Underground three-component optical fiber magnetic field sensor based on micro-nano optical fiber and system thereof

Abstract

The invention relates to the technical field of optical fiber sensing, in particular to an underground three-component optical fiber magnetic field sensor based on a micro-nano optical fiber and a system thereof. The fiber magnetic field sensor is constructed by wrapping the symmetrical biconical micro-nano fiber with a giant magnetostrictive rod. When the size of an underground magnetic field is changed, the internal molecular structure of the giant magnetostrictive rod is changed, so that the external structure is subjected to extension or contraction deformation, and meanwhile, the symmetrical biconical micro-nano optical fiber wrapped by the giant magnetostrictive rod is caused to generate basically identical extension or contraction; the broadband light source and the spectrograph which are connected to the two ends of the symmetrical biconical micro-nano optical fiber can detect the strain which is generated on the symmetrical biconical micro-nano optical fiber and is basically the same as the deformation of the giant magnetostrictive rod. By measuring the strain generated by the symmetrical biconical micro-nano optical fiber, the variable quantity of the external magnetic field can be calculated. An underground, land, aviation and seabed three-component magnetic field data acquisition system can be conveniently constructed by using the optical fiber magnetic field sensor.

Description

Technical Field

[0001] This invention relates to the field of fiber optic sensing technology, specifically to a downhole three-component fiber optic magnetic field sensor and its system based on micro-nano optical fibers. Background Technology

[0002] Micro-nano optical fibers are one-dimensional optical waveguide devices with diameters close to or smaller than the wavelength of transmitted light. They possess characteristics such as low loss, low cost, and ease of mass production, and are widely used in fields such as detection, medicine, and communications. Their atomic-level surface smoothness, strong optical field confinement, and high-proportion evanescent wave transmission characteristics give them unique advantages among micro-nano photonic devices. Fabrication primarily employs a flame-heated stretching method; a two-step stretching method can reduce the diameter to 50 nm, while CO2 laser and metal electric heating processes improve fabrication efficiency.

[0003] In recent years, magnetic field sensing has played an increasingly important role in many fields such as scientific research and engineering applications. However, the structure and cost of traditional magnetic field sensors based on sensing principles such as the Hall effect, magnetoresistive effect, and fluxgate magnetization still need improvement. Fiber optic magnetic field sensors have attracted increasing attention due to their advantages such as light weight, small size, low cost, high temperature resistance, and remote controllability. Traditional optical fibers, such as those made of quartz, are not easily affected by electromagnetic signals. Therefore, fiber optic magnetic field sensors require specially designed fiber structures and magnetically sensitive materials so that the phase, intensity, frequency, and other physical properties of the light waves in the fiber can be modulated by the ambient magnetic field.

[0004] Magnetostrictive materials, under the influence of an applied magnetic field, will elongate or shorten in the magnetization direction; the dimensional change depends on the magnitude and direction of the magnetic flux density. Magnetostrictive materials can be attached to or wrapped around the surface of optical fiber structures to cause changes in the length of the fiber under the influence of a magnetic field, thereby altering parameters such as the refractive index of the fiber. Rare-earth magnetostrictive materials, such as the terbium-dysprosium-iron (TbDyFe) alloy series, also known as Terfenol D, have a magnetostriction coefficient of... It is 40 to 50 times stronger than nickel-based materials, hence it is also known as rare earth super magnetostrictive material, which has attracted much attention in the field of magnetic field measurement.

[0005] Changing the magnitude of the applied magnetic field causes alterations in the internal molecular structure of the magnetostrictive material, resulting in the elongation or contraction of the external structure. The relationship between the resulting strain and the applied magnetic field is expressed as ε. T =ΔL / L=C f H 2 In the formula: ε T ΔL is the strain of the TbDyFe magnetostrictive rod; ΔL is the elongation of the TbDyFe magnetostrictive rod; L is the length of the TbDyFe magnetostrictive rod itself; C fThe magnetostriction coefficient of TbDyFe increases with the increase of the applied magnetic field H; H is the magnitude of the applied magnetic field. Under the action of the applied magnetic field, the TbDyFe magnetostrictive rod itself deforms, causing the symmetrical biconical micro / nano fiber fixed to it to also produce essentially the same strain. When the micro / nano fiber interferometer is subjected to a uniform axial strain ε... T When this occurs, an elastic-optical effect is generated, which changes the effective refractive index of the fundamental and higher-order modes of the interfering fiber, and the interference length of the interferometer also changes. This causes a wavelength shift in the interference spectrum of the micro / nano fiber interferometer. The amount of wavelength shift is related to the strain generated by the symmetrical biconical micro / nano fiber. By measuring the strain generated by the symmetrical biconical micro / nano fiber, the change in the external magnetic field can be calculated.

