WO2016008100A1

WO2016008100A1 - Three-dimensional seismic anisotropic medium reverse time migration imaging method and device

Info

Publication number: WO2016008100A1
Application number: PCT/CN2014/082257
Authority: WO
Inventors: 杨顺伟
Original assignee: 杨顺伟
Priority date: 2014-07-15
Filing date: 2014-07-15
Publication date: 2016-01-21
Also published as: CN104937440A

Abstract

A three-dimensional seismic anisotropic medium reverse time migration imaging method and device, used in the technical field of reflected wave seismic data processing, the method comprising: determining all shots requiring reverse time migration imaging (S11); performing the following steps for each shot (S12): placing a sub-wave at a shot point position corresponding to the shot, and conducting shot point wave field simulation on the shot by using a coupling second-order partial differential equation (S121); conducting wave detection point wave field simulation on the shot by applying the coupling second-order partial differential equation to shot data corresponding to the shot (S122); and imaging the result of the shot point wave field simulation and the result of the wave detection point wave field simulation by using a mutual correlation imaging condition so as to obtain a single-shot reverse time migration result of the shot (S123); after performing the above steps on all shots, superimposing the single-shot reverse time migration results of all the shots to form a reverse time migration imaging profile (S13). The present invention employs a stable coupling second-order partial differential equation to realize differential solving of a wave equation, thus solving the problem of inconsistent calculation caused by the change of the symmetrical axis inclination angle of a TTI medium, and finally solving the problem of rapid changes in the imaging of a three-dimensional complex structure.

Description

Three-dimensional seismic anisotropic medium reverse time migration imaging method and device

Technical field

The present invention relates to the field of reflected wave seismic data processing technology, and in particular to a method and apparatus for inverse time migration imaging of a three-dimensional seismic anisotropic medium. Background technique

Seismic anisotropy of the Earth's medium has proven to be ubiquitous, but seismic exploration often considers the Earth's approximation as an isotropic medium. In the past, this approximation simplifies the problems and formulas of seismic processing interpretation, but in the pursuit of fine reservoir exploration today, some seismic media are neglected (such as thin interbedded sandstone reservoir media, layered shale media, carbonates). The anisotropy of cracks in the rock - karst reservoir media and igneous reservoir media developed by the fracture may cause large errors in seismic interpretation, and one of the errors in seismic data processing is partial Dislocation resulting from the displacement of the fault. Therefore, it is quite necessary and urgent to study anisotropic seismic exploration techniques.

In addition, the prior art has a problem of computational instability at the abrupt position of the symmetry axis inclination parameter profile, resulting in an abnormal value in the calculation, so that the calculation error exits. Summary of the invention

The main object of the embodiments of the present invention is to provide a three-dimensional seismic anisotropic medium reverse time migration imaging method and device, which can solve the mutation position of the symmetry axis inclination parameter profile in the prior art when performing the shot wave field simulation. There is a problem of computational instability.

In order to achieve the above object, an embodiment of the present invention provides a three-dimensional seismic anisotropic medium reverse time migration imaging method, including:

Identify all guns that require reverse time migration imaging;

For each shot, perform the following processing steps:

The wavelet is placed at the corresponding shot position of the gun, and the second-order partial differential equation is used to simulate the shot wave field; the coupled second-order partial differential equation is applied to the corresponding gun data of the gun, The gun performs the wave field simulation of the detection point; the cross-correlation imaging condition is used to image the result of the wave field simulation of the shot point and the result of the wave field simulation of the detection point, and the single shot reverse time migration result of the gun is obtained;

After performing the above processing steps for all the shots, the single shot reverse time offset results of all the shots are superimposed to form a reverse time offset imaging profile;

Wherein the coupled second-order partial differential equation is:

O ¹ -(l + 2S)H ₂ p + H _iq -— H ₂ (pq)

, ' - - a

Η _Λ - sin ² ^cos ² φ ~ - + sin ² ^sin ² φ ~ - + cos ² Θ

¹ dx ² dy ² sin ² Θ sin 2φ h sin 2Θ sin φ h sin 2Θ cos φ

Dxdy dydz dxdz

Η _Ί =—― H ― H — H,

² dx ¹ dy ¹ dz ^{1 In} the equation, δ and ε are respectively Thomson anisotropic parameters corresponding to the imaging space;

θ and φ are the symmetry axis inclination angle parameters and the symmetry axis azimuth angle parameters corresponding to the imaging space, respectively.

