Method and device for determining reflection coefficient model under undulating surface condition, electronic equipment and storage medium

Abstract

The invention discloses a method and a device for determining a reflection coefficient model under an undulating surface condition, electronic equipment and a storage medium, and the method comprises the steps: carrying out the viscous sound wave Born simulation based on an immersion absorption boundary, determining a reflection wave field under a target undulating surface condition, and recording the reflection wave field to obtain first reflection wave seismic data, the immersion absorption boundary is used for updating a wave field within a preset distance range close to the undulating surface in a sound wave simulation process; based on the first reflected wave seismic data and the second reflected wave seismic data, the gradient of a reflection coefficient model under the target undulating surface condition is determined; and updating the reflection coefficient model under the target undulating surface condition according to the gradient of the reflection coefficient model. According to the scheme, migration imaging can be directly carried out on undulating surface seismic data, seismic wave amplitude attenuation and velocity dispersion caused by absorption attenuation characteristics of underground media can be stably compensated, the calculation efficiency is high, and the implementation process is convenient and fast.

Description

Technical Field

[0001] This invention relates to the field of seismic exploration technology, and in particular to a method, apparatus, electronic device, and storage medium for determining a reflection coefficient model under undulating surface conditions. Background Technology

[0002] Seismic exploration technology plays a crucial role in oil and gas exploration and development. As exploration difficulties increase, unconventional oil and gas reservoirs are gradually becoming the primary targets for exploration and development. In particular, as exploration targets shift towards complex areas such as deep seas and high mountains, oil and gas geophysical research must address more complex geological environments for oil exploration. Against this backdrop, high-precision migration imaging of seismic data under undulating surface conditions is essential, and high-precision migration imaging requires obtaining relatively accurate reflection coefficients under undulating surface conditions. Summary of the Invention

[0003] This invention provides a method, apparatus, electronic device, and storage medium for determining the reflection coefficient model under undulating surface conditions. It can realize direct migration imaging of seismic data on undulating surfaces and can stably compensate for the amplitude attenuation and velocity dispersion of seismic waves caused by the absorption and attenuation characteristics of the underground medium.

[0004] In a first aspect, the present invention provides a method for determining a reflection coefficient model under undulating surface conditions, the method comprising:

[0005] Based on the immersion absorption boundary, viscous acoustic wave Bonn simulation is performed to determine the reflected wave field under the target undulating surface conditions, and the reflected wave field is recorded to obtain the first reflected wave seismic data. The immersion absorption boundary is used to update the wave field within a preset distance range of the adjacent undulating surface during the acoustic wave simulation.

[0006] Based on the first and second reflected wave seismic data, the gradient of the reflection coefficient model under the target undulating surface conditions is determined. The second reflected wave seismic data is the reflected wave seismic data obtained by actual observation under the target undulating surface conditions.

[0007] The reflection coefficient model under the target undulating surface condition is updated based on the gradient of the reflection coefficient model under the target undulating surface condition.

[0008] Secondly, the present invention also provides an apparatus for determining a reflection coefficient model under undulating surface conditions, the apparatus comprising:

[0009] The first reflection wave seismic data determination module is used to determine the reflection wave field under the target undulating surface conditions based on the viscous acoustic wave Bonn simulation based on the immersion absorption boundary, and to record the reflection wave field to obtain the first reflection wave seismic data. The immersion absorption boundary is used to update the wave field within a preset distance range of the adjacent undulating surface during the acoustic simulation process.

[0010] The gradient determination module is used to determine the gradient of the reflection coefficient model under the target undulating surface conditions based on the first reflected wave seismic data and the second reflected wave seismic data, wherein the second reflected wave seismic data is reflected wave seismic data obtained by actual observation under the target undulating surface conditions.

[0011] The reflection coefficient model update module is used to update the reflection coefficient model under the target undulating surface conditions based on the gradient of the reflection coefficient model under the target undulating surface conditions.

[0012] Thirdly, this invention also provides an electronic device, comprising:

[0013] One or more processors;

[0014] Storage device for storing one or more programs.

[0015] When the one or more programs are executed by the one or more processors, the one or more processors implement the method for determining the reflection coefficient model under undulating surface conditions as provided in any embodiment of the present invention.

[0016] Fourthly, this invention also provides a storage medium containing computer-executable instructions, which, when executed by a computer processor, are used to perform a method for determining a reflection coefficient model under undulating surface conditions as provided in any embodiment of this invention.

[0017] The technical solution provided by this invention determines the reflected wavefield under target undulating surface conditions using viscous acoustic wave Born simulation based on an immersion absorbing boundary, and records the reflected wavefield to obtain first reflected wave seismic data. The immersion absorbing boundary is used to update the wavefield within a preset distance range near the undulating surface during the acoustic wave simulation. Based on the first and second reflected wave seismic data, the gradient of the reflection coefficient model under the target undulating surface conditions is determined. The reflection coefficient model under the target undulating surface conditions is updated according to the gradient of the reflection coefficient model. This solution considers the conditions of undulating surfaces and updates the wavefield within the range near the undulating surface during the acoustic wave simulation based on an immersion absorbing boundary. The iteratively updated reflection coefficient model is closer to the reflection coefficient under real conditions, enabling direct migration imaging of seismic data from undulating surfaces. It also stably compensates for seismic wave amplitude attenuation and velocity dispersion caused by the absorption and attenuation characteristics of the subsurface medium, resulting in high computational efficiency and a convenient implementation process.

