Chromatographic static correction method and device based on VTI medium and electronic equipment

Abstract

The invention discloses a chromatography static correction method based on a VTI medium. The method comprises the following steps: picking up seismic first arrival wave time by adopting a high-precision first arrival picking-up method; introducing the anisotropic parameters into a travel time linear interpolation (LTI) ray tracing algorithm, and establishing a travel time calculation formula of the first-motion wave in a VTI medium; carrying out near-surface velocity tomography inversion by adopting an LSQR algorithm; respectively calculating a reference surface static correction value and a model-based first-motion wave residual static correction value; the problem of medium and long wavelength static correction is solved by applying a reference surface static correction value, and the accuracy of a structural form is ensured; and then the short-wavelength static correction problem is solved by applying the first-motion wave residual static correction value, the precision and the signal-to-noise ratio of superposition imaging are further improved, and high-precision static correction processing is realized through fusion of the two methods. The method effectively solves the influence of the complex near-surface on the static time shifting of the seismic data, and lays a foundation for high-precision seismic imaging.

Description

Technical Field

[0001] The present invention relates to the technical field of geophysical exploration, and particularly relates to a tomography static correction method, device and electronic equipment based on VTI medium. Background Art

[0002] Due to the topographic undulation and lateral variation of near-surface velocity, the static correction problem generally exists in the seismic data collected in the field. The static correction processing is used to eliminate the influence of the near-surface low structure on the seismic wave propagation time, so as to improve the imaging quality and accuracy of the seismic data. However, in complex near-surface areas, the propagation path of seismic waves becomes extremely complex, and the static correction problem is particularly prominent. Effectively solving the static correction problem has become one of the difficulties in seismic data processing in complex near-surface areas.

[0003] The currently commonly used static correction methods include refraction static correction and tomography static correction. Both are based on the first arrival time of seismic records and calculate the static correction amount by obtaining the velocity of the near-surface low velocity zone. The refraction static correction uses refraction wave information to estimate the near-surface velocity and thickness, and is applicable to areas with small lateral velocity changes. Its advantage lies in high calculation efficiency. However, under complex near-surface conditions, due to significant lateral velocity changes, the application of refraction static correction is limited. The tomography static correction breaks through the limitations of the traditional refraction wave static correction method on the longitudinal and lateral changes of the surface and near-surface structures, and is particularly suitable for complex geological regions. This method can more accurately depict the near-surface velocity distribution through high-precision tomography inversion, so as to calculate a more reliable static correction amount, significantly improving the accuracy and adaptability of static correction.

[0004] Inverting the near-surface velocity model using the first arrival wave travel time is a key step in tomography static correction processing. However, due to the generally anisotropic characteristics of the earth medium, there are significant limitations in the seismic wave field travel time calculation and velocity modeling accuracy of conventional isotropic first arrival wave tomography methods. The tomography inversion process includes forward simulation and inversion calculation. Therefore, when using ray tracing or wave equation forward simulation, considering the influence of anisotropy on wave propagation can significantly improve the accuracy of wavefront travel time calculation; introducing anisotropic parameters in the inversion calculation and carrying out tomography inversion based on anisotropic media can significantly improve the accuracy of near-surface modeling, which is beneficial to the accurate calculation of static correction amounts.

[0005] In the static correction calculation based on the velocity model, it mainly includes datum static correction and residual static correction. The datum static correction calculates the static correction amounts of shot points and geophone points, and corrects the seismic records to the horizontal datum plane, thereby eliminating the large-scale influence of terrain undulation and low-velocity layer on the seismic wave propagation time. The residual static correction is based on the datum static correction, and uses the spatial coherence of refracted waves or reflected waves and the inter-trace time difference to further solve the local residual time difference. With the improvement of the requirements for data processing quality, various residual static correction calculation methods have been developed in recent years, including cross-correlation method, maximum energy method and model-based method. These methods can effectively improve the static correction accuracy and provide guarantee for high-resolution seismic imaging. The present invention performs forward modeling by establishing the travel time calculation formula of seismic first arrival waves in VTI media, and the inversion adopts the regularized LSQR algorithm, thereby forming a tomography inversion method based on VTI media. This method can invert to obtain a near-surface velocity model closer to the real one, and significantly improve the velocity modeling accuracy under complex near-surface conditions. In terms of static correction calculation, aiming at the processing objectives of structural morphology and imaging quality, the static correction amounts are decomposed and deepened, and the datum static correction and the first arrival wave residual static correction amount based on the model are calculated respectively. By fusing and calculating the two static correction amounts and comparing their applications, the target-driven static correction research is carried out, effectively solving the influence of complex near-surface on the static time shift of seismic data and laying a foundation for high-precision seismic imaging. Summary of the Invention

[0006] An object of the present invention is to provide a tomography static correction method, device and electronic device based on VTI media to solve the problems proposed in the above-mentioned background technology.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] In the first aspect, a tomography static correction method based on VTI media is provided, including:

[0009] Step S1, picking up seismic first arrival waves: picking up the time of seismic first arrival waves by using a high-precision first arrival picking method;

[0010] Step S2, ray tracing and first arrival wave travel time calculation: introducing anisotropic parameters into the travel time linear interpolation (LTI) ray tracing algorithm, and establishing the travel time calculation formula of first arrival waves in VTI media;

[0011] Step S3, near-surface velocity tomography inversion: using the LSQR algorithm for iterative inversion, and adding a regularization constraint factor during the inversion process;

[0012] Step S4, static correction amount calculation: calculating the datum static correction and the first arrival wave residual static correction amount based on the model respectively;

[0013] Step S5, perform static correction: Based on the static correction amount calculated in step S4, apply the datum plane static correction amount to solve the medium- and long-wavelength static correction problems and ensure the accuracy of the structural morphology; then apply the first-arrival residual static correction amount to solve the short-wavelength static correction problem and further improve the precision and signal-to-noise ratio of the stacked imaging. High-precision static correction processing is achieved through the integration of the two methods.

[0014] Further, in step S1, when picking up the seismic first arrivals, use a high-precision first-arrival picking method to pick up the seismic first-arrival time, including:

[0015] Combine the method of improving the signal-to-noise ratio of the original data, the linear dynamic correction method, applying the preliminary static correction amount, manual interaction picking, and the automatic picking algorithm, and supplement with quality control means to pick up the seismic first-arrival time to ensure the reliability of the picked first-arrival time.

