A method and device for wave field fitting of body wave trough waves

Abstract

The present invention relates to the field of exploration physics technology, and specifically relates to a method and device for wave field fitting of body wave trough waves. This method can perform inversion using the established joint objective function. Based on the body wave field and trough wave dispersion information, the residual of the body wave field and the travel time residuals of each point corresponding to the trough wave are obtained, thereby constructing a large sparse matrix, jointly performing joint inversion, participating in iterative calculations, and obtaining the change amount of the velocity model parameters. It can be understood that since this method combines the wave field properties of body waves and the dispersion properties of trough waves, it weakens the non-linearity brought by different wave fields and different frequency components, can achieve a complete match of the full wave field information, and improve the clear description of the coal-rock interface.

Description

Technical Field

[0001] The present invention relates to the technical field of exploration physics, and in particular to a method and device for wave field fitting of body wave trough waves. Background Art

[0002] In order to improve the coal mining efficiency in a coal mine working face, it is necessary to clearly define the boundary between coal and rock mining. Therefore, depicting the coal-rock interface in the underground coal mine working face is the main purpose of three-dimensional full waveform inversion imaging research. According to the properties of the transmitted wave field, only trough waves can detect the coal-rock interface, while the resolution of the remaining refracted longitudinal waves, refracted transverse waves, and direct waves (collectively referred to as body waves) is insufficient, and the propagation path cannot penetrate this interface. Conventional body wave full waveform inversion cannot depict the coal-rock interface.

[0003] In addition, the underground coal mine transmitted seismic data has body wave and strong trough wave information. In wave field inversion fitting, the frequency ranges of the two wave fields are inconsistent, and the wavelength components are different. Therefore, when performing wave field inversion fitting, there is strong non-linearity, resulting in distorted inversion structures. The traditional objective function is to establish the full wave field residual between the forward seismic data and the actual seismic data, and then calculate the gradient of the data with respect to the underground model parameters, and solve the inverse problem from data to model through non-linear linearization. For this special dispersive wave of trough waves, simple iterative fitting of wave field data is difficult to satisfy the simultaneous fitting of the full wave field, and thus the information of body waves and trough waves cannot be utilized simultaneously. Summary of the Invention

[0004] In view of this, an object of the present invention is to provide a method for wave field fitting of body wave trough waves to solve the above problems in the prior art to a certain extent.

[0005] According to the first aspect of the embodiments of the present invention, a method for wave field fitting of body wave trough waves is provided, including:

[0006] Step S1, collecting transmitted data of a coal mine working face, and extracting longitudinal wave data, transverse wave data, and trough wave data according to the transmitted data of the coal mine working face;

[0007] Step S2, obtaining a longitudinal wave waveform residual difference objective function according to the longitudinal wave data, and obtaining a transverse wave waveform residual difference objective function according to the transverse wave data;

[0008] Step S3, using a preset geophone point to obtain the travel time of the trough wave simulated wave field;

[0009] Step S4, obtaining a trough wave travel time residual difference objective function according to the travel time of the trough wave simulated wave field and the trough wave data;

[0010] Step S5: Obtain a joint objective function based on the longitudinal wave waveform residual difference objective function, the shear wave waveform residual difference objective function, and the slot wave travel time residual difference objective function;

[0011] Step S6: Calculate a new longitudinal wave velocity and a new shear wave velocity according to the joint objective function, a preset longitudinal wave velocity, and a preset shear wave velocity;

[0012] Step S7: If the joint objective function does not converge, perform 3D elastic wave equation forward modeling using the new longitudinal wave velocity and the new shear wave velocity to obtain simulated transmission seismic data;

[0013] Step S8: Extract longitudinal wave data, shear wave data, and slot wave data from the simulated transmission seismic data, and then go back to execute Step S2;

[0014] Step S9: If the joint objective function converges, output the inversion result.