[0006] Fiber optic magnetic field sensor technology is developing rapidly and has broad application prospects, such as in current sensing, multi-dimensional ocean detection, and national defense. Fiber optic magnetic field sensors can also be used as current sensors, geomagnetic sensors, and quasi-distributed magnetic field sensors. Summary of the Invention

[0007] The technical problem this invention aims to solve is that, although traditional fiber optic magnetic field sensors are not easily affected by electromagnetic signals, they are difficult to apply well in special environments such as underground, air, and seabed. Changes in the ambient magnetic field cannot modulate the physical characteristics of the light waves in the fiber optic cable, such as phase, intensity, and frequency. The purpose of this invention is to provide an underground three-component fiber optic magnetic field sensor, system, and application based on micro-nano fiber optics. It improves upon the traditional fiber optic structure by using a TbDyFe supermagnetostrictive rod wrapped around a symmetrical biconical micro-nano fiber to construct the fiber optic magnetic field sensor, so that changes in the ambient magnetic field can modulate the physical characteristics of the light waves in the fiber optic cable, such as phase, intensity, and frequency.

[0008] This invention is achieved through the following technical solution: a high-temperature resistant TbDyFe supermagnetostrictive rod.

[0009] This invention provides a downhole three-component fiber optic magnetic field sensor based on micro / nano fiber, comprising a symmetrical biconical micro / nano fiber, wherein the symmetrical biconical micro / nano fiber comprises: a micro / nano single-mode fiber core between the symmetrical bicones for transmitting and sensing optical signals; and a micro / nano single-mode fiber cladding for protecting the micro / nano single-mode fiber core.

[0010] The downhole three-component fiber optic magnetic field sensor based on micro / nano fibers also includes: a TbDyFe super magnetostrictive rod wrapped around a symmetrical biconical micro / nano fiber; each TbDyFe super magnetostrictive rod wrapped around the symmetrical biconical micro / nano fiber has high-temperature resistant and hydrogen-loss resistant single-mode fiber fused to both ends, and is encapsulated in a non-magnetic titanium alloy tube, thus constructing a fiber optic magnetic field sensor based on micro / nano fibers that is sensitive to changes in the magnetic field parallel to the extension direction of the titanium alloy tube.

[0011] Three identical fiber optic magnetic field sensors based on micro-nano optical fibers are installed and fixed in a pairwise orthogonal configuration inside a cylinder made of non-magnetic alloy or composite material, forming a high-temperature resistant downhole three-component fiber optic magnetic field sensor based on micro-nano optical fibers.

[0012] The multiple downhole three-component fiber optic magnetic field sensors based on micro-nano optical fibers can be connected together via inter-stage armored optical cables to form a downhole three-component fiber optic magnetic field sensor array. The high-temperature resistant and hydrogen-loss-resistant single-mode optical fibers fused at both ends of the micro-nano optical fiber magnetic field sensors are connected to a three-channel broadband light source and a three-channel spectrometer on the ground via armored optical cables.

[0013] When the magnitude of the downhole magnetic field changes, it causes changes in the internal molecular structure of the TbDyFe supermagnetostrictive rod, resulting in elongation or contraction of the external structure. At the same time, it causes the symmetrical biconical micro / nanofiber encased in the rod to undergo essentially the same elongation or contraction. Broadband light sources and spectrometers connected to both ends of the symmetrical biconical micro / nanofiber can detect strains on the symmetrical biconical micro / nanofiber that are essentially the same as the deformation of the TbDyFe supermagnetostrictive rod.

