Azimuth anisotropy equivalent parameter prestack migration imaging method and device

Abstract

The application discloses an azimuth anisotropy equivalent parameter prestack migration imaging method and device, which generates a migration distance-azimuth angle imaging gather and an initial migration stacking profile according to prestack seismic data and a migration velocity model; inverses three azimuth anisotropy equivalent parameters corresponding to an anisotropic medium with a horizontal symmetry axis according to a pre-constructed target prestack time migration algorithm, the migration distance-azimuth angle imaging gather and the initial migration stacking profile, respectively determines each azimuth anisotropy equivalent parameter model; and generates a target imaging gather and a target migration stacking profile according to each azimuth anisotropy equivalent parameter model and the prestack seismic data. Since the application is based on the pre-constructed target prestack time migration algorithm and inverses the three azimuth anisotropy equivalent parameters simultaneously, errors caused by step-by-step parameter estimation are reduced, and the problems of the existing azimuth anisotropy prestack migration imaging technology in terms of parameter modeling efficiency and accuracy are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of seismic exploration, in particular to a method and device for azimuth anisotropy equivalent parameter prestack migration imaging. BACKGROUND

[0002] For complex geological structures with anisotropy, the anisotropy of the stratum needs to be considered when performing seismic imaging, mainly including transverse isotropic medium with vertical symmetry axis (VTI) and transverse isotropic medium with horizontal symmetry axis (HTI).

[0003] The prior art mainly uses wide-azimuth seismic data to consider the influence of azimuth anisotropy based on HTI approximate fitting velocity ellipse. Since velocity analysis and migration imaging need to be performed in different directions, the accuracy and efficiency are usually relatively low. In addition, orthogonal anisotropy can also be used for processing. The existing orthogonal anisotropy technology generally uses VTI+HTI step-by-step parameter estimation method to independently calculate the step-by-step parameters, which is easy to neglect one aspect and pay attention to another aspect, resulting in deficiencies in modeling efficiency and accuracy.

[0004] Therefore, the existing azimuth anisotropy prestack migration imaging technology has obvious deficiencies in parameter modeling efficiency and accuracy.

[0005] Therefore, the prior art still needs to be improved and developed. SUMMARY

[0006] The technical problem to be solved by the present application is to provide a method and device for azimuth anisotropy equivalent parameter prestack migration imaging, aiming at solving the problem of deficiencies in parameter modeling efficiency and accuracy of the existing azimuth anisotropy prestack migration imaging technology.

[0007] The technical scheme adopted by the present application to solve the problem is as follows:

[0008] In a first aspect, the present application provides a method for azimuth anisotropy equivalent parameter prestack migration imaging, wherein the method comprises:

[0009] obtaining prestack seismic data and migration velocity model corresponding to a target work area, generating offset-azimuth imaging gathers and initial migration stack section according to the prestack seismic data and the migration velocity model;

[0010] inverting three azimuth anisotropy equivalent parameters corresponding to anisotropic medium with horizontal symmetry axis according to a pre-constructed target prestack time migration algorithm, the offset-azimuth imaging gathers and the initial migration stack section, determining an azimuth anisotropy equivalent parameter model corresponding to each of the azimuth anisotropy equivalent parameters;

[0011] The target imaging gathers and the target migration stack section are generated according to the anisotropy equivalent parameter models and the pre-stack seismic data.

[0012] In an implementation method, the method for constructing the target pre-stack time migration algorithm comprises:

[0013] A traveltime function is constructed according to the pre-stack seismic data parameters and the anisotropy equivalent parameters.

[0014] The target pre-stack time migration algorithm is determined according to the traveltime function and the pre-stack time migration algorithm.

[0015] In an implementation method, the traveltime function comprises:

[0016]

[0017] wherein h r is a horizontal distance from an imaging point to a shot point or a receiver point, a is an azimuth angle of a shot-receiver point, t0 is a two-way time depth, W avg , W cos , W sin are the anisotropy equivalent parameters respectively.

[0018] In an implementation method, the three anisotropy equivalent parameters corresponding to the anisotropy medium with a horizontal symmetry axis are inverted according to the pre-constructed target pre-stack time migration algorithm, the offset-azimuth imaging gathers and the initial migration stack section, comprising:

[0019] A plurality of initial time windows and local offset-azimuth imaging gathers corresponding to each of the initial time windows are determined according to the offset-azimuth imaging gathers and the initial migration stack section.

