A method and system for prestack migration output aperture-migrated gathers
By separating the cross-wave field through Hilbert transforms in the time and space domains, the zero point of the Poynting vector is eliminated, thus solving the inaccuracy and instability problems of the Poynting vector method in generating angular gathers and improving the quality and energy concentration of the gathers.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA NATIONAL OFFSHORE OIL (CHINA) CO LTD
- Filing Date
- 2022-11-02
- Publication Date
- 2026-05-15
AI Technical Summary
The existing Poynting vector method suffers from inaccurate and unstable direction calculations when generating angle gathers, leading to energy leakage of reflected waves and poor gather quality.
The cross wavefield is separated by Hilbert transform in both the time and spatial domains, eliminating the zero point of the Poynting vector. The wavefield is reconstructed using backpropagation and Hilbert transform, the Poynting vector is calculated and the angular divergence is determined, and a high-quality angular divergence gather is generated.
This improves the generation quality of angular gathers, avoids inaccuracies and instabilities in direction calculations, and ensures the concentration and accuracy of gather energy.
Smart Images
Figure CN115542387B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of geophysical exploration technology, and in particular to a method and system for producing angular migration gathers by pre-stack migration. Background Technology
[0002] Pre-stack migration imaging is a crucial technique for probing the Earth's internal structure using observed seismic records, thereby enabling the exploration of resources such as oil and gas. Angle gathers are a key output of pre-stack migration imaging, containing important information such as seismic wave travel time and amplitude. Therefore, angle gathers can be used for a range of important applications, including velocity modeling and pre-stack attribute inversion.
[0003] The Poynting vector method is a fast method for producing angle gathers by pre-stack migration. This method uses a simulated wavefield to calculate the Poynting vector, which represents the propagation direction of the wavefield. Therefore, the angle can be calculated based on the Poynting vector. Then, the imaging values are extracted using cross-correlation imaging conditions, and the extracted imaging values are arranged at the imaging point positions according to the angle, finally producing the angle-migrated gather.
[0004] However, in practical applications, when wavefields intersect during propagation, the direction obtained using the Poynting vector is inaccurate. Furthermore, the calculated Poynting vector direction is unstable at and near the zero point. Therefore, during the generation of angular gathers, due to the inaccuracy and instability of the Poynting vector method, the imaging values extracted from the imaging conditions are often mapped to incorrect angles, leading to problems such as leakage of reflected wave energy and poor gather quality. Summary of the Invention
[0005] To address the aforementioned problems, the present invention aims to provide a method and system for generating angular migration gathers via pre-stack migration, which can solve the problems of inaccuracy and instability in direction calculation faced by generating angular gathers using the Poynting vector method.
[0006] To achieve the above objectives, the present invention adopts the following technical solution: Firstly, a method for generating angular migration gathers through pre-stack migration is provided, comprising:
[0007] Acquire the migration velocity model and seismic data for the target area;
[0008] Based on the migration velocity model of the target region, the source end wavefield and its orthogonal wavefield are simulated, the corresponding boundary values are recorded, and the reconstructed source end wavefield and its orthogonal wavefield are obtained by backpropagation.
[0009] The acquired seismic data is placed at the detector end, and the wavefield at the detector end and its orthogonal wavefield are backpropagated based on the migration velocity model of the target area.
[0010] Upward and downward wave separation is performed on the wave fields and their orthogonal wave fields at the source and detector ends to obtain the upward and downward wave fields at the source and detector ends.
[0011] The Poynting vector of the downflow wavefield is obtained from the downflow wavefield and its orthogonal wavefield at the source end, and the Poynting vector of the upflow wavefield is obtained from the upflow wavefield and its orthogonal wavefield at the detector end, and the sag angle is determined.
[0012] The downflow wave field at the source end and the upflow wave field at the detector end are imaged to obtain the image values, and the angular gather of the target area is extracted based on the obtained angular gather.