[0018] The above description of the invention is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0019] The above and other features, advantages, and aspects of the various embodiments of the present invention will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the originals and elements are not necessarily drawn to scale.

[0020] Figure 1 This is a flowchart illustrating a method for determining a reflection coefficient model under undulating surface conditions, provided in an embodiment of the present invention.

[0021] Figure 2 A schematic diagram illustrating the implementation process of an immersion absorption boundary provided in an embodiment of the present invention;

[0022] Figure 3 A flowchart illustrating another method for determining the reflection coefficient model under undulating surface conditions provided in an embodiment of the present invention;

[0023] Figure 4 A schematic diagram of the structure of a device for determining the reflection coefficient model under undulating surface conditions provided in an embodiment of the present invention;

[0024] Figure 5 This is a schematic diagram of an electronic device for determining a reflection coefficient model under undulating surface conditions, as provided in an embodiment of the present invention. Detailed Implementation

[0025] Embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While some 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 construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the invention. It should be understood that the accompanying drawings and embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the invention.

[0026] It should be understood that the various steps described in the method embodiments of the present invention may be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of the present invention is not limited in this respect.

[0027] The term "comprising" and its variations as used herein are open-ended inclusions, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". Definitions of other terms will be given in the description below.

[0028] It should be noted that the concepts of "first" and "second" mentioned in this invention are only used to distinguish different devices, modules or units, and are not used to limit the order of functions performed by these devices, modules or units or their interdependencies.

[0029] It should be noted that the terms "a" and "a plurality of" used in this invention are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0030] The names of the messages or information exchanged between the multiple devices in the embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of these messages or information.

[0031] Figure 1 This is a flowchart illustrating a method for determining a reflection coefficient model under undulating surface conditions, provided by an embodiment of the present invention. This embodiment is applicable to determining a reflection coefficient model under undulating surface conditions. The method can be executed by a device for determining the reflection coefficient model under undulating surface conditions. This device can be implemented in software and / or hardware and is generally integrated into any electronic device with network communication capabilities, such as a mobile terminal, PC, or server. Figure 1As shown, the method for determining the reflection coefficient model under undulating surface conditions according to embodiments of the present invention may include the following process:

[0032] S110. Based on the immersion absorption boundary, perform viscous acoustic wave Bonn simulation to determine the reflected wave field under the target undulating surface conditions, and record the reflected wave field to obtain the first reflected wave seismic data. The immersion absorption boundary is used to update the wave field within a preset distance range of the adjacent undulating surface during the acoustic wave simulation process.

[0033] The undulating surface is used to reflect the undulation of the earth's surface. The reflected wave field is the wave field formed when seismic waves are reflected due to different medium surfaces during transmission. The reflected wave field under the target undulating surface conditions can be determined based on the target undulating surface conditions, velocity model, quality factor model, and related viscous acoustic wave equations.

[0034] When a wave propagates to an area near an undulating surface, the irregular surface boundary conditions can affect the propagation path of the seismic wave, resulting in reflection or diffraction from the free surface, which in turn affects the migration imaging results. Therefore, during the simulation of the reflected wave field, the reflected wave can be processed based on the immersion absorption boundary, so that the wave field within a preset distance range near the undulating surface can be updated during the viscous acoustic wave simulation.

[0035] After determining the reflected wave field under the target undulating surface conditions, the reflected wave field can be recorded to obtain the first reflected wave seismic data.

[0036] As an optional but non-limiting implementation, the process of implementing the immersion absorbing boundary may include the following steps A1-A5:

[0037] Step A1: Determine the ghost nodes based on the undulating surface information and the length of the difference operator; the ghost nodes are the grid nodes that need to be used for the difference calculation of the grid nodes above and below the undulating surface.

[0038] The information on undulating terrain can be obtained based on actual survey data. The length of the difference operator is the operator length used in the finite difference method. Figure 2 A schematic diagram illustrating the implementation process of an immersion absorption boundary provided by an embodiment of the present invention, as shown below. Figure 2 As shown in the figure, the meshing of part of the model is illustrated. F is the center point of the difference operator, and the black dashed line represents the undulating surface. Based on the undulating surface information, all mesh nodes can be divided into inner nodes below the surface and outer nodes above and below the surface.

[0039] Ghost nodes can be determined based on information about undulating terrain and the length of the difference operator. Figure 2The black solid triangle points in the diagram are ghost nodes. Ghost nodes are grid nodes used for differential calculations of grid nodes above and below the undulating surface. Ghost nodes are located in the absorption region above the surface.

[0040] Step A2: Determine the direction of the normal to the ground surface based on the projection point of the ghost node on the ground surface.

[0041] Specifically, for each ghost node, its projection point on the undulating surface can be determined, and thus the normal direction of the surface corresponding to the ghost node at this location can be determined. Figure 2 G1 is one of the ghost nodes. The projection point of ghost node G1 on the ground is B1. The black dashed arrow indicates the direction of the normal to the ground.

[0042] Step A3: Determine the preset number of Li ao boundary points for ghost nodes based on the normal direction of the ground surface.

[0043] Specifically, a predetermined number of grid nodes are determined along the surface normal direction and at equal grid intervals. If these determined grid nodes are located below the surface, they are considered Li ao boundary points. However, if any of these determined grid nodes are located above the surface at non-integer positions, then a corresponding number of Li ao boundary points need to be added along the surface normal direction. The predetermined number can be set based on actual needs; for example, it can be set to four. Figure 2 As shown, Figure 2 The black dashed arrows in the diagram indicate that A1, A2, A3, and A4 are the four Li ao boundary points determined with respect to the ghost node G1.

