Coal mine underground while-drilling forepoling geological radar detection method and device

Abstract

The invention relates to a coal mine underground while-drilling forepoling geological radar detection method and device, and the device comprises a while-drilling geological radar instrument, one end of the while-drilling geological radar instrument is connected with a drill bit through a metal drill rod, and the other end of the while-drilling geological radar instrument is connected with an in-hole communication device; the device further comprises a hole depth recorder installed on the drilling machine, and the hole depth recorder is connected with an orifice monitor. The while-drilling geological radar instrument comprises a transmitting antenna, a receiving antenna and an in-hole control device, and the in-hole control device is connected with the in-hole communication device. In the coal mine underground drilling process, the geological conditions in front of a drill bit and around a drill hole can be finely detected, detected data are transmitted to a hole opening in real time, the hole opening judges the geological conditions around the drill hole and in front of the drill bit according to the data detected by an instrument in the hole, a geological model is updated, the drill bit is adjusted, and the drill hole moves forwards along a target; and technical support is provided for underground coal mine rapid directional drilling.

Description

Technical Field

[0001] This application relates to the field of radar detection, and specifically, to a method and device for detecting geological radar while drilling in underground coal mines for forward exploration. Background Art

[0002] With the development of intelligent coal mining, the development of gas control and water hazard control in coal mines from qualitative to quantitative, and the demand for forward detection of the mining face, etc., put forward detection requirements of high detection accuracy and long detection distance for geophysical exploration. Currently, for the safe coal mining, in order to prevent water hazard accidents and gas disasters in underground coal mines, underground coal mine drilling is an effective means to solve this problem. In order to make the drill hole drill along the set trajectory, the directional drilling technology has been developed. However, the directional drilling technology can only ensure drilling along the set trajectory. When designing the drill hole trajectory in the early stage, it is designed according to the previous exploration data, and some small changes and small structures in the strata cannot be reflected in the previous exploration. Therefore, the directional drilling technology cannot perform real-time forward detection, update the geological model, adjust the designed trajectory and the drilling trajectory.

[0003] The geological steering drilling (well) technology is a drilling (well) technology that identifies the geological environment of the drilled strata and forecasts the underground conditions to be encountered according to the real-time geological information and directional data provided by the downhole (in the drill hole) instruments during drilling, guides the drill bit into the target layer and ensures that the drill hole trajectory extends along the target layer. It is a comprehensive technology of geological information, downhole instrument response and used to guide the drill bit into the target layer and within the target layer, and provides data for updating the geological model of the entire area according to the information detected while drilling. The traditional geological steering drilling (well) uses logging-while-drilling instruments such as natural gamma and resistivity to measure the physical property differences of the strata to ensure that the drill bit drills in the target layer. However, when the target layer is relatively thick, it cannot ensure advancing within a certain range from the interface. For example, in the horizontal wells on the ground for coalbed methane, in order to ensure the effect of gas extraction in the broken soft coal seams, horizontal wells are arranged along the development direction of the coal seam on the coal seam roof. The horizontal wells require to be within 2 m from the coal seam. Due to the relatively large thickness of the roof and the small physical property differences of the rock strata in the roof, the traditional logging technology for geological steering cannot control the drill hole within 2 m from the coal seam interface. Summary of the Invention

[0004] To overcome at least one deficiency in the prior art, this application provides a method and device for detecting geological radar while drilling in underground coal mines for forward exploration.

[0005] In a first aspect, there is provided a method for processing radar detection data in front of a drill hole, including:

[0006] Obtain the radar detection data in front of the drill hole. The radar detection data in front of the drill hole includes radar detection data at multiple depths. Perform continuous wavelet transform on the radar detection data at each depth based on different main frequencies to obtain the transformed radar detection data corresponding to different main frequencies at each depth.

[0007] Obtain the radar simulation data at multiple depths through numerical simulation. Perform continuous wavelet transform on the radar simulation data at each depth based on different main frequencies to obtain the transformed radar simulation data corresponding to different main frequencies at each depth.

