Azimuthal velocity models are now widely used for land seismic exploration. In particular, Horizontal Transverse Isotropy (HTI) models have often been applied as the anisotropic velocity model of choice, to extract velocity information from situations where the earth consists of horizontally fractured media. The velocities extracted can be used both to perform azimuthally dependent move-out to flatten the CMP gathers, providing a sharper and clearer stack, and also to generate the interval velocity models via generalized Dix inversion, which are a powerful tool for interpreters when dealing with fractured earth models. However, HTI velocity models are known to be insufficient as a modelling tool in certain circumstances, particularly in surveys where large offsets are present, resulting in incidence angles of over 30 degrees where higher order terms in the move-out equation start to become significant. This study therefore implements an orthorhombic velocity model as an extension to the standard HTI model, where azimuthally dependent higher order move-out is present in the move-out equation. The method of solution of the orthorhombic model is described, together with an application to a Full-Azimuth high density Independent Simultaneous Shooting (ISS®) survey as an illustration.


Article metrics loading...

Loading full text...

Full text loading...


  1. Alkhalifah, T. and Tsvankin, I.
    [1995] Velocity analysis for transversely isotropic media. Geophysics, 60, 1550–1566.
    [Google Scholar]
  2. Contreras, P., Grechka, V. and Tsvankin, I.
    [1999] Moveout inversion of P-wave data for horizontal transverse isotropy. Geophysics, 64, 1219–1229.
    [Google Scholar]
  3. Davison, C., Ratcliffe, A., Grion, S., Johnston, R., Duque, C., Neep, J. and Maharramov, M.
    [2011] Azimuthal velocity uncertainty: estimation and application. SEG Expanded Abstracts.
    [Google Scholar]
  4. Grechka, V., Tsvankin, I. and Cohen, J.K.
    [1999] Generalized Dix equation and analytic treatment of normal-moveout velocity for anisotropic media. Geophysical Prospecting, 47, 117–148.
    [Google Scholar]
  5. Siliqi, R. and Bousquie, N.
    [2000] Anelliptic time processing based on a shifted hyperbola approach. SEG Expanded Abstracts.
    [Google Scholar]
  6. Tarantola, A.
    [1987] Inverse Problem Theory. Elsevier.
    [Google Scholar]
  7. Todorovic-Marinic, D., Mattocks, B., Bale, R., Dewar, D. and Roche, S.
    [2005] More Powerful Fracture Detection: Integrating P-wave, Converted-wave, FMI and Everything. EAGE Expanded Abstracts.
    [Google Scholar]
  8. Tsvankin, I. and Grechka, V.
    [2011] Seismology of Azimuthally Anisotropic Media and Seismic Fracture Characterization. SEG Geophysical Reference Series, No. 17.
    [Google Scholar]
  9. ISS® is a registered trade mark of BP plc.

Data & Media loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error