[0044] Step A4: Update the wave field of the ghost node based on the wave field values ​​of a preset number of Li ao boundary points.

[0045] The wave field values ​​at the Li ao boundary points can be determined using Lagrange interpolation. Specifically, a corresponding interpolation window can be determined for each Li ao boundary point, such as... Figure 2 As shown, Figure 2 The black dashed box in the diagram represents the interpolation window corresponding to the Li ao boundary point A1. This interpolation window is 4×4, and the wave field value of the Li ao boundary point A1 can be determined using the Lagrange interpolation method. Similarly, the wave field values ​​corresponding to a preset number of Li ao boundary points can be determined.

[0046] After obtaining the wavefield values ​​of each Liao boundary point, the wavefield of the ghost node can be updated. In this embodiment, the following formula can be used to update the wavefield of the ghost node:

[0047]

[0048] Where G1 is a specific ghost node; p G1 p is the wave field value of the ghost node G1. A1 p A2 p A3 and p A4 These are the wave field values ​​of each Liao boundary point corresponding to the ghost node G1; T 1,2 =s(2-s), v is the velocity of the ghost node. Since the ghost node is located on the undulating surface, the velocity value of the ghost node can be considered as the velocity of the ghost node at its location on the surface; Δt is the time sampling interval; Δx is the spatial sampling interval, which is the grid spacing formed after dividing the model space using a rectangular grid.

[0049] Step A5: Update the wave field of the internal boundary points based on the wave field updated by the ghost nodes. The internal boundary points are grid nodes within a preset distance range of the nearby undulating surface.

[0050] After updating the wavefield of the ghost nodes, the wavefield of the internal boundary points can be updated based on the updated wavefield of the ghost nodes. The internal boundary points are grid nodes within a preset distance range of the nearby undulating terrain. For example... Figure 2 As shown, Figure 2 The solid black dots in the diagram represent internal boundary points, which are located within a preset range adjacent to the undulating surface. By updating the wave field at these internal boundary points, the influence of surface boundary reflections on the simulation results is eliminated to some extent. This enables the updating of the wave field within a preset distance range adjacent to the undulating surface during viscous acoustic wave simulation, thereby improving the accuracy of the viscous acoustic wave simulation process.

[0051] S120. Based on the first reflection wave seismic data and the second reflection wave seismic data, determine the gradient of the reflection coefficient model under the target undulating surface conditions. The second reflection wave seismic data is the reflection wave seismic data obtained from actual observations under the target undulating surface conditions.

[0052] The reflection coefficient model describes the reflection capability of seismic waves at different locations underground. Differences in the geological medium and depth of the seismic waves will result in different reflection coefficients at different locations. The gradient of the reflection coefficient model refers to the rate at which the model changes and adjusts; the gradient reflects the direction and magnitude of these parameter changes.

[0053] The first reflection wave seismic data is obtained by performing a viscous acoustic Bonn simulation and recording the seismic data under the target undulating surface conditions. The second reflection wave seismic data is obtained by actual observation of the target undulating surface. Based on the two reflection wave seismic data, the degree of difference between the simulated data and the actual data can be measured. Furthermore, based on the degree of difference between the two, the gradient of the reflection coefficient model under the target undulating surface conditions can be determined.

[0054] S130. Update the reflection coefficient model under the target undulating surface conditions based on the gradient of the reflection coefficient model under the target undulating surface conditions.

[0055] Once the gradient of the reflection coefficient model under the target undulating surface conditions is obtained, it's equivalent to knowing the direction and magnitude of each iteration update, allowing for iterative updates of the reflection coefficient model. This continues until the resulting reflection coefficient model more closely approximates the actual situation. This model can then be used for seismic layer analysis imaging, helping to generate high-resolution images of subsurface structures. Simultaneously, it aids researchers in understanding and distinguishing different geological layers, identifying faults, fractures, and other structures, and helping to locate resources such as oil and natural gas.

[0056] The technical solution provided by this invention determines the reflected wavefield under target undulating surface conditions using viscous acoustic wave Born simulation based on an immersion absorbing boundary, and records the reflected wavefield to obtain first reflected wave seismic data. The immersion absorbing boundary is used to update the wavefield within a preset distance range near the undulating surface during the acoustic wave simulation. Based on the first and second reflected wave seismic data, the gradient of the reflection coefficient model under the target undulating surface conditions is determined. The reflection coefficient model under the target undulating surface conditions is updated according to the gradient of the reflection coefficient model. This solution considers the conditions of undulating surfaces and updates the wavefield within the range near the undulating surface during the acoustic wave simulation based on an immersion absorbing boundary. The iteratively updated reflection coefficient model is closer to the reflection coefficient under real conditions, enabling direct migration imaging of seismic data from undulating surfaces. It also stably compensates for seismic wave amplitude attenuation and velocity dispersion caused by the absorption and attenuation characteristics of the subsurface medium, resulting in high computational efficiency and a convenient implementation process.

[0057] Figure 3 This is a flowchart illustrating another method for determining the reflection coefficient model under undulating surface conditions provided by an embodiment of the present invention. The technical solution of this embodiment further optimizes the process of determining the gradient of the reflection coefficient model under the target undulating surface conditions based on the first and second reflected wave seismic data in the aforementioned embodiments, building upon the technical solutions of the above embodiments. This embodiment can be combined with various optional solutions in one or more of the above embodiments. Figure 3As shown, the method for determining the reflection coefficient model under undulating surface conditions according to an embodiment of the present invention may include the following process:

[0058] S310. Based on the immersion absorbing boundary, perform viscous acoustic wave Bonn simulation to determine the reflected wave field under the target undulating surface conditions, and record the reflected wave field to obtain the first reflected wave seismic data. The immersion absorbing boundary is used to update the wave field within a preset distance range of the adjacent undulating surface during the acoustic wave simulation process.