[0015] Preferably, the obtaining of the travel time of the slot wave simulation wave field using preset geophone points includes:

[0016] Establish a one-dimensional medium model for the preset geophone points;

[0017] Solve the dispersion curve corresponding to each preset geophone point according to the one-dimensional medium model, and obtain a velocity distribution map corresponding to different periods according to the dispersion curve;

[0018] Establish a three-dimensional model for the preset geophone points, perform grid meshing on the three-dimensional model according to the velocity distribution map, solve the eikonal equation, and obtain the travel time corresponding to each geophone point;

[0019] Calculate the travel time of the slot wave simulation wave field according to the travel times corresponding to all the geophone points.

[0020] Preferably, the obtaining of the slot wave travel time residual difference objective function according to the travel time of the slot wave simulation wave field and the slot wave data includes:

[0021] Obtain the travel time of the slot wave observed wave field according to the slot wave data;

[0022] Take the difference between the travel time of the slot wave simulation wave field and the travel time of the slot wave observed wave field as the slot wave travel time residual difference objective function.

[0023] Preferably, the obtaining of the joint objective function according to the longitudinal wave waveform residual difference objective function, the shear wave waveform residual difference objective function, and the slot wave travel time residual difference objective function includes:

[0024] The obtained joint objective function is as follows:

[0025]

[0026] Among them, , is the longitudinal wave simulated wavefield data of the i-th component, is the longitudinal wave observed wavefield data of the i-th component; , is the shear wave simulated wavefield data of the i-th component, is the shear wave observed wavefield data of the i-th component; , is the travel time of the slot wave simulated wavefield of the i-th component, is the travel time of the slot wave observed wavefield of the i-th component; is the gradient value of the longitudinal wave wavefield with respect to the longitudinal wave, is the gradient value of the shear wave wavefield with respect to the shear wave, is the gradient value of the slot wave travel time with respect to the shear wave; V p is the longitudinal wave velocity, V s is the shear wave velocity; is the longitudinal wave perturbation, is the shear wave perturbation.

[0027] Preferably, calculating the new longitudinal wave velocity and the new shear wave velocity according to the joint objective function, the preset longitudinal wave velocity, and the preset shear wave velocity includes:

[0028] Calculating the gradient value of the longitudinal wave wavefield with respect to the longitudinal wave, the gradient value of the shear wave wavefield with respect to the shear wave, and the gradient value of the slot wave travel time with respect to the shear wave by using the joint objective function;

[0029] Solving the joint objective function by using the gradient value of the longitudinal wave wavefield with respect to the longitudinal wave, the gradient value of the shear wave wavefield with respect to the shear wave, and the gradient value of the slot wave travel time with respect to the shear wave to obtain the longitudinal wave perturbation and the shear wave perturbation;

[0030] Calculating the new longitudinal wave velocity and the new shear wave velocity according to the preset longitudinal wave velocity, the preset shear wave velocity, the longitudinal wave perturbation, and the shear wave perturbation.

[0031] According to the second aspect of the embodiments of the present invention, there is provided a wavefield fitting device for body waves and slot waves, including:

[0032] A main controller and a memory connected to the main controller;

[0033] A memory, in which program instructions are stored;

[0034] The main controller is configured to execute the program instructions stored in the memory to execute the method described in any one of the above.

[0035] The technical solutions provided by the embodiments of the present invention may include the following beneficial effects:

[0036] It is understandable that the present invention discloses a method and device for wave field fitting of body wave trough waves. This method can perform inversion using the established combined objective function. Based on the body wave field and trough wave dispersion information, the residual of the body wave field and the travel time residuals of each point corresponding to the trough wave are obtained, thereby constructing a large sparse matrix, jointly performing combined inversion, participating in iterative calculations, and obtaining the change amount of the velocity model parameters. It is understandable that since this method combines the wave field properties of body waves and the dispersion properties of trough waves, it weakens the nonlinearity brought by different frequency components of different wave fields, can achieve a complete match of the full wave field information, and improve the clear delineation of the coal-rock interface.

[0037] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present invention. Brief Description of the Drawings

[0038] The accompanying drawings herein are incorporated into the specification and form a part of the specification, showing embodiments consistent with the present invention, and are used together with the specification to explain the principles of the present invention.