The invention also provides a three-dimensional seismic anisotropic medium reverse time migration imaging device, comprising:

a gun determination module for determining all guns that require reverse time migration imaging;

The single shot processing module is used to perform the following processing steps for each shot:

The wavelet is placed at the corresponding shot position of the gun, and the coupled second-order partial differential equation is used to simulate the shot wave field; the corresponding gun data is obtained, and the coupled second-order partial differential equation is applied to detect the wave field Simulation; applying the cross-correlation imaging condition to image the result of the shot wave field simulation and the result of the wave field simulation of the detection point, and obtain a single shot reverse time migration result of the shot;

a superimposed imaging module, configured to perform the above processing steps on all the shots, and stack the single shot reverse time offset results of all the shots to form a reverse time offset imaging profile;

Wherein the coupled second-order partial differential equation is:

¹ -(l + 2s)H ₂ p + H _l q + ^-H _l (pq)

, ' - - a

_{2 2} d ² 2 2 d ² 2 d ²

Hj = sin ^cos φ ~ - + sin ^sin φ ~ - + cos Θ- dx dy ² dz ² sin ² Θ sin 2φ h sin 2Θ sin φ h sin 2 cos - dxdy dydz dxdz

H ₇ =—― ― ― Η —— Η _λ

Ox oy dz In the equation, S and s are the Thomson anisotropic parameters corresponding to the imaging space;

θ is the symmetry axis inclination parameter and the symmetry axis azimuth parameter corresponding to the imaging space, respectively. By means of the above technical solution, the invention adopts a stable coupled second-order partial differential equation to realize the differential solution of the wave equation, can solve the computational instability problem caused by the sudden change of the inclination axis of the medium symmetry, and finally solves the three-dimensional complex structure imaging with rapid change of speed. problem. The method of the invention has the advantages of high computational efficiency, good imaging effect, and easy realization, and is suitable for the development of reverse-time offset commercial software and industrial production. DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments will be briefly described below. It is obvious that the drawings in the following description are only the present invention. For some embodiments, other drawings may be obtained from those skilled in the art without any inventive labor.

1 is a schematic flow chart of a three-dimensional seismic anisotropic medium reverse time migration imaging method provided by the present invention;

2 is a simulated snapshot of a counter-offset shot point wave field in a seismic anisotropic medium region provided by the present invention; FIG. 3 is a snapshot of a shot point wave field provided by the present invention;

4 is a snapshot of a wave point of a detection point provided by the present invention;

Figure 5 is a single shot reverse time shifting result provided by the present invention;

6 is a reverse time migration imaging result of a seismic anisotropic medium region provided by the present invention;

7 is a reverse time migration imaging result of the negligible anisotropy tilt angle parameter provided by the present invention;

Figure 8 is an isotropic reverse time migration imaging result ignoring all anisotropic parameters provided by the present invention;

Figure 9 is a partial enlarged view of Figure 6;

Figure 10 is a partial enlarged view of Figure 7;

Figure 11 is a partial enlarged view of Figure 8;

Figure 12 is a result of superimposing the result of the reverse time shift and the velocity model provided by the present invention;

13 is a schematic structural view of a three-dimensional seismic anisotropic medium reverse time migration imaging apparatus provided by the present invention;

FIG. 14 is a schematic flow chart of a three-dimensional seismic anisotropic medium reverse time migration imaging method according to an embodiment of the present invention. detailed description

The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

In the process of implementing the present invention, the inventors discovered that:

The finite difference migration method based on the full acoustic equation (also called the reverse time migration method, or the RTM method) passes in time - The spatial domain directly solves the full acoustic partial differential equation by displaying the high-order finite difference algorithm, and truly simulates the wave propagation phenomenon. The method is completed - 1 3⁄4 2 full compliance with the wave equation, there is no inclination limit, it can be applied to the sharp change of the velocity field, has obvious advantages in three-dimensional complex structure imaging, and has high imaging precision. Since the reverse time migration algorithm directly simulates the propagation of seismic waves in the space-time domain, it is easier to apply to the imaging problems in complexly varying vertical transversely isotropic and oblique transverse isotropic isotropic media.

When there is an anisotropic feature in the subsurface medium, the propagation mode of the seismic wave in the subsurface medium is different. Based on the above findings, the present invention provides a three-dimensional seismic anisotropic medium reverse time migration imaging method, as shown in FIG. The method includes: Step S11, determining all the guns that need to perform reverse time migration imaging;

In step S12, for each shot, the following processing steps are performed:

Step S121, placing a wavelet at a position corresponding to the shot, and applying a second-order partial differential equation to simulate the shot wave field of the shot;

Step S122, applying the coupled second-order partial differential equation to the gun data corresponding to the gun, and performing a detection point wave field simulation on the gun;

Step S123, applying a cross-correlation imaging condition to image the result of the shot wave field simulation and the result of the wave field simulation of the detection point, and obtain a single shot reverse time migration result of the shot;

Step S13, after performing the above processing steps on all the shots, superimposing the single shot reverse time offset results of all the shots to form a reverse time offset imaging profile;

Wherein the coupled second-order partial differential equation is:

_F — 3

-(l + 2s)H ₂ p + H _l q + ^—H _l (pq)

σ

O {, \ + 25)H ₂ p + H _i , _q -"-H ₂ (pq)

1 σ

, _{2 2} d ² _{2 2} d ² ₂ d ²

H = sin ^cos φ ~ - + sin ^sin φ ~ - + cos Θ ~ - +

¹ dx ² dy ² dz ²

Q ² Q ² Q ²

Sin ² Θ sin 2φ h sin 2Θ sin φ h sin Ιθοο^ - dxdy dydz dxdz

H ₂ = Η Η ― H!

