An electromagnetic induction directional detection device and a directional detection method

Abstract

The application provides an electromagnetic induction directional detection device and a directional detection method, wherein the directional detection device comprises a transmitting device, a receiving device, a solenoid and a receiving wire assembly; the solenoid is connected with the transmitting device; the receiving wire assembly is located at the upper part or the lower part of the solenoid; the receiving wire assembly comprises first receiving wires and second receiving wires which are orthogonally distributed; the first receiving wires and the second receiving wires are connected with the receiving device; and the solenoid is zero in the primary field magnetic flux of the loop cavity formed by the first receiving wires and the second receiving wires. The application can enhance the primary field intensity provided by the transmitting device and realize the positioning detection of the low-resistance body in the to-be-detected region.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic induction technology, and in particular to an electromagnetic induction directional detection device and directional detection method. Background Technology

[0002] Currently, in the fields of resource and engineering geophysical exploration, there are numerous and widely used geophysical exploration methods and devices based on the principle of electromagnetic induction, especially transient electromagnetic methods. Transient electromagnetic methods can help solve the challenges of shallow exploration, but when the probe is located in a confined space within the well, the signal received by the transient electromagnetic instrument is not only affected by external interference, but also suffers from low resolution due to the superposition of mutual inductance between the transceiver and receiver. Furthermore, due to the isotropic nature of the transceiver coils with respect to surrounding anomalies, achieving precise interpretation and directional detection in electromagnetic exploration remains a globally recognized challenge. Therefore, as a method of transient electromagnetic exploration in wells, eliminating the near-field mutual inductance effect of transceiver sensors and achieving directional detection of concealed targets require new technological attempts and breakthroughs.

[0003] The invention disclosed in CN116224448A is an electromagnetic induction detection method and system. It provides a primary field through a grounded straight wire and uses a dual-channel orthogonal coil as a receiving device. However, the number of turns of the grounded straight wire cannot be increased, which makes the primary field provided very limited. At the same time, its grounding current will also affect the accuracy of the detection. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of the prior art by providing an electromagnetic induction-based directional detection device and method, which can enhance the primary field strength provided by the transmitting device and achieve the positioning and detection of low-resistivity bodies within the test area.

[0005] To achieve the above objectives, the present invention provides an electromagnetic induction directional detection device, comprising a transmitting device, a receiving device, a solenoid, and a receiving wire assembly;

[0006] The solenoid is connected to the transmitting device, and the receiving wire assembly is located at the upper or lower part of the solenoid. The receiving wire assembly includes a first receiving wire and a second receiving wire that are orthogonally distributed. Both the first receiving wire and the second receiving wire are connected to the receiving device. The primary magnetic flux of the solenoid in the loop cavity formed by the first receiving wire and the second receiving wire is zero.

[0007] In operation, the solenoid is first connected to the transmitting device; then, the first and second receiving wires are both connected to the receiving device; next, the electromagnetic induction directional detection device is placed in the borehole of the area to be detected, and the power supply to the transmitting device is turned on; after a period of time, the power is turned off. According to Faraday's law of electromagnetic induction, the low-resistivity body in the area to be tested will form eddy currents inside, generating a secondary magnetic field that decays over time, which is received by the first and second receiving wires. The receiving device obtains the test data of the first and second receiving wires; the direction of the low-resistivity body is determined based on the test data obtained by the receiving device, thus realizing the positioning and detection of the low-resistivity body in the area to be tested.

[0008] Solenoids are used to transmit the primary field, which avoids grounding and creating a loop that could affect the accuracy of directional detection. They also increase the number of turns in the transmitting coil, thus increasing the strength of the primary field.

[0009] The first and second receiving wires are orthogonally distributed to receive the secondary field. The planes containing the first and second receiving wires are perpendicular to each other, and their axes of symmetry coincide. The first and second receiving wires not only do not generate mutual inductance, but the primary field magnetic flux of the solenoid in the loop cavity formed by the first and second receiving wires is zero. This cleverly eliminates the interference of the primary field on the target, improves the resolution of the detection results, and enables directional detection.

[0010] The receiving wire assembly is located at the upper or lower part of the solenoid. There is a height difference between the receiving wire assembly and the solenoid, which ensures that the secondary magnetic flux passing through the first and second receiving wires can never be zero. At the same time, it ensures that when a low-resistivity body is detected, the first and second receiving wires can always receive the signal of the low-resistivity body, thus ensuring a response.

[0011] Optionally, the solenoid may be a rewound coil.