[0059] As an optional but non-limiting approach, determining the reflected wave field under undulating surface conditions of the target may include the following steps B1-B2:

[0060] Step B1: In the first forward modeling simulation, the background wave field under the target undulating surface conditions is determined based on the viscous acoustic wave equation and the background velocity; where the background velocity is the propagation speed of seismic waves in the medium.

[0061] Forward modeling refers to simulating the propagation of seismic waves based on a known geological model. The viscous acoustic wave equation used in this embodiment is a second-order viscous acoustic wave equation. Using the viscous acoustic wave equation can compensate for the amplitude attenuation and velocity dispersion of seismic waves caused by the absorption and attenuation characteristics of the underground medium, and also takes into account the influence of seismic waves in viscous media.

[0062] The specific viscous acoustic wave equation used in this embodiment is as follows:

[0063]

[0064] Where p(x;t) represents the wavefield variable; r(x;t) represents the memory variable, which describes the accumulation of the wavefield in time or space; Q(x) represents the quality factor, which describes the degree of absorption and attenuation of the subsurface medium at different locations; τ(x) and τ σ (x) represents the variable related to the quality factor; t represents the time step in the simulation process; x represents different spatial locations in geology, and spatial location x can be denoted as x(x,y,z); v(x) represents the velocity at different spatial locations x.

[0065] Specifically, based on the above viscous acoustic wave equation and by substituting the relevant parameter values, the background wave field under the target undulating surface conditions can be determined.

[0066] Step B2: In the second forward modeling, the background wave field under the undulating surface conditions of the target is used as the source, and the reflected wave field under the undulating surface conditions of the target is calculated based on the Born approximation.

[0067] Specifically, in the second forward modeling, the background wave field under the undulating surface conditions of the target is used as the source to determine the corresponding reflected wave field during the simulation. The reflected wave field under the undulating surface conditions of the target can be calculated based on the Born approximation. Using the Born approximation, the perturbation terms in the wave equation can be treated as small perturbations, and a series of approximations can simplify the solution process, thereby achieving a fast and efficient solution for the reflected wave field.

[0068] As an optional but non-limiting implementation, calculating the reflected wave field under undulating surface conditions based on the Born approximation may include the following steps C1-C2:

[0069] Step C1: Determine the inverse migration equations of the viscous acoustic wave equations based on the Born approximation.

[0070] Based on the Born approximation theory, it is assumed that the disturbance of the seismic wave field is mainly caused by velocity disturbance, and the velocity can be obtained by superimposing the background velocity and the disturbance velocity, that is, the velocity v = v0 + δv; where v0 is the background velocity and δv is the disturbance velocity.

[0071] Accordingly, the wave field is obtained by superimposing the background wave field and the perturbation wave field, so the wave field p = p0 + δp; where p0 is the background wave field and δp is the perturbation wave field. Then, the velocity v and the wave field p can be substituted into the viscous acoustic wave equation. During the calculation and solution process, the Taylor approximation is used, letting 1 / (v0 + δv) 2 ≈1 / v0 2 -2δv / v0 3 Therefore, the following intermediate step formula can be obtained:

[0072]

[0073] Where r0 is the background memory variable and δr is the perturbation memory variable.

[0074] Furthermore, subtracting the obtained intermediate formula from the initial viscous acoustic wave equation yields the inverse offset equation set of the viscous acoustic wave equation. The specific inverse offset equation set of the viscous acoustic wave equation calculated in this embodiment is as follows:

[0075]

[0076] Wherein, s(t)δ(xx) s () indicates that the shot point is at x = x s The point of origin is the point where the seismic wave is generated; m is the reflection coefficient model.

[0077] Step C2: Calculate the reflected wave field under the undulating surface conditions of the target based on the inverse migration equation set of the viscous acoustic wave equation.

[0078] The inverse migration equations of the viscous acoustic wave equations contain a perturbation wave field, which is the reflected wave field generated when the background wave field is used as the source. Therefore, the reflected wave field under the condition of the target undulating surface can be calculated based on the inverse migration equations of the viscous acoustic wave equations.

[0079] After obtaining the reflected wave field, the reflected wave field can be recorded, and the corresponding first reflected wave seismic data can be obtained.

[0080] It should be noted that the immersion absorption boundary was used in the process of simulating and recording the background wave field and the reflected wave field to update the wave field within a preset distance range of the nearby undulating surface.

[0081] S320. Determine the residual data under the target undulating surface conditions based on the first reflection wave seismic data and the second reflection wave seismic data.

[0082] The second reflection wave seismic data is obtained through actual observation of the target's undulating surface conditions. The residual data is the first reflection wave seismic data minus the second reflection wave seismic data.

[0083] Before calculating the residual data, an objective function for the reflection coefficient model can be established. In this embodiment, an objective function based on the L2 norm can be established, and the specific objective function is as follows:

[0084]

[0085] Where J is the objective function of the reflection coefficient model m; d syn This refers to the first reflection wave seismic data; d obs This is the seismic data for the second reflection wave.

[0086] S330, reverse propagation residual data, and determine the associated wave field under the target undulating surface conditions based on the associated state method.