[0013] Furthermore, the migration velocity model based on the target region simulates the source end wavefield and its orthogonal wavefield, records the corresponding boundary values, and backpropagates to obtain the reconstructed source end wavefield and its orthogonal wavefield, including:
[0014] A source wavelet is placed at the source end, and the wave field at the source end is simulated based on the migration velocity model of the target area, and the boundary values are recorded.
[0015] Perform a time-domain Hilbert transform on the source wavelet, place the Hilbert-transformed source wavelet at the shot point, simulate the orthogonal wave field of the source end wave field, and record the boundary values.
[0016] The boundary values recorded by backpropagation are used to reconstruct the wavefield at the source end and its orthogonal wavefield.
[0017] Furthermore, the process of placing the acquired seismic data at the detector end and backpropagating the wavefield at the detector end and its orthogonal wavefield based on the migration velocity model of the target area includes:
[0018] The acquired seismic data is placed at the detector end, and the wave field at the detector end is backpropagated based on the migration velocity model of the target area.
[0019] The observation data is subjected to a time-domain Hilbert transform and placed at the detector position to backpropagate the orthogonal wave field of the detector end wave field.
[0020] Furthermore, the descending wave field at the source end is obtained using the following formula:
[0021]
[0022] Where, p d (x,t;x s ) represents the descending wave field at the source end, p h (x,t;x s p(x,t; x) represents the orthogonal wavefield of the descending wavefield at the source end; s () represents the wave field at the earthquake source end; This is an orthogonal wavefield simulating the wavefield at the earthquake source; z represents the depth.
[0023] The upward wave field at the detector end is obtained using the following formula:
[0024]
[0025] Where, q u (x,t;x s () represents the upward wave field at the detector end. For the orthogonal wave field of the traveling wave field at the detector end, q(x,t; x s ) represents the wave field at the detector end; q h (x,t;x s This involves performing a spatial domain Hilbert transform on the orthogonal wave field at the detector end along the z-axis.
[0026] Furthermore, the Poynting vector of the descending wave field at the source end for:
[0027]
[0028] Poynting vector of the traveling wave field at the detector end for:
[0029]
[0030] Furthermore, the subtended angle θ is:
[0031]
[0032] Furthermore, the angular gather I(x; θ) is:
[0033]
[0034] Where δ(θ′-θ) is the image value extracted at the subtended angle θ.
[0035] Secondly, a system for producing angular migration gathers by pre-stack migration is provided, comprising:
[0036] The data acquisition module is used to acquire the migration velocity model and seismic data of the target area;
[0037] The source end wavefield backpropagation module is used to simulate the source end wavefield and its orthogonal wavefield based on the migration velocity model of the target area, record the corresponding boundary values, and obtain the reconstructed source end wavefield and its orthogonal wavefield through backpropagation.
[0038] The detector-end wavefield backpropagation module is used to place the acquired seismic data at the detector end and backpropagate the wavefield at the detector end and its orthogonal wavefield based on the migration velocity model of the target area.
[0039] The uplink and downlink wave separation module is used to separate the wave fields and their orthogonal wave fields at the source end and the detector end, so as to obtain the uplink and downlink wave fields at the source end and the detector end.
[0040] The angle determination module is used to obtain the Poynting vector of the downflow wave field based on the downflow wave field and its orthogonal wave field at the source end, and to obtain the Poynting vector of the upflow wave field based on the upflow wave field and its orthogonal wave field at the detector end, and to determine the angle.
[0041] The angular gather extraction module is used to image the down-going wave field at the source end and the up-going wave field at the detector end, obtain the image values, and extract the angular gather of the target area based on the obtained angular gather.
[0042] Thirdly, a processing apparatus is provided, including computer program instructions, wherein when the computer program instructions are executed by the processing apparatus, they are used to implement the steps corresponding to the above-described method for producing angular offset gathers by pre-stack migration.
