the armored optical cable 7.

[0063] The sensing method of the magnetic field sensing system based on the diamond nitrogen-quantum fiber probe comprises the following steps:

[0064] S1. Connect the quantum fiber probe 1 encapsulated in the metal sleeve 8 to the armored optical cable 7 or armored optoelectronic composite cable 13, and slowly lower the three-component optical fiber quantum probe magnetic field sensor 5 to the bottom of a vertical well or a low-angle well via a logging vehicle 9;

[0065] S2, such as Figure 4 As shown, for a high-angle well or horizontal well, the quantum fiber probe 1 encapsulated in the metal sleeve 8 is connected to the armored optoelectronic composite cable 13. Then, a downhole crawler 11 is installed at the tail end of the three-component optical fiber quantum probe magnetic field sensor 5. A DC power supply 12 is installed in the logging vehicle 9. The DC power supply 12 in the logging vehicle 9 and the armored optoelectronic composite cable 13 drive the downhole crawler 11 to drag the three-component optical fiber quantum probe magnetic field sensor 5 to the end of the horizontal well. Figure 4 Schematic diagram of a three-component optical fiber quantum probe magnetic field sensor system collecting three-component magnetic field data in a horizontal well;

[0066] S3, connecting the single-mode optical fiber in the armored optical cable 7 or armored optoelectronic composite cable 13 at the wellhead to the optical excitation and collection system 2, microwave modulation system 3, and signal processing and analysis system 4 in the logging vehicle 9; connecting the multi-mode optical fiber in the armored optical cable 7 or armored optoelectronic composite cable 13 at the wellhead to the signal input terminal of the DTS modem instrument 10 in the logging vehicle 9;

[0067] S4. Start the optical excitation and collection system 2, microwave modulation system 3, and signal processing and analysis system 4 in the logging vehicle 9 to perform a system self-check and comprehensive test on the three-component optical fiber quantum probe magnetic field sensor 5 at the bottom of the well to ensure that the three-component optical fiber quantum probe magnetic field sensor 5 at the bottom of the well can collect the correct three-component magnetic field signal downhole and the three-component attitude signal of the magnetic field sensor;

[0068] S5. After the three-component optical fiber quantum probe magnetic field sensor 5 is lowered to the bottom of a vertical well or a low-angle well, or to the end of a high-angle well or a horizontal well, the three-component optical fiber quantum probe magnetic field sensor 5 begins to collect three-component magnetic field signals in the well, and the three-component optical fiber attitude sensor 6 collects three-component attitude data of the three-component optical fiber quantum probe magnetic field sensor 5 at each magnetic field measurement position in the well. At the same time, the electric winch in the logging vehicle 9 is started to lift the three-component optical fiber quantum probe magnetic field sensor 5 to the wellhead at a uniform and slow speed.

[0069] S6. During the process of slowly and uniformly lifting the three-component optical fiber quantum probe magnetic field sensor 5 to the wellhead, the three-component optical fiber quantum probe magnetic field sensor 5 continuously collects three-component magnetic field data of the entire well section, the three-component optical fiber attitude sensor 6 collects three-component attitude data of the position of the three-component optical fiber quantum probe magnetic field sensor 5 at each magnetic field data collection moment, and the multimode optical fiber in the armored optical cable 7 or armored optoelectronic composite cable 13 and the DTS modem instrument 10 in the logging vehicle 9 synchronously measure the temperature on the armored optoelectronic composite cable;

[0070] S7. After completing the three-component magnetic field data acquisition of the entire well section in step S6, it is first necessary to correct the temperature drift of the three-component optical fiber quantum probe magnetic field sensor 5 according to the temperature at the location measured by the DTS modem instrument 10; then it is necessary to pre-process the three-component magnetic field raw data collected in the entire well section by rotating and converting the three-component attitude data recorded at each three-component magnetic field data acquisition position.