[0014] The downhole three-component fiber optic magnetic field sensor system based on micro-nano fiber optics includes: a fiber optic signal modem, a surface logging vehicle, an armored optical cable, a metal sleeve, a fiber optic gyroscope, a three-component fiber optic attitude sensor, a three-component fiber optic electric field sensor, and a downhole three-component fiber optic magnetic field sensor based on micro-nano fiber optics. The metal sleeve is made of non-magnetic titanium alloy or non-magnetic alloy steel.

[0015] The downhole three-component fiber optic magnetic field sensor based on micro-nano fiber is fixed inside a metal sleeve. The fiber optic gyroscope, the three-component fiber optic attitude sensor, and the three-component fiber optic electric field sensor are also installed and fixed inside the metal sleeve. Each magnetic field sensing component, fiber optic gyroscope, three-component fiber optic attitude sensor, and three-component fiber optic electric field sensor are connected to the ground logging vehicle through armored optical cables.

[0016] The fiber optic signal modem inside the surface logging vehicle is connected to the downhole fiber optic gyroscope, three-component fiber optic attitude sensor, and three-component fiber optic electric field sensor via armored optical cables. It is used to demodulate in real time the three-component electric field signal measured by the downhole three-component fiber optic electric field sensor, the three-component magnetic field signal measured by the downhole three-component fiber optic magnetic field sensor based on micro-nano fiber, and the real-time azimuth and three-component attitude signals of the sensor downhole.

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0018] This invention discloses a downhole three-component fiber optic magnetic field sensor and its system based on micro / nano-fibers, relating to the field of fiber optic sensing technology. The fiber optic magnetic field sensor is constructed by wrapping a TbDyFe magnetostrictive rod around a symmetrical biconical micro / nano-fiber. When the magnitude of the downhole magnetic field changes, it causes a change in the internal molecular structure of the TbDyFe magnetostrictive rod, resulting in elongation or contraction of the external structure. Simultaneously, the symmetrical biconical micro / nano-fiber it wraps undergoes essentially the same elongation or contraction. A broadband light source and spectrometer connected to both ends of the symmetrical biconical micro / nano-fiber can detect the strain generated on the symmetrical biconical micro / nano-fiber that is essentially the same as the deformation of the TbDyFe magnetostrictive rod. By measuring the strain generated in the symmetrical biconical micro / nano-fiber, the change in the applied magnetic field can be calculated. This solution improves upon the traditional fiber optic structure by using specially made micro-nano optical fibers and magnetostrictive materials to fabricate fiber optic magnetic field sensors. These sensors can then be used to easily construct three-component magnetic field data acquisition systems for wells, land, air, and seabed. These fiber optic magnetic field sensors offer advantages such as small size, light weight, low cost, high temperature and high pressure resistance, resistance to electromagnetic interference, no need for power supply, and no electronic components connected to the sensor. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0020] Figure 1 This is a schematic diagram of a symmetrical biconical micro / nano fiber structure.

[0021] Figure 2 Schematic diagram of a symmetrical biconical micro / nano fiber structure wrapped with a TbDyFe super magnetostrictive rod;

[0022] Figure 3 A schematic diagram of a micro / nano fiber optic single-component magnetic field sensor encapsulated in a titanium alloy capillary tube.

[0023] Figure 4 This is a schematic diagram of the deployment of a downhole single-stage three-component fiber optic magnetic field sensor system based on micro-nano optical fibers.

[0024] Figure 5 This is a schematic diagram of the deployment of a downhole array three-component fiber optic magnetic field sensor system based on micro-nano optical fibers.

[0025] The attached diagram shows the markings and corresponding component names:

[0026] 1-Symmetrical biconical micro / nano optical fiber, 2-Micro / nano single-mode optical fiber core, 3-Micro / nano single-mode optical fiber cladding, 4-TbDyFe super magnetostrictive rod, 5-High temperature resistant and hydrogen loss resistant single-mode optical fiber, 6-Titanium alloy capillary tube, 7-Cylinder, 8-Interstage armored optical cable, 9-Armored optical cable, 10-Broadband light source, 11-Spectrometer, 12-Fiber optic signal modem, 13-Ground logging vehicle, 14-Metal sleeve, 15-Fiber optic gyroscope, 16-Three-component fiber optic attitude sensor, 17-Three-component fiber optic electric field sensor. Detailed Implementation

[0027] To facilitate understanding of the objectives, technical solutions, and advantages of this invention, the invention will be described in more detail below with reference to the accompanying drawings and specific embodiments. The accompanying drawings illustrate preferred embodiments of the invention. However, the invention can be implemented in many different forms and is not limited to the embodiments described in this specification. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this invention. The illustrative embodiments and descriptions of this invention are for illustrative purposes only and do not constitute a limitation of the invention; they are merely examples, and the advantages of the invention will become clearer and easier to understand by illustrating them.

