Multi-frequency drilling radar device and control method

Abstract

The invention discloses a multi-frequency drill hole radar device and a control method, and the method comprises the steps: placing a drill hole radar into a drill hole, and feeding the drill hole radar into the deepest part of the drill hole through a drill rod; wherein the borehole radar comprises transmitting and receiving antennas with different frequencies; the drilling radar carries out electromagnetic data acquisition according to a set working mode, wherein the working mode comprises a time triggering mode and a distance triggering mode; the data acquisition comprises acquisition of low-frequency electromagnetic data and high-frequency electromagnetic data; when the drilling radar works, the angle correction module records the angular displacement of the drilling radar according to the working mode of the drilling radar; and according to the collected low-frequency electromagnetic data and high-frequency electromagnetic data and the recorded angular displacement of the borehole radar, obtaining stratum structure and geological target information around the borehole. The technical scheme provided by the invention is adopted.

Description

Technical Field

[0001] The invention relates to the field of geological detection, and in particular to a multi-frequency borehole radar device and a control method. Background Art

[0002] Existing borehole radars also have some technical limitations. First of all, in terms of antennas, due to the limitation of borehole space, it is difficult to design and implement borehole radar antennas with directional performance; therefore, current borehole radars generally use low-frequency omnidirectional dipole antennas, which can transmit and receive signals in all directions, but cannot determine the specific orientation of the reflector when using single-hole reflection measurement, but can only determine the existence of the reflector and its distance from the borehole. In addition, the current operating frequency of borehole radars is relatively single, and it is difficult to adapt to the requirements for detection depth and resolution under different exploration environments and geological conditions. For example, in some complex geological environments, the use of lower frequencies can achieve a deeper detection depth, but it will also sacrifice the ability to identify small reflective targets near the borehole. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a multi-frequency borehole radar device control method, comprising the following steps:

[0004] Step 1: Place the borehole radar into the borehole and send the borehole radar to the deepest part of the borehole through the drill rod; wherein the borehole radar includes transceiver antennas with different frequencies;

[0005] Step 2: The borehole radar collects electromagnetic data according to a set working mode, wherein the working mode includes a time trigger mode and a distance trigger mode; the data collection includes collecting low-frequency electromagnetic data and high-frequency electromagnetic data;

[0006] Step 3: When the borehole radar is working, the angle correction module records the angular displacement of the borehole radar according to the working mode of the borehole radar;

[0007] Step 4: Based on the collected low-frequency electromagnetic data and high-frequency electromagnetic data, and the recorded angular displacement of the borehole radar, the stratigraphic structure and geological target information around the borehole are obtained.

[0008] Furthermore, the working mode includes:

[0009] The working modes include time trigger mode and distance trigger mode. When the time trigger mode is adopted, the signal control module drives the antenna to transmit and collect signals at set time intervals.

[0010] When the distance trigger mode is adopted, the distance measuring wheel measures the moving distance of the borehole radar and outputs a trigger pulse through photoelectric conversion, driving the signal transmission and collection work of the antenna at every set distance.

[0011] Furthermore, when the time trigger mode is adopted, the signal control module drives the antenna to transmit and collect signals at set time intervals, including:

[0012] When the low-frequency omnidirectional antenna is working, it emits omnidirectional electromagnetic waves along the radial direction of the borehole according to the sampling trigger pulse output by the signal control module, and receives the electromagnetic wave signal reflected by the reflector to obtain low-frequency data.

[0013] Furthermore, when the distance trigger mode is adopted, the distance measuring wheel measures the moving distance of the borehole radar, and outputs a trigger pulse through photoelectric conversion, and drives the signal transmission and collection work of the antenna at every set distance, including:

[0014] When the high-frequency omnidirectional transmitting antenna and the high-frequency directional receiving antenna array are working, the high-frequency omnidirectional transmitting antenna emits directional electromagnetic waves along the radial direction of the borehole according to the sampling trigger pulse output by the signal control module, and the high-frequency directional receiving antenna array receives the electromagnetic wave signals reflected back by the reflector to obtain multiple groups of high-frequency data.

[0015] Furthermore, when the borehole radar is working, the angle correction module records the angular displacement of the borehole radar according to the working mode of the borehole radar, including:

[0016] When the borehole radar adopts the time trigger mode or the distance trigger mode, when collecting low-frequency data and high-frequency data, the angle correction module records the angular displacement data during measurement according to the sampling trigger pulse output by the signal control module.

