A method for seismic full wavefield simulation based on optimized phase shift

Abstract

The application discloses a seismic full wave field simulation method based on optimized phase shift, which comprises the following steps: constructing a seismic wave source equation, constructing a wave field function for simulating seismic wave propagation according to the seismic wave source equation, setting a phase shift step number, constructing a phase shift wave equation according to the wave field function, constructing an upgoing wave field and a downgoing wave field of one-time propagation according to the phase shift wave equation for each depth interface, constructing an upgoing wave field and a downgoing wave field of two-time propagation according to the upgoing wave field and the downgoing wave field of one-time propagation, and superimposing the upgoing wave field and the downgoing wave field of one-time propagation and the upgoing wave field and the downgoing wave field of two-time propagation to obtain a full wave field simulation result. The method realizes simulation of one-time reflection and multiple reflections in seismic waves, and the simulated wave field is more accurate.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of geophysical exploration technology, and in particular to a seismic full-wavefield simulation method based on optimized phase shift. Background Technology

[0002] When seismic waves propagate from high-velocity strata or strong-impedance interfaces, they undergo multiple reflections between these interfaces. Multiples refer to seismic waves reflected from the subsurface medium that, upon reaching a strong-impedance surface, undergo at least one downward reflection at the surface and then return underground after a certain propagation path. Multiples typically have short periods and high orders, making them difficult to distinguish from primary waves in terms of energy. Therefore, in seismic data processing, it is necessary to simulate not only the primary reflection wavefield but also the multiple wavefield; otherwise, the final imaging results will be affected. Existing techniques, such as the split-step phase-shift method, can simulate seismic waves to some extent. By dividing the subsurface medium vertically into several approximately invariant thin layers, a one-way wave propagation operator is obtained. During propagation, the background velocity of the subsurface medium and inter-layer velocity perturbations are combined to simulate the primary reflection wave. However, this method can only simulate the primary reflection wavefield in three-dimensional space and cannot simulate the entire seismic wavefield. Therefore, this method cannot completely simulate the entire seismic wavefield. Summary of the Invention

[0003] To address the aforementioned technical problems, at least one embodiment of the present invention provides a seismic full-wavefield simulation method based on optimized phase shift, thereby improving the accuracy and precision of seismic full-wavefield simulation.

[0004] In some optional embodiments, the method includes the following steps:

[0005] Construct the source equation for seismic waves, and based on the source equation, construct the wavefield function for simulating seismic wave propagation;

[0006] Set the phase shift step number and construct the phase shift wave equation based on the wave field function;

[0007] For each depth interface, a first-propagation up-row field and a second-propagation up-row field are constructed based on the phase-shift wave equation.

[0008] The up-row and down-row fields from the first propagation are superimposed with the up-row and down-row fields from the second propagation to obtain the full-field simulation results.

[0009] In some optional embodiments, constructing the wavefield function for simulating seismic wave propagation based on the source equation includes:

[0010] Construct a depth-dependent wavefield function based on the aforementioned source equation;

[0011] The depth-dependent wavefield function is rewritten as a wavefield function dependent on amplitude and phase.

[0012] In some optional embodiments, the source equation is expressed as:

[0013]

[0014] Where T is the propagation period, f is the peak frequency of the earthquake source, and A is the amplitude of the earthquake source. Let be the direction of propagation of the earthquake source in space. When the source equation propagates upwards, it is: When propagating downwards

[0015] In some optional embodiments, the expression for the depth-related wavefield function is:

[0016]

[0017] Where z is the depth, P A (f) represents the wave field. This is the Green's function.

[0018] In some optional embodiments, the expression for the wave field function related to amplitude and phase is:

[0019]

[0020] Where j is the imaginary part of the seismic signal, k is the wave number, r is the propagation path length of the seismic wave, S is the surface element for calculating the integral, and φ is the phase of the seismic signal.

[0021] In some optional embodiments, the expression for the phase-shift wave equation is:

[0022]

[0023] In some optional embodiments, the expression for the first propagation of the up-traveling wave field is:

[0024]

[0025] The expression for the downlink wave field of the first propagation is:

[0026]

[0027] In some optional embodiments, the expression for the secondary propagation up-going wave field is:

[0028]

[0029] The expression for the downlink wave field of the secondary propagation is:

[0030]

[0031] At least one embodiment of the present invention also provides a seismic full-wavefield simulation device based on optimized phase shift, characterized in that it comprises:

[0032] The wavefield function construction module is used to construct the source equation of seismic waves and construct the wavefield function for simulating the propagation of seismic waves based on the source equation.