[0020] The anisotropy equivalent parameters are inverted according to each of the initial time windows, each of the local offset-azimuth imaging gathers and the target pre-stack time migration algorithm.

[0021] In an implementation method, the plurality of initial time windows and the local offset-azimuth imaging gathers corresponding to each of the initial time windows are determined according to the offset-azimuth imaging gathers and the initial migration stack section, comprising:

[0022] A plurality of initial time windows are selected at local positions of reflection symmetry axes on the initial migration stack section with a horizontal position interval;

[0023] The local offset-azimuth imaging gathers corresponding to each of the initial time windows on the offset-azimuth imaging gathers are extracted according to each of the initial time windows.

[0024] In an implementation method, the inverting each of the azimuthal anisotropy equivalent parameters according to each of the initial time window, each of the local offset-azimuth angle imaging gathers and the target prestack time migration algorithm comprises:

[0025] constructing a target optimization function based on the target prestack time migration algorithm;

[0026] inverting each of the azimuthal anisotropy equivalent parameters according to each of the initial time window, each of the local offset-azimuth angle imaging gathers and the target optimization function.

[0027] In an implementation method, the target optimization function comprises:

[0028]

[0029] wherein J represents the target optimization function, ||·|| represents a norm, w(Δt) represents a cross-correlation time-shifted summation function, T(Δt) represents a weighting function, Δt represents a time sampling rate, W avg , W cos , W sin respectively represent the azimuthal anisotropy equivalent parameters;

[0030]

[0031] wherein i is a trace index number, C[.] is a cross-correlation calculation, I is a local offset-azimuth angle imaging gather calculated based on the target prestack time migration algorithm, h represents an offset distance from a shot point to a receiver, a is a shot-receiver azimuth angle, and t1 is a time window center time.

[0032] In a second aspect, the embodiments of the present application further provide a device for azimuthal anisotropy equivalent parameter prestack migration imaging, wherein the device comprises:

[0033] an initial imaging module, configured to acquire prestack seismic data and a migration velocity model corresponding to a target work area, and generate offset-azimuth angle imaging gathers and an initial migration summation profile according to the prestack seismic data and the migration velocity model;

[0034] a parameter inversion module, configured to invert three azimuthal anisotropy equivalent parameters corresponding to an anisotropic medium with a horizontal symmetry axis according to a preconstructed target prestack time migration algorithm, the offset-azimuth angle imaging gathers and the initial migration summation profile, and determine an azimuthal anisotropy equivalent parameter model corresponding to each of the azimuthal anisotropy equivalent parameters;

[0035] a target imaging module, configured to generate target imaging gathers and a target migration summation profile according to each of the azimuthal anisotropy equivalent parameter models and the prestack seismic data.

[0036] In a third aspect, an embodiment of the present application further provides a terminal, comprising a memory and one or more processors; the memory stores one or more programs; the programs contain instructions for executing the azimuth anisotropy equivalent parameter pre-stack migration imaging method according to any one of the above aspects; and the processors are configured to execute the programs.

[0037] In a fourth aspect, an embodiment of the present application further provides a computer readable storage medium, which stores a plurality of instructions, wherein the instructions are adapted to be loaded and executed by a processor to implement the azimuth anisotropy equivalent parameter pre-stack migration imaging method according to any one of the above aspects.

[0038] The present application has the following beneficial effects: the embodiment of the present application obtains pre-stack seismic data corresponding to a target work area, generates offset-bazimuth imaging gathers and initial migration stacking profiles in the offset-bazimuth domain according to the pre-stack seismic data, inverses three azimuth anisotropy equivalent parameters corresponding to an anisotropic medium with a horizontal symmetry axis according to a pre-constructed target pre-stack time migration algorithm, the offset-bazimuth imaging gathers and the initial migration stacking profiles, determines azimuth anisotropy equivalent parameter models corresponding to the azimuth anisotropy equivalent parameters, and generates target imaging gathers and target migration stacking profiles according to the azimuth anisotropy equivalent parameter models and the pre-stack seismic data. Since the present application is based on the pre-constructed target pre-stack time migration algorithm and inverses the three azimuth anisotropy equivalent parameters at the same time, the errors caused by step-by-step parameter estimation are reduced, and the problems of the existing azimuth anisotropy pre-stack migration imaging technology in terms of parameter modeling efficiency and accuracy are effectively solved. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed in the embodiments or the prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can also be obtained by those skilled in the art without any creative effort.

