A seismic wave forward modeling method, device, equipment and storage medium

Abstract

The application discloses a seismic wave forward simulation method, device and equipment and a storage medium. The method comprises the following steps: constructing a marine geology model, setting a seismic wave field to be excited from a set depth of a shot point position, generating an upgoing wave and a downgoing wave, loading a last round of a geophone wave field as a secondary virtual field source at a position above the shot point during propagation of the downgoing wave, and simultaneously propagating a real field source and the secondary virtual field source at a position below the shot point; during propagation of the upgoing wave, only the secondary virtual source propagates below the shot point, and the upgoing wave above the shot point contains a real shot point signal and a secondary virtual field source signal; after iterative calculation, multiple wave and ghost wave information of marine seismic data are simulated and separated, and accurate seismic wave data are obtained, so that the marine seismic data can be used for marine seismic analysis, and the accuracy of marine seismic situation analysis is improved.

Description

Technical Field

[0001] This invention relates to the field of earthquake detection technology, specifically to a method, apparatus, equipment, and storage medium for seismic wave forward modeling. Background Technology

[0002] During the acquisition of marine seismic data, both the shot point and the receiving tow cable are located below the water surface. After the shot point is excited, it can be divided into up and down waves. The up wave is reflected by the free sea surface to form a ghost wave at the shot point. The primary reflection wave from the subsurface reflection interface and the primary reflection wave are reflected by the free sea surface to reach the receiver point, forming a receiver ghost wave. The ghost wave and the primary reflection wave interfere with each other, affecting the waveform characteristics of the primary reflection wave, which brings difficulties to the interpretation and inversion of seismic data. Summary of the Invention

[0003] Based on this, the present invention provides a seismic wave forward modeling method, apparatus, equipment and storage medium to solve the shortcomings of the prior art in accurately analyzing marine earthquakes.

[0004] To achieve the above objectives, embodiments of the present invention provide a seismic wave forward modeling method, comprising:

[0005] Construct a marine geological model; wherein, in the marine geological model, the interface between the water surface and the underwater surface is divided into multiple layers from top to bottom, and shot points are set at a set depth to generate seismic wave fields;

[0006] Set the seismic wave field to be excited starting from the shot point at a set depth;

[0007] Obtain the downpropagation operators and downpropagation two-way wave secondary virtual source terms for each layer above the first type layer to calculate the downpropagation wave field from the water surface to the first type layer; where the first type layer is any layer at or above the shot point layer.

[0008] The down propagation operators of each layer above the second type of layer, the down two-way wave secondary virtual source terms of each layer above the second type of layer, and the down real source propagation terms from the layer where the shot point is located to the second type of layer are obtained to calculate the down wave field propagating from the water surface to the second type of layer; wherein, the second type of layer is any layer below the layer where the shot point is located.

[0009] The upward real source propagation term from the layer where the shot point is located to the first type layer, the upward propagation operator of each layer below the first type layer, and the upward two-way wave secondary virtual source term from the water surface to each layer below the first type layer are obtained in order to calculate the upward wave field that propagates downward from the water surface to the underwater interface and is reflected to the first type layer.

[0010] Obtain the up-propagation operators of each layer below the second type of layer, and the secondary virtual source term of the up-propagation two-way wave from the water surface to each layer below the second type of layer, so as to calculate the up-propagation wave field that propagates downward from the water surface to the underwater interface and then reflects upward to the second type of layer;

[0011] Seismic wave data are generated based on the downflow wave field propagating from the water surface to the first type layer, the downflow wave field propagating from the water surface to the second type layer, the upflow wave field propagating downwards from the water surface to the underwater interface and then reflecting back to the first type layer, and the upflow wave field propagating downwards from the water surface to the underwater interface and then reflecting back upwards to the second type layer, for use in marine seismic analysis.

[0012] To achieve the above objectives, embodiments of the present invention also provide a seismic wave forward modeling apparatus, comprising:

[0013] The model building module is used to build a marine geological model; wherein, in the marine geological model, the water surface and underwater interface are divided into multiple layers from top to bottom, and shot points are set at a set depth to excite the seismic wave field;

[0014] The wave field excitation module is used to set the seismic wave field to be excited from the shot point at a set depth;

[0015] The first down-going wave field calculation module is used to obtain the down-going propagation operators and down-going two-way wave secondary virtual source terms of each layer above the first type layer, so as to calculate the down-going wave field propagating from the water surface to the first type layer; wherein, the first type layer is any layer above the layer where the shot point is located.

[0016] The second downlink wave field calculation module is used to obtain the downlink propagation operators of each layer above the second type layer, the downlink two-way wave secondary virtual source terms of each layer above the second type layer, and the downlink real source propagation terms from the layer where the shot point is located to the second type layer, so as to calculate the downlink wave field propagating from the water surface to the second type layer; wherein, the second type layer is any layer below the layer where the shot point is located.

