Azimuth anisotropy equivalent parameter prestack migration imaging method and device

Abstract

The invention discloses an azimuth anisotropy equivalent parameter pre-stack migration imaging method and device. The method comprises the following steps: generating an offset-azimuth angle imaging gather and an initial migration stack section according to pre-stack seismic data and a migration velocity model; inverting three azimuth anisotropy equivalent parameters corresponding to the anisotropic medium with the 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 stack section, and respectively determining each azimuth anisotropy equivalent parameter model; and generating a target imaging gather and a target migration stack section according to the anisotropy equivalent parameter model in each orientation and the pre-stack seismic data. The three azimuth anisotropy equivalent parameters are inverted at the same time on the basis of the pre-constructed target pre-stack time migration algorithm, so that errors caused by step-by-step parameter estimation are reduced, and the problem that an existing azimuth anisotropy pre-stack migration imaging technology is insufficient in parameter modeling efficiency and precision is solved.

Description

Technical Field

[0001] The invention relates to the field of seismic exploration, and in particular to an azimuthal anisotropy equivalent parameter prestack migration imaging method and device. Background Art

[0002] For complex geological structures with anisotropy, the anisotropic effects of the strata need to be considered when performing seismic imaging, mainly including transversely isotropic media with a vertical symmetry axis (VTI) and transversely isotropic media with a horizontal symmetry axis (HTI).

[0003] The existing technology mainly uses wide-azimuth seismic data to approximate the velocity ellipse based on HTI to consider the influence of azimuthal anisotropy. Since velocity analysis and migration imaging need to be performed in different azimuths, the accuracy and efficiency are usually relatively low. In addition, orthogonal anisotropy can also be used for processing. The parameter modeling of existing orthogonal anisotropy technology generally adopts the VTI+HTI step-by-step parameter estimation method. It is inevitable that the independent step-by-step method is easy to lose sight of the other, resulting in deficiencies in modeling efficiency and accuracy.

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

[0005] Therefore, the existing technology still needs to be improved and developed. Summary of the invention

[0006] The technical problem to be solved by the present invention is that, in view of the above-mentioned defects of the prior art, a method and device for azimuthal anisotropic equivalent parameter prestack migration imaging is provided, aiming to solve the problem that the existing azimuthal anisotropic prestack migration imaging technology is insufficient in parameter modeling efficiency and accuracy.

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

[0008] In a first aspect, an embodiment of the present invention provides an azimuthal anisotropy equivalent parameter prestack migration imaging method, wherein the method comprises:

[0009] Acquire pre-stack seismic data and a migration velocity model corresponding to the target work area, and generate offset-azimuth imaging gathers and an initial migration stacking section according to the pre-stack seismic data and the migration velocity model;

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

[0011] A target imaging gather and a target offset stacking section are generated according to each of the azimuthal anisotropy equivalent parameter models and the pre-stack seismic data.

[0012] In one implementation method, the method for constructing the target prestack time migration algorithm includes:

[0013] constructing a travel time function according to pre-stack seismic data parameters and each of the azimuthal anisotropy equivalent parameters;

[0014] A target prestack time migration algorithm is determined according to the travel time function and the prestack time migration algorithm.

[0015] In one implementation, the travel time function includes:

[0016]

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

[0018] In an implementation method, the inversion of three azimuthal anisotropy equivalent parameters corresponding to an anisotropic medium having 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 includes:

[0019] Determine 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 offset stacking profile;

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

[0021] In an implementation method, 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 stacking profile comprises:

[0022] Selecting a number of initial time windows of local positions of reflection isotropic axes on the initial migration stacking section at horizontal position intervals;

[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, 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 includes:

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

[0026] The azimuthal anisotropy equivalent parameters are inverted according to the initial time windows, the local offset-azimuth imaging gathers and the target optimization function.

