Elastic wave stress tensor double dot product seismic imaging method, device and equipment

Abstract

This article relates to the field of exploration geophysics, and in particular to a double-dot-product seismic imaging method, device, and equipment for elastic wave stress tensor. This includes obtaining a decoupled particle vibration velocity vector wave field by using the existing decoupled wave equation method on the detection wave field; then using the obtained decoupled particle vibration velocity vector wave field to construct a decoupled pseudo-stress equation to obtain a decoupled pseudo-stress wave field; and finally using the double-dot-product cross-correlation imaging condition algorithm to calculate the second-order stress tensor wave field of the earthquake source and the decoupled detection second-order stress tensor wave field to obtain the final scalar imaging result. Through the embodiments of this article, it is possible to realize the joint exploration of longitudinal and shear waves, so as to use the obtained imaging to accurately predict the risks of gas exploration, thereby solving the problem that the existing longitudinal wave imaging technology cannot give full play to the advantages of the joint exploration of longitudinal and shear waves, resulting in the inability to accurately predict the risks of oil and gas exploration using multi-wave imaging results.

Description

Technical Field

[0001] The present invention relates to the field of exploration geophysics, and in particular to a method, device and equipment for elastic wave stress tensor double dot product seismic imaging. Background Art

[0002] In current elastic reverse time migration imaging, the commonly used structurally decoupled wave equation separation technique cannot obtain crosstalk-free shear stress. Furthermore, the stress field is essentially a second-order tensor, and existing scalar or vector correlation imaging conditions cannot be directly applied to second-order stress tensor wave fields. Conventional stress imaging, which mostly relies on a single P-wave component, fails to leverage the advantages of combined P- and S-wave exploration, resulting in poor imaging quality and an inability to accurately predict oil and gas exploration risks.

[0003] There is an urgent need for an elastic wave stress tensor double dot product seismic imaging method to solve the problem that existing P-wave imaging technology cannot give full play to the advantages of joint P-wave and S-wave exploration, resulting in the inability to accurately use multi-wave imaging results to predict the risks of oil and gas exploration. Summary of the Invention

[0004] To address the problem that existing P-wave imaging technology cannot leverage the advantages of combined P-wave and S-wave exploration, resulting in an inability to accurately predict the risks of oil and gas exploration using multi-wave imaging results, the embodiments of this article provide an elastic wave stress tensor double-dot product seismic imaging method, device, and apparatus, which can obtain a decoupled stress wave field. The corresponding imaging conditions take into account each part of the energy in the stress tensor wave field and can obtain scalar imaging results through a relatively simple calculation process. The stress imaging results obtained in this article include both P-wave stress imaging and S-wave stress imaging, which can realize combined P-wave and S-wave stress exploration, thereby using the obtained imaging to accurately predict the risks of gas exploration.

[0005] In order to solve the above technical problems, the specific technical solutions of this article are as follows:

[0006] On the one hand, the embodiments of this invention provide a method for elastic wave stress tensor double dot product seismic imaging, comprising:

[0007] Based on the first-order velocity-stress equation of elastic isotropic media, the medium model parameters, source wavelet function and multi-component seismic records are used as input. The staggered grid high-order finite difference method is used to solve the first-order velocity-stress equation, and the source stress tensor wavefield and the detector particle vibration velocity vector wavefield are obtained.

[0008] Using the detection particle vibration velocity vector wave field, a decoupled wave equation is constructed to obtain a decoupled detection longitudinal wave particle vibration velocity vector wave field and a decoupled detection shear wave vibration velocity vector wave field;

[0009] A decoupled pseudo-stress equation is constructed using the decoupled detection longitudinal wave particle vibration velocity vector wave field and the decoupled detection shear wave vibration velocity vector wave field to obtain a decoupled pseudo-stress tensor wave field;

[0010] A double dot product cross-correlation imaging condition is applied to the source stress tensor wavefield and the detection decoupled pseudo stress tensor wavefield to obtain pseudo PP scalar imaging results and pseudo PS scalar imaging results, which are used as elastic wave stress tensor double dot product seismic imaging results.

[0011] Furthermore, the first-order velocity-stress equation of the elastic isotropic medium is:

[0012]

[0013] Among them, (τ xx ,τ zz ,τ xz ) represents the source stress tensor wave field, (v x ,v z ) represents the vibration velocity vector wave field of the detection particle, λ and μ represent Lame parameters, ρ represents density; t represents time; x and z represent the x and z directions of the two-dimensional Cartesian coordinate system respectively;

[0014] The grid points of the staggered grid are defined as (1:v x ; 2: τ xx ,τ zz ; 3: τ xz ;4:v z ), where 1, 2, 3, and 4 are four different spatial positions in the cells of the staggered grid.

[0015] Furthermore, based on the first-order velocity-stress equation of elastic isotropic medium, the medium model parameters, source wavelet function and multi-component seismic records are used as input, and the staggered grid high-order finite difference method is used to solve the first-order velocity-stress equation of elastic isotropic medium, and the source stress tensor wave field and the detection particle vibration velocity vector wave field are obtained.