[0017] The first upgoing wave field calculation module is used to obtain the upgoing real source propagation term from the layer where the shot point is located to the first type layer, the upgoing propagation operator of each layer below the first type layer, and the upgoing two-way wave secondary virtual source term from the water surface to each layer below the first type layer, so as to calculate the upgoing wave field that propagates downward from the water surface to the underwater interface and is reflected to the first type layer.

[0018] The second upgoing wave field calculation module is used to obtain the upgoing propagation operators of each layer below the second type of layer and the secondary virtual source term of the upgoing two-way wave from the water surface to each layer below the second type of layer, so as to calculate the upgoing wave field that propagates downward from the water surface to the underwater interface and then reflects upward to the second type of layer.

[0019] The analysis module is used to generate seismic wave data for marine earthquake analysis based on the downflow wave field propagating from the water surface to the first type layer, the downflow wave field propagating from the water surface to the second type layer, the upflow wave field propagating downward from the water surface to the underwater interface and then reflecting back to the first type layer, and the upflow wave field propagating downward from the water surface to the underwater interface and then reflecting back upward to the second type layer.

[0020] To achieve the above objectives, embodiments of the present invention also provide a seismic wave forward modeling device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the seismic wave forward modeling method as described in any of the above embodiments.

[0021] To achieve the above objectives, embodiments of the present invention also provide a computer-readable storage medium, the computer-readable storage medium including a stored computer program, wherein, when the computer program is executed, it controls the device where the computer-readable storage medium is located to perform the seismic wave forward modeling method as described in any of the above embodiments.

[0022] Compared with existing technologies, the seismic wave forward modeling method, apparatus, equipment, and storage medium disclosed in this invention first constructs a marine geological model. In this model, the interface between the water surface and the underwater surface is divided into multiple layers from top to bottom. Shot points are set at a predetermined depth to generate the seismic wave field. Then, the seismic wave field is generated starting from the shot point at the predetermined depth. Next, the downpropagation operators and downpropagation two-way wave secondary virtual source terms for each layer above the first type of layer are obtained to calculate the downpropagation wave field propagating from the water surface to the first type of layer. The first type of layer is any layer above the shot point. Then, the downpropagation operators, downpropagation two-way wave secondary virtual source terms, and downpropagation real source propagation terms from the shot point to the second type of layer are obtained to calculate the downpropagation wave field propagating from the water surface to the second type of layer. The second type of layer is the shot point. The system obtains the following information: First, it acquires the true upward source propagation term from the layer containing the shot point to the first type of layer, the upward propagation operator from each layer below the first type of layer, and the secondary virtual source term of the upward two-way wave from the water surface to each layer below the first type of layer. This is used to calculate the upward wave field propagating downwards from the water surface to the underwater interface and then reflecting back to the first type of layer. Second, it acquires the upward propagation operator from each layer below the second type of layer and the secondary virtual source term of the upward two-way wave from the water surface to each layer below the second type of layer. This is used to calculate the upward wave field propagating downwards from the water surface to the underwater interface and then reflecting back to the second type of layer. Finally, based on the downward wave field propagating from the water surface to the first type of layer, the downward wave field propagating from the water surface to the second type of layer, the upward wave field propagating downwards from the water surface to the underwater interface and then reflecting back to the first type of layer, and the upward wave field propagating downwards from the water surface to the underwater interface and then reflecting back to the second type of layer, seismic wave data is generated for use in marine earthquake analysis, improving the accuracy of marine earthquake situation analysis. Attached Figure Description

[0023] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic flowchart of a seismic wave forward modeling method provided in an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of a model hierarchy partitioning provided in an embodiment of the present invention;

[0026] Figure 3 This is a forward modeling simulation recording diagram and a wavefield separation schematic diagram provided in an embodiment of the present invention;

[0027] Figure 4 This is a schematic diagram of the structure of a seismic wave forward modeling device provided in an embodiment of the present invention;

[0028] Figure 5 This is a schematic diagram of the structure of a seismic wave forward modeling simulation device provided in an embodiment of the present invention. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] See Figure 1 , Figure 1 This is a flowchart illustrating a seismic wave forward modeling method provided in an embodiment of the present invention. Specifically, the seismic wave forward modeling method includes steps S11 to S17:

[0031] S11. Construct a marine geological model; wherein, in the marine geological model, the interface between the water surface and the underwater surface is divided into multiple layers from top to bottom, and shot points are set at a set depth to excite the seismic wave field.