[0071] The processing steps are as follows:

[0072] (1) According to the inclination angle of the three-component optical fiber quantum probe magnetic field sensor 5 at each magnetic field data acquisition position recorded by the three-component optical fiber attitude sensor 6, the vertical component H of the three-component magnetic field raw data is converted to Z Rotate to a direction perpendicular to the ground plane;

[0073] (2) According to the azimuth angle of the three-component optical fiber quantum probe magnetic field sensor 5 at each magnetic field data acquisition position recorded by the three-component optical fiber attitude sensor 6, a horizontal component H of the three-component magnetic field raw data that has been rotated to a direction perpendicular to the ground plane is X Rotate to an east-west direction;

[0074] (3) According to the azimuth angle of the three-component optical fiber quantum probe magnetic field sensor 5 at each magnetic field data acquisition position recorded by the three-component optical fiber attitude sensor 6, the other horizontal component H of the three-component magnetic field raw data that has been rotated to a direction perpendicular to the ground plane is Y Rotate to the north-south direction;

[0075] S8. After completing the rotation preprocessing of the three-component magnetic field data of the entire well section in step S7, it is also necessary to rotate the vertical magnetic field component H perpendicular to the ground plane according to the well trajectory data. Z and two horizontal magnetic field components H parallel to the east-west and north-south directions respectively X and H Y Project them onto the well trajectory perpendicular to the ground, and assign the original measured depth value of the three-component magnetic field data of each magnetic field measurement position to the vertical depth value after projection;

[0076] S9, finally, the three-component magnetic field data (H) obtained in step S8 distributed along the well trajectory perpendicular to the ground Z ,H X ,H Y ) Comprehensive interpretation based on the magnetic parameters of the formation rocks or minerals passed by the well trajectory;

[0077] S10, in the absence of an active electrical source (power supply electrode) or magnetic source (coil inputting alternating current) in the air, on the ground, in the same well, or in a nearby well, by analyzing the three-component magnetic field data (H) obtained in step S8 distributed along the well trajectory perpendicular to the ground. Z ,H X ,H Y ) analysis and interpretation to identify the distribution characteristics and patterns of highly magnetic abnormal geological bodies or highly magnetic abnormal ore bodies (such as pyrite, hematite, vanadium-titanium magnetite, etc.) in the underground strata along the well trajectory;

[0078] S11, under the stimulation of an active electrical source (power supply electrode) or magnetic source (coil inputting alternating current) deployed in the air, on the ground, in the same well, or in a nearby well, the three-component magnetic field data (H) obtained in step S8 distributed along the well trajectory perpendicular to the ground are analyzed. Z ,H X ,H Y ) analysis and interpretation, and identify the distribution characteristics and laws of high electromagnetic anomaly geological bodies along the well trajectory generated by rocks or minerals in the downhole strata under the excitation of active source electric field or active source magnetic field.

[0079] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A magnetic field sensing system based on diamond nitrogen-quantum fiber probe, characterized in that: A three-component optical fiber quantum probe magnetic field sensor (5) is obtained by assembling three quantum optical fiber probes (1) with the same structure in three mutually orthogonal directions; It also includes a three-component optical fiber attitude sensor (6) fixed behind the three-component optical fiber quantum probe magnetic field sensor (5); The three-component optical fiber quantum probe magnetic field sensor (5) and the three-component optical fiber attitude sensor (6) realize three-component magnetic field signal measurement in a long-distance high-temperature environment through an armored optical cable (7) or an armored optoelectronic composite cable (13); the armored optical cable (7) or the armored optoelectronic composite cable (13) has built-in single-mode optical fiber and multi-mode optical fiber that are resistant to high temperature and hydrogen loss; The three-component optical fiber quantum probe magnetic field sensor (5) and the three-component optical fiber attitude sensor (6) are fixed in a metal sleeve (8), and the metal sleeve (8) is made of a non-magnetic titanium alloy or a non-magnetic alloy steel material or a non-metallic high-temperature-resistant high-strength composite material; the three-component optical fiber quantum probe magnetic field sensor (5) and the three-component optical fiber attitude sensor (6) are connected to an optical excitation and collection system (2), a microwave modulation system (3), a signal processing and analysis system (4), and a DTS modem (10) built into a ground logging vehicle (9) via an armored optical cable (7) or an armored optoelectronic composite cable (13).

2. A magnetic field sensing system based on diamond nitrogen-quantum fiber probe according to claim 1, characterized in that: The quantum optical fiber probe (1) is a specially made diamond-doped quantum optical fiber probe based on sol-gel doping of diamond nanoparticles containing nitrogen-vacancy color centers; The optical excitation and collection system (2) is used to excite nitrogen-vacancy color centers in the diamond microstructure and collect the fluorescence emitted; The microwave modulation system (3) is used to apply a microwave field to the nitrogen-vacancy color center; The signal processing and analysis system (4) is used to determine the size and distribution of the magnetic field to be measured according to the change in fluorescence intensity.

