Unfavorable geological exploration method based on inclined drilling

Abstract

The present invention provides a method for poor geological exploration based on inclined drilling, including: conducting on-site exploration of a target area containing protected underground structures; designing the inclination and azimuth of drilling; drilling according to the designed inclination and azimuth, measuring the top angle and azimuth of the borehole, and compiling borehole information; conducting in-hole geophysical exploration, obtaining geophysical cross-hole CT raw data; processing the geophysical cross-hole CT raw data, including extracting common shot point gathers, extracting the coordinates of the transmitting point and the receiving point, using a neural network to pick up the first arrival time, establishing an initial velocity model, inverting the cross-hole seismic CT raw data, and obtaining an inclined borehole cross-hole seismic CT velocity profile; and delineating a poor geological area according to geophysical information and geological information. The present invention can significantly reduce exploration blind areas and realize continuous detection of geophysical profiles.

Description

Technical Field

[0001] The invention relates to the field of geological exploration in complex environments, and in particular to a method for exploring adverse geology based on inclined drilling. Background Art

[0002] Hidden bad geology may cause ground collapse, thus posing a major threat to the construction and operation of urban infrastructure such as tunnels, bridges, and highways. Conducting exploration of hidden bad geology can provide important geological information for urban planning and construction, evaluate the feasibility and risks of construction in specific areas, and ensure the safety of project site selection, design, and construction. With the advancement of urban modernization, the demand for subways and intercity railways is increasing, and higher requirements are also placed on exploration techniques and methods. It is difficult to carry out efficient and accurate exploration work in urban exploration restricted areas, such as highways, areas with dense buildings, and areas where major pipelines are laid. Traditional exploration methods often rely on drilling to obtain underground rock and soil information. In addition, geophysical exploration technology is also very important for the exploration of hidden bad geology, such as micro-seismic exploration, transient electromagnetic method, geological radar method, and high-density electrical method. However, there are strong electromagnetic interference, traffic noise interference, construction activities, and environmental noise in cities, which affect the accuracy of geophysical exploration methods to a certain extent. In addition, in areas with dense buildings such as highways, they are affected by site restrictions, and it is difficult for geophysical exploration technicians to arrange geophysical exploration lines and carry out geophysical exploration. Traditional vertical borehole geophysical exploration cannot be carried out due to site limitations. Even if drilling is carried out around the exploration restriction area, the accuracy will be affected to a certain extent. Therefore, it is urgent to study a survey method to conduct efficient and accurate exploration of hidden poor geological areas in urban exploration restriction areas. Summary of the invention

[0003] The present invention aims to propose an in-hole geophysical exploration method based on inclined drilling to conduct adverse geological exploration in urban exploration restricted areas, obtain underground lithology in restricted construction areas through inclined drilling, and carry out in-hole geophysical exploration. The geophysical exploration data is further processed, and combined with the existing drilling data, the concealed adverse geological areas are detected and delineated, thereby filling the geological data gap in urban exploration restricted areas to a large extent.

[0004] To this end, the present invention provides a method for unfavorable geological exploration based on inclined drilling, comprising the following steps:

[0005] S1. Conduct on-site exploration of the target area containing the protected underground structure;

[0006] S2. Design the inclination and azimuth of drilling according to the location of the protected underground structure;

[0007] S3. Drilling is performed according to the designed inclination and azimuth, and the top angle and azimuth of the borehole are measured, and the drilling information is recorded;

[0008] S4, perform in-hole geophysical exploration and obtain geophysical cross-hole CT raw data;

[0009] S5. Processing the geophysical cross-hole CT raw data, including extracting the common shot point gather, extracting the coordinates of the transmitting point and the receiving point, picking the first arrival time by using a neural network, establishing an initial velocity model, inverting the cross-hole seismic CT raw data, and obtaining the inclined borehole cross-hole seismic CT velocity profile;

[0010] S6. Delineate areas of adverse geology based on geophysical and geological information.

[0011] Further preferably, in S2, the designing of the inclination angle and azimuth of the drilling according to the location of the protected underground structure includes: using the following formula to calculate the maximum inclination angle when arranging the boreholes at the minimum distance: for:

[0012]

[0013] in, is the inclination angle, M2 is the ground distance where the borehole cannot be arranged, D1 is the maximum burial depth of the protected underground structure, and D2 is the designed burial depth of the tunnel vault.

