| Finite-difference calculation of traveltimes based on rectangular grid |
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| 作者姓名： | 李振春 刘玉莲 张建磊 马在田 王华忠 |
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| 作者单位： | College of Earth Resources and Information，University of Petroleum，Dongying 257061，China，College of Earth Resources and Information，University of Petroleum，Dongying 257061，China，College of Earth Resources and Information，University of Petroleum，Dongying 257061，China，College of Marine and Earth Science，Tongji University，Shanghai 200092，China，College of Marine and Earth Science，Tongji University，Shanghai 200092，China |
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| 基金项目： | National Natural Science Foundation of China (49894190-024) and Geophysical Prospecting Key Laboratory Foun-
dation of China National Petroleum Corporation. |
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| 摘 要： | Introduction The calculation of seismic wave traveltimes is a basic and the most important step in tomo-graphy, seismic wave forward modeling and Kirchhoff prestack depth migration. Limitations withtraditional ray tracing fall into four categories. a) Analytical methods can only realize ray tracingfor simply varying velocity fields, so they have relative small applied-range; b) Shooting methodsof ray tracing can cause shadow zones. When the shadow zones exist the method will invalid; c)…
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| 收稿时间： | 25 March 2003 |
| 修稿时间： | 1 April 2004 |
Finite-difference calculation of traveltimes based on rectangular grid |
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| Li Zhen-chun , Liu Yu-lian , Zhang Jian-lei , Ma Zai-tian and Wang Hua-zhong.Finite-difference calculation of traveltimes based on rectangular grid[J].Acta Seismologica Sinica(English Edition),2004,17(6):707-714. |
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| Authors: | Li Zhen-chun Liu Yu-lian Zhang Jian-lei Ma Zai-tian and Wang Hua-zhong |
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| Institution: | 1. College of Earth Resources and Information, University of Petroleum, Dongying 257061, China
2. College of Marine and Earth Science, Tongji University, Shanghai 200092, China |
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| Abstract: | To the most of velocity fields, the traveltimes of the first break that seismic waves propagate along rays can be computed
on a 2-D or 3-D numerical grid by finite-difference extrapolation. Under ensuring accuracy, to improve calculating efficiency
and adaptability, the calculation method of first-arrival traveltime of finite-difference is derived based on any rectangular
grid and a local plane wavefront approximation. In addition, head waves and scattering waves are properly treated and shadow
and caustic zones cannot be encountered, which appear in traditional ray-tracing. The testes of two simple models and the
complex Marmousi model show that the method has higher accuracy and adaptability to complex structure with strong vertical
and lateral velocity variation, and Kirchhoff prestack depth migration based on this method can basically achieve the position
imaging effects of wave equation prestack depth migration in major structures and targets. Because of not taking account of
the later arrivals energy, the effect of its amplitude preservation is worse than that by wave equation method, but its computing
efficiency is higher than that by total Green’s function method and wave equation method.
Foundation item: National Natural Science Foundation of China (49894190-024) and Geophysical Prospecting Key Laboratory Foundation of China
National Petroleum Corporation. |
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| Keywords: | finite-difference eikonal equation first-arrival traveltime rectangular grid Kirchhoff prestack depth migration Marmousi model |
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