A wavefield constraint based least squares reverse time migration method and apparatus

Abstract

The application provides a wave field constraint-based least square reverse time migration method, device, computer readable storage medium and electronic equipment. The method adds a constraint term in a target functional of the least square reverse time migration, realizes wave field constraint through reconstruction of a first-order scattering wave field, suppresses imaging noise and artifacts caused by the Born approximation, and obtains high-resolution and high-quality imaging results. Meanwhile, the method obtains a high-quality velocity disturbance gradient through wave field constraint, thereby accelerating the convergence speed, improving the calculation efficiency, and providing support for practicalization of the least square reverse time migration.

Description

Technical Field

[0001] This invention relates to the field of seismic wave imaging technology, and in particular to a least-squares reverse time migration method, apparatus, computer-readable storage medium, and electronic device based on wavefield constraints. Background Technology

[0002] Data-domain least-squares reverse-time migration (LSTM) achieves a perfect fit between observed and simulated data through an iterative approach, yielding high-resolution and high-amplitude-preserving imaging results. Compared to conventional LSTM, LSTM exhibits no significant low-frequency noise, migration artifacts, or acquisition footprint issues. Conventional LSTM theory is based on the first-order scattering wave assumption under the Born approximation, requiring the subsurface medium to satisfy the assumptions of weak scattering potential and small scatterers. Theoretically, this method can only accurately describe subsurface media that meet these assumptions. However, actual subsurface structures are highly complex and cannot always satisfy the conditions of weak scattering potential and small scatterers. Seismic wave propagation in these complex media is also a nonlinear process, generating various wave fields, including direct waves and rotating waves. These can interfere with the first-order scattering wave required for LSTM, producing artifacts and affecting imaging quality. Summary of the Invention

[0003] To address the aforementioned problems, embodiments of the present invention provide a least-squares reverse time migration method, apparatus, computer-readable storage medium, and electronic device based on wave field constraints.

[0004] In a first aspect, embodiments of the present invention provide a least-squares reverse-time migration method based on wavefield constraints, comprising:

[0005] S100, construct an objective function for least squares reverse time migration based on wave field constraints;

[0006] S200, based on the seismic velocity field and shot record, inverts the scattered waves to obtain the reconstructed scattered wave field;

[0007] S300, Based on the reconstructed scattered wave field, obtain the gradient of the objective function with respect to the seismic velocity perturbation;

[0008] S400, based on the preset step size and the gradient of the seismic velocity perturbation by the objective function, the seismic velocity perturbation is updated, and the corresponding simulated shot record is obtained based on the updated seismic velocity perturbation.

[0009] S500: Determine whether the preset termination condition is met. If the termination condition is not met, return to steps S200 to S400 to perform iterative calculations based on the seismic velocity field and the difference between the simulated shot record and the previous shot record until the preset termination condition is met, and output the offset result.

[0010] According to an embodiment of the present invention, the objective function is an objective functional under the L-2 norm.

[0011] According to an embodiment of the present invention, step S200 includes: inverting the scattered wave based on the seismic velocity field and shot record, and obtaining the background wave field and the reconstructed scattered wave field through finite difference calculation.

[0012] According to an embodiment of the present invention, the aforementioned scattered wave is a first-order scattered wave, and the aforementioned scattered wave field is a first-order scattered wave field.

[0013] According to an embodiment of the present invention, in step S400 above, the step size is calculated and set using the steepest descent method.

[0014] According to an embodiment of the present invention, in step S500 above, the termination condition includes the value of the objective function being less than a preset threshold.

[0015] According to an embodiment of the present invention, in step S500 above, the termination condition includes the number of iterations being less than a preset threshold number.

[0016] Secondly, embodiments of the present invention also provide a least-squares reverse-time migration device based on wavefield constraints, comprising:

[0017] The function building module is used to construct an objective function for least-squares reverse-time migration based on wave field constraints;

[0018] The wavefield reconstruction module is used to invert the scattered waves based on the seismic velocity field and shot records to obtain the reconstructed scattered wavefield.

[0019] The gradient calculation module is used to obtain the gradient of the objective function with respect to the seismic velocity perturbation based on the reconstructed scattered wave field.

[0020] The perturbation update module is used to update the seismic velocity perturbation according to the preset step size and the gradient of the seismic velocity perturbation by the objective function, and obtain the corresponding simulated shot record based on the updated seismic velocity perturbation.