[0039] Figure 1 is a schematic flow chart of a method for wave field fitting of body wave trough waves shown according to an exemplary embodiment;

[0040] Figure 2 is a schematic diagram for obtaining the travel time of the simulated wave field of trough waves shown according to an exemplary embodiment;

[0041] Figure 3 is a schematic diagram of the y-z cross-section of the inversion result of the traditional method;

[0042] Figure 4 is a schematic diagram of the y-z cross-section of the result of an exemplary embodiment. Detailed Embodiments

[0043] Here, the exemplary embodiments will be described in detail, and the examples are shown in the accompanying drawings. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. On the contrary, they are only examples of devices and methods consistent with some aspects of the present invention as detailed in the appended claims.

[0044] Embodiment 1

[0045] Figure 1 is a schematic flow chart of a method for wave field fitting of body wave trough waves shown according to an exemplary embodiment. Refer to Figure 1 , a method for wave field fitting of body wave trough waves is provided, including:

[0046] Step S1: Collect the transmission data of the coal mining face, and extract the longitudinal wave data, transverse wave data, and trough wave data according to the transmission data of the coal mining face.

[0047] In specific practice, the collected transmission data of the coal mining face can be used to extract the refracted longitudinal wave of the actual and synthetic data through band-pass filtering and cutting as the longitudinal wave data; the refracted transverse wave of the actual and synthetic data can be extracted through the combination of band-pass filtering and polarity filtering and direct cutting as the transverse wave data; the actual trough wave can be extracted through direct cutting as the trough wave data.

[0048] Step S2: Obtain the longitudinal wave waveform residual difference objective function according to the longitudinal wave data, and obtain the transverse wave waveform residual difference objective function according to the transverse wave data.

[0049] Step S3: Use the preset geophone points to obtain the travel time of the trough wave simulation wave field.

[0050] In specific practice, the travel time of the trough wave simulation wave field needs to be obtained in combination with the dispersion characteristics of the trough wave. It should be noted that the obtaining of the travel time of the trough wave simulation wave field by using the preset geophone points includes:

[0051] Establish a one-dimensional medium model of the preset geophone points;

[0052] Solve the dispersion curve corresponding to each preset geophone point according to the one-dimensional medium model, and obtain the velocity distribution map corresponding to different periods according to the dispersion curve;

[0053] Establish a three-dimensional model of the preset geophone points, perform grid meshing on the three-dimensional model according to the velocity distribution map, solve the eikonal equation, and obtain the travel time corresponding to each geophone point;

[0054] Calculate the travel time of the trough wave simulation wave field according to the travel times corresponding to all geophone points.

[0055] In specific practice, referring to Figure 2 , assuming that each geophone point corresponds to a one-dimensional medium model of three layers (surrounding rock - coal seam - surrounding rock), the dispersion curve corresponding to each geophone can be solved according to the Thomson-Haskell propagation matrix method, so as to obtain the velocity distribution map (dispersion map) corresponding to different periods (or frequencies), as shown by Figure 2 the first arrow.

[0056] Assuming that the geophone points and the seismic source are on the left and right sides of the three-layer model, then according to the ray tracing problem in the three-dimensional medium, perform grid meshing on the three-dimensional model to solve the eikonal equation, obtain the travel time of each point, and finally trace the travel time corresponding to each geophone, that is , xr is the position of the geophone, xsis the position of the seismic source, is the corresponding velocity in the dispersion curve, f is the frequency band range where the slot wave of the actual data is located, and finally the travel times corresponding to different period waves of the slot wave are calculated .

[0057] Step S4: Obtain the travel-time residual difference objective function of the slot wave according to the travel time of the slot wave simulated wave field and the slot wave data.

[0058] It should be noted that this step also includes:

[0059] Obtain the travel time of the slot wave observed wave field according to the slot wave data;

[0060] Take the difference between the travel time of the slot wave simulated wave field and the travel time of the slot wave observed wave field as the travel-time residual difference objective function of the slot wave.