[0043] Fourthly, a computer-readable storage medium is provided, wherein computer program instructions are stored on the computer-readable storage medium, wherein the computer program instructions, when executed by a processor, are used to implement the steps corresponding to the above-described method for producing angular offset gathers by pre-stack migration.
[0044] The present invention has the following advantages due to the adoption of the above technical solutions:
[0045] 1. This invention separates the cross wave field by using Hilbert transform in the time and spatial domains, thus avoiding inaccuracies in direction calculation.
[0046] 2. This invention avoids the instability of the Poynting vector method by eliminating the zero point of the Poynting vector during wave field propagation.
[0047] 3. By overcoming the inaccuracy and instability of the Poynting vector, this invention can greatly improve the quality of the generated angle gathers. Attached Figure Description
[0048] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. In the drawings:
[0049] Figure 1 This is a schematic diagram of a method flow provided in an embodiment of the present invention;
[0050] Figure 2This is a schematic diagram of the full wave field and its propagation direction provided in an embodiment of the present invention;
[0051] Figure 3 This is a schematic diagram of the separated upward wave field and its propagation direction provided in an embodiment of the present invention;
[0052] Figure 4 This is a schematic diagram of the propagation direction obtained by the Poynting vector using a conventional method according to an embodiment of the present invention;
[0053] Figure 5 This is a schematic diagram of the propagation direction obtained by the Poynting vector using the method of the present invention, provided in an embodiment of the present invention;
[0054] Figure 6 This is a schematic diagram of pre-stack offset results provided in an embodiment of the present invention;
[0055] Figure 7 This is a schematic diagram of the result of an angular offset gather produced using a conventional method according to an embodiment of the present invention, wherein... Figure 7 (a) is the angled track set located 1.4 km laterally, generated using traditional methods. Figure 7 (b) is the Zhangjiao track set located at a lateral position of 3.2 kilometers, generated using traditional methods. Figure 7 (c) is the Zhangjiao track set located at a lateral position of 4.8 kilometers, generated using traditional methods. Figure 7 (d) is the angled track set located at a lateral position of 6.4 kilometers, generated using the traditional method;
[0056] Figure 8 This is a schematic diagram of the result of the angular offset gather produced by the method of the present invention according to an embodiment of the present invention, wherein, Figure 8 (a) An angle gather located 1.4 km laterally, generated using the method of the present invention. Figure 8 (b) Angle gather located at a lateral position of 3.2 km, generated using the method of the present invention. Figure 8 (c) Angle gather located at a lateral position of 4.8 kilometers, generated using the method of the present invention. Figure 8 (d) is the angled track set located at a lateral position of 6.4 km, generated using the method of the present invention. Detailed Implementation
[0057] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.
[0058] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.
[0059] The method and system for generating angular migration gathers by pre-stack migration provided in this invention separates the cross wavefields through Hilbert transforms in the time and spatial domains, avoiding inaccuracies in direction calculation; it avoids the instability of the Poynting vector method by eliminating the zero points of the Poynting vector during wavefield propagation; and by overcoming the inaccuracy and instability of the Poynting vector, it can greatly improve the quality of the generated angular gathers.
[0060] Example 1
[0061] like Figure 1 As shown, this embodiment provides a method for generating angular migration gathers through pre-stack migration, including the following steps:
[0062] 1) Obtain the migration velocity model and seismic data of the target area.
[0063] 2) Based on the migration velocity model v of the target region, simulate the source end wavefield and its orthogonal wavefield, record the corresponding boundary values, and obtain the reconstructed source end wavefield and its orthogonal wavefield through backpropagation based on the recorded boundary values, specifically:
[0064] 2.1) At the epicenter x s Place the seismic source wavelet f(t; x) at the location s Based on the migration velocity model v of the target region, the wave field p(x,t; x) at the source end is simulated. s ), and record the boundary values.