[0012] The solenoid uses a rewinding method, which increases the number of turns of the transmitting coil, increases the primary field, and increases the inductance of the solenoid. This increases the effective primary field and the excitation secondary field, and avoids the unnecessary interference primary field generated by directly rewinding after the first winding. At the same time, the magnetic field generated by the rewinding coil is consistent with the magnetic field generated by the first winding coil, which enhances the transmitted signal.

[0013] Optionally, the solenoid has a hollow structure, and a magnetic rod is provided at the center of the solenoid.

[0014] The solenoid has a hollow structure, and its center can be filled with a magnetic rod, which further increases the primary field.

[0015] Optionally, the central axes of both the first receiving wire and the second receiving wire coincide with the central axis of the solenoid.

[0016] The central axes of the first and second receiving wires coincide with the rotation center of the solenoid, ensuring that the first and second receiving wires are rotationally symmetrical. By utilizing the symmetry of the magnetic field, the first and second receiving wires are ensured to be located on the symmetry plane of the primary field, so that the primary field does not pass through the first and second receiving wires in any direction. The primary field magnetic flux of the solenoid in the loop cavity formed by the first and second receiving wires is zero, which cleverly eliminates the interference of the primary field and improves the detection resolution.

[0017] Optionally, the height of the solenoid is greater than the height of the first receiving wire or the second receiving wire.

[0018] The heights of the first and second receiving wires are always less than the length of the solenoid, and the first and second receiving wires are located above or below the solenoid, ensuring that the magnetic flux of the secondary field in the first and second receiving wires is never zero. If the solenoid and the receiving coil are at the same height, when the low-resistivity element is located in the middle of the device, the magnetic flux will cancel each other out symmetrically, weakening the received signal.

[0019] Optionally, the height of the solenoid is greater than the height of the first receiving wire or the second receiving wire, wherein the height of the solenoid is greater than or equal to twice the height of the first receiving wire or the second receiving wire.

[0020] Optionally, the receiving device is one of a coil sensor, a magnetic rod sensor, a magnetoresistive sensor, and a Hall sensor.

[0021] The present invention also provides a method for directional detection by electromagnetic induction, comprising the following steps:

[0022] S1. A solenoid and a receiving wire assembly are set in the area to be detected. The solenoid is connected to the transmitting device. The receiving wire assembly is set in the upper or lower part of the solenoid. The receiving wire assembly includes a first receiving wire and a second receiving wire that are orthogonally distributed. Both the first receiving wire and the second receiving wire are connected to the receiving device. The primary magnetic flux of the loop cavity formed by the solenoid and the first receiving wire and the second receiving wire is zero.

[0023] S2. Turn on the transmitter, and the transmitter supplies current to the solenoid.

[0024] S3. Turn off the transmitting device. If the receiving device receives the signal generated by the low-resistivity body in the area to be detected through the receiving wire assembly and obtains the test data, it proves that there is a low-resistivity body in the area to be detected. Otherwise, there is no low-resistivity body in the area to be detected.

[0025] S4. Determine the direction of the low-resistivity body based on the test data obtained from the receiving device.

[0026] Optionally, in step S3, the receiving device receives the signal generated by the low-resistivity body in the area to be detected and obtains the test data as follows: the transmitting device is turned off, and the receiving device obtains the induced electromotive force E of the first receiving wire through the first receiving wire and the second receiving wire, respectively. x The attenuation curve, and the induced electromotive force E of the second receiving wire. y The decay curve.

[0027] Optionally, step S4 specifically involves: inducing an electromotive force E based on the first receiving wire. x The attenuation curve, and the induced electromotive force E of the second receiving wire. y The attenuation curve is used to obtain the direction of the low-resistivity body relative to the central axis of the solenoid.

[0028] Optionally, the direction of the low-resistivity element relative to the central axis of the solenoid is obtained based on the angle θ between the low-resistivity element and the central axis of the solenoid. The formula for calculating the angle θ between the low-resistivity element and the central axis of the solenoid is:

[0029]

[0030] Beneficial effects:

[0031] 1. This invention comprises a transmitting device, a receiving device, a solenoid, and a receiving wire assembly. During use, the solenoid is first connected to the transmitting device; then, both the first and second receiving wires are connected to the receiving device; next, the electromagnetic induction directional detection device is placed in a borehole in the area to be detected, and the transmitting device is powered on; after a period of time, the power is turned off. According to Faraday's law of electromagnetic induction, the low-resistivity body in the area to be measured will form eddy currents internally, generating a secondary magnetic field that decays over time. This magnetic field is received by the first and second receiving wires, and test data from the first and second receiving wires is obtained in the receiving device. The direction of the low-resistivity body is determined based on the test data obtained by the receiving device, thus achieving the location detection of the low-resistivity body in the area to be measured.