3. A magnetic field sensing system based on diamond nitrogen-quantum fiber probe according to claim 2, characterized in that: The quantum optical fiber probe (1) adopts a single-mode optical fiber or a multi-mode optical fiber, and a diamond microstructure containing a nitrogen-vacancy color center is integrated at one end of the optical fiber; the diamond microstructure is prepared by etching, detonation or ion implantation, and fixed to the end of the optical fiber.

4. The magnetic field sensing system based on diamond nitrogen-quantum fiber probe according to claim 2, characterized in that: The optical excitation and collection system (2) comprises a laser, a fiber coupler, an objective lens and a filter; the laser emits laser light of a specific wavelength, which is focused onto the NV color center in the diamond microstructure through the fiber coupler and the objective lens, thereby exciting the NV color center to produce fluorescence; The fluorescence is collected via optical fibers and transmitted to a signal processing and analysis system (4).

5. The magnetic field sensing system based on diamond nitrogen-quantum fiber probe according to claim 2, characterized in that: The microwave modulation system (3) comprises a microwave source and a microwave antenna; the microwave antenna adopts a "U"-shaped or "Ω ring" structure and is fixed at the end of the optical fiber or near the diamond microstructure, and is used to apply a microwave field to the NV color center to achieve electron spin resonance.

6. The magnetic field sensing system based on diamond nitrogen-quantum fiber probe according to claim 2, characterized in that: The signal processing and analysis system (4) includes a photoelectric detector, a signal analyzer and a computer; the photoelectric detector collects the fluorescence signal and converts it into an electrical signal, the signal analyzer processes and analyzes the electrical signal, and the computer calculates the size and distribution of the magnetic field to be measured based on the data of the change law of fluorescence intensity with microwave frequency.

