1887
Volume 67, Issue 5
  • E-ISSN: 1365-2478

Abstract

ABSTRACT

With the progress in computational power and seismic acquisition, elastic reverse time migration is becoming increasingly feasible and helpful in characterizing the physical properties of subsurface structures. To achieve high‐resolution seismic imaging using elastic reverse time migration, it is necessary to separate the compressional (P‐wave) and shear (S‐wave) waves for both isotropic and anisotropic media. In elastic isotropic media, the conventional method for wave‐mode separation is to use the divergence and curl operators. However, in anisotropic media, the polarization direction of P waves is not exactly parallel to the direction of wave propagation. Also, the polarization direction of S‐waves is not totally perpendicular to the direction of wave propagation. For this reason, the conventional divergence and curl operators show poor performance in anisotropic media. Moreover, conventional methods only perform well in the space domain of regular grids, and they are not suitable for elastic numerical simulation algorithms based on non‐regular grids. Besides, these methods distort the original wavefield by taking spatial derivatives. In this case, a new anisotropic wave‐mode separation scheme is developed using Poynting vectors. This scheme can be performed in the angle domain by constructing the relationship between group and polarization angles of different wave modes. Also, it is performed pointwise, independent of adjacent space points, suitable for parallel computing. Moreover, there is no need to correct the changes in phase and amplitude caused by the derivative operators. By using this scheme, the anisotropic elastic reverse time migration is more efficiently performed on the unstructured mesh. The effectiveness of our scheme is verified by several numerical examples.

Loading

Article metrics loading...

/content/journals/10.1111/1365-2478.12777
2019-04-02
2020-02-18
Loading full text...

Full text loading...