[0032] 2. The invention incorporates a solenoid for transmitting the primary field, which avoids grounding and creating a loop that could affect the accuracy of directional detection. Furthermore, it increases the number of turns in the transmitting coil, thereby increasing the primary field.

[0033] 3. In this invention, the receiving wire assembly is located at the upper or lower part of the solenoid. There is a height difference between the receiving wire assembly and the solenoid, which ensures that the secondary magnetic flux passing through the first and second receiving wires can never be zero. At the same time, it ensures that when a low-resistivity body is detected, the first and second receiving wires can always receive the signal of the low-resistivity body, thus ensuring a response.

[0034] 4. In this invention, the first and second receiving wires are orthogonally distributed to receive the secondary field. The planes containing the first and second receiving wires are perpendicular to each other, and their axes of symmetry coincide. The first and second receiving wires will not generate mutual inductance. The primary field magnetic flux of the solenoid in the loop cavity formed by the first and second receiving wires is zero, which cleverly eliminates the interference of the primary field on the detection target, improves the resolution of the detection results, and can achieve the purpose of directional detection.

[0035] 5. In this invention, the solenoid is wound in a back-winding manner, which increases the number of turns of the transmitting coil, increases the primary field, and increases the inductance of the solenoid, thereby increasing the effective primary field and the excitation secondary field. It can also avoid the unnecessary interference primary field generated by directly rewinding after the first winding. At the same time, the magnetic field generated by the back-winding coil is consistent with the magnetic field generated by the first winding coil, which enhances the transmitted signal. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0037] Figure 1 This is a structural diagram of the electromagnetic induction directional detection device disclosed in this invention;

[0038] Figure 2 This is a top view of the primary field emitted by the solenoid in the electromagnetic induction directional detection device disclosed in this invention;

[0039] Figure 3 This is a front view of the primary field emitted by the solenoid in the electromagnetic induction directional detection device disclosed in this invention;

[0040] Figure 4 A top view of a low-resistivity body obtained by the electromagnetic induction directional detection device disclosed in this invention;

[0041] Figure 5 The front view of a low-resistivity body is obtained by the electromagnetic induction directional detection device disclosed in this invention.

[0042] Figure 6 This is a graph showing the attenuation curve of the induced electromotive force of the receiving wire assembly in the electromagnetic induction directional detection method disclosed in this invention.

[0043] Figure 7 This is a comparison diagram of the measured direction of a low-resistivity body and a preset direction in the electromagnetic induction directional detection method disclosed in this invention.

[0044] Figure 8 This is a comparison diagram of the measured direction of a low-resistivity body in multiple preset directions and the preset direction in the electromagnetic induction directional detection method disclosed in this invention.

[0045] Reference numerals: 1. Transmitting device; 2. Solenoid; 3. Low-resistivity body; 41. First receiving wire; 42. Second receiving wire; 5. Receiving device.

[0046] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0047] 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 a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0049] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0050] Example 1:

[0051] See Figure 1-5 According to an embodiment of the present invention, an electromagnetic induction directional detection device includes a transmitting device 1, a receiving device 5, a solenoid 2, and a receiving wire assembly.

[0052] The solenoid 2 is connected to the transmitting device 1. The receiving wire assembly is located at the upper or lower part of the solenoid 2. The receiving wire assembly includes a first receiving wire 41 and a second receiving wire 42 that are orthogonally distributed. Both the first receiving wire 41 and the second receiving wire 42 are connected to the receiving device 5. The primary magnetic flux of the loop cavity formed by the first receiving wire 41 and the second receiving wire 42 of the solenoid 2 is zero.

[0053] Specifically, during use, the solenoid 2 is first connected to the transmitting device 1; then, the first receiving wire 41 and the second receiving wire 42 are both connected to the receiving device 5; then, the electromagnetic induction directional detection device is placed in the borehole of the area to be detected, and the power supply of the transmitting device 1 is turned on; after a period of time, the power supply is turned off. According to Faraday's law of electromagnetic induction, the low-resistivity body 3 in the area to be tested will form eddy currents inside, generating a secondary magnetic field that decays over time, which is received by the first receiving wire 41 and the second receiving wire 42. The receiving device 5 obtains the test data of the first receiving wire 41 and the second receiving wire 42; the direction of the low-resistivity body 3 is determined based on the test data obtained by the receiving device 5, thereby realizing the positioning and detection of the low-resistivity body 3 in the area to be tested.