[0040] Figure 1 is a flowchart of the azimuth anisotropy equivalent parameter pre-stack migration imaging method provided by the embodiment of the present application.

[0041] Figure 2 is a specific processing flowchart of the azimuth anisotropy equivalent parameter pre-stack migration imaging method provided by the embodiment of the present application.

[0042] Figure 3 is a schematic diagram of a 420-line minimum offset data profile provided by the embodiment of the present application.

[0043] Figure 4 is a schematic diagram of an isotropic pre-stack time migration velocity model provided by an embodiment of the present application.

[0044] Figure 5 is a schematic diagram of a migration stack profile and a selected time window provided by an embodiment of the present application.

[0045] Figure 6 is a schematic diagram of an azimuth-offset domain imaging gather provided by an embodiment of the present application.

[0046] Figure 7 is a comparison diagram of local offset-azimuth imaging gathers before and after azimuth residual moveout correction obtained by optimization inversion provided by an embodiment of the present application.

[0047] Figure 8 is a schematic diagram of an azimuth anisotropy equivalent parameter model obtained by inversion update provided by an embodiment of the present application.

[0048] Figure 9 is a comparison diagram of target migration imaging gathers provided by an embodiment of the present application.

[0049] Figure 10 is a comparison diagram of target migration stack profiles provided by an embodiment of the present application.

[0050] Figure 11 is a schematic diagram of internal modules of an azimuth anisotropy equivalent parameter pre-stack migration imaging device provided by an embodiment of the present application.

[0051] Figure 12 is a schematic diagram of a terminal provided by an embodiment of the present application. DETAILED DESCRIPTION

[0052] The present application discloses a kind of azimuth anisotropy equivalent parameter pre-stack migration imaging method, device, to make the purpose, technical scheme and effect of the present application more clear, definite, the following referring to drawing and taking example for further detailed description of the present application.It should be understood, the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0053] It is to be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. It is further understood that the terms "comprise" (or comprise), "comprises" (or comprises) and "comprising" (or comprises) when used in this specification, specify the presence of stated features, integers, steps, operations, elements, or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or groups thereof. It is further understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements can be present. In addition, the word "connected" or "coupled" as used herein can include wirelessly connected or wirelessly coupled. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0054] It is to be understood that the terms so used are intended to encompass the general meaning of such terms as well as the specific meaning that can be attributed to such terms based on the present technology unless otherwise defined. It is further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0055] For complex geological structures with anisotropy, the anisotropy of the stratum needs to be considered when performing seismic imaging, mainly including transverse isotropic medium with vertical symmetry axis (VTI) and transverse isotropic medium with horizontal symmetry axis (HTI).

[0056] The prior art mainly uses wide-azimuth seismic data to consider the influence of azimuthal anisotropy based on HTI approximation fitting velocity ellipses. Since velocity analysis and migration imaging need to be performed in different directions, the accuracy and efficiency are usually relatively low. In addition, orthogonal anisotropy can also be used for processing. The existing orthogonal anisotropy technology generally uses a VTI+HTI step-by-step parameter estimation method for parameter modeling, and the step-by-step independent calculation is inevitably prone to neglecting one aspect while focusing on the other, resulting in deficiencies in modeling efficiency and accuracy.

[0057] Therefore, the existing azimuthal anisotropy prestack migration imaging technology has obvious deficiencies in parameter modeling efficiency and accuracy.

[0058] In view of the above defects of the prior art, the application provides a method for azimuth anisotropy equivalent parameter pre-stack migration imaging, which acquires pre-stack seismic data and migration velocity model corresponding to a target work area, generates offset-bazimuth imaging gathers and initial migration stack section according to the pre-stack seismic data and the migration velocity model, inverses three azimuth anisotropy equivalent parameters corresponding to an anisotropic medium with a horizontal symmetry axis according to a pre-constructed target pre-stack time migration algorithm, the offset-bazimuth imaging gathers and the initial migration stack section, determines azimuth anisotropy equivalent parameter models corresponding to the three azimuth anisotropy equivalent parameters, and generates target imaging gathers and target migration stack section according to the azimuth anisotropy equivalent parameter models and the pre-stack seismic data. Since the application is based on the pre-constructed target pre-stack time migration algorithm and inverses the three azimuth anisotropy equivalent parameters at the same time, the error caused by step-by-step parameter estimation is reduced, and the problems of the existing azimuth anisotropy pre-stack migration imaging technology in terms of parameter modeling efficiency and accuracy are effectively solved.