[0014] Further preferably, in S4, obtaining geophysical cross-hole CT raw data includes using cross-hole seismic CT as the main method and tube wave detection and electromagnetic wave CT as the auxiliary method.

[0015] Further preferably, in S5, the extracting of the coordinates of the transmitting point and the receiving point adopts the following steps:

[0016] An observation coordinate system is established. When the observation coordinate system is established, the intersection of the launch hole and the ground is taken as the origin, the straight line where the launch hole is located is taken as the Z axis, and a plane coordinate system is established with the straight line perpendicular to the launch hole as the X axis;

[0017] Mark the coordinates of the transmitting hole and the receiving hole;

[0018] According to the angle θ with the straight line where the receiving hole is located 3 satisfy , establish auxiliary lines;

[0019] Among them, the inclination angle of the transmitting hole is θ 1 , the receiving hole inclination angle is θ 2 ;

[0020] Calculate the receiving hole coordinates according to the following formula:

[0021]

[0022]

[0023] Among them, θ 4 is the angle between the X axis and the ground, H R1’ Point R 1 ’ The distance between the transmitting hole and the receiving hole is D.

[0024] Further preferably, in S5, the picking up of the first arrival time by using a neural network includes establishing an inclined borehole cross-hole seismic CT sample data set, dividing it into a training set and a test set in a ratio of 4:1, building a U-net network structure, using amplitude balance and apparent velocity to establish constraint conditions for training, the input end is the reorganized inclined borehole cross-hole seismic CT data, and the output end is the first arrival time;

[0025] After the training is completed, the first arrival measured data is input into the U-net network model to obtain the first arrival time, check the first arrival results, and correct the unreasonable first arrival time; the corrected first arrival time and the extracted transmission and receiving point coordinates together constitute the inversion file.

[0026] Further preferably, in S5, establishing the initial velocity model includes:

[0027] The multi-level grid modeling is adopted, and the initial velocity model is set up by integrating the ray tracing results of the minimum travel time algorithm, the drilling information and the tube wave detection results.

[0028] Further preferably, the modeling using multi-level grid division includes: using dense grid (0.2m×0.2m) division for possible abnormal areas revealed by original geological and geophysical data, and using normal grid (1m×1m) division for normal velocity areas.

[0029] Further preferably, in S5, the cross-hole seismic CT raw data are inverted, including: using a least squares inversion algorithm to invert the cross-hole seismic CT raw data, calculating the fitting error in the inversion process, continuously improving the initial model in combination with the ray trajectory and then inverting, and finally obtaining the inclined borehole cross-hole seismic CT velocity profile.

[0030] The adverse geological exploration method based on inclined drilling provided by the present invention has at least the following advantages compared with the prior art:

[0031] This application uses the U-net network to obtain the first arrival time in a short time, check the first arrival results, correct unreasonable first arrivals, and ensure the efficiency and accuracy of the first arrival picking work.

[0032] This application solves the problem of hidden poor geological exploration in restricted areas of urban exploration. Compared with traditional exploration methods, it significantly reduces exploration blind areas and realizes continuous detection of geophysical profiles. The borehole inclination measurement ensures the accuracy of the borehole position, the coordinate extraction of the transmitting point and the receiving point and the intelligent picking of the first arrival ensure the efficient and accurate processing of the inclined borehole cross-hole seismic CT data. The borehole data and tube wave detection can more accurately delineate the hidden poor geological areas and provide more complete exploration data for subsequent design and construction.

[0033] When creating the initial inversion model, comprehensive reference is made to the borehole data, inclined borehole cross-hole seismic CT original data, and tube wave detection results to ensure the scientific nature of the initial model establishment and thus improve the efficiency and accuracy of the inversion. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A flow chart of the adverse geological exploration method based on inclined drilling provided by the present invention;

[0035] Figure 2 A schematic diagram of the inclined drilling arrangement provided by the present invention;

[0036] Figure 3 It is a comparison chart between the designed drilling inclination angle and the measured inclination angle;

[0037] Figure 4 This is a schematic diagram for comparing the coordinate extraction of vertical drilling and inclined drilling;

[0038] Figure 5 Schematic diagram of the process of picking the first arrival time for the U-net network;

[0039] Figure 6 This is a schematic diagram of the initial model mesh division;

[0040] Figure 7 This is a schematic diagram of cross-hole geophysical exploration in inclined drilling in the field;

[0041] Figure 8 This is the final result map obtained by the adverse geological exploration method based on inclined drilling in the present invention. DETAILED DESCRIPTION

[0042] The present invention is further described in detail below through the accompanying drawings and specific embodiments.

