A borehole ground-penetrating radar device and directional detection method

Abstract

This invention relates to a borehole ground-penetrating radar device and a directional detection method. The borehole ground-penetrating radar device includes a shielding layer and an internal structure. The internal structure includes a main control module, a gyroscope, a high-frequency antenna, and a low-frequency antenna. The shielding layer includes a directional receiving antenna. The main control module controls the high-frequency and low-frequency antennas to transmit multi-frequency, multi-resolution, and multi-scale electromagnetic wave signals. The shielding layer controls the radiation direction of the electromagnetic wave signals transmitted by the high-frequency and low-frequency antennas and receives reflected electromagnetic wave signals through the directional receiving antenna. Different electromagnetic wave signals are transmitted and received at different angles according to different needs, thus meeting the detection requirements. The high-frequency antenna, low-frequency antenna, and directional receiving antenna are mounted on the borehole ground-penetrating radar device, which transmits and receives electromagnetic wave signals directionally according to requirements. The gyroscope records the propagation distance and angle information of the electromagnetic wave signals, eliminating the need for an additional rotation device.

Description

Technical Field

[0001] This invention relates to the field of geophysical exploration technology, and in particular to a borehole ground-penetrating radar device and a directional detection method. Background Technology

[0002] Borehole ground-penetrating radar (BPR) is an important geophysical exploration technology that plays a vital role in deep geological exploration, engineering geological surveys, and mineral resource exploration. However, its current technology still has many shortcomings, which limit its wider application and further development.

[0003] Existing borehole radar antennas typically use fixed-frequency antennas for detection, making it impossible to simultaneously meet the requirements of high resolution in shallow areas and wide-area detection in deep areas. Furthermore, traditional borehole ground-penetrating radar systems generally employ a separate structural design, where the main unit and antenna are connected by a cable, and the antenna relies primarily on gravity for vertical movement. While this design performs well in vertical borehole detection, it faces numerous challenges in long-distance horizontal borehole detection. In horizontal boreholes, the antenna cannot move effectively due to gravity, requiring additional rotation mechanisms.

[0004] Therefore, there is an urgent need to propose a borehole ground-penetrating radar device and directional detection method to solve the technical problems existing in the technology, which typically use fixed-frequency antennas for detection and employ a split structure, making it impossible to simultaneously meet the requirements of high resolution in shallow areas and large-scale detection in deep areas during long-distance horizontal borehole detection. Summary of the Invention

[0005] In view of this, it is necessary to provide a borehole ground-penetrating radar device and directional detection method to solve the technical problems existing in the prior art, which typically use fixed-frequency antennas for detection and adopt a split structure, resulting in severe signal attenuation of cable transmission during long-distance horizontal borehole detection, affecting detection accuracy and reliability.

[0006] To address the aforementioned problems, in a first aspect, the present invention also provides a borehole ground-penetrating radar device, comprising:

[0007] The device includes a shielding layer and an internal structure; the internal structure includes a main control module, a gyroscope, a high-frequency antenna, and a low-frequency antenna; the shielding layer includes a directional receiving antenna.

[0008] The main control module is used to control the high-frequency antenna and the low-frequency antenna to transmit multi-frequency, multi-resolution, and multi-scale electromagnetic wave signals.

[0009] The shielding layer is used to control the radiation direction of the electromagnetic wave signals emitted by the high-frequency antenna and the low-frequency antenna, and to receive the reflected electromagnetic wave signals through the directional receiving antenna.

[0010] The gyroscope is used to record the propagation distance and angle information of the electromagnetic wave signal.

[0011] In one possible implementation, the shielding layer includes a PIN diode;

[0012] The shielding layer is also used to control the radiation direction of the high-frequency antenna and the low-frequency antenna by switching the PIN diode on and off.

[0013] In one possible implementation, the directional receiving antenna is composed of a dipole antenna and several cross-shaped metal structures; when the PIN diode is not conducting, the dipole antenna and the several cross-shaped metal structures are equivalent to a reflector, which reflects electromagnetic wave signals.