[0016] Further, in step S2, when performing ray tracing and first-arrival travel-time calculation, introduce the anisotropic parameter into the travel-time linear interpolation (LTI) ray-tracing algorithm, and establish the first-arrival travel-time calculation formula in the VTI medium, including:

[0017] Step S21: Establish the relationship between the seismic wavefield propagation velocity and the propagation angle in the VTI medium as follows:

[0018]

[0019] In the formula, v p represents the group velocity of the qP wave in the VTI medium, represents the angle between the group velocity and the vertical direction, δ and ε are dimensionless Thomsen anisotropic parameters, and v p0 is the vertical propagation velocity of the qP wave;

[0020] Step S22: Calculate the first-arrival travel time in the VTI medium based on the travel-time linear interpolation (LTI) ray-tracing algorithm as follows: The travel time t c at point C can be expressed as:

[0021]

[0022] In the formula, s represents the slowness near point C. Since the velocity in the VTI medium is a function of the propagation angle, s in the above formula is also a function that varies with the group angle; the LTI method calculates the travel time at point C and the coordinates of the intersection point D of the ray passing through AB and reaching C with AB through linear interpolation based on the known travel times at points A and B. Therefore, t a is the travel time at point A, and t bWhen traveling to point B, d1 is the distance between A and B, d2 is the distance between point A and the projection point E of point C projected vertically onto AB, l is the distance between the intersection point D and the projection point E; d3 is the distance between the projection point E and point C; Step S23: Introduce the anisotropic parameter into the travel-time linear interpolation (LTI) ray-tracing algorithm, and there is:

[0023] Express Equation (2) as a function of l:

[0024]

[0025] In the formula, s p0 is the slowness of the qP wave in the vertical direction, and the value of l is between d2 - d1 and d1;

[0026] Substitute Equation (4) into Equation (3) to obtain

[0027]

[0028] In the formula, t pc is the travel time for the ray passing through point D to reach point C with slowness s p The coordinates of point D can be expressed as:

[0029]

[0030] In the formula, x a , x b , x d are the abscissas at points A, B, and D respectively; z a , z d are the ordinates at points A and D respectively, r is the distance between point A and point D, and |AB| is the distance between point A and point B.

[0031] Furthermore, in step S4, when calculating the static correction amount, calculate the datum plane static correction and the first-arrival residual static correction amount based on the model respectively, including:

[0032] Step S41, calculate the datum plane static correction amount: For any position, the datum plane static correction needs to calculate the static correction amounts of the shot point and the receiver point respectively, and its calculation formula is as follows:

[0033]

[0034] In the formula, t represents the datum plane static correction amount of the shot point / receiver point, E g is the elevation of the shot point or the receiver point; E d is the elevation of the datum plane; h i , v i are the thickness and velocity of each layer in the low-velocity layer with reduced velocity respectively; v c is the velocity of the high-velocity layer; N is the number of layers in the low-velocity zone.

[0035] Step S42, calculate the residual statics of first-arrival waves based on the model: The residual statics algorithm of first-arrival waves based on the model establishes a relationship curve model between the first-arrival time and the offset, and uses the difference between the actual first-arrival time and the model-predicted time to solve for the residual statics. Through surface-consistent decomposition, the residual statics of the shot point and the receiver point for each trace are obtained respectively, as follows:

[0036] After determining the model trace, for the sth shot and the rth receiver point, the difference in the first-arrival time between the model trace and the actual trace can be expressed as: i For the sth shot and the rth receiver point, j The difference in the first-arrival time between the model trace and the actual trace at the receiver point can be expressed as:

[0037]

[0038] In the formula, represent the model first-arrival time and the actual first-arrival time respectively, and ΔT i,j can also represent the residual statics, which is the sum of the residual statics of the shot point and the receiver point for this trace, that is, ΔT i,j = T Si + T Rj . If there are j traces for the ith shot, summing up the above formula gives:

[0039]

[0040] According to the assumption that the sum of the residual statics of all receiver points in the common-shot gather is zero, the residual statics of the shot point for the ith shot can be obtained through the following formula:

[0041]

[0042] Similarly, according to the assumption that the sum of the residual statics of all shot points in each common-receiver gather is zero, the residual statics of any receiver point can be obtained:

[0043]

[0044] In the second aspect, a tomography statics correction device based on VTI media is provided, including:

[0045] First-arrival wave picking unit for seismic waves: Picks up the first-arrival time of seismic waves using a high-precision first-arrival picking method;

[0046] Ray tracing and first-arrival travel-time calculation unit: Introduces anisotropic parameters into the travel-time linear interpolation (LTI) ray tracing algorithm, and establishes a first-arrival travel-time calculation formula in VTI media;

[0047] Near-surface velocity tomography inversion unit: Performs iterative inversion using the LSQR algorithm, and adds a regularization constraint factor during the inversion process;

[0048] Static correction calculation unit: Calculate the datum plane static correction and the first-arrival residual static correction based on the model respectively;

[0049] Static correction implementation unit: Based on the static correction calculated by the static correction calculation unit, apply the datum plane static correction to solve the medium- and long-wavelength static correction problems and ensure the accuracy of the structural morphology; then apply the first-arrival residual static correction to solve the short-wavelength static correction problem, further improve the precision and signal-to-noise ratio of the stacked imaging, and achieve high-precision static correction processing through the fusion of the two methods. Further, in the first-arrival seismic wave picking unit, a high-precision first-arrival picking method is used to pick the first-arrival time of the seismic wave, including:

[0050] Combining the method of improving the signal-to-noise ratio of the original data, the linear dynamic correction method, applying the preliminary static correction and manual interaction picking with the automatic picking algorithm, and supplemented by quality control means to pick the first-arrival time of the seismic wave to ensure the reliability of the picked first-arrival time.

[0051] Further, in the ray tracing and first-arrival travel time calculation unit, anisotropic parameters are introduced into the travel time linear interpolation (LTI) ray tracing algorithm, and the first-arrival travel time calculation formula in the VTI medium is established, including:

[0052] The first module: Establish the relationship between the seismic wave field propagation velocity and the propagation angle in the VTI medium as follows:

[0053]

[0054] In the formula, v p represents the group velocity of the qP wave in the VTI medium, represents the angle between the group velocity and the vertical direction, δ and ε are dimensionless Thomsen anisotropic parameters, and v p0 is the vertical propagation velocity of the qP wave;

[0055] The second module: Calculate the first-arrival travel time in the VTI medium based on the travel time linear interpolation (LTI) ray tracing algorithm as follows: The travel time t of point C c can be expressed as:

[0056]

[0057] In the formula, s represents the slowness near point C. Since the velocity in the VTI medium is a function of the propagation angle, s in the above formula is also a function that changes with the group angle; the LTI method calculates the travel time of point C and the coordinates of the intersection point D of the ray passing through AB and reaching C with AB through linear interpolation based on the known travel times of points A and B. Therefore, t a is the travel time of point A, and t bWhen traveling to point B, d1 is the distance between A and B, d2 is the distance between point A and the projection point E of point C projected vertically onto AB, l is the distance between the intersection point D and the projection point E; d3 is the distance between the projection point E and point C;

[0058] Step S23: Introduce anisotropic parameters into the traveltime linear interpolation (LTI) ray tracing algorithm, and we have:

[0059] Equation (2) is expressed as a function of l:

[0060]

[0061] In the equation, s p0 is the slowness of the qP wave in the vertical direction, and the value of l is between d2 - d1 and d1;

[0062] Substituting Equation (4) into Equation (3), we get

[0063]

[0064] In the equation, t pc is the traveltime for the ray passing through point D to reach point C with slowness s p , and the coordinates of point D can be expressed as:

[0065]

[0066] In the equation, x a , x b , x d are the abscissas at points A, B, and D respectively; z a , z d are the ordinates at points A and D respectively, r is the distance between point A and point D, and |AB| is the distance between point A and point B.