[0032] Specifically, such as Figure 2 As shown, assuming the underwater interface is the seabed, Figure 2 The water surface and underwater interface are divided into layers, and the specific number of layers is not limited. Figure 2 As shown, the shot point is set between the water surface and the underwater interface to generate seismic wave fields.

[0033] S12. Set the seismic wave field to be excited from the shot point at the set depth.

[0034] Specifically, after the seismic wave field is generated at the shot point, the seismic waves will propagate as ascending and descending waves. The ascending wave is reflected by the water surface to form a ghost wave at the shot point; the descending wave propagates downward to the water surface and is reflected to the receiver point to form a primary reflection wave; the primary reflection wave is reflected by the water surface and reaches the receiver point to form a receiver ghost wave. The ghost wave will follow the primary reflection wave and affect the waveform characteristics of the primary reflection wave.

[0035] S13. Obtain the downpropagation operators and downpropagation two-way wave secondary virtual source terms for each layer above the first type layer to calculate the downpropagation wave field from the water surface to the first type layer; where the first type layer is any layer above the shot point.

[0036] S14. Obtain the down propagation operators of each layer above the second type layer, the down two-way wave secondary virtual source terms of each layer above the second type layer, and the down real source propagation terms from the layer where the shot point is located to the second type layer, so as to calculate the down wave field propagating from the water surface to the second type layer; wherein, the second type layer is any layer below the layer where the shot point is located.

[0037] S15. Obtain the uplink real source propagation term from the layer where the shot point is located to the first type layer, the uplink propagation operator of each layer below the first type layer, and the uplink two-way wave secondary virtual source term from the water surface to each layer below the first type layer, so as to calculate the uplink wave field that propagates downward from the water surface to the underwater interface and is reflected to the first type layer.

[0038] S16. Obtain the up-propagation operators of each layer below the second type of layer and the secondary virtual source term of the up-propagation two-way wave from the water surface to each layer below the second type of layer, so as to calculate the up-propagation wave field that propagates downward from the water surface to the underwater interface and then reflects upward to the second type of layer.

[0039] S17. Based on the downflow wave field propagating from the water surface to the first type layer, the downflow wave field propagating from the water surface to the second type layer, the upflow wave field propagating downwards from the water surface to the underwater interface and then reflected back to the first type layer, and the upflow wave field propagating downwards from the water surface to the underwater interface and then reflected back upwards to the second type layer, generate seismic wave data for use in marine earthquake analysis.

[0040] Specifically, using a closed-loop iterative approach, the seismic wave field is set to be excited from the shot point at a predetermined depth, generating up-going and down-going waves. During the down-going wave propagation, the receiver wave field from the previous round is loaded at the position above the shot point (i.e., the first type of layer) as a secondary virtual source, while the real source (i.e., the down-going real source propagation term of the second type of layer) and the secondary virtual source propagate simultaneously at the position below the shot point. During the up-going wave propagation, only the secondary virtual source propagates below the shot point, while the up-going wave above the shot point contains both the real shot point signal and the secondary virtual source signal. Through iterative calculation, the multiple wave and ghost wave information of marine seismic data can be simulated and separated to obtain accurate seismic wave data for marine seismic analysis, thereby improving the accuracy of marine seismic situation analysis.

[0041] In one implementation, the downflow wave field propagating from the water surface to the first type layer is calculated in the following manner:

[0042] The down propagation operators of each layer above the first type of layer are multiplied by the corresponding down two-way wave second virtual source term and then added together to obtain the down wave field propagating from the water surface to the first type of layer.

[0043] Specifically, the propagation of seismic waves is analyzed in two categories: above and below the shot point layer. Above the shot point layer, the wave field is further divided into ascending and descending wave fields; similarly, below the shot point layer, the wave field is also divided into ascending and descending wave fields. For example, the first type of layer refers to any layer above the shot point layer (including the shot point layer itself). The descending wave field propagating from the water surface to the first type of layer is calculated as follows:

[0044] The downpropagation operator of the first target class layer, which is obtained in advance, is multiplied by the downpropagation two-way wave second virtual source term of the first target class layer to obtain the downpropagation virtual propagation term of the first target class layer; wherein, the first target class layer is any layer between the water surface and the first class layer (including the water surface, but excluding the first class layer).

[0045] The downlink virtual propagation terms of all first target class layers in the first type layer are summed to obtain the downlink wave field propagating from the water surface to the first type layer.

[0046] In one implementation, the downlink wave field propagating from the water surface to the second type layer is calculated in the following manner:

[0047] The down propagation operators of each layer above the second type of layer are multiplied by the down two-way wave second virtual source term of the corresponding layer and then added together to obtain the first virtual value of each layer above the second type of layer. All the first virtual values ​​are added to the down real source propagation term from the layer where the shot point is located to the second type of layer to obtain the down wave field propagating from the water surface to the second type of layer.