[0008] According to the transformed radar detection data corresponding to different main frequencies at each depth, determine the radar detection data set composed of the transformed radar detection data corresponding to each depth at each main frequency. According to the transformed radar simulation data corresponding to different main frequencies at each depth, determine the radar simulation data set composed of the transformed radar simulation data corresponding to each depth at each main frequency.

[0009] Calculate the structural similarity index between the radar detection data set and the radar simulation data set at each main frequency. According to the structural similarity index at each main frequency, determine the correlation between the radar detection data and the radar simulation data.

[0010] Determine whether to adjust the drilling direction of the drill bit according to the correlation.

[0011] In one embodiment, performing continuous wavelet transform on the radar detection data at each depth based on different main frequencies to obtain the transformed radar detection data corresponding to different main frequencies at each depth includes:

[0012] Find the average value of the radar detection data at all depths as the average detection data.

[0013] Perform Fourier transform on the average detection data to obtain the frequency spectrum. Determine the extreme points of the frequency spectrum and extract the frequency corresponding to each extreme point as the main frequency.

[0014] Set the cosine signals corresponding to each main frequency and perform continuous wavelet transform on the radar detection data at each depth based on the cosine signals to obtain the transformed radar detection data corresponding to different main frequencies at each depth.

[0015] In one embodiment, calculating the structural similarity index between the radar detection data set and the radar simulation data set at each main frequency includes:

[0016] For the j-th main frequency, normalize the radar detection data set W j and the radar simulation data set W1 j to obtain the normalized radar detection data set x and the normalized radar simulation data set y.

[0017] Calculate the mean value μ of x x and the standard deviation σ x ; calculate the mean value μ of y y and the standard deviation σ y ; calculate the covariance of x and Y;

[0018] Calculate the structural similarity index using the following formula:

[0019]

[0020] where SSIM j is the structural similarity index between the radar detection data set and the radar simulation data set at the j-th main frequency, and C1, C2, and C3 are constants.

[0021] In one embodiment, determine the correlation between the radar detection data and the radar simulation data according to the structural similarity indices at each main frequency, using the following formula:

[0022]

[0023] where F is the correlation between the radar detection data and the radar simulation data, J is the number of main frequencies, ε j is the weight coefficient of the j-th main frequency, and SSIM j is the structural similarity index between the radar detection data set and the radar simulation data set at the j-th main frequency.

[0024] In one embodiment, determine whether to adjust the drilling direction of the drill bit according to the correlation, including:

[0025] If the correlation is less than the set value, then it is necessary to adjust the drilling direction of the drill bit; otherwise, it is not necessary to adjust the drilling direction of the drill bit.

[0026] In a second aspect, there is provided a downhole geological radar detection device for advancing exploration while drilling in a coal mine, including: a geological radar while drilling, one end of the geological radar while drilling is connected to a drill bit through a metal drill pipe, and the other end is connected to an in-hole communication device; the device further includes a hole depth recorder installed on the drilling rig, and the hole depth recorder is connected to a hole mouth monitor;

[0027] The geological radar while drilling includes a transmitting antenna, a receiving antenna, and an in-hole control device, and the in-hole control device is connected to the in-hole communication device;

[0028] During the drilling process, the hole mouth monitor issues a signal sending command, which is transmitted to the downhole control device through the downhole communication device. The downhole control device controls the transmitting antenna to emit a signal towards the bottom of the hole, and obtains the radar detection data in front of the drill hole through the receiving antenna. The hole mouth monitor issues a command to upload data, which is transmitted to the downhole control device through the downhole communication device. The downhole control device uploads the radar detection data in front of the drill hole to the hole mouth monitor through the downhole communication device;

[0029] The hole mouth monitor processes the radar detection data in front of the drill hole to determine whether it is necessary to adjust the drilling direction of the drill bit.

[0030] In one embodiment, after the transmitting antenna and the receiving antenna are connected by a non-metallic connecting piece, they are placed inside a non-metallic outer tube;

[0031] The transmitting antenna and the receiving antenna have the same structure. The transmitting antenna includes a non-metallic tube, and a plurality of metal copper rings or copper foils are sleeved or wound on the non-metallic tube, and adjacent metal copper rings or copper foils are connected by resistance components.