[0027] In one implementation method, the target optimization function includes:

[0028]

[0029] Where J represents the target optimization function, ||·|| represents the norm, w(Δt) represents the cross-correlation time-shift superposition function, T(Δt) represents the weighting function, Δt represents the time sampling rate, and W avg , W cos , W sin are the azimuthal anisotropy equivalent parameters respectively;

[0030]

[0031] Wherein, i is the trace index, C[.] is the cross-correlation calculation, I is the local offset-azimuth imaging gather calculated based on the target prestack time migration algorithm, h is the offset from the shot point to the receiver point, α is the azimuth of the shot-receiver point, and t1 is the center time of the time window.

[0032] In a second aspect, an embodiment of the present invention further provides an azimuthally anisotropic equivalent parameter prestack migration imaging device, wherein the azimuthally anisotropic equivalent parameter prestack migration imaging device comprises:

[0033] An initial imaging module is used to obtain pre-stack seismic data and a migration velocity model corresponding to a target work area, and generate an offset-azimuth imaging gather and an initial migration stack section according to the pre-stack seismic data and the migration velocity model;

[0034] A parameter inversion module is used to invert three azimuthal 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 azimuthal anisotropy equivalent parameter model corresponding to each of the azimuthal anisotropy equivalent parameters;

[0035] The target imaging module is used to generate target imaging gathers and target offset stacking sections according to each of the azimuthal anisotropy equivalent parameter models and the pre-stack seismic data.

[0036] In a third aspect, an embodiment of the present invention further provides a terminal, comprising a memory and one or more processors; the memory stores one or more programs; the programs include instructions for executing any of the azimuthal anisotropy equivalent parameter prestack migration imaging methods described above; and the processor is used to execute the programs.

[0037] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium having a plurality of instructions stored thereon, wherein the instructions are suitable for being loaded and executed by a processor to implement any of the above-mentioned azimuthal anisotropy equivalent parameter prestack migration imaging methods.

[0038] Beneficial effects of the present invention: The embodiment of the present invention obtains pre-stack seismic data corresponding to the target work area, generates offset-azimuth imaging gathers and initial offset stacking sections in the offset-azimuth domain according to the pre-stack seismic data; inverts three azimuthal 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-azimuth imaging gathers and initial offset stacking sections, and determines an azimuthal anisotropy equivalent parameter model corresponding to the azimuthal anisotropy equivalent parameters; generates target imaging gathers and target offset stacking sections according to each azimuthal anisotropy equivalent parameter model and pre-stack seismic data. Since the present invention is based on a pre-constructed target pre-stack time migration algorithm, and simultaneously inverts three azimuthal anisotropy equivalent parameters, the error caused by step-by-step parameter estimation is reduced, and the problem of the existing azimuthal anisotropy pre-stack migration imaging technology being insufficient in parameter modeling efficiency and accuracy is effectively solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 It is a flow chart of the azimuthal anisotropy equivalent parameter prestack migration imaging method provided by an embodiment of the present invention.

[0041] Figure 2 It is a schematic diagram of a specific processing flow of the azimuthal anisotropy equivalent parameter prestack migration imaging method provided by an embodiment of the present invention.

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

[0043] Figure 4 It is a schematic diagram of an isotropic prestack time migration velocity model provided by an embodiment of the present invention.

[0044] Figure 5 It is a schematic diagram of the offset stacking section and the selected time window provided in an embodiment of the present invention.

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

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

[0047] Figure 8 It is a schematic diagram of an azimuthal anisotropy equivalent parameter model obtained by inversion updating provided in an embodiment of the present invention.

[0048] Fig. 9 It is a schematic diagram of comparison of target migration imaging gathers provided by an embodiment of the present invention.

[0049] Fig.10 It is a schematic diagram of target offset superimposed profile comparison provided by an embodiment of the present invention.

[0050] Fig.11 It is a schematic diagram of the internal modules of the azimuthal anisotropy equivalent parameter prestack migration imaging device provided by an embodiment of the present invention.

