Kirchh off型真振幅偏移与反偏移
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摘要
对Kirchhoff型真振幅偏移和反偏移理论中的基本概念、基本假设和基本公式进行了简要的回顾和综合评述 ,并探讨了在今后发展中所面临的问题。从研究问题的出发点来看 ,已发表的真振幅成像理论与波动方程没有直接的关系。在数学上 ,加权绕射叠加和等时线叠加的表达方式具有多样性 ,真振幅加权函数具有多解性 ,这为真振幅偏移和反偏移的实现提供了多个途径。如果速度模型过于复杂 ,已发表的真振幅加权函数将在波场的焦散区失效。因此 ,在今后的研究中要探讨焦散区的加权函数计算问题。此外 ,要找寻最佳偏移孔径的快速估算方法 ,建立相应的预处理体系 ,并将现有的标量理论推广到矢量波场和各向异性介质。
I briefly review the basic concepts and assumptions as well as the basic equations in Kirchhoff-type migration and demigration. It is found that the starting point of the true-amplitude imaging theory has no direct relation to the wave equation, and that both of the diffraction- and the isochrone-stack can be formulated in different forms. Further, the true-amplitude weight function has no unique solution. This gives a possibility to implement the true-amplitude imaging in different ways. If the macro-velocity model is too complicated, the published weight functions become invalid in caustic regions. Therefore, a key point for further research is to find the weight function valid in caustic points. Furthermore, it is necessary to find a method for fast estimation of the optimal aperture, and to extend the present theory from scalar wave-field to the vector one, and from the isotropic media to the anisotropic media.
I briefly review the basic concepts and assumptions as well as the basic equations in Kirchhoff-type migration and demigration. It is found that the starting point of the true-amplitude imaging theory has no direct relation to the wave equation, and that both of the diffraction- and the isochrone-stack can be formulated in different forms. Further, the true-amplitude weight function has no unique solution. This gives a possibility to implement the true-amplitude imaging in different ways. If the macro-velocity model is too complicated, the published weight functions become invalid in caustic regions. Therefore, a key point for further research is to find the weight function valid in caustic points. Furthermore, it is necessary to find a method for fast estimation of the optimal aperture, and to extend the present theory from scalar wave-field to the vector one, and from the isotropic media to the anisotropic media.
引文
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7 孙建国.论三维等时线叠加反偏移中的有关问题.吉林大学学报(地球科学版),2002,32(2):273～278
8 SunJ,GajewskiD .True amplitudecommon shotmigra tionrevisited.Geophysics,1997,62(5):1250～1259
2 SunJ.Onthelimitedaperturemigrationintwodimen sions.Geophysics,1998,63(4):984～994
3 SchleicherJ ,TygelM ,HubralP .3Dtrue amplitudefi nite offsetmigration.Geophysics,1993,58(4):1112～1126
4 HubralP ,SchleicherJ ,TygelM .Aunifiedapproachto3Dseismicreflectionimaging.PartI:Basicconcepts.Geophysics,1996,61(3):742～758
5 TygelM ,SchleicherJ ,HubralP .Aunifiedapproachto3Dseismicreflectionimaging.PartII :Theory.Geophysics,1996,61(3):759～775
6 SunJ.Ontheapertureeffectin3DKirchhoff typemigra tion.GeophysicalProspecting,1999,47(6):1045～1076
7 孙建国.论三维等时线叠加反偏移中的有关问题.吉林大学学报(地球科学版),2002,32(2):273～278
8 SunJ,GajewskiD .True amplitudecommon shotmigra tionrevisited.Geophysics,1997,62(5):1250～1259
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