[0087] Backpropagation of residual data specifically involves propagating the residual data backwards to update the model's parameters. Specifically, based on the adjoint state method, the viscous acoustic wave equation can be written in matrix form as follows:

[0088]

[0089] Then, the adjoint matrix corresponding to this matrix is ​​determined. Specifically, the determined adjoint matrix takes the following form:

[0090]

[0091] Where q represents the adjoint wave field; s represents the adjoint memory variable; and Δd is the residual data of the reverse-time input.

[0092] Furthermore, after transforming the obtained adjoint matrix into equation form, we can obtain the following equation regarding the adjoint wave field q:

[0093]

[0094] Where q(x;t) is the adjoint wave field; s(x;t) is the adjoint memory variable.

[0095] It should be noted that the immersion absorbing boundary was also used in the simulation of the accompanying wave field to update the wave field within a preset distance range of the nearby undulating surface.

[0096] S340. Perform zero-delay cross-correlation calculation between the background wave field and the accompanying wave field under the target undulating surface condition to obtain the gradient of the reflection coefficient model under the target undulating surface condition.

[0097] Zero-delay cross-correlation refers to the absence of time or space delay between two sets of data. Since the background wavefield reflects the wavefield obtained from forward simulation and the adjoint wavefield reflects the wavefield obtained from backward propagation, the gradient of the reflection coefficient model under the target undulating surface conditions can be obtained by performing zero-delay cross-correlation calculation between the background wavefield and the adjoint wavefield, and can then be used for subsequent updates to the reflection coefficient model.

[0098] In this embodiment, the zero-delay cross-correlation calculation of the background wavefield and the adjoint wavefield can be achieved by calculating the partial derivative of the objective function with respect to the reflectivity model. Specifically, the gradient of the reflectivity model under the undulating surface conditions of the target can be calculated according to the following formula:

[0099]

[0100] S350. Update the reflection coefficient model under the target undulating surface conditions based on the gradient of the reflection coefficient model under the target undulating surface conditions.

[0101] As an optional but non-limiting implementation, updating the reflection coefficient model under the target undulating surface conditions based on the gradient of the reflection coefficient model can include the following steps D1-D2:

[0102] Step D1: Calculate the update direction and update step size of the gradient of the reflection coefficient model based on the conjugate gradient method.

[0103] The update direction reflects the adjustment direction when updating the reflection coefficient model. To make the reflection coefficient model closer to the reflection coefficient of the actual underground situation, that is, to minimize the difference between the two, the reflection model needs to be updated in the negative gradient direction. The update step size reflects the magnitude of the adjustment of the reflection coefficient model in each update.

[0104] Specifically, in this embodiment, the update direction and update step size of the gradient of the reflection coefficient model are calculated based on the conjugate gradient method, which can be expressed by the following formula:

[0105]

[0106] Where the exponent n represents the number of iterations, i.e., n represents the nth iteration, and n+1 represents the (n+1)th iteration; g n P represents the gradient at the nth iteration; T represents the transpose of the matrix; P -1 β is the inverse matrix of the preconditioner operator P; n z is the conjugate gradient correction factor; n The model descent direction is represented by L; L represents the inverse offset operator; α n This indicates the gradient update step size.

[0107] Step D2: Based on the gradient update direction and update step size of the reflection coefficient model and the preset iterative formula, iteratively update the reflection coefficient model and obtain the least squares reverse time offset result at the end of the iterative update; the least squares reverse time offset result is the reflection coefficient model at the end of the iterative update; the preset iterative formula is used to reflect the correlation between every two iterations of the reflection coefficient model during the iterative process.

[0108] After obtaining the gradient update direction and update step size of the reflection coefficient model, the reflection coefficient model can be iteratively updated using a preset iterative formula, and the least squares reverse time offset result is obtained at the end of the iterative update. The least squares reverse time offset result is the reflection coefficient model at the end of the iterative update. The preset iterative formula is used to reflect the correlation between every two iterations of the reflection coefficient model during the iterative process.

[0109] The conditions for ending the iterative update are: the iterative update ends when the number of iterations reaches a preset number; or the iterative update ends when the objective function value obtained after iteration is less than a set threshold.

[0110] As an optional but non-limiting implementation, the preset iteration formula in this embodiment is:

[0111] m n+1 =m n +α n+1 z n+1 ;

[0112] Where m represents the reflection coefficient model under the undulating surface conditions of the target, n represents the number of iterations, and α n+1 Z represents the gradient update step size. n+1 This indicates the direction of descent in the model.

[0113] The technical solution provided by this invention determines the reflected wavefield under target undulating surface conditions using viscous acoustic wave Born simulation based on an immersion absorbing boundary, and records the reflected wavefield to obtain first reflected wave seismic data. The immersion absorbing boundary is used to update the wavefield within a preset distance range near the undulating surface during the acoustic wave simulation. Based on the first and second reflected wave seismic data, the gradient of the reflection coefficient model under the target undulating surface conditions is determined. The reflection coefficient model under the target undulating surface conditions is updated according to the gradient of the reflection coefficient model. This solution considers the conditions of undulating surfaces and updates the wavefield within the range near the undulating surface during the acoustic wave simulation based on an immersion absorbing boundary. The iteratively updated reflection coefficient model is closer to the reflection coefficient under real conditions, enabling direct migration imaging of seismic data from undulating surfaces. It also stably compensates for seismic wave amplitude attenuation and velocity dispersion caused by the absorption and attenuation characteristics of the subsurface medium, resulting in high computational efficiency and a convenient implementation process.