[0051] Fig.12 It is a principle block diagram of a terminal provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0052] The present invention discloses an azimuthal anisotropic equivalent parameter prestack migration imaging method and device. In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0053] It will be understood by those skilled in the art that, unless expressly stated, the singular forms "one", "said", and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we refer to an element as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be intermediate elements. In addition, the "connection" or "coupling" used herein may include wireless connection or wireless coupling. The term "and / or" used herein includes all or any unit and all combinations of one or more associated listed items.

[0054] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless specifically defined as herein.

[0055] For complex geological structures with anisotropy, the anisotropic effects of the strata need to be considered when performing seismic imaging, mainly including transversely isotropic media with a vertical symmetry axis (VTI) and transversely isotropic media with a horizontal symmetry axis (HTI).

[0056] The existing technology mainly uses wide-azimuth seismic data to approximate the velocity ellipse based on HTI to consider the influence of azimuthal anisotropy. Since velocity analysis and migration imaging need to be performed in different azimuths, the accuracy and efficiency are usually relatively low. In addition, orthogonal anisotropy can also be used for processing. The parameter modeling of existing orthogonal anisotropy technology generally adopts the VTI+HTI step-by-step parameter estimation method. It is inevitable that the independent step-by-step method is easy to lose sight of the other, resulting in deficiencies in modeling efficiency and accuracy.

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

[0058] In view of the above-mentioned defects of the prior art, the present invention provides an azimuthal anisotropy equivalent parameter prestack migration imaging method, the method obtains prestack seismic data and a migration velocity model corresponding to a target work area, generates an offset distance-azimuth imaging gather and an initial migration stacking section according to the prestack seismic data and the migration velocity model; inverts three azimuthal anisotropy equivalent parameters corresponding to an anisotropic medium with a horizontal symmetry axis according to a pre-constructed target prestack time migration algorithm, an offset distance-azimuth imaging gather and an initial migration stacking section, determines an azimuthal anisotropy equivalent parameter model corresponding to the azimuthal anisotropy equivalent parameter; generates a target imaging gather and a target migration stacking section according to each azimuthal anisotropy equivalent parameter model and prestack seismic data. Since the present invention is based on a pre-constructed target prestack time migration algorithm, and simultaneously inverts three azimuthal anisotropy equivalent parameters, the error caused by step-by-step parameter estimation is reduced, and the problem of the existing azimuthal anisotropy prestack migration imaging technology being insufficient in parameter modeling efficiency and accuracy is effectively solved.

[0059] Exemplary Methods

[0060] like Figure 1 As shown, the method includes:

[0061] Step S100: obtaining pre-stack seismic data and a migration velocity model corresponding to a target work area, and generating an offset-azimuth imaging gather and an initial migration stack section according to the pre-stack seismic data and the migration velocity model.

[0062] Specifically, pre-stack seismic data refers to seismic data collected before stacking. This embodiment obtains wide-azimuth pre-stack seismic data and a time-domain migration velocity model after pre-processing in the target work area, performs pre-stack time migration on the pre-stack seismic data using the time-domain migration velocity model, and generates offset-azimuth imaging gathers and initial migration stacking sections by azimuth and offset grouping. Pre-processing of pre-stack seismic data includes gather sorting, denoising, amplitude compensation, etc.

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

[0064] Step S200, determining an azimuthal anisotropy equivalent parameter model corresponding to each of the azimuthal anisotropy equivalent parameters according to the pre-constructed target pre-stack time migration algorithm, the offset-azimuth imaging gathers, and the initial migration stack profile inversion of three azimuthal anisotropy equivalent parameters corresponding to the anisotropic medium with a horizontal symmetry axis.

[0065] In short, in order to be able to invert the three azimuthal anisotropic equivalent parameters corresponding to anisotropic media (HTI) with a horizontal axis of symmetry, this embodiment pre-constructs a new target pre-stack time migration algorithm based on a conventional pre-stack time migration algorithm, and inverts the three azimuthal anisotropic equivalent parameters according to the offset-azimuthal imaging gathers, the initial migration stacked profile, and the target pre-stack time migration algorithm. The azimuthal anisotropic equivalent parameters obtained by the inversion are interpolated and smoothed to determine the models of the azimuthal anisotropic equivalent parameters. This embodiment pre-constructs the target pre-stack time migration algorithm to simultaneously invert the three azimuthal anisotropic equivalent parameters corresponding to anisotropic media with a horizontal axis of symmetry, effectively reducing the error caused by the step-by-step estimation of the azimuthal anisotropic equivalent parameters, and improving the efficiency and accuracy of azimuthal anisotropic pre-stack migration imaging in parameter modeling.