[0054] Solenoid 2 is used to transmit the primary field, which can avoid grounding and forming a loop that affects the accuracy of directional detection. It also increases the number of turns of the transmitting coil and increases the primary field.

[0055] The first receiving wire 41 and the second receiving wire 42 are orthogonally distributed to receive the secondary field. The planes containing the first receiving wire 41 and the second receiving wire 42 are perpendicular to each other, and their axes of symmetry coincide. The first receiving wire 41 and the second receiving wire 42 will not generate mutual inductance, and the primary field magnetic flux of the solenoid 2 in the loop cavity formed by the first receiving wire 41 and the second receiving wire 42 is zero. This cleverly eliminates the interference of the primary field on the detection target, improves the resolution of the detection results, and enables directional detection.

[0056] The receiving wire assembly is located at the upper or lower part of the solenoid 2. There is a height difference between the receiving wire assembly and the solenoid 2, so that the secondary field magnetic flux passing through the first receiving wire 41 and the second receiving wire 42 can never be zero. At the same time, it ensures that when the low-resistivity body 3 is detected, the first receiving wire 41 and the second receiving wire 42 can always receive the signal of the low-resistivity body 3, ensuring a response.

[0057] Because a single measurement may involve randomness and error, multiple measurements can be taken at the same point in the area to be detected, as well as at different points in the area. If the azimuth vectors measured at multiple different points point to the same point, then the low-resistivity body 3 can be considered to be located near that point. The solenoid 2 consists of two sections of equal length, and the coils of the two solenoid sections 2 are connected in series with positive polarity.

[0058] Compared to the invention with publication number CN116224448A, which uses a straight transmitting conductor, this invention uses a solenoid 2, significantly increasing the intensity of the primary field. To simplify calculations, the low-resistivity body in the test area is equivalent to a circular ring with a diameter of 10cm. When the transmitting device is a straight conductor, the current is 1A, and the distance from the low-resistivity body to be measured is 20cm, the Biot-Savart law is applied:

[0059]

[0060] Where B1 is the magnetic induction intensity of the primary field; μ0 is the permeability of vacuum; I is the magnitude of the current in the conductor; L represents the conductor; dl represents a directed element of the conductor; and R represents the distance from a point in space to dl.

[0061] Combining the magnetic flux calculation formula:

[0062]

[0063] in, Let S represent the magnetic flux in the toroidal ring; S represent the directed area of ​​the toroidal ring; and ds represent a unit cell of S. The equivalent magnetic flux of the toroidal ring can be calculated to be approximately 7.97 × 10⁻⁶. -9 Wb.

[0064] When the transmitting device is a solenoid with a diameter of 10cm, and is energized with 1A and 50 turns, and is 20cm away from the low-resistivity body being measured, the magnetic flux of the equivalent circular ring can be calculated to be approximately 7.5632×10-8Wb using the same formula. Compared to a straight wire, the magnetic flux of the solenoid is increased by about 10 times. If the number of turns is further increased, the magnetic flux will be further increased.

[0065] See Figure 1 In some embodiments of the present invention, the solenoid 2 is a rewinding coil.

[0066] The solenoid 2 is wound in a rewinding manner, which increases the number of turns of the transmitting coil, increases the primary field, and increases the inductance of the solenoid 2, thereby increasing the effective primary field and the excitation secondary field. It can also avoid the unnecessary interference primary field generated by directly rewinding after the first winding. At the same time, the magnetic field generated by the rewinding coil is consistent with the magnetic field generated by the first winding coil, which enhances the transmitted signal.

[0067] Assuming that the solenoid 2 is directly connected to the transmitting device after being wound once, the returned wire is inconsistent with the magnetic field originally generated by the solenoid 2, and the returned wire passes through the first receiving wire 41 and the second receiving wire 42, which will generate additional primary field interference.

[0068] See Figure 1 In some embodiments of the present invention, the solenoid 2 has a hollow structure and a magnetic rod is provided at the center of the solenoid 2.

[0069] The solenoid 2 has a hollow structure, and its center can be filled with a magnetic rod, which further increases the primary field.

[0070] See Figure 3 and 4In some embodiments of the present invention, the central axes of the first receiving wire 41 and the second receiving wire 42 are both coincident with the central axis of the solenoid 2.