[0048] Specifically, the propagation of seismic waves is analyzed in two categories: above and below the shot point layer. Above the shot point layer, the wave field is further divided into ascending and descending wave fields; similarly, below the shot point layer, the wave field is also divided into ascending and descending wave fields. For example, the second type of layer refers to any layer below the shot point layer (excluding the shot point layer itself). The descending wave field propagating from the water surface to the second type of layer is calculated as follows:

[0049] The downpropagation operator of the second target class layer, which is obtained in advance, is multiplied by the downpropagation two-way wave second virtual source term of the second target class layer to obtain the downpropagation virtual propagation term of the second target class layer; wherein, the second target class layer is any layer between the water surface and the second class layer (including the water surface, but excluding the second class layer);

[0050] Add the downlink virtual propagation terms of all second target class layers in the second type layer, and then add the downlink real source propagation terms of the second type layer to obtain the downlink wave field propagating from the water surface to the second type layer.

[0051] In one embodiment, the ascending wave field that propagates downwards to the underwater interface and is reflected to the first type layer is calculated as follows:

[0052] The uplink propagation operator of each layer below the first type of layer is multiplied by the uplink two-way wave second virtual source term of the corresponding layer to obtain the second virtual value of each layer below the first type of layer. All the second virtual values ​​are added to the uplink real source propagation term from the layer where the shot point is located to the first type of layer to obtain the uplink wave field that propagates downward from the water surface to the underwater interface and is reflected to the first type of layer.

[0053] Specifically, the propagation of seismic waves is analyzed in two categories: above and below the shot point layer. Above the shot point layer, the wave field is further divided into ascending and descending wave fields; similarly, below the shot point layer, the wave field is also divided into ascending and descending wave fields. For example, the first type of layer refers to any layer above the shot point layer (including the shot point layer itself). The ascending wave field, after propagating downwards from the water surface to the underwater interface and reflecting back to the first type of layer, is calculated as follows:

[0054] Multiply the pre-acquired uplink propagation operator of the third target class layer by the uplink two-way wave second virtual source term of the third target class layer to obtain the uplink virtual propagation term of the third target class layer; where the third target class layer refers to any layer between the first class layer and the underwater interface (excluding the first class layer, including the underwater interface).

[0055] Add up the uplink virtual propagation terms of all third-target-class layers in the first-class layer, and add the real source propagation terms from the layer where the shot point is located to the first-class layer to obtain the uplink wave field that propagates downward from the water surface to the underwater interface and is reflected back to the first-class layer.

[0056] In one implementation, the upward wave field that is reflected after the water surface propagates downward to the underwater interface and then propagates upward to the second type layer is calculated in the following way:

[0057] The upward propagation operators of each layer below the second type of layer are multiplied by the corresponding upward two-way wave second virtual source term and then added together to obtain the upward wave field that propagates downward from the water surface to the underwater interface and then reflects upward to the second type of layer.

[0058] Specifically, the propagation of seismic waves is analyzed in two categories: above and below the shot point layer. Above the shot point layer, the wave field is further divided into ascending and descending wave fields; similarly, below the shot point layer, the wave field is also divided into ascending and descending wave fields. The second type of layer refers to any layer below the shot point layer (excluding the shot point layer itself). The ascending wave field, after propagating downwards from the water surface to the underwater interface and then reflecting upwards to the second type of layer, is calculated. The specific calculation method is as follows:

[0059] Multiply the pre-acquired uplink propagation operator of the fourth target class layer by the uplink two-way wave second virtual source term of the fourth target class layer (assuming there is no source term from below the model) to obtain the uplink virtual propagation term of the fourth target class layer; where the fourth target class layer is any layer between the second class layer and the underwater interface (excluding the second class layer, including the underwater interface).

[0060] Add up all the uplink virtual propagation terms of the fourth target class layer in the second class layer to obtain the uplink wave field that propagates downwards to the underwater interface and then reflects upwards to the second class layer.

[0061] In one implementation, the down-travel two-way wave secondary virtual source term is calculated in the following manner:

[0062] The following parameters are obtained: the lower surface reflection coefficient of the layer to which the down-two-way wave secondary virtual source term belongs; the upward wave field that propagates from the water surface downward to the underwater interface and then reflects upward to the layer to which the down-two-way wave secondary virtual source term belongs; the down-transmission factor of the layer to which the down-two-way wave secondary virtual source term belongs; and the down-wave field that propagates from the water surface to the layer to which the down-two-way wave secondary virtual source term belongs.

[0063] Multiply the reflection coefficient of the lower surface of the layer to which the down-two-way wave secondary virtual source term belongs by the reflection coefficient of the water surface after it propagates downward to the underwater interface and then reflects upward to the up-propagating wave field of the layer to which the down-two-way wave secondary virtual source term belongs, to obtain the first virtual reflection value.