[0028] Example 1

[0029] This embodiment provides a downhole three-component fiber optic magnetic field sensor based on micro / nano optical fibers, including a symmetrical biconical micro / nano optical fiber 1, as shown below. Figure 1 As shown, the symmetrical biconical micro / nano fiber 1 includes:

[0030] The micro / nano single-mode fiber core 2 between the symmetrical biconical structures is used for transmitting and sensing optical signals; the micro / nano single-mode fiber cladding 3 is used to protect the micro / nano single-mode fiber core 2; and the single-mode fiber 5 is used to prepare the symmetrical biconical micro / nano fiber 1.

[0031] like Figure 2 As shown, the fiber optic magnetic field sensor based on micro / nano optical fiber further includes: a high-temperature resistant TbDyFe magnetostrictive rod 4, wrapped around a symmetrical biconical micro / nano optical fiber 1; and high-temperature resistant and hydrogen-loss resistant single-mode optical fiber 5 fused to both ends of each TbDyFe magnetostrictive rod 4 wrapping the symmetrical biconical micro / nano optical fiber 1.

[0032] like Figure 3 As shown, a fiber optic magnetic field sensor based on micro-nano fiber is encapsulated in a non-magnetic titanium alloy tube 6 to construct a fiber optic magnetic field sensor based on micro-nano fiber that is sensitive to changes in the magnetic field parallel to the extension direction of the titanium alloy tube 6.

[0033] like Figure 4As shown, three identical fiber optic magnetic field sensors based on micro-nano optical fibers are installed and fixed in a pairwise orthogonal configuration inside a cylinder 7 made of non-magnetic alloy or composite material, forming a high-temperature resistant downhole three-component fiber optic magnetic field sensor based on micro-nano optical fibers.

[0034] like Figure 5 As shown, the multiple downhole three-component fiber optic magnetic field sensors based on micro-nano optical fibers are connected together by inter-stage armored optical cables 8 to form a downhole three-component fiber optic magnetic field sensor array. The high-temperature resistant and hydrogen-loss-resistant single-mode optical fibers 5 fused at both ends of the micro-nano optical fiber magnetic field sensors are connected to a three-channel broadband light source 10 and a three-channel spectrometer 11 on the ground via armored optical cables 9, respectively.

[0035] For magnetostrictive materials, changing the magnitude of the applied magnetic field causes a change in the internal molecular structure, resulting in the elongation or contraction of the external structure. The relationship between the resulting strain and the applied magnetic field is expressed as ε. T =ΔL / L=C f H 2 In the formula: ε T ΔL is the strain of the TbDyFe magnetostrictive rod 4; ΔL is the elongation of the TbDyFe magnetostrictive rod; L is the length of the TbDyFe magnetostrictive rod itself; C f The magnetostriction coefficient of TbDyFe increases with the increase of the applied magnetic field H; H is the magnitude of the applied magnetic field. Under the action of the applied magnetic field, the TbDyFe magnetostrictive rod itself deforms, causing the symmetrical biconical micro / nano fiber 1 fixed to it to also produce essentially the same strain. When the micro / nano fiber interferometer is subjected to a uniform axial strain ε... T When this occurs, an elastic-optical effect is generated, which changes the effective refractive index of the fundamental and higher-order modes of the interfering fiber, and the interference length of the interferometer also changes, causing a wavelength drift in the interference spectrum of the micro-nano fiber interferometer. The amount of wavelength drift is related to the strain generated by the symmetrical biconical micro-nano fiber 1. By measuring the strain generated by the symmetrical biconical micro-nano fiber 1, the change in the external magnetic field can be calculated.

