Angle domain dynamic focusing beam reverse time migration method and device, electronic equipment and medium

Abstract

This application discloses a method, apparatus, electronic device, and medium for angle-domain dynamic focusing beam reverse-time migration. The migration method includes: modifying complex-valued beam parameters; constructing a dynamic focusing beam operator based on the modified complex-valued beam parameters; constructing a Green's function using the dynamic focusing beam operator; performing forward and reverse wave field extensions using the Green's function; cross-correlating the forward and reverse wave field extensions along the time direction to obtain single-shot imaging results; and combining the single-shot imaging results with the propagation angle used in the dynamic focusing beam calculation to extract the angle-domain common imaging point gather. This invention applies the concept of dynamic focusing beam to Gaussian beam reverse-time migration, uses a dynamic focusing beam operator to construct a Green's function, thereby achieving forward and reverse wave field extensions, and finally obtains the imaging results through their cross-correlation. Simultaneously, by combining the propagation angle information used in the dynamic focusing beam calculation, the extraction of the angle-domain common imaging point gather is directly achieved.

Description

Technical Field

[0001] This invention relates to the field of seismic migration imaging technology in oil and gas exploration and development, and more specifically, to an angle-domain dynamic focusing beam reverse time migration method, device, electronic equipment and medium. Background Technology

[0002] Seismic migration imaging, as one of the three major seismic processing technologies, plays an important role in oil and gas exploration.

[0003] (1) Focusing beam offset

[0004] In Gaussian beam migration imaging algorithms, the seismic beamwidth diverges rapidly with increasing propagation distance, severely impacting imaging accuracy. Nowack, based on the fundamental properties of Gaussian beams, proposed a focusing beam theory by placing the Gaussian beam waist within the target region and combining it with Gaussian beam migration. Subsequently, by adjusting complex-valued beam parameters, a dynamic focusing beam operator was constructed. Through multiple focusing operations, the seismic wave energy was constrained within the same beamwidth, further improving the imaging accuracy of complex structures. This led to the development of Fresnel beam and dynamically parameter-controlled seismic beam migration methods. However, due to the inherent limitations of ray theory, their imaging accuracy remains limited.

[0005] (2) Gaussian beam reverse time migration

[0006] Popov, based on the Kirchhoff integral, uses the Green's function, represented by Gaussian beam weighted integral, to achieve seismic wavefield extension. He then obtains the imaging values ​​through cross-correlation of the forward and reverse extended wavefields, proposing a Gaussian beam reverse time migration algorithm. This algorithm combines the high accuracy of reverse time migration with the high efficiency of Gaussian beam migration in the depth domain. Compared to conventional Gaussian beam migration methods, this algorithm has higher resolution, but its efficiency is relatively low due to the more intensive computation. Current research on Gaussian beam reverse time migration algorithms mainly focuses on viscoelastic acoustic media, anisotropic media, and elastic wave media.

[0007] Therefore, we look forward to an angle-domain migration imaging algorithm suitable for complex media, which can extract common imaging point gathers in the angle domain and better serve migration velocity analysis and reservoir characterization.

[0008] The information disclosed in the background section of this invention is intended only to enhance the understanding of the general background of this invention, and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art. Summary of the Invention

[0009] The purpose of this invention is to propose an angle-domain dynamic focusing beam reverse time migration method, device, electronic equipment and medium, which can effectively improve the imaging accuracy of complex targets and obtain high-quality seismic profiles.

[0010] In a first aspect, embodiments of this disclosure provide a method for reverse-time shifting of a dynamically focused beam in the angle domain, including:

[0011] Modify the complex-valued beam parameters and construct a dynamic focusing beam operator based on the modified complex-valued beam parameters;

[0012] Constructing Green's functions using dynamic focusing bundle operators;

[0013] The Green's function is used to extend the forward wave field and the reverse wave field.

[0014] Cross-correlate the forward wavefield extension and the reverse wavefield extension along the time direction to obtain the single-shot imaging result;

[0015] By combining the single-shot imaging results with the propagation angle calculated during dynamic focusing, the common imaging point gather in the angle domain is extracted.

