3D Prestack Fourier Mixed-Domain (FMD) depth migration for VTI media with large lateral contrasts

• Published in: Journal of applied geophysics 2019-09, Vol.168, p.118-127
• Main Authors: Zhao, H., Gelius, L.-J., Tygel, M., Harris Nilsen, E., Kjelsrud Evensen, A.
• Format: Article
• Language: English
• Subjects: Anisotropic; Fourier mixed domain; PSDM; Seismic migration
• ISSN: 0926-9851; 1879-1859
• DOI: 10.1016/j.jappgeo.2019.06.009

Although many 3D One-Way Wave-equation Migration (OWEM) methods exist for VTI media, most of them struggle either with the stability, the anisotropic noise or the computational cost. In this paper we present a new method based on a mixed space- and wavenumber-propagator that overcome these issues very effectively as demonstrated by the examples. The pioneering methods of phase-shift (PS) and Stolt migration in the frequency-wavenumber domain designed for laterally homogeneous media have been followed by several extensions for laterally inhomogeneous media. Referred many times to as phase-screen or generalized phase-screen methods, such extensions include as main examples of the Split-step Fourier (SSF) and the phase-shift plus interpolation (PSPI). To further refine such phase-screen techniques, we introduce a higher-order extension to SSF valid for a 3D VTI medium with large lateral contrasts in vertical velocity and anisotropy parameters. The method is denoted Fourier Mixed-Domain (FMD) prestack depth migration and can be regarded as a stable explicit algorithm. The FMD technique was tested using the 3D SEG/EAGE salt model and the 2D anisotropic Hess model with good results. Finally, FMD was applied with success to a 3D field data set from the Barents Sea including anisotropy. •A new prestack depth migration technique for 2D and 3D vertical transverse isotropic (VTI) media.•An explicit one-way wave-equation operator implemented in Fourier Mixed-domain for 3D anisotropic prestack depth migration.•A higher-order version of the Split-Step Fourier method valid for complex 3D VTI media.•A stable explicit wavefield propagator avoiding the issues of anisotropic noise in 3D finite-difference implementations.