[0032] In one embodiment, the downhole control device is placed in a metal outer tube and is connected to the receiving antenna by a non-metallic female buckle; there is no conduction between the metal copper rings or copper foils inside the receiving antenna and the metal outer tube.

[0033] In one embodiment, the metal copper ring or copper foil at the front end of the transmitting antenna is connected and conducted to the metal drill pipe through a metal male buckle.

[0034] In one embodiment, the hole mouth monitor processes the radar detection data in front of the drill hole to determine whether it is necessary to adjust the drilling direction of the drill bit, which is based on the above-mentioned method for processing radar detection data in front of the drill hole.

[0035] In a third aspect, a method for detecting geological radar while drilling in coal mines is provided, including:

[0036] Step 1, start drilling according to the designed drilling trajectory. After the drilling depth is greater than 10m, lift the drill string to the hole mouth;

[0037] Step 2, install the geological radar detection device for detecting while drilling in coal mines, including: installing the hole depth recorder on the drilling rig; connecting the metal drill pipe to the drill bit, then connecting the geological radar while drilling to the metal drill pipe, then connecting the downhole communication device to the geological radar while drilling, and then connecting the metal drill pipe to the downhole communication device; sending the downhole equipment of the geological radar detection device for detecting while drilling in coal mines into the hole drilled in Step 1;

[0038] Step 3: Connect the orifice monitor to the depth recorder, turn on the orifice monitor, and test whether the entire system works properly. After testing that the entire system works properly, the orifice monitor synchronizes the depth recorder and the GPR while drilling, and issues the setting parameters of the depth recorder and the GPR while drilling. The orifice monitor, the GPR while drilling, and the depth recorder start working according to the drilling mode.

[0039] Step 4: Continue normal drilling. During the gap when adding drill pipes, the orifice monitor communicates with the downhole communication device. The orifice monitor issues a command to upload data, which is transmitted to the downhole control device through the downhole communication device. The downhole control device uploads the radar detection data in front of the drill hole to the orifice monitor through the downhole communication device.

[0040] Step 5: The orifice monitor processes the obtained radar detection data in front of the drill hole to determine whether it is necessary to adjust the drilling direction of the drill bit. Return to Step 4 until the drilling is completed, and then lift the drill. The data processing is based on the above-mentioned method for processing radar detection data in front of the drill hole.

[0041] Compared with the prior art, the present application has the following beneficial effects:

[0042] 1. It saves detection time, obtains detection information in real time during drilling, and the detection does not affect the drilling construction in coal mines. Moreover, through real-time detection, it can guide drilling, improve the drilling efficiency, and make the drilling process in coal mines better serve the drilling target.

[0043] 2. The GPR antenna while drilling has a wide range of selectable frequencies. The antenna frequency distribution ranges from 50 MHz to 500 MHz (one antenna every 50 MHz), and the highest resolution can reach 0.15 m, with high detection accuracy. Different GPR antennas while drilling can be selected according to different geological conditions. For drilling detection targets with a relatively thin target layer and a geological anomaly close to the drill hole, an antenna with a high center frequency is selected. For drilling detection targets with a thick target layer and a designed drill hole far from the geological anomaly, an antenna with a low center frequency is selected. The present application can not only meet the requirement of high detection accuracy but also meet the requirement of a large detection radius, and can provide powerful geological information for the intelligent mining in coal mines.

[0044] 3. The drilling conditions in coal mines are not restricted, and it is suitable for various drilling methods such as air drilling and water drilling. The communication method between the downhole instrument and the orifice can be selected according to the actual drilling method, and electromagnetic wave wireless communication, pulsed wireless communication, or wired communication through a drill pipe with a cable can be selected.