[0016] Based on the grid point definition, the staggered grid high-order finite difference method is used to discretize the first-order velocity-stress equation of the elastic isotropic medium, and the discretization format is obtained as follows:

[0017]

[0018] Wherein, Δt represents the time interval, i and k represent the discrete points in the x and z directions in the two-dimensional Cartesian coordinate system, n represents the discrete points in the time t direction, and ρ- 1 represents the density ρ to the power of -1, F s(s=x,z) and B s (s=x,z) are the forward difference operator and backward difference operator in the x and z directions respectively. The specific expressions are:

[0019]

[0020]

[0021]

[0022]

[0023] Among them, Δx and Δz represent the sampling intervals in the x and z directions, and f i,k represents the wave field quantity acted upon by the differential operator, i and k represent the discrete points used to determine the spatial position of the wave field quantity, represents the finite difference coefficients of the staggered grid of order 2M, where 2M represents the difference order and M represents a positive integer;

[0024] Using the discrete format, according to the given medium model parameters, the Lamé parameters λ and μ, and the density ρ are obtained;

[0025] The longitudinal wave source in the form of Ricker wavelet loaded in the continuation process of the source wave field is loaded on the (τ xx ,τ zz ), the earthquake source stress tensor wave field (τ xx ,τ zz ,τ xz );

[0026] The multi-component seismic record of the detection wave field in the continuation process is loaded onto the vibration velocity vector wave field (v x ,v z ), calculate and obtain the vibration velocity vector wave field (v x ,v z ).

[0027] Furthermore, constructing a decoupled wave equation using the detection particle vibration velocity vector wave field to obtain a decoupled detection longitudinal wave particle vibration velocity vector wave field and a detection shear wave vibration velocity vector wave field further includes:

[0028] The decoupled wave equation is,

[0029]

[0030] Among them, τ P represents the auxiliary longitudinal wave stress;

[0031] The decoupling detection longitudinal wave particle vibration velocity vector wave field is:

[0032]

[0033] in, Represents the longitudinal wave particle vibration velocity vector wave field;

[0034] The decoupling detection shear wave vibration velocity vector wave field is:

[0035]

[0036] Among them, (v x S,v z S ) represents the shear wave particle vibration velocity vector wave field.

[0037] Furthermore, the decoupling detection longitudinal wave particle vibration velocity vector wave field and the decoupling detection shear wave vibration velocity vector wave field are used to construct a decoupling pseudo stress equation, and the detection decoupling pseudo stress tensor wave field is obtained, further comprising:

[0038] The decoupled pseudo-stress equation includes a longitudinal wave pseudo-stress equation and a transverse wave pseudo-stress equation, wherein the longitudinal wave pseudo-stress equation is:

[0039]

[0040] in, represents the longitudinal wave pseudo stress;

[0041] The shear wave pseudo stress equation is:

[0042]

[0043] in, represents shear wave pseudo stress;

[0044] The decoupling detection longitudinal wave particle vibration velocity vector wave field Decoupling detection of shear wave particle vibration velocity vector wave field Substitute them into the longitudinal wave pseudo stress equation and the shear wave pseudo stress equation respectively to obtain the detection decoupled pseudo stress tensor wave field Rcv, wherein the detection decoupled pseudo stress tensor wave field includes the detection longitudinal wave decoupled pseudo stress tensor wave field Decoupling pseudo-stress tensor wave field from detected shear waves

[0045] Furthermore, applying a double dot product cross-correlation imaging condition to the source stress tensor wavefield and the detection decoupled pseudo stress tensor wavefield to obtain a pseudo PP scalar imaging result and a pseudo PS scalar imaging result further includes:

[0046] The source stress tensor wave field Src=(τxx ,τ zz ,τ xz ) and the detection decoupling pseudo stress tensor wave field Rcv apply double dot product cross-correlation imaging conditions:

[0047]

[0048] The pseudo PP scalar imaging result and the pseudo PS scalar imaging result are obtained by calculation, wherein I qPP is the pseudo-PP scalar imaging result, I qPS is the pseudo-PS scalar imaging result, x represents the spatial position, t represents the time; Src and Rcv are the corresponding component forms of the source stress tensor wavefield Src and the detection decoupled pseudo stress tensor wavefield, respectively.

[0049] On the other hand, the embodiments of this invention further provide an elastic wave stress tensor double dot product seismic imaging device, comprising:

[0050] A first-order velocity-stress equation solving unit is used to solve the first-order velocity-stress equation of the elastic isotropic medium based on the medium model parameters, the source wavelet function and the multi-component seismic record by using the staggered grid high-order finite difference method to obtain the source stress tensor wave field and the detector particle vibration velocity vector wave field;

[0051] a decoupled wave equation solving unit, configured to construct a decoupled wave equation using the detection particle vibration velocity vector wave field to obtain a decoupled detection longitudinal wave particle vibration velocity vector wave field and a decoupled detection shear wave vibration velocity vector wave field;

[0052] a decoupled pseudo-stress equation solving unit, configured to construct a decoupled pseudo-stress equation using the decoupled detection longitudinal wave particle vibration velocity vector wave field and the decoupled detection shear wave vibration velocity vector wave field to obtain a decoupled pseudo-stress tensor wave field;

[0053] An imaging result calculation unit is used to apply a double dot product cross-correlation imaging condition to the source stress tensor wavefield and the detection decoupled pseudo stress tensor wavefield to obtain a pseudo PP scalar imaging result and a pseudo PS scalar imaging result, and use the pseudo PP scalar imaging result and the pseudo PS scalar imaging result as the elastic wave stress tensor double dot product seismic imaging result.

[0054] On the other hand, an embodiment of the present invention further provides a computer device, including a memory, a processor, and a computer program stored in the memory, wherein the processor implements the above method when executing the computer program.

[0055] On the other hand, an embodiment of the present invention further provides a computer storage medium storing a computer program. When the computer program is executed by a processor of a computer device, the above method is executed.