[0016] In an optional configuration, the complex-valued beam parameters in the two-dimensional ray center coordinate system are:

[0017]

[0018] Where ε is the complex-valued beam parameter, V m For point (s) m Velocity at point 0, S m For point (s) m ,0) to point (s) n The distance l from ,0) m denoted as the width of the ray beam, N is the ratio of the complex-valued dynamic ray tracing parameters P and Q, i is the imaginary unit, Re is the real part, and Im is the imaginary part.

[0019] In the optional scheme, the modified complex-valued bundle parameters are:

[0020]

[0021] Where ε is the complex-valued beam parameter, [p1(s),q1(s)] is the plane wave solution of the dynamic ray tracing equation, [p2(s),q2(s)] is the spherical wave solution of the dynamic ray tracing equation, and ω ref The reference frequency is L, and the beam center position is L.

[0022] In an optional configuration, the Green's function is:

[0023]

[0024] Where θ is the emission angle, U θ (s,n) is the bundle operator, and Ψ(θ) is the weight coefficient, which has the following form:

[0025]

[0026] Where P and Q are complex-valued dynamic ray tracing parameters, which have the following forms:

[0027]

[0028] Where V(s) is the seismic wave propagation velocity, n is the normal distance from a point near the ray to the ray, ω is the angular frequency, τ is the travel time of the central ray, and the complex-valued beam parameter ε is ε(s) in formula (6).

[0029] In the optional scheme, the extension of the positive wave field is achieved using the following relationship:

[0030]

[0031] Where f(ω) is the Fourier transform of the seismic wavelet, G is the dynamic focusing beam eigenfunction Green's function, F is the forward propagation wavefield, and x s Let x be the location of the firing point, x be any point underground, and t be the propagation time.

[0032] In an optional approach, the extension of the reverse wave field is achieved using the following relationship:

[0033]

[0034] Among them, U (m) For t m The seismic wave field received within the time interval ≤ t ≤ T, where B is the reverse extended wave field, t m For any given moment.

[0035] In an optional approach, the single-shot imaging result is obtained using the following relationship:

[0036] I(x m ,x s )=∫B(x m ,t m )F(x m ,t;x s )dt m

[0037] Where I represents the single-shot imaging value.

[0038] In an optional approach, the propagation angle is obtained using the following formula:

[0039]

[0040] Where Φ is the propagation angle, P x For the slowness level component, P z This represents the slow vertical component.

[0041] Secondly, embodiments of this disclosure also provide an electronic device, the electronic device comprising:

[0042] At least one processor; and,

[0043] A memory communicatively connected to the at least one processor; wherein,

[0044] The memory stores instructions that can be executed by the at least one processor to enable the at least one processor to perform the angle-domain dynamic focusing beam reverse-time offset method according to any one of claims 1-8.

[0045] Thirdly, embodiments of this disclosure also provide a non-transitory computer-readable storage medium storing computer instructions for causing a computer to execute the above-described angle-domain dynamic focusing beam reverse-time offset method.

[0046] The beneficial effects of this invention are as follows:

[0047] This invention applies the concept of dynamic focusing beam to Gaussian beam reverse time migration, employing a dynamic focusing beam operator to construct a Green's function, thereby achieving the extension of the forward and reverse wave fields. Finally, the imaging results are obtained through the cross-correlation of these two fields. Simultaneously, by combining the propagation angle information from the dynamic focusing beam calculation, the extraction of common imaging point gathers in the angle domain is directly achieved. This invention can constrain seismic wave energy within an effective range, thereby improving imaging quality and outputting high-quality common imaging point gathers in the angle domain, providing effective support for subsequent migration velocity analysis and reservoir characterization.

[0048] The methods and apparatus of the present invention have other features and advantages that will be apparent from or will be set forth in detail in the accompanying drawings and following detailed description, which together serve to explain the particular principles of the invention. Attached Figure Description

[0049] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same parts.

[0050] Figure 1 A flowchart illustrating the steps of an angle-domain dynamic focusing beam reverse-time offset method according to an embodiment of the present invention is shown.