[0021] The output judgment module is used to determine whether the preset termination condition is met. When the termination condition is not met, the wavefield reconstruction module, gradient calculation module and disturbance update module are called again to perform iterative calculation based on the seismic velocity field and the difference between the simulated shot record and the previous shot record until the termination condition is met, and the migration result is output.

[0022] Thirdly, embodiments of the present invention provide a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements a least-squares reverse time migration method based on wave field constraints as described in the first aspect.

[0023] Fourthly, embodiments of the present invention provide an electronic device comprising:

[0024] processor;

[0025] Memory used to store the processor's executable instructions;

[0026] The processor is configured to execute the instructions to implement a wave field-constrained least-squares reverse time migration method as described in the first aspect above.

[0027] Compared with the prior art, the above-mentioned technical solution of the present invention has the following beneficial effects:

[0028] This invention provides a wavefield-constrained least-squares reverse-time migration method. This method adds constraint terms to the target functional of the least-squares reverse-time migration and enhances the constraint on the first-order scattered wave by reconstructing the first-order scattered wavefield. This suppresses noise caused by the Born approximation assumption, resulting in high-resolution and high-quality imaging results. Simultaneously, this method obtains high-quality perturbation gradients through wavefield constraints, thereby accelerating convergence, improving computational efficiency, and enhancing the adaptability of the least-squares reverse-time migration algorithm, thus supporting the practical application of least-squares reverse-time migration. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a flowchart of the steps of the least squares reverse time migration method based on wave field constraints provided in this embodiment of the invention;

[0031] Figure 2 This is a schematic diagram of the scatterer model provided in an embodiment of the present invention;

[0032] Figure 3 This is a schematic diagram of the original gun record provided in an embodiment of the present invention;

[0033] Figure 4 This is a schematic diagram of the LSRTM results after 30 iterations provided in an embodiment of the present invention;

[0034] Figure 5 This is a schematic diagram of the LSRTM results of constraints with 30 iterations provided in an embodiment of the present invention;

[0035] Figure 6 yes Figure 3 A schematic diagram of the magnified local result;

[0036] Figure 7 yes Figure 4 A schematic diagram of the magnified local result;

[0037] Figure 8 This is a schematic diagram of the convergence curve provided in an embodiment of the present invention;

[0038] Figure 9 This is a schematic diagram of the composition of the electronic device provided in an embodiment of the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Example 1

[0041] Since conventional data domain least squares reverse time migration is based on the first-order scattering wave assumption of the Born approximation, this assumption requires the subsurface medium to satisfy the assumptions of weak scattering potential and small scatterers. However, the actual subsurface medium is complex and it is difficult to satisfy this assumption. Therefore, a lot of imaging noise will appear in the final imaging results, affecting the final imaging quality.

[0042] To address the problems of the aforementioned least-squares reverse-time migration in the data domain, this invention proposes a least-squares reverse-time migration method based on wavefield constraints. By reconstructing the wavefield, a more accurate first-order scattered wavefield from the subsurface is obtained. Wavefield constraints are applied to enhance the influence of the first-order scattered wavefield, thereby reducing the impact of the background wavefield and other wavefields on the imaging results. This achieves high-quality and high-amplitude-preserving imaging of subsurface structures, while also accelerating the convergence speed and reducing computational costs, thus contributing to the further practical application of least-squares reverse-time migration.

[0043] This invention proposes a wavefield-constrained least-squares inverse time migration method, which is still based on the least-squares inversion framework. First, a target functional of wavefield-constrained least-squares inverse time migration is reconstructed. Then, the seismic velocity model and shot records are input, and finite-difference calculations are performed to solve for the corresponding background and scattered wavefields. The gradients are calculated according to the corresponding formulas. Next, the step size is determined, and the seismic velocity perturbation is updated. Then, it is determined whether the termination condition is met. If the termination condition is met, the final result is output. If not, iterative calculations are performed until the termination condition is met, ultimately obtaining high-quality and high-amplitude-preserving imaging results. The specific implementation process includes the following steps:

[0044] Construct a new objective functional under the least-squares inverse-time offset L-2 norm:

[0045]

[0046] in, Represents a spatial vector. express The spatial vector of nearby disturbance points, where ω represents frequency. This represents the simulated first-order scattered wave field. d represents the first-order scattered wave field in the observation data. n V represents the higher-order scattered wave field and background wave field in the observation data, V represents the velocity, u0 is the background wave field, G is the Green's function, and λ is the constraint factor.