[0045] 4. It can be applied to any type of drilling rig. When encountering borehole collapse, it can adopt the rotary drilling method for feed drilling. After the measurement is completed and the well is lifted, the ground personnel can understand the downhole measurement process and the status during the entire measurement process based on the recorded information, which is convenient for subsequent fine data processing and interpretation. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] This application can be better understood by referring to the description given below in conjunction with the accompanying drawings. The drawings, together with the following detailed description, are included in this specification and form a part of this specification. In the drawings:

[0047] Figure 1 shows the structural schematic diagram of the downhole geological radar detection device while drilling in coal mines;

[0048] Figure 2 shows the detailed schematic diagram of the transmitting antenna and the receiving antenna;

[0049] Figure 3 shows the flow block diagram of the radar detection data processing method in front of the borehole.

[0050] Reference Signs:

[0051] 1 - Geosteering radar while drilling, 2 - In-hole communication device, 3 - Metal drill pipe, 4 - Hole depth recorder, 5 - Hole mouth monitor, 6 - Drilling rig, 7 - Borehole to be measured, 8 - Drill bit, 9 - Surrounding rock, 10 - Tunnel; 11 - Transmitting antenna, 12 - Receiving antenna, 13 - In-hole control device; 14 - Non-metallic connecting piece, 15 - Non-metallic outer pipe, 16 - Non-metallic pipe, 17 - Resistor component; 18 - Metal outer pipe, 19 - Non-metallic female thread, 20 - Metal male thread, 21 - Metal copper ring. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0052] Hereinafter, the exemplary embodiments of this application will be described in conjunction with the accompanying drawings. For the sake of clarity and conciseness, not all features of the actual embodiments are described in the specification. However, it should be understood that many embodiment-specific decisions may be made during the development of any such actual embodiment in order to achieve the specific goals of the developer, and these decisions may vary with different embodiments.

[0053] Here, it should also be noted that in order to avoid obscuring this application with unnecessary details, only the device structures closely related to the solution of this application are shown in the drawings, while other details less related to this application are omitted.

[0054] It should be understood that the present application is not limited to the described embodiments only due to the following description with reference to the accompanying drawings. In this text, where feasible, embodiments can be combined with each other, features can be replaced or borrowed between different embodiments, and one or more features can be omitted in one embodiment.

[0055] An embodiment of the present application provides a downhole geologic radar detection device for drilling Figure 1 The structural schematic diagram of the downhole geologic radar detection device for drilling is shown. Refer to Figure 1 , the device includes a downhole geologic radar 1. One end of the downhole geologic radar 1 is connected to the drill bit through a metal drill pipe 3, and the other end is connected to an in-hole communication device 2; the device also includes a hole depth recorder 4 installed on the drill rig 6, and the hole depth recorder 4 is connected to a hole mouth monitor 5;

[0056] The downhole geologic radar 1 includes a transmitting antenna 11, a receiving antenna 12, and an in-hole control device 13, and the in-hole control device 13 is connected to the in-hole communication device 2;

[0057] During the drilling process, the hole mouth monitor 5 issues a signal sending command, which is transmitted to the in-hole control device 13 through the in-hole communication device 2. The in-hole control device 13 controls the transmitting antenna 11 to emit a signal to the bottom of the hole, and obtains radar detection data in front of the drill hole through the receiving antenna 12; the hole mouth monitor 5 issues a command to upload data, which is transmitted to the in-hole control device 13 through the in-hole communication device 2. The in-hole control device 13 uploads the radar detection data in front of the drill hole to the hole mouth monitor 5 through the in-hole communication device 2;

[0058] The hole mouth monitor 5 processes the radar detection data in front of the drill hole to determine whether it is necessary to adjust the drilling direction of the drill bit. The specific data processing process is based on the data processing method in the subsequent embodiments.

[0059] In this embodiment, for the connection section between the downhole drilling radar and the drill bit, the connection of the metal drill pipe is adopted, which can avoid the damage of the non-metal shell of the downhole radar caused by the huge torsion during the drilling of the drill bit. At the same time, the transmitting antenna of the downhole drilling radar is connected to the metal drill pipe, and the metal drill pipe can be used as an extended amplification section of the transmitting antenna to form a guided wave on the metal drill pipe. During the working process of the downhole drilling radar, the detection end is closer to the drill bit, the detection effect is better, which is more conducive to guiding the drilling and avoiding the detection lag caused by the gap between the downhole drilling radar and the drill bit.