[0036] A fiber optic magnetic field sensor can be constructed by wrapping a TbDyFe magnetostrictive rod 4 around a symmetrical biconical micro / nanofiber 1. When the magnitude of the downhole magnetic field changes, it causes a change in the internal molecular structure of the TbDyFe magnetostrictive rod 4, resulting in elongation or contraction of the external structure. Simultaneously, the symmetrical biconical micro / nanofiber 1 it wraps undergoes a similar elongation or contraction. Broadband light sources and spectrometers connected to both ends of the symmetrical biconical micro / nanofiber 1 can detect strains on the symmetrical biconical micro / nanofiber that are essentially the same as the deformation of the TbDyFe magnetostrictive rod 4.

[0037] This embodiment provides a downhole three-component fiber optic magnetic field sensor system based on micro / nano optical fibers, such as... Figure 4 As shown, it includes: an optical fiber signal modem 12, a ground logging vehicle 13, an armored optical cable 9, a metal sleeve 14, an optical fiber gyroscope 15, a three-component optical fiber attitude sensor 16, a three-component optical fiber electric field sensor 17, and an optical fiber magnetic field sensor based on micro-nano optical fibers. The metal sleeve 14 is made of non-magnetic titanium alloy or non-magnetic alloy steel.

[0038] The downhole three-component fiber optic magnetic field sensor system based on micro-nano fiber optics is described. The downhole three-component fiber optic magnetic field sensor is fixed inside a metal sleeve 14. The fiber optic gyroscope 15, the three-component fiber optic attitude sensor 16, and the three-component fiber optic electric field sensor 17 are also installed and fixed inside the metal sleeve 14. Each magnetic field sensing component, fiber optic gyroscope 15, three-component fiber optic attitude sensor 16, and three-component fiber optic electric field sensor 17 are connected to the surface logging vehicle 13 via armored optical cables 9.

[0039] like Figure 5As shown, the fiber optic signal modem 12 inside the surface logging vehicle 13 is connected to the downhole fiber optic gyroscope 15, three-component fiber optic attitude sensor 16, and three-component fiber optic electric field sensor 17 via armored optical cable 9. When collecting downhole electromagnetic data, a single or array-type downhole three-component fiber optic magnetic field sensor based on micro / nano fiber optics is first lowered to the bottom of the well using armored optical cable 9. Then, the fiber optic signal modem 12, broadband light source 10, and spectrometer 11 inside the surface logging vehicle 13 are activated to begin data collection. The downhole three-component fiber optic magnetic field sensor based on micro / nano fiber optics is then slowly raised to the wellhead. Simultaneously, the three-component magnetic field signal measured by the downhole three-component fiber optic magnetic field sensor based on micro / nano fiber optics within the metal sleeve 14, the three-component electric field signal measured by the three-component fiber optic electric field sensor 17, the real-time azimuth of the sensor downhole measured by the fiber optic gyroscope 15, and the three-component attitude signal measured by the three-component fiber optic attitude sensor 16 are continuously collected.

[0040] The three-channel broadband light source 10 and the three-channel spectrometer 11 inside the ground logging vehicle 13 demodulate the output signal of the downhole three-component fiber optic magnetic field sensor based on micro-nano fiber into real-time three-component magnetic field data at any location along the well trajectory throughout the well section.

[0041] The fiber optic signal modem 12 inside the surface logging vehicle 13 demodulates the output signals of the full-section fiber optic gyroscope 15 and the three-component fiber optic attitude sensor 16 of the downhole metal sleeve 14 into real-time azimuth data and three-component attitude data of the downhole metal sleeve 14 at any position along the well trajectory.

[0042] Using the real-time azimuth data and three-component attitude data of the downhole metal sleeve 14 at any location along the well trajectory, the real-time three-component magnetic field data at any location on the well trajectory is rotated to a vertical magnetic field component perpendicular to the ground, a first horizontal magnetic field component parallel to the north-south direction, and a second horizontal magnetic field component parallel to the east-west direction.

[0043] This invention utilizes a downhole three-component fiber optic magnetic field sensor based on micro / nano-fiber wrapped with a TbDyFe magnetostrictive rod. It offers advantages such as small size, light weight, low cost, high temperature and high pressure resistance, resistance to electromagnetic interference, no need for power supply, and no electronic components connected to the fiber optic magnetic field sensor. This facilitates the construction of downhole, land, airborne, and seabed three-component magnetic field data acquisition systems using the fiber optic magnetic field sensor. This system directly measures the three-component magnetic field signals from downhole, land, air, and seabed locations using a three-channel broadband light source 10 and a three-channel spectrometer 11 located away from the fiber optic magnetic field sensor, and the downhole three-component fiber optic magnetic field sensor connected to the tail end of an armored optical cable.