[0114] Figure 4 This is a schematic diagram of a device for determining the reflection coefficient model under undulating surface conditions, provided in an embodiment of the present invention. This embodiment is applicable to determining the reflection coefficient model under undulating surface conditions. The device for determining the reflection coefficient model under undulating surface conditions can be implemented in software and / or hardware, and is generally integrated into any electronic device with network communication capabilities, such as a mobile terminal, PC, or server. Figure 4 As shown, the apparatus for determining the reflection coefficient model under undulating surface conditions according to an embodiment of the present invention may include a first reflected wave seismic data determination module 410, a gradient determination module 420, and a reflection coefficient model update module 430. Wherein:

[0115] The first reflection wave seismic data determination module 410 is used to determine the reflection wave field under the target undulating surface conditions based on the viscous acoustic wave Bonn simulation based on the immersion absorption boundary, and to record the reflection wave field to obtain the first reflection wave seismic data. The immersion absorption boundary is used to update the wave field within a preset distance range of the adjacent undulating surface during the acoustic simulation process.

[0116] The gradient determination module 420 is used to determine the gradient of the reflection coefficient model under the target undulating surface conditions based on the first reflected wave seismic data and the second reflected wave seismic data, wherein the second reflected wave seismic data is reflected wave seismic data obtained by actual observation under the target undulating surface conditions.

[0117] The reflection coefficient model update module 430 is used to update the reflection coefficient model under the target undulating surface conditions according to the gradient of the reflection coefficient model under the target undulating surface conditions.

[0118] As an optional but non-limiting implementation, determining the reflected wave field under the target undulating surface conditions includes:

[0119] In the first forward modeling simulation, the background wave field under the undulating surface conditions of the target was determined based on the viscous acoustic wave equation and the background velocity; where the background velocity is the propagation speed of the wave in the medium.

[0120] In the second forward modeling simulation, the background wave field under the undulating surface conditions of the target was used as the source, and the reflected wave field under the undulating surface conditions of the target was calculated based on the Born approximation.

[0121] As an optional but non-restrictive implementation, the implementation process of immersion absorbing boundaries includes:

[0122] Ghost nodes are determined based on undulating surface information and the length of the difference operator; the ghost nodes are the grid nodes used for the difference calculation of grid nodes above and below the undulating surface.

[0123] Based on the projection point of the ghost node on the ground surface, the normal direction of the ground surface is determined;

[0124] A predetermined number of Li ao boundary points are determined based on the normal direction of the ground surface to identify the ghost node.

[0125] The wave field of the ghost node is updated based on the wave field values ​​of the preset number of Li ao boundary points;

[0126] The wave field of the internal boundary point is updated based on the wave field updated by the ghost node. The internal boundary point is a grid node within a preset distance range of the nearby undulating surface.

[0127] As an optional but non-limiting implementation, the reflected wave field under undulating surface conditions of the target is calculated based on the Born approximation, including:

[0128] The inverse offset equations of the viscous acoustic wave equations are determined based on the Born approximation.

[0129] The reflected wave field under the undulating surface conditions of the target is calculated based on the inverse migration equation set of the viscous acoustic wave equation.

[0130] As an optional but non-limiting implementation, based on the first and second reflected wave seismic data, the gradient of the reflection coefficient model under the target undulating surface conditions is determined, including:

[0131] Based on the first and second reflection wave seismic data, determine the residual data corresponding to the reflection coefficient model under the target undulating surface conditions;

[0132] The residual data is back-transmitted, and the associated wave field under the target undulating surface conditions is determined based on the associated state method.

[0133] The gradient of the reflection coefficient model under the target undulating surface condition is obtained by performing zero-delay cross-correlation between the background wave field and the accompanying wave field under the target undulating surface condition.

[0134] As an optional but non-limiting implementation, the reflection coefficient model under the target undulating surface conditions is updated based on the gradient of the reflection coefficient model under the target undulating surface conditions, including:

[0135] The update direction and update step size of the gradient of the reflection coefficient model are calculated based on the conjugate gradient method.

[0136] The reflection coefficient model is iteratively updated based on the gradient update direction and update step size of the reflection coefficient model and the preset iterative formula. At the end of the iterative update, the least squares inverse time offset result is obtained. The least squares inverse time offset result is the reflection coefficient model at the end of the iterative update. The preset iterative formula is used to reflect the correlation between every two iterations of the reflection coefficient model during the iterative process.

[0137] As an optional but non-restrictive implementation, the default iteration formula is:

[0138] m n+1 =m n +α n+1 z n+1 ;

[0139] Where m represents the reflection coefficient model under the undulating surface conditions of the target, n represents the number of iterations, and α n+1 Z represents the gradient update step size. n+1 This indicates the direction of descent in the model.

[0140] The technical solution provided by this invention determines the reflected wavefield under target undulating surface conditions using viscous acoustic wave Born simulation based on an immersion absorbing boundary, and records the reflected wavefield to obtain first reflected wave seismic data. The immersion absorbing boundary is used to update the wavefield within a preset distance range near the undulating surface during the acoustic wave simulation. Based on the first and second reflected wave seismic data, the gradient of the reflection coefficient model under the target undulating surface conditions is determined. The reflection coefficient model under the target undulating surface conditions is updated according to the gradient of the reflection coefficient model. This solution considers the conditions of undulating surfaces and updates the wavefield within the range near the undulating surface during the acoustic wave simulation based on an immersion absorbing boundary. The iteratively updated reflection coefficient model is closer to the reflection coefficient under real conditions, enabling direct migration imaging of seismic data from undulating surfaces. It also stably compensates for seismic wave amplitude attenuation and velocity dispersion caused by the absorption and attenuation characteristics of the subsurface medium, resulting in high computational efficiency and a convenient implementation process.