[0017] A multi-frequency borehole radar device, using the multi-frequency borehole radar device control method, comprising: a low-frequency omnidirectional antenna, a high-frequency omnidirectional transmitting antenna, a high-frequency directional receiving antenna array, a radar host and a ranging wheel;

[0018] The low-frequency omnidirectional antenna, high-frequency omnidirectional transmitting antenna, high-frequency directional receiving antenna array and ranging wheel are respectively connected to the radar host;

[0019] Wherein, the low-frequency omnidirectional antenna is used to transmit and receive low-frequency omnidirectional electromagnetic waves;

[0020] The high-frequency omnidirectional transmitting antenna is used to transmit high-frequency omnidirectional electromagnetic waves.

[0021] The high-frequency directional receiving antenna array is used to receive the reflected high-frequency directional electromagnetic waves; the high-frequency directional receiving antenna array is composed of a plurality of high-frequency directional receiving antennas facing different directions;

[0022] The radar host is used for data collection and storage of the borehole radar;

[0023] The distance measuring wheel is used to measure the distance traveled by the drilling radar in the hole to provide a distance trigger mode.

[0024] Preferably, the radar host includes a signal control module, an angle correction module, a storage module and a power supply module;

[0025] The signal control module, angle correction module and power supply module are respectively connected to the storage module;

[0026] The signal control module is used to control the transmission and reception of electromagnetic waves of the low-frequency omnidirectional antenna, the high-frequency omnidirectional transmitting antenna and the high-frequency receiving directional antenna;

[0027] The angle correction module is used to record the angular displacement generated by the borehole radar while collecting data;

[0028] The storage module is used to store the collected low-frequency data and high-frequency data;

[0029] The power supply module is used to provide power supply.

[0030] The beneficial effects of the present invention are:

[0031] (1) By transmitting and receiving electromagnetic wave signals of two different frequencies, low-frequency data and high-frequency data can be collected simultaneously in one drilling measurement.

[0032] (2) Low-frequency data is suitable for distance detection of deep reflectors that do not require angle positioning information. In terms of high-frequency data, unlike omnidirectional low-frequency electromagnetic wave signals that can only determine the distance of reflectors around the borehole from the borehole but cannot determine the specific direction, high-frequency electromagnetic waves will serve as directional signals and can achieve accurate angle positioning of reflectors with the borehole as the axis. The coordinated detection of high-frequency and low-frequency signals may enable the estimation of the direction and trend of surrounding rock cracks.

[0033] (3) In addition, as needed, the two types of data can be fused during data interpretation to enhance the resolution of shallow reflectors around the borehole in the data while maintaining the information of deep reflectors. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a flowchart of a control method of a multi-frequency borehole radar device;

[0035] Figure 2 It is a schematic diagram of the structure of the multi-frequency borehole radar;

[0036] Figure 3 The implementation workflow diagram for multi-frequency borehole radar;

[0037] Figure 4 This is a schematic diagram of a high frequency directional receiving antenna array;

[0038] Figure 5 This is a schematic diagram of the structure of a high-frequency directional receiving antenna;

[0039] Figure 6 This is a schematic diagram of the arrangement of high-frequency directional receiving antenna arrays;

[0040] Figure 7 Schematic diagram of the low-frequency omnidirectional antenna structure;

[0041] Figure 8 A flowchart of a method for interpreting multi-frequency borehole radar data is shown. DETAILED DESCRIPTION

[0042] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following.

[0043] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0044] like Figure 1 As shown, a multi-frequency borehole radar device control method comprises the following steps:

[0045] Step 1: Place the borehole radar into the borehole and send the borehole radar to the deepest part of the borehole through the drill rod; wherein the borehole radar includes transceiver antennas with different frequencies;

[0046] Step 2: The borehole radar collects electromagnetic data according to a set working mode, wherein the working mode includes a time trigger mode and a distance trigger mode; the data collection includes collecting low-frequency electromagnetic data and high-frequency electromagnetic data;

[0047] Step 3: When the borehole radar is working, the angle correction module records the angular displacement of the borehole radar according to the working mode of the borehole radar;

[0048] Step 4: Based on the collected low-frequency electromagnetic data and high-frequency electromagnetic data, and the recorded angular displacement of the borehole radar, the stratigraphic structure and geological target information around the borehole are obtained.

[0049] The working modes include:

[0050] The working modes include time trigger mode and distance trigger mode. When the time trigger mode is adopted, the signal control module drives the antenna to transmit and collect signals at set time intervals.