[0059] Exemplary method

[0060] As shown in Figure 1 , the method comprises:

[0061] Step S100, acquiring pre-stack seismic data and migration velocity model corresponding to a target work area, and generating offset-bazimuth imaging gathers and initial migration stack section according to the pre-stack seismic data and the migration velocity model.

[0062] Specifically, the pre-stack seismic data refers to seismic data collected before stacking processing. In this embodiment, pre-processed wide-azimuth pre-stack seismic data and migration velocity model in the time domain of the target work area are acquired, the pre-stack seismic data is subjected to pre-stack time migration by using the migration velocity model in the time domain, and offset-bazimuth imaging gathers and initial migration stack section are generated according to the azimuth and offset. Wherein, the pre-processing of the pre-stack seismic data includes trace sorting, denoising, amplitude compensation, etc.

[0063] As shown in Figure 1 , the method further comprises the following steps:

[0064] Step S200, inversing three azimuth anisotropy equivalent parameters corresponding to an anisotropic medium with a horizontal symmetry axis according to a pre-constructed target pre-stack time migration algorithm, offset-bazimuth imaging gathers and initial migration stack section, and determining azimuth anisotropy equivalent parameter models corresponding to the three azimuth anisotropy equivalent parameters.

[0065] Briefly, in order to be able to obtain three azimuth anisotropy equivalent parameters corresponding to the anisotropic medium with horizontal symmetry axis (HTI) by inversion, the embodiment pre-constructs a new target pre-stack time migration algorithm based on a conventional pre-stack time migration algorithm, and inverses three azimuth anisotropy equivalent parameters according to offset-azimuth angle imaging gathers, initial migration stacking profile and the target pre-stack time migration algorithm, and interpolation and smoothing are performed on the inverted azimuth anisotropy equivalent parameters to determine each azimuth anisotropy equivalent parameter model. The embodiment pre-constructs the target pre-stack time migration algorithm, thereby realizing the inversion of three azimuth anisotropy equivalent parameters corresponding to the anisotropic medium with horizontal symmetry axis at the same time, effectively reducing the error caused by step-by-step estimation of each azimuth anisotropy equivalent parameter, and improving the efficiency and accuracy of parameter modeling of azimuth anisotropy pre-stack migration imaging.

[0066] In an implementation manner, the method for constructing the target pre-stack time migration algorithm comprises:

[0067] constructing a travel time function according to the pre-stack seismic data parameters and the azimuth anisotropy equivalent parameters;

[0068] determining the target pre-stack time migration algorithm according to the travel time function and the pre-stack time migration algorithm.

[0069] Specifically, the embodiment constructs the target pre-stack time migration algorithm based on the Kirchhoff three-dimensional pre-stack time migration algorithm. The Kirchhoff three-dimensional pre-stack time migration imaging gathers can be expressed in the frequency domain as:

[0070]

[0071] wherein (x, y) is the horizontal position of the imaging point, t0 is the two-way time depth, h is the offset distance from the shot point to the receiver, F n (ω) represents the frequency domain data of the nth seismic trace, N is the total number of seismic traces, ω is the angular frequency, j is the imaginary unit, τ s and τ g are the travel times of the imaging point to the shot point and the receiver, respectively. Under the assumption of isotropic horizontal layered medium, the travel time is in hyperbolic form, and the calculation function of the travel time is:

[0072]

[0073] wherein h r represents the horizontal distance of the imaging point to the shot point or the receiver, V rms represents the root mean square velocity of the imaging point position.

[0074] The embodiment accumulates the migration imaging result to the corresponding azimuth and offset group in the migration imaging process by Kirchhoff pre-stack time migration algorithm, so as to generate offset-azimuth imaging gathers, which can be expressed as I(x, y, t0, h, a).

[0075] In order to consider the influence of azimuth anisotropy, it is necessary to introduce the azimuth-dependent travel time in the migration process. Under the assumption of HTI anisotropy, the travel time function can be constructed according to the pre-stack seismic data parameters and azimuth anisotropy equivalent parameters, wherein the pre-stack seismic data parameters correspond to the pre-stack seismic data, and the pre-stack seismic data parameters include shotpoint azimuth, two-way time depth, horizontal distance from imaging point to shotpoint or geophone, etc.