[0064] Multiply the down transmission factor of the layer to which the down two-way wave secondary virtual source term belongs by the down wave field propagating from the water surface to the layer to which the down two-way wave secondary virtual source term belongs to obtain the first virtual transmission value;

[0065] The first virtual reflection value and the first virtual transmission value are added together to obtain the second virtual source term of the down-pass two-way wave.

[0066] In one implementation, the upward two-way wave secondary virtual source term is calculated in the following manner:

[0067] The upper surface reflection coefficient of the layer to which the upward two-way wave secondary virtual source term belongs, the downward wave field propagating from the water surface to the layer to which the upward two-way wave secondary virtual source term belongs, the upward transmission factor of the layer to which the upward two-way wave secondary virtual source term belongs, and the upward wave field propagating from the water surface to the underwater interface and then reflected to the layer to which the upward two-way wave secondary virtual source term belongs are obtained.

[0068] The second virtual reflection value is obtained by multiplying the upper surface reflection coefficient of the layer to which the upward two-way wave secondary virtual source term belongs by the downward wave field propagating from the water surface to the layer to which the upward two-way wave secondary virtual source term belongs.

[0069] The upward transmission factor of the layer to which the upward two-way wave secondary virtual source term belongs is multiplied by the water surface propagation to the underwater interface and then reflected back to the upward wave field of the layer to which the downward two-way wave secondary virtual source term belongs, to obtain the second virtual transmission value.

[0070] The second virtual reflection value and the second virtual transmission value are added together to obtain the second virtual source term of the upward two-way wave.

[0071] The above method can be used to simulate seismic waves; see [link / reference]. Figure 3 The forward modeling record and wavefield separation diagram shown are as follows: (a) is the reflected wavefield information, which does not contain the downlink wavefield in the first iteration simulation; (b) is the shot gather record of the second iteration simulation result, during which source ghost wave information and receiver ghost wave information are generated; (c) represents the downlink single-shot simulation record obtained in the third iteration forward modeling simulation; (d) and (e) are the separated first-order multiples and second-order multiples. Figure 3 The horizontal axis of each subplot represents width in meters (m), and the vertical axis represents time in milliseconds (ms).

[0072] Compared with existing technologies, the method provided in this embodiment of the invention firstly constructs a marine geological model; wherein, in the marine geological model, the interface between the water surface and the underwater surface is divided into multiple layers from top to bottom, and shot points are set at a set depth to excite the seismic wave field; then, the seismic wave field is set to be excited starting from the shot point position at the set depth; next, the downpropagation operators and downpropagation two-way wave secondary virtual source terms of each layer above the first type layer are obtained to calculate the downpropagation wave field propagating from the water surface to the first type layer; wherein, the first type layer is any layer above the shot point layer; the downpropagation operators, downpropagation two-way wave secondary virtual source terms of each layer above the second type layer, and downpropagation real source propagation terms from the shot point layer to the second type layer are obtained to calculate the downpropagation wave field propagating from the water surface to the second type layer; wherein, the second type layer is any layer below the shot point layer. The process involves: obtaining the true upward source propagation term from the layer containing the shot point to the first type of layer, the upward propagation operator for each layer below the first type of layer, and the secondary virtual source term of the upward two-way wave from the water surface to each layer below the first type of layer, to calculate the upward wave field propagating downward from the water surface to the underwater interface and then reflecting back to the first type of layer; obtaining the upward propagation operator for each layer below the second type of layer and the secondary virtual source term of the upward two-way wave from the water surface to each layer below the second type of layer, to calculate the upward wave field propagating downward from the water surface to the underwater interface and then reflecting back to the second type of layer; finally, generating seismic wave data based on the downward wave field propagating from the water surface to the first type of layer, the downward wave field propagating from the water surface to the second type of layer, the upward wave field propagating downward from the water surface to the underwater interface and then reflecting back to the first type of layer, and the upward wave field propagating downward from the water surface to the underwater interface and then reflecting back to the second type of layer, for use in marine earthquake analysis, thereby improving the accuracy of marine earthquake situation analysis.

[0073] See Figure 4 This invention also provides a seismic wave forward modeling simulation device, comprising:

[0074] Model building module 21 is used to build a marine geological model; wherein, in the marine geological model, the water surface and underwater interface are divided into multiple layers from top to bottom, and shot points are set at a set depth to excite seismic wave fields;

[0075] Wavefield excitation module 22 is used to set the seismic wavefield to start excitation from the shot point at a set depth;

[0076] The first down-going wave field calculation module 23 is used to obtain the down-going propagation operators of each layer above the first type layer and the down-going two-way wave secondary virtual source terms of each layer above the first type layer, so as to calculate the down-going wave field propagating from the water surface to the first type layer; wherein, the first type layer is any layer above the layer where the shot point is located.