[0051] When the distance trigger mode is adopted, the distance measuring wheel measures the moving distance of the borehole radar and outputs a trigger pulse through photoelectric conversion, driving the signal transmission and collection work of the antenna at every set distance.

[0052] When the time trigger mode is adopted, the signal control module drives the antenna to transmit and collect signals at set time intervals, including:

[0053] When the low-frequency omnidirectional antenna is working, it emits omnidirectional electromagnetic waves along the radial direction of the borehole according to the sampling trigger pulse output by the signal control module, and receives the electromagnetic wave signal reflected by the reflector to obtain low-frequency data.

[0054] When the distance trigger mode is adopted, the distance measuring wheel measures the moving distance of the borehole radar and outputs a trigger pulse through photoelectric conversion to drive the signal transmission and collection work of the antenna at every set distance, including:

[0055] When the high-frequency omnidirectional transmitting antenna and the high-frequency directional receiving antenna array are working, the high-frequency omnidirectional transmitting antenna emits directional electromagnetic waves along the radial direction of the borehole according to the sampling trigger pulse output by the signal control module, and the high-frequency directional receiving antenna array receives the electromagnetic wave signals reflected back by the reflector to obtain multiple groups of high-frequency data.

[0056] When the borehole radar is working, the angle correction module records the angular displacement of the borehole radar according to the working mode of the borehole radar, including:

[0057] When the borehole radar adopts the time trigger mode or the distance trigger mode, when collecting low-frequency data and high-frequency data, the angle correction module records the angular displacement data during measurement according to the sampling trigger pulse output by the signal control module.

[0058] A multi-frequency borehole radar device, using the multi-frequency borehole radar device control method, comprising: a low-frequency omnidirectional antenna, a high-frequency omnidirectional transmitting antenna, a high-frequency directional receiving antenna array, a radar host and a ranging wheel;

[0059] The low-frequency omnidirectional antenna, high-frequency omnidirectional transmitting antenna, high-frequency directional receiving antenna array and ranging wheel are respectively connected to the radar host;

[0060] Wherein, the low-frequency omnidirectional antenna is used to transmit and receive low-frequency omnidirectional electromagnetic waves;

[0061] The high-frequency omnidirectional transmitting antenna is used to transmit high-frequency omnidirectional electromagnetic waves.

[0062] The high-frequency directional receiving antenna array is used to receive the reflected high-frequency directional electromagnetic waves; the high-frequency directional receiving antenna array is composed of a plurality of high-frequency directional receiving antennas facing different directions;

[0063] The radar host is used for data collection and storage of the borehole radar;

[0064] The distance measuring wheel is used to measure the distance traveled by the drilling radar in the hole to provide a distance trigger mode.

[0065] The radar host comprises a signal control module, an angle correction module, a storage module and a power supply module;

[0066] The signal control module, angle correction module and power supply module are respectively connected to the storage module;

[0067] The signal control module is used to control the transmission and reception of electromagnetic waves of the low-frequency omnidirectional antenna, the high-frequency omnidirectional transmitting antenna and the high-frequency receiving directional antenna;

[0068] The angle correction module is used to record the angular displacement generated by the borehole radar while collecting data;

[0069] The storage module is used to store the collected low-frequency data and high-frequency data;

[0070] The power supply module is used to provide power supply.

[0071] Specifically, in view of the shortcomings of the existing borehole radar system using omnidirectional dipole antennas, such as non-directionality, single frequency, and inability to meet complex measurement conditions, the present invention provides a borehole radar device based on a multi-frequency antenna and a method for using the same.

[0072] By designing two transceiver antennas with different frequencies to transmit and receive electromagnetic waves, it is possible to simultaneously collect low-frequency electromagnetic data and high-frequency electromagnetic data in one drilling measurement.

[0073] In the application of low-frequency electromagnetic data, it is mainly used to evaluate the distance detection from deep reflectors, but cannot determine the direction of the reflectors. In the application of high-frequency electromagnetic data, the directional antenna design used can determine the distance and direction of the reflectors with the borehole as the axis.

[0074] In addition, as needed, data fusion can be performed when processing and interpreting the two types of electromagnetic data to enhance the resolution of shallow reflectors around the borehole in the radar image while retaining the information of deep reflectors.

[0075] In some special geological structures, the direction and range of fracture extension can be roughly inferred by combining the azimuth information of near-well targets detected by high-frequency antennas with the distance information of deep targets detected by low-frequency antennas.

