Electric spark source multidirectional detection system and method based on polarization effect

Abstract

The invention discloses an electric spark source multidirectional detection system and method based on a polarization effect, the system comprises a source drill rod, a capacitance drill rod, a conductive drill rod and a console, discharge electrodes respectively correspond to excitation ports in different orientations, and three space orthogonal excitation ports are formed in this way for time-sharing excitation. Three pure transverse wave sources with known polarization directions are manufactured, so that the detection precision is improved for subsequent inversion analysis; obtaining a three-component seismic trace record data set corresponding to the three seismic sources; processing the data set to obtain three groups of azimuth data; thirdly, defining a model parameter vector and determining a full-waveform inversion function; according to the method, an adjoint state method is adopted to obtain a gradient direction enabling an objective function to descend, an L-BFGS algorithm is utilized to iteratively update model parameters, and finally, an optimal solution is utilized to be combined with three groups of azimuth data to carry out full-waveform inversion, so that azimuth anisotropy information of a detection area is obtained. And the accurate identification of the disaster geologic body in the detection target area is realized by fusing the multidirectional detection data.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of geophysical exploration, in particular to a multi-azimuth detection system and method of electric spark source based on polarization effect. BACKGROUND

[0002] Seismic exploration is a key technology in geology and geophysics for detecting underground structures. It infers the properties and structure of underground rock layers by generating seismic waves on the surface or underground and recording the propagation of these waves underground. Traditional seismic exploration methods usually rely on artificial seismic data excited by artificial sources such as ramming, explosives, etc. However, this method has some limitations, such as the influence of underground medium properties, the mixing of abnormal body characteristic signals, and low exploration accuracy. In order to overcome these limitations, borehole seismic exploration technology has emerged. Borehole seismic exploration can be excited in deep or remote areas away from the exploration surface, thereby obtaining more accurate reflection signals of abnormal media and providing more accurate local underground medium information. However, the exploration accuracy of this method has high requirements for the performance and position of the source. When drilling in the blind area of the deep stratum, the traditional source has obvious limitations, such as the inconvenience of detonating explosives inside the drill hole, the shallow and unsafe arrangement depth, and the narrow frequency band and low intensity of the mechanical source, resulting in shallow exploration depth. Currently, electric spark sources are also used for borehole exploration. This source has a wide frequency band and high intensity, making it have a higher exploration depth. However, the current electric spark source only has a single excitation direction, which results in the data obtained by the exploration not having azimuth anisotropy information, and the abnormal body cannot be analyzed in more detail.

[0003] Therefore, how to provide a new detection system and method that can obtain accurate geological conditions while ensuring the intensity and exploration depth of the source is the research direction of the present application. SUMMARY

[0004] In view of the problems existing in the prior art, the present application provides a multi-azimuth detection system and method of electric spark source based on polarization effect, which can perform multi-azimuth detection in the limited space of the drill hole while ensuring the intensity and exploration depth of the source, and obtain accurate geological conditions by fusing multi-azimuth detection data.

[0005] In order to achieve the above purpose, the technical scheme adopted by the present application is: a multi-azimuth detection system of electric spark source based on polarization effect, comprising a source drill rod, a capacitor drill rod, a conductive drill rod, and a control console; the source drill rod, the capacitor drill rod, and the conductive drill rod are coaxially connected in sequence and are located in a detection drill hole.

[0006] The source drill pipe is provided with a time device, an electronic gyroscope, an angle sensor, a battery and a plurality of discharge electrodes; the electronic gyroscope and the angle sensor are used for measuring the rotation angle and the inclination angle of the source drill pipe in the detection borehole in real time; the time device is used for synchronizing the electronic gyroscope and the angle sensor with the control console; three excitation openings are formed on the outer wall of the source drill pipe and face different directions, and each excitation opening is provided with an energy release shear piece; each discharge electrode faces one excitation opening and is used for exciting a directional electric spark source; and the battery supplies power for the time device, the electronic gyroscope and the angle sensor.

[0007] The capacitor drill pipe is provided with a high-voltage ceramic capacitor array which is connected with the discharge electrodes and is used for providing pulse current to the discharge electrodes.