[0065] Specifically, the equation used in this step to simulate the wavefield at the source end is the second-order equation for constant-density acoustic waves:
[0066]
[0067] Where v is the offset velocity; t is time; x is the spatial coordinate; x s The location of the firing point; x bThese are the boundary points of the offset velocity model; This indicates the recording of the source wave field p(x,t; x) s At boundary point x b The value at p(x) b ,t;x s ) represents the boundary value of the recorded source end wavefield.
[0068] 2.2) For the source wavelet f(t; x) s Perform a time-domain Hilbert transform and at the shot point position x s The source wavelet after Hilbert transformation is placed at point p to simulate the orthogonal wavefield p at the source end. h (x,t;x s ), and record the boundary values.
[0069] Specifically, the equations used in this step to simulate the orthogonal wavefield at the source end are:
[0070]
[0071] Where * represents the convolution symbol; p is the time-domain Hilbert transform of the source wavelet; h (x,t;x s () represents the orthogonal wavefield of the simulated source wavefield; p represents the orthogonal wave field that records the source wave field. h (x,t;x s At boundary point x b The value at p; h (x b ,t;x s ) represents the boundary value of the orthogonal wavefield of the recorded source end wavefield.
[0072] 2.3) Reconstruct the wavefield and its orthogonal wavefield at the source end by backpropagating the boundary values recorded in steps 2.1) and 2.2).
[0073] Specifically, the equations used in this step to reverse reconstruct the source end wavefield and its orthogonal wavefield are as follows:
[0074]
[0075] 3) Place the acquired seismic data at the detector end, and backpropagate the wavefield at the detector end and its orthogonal wavefield based on the migration velocity model v of the target area, specifically:
[0076] 3.1) At the detector end x r Place the acquired seismic data d(x) r ,t;x sBased on the offset velocity model v of the target region, the wave field q(x,t; x) at the backpropagation detector end. s ).
[0077] 3.2) For seismic data d(x) r ,t;x s Perform a time-domain Hilbert transform and place it at detector position x. r The orthogonal wave field q at the back-propagating detector end h (x r ,t;x s ).
[0078] Specifically, the seismic data at the detector end is backpropagated using the following equation (4):
[0079]
[0080] Where, x r The position of the detector; For earthquake data d(x) r ,t;x s The time-domain Hilbert transform.
[0081] 4) Perform up and down wave separation on the wave fields and their orthogonal wave fields at the source and detector ends to obtain the up and down wave fields at the source and detector ends.
[0082] Specifically, this embodiment only utilizes the downflow wave field at the source end and the upflow wave field at the detector end.
[0083] Specifically, the descending wave field at the source end can be obtained using the following formula (5):
[0084]
[0085] Where z represents depth; This indicates that the wave field at the source end is subjected to a spatial domain Hilbert transform along the z-axis; This represents a spatial domain Hilbert transform of the orthogonal wavefield at the source end along the z-axis; p d (x,t;x s () represents the descending wave field at the source end; It is an orthogonal wave field of the descending wave field at the source end.
[0086] Specifically, the ascending wave field at the detector end can be obtained using the following formula (6):
[0087]
[0088] in, This indicates that the wave field at the detector end is subjected to a spatial domain Hilbert transform along the z-axis; This represents a spatial domain Hilbert transform of the orthogonal wavefield at the detector end along the z-axis; q u (x,t;x s () represents the upward wave field at the detector end; It is the orthogonal wave field of the downlink wave field at the detector end.
[0089] 5) Obtain the Poynting vector of the downflow wavefield from the source end and its orthogonal wavefields, and obtain the Poynting vector of the upflow wavefield from the detector end and its orthogonal wavefields, and determine the subtraction angle, specifically:
[0090] 5.1) Based on the descending wavefield and its orthogonal wavefield at the source end, the Poynting vector of the descending wavefield at the source end is obtained. for:
[0091]
[0092] 5.2) Based on the up-traveling wave field and its orthogonal wave field at the detector end, obtain the Poynting vector of the up-traveling wave field at the detector end. for:
[0093]
[0094] 5.3) Determine the slant angle based on the Poynting vector obtained in steps 5.1) and 5.2).