[0056] Using the embodiments of this paper, by applying the existing decoupled wave equation method to the detector wavefield, a decoupled particle vibration velocity vector wavefield is obtained. The decoupled particle vibration velocity vector wavefield is then used to construct a decoupled pseudo-stress equation to obtain a decoupled pseudo-stress wavefield. Finally, a double-dot-product cross-correlation imaging condition algorithm is used to calculate the source second-order stress tensor wavefield and the decoupled detector second-order stress tensor wavefield to obtain the final scalar imaging result. The stress imaging results obtained in this paper include both longitudinal and shear wave stress imaging, enabling joint exploration of longitudinal and shear waves. The resulting imaging can then be used to accurately predict gas exploration risks, resolving the problem that existing longitudinal wave imaging technology cannot leverage the advantages of joint longitudinal and shear wave exploration, resulting in an inability to accurately predict oil and gas exploration risks using multi-wave imaging results. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the technical solutions in the embodiments of this article or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of this article. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0058] Figure 1 FIG2 is a flow chart of a method for double-dot-product seismic imaging of elastic wave stress tensors according to an embodiment of the present invention;

[0059] Figure 2a and Figure 2b Shown is a schematic diagram of the definition of the staggered grid in the embodiment of this article;

[0060] Figure 3 The figure shows a schematic diagram of specific parameters of the elastic model with a horizontal-vertical interface according to the embodiment of this article;

[0061] Figure 4a 、 Figure 4b and Figure 4c The examples in this paper are shown Figure 2a and Figure 2b The wave field snapshot of the model shown in the forward decoupled longitudinal wave pseudo-stress at 450ms;

[0062] Figure 5a 、 Figure 5b and Figure 5c The examples in this paper are shown Figure 2a and Figure 2b The wave field snapshot of the model shown in the forward decoupled shear wave pseudo stress at 450ms;

[0063] Figure 6a 、 Figure 6b and Figure 6c The Marmousi2 model after resampling in the embodiment of this article is shown;

[0064] Figure 7a and Figure 7b The examples in this paper are shown Figure 5a 、 Figure 5b and Figure 5c Migration imaging results shown;

[0065] Figure 8a 、 Figure 8b and Figure 8c The examples shown are Figure 6a 、 Figure 6b and Figure 6c The image obtained by zooming in on the Marmousi2 model at a width of 1000m to 3200m and a depth of 1100m to 1600m;

[0066] Figure 9a and Figure 9b The examples in this paper are shown Figure 8a and Figure 8b The area shown is the migration imaging result using the method proposed in this paper;

[0067] Figure 10 FIG2 is a schematic structural diagram of an elastic wave stress tensor double dot product seismic imaging device according to an embodiment of the present invention;

[0068] Figure 11 Shown is a schematic structural diagram of a computer device according to an embodiment of this invention.

[0069]

Description of the accompanying drawings

[0070] 1001. First-order velocity-stress equation solving unit;

[0071] 1002. Decoupled wave equation solving unit;

[0072] 1003. Decoupled pseudo-stress equation solving unit;

[0073] 1004. Imaging result calculation unit;

[0074] 1102. Computer equipment;

[0075] 1104. Processing equipment;

[0076] 1106. Storage resources;

[0077] 1108, driving mechanism;

[0078] 1110, input / output module;

[0079] 1112. Input device;

[0080] 1114. Output device;

[0081] 1116. Presentation equipment;

[0082] 1118. Graphical User Interface;

[0083] 1120, network interface;

[0084] 1122, communication link;

[0085] 1124. Communication bus. DETAILED DESCRIPTION

[0086] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in the embodiments of this document. Obviously, the embodiments described are only part of the embodiments of this document, not all of the embodiments. Based on the embodiments of this document, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this document.

[0087] It should be noted that the terms "first," "second," and the like in the specification and claims herein and in the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having," as well as any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, apparatus, product, or device comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to these processes, methods, products, or devices.

[0088] It should be noted that the acquisition, storage, use, and processing of data in the technical solution of this application comply with the relevant provisions of national laws and regulations.

[0089] To address the problems existing in the prior art, an embodiment of this invention provides an elastic wave stress tensor double dot product seismic imaging method, which can obtain a decoupled stress wave field. The corresponding imaging conditions take into account every part of the energy in the stress tensor wave field and obtain scalar imaging results through a relatively simple calculation process. Figure 1The figure shows a flow chart of a double dot product seismic imaging method of elastic wave stress tensor in an embodiment of this invention. The process of imaging based on seismic stress is described in this figure, but more or fewer operation steps may be included based on conventional or non-creative work. The order of steps listed in the embodiment is only one way of executing the order of many steps and does not represent the only execution order. When the system or device product is actually executed, it can be executed in sequence or in parallel according to the method shown in the embodiment or the accompanying drawings. Specifically, Figure 1 As shown, the method can be executed by a processor and may include:

[0090] Step 101: Based on the first-order velocity-stress equation of elastic isotropic media, the medium model parameters, source wavelet function and multi-component seismic records are used as input, and the first-order velocity-stress equation is solved using a staggered grid high-order finite difference method to obtain the source stress tensor wavefield and the detector particle vibration velocity vector wavefield;

[0091] Step 102: constructing a decoupled wave equation using the detection particle vibration velocity vector wave field to obtain a decoupled detection longitudinal wave particle vibration velocity vector wave field and a decoupled detection shear wave vibration velocity vector wave field;

[0092] Step 103: constructing a decoupled pseudo-stress equation using the decoupled detection longitudinal wave particle vibration velocity vector wave field and the decoupled detection shear wave vibration velocity vector wave field to obtain a decoupled pseudo-stress tensor wave field;

[0093] Step 104: Apply a double dot product cross-correlation imaging condition to the source stress tensor wavefield and the detection decoupled pseudo stress tensor wavefield to obtain a pseudo PP scalar imaging result and a pseudo PS scalar imaging result, and use the pseudo PP scalar imaging result and the pseudo PS scalar imaging result as the elastic wave stress tensor double dot product seismic imaging result.