[0076] The travel time function can be approximately expressed as:

[0077]

[0078] Wherein, h r is the horizontal distance from the imaging point to the shotpoint or the geophone, a is the shotpoint azimuth, t0 is the two-way time depth, W avg , W cos , W sin are the azimuth anisotropy equivalent parameters respectively.

[0079] In one implementation, the three azimuth anisotropy equivalent parameters corresponding to the anisotropic medium with horizontal symmetry axis are inversed from the pre-constructed target pre-stack time migration algorithm, the offset-azimuth imaging gathers and the initial migration stack profile, including:

[0080] A plurality of initial time windows and local offset-azimuth imaging gathers corresponding to each initial time window are determined according to the offset-azimuth imaging gathers and the initial migration stack profile.

[0081] Each of the azimuth anisotropy equivalent parameters is inversed according to each of the initial time windows, each of the local offset-azimuth imaging gathers and the target pre-stack time migration algorithm.

[0082] Specifically, determining a plurality of initial time windows and local offset-distance-azimuth angle imaging gathers corresponding to each initial time window according to the offset-distance-azimuth angle imaging gathers and the initial migration profile includes: selecting a plurality of initial time windows according to local positions of reflection events on the initial migration profile at certain horizontal position (CDP) intervals; and extracting local offset-distance-azimuth angle imaging gathers corresponding to each initial time window on the offset-distance-azimuth angle imaging gathers according to each time window. Since the pre-constructed target pre-stack time migration algorithm considers three azimuthal anisotropy equivalent parameters corresponding to the anisotropic medium with a horizontal symmetry axis, the embodiment simultaneously inverts each azimuthal anisotropy equivalent parameter based on the target pre-stack time migration algorithm according to each local offset-distance-azimuth angle imaging gather and each initial time window.

[0083] The embodiment selects a certain time window according to the migration profile. For the azimuth-angle-offset imaging gather corresponding to each time window, the azimuth residual moveout is mainly determined by three azimuthal anisotropy equivalent parameters. Correct parameters can correct the "snail" moveout shown by the azimuth-angle-offset imaging gather and stretch the azimuth-angle-offset imaging gather.

[0084] In an implementation manner, the inverting each azimuthal anisotropy equivalent parameter according to each initial time window, each local offset-distance-azimuth angle imaging gather and the target pre-stack time migration algorithm includes:

[0085] constructing a target optimization function based on the target pre-stack time migration algorithm;

[0086] inverting each azimuthal anisotropy equivalent parameter according to each initial time window, each local offset-distance-azimuth angle imaging gather and the target optimization function.

[0087] Specifically, the embodiment determines the offset-distance-azimuth angle imaging gather based on the target pre-stack time migration algorithm, determines each local offset-distance-azimuth angle imaging gather based on the imaging gather, performs cross-correlation calculation on each local offset-distance-azimuth angle imaging gather based on the cross-correlation time shift stacking function, performs weighting through a weighting function to obtain a target optimization function. The embodiment obtains the optimal azimuthal anisotropy equivalent parameter of each time window through the fast simulated annealing algorithm based on the target optimization function and each initial time window and each local offset-distance-azimuth angle imaging gather.

[0088] In an implementation manner, the target optimization function includes:

[0089]

[0090] wherein J represents a target optimization function, ||·|| represents a norm, w(Δt) represents a cross-correlation time-shifted stacking function, T(Δt) represents a weighting function, Δt represents a time sampling rate, W avg , W cos , W sin respectively represent the azimuth anisotropy equivalent parameters;

[0091] For the local offset-azimuth imaging gathers extracted by the time window, the corresponding time difference can be obtained by the cross-correlation calculation of adjacent traces in the gather, and the cross-correlation time-shifted stacking function can be obtained by stacking the time difference along the time direction, which can be represented as:

[0092]

[0093] wherein i is a trace index number, C[.] is a cross-correlation calculation, I is a local offset-azimuth imaging gather calculated based on the target pre-stack time migration algorithm, h represents the offset distance from a shot point to a receiver, a is a shot-receiver azimuth angle, and t1 is a time window center time.

[0094] The embodiment can accurately consider the medium azimuth anisotropy effect by constructing the cross-correlation target optimization function, and independently determine the azimuth anisotropy equivalent parameters. Different from the existing azimuth residual time difference picking and fitting anisotropy parameter estimation method, the multi-parameter global optimization method based on the azimuth anisotropy equivalent parameters of the embodiment reduces the non-uniqueness of parameter estimation, can adapt to lower signal-to-noise ratio data, and has higher inversion accuracy.