[0008] The control console is located outside the borehole, and the control console adjusts the pulse current output by the high-voltage ceramic capacitor array through the cable in the conductive drill pipe, thereby controlling the directional electric spark source generated by each discharge electrode, and obtaining feedback data of the electronic gyroscope and the angle sensor, so as to realize directional excitation of seismic waves in different directions.

[0009] Further, the three excitation openings are a first excitation opening, a second excitation opening and a third excitation opening, wherein the first excitation opening and the second excitation opening each face a projection coaxial and opposite in the same cross section of the source drill pipe; the first excitation opening and the second excitation opening each face a projection perpendicular to the third excitation opening in the same cross section of the source drill pipe. In this way, three spatially orthogonal excitation openings are formed in the detection borehole, three polarized direction known and pure shear wave sources are manufactured, and the seismic wave polarization characteristics are used to complete the analytical detection of the detection target.

[0010] Further, the source drill pipe, the capacitor drill pipe and the conductive drill pipe are connected with each other through a conductive slip ring. In this way, the transmission of electrical signals in each borehole is ensured.

[0011] Further, the high-voltage ceramic capacitor array is fixed in the capacitor drill pipe through an anti-vibration insulation frame. In this way, the stability of the high-voltage ceramic capacitor array during the drilling process of the drill pipe is ensured, and normal work is facilitated during subsequent detection.

[0012] Further, the control console comprises a voltage regulator, a step-up transformer, a rectifier, a control display, an electronic gyroscope II, a GPS module, a time synchronization module, and a time delay generator; the electronic gyroscope II and the GPS module are used to obtain the pose of the control console; the time synchronization module is used to synchronize with a time synchronization device; the voltage regulator, the step-up transformer, and the rectifier cooperate with each other to regulate the pulse current output by the array of high-voltage ceramic capacitors; the control display is used to control the sequence of the pulse current output by each discharge electrode; and the data fed back by the electronic gyroscope I and the inclination sensor are obtained to determine the orientation of each discharge electrode in the detection borehole; and the time delay generator is used to control the discharge electrodes to be sequentially excited in time sequence.

[0013] Further, the energy release shear piece is made of amorphous alloy material. The material is a current material, which can resist the hydrostatic pressure of the drill rod extending into the deep stratum and be broken down under the excitation of the electric pulse of the discharge electrode, so as to generate a directional electric spark source in the borehole.

[0014] The detection method of the electric spark source multi-directional detection system based on the polarization effect comprises the following steps: Step one: based on the geological conditions of the target area to be detected, a seismic detector borehole is constructed and the construction path of the detection borehole is determined, and after completion, a plurality of seismic detectors are arranged in the borehole along the borehole direction to form a seismic observation system.

[0015] Step two: first, the internal components of the source drill rod and the control console are turned on, and the time synchronization device and the time synchronization module are connected through the connecting line to synchronize, and the electronic gyroscope I, the inclination sensor, the electronic gyroscope II, and the GPS module are used to obtain the pose information of the current source drill rod and the control console, and the source local coordinate system and the geodetic coordinate system are constructed for the source drill rod and the control console respectively, and the source drill rod coordinate system is transformed to the geodetic coordinate system through coordinate change.

[0016] Step three: disconnect the source drill rod and the control console, then connect the source drill rod, the capacitor drill rod, and the conductive drill rod in sequence, and drive the drill to rotate according to the construction path determined in step one, drill into the detection borehole, stop when drilling to the designed depth, and the electronic gyroscope I and the inclination sensor record the rotation angle and inclination information of the current source drill rod, and the control console is reconnected with the electronic gyroscope I and the inclination sensor to obtain the corresponding data, and after calculation, the orientation of each excitation port is determined.

[0017] Step four: the control console sends trigger instructions to the three discharge electrodes in a preset time sequence; each discharge electrode instantaneously releases a high-voltage pulse in the drilling fluid after receiving the instruction, generates a plasma channel, and forms a directional shock wave; at the same time, the seismic observation system is started to observe and record three sets of independent three-component seismic trace record data sets excited in three different directions in sequence.