Dx dy dz In the equation, p is the coupled wave field, x, y, z are the spatial axis coordinates, which are the time axis coordinates, and δ and s are the Thomson anisotropic parameters corresponding to the imaging space;

The three-dimensional seismic anisotropic medium reverse time migration imaging method provided by the invention can solve the sudden change of the symmetry axis inclination angle Calculate the problem of instability. 2 is a simulation example of a reverse-phase offset shot point wave field and a symmetry axis tilt angle parameter of a seismic anisotropic medium region obtained by applying the present invention (9 superimposed display results, it can be seen that the symmetry axis tilt angle parameter (profile) There is a mutation on the right side. When the traditional equation is simulated, there is a problem of computational instability at the mutation position. However, the equation proposed by the present invention can solve the instability problem. As can be seen from Fig. 2, the seismic wave successfully passes the The location of the mutation, there is no computational instability problem.

FIG. 3 shows an example of a shot point snapshot of a shot obtained by applying the present invention.

FIG. 4 shows an example of a wave point snapshot of a detection point obtained by applying the present invention.

Fig. 5 is a view showing an example of a single shot reverse time shift result obtained by applying the present invention.

Fig. 6 is a graph showing the results of a reverse time migration imaging profile of a seismic anisotropic medium region obtained by applying the present invention. Figure 7-12 shows the results of reverse time migration imaging in an anisotropic medium. Figure 7 shows the inverse time migration result of ignoring the anisotropic dip parameter, and Figure 8 shows the isotropic reverse time migration result of ignoring all anisotropic parameters. By comparing Figure 6-8, the reverse-time migration imaging results are significantly better than the latter two results, especially the high-speed body boundary imaging is correct, while the latter two results have errors in the imaging of high-speed body boundaries, showing reverse time migration. The importance of imaging for complex structures. The above three results are magnified to obtain the results of Fig. 9-11. It can be seen that in the imaging of the high-speed body boundary, the reverse time migration is the clearest, especially the boundary with a large dip angle, and the isotropic reverse time. The result of the offset has a large error. Figure 12 shows the result of the reverse time migration and the velocity model. It can be seen that the result can reflect the true underground structure.

The invention adopts a stable coupled second-order partial differential equation to realize the differential solution of the wave equation, can solve the computational instability problem caused by the sudden change of the symmetry axis of the medium, and finally solves the three-dimensional complex structure imaging problem with sharply changing speed. The method of the present invention has the advantages of high computational efficiency, good imaging effect, and easy implementation, and is suitable for the development of reverse time offset commercial software and industrial production. Correspondingly, the present invention provides a three-dimensional seismic anisotropic medium reverse time migration imaging apparatus. As shown in FIG. 13, the apparatus includes:

A gun determination module 1401, configured to determine all guns that require reverse time migration imaging;

The single shot processing module 1402 is configured to perform the following processing steps for each shot:

The superimposed imaging module 1403 is configured to perform the foregoing processing steps on all the guns, and superimpose the results of the single shot reverse time offset of all the guns to form a reverse time migration imaging profile; Wherein the coupled second-order partial differential equation is:

1 d ² p ε - δ

(1 + 2ε) Η ₂ ρ + H _x q + H _x {p - q

σ

_{2 2} d ² 2 2 d ² J d

Hj = sin ^ cos φ ~ - + sin ^ sin φ ~ - + cos Θ- dx dy dz sin ² Θ sin 2φ h sin 2Θ sin φ h sin Ιθοο^ - dxdy dydz dxdz

H ₉ Η ― Η —— H

In the equation of ox oy oz, δ and ε are respectively Thomson anisotropic parameters corresponding to the imaging space;

θ and φ are the symmetry axis inclination angle parameters and the symmetry axis azimuth angle parameters corresponding to the imaging space, respectively. Example

The embodiment provides a specific embodiment of applying the inverse time migration imaging method of the three-dimensional seismic anisotropic medium of the present invention to the commercialization software. As shown in FIG. 14, the method specifically includes the following steps:

Step A, storing all the gun data locally, and the depth domain velocity field, the Thomson anisotropy parameter, the symmetry axis inclination parameter, and the symmetry axis azimuth parameter corresponding to the imaging space;

Step A2: determining a current gun to be processed from the task list, reading the gun data corresponding to the gun, and the depth field velocity field, the Thomson anisotropy parameter, the symmetry axis inclination parameter, and the symmetry axis azimuth parameter corresponding to the imaging space, And perform the following processing for the gun:

Step A21, placing a wavelet at a corresponding shot position of the gun, and applying a second-order partial differential equation to perform a shot wave field simulation (using the equation to make the calculation stable when the tilt of the symmetry axis is abrupt), the obtained shot point wave Field simulation results are stored locally;

Step A22, applying a second-order partial differential equation to the corresponding gun data of the gun, realizing the wave field simulation of the detection point, and storing the obtained detection result of the detection wave field locally;

Step A23, applying the cross-correlation imaging condition to image the simulation result of the shot wave field obtained in step A21 and the simulation result of the detection point wave obtained in step A22, and obtaining the single-shot reverse time migration result of the shot, and storing the result in the local;

Step A3, determining whether there are any unprocessed cannons in the task list, and if so, looping through step A2 (including steps A21 to A23); otherwise, executing step A4;

In step A4, the single-shot reverse time offset results of all the guns are superimposed to form a reverse-time migration imaging profile, and the result is output. In order to improve the processing speed of step A23 in this embodiment, when step A21 is performed, according to the set time interval The simulation results of the shot wave field are compressed step by step, and then the compression results corresponding to the respective time intervals are stored locally. Then, when step A23 is executed, the compression package of the simulation result of the shot wave field can be decompressed by the thread synchronization. Then, the cross-correlation imaging conditions are applied to image the simulated wave field simulation results and the detection point wave field simulation results. Due to the use of step-by-step compression and split-thread synchronous decompression, the speed of single-shot processing is improved, and the processing efficiency of the whole process is improved.

In summary, the three-dimensional TTI seismic anisotropic medium reverse time migration imaging method and apparatus provided by the embodiments of the present invention have the following beneficial effects:

(1) The stable coupled second-order partial differential equation is used to realize the differential solution of the wave equation, which can solve the computational instability caused by the sudden tilt angle variation of the TTI medium, and finally solve the three-dimensional complex structure imaging problem with sharply changing speed;

(2) It has the advantages of high computational efficiency, good imaging effect, and easy implementation, and is suitable for the development of reverse time migration (RTM) commercial software and the needs of industrial production.

The above described specific embodiments of the present invention are further described in detail, and are intended to be illustrative of the embodiments of the present invention. The scope of the protection, any modifications, equivalents, improvements, etc., made within the spirit and scope of the invention are intended to be included within the scope of the invention.

Claims

WO 2016/008100 +T7 c,i _μ- +, > PCT/CN2014/082257 Request

A method for inverse time migration imaging of a three-dimensional seismic anisotropic medium, comprising:

Identify all guns that require reverse time migration imaging;

For each shot, perform the following processing steps:

Wherein the coupled second-order partial differential equation is: H _i (p - _q )

O ¹ - (l + 2S) H ₂ p + H _iq - H ₂ (p - q)

, ' - - a

H, = sin ² O cos, ¹ φ ~ - + sin ² ^ sin ² φ ~ - + cos ² Θ

¹ dx ² dy ² sin ² Θ sin 2φ h sin 2Θ sin φ h sin 1£ c. s φ

Dxdy dydz dxdz

In the equation, δ and ε are respectively Thomson anisotropic parameters corresponding to the imaging space;

2. The method of claim 1 further comprising: compressing the shot field simulation results for the set time interval.

3. A three-dimensional seismic anisotropic medium reverse time migration imaging device, comprising:

Superimposed imaging module, after performing the above processing steps on all the guns, stacking the results of the single shots of all the guns Add up to form a reverse time migration imaging profile;

Wherein the coupled second-order partial differential equation is:

1 d ² p ε-δ

(ΐ + 2ε)Η ₂ ρ + Η^ + H^pq)

, ' - - a

_{2 2} d ² 2 2 d ² J d

Hj = sin ^cos φ ~ - + sin ^sin φ ~ - + cos Θ- dx ² dy ² dz sin ² Θ sin 2φ h sin 2Θ sin φ h sin Ιθοο^ - dxdy dydz dxdz

H ₉ Η ― Η —— H

In the equation of ox oy oz, δ and ε are the Thomson anisotropic parameters corresponding to the imaging space respectively; θ and φ are the symmetry axis inclination parameter and the symmetry axis azimuth parameter corresponding to the imaging space, respectively.

4. The device according to claim 3, further comprising:

A compression module is used to compress the simulation results of the shot point wave field at a set time interval.