[0095] As shown in Figure 1 , the method further comprises the following steps:

[0096] Step S300, generating target imaging gathers and target migration stacking sections according to each azimuth anisotropy equivalent parameter model and the pre-stack seismic data.

[0097] Specifically, the target imaging gathers and the target migration stacking sections can be obtained by using the target pre-stack time migration algorithm according to the azimuth anisotropy equivalent parameter model and the pre-stack seismic data. Compared with the existing split-azimuth migration technology, the embodiment can efficiently process large-scale 3D wide-azimuth seismic data, and the target imaging gathers and the target migration stacking sections obtained have higher accuracy and efficiency.

[0098] As shown in Figure 2 , the specific implementation is as follows:

[0099] (1) Based on the wide-azimuth 3D seismic data collected on land. The data has been preprocessed and velocity analyzed using the conventional seismic data processing flow, and the isotropic time-domain migration velocity model is obtained. Taking imaging line 420 as an example, the CDP range is from 70 to 1200, with a total of 1131 CDPs, and the CDP interval is 10 meters; the minimum offset distance of the data is 50 meters, the maximum offset distance is 4450 meters, the offset distance interval is 100 meters, the data length is 6 seconds, and the sampling rate is 2 milliseconds. The minimum offset distance profile corresponding to the imaging line 420 is shown in Figure 3 , and the isotropic time-domain migration velocity model is shown in Figure 4 . Using the obtained isotropic time-domain migration velocity model, isotropic prestack time migration is performed to generate the azimuth-offset imaging gathers and the corresponding migration stacking sections, with the azimuth from 0° to 360°, the interval of 30°, a total of 13 groups; the offset from 50 meters to 4450 meters, the interval of 400 meters, a total of 12 groups; Figure 5 is the migration stacking section of line 420, Figure 6 is the obtained offset-azimuth imaging gather at the CDP 500 position.

[0100] (2) According to the obtained migration imaging stacking section, 82 time windows with relatively clear phase axes are selected, with a time direction size of 200 milliseconds, and the distribution is shown by the black line segment in Figure 5 .

[0101] (3) Based on the selected time windows and the local offset-azimuth imaging gathers corresponding to the time windows, based on the constructed target prestack time migration algorithm and the target optimization function, the azimuth anisotropy equivalent parameter fast simulated annealing optimization inversion is performed on each time window in turn, Figure 7 shows a comparison of the local azimuth residual moveout correction gather at a window (CDP 500, 1.96 seconds), Figure 7 , in which (a) is the input gather, Figure 7 , in which (b) is the corrected gather, and it can be seen that the reflection phase axis of the imaging gather in the offset group shown by the box is flattened, indicating that the azimuth anisotropy equivalent parameter model obtained by inversion is relatively accurate.

[0102] (4) By performing inversion on all selected windows, the azimuth anisotropy equivalent parameters of each local imaging point position are obtained, and by interpolating and smoothing them, the inverted azimuth anisotropy equivalent parameter model is obtained, Figure 8 is the three azimuth anisotropy equivalent parameter models established, Figure 8 , in which (a) is W avg , Figure 8 , in which (b) is W cos , Figure 8 , in which (c) is W sin .

[0103] (5) Azimuth anisotropy pre-stack time migration based on the azimuth anisotropy equivalent parameter model. In this embodiment, the imaging gathers at CDP 600 are extracted for comparison, Figure 9 Fig. 6(a) is the isotropic migration imaging gather, Figure 9 Fig. 6(b) is the target imaging gather in this embodiment. By comparison, it can be found that the event in this embodiment is finer and straighter, which also indicates that the azimuth anisotropy equivalent parameter model in this embodiment can be obtained to correct the azimuth residual moveout. The stacked migration profiles of the isotropic pre-stack time migration in the prior art are further compared. Figure 10 Fig. 7(a) is the isotropic migration stacked profile of the target area in the prior art, Figure 10 Fig. 7(b) is the target migration stacked profile obtained by using this embodiment. By comparison, it can be seen that the event in the imaging profile of this embodiment is clearer, and the imaging of faults and small-scale structures is obviously improved. By processing all target imaging lines according to the above process, the azimuth anisotropy pre-stack time migration imaging result of the whole imaging area of the working area can be obtained.