[0067] Furthermore, in the static correction calculation, the datum plane static correction and the first-arrival residual static correction based on the model are calculated respectively, including:

[0068] Module for calculating the datum plane static correction amount: For any position, the datum plane static correction needs to calculate the static correction amounts of the shot point and the geophone point respectively, and its calculation formula is as follows:

[0069]

[0070] In the equation, t represents the datum plane static correction amount of the shot point / geophone point, E g is the elevation of the shot point or the geophone point; E d is the elevation of the datum plane; h i , v i are the thickness and velocity of each layer in the low-velocity layer with reduced velocity respectively; v c is the velocity of the high-velocity layer; N is the number of layers in the low-velocity zone.

[0071] Module for calculating model-based first-arrival residual statics: The model-based first-arrival residual statics algorithm solves the residual statics by establishing a relationship curve model between the first-arrival time and the offset, and using the difference between the actual first-arrival time and the model-predicted time. Through surface-consistent decomposition, the shot-point and receiver-point residual statics for each trace are obtained respectively, as follows:

[0072] After determining the model trace, for the sth i shot and the rth j receiver, the difference in first-arrival time between the model trace and the actual trace can be expressed as:

[0073]

[0074] where represent the model first-arrival time and the actual first-arrival time respectively, and ΔT i,j can also represent the residual statics, which is the sum of the shot-point and receiver-point residual statics for this trace, i.e., ΔT i,j = T Si + T Rj . If there are j traces for the ith shot, summing the above equation gives:

[0075]

[0076] According to the assumption that the sum of the residual statics of all receivers in a common-shot gather is zero, the shot-point residual statics for the ith shot can be obtained through the following equation:

[0077]

[0078] Similarly, according to the assumption that the sum of the residual statics of all shots in a common-receiver gather is zero, the residual statics of any receiver can be obtained:

[0079]

[0080] In a third aspect, an electronic device is provided, including: a memory for storing a computer program; a processor for implementing the steps of the tomography statics method based on VTI media when executing the computer program.

[0081] In a fourth aspect, a computer-readable storage medium is provided, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the tomography statics method based on VTI media are implemented.

[0082] By adopting the above technical solutions, quantitative prediction of the hydrate saturation in a reservoir containing natural gas hydrates is achieved.

[0083] Compared with the prior art, the beneficial effects of the present invention are:

[0084] The present invention realizes a tomographic inversion method based on VTI media, significantly improving the accuracy and reliability of velocity modeling under complex near-surface conditions, and laying a solid foundation for high-precision static correction and seismic imaging. The research on target-driven static correction effectively solves the influence of complex near-surface on the static time shift of seismic data, laying a foundation for high-precision seismic imaging. Specifically, the present invention realizes a tomographic velocity modeling and target-driven static correction method based on VTI media. In the forward simulation, anisotropic parameters are introduced into the travel-time linear interpolation ray-tracing algorithm, and a calculation formula for the first-arrival travel time in VTI media is established. The iterative inversion adopts the LSQR algorithm, and a regularization constraint factor is added during the inversion process to increase the stability of the algorithm. In the static correction process, the datum plane static correction and the model-based first-arrival residual static correction amount are calculated respectively. The datum plane static correction corrects the seismic data to a unified horizontal plane, mainly solving the long-wavelength static correction amount to ensure the correct imaging of the structural morphology; the residual static correction aims at the influence of drastic elevation changes, compensating for the residual static correction amount after the datum plane static correction, solving the short-wavelength static correction problem, and further improving the imaging accuracy. By fusing and calculating the two static correction amounts and comparing their applications, target-driven static correction is carried out, effectively solving the influence of complex near-surface on the static time shift of seismic data and laying a foundation for high-precision seismic imaging. Description of the Drawings

[0085] Figure 1 It is a flowchart for implementing the tomographic inversion method based on VTI media according to an embodiment of the present invention;

[0086] Figure 2 It is a flowchart for implementing the specific details of the tomographic inversion method based on VTI media according to an embodiment of the present invention;

[0087] Figure 3 It is a flowchart for implementing the calculation of the first-arrival travel time in VTI media according to an embodiment of the present invention;

[0088] Figure 4 It is a flowchart for implementing the calculation of the static correction amount according to an embodiment of the present invention;

[0089] Figure 5 It is a structural diagram of the device for tomographic inversion based on VTI media according to an embodiment of the present invention;

[0090] Figure 6 It is a structural diagram of the unit for implementing the calculation of the first-arrival travel time in VTI media according to an embodiment of the present invention;

[0091] Figure 7 It is a structural diagram of the unit for implementing the static correction calculation according to an embodiment of the present invention

[0092] Figure 8It is a diagram of the travel-time geometric relationship of the first arrival wave in the VTI medium provided by an embodiment of the present invention;

[0093] Figure 9 It is a schematic diagram of the datum plane static correction provided by an embodiment of the present invention;

[0094] Figure 10 It is a comparison diagram of the travel times of the first arrival waves in the isotropic medium and the VTI medium provided by an embodiment of the present invention;

[0095] Figure 11 It is an effect diagram of near-surface tomography inversion provided by an embodiment of the present invention;

[0096] Figure 12 It is a comparison diagram of the static correction effects of actual data provided by an embodiment of the present invention;

[0097] Figure 13 It is a structural diagram of an electronic device provided by an embodiment of the present invention. Detailed implementation manners

[0098] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0099] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described here can be implemented in an order different from those illustrated or described here. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device including a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0100] At present, seismic data static correction processing assumes an isotropic medium. Due to the generally anisotropic characteristics of the earth's medium, conventional methods have significant limitations in the calculation of seismic wavefield travel times and the accuracy of velocity modeling, reducing the calculation accuracy of the static correction amount. The present invention realizes a tomographic static correction method based on VTI medium. The influence of anisotropy on wave propagation is considered in the forward simulation, significantly improving the calculation accuracy of wavefront travel times. Anisotropic parameters are introduced in the inversion to carry out tomographic inversion based on anisotropic media, significantly improving the accuracy of near-surface modeling, which is conducive to the accurate calculation of the static correction amount. The flow of this method is shown in the attached drawings, and its main steps include: 1) First arrival time picking, extracting the first arrival travel time data from the seismic records as the input for tomographic inversion. 2) Forward travel time calculation, establishing an initial velocity model in combination with the elevation information of the study area, and performing ray tracing and first arrival travel time calculation based on VTI medium. 3) Velocity inversion, using the regularized LSQR method to invert and obtain the velocity update amount, and modifying the model to obtain the updated near-surface velocity structure. 4) Static correction processing, calculating the datum plane static correction amount and the residual static correction amount of the shot points and geophone points according to the tomographic inversion velocity, and applying them to the seismic data to adjust the arrival time of the seismic waves, thereby eliminating the influence of near-surface heterogeneity on the seismic wave propagation time. This method effectively solves the influence of complex near-surface on the static time shift of seismic data, laying a foundation for high-precision seismic imaging.