[0095] Specifically, the angle can be determined using the following formula (9):
[0096]
[0097] Where θ is the subtended angle, arccos is the inverse cosine function, and ||·|| represents the magnitude of the vector.
[0098] 6) Based on the cross-correlation imaging conditions, the down-going wave field at the source end and the up-going wave field at the detector end are imaged to obtain the imaging values.
[0099] Specifically, the following formula (i.e., the cross-correlation imaging condition) can be used to image the downflow wave field at the source end and the upflow wave field at the detector end, and extract the imaging value at time t:
[0100] p d (x,t;x s )q u (x,t;x s (10)
[0101] 7) Based on the obtained subtraction angle and imaging value, extract the subtraction angle gather of the target area.
[0102] Specifically, the following formula (10) can be used to extract the angular gather I(x; θ) of the target region:
[0103]
[0104] Where δ(θ′-θ) is the image value extracted at the subtended angle θ.
[0105] The method for generating angular migration gathers using pre-stack migration of this invention can solve the problems of inaccuracy and instability in direction calculation encountered when using the Poynting vector method to obtain angular gathers. For example... Figure 2 As shown, this is the backpropagation wave field recorded during acquisition. It can be seen that in Figure 2 The position of the lower left wavefield intersection, according to the direction obtained from the Poynting vector, often leans towards the stronger in-phase axis rather than a single in-phase axis. For example... Figure 3 As shown, this is the downlink component of the backpropagating wave field separated using the Hilbert transform. It can be seen that... Figure 3 In the diagram, the cross-wavefield is separated; the green arrow is calculated from the Poynting vector of the descending wavefield, pointing perpendicular to the local wavefront. For Figure 2 and Figure 3 It can be observed that the accuracy of direction calculation has been improved.
[0106] like Figure 4 As shown, the propagation direction is calculated using the Poynting vector using traditional methods, and it can be seen that its direction is not stable. Figure 5 As shown, the propagation direction calculated using the Poynting vector obtained by the method of this invention is shown, and it can be seen that its pointing consistency is better.
[0107] like Figure 6 As shown, this is the imaging result of the pre-stack offset output, as follows: Figure 7 As shown, this is a gather extracted using traditional methods. It can be observed that energy leakage occurs in the reflected wave, severely affecting the output quality of the gather. For example... Figure 8 As shown, the angular gather output by the method of the present invention is a more concentrated energy and a better quality gather.
[0108] Example 2
[0109] This embodiment provides a system for generating angular offset gathers through pre-stack migration, including:
[0110] The data acquisition module is used to acquire the migration velocity model and seismic data of the target area.
[0111] The source end wavefield backpropagation module is used to simulate the source end wavefield and its orthogonal wavefield based on the migration velocity model of the target region, record the corresponding boundary values, and obtain the reconstructed source end wavefield and its orthogonal wavefield through backpropagation.
[0112] The detector-end wavefield backpropagation module is used to place the acquired seismic data at the detector end and backpropagate the wavefield at the detector end and its orthogonal wavefield based on the migration velocity model of the target area.
[0113] The uplink and downlink wave separation module is used to separate the wave fields and their orthogonal wave fields at the source and detector ends to obtain the uplink and downlink wave fields at the source and detector ends.
[0114] The angle determination module is used to obtain the Poynting vector of the downflow wave field based on the downflow wave field and its orthogonal wave field at the source end, and to obtain the Poynting vector of the upflow wave field based on the upflow wave field and its orthogonal wave field at the detector end, and to determine the angle.
[0115] The angular gather extraction module is used to image the down-going wave field at the source end and the up-going wave field at the detector end, obtain the image values, and extract the angular gather of the target area based on the obtained angular gather.