[0043] like Figure 1 As shown, an adverse geological exploration method based on inclined drilling provided by an embodiment of one aspect of the present invention comprises the following steps:

[0044] S1. Conduct on-site exploration of target areas containing protected underground structures; this includes comprehensive survey data and ground geophysical exploration to identify protected underground structures, such as underground pipelines, pile foundations, cables, etc., that exist underground in urban exploration restricted areas.

[0045] S2. Design the inclination and azimuth of drilling according to the location of the protected underground structure;

[0046] As attached Figure 2 As shown:

[0047] During the survey, it is necessary to find out the range where the borehole cannot be arranged on the ground and to clarify the area of ​​the protected underground structure. The ground distance where the borehole cannot be arranged is represented as M2 in the figure, the maximum burial depth of the protected underground structure is D1, the burial depth of the designed tunnel vault is D2, and the burial depth of the designed tunnel vault is D3. Under the premise of finding out whether there is unfavorable geology around the tunnel body, the minimum distance M1 between the layout of the borehole and the surface building should be:

[0048]

[0049] Furthermore, we have:

[0050]

[0051] The following formula is used to calculate the maximum inclination angle when arranging the drilling holes at the minimum distance: for:

[0052]

[0053] in, is the inclination angle, M2 is the ground distance where the borehole cannot be arranged, D1 is the maximum burial depth of the protected underground structure, and D2 is the designed burial depth of the tunnel vault.

[0054] Further,

[0055]

[0056] From M1 and The scope of drilling layout can be clearly defined, as shown in the attached Figure 2 As shown, its layout should be at least on the left side of the red line in the figure, and it is recommended to be appropriately far away to ensure construction safety.

[0057] S3. Drill according to the designed inclination and azimuth, measure the top angle and azimuth of the borehole, and compile the drilling information; Figure 3 As shown in the figure, there is a comparison between the designed drilling inclination and the measured inclination.

[0058] S4, conducting in-hole geophysical exploration and obtaining geophysical cross-hole CT raw data; in S4, obtaining geophysical cross-hole CT raw data includes mainly using cross-hole seismic CT, supplemented by tube wave detection and electromagnetic wave CT.

[0059] S5. Processing of geophysical cross-hole CT raw data, including:

[0060] Extract the common shot point gathers; this step arranges the superimposed gathers of each common shot point in order according to the shot interval size, that is, data reorganization.

[0061] Extract the coordinates of the transmitting point and the receiving point; on the one hand, the hole inclination and azimuth measured in step 2 can better calibrate the spatial position of the borehole, and on the other hand, accurately complete the coordinate extraction of the transmitting point and the receiving point;

[0062] The coordinates of the transmitting point and the receiving point are extracted as follows:

[0063] Attach Figure 4 For example, here we will compare the coordinate extraction method of the traditional straight hole and the inclined hole involved in the present invention:

[0064] The depth of the launch hole is H 1 , the receiving hole depth is H 2 , the hole spacing is D, the transmitting hole slope is θ 1 , the receiving hole is inclined as θ 2 ;

[0065] Traditional straight hole transmission point receiving point coordinate extraction method ( Figure 4 Left side of the figure):

[0066] The observation system is established as follows:

[0067] A plane coordinate system is established with the intersection of the launch hole and the ground as the origin, the straight line where the launch hole is located as the Z axis, and the straight line where the ground is located as the X axis.

[0068] Point T on the launch aperture 1 The coordinates should be: (0, H T1 ), H T1 Point T 1 Distance from the orifice;

[0069] Point R on the receiving hole 1 The coordinates should be: (D, H R1 ), H R1 Point R 1 Distance from the orifice

[0070] Coordinate extraction method of transmitting point and receiving point in inclined drilling ( Figure 4 (right side of the figure):

[0071] The observation system is established as follows:

[0072] A plane coordinate system is established with the intersection of the launch hole and the ground as the origin, the straight line where the launch hole is located as the Z axis, and the straight line perpendicular to the launch hole as the X axis.

