Absorbing boundary condition method suitable for reverse time migration
A technology of absorbing boundary conditions and reverse time migration, applied in seismic signal processing and other directions, can solve problems such as difficult implementation, low computational efficiency, and inability to deal with incident wave reflection problems well, to eliminate reflection problems and ensure Computational Efficiency, Effect of Eliminating RTM Imaging Noise Problems
Active Publication Date: 2015-01-14
BC P INC CHINA NAT PETROLEUM CORP +1
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Problems solved by technology
The disadvantage of this type of method is that it cannot deal well with the reflection of incident waves with large incident angles.
Berenger (1994) designed an effective absorbing boundary condition, that is, the best matching layer (PML), but its disadvantage is that the calculation amount is relatively large, and the reverse time migration (RTM) itself is a calculation amount huge process
The calculation efficiency of this method is not high, the absorption effect is not good, and it is not easy to implement
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[0026] On the basis of the absorbing boundary conditions given by Higdon (1986, 1987), the present invention develops an absorbing boundary condition method suitable for reverse time migration (RTM), which has high calculation efficiency, good absorption effect and is easy to implement , which is well suited for reverse time migration (RTM).
[0027] The specific implementation mode of the present invention is:
[0028] 1) Acquire seismic data and complete pre-stack processing and depth domain modeling.
[0029] 2) Carry out the shot point finite difference wave field simulation, the second order difference along the time direction, at each time t, for the four horizontal directions of the calculation area, add n layers of calculation layers respectively; at the same time, for each calculation layer, loop Using the first-order mixed difference approximate absorbing boundary condition formula based on the Higdon method to calculate and update the wave fields U1, U2, U3.
[00...
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The invention relates to an absorbing boundary condition method suitable for reverse time migration. After pre-stacking and depth domain modeling, shotpoint wave field simulation is carried out, according to the second order difference in the time direction, n calculation layers are added to each time t in the four horizontal directions of a calculation domain; cycle calculation is carried out on each calculation layer through an Higdon method, and the wave field is updated; a second order hybrid difference approximation absorption boundary condition formula is used for calculation in the top surface and bottom surface directions of the calculation domain, and demodulator probe wave field simulation is carried out through the same steps; cross-correlation calculation is carried out on the shotpoint wave field and the demodulator probe wave field through cross-correlation imaging to obtain a shot migration result, seismic data migration calculation of all shots is finished, and a section is formed by overlapping. The absorbing boundary condition method suitable for reverse time migration can effectively process reflection of incident waves with a large incident angle and effectively eliminate imaging noise caused by false reflection under the condition of not increasing too much calculation, and is high in calculation efficiency, good in absorption effect and easy to implement.
Description
technical field [0001] The invention relates to a seismic wave migration imaging technology in reflection wave seismic data processing, in particular to an absorption boundary condition method for seismic wave reverse time migration (RTM) imaging. Background technique [0002] Reverse Time Migration (RTM) can well solve the imaging problems in areas with rapid velocity changes and extremely complex structures. At present, this technology has become the focus of migration imaging methods in the main international seismic detection market, and it is also the focus of various It is a characteristic technology for complex structure imaging developed by Geophysical Corporation. Reverse Time Migration (RTM) is based on the full-acoustic equation and has no restriction on the imaging inclination angle. It can effectively image rotary waves, prism waves, amplitude sea surface reflections (Ghosts), and multiple waves, and is suitable for anisotropic migration. It is very important t...
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Inventor 吴晓丰戴南浔武威刘磊
Owner BC P INC CHINA NAT PETROLEUM CORP