[0094] Using the embodiments of this paper, by applying the existing decoupled wave equation method to the detector wavefield, a decoupled particle vibration velocity vector wavefield is obtained. The decoupled particle vibration velocity vector wavefield is then used to construct a decoupled pseudo-stress equation to obtain a decoupled pseudo-stress wavefield. Finally, a double-dot-product cross-correlation imaging condition algorithm is used to calculate the source second-order stress tensor wavefield and the decoupled detector second-order stress tensor wavefield to obtain the final scalar imaging result. The stress imaging results obtained in this paper include both longitudinal and shear wave stress imaging, enabling joint exploration of longitudinal and shear waves. The resulting imaging can then be used to accurately predict gas exploration risks, resolving the problem that existing longitudinal wave imaging technology cannot leverage the advantages of joint longitudinal and shear wave exploration, resulting in an inability to accurately predict oil and gas exploration risks using multi-wave imaging results.

[0095] The elastic wave stress tensor double dot product seismic imaging method described in the embodiment of this invention includes the following steps:

[0096] Step 1: Based on the first-order velocity-stress equation for elastic isotropic media, the medium model parameters, source wavelet function, and multi-component seismic records are used as input. The first-order velocity-stress equation is solved using the staggered grid high-order finite difference method to obtain the source stress tensor wavefield and the detector particle vibration velocity vector wavefield.

[0097] The first-order velocity-stress equation for elastic isotropic media is formula (1):

[0098]

[0099] Among them, (τ xx ,τ zz ,τ xz ) represents the source stress tensor wave field, (v x ,v z ) represents the vibration velocity vector wave field of the detection particle, λ and μ represent Lame parameters, ρ represents density; t represents time; x and z represent the x and z directions of the two-dimensional Cartesian coordinate system respectively;

[0100] The definition of staggered grid is as follows Figure 2a and Figure 2b As shown, Figure 2a is a schematic diagram of the entire space grid, Figure 2b The unit grid is defined, where the full grid is represented by a solid line and the half grid is represented by a dotted line. Figure 2b The four different spatial relative positions of 1, 2, 3, and 4 will be used to calculate the source stress tensor wave field (τ xx ,τ zz ,τ xz ) and the detection particle vibration velocity vector wave field, as shown in formula (2):

[0101] (1:v x ; 2: τ xx ,τ zz ; 3: τ xz ;4:v z ) (2)

[0102] Based on the above grid definition, the staggered grid high-order finite difference method is used to discretize the first-order velocity-stress equation of elastic isotropic medium, and the discretization format is obtained as formula (3):

[0103]

[0104] In the discrete format, Δt represents the time interval, i and k represent the discrete points in the x and z directions in the two-dimensional Cartesian coordinate system, n represents the discrete points in the time t direction, and ρ -1 represents the density ρ to the power of -1, F s(s=x,z) and B s (s=x,z) are the forward difference operator and the backward difference operator in the x and z directions respectively. The specific expression is formula (4):

[0105]

[0106] Among them, Δx and Δz represent the sampling intervals in the x and z directions, and f i,k represents the wave field quantity acted by the differential operator, i and k represent the discrete points used to determine the spatial position of the wave field quantity, represents the finite difference coefficients of the staggered grid of order 2M, where 2M represents the difference order and M represents a positive integer;

[0107] Using the above discrete format, the Lamé parameters λ and μ, and the density ρ are obtained according to the given medium model parameters. In the process of source wave field extension, the longitudinal wave source is loaded on the stress tensor wave field (τ xx ,τ zz ) component, iteratively update the particle vibration velocity component (v x ,v z ) and the particle stress tensor wave field (τ xx ,τ zz ,τ xz ), the earthquake source stress tensor wave field (τ xx ,τ zz ,τ xz ); In the process of wave field extension, the multi-component seismic record is loaded into the vibration velocity vector wave field (v x ,v z ), iteratively update the particle stress tensor wave field (τ xx ,τ zz ,τ xz ) and the particle vibration velocity component (v x ,v z ), calculate and obtain the vibration velocity vector wave field of the detection particle (v x ,v z ).

[0108] Step 2: Use the detection particle vibration velocity vector wave field (v x ,v z ) The auxiliary longitudinal wave stress of the structure is shown in formula (5):

[0109]

[0110] Among them, τ PDenotes the auxiliary longitudinal wave stress. Solving formula (5), we can obtain the decoupled detection longitudinal wave particle vibration velocity vector wave field and the decoupled detection shear wave vibration velocity vector wave field.

[0111] Among them, the decoupled detection longitudinal wave particle vibration velocity vector wave field is formula (6):

[0112]

[0113] in, Represents the longitudinal wave particle vibration velocity vector wave field;

[0114] The decoupled detection shear wave vibration velocity vector wave field is formula (7):

[0115]

[0116] in, Represents the shear wave particle vibration velocity vector wave field.