[0076] The following is a detailed description of the embodiments of the present invention in conjunction with the accompanying drawings and embodiments:

[0077] like Figure 2 The multi-frequency borehole radar equipment provided by the embodiment of the present invention includes:

[0078] A low-frequency omnidirectional antenna 100, used for transmitting and receiving low-frequency omnidirectional electromagnetic waves;

[0079] A high-frequency omnidirectional transmitting antenna 200 is used to transmit high-frequency omnidirectional electromagnetic waves;

[0080] The high-frequency directional receiving antenna array 300 is used to receive the reflected high-frequency directional electromagnetic waves. The high-frequency directional receiving antenna array 300 is composed of a plurality of high-frequency directional receiving antennas facing different directions;

[0081] The radar host 400 is used for data collection and storage of the borehole radar. The radar host 400 includes three submodules, namely a signal control module 410, an angle correction module 420, a storage module 430, and a power supply module 440;

[0082] A signal control module 410, used to control the transmission and reception of electromagnetic waves of the low-frequency omnidirectional antenna 100, the high-frequency omnidirectional transmitting antenna 200 and the high-frequency receiving directional antenna 300;

[0083] Angle correction module 420, used to record the angular displacement generated by the borehole radar while collecting data, so as to perform later data correction and fusion;

[0084] The storage module 430 is used to store the collected low-frequency data and high-frequency data;

[0085] A power supply module 440 provides power supply to other modules;

[0086] The housing 500 is used to place the low-frequency omnidirectional antenna 100, the high-frequency omnidirectional transmitting antenna 200, the high-frequency directional receiving antenna array 300, and the radar host 400 therein to prevent foreign objects in the borehole from invading the borehole radar and to provide protection.

[0087] The distance measuring wheel 600 is used to measure the distance that the borehole radar travels in the hole to provide a distance trigger mode. In the distance trigger mode, when the borehole radar travels in the hole, the distance measuring wheel 600 closely adheres to the hole wall to measure the moving distance of the borehole radar, and outputs a trigger pulse through photoelectric conversion to drive the antenna to transmit and collect signals at intervals.

[0088] Figure 3 The working flow diagram of a specific embodiment includes:

[0089] S100, put the borehole radar into the hole and send it to the deepest part of the borehole through the drill pipe. During this period, the drill pipe needs to be mechanically connected to the borehole radar.

[0090] S101, after the drilling radar reaches the deepest part of the borehole, the staff pulls out the drill rod to drive the drilling radar to move toward the hole mouth.

[0091] S102, the borehole radar works according to the working mode set by the staff. The working modes of the borehole radar include time trigger mode and distance trigger mode. When the time trigger mode is adopted, the signal control module 410 will drive the antenna to transmit and collect signals at intervals; when the distance trigger mode is adopted, the distance measuring wheel 600 is close to the hole wall to measure the moving distance of the borehole radar, and outputs trigger pulses through photoelectric conversion, driving the antenna to transmit and collect signals at intervals.

[0092] S102-1, when the low-frequency omnidirectional antenna 100 is working, it emits omnidirectional electromagnetic waves along the radial direction of the borehole according to the sampling trigger pulse output by the signal control module 410, and receives the electromagnetic wave signal reflected by the reflector to obtain low-frequency data. Since the center frequency of the low-frequency omnidirectional antenna 100 is low and it is an omnidirectional antenna, the low-frequency omnidirectional antenna 100 is suitable for distance detection of deep reflectors that do not require angle positioning information.

[0093] Preferably, the low-frequency omnidirectional antenna 100 is an omnidirectional dipole antenna in a transceiver-integrated mode, that is, it is responsible for transmitting and receiving electromagnetic waves at the same time.

[0094] S102-2, when the high-frequency omnidirectional transmitting antenna 200 and the high-frequency directional receiving antenna array 300 are working, the high-frequency omnidirectional transmitting antenna 200 transmits directional electromagnetic waves along the radial direction of the borehole according to the sampling trigger pulse output by the signal control module 410, and the high-frequency directional receiving antenna array 300 is responsible for receiving the electromagnetic wave signals reflected back by the reflector to obtain multiple sets of high-frequency data. Since the high-frequency directional receiving antenna array 300 includes multiple sets of high-frequency directional receiving antennas, the multiple sets of high-frequency data are high-frequency data sets facing different directions. The operator can roughly determine the position information of the reflector with the borehole as the radial direction based on the signal strength and phase difference in the multiple sets of high-frequency data under the same sampling, and infer the angular azimuth information of the transmitter relative to the borehole based on the azimuth of the receiving antenna corresponding to the multiple sets of high-frequency data. Since the center frequency of the high-frequency directional receiving antenna array 300 is relatively high and it is a directional antenna, the high-frequency directional receiving antenna array 300 is suitable for distance detection of shallow reflectors that require angle positioning information.