[0014] Secondly, the present invention provides a directional detection method, comprising:

[0015] The borehole is obtained using a borehole ground-penetrating radar to acquire radar profile data within the borehole. The radar profile data includes first electromagnetic wave signals of different frequencies and directions emitted by the high-frequency and low-frequency antennas of the borehole ground-penetrating radar to the surrounding area, and second electromagnetic wave signals received by the directional receiving antenna.

[0016] The radar profile data is filtered in the angle domain according to the angle weights corresponding to the transmission angle or the reception angle to obtain the time-space domain wave field.

[0017] Based on the first electromagnetic wave signal and the second electromagnetic wave signal in the time-space domain wave field, determine the spatial energy density and the reverse transmission energy density in the preset direction.

[0018] An imaging profile is obtained based on the spatial energy density and the reverse transmission energy density, and the borehole is detected based on the imaging profile.

[0019] In one possible implementation, the step of performing angle-domain filtering on the radar profile data based on the angle weights corresponding to the transmission angle or reception angle to obtain the time-space domain wavefield includes:

[0020] A two-dimensional Fourier transform is performed on the radar profile data to obtain the frequency-wavenumber domain wavefield.

[0021] Determine the corresponding angle weight based on the transmission angle or the reception angle;

[0022] Angle domain interpolation is performed on the frequency-wavenumber domain wavefield according to the preset first angle domain interpolation algorithm and the angle weights to obtain the plane wavefield;

[0023] The spatial wavefield is obtained by calculating the plane wavefield and the frequency-wavenumber domain wavefield according to the preset second angle domain interpolation algorithm and the angle weights;

[0024] A two-dimensional inverse Fourier transform is performed on the spatial wave field to obtain the time-space domain wave field.

[0025] In one possible implementation, the step of calculating the plane wave field and the frequency-wavenumber domain wave field according to a preset second angle domain interpolation algorithm and the angle weights to obtain the spatial wave field includes:

[0026] A two-dimensional inverse Fourier transform is performed on the frequency-wavenumber domain wavefield to obtain the time-space wavefield;

[0027] The time-space wavefield is subjected to offset filtering to obtain an offset profile after angular domain filtering;

[0028] A two-dimensional inverse Fourier transform is performed on the offset profile to obtain the time-wavenumber wavefield;

[0029] The spatial wavefield is obtained by calculating the time-wavenumber wavefield and the plane wavefield using the second angle domain interpolation algorithm and the angle weights.

[0030] In one possible implementation, determining the spatial energy density and reverse propagation energy density in a preset direction based on the first electromagnetic wave signal and the second electromagnetic wave signal in the time-space domain wave field includes:

[0031] The spatial energy density is obtained by transmitting first electromagnetic wave signals of different frequencies to the borehole in the preset direction by the high-frequency antenna and the low-frequency antenna in the time-space domain wave field.

[0032] The reverse propagation energy density is obtained based on the second electromagnetic wave signal received by the directional receiving antenna in the preset direction in the time-space domain wave field.

[0033] In one possible implementation, obtaining the imaging profile based on the spatial energy density and the backpropagation energy density includes:

[0034] The spatial energy density and the reverse transmission energy density are calculated according to the energy density calculation formula to obtain the target spatial energy density and the target reverse transmission energy density.

[0035] The target spatial energy density and the target backpropagation energy density are calculated according to the preset imaging formula to obtain the imaging profile.

[0036] In one possible implementation, the energy density calculation formula is:

[0037]

[0038] In the formula, , They are respectively x and y Electric field in the direction, It is a magnetic field. For energy density, , They represent x and y The unit vector of direction.

[0039] In one possible implementation, the preset imaging formula is:

[0040]

[0041] In the formula, Energy density intensity, T To calculate the total time, In terms of energy flow direction, The azimuth angle for directional transmission and directional reception of a specified antenna. for Energy density threshold function in the direction, This is the final imaging profile.

