Prestack wave-equation migration as a routine production tool

Pharez, Stephen; Jones, N.; Dirks, Volker; Zimine, S.; Prigent, H.; Ibbotson, Keith; Gruffeille, J.-P.

doi:10.1190/1.1946216

Cited by 4 publications

(1 citation statement)

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“…Four strong scatterers are clearly visible in the image. We note that the Kirchhoff migration fails to image them properly due to multipathing and ray-tracing problems through the salt body (e.g., Pharez et al 2005). However, diffraction events along a fault plane are not imaged because they are weak and need more accurate threshold in our separation procedure.…”

Section: E X a M P L E Smentioning

confidence: 99%

Poststack diffraction imaging using reverse-time migration

Silvestrov

Baina²,

Landa

2015

Geophysical Prospecting

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A B S T R A C TWe propose a method for imaging small-scale diffraction objects in complex environments in which Kirchhoff-based approaches may fail. The proposed method is based on a separation between the specular reflection and diffraction components of the total wavefield in the migrated surface angle domain. Reverse-time migration was utilized to produce the common image gathers. This approach provides stable and robust results in cases of complex velocity models. The separation is based on the fact that, in surface angle common image gathers, reflection events are focused at positions that correspond to the apparent dip angle of the reflectors, whereas diffracted events are distributed over a wide range of angles. The high-resolution radon-based procedure is used to efficiently separate the reflection and diffraction wavefields. In this study, we consider poststack diffraction imaging. The advantages of working in the poststack domain are its numerical efficiency and the reduced computational time. The numerical results show that the proposed method is able to image diffraction objects in complex environments. The application of the method to a real seismic dataset illustrates the capability of the approach to extract diffractions.

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Section: E X a M P L E Smentioning

confidence: 99%

Poststack diffraction imaging using reverse-time migration

Silvestrov

Baina²,

Landa

2015

Geophysical Prospecting

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References

2007

Handbook of Geophysical Exploration: Seismic Exploration

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Improving explicit seismic depth migration with a stabilizing Wiener filter and spatial resampling

et al. 2006

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We present a new approach to the design and implementation of explicit wavefield extrapolation for seismic depth migration in the space-frequency domain. Instability of the wavefield extrapolation operator is addressed by splitting the operator into two parts, one to control phase accuracy and a second to improve stability. The first partial operator is simply a windowed version of the exact operator for a half step. The second partial operator is designed, using the Wiener filter method, as a band-limited, least-squares inverse of the first. The final wavefield extrapolation operator for a full step is formed as a convolution of the first partial operator with the complex conjugate of the second. This resulting wavefield extrapolation operator can be designed to have any desired length and is generally more stable and more accurate than a simple windowed operator of similar length. Additional stability is gained by reducing the amount of evanescent filtering and by spatially downsampling the lower temporal frequencies. The amount of evanescent filtering is controlled by building two operator tables, one corresponding to significant evanescent filtering and the other to very little evanescent filtering. During the wavefield extrapolation process, most steps are taken with the second table while the first is invoked only for roughly every tenth step. Also, the data are divided into frequency partitions that are optimally resampled in the spatial coordinates to further enhance the performance of the extrapolation operator. Lower frequencies are downsampled to a larger spatial sample size. Testing of the algorithm shows accurate, high-angle impulse responses and run times comparable to the phase shift method of time migration. Images from trial depth migrations of the Marmousi model show very high resolution.

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Prestack wave-equation migration as a routine production tool

Cited by 4 publications

References 0 publications

Poststack diffraction imaging using reverse-time migration

Poststack diffraction imaging using reverse-time migration

References

Improving explicit seismic depth migration with a stabilizing Wiener filter and spatial resampling

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