[0033] The wave equation construction module is used to set the phase shift step number and construct the phase-shifted wave equation based on the wave field function;

[0034] The secondary wave field construction module is used to construct the first-propagation up-row and down-row wave fields for each depth interface according to the phase shift wave equation, and to construct the second-propagation up-row and down-row wave fields according to the first-propagation up-row and down-row wave fields.

[0035] The full-wave field simulation module is used to superimpose the up-row and down-row fields of the first propagation with the up-row and down-row fields of the second propagation to obtain the full-wave field simulation results.

[0036] At least one embodiment of the present invention also provides an electronic device, characterized in that it comprises:

[0037] At least one processor; and,

[0038] A memory communicatively connected to the at least one processor; wherein,

[0039] The memory stores instructions that can be executed by the at least one processor to enable the at least one processor to perform the seismic full-wavefield simulation method based on optimized phase shift as described above.

[0040] At least one embodiment of the present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the seismic full-wavefield simulation method based on optimized phase shift as described above.

[0041] At least one embodiment of the present invention also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the seismic full-wavefield simulation method based on optimized phase shift as described above.

[0042] Compared with existing technologies, embodiments of the present invention provide a seismic full-wavefield simulation method based on optimized phase shift. This method constructs a source equation based on the phenomenon of seismic wave propagation in complex media, establishes a phase shift propagation operator, constructs a wavefield, sets the phase shift step number, and then generates an up-propagating and down-propagating wavefield for each depth. A secondary propagating wavefield is then generated based on the primary propagating wavefield. Finally, the primary and secondary propagating wavefields are superimposed to obtain the final seismic full-wavefield. The proposed method for simulating the seismic full-wavefield achieves simulation of both primary and multiple reflections of seismic waves, resulting in a more accurate simulated wavefield. Attached Figure Description

[0043] One or more embodiments are illustrated by way of example with reference to the accompanying drawings, and these illustrative descriptions do not constitute a limitation on the embodiments.

[0044] Figure 1 This is a flowchart of the steps of the seismic full-wavefield simulation method based on optimized phase shift used in Embodiment 1 of the present invention;

[0045] Figure 2 This is a schematic diagram of a velocity model for simulation provided in Embodiment 2 of the present invention;

[0046] Figure 3 This is a schematic diagram of wavefield data simulating a single propagation provided in Embodiment 2 of the present invention;

[0047] Figure 4 This is a schematic diagram of simulated full-wave field data provided in Embodiment 2 of the present invention. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the various embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details are presented in the embodiments of the present invention to facilitate a better understanding of the invention. However, the technical solutions claimed in the present invention can be implemented even without these technical details and various variations and modifications based on the following embodiments. The division of the following embodiments is for ease of description and should not constitute any limitation on the specific implementation of the present invention. The various embodiments can be combined with and referenced by each other without contradiction.

[0049] As mentioned above, in order to solve the technical problem, this invention proposes a seismic full-wavefield simulation method based on optimized phase shift.

[0050] The implementation details of the above method are described in detail below through examples. The following content is only for the convenience of understanding the implementation details and is not necessary for implementing this solution.

[0051] Example 1:

[0052] like Figure 1 As shown in the figure, this embodiment provides a seismic full-wavefield simulation method based on optimized phase shift, which mainly includes the following steps.

[0053] Step 1: First, construct the source equation for the seismic waves.

[0054] The expression for the source equation is:

[0055]

[0056] Where T is the propagation period, f is the peak frequency of the earthquake source, and A is the amplitude of the earthquake source. Let be the direction of propagation of the earthquake source in space. When the source equation propagates upwards, it is: When propagating downwards

[0057] Step 2: At a certain imaging point at depth z, construct a wavefield function to simulate the propagation process of seismic waves. The expression for the wavefield function is:

[0058]

[0059] Where z is the depth, P A (f) represents the wave field. This is the Green's function.

