Study Of The Amplitude-preserving Converted-wave Pre-stack Time Imaging By Pseudo-offset Migration

In converted-wave exploration technology, converted-wave migration imagingtechnology has become an important research topic in recent years. In migration methods,post-stack migration is limited too much by the geological conditions and pre-stack depthmigration requires velocity models whose precision are too high. But pre-stack timemigration can give us the true common reflection point gathers and data after migration hashigh signal to noise ratio and can achieve amplitude-preserving migration. So, pre-stack timemigration is getting more and more attention. With the development of AVO, amplitudefidelity becomes more and more important while migrating．Pre-stack migration withamplitude-preserving not only images the construct correctly but also provides more usefulinformation for AVO analysis．So the converted-wave pre-stack migration with amplitudepreserving based on pseudo-offset migration(POM) presented in this article has its importantmeanings．This thesis has realized two kinds of converted wave pre-stack time migration methodsby pseudo-offset on the base of the fundamental theory of it, which are conventionalmigration and amplitude-preserving migration, and compares the two methods and theirinfluence factors. This paper mainly studies the converted wave pre-stack migration withamplitude preserving, summarizes different forms of weight functions of amplitudepreserving and introduces the specific form of the common offset gathers weight function ofconverted wave amplitude preserving migration. The converted wave amplitude preservingwas achieved in imaging POM gathers and avoid accumulating same time points．Based onthe pseudo-offset migration, the author has compiled two programs to extract gathers. And bymeans of kirchhoff stack method, this paper simplifies the traditional process of convertedwave pre-stack time part migration and realizes the converted-wave pre-stack time migration.Afterwards, this paper uses some models, which are upheaval model, faults group model anda lenticle etc to test the two different methods and contrasts the two methods’ migrationimaging effect. It shows that the converted wave amplitude preserving pre-stack migration method based on POM has achieved amplitude compensation and its results have certainadvantages. The results can be used in isotropic medium of converted-wave pre-stack timemigration, also for laying a certain foundation for further research of complex mediumpre-stack migration and depth migration.