[0051] Figure 2 A velocity field according to an embodiment of the present invention is shown.

[0052] Figure 3 A single-shot record according to an embodiment of the present invention is shown.

[0053] Figure 4 The Gaussian beam reverse time migration imaging result of an example of the prior art is shown.

[0054] Figure 5 The results of focused beam time-shift imaging based on dynamic parameters according to an embodiment of the present invention are shown.

[0055] Figure 6a The angle gather (Gaussian time-shifted) extracted at CDP1200 in the prior art is shown.

[0056] Figure 6b An angular gather (dynamic focusing beam reverse time shift) extracted at CDP1200 is shown according to an embodiment of the present invention. Detailed Implementation

[0057] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0058] One embodiment of the present invention provides an angle-domain dynamic focusing beam reverse time migration method applied to seismic wavefield imaging. The method includes:

[0059] Modify the complex-valued beam parameters and construct a dynamic focusing beam operator based on the modified complex-valued beam parameters;

[0060] Constructing Green's functions using dynamic focusing bundle operators;

[0061] The Green's function is used to extend the forward wave field and the reverse wave field.

[0062] Cross-correlate the forward wavefield extension and the reverse wavefield extension along the time direction to obtain the single-shot imaging result;

[0063] By combining the single-shot imaging results with the propagation angle calculated during dynamic focusing, the common imaging point gather in the angle domain is extracted.

[0064] In one example, in a two-dimensional ray center coordinate system, the complex-valued beam parameters are:

[0065]

[0066] Where ε is the complex-valued beam parameter, V m For point (s) m Velocity at point 0, S m For point (s) m ,0) to point (s)n The distance l from ,0) m denoted as the width of the ray beam, N is the ratio of the complex-valued dynamic ray tracing parameters P and Q, i is the imaginary unit, Re is the real part, and Im is the imaginary part.

[0067] In one example, the modified complex-valued bundle parameters are:

[0068]

[0069] Where ε is the complex-valued beam parameter, [p1(s),q1(s)] is the plane wave solution of the dynamic ray tracing equation, [p2(s),q2(s)] is the spherical wave solution of the dynamic ray tracing equation, and ω ref The reference frequency is L, and the beam center position is L.

[0070] In one example, the Green's function is:

[0071]

[0072] Where G(x) is the Green's function, θ is the exit angle, and U θ (s,n) is the bundle operator, and Ψ(θ) is the weight coefficient, which has the following form:

[0073]

[0074] Where P and Q are complex-valued dynamic ray tracing parameters, which have the following forms:

[0075]

[0076] Where V(s) is the seismic wave propagation velocity, n is the normal distance from a point near the ray to the ray, ω is the angular frequency, τ is the travel time of the central ray, and the complex-valued beam parameter ε is ε(s) in formula (6).

[0077] In one example, the extension of the positive wave field is achieved using the following relationship:

[0078]

[0079] Where f(ω) is the Fourier transform of the seismic wavelet, G is the dynamic focusing beam eigenfunction Green's function, F is the forward propagation wavefield, and x s Let x be the location of the firing point, x be any point underground, and t be the propagation time.

[0080] In one example, the extension of the reverse wave field is achieved using the following relationship:

[0081]

[0082] Among them, U (m) For tm The seismic wave field received within the time interval ≤ t ≤ T, where B is the reverse extended wave field, t m For any given moment.

[0083] In one example, the single-shot imaging result is obtained using the following relationship:

[0084] I(x m ,x s )=∫B(x m ,t m )F(x m ,t;x s )dt m

[0085] Where I represents the single-shot imaging value.

[0086] In one example, the propagation angle is obtained using the following relationship:

[0087]

[0088] Where Φ is the propagation angle, P x For the slowness level component, P z This represents the slow vertical component.

[0089] This invention applies the concept of dynamic focusing beam to Gaussian beam reverse time migration, employing a dynamic focusing beam operator to construct a Green's function, thereby achieving the extension of the forward and reverse wave fields. Finally, the imaging results are obtained through the cross-correlation of these two fields. Simultaneously, by combining the propagation angle information from the dynamic focusing beam calculation, the extraction of common imaging point gathers in the angle domain is directly achieved. This invention can constrain seismic wave energy within an effective range, thereby improving imaging quality and outputting high-quality common imaging point gathers in the angle domain, providing effective support for subsequent migration velocity analysis and reservoir characterization.