[0117] Step 3: Use the decoupled detection longitudinal wave particle vibration velocity vector wave field and the decoupled detection shear wave vibration velocity vector wave field to construct a decoupled pseudo stress equation and obtain the detection decoupled pseudo stress tensor wave field;

[0118] The longitudinal wave pseudo stress equation is formula (8):

[0119]

[0120] Formula (8) is expanded into formula (9):

[0121]

[0122] The shear wave pseudo stress equation is formula (10):

[0123]

[0124] Formula (10) is expanded into formula (11):

[0125]

[0126] In formulas (8)-(11), represents the longitudinal wave pseudo stress, represents the shear wave pseudo stress, δ ij is the Kronecker function.

[0127] Decoupling the detection longitudinal wave particle vibration velocity vector wave field Decoupling detection of shear wave particle vibration velocity vector wave field Substituted into the longitudinal wave pseudo stress equation and the shear wave pseudo stress equation respectively, the detection decoupled pseudo stress tensor wave field Rcv is obtained, where the detection decoupled pseudo stress tensor wave field includes the detection longitudinal wave decoupled pseudo stress tensor wave field Decoupling pseudo-stress tensor wave field from detected shear waves

[0128] Step 4: Calculate the source stress tensor wave field The double dot product cross-correlation imaging condition is applied to the decoupled pseudo stress tensor wave field Rcv, as shown in formula (12):

[0129]

[0130] Among them, I qPP is the pseudo-PP scalar imaging result, I qPS is the pseudo-PS scalar imaging result, the position vector x represents the spatial position coordinate (x, z) of the calculation node in the two-dimensional Cartesian coordinate system, t represents time, and : is the double dot product operator symbol; the double dot product algorithm is expanded as shown in formula (13):

[0131]

[0132] Where Src and Rcv are the corresponding component forms of the source stress tensor wave field Src and the detector decoupled pseudo stress tensor wave field, respectively. denote the xx, zz, and xz components of the source stress tensor, respectively. denote the xx, zz, and xz components of the decoupled longitudinal wave pseudo-stress tensor, They represent the xx, zz, and xz components of the decoupled shear wave pseudo stress tensor. qPP The pseudo-PS scalar imaging results are used as the double dot product seismic imaging results of elastic wave stress tensor. qPP and pseudo PS imaging results I qPS The difference from the traditional PP and PS imaging results is that the traditional imaging results mostly use the particle vibration velocity vector or displacement field for imaging, while I qPP and I qPS Imaging is performed using elastic stress wave fields that satisfy the tensor form.

[0133] The embodiments of this paper can obtain a second-order tensor-decoupled stress wavefield corresponding to the total stress wavefield. Through the double-dot-product cross-correlation imaging condition, the second-order stress tensor wavefield can be directly used to obtain scalar imaging results. This has a clearer physical meaning. Moreover, this imaging condition fully considers each component of the tensor wavefield, realizing elastic reverse time migration stress imaging and providing an additional option for elastic reverse time migration algorithms.

[0134] For example, in conjunction with the application of the stress wave field decoupling method of the elastic model with horizontal-vertical interface described herein, the model and its parameters are as follows: Figure 3 As shown, in Figure 3 In the figure, the horizontal axis "Distance" represents the model width, and the vertical axis "Depth" represents the model depth, both in "km". Figure 3 a, b, and c in the equation represent the longitudinal wave velocity, shear wave velocity, and density, respectively. Using the 30 Hz main frequency Ricker wavelet source function to excite pure longitudinal waves as input, the wave field is simulated. Step 1 of this article is applied to obtain the detection particle vibration velocity vector wave field. Then, the decoupled wave equation in step 2 of the present invention is applied to obtain the decoupled detection longitudinal wave particle vibration velocity vector wave field and the decoupled detection shear wave vibration velocity vector wave field. Then, the pseudo-stress decoupling equation in step 3 of the present invention is applied to obtain the decoupled longitudinal and shear wave pseudo-stresses. The decoupled detection longitudinal wave pseudo-stress results are shown in Figure 2. Figure 4a 、 Figure 4b and Figure 4c As shown, the decoupled detection shear wave pseudo stress results are as follows Figure 5a Figure 5b and Figure 5c As shown, Figure 4a 、 Figure 4b 、 Figure 4c and Figure 5a Figure 5b 、 Figure 5c The horizontal axis "Distance" represents the model width, and the vertical axis "Depth" represents the model depth, both in "km". Figure 4a 、 Figure 4b 、 Figure 4c and Figure 5a 、 Figure 5b 、 Figure 5c It can be seen that the transmission and reflection P waves and the converted transmission and reflection S waves are successfully decoupled at the interface, which shows that the stress decoupling method in this paper is correct and effective.

[0135] In order to verify the adaptability of the double dot product cross-correlation imaging condition method in this paper to complex models, the stress decoupling and imaging conditions of this paper are used in the elastic wave imaging experiment of the resampled Marmousi2 model. Figure 6a 、 Figure 6b and Figure 6c As shown, Figure 6a represents the Marmousi2 model longitudinal wave velocity model, Figure 6b represents the Marmousi2 model longitudinal wave velocity model, Figure 6c represents the shear wave velocity model and density model.

[0136] The following uses a certain shot imaging as an example to illustrate the migration imaging process of the present invention.