[0042] The beneficial effects of this invention are as follows: The borehole ground-penetrating radar device of this invention includes a shielding layer and an internal structure. The internal structure includes a main control module, a gyroscope, a high-frequency antenna, and a low-frequency antenna. The shielding layer includes a directional receiving antenna. The main control module is used to control the high-frequency antenna and the low-frequency antenna to transmit multi-frequency, multi-resolution, and multi-scale electromagnetic wave signals. The shielding layer is used to control the radiation direction of the electromagnetic wave signals transmitted by the high-frequency antenna and the low-frequency antenna, and to receive the reflected electromagnetic wave signals through the directional receiving antenna. Thus, different electromagnetic wave signals can be transmitted and received at different angles according to different needs, meeting the detection requirements. The high-frequency antenna, the low-frequency antenna, and the directional receiving antenna are set on the borehole ground-penetrating radar device, which can transmit and receive electromagnetic wave signals directionally according to needs. The gyroscope records the propulsion distance and angle information of the electromagnetic wave signals, eliminating the need for an additional rotation device. Attached Figure Description

[0043] Figure 1 A schematic diagram of an embodiment of the borehole ground-penetrating radar device provided by the present invention;

[0044] Figure 2 A schematic diagram of an embodiment of the internal structure provided by the present invention;

[0045] Figure 3 A schematic diagram of an embodiment of the shielding layer provided by the present invention;

[0046] Figure 4 A schematic flowchart of an embodiment of the directional detection method provided by the present invention;

[0047] Figure 5 For the present invention Figure 4 A schematic diagram of an embodiment of step S402;

[0048] Figure 6 For the present invention Figure 5 A schematic flowchart of an embodiment of step S504; Detailed Implementation

[0049] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0050] A specific embodiment of the present invention discloses a borehole ground-penetrating radar device, the borehole ground-penetrating radar device as follows: Figure 1 As shown, the borehole ground-penetrating radar device mainly consists of a shielding layer and an internal structure, the internal structure of which is as follows: Figure 2 As shown, the internal structure can include a power supply, a storage module, a main control module, a gyroscope, a high-frequency antenna, and a low-frequency antenna. The borehole ground-penetrating radar device is connected to the drill rod and is pushed into the borehole with it. Upon powering on, the device is powered by an internal high-power battery that continuously supplies power to the borehole ground-penetrating radar. The transmitting antenna of the borehole ground-penetrating radar device adopts a high-frequency + low-frequency combination, enabling multi-frequency, multi-resolution, and multi-scale detection. The high-frequency antenna meets the requirements for small-size, high-resolution detection, while the low-frequency antenna meets the requirements for large-size, low-resolution general surveys. After powering on, the main control module can control the high-frequency and low-frequency antennas to transmit multi-frequency, multi-resolution, and multi-scale electromagnetic wave signals. The shielding layer can control the radiation direction of the electromagnetic wave signals transmitted by the high-frequency and low-frequency antennas. The gyroscope records the propulsion distance and angle information. The electromagnetic wave signals are reflected back from the geological body outside the borehole and received by a directional receiving antenna. The storage module can store the propulsion distance and angle information recorded by the gyroscope after receiving the reflected electromagnetic wave signals.

[0051] Compared with existing technologies, the borehole ground-penetrating radar device provided in this embodiment includes a shielding layer and an internal structure. The internal structure includes a main control module, a gyroscope, a high-frequency antenna, and a low-frequency antenna. The shielding layer includes a directional receiving antenna. The main control module is used to control the high-frequency and low-frequency antennas to transmit multi-frequency, multi-resolution, and multi-scale electromagnetic wave signals. The shielding layer is used to control the radiation direction of the electromagnetic wave signals transmitted by the high-frequency and low-frequency antennas, and to receive the reflected electromagnetic wave signals through the directional receiving antenna. Thus, different electromagnetic wave signals can be transmitted and received at different angles according to different needs, meeting the detection requirements. The high-frequency antenna, low-frequency antenna, and directional receiving antenna are set on the borehole ground-penetrating radar device, which can transmit and receive electromagnetic wave signals directionally according to needs. The gyroscope records the propagation distance and angle information of the electromagnetic wave signals, without the need for an additional rotation device.