[0018] Step five, the console carries out inversion analysis on the observation record seismic trace data set, and extracts the azimuth anisotropy information of the detection area by comparing the travel time, amplitude, spectrum and polarization state of the reflection / scattering signals in the three groups of data, so as to realize the identification of the disaster geological body in the detection target area.

[0019] Further, the step five is specifically: S1, obtaining the relationship between the geodetic coordinate system and the local coordinate system of the source, determining the position information of the three different direction excitation sources in the geodetic coordinate system according to the orientation of each excitation port; and further determining the source expression: wherein is the excitation times, is the force function, is the source position, is the Dirac function; is the source orientation of the alpha-th excitation, alpha = 1, 2, 3.

[0020] S2, under the excitation of a point source, the displacement field solution is obtained by means of the Green tensor of elastic dynamics After simplification, it is expressed as: wherein is the space-time convolution; is the source position; is the seismic detector position; is the component of the source orientation represented by on the coordinate axis, = 1, 2, 3 corresponding to X, Y, Z axis respectively.

[0021] After substituting the source expression in step S1, the following is obtained: S3, assuming that the position set of the seismic detector is {x r (q)}, q = 1, 2,..., N r ; each seismic detector records three-component displacement u (α,q) (t); through independent excitation of three different directions, three groups of azimuth data sets are obtained: wherein is the data set, i.e. the projection of the same underground medium elastic parameter under different azimuth illumination; N r is the number of seismic detectors.

[0022] S4, define a model parameter vector m, and construct a full waveform inversion function with the objective of minimizing the three sets of azimuth data residuals: wherein represents the model m and is forward modeled in the direction of the source; through the adjoint state method, the gradient direction that makes the objective function descend is obtained ; the gradient direction is the weighted sum of the gradient fields calculated under three different azimuths and independently excited sources.

[0023] S5, define the objective function of the full waveform inversion function in step S4 as the difference norm of the observed data Dobs and the forward modeling data F(m): wherein R(m) is a regularization term, β is a regularization parameter, is the actual observed data, is the model calculated data.

[0024] S6, update the model through the L-BFGS algorithm iteration until convergence, and finally obtain the model parameter of the optimal solution .

[0025] S7, use the model parameter of the optimal solution to combine three sets of azimuth data for full waveform inversion, thereby obtaining the fracture strike azimuth in the detection area, i.e. obtaining the azimuth anisotropy information of the detection area, and realizing the identification of the disaster geological body in the detection target area.

[0026] Further, in the step S4, the gradient direction that makes the objective function descend is obtained through the adjoint state method , specifically: calculate the data residual ; solve the adjoint wave field and the gradient, wherein the adjoint wave field takes the data residual as a virtual source at each geophone and is reversely propagated in time; the gradient field is obtained by cross-correlating the forward wave field and the adjoint wave field in time and summing the contributions of three different azimuths: wherein , and are the strain tensors of the forward and adjoint wave fields, respectively;

[0027] Through the chain rule, the gradient of the objective function with respect to the elastic stiffness tensor is converted into the gradient direction of the model parameter vector m , and for any parameter in m, the gradient vector is: ​ The gradient of the density is calculated by the dot product of the velocity field: where is the displacement tensor of the forward wavefield; is the displacement tensor of the adjoint wavefield.

[0028] Through the above process, the gradient direction of the objective function is obtained .

[0029] Compared with the prior art, the present application has the following advantages: 1. The present application adopts the combination of a seismic source drill pipe, a capacitive drill pipe, a conductive drill pipe and a control console, three discharge electrodes correspond to three different orientation excitation ports respectively, the three excitation ports form orthogonal excitation ports in the drilling space, and the control console controls the excitation ports to generate directional shock waves in turn to form a directional seismic source; in this way, three spatially orthogonal excitation ports are formed to excite in time, three polarized direction known and pure shear wave sources are manufactured, thereby providing data support for subsequent acquisition of azimuth anisotropy information of the target area.