[0137] The source wave field is forward extrapolated with the source function as input, and the detection wave field is reversely extrapolated with the unseparated multi-component seismic data as input to obtain the elastic wave field at each moment; the detection wave field is applied in step 1 of this article to obtain the detection particle vibration velocity vector wave field, and then the decoupled wave equation in step 2 of this article is applied to obtain the decoupled detection longitudinal wave particle vibration velocity vector wave field and the decoupled detection shear wave vibration velocity vector wave field; then the pseudo-stress decoupling equation in step 3 of this article is applied to obtain the decoupled longitudinal and shear wave pseudo-stress; combined with the source stress wave field and the detection decoupled pseudo-stress wave field, the double dot product cross-correlation imaging condition in step 4 is applied to obtain the scalar imaging result. The above process is applied to obtain the single-shot imaging result, and the final multi-shot superposition result is as follows: Figure 7a and Figure 7b As shown, Figure 7a Represents the scalar pseudo-PP imaging result I qPP , Figure 7b Represents the scalar pseudo PS imaging result I qPS ,by Figure 6a 、 Figure 6b and Figure 6c The model in is used for comparison. The imaging results well image the structure, stratum, depth and other information of the model, which shows that the dual dot product cross-correlation imaging condition of the present invention can be applied to elastic reverse time migration stress imaging of complex media.

[0138] To further illustrate the advantages of this method in seismic exploration oil and gas interpretation, the Marmousi2 model with a width of 1000m to 3200m and a depth of 1100m to 1600m is enlarged as shown in the figure. Figure 8a 、 Figure 8b and Figure 8c As shown, Figure 8a represents the P-wave velocity model of this part, Figure 8b represents the shear wave velocity model of this part, Figure 8c The density model of this part is shown in the enlarged model. It can be seen that there is a special lithology area (the five-pointed star position) in this area. The P-wave and S-wave velocities of this special lithology area are the same, but the density is obviously different. In addition, there is a "lens" structure ( Figure 7a and Figure 7b In oil and gas exploration, lens structures are usually favorable locations for oil and gas accumulation and are also one of the key exploration targets. Figure 9a and Figure 9b As shown, Figure 9a Represents the scalar pseudo-PP imaging result of the region I qPP , Figure 9b Represents the scalar pseudo PS imaging result of the region I qPS ,from Figure 9a and Figure 9bThe imaging results show that in the special lithologic area, the top and bottom interfaces I qPP and I qPS Very clear imaging was obtained ( Figure 9a and Figure 9b At the position of the five-pointed star), but at the top interface of the "lens" I qPP The imaging result is very blurry, and the outline of the top interface of the "lens" is basically invisible ( Figure 9a This will increase the risk of actual oil and gas exploration, which is also a problem faced by traditional single-component seismic exploration. Figure 9b I qPS The imaging results clearly depict the top interface of the lens, which is crucial for both oil and gas exploration and subsequent interpretation and reserve calculation. Therefore, this method can be used in the combined interpretation of seismic exploration and imaging, potentially reducing the risks of oil and gas exploration.

[0139] Based on the same inventive concept, the embodiment of this invention also provides an elastic wave stress tensor double dot product seismic imaging device, such as Figure 10 Shown, including:

[0140] The first-order velocity-stress equation solving unit 1001 is used to solve the first-order velocity-stress equation of the elastic isotropic medium based on the medium model parameters, the source wavelet function and the multi-component seismic record using the staggered grid high-order finite difference method to obtain the source stress tensor wave field and the detector particle vibration velocity vector wave field;

[0141] The decoupled wave equation solving unit 1002 is used to construct a decoupled wave equation using the detection particle vibration velocity vector wave field to obtain a decoupled detection longitudinal wave particle vibration velocity vector wave field and a decoupled detection shear wave vibration velocity vector wave field;

[0142] The decoupled pseudo-stress equation solving unit 1003 is used to construct a decoupled pseudo-stress equation using the decoupled detection longitudinal wave particle vibration velocity vector wave field and the decoupled detection shear wave vibration velocity vector wave field to obtain a detection decoupled pseudo-stress tensor wave field;

[0143] An imaging result calculation unit 1004 is configured to apply a double dot product cross-correlation imaging condition to the source stress tensor wavefield and the detection decoupled pseudo stress tensor wavefield to obtain a pseudo PP scalar imaging result and a pseudo PS scalar imaging result, and use the pseudo PP scalar imaging result and the pseudo PS scalar imaging result as elastic wave stress tensor double dot product seismic imaging results.

[0144] Since the principle of solving the problem by the above device is similar to that of the above method, the implementation of the above device can refer to the implementation of the above method, and the repeated parts will not be repeated.

[0145] like Figure 11 The diagram shows a schematic diagram of the structure of a computer device according to an embodiment of the present invention. The apparatus herein may be a computer device according to this embodiment, executing the method described above. Computer device 1102 may include one or more processing devices 1104, such as one or more central processing units (CPUs), each of which may implement one or more hardware threads. Computer device 1102 may also include any storage resources 1106 for storing any type of information, such as code, settings, data, etc. For example, and without limitation, storage resources 1106 may include any one or more combinations of the following: any type of RAM, any type of ROM, flash memory devices, hard disks, optical disks, etc. More generally, any storage resource may use any technology to store information. Furthermore, any storage resource may provide volatile or non-volatile retention of information. Furthermore, any storage resource may represent a fixed or removable component of computer device 1102. In one embodiment, when processing device 1104 executes associated instructions stored in any storage resource or combination of storage resources, computer device 1102 may perform any operation of the associated instructions. The computer device 1102 also includes one or more drive mechanisms 1108 for interacting with any storage resources, such as a hard disk drive mechanism, an optical disk drive mechanism, and the like.