[0090] An embodiment of the present invention also provides an electronic device, the electronic device comprising:

[0091] At least one processor; and,

[0092] A memory that is communicatively connected to at least one processor; wherein,

[0093] The memory stores instructions that can be executed by at least one processor, which enables the at least one processor to perform the above-described angle-domain dynamic focusing beam reverse-time offset method.

[0094] An embodiment of the present invention also provides a non-transitory computer-readable storage medium storing computer instructions for causing a computer to execute the above-described angle-domain dynamic focusing beam reverse-time offset method.

[0095] To facilitate understanding of the solutions and effects of the embodiments of the present invention, three specific application examples are given below. Those skilled in the art should understand that these examples are merely for the purpose of understanding the present invention, and any specific details therein are not intended to limit the present invention in any way.

[0096] Example 1

[0097] Figure 1 A flowchart illustrating the steps of an angle-domain dynamic focusing beam reverse-time offset method according to an embodiment of the present invention is shown.

[0098] like Figure 1 As shown, the angle-domain dynamic focusing beam reverse-time migration method includes: Step 101, modifying the complex-valued beam parameters and constructing a dynamic focusing beam operator based on the modified complex-valued beam parameters; Step 102, constructing a Green's function through the dynamic focusing beam operator; Step 103, realizing the extension of the forward wave field and the extension of the reverse wave field through the Green's function; Step 104, cross-correlating the forward wave field extension and the reverse wave field extension along the time direction to obtain the single-shot imaging result; combining the single-shot imaging result with the propagation angle calculated during dynamic focusing beam calculation to extract the angle-domain common imaging point gather.

[0099] The following is a further explanation of this embodiment.

[0100] Step 1: Construct a dynamic focusing beam operator based on the modified complex-valued beam parameters.

[0101] In a two-dimensional ray center coordinate system, for a ray starting from the initial position (s) m ,0) propagates to point (s) n A ray beam with ,0) has a propagation matrix of the following form:

[0102]

[0103] By applying the reciprocity principle, we can obtain the value from point (s). n From 0 to the initial position (s) m The propagation matrix of (,0) is:

[0104]

[0105] Assume the ray beam is at point (s) n The beam is focused at (0) and the width of the beam is l. m At this point (s) m The dynamic ray tracing parameters at (,0) can be expressed as:

[0106]

[0107] make:

[0108]

[0109] Complex-valued bundle parameters have the following forms:

[0110]

[0111] Where V m For point (s) m Velocity at point 0, S m For point (s) m ,0) to point (s) n The distance between (s, 0) is used. The Gaussian beam determined by the aforementioned complex-valued beam parameters is usually called the focusing beam. Because it only exists at point (s, 0). m 0) Focusing cannot constrain the energy of the entire beam. Therefore, the energy of the entire beam can be constrained within an effective range by adjusting the complex-valued beam parameters:

[0112]

[0113] Where [p1(s),q1(s)] and [p2(s),q2(s)] are the plane wave and spherical wave solutions of the dynamic ray tracing equation, respectively, and ω ref This is the reference frequency.

[0114] Step 2: Construct the Green function using the dynamic focusing bundle operator.

[0115] In the beam deflection method, the Green's function can be characterized by a weighted integral of a series of beam operators:

[0116]

[0117] Where θ is the emission angle, U θ (s,n) is the bundle operator, and Ψ(θ) is the weight coefficient, which has the following form:

[0118]

[0119] Where P and Q are complex-valued dynamic ray tracing parameters, which have the following forms:

[0120]

[0121] In the above equation, the complex-valued beam parameter ε determines the type of beam operator. For dynamic focusing beam offset, the beam parameter in equation (6) is used to construct the Green function.

[0122] Step 3: The forward and reverse wave fields are extended using the Green's function characterized by the focused beam.