[0030] 2. The present application first acquires three sets of three-component seismic trace record data sets of independent excitation and different polarized direction sources, determines the source expression and the position set of the seismic detector, and obtains three sets of azimuth data after processing the data sets; then, a model parameter vector is defined, and a full waveform inversion function is determined; the gradient direction of the objective function is obtained by the adjoint state method, and the model parameters are iteratively updated by using the L-BFGS algorithm, and finally the model parameters of the optimal solution are combined with the three sets of azimuth data to perform full waveform inversion, thereby obtaining the azimuth anisotropy information of the detection area, and finally realizing the accurate identification of the disaster geological body in the target area by fusing multi-azimuth detection data. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is the structure diagram of the seismic source drill pipe in the detection system of the present application.

[0032] Figure 2 is the structure diagram of the capacitive drill pipe in the detection system of the present application.

[0033] Figure 3 is the structure diagram of the conductive drill pipe in the detection system of the present application.

[0034] Figure 4 is the structure diagram of the control console in the detection system of the present application.

[0035] Figure 5 is the field layout diagram of the detection system of the present application.

[0036] In the diagram: 1-Conductive slip ring, 2-Time synchronization device, 3-Electronic gyroscope one, 4-Discharge electrode, 5a-First excitation port, 5b-Second excitation port, 5c-Third excitation port, 6-Tilt sensor, 7-Wires and data transmission lines, 8-Battery, 9-Seismic insulating frame, 10-High voltage ceramic capacitor array, 11-Cable, 12-Voltage regulator, 13-Step-up transformer, 14-Rectifier, 15-Control display, 16-Electronic gyroscope two, 17-GPS module, 18-Time synchronization module, 19-Delay generator, 21-Detection target area, 22-Detection borehole, 23-Seismic detector borehole. Detailed Implementation

[0037] The present invention will be further described below.

[0038] like Figure 1 As shown, a multi-directional detection system for an electric spark source based on polarization effect includes a source drill rod, a capacitor drill rod, a conductive drill rod, and a control console; the source drill rod, capacitor drill rod, and conductive drill rod are coaxial in sequence and connected by a conductive slip ring 1, and are located within the detection borehole 22.

[0039] like Figure 1 As shown, the seismic source drill rod is equipped with a time synchronization device 2, an electronic gyroscope 3, an inclination sensor 6, a battery 8, and multiple discharge electrodes 4. The electronic gyroscope 3 and the inclination sensor 6 are used to measure the rotation angle and inclination angle of the seismic source drill rod in the detection borehole 22 in real time. The time synchronization device 2 is used to synchronize the electronic gyroscope 3 and the inclination sensor 6 with the control console. Three excitation ports facing different directions are opened on the outer wall of the seismic source drill rod, and each excitation port is equipped with an energy-releasing shear plate. Each discharge electrode faces one excitation port and is used to excite an electric pulse to generate a directional electric spark seismic source. This seismic source can achieve a wide frequency band excitation of 3Hz~3kHz, and its energy conversion efficiency can reach more than 75%. The battery 8 supplies power to the time synchronization device 2, the electronic gyroscope 3, and the inclination sensor 6. The three excitation ports are designated as first excitation port 5a, second excitation port 5b, and third excitation port 5c. The projections of the first and second excitation ports 5a and 5b onto the same cross-section of the seismic source drill rod are coaxial and opposite. The projections of the first and second excitation ports 5a and 5b onto the same cross-section of the seismic source drill rod are perpendicular to the projections of the third excitation port 5c. This arrangement creates three spatially orthogonal excitation ports within the detection borehole 22, generating three pure shear wave sources with known polarization directions. The polarization characteristics of seismic waves are then used to perform analytical detection of the target area 21.

[0040] like Figure 2As shown, a high-voltage ceramic capacitor array 10 is provided inside the capacitor drill rod, and the high-voltage ceramic capacitor array 10 is fixed inside the capacitor drill rod by an anti-vibration insulating frame 9; it is connected to each discharge electrode and is used to provide pulse current to the discharge electrode 4.