[0052] In some embodiments of the present invention, the structure of the shielding layer is as follows: Figure 3 As shown, the shielding layer may include a PIN diode and a directional receiving antenna. The directional receiving antenna is composed of a dipole antenna and several cross-shaped metal structures. The shielding layer can control the radiation direction of the high-frequency antenna and the low-frequency antenna by switching the PIN diode on and off. When the PIN diode is not conducting, the dipole antenna and several cross-shaped metal structures are equivalent to a mesh reflector with high reflection characteristics, reflecting the electromagnetic waves of the radiating antenna back, thereby achieving control of the antenna radiation direction.

[0053] like Figure 4 As shown, a specific embodiment of the present invention discloses a directional detection method, comprising:

[0054] S401. Obtain radar profile data inside the borehole based on borehole ground-penetrating radar; the radar profile data includes first electromagnetic wave signals of different frequencies and directions emitted by the high-frequency and low-frequency antennas of the borehole ground-penetrating radar to the surrounding area, and second electromagnetic wave signals received by the directional receiving antenna.

[0055] This involves using a borehole ground-penetrating radar (GPR) to collect data along the borehole, acquiring the electromagnetic wave data recorded in the GPR's storage module, i.e., the radar profile data within the borehole. Radar profile data can include first electromagnetic wave signals of different frequencies and directions emitted by the high-frequency and low-frequency antennas of the borehole ground-penetrating radar and second electromagnetic wave signals received by the directional receiving antenna. After the high-frequency and low-frequency antennas emit the first electromagnetic wave signals, the first electromagnetic wave signals are reflected back by the geological body outside the borehole, and the directional receiving antenna receives the reflected second electromagnetic wave signals.

[0056] S402. Perform angle domain filtering on the radar profile data according to the angle weights corresponding to the transmission angle or reception angle to obtain the time-space domain wave field.

[0057] The algorithm can be configured with an angle domain interpolation algorithm, and can also determine the angles at which the high-frequency and low-frequency antennas transmit towards the borehole and the angles at which the directional receiving antenna receives the signal. This allows for the determination of the corresponding angle weights. When the first electromagnetic wave signal is calculated using the angle domain interpolation algorithm, the angle weights in the algorithm are the weights of the transmitted angle. When the second electromagnetic wave signal is calculated using the angle domain interpolation algorithm, the angle weights in the algorithm are the weights of the received angle. Thus, the radar profile data can be filtered in the angle domain using the angle domain interpolation algorithm to remove redundant and useless data, thereby obtaining the temporal and spatial domain wave field.

[0058] S403. Determine the spatial energy density and reverse transmission energy density in the preset direction based on the first electromagnetic wave signal and the second electromagnetic wave signal in the time-space domain wave field.

[0059] After filtering the data, a preset direction can be set according to the actual situation, that is, the azimuth angle of the antenna for directional transmission and directional reception. It can be based on the azimuth angle of the wave field in the time and space domain. The corresponding electromagnetic wave signals (i.e., the first electromagnetic wave signal and the second electromagnetic wave signal) determine the corresponding spatial energy density and reverse transmission energy density.

[0060] S404. Based on the spatial energy density and the reverse transmission energy density, an imaging profile is obtained, and the borehole is inspected based on the imaging profile.

[0061] After calculating the spatial energy density and the reverse transmission energy density, the energy threshold constrained imaging algorithm can be used to calculate the spatial energy density and the reverse transmission energy density to obtain the imaging profile. The imaging profile can then be displayed on an electronic device, and staff can analyze and inspect the borehole based on the displayed imaging profile.

[0062] Compared with existing technologies, the borehole ground-penetrating radar provided in this embodiment is equipped with a high-frequency antenna, a low-frequency antenna, and a directional receiving antenna. The high-frequency and low-frequency antennas can emit first electromagnetic wave signals of different frequencies and directions around the borehole, while the directional receiving antenna can receive electromagnetic wave signals. Thus, different second electromagnetic wave signals can be emitted and received at different angles according to different needs, meeting the detection requirements. The radar profile data can be filtered in the angle domain according to the angle weights corresponding to different angles to obtain the temporal and spatial domain wave field. Excessive and inaccurate data are removed, and then the spatial energy density and backpropagation energy density in the preset direction can be determined based on the electromagnetic wave signals in the temporal and spatial domain wave field. Then, the imaging profile can be obtained based on the spatial energy density and backpropagation energy density. The accuracy of the electromagnetic wave signals can be improved by using the spatial energy density and backpropagation energy density, thereby making the detection results of the imaging profile more accurate.