[0073] Point T on the launch aperture 1 ’ The coordinates should be: (0, H T1’ ), H T1’ Point T 1 ’ Distance from the orifice;

[0074] Then the point R on the receiving hole 1 ’ Coordinate (X R1’ , Z R1’ )for:

[0075] Draw auxiliary lines, see Figure 4 The black dotted line in the right figure has a length of L, and the angle θ between the auxiliary line and the straight line where the receiving hole is located is 3 :

[0076]

[0077] Furthermore, we have:

[0078]

[0079]

[0080] Among them, θ 4 is the angle between the X axis and the ground, H R1’ Point R 1 ’ Distance from the orifice;

[0081] Furthermore, in terms of angle size relationship:

[0082]

[0083]

[0084] Furthermore, we have:

[0085]

[0086]

[0087] So point R 1 ’ The coordinates are ( , ) ; D is the hole spacing between the transmitting hole and the receiving hole.

[0088] A neural network is used to pick the first arrival time;

[0089] like Figure 5 As shown in the figure, an inclined borehole cross-hole seismic CT sample data set is established and divided into a training set and a test set in a ratio of 4:1. A U-net network structure is built for training with the aid of amplitude balance and apparent velocity constraints. The input end is the reorganized inclined borehole cross-hole seismic CT data, and the output end is the first arrival time. After the U-net network model training is completed, the measured data to be picked up for the first arrival is input into the U-net network model, so that the first arrival time can be obtained in a short time. The first arrival result is manually checked and the unreasonable first arrival is corrected. The corrected first arrival time and the extracted transmitting and receiving point coordinates together constitute the inversion file.

[0090] Establish initial velocity model;

[0091] like Figure 6 As shown in FIG. 1 , for the setting of the initial model, it is necessary to integrate the results of ray tracing by the minimum travel time algorithm, the borehole information and the tube wave detection results to complete the setting of the initial velocity model; the present invention adopts a multi-level grid partitioning modeling method, that is, a dense grid (0.2m×0.2m) is used for the possible abnormal area revealed by the original geological and geophysical data, and a normal grid (1m×1m) is used for the normal velocity area, so as to take into account both efficiency and accuracy. The schematic diagram of the grid partitioning is shown in the attached figure. Figure 6 .

[0092] Invert the cross-hole seismic CT raw data; use the least squares inversion algorithm to invert the cross-hole seismic CT raw data, calculate the fitting error during the inversion process, and continuously improve the initial model in combination with the ray trajectory before inversion;

[0093] Finally, the inclined borehole cross-hole seismic CT velocity profile is obtained as follows: Figure 8 In the figure, different colors represent the wave speeds at different positions, and the wave speed image spectrum has been shown in the figure.

[0094] S6. Delineate areas with unfavorable geology based on geophysical and geological information.

[0095] like Figure 7 As shown, it is a schematic diagram of field detection according to the above-mentioned inclined drilling cross-hole geophysical exploration method of the present invention. It should be noted that the movement of the transmitting point and the movement of the receiving point are performed alternately, that is, at the initial moment, the transmitting point transmits the detection signal at the initial position, and receives it at the corresponding receiving point. After the position of the transmitting point is moved according to the inclined drilling, the receiving point remains stationary and continues to receive at the original position, and then moves to the next receiving point to receive the detection signal.

[0096] The patent of this invention solves the problem of hidden poor geological exploration in restricted areas of urban exploration to a certain extent. Compared with traditional exploration methods, it significantly reduces exploration blind areas and realizes continuous detection of geophysical profiles. The borehole inclination measurement ensures the accuracy of the borehole position, the coordinate extraction of the transmitting point and the receiving point and the intelligent picking of the first arrival ensure the efficient and accurate processing of the inclined borehole cross-hole seismic CT data, and the multi-level grid division establishes the initial model to use the least squares method for inversion, and the initial model is continuously adjusted and optimized in combination with the ray trajectory during the inversion process, ensuring the efficiency and rationality of the conversion of geophysical data into results. Assisted by the borehole information and tube wave detection results, it can more accurately delineate the hidden poor geological areas and provide more complete exploration data for subsequent design and construction.