[0060] In an isotropic medium, the above wave field function can be rewritten as an expression related to amplitude and phase:

[0061]

[0062] Where j is the imaginary part of the seismic signal, k is the wave number, r is the propagation path length of the seismic wave, S is the surface element for calculating the integral, and φ is the phase of the seismic signal.

[0063] Step 3: Set the number of phase shift steps N, and construct the N-step phase shift wave equation. Typically, N = 1, 2, 3, or 4.

[0064] The expression for the phase-shift wave equation is:

[0065]

[0066] Step 4: Construct the up-going and down-going waves of the source wave field (i.e., the up-going and down-going wave fields of the first propagation), where:

[0067] The expression for an upward wave is:

[0068]

[0069] The expression for the downward wave is:

[0070]

[0071] Step 5: Using the upwave and downwave of the source wave field as input data, construct the upwave field and downwave field of the secondary propagation.

[0072] in:

[0073] The expression for the ascending wave field is:

[0074]

[0075] The expression for the downlink wave field is:

[0076]

[0077] Step Six: Superimpose the above four wavefield results to obtain the full wavefield simulation result.

[0078] The full wave field expression is:

[0079]

[0080] Where P represents the full wave field. For a single propagation of the upward wave field, For a single propagation of the downlink wave field, For the secondary propagation of the uplink wave field, This is the downlink wave field for secondary propagation.

[0081] Example 2

[0082] The technical solution of the present invention and its beneficial effects will be further illustrated below with a specific example.

[0083] Figure 2 A schematic diagram of the velocity model is shown. The velocity model is used to simulate the velocity of the actual ocean, where the first layer is the water layer with a velocity of 1500 m / s, and there is a high-velocity anomalous geological body below.

[0084] Figure 3 The results of generating a reflected wave using this method are shown. The wavefield results show that the calculated reflection results are consistent with the theoretical values, and the amplitude values ​​are correct.

[0085] Figure 4 The results of the full-wavefield simulation are shown. The simulation results reveal that the simulation not only contains effective information about the primary wave but also information about multiple reflections, and the temporal and spatial locations of these multiple reflections are consistent with theoretical values.

[0086] This embodiment illustrates that when seismic waves propagate from high-velocity strata or strong impedance interfaces, the wave propagation exhibits multiple reflections between the interfaces. This invention proposes a novel method specifically for simulating the full seismic wavefield. This method constructs a source equation, establishes a phase-shift propagation operator, builds a wavefield, sets the phase-shift step number, and then generates primary propagation up-wavefields and down-wavefields at each depth interface. Based on these primary propagation up-wavefields and down-wavefields, secondary propagation up-wavefields and down-wavefields are calculated. Finally, the primary and secondary propagation up-wavefields and down-wavefields are superimposed to obtain the final full seismic wavefield. Compared to traditional methods, this proposed method for simulating the full seismic wavefield achieves simulation of both primary and multiple reflections of seismic waves, resulting in a more accurate simulated wavefield.

[0087] Example 3

[0088] Another embodiment of the present invention relates to a seismic full-wavefield simulation device based on optimized phase shift, comprising:

[0089] The wavefield function construction module is used to construct the source equation of seismic waves and construct the wavefield function for simulating the propagation of seismic waves based on the source equation.

[0090] The wave equation construction module is used to set the phase shift step number and construct the phase-shifted wave equation based on the wave field function;

[0091] The secondary wave field construction module is used to construct the first-propagation up-row and down-row wave fields for each depth interface according to the phase shift wave equation, and to construct the second-propagation up-row and down-row wave fields according to the first-propagation up-row and down-row wave fields.

[0092] The full-wave field simulation module is used to superimpose the up-row and down-row fields of the first propagation with the up-row and down-row fields of the second propagation to obtain the full-wave field simulation results.

[0093] Example 4:

[0094] Another embodiment of the present invention relates to an electronic device, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the seismic full-wavefield simulation method based on optimized phase shift in the above embodiments.

[0095] The memory and processor are connected via a bus, which can include any number of interconnecting buses and bridges, connecting various circuits of one or more processors and memories. The bus can also connect various other circuits, such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and will not be described further herein. The bus interface provides an interface between the bus and the transceiver. The transceiver can be a single element or multiple elements, such as multiple receivers and transmitters, providing a unit for communicating with various other devices over a transmission medium. Data processed by the processor is transmitted over the wireless medium via an antenna, which further receives data and transmits it to the processor.