[0101] Figure 1 It is a method implementation flowchart of the tomographic static correction method based on VTI medium provided according to an embodiment of the present invention. Figure 2 It is a specific detail implementation flowchart of the tomographic inversion method based on VTI medium provided according to an embodiment of the present invention. For the convenience of description, only the parts related to the embodiments of the present invention are shown and are described in detail as follows:

[0102] As Figure 1 、 2As shown in the figure, the method mainly includes the following steps: In the step of picking up the seismic first arrival time, a high-precision first arrival picking method is adopted, such as using measures to improve the signal-to-noise ratio of the original data, linear moveout correction, applying preliminary static correction amount and combining manual interactive picking with an automatic picking algorithm, and supplemented by quality control means to ensure the reliability of the first arrival time. In the step of ray tracing and first arrival travel time calculation, anisotropic parameters are introduced into the travel time linear interpolation (LTI) ray tracing algorithm, and the first arrival travel time calculation formula in VTI media is established. In the step of near-surface velocity tomography, the LSQR algorithm is used for iterative inversion, and a regularization constraint factor is added during the inversion process. In the static correction amount calculation step, the datum plane static correction and the first arrival residual static correction amount based on the model are calculated respectively. In the static correction step, the datum plane static correction amount is applied to solve the medium and long wavelength static correction problems to ensure the accuracy of the structural morphology; then the first arrival residual static correction amount is applied to solve the short wavelength static correction problems to further improve the accuracy and signal-to-noise ratio of the stacked imaging, and high-precision static correction processing is achieved through the fusion of the two methods.

[0103] Figure 3 It is a flow chart for implementing the first arrival travel time calculation in VTI media according to an embodiment of the present invention; Figure 8 It is a geometric relationship diagram of the first arrival travel time in VTI media according to an embodiment of the present invention; For the sake of description, only the parts related to the embodiment of the present invention are shown and are described in detail as follows:

[0104] Anisotropic parameters are introduced into the travel time linear interpolation (LTI) ray tracing algorithm, and the first arrival travel time calculation formula in VTI media is established. The relationship between the seismic wave field propagation speed and the propagation angle in VTI media is as follows:

[0105]

[0106] In the formula, v p represents the group velocity of the qP wave in VTI media, represents the angle between the group velocity and the vertical direction, δ and ε are dimensionless Thomsen anisotropic parameters, and v p0 is the vertical propagation velocity of the qP wave.

[0107] Let the coordinates of points A, B, and C be (x a , z a ), (x b , z b ), (x c , z c ) respectively, the travel times of points A, B, and D are t a , t b , t d respectively, and r is the distance from A to D, satisfying 0 ≤ r ≤ AB, is the angle between AB and AC. The core of the LTI method is to calculate the travel time of point C and the coordinates of the intersection point D of the ray passing through AB to C and AB based on the known travel times of points A and B through linear interpolation.

[0108] The LTI method calculates the travel time of point C and the coordinates of the intersection point D of the ray passing through AB to C and AB based on the known travel times of points A and B through linear interpolation. The geometric relationship of the first arrival travel time in VTI media is shown in the appendix Figure 2 According to the geometric relationship in the figure, the ray passes through point D on the AB boundary to reach point C, then the travel time t of point C c can be expressed as:

[0109]

[0110] In the formula, s represents the slowness near point C. Since the velocity in VTI media is a function of the propagation angle, s in the above formula is also a function that varies with the group angle. The meanings of l, d1, d2, and d3 in the formula are as shown in the appendix Figure 2 As shown, express formula (2) as a function of l:

[0111]

[0112] In the formula, s p0 is the slowness of the qP wave in the vertical direction. The value of l is between d2 - d1 and d1. Substituting it into formula (3) gives:

[0113]

[0114] where, t pc is the travel time for the ray passing through point D to reach point C with slowness s p . The coordinates of point D can be expressed as:

[0115]

[0116] The LTI algorithm adopts a forward-backward processing method, and its calculation process is divided into two steps. The first step: forward processing, calculating the propagation time of seismic waves. According to formula (5), calculate the travel times from the shot point to the discrete points on the boundaries of each grid cell, and finally determine the minimum travel time of the receiving point. The second step: backward processing, determining the propagation path of seismic waves. Based on Fermat's principle, trace the ray path of the first arrival wave and determine the intersection coordinates of the ray and the boundaries of each grid cell according to formula (6).

[0117] Figure 4 is the flow chart for calculating the static correction amount provided according to the embodiment of the present invention; Figure 9 is the schematic diagram of the datum plane static correction provided according to the embodiment of the present invention; For ease of description, only the parts related to the embodiment of the present invention are shown and are described in detail as follows:

[0118] In step S4, in the static correction amount calculation, the datum plane static correction and the first-arrival wave residual static correction amount based on the model are calculated respectively, including:

[0119] Step S41, calculate the datum plane static correction amount: For any position, the static correction amounts of the shot point and the geophone need to be calculated respectively for the datum plane static correction, and the calculation formula is as follows:

[0120]

[0121] In the formula, t represents the datum plane static correction amount of the shot point / geophone, E g is the elevation of the shot point or the geophone; E d is the elevation of the datum plane; h i , v i are the thickness and velocity of each layer in the low-velocity layer; v c is the velocity of the high-velocity layer; N is the number of layers in the low-velocity zone.