[0095] Preferably, the center frequency of the low-frequency omnidirectional antenna 100 is not higher than 100 MHz, and the center frequencies of the high-frequency omnidirectional transmitting antenna 200 and the high-frequency directional receiving antenna array 300 are not lower than 200 MHz.

[0096] S103, when the borehole radar is working, the angle correction module 420 will record the angular displacement of the borehole radar according to the working mode of the borehole radar. For example, when the borehole radar adopts the time trigger mode or the distance trigger mode, in addition to collecting low-frequency data and high-frequency data, the angle correction module 420 will also record the angular displacement data during measurement according to the sampling trigger pulse output by the signal control module 410.

[0097] S104, data collection is completed, and at the same time, the borehole radar is taken out of the borehole. The operator sends the collected and stored data to the data processing equipment for data processing.

[0098] The effects of the present invention are:

[0099] (1) By transmitting and receiving electromagnetic wave signals of two different frequencies, low-frequency data and high-frequency data can be collected simultaneously in one drilling measurement.

[0100] (2) Low-frequency data is suitable for distance detection of deep reflectors that do not require angle positioning information. In terms of high-frequency data, unlike omnidirectional low-frequency electromagnetic wave signals that can only determine the distance of reflectors around the borehole from the borehole but cannot determine the specific direction, high-frequency electromagnetic waves will serve as directional signals and can achieve accurate angle positioning of reflectors with the borehole as the axis. The coordinated detection of high-frequency and low-frequency signals may enable the estimation of the direction and trend of surrounding rock cracks.

[0101] (3) In addition, as needed, the two types of data can be fused during data interpretation to enhance the resolution of shallow reflectors around the borehole in the data while maintaining the information of deep reflectors.

[0102] In this embodiment, the antennas of the high-frequency directional receiving antenna array 300 are arranged as follows: Figure 4 As shown:

[0103] The high-frequency directional receiving antenna array 300 is composed of three high-frequency directional receiving antennas 310 that are closely attached to each other, and the three high-frequency directional receiving antennas face three directions respectively. Each high-frequency directional receiving antenna 310 is composed of an antenna vibrator 311, a loading resistor 312, a high dielectric constant filling medium 313 and a metal reflector 314. Figure 5 shown.

[0104] The antenna vibrator 311 is used to receive the electromagnetic wave signal reflected by the target body. The loading resistor 312 is used to reduce the current oscillation at the end of the antenna vibrator 311 to improve the quality of the received signal. The metal reflector 314 is used to be placed behind the antenna vibrator 311 to achieve isolation of electromagnetic signals from other directions. The high dielectric constant medium 313 is used to fill between the antenna vibrator 311 and the metal reflector 314 to reduce the interference of the echo electromagnetic signal from the metal reflector 314 on the target reflection signal received by the antenna vibrator 311 itself. The high dielectric constant characteristic of the medium 313 should reduce the propagation wavelength of the back electromagnetic wave therein. Ideally, the spacing between the reflector 314 and the antenna vibrator 311 should be a quarter wavelength to minimize the destructive interference of the electromagnetic signal reflected by the reflector 314 on the distant echo signal received by the antenna vibrator 311. In this embodiment, the effect of using three high-frequency directional receiving antennas is that high-frequency electromagnetic waves can be used as directional signals to achieve angular positioning of the reflector in three directions with the borehole as the axis.

[0105] The following is another embodiment of the high-frequency directional receiving antenna array 300. The high-frequency directional receiving antennas of the high-frequency directional receiving antenna array 300 are arranged differently, such as Figure 6 shown.

[0106] In this embodiment, three high-frequency directional receiving antennas 310 are arranged along the axial direction of the borehole radar. The effect of this is to increase the distance between the antenna vibrator 311 and the metal reflector 314. When the material selection of the high dielectric constant filling medium 313 is limited, the signal crosstalk phenomenon that may be generated when the three high-frequency directional receiving antennas 310 receive the reflected signal can be alleviated to a greater extent.