[0141] The device for determining the reflection coefficient model under undulating surface conditions provided in this embodiment of the invention can be used to execute the method for determining the reflection coefficient model under undulating surface conditions, and has the corresponding functional modules and beneficial effects for executing the method for determining the reflection coefficient model under undulating surface conditions.

[0142] It is worth noting that the various units and modules included in the above-mentioned device are only divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be realized; in addition, the specific names of each functional unit are only for easy differentiation and are not used to limit the protection scope of the embodiments of the present invention.

[0143] Figure 5 This is a schematic diagram of an electronic device for determining a reflection coefficient model under undulating surface conditions, as provided in an embodiment of the present invention. (Refer to the following...) Figure 5 This diagram illustrates a structural schematic of an electronic device 510 suitable for implementing embodiments of the present invention. The terminal devices in these embodiments may include, but are not limited to, mobile terminals such as mobile phones, laptops, digital broadcast receivers, PDAs (personal digital assistants), PADs (tablet computers), PMPs (portable multimedia players), in-vehicle terminals (e.g., in-vehicle navigation terminals), and fixed terminals such as digital TVs and desktop computers. Figure 5 The electronic device shown is merely an example and should not be construed as limiting the functionality and scope of the embodiments of the present invention.

[0144] like Figure 5As shown, the electronic device 510 includes at least one processor 511 and a memory, such as a read-only memory (ROM) 512 or a random access memory (RAM) 513, communicatively connected to the at least one processor 511. The memory stores computer programs executable by the at least one processor. The processor 511 can perform various appropriate actions and processes based on the computer program stored in the ROM 512 or loaded from storage unit 518 into the RAM 513. The RAM 513 may also store various programs and data required for the operation of the electronic device 510. The processor 511, ROM 512, and RAM 513 are interconnected via a bus 514. An input / output (I / O) interface 515 is also connected to the bus 514.

[0145] Multiple components in electronic device 510 are connected to I / O interface 515, including: input unit 516, such as keyboard, mouse, etc.; output unit 517, such as various types of displays, speakers, etc.; storage unit 518, such as disk, optical disk, etc.; and communication unit 519, such as network card, modem, wireless transceiver, etc. Communication unit 519 allows electronic device 510 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0146] Processor 511 can be a variety of general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of processor 511 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. Processor 511 executes the method for determining the reflection coefficient model under undulating surface conditions provided in any embodiment of the present invention.

[0147] In particular, according to embodiments of the present invention, the processes described above with reference to the flowchart can be implemented as computer software programs. For example, embodiments of the present invention include a computer program product comprising a computer program carried on a non-transitory computer-readable medium, the computer program containing program code for performing the method for determining a reflection coefficient model under undulating surface conditions as shown in the flowchart. When executed by a processing device, the above-described functions defined in the method for determining a reflection coefficient model under undulating surface conditions according to embodiments of the present invention are performed.

[0148] The names of the messages or information exchanged between the multiple devices in the embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of these messages or information.

[0149] The electronic device provided in this embodiment of the invention and the method for determining the reflection coefficient model under undulating surface conditions provided in the above embodiments belong to the same inventive concept. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.

[0150] This invention provides a computer storage medium storing a computer program that, when executed by a processor, implements the method for determining the reflection coefficient model under undulating surface conditions provided in the above embodiments.

[0151] It should be noted that the computer-readable medium described above in this invention can be a computer-readable signal medium, a computer-readable storage medium, or any combination thereof. A computer-readable storage medium can be, for example,—but not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of a computer-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this invention, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. In this invention, a computer-readable signal medium can include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A computer-readable signal medium can be any computer-readable medium other than a computer-readable storage medium, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the computer-readable medium can be transmitted using any suitable medium, including but not limited to: wires, optical fibers, RF (radio frequency), etc., or any suitable combination thereof.

[0152] In some implementations, clients and servers can communicate using any currently known or future-developed network protocol such as HTTP (Hypertext Transfer Protocol) and can interconnect with digital data communication (e.g., communication networks) of any form or medium. Examples of communication networks include local area networks (“LANs”), wide area networks (“WANs”), the Internet (e.g., the Internet of Things), and peer-to-peer networks (e.g., ad hoc peer-to-peer networks), as well as any currently known or future-developed networks.

[0153] The aforementioned computer-readable medium may be included in the aforementioned electronic device; or it may exist independently and not assembled into the electronic device.

[0154] Computer program code for performing the operations of this invention can be written in one or more programming languages ​​or a combination thereof, including but not limited to object-oriented programming languages ​​such as Java, Smalltank, and C++, as well as conventional procedural programming languages ​​such as "C" or similar languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0155] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0156] The units described in the embodiments of the present invention can be implemented in software or in hardware. The name of a unit does not necessarily limit the unit itself; for example, the first acquisition unit can also be described as "a unit that acquires at least two Internet Protocol addresses".

[0157] The functions described above in this document can be performed, at least in part, by one or more hardware logic components. For example, exemplary types of hardware logic components that can be used, without limitation, include: Field Programmable Gate Arrays (FPGAs), Application-Specific Integrated Circuits (ASICs), Application-Specific Standard Products (ASSPs), System-on-Chip (SoCs), Complex Programmable Logic Devices (CPLDs), and so on.

