1887
Volume 63, Issue 5
  • E-ISSN: 1365-2478

Abstract

ABSTRACT

Wavefield extrapolation operators for elliptically anisotropic media offer significant cost reduction compared with that for the transversely isotropic case, particularly when the axis of symmetry exhibits tilt (from the vertical). However, elliptical anisotropy does not provide accurate wavefield representation or imaging for transversely isotropic media. Therefore, we propose effective elliptically anisotropic models that correctly capture the kinematic behaviour of wavefields for transversely isotropic media. Specifically, we compute source‐dependent effective velocities for the elliptic medium using kinematic high‐frequency representation of the transversely isotropic wavefield. The effective model allows us to use cheaper elliptic wave extrapolation operators. Despite the fact that the effective models are obtained by matching kinematics using high‐frequency asymptotic, the resulting wavefield contains most of the critical wavefield components, including frequency dependency and caustics, if present, with reasonable accuracy. The methodology developed here offers a much better cost versus accuracy trade‐off for wavefield computations in transversely isotropic media, particularly for media of low to moderate complexity. In addition, the wavefield solution is free from shear‐wave artefacts as opposed to the conventional finite‐difference‐based transversely isotropic wave extrapolation scheme. We demonstrate these assertions through numerical tests on synthetic tilted transversely isotropic models.

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2015-03-23
2024-03-29
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References

  1. AlkhalifahT., MaX., WaheedU. and ZuberiM.2013. Efficient anisotropic wavefield extrapolation using effective isotropic models. 75th EAGE Conference & Exhibition incorporating SPE EUROPEC 2013, 10.3997/2214‐4609.20130359.
  2. AlkhalifahT.2000. An acoustic wave equation for anisotropic media. Geophysics65(4), 1239–1250.
    [Google Scholar]
  3. BaysalE., KosloffD.D. and SherwoodJ.W.1983. Reverse time migration. Geophysics48(11), 1514–1524.
    [Google Scholar]
  4. CrampinS.1984. An introduction to wave propagation in anisotropic media. Geophysical Journal International76(1), 17–28.
    [Google Scholar]
  5. EtgenJ.T.2006. How many angles do we really need for delayed‐shot migration. 68th EAGE Conference & Exhibition.
  6. FletcherR.P., DuX. and FowlerP.J.2009. Reverse time migration in tilted transversely isotropic (TTI) media. Geophysics74(6), WCA179–WCA187.
    [Google Scholar]
  7. GuanH., DussaudE., DenelB., WilliamsonP., et al. 2011. Techniques for an efficient implementation of RTM in TTI media. 2011 SEG annual meeting, Society of Exploration Geophysicists.
  8. HuangT., XuS., WangJ., IonescuG. and RichardsonM.2008. The benefit of TTI tomography for dual azimuth data in Gulf of Mexico. In: SEG Technical Program Expanded Abstracts 2008. Society of Exploration Geophysicists, 222–226.
  9. Ibanez‐JacomeW., AlkhalifahT. and WaheedU.2014. Effective orthorhombic anisotropic models for wavefield extrapolation. Geophysical Journal International198(3), 1653–1661.
    [Google Scholar]
  10. McMechanG.1983. Migration by extrapolation of time‐dependent boundary values. Geophysical Prospecting31(3), 413–420.
    [Google Scholar]
  11. ShahH.2007. The 2007 BP anisotropic velocity‐analysis benchmark. 70th EAGE annual meeting, workshop.
  12. StovasA. and AlkhalifahT.2012. A new traveltime approximation for TI media. Geophysics77(4), C37–C42.
    [Google Scholar]
  13. TsvankinI.1997. Moveout analysis for transversely isotropic media with a tilted symmetry axis. Geophysical Prospecting45(3), 479–512.
    [Google Scholar]
  14. VighD. and StarrE.W.2008. 3D prestack plane‐wave, full‐waveform inversion. Geophysics73(5), VE135–VE144.
    [Google Scholar]
  15. WaheedU. and AlkhalifahT.2014. Effective elliptic models for efficient wavefield extrapolation in anisotropic media. 76th EAGE Conference & Exhibition, 10.3997/2214‐4609.20140813.
  16. WaheedU., YarmanC. and FlaggG.2014. An iterative fast sweeping based eikonal solver for tilted orthorhombic media. In: SEG Technical Program Expanded Abstracts 2014. Society of Exploration Geophysicists, 10.1190/segam2014‐0846.1.
  17. WaheedU., AlkhalifahT. and StovasA.2013. Diffraction traveltime approximation for TI media with an inhomogeneous background. Geophysics78(5), WC103–WC111.
    [Google Scholar]
  18. WangH., WaheedU. and AlkhalifahT.2014. Effective anisotropy through traveltime and amplitude matching. In: SEG Technical Program Expanded Abstracts 2014. Society of Exploration Geophysicists, doi: 10.1190/segam2014-1183.1.
  19. XuS. and ZhouH.2014. Efficient and accurate algorithm for quasi‐P wave propagation. 76th EAGE Conference and Exhibition 2014.
  20. ZhangJ.H., ZhangG., ZhangY., et al. 2009. Removing S‐wave noise in TTI reverse time migration. 2009 SEG annual meeting, Society of Exploration Geophysicists.
  21. ZhangY., SunJ., NotforsC., GrayS.H., ChernisL. and YoungJ.2005. Delayed‐shot 3D depth migration. Geophysics70(5), E21–E28.
    [Google Scholar]
  22. ZhouH., PhamD., GrayS., WangB., et al. 2004. Tomographic velocity analysis in strongly anisotropic TTI media. 2004 SEG annual meeting, Society of Exploration Geophysicists.
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  • Article Type: Research Article
Keyword(s): Anisotropy; Modelling; Wave

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