[0041] like Figure 3 As shown, the control console is located outside the borehole. The console adjusts the pulse current output by the high-voltage ceramic capacitor array 10 via the cable 11 inside the conductive drill rod, thereby controlling the directional electric spark sources generated by each discharge electrode 4 and acquiring feedback data from the electronic gyroscope 3 and tilt sensor 6 to achieve directional excitation of seismic waves in different orientations. Figure 4 As shown, the control console includes a voltage regulator 12, a step-up transformer 13, a rectifier 14, a control display 15, an electronic gyroscope 16, a GPS module 17, a time synchronization module 18, and a delay generator 19. The electronic gyroscope 16 and the GPS module 17 are used to acquire the position and orientation of the control console. The time synchronization module 18 is used to synchronize with the time synchronization device 2. The voltage regulator 12, the step-up transformer 13, and the rectifier 14 cooperate to adjust the pulse current output by the high-voltage ceramic capacitor array 10. The control display 15 is used to control the sequence of pulse currents output by each discharge electrode 4 and to acquire data from the electronic gyroscope 3 and the tilt sensor 6 to determine the orientation of each discharge electrode 4 within the detection borehole 22. The delay generator 19 is used to control the discharge electrodes 4 to discharge sequentially according to the time sequence.

[0042] As an improvement of the present invention, the energy-releasing shear plate is made of an amorphous alloy material. This material is an existing material that can resist the hydrostatic pressure of the drill pipe extending deep into the formation and is broken down under the excitation electric pulse of the discharge electrode 4, thereby generating a directional electric spark source within the probe borehole 22.

[0043] like Figure 5 As shown, the detection method of the above-mentioned multi-directional detection system for electric spark sources based on polarization effect includes the following steps: Step 1: Based on the geological conditions of the target area to be detected, construct seismic detector borehole 23 and determine the construction path of detection borehole 22. After completion, arrange multiple seismic detectors along the borehole direction in the borehole to form a seismic observation system.

[0044] Step 2: First, open all the internal components of the seismic source drill rod and the control console, and connect them with connecting cables to synchronize the time synchronization device 2 and the time synchronization module 18. At the same time, use the electronic gyroscope 1 3, tilt sensor 6, electronic gyroscope 2 16, and GPS module 17 to obtain the current azimuth information of the seismic source drill rod and the control console. Construct the local coordinate system and the geodetic coordinate system for the seismic source drill rod and the control console respectively, and transform the coordinate system of the seismic source drill rod to the geodetic coordinate system through coordinate transformation.

[0045] Step three, disconnect the seismic drill pipe and the control console, then connect the seismic drill pipe, the capacitive drill pipe and the conductive drill pipe in turn, drive the rotation through the drilling machine, drill the detection borehole 22 according to the construction path determined in step one, stop when drilling to the designed depth, the electronic gyroscope one 3 and the inclination sensor 6 record the rotation angle and the inclination information of the current seismic drill pipe, and reconnect the control console and the electronic gyroscope one 3 and the inclination sensor 6 through the wire and the data transmission line 7 to obtain the corresponding data, and determine the orientation of each excitation port after calculation.

[0046] Step four, the control console sends trigger instructions to the three discharge electrodes 4 in turn according to the preset time sequence; each discharge electrode 4 instantaneously releases high-voltage pulses in the drilling fluid to generate plasma channels and form directional shock waves after receiving the instructions; at the same time, start the seismic observation system to observe and record three groups of independent three-component seismic trace record data sets excited in three different directions in turn.

[0047] Step five, the control console inversely analyzes the observed seismic trace data set, compares the travel time, amplitude, spectrum and polarization state of the reflection / scattering signals in the three groups of data, extracts the azimuth anisotropy information of the detection area, and realizes the identification of the disaster geological body in the detection target area, specifically: S1, obtain the relationship between the geodetic coordinate system (i.e. the coordinate system of the control console outside the borehole) and the seismic source local coordinate system (i.e. the coordinate system of the seismic drill pipe inside the borehole): the rotation relationship of the seismic source local coordinate system relative to the geodetic coordinate system is determined by the electronic gyroscope one 3 and the inclination sensor 6 in real time. Let the rotation matrix be R, which satisfies Among them, is the seismic source local coordinate system; is the geodetic coordinate system.

[0048] Assuming that the propagation of elastic waves in the medium follows the motion equation and the generalized Hooke's law: Among them is the density, is the displacement field component, is the stress tensor component, is the seismic source body force term, is the independent variable, where represents the spatial coordinates, represents time.