[0146] The computer device 1102 may also include an input / output module 1110 (I / O) for receiving various inputs (via input devices 1112) and for providing various outputs (via output devices 1114). A specific output mechanism may include a presentation device 1116 and an associated graphical user interface (GUI) 1118. In other embodiments, the input / output module 1110 (I / O), input devices 1112, and output devices 1114 may not be included, and the computer device 1102 may simply be a computer device in a network. The computer device 1102 may also include one or more network interfaces 1120 for exchanging data with other devices via one or more communication links 1122. One or more communication buses 1124 couple the components described above together.

[0147] The communication link 1122 may be implemented in any manner, for example, via a local area network, a wide area network (e.g., the Internet), a point-to-point connection, etc., or any combination thereof. The communication link 1122 may include any combination of hardwired links, wireless links, routers, gateway functions, name servers, etc., governed by any protocol or combination of protocols.

[0148] Corresponding to Figure 1 In the method, an embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the above steps are executed.

[0149] The embodiment of the present invention also provides a computer readable instruction, wherein when the processor executes the instruction, the program causes the processor to execute the following Figure 1 method.

[0150] It should be understood that in the various embodiments of this document, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this document.

[0151] It should also be understood that in the embodiments herein, the term "and / or" merely describes an association between associated objects, indicating that three possible relationships exist. For example, "A and / or B" could represent: A alone, A and B simultaneously, or B alone. Furthermore, the character " / " in this document generally indicates an "or" relationship between the associated objects.

[0152] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the above description has generally described the composition and steps of each example according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this document.

[0153] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0154] In the several embodiments provided herein, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices, or units, or can be an electrical, mechanical, or other form of connection.

[0155] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the embodiments herein.

[0156] In addition, the functional units in the various embodiments herein may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0157] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this article is essentially or the part that contributes to the existing technology, or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of this article. The aforementioned storage medium includes: various media that can store program code, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0158] This article uses specific embodiments to illustrate the principles and implementation methods of this article. The description of the above embodiments is only used to help understand the methods and core ideas of this article. At the same time, for those skilled in the art, based on the ideas of this article, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation to this article.

Claims

1. A double-dot-product seismic imaging method for elastic wave stress tensors, characterized in that: include: Based on the first-order velocity-stress equation of elastic isotropic media, the medium model parameters, source wavelet function and multi-component seismic records are used as input. The staggered grid high-order finite difference method is used to solve the first-order velocity-stress equation, and the source stress tensor wavefield and the detector particle vibration velocity vector wavefield are obtained. Using the detection particle vibration velocity vector wave field, a decoupled wave equation is constructed to obtain a decoupled detection longitudinal wave particle vibration velocity vector wave field and a decoupled detection shear wave vibration velocity vector wave field; A decoupled pseudo-stress equation is constructed using the decoupled detection longitudinal wave particle vibration velocity vector wave field and the decoupled detection shear wave vibration velocity vector wave field to obtain a decoupled pseudo-stress tensor wave field; Applying a double dot product cross-correlation imaging condition to the source stress tensor wavefield and the detection decoupled pseudo stress tensor wavefield to obtain a pseudo PP scalar imaging result and a pseudo PS scalar imaging result, and using the pseudo PP scalar imaging result and the pseudo PS scalar imaging result as elastic wave stress tensor double dot product seismic imaging results; The decoupling detection of the longitudinal wave particle vibration velocity vector wave field and the decoupling detection of the shear wave vibration velocity vector wave field are used to construct a decoupling pseudo stress equation to obtain the detection decoupling pseudo stress tensor wave field, further comprising: The decoupled pseudo-stress equation includes a longitudinal wave pseudo-stress equation and a transverse wave pseudo-stress equation, wherein the longitudinal wave pseudo-stress equation is: in, represents the longitudinal wave pseudo stress; The shear wave pseudo stress equation is: in, represents shear wave pseudo stress; The decoupling detection longitudinal wave particle vibration velocity vector wave field Decoupling detection of shear wave particle vibration velocity vector wave field Substitute them into the longitudinal wave pseudo stress equation and the shear wave pseudo stress equation respectively to obtain the detection decoupled pseudo stress tensor wave field Rcv, wherein the detection decoupled pseudo stress tensor wave field includes the detection longitudinal wave decoupled pseudo stress tensor wave field Decoupling pseudo-stress tensor wave field from detected shear waves λ and μ represent the Lame parameters, and x and z denote the x and z directions of the two-dimensional Cartesian coordinate system, respectively.

2. The method according to claim 1, characterized in that The first-order velocity-stress equation of the elastic isotropic medium is: Among them, (τ xx ,τ zz ,τ xz ) represents the source stress tensor wave field, (v x ,v z ) represents the vibration velocity vector wave field of the detection particle, λ and μ represent Lame parameters, ρ represents density, t represents time, and x and z represent the x and z directions of a two-dimensional Cartesian coordinate system, respectively; The grid points of the staggered grid are defined as (1:v x ; 2: τ xx ,τ zz ; 3: τ xz ;4:v z ), where 1, 2, 3, and 4 are four different spatial positions in the cells of the staggered grid.