[0071] The central axes of the first receiving wire 41 and the second receiving wire 42 coincide with the rotation center of the solenoid 2, ensuring that the first receiving wire 41 and the second receiving wire 42 are rotationally symmetric structures. By utilizing the symmetry of the magnetic field, the first receiving wire 41 and the second receiving wire 42 are ensured to be located on the symmetry plane of the primary field, so that the primary field does not pass through the first receiving wire 41 and the second receiving wire 42 in any direction. The primary field magnetic flux of the solenoid 2 in the loop cavity formed by the first receiving wire 41 and the second receiving wire 42 is zero, which cleverly eliminates the interference of the primary field and improves the detection resolution.

[0072] See Figure 1 In some embodiments of the present invention, the height of the solenoid 2 is greater than the height of the first receiving wire 41 or the second receiving wire 42.

[0073] The heights of the first receiving wire 41 and the second receiving wire 42 are always less than the length of the solenoid 2, and the first receiving wire 41 and the second receiving wire 42 are located above or below the solenoid 2, ensuring that the magnetic flux of the secondary field in the first receiving wire 41 and the second receiving wire 42 is never zero. If the solenoid 2 is at the same height as the receiving coil, when the low-resistance body 3 is located in the middle of the device, the magnetic flux will cancel each other out symmetrically, weakening the received signal.

[0074] See Figure 1 In some embodiments of the present invention, the height of the solenoid 2 is greater than or equal to twice the height of the first receiving wire 41 or the second receiving wire 42.

[0075] The height of the solenoid 2 is twice the height of the receiving coil, i.e. there is a certain height difference, and the first receiving wire 41 and the second receiving wire 42 are located above or below the solenoid 2, so that the magnetic flux of the secondary field in the first receiving wire 41 and the second receiving wire 42 is never zero.

[0076] See Figure 1 In some embodiments of the present invention, the receiving device 5 is one of a coil sensor, a magnetic rod sensor, a magnetoresistive sensor, and a Hall sensor.

[0077] Example 2:

[0078] See Figure 4-8 According to an embodiment of the present invention, a method for directional detection by electromagnetic induction includes the following steps:

[0079] S1. A solenoid 2 and a receiving wire assembly are set in the area to be detected. The solenoid 2 is connected to the transmitting device 1. The receiving wire assembly is set in the upper or lower part of the solenoid 2. The receiving wire assembly includes a first receiving wire 41 and a second receiving wire 42 that are orthogonally distributed. Both the first receiving wire 41 and the second receiving wire 42 are connected to the receiving device 5. The primary field magnetic flux of the loop cavity formed by the first receiving wire 41 and the second receiving wire 42 of the solenoid 2 is zero.

[0080] S2. Turn on the transmitter 1, and the transmitter 1 supplies current to the solenoid 2;

[0081] S3. Turn off the transmitting device 1. If the receiving device 5 receives the signal generated by the low-resistivity body 3 in the area to be detected through the receiving wire assembly and obtains the test data, it proves that the low-resistivity body 3 exists in the area to be detected. Otherwise, the low-resistivity body 3 does not exist in the area to be detected.

[0082] S4. Determine the direction of the low-resistivity body 3 based on the test data obtained from the receiving device 5.

[0083] See Figure 5 and 6 In some embodiments of the present invention, the receiving device 5 receiving the signal generated by the low-resistivity body 3 in the area to be detected and obtaining test data in step S3 specifically involves: turning off the transmitting device 1, and the receiving device 5 obtaining the induced electromotive force E of the first receiving wire 41 through the first receiving wire 41 and the second receiving wire 42, respectively. x The attenuation curve, and the induced electromotive force E of the second receiving wire 42. y The decay curve.

[0084] See Figure 6 In some embodiments of the present invention, step S4 specifically involves: generating an electromotive force E based on the first receiving wire 41. x The attenuation curve, and the induced electromotive force E of the second receiving wire 42. y From the attenuation curve, the direction of the low-resistivity element 3 relative to the central axis of solenoid 2 is obtained. The direction of the low-resistivity element 3 relative to the central axis of solenoid 2 is obtained from the angle θ of the low-resistivity element 3 relative to the central axis of solenoid 2. The formula for calculating the angle θ of the low-resistivity element 3 relative to the central axis of solenoid 2 is:

[0085]

[0086] In this embodiment, the transmitting device 1 is turned off after being turned on for a period of time, and the current of the solenoid 2 is turned off. Due to the presence of eddy currents in the low-resistivity body 3, a decaying secondary field will be generated, which will be received by the first receiving wire 41 and the second receiving wire 42. The intensity of these two sets of decaying signals is proportional to the magnetic flux.

