Local Angle-Domain Ray Tracing and Prestack Depth Migration in TI Medium
详细信息
- 责任者：Duan Pengfei (School of Ocean and Earth Science ; Tongji University ; Shanghai 200092 ; China) ; Cheng Jiubing
- 刊名：Chinese Journal of Geophysics
- 出版年：2013
- 卷期：56(1)
- 关键词：射线追踪 ; ray tracing ; 叠前深度偏移 ; prestack depth migration
- 页码：p.269-279
- 图表：illus., 1 table, 18 refs.
- 分类号：1600
- issnNo：ISSN0001-5733
- isbnNo：CN11-2074/P
摘要
Neglecting anisotropy in seismic imaging may result in remarkable positional errors and focusing problem,especially for long-offset and wide-azimuth seismic data.To meet the demands of seismic imaging and anisotropic velocity analysis in laterally heterogeneous transversely isotropic(TI) media,we present an angle-domain imaging approach for prestack depth migration based on two advanced anisotropic ray tracing algorithms.It not only outputs migrated section and offset-domain common image gathers,but also obtains incident angles domain and illumination angles domain imaging results according to the local angular characteristics at a subsurface image point based on extended superposition of the impulse responses.In order to efficiently calculate traveltimes and local angular attributes in TI medium,we discuss and compare two improved ray tracing systems.One is based on phase velocity,which is evolved from the classic ray tracing equation of anisotropic media.Another system is derived from qP wave equation with acoustic approximation for VTI medium,and is extended to tackle TTI medium through coordinate rotation.Numerical examples on the standard theoretical anisotropic models show that our approach can be used as imaging tool for complex geological structures and efficient migration engine for anisotropic migration velocity analysis and model building.