[0096] The processor manages the bus and general processing, and also provides various functions, including timing, peripheral interfaces, voltage regulation, power management, and other control functions. Memory is used to store data used by the processor during operation.

[0097] Example 5:

[0098] Another embodiment of the present invention relates to a computer-readable storage medium storing a computer program. When executed by a processor, the computer program implements the seismic full-wavefield simulation method based on optimized phase shift described in the above embodiments.

[0099] That is, those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. This program is stored in a storage medium and includes several instructions to cause a device (which may be a microcontroller, chip, etc.) or processor to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0100] Example 6

[0101] Another embodiment of the present invention relates to a computer program product, including a computer program that, when executed by a processor, implements the steps of the optimized phase shift-based full-wavefield seismic simulation method of the above embodiments.

[0102] Those skilled in the art will understand that the above embodiments are specific embodiments for implementing the present invention, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of the present invention.

Claims

1. A seismic full-wavefield simulation method based on optimized phase shift, characterized in that, include: Construct the source equation for seismic waves, and based on the source equation, construct the wavefield function for simulating seismic wave propagation; Set the phase shift step number and construct the phase shift wave equation based on the wave field function; For each depth interface, a first-propagation up-row field and a second-propagation up-row field are constructed based on the phase-shift wave equation. The up-row and down-row fields from the first propagation are superimposed with the up-row and down-row fields from the second propagation to obtain the full-field simulation results.

2. The seismic full-wavefield simulation method based on optimized phase shift according to claim 1, characterized in that, The construction of the wavefield function for simulating seismic wave propagation based on the source equation includes: Construct a depth-dependent wavefield function based on the aforementioned source equation; The depth-dependent wavefield function is rewritten as a wavefield function dependent on amplitude and phase.

3. The seismic full-wavefield simulation method based on optimized phase shift according to claim 2, characterized in that, The expression for the source equation is: Where T is the propagation period, f is the peak frequency of the earthquake source, and A is the amplitude of the earthquake source. Let be the direction of propagation of the earthquake source in space. When the source equation propagates upwards, it is: When propagating downwards 4. The seismic full-wavefield simulation method based on optimized phase shift according to claim 3, characterized in that, The expression for the depth-related wavefield function is: Where z is the depth, P A (f) represents the wave field. It is the Green's function; The expression for the wave field function related to amplitude and phase is: Where j is the imaginary part of the seismic signal, k is the wave number, r is the propagation path length of the seismic wave, S is the surface element for calculating the integral, and φ is the phase of the seismic signal.

5. The seismic full-wavefield simulation method based on optimized phase shift according to claim 4, characterized in that, The expression for the phase-shift wave equation is:

6. The seismic full-wavefield simulation method based on optimized phase shift according to claim 1, characterized in that, The expression for the upward wave field of the first propagation is: The expression for the downlink wave field of the first propagation is:

7. The seismic full-wavefield simulation method based on optimized phase shift according to claim 1, characterized in that, The expression for the upward wave field of the secondary propagation is: The expression for the downlink wave field of the secondary propagation is:

8. A seismic full-wavefield simulation device based on optimized phase shift, characterized in that, include: The wavefield function construction module is used to construct the source equation of seismic waves and construct the wavefield function for simulating the propagation of seismic waves based on the source equation. The wave equation construction module is used to set the phase shift step number and construct the phase-shifted wave equation based on the wave field function; The secondary wave field construction module is used to construct the first-propagation up-row and down-row wave fields for each depth interface according to the phase shift wave equation, and to construct the second-propagation up-row and down-row wave fields according to the first-propagation up-row and down-row wave fields. The full-wave field simulation module is used to superimpose the up-row and down-row fields of the first propagation with the up-row and down-row fields of the second propagation to obtain the full-wave field simulation results.

9. An electronic device, characterized in that, include: At least one processor; as well as, A memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor to enable the at least one processor to perform the seismic full-wavefield simulation method based on optimized phase shift as described in any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the seismic full-wavefield simulation method based on optimized phase shift as described in any one of claims 1 to 7.

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