[0122] Step S42, calculate the first-arrival wave residual static correction amount based on the model: The first-arrival wave residual static correction algorithm based on the model solves the residual static correction amount by establishing a relationship curve model between the first-arrival time and the shot-receiver offset, and through surface-consistent decomposition, the residual static correction amounts of the shot point and the geophone for each trace are obtained respectively, as follows:

[0123] After determining the model trace, the difference in the first-arrival time between the model trace and the actual trace of the Rth receiver of the Sth shot can be expressed as: i shot and the Rth j receiver point can be expressed as:

[0124]

[0125] In the formula, represent the model first-arrival time and the actual first-arrival time respectively, and ΔT i,j can also represent the residual static correction amount, which is the sum of the residual static correction amounts of the shot point and the geophone for this trace, that is, ΔT i,j = T Si + T Rj . If there are j traces for the ith shot, summing the above formula gives:

[0126]

[0127] Assuming that the sum of the residual static correction amounts of all geophones in the common-shot gather is zero, the residual static correction amount of the shot point of the ith shot can be obtained through the following formula:

[0128]

[0129] Similarly, according to the condition that the sum of the residual statics of all shot points in each common geophone gather is zero, the residual statics of any geophone can be obtained:

[0130]

[0131] In step S5, the datum statics corrects the seismic data to a unified horizontal plane, mainly solving the long-wavelength statics to ensure the correct imaging of the structural morphology; the residual statics, on the other hand, aims at the influence of drastic elevation changes, compensating for the residual statics after the datum statics and solving the short-wavelength statics problem to further improve the imaging accuracy.

[0132] Figure 5 FIG. is a structural diagram of a tomography inversion device based on VTI media according to an embodiment of the present invention; Figure 6 FIG. is a structural diagram of a first arrival travel time calculation implementation unit in VTI media according to an embodiment of the present invention; Figure 7 FIG. is a structural diagram of a statics calculation implementation unit according to an embodiment of the present invention; for ease of description, only the parts related to the embodiments of the present invention are shown and are described in detail as follows:

[0133] The tomography statics correction device based on VTI media includes: a seismic first arrival picking unit: picking the seismic first arrival time by using a high-precision first arrival picking method; a ray tracing and first arrival travel time calculation unit: introducing anisotropic parameters into the travel time linear interpolation (LTI) ray tracing algorithm to establish a first arrival travel time calculation formula in VTI media; a near-surface velocity tomography inversion unit: performing iterative inversion by using the LSQR algorithm and adding a regularization constraint factor during the inversion process; a statics calculation unit: calculating the datum statics and the first arrival residual statics based on the model respectively; a statics correction unit: based on the statics calculated by the statics calculation unit, applying the datum statics to solve the medium- and long-wavelength statics problems and ensuring the accuracy of the structural morphology; then applying the first arrival residual statics to solve the short-wavelength statics problem to further improve the accuracy and signal-to-noise ratio of the stacked imaging, and realizing high-precision statics correction processing through the fusion of the two methods.

[0134] Further, in the ray tracing and first arrival travel time calculation unit, introducing anisotropic parameters into the travel time linear interpolation (LTI) ray tracing algorithm to establish a first arrival travel time calculation formula in VTI media includes: a first module: establishing the relationship between the seismic wave field propagation velocity and the propagation angle in VTI media as follows:

[0135]

[0136] In the formula, v p represents the group velocity of the qP wave in VTI media, denotes the angle between the group velocity and the vertical direction, δ and ε are dimensionless Thomsen anisotropy parameters, and v p0 is the vertical propagation velocity of the qP wave;

[0137] Second module: Calculate the travel time of the first arrival wave in VTI medium based on the travel time linear interpolation (LTI) ray tracing algorithm as follows: The travel time t at point C c can be expressed as:

[0138]

[0139] where s represents the slowness near point C. Since the velocity in VTI medium is a function of the propagation angle, s in the above formula is also a function that varies with the group angle; The LTI method calculates the travel time at point C and the coordinates of the intersection point D of the ray passing through AB to C with AB by linear interpolation based on the known travel times at points A and B. Therefore, t a is the travel time at point A, t b is the travel time at point B, d1 is the distance between A and B, d2 is the distance between the projection point E of point C perpendicular to AB and point A, l is the distance between the intersection point D and the projection point E; d3 is the distance between the projection point E and point C;

[0140] Step S23: Introduce the anisotropy parameters into the travel time linear interpolation (LTI) ray tracing algorithm, and we have:

[0141] Equation (2) is expressed as a function of l:

[0142]

[0143] where s p0 is the slowness of the qP wave in the vertical direction, and the value of l is between d2 - d1 and d1;

[0144] Substituting Equation (4) into Equation (3) gives

[0145]

[0146] where t pc is the travel time for the ray passing through point D to reach point C with slowness s p , and the coordinates of point D can be expressed as:

[0147]

[0148] where x a , x b , x d are the abscissas at points A, B, and D respectively; z a , z d are the ordinates at points A and D respectively, r is the distance between point A and point D, and |AB| is the distance between point A and point B.

[0149] Furthermore, in static correction calculation, datum plane static correction and model-based first arrival residual static correction are calculated respectively, including:

[0150] Datum plane static correction calculation module: For any position, the static correction of the datum plane needs to calculate the static correction of the shot point and the receiver point respectively, and its calculation formula is as follows:

[0151]

[0152] In the formula, t represents the static correction of the shot point / receiver point to the datum plane, E g is the elevation of the shot point or receiver point; E d is the elevation of the datum plane; h i , v i are the thickness and velocity of each layer in the low-velocity layer respectively; v c is the velocity of the high-velocity layer; N is the number of layers in the low-velocity zone.

[0153] Model-based first arrival residual static correction calculation module: The model-based first arrival residual static correction algorithm solves the residual static correction by establishing a relationship curve model between the first arrival time and the shot-receiver offset, and uses the difference between the actual first arrival time and the model predicted time. Through surface-consistent decomposition, the residual static correction of the shot point and the receiver point of each trace is obtained respectively, as follows:

[0154] After determining the model trace, the difference in the first arrival time between the model trace and the actual trace at the R i th receiver point of the S j th shot can be expressed as:

[0155]

[0156] In the formula, represent the model first arrival time and the actual first arrival time respectively, and ΔT i,j can also represent the residual static correction, which is the sum of the residual static corrections of the shot point and the receiver point of this trace, that is, ΔT i,j = T Si + T Rj . If there are j traces for the i-th shot, summing the above formula gives:

[0157]

[0158] Assuming that the sum of the residual static corrections of all receiver points in the common shot gather is zero, the residual static correction of the shot point of the i-th shot can be obtained through the following formula:

[0159]

[0160] Similarly, according to the fact that the sum of the residual static corrections of all shot points in each common detection point gather is zero, the residual static correction of any detection point can be obtained:

[0161]

[0162] Figure 10 This is a comparison diagram of the first arrival wave travel time of an isotropic medium and a VTI medium provided according to an embodiment of the present invention; for ease of description, only the part related to the embodiment of the present invention is shown, which is described in detail as follows:

[0163] The forward modeling methods of isotropic medium and VTI medium are used to calculate the first arrival wave travel time. Affected by the fluctuation of the surface, the theoretically calculated first arrival wave travel time no longer shows a linear feature, showing a time shift phenomenon and highlighting the need for static correction. Data comparison shows that in the area near the shot point, the first arrival times calculated by the two methods are highly consistent. With the increase of the offset distance, the difference in the first arrival time gradually becomes significant, indicating that with the increase of the offset distance or the increase of the depth, the anisotropy of the formation medium has a greater impact on the propagation of the seismic wave field. The first arrival travel time in the VTI medium is significantly shortened, indicating that the seismic wave has a higher propagation speed in this medium.