[0060] Specifically, Figure 2 The detailed schematic diagram of the transmitting antenna and the receiving antenna is shown. Refer to Figure 2 , after the transmitting antenna 11 and the receiving antenna 12 are connected through a non-metal connecting piece 14, they are placed in a non-metal outer pipe 15;

[0061] The structures of the transmitting antenna 11 and the receiving antenna 12 are the same. The transmitting antenna 11 includes a non-metallic tube 16, on which a plurality of metal copper rings 21 or copper foils are sleeved or wound, and adjacent metal copper rings 21 or copper foils are connected by a resistance component 17.

[0062] Specifically, referring to Figure 2 , the in-hole control device 13 is placed in the metal outer tube 18 and is connected to the receiving antenna 12 through a non-metallic female buckle 19; there is no electrical connection between the metal copper rings or copper foils inside the receiving antenna 12 and the metal outer tube 18.

[0063] Specifically, referring to Figure 2 , the metal copper ring or copper foil at the front end of the transmitting antenna 11 is electrically connected to the metal drill pipe 3 through a metal male buckle 20.

[0064] The embodiment of the present application also provides a method for processing radar detection data in front of a borehole, which is applied to a hole mouth monitor. Figure 3 shows a flowchart of the method for processing radar detection data in front of a borehole. Referring to Figure 3 , the method mainly includes the following steps:

[0065] Step S31, obtaining radar detection data in front of the borehole. The radar detection data in front of the borehole includes radar detection data at multiple depths; performing continuous wavelet transform on the radar detection data at each depth based on different main frequencies to obtain the transformed radar detection data corresponding to different main frequencies at each depth.

[0066] Specifically, calculating the average value of the radar detection data at all depths as the average detection data;

[0067] Performing Fourier transform on the average detection data to obtain a frequency spectrum; determining the extreme points of the frequency spectrum and extracting the frequency corresponding to each extreme point as the main frequency;

[0068] Setting the cosine signal s(f j ,l), where f j represents the jth main frequency and l represents the signal time length; performing continuous wavelet transform on the radar detection data at each depth based on the cosine signal to obtain the transformed radar detection data corresponding to different main frequencies at each depth.

[0069] Step S32, obtaining radar simulation data at multiple depths through numerical simulation; performing continuous wavelet transform on the radar simulation data at each depth based on different main frequencies to obtain the transformed radar simulation data corresponding to different main frequencies at each depth.

[0070] Here, the geological exploration information in the early stage is collected, a basic geological model with stratigraphic interfaces is constructed, and numerical simulation analysis of borehole ground penetrating radar is carried out. Two kinds of simulated antennas are established, namely, the transmitting antenna is separated from the front drill tool and the transmitting antenna is not separated from the front drill tool, and the radar simulation data under the current borehole trajectory change is obtained.

[0071] Step S33: According to the transformed radar detection data corresponding to different main frequencies at each depth, determine the radar detection data set composed of the transformed radar detection data corresponding to each depth at each main frequency; according to the transformed radar simulation data corresponding to different main frequencies at each depth, determine the radar simulation data set composed of the transformed radar simulation data corresponding to each depth at each main frequency.

[0072] Step S34: Calculate the structural similarity index between the radar detection data set and the radar simulation data set at each main frequency; according to the structural similarity index at each main frequency, determine the correlation between the radar detection data and the radar simulation data.

[0073] Specifically, for the j-th main frequency, for the radar detection data set W j and the radar simulation data set W1 j perform normalization processing to obtain the normalized radar detection data set x and the normalized radar simulation data set y;

[0074] Calculate the mean μ x and standard deviation σ x of x, calculate the mean μ y and standard deviation σ y of y, and calculate the covariance of x and Y;

[0075] Calculate the structural similarity index using the following formula:

[0076]

[0077] where SSIM j is the structural similarity index between the radar detection data set and the radar simulation data set at the j-th main frequency, and C1, C2, and C3 are constants to prevent the denominator from being zero, which can be determined according to the actual data.