[0107] In another embodiment of the present invention, the low-frequency omnidirectional antenna 100 adopts a single-transmit and single-receive mode, such as Figure 7 shown.

[0108] The low-frequency omnidirectional antenna 100 is composed of a low-frequency omnidirectional transmitting antenna 110 and a low-frequency omnidirectional receiving antenna 120. The low-frequency omnidirectional transmitting antenna 110 is responsible for transmitting electromagnetic waves, and the low-frequency omnidirectional receiving antenna 120 is responsible for receiving electromagnetic wave signals reflected by the reflector. The low-frequency omnidirectional transmitting antenna 110 and the low-frequency omnidirectional receiving antenna 120 are arranged along the axial direction.

[0109] In this embodiment, the effect of using the low-frequency omnidirectional transmitting antenna 110 and the low-frequency omnidirectional receiving antenna 120 is that the reflected signal in the low-frequency omnidirectional receiving antenna 120 will not be disturbed by the residual surface current oscillation of the electromagnetic wave transmitted by the low-frequency omnidirectional transmitting antenna 110, which can significantly improve the signal-to-noise ratio of the low-frequency data. (All omnidirectional antennas that can transmit and receive low-frequency electromagnetic wave signals must be protected)

[0110] In another embodiment of the present invention, the high-frequency directional receiving antenna array 300 is no longer used, but a single high-frequency directional transmitting antenna 200 and a high-frequency directional receiving antenna 320 are used. At the same time, the arrangement of the distance measuring wheel 600 is changed to a circumferential distance measuring wheel 610, and its axis is arranged parallel to the axis of the borehole to record the total rotation path of the borehole radar.

[0111] Since a single high-frequency directional transmitting antenna 200 and a high-frequency directional receiving antenna 320 are used, the borehole radar needs to be rotated during measurement to receive reflector echo signals at all angles. In this embodiment, the workflow includes:

[0112] S200, put the borehole radar into the hole and send it to the deepest part of the borehole through the drill pipe. During this period, the drill pipe needs to be mechanically connected to the borehole radar.

[0113] S201, after the drilling radar reaches the deepest part of the borehole, the operator pulls out the drill rod and rotates the drill rod clockwise or counterclockwise at the same time. The radially rotating drill rod will drive the drilling radar to move toward the hole mouth.

[0114] S202, the borehole radar operates according to the operating mode set by the operator. The operating modes of the borehole radar include time trigger mode and distance trigger mode. When the time trigger mode is adopted, the signal control module 410 will drive the antenna to transmit and collect signals at intervals; when the distance trigger mode is adopted, the distance measuring wheel 600 is close to the hole wall to measure the moving distance of the borehole radar, and outputs trigger pulses through photoelectric conversion, driving the antenna to transmit and collect signals at intervals.

[0115] S202-1, when the low-frequency omnidirectional antenna 100 is working, it emits omnidirectional electromagnetic waves along the radial direction of the borehole according to the sampling trigger pulse output by the signal control module 410, and receives the electromagnetic wave signal reflected by the reflector to obtain low-frequency data. Since the center frequency of the low-frequency omnidirectional antenna 100 is low and it is an omnidirectional antenna, the low-frequency omnidirectional antenna 100 can only detect the distance of the deep reflector but cannot provide azimuth information.

[0116] S202-2, when the high-frequency directional transmitting antenna 200 and the high-frequency directional receiving antenna 320 are working, the high-frequency directional transmitting antenna 200 transmits directional electromagnetic waves along the radial direction of the borehole according to the sampling trigger pulse output by the signal control module 410, and the high-frequency directional receiving antenna 320 is responsible for receiving the electromagnetic wave signal reflected back by the reflector to obtain high-frequency data. At the same time, the angle correction module 420 will record the angular displacement of the borehole radar according to the working mode of the borehole radar. For example, when the borehole radar adopts the time trigger mode or the distance trigger mode, in addition to collecting low-frequency data and high-frequency data, the angle correction module 420 will also record the angular displacement data during measurement according to the sampling trigger pulse output by the signal control module 410, and form the high-frequency data at the current angle with the high-frequency data.

[0117] S203, data collection is completed, and at the same time, the borehole radar is taken out of the borehole. The operator sends the collected and stored data to the data processing equipment for data processing.