[0104] Based on the above embodiments, the application further provides an azimuth anisotropy equivalent parameter pre-stack migration imaging device, as shown in Fig. 8, which comprises: Figure 11 as shown in Fig. 8, the device comprises:

[0105] An initial imaging module 01 is configured to acquire pre-stack seismic data and a migration velocity model corresponding to a target working area, generate a migration distance-azimuth angle imaging gather and an initial migration stacked profile according to the pre-stack seismic data and the migration velocity model.

[0106] A parameter inversion module 02 is configured to invert three azimuth anisotropy equivalent parameters corresponding to an anisotropic medium with a horizontal symmetry axis according to a pre-constructed target pre-stack time migration algorithm, the migration distance-azimuth angle imaging gather and the initial migration stacked profile, and determine an azimuth anisotropy equivalent parameter model corresponding to each of the azimuth anisotropy equivalent parameters.

[0107] A target imaging module 03 is configured to generate a target imaging gather and a target migration stacked profile according to each of the azimuth anisotropy equivalent parameter models and the pre-stack seismic data.

[0108] Based on the above embodiments, the application further provides a terminal, and the principle block diagram thereof can be as shown in Fig. 9. Figure 12The terminal includes a processor, a memory, a network interface, and a display screen connected through a system bus. The processor of the terminal is configured to provide computing and control capabilities. The memory of the terminal includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for running the operating system and the computer program in the non-volatile storage medium. The network interface of the terminal is configured to communicate with external terminals through a network connection. The computer program is executed by the processor to implement the azimuth anisotropy equivalent parameter prestack migration imaging method. The display screen of the terminal can be a liquid crystal display screen or an electronic ink display screen.

[0109] Those skilled in the art can understand that Figure 12 The principle block diagram shown in the figure is only a block diagram of part of the structure related to the scheme of the present application, and does not constitute a limitation on the terminal to which the scheme of the present application is applied. The specific terminal can include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0110] In an implementation manner, the memory of the terminal stores more than one program, and is configured to execute the more than one program by more than one processor, which includes instructions for performing the azimuth anisotropy equivalent parameter prestack migration imaging method.

[0111] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be completed by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer readable storage medium. When the computer program is executed, it can include the processes of the above-mentioned embodiments. Any reference to memory, storage, database or other medium used in the embodiments of the present application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration but not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronization link (Synchronization link) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0112] In summary, the application discloses a method and device for azimuth anisotropy equivalent parameter prestack migration imaging, which obtains prestack seismic data and migration velocity model corresponding to a target work area, generates offset-azimuth imaging gathers and initial migration stack section according to the prestack seismic data and the migration velocity model, inverts three azimuth anisotropy equivalent parameters corresponding to an anisotropic medium with a horizontal symmetry axis according to a pre-constructed target prestack time migration algorithm, the offset-azimuth imaging gathers and the initial migration stack section, determines an azimuth anisotropy equivalent parameter model corresponding to the azimuth anisotropy equivalent parameters, and generates target imaging gathers and target migration stack section according to the azimuth anisotropy equivalent parameter models and the prestack seismic data. Since the application is based on the pre-constructed target prestack time migration algorithm and simultaneously inverts the three azimuth anisotropy equivalent parameters, errors caused by step-by-step parameter estimation are reduced, and the problems of the existing azimuth anisotropy prestack migration imaging technology in terms of parameter modeling efficiency and accuracy are effectively solved.

[0113] It should be understood that the application is not limited to the above examples, and can be improved or changed according to the above description for those skilled in the art, and all these improvements and changes shall belong to the protection scope of the appended claims of the application.

Claims

1. An azimuthally anisotropic equivalent parameter prestack migration imaging method, characterized in that, The method comprises: acquiring prestack seismic data and migration velocity model corresponding to a target work area, generating offset-azimuth imaging gathers and initial migration stack section according to the prestack seismic data and the migration velocity model; inverting three azimuthal anisotropy equivalent parameters corresponding to anisotropic medium with horizontal symmetry axis according to pre-constructed target prestack time migration algorithm, the offset-azimuth imaging gathers and the initial migration stack section, determining azimuthal anisotropy equivalent parameter model corresponding to each of the azimuthal anisotropy equivalent parameters; generating target imaging gathers and target migration stack section according to each of the azimuthal anisotropy equivalent parameter model and the prestack seismic data; the construction method of the target prestack time migration algorithm, comprising: constructing travel time function according to prestack seismic data parameters and each of the azimuthal anisotropy equivalent parameters; determining target prestack time migration algorithm according to the travel time function and prestack time migration algorithm; the travel time function comprises: where h r is the horizontal distance from the imaging point to the shot or receiver point, a is the azimuth of the shot-receiver point, t0is the two-way time depth, W avg , W cos , and W sin are the azimuth anisotropy equivalent parameters, respectively.

