Interactive Seismic Imaging by Fast Beam Migration文档.pdfVIP

C017 Interactive Seismic Imaging by Fast Beam Migration F. Gao* (CGGVeritas), P. Zhang (CGGVeritas), B. Wang (CGGVeritas), G. Thomas-Collignon (CGGVeritas) V. Dirks (CGGVeritas) SUMMARY This paper presents a Fast Beam migration algorithm which has been specifically designed to facilitate very rapid migration turnarounds to allow for interactive velocity model building and validation. The very fast imaging turnaround is achieved by only migrating pre-picked events in a wavelet by wavelet fashion. Coherent noise and migration artifacts are reduced compared to classical Kirchhoff migration techniques by using a sophisticated event selection scheme during the event picking phase and by subsequent multi-path migration, where focusing errors are used to further reduce migration noise. The multi-path concept of the algorithm is borrowed from the Gaussian beam migration technique. Tests on the 2D Sigsbee synthetic dataset demonstrate the superior subsalt imaging capabilities of the algorithm compared to Kirchhoff migrations and resulted in a total migration speed-up of a factor of 30. Images for 3D real data compare favorably with those from Kirchhoff migrations but can be produced with a speed of two orders of magnitude higher than by classical imaging schemes. With the achieved image turnaround improvements the Fast Beam migration is opening the door to real 3D interactive velocity model building and model validations particularly in areas of high structural complexity and model uncertainty. th EAGE 69 Conference Exhibition — London, UK, 11 - 14 June 2007 Introduction It is well known that subsalt seismic imaging is a challenge which arises from the fact that signals containing subsalt information are usually weak, and subsalt illumination is generally poor and non-uniform. More often than not is the identification of salt base problematic. Poor subsalt images make subsalt seismic