[0063] In some embodiments of the present invention, such as Figure 5 As shown, step S402 includes:

[0064] S501. Perform a two-dimensional Fourier transform on the radar profile data to obtain the frequency-wavenumber domain wave field.

[0065] Among them, the time-space domain electromagnetic wave field at time t in the radar profile data The frequency-wavenumber domain wavefield is obtained by performing a two-dimensional Fourier transform (2D FT). .

[0066] S502. Determine the corresponding angle weight based on the transmission angle or the reception angle.

[0067] This can be based on the corresponding angles (i.e., the azimuth angles for directional transmission and directional reception of the antenna). The corresponding angle weights can be set, and the values ​​can be set according to the actual situation. This embodiment of the invention does not impose any restrictions on them.

[0068] S503. Perform angle domain interpolation calculation on the frequency-wavenumber domain wave field according to the preset first angle domain interpolation algorithm and angle weights to obtain the plane wave field.

[0069] Among them, a preset first angle domain interpolation algorithm can be set, which is used for the frequency-wavenumber domain wave field. Angle domain interpolation is performed to obtain the plane wave field. The preset first angle domain interpolation algorithm is shown in formula (1):

[0070] (1)

[0071] In the formula, , They are respectively x and z Wave number in direction, Angular frequency, For speed, For angle, The angle weights are used.

[0072] S504. The plane wave field and the frequency-wavenumber domain wave field are calculated according to the preset second angle domain interpolation algorithm and angle weights to obtain the space wave field.

[0073] Specifically, a preset second angle domain interpolation algorithm can be set. After calculating the plane wave field and the frequency-wavenumber domain wave field, the preset second angle domain interpolation algorithm and angle weights can be used to process the plane wave field and the frequency-wavenumber domain wave field to obtain the space wave field. .

[0074] S505. Perform a two-dimensional inverse Fourier transform on the spatial wave field to obtain the time-space domain wave field.

[0075] Among them, in obtaining the space wave field Then, the spatial wave field can be analyzed. Performing a two-dimensional inverse Fourier transform (2D FT) yields the processed time-space domain wavefield. .

[0076] In some embodiments of the present invention, such as Figure 6 As shown, step S504 includes:

[0077] S601. Perform a two-dimensional inverse Fourier transform on the frequency-wavenumber domain wavefield to obtain the time-space wavefield.

[0078] Among them, in obtaining the frequency-wavenumber domain wave field Then, the frequency-wavenumber domain wave field can be analyzed. Performing a two-dimensional inverse Fourier transform (2D FT) yields the time-space wavefield. .

[0079] S602. Perform offset filtering on the time-space wave field to obtain the offset profile after angular domain filtering.

[0080] Among these methods, clutter interference can be manually removed after offset filtering to obtain the offset profile after angle-domain filtering. .

[0081] S603. Perform a two-dimensional inverse Fourier transform on the offset profile to obtain the time-wavenumber wave field.

[0082] Among them, offset profiles can be used. Perform a two-dimensional inverse Fourier transform (2D FT) to obtain the time-wavenumber wavefield. .

[0083] S604. The time-wavenumber wave field and the plane wave field are calculated based on the second angle domain interpolation algorithm and angle weights to obtain the spatial wave field.

[0084] Among them, the time-wavenumber wave field can be... Plane wave field The angle weights are substituted into the second angle domain interpolation algorithm for calculation to obtain the spatial wave field. The second angle domain interpolation algorithm is shown in formula (2):

[0085] (2)

[0086] In some embodiments of the present invention, step S403 includes:

[0087] The spatial energy density is obtained by transmitting first electromagnetic wave signals of different frequencies to a predetermined drilling direction using high-frequency and low-frequency antennas in the time-space domain wave field.