[0049] Among them is the fourth-order elastic stiffness tensor, which has symmetry, is the strain tensor: In tensor formula, the letters (i, j, k, l) themselves do not represent fixed X, Y, Z or numerical order, but represent "any one direction" placeholder or "free index, subscript is defined by repeated occurrence or pair occurrence to define the operation, where u l represents the first l rectangular coordinate component of the displacement vector, represents, x l represents the first l rectangular coordinate axis of space, x k represents the kth rectangular coordinate axis of space.

[0050] According to the orientation of each excitation port, the position information of the three different direction excitation source in the earth coordinate system is determined; and then the source expression is determined: wherein is the number of excitations, is the force function, is the source position, is the Dirac function; is the source orientation of the a-th excitation, a = 1, 2, 3.

[0051] S2, under the excitation of point source, the displacement field solution can be represented by the Green tensor of elastic dynamics : wherein since the source is a space-time point source .

[0052] After simplification, it is: wherein is a space-time convolution; is the source position; is the seismic detector position; is the component of the source orientation represented by on the coordinate axis, =1,2,3 respectively corresponding to X, Y, Z axis.

[0053] After substituting the source expression in step S1, the following is obtained: ; S3, the position set of the seismic detector is set as {x r (q)}, q = 1, 2,..., N r ; each seismic detector records three-component displacement u (α,q)(t); three sets of azimuthal data are obtained by three independent excitations in different directions : where is the data set, i.e., the same elastic parameters of the subsurface medium under different azimuthal illumination.

[0054] S4, define the model parameter vector m: for the HTI medium representing the fracture, the Thomsen parameterization is commonly used: where is the fracture strike azimuth, is the P and S wave velocity in the isotropic background. is the three dimensionless Thomsen parameters describing the anisotropy strength of the HTI medium.

[0055] and construct the full waveform inversion function with the goal of minimizing the residual of the three sets of azimuthal data: where denotes the forward simulation of the model m and is performed in the direction of the source; the gradient direction that makes the objective function descend is obtained by the adjoint state method , specifically: calculate the data residual: ; solve the adjoint wave field and the gradient, where the adjoint wave field is taken as a virtual source at each geophone in time and is backward propagated; the gradient field is obtained by cross-correlation of the forward wave field and the adjoint wave field in time, and the contributions of the three different azimuths are summed up to obtain: where , are the strain tensors of the forward and adjoint wave fields, respectively; is the total time length of the seismic record.

[0056] By the chain rule, the gradient of the objective function with respect to the elastic stiffness tensor is converted to the gradient direction of the model parameter vector m , for any parameter in m, its gradient vector is: The dot product of the velocity field is used to calculate the gradient with respect to density: where is the displacement tensor of the forward wave field; is the displacement tensor of the adjoint wave field.

[0057] Through the above process, the gradient direction of the objective function is obtained .

[0058] The gradient direction is the weighted sum of the gradient fields calculated in three different directions and independently excited sources, and the specific formula is: This means that each model update must be performed simultaneously towards a compromised direction that weakens the data residual in three directions, thereby forcing the model to converge to a solution that can uniformly explain all azimuthal observations.

[0059] S5, define the objective function of the full waveform inversion function in step S4 as the difference norm of the observed data Dobs and the forward simulation data F(m): Where R(m) is the regularization term, and β is the regularization parameter, used to suppress the multi-solution; is the actual observed data, is the model calculation data; S6, update the model by L-BFGS algorithm iteration, the specific formula is , until convergence, finally obtain the optimal solution of the model parameters ; that is ; in the formula is the step size, is the approximate inverse Hessian matrix, is the iteration number.

[0060] S7, use the optimal solution of the model parameters Combine three sets of azimuthal data to perform full waveform inversion, thereby obtaining the fracture strike azimuth in the detection area, i.e. obtaining the azimuth anisotropy information of the detection area, and realizing the identification of the disaster geologic body in the detection target area.