[0087] See Figure 4 , 5 and 6, Figure 4 and 5 The top and front views of the low-resistivity body 3 are shown for the electromagnetic induction directional detection device. To verify the accuracy of the electromagnetic induction directional detection device, the low-resistivity body is presumably located at (-4, -3) on the central axis of solenoid 2. According to the transient electromagnetic method theory, the following will be obtained: Figure 6 The two sets of attenuation curves shown are as follows: Figure 6 China E x E represents the induced electromotive force (EMF) of the first receiving wire 41 in the x-direction. y This represents the induced electromotive force of the second receiving wire 42 in the y direction.

[0088] See Figure 7 The formula for calculating the angle θ between the low-resistivity body 3 and the central axis of the solenoid 2 is as follows:

[0089]

[0090] The measured direction of the low-resistivity body 3 relative to the central axis of the solenoid 2 can be obtained, and it can be seen that the measured direction of the low-resistivity body 3 is basically consistent with the preset direction.

[0091] See Figure 8 As shown, the above method is repeated and the electromagnetic induction orientation detection device is moved. When the low-resistivity body 3 is in various preset directions relative to the central axis of the solenoid 2, the direction of the low-resistivity body 3 is measured by the electromagnetic induction orientation detection device. The curve shows the comparison between the direction measured by the low-resistivity body 3 relative to the central axis of the solenoid 2 and the preset direction. It can be seen that the direction measured by this method is basically consistent with the preset direction, which ensures the accuracy of the electromagnetic induction orientation detection device.

[0092] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. An electromagnetic induction directional detection device, characterized in that, The device comprises a transmitting device, a receiving device, a solenoid and a receiving wire assembly; The solenoid is connected with the transmitting device and comprises a hollow structure formed by a return coil made by a return winding method, and a magnetic rod is arranged in the center of the solenoid, the return winding method can avoid the direct return of the excess interference primary field after the first winding, and the magnetic field generated by the return coil is consistent with the magnetic field generated by the coil wound for the first time; The receiving wire assembly is arranged at the upper part or the lower part of the solenoid, and the height of the solenoid is greater than or equal to twice the height of the receiving wire assembly; The receiving wire assembly comprises first receiving wires and second receiving wires arranged in an orthogonal distribution, the first receiving wires and the second receiving wires are connected with the receiving device, and the central axes of the first receiving wires and the second receiving wires are coincident with the central axis of the solenoid; The primary field magnetic flux of the solenoid in the loop cavity formed by the first receiving wires and the second receiving wires is zero.

2. The electromagnetic induction directional probe of claim 1, wherein, The receiving device is one of a coil sensor, a magnetic rod sensor, a magnetoresistance sensor and a Hall sensor.

3. A method of electromagnetic induction direction finding, characterized by, The method is based on the directional detection device of electromagnetic induction in claim 1 or 2, and comprises the following steps: S1, arranging a solenoid and a receiving wire assembly in a region to be detected, the solenoid is connected with the transmitting device and comprises a hollow structure formed by a return coil made by a return winding method, and a magnetic rod is arranged in the center of the solenoid, the receiving wire assembly is arranged at the upper part or the lower part of the solenoid, and the height of the solenoid is greater than or equal to twice the height of the receiving wire assembly, the receiving wire assembly comprises first receiving wires and second receiving wires arranged in an orthogonal distribution, the central axes of the first receiving wires and the second receiving wires are coincident with the central axis of the solenoid, the first receiving wires and the second receiving wires are connected with the receiving device, and the primary field magnetic flux of the solenoid in the loop cavity formed by the first receiving wires and the second receiving wires is zero; S2, turning on the transmitting device, and passing current to the solenoid by the transmitting device; S3, the transmitting device is turned off, and if the receiving device passes through the receiving wire assembly, the receiving device obtains a first receiving wire induced electromotive force E x decay curve and a second receiving wire induced electromotive force E y decay curve, respectively; S4, calculating the angle θ of the low-resistance body relative to the central axis of the solenoid according to the attenuation curves of Ex and Ey, and the calculation formula is θ = arctan(Ex / Ey), so as to determine the direction of the low-resistance body.

4. The method of electromagnetic induction directed detection of claim 3, wherein, In step S3, if the signal generated by the low-resistance body in the region to be detected is received, it is proved that the low-resistance body exists in the region to be detected, otherwise, the low-resistance body does not exist in the region to be detected.

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