[0088] In the operation of a borehole ground-penetrating radar, the emission of electromagnetic waves of different frequencies around the borehole can be considered as energy radiation. The process of electromagnetic waves propagating in different directions and being reflected can be considered as energy radiation in different directions. The energy density varies in different directions. The spatial energy density of electromagnetic wave signals of different frequencies emitted in a specified direction at any given time t is denoted as […]. .

[0089] The reverse propagation energy density is obtained based on the second electromagnetic wave signal received by the directional receiving antenna in the time-space domain wave field in the preset direction.

[0090] In this process, the electromagnetic field emitted by the transmitting antenna propagates outward. When it encounters geological features outside the borehole, the reflected electromagnetic field is recorded by the directional receiving antenna. Then, based on the full-wave equation, the back-propagated energy density at any given time t and a specified angle is calculated and denoted as follows: .

[0091] In some embodiments of the present invention, step S404 includes:

[0092] The space energy density and the reverse transmission energy density are calculated according to the energy density calculation formula to obtain the target space energy density and the target reverse transmission energy density.

[0093] Among them, since the directional drilling ground radar used has the functions of directional transmission and directional reception, the energy density of the electromagnetic field transmitted around the borehole and reflected back and recorded by the receiving antenna has directionality. When processing the data, a directional threshold is constructed to constrain the energy density in this direction, thereby improving the imaging accuracy and realizing directional detection. The energy density calculation formula is shown in formula (3):

[0094] (3)

[0095] In the formula, , They are respectively x and y Electric field in the direction, It is a magnetic field. For energy density, , They represent x and y The unit vector of direction.

[0096] When the electromagnetic wave signal of different frequencies is transmitted in the preset direction by formula (3), the result obtained by formula (3) is the target space energy density. When the electromagnetic wave signal of the preset direction received by the directional receiving antenna is calculated by formula (3), the result obtained by formula (3) is the target reverse transmission energy density.

[0097] The target spatial energy density and the target backpropagation energy density are calculated according to the preset imaging formula to obtain the imaging profile.

[0098] Among them, a preset imaging formula can be set, and the target spatial energy density and the target backpropagation energy density can be substituted into the preset imaging formula for calculation to obtain the imaging profile. The preset imaging formula is shown in formula (4):

[0099] (4)

[0100] In the formula, Energy density intensity, T To calculate the total time, In terms of energy flow direction, The azimuth angle for directional transmission and directional reception of a specified antenna. for Energy density threshold function in the direction, This is the final imaging profile.

[0101] This invention proposes a directional borehole ground-penetrating radar based on an electronically controlled diode shielding layer, which can achieve directional transmission and reception along the borehole radial direction, thereby achieving the purpose of directional scanning detection. It also proposes a cable-free storage-type borehole radar based on multi-frequency antenna coupling, resolving the contradiction between resolution and penetration, and enabling long-term, uninterrupted multi-scale, multi-resolution measurements while drilling. Furthermore, it proposes an angle-domain weighted offset filtering algorithm, which can increase the wave field energy in a specified direction, suppress interference waves in other directions, and improve the data signal-to-noise ratio. Finally, it proposes an energy flow threshold-constrained imaging algorithm, which focuses the electromagnetic wave energy in the target direction, achieving high imaging accuracy and fast calculation speed.

[0102] The directional detection method and device provided by the present invention have been described in detail above. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A borehole ground-penetrating radar device, characterized in that, The device includes a shielding layer and an internal structure; the internal structure includes a main control module, a gyroscope, a high-frequency antenna, and a low-frequency antenna; the shielding layer includes a directional receiving antenna. The main control module is used to control the high-frequency antenna and the low-frequency antenna to transmit multi-frequency, multi-resolution, and multi-scale electromagnetic wave signals. The shielding layer is used to control the radiation direction of the electromagnetic wave signals emitted by the high-frequency antenna and the low-frequency antenna, and to receive the reflected electromagnetic wave signals through the directional receiving antenna. The gyroscope is used to record the propulsion distance and angle information of the electromagnetic wave signal; The shielding layer includes a PIN diode; The shielding layer is also used to control the radiation direction of the high-frequency antenna and the low-frequency antenna by switching the PIN diode on and off; The directional receiving antenna is composed of a dipole antenna and several cross-shaped metal structures; when the PIN diode is not conducting, the dipole antenna and the several cross-shaped metal structures reflect electromagnetic wave signals.