[0078] The range of SSIM is [0, 1]. When SSIM = 0, it means that the actual measurement is completely dissimilar to the simulation. When SSIM = 1, it means that the actual measurement is exactly the same as the simulation.

[0079] Specifically, among them, according to the structural similarity index at each main frequency, determine the correlation between the radar detection data and the radar simulation data using the following formula:

[0080]

[0081] Among them, F is the correlation between the radar detection data and the radar simulation data, J is the number of main frequencies, and ε j is the weight coefficient of the j-th main frequency, and SSIM j is the structural similarity index between the radar detection data set and the radar simulation data set at the j-th main frequency.

[0082]

[0083] Among them, α j is the initial weight coefficient of the j-th main frequency, which is determined according to the data characteristics of different scales during the wavelet transform of the actual data.

[0084] Step S35, determine whether to adjust the drilling direction of the drill bit according to the correlation.

[0085] Specifically, if the correlation is less than the set value, the drilling direction of the drill bit needs to be adjusted; otherwise, the drilling direction of the drill bit does not need to be adjusted. Here, the set value is determined according to the actual formation and the actual instrument, and it should be noted that the set value is less than 1.

[0086] The embodiment of the present application also provides a method for detecting the geological radar while drilling in a coal mine underground, which mainly includes:

[0087] Step 1, start drilling according to the designed borehole trajectory. After the drilling depth is greater than 10m, lift the drill string to the hole mouth;

[0088] Step 2, install the geological radar detection device for detecting while drilling in a coal mine underground, including: installing the hole depth recorder on the drilling rig; connecting the metal drill pipe to the drill bit, then connecting the downhole geological radar to the metal drill pipe, then connecting the in-hole communication device to the downhole geological radar, and then connecting the metal drill pipe to the in-hole communication device; sending the in-hole equipment of the geological radar detection device for detecting while drilling in a coal mine underground into the hole drilled in Step 1;

[0089] Step 3, connect the hole mouth monitor to the depth recorder, turn on the hole mouth monitor, and test whether the whole system works normally; after testing that the whole system works normally, the hole mouth monitor synchronizes the depth recorder and the downhole geological radar, sends down the setting parameters of the depth recorder and the downhole geological radar, and the hole mouth monitor, the downhole geological radar, and the depth recorder start to work according to the drilling mode;

[0090] Step 4, continue normal drilling. During the gap of adding drill pipes, the hole mouth monitor communicates with the in-hole communication device, the hole mouth monitor sends down the command to upload data, which is transmitted to the in-hole control device through the in-hole communication device, and the in-hole control device uploads the radar detection data in front of the drill hole to the hole mouth monitor through the in-hole communication device;

[0091] Step 5: The orifice monitor processes the radar detection data in front of the drill hole obtained, and determines whether it is necessary to adjust the drilling direction of the drill bit; return to Step 4 until the drilling is completed, and then lift the drill; the data processing is based on the radar detection data processing method in front of the drill hole described in the foregoing embodiment.

[0092] In summary, the present application has the following technical effects:

[0093] 1. It saves detection time, obtains detection information in real time during the drilling process, and the detection does not affect the drilling construction in the coal mine underground. Moreover, through real-time detection, it can guide the drilling, improve the drilling efficiency, and enable the drilling process in the coal mine underground to better serve the drilling target.

[0094] 2. The frequency of the downhole radar antenna for drilling is wide for selection. The antenna frequency distribution ranges from 50 MHz to 500 MHz (one antenna at an interval of 50 MHz), and the highest resolution can reach 0.15 m. The detection accuracy is high. Different downhole radar antennas for drilling can be selected according to different geological conditions. For the drilling detection targets with a relatively thin target layer and a geological anomaly body close to the drill hole, an antenna with a high center frequency is selected. For the drilling detection targets with a large thickness of the target layer and a relatively long designed drill hole distance from the geological anomaly body, an antenna with a low center frequency is selected. The present application can not only meet the requirement of high detection accuracy but also meet the requirement of a large detection radius, and can provide powerful geological information for the intelligent mining in the coal mine underground.