[0118] In the embodiment of the present invention, the use of a single high-frequency directional transmitting antenna 200 and a high-frequency directional receiving antenna 320 has the following effects:

[0119] (1) There is no need for multiple high-frequency directional receiving antennas 320 to form a high-frequency directional receiving antenna array 300. With the angle correction module 420, it is possible to simultaneously collect low-frequency data and high-frequency data in a drilling measurement by transmitting and receiving electromagnetic wave signals of two different frequencies.

[0120] (2) Unlike omnidirectional low-frequency electromagnetic wave signals, which can only determine the distance of the reflectors around the borehole from the borehole but cannot determine the specific orientation of the reflectors, high-frequency electromagnetic waves will serve as directional signals and can achieve precise angular positioning of the reflectors with the borehole as the axis.

[0121] (3) In addition, as needed, the two types of data can be fused during data interpretation to enhance the resolution of shallow reflectors around the borehole in the data.

[0122] The present invention takes a specific embodiment as an example to illustrate a method for interpreting multi-frequency borehole radar data. The work flow diagram is as follows: Figure 8 shown.

[0123] S300, performing preprocessing operations on the low-frequency data, including but not limited to direct wave removal, background signal removal, bandpass filtering and gain.

[0124] S301, preprocessing operations are performed on the high-frequency data, including but not limited to direct wave removal, background signal removal, bandpass filtering and gain, and the angle information of the angle correction module 420 is attached as a reference.

[0125] In the embodiment using the high-frequency directional receiving antenna array 300, there will be three high-frequency data with angle information for preprocessing. At this time, the angle information of the angle correction module 420 needs to be used as calibration to compensate for the angular displacement that the borehole radar may produce in the borehole; in the embodiment using a single high-frequency directional receiving antenna 320, there will be one high-frequency data with angle information for preprocessing. At this time, it is only necessary to attach the angle information of the angle correction module 420 to each sampled high-frequency data.

[0126] S302, combining low-frequency data and high-frequency data for advanced geological forecast interpretation. The low-frequency data is suitable for distance detection of deep reflectors that do not require angle positioning information. The high-frequency data can determine the distance of the reflectors around the borehole from the borehole, as well as the precise angle positioning of the reflectors with the borehole as the axis.

[0127] Specifically, after the low-frequency data is preprocessed, a reflector signal as shown in Figure X is generated. According to the propagation time from the deep reflector signal to the borehole and the estimated propagation speed of the electromagnetic wave in the medium, the depth of the deep reflector from the borehole can be calculated.

[0128] In the embodiment using the high-frequency directional receiving antenna array 300, after the high-frequency data is preprocessed, there will be three reflector signals with angle information. According to the amplitude difference and time phase difference of the three reflector signals, the angle position of the reflector around the borehole can be determined. For example, the angle information of the high-frequency directional receiving antenna 310 corresponding to the signal with the largest signal amplitude and the shortest time phase among the three reflector signals is the angle position of the reflector around the borehole; in the embodiment using the high-frequency directional receiving antenna 320, after the high-frequency data is preprocessed, there will be one reflector signal with angle information. According to the amplitude difference and time phase difference of the reflector signal at different rotation angles, the angle position of the reflector around the borehole can be determined. For example, for a reflector around a borehole, the corresponding signal amplitude will show a cyclic change of increase-decrease-increase-decrease, because the borehole radar is measured in a spiral advance in the borehole. Find the maximum amplitude in the middle of the overall signal, and the corresponding angle information of the angle correction module 420 is the angle of the reflector around the borehole. In these two embodiments, the depth of the reflectors around the borehole from the borehole can be calculated based on the propagation time from the point where the signal amplitude of the reflectors around the borehole is maximum to the borehole and the estimated propagation speed of the electromagnetic wave in the medium.

[0129] S303, according to the needs of data interpretation, the low-frequency data and the high-frequency data can also be fused to enhance the resolution of the shallow reflectors around the borehole in the data while maintaining the information of the deep reflectors. In the embodiment using the high-frequency directional receiving antenna array 300, the high-frequency data of the three reflected signals with angle information are first aligned with the low-frequency data, and then superimposed with the low-frequency data to obtain the high- and low-frequency data fusion images of the three different high-frequency directional receiving antennas 310; in the embodiment using the high-frequency directional receiving antenna 320, the number of sampling points N of the borehole radar rotation is first determined, and then the high-frequency data of the N reflected signals with angle information are aligned with the low-frequency data, and finally superimposed with the low-frequency data to obtain the high- and low-frequency data fusion images of N different angle information.