[0077] The second downlink wave field calculation module 24 is used to obtain the downlink propagation operators of each layer above the second type layer, the downlink two-way wave secondary virtual source terms of each layer above the second type layer, and the downlink real source propagation terms from the layer where the shot point is located to the second type layer, so as to calculate the downlink wave field propagating from the water surface to the second type layer; wherein, the second type layer is any layer below the layer where the shot point is located.

[0078] The first upgoing wave field calculation module 25 is used to obtain the upgoing real source propagation term from the layer where the shot point is located to the first type layer, the upgoing propagation operator of each layer below the first type layer, and the upgoing two-way wave secondary virtual source term from the water surface to each layer below the first type layer, so as to calculate the upgoing wave field that propagates downward from the water surface to the underwater interface and is reflected to the first type layer.

[0079] The second upgoing wave field calculation module 26 is used to obtain the upgoing propagation operators of each layer below the second type of layer and the secondary virtual source term of the upgoing two-way wave from the water surface to each layer below the second type of layer, so as to calculate the upgoing wave field that propagates downward from the water surface to the underwater interface and then reflects upward to the second type of layer.

[0080] Analysis module 27 is used to generate seismic wave data based on the downflow wave field propagating from the water surface to the first type layer, the downflow wave field propagating from the water surface to the second type layer, the upflow wave field propagating downward from the water surface to the underwater interface and then reflected back to the first type layer, and the upflow wave field propagating downward from the water surface to the underwater interface and then reflected back to the second type layer, for use in marine earthquake analysis.

[0081] It is worth noting that the working principle of the seismic wave forward modeling simulation device provided in the above embodiments can be found in the workflow of the seismic wave forward modeling simulation method provided in any of the above embodiments, and will not be repeated here.

[0082] Compared with existing technologies, the seismic wave forward modeling device provided in this invention constructs a marine geological model and sets the seismic wave field to be excited from the shot point at a set depth, generating up-going and down-going waves. During the propagation of the down-going wave, the receiver wave field from the previous round is loaded at the position above the shot point as a secondary virtual source, while the real source and the secondary virtual source propagate simultaneously at the position below the shot point. During the propagation of the up-going wave, only the secondary virtual source propagates below the shot point, while the up-going wave above the shot point contains both the real shot point signal and the secondary virtual source signal. Through iterative calculation, the multiple wave and ghost wave information of marine seismic data are simulated and separated to obtain accurate seismic wave data for marine seismic analysis, thereby improving the accuracy of marine seismic situation analysis.

[0083] See Figure 5This invention also provides a seismic wave forward modeling simulation device, including a processor 31, a memory 32, and a computer program stored in the memory 32 and configured to be executed by the processor 31. When the processor 31 executes the computer program, it implements the steps described in the seismic wave forward modeling simulation method embodiments above, for example... Figure 1 S11 to S17; or, when the processor 31 executes the computer program, it implements the functions of each module in the above-described device embodiments.

[0084] For example, the computer program can be divided into one or more modules, which are stored in the memory 32 and executed by the processor 31 to complete the present invention. The one or more modules can be a series of computer program instruction segments capable of performing specific functions, which describe the execution process of the computer program in the seismic wave forward modeling device. For example, the computer program can be divided into multiple modules, and the specific working process of each module can be referred to the working process of the seismic wave forward modeling device described in the above embodiments, which will not be repeated here.

[0085] The seismic wave forward modeling simulation device can be a desktop computer, laptop, handheld computer, or cloud server, etc. The seismic wave forward modeling simulation device may include, but is not limited to, a processor 31 and a memory 32. Those skilled in the art will understand that the seismic wave forward modeling simulation device may also include input / output devices, network access devices, buses, etc.

[0086] The processor 31 can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor. The processor 31 is the control center of the seismic wave forward modeling equipment, connecting all parts of the equipment via various interfaces and lines.

[0087] The memory 32 can be used to store the computer program and / or modules. The processor 31 implements various functions of the seismic wave forward modeling device by running or executing the computer program and / or modules stored in the memory 32 and calling the data stored in the memory 32. The memory 32 may mainly include a program storage area and a data storage area. The program storage area may store the operating system, at least one application program required for a function (such as image playback function), etc.; the data storage area may store data created based on the use of the mobile phone, etc. In addition, the memory 32 may include high-speed random access memory, and may also include non-volatile memory, such as hard disk, memory, plug-in hard disk, smart memory card (SMC), secure digital card (SD) card, flash card, at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0088] If the modules integrated into the seismic wave forward modeling equipment are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by the processor 31, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc.