[0095] 3. The drilling conditions in the coal mine underground are not restricted, and it is suitable for various drilling methods such as air drilling and water drilling. The communication method between the instrument in the drill hole and the orifice can be selected according to the actual drilling method, and electromagnetic wave wireless communication method, pulse wireless communication method, and wired communication method through a cable drill pipe can be selected.

[0096] 4. It can be applied to any type of drilling rig. And when the drill hole collapses, the rotation drilling method can be adopted to feed the drill. After the measurement is completed and the rig is lifted out of the well, the ground personnel can understand the underground measurement process and the status during the entire measurement process according to the recorded information, which is convenient for subsequent refined data processing and interpretation.

[0097] The above are only various implementation manners of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for processing radar detection data in front of a drill hole, characterized in that Including: Obtain radar detection data in front of the drill hole, where the radar detection data in front of the drill hole includes radar detection data at multiple depths; Perform continuous wavelet transform on the radar detection data at each depth based on different main frequencies to obtain the transformed radar detection data corresponding to different main frequencies at each depth; Obtain radar simulation data at multiple depths through numerical simulation; perform continuous wavelet transform on the radar simulation data at each depth based on different main frequencies to obtain the transformed radar simulation data corresponding to different main frequencies at each depth; According to the transformed radar detection data corresponding to different main frequencies at each depth, determine a radar detection data set composed of the transformed radar detection data corresponding to each depth at each main frequency; according to the transformed radar simulation data corresponding to different main frequencies at each depth, determine a radar simulation data set composed of the transformed radar simulation data corresponding to each depth at each main frequency; Calculate the structural similarity index between the radar detection data set and the radar simulation data set at each main frequency; determine the correlation between the radar detection data and the radar simulation data according to the structural similarity index at each main frequency; Determine whether to adjust the drilling direction of the drill bit according to the correlation.

2. The method according to claim 1, characterized in that, Wherein, Performing continuous wavelet transform on the radar detection data at each depth based on different main frequencies to obtain the transformed radar detection data corresponding to different main frequencies at each depth includes: Find the average value of the radar detection data at all depths as the average detection data; Perform Fourier transform on the average detection data to obtain a frequency spectrum; determine the extreme points of the frequency spectrum and extract the frequency corresponding to each extreme point as the main frequency; Set cosine signals corresponding to each main frequency, and perform continuous wavelet transform on the radar detection data at each depth based on the cosine signals to obtain the transformed radar detection data corresponding to different main frequencies at each depth.

3. The method according to claim 1, wherein Wherein, Calculating the structural similarity index between the radar detection data set and the radar simulation data set at each main frequency includes: For the j-th main frequency, for the radar detection data set W j and the radar simulation data set W1 j perform normalization processing to obtain the normalized radar detection data set x and the normalized radar simulation data set y; Calculate the mean μ of x x and the standard deviation σ x ; calculate the mean μ of y y and the standard deviation σ y ; calculate the covariance of x and y Calculate the structural similarity index using the following formula: where SSIM j is the structural similarity index between the radar detection data set and the radar simulation data set at the j-th main frequency, and C1, C2, and C3 are constants.

4. The method according to claim 1, characterized in that Wherein, Determine the correlation between the radar detection data and the radar simulation data according to the structural similarity index at each main frequency using the following formula: Among them, F is the correlation between the radar detection data and the radar simulation data, J is the number of main frequencies, and ε j is the weight coefficient of the j-th main frequency, and SSIM j is the structural similarity index between the radar detection data set and the radar simulation data set at the j-th main frequency.

5. The method according to claim 1, characterized in that, Wherein, Determining whether to adjust the drilling direction of the drill bit according to the correlation includes: If the correlation is less than the set value, the drilling direction of the drill bit needs to be adjusted; otherwise, the drilling direction of the drill bit does not need to be adjusted.