[0047] (2) Input the velocity model and the difference between the original shot record or the simulated shot record and the original shot record. Perform inversion on the first-order scattered wave to obtain a more accurate first-order scattered wave field. The reconstructed expression is as follows:

[0048]

[0049] The parameters are consistent with those in formula (1);

[0050] (3) After accurately reconstructing the scattered wave field, the gradient of the objective function with respect to the velocity perturbation can be obtained, as shown in the formula:

[0051]

[0052] in, The gradient is represented by , and the other parameters remain consistent with formula (1);

[0053] (4) Using the steepest descent method, calculate the step size, and update the velocity perturbation based on the step size and gradient. The formula is as follows:

[0054]

[0055] Where α is the step size, The gradient obtained in step (3) is r, which represents the velocity perturbation, i represents the i-th iteration, L represents the forward operator, and T represents the transpose of the vector.

[0056] (5) Based on the update result, determine whether the termination condition is met. If the termination condition is met, proceed to step (6). If the termination condition is not met, return to step (2) and iterate to obtain a new update result.

[0057] (6) Output the final little-squared reverse time offset result.

[0058] The present invention will be further explained below using a scattering point model that does not satisfy the Born approximation as an example, in conjunction with the accompanying drawings and specific embodiments.

[0059] (1) Add constraint terms and reconstruct the objective functional of least squares reverse time offset;

[0060] (2) Read the velocity field of the scattering point used for offset (e.g.) Figure 2 (as shown) and original gun records (such as) Figure 3 (as shown);

[0061] (3) Inversion is performed on the first-order scattered wave to obtain a more accurate reconstructed first-order scattered wave field;

[0062] (4) Based on the reconstructed scattered wave field, determine the gradient of the objective function with respect to the seismic velocity perturbation;

[0063] (5) Calculate the step size and update the seismic velocity perturbation based on the step size and the gradient of the objective function.

[0064] (6) Determine whether the termination condition is met:

[0065] If the termination condition is met, proceed to step (7). If the termination condition is not met, return to steps (2) to (5) and perform iterative calculations based on the difference between the simulated shot record and the original shot record until the termination condition is met.

[0066] In this embodiment, during the initial run, since no simulated shot records are generated, calculations are performed based on the original shot records and the velocity model. Subsequent iterative calculations, performed without meeting the termination condition, are based on the difference between the simulated and original shot records and the velocity model. Each iteration yields a new seismic velocity perturbation. Changes in this perturbation lead to changes in the simulated shot records, which in turn cause changes in the difference between the simulated and original shot records. This iteration continues until the termination condition is met. In this embodiment, the termination condition is that the value of the target functional J is less than a preset threshold, such as 0.0001, or that the number of iterations reaches a preset threshold, such as 30.

[0067] (7) Output the final least squares reverse time offset result.

[0068] Figure 4 and Figure 5 The results are respectively the conventional least-squares reverse-time migration results and the constraint-based least-squares reverse-time migration results proposed in this invention. It can be seen that... Figure 5 The imaging effect is better than Figure 3 However, due to display limitations, it was not very obvious; therefore, a partial magnification was performed. Figure 6 and Figure 7 The magnified results clearly show that the method proposed in this invention has a significant improvement in imaging quality. The resolution of the scatterer is high and the low-frequency noise is relatively weak, indicating that the method of this invention can effectively suppress noise and artifacts caused by Born approximation, and obtain high-resolution and high-quality imaging results. Figure 8 The convergence curves of conventional least squares reverse time offset and the constrained least squares reverse time offset of the present invention are shown. It can be seen that the convergence speed of the method of the present invention is significantly faster, and convergence is achieved with fewer iterations, thereby reducing the number of iterations and improving computational efficiency.

[0069] The wave-field-constrained least-squares reverse time migration method described above suppresses imaging noise and artifacts caused by the Born approximation by using wave-field constraints, thereby improving the imaging quality of least-squares reverse time migration. It also accelerates the convergence speed and improves computational efficiency, which in turn helps to promote the practical application of least-squares reverse time migration.

[0070] Example 2

[0071] The following are embodiments of the apparatus of the present invention, which can be used to execute embodiments of the method of the present invention. For details not disclosed in the embodiments of the apparatus of the present invention, please refer to the embodiments of the method of the present invention.

[0072] This embodiment provides a least-squares reverse-time migration device based on wavefield constraints, which includes:

[0073] The function building module is used to construct an objective function for least-squares reverse-time migration based on wave field constraints;

[0074] The wavefield reconstruction module is used to invert the scattered waves based on the seismic velocity field and shot records to obtain the reconstructed scattered wavefield.

[0075] The gradient calculation module is used to obtain the gradient of the objective function with respect to the seismic velocity perturbation based on the reconstructed scattered wave field.