[0164] Figure 11 This is a near-surface tomography inversion effect diagram provided according to an embodiment of the present invention; for ease of description, only the part related to the embodiment of the present invention is shown, which is described in detail as follows:

[0165] A high-precision near-surface velocity model is obtained through VTI medium tomography inversion. The basic equation of velocity tomography is as follows:

[0166] Ax=t (1)

[0167] Where A represents the Jacobian coefficient matrix formed by the geometric path of seismic rays; x represents the underground slowness model (slowness is the inverse of velocity); t represents the travel time information of the first arrival wave picked up from the seismic data. Seismic tomography inversion is to solve equation (1) to obtain the velocity value in the underground grid unit.

[0168] The iterative inversion adopts the LSQR algorithm, and a regularization constraint factor is added in the inversion process.

[0169] For the seismic ray travel time equation of the form Ax = t, after linearization and discretization, the LSQR inversion equation group can be expressed as:

[0170] AΔx=Δt (7)

[0171] A is the coefficient matrix, whose elements are equal to the ray path lengths within the grid and are obtained through forward ray tracing calculations; Δt is the difference between the picked actual first arrival time and the first arrival time obtained from forward ray tracing; Δx is the slowness update vector, which is the quantity to be solved in the LSQR tomography inversion. For areas with extremely complex near-surface structures, the inversion results have strong non-uniqueness. The present invention constrains the inversion results by adding a regularization factor. The regularized LSQR inversion equation system can be expressed as:

[0172]

[0173] In the formula, x’ is the initial model, λ is the regularization constraint factor. The larger the regularization factor, the stronger the role of the prior constraint; W is an L×N-dimensional matrix, L is the number of constrained parameters, N is the number of parameters to be obtained, and:

[0174]

[0175] The equation system (8) is simplified into the form of Ax = b, and then the LSQR algorithm is used to solve it. The main iterative process is as follows.

[0176] Initialization:

[0177]

[0178] Tri-diagonalization:

[0179]

[0180] Orthogonal transformation:

[0181]

[0182] Solution vector:

[0183]

[0184] Convergence condition: When the number of iterations increases, if the obtained solution does not change significantly, the iteration can be stopped. Alternatively, the inversion results can be output after a certain number of iterations are satisfied.

[0185] In the above iterative formulas, a and b are scalar sequences of the tri-diagonalized matrix A, u and v are vector sequences, λ is the regularization factor, and the rest are intermediate variables.

[0186] Such as Figure 11As shown in the figure, a seismic first-arrival traveltime tomography method based on VTI media was adopted to inversely obtain a high-precision near-surface velocity model. The actual data is located on the southwestern margin of the Ordos Basin. The geomorphology of the seismic exploration area here is complex, mainly including three types: river valleys and flatlands, loess plateaus and gullies. The overall terrain is low in the west and high in the east. The highest altitude of the plateau surface is about 1175 m, and the lowest altitude of the gully is about 846 m, with a relative elevation difference of about 329 m. Most of it is covered by loess layers, and the bedrock is exposed in the gully part. The surface coverage condition is complex, the thickness of the shallow low-velocity zone is uneven and the lateral velocity varies greatly, which has a significant impact on the propagation of seismic waves. Figure 11 a is the initial velocity model for tomography inversion. It can be seen that the surface undulates violently and the elevation changes greatly. Based on the top interface of the high-velocity layer, the velocity is simply divided into two layers. Figure 11 b is the updated velocity after inversion. The lateral variation of the shallow velocity is significant, and the thickness distribution of the low-velocity layer is uneven. In some areas, the thickness of the low-velocity layer becomes thinner or even disappears, which is consistent with the geological characteristics of the bedrock exposure in the gully section of the loess plateau exploration area. Based on the method of the present invention, a high-resolution near-surface velocity distribution was successfully obtained.

[0187] Figure 12 It is a comparison diagram of the static correction effect of the actual data provided according to the embodiment of the present invention; for the convenience of description, only the part related to the embodiment of the present invention is shown and is described in detail as follows:

[0188] The datum plane static correction corrects the seismic data to a unified horizontal plane, which is mainly used to solve the long-wavelength static correction problem and ensure the accurate imaging of the structural morphology; the residual static correction is aimed at the influence of the drastic change in elevation, compensates for the residual static correction amount after the datum plane static correction, solves the short-wavelength static correction problem, and further improves the imaging accuracy. The surface elevation of this profile is between 900 and 1150 m, with large undulations and relatively drastic changes ( Figure 12 a). Due to the existence of a large static correction problem, the data before field static correction cannot be stacked in phase, making it difficult to perform correct imaging, and the reflection wave of the main target layer cannot be identified ( Figure 12 b). The datum plane static correction better solves the influence of surface undulation and lateral variation of near-surface velocity on seismic data, and obtains better structural imaging. The continuity of the reflection wave homophase axis of the bottom interface of the Cenozoic and the coal seam is good, and the occurrence condition is clear ( Figure 12 c). This shows that the tomography inversion static correction has achieved good results because the tomography inversion method based on VTI media constructs a more accurate near-surface velocity model, laying a good foundation for the calculation of static correction amounts. In the thick loess area (mountain ridges, plateaus), affected by the drastic changes in near-surface elevation and velocity structure, there is still a certain amount of residual static correction in this area, manifested as low signal-to-noise ratio and poor continuity of the profile. Through the first-arrival wave residual static correction, the continuity of the homophase axis and the signal-to-noise ratio of the local profile are improved, and the imaging quality is further improved ( Figure 12d). By comprehensively applying datum static correction and residual static correction, the influence of complex near-surface on the static time shift of seismic data can be effectively solved, laying a foundation for high-precision seismic imaging.

[0189] Figure 13 The following is a structural diagram of an electronic device provided by an embodiment of the present invention. As Figure 13 shown, the device includes: a memory 21 for storing computer programs; a processor 22 for implementing the steps of the tomography inversion method based on VTI media when executing the computer programs. Among them, the processor 22 may include one or more processing cores, such as a 4-core processor, an 8-core processor, etc. The processor 22 may be implemented in at least one hardware form of a digital signal processor (DSP), a field-programmable gate array (FPGA), or a programmable logic array (PLA). The processor 22 may also include a main processor and a coprocessor. The main processor is a processor for processing data in the wake state, also known as a central processing unit (CPU); the coprocessor is a low-power processor for processing data in the standby state. In some embodiments, the processor 22 may be integrated with a graphics processing unit (GPU), and the GPU is responsible for rendering and drawing the content to be displayed on the display screen. In some embodiments, the processor 22 may further include an artificial intelligence (AI) processor, and the AI processor is used to process computational operations related to machine learning.