6. A geological radar detection device for forward exploration while drilling in underground coal mines, characterized in that, Including: A downhole geological radar (1), one end of the downhole geological radar (1) is connected to a drill bit (8) through a metal drill pipe (3), and the other end is connected to an in-hole communication device (2); the device further includes a hole depth recorder (4) installed on a drilling rig (6), and the hole depth recorder (4) is connected to a hole mouth monitor (5); The downhole geological radar (1) includes a transmitting antenna (11), a receiving antenna (12) and an in-hole control device (13), and the in-hole control device (13) is connected to the in-hole communication device (2); During the drilling process, the hole mouth monitor (5) issues a signal sending command, which is transmitted to the downhole control device (13) through the downhole communication device (2). The downhole control device (13) controls the transmitting antenna (11) to emit a signal towards the bottom of the hole, and obtains radar detection data in front of the drill hole through the receiving antenna (12). The hole mouth monitor (5) issues a command to upload data, which is transmitted to the downhole control device (13) through the downhole communication device (2). The downhole control device (13) uploads the radar detection data in front of the drill hole to the hole mouth monitor (5) through the downhole communication device (2). The hole mouth monitor (5) processes the radar detection data in front of the drill hole to determine whether it is necessary to adjust the drilling direction of the drill bit (8).

7. The device according to claim 6, wherein, After the transmitting antenna (11) and the receiving antenna (12) are connected by a non-metallic connecting piece (14), they are placed inside a non-metallic outer tube (15). The structures of the transmitting antenna (11) and the receiving antenna (12) are the same. The transmitting antenna (11) includes a non-metallic tube (16), and a plurality of metal copper rings (21) or copper foils are sleeved or wound on the non-metallic tube (16). Adjacent metal copper rings (21) or copper foils are connected by resistance components (17).

8. The device according to claim 7, wherein The downhole control device (13) is placed in a metal outer tube (18) and is connected to the receiving antenna (12) through a non-metallic female buckle (19). There is no electrical connection between the metal copper rings or copper foils inside the receiving antenna (12) and the metal outer tube (18).

9. The device according to claim 7, characterized in that, The metal copper rings or copper foils at the front end of the transmitting antenna (11) are connected and electrically conducted to the metal drill pipe (3) through a metal male buckle (20).

10. The device according to claim 6, characterized in that, Among them, The method for processing radar detection data in front of the drill hole, where the hole mouth monitor (5) processes the radar detection data in front of the drill hole to determine whether it is necessary to adjust the drilling direction of the drill bit (8), is the method for processing radar detection data in front of the drill hole according to any one of claims 1-5.

11. A method for detecting geological radar while drilling ahead in underground coal mines, characterized in that, It includes: Step 1: Start drilling according to the designed drilling trajectory. After the drilling depth is greater than 10m, lift the drill tool to the hole mouth; Step 2: Install the downhole forward-looking geological radar detection device for coal mines, including installing a hole depth recorder on the drill rig; After connecting the metal drill pipe to the drill bit, then connect the downhole geological radar to the metal drill pipe, then connect the downhole communication device to the downhole geological radar, and then connect the metal drill pipe to the downhole communication device; Send the downhole equipment of the downhole forward-looking geological radar detection device for coal mines into the hole drilled in Step 1; Step 3: Connect the hole mouth monitor to the depth recorder, turn on the hole mouth monitor, and test whether the whole system works properly; After testing that the whole system works properly, the hole mouth monitor synchronizes the depth recorder and the downhole geological radar, issues the setting parameters of the depth recorder and the downhole geological radar, and the hole mouth monitor, the downhole geological radar, and the depth recorder start working according to the drilling mode; Step 4: Continue normal drilling. When adding drill pipes, the hole mouth monitor communicates with the in-hole communication device. The hole mouth monitor issues a command to upload data, which is transmitted to the in-hole control device through the in-hole communication device. The in-hole control device uploads the radar detection data in front of the drill hole to the hole mouth monitor through the in-hole communication device; Step 5: The hole mouth monitor processes the obtained radar detection data in front of the drill hole to determine whether it is necessary to adjust the drilling direction of the drill bit. Return to Step 4 until the drilling is completed, and then withdraw the drill; the data processing is performed according to the radar detection data processing method in front of the drill hole described in any one of claims 1 to 5.

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