[0123] In the dynamic focusing beam reverse time migration algorithm, the expression for the forward propagation wavefield can be obtained from the Green's function characterized by the dynamic focusing beam:

[0124]

[0125] Where f(ω) is the Fourier transform of the seismic wavelet, and G is the dynamic focusing beam eigenfunction Green's function, satisfying the Kirchhoff approximate boundary conditions:

[0126] G| z＝0 =0 (11)

[0127] By using Kirchhoff integration, any point x in the subsurface offset domain can be obtained. m In t m The reverse extension wave field at time:

[0128]

[0129] U (m) For t m The seismic wave field received within the time interval ≤ t ≤ T, Let n be the boundary of the closed space Ω. x Let Ω be the outward normal. The derivative of the outward normal direction, substituted into the dynamic focusing beam characterization of the Green's function, can be further expressed as:

[0130]

[0131] Step 4: Obtain the single-shot imaging value by cross-correlation of the forward and reverse extended wavefields.

[0132] Based on the principle of reflected wave imaging, imaging values ​​can be obtained through the cross-correlation of the forward and reverse extended wave fields:

[0133] I(x m ,x s )=∫B(x m ,t m )F(x m ,t;x s )dt m (14)

[0134] Step 5: Extract the common imaging point gather in the angle domain.

[0135] For any point R near the ray, its travel time can be represented by the travel time of a point X on the ray:

[0136]

[0137] Where n is the distance from point R to point X, it has the following form:

[0138] n = (xx X )t z -(zz X )t x (16)

[0139] Where t x and t z Let x and z be the components of the tangent vector t, respectively. Taking the partial derivatives of both sides of the above equation with respect to x and z, we get:

[0140]

[0141] Substitute equation (16) into the above equation and record:

[0142]

[0143] At this point:

[0144]

[0145] The propagation angle Φ can be expressed as:

[0146]

[0147] After obtaining the propagation angle, the offset angle can be calculated, and then the common imaging point gather in the angle domain can be directly extracted.

[0148] In a specific instance, refer to Figures 2-6b , Figure 2 and Figure 3 This example demonstrates the velocity field and single-shot records required for input. The fault block model has a mesh size of 1500x500 with mesh spacings of 10m and 8m. The seismic record consists of 375 shots, using a full receiver mode with shot and trace intervals of 40m and 10m, respectively. There are 4001 time sampling points with an interval of 1ms. Figure 4 This is the result of existing Gaussian beam reverse time migration imaging technology. Figure 5 This is the result of the focused beam reverse time migration imaging based on the dynamic parameters of this invention. Figure 6a This is an angle gather (Gaussian reverse time migration) extracted at CDP1200 in the existing technology. Figure 6b This is the angle gather (dynamic focusing beam reverse time migration) extracted at CDP1200 in this invention. A comparison of the imaging results and the angle domain common imaging point gather shows that this invention can effectively improve the imaging accuracy of complex targets and obtain high-quality seismic profiles.

[0149] Example 2

[0150] This disclosure also provides an electronic device, which includes:

[0151] At least one processor; and,

[0152] A memory that is communicatively connected to at least one processor; wherein,

[0153] The memory stores instructions that can be executed by at least one processor, which enables the at least one processor to perform the above-described angle-domain dynamic focusing beam reverse-time offset method.

[0154] An electronic device according to an embodiment of the present disclosure includes a memory and a processor.

[0155] This memory is used to store non-transitory computer-readable instructions. Specifically, the memory may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may, for example, include random access memory (RAM) and / or cache memory. The non-volatile memory may, for example, include read-only memory (ROM), hard disk, flash memory, etc.

[0156] The processor may be a central processing unit (CPU) or other form of processing unit with data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions. In one embodiment of this disclosure, the processor is used to execute computer-readable instructions stored in the memory.

[0157] Those skilled in the art will understand that, in order to solve the technical problem of how to achieve a good user experience, this embodiment may also include well-known structures such as communication buses and interfaces, and these well-known structures should also be included within the protection scope of this disclosure.

[0158] This disclosure also provides a non-transitory computer-readable storage medium storing computer instructions for causing a computer to execute the above-described angle-domain dynamic focusing beam reverse-time offset method.