7. A magnetic field sensing method based on diamond nitrogen-quantum fiber probe, characterized in that: A magnetic field sensing system based on a diamond nitrogen-quantum fiber probe according to any one of claims 1 to 6 is used; the method comprising the following steps: S1, connecting the quantum optical fiber probe (1) encapsulated in the metal sleeve (8) to the armored optical cable (7), and slowly lowering the three-component optical fiber quantum probe magnetic field sensor (5) to the bottom of a vertical well or a low-angle well via a logging vehicle (9); S2. For a high-angle well or a horizontal well, the quantum optical fiber probe (1) encapsulated in the metal sleeve (8) is connected to the armored photoelectric composite cable (13), and then a downhole crawler (11) is installed at the tail end of the three-component optical fiber quantum probe magnetic field sensor (5). A DC power supply (12) is installed in the logging vehicle (9), and the DC power supply (12) in the logging vehicle (9) and the armored photoelectric composite cable (13) are used to drive the downhole crawler (11) to drag the three-component optical fiber quantum probe magnetic field sensor (5) to the end of the horizontal well; S3, connecting the single-mode optical fiber in the armored optical cable (7) or armored optoelectronic composite cable (13) at the wellhead to the optical excitation and collection system (2), microwave modulation system (3) and signal processing and analysis system (4) in the logging vehicle (9); connecting the multi-mode optical fiber in the armored optical cable (7) or armored optoelectronic composite cable (13) at the wellhead to the signal input end of the DTS modulation and demodulation instrument (10) in the logging vehicle (9); S4, starting the optical excitation and collection system (2), the microwave modulation system (3), and the signal processing and analysis system (4) in the logging vehicle (9), and performing a system self-check and comprehensive test on the three-component optical fiber quantum probe magnetic field sensor (5) and the three-component optical fiber attitude sensor (6) at the bottom of the well, to ensure that the three-component optical fiber quantum probe magnetic field sensor (5) and the three-component optical fiber attitude sensor (6) at the bottom of the well can collect the correct three-component magnetic field signal downhole and the three-component attitude signal of the magnetic field sensor; S5. After the three-component optical fiber quantum probe magnetic field sensor (5) is lowered to the bottom of a vertical well or a low-angle well or the end of a high-angle well or a horizontal well, the three-component optical fiber quantum probe magnetic field sensor (5) begins to collect three-component magnetic field signals in the well, and the three-component optical fiber attitude sensor (6) collects three-component attitude data of the three-component optical fiber quantum probe magnetic field sensor (5) at each position in the well. At the same time, the electric winch in the logging vehicle (9) is started to lift the three-component optical fiber quantum probe magnetic field sensor (5) to the wellhead at a uniform and slow speed. S6. During the process of slowly and uniformly lifting the three-component optical fiber quantum probe magnetic field sensor (5) to the wellhead, the three-component optical fiber quantum probe magnetic field sensor (5) continuously collects three-component magnetic field data of the entire well section, the three-component optical fiber attitude sensor (6) collects three-component attitude data of the three-component optical fiber quantum probe magnetic field sensor (5) at each data collection moment, and the multimode optical fiber in the armored optical cable (7) or armored optoelectronic composite cable (13) and the DTS modem instrument (10) in the logging vehicle (9) synchronously measure the temperature on the armored optical cable (7) or armored optoelectronic composite cable (13); S7, after completing the acquisition of the three-component magnetic field data of the entire well section in step S6, firstly, it is necessary to correct the temperature drift of the three-component optical fiber quantum probe magnetic field sensor (5) according to the temperature at the location where the three-component optical fiber quantum probe magnetic field sensor (5) is located measured by the DTS modulation and demodulation instrument (10); then, it is necessary to pre-process the three-component magnetic field raw data acquired in the entire well section by rotating and converting the three-component attitude data recorded at each three-component magnetic field data acquisition location; S8. After completing the rotation preprocessing of the three-component magnetic field data of the entire well section in step S7, it is also necessary to rotate the vertical magnetic field component H perpendicular to the ground plane according to the well trajectory data. Z and two horizontal magnetic field components H parallel to the east-west and north-south directions respectively X and H Y Project them onto the well trajectory perpendicular to the ground, and assign the original measured depth value of the three-component magnetic field data of each measurement position to the vertical depth value after projection; S9, finally, the three-component magnetic field data (H) obtained in step S8 distributed along the well trajectory perpendicular to the ground Z ,H X ,H Y ) Comprehensive interpretation based on the magnetic parameters of the formation rocks or minerals passed by the well trajectory; S10, in the absence of an active electrical or magnetic source in the air, on the ground, or in the same well or in a side well, by analyzing the three-component magnetic field data (H) obtained in step S8 distributed along the well trajectory perpendicular to the ground. Z ,H X ,H Y ) analysis and interpretation can identify the distribution characteristics and regularities of high magnetic anomaly geological bodies or high magnetic anomaly ore bodies along the well trajectory in the underground strata; S11, under the stimulation of an active electrical source or magnetic source deployed in the air or on the ground or in the same well or in a side well, the three-component magnetic field data (H) obtained in step S8 after the controllable source is excited and distributed along the well trajectory perpendicular to the ground is obtained. Z ,H X ,H Y ) analysis and interpretation, and identify the distribution characteristics and laws of high electromagnetic anomaly geological bodies along the well trajectory generated by rocks or minerals in the downhole strata under the excitation of active source electric field or active source magnetic field.

8. The magnetic field sensing method based on diamond nitrogen-quantum fiber probe according to claim 7, characterized in that: The method for preprocessing the rotation and conversion of the three-component magnetic field raw data of S7 includes the following sub-steps: S7.

1. Based on the inclination angle of the three-component optical fiber quantum probe magnetic field sensor (5) at each magnetic field data acquisition position recorded by the three-component optical fiber attitude sensor (6), the vertical component H of the three-component magnetic field raw data at that position is converted to Z Rotate to a direction perpendicular to the ground plane; S7.

2. Based on the azimuth angle of the three-component optical fiber quantum probe magnetic field sensor (5) at each magnetic field data acquisition position recorded by the three-component optical fiber attitude sensor (6), rotate the position to a horizontal component H of the three-component magnetic field raw data in a direction perpendicular to the ground plane. X Rotate to an east-west direction; S7.3, according to the azimuth angle of the three-component optical fiber quantum probe magnetic field sensor (5) at each magnetic field data acquisition position recorded by the three-component optical fiber attitude sensor (6), rotate the position to another horizontal component H of the three-component magnetic field raw data in the direction perpendicular to the ground plane Y Rotate to the north-south direction.

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