[0076] The perturbation update module is used to update the seismic velocity perturbation according to the preset step size and the gradient of the seismic velocity perturbation by the objective function, and obtain the corresponding simulated shot record based on the updated seismic velocity perturbation.

[0077] The output judgment module is used to determine whether the preset termination condition is met. When the termination condition is not met, the wavefield reconstruction module, gradient calculation module and disturbance update module are called again to perform iterative calculation based on the seismic velocity field and the difference between the simulated shot record and the previous shot record until the termination condition is met, and the migration result is output.

[0078] Example 3

[0079] This embodiment provides a computer-readable medium storing a computer program that, when executed by a processor, implements the steps of a least-squares reverse-time migration method based on wave field constraints as described in the above embodiment.

[0080] It should be noted that all or part of the processes in the methods of the above embodiments of the present invention can be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. Of course, there are other readable storage media, such as quantum memories, graphene memories, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and inventive practice in the jurisdiction. For example, in some jurisdictions, according to legislation and inventive practice, computer-readable media do not include electrical carrier signals and telecommunication signals.

[0081] Example 4

[0082] Figure 5 This is a schematic diagram of the structure of an electronic device according to an embodiment of the present invention. Figure 5 As shown, at the hardware level, this electronic device includes a processor, and optionally also includes an internal bus, a network interface, and memory. The memory may include main memory, such as high-speed random-access memory (RAM), or it may include non-volatile memory, such as at least one disk drive. Of course, this electronic device may also include other hardware required for other business operations.

[0083] The processor, network interface, and memory can be interconnected via an internal bus, which can be an ISA (Industry Standard Architecture) bus, a PCI (Peripheral Component Interconnect) bus, or an EISA (Extended Industry Standard Architecture) bus, etc. This bus can be categorized as an address bus, data bus, control bus, etc. For ease of illustration, only line segments are used in the diagram, but this does not imply that there is only one bus or one type of bus.

[0084] A memory is used to store programs. Specifically, the program may include program code, which includes computer operation instructions. The memory may include main memory and non-volatile memory, and provides instructions and data to the processor. The processor reads the corresponding computer program from the non-volatile memory into main memory and then runs it. The processor executes the program stored in the memory to perform all the steps in the aforementioned least-squares reverse-time migration method based on wave field constraints.

[0085] The communication bus mentioned above can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. This communication bus can be divided into address bus, data bus, control bus, etc. For ease of illustration, only one thick line is used to represent it in the diagram, but this does not mean that there is only one bus or one type of bus. The communication interface is used for communication between the above electronic devices and other devices.

[0086] A bus, including hardware, software, or both, is used to couple the aforementioned components together. For example, a bus may include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), HyperTransport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an Infinite Bandwidth Interconnect, a Low Pin Count (LPC) bus, a memory bus, a Microchannel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local (VLB) bus, or other suitable buses, or combinations of two or more of these. Where appropriate, a bus may include one or more buses. Although specific buses are described and illustrated in embodiments of the invention, the invention contemplates any suitable bus or interconnect.

[0087] The memory may include random access memory (RAM) or non-volatile memory (NVM), such as at least one disk storage device. Optionally, the memory may also be at least one storage device located remotely from the aforementioned processor.

[0088] The memory may include a large-capacity storage device for data or instructions. For example, and not limitingly, the memory may include a hard disk drive (HDD), a floppy disk drive, flash memory, an optical disk drive, a magneto-optical disk drive, magnetic tape, or a Universal Serial Bus (USB) drive, or a combination of two or more of these. Where suitable, the memory may include removable or non-removable (or fixed) media. In a particular embodiment, the memory is a non-volatile solid-state memory. In a particular embodiment, the memory includes a read-only memory (ROM). Where suitable, the ROM may be a mask-programmed ROM, a programmable ROM (PROM), an erasable PROM (EPROM), an electrically erasable PROM (EEPROM), an electrically rewritable ROM (EAROM), or flash memory, or a combination of two or more of these.

[0089] The processors mentioned above can be general-purpose processors, including central processing units (CPUs), network processors (NPs), etc.; they can also be digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0090] It should be noted that those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is used as an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this invention. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0091] The apparatus, device, system, module, or unit described in the above embodiments can be implemented by a computer chip or entity, or by a product with a certain function. A typical implementation device is a computer. Specifically, the computer can be, for example, a personal computer, a laptop computer, an in-vehicle human-machine interaction device, a cellular phone, a camera phone, a smartphone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or any combination of these devices.