[0066] In one implementation, the method for constructing the target prestack time migration algorithm includes:

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

[0068] A target prestack time migration algorithm is determined according to the travel time function and the prestack time migration algorithm.

[0069] Specifically, this embodiment constructs a target prestack time migration algorithm based on the Kirchhoff 3D prestack time migration algorithm. The Kirchhoff 3D prestack time migration imaging gather can be expressed in the frequency domain as:

[0070]

[0071] Where (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 point, and F n (ω) represents the frequency domain data of the nth seismic channel, N is the total number of seismic channels, ω is the angular frequency, j is the imaginary unit, τ s and τ g are the travel time from the imaging point to the shot point and the receiver point respectively. Under the assumption of isotropic horizontal layered medium, the travel time is in a hyperbolic form, and the calculation function of the travel time is:

[0072]

[0073] Among them, h r Indicates the horizontal distance from the imaging point to the shot point or the receiver point, V rms Represents the root mean square velocity of the imaging point position.

[0074] This embodiment uses the Kirchhoff prestack time migration algorithm to accumulate the migration imaging results to the corresponding azimuth and offset groups during the migration imaging process, thereby generating an offset-azimuth imaging gather, which can be expressed as I(x, y, t0, h, α).

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

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

[0077]

[0078] Among them, h r is the horizontal distance from the imaging point to the shot point or the receiver point, α is the azimuth of the shot-receiver point, t0 is the two-way time depth, W avg , W cos , W sin are the azimuthal anisotropy equivalent parameters respectively.

[0079] In one implementation, the inversion of three azimuthal anisotropy equivalent parameters corresponding to an anisotropic medium having 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 includes:

[0080] Determine 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 offset stacking profile;

[0081] The azimuthal anisotropy equivalent parameters are inverted according to the initial time windows, the local offset-azimuth imaging gathers and the target prestack time migration algorithm.

[0082] Specifically, 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 stacking section includes: selecting a plurality of initial time windows of the local position of the reflection event on the initial migration stacking section at a certain horizontal position (CDP) interval; extracting local offset-azimuth imaging gathers corresponding to each initial time window on the offset-azimuth 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 anisotropic media with a horizontal symmetry axis, this embodiment simultaneously inverts each azimuthal anisotropy equivalent parameter based on the target pre-stack time migration algorithm according to each local offset-azimuth imaging gather and each initial time window obtained.

[0083] This embodiment uses the offset stacking profile to select a certain time window. For the azimuth-offset imaging gather corresponding to each time window, its azimuth residual time difference is mainly determined by three azimuth anisotropy equivalent parameters. Correct parameters can correct the "snail"-like time difference shown by the azimuth-offset imaging gather and square the azimuth-offset imaging gather.

[0084] In one implementation, 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 includes:

[0085] constructing a target optimization function based on the target prestack time migration algorithm;

[0086] The azimuthal anisotropy equivalent parameters are inverted according to the initial time windows, the local offset-azimuth imaging gathers and the target optimization function.

[0087] Specifically, this embodiment determines the offset-azimuth imaging gathers based on the target pre-stack time migration algorithm, and determines each local offset-azimuth imaging gather based on the imaging gathers, and after performing cross-correlation calculation on each local offset-azimuth imaging gather based on the cross-correlation time-shift stacking function, weights them by a weighting function to obtain a target optimization function. This embodiment uses a fast simulated annealing algorithm to perform optimization inversion based on the target optimization function and each initial time window and each local offset-azimuth imaging gather to obtain the optimal azimuth anisotropy equivalent parameter for each time window.

