Finite‐element reverse‐time migration for elastic waves

Teng, Yu-Chiung; Dai, Ting-fan; Kuo, John T.

doi:10.1190/1.1892988

Cited by 4 publications

(4 citation statements)

References 5 publications

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“…Without P-and S-wave separation, and calculation of their correct relative amplitudes, the results of crosscorrelations of the mixed wave types or ðx; y; zÞ components lack meaningful interpretations in terms of reflection coefficients (Teng et al, 1986;Chang and McMechan, 1987;Yan and Sava, 2007). Vector magnitudes and directions of P-and S-waves are directly obtained from the vector wavefields after P-and S-vector separations.…”

Section: Full Wavefield Storage and Crosscorrelationmentioning

confidence: 99%

“…The implementations and applications described above are acoustic. Elastic RTM has already been studied (Teng et al, 1986;Chang and McMechan, 1987;Cunha Filho, 1992;Sun et al, 2006;Lu et al, 2010;Xiao and Leaney, 2010;Anderson et al, 2012;Jiao et al, 2012;Yan and Xie, 2012;Luo et al, 2013). These studies have generally omitted, or used approximate, P-S wave separations, amplitude and phase corrections, and S-polarity correction, and do not deal with storage issues.…”

Section: Introductionmentioning

confidence: 99%

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Five ways to avoid storing source wavefield snapshots in 2D elastic prestack reverse time migration

2015

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Five alternative algorithms were evaluated to circumvent the excessive storage requirement imposed by saving source wavefield snapshots used for the crosscorrelation image condition in 2D prestack elastic reverse time migration. We compared the algorithms on the basis of their ability, either to accurately reconstruct (not save) the source wavefield or to use an alternate image condition so that neither saving nor reconstruction of full wavefields was involved. The comparisons were facilitated by using the same (velocity-stress) extrapolator in all the algorithms, and running them all on the same hardware. We assumed that there was enough memory in a node to do an extrapolation, and that all input data were stored on disk rather than residing in randomaccess memory. This should provide a fair and balanced comparison. Reconstruction of the source wavefield from boundary and/or initial values reduced the required storage to a very small fraction of that needed to store source wavefield snapshots for conventional crosscorrelation, at the cost of adding an additional source extrapolation. Reverse time checkpointing avoided recursive forward recomputation. Two nonreconstructive imaging conditions do not require full snapshot storage or an additional extrapolation. Timebinning the imaging criteria removed the need for image time searching or sorting. Numerical examples using elastic data from the Marmousi2 model showed that the quality of the elastic prestack PP and PS images produced by the cost-optimized alternative algorithms were (virtually) identical to the higher cost images produced by traditional crosscorrelation.

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Section: Full Wavefield Storage and Crosscorrelationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Five ways to avoid storing source wavefield snapshots in 2D elastic prestack reverse time migration

2015

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“…Extrapolation of the recorded wavefield for reverse-time migration may be carried out with any desired extrapolator that steps in time. Ray-tracing , finite-differences (Chang and McMechan 1986), and finite elements (Teng, Dai and Kuo 1986) have all been previously used in 2D, and are directly extendable to 3D. We use 3D acoustic finite-differences (Chang and McMechan 1989a, b).…”

Section: Reverse-time Extrapolation Of the Recorded Wavefield In 3mentioning

confidence: 99%

3D ACOUSTIC PRESTACK REVERSE‐TIME MIGRATION¹

Chang

McMechan

1990

Geophysical Prospecting

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CHANG, W.F. and MCMECHAN, G. A. 1990. 3D acoustic prestack reverse-time migration. Geophysical Prospecting 38,737-755.A prestack reverse-time migration algorithm which operates on common-source gathers, recorded at the Earth's surface, from 3D structures, is conceived, implemented and tested. Reverse-time extrapolation of the recorded wavefield (a boundary-value problem), and computation of the excitation-time imaging condition for each point in a 3D volume (an initialvalue problem), are both performed using a second-order finite-difference solution of the full 3D scalar wave equation. The algorithm is illustrated by processing synthetic data for a point diffractor, an oblique wedge, and the French double dome and fault model.

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“…The corresponding problem in exploration seismology, which is the imaging of reflectors (treated as secondary sources), in elastic media has recently been the object of considerable research (cf. Marfurt 1978;Kuo & Dai 1984;Teng et al, Sun & McMechan 1986;Chang & McMechan 1987). By applying the key ideas from these papers, with small modifications, we produce images of the primary (earthquake) source rather than the secondary (structure) sources.…”

Section: Introductionmentioning

confidence: 99%

Elastic Finite-Difference Modelling and Imaging for Earthquake Sources

McMechan

1988

Geophysical Journal International

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Summary 2‐D modelling and imaging of line double‐couple and spatially extended earthquake sources is demonstrated. Extrapolation of two‐component (elastic) wavefields is implemented using finite differences. Running the extrapolatioin forward in time produces synthetic seismograms; running it backward in time produces an image of the source. Provided that the recording aperture is adequate, the source location, extent, orientation and radiation pattern may be recovered from the data. Synthetic examples include a normal fault at the edge of a rift, a reverse fault in a subduction zone and a line double couple in a cylindrical, whole‐earth model.

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Finite‐element reverse‐time migration for elastic waves

Cited by 4 publications

References 5 publications

Five ways to avoid storing source wavefield snapshots in 2D elastic prestack reverse time migration

Five ways to avoid storing source wavefield snapshots in 2D elastic prestack reverse time migration

3D ACOUSTIC PRESTACK REVERSE‐TIME MIGRATION¹

Elastic Finite-Difference Modelling and Imaging for Earthquake Sources

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Finite‐element reverse‐time migration for elastic waves

Cited by 4 publications

References 5 publications

Five ways to avoid storing source wavefield snapshots in 2D elastic prestack reverse time migration

Five ways to avoid storing source wavefield snapshots in 2D elastic prestack reverse time migration

3D ACOUSTIC PRESTACK REVERSE‐TIME MIGRATION1

Elastic Finite-Difference Modelling and Imaging for Earthquake Sources

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3D ACOUSTIC PRESTACK REVERSE‐TIME MIGRATION¹