[0190] The memory 21 may include one or more computer-readable storage media, and the computer-readable storage media may be non-transitory. The memory 21 may further include high-speed random access memory and non-volatile memory, such as one or more disk storage devices and flash storage devices. In this embodiment, the memory 21 is at least used to store the following computer program 211. After the computer program is loaded and executed by the processor 22, it can implement the relevant steps of the steps of the tomography inversion method based on VTI media disclosed in any of the foregoing embodiments. In addition, the resources stored in the memory 21 may further include an operating system 212 and data 213, etc., and the storage method may be temporary storage or permanent storage. Among them, the operating system 212 may include Windows, Unix, Linux, etc. The data 213 may include, but is not limited to, data involved in the tomography inversion method based on VTI media, etc.

[0191] In some embodiments, the electronic device may further include a display screen 23, an input / output interface 24, a communication interface 25, a power supply 26, and a communication bus 27.

[0192] Those skilled in the art can understand that Figure 13 the structure shown in does not constitute a limitation on the electronic device, and it may include more or fewer components than those shown in the figure.

[0193] The processor 22 implements the steps of the tomographic inversion method based on the VTI medium provided in any of the above embodiments by calling the instructions stored in the memory 21.

[0194] For the introduction of an electronic device provided by the present invention, please refer to the above method embodiments. The present invention will not be elaborated herein again, and it has the same beneficial effects as the steps of the above tomographic inversion method based on the VTI medium.

[0195] Furthermore, the present invention also provides a computer-readable storage medium. A computer program is stored on the computer-readable storage medium. When the computer program is executed by the processor 22, it implements the steps of the tomographic inversion method based on the VTI medium as described above. It can be understood that if the method in the above embodiments is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and executes all or part of the steps of the methods in various embodiments of the present invention. The aforementioned storage medium includes: USB flash drives, mobile hard disks, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical discs, etc., which can store program codes.

[0196] For the introduction of a computer-readable storage medium provided by the present invention, please refer to the above method embodiments. The present invention will not be elaborated herein again, and it has the same beneficial effects as the steps of the above tomographic inversion method based on the VTI medium.

[0197] The above has introduced in detail a tomography inversion method, apparatus, device, and medium based on VTI media provided by the present invention. The various embodiments in the specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference can be made to each other. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple. For related parts, reference can be made to the description in the method part. It should be noted that for those of ordinary skill in the art in the technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the present invention.

[0198] It should also be noted that in this specification, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including", or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the existence of additional identical elements in the process, method, article, or device comprising the element.

Claims

1. A tomography static correction method based on VTI media, characterized in that, It includes the following steps: Step S1, picking up seismic first-arrival waves: picking up the seismic first-arrival wave time by using a high-precision first-arrival picking method; Step S2, ray tracing and first-arrival travel-time calculation: introducing anisotropic parameters into the travel-time linear interpolation (LTI) ray-tracing algorithm, and establishing the first-arrival travel-time calculation formula in VTI media; Step S3, near-surface velocity tomographic inversion: using the LSQR algorithm for iterative inversion, and adding a regularization constraint factor during the inversion process; Step S4, static correction calculation: calculating the datum plane static correction and the first-arrival wave residual static correction based on the model respectively; Step S5, performing static correction: based on the static correction calculated in Step S4, applying the datum plane static correction to solve the medium- and long-wavelength static correction problems and ensure the accuracy of the structural morphology; then applying the first-arrival wave residual static correction to solve the short-wavelength static correction problem, further improving the accuracy and signal-to-noise ratio of the stacked imaging, and achieving high-precision static correction processing through the fusion of the two methods.

2. The tomographic static correction method based on VTI media according to claim 1, wherein In the said Step S1, when picking up seismic first-arrival waves and picking up the seismic first-arrival wave time by using a high-precision first-arrival picking method, it includes: Combining the method of improving the signal-to-noise ratio of the original data, the linear dynamic correction method, applying the preliminary static correction amount and manual interactive picking with the automatic picking algorithm, and supplementing with quality control means to pick up the seismic first-arrival wave time to ensure the reliability of the picked first-arrival time.

3. The tomographic static correction method based on VTI media according to claim 1, wherein In the said Step S2, when introducing anisotropic parameters into the travel-time linear interpolation (LTI) ray-tracing algorithm in ray tracing and first-arrival travel-time calculation and establishing the first-arrival travel-time calculation formula in VTI media, it includes: Step S21: Establishing the relationship between the seismic wavefield propagation velocity and the propagation angle in VTI media as follows: where \(v\) p represents the group velocity of the qP wave in the VTI medium, represents the angle between the group velocity and the vertical direction, \(\delta\) and \(\varepsilon\) are dimensionless Thomsen anisotropy parameters, and \(v\) p0 is the vertical propagation velocity of the qP wave; Step S22: Calculate the travel time of the first arrival wave in the VTI medium based on the Linear Interpolation on Traveltime (LTI) ray tracing algorithm as follows: The travel time t of point C c can be expressed as: In the formula, s represents the slowness near point C. Since the velocity in VTI medium is a function of the propagation angle, s in the above formula is also a function of the group angle. The LTI method calculates the travel time of point C and the coordinates of the intersection point D of the ray passing through AB to C with AB by linear interpolation based on the known travel times of points A and B. Therefore, t a is the travel time of point A, t b is the travel time of point B, d1 is the distance between A and B, d2 is the distance between the projection point E of point C vertically projected onto AB and point A, l is the distance between the intersection point D and the projection point E; d3 is the distance between the projection point E and point C; Step S23: Introducing anisotropic parameters into the travel-time linear interpolation (LTI) ray-tracing algorithm, and having: Equation (2) is expressed as a function of l: where s p0 is the slowness in the vertical direction of the qP wave, and the value of l is between d2 - d1 and d1; Substituting Equation (4) into Equation (3) gives where t pc is the travel time for the ray passing through point D with slowness s p to reach point C, and the coordinates of point D can be expressed as: where x a , x b , x d are the abscissas of points A, B, and D respectively; z a , z d are the ordinates of points A and D respectively, r is the distance between points A and D, and |AB| is the distance between points A and B.