3. The method according to claim 2, characterized in that Based on the first-order velocity-stress equation of elastic isotropic medium, the medium model parameters, source wavelet function and multi-component seismic records are used as input, and the staggered grid high-order finite difference method is used to solve the first-order velocity-stress equation of elastic isotropic medium to obtain the source stress tensor wave field and the detector particle vibration velocity vector wave field. Based on the grid point definition, the staggered grid high-order finite difference method is used to discretize the first-order velocity-stress equation of the elastic isotropic medium, and the discretization format is obtained as follows: Wherein, Δt represents the time interval, i and k represent the discrete points in the x and z directions in the two-dimensional Cartesian coordinate system, n represents the discrete points in the time t direction, and ρ -1 represents the density ρ to the power of -1, F s (s=x,z) and B s (s=x,z) are the forward difference operator and the backward difference operator in the x and z directions respectively. The specific expressions are: Among them, Δx and Δz represent the sampling intervals in the x and z directions, and f i,k represents the wave field quantity acted by the differential operator, i and k represent the discrete points used to determine the spatial position of the wave field quantity, represents the finite difference coefficients of the staggered grid of order 2M, where 2M represents the difference order and M represents a positive integer; Using the discrete format, according to the given medium model parameters, the Lamé parameters λ and μ, and the density ρ are obtained; The longitudinal wave source in the form of Ricker wavelet loaded in the continuation process of the source wave field is loaded on the (τ xx ,τ zz ), the earthquake source stress tensor wave field (τ xx ,τ zz ,τ xz ); The multi-component seismic record of the detection wave field in the continuation process is loaded onto the vibration velocity vector wave field (v x ,v z ), calculate and obtain the vibration velocity vector wave field (v x ,v z ).

4. The method according to claim 3, characterized in that The decoupled wave equation is constructed by using the detection particle vibration velocity vector wave field to obtain the decoupled detection longitudinal wave particle vibration velocity vector wave field and the detection shear wave vibration velocity vector wave field, further comprising: The decoupled wave equation is, Among them, τ P represents the auxiliary longitudinal wave stress; The decoupling detection longitudinal wave particle vibration velocity vector wave field is: in, Represents the longitudinal wave particle vibration velocity vector wave field; The decoupling detection shear wave vibration velocity vector wave field is: in, Represents the shear wave particle vibration velocity vector wave field.

5. The method according to claim 4, characterized in that Applying a double dot product cross-correlation imaging condition to the source stress tensor wavefield and the detection decoupled pseudo stress tensor wavefield to obtain a pseudo PP scalar imaging result and a pseudo PS scalar imaging result further includes: The source stress tensor wave field Src=(τ xx ,τ zz ,τ xz ) and the detection decoupling pseudo stress tensor wave field Rcv apply double dot product cross-correlation imaging conditions: The pseudo PP scalar imaging result and the pseudo PS scalar imaging result are obtained by calculation, wherein I qPP is the pseudo-PP scalar imaging result, I qPS is the pseudo-PS scalar imaging result, x represents the spatial position, t represents the time; Src and Rcv are the corresponding component forms of the source stress tensor wavefield Src and the detection decoupled pseudo stress tensor wavefield, respectively.

6. An elastic wave stress tensor double dot product seismic imaging device, characterized in that: include: A first-order velocity-stress equation solving unit is used to solve the first-order velocity-stress equation of the elastic isotropic medium based on the medium model parameters, the source wavelet function and the multi-component seismic record by using the staggered grid high-order finite difference method to obtain the source stress tensor wave field and the detector particle vibration velocity vector wave field; a decoupled wave equation solving unit, configured to construct a decoupled wave equation using the detection particle vibration velocity vector wave field to obtain a decoupled detection longitudinal wave particle vibration velocity vector wave field and a decoupled detection shear wave vibration velocity vector wave field; a decoupled pseudo-stress equation solving unit, configured to construct a decoupled pseudo-stress equation using the decoupled detection longitudinal wave particle vibration velocity vector wave field and the decoupled detection shear wave vibration velocity vector wave field to obtain a decoupled pseudo-stress tensor wave field; an imaging result calculation unit, configured to apply a double dot product cross-correlation imaging condition to the source stress tensor wavefield and the detection decoupled pseudo stress tensor wavefield to obtain a pseudo PP scalar imaging result and a pseudo PS scalar imaging result, and use the pseudo PP scalar imaging result and the pseudo PS scalar imaging result as elastic wave stress tensor double dot product seismic imaging results; The decoupling detection of the longitudinal wave particle vibration velocity vector wave field and the decoupling detection of the shear wave vibration velocity vector wave field are used to construct a decoupling pseudo stress equation to obtain the detection decoupling pseudo stress tensor wave field, further comprising: The decoupled pseudo-stress equation includes a longitudinal wave pseudo-stress equation and a transverse wave pseudo-stress equation, wherein the longitudinal wave pseudo-stress equation is: in, represents the longitudinal wave pseudo stress; The shear wave pseudo stress equation is: in, represents shear wave pseudo stress; The decoupling detection longitudinal wave particle vibration velocity vector wave field Decoupling detection of shear wave particle vibration velocity vector wave field Substitute them into the longitudinal wave pseudo stress equation and the shear wave pseudo stress equation respectively to obtain the detection decoupled pseudo stress tensor wave field Rcv, wherein the detection decoupled pseudo stress tensor wave field includes the detection longitudinal wave decoupled pseudo stress tensor wave field Decoupling pseudo-stress tensor wave field from detected shear waves λ and μ represent the Lame parameters, and x and z denote the x and z directions of the two-dimensional Cartesian coordinate system, respectively.

7. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the method according to any one of claims 1 to 5 is implemented.

8. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 5 is implemented.

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