[0158] In the context of this invention, a machine-readable medium can be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. Machine-readable media can include, but are not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0159] The above description is merely a preferred embodiment of the present invention and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of disclosure in this invention is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this invention.

[0160] Furthermore, while the operations are described in a specific order, this should not be construed as requiring these operations to be performed in the specific order shown or in sequential order. In certain circumstances, multitasking and parallel processing may be advantageous. Similarly, while several specific implementation details are included in the above discussion, these should not be construed as limiting the scope of the invention. Certain features described in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments.

[0161] Although the subject matter has been described using language specific to structural features and / or methodological logic, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are merely illustrative examples of implementing the claims.

Claims

1. A method of determining a reflection coefficient model in a rough surface condition, characterized by, The method comprises: determining a reflected wave field under a target undulating surface condition based on an immersed absorbing boundary, the immersed absorbing boundary being used to update a wave field within a preset distance range adjacent to the undulating surface during acoustic wave simulation, and recording the reflected wave field to obtain first reflected wave seismic data; determining a gradient of a reflection coefficient model under the target undulating surface condition based on the first reflected wave seismic data and second reflected wave seismic data, the second reflected wave seismic data being actual observation reflected wave seismic data obtained under the target undulating surface condition; updating the reflection coefficient model under the target undulating surface condition according to the gradient of the reflection coefficient model under the target undulating surface condition.

2. The method of claim 1, wherein, The determination of the reflected wave field under the target undulating surface condition comprises: in a first forward simulation, determining a background wave field under the target undulating surface condition based on a viscous acoustic wave equation and a background velocity; wherein the background velocity is the propagation velocity of a wave in a medium; in a second forward simulation, taking the background wave field under the target undulating surface condition as a source, and calculating a reflected wave field under the target undulating surface condition based on Born approximation.

3. The method of claim 1, wherein, The implementation process of the immersed absorbing boundary comprises: determining a ghost node according to undulating surface information and a difference operator length; the ghost node being a grid node used for difference calculation of a grid node above the undulating surface and below the surface; determining a normal direction of the surface based on a projection point of the ghost node on the surface; determining a preset number of Liao boundary points of the ghost node based on the normal direction of the surface; updating a wave field of the ghost node based on a wave field value of the preset number of Liao boundary points; updating a wave field of an internal boundary point based on the updated wave field of the ghost node, the internal boundary point being a grid node within a preset distance range adjacent to the undulating surface.

4. The method of claim 2, wherein, The calculation of the reflected wave field under the target undulating surface condition based on Born approximation comprises: determining an inverse migration equation set of the viscous acoustic wave equation based on Born approximation, calculating a reflected wave field under the target undulating surface condition based on the inverse migration equation set of the viscous acoustic wave equation.

5. The method of claim 1, wherein, The determination of the gradient of the reflection coefficient model under the target undulating surface condition based on the first reflected wave seismic data and the second reflected wave seismic data comprises: determining residual data corresponding to the reflection coefficient model under the target undulating surface condition based on the first reflected wave seismic data and the second reflected wave seismic data; back-propagating the residual data and determining an adjoint wave field under the target undulating surface condition based on an adjoint state method; performing zero-delay cross-correlation calculation on a background wave field under the target undulating surface condition and the adjoint wave field under the target undulating surface condition to obtain the gradient of the reflection coefficient model under the target undulating surface condition.

6. The method of claim 1, wherein, The updating of the reflection coefficient model under the target undulating surface condition according to the gradient of the reflection coefficient model under the target undulating surface condition comprises: calculating an updating direction and an updating step length of the gradient of the reflection coefficient model based on a conjugate gradient method; The reflection coefficient model is iteratively updated based on an update direction and an update step length of a gradient of the reflection coefficient model and a preset iteration formula, and a least square reverse time migration result is obtained at the end of the iterative update; the least square reverse time migration result is the reflection coefficient model at the end of the iterative update; and the preset iteration formula is used to reflect a correlation between every two iterations in the iterative process.

7. The method of claim 6, wherein, The preset iteration formula is: m n+1 = m n + a n+1 z n+1 ; Wherein, m represents the reflection coefficient model under the target relief surface condition, n represents the iteration number, a n+1 represents the gradient update step, Z n+1 represents the model descent direction.

8. An apparatus for determining a reflection coefficient model in a rough surface condition, characterized by The apparatus comprises: A first reflected wave seismic data determination module is configured to determine a reflected wave field under a target undulating surface condition based on an immersed absorbing boundary, and record the reflected wave field to obtain first reflected wave seismic data, wherein the immersed absorbing boundary is configured to update a wave field within a preset distance range adjacent to the undulating surface during acoustic wave simulation; A gradient determination module is configured to determine a gradient of a reflection coefficient model under the target undulating surface condition based on the first reflected wave seismic data and second reflected wave seismic data, wherein the second reflected wave seismic data is actual observation reflected wave seismic data obtained under the target undulating surface condition; A reflection coefficient model update module is configured to update the reflection coefficient model under the target undulating surface condition according to the gradient of the reflection coefficient model under the target undulating surface condition.

9. An electronic device, comprising: The electronic device comprises: one or more processors; a storage device configured to store one or more programs, when the one or more programs are executed by the one or more processors, the one or more processors are caused to implement the method for determining a reflection coefficient model under an undulating surface condition according to any one of claims 1-7.

10. A storage medium containing computer-executable instructions, wherein: The computer executable instructions, when executed by a computer processor, are configured to implement the method for determining a reflection coefficient model under an undulating surface condition according to any one of claims 1-7.

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