[0061] In specific practice, the travel time of the corresponding wave field is obtained from the dispersion curve of the simulated slot wave, and the travel time of the corresponding wave field is obtained from the transmitted slot wave separated from the measured data, so as to obtain the ill-posed function of the travel time with the dispersion property of the slot wave .

[0062] Step S5: Obtain the joint objective function according to the longitudinal wave waveform residual difference objective function, the transverse wave waveform residual difference objective function, and the travel-time residual difference objective function of the slot wave.

[0063] It should be noted that the obtained joint objective function is as follows:

[0064]

[0065] Among them, , is the longitudinal wave simulated wave field data of the i-th component, is the longitudinal wave observed wave field data of the i-th component; , is the transverse wave simulated wave field data of the i-th component, is the transverse wave observed wave field data of the i-th component; , is the travel time of the slot wave simulated wave field of the i-th component, is the travel time of the slot wave observed wave field of the i-th component; is the gradient value of the longitudinal wave field with respect to the longitudinal wave, is the gradient value of the transverse wave field with respect to the transverse wave, is the gradient value of the travel time of the slot wave with respect to the transverse wave; V p is the longitudinal wave velocity, V s is the transverse wave velocity; is the longitudinal wave perturbation amount, is the shear wave perturbation quantity.

[0066] The above final combined objective function is composed of three ill - posed functions containing different types of wave - field information, where is an empirical constant, representing the influence weight of the trough wave compared to the body wave, and can be obtained by trial - and - error debugging.

[0067] Step S6: Calculate the new P - wave velocity and new S - wave velocity according to the combined objective function, the preset P - wave velocity, and the preset S - wave velocity.

[0068] It should be noted that this step may include:

[0069] Calculate the gradient value of the P - wave wave - field with respect to the P - wave, the gradient value of the S - wave wave - field with respect to the S - wave, and the gradient value of the trough - wave travel - time with respect to the S - wave using the combined objective function;

[0070] Solve the combined objective function using the gradient value of the P - wave wave - field with respect to the P - wave, the gradient value of the S - wave wave - field with respect to the S - wave, and the gradient value of the trough - wave travel - time with respect to the S - wave to obtain the P - wave perturbation quantity and the S - wave perturbation quantity;

[0071] Calculate the new P - wave velocity and new S - wave velocity according to the preset P - wave velocity, preset S - wave velocity, P - wave perturbation quantity, and S - wave perturbation quantity.

[0072] In specific practice, the LSQR method can be used to solve the above large - scale sparse algebraic equations (combined objective function). After obtaining the perturbation quantity of the model parameters by iteration, update the corresponding model parameters as follows:

[0073]

[0074]

[0075] where and are the search step sizes obtained by the linear search algorithm respectively.

[0076] Step S7: If the combined objective function does not converge, perform 3D elastic wave equation forward modeling using the new P - wave velocity and new S - wave velocity to obtain simulated transmission seismic data.

[0077] In specific practice, the P - wave velocity and S - wave velocity can be used to construct a velocity model. Update the P - wave velocity and S - wave velocity in the velocity model through the above Step S6, thereby realizing the iteration of the velocity model. Then, perform 3D elastic wave equation forward modeling through the new velocity model to obtain simulated transmission seismic data.

[0078] Step S8: Extract the P-wave data, S-wave data, and channel wave data from the simulated transmission seismic data, and then proceed to step S2;

[0079] Step S9: If the joint objective function converges, output the inversion result.