[0044] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment 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 within the scope of protection of the present invention.

Claims

1. A downhole three-component fiber optic magnetic field sensor based on micro / nano optical fibers, characterized in that, The symmetrical biconical micro / nano fiber (1) includes: The micro / nano single-mode fiber core (2) between symmetrical bicones is used for transmitting and sensing optical signals; Micro-nano single-mode fiber cladding (3) is used to protect the micro-nano single-mode fiber core (2). It also includes: a high-temperature resistant TbDyFe magnetostrictive rod (4) wrapped around a symmetrical biconical micro / nano fiber (1); each TbDyFe magnetostrictive rod (4) wrapped around the symmetrical biconical micro / nano fiber (1) has a high-temperature resistant and hydrogen-loss resistant single-mode fiber (5) fused to both ends, and encapsulated in a non-magnetic titanium alloy tube (6) to form a fiber optic magnetic field sensor based on micro / nano fiber that is sensitive to changes in the magnetic field parallel to the extension direction of the titanium alloy tube (6); The high-temperature resistant and hydrogen-damage resistant single-mode optical fiber (5) is connected to a three-channel broadband light source (10) and a three-channel spectrometer (11) on the ground via armored optical cable (9). When the magnitude of the downhole magnetic field changes, it causes the internal molecular structure of the TbDyFe super magnetostrictive rod (4) to change, thereby causing the external structure to elongate or contract. At the same time, it causes the symmetrical biconical micro-nano fiber (1) wrapped by it to elongate or contract in the same way. The broadband light source (10) and spectrometer (11) connected to both ends of the symmetrical biconical micro-nano fiber (1) can detect the strain generated on the symmetrical biconical micro-nano fiber that is basically the same as the deformation of the TbDyFe super magnetostrictive rod (4). Three identical fiber optic magnetic field sensors based on micro-nano optical fibers are installed and fixed in a cylinder (7) made of non-magnetic alloy or composite material in a pairwise orthogonal configuration to form a high-temperature resistant downhole three-component fiber optic magnetic field sensor based on micro-nano optical fibers.

2. The downhole three-component fiber optic magnetic field sensor based on micro / nano fiber optics according to claim 1, characterized in that, Multiple downhole three-component fiber optic magnetic field sensors based on micro-nano optical fibers are connected by inter-stage armored optical cables (8) to form a downhole three-component fiber optic magnetic field sensor array.

3. A downhole three-component fiber optic magnetic field sensing system based on micro / nano optical fibers, characterized in that, include: The fiber optic signal modem (12), the ground logging vehicle (13), the armored optical cable (9), the metal sleeve (14), the fiber optic gyroscope (15), the three-component fiber optic attitude sensor (16), the three-component fiber optic electric field sensor (17), and the downhole three-component fiber optic magnetic field sensor based on micro-nano fiber optics as described in claim 1 or 2, wherein the metal sleeve (14) is made of non-magnetic titanium alloy or non-magnetic alloy steel. The downhole three-component fiber optic magnetic field sensor based on micro-nano fiber is fixed inside a metal sleeve (14). The fiber optic gyroscope (15), the three-component fiber optic attitude sensor (16), and the three-component fiber optic electric field sensor (17) are also installed and fixed inside the metal sleeve (14). Each magnetic field sensing component, fiber optic gyroscope (15), three-component fiber optic attitude sensor (16), and three-component fiber optic electric field sensor (17) are connected to the ground logging vehicle (13) through armored optical cable (9). The fiber optic signal modem (12) inside the ground logging vehicle (13) is connected to the downhole fiber optic gyroscope (15), three-component fiber optic attitude sensor (16) and three-component fiber optic electric field sensor (17) via armored optical cable (9) in real time. It is used to demodulate the three-component electric field signal measured by the downhole three-component fiber optic electric field sensor (17), the three-component magnetic field signal measured by the downhole three-component fiber optic magnetic field sensor based on micro-nano fiber, and the real-time orientation and three-component attitude signals of the sensor.

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