Claims

1. A multi-frequency borehole radar device control method, characterized in that: The steps include: Step 1: Place the borehole radar into the borehole and send the borehole radar to the deepest part of the borehole through the drill rod; wherein the borehole radar includes transceiver antennas with different frequencies; Step 2: The borehole radar collects electromagnetic data according to a set working mode, wherein the working mode includes a time trigger mode and a distance trigger mode; the data collection includes collecting low-frequency electromagnetic data and high-frequency electromagnetic data; Step 3: When the borehole radar is working, the angle correction module records the angular displacement of the borehole radar according to the working mode of the borehole radar; Step 4: Based on the collected low-frequency electromagnetic data and high-frequency electromagnetic data, and the recorded angular displacement of the borehole radar, the stratigraphic structure and geological target information around the borehole are obtained.

2. A multi-frequency borehole radar device control method according to claim 1, characterized in that: The working modes include: The working modes include time trigger mode and distance trigger mode. When the time trigger mode is adopted, the signal control module drives the antenna to transmit and collect signals at set time intervals. When the distance trigger mode is adopted, the distance measuring wheel measures the moving distance of the borehole radar and outputs a trigger pulse through photoelectric conversion, driving the signal transmission and collection work of the antenna at every set distance.

3. A multi-frequency borehole radar device control method according to claim 2, characterized in that: When the time trigger mode is adopted, the signal control module drives the antenna to transmit and collect signals at set time intervals, including: When the low-frequency omnidirectional antenna is working, it emits omnidirectional electromagnetic waves along the radial direction of the borehole according to the sampling trigger pulse output by the signal control module, and receives the electromagnetic wave signal reflected back by the reflector to obtain low-frequency data.

4. The method for controlling a multi-frequency borehole radar device according to claim 2, characterized in that: When the distance trigger mode is adopted, the distance measuring wheel measures the moving distance of the borehole radar, and outputs a trigger pulse through photoelectric conversion, and drives the signal transmission and collection work of the antenna at every set distance, including: When the high-frequency omnidirectional transmitting antenna and the high-frequency directional receiving antenna array are working, the high-frequency omnidirectional transmitting antenna emits directional electromagnetic waves along the radial direction of the borehole according to the sampling trigger pulse output by the signal control module, and the high-frequency directional receiving antenna array receives the electromagnetic wave signals reflected back by the reflector to obtain multiple sets of high-frequency data.

5. The method for controlling a multi-frequency borehole radar device according to claim 1, characterized in that: When the borehole radar is working, the angle correction module records the angular displacement of the borehole radar according to the working mode of the borehole radar, including: When the borehole radar adopts the time trigger mode or the distance trigger mode, when collecting low-frequency data and high-frequency data, the angle correction module records the angular displacement data during measurement according to the sampling trigger pulse output by the signal control module.

6. A multi-frequency borehole radar device, characterized in that: A multi-frequency borehole radar device control method according to any one of claims 1 to 5, comprising: a low-frequency omnidirectional antenna, a high-frequency omnidirectional transmitting antenna, a high-frequency directional receiving antenna array, a radar host and a ranging wheel; The low-frequency omnidirectional antenna, high-frequency omnidirectional transmitting antenna, high-frequency directional receiving antenna array and ranging wheel are respectively connected to the radar host; Wherein, the low-frequency omnidirectional antenna is used to transmit and receive low-frequency omnidirectional electromagnetic waves; The high-frequency omnidirectional transmitting antenna is used to transmit high-frequency omnidirectional electromagnetic waves. The high-frequency directional receiving antenna array is used to receive the reflected high-frequency directional electromagnetic waves; the high-frequency directional receiving antenna array is composed of a plurality of high-frequency directional receiving antennas facing different directions; The radar host is used for data collection and storage of the borehole radar; The distance measuring wheel is used to measure the distance traveled by the drilling radar in the hole to provide a distance trigger mode.

7. The multi-frequency borehole radar device according to claim 6, characterized in that: The radar host comprises a signal control module, an angle correction module, a storage module and a power supply module; The signal control module, angle correction module and power supply module are respectively connected to the storage module; The signal control module is used to control the transmission and reception of electromagnetic waves of the low-frequency omnidirectional antenna, the high-frequency omnidirectional transmitting antenna and the high-frequency receiving directional antenna; The angle correction module is used to record the angular displacement generated by the borehole radar while collecting data; The storage module is used to store the collected low-frequency data and high-frequency data; The power supply module is used to provide power supply.

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