[0089] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for seismic wave forward modeling, characterized in that, include: Construct a marine geological model; wherein, in the marine geological model, the interface between the water surface and the underwater surface is divided into multiple layers from top to bottom, and shot points are set at a set depth to generate seismic wave fields; Set the seismic wave field to be excited starting from the shot point at a set depth; Obtain the downpropagation operators and downpropagation two-way wave secondary virtual source terms for each layer above the first type layer to calculate the downpropagation wave field from the water surface to the first type layer; where the first type layer is any layer at or above the shot point layer. The down propagation operators of each layer above the second type of layer, the down two-way wave secondary virtual source terms of each layer above the second type of layer, and the down real source propagation terms from the layer where the shot point is located to the second type of layer are obtained to calculate the down wave field propagating from the water surface to the second type of layer; wherein, the second type of layer is any layer below the layer where the shot point is located. The upward real source propagation term from the layer where the shot point is located to the first type layer, the upward propagation operator of each layer below the first type layer, and the upward two-way wave secondary virtual source term from the water surface to each layer below the first type layer are obtained in order to calculate the upward wave field that propagates downward from the water surface to the underwater interface and is reflected to the first type layer. Obtain the up-propagation operators of each layer below the second type of layer, and the secondary virtual source term of the up-propagation two-way wave from the water surface to each layer below the second type of layer, so as to calculate the up-propagation wave field that propagates downward from the water surface to the underwater interface and then reflects upward to the second type of layer; Seismic wave data are generated based on the downflow wave field propagating from the water surface to the first type layer, the downflow wave field propagating from the water surface to the second type layer, the upflow wave field propagating downwards from the water surface to the underwater interface and then reflecting back to the first type layer, and the upflow wave field propagating downwards from the water surface to the underwater interface and then reflecting back upwards to the second type layer, for use in marine earthquake analysis. The down-travel two-way wave secondary virtual source term is calculated in the following way: The following parameters are obtained: the lower surface reflection coefficient of the layer to which the down-two-way wave secondary virtual source term belongs; the upward wave field that propagates from the water surface downward to the underwater interface and then reflects upward to the layer to which the down-two-way wave secondary virtual source term belongs; the down-transmission factor of the layer to which the down-two-way wave secondary virtual source term belongs; and the down-wave field that propagates from the water surface to the layer to which the down-two-way wave secondary virtual source term belongs. Multiply the reflection coefficient of the lower surface of the layer to which the down-two-way wave secondary virtual source term belongs by the reflection coefficient of the water surface after it propagates downward to the underwater interface and then reflects upward to the up-propagating wave field of the layer to which the down-two-way wave secondary virtual source term belongs, to obtain the first virtual reflection value. Multiply the down transmission factor of the layer to which the down two-way wave secondary virtual source term belongs by the down wave field propagating from the water surface to the layer to which the down two-way wave secondary virtual source term belongs to obtain the first virtual transmission value; The first virtual reflection value and the first virtual transmission value are added together to obtain the second virtual source term of the down-pass two-way wave.

2. The seismic wave forward modeling method of claim 1, wherein, The downflow wave field propagating from the water surface to the first type layer is calculated in the following way: The down propagation operators of each layer above the first type of layer are multiplied by the corresponding down two-way wave second virtual source term and then added together to obtain the down wave field propagating from the water surface to the first type of layer.

3. The seismic wave forward modeling method of claim 1, wherein, The downflow wave field propagating from the water surface to the second type layer is calculated in the following way: The down propagation operators of each layer above the second type of layer are multiplied by the down two-way wave second virtual source term of the corresponding layer and then added together to obtain the first virtual value of each layer above the second type of layer. All the first virtual values ​​are added to the down real source propagation term from the layer where the shot point is located to the second type of layer to obtain the down wave field propagating from the water surface to the second type of layer.

4. The seismic wave forward modeling method of claim 1, wherein, The upward wave field that propagates downwards to the underwater interface and is reflected to the first type layer is calculated in the following way: The uplink propagation operator of each layer below the first type of layer is multiplied by the uplink two-way wave second virtual source term of the corresponding layer to obtain the second virtual value of each layer below the first type of layer. All the second virtual values ​​are added to the uplink real source propagation term from the layer where the shot point is located to the first type of layer to obtain the uplink wave field that propagates downward from the water surface to the underwater interface and is reflected to the first type of layer.

5. The method of claim 1, wherein, The upward wave field, which propagates downwards to the underwater interface and then reflects upwards to the second type of layer, is calculated in the following way: The upward propagation operators of each layer below the second type of layer are multiplied by the corresponding upward two-way wave second virtual source term and then added together to obtain the upward wave field that propagates downward from the water surface to the underwater interface and then reflects upward to the second type of layer.