[0116] The system provided in this embodiment is used to execute the above-described method embodiments. For specific processes and details, please refer to the above embodiments, which will not be repeated here.
[0117] Example 3
[0118] This embodiment provides a processing device corresponding to the method for generating angular offset gathers by pre-stack migration provided in Embodiment 1. The processing device can be applied to client processing devices, such as mobile phones, laptops, tablets, desktop computers, etc., to execute the method for generating angular offset gathers by pre-stack migration in Embodiment 1.
[0119] The processing device includes a processor, a memory, a communication interface, and a bus. The processor, memory, and communication interface are connected via the bus to enable communication between them. The memory stores a computer program that can run on the processing device. When the processing device runs the computer program, it executes the method for producing angular migration gathers by pre-stack migration provided in Embodiment 1.
[0120] In some implementations, the memory may be high-speed random access memory (RAM), and may also include non-volatile memory, such as at least one disk storage device.
[0121] In other implementations, the processor can be any type of general-purpose processor, such as a central processing unit (CPU) or a digital signal processor (DSP), and there is no limitation here.
[0122] Furthermore, the logical instructions in the aforementioned memory can be implemented as software functional units and sold or used as independent products, and can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.
[0123] Those skilled in the art will understand that the structure of the above-described computing device is only a partial structure related to the solution of this application and does not constitute a limitation on the computing device to which the solution of this application is applied. A specific computing device may include more or fewer components, or combine certain components, or have different component arrangements.
[0124] Example 4
[0125] This embodiment provides a computer program product corresponding to the method for producing angular offset gathers by pre-stack migration provided in Embodiment 1. The computer program product may include a computer-readable storage medium on which computer-readable program instructions for executing the method for producing angular offset gathers by pre-stack migration as described in Embodiment 1 are loaded.
[0126] A computer-readable storage medium can be a tangible device that holds and stores instructions for use by an instruction execution device. A computer-readable storage medium can be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any combination thereof.
[0127] The computer-readable storage medium provided in the above embodiments has a similar implementation principle and technical effect to the above method embodiments, and will not be described again here.
[0128] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.
[0129] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.
[0130] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.
[0131] The above embodiments are only used to illustrate the present invention. The structure, connection method and manufacturing process of each component can be varied. All equivalent transformations and improvements made on the basis of the technical solution of the present invention should not be excluded from the protection scope of the present invention.
Claims
1. A method for generating angular offset gathers via pre-stack migration, characterized in that, include: Acquire the migration velocity model and seismic data for the target area; Based on the migration velocity model of the target region, the source end wavefield and its orthogonal wavefield are simulated, the corresponding boundary values are recorded, and the reconstructed source end wavefield and its orthogonal wavefield are obtained by backpropagation. The acquired seismic data is placed at the detector end, and the wavefield at the detector end and its orthogonal wavefield are backpropagated based on the migration velocity model of the target area. Upward and downward wave separation is performed on the wave fields and their orthogonal wave fields at the source and detector ends to obtain the upward and downward wave fields at the source and detector ends. The Poynting vector of the downflow wavefield is obtained from the downflow wavefield and its orthogonal wavefield at the source end, and the Poynting vector of the upflow wavefield is obtained from the upflow wavefield and its orthogonal wavefield at the detector end, and the sag angle is determined. Imaging is performed on the downflow wave field at the source end and the upflow wave field at the detector end to obtain imaging values, and the angular gather of the target area is extracted based on the obtained angular gather. The descending wave field at the source end is obtained using the following formula: in, The downward wave field at the source end, This is an orthogonal wavefield representing the descending wavefield at the earthquake source. Wavefield at the source end; To simulate the orthogonal wavefield at the source end; For depth; The upward wave field at the detector end is obtained using the following formula: in, The up-traveling wave field at the detector end, The orthogonal wave field of the upward wave field at the detector end. For the detector end wave field; To perform a spatial domain Hilbert transform on the orthogonal wave field at the detector end along the z-axis.
