Removing false images in reverse time migration: The concept of de-primary

Fei, Tong W.; Luo, Yi; Yang, Jiarui; Liu, Hongwei; Qin, Fuhao

doi:10.1190/geo2015-0289.1

Cited by 124 publications

(43 citation statements)

References 12 publications

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“…A critical component of the DOWFI scheme is the wavefield decomposition methodology using analytic wavefields to significantly reduce the low frequency artefacts (Fei et al . ; Hu et al . ).…”

Section: Directional‐oriented Wavefield Imagingmentioning

confidence: 99%

“…; Fei et al . ), as follows:

{\overset{U}{true}}_{a} false(t, x, y, k_{z} false) = \{\begin{matrix} U^{+} (t, x, y, k_{z}), k_{z} \geq 0 \\ U^{-} (t, x, y, k_{z}), k_{z} < 0 \end{matrix}\},

where the superscripts + and – mean down‐going and up‐going wavefields, respectively. However, there is a computational overhead in this methodology, due to the fact that the Hilbert transform requires a Fourier transform with its shifting phase component at ±90°.…”

Section: Directional‐oriented Wavefield Imagingmentioning

confidence: 99%

“…To solve this issue, we employ the wavefield decomposition using analytic signals for the source and receiver extrapolated wavefields (Fei et al . ; Hu, Wang and Wang ). Next, from the decomposed wavefields, we compute the propagation vector directions required to estimate subsurface azimuth and reflection angles for each depth point and for each imaging time step by employing the optical flow methodology.…”

Section: Introductionmentioning

confidence: 99%

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Directional‐oriented wavefield imaging: a new wave‐based subsurface illumination imaging condition for reverse time migration

Kim

Tsingas

Jeong

2018

Geophysical Prospecting

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The key objective of an imaging algorithm is to produce accurate and high‐resolution images of the subsurface geology. However, significant wavefield distortions occur due to wave propagation through complex structures and irregular acquisition geometries causing uneven wavefield illumination at the target. Therefore, conventional imaging conditions are unable to correctly compensate for variable illumination effects. We propose a generalised wave‐based imaging condition, which incorporates a weighting function based on energy illumination at each subsurface reflection and azimuth angles. Our proposed imaging kernel, named as the directional‐oriented wavefield imaging, compensates for illumination effects produced by possible surface obstructions during acquisition, sparse geometries employed in the field, and complex velocity models. An integral part of the directional‐oriented wavefield imaging condition is a methodology for applying down‐going/up‐going wavefield decomposition to both source and receiver extrapolated wavefields. This type of wavefield decomposition eliminates low‐frequency artefacts and scattering noise caused by the two‐way wave equation and can facilitate the robust estimation for energy fluxes of wavefields required for the seismic illumination analysis. Then, based on the estimation of the respective wavefield propagation vectors and associated directions, we evaluate the illumination energy for each subsurface location as a function of image depth point and subsurface azimuth and reflection angles. Thus, the final directional‐oriented wavefield imaging kernel is a cross‐correlation of the decomposed source and receiver wavefields weighted by the illuminated energy estimated at each depth location. The application of the directional‐oriented wavefield imaging condition can be employed during the generation of both depth‐stacked images and azimuth–reflection angle‐domain common image gathers. Numerical examples using synthetic and real data demonstrate that the new imaging condition can properly image complex wave paths and produce high‐fidelity depth sections.

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Section: Directional‐oriented Wavefield Imagingmentioning

confidence: 99%

“…; Fei et al . ), as follows:

{\overset{U}{true}}_{a} false(t, x, y, k_{z} false) = \{\begin{matrix} U^{+} (t, x, y, k_{z}), k_{z} \geq 0 \\ U^{-} (t, x, y, k_{z}), k_{z} < 0 \end{matrix}\},

Section: Directional‐oriented Wavefield Imagingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Directional‐oriented wavefield imaging: a new wave‐based subsurface illumination imaging condition for reverse time migration

Kim

Tsingas

Jeong

2018

Geophysical Prospecting

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show abstract

“…; Fei et al . ). Both methods can be used to eliminate low‐frequency noise by abnegating the imaging components of wave‐fields with the same propagation direction.…”

Section: Introductionmentioning

confidence: 97%

Imaging artefacts of artificial diving waves in reverse time migration: cause analysis in the angle domain and an effective removal strategy

Liu

Yan

et al. 2019

Geophysical Prospecting

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In areas with strong velocity gradients, traditional reverse time migration based on cross‐correlation imaging condition not only produces low‐frequency noise but also generates diving wave artefacts. The artefacts caused by diving waves have no typical low‐frequency characteristics and cannot be eliminated by simple high‐pass filtering approaches. We apply the wave‐field decomposition imaging condition to analyse the causes of false images in reverse time migration by decomposing the full wave‐field into up‐going and down‐going components in the angle domain. We find that artificial diving wave imaging artefacts, which are generated by the cross‐correlation between the up‐going source and down‐going receiver wave‐fields in areas with strong velocity gradients, arise at large angles. We propose an efficient strategy by means of the wavelength‐dependent smoothing operator to eliminate artefacts from artificial diving waves in reverse time migration. Specifically, the proposed method provides more reasonable down‐going wave‐fields in areas with sharp velocity constructs by considering the factor of varying seismic wavelengths during wave propagation, and the artificial components of diving waves are eliminated in a straightforward manner. Meanwhile, the other wave‐field components that contribute to true subsurface images are minimally affected. Benefiting from a smoothed velocity, the proposed method can be adapted to the traditional reverse time migration imaging frame, which reveals significant implementation potential for the seismic exploration industry. A salt model is designed and included to demonstrate the effectiveness of our approach.

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“…Here, the the total field is decomposed into upgoing and downgoing parts (Fei et al, 2015), and we only correlate upgoing source fields with the backpropagated reflections to get the rabbit-ear portion of the gradient. However, we now compute the tomographic gradients with both the FWI and the MPI methods.…”

Section: Appendix B: Reflection Mpimentioning

confidence: 99%

Multiscale phase inversion of seismic data

Guo

Schuster

2018

GEOPHYSICS

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We present a scheme for multiscale phase inversion (MPI) of seismic data that is less sensitive than full-waveform inversion (FWI) to the unmodeled physics of wave propagation and to a poor starting model. To avoid cycle skipping, the multiscale strategy temporally integrates the traces several times, i.e., high-order integration, to produce low-boost seismograms that are used as input data for the initial iterations of MPI. As the iterations proceed, lower frequencies in the data are boosted by using integrated traces of lower order as the input data. The input data are also filtered into different narrow frequency bands for the MPI implementation. Numerical results with synthetic acoustic data indicate that, for the Marmousi model, MPI is more robust than conventional multiscale FWI when the initial model is moderately far from the true model. Results from synthetic viscoacoustic and elastic data indicate that MPI is less sensitive than FWI to some of the unmodeled physics. Inversion of marine data indicates that MPI is more robust and produces modestly more accurate results than FWI for this data set.

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Removing false images in reverse time migration: The concept of de-primary

Cited by 124 publications

References 12 publications

Directional‐oriented wavefield imaging: a new wave‐based subsurface illumination imaging condition for reverse time migration

Directional‐oriented wavefield imaging: a new wave‐based subsurface illumination imaging condition for reverse time migration

Imaging artefacts of artificial diving waves in reverse time migration: cause analysis in the angle domain and an effective removal strategy

Multiscale phase inversion of seismic data

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