[0080] In specific practice, a numerical simulation experiment can be designed according to the method of inversely fitting the wave field with the traditional objective function to invert the P-wave and S-wave velocities and verify the effectiveness of the technical solution of this embodiment. Using the "sandwich" velocity model of "surrounding rock - coal seam - surrounding rock", the lengths of the model in the x, y, and z directions are 625m, 450m, and 30m respectively, and the discrete grid size is dx = dy = 1m, dz = 0.5m. The geophones and the seismic source are distributed on both sides of the xy-plane model boundary, and a transmission observation system is adopted, that is, the seismic source is excited on one side and the geophones on the other side receive. In the model, the low-velocity coal seam has a P-wave velocity of 3200m / s and an S-wave velocity of 1500m / s, the high-velocity surrounding rock has a P-wave velocity of 4000m / s and an S-wave velocity of 2200m / s, the coal seam thickness is 2 meters, and the seismic signal propagates through the low-velocity coal seam to form a transmission seismic wave field.

[0081] Verify the inversion effects of the traditional method and the method of the present invention. First, fit the observed seismic wave field data as a whole according to the traditional workflow to obtain Figure 3 , due to the nonlinear influence of multiple wave fields on each other, the inversion result shows structural distortion and extremely low resolution; then, according to the workflow of the method of the present invention, intercept the data within the time window corresponding to different wave fields in turn, and through wave field forward simulation and channel wave dispersion analysis, construct a joint objective function with the obtained data and the actual observed data. After inversion calculation, obtain Figure 4 , the improved result shows that the coal-rock interface is clearer, the horizons form continuous phase and amplitude, the nonlinearity brought by the fitting of different wave fields in the inversion is reduced, and the effect of integrating the role of channel wave information into the operation is more reflected.

[0082] It can be understood that this embodiment shows a method and device for wave field fitting of body waves and channel waves. This method can perform inversion using the established joint objective function, and based on the body wave field and channel wave dispersion information, obtain the residual of the body wave field and the travel time residual of each point corresponding to the channel wave, so as to construct a large sparse matrix, jointly perform joint inversion, participate in iterative calculation, and obtain the change amount of the velocity model parameters. It can be understood that because this method combines the wave field properties of body waves and the dispersion properties of channel waves, it weakens the nonlinearity brought by different frequency components of different wave fields, can achieve a complete match of the full wave field information, and improve the clear description of the coal-rock interface.

[0083] Embodiment 2

[0084] According to a second aspect of the embodiments of the present invention, there is provided a wave field fitting device for body wave trough waves, including:

[0085] A main controller and a memory connected to the main controller;

[0086] The memory stores program instructions;

[0087] The main controller is configured to execute the program instructions stored in the memory and execute the method described in any one of the above.

[0088] It can be understood that the same or similar parts in the above embodiments can be referred to each other, and the content not detailed in some embodiments can be referred to the same or similar content in other embodiments.

[0089] It should be noted that in the description of the present invention, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise specified, the meaning of "plurality" refers to at least two.

[0090] Any process or method description in the flowchart or described in other ways herein can be understood as representing a module, segment, or part of code including one or more executable instructions for implementing a specific logical function or process, and the scope of the preferred embodiments of the present invention includes additional implementations, where the functions can be executed in a substantially simultaneous manner or in an opposite order according to the functions involved, rather than in the order shown or discussed, which should be understood by those skilled in the technical field to which the embodiments of the present invention belong.

[0091] It should be understood that each part of the present invention can be implemented by hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, any one of the following well-known technologies in the art or a combination thereof can be used: discrete logic circuits with logic gate circuits for implementing logical functions on data signals, application-specific integrated circuits with appropriate combinational logic gate circuits, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0092] Those of ordinary skill in the technical field of the present invention can understand that all or part of the steps carried by the methods in the above embodiments can be completed by instructing relevant hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiments.

[0093] In addition, each functional unit in various embodiments of the present invention may be integrated into a processing module, or each unit may exist physically alone, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. When the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0094] The above-mentioned storage medium may be a read-only memory, a magnetic disk, an optical disc, or the like.