[0061] The above only describes the preferred embodiments of the present application, and it should be noted that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A multi-directional detection system for electric spark sources based on polarization effect, characterized in that, It includes a seismic source drill rod, a capacitor drill rod, a conductive drill rod, and a control console; the seismic source drill rod, capacitor drill rod, and conductive drill rod are coaxially connected in sequence and located inside the detection borehole; The seismic source drill rod is equipped with a time synchronization device, an electronic gyroscope, an inclination sensor, a battery, and multiple discharge electrodes. The electronic gyroscope and inclination sensor are used to measure the rotation and inclination angles of the seismic source drill rod in real time within the borehole. The time synchronization device is used to synchronize the electronic gyroscope and inclination sensor with the control console. Three excitation ports facing different directions are opened on the outer wall of the seismic source drill rod, and each excitation port is equipped with an energy-releasing shear plate. Each discharge electrode faces one of the excitation ports and is used to generate a directional electric spark seismic source by exciting an electric pulse. The battery powers the time synchronization device, the electronic gyroscope, and the inclination sensor. The capacitor drill rod is equipped with a high-voltage ceramic capacitor array, which is connected to each discharge electrode to provide pulse current to the discharge electrode. The control console is located outside the borehole. The control console adjusts the pulse current output by the high-voltage ceramic capacitor array through the cable inside the conductive drill rod, thereby controlling the directional electric spark source generated by each discharge electrode and acquiring feedback data from the electronic gyroscope and tilt sensor to realize directional excitation of seismic waves in different directions.

2. The multi-directional detection system for electric spark sources based on polarization effect according to claim 1, characterized in that, The three excitation ports are designated as the first excitation port, the second excitation port, and the third excitation port. The projections of the first and second excitation ports onto the same cross-section of the vibrating source drill pipe are coaxial and opposite. The projections of the first and second excitation ports onto the same cross-section of the vibrating source drill pipe are perpendicular to the projections of the third excitation port.

3. The multi-directional detection system for electric spark sources based on polarization effect according to claim 1, characterized in that, The seismic source drill rod, capacitor drill rod, and conductive drill rod are connected to each other via conductive slip rings.

4. The multi-directional detection system for electric spark sources based on polarization effect according to claim 1, characterized in that, The high-voltage ceramic capacitor array is fixed inside the capacitor drill rod by an anti-vibration insulating frame.

5. The multi-directional detection system for electric spark sources based on polarization effect according to claim 1, characterized in that, The control console includes a voltage regulator, a step-up transformer, a rectifier, a control display, an electronic gyroscope II, a GPS module, a time synchronization module, and a delay generator. The electronic gyroscope II and the GPS module are used to acquire the position and orientation of the control console. The time synchronization module is used to synchronize with the time synchronization device. The voltage regulator, step-up transformer, and rectifier work together to adjust the pulse current output by the high-voltage ceramic capacitor array. The control display is used to control the sequence of pulse currents output by each discharge electrode and to acquire data from the electronic gyroscope I and the tilt sensor to determine the orientation of each discharge electrode within the borehole. The delay generator is used to control the discharge electrodes to discharge sequentially according to a time sequence.

6. The multi-directional detection system for electric spark sources based on polarization effect according to claim 1, characterized in that, The energy-releasing shear plate is made of amorphous alloy material.