6. The method according to any one of claims 1 to 4, wherein, The upward two-way wave secondary virtual source term is calculated in the following way: The upper surface reflection coefficient of the layer to which the upward two-way wave secondary virtual source term belongs, the downward wave field propagating from the water surface to the layer to which the upward two-way wave secondary virtual source term belongs, the upward transmission factor of the layer to which the upward two-way wave secondary virtual source term belongs, and the upward wave field propagating from the water surface to the underwater interface and then reflected to the layer to which the upward two-way wave secondary virtual source term belongs are obtained. The second virtual reflection value is obtained by multiplying the upper surface reflection coefficient of the layer to which the upward two-way wave secondary virtual source term belongs by the downward wave field propagating from the water surface to the layer to which the upward two-way wave secondary virtual source term belongs. The upward transmission factor of the layer to which the upward two-way wave secondary virtual source term belongs is multiplied by the water surface propagation to the underwater interface and then reflected back to the upward wave field of the layer to which the downward two-way wave secondary virtual source term belongs, to obtain the second virtual transmission value. The second virtual reflection value and the second virtual transmission value are added together to obtain the second virtual source term of the upward two-way wave.

7. A device for seismic wave forward modeling, characterized in that, include: The model building module is used to build a marine geological model; wherein, in the marine geological model, the water surface and underwater interface are divided into multiple layers from top to bottom, and shot points are set at a set depth to excite the seismic wave field; The wave field excitation module is used to set the seismic wave field to be excited from the shot point at a set depth; The first down-going wave field calculation module is used to obtain the down-going propagation operators and down-going two-way wave secondary virtual source terms of each layer above the first type layer, so as to calculate the down-going wave field propagating from the water surface to the first type layer; wherein, the first type layer is any layer above the layer where the shot point is located. The second downlink wave field calculation module is used to obtain the downlink propagation operators of each layer above the second type layer, the downlink two-way wave secondary virtual source terms of each layer above the second type layer, and the downlink real source propagation terms from the layer where the shot point is located to the second type layer, so as to calculate the downlink wave field propagating from the water surface to the second type layer; wherein, the second type layer is any layer below the layer where the shot point is located. The first upgoing wave field calculation module is used to obtain the upgoing real source propagation term from the layer where the shot point is located to the first type layer, the upgoing propagation operator of each layer below the first type layer, and the upgoing two-way wave secondary virtual source term from the water surface to each layer below the first type layer, so as to calculate the upgoing wave field that propagates downward from the water surface to the underwater interface and is reflected to the first type layer. The second upgoing wave field calculation module is used to obtain the upgoing propagation operators of each layer below the second type of layer and the secondary virtual source term of the upgoing two-way wave from the water surface to each layer below the second type of layer, so as to calculate the upgoing wave field that propagates downward from the water surface to the underwater interface and then reflects upward to the second type of layer. The analysis module is used to generate seismic wave data based on the downflow wave field propagating from the water surface to the first type layer, the downflow wave field propagating from the water surface to the second type layer, the upflow wave field propagating downward from the water surface to the underwater interface and then reflecting back to the first type layer, and the upflow wave field propagating downward from the water surface to the underwater interface and then reflecting back upward to the second type layer, for use in marine earthquake analysis. The down-travel two-way wave secondary virtual source term is calculated in the following way: The following parameters are obtained: the lower surface reflection coefficient of the layer to which the down-two-way wave secondary virtual source term belongs; the upward wave field that propagates from the water surface downward to the underwater interface and then reflects upward to the layer to which the down-two-way wave secondary virtual source term belongs; the down-transmission factor of the layer to which the down-two-way wave secondary virtual source term belongs; and the down-wave field that propagates from the water surface to the layer to which the down-two-way wave secondary virtual source term belongs. Multiply the reflection coefficient of the lower surface of the layer to which the down-two-way wave secondary virtual source term belongs by the reflection coefficient of the water surface after it propagates downward to the underwater interface and then reflects upward to the up-propagating wave field of the layer to which the down-two-way wave secondary virtual source term belongs, to obtain the first virtual reflection value. Multiply the down transmission factor of the layer to which the down two-way wave secondary virtual source term belongs by the down wave field propagating from the water surface to the layer to which the down two-way wave secondary virtual source term belongs to obtain the first virtual transmission value; The first virtual reflection value and the first virtual transmission value are added together to obtain the second virtual source term of the down-pass two-way wave.

8. A seismic wave forward modeling device, characterized by, It includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor, when executing the computer program, implements the seismic wave forward modeling method as described in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored computer program, wherein, when the computer program is executed, it controls the device containing the computer-readable storage medium to perform the seismic wave forward modeling method as described in any one of claims 1 to 6.

Images