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

[0089]

[0090] Where J represents the target optimization function, ||·|| represents the norm, w(Δt) represents the cross-correlation time-shift superposition function, T(Δt) represents the weighting function, Δt represents the time sampling rate, and W avg , W cos , W sin are the azimuthal anisotropy equivalent parameters respectively;

[0091] For the local offset-azimuth imaging gathers extracted in the time window, the corresponding time difference can be obtained by cross-correlation calculation of adjacent traces in the gather. The cross-correlation time-shift superposition function can be obtained by superimposing the time difference along the time direction, which can be expressed as:

[0092]

[0093] Wherein, i is the trace index, C[.] is the cross-correlation calculation, I is the local offset-azimuth imaging gather calculated based on the target prestack time migration algorithm, h is the offset from the shot point to the receiver point, α is the azimuth of the shot-receiver point, and t1 is the center time of the time window.

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

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

[0096] Step S300: generating target imaging gathers and target migration stacking sections according to the azimuthal anisotropy equivalent parameter models and the pre-stack seismic data.

[0097] Specifically, the target prestack time migration algorithm is used to obtain the target imaging gathers and the target migration stacking profile according to the azimuthal anisotropy equivalent parameter model and prestack seismic data. Compared with the existing azimuth migration technology, this embodiment can efficiently process large-scale three-dimensional wide azimuth seismic data, and the obtained target imaging gathers and target migration stacking profiles have higher accuracy and efficiency.

[0098] like Figure 2 As shown, the specific embodiments are as follows:

[0099] (1) Based on wide-azimuth three-dimensional seismic data collected on land. The data has been preprocessed and velocity analyzed using conventional seismic data processing procedures to obtain an isotropic time-domain migration velocity model. Taking imaging line 420 as an example, the CDP range is from 70 to 1200, with a total of 1131 CDPs and a CDP interval of 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 imaging line 420 is shown in the figure below: Figure 3 As shown in Figure 2, the isotropic time-domain migration velocity model is as follows: Figure 4 The obtained isotropic time-domain migration velocity model is used to perform isotropic prestack time migration, generating azimuth-offset imaging gathers and corresponding migration stacking sections, with azimuths ranging from 0° to 360°, with an interval of 30°, for a total of 13 groups; offsets ranging from 50 meters to 4450 meters, with an interval of 400 meters, for a total of 12 groups; Figure 5 This is the offset stacking section of line 420. Figure 6 is the offset-azimuth imaging gather obtained for the CDP 500 position.

[0100] (2) This embodiment selects 82 time windows with relatively clear events based on the above-obtained migration imaging stacking profiles. The time direction size is 200 milliseconds and the distribution is as follows: Figure 5 Shown as the black line segment.

[0101] (3) Based on the selected time window and the local offset-azimuth imaging gathers corresponding to the time window, and based on the constructed target prestack time migration algorithm and target optimization function, the azimuthal anisotropy equivalent parameter fast simulated annealing optimization inversion is performed on each time window in turn. Figure 7 The comparison of the local azimuth residual moveout correction gathers at a window (CDP500, 1.96 seconds) is shown. Figure 7 (a) is the input gather, Figure 7 (b) is the corrected gather. It can be seen that the reflection events of the imaging gathers in the offset group are flattened as shown in the box, indicating that the azimuthal anisotropy equivalent parameter model obtained by inversion is relatively accurate.

[0102] (4) The azimuthal anisotropy equivalent parameters of each local imaging point are obtained by inverting all selected windows, and the inverted azimuthal anisotropy equivalent parameter model is obtained by interpolating and smoothing them. Figure 8 Three azimuthal anisotropy equivalent parameter models are established. Figure 8 (a) is W avg , Figure 8 (b) is W cos , Figure 8 (c) is W sin .