2. The azimuthally anisotropic equivalent-parameters prestack migration imaging method of claim 1, wherein, the inversion of three azimuthal anisotropy equivalent parameters corresponding to anisotropic medium with horizontal symmetry axis according to pre-constructed target prestack time migration algorithm, the offset-azimuth imaging gathers and the initial migration stack section comprises: determining a plurality of initial time windows and local offset-azimuth imaging gathers corresponding to each of the initial time windows according to the offset-azimuth imaging gathers and the initial migration stack section; inverting each of the azimuthal anisotropy equivalent parameters according to each of the initial time windows, each of the local offset-azimuth imaging gathers and the target prestack time migration algorithm.

3. The azimuthally anisotropic equivalent-parameters prestack migration imaging method of claim 2, wherein, the determination of a plurality of initial time windows and local offset-azimuth imaging gathers corresponding to each of the initial time windows according to the offset-azimuth imaging gathers and the initial migration stack section comprises: selecting a plurality of initial time windows of local positions of reflection symmetry axis on the initial migration stack section with horizontal position interval; extracting the local offset-azimuth imaging gathers corresponding to each of the initial time windows on the offset-azimuth imaging gathers according to each of the initial time windows.

4. The azimuthally anisotropic equivalent-parameters prestack migration imaging method of claim 2, wherein, the inversion of each of the azimuthal anisotropy equivalent parameters according to each of the initial time windows, each of the local offset-azimuth imaging gathers and the target prestack time migration algorithm comprises: constructing target optimization function based on the target prestack time migration algorithm; inverting each of the azimuthal anisotropy equivalent parameters according to each of the initial time windows, each of the local offset-azimuth imaging gathers and the target optimization function.

5. The azimuthally anisotropic equivalent-parameters prestack migration imaging method of claim 4, wherein, the target optimization function comprises: where J denotes the objective optimization function, ||•|| denotes a norm, w(Δt) denotes a cross-correlation time-shifted stacking function, T(Δt) denotes a weighting function, Δt denotes a time sampling rate, W avg , W cos , W sin are the azimuthal anisotropy equivalent parameters, respectively. wherein, i is a trace index number, C[.] is cross-correlation calculation, I is local offset-azimuth imaging gather calculated based on the target prestack time migration algorithm, h represents offset distance from shot point to receiver, a is shot-receiver azimuth, t1 is time window center time.

6. An azimuthally anisotropic equivalent parameter prestack migration imaging apparatus, characterized in that, The device comprises: an initial imaging module, configured to acquire prestack seismic data and migration velocity model corresponding to a target work area, generate offset-azimuth imaging gathers and initial migration stack section according to the prestack seismic data and the migration velocity model; The parameter inversion module is configured to determine three azimuth anisotropy equivalent parameters corresponding to an anisotropic medium with a horizontal symmetry axis according to a pre-constructed target pre-stack time migration algorithm, the offset-azimuth imaging gathers and the initial migration stack profile, and determine an azimuth anisotropy equivalent parameter model corresponding to each of the azimuth anisotropy equivalent parameters; The target imaging module is configured to generate target imaging gathers and target migration stack profiles according to each of the azimuth anisotropy equivalent parameter models and the pre-stack seismic data; The construction method of the target pre-stack time migration algorithm comprises: constructing a travel time function according to pre-stack seismic data parameters and each of the azimuth anisotropy equivalent parameters; determining a target pre-stack time migration algorithm according to the travel time function and a pre-stack time migration algorithm; The travel time function comprises: where h r is the horizontal distance from the imaging point to the shot or receiver point, a is the azimuth of the shot-receiver point, t0is the two-way time depth, W avg , W cos , W sin are the azimuth anisotropy equivalent parameters, respectively.

7. A terminal, characterized by comprising: The terminal comprises a memory and one or more processors; the memory stores one or more programs; the programs contain instructions for executing the azimuth anisotropy equivalent parameter pre-stack migration imaging method according to any one of claims 1-5; and the processors are configured to execute the programs.

8. A computer-readable storage medium having a plurality of instructions stored thereon, characterized in that: The instructions are suitable for being loaded and executed by the processors to implement the steps of the azimuth anisotropy equivalent parameter pre-stack migration imaging method according to any one of claims 1-5.

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