7. A detection method for a multi-directional detection system for an electric spark source based on polarization effect according to any one of claims 1 to 6, characterized in that, Includes the following steps: Step 1: Based on the geological conditions of the target area to be detected, construct seismic detector boreholes and determine the construction path of the boreholes. After completion, arrange multiple seismic detectors along the borehole direction in the borehole to form a seismic observation system. Step 2: First, open all the internal components of the seismic source drill rod and the control console, and connect them with connecting cables to synchronize the time synchronization device and the time synchronization module. At the same time, use electronic gyroscope 1, tilt sensor, electronic gyroscope 2, and GPS module to obtain the current azimuth information of the seismic source drill rod and the control console, and construct the local coordinate system and the geodetic coordinate system of the seismic source drill rod and the control console respectively. Then, transform the coordinate system of the seismic source drill rod to the geodetic coordinate system through coordinate transformation. Step 3: Disconnect the source drill rod from the control console, then connect the source drill rod, capacitor drill rod, and conductive drill rod in sequence and rotate them using the drilling rig. Drill the exploratory borehole according to the construction path determined in Step 1. Stop drilling when the design depth is reached. The electronic gyroscope and tilt sensor record the rotation angle and tilt angle information of the source drill rod. Reconnect the control console to the electronic gyroscope and tilt sensor to obtain the corresponding data. After calculation, determine the orientation of each excitation port. Step 4: The control console sends trigger commands to the three discharge electrodes in sequence according to the preset timing. After receiving the command, each discharge electrode instantly releases a high-voltage pulse into the drilling fluid, generating a plasma channel and forming a directional shock wave. At the same time, the seismic observation system is activated to observe and record three independent three-component seismic trace data sets that are excited sequentially from three different directions. Step 5: The console performs inversion analysis on the seismic trace dataset recorded by observation. By comparing the travel time, amplitude, spectrum and polarization state of the reflected / scattered signals in the three sets of data, the azimuth anisotropy information of the detection area is extracted, thereby realizing the identification of hazardous geological bodies in the detection target area.

8. The detection method according to claim 7, characterized in that, Step five specifically involves: S1. Obtain the relationship between the geodetic coordinate system and the local coordinate system of the seismic source, and determine the position information of the three seismic sources in different directions on the geodetic coordinate system based on the orientation of each excitation port; then determine the source expression: in To trigger the number of times, It is a force function. Location of the epicenter. It is the Dirac function; Let α be the orientation of the source of the αth excitation, where α = 1, 2, 3; S2. Under point source excitation, the solution of the displacement field is obtained using the Green's tensor of elastic dynamics. Simplified representation: in Spatiotemporal convolution; Location of the epicenter; Location of the seismic detector; for The component of the hypocenter orientation represented on the coordinate axis; Substituting the source expression from step S1, we get: ； S3. Let the set of locations of the seismic detectors be {x} r (q) },q=1,2,...,N r Each seismic detector records three components of displacement u. (α,q) (t); A dataset of three sets of azimuth data was obtained through three independent excitations in different directions. : in For the dataset; N r The number of seismic detectors; S4. Define the model parameter vector m, and construct a full waveform inversion function with the objective of minimizing the residuals of the three sets of azimuth data: in Representing model m and using Forward modeling with the earthquake source as the direction; using the adjoint state method, the gradient direction that causes the objective function to decrease is obtained. The gradient direction is a weighted sum of the gradient fields calculated from three independently excited seismic sources in three different orientations. S5. Define the objective function of the full waveform inversion function in step S4 as the difference norm between the observed data Dobs and the forward simulation data F(m): Where R(m) is the regularization term and β is the regularization parameter. Based on actual observation data, Calculate data for the model; S6. Iteratively update the model using the L-BFGS algorithm until convergence, finally obtaining the optimal model parameters. ; S7. Using the model parameters of the optimal solution By combining three sets of azimuth data to perform full waveform inversion, the azimuth angle of the fracture strike in the detection area can be obtained, that is, the azimuth anisotropy information of the detection area can be obtained, so as to identify the hazardous geological bodies in the detection target area.

9. The detection method according to claim 8, characterized in that, In step S4, the gradient direction that causes the objective function to decrease is obtained using the adjoint state method. Specifically, this involves calculating the residual data: The accompanying wave field and gradient are solved, where the accompanying wave field uses the data residuals as virtual sources at each seismic detector and propagates backward in time; the gradient field is obtained by integrating the cross-correlation between the forward propagation wave field and the accompanying wave field in time and summing the contributions over three different orientations. In the formula, , These are the strain tensors for the propagating and accompanying wave fields, respectively. This represents the total duration of the seismic wave record. By using the chain rule, the gradient of the objective function with respect to the elastic stiffness tensor is... Transformed into the gradient direction with respect to the model parameter vector m For any parameter in m, its gradient vector is: Calculate the gradient with respect to density using the dot product of the velocity field: In the formula For the displacement tensor of the propagating wave field; For the displacement tensor of the accompanying wave field; Through the above process, the gradient direction that causes the objective function to decrease is obtained. .

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