[0103] (5) Perform azimuthal anisotropy prestack time migration on the azimuthal anisotropy equivalent parameter model. This embodiment extracts the imaging gathers at CDP 600 for comparison. Fig. 9 (a) is the isotropic migration imaging gather. Fig. 9 (b) is the target imaging gather in this embodiment. By comparison, it can be found that the gather event axis in this embodiment is thinner and straighter, which also shows that this embodiment can obtain a more accurate azimuthal anisotropy equivalent parameter model to correct the azimuthal residual time difference. The stacked imaging section of the isotropic prestack time migration in the existing method is further compared. Fig.10 (a) is the isotropic migration imaging section of the target area using the existing method. Fig.10 (b) is the target migration stacked section obtained by this embodiment. By comparison, it can be seen that the imaging section of this embodiment has clearer phase axes, and the imaging of faults and small-scale structures is significantly improved. By processing all target imaging lines according to the above process, the azimuthal anisotropic prestack time migration imaging results of the entire imaging area of ​​the work area can be obtained.

[0104] Based on the above embodiments, the present invention also provides an azimuthally anisotropic equivalent parameter prestack migration imaging device, such as Fig.11 As shown, the device comprises:

[0105] Initial imaging module 01 is used to obtain pre-stack seismic data and migration velocity model corresponding to the target work area, and generate offset-azimuth imaging gathers and initial migration stacking sections according to the pre-stack seismic data and the migration velocity model;

[0106] The parameter inversion module 02 is used to invert three azimuthal anisotropy equivalent parameters corresponding to the anisotropic medium with a horizontal symmetry axis according to the pre-constructed target pre-stack time migration algorithm, the offset-azimuth imaging gathers and the initial migration stack profile, and determine the azimuthal anisotropy equivalent parameter model corresponding to each of the azimuthal anisotropy equivalent parameters;

[0107] The target imaging module 03 is used to generate target imaging gathers and target migration stacking sections according to each of the azimuthal anisotropy equivalent parameter models and the pre-stack seismic data.

[0108] Based on the above embodiment, the present invention further provides a terminal, whose principle block diagram can be shown as follows: Fig.12As shown. The terminal includes a processor, a memory, a network interface, and a display screen connected through a system bus. Among them, the processor of the terminal is used 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 the operation of the operating system and the computer program in the non-volatile storage medium. The network interface of the terminal is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, an azimuthal anisotropy equivalent parameter prestack migration imaging method is implemented. 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 will understand that Fig.12 The principle block diagram shown in the figure is only a block diagram of a partial structure related to the scheme of the present invention, and does not constitute a limitation on the terminal to which the scheme of the present invention is applied. The specific terminal may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0110] In one implementation, the memory of the terminal stores one or more programs, and is configured to be executed by one or more processors. The one or more programs include instructions for performing an azimuthal anisotropy equivalent parameter prestack migration imaging method.

[0111] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing related hardware through a computer program, and 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 embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided by the present invention may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), 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 present invention discloses a method and device for prestack migration imaging of azimuthal anisotropy equivalent parameters. The method obtains prestack seismic data and a migration velocity model corresponding to a target work area, generates an offset-azimuth imaging gather and an initial migration stacking section according to the prestack seismic data and the migration velocity model; inverts three azimuthal anisotropy equivalent parameters corresponding to an anisotropic medium with a horizontal symmetry axis according to a pre-constructed target prestack time migration algorithm, an offset-azimuth imaging gather and an initial migration stacking section, determines an azimuthal anisotropy equivalent parameter model corresponding to the azimuthal anisotropy equivalent parameter; generates a target imaging gather and a target migration stacking section according to each azimuthal anisotropy equivalent parameter model and prestack seismic data. Since the present invention is based on a pre-constructed target prestack time migration algorithm, and simultaneously inverts three azimuthal anisotropy equivalent parameters, the error caused by step-by-step parameter estimation is reduced, and the problem of the existing azimuthal anisotropy prestack migration imaging technology being insufficient in parameter modeling efficiency and accuracy is effectively solved.