[0097] Obviously, the above embodiments are only examples for clear explanation, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from them are still within the protection scope of the invention.

Claims

1. A method for unfavorable geological exploration based on inclined drilling, characterized in that: The following steps are involved: S1. Conduct on-site exploration of the target area containing the protected underground structure; S2. Design the inclination and azimuth of drilling according to the location of the protected underground structure; S3. Drilling is performed according to the designed inclination and azimuth, and the top angle and azimuth of the borehole are measured, and the drilling information is recorded; S4, perform in-hole geophysical exploration and obtain geophysical cross-hole CT raw data; S5, processing the geophysical cross-hole CT raw data, including extracting common shot point gathers, extracting the coordinates of the launch point and the receiving point, picking up the first arrival time using a neural network, establishing an initial velocity model, inverting the cross-hole seismic CT raw data, and obtaining the inclined borehole cross-hole seismic CT velocity profile; the extraction of the launch point and the receiving point coordinates adopts the following steps: An observation coordinate system is established. When the observation coordinate system is established, the intersection of the launch hole and the ground is taken as the origin, the straight line where the launch hole is located is taken as the Z axis, and a plane coordinate system is established with the straight line perpendicular to the launch hole as the X axis; Mark the coordinates of the transmitting hole and the receiving hole; According to the angle θ3 with the straight line where the receiving hole is located, , establish auxiliary lines; Among them, the inclination angle of the transmitting hole is θ1, and the inclination angle of the receiving hole is θ2; Calculate the coordinates of the transmitting hole and the receiving hole according to the following formula: Among them, θ4 is the angle between the X axis and the ground, H R1’ Point R1 ’ Distance from the orifice; S6. Delineate areas with unfavorable geology based on geophysical and geological information.

2. The method for exploring adverse geological conditions based on inclined drilling according to claim 1, characterized in that: In S2, the design of the inclination and azimuth of the drilling according to the location of the protected underground structure includes: using the following formula to calculate the maximum inclination when arranging the boreholes at the minimum distance: for: in, is the inclination angle, M2 is the ground distance where the borehole cannot be arranged, D1 is the maximum burial depth of the protected underground structure, and D2 is the designed burial depth of the tunnel vault.

3. The method for exploring adverse geological conditions based on inclined drilling according to claim 1, characterized in that: In S4, the acquisition of geophysical cross-hole CT raw data includes mainly using cross-hole seismic CT, supplemented by tube wave detection and electromagnetic wave CT.

4. The method for exploring adverse geological conditions based on inclined drilling according to claim 1, characterized in that: In S5, the neural network is used to pick up the first arrival time, including establishing an inclined borehole cross-hole seismic CT sample data set, and dividing it into a training set and a test set in a ratio of 4:1, building a U-net network structure, using amplitude balance and apparent velocity to establish constraint conditions for training, the input end is the reorganized inclined borehole cross-hole seismic CT data, and the output end is the first arrival time; After the training is completed, the first arrival measured data is input into the U-net network model to obtain the first arrival time, check the first arrival results, and correct the unreasonable first arrival time; the corrected first arrival time and the extracted transmission and receiving point coordinates together constitute the inversion file.

5. The method for adverse geological exploration based on inclined drilling according to claim 1, characterized in that: In S5, establishing the initial velocity model includes: The multi-level grid modeling is adopted, and the initial velocity model is set up by integrating the ray tracing results of the minimum travel time algorithm, the drilling information and the tube wave detection results.

6. The method for exploring adverse geological conditions based on inclined drilling according to claim 1, characterized in that: The multi-level grid modeling includes: using dense grid 0.2m×0.2m for the possible abnormal area revealed by the original geological and geophysical data, and using normal grid 1m×1m for the normal velocity area.

7. The method for exploring adverse geological conditions based on inclined drilling according to claim 1, characterized in that: In S5, the cross-hole seismic CT raw data are inverted, including: The least squares inversion algorithm is used to invert the original cross-hole seismic CT data, and the fitting error in the inversion process is calculated. The initial model is continuously improved in combination with the ray trajectory and then inverted again, and finally the inclined borehole cross-hole seismic CT velocity profile is obtained.

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