[0159] Example 3

[0160] This disclosure provides a non-transitory computer-readable storage medium storing computer instructions for causing a computer to execute the above-described angle-domain dynamic focusing beam reverse-time offset method.

[0161] A computer-readable storage medium according to embodiments of the present disclosure stores non-transitory computer-readable instructions. When these non-transitory computer-readable instructions are executed by a processor, all or part of the steps of the methods described in the foregoing embodiments of the present disclosure are performed.

[0162] The aforementioned computer-readable storage media include, but are not limited to: optical storage media (e.g., CD-ROM and DVD), magneto-optical storage media (e.g., MO), magnetic storage media (e.g., magnetic tape or portable hard drive), media with built-in rewritable non-volatile memory (e.g., memory card), and media with built-in ROM (e.g., ROM cartridge).

[0163] Those skilled in the art should understand that the above description of the embodiments of the present invention is only intended to illustrate the beneficial effects of the embodiments of the present invention, and is not intended to limit the embodiments of the present invention to any of the examples given.

[0164] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. An angle-domain dynamic focusing beam reverse time migration method applied to seismic wave field imaging, characterized in that, The method comprises: modifying a complex beam parameter, constructing a dynamic focused beam operator based on the modified complex beam parameter; constructing a Green function through the dynamic focused beam operator; realizing the continuation of a forward wave field and the continuation of a reverse wave field through the Green function; correlating the continuation of the forward wave field and the continuation of the reverse wave field in a time direction to obtain single-shot imaging results; combining the single-shot imaging results and a propagation angle during dynamic focused beam calculation to extract an angle domain common imaging point gather; wherein, in a two-dimensional ray center coordinate system, the complex beam parameter is: （1） wherein is the complex beam parameter, is the point velocity, is the point distance, distance, is the width of the ray bundle, N is the ratio of the complex dynamic ray tracing parameters P and Q, i is the imaginary unit, Re is the real part, and Im is the imaginary part; wherein, the modified complex beam parameter is: （2） wherein, is the complex beam parameter, is the plane wave solution of the kinetic ray tracing equation, is the spherical wave solution of the kinetic ray tracing equation, is the reference frequency, L is the beam center position.

2. The angle-domain dynamic focusing beam reverse time migration method according to claim 1, characterized in that, the Green function is: （3） wherein G is the Green function, θ is the exit angle, B is the beam operator, w is the weight coefficient, and has the form: （4） wherein P and Q are complex value dynamic ray tracing parameters, and have the following form: （5） where is the seismic wave propagation velocity, is the normal distance from the ray to the point, is the circular frequency, is the central ray travel time, complex beam parameter is the (s).

3. The angle-domain dynamic focusing beam reverse time migration method according to claim 1, wherein, the continuation of the forward wave field is realized by using the following relationship, wherein is the Fourier transform of the seismic wavelet, is the dynamic focused-beamlet Green's function, F is the forward propagating wavefield, is the shot position, is any point in the subsurface, is the traveltime.

4. The angle-domain dynamic focusing beam reverse time migration method according to claim 3, characterized in that, the continuation of the reverse wave field is realized by using the following relationship, wherein is the seismic wavefield received during a time interval, B is the reverse-time wavefield, is any time.

5. The angle-domain dynamic focusing beam reverse time migration method according to claim 3, characterized in that, the single-shot imaging results are obtained by using the following relationship, wherein I is a single-shot imaging value.

6. The angle-domain dynamic focusing beam reverse time migration method according to claim 5, characterized in that, the propagation angle is obtained by using the following relationship, wherein is the propagation angle, P x is the slowness horizontal component, P z is the slowness vertical component.

7. An electronic device, comprising: The electronic device comprises: at least one processor; and a memory connected with the at least one processor in communication; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the angle domain dynamic focused beam reverse-time migration method of any one of claims 1-6.

8. A non-transitory computer-readable storage medium, comprising: The non-transitory computer readable storage medium stores computer instructions for causing a computer to perform the angle domain dynamic focused beam reverse-time migration method of any one of claims 1-6.

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