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Imaging Complex Structures With First-arrival Traveltimes
| Content Provider | Semantic Scholar |
|---|---|
| Author | Bevc, Dimitri |
| Copyright Year | 1995 |
| Abstract | I present a layer-stripping Kirchhoff migration algorithm which is capable of obtaining accurate images of complex structures by downward continuing the data and imaging from a lower datum. I use eikonal traveltimes in a Kirchhoff datuming algorithm for the downward continuation. After downward continuation, I perform Kirchhoff migration. The method alternates steps of datuming and imaging. Because traveltimes are computed for each step, the adverse effects of caustics, headwaves, and multiple arrivals do not develop. In principal, this method only requires the same number of traveltime calculations as a standard migration. Tests on the Marmousi data set produce excellent results. INTRODUCTION Kirchhoff migration is generally accepted to be the most efficient method of imaging 2-D and 3-D prestack seismic data. The Marmousi synthetic data set (Versteeg, 1994) has been a popular testbed for migration algorithms and many researchers have discovered that Kirchhoff algorithms using first-arrival traveltimes do a poor job of imaging the target zone (Audebert et al., 1994; Gray and May, 1994; Geoltrain and Brac, 1993). Even methods which calculate most energetic arrivals and estimate amplitude and phase do not always result in images which compare favorably with finite-difference shot-profile migration. In their 1993 Geophysics article, Geoltrain and Brac ask the question “Can we image complex structures with first-arrival traveltime?” They conclude that they cannot, and that they should either ray trace to find the most energetic arrivals, or calculate multiple-arrival Green’s functions. Nichols (1994) calculates band-limited Green’s functions to estimate the most energetic arrivals. He estimates not only traveltime, but also amplitude and phase. My approach is simpler; by breaking up the complex velocity structure, I am able to calculate traveltimes in velocity models where finite-differencing the eikonal equation is valid. This results in images comparable to those obtained by Nichols’ method and by shot-profile migration at a reduced computational cost. e-mail: dimitri@sep.stanford.edu |
| File Format | PDF HTM / HTML |
| DOI | 10.1190/1.1887320 |
| Alternate Webpage(s) | http://sepwww.stanford.edu/public/docs/sep84/dimitri1.pdf |
| Alternate Webpage(s) | http://www.reproducibility.org/RSF/book/sep/fat/paper.pdf |
| Alternate Webpage(s) | http://sepwww.stanford.edu/data/media/public/docs/sep84/dimitri1.pdf |
| Alternate Webpage(s) | https://doi.org/10.1190/1.1887320 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