[0092] While this invention provides the method operation steps as described in the embodiments or flowcharts, more or fewer operation steps may be included based on conventional or non-inventive means. The order of steps listed in the embodiments is merely one possible execution order among many and does not represent the only execution order. In actual devices or terminal products, the methods shown in the embodiments or drawings can be executed sequentially or in parallel (e.g., in a parallel processor or multi-threaded processing environment, or even a distributed data processing environment).

[0093] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. 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 illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0094] 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.

[0095] 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.

[0096] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0097] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the embodiments of apparatus, electronic devices, and readable storage media are basically similar to the method embodiments, so the descriptions are relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0098] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A least-squares reverse-time migration method based on wavefield constraints, characterized in that, Includes the following steps: S100, construct an objective function for least squares reverse time migration based on wave field constraints; S200, based on the seismic velocity field and shot record, inverts the scattered waves to obtain the reconstructed scattered wave field; S300, Based on the reconstructed scattered wave field, obtain the gradient of the objective function with respect to the seismic velocity perturbation; S400, based on the preset step size and the gradient of the seismic velocity perturbation by the objective function, the seismic velocity perturbation is updated, and the corresponding simulated shot record is obtained based on the updated seismic velocity perturbation. S500, determine whether the preset termination condition is met. If the termination condition is not met, return to steps S200 to S400 to perform iterative calculations based on the seismic velocity field and the difference between the simulated shot record and the previous shot record until the preset termination condition is met, and output the offset result. The objective function is the objective functional under the L-2 norm as shown below: Represents a spatial vector. express Spatial vector of nearby disturbance points, Indicates frequency, This represents the simulated first-order scattered wave field. This represents the first-order scattered wave field in the observation data. This represents the higher-order scattered wavefield and background wavefield in the observed data. Indicates speed, For the background wave field, For Green's function, This is a constraint factor.

2. The least-squares reverse-time migration method based on wavefield constraints as described in claim 1, characterized in that, Step S200 includes: inverting the scattered wave based on the seismic velocity field and shot record, and obtaining the background wave field and the reconstructed scattered wave field through finite difference calculation.

3. The least-squares reverse-time migration method based on wavefield constraints as described in claim 2, characterized in that, The scattered wave is a first-order scattered wave, and the scattered wave field is a first-order scattered wave field.

4. The least-squares reverse-time migration method based on wavefield constraints as described in claim 1, characterized in that, In step S400, the step size is calculated and set using the steepest descent method.

5. The least-squares reverse-time migration method based on wavefield constraints as described in claim 1, characterized in that, In step S500, the termination condition includes the value of the objective function being less than a preset threshold.

6. The least-squares reverse-time migration method based on wavefield constraints as described in claim 1, characterized in that, In step S500, the termination condition includes the number of iterations being less than a preset threshold number.

7. A least-squares reverse-time migration device based on wavefield constraints, characterized in that, include: The function building module is used to construct an objective function for least-squares reverse-time migration based on wave field constraints; The wavefield reconstruction module is used to invert the scattered waves based on the seismic velocity field and shot records to obtain the reconstructed scattered wavefield. The gradient calculation module is used to obtain the gradient of the objective function with respect to the seismic velocity perturbation based on the reconstructed scattered wave field. The perturbation update module is used to update the seismic velocity perturbation according to the preset step size and the gradient of the seismic velocity perturbation by the objective function, and obtain the corresponding simulated shot record based on the updated seismic velocity perturbation. The output judgment module is used to determine whether the preset termination condition is met. When the termination condition is not met, the wave field reconstruction module, gradient calculation module and disturbance update module are called again to perform iterative calculation based on the seismic velocity field and the difference between the simulated shot record and the previous shot record until the termination condition is met, and the migration result is output. The objective function is the objective functional under the L-2 norm as shown below: Represents a spatial vector. express Spatial vector of nearby disturbance points, Indicates frequency, This represents the simulated first-order scattered wave field. This represents the first-order scattered wave field in the observation data. This represents the higher-order scattered wavefield and background wavefield in the observed data. Indicates speed, For the background wave field, For Green's function, This is a constraint factor.

8. A computer-readable storage medium, characterized in that, It stores a computer program that, when executed by a processor, implements a least-squares reverse time migration method based on wave field constraints as described in any one of claims 1 to 6.

9. An electronic device comprising: processor; Memory used to store the processor's executable instructions; The processor is configured to execute the instructions to implement a least-squares reverse time migration method based on wave field constraints as described in any one of claims 1 to 6.

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