[0095] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0096] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for wave field fitting of body wave trough waves, characterized in that, Including: Step S1: Collect the transmission data of the coal mining face, and extract the longitudinal wave data, transverse wave data, and trough wave data according to the transmission data of the coal mining face; Step S2: Obtain the longitudinal wave waveform residual difference objective function according to the longitudinal wave data, and obtain the transverse wave waveform residual difference objective function according to the transverse wave data; Step S3: Use the preset geophone points to obtain the travel time of the trough wave simulation wave field; Step S4: According to the travel time of the trough wave simulation wave field and the trough wave data, obtain the trough wave travel time residual difference objective function, including: obtaining the travel time of the trough wave observation wave field according to the trough wave data; taking the difference between the travel time of the trough wave simulation wave field and the travel time of the trough wave observation wave field as the trough wave travel time residual difference objective function; Step S5: According to the longitudinal wave waveform residual difference objective function, the transverse wave waveform residual difference objective function, and the trough wave travel time residual difference objective function, obtain the joint objective function; Step S6: Calculate the new longitudinal wave velocity and the new transverse wave velocity according to the joint objective function, the preset longitudinal wave velocity, and the preset transverse wave velocity; Step S7: If the joint objective function does not converge, perform forward simulation of the three-dimensional elastic wave equation using the new longitudinal wave velocity and the new transverse wave velocity to obtain the simulated transmission seismic data; Step S8: Extract the longitudinal wave data, transverse wave data, and trough wave data according to the simulated transmission seismic data, and then execute Step S2; Step S9: If the joint objective function converges, output the inversion result.

2. The method according to claim 1, wherein The obtaining the travel time of the trough wave simulation wave field by using the preset geophone points includes: Establish a one-dimensional medium model of the preset geophone points; Solve the dispersion curve corresponding to each preset geophone point according to the one-dimensional medium model, and obtain the velocity distribution map corresponding to different periods according to the dispersion curve; Establish a three-dimensional model of the preset geophone points, and perform grid meshing on the three-dimensional model according to the velocity distribution map to solve the eikonal equation, and obtain the travel time corresponding to each geophone point; Calculate the travel time of the trough wave simulation wave field according to the travel times corresponding to all the geophone points.

3. The method according to claim 1, wherein The obtaining the joint objective function according to the longitudinal wave waveform residual difference objective function, the transverse wave waveform residual difference objective function, and the trough wave travel time residual difference objective function includes: The obtained joint objective function is as follows: Among them, , is the longitudinal wave simulated wavefield data of the i-th component, is the longitudinal wave observed wavefield data of the i-th component; , is the shear wave simulated wavefield data of the i-th component, is the shear wave observed wavefield data of the i-th component; , is the travel time of the slot wave simulated wavefield of the i-th component, is the travel time of the slot wave observed wavefield of the i-th component; is the gradient value of the longitudinal wave wavefield with respect to the longitudinal wave, is the gradient value of the shear wave wavefield with respect to the shear wave, is the gradient value of the slot wave travel time with respect to the shear wave; V p is the longitudinal wave velocity, V s is the shear wave velocity; is the longitudinal wave perturbation, is the shear wave perturbation, is an empirical constant, representing the influence weight of the slot wave compared to the body wave.

4. The method according to claim 3, wherein The calculating the new longitudinal wave velocity and the new transverse wave velocity according to the joint objective function, the preset longitudinal wave velocity, and the preset transverse wave velocity includes: Calculating the gradient value of the longitudinal wave field with respect to the longitudinal wave, the gradient value of the transverse wave field with respect to the transverse wave, and the gradient value of the trough wave travel time with respect to the transverse wave by using the joint objective function; Solving the joint objective function by using the gradient value of the longitudinal wave field with respect to the longitudinal wave, the gradient value of the transverse wave field with respect to the transverse wave, and the gradient value of the trough wave travel time with respect to the transverse wave to obtain the longitudinal wave perturbation and the transverse wave perturbation; Calculate the new longitudinal wave velocity and the new transverse wave velocity according to the preset longitudinal wave velocity, the preset transverse wave velocity, the longitudinal wave perturbation, and the transverse wave perturbation.

5. A wave field fitting device for body wave trough waves, characterized in that Including: A main controller, and a memory connected to the main controller; The memory stores program instructions; The main controller is used to execute the program instructions stored in the memory and execute the method according to any one of claims 1 to 4.

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