References

  1. AkiK. and RichardsP.1980. Quantitative Seismology, Theory and Methods. New York, NY: W.H. Freeman and Co.
    [Google Scholar]
  2. AlkhalifahT.1998. Acoustic approximations for processing in transversely isotropic media. Geophysics63, 623–631.
    [Google Scholar]
  3. AlkhalifahT.2003. Tau migration and velocity analysis: theory and synthetic examples. Geophysics68, 1331–1339.
    [Google Scholar]
  4. BerrymanJ. G.1979. Longwave elastic anisotropy in transversely isotropic media. Geophysics44, 896–917.
    [Google Scholar]
  5. CervenyČervenýV.2000. Seismic Ray Method. Cambridge University Press.
    [Google Scholar]
  6. ChangW. F. and McMechanG.A.1987. Elastic reverse‐time migration. Geophysics52, 243–256.
    [Google Scholar]
  7. ChangW. F. and McMechanG.A.1994. 3‐d elastic prestack, reverse‐time depth migration. Geophysics59, 597–609.
    [Google Scholar]
  8. ChengJ., AlkhalifahT., WuZ., ZouP. and WangC.2016. Simulating propagation of decoupled elastic waves using low‐rank approximate mixed‐domain integral operators for anisotropic media. Geophysics81, T63–T77.
    [Google Scholar]
  9. ChengJ. and FomelS.2014. Fast algorithms for elastic‐wave‐mode separation and vector decomposition using low‐rank approximation for anisotropic media. Geophysics79, C97–C110.
    [Google Scholar]
  10. DellingerJ. and EtgenJ.1990. Wavefield separation in twodimensional anisotropic media. Geophysics55, 914.
    [Google Scholar]
  11. DickensT.A. and WinbowG.A.2011. Rtm angle gathers using poynting vectors. SEG Technical Program, Expanded Abstracts, 3109–3113.
  12. DuQ., GuoC.F., ZhaoQ., GongX., WangC. and LiX.Y.2017. Vector‐based elastic reverse time migration based on scalar imaging condition. Geophysics82, S111–S127.
    [Google Scholar]
  13. DuQ., ZhuY. and BaJ.2012. Polarity reversal correction for elastic reverse time migration. Geophysics77, 31.
    [Google Scholar]
  14. DuanY. and SavaP.2015. Scalar imaging condition for elastic reverse time migration. Geophysics80, S127–S136.
    [Google Scholar]
  15. GaoH. and ZhangJ.2010. Parallel 3‐d simulation of seismic wave propagation in heterogeneous anisotropic media: a grid method approach. Geophysical Journal International165, 875–888.
    [Google Scholar]
  16. KomatitschD. and VilotteJ.P.1998. The spectral element method: an efficient tool to simulate the seismic response of 2d and 3d geological structures. Bulletin of the Seismological Society of America88, 368–392.
    [Google Scholar]
  17. LiuQ., ZhangJ. and ZhangH.2016. Eliminating the redundant source effects from the cross‐correlation reverse‐time migration using a modified stabilized division. Computers & geosciences, 92, 49–57.
    [Google Scholar]
  18. LiuQ., PeterD. and LuY.2017a. A fast pointwise strategy for anisotropic wave‐mode separation in ti media. SEG Technical Program, Expanded Abstracts, 447–451.
  19. LiuQ., ZhangJ. and GaoH.2017b. Reverse time migration from rugged topography using irregular, unstructured mesh. Geophysical Prospecting, 65, 453–466.
    [Google Scholar]
  20. LiuQ., ZhangJ., LuY., GaoH., LiuS. and ZhangH.2019. Fast Poynting‐Vector based wave‐mode separation and RTM in 2D elastic TI media. Journal of Computational Physics, 381, 27–41.
    [Google Scholar]
  21. LuY. and LiuQ.2018. Non‐overlapped p‐ and s‐wave Poynting vectors and their solution by the grid method. Journal of Geophysics and Engineering15, 788.
    [Google Scholar]
  22. McgarryR. and QinY.2013. Direction‐vector‐based angle gathers from anisotropic elastic rtm. SEG Technical Program, Expanded Abstracts, 3820–3824.
  23. OhJ. W., KalitaM. and AlkhalifahT.2018. 3d elastic full‐waveform inversion using p‐wave excitation amplitude: Application to ocean bottom cable field data. Geophysics83, R129–R140.
    [Google Scholar]
  24. SavaP. and AlkhalifahT.2013. Wide‐azimuth angle gathers for anisotropic wave‐equation migration. Geophysical Prospecting61, 75–91.
    [Google Scholar]
  25. TangH., HeB. and MouH.2016. P‐ and s‐wave energy flux density vectors. Geophysics81, T357–T368.
    [Google Scholar]
  26. ThomsenL.1986. Weak elastic anisotropy. Geophysics51, 1954–1957.
    [Google Scholar]
  27. TsvankinI.1996. P‐wave signatures and notation for transversely isotropic media: An overview. Geophysics61, 467–483.
    [Google Scholar]
  28. TsvankinI.2005. Seismic Signatures and Analysis of Reflection Data in Anisotropic Media, 2nd edn. Elsevier.
    [Google Scholar]
  29. WangM.X., YangH., OsenA. and YangD.H.2013. Full‐wave equation based illumination analysis by nad method. 75th Annual International Conference and Exhibition EAGE, Extended Abstracts.
  30. WangW. and McMechanG.A.2015. Vector‐based elastic reverse time migration. Geophysics80, S245–S258.
    [Google Scholar]
  31. XieX.B.2015. An angle‐domain wavenumber filter for multi‐scale full‐waveform inversion. SEG Technical Program, Expanded Abstracts, 1132–1137.
  32. YanJ. and DickensT.A.2016. Reverse time migration angle gathers using poynting vectors. Geophysics81, S511–S522.
    [Google Scholar]
  33. YanJ. and SavaP.2008. Isotropic angle‐domain elastic reverse‐time migration. Geophysics73, S229–S239.
    [Google Scholar]
  34. YanJ. and SavaP.2009. Elastic wave‐mode separation for vti media. Geophysics74, WB19–WB32.
    [Google Scholar]
  35. YanJ. and SavaP.2011. Improving the efficiency of elastic wave‐mode separation for heterogeneous tilted transverse isotropic media. Geophysics76, T65–T78.
    [Google Scholar]
  36. YangK., ZhangJ. and GaoH.2017. Unstructured mesh based elastic wave modelling on gpu: A double‐mesh grid method. Geophysical Journal International211, 741–750.
    [Google Scholar]
  37. YoonK., GuoM., CaiJ. and WangB.2011. 3d rtm angle gathers from source wave propagation direction and dip of reflector. SEG Technical Program, Expanded Abstracts, 3136–3140.
  38. YoonK. and MarfurtK.J.2006. Reverse‐time migration using the poynting vector. Exploration Geophysics59, 102–107.
    [Google Scholar]
  39. ZhangJ. and LiuT.1999. P‐sv‐wave propagation in heterogeneous media: grid method. Geophysical Journal International, 136, 431–438.
    [Google Scholar]
  40. ZhangJ. and LiuT.2010. Elastic wave modelling in 3d heterogeneous media: 3d grid method. Geophysical Journal International150, 780–799.
    [Google Scholar]
  41. ZhangQ. and McMechanG.A.2010. 2d and 3d elastic wavefield vector decomposition in the wavenumber domain for vti media. Geophysics75, D13–D26.
    [Google Scholar]
  42. ZhouY. and WangH.2017. Efficient wave‐mode separation in vertical transversely isotropic media. Geophysics80, C35–C47.
    [Google Scholar]
http://instance.metastore.ingenta.com/content/journals/10.1111/1365-2478.12777
Loading
/content/journals/10.1111/1365-2478.12777
Loading

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