[0113] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for azimuthal anisotropy equivalent parameter prestack migration imaging, characterized in that: The method comprises: Acquire pre-stack seismic data and a migration velocity model corresponding to the target work area, and generate offset-azimuth imaging gathers and an initial migration stacking section according to the pre-stack seismic data and the migration velocity model; Determine an azimuthal anisotropy equivalent parameter model corresponding to each of the azimuthal anisotropy equivalent parameters according to the pre-constructed target pre-stack time migration algorithm, the offset-azimuth imaging gathers, and the initial migration stack profile inversion corresponding to three azimuthal anisotropy equivalent parameters of the anisotropic medium with a horizontal symmetry axis; A target imaging gather and a target offset stacking section are generated according to each of the azimuthal anisotropy equivalent parameter models and the pre-stack seismic data.

2. The azimuthal anisotropy equivalent parameter prestack migration imaging method according to claim 1, characterized in that: The method for constructing the target prestack time migration algorithm comprises: constructing a travel time function according to pre-stack seismic data parameters and each of the azimuthal anisotropy equivalent parameters; A target prestack time migration algorithm is determined according to the travel time function and the prestack time migration algorithm.

3. The azimuthal anisotropy equivalent parameter prestack migration imaging method according to claim 2, characterized in that: The travel time function comprises: Among them, h r is the horizontal distance from the imaging point to the shot point or the receiver point, α is the azimuth of the shot-receiver point, t0 is the two-way time depth, W avg , W cos , W sin are the azimuthal anisotropy equivalent parameters respectively.

4. The azimuthal anisotropy equivalent parameter prestack migration imaging method according to claim 1, characterized in that: The three azimuthal anisotropy equivalent parameters corresponding to the anisotropic 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 profile, including: Determine 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 offset stacking profile; The azimuthal anisotropy equivalent parameters are inverted according to the initial time windows, the local offset-azimuth imaging gathers and the target prestack time migration algorithm.

5. The azimuthal anisotropy equivalent parameter prestack migration imaging method according to claim 4, characterized in that: The step of 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 offset stacking profile comprises: Selecting a number of initial time windows of local positions of reflection isotropic axes on the initial migration stacking section at horizontal position intervals; 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.

6. The azimuthal anisotropy equivalent parameter prestack migration imaging method according to claim 4, characterized in that: The 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 comprises: constructing a target optimization function based on the target prestack time migration algorithm; The azimuthal anisotropy equivalent parameters are inverted according to the initial time windows, the local offset-azimuth imaging gathers and the target optimization function.

7. The azimuthal anisotropy equivalent parameter prestack migration imaging method according to claim 6, characterized in that: The target optimization function includes: Where J represents the target optimization function, ||·|| represents the norm, w(Δt) represents the cross-correlation time-shift superposition function, T(Δt) represents the weighting function, Δt represents the time sampling rate, and W avg , W cos , W sin are the azimuthal anisotropy equivalent parameters respectively; Wherein, i is the trace index, C[.] is the cross-correlation calculation, I is the local offset-azimuth imaging gather calculated based on the target prestack time migration algorithm, h is the offset from the shot point to the receiver point, α is the azimuth of the shot-receiver point, and t1 is the center time of the time window.

8. An azimuthal anisotropy equivalent parameter prestack migration imaging device, characterized in that: The device comprises: An initial imaging module is used to obtain pre-stack seismic data and a migration velocity model corresponding to a target work area, and generate an offset-azimuth imaging gather and an initial migration stack section according to the pre-stack seismic data and the migration velocity model; A parameter inversion module is used to invert three azimuthal 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 azimuthal anisotropy equivalent parameter model corresponding to each of the azimuthal anisotropy equivalent parameters; The target imaging module is used to generate target imaging gathers and target offset stacking sections according to each of the azimuthal anisotropy equivalent parameter models and the pre-stack seismic data.

9. A terminal, characterized in that: The terminal includes a memory and one or more processors; the memory stores one or more programs; the programs contain instructions for executing the azimuthal anisotropy equivalent parameter prestack migration imaging method as described in any one of claims 1 to 7; and the processor is used to execute the programs.

10. 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 a processor to implement the steps of the azimuthal anisotropy equivalent parameter prestack migration imaging method described in any one of claims 1 to 7.

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