2. The method for generating angular offset gathers by pre-stack migration as described in claim 1, characterized in that, The target region-based migration velocity model simulates the source end wavefield and its orthogonal wavefield, records the corresponding boundary values, and backpropagates to obtain the reconstructed source end wavefield and its orthogonal wavefield, including: A source wavelet is placed at the source end, and the wave field at the source end is simulated based on the migration velocity model of the target area, and the boundary values are recorded. Perform a time-domain Hilbert transform on the source wavelet, place the Hilbert-transformed source wavelet at the shot point, simulate the orthogonal wave field of the source end wave field, and record the boundary values. The boundary values recorded by backpropagation are used to reconstruct the wavefield at the source end and its orthogonal wavefield.
3. The method for generating angular offset gathers by pre-stack migration as described in claim 1, characterized in that, The process of placing the acquired seismic data at the detector end and backpropagating the wavefield at the detector end and its orthogonal wavefield based on the migration velocity model of the target area includes: The acquired seismic data is placed at the detector end, and the wave field at the detector end is backpropagated based on the migration velocity model of the target area. The observation data is subjected to a time-domain Hilbert transform and placed at the detector position to backpropagate the orthogonal wave field of the detector end wave field.
4. The method for generating angular offset gathers by pre-stack migration as described in claim 1, characterized in that, The Poynting vector of the descending wave field at the source end for: Poynting vector of the traveling wave field at the detector end for: 。 5. The method for generating angular offset gathers by pre-stack migration as described in claim 4, characterized in that, The angle is: 。 6. The method for generating angular offset gathers by pre-stack migration as described in claim 1, characterized in that, The Zhangjiao Daoji for: in, To extract Zhangjiao The image value at that location.
7. A system for generating angular migration gathers via pre-stack migration, characterized in that, include: The data acquisition module is used to acquire the migration velocity model and seismic data of the target area; The source end wavefield backpropagation module is used to simulate the source end wavefield and its orthogonal wavefield based on the migration velocity model of the target area, record the corresponding boundary values, and obtain the reconstructed source end wavefield and its orthogonal wavefield through backpropagation. The detector-end wavefield backpropagation module is used to place the acquired seismic data at the detector end and backpropagate the wavefield at the detector end and its orthogonal wavefield based on the migration velocity model of the target area. The uplink and downlink wave separation module is used to separate the wave fields and their orthogonal wave fields at the source end and the detector end, so as to obtain the uplink and downlink wave fields at the source end and the detector end. The angle determination module is used to obtain the Poynting vector of the downflow wave field based on the downflow wave field and its orthogonal wave field at the source end, and to obtain the Poynting vector of the upflow wave field based on the upflow wave field and its orthogonal wave field at the detector end, and to determine the angle. The angular gather extraction module is used to image the down-going wave field at the source end and the up-going wave field at the detector end, obtain the image values, and extract the angular gather of the target area based on the obtained angular gather. The descending wave field at the source end is obtained using the following formula: in, The downward wave field at the source end, This is an orthogonal wavefield representing the descending wavefield at the earthquake source. Wavefield at the source end; To simulate the orthogonal wavefield at the source end; For depth; The upward wave field at the detector end is obtained using the following formula: in, The up-traveling wave field at the detector end, The orthogonal wave field of the upward wave field at the detector end. For the detector end wave field; To perform a spatial domain Hilbert transform on the orthogonal wave field at the detector end along the z-axis.
8. A processing apparatus, characterized in that, It includes computer program instructions, wherein when executed by a processing device, the computer program instructions are used to implement the steps corresponding to the method for producing angular offset gathers by pre-stack migration as described in any one of claims 1-6.
9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer program instructions, wherein when executed by a processor, the computer program instructions are used to implement the steps corresponding to the method for producing angular offset gathers by pre-stack migration as described in any one of claims 1-6.