2. A directional detection method, characterized in that, The method applicable to the borehole ground-penetrating radar device of claim 1 includes: The borehole is obtained using a borehole ground-penetrating radar to acquire radar profile data within the borehole. The radar profile data includes first electromagnetic wave signals of different frequencies and directions emitted by the high-frequency and low-frequency antennas of the borehole ground-penetrating radar to the surrounding area, and second electromagnetic wave signals received by the directional receiving antenna. The radar profile data is filtered in the angle domain according to the angle weights corresponding to the transmission angle or the reception angle to obtain the time-space domain wave field. Based on the first electromagnetic wave signal and the second electromagnetic wave signal in the time-space domain wave field, determine the spatial energy density and the reverse transmission energy density in the preset direction. An imaging profile is obtained based on the spatial energy density and the reverse transmission energy density, and the borehole is detected based on the imaging profile.

3. The directional detection method according to claim 2, characterized in that, The step of performing angle-domain filtering on the radar profile data based on the angle weights corresponding to the transmission or reception angle to obtain the time-space domain wavefield includes: A two-dimensional Fourier transform is performed on the radar profile data to obtain the frequency-wavenumber domain wavefield. Determine the corresponding angle weight based on the transmission angle or the reception angle; Angle domain interpolation is performed on the frequency-wavenumber domain wavefield according to the preset first angle domain interpolation algorithm and the angle weights to obtain the plane wavefield; The spatial wavefield is obtained by calculating the plane wavefield and the frequency-wavenumber domain wavefield according to the preset second angle domain interpolation algorithm and the angle weights; A two-dimensional inverse Fourier transform is performed on the spatial wave field to obtain the time-space domain wave field.

4. The directional detection method according to claim 3, characterized in that, The step of calculating the spatial wavefield by using a preset second angle domain interpolation algorithm and the angle weights to obtain the plane wavefield and the frequency-wavenumber domain wavefield includes: A two-dimensional inverse Fourier transform is performed on the frequency-wavenumber domain wavefield to obtain the time-space wavefield; The time-space wavefield is subjected to offset filtering to obtain an offset profile after angular domain filtering; A two-dimensional inverse Fourier transform is performed on the offset profile to obtain the time-wavenumber wavefield; The spatial wavefield is obtained by calculating the time-wavenumber wavefield and the plane wavefield using the second angle domain interpolation algorithm and the angle weights.

5. The directional detection method according to claim 2, characterized in that, The step of determining the spatial energy density and reverse transmission energy density in a preset direction based on the first electromagnetic wave signal and the second electromagnetic wave signal in the time-space domain wave field includes: The spatial energy density is obtained by transmitting first electromagnetic wave signals of different frequencies to the borehole in the preset direction by the high-frequency antenna and the low-frequency antenna in the time-space domain wave field. The reverse propagation energy density is obtained based on the second electromagnetic wave signal received by the directional receiving antenna in the preset direction in the time-space domain wave field.

6. The directional detection method according to claim 2, characterized in that, The step of obtaining the imaging profile based on the spatial energy density and the reverse transmission energy density includes: The spatial energy density and the reverse transmission energy density are calculated according to the energy density calculation formula to obtain the target spatial energy density and the target reverse transmission energy density. The target spatial energy density and the target backpropagation energy density are calculated according to the preset imaging formula to obtain the imaging profile.

7. The directional detection method according to claim 6, characterized in that, The formula for calculating the energy density is: In the formula, , They are respectively x and y Electric field in the direction, It is a magnetic field. For energy density, , They represent x and y The unit vector of direction.

8. The directional detection method according to claim 6, characterized in that, The preset imaging formula is: In the formula, Energy density intensity, T To calculate the total time, In terms of energy flow direction, The azimuth angle for directional transmission and directional reception of a specified antenna. for Energy density threshold function in the direction, This is the final imaging profile.

Images