4. The tomography static correction method based on VTI media according to claim 3, characterized in that, In the said Step S4, when calculating the static correction amount and calculating the datum plane static correction and the first-arrival wave residual static correction based on the model respectively, it includes: Step S41, calculating the datum plane static correction amount: For any position, the datum plane static correction needs to calculate the static correction amounts of the shot point and the geophone point respectively, and its calculation formula is as follows: In the formula, t represents the static correction amount of the shot / receiver datum plane, E g is the elevation of the shot or receiver; E d is the elevation of the datum plane; h i , v i are the thickness and velocity of each layer in the low-velocity layer with decreasing velocity; v c is the velocity of the high-velocity layer; N is the number of layers in the low-velocity zone. Step S42, calculating the first-arrival wave residual static correction based on the model: The first-arrival wave residual static correction algorithm based on the model solves the residual static correction amount by establishing the relationship curve model between the first-arrival time and the shot-receiver offset, and uses the difference between the actual first-arrival time and the model predicted time, and through surface-consistent decomposition, the shot point and geophone point residual static correction amounts of each trace are obtained respectively, as follows: After determining the model trace, the Sth i shot and the Rth j The first arrival time difference between the model trace and the actual trace at the receiver can be expressed as: In the formula, respectively represent the model first arrival time and the actual first arrival time, ΔT i,j can also represent the residual static correction amount, which is the sum of the residual static correction amounts of the shot point and the receiver point of this trace, that is, ΔT i,j = T Si + T Rj , if there are j traces in the i-th shot, summing up the above formula gives: According to the assumption that the sum of the residual static correction amounts of all geophone points in the common shot gather is zero, the shot point residual static correction amount of the i-th shot can be obtained through the following formula: Similarly, according to the fact that the sum of the residual static correction amounts of all shot points in each common geophone gather is zero, the residual static correction amount of any geophone point can be obtained:

5. A tomographic static correction device based on VTI media, characterized in that, It includes: Seismic first-arrival wave picking unit: picking up the seismic first-arrival wave time by using a high-precision first-arrival picking method; Ray tracing and first arrival travel time calculation unit: Anisotropic parameters are introduced into the travel time linear interpolation (LTI) ray tracing algorithm, and the calculation formula for the first arrival travel time in VTI media is established; Near-surface velocity tomographic inversion unit: The LSQR algorithm is used for iterative inversion, and a regularization constraint factor is added during the inversion process; Static correction calculation unit: Calculate the datum plane static correction and the first arrival residual static correction based on the model respectively; Static correction implementation unit: Based on the static correction calculated by the static correction calculation unit, the datum plane static correction is applied to solve the medium and long wavelength static correction problems to ensure the accuracy of the structural morphology; then the first arrival residual static correction is applied to solve the short wavelength static correction problem, further improving the accuracy and signal-to-noise ratio of the stacked imaging. High-precision static correction processing is achieved through the fusion of the two methods.

6. The tomography static correction device based on VTI medium according to claim 5, characterized in that, In the seismic first arrival picking unit, a high-precision first arrival picking method is used to pick the seismic first arrival time, including: Combining methods such as improving the signal-to-noise ratio of the original data, linear dynamic correction, applying preliminary static correction, and manual interaction picking with an automatic picking algorithm, and supplemented by quality control means to pick the seismic first arrival time to ensure the reliability of the picked first arrival time.

7. The tomographic static correction device based on VTI media according to claim 5, characterized in that, In the ray tracing and first arrival travel time calculation unit, anisotropic parameters are introduced into the travel time linear interpolation (LTI) ray tracing algorithm, and the calculation formula for the first arrival travel time in VTI media is established, including: First module: Establish the relationship between the seismic wave field propagation velocity and the propagation angle in VTI media as follows: where \(v\) p represents the group velocity of the qP-wave in the VTI medium, represents the angle between the group velocity and the vertical direction, \(\delta\) and \(\varepsilon\) are dimensionless Thomsen anisotropy parameters, and \(v\) p0 is the vertical propagation velocity of the qP-wave; Second module: Calculate the travel time of the first arrival wave in VTI media based on the linear traveltime interpolation (LTI) ray tracing algorithm as follows: The travel time t of point C c can be expressed as: In the formula, s represents the slowness near point C. Since the velocity in VTI media is a function of the propagation angle, s in the above formula is also a function of the group angle. The LTI method calculates the travel time at point C and the coordinates of the intersection point D of the ray passing through AB to reach point C with AB based on the known travel times at points A and B through linear interpolation. Therefore, t a is the travel time at point A, t b is the travel time at point B, d1 is the distance between A and B, d2 is the distance between the projection point E of point C onto AB and point A, l is the distance between the intersection point D and the projection point E; d3 is the distance between the projection point E and point C; Step S23: Introduce anisotropic parameters into the travel time linear interpolation (LTI) ray tracing algorithm, and we have: Equation (2) is expressed as a function of l: where s p0 is the slowness in the vertical direction of the qP wave, and the value of l is between d2 - d1 and d1; Substituting Equation (4) into Equation (3) gives where t pc is the travel time for the ray passing through point D with slowness s p to reach point C, and the coordinates of point D can be expressed as: where x a , x b , x d are the abscissas of points A, B, and D respectively; z a , z d are the ordinates of points A and D respectively, r is the distance between points A and D, and |AB| is the distance between points A and B.

8. The tomography static correction method based on VTI media according to claim 7, wherein In step S4, when calculating the static correction, the datum plane static correction and the first arrival residual static correction based on the model are calculated respectively, including: Datum plane static correction calculation module: For any position, the datum plane static correction needs to calculate the static correction of the shot point and the receiver point respectively, and its calculation formula is as follows: In the formula, t represents the static correction amount of the shot point / check point datum plane, E g is the elevation of the shot point or check point; E d is the elevation of the datum plane; h i , v i are the thickness and velocity of each layer in the low-velocity layer with decreasing velocity respectively; v c is the velocity of the high-velocity layer; N is the number of layers in the low-velocity zone. First arrival residual static correction calculation module based on the model: The first arrival residual static correction algorithm based on the model solves the residual static correction by establishing a relationship curve model between the first arrival time and the shot-receiver offset, and using the difference between the actual first arrival time and the model predicted time. Through surface consistent decomposition, the shot point and receiver point residual static corrections of each trace are obtained respectively, as follows: After determining the model trace, the Sth i shot and the Rth j The travel-time difference between the model trace and the actual trace at the receiver can be expressed as: In the formula, respectively represent the model first arrival time and the actual first arrival time, and ΔT i,j can also represent the residual static correction amount, which is the sum of the residual static correction amounts of the shot point and the geophone point of this trace, that is, ΔT i,j = T Si + T Rj , if there are j traces in the i-th shot, summing up the above formula gives: According to the assumption that the sum of the receiver point residual static corrections in all receiver gathers of a common shot gather is zero, the shot point residual static correction of the i-th shot can be obtained through the following formula: Similarly, according to the assumption that the sum of the shot point residual static corrections in all shot gathers of a common receiver gather is zero, the residual static correction of any receiver point can be obtained:

9. An electronic device, characterized in that, Including: A memory for storing computer programs; A processor for implementing the steps of the tomographic static correction method based on VTI media as described in any one of claims 1-4 when executing the computer program.

10. A computer-readable storage medium, characterized in that, The computer program is stored on a computer-readable storage medium, and when the computer program is executed by the processor, it implements the steps of the tomographic static correction method based on VTI media as described in any one of claims 1-4.

Images