1887
Volume 52, Issue 6
  • ISSN: 0812-3985
  • E-ISSN: 1834-7533

Abstract

Time migration is an important tool to provide a subsurface image because it is faster and less sensitive to velocity errors than depth migration. However, a reliable and focused time migration image is achievable only with well-determined time-migration velocities. As an alternative of prestack time migration, equivalent offset migration (EOM) provides intermediate common scatterpoint (CSP) gathers that have higher fold and larger offset range than common midpoint (CMP) gathers, which enables precise focusing of the velocity semblance and accurate velocity analysis. However, direct implementation of EOM might introduce coherent mapping noise, which smears the velocity spectra and decreases the resolution of the final stacked image. We reformulate the EOM as a linear operator that maps CMP gathers to CSP gathers and then propose least-squares equivalent offset migration (LS-EOM) method that inverts for optimal CSP gathers by minimising the misfit between simulated and observed CMP gathers. Compared with the EOM method, LS-EOM provides noise-free CSP gathers, leading to better focusing of the velocity semblance and higher resolution of the final stacked image. Both synthetic and field data tests demonstrate the effectiveness of our proposed method.

© 2021 Australian Society of Exploration Geophysicists
Loading

Article metrics loading...

/content/journals/10.1080/08123985.2021.1872348
2021-11-02
2026-01-12

  • From This Site

    /content/journals/10.1080/08123985.2021.1872348
    dcterms_title,dcterms_subject,pub_keyword
    -contentType:Journal -contentType:Contributor -contentType:Concept -contentType:Institution
    10
    5
Loading full text...

Full text loading...

References

  1. Al-Yahya, K.M.1989. Velocity analysis by iterative profile migration. Geophysics54, no. 6: 718–29. doi:10.1190/1.1892389.
     https://doi.org/10.1190/1.1892389 [Google Scholar]
  2. Asakawa, E., and J.McIntyre. 2015. The application of equivalent offset migration (EOM) to vertical cable seismic (VCS) data. SEG Technical Program Expanded Abstracts34: 5560–4. doi:10.1190/segam2015‑5897444.1.
     https://doi.org/10.1190/segam2015-5897444.1 [Google Scholar]
  3. Bancroft, J.C., and H.D.Geiger. 1997. Anatomy of common scatterpoint (CSP) gathers formed during equivalent offset prestack migration (EOM). Energy9, no. 2: 1–10.
     [Google Scholar]
  4. Bancroft, J.C., H.D.Geiger, and G.F.Margrave. 1998. The equivalent offset method of prestack time migration. Geophysics63, no. 6: 2042–53. doi:10.1190/1.1444497.
     https://doi.org/10.1190/1.1444497 [Google Scholar]
  5. Bancroft, J.C., and S.Wang. 1994. Converted-wave prestaek migration and velocity analysis by equivalent offsets and CCP gathers. CREWES Research Report 6: 28-1–28-7.
  6. Berryhill, J.R.1996. System and method of seismic shot-record migration. Google Patents.
  7. Beydoun, W.B., and M.Mendes. 1989. Elastic ray-Born L2-migration/inversion. Geophysical Journal International97: 151–60.
     [Google Scholar]
  8. Bleistein, N.2012. Mathematical methods for wave phenomena. Academic Press.
  9. Burnett, W.A., and R.J.Ferguson. 2011. A reversible transform for seismic data processing. Journal of Geophysics and Engineering8, no. 3: 477–86. doi:10.1088/1742‑2132/8/3/008.
     https://doi.org/10.1088/1742-2132/8/3/008 [Google Scholar]
  10. Claerbout, J.F.1992. Earth soundings analysis: Processing versus inversion. London: Blackwell Scientific Publications.
  11. Dell, S., D.Gajewski, and C.Vanelle. 2012. Prestack time migration by common-migrated-reflector-element stacking. Geophysics77, no. 3: S73–82. doi:10.1190/geo2011‑0200.1.
     https://doi.org/10.1190/geo2011-0200.1 [Google Scholar]
  12. Fomel, S.2014. Recent advances in time-domain seismic imaging. SEG Technical Program Expanded Abstracts33: 4400–4. doi:10.1190/segam2014‑1461.1.
     https://doi.org/10.1190/segam2014-1461.1 [Google Scholar]
  13. Fomel, S., P.C.Sava, I.Vlad, Y.Liu, and V.Bashkardin. 2013. Madagascar: Open-source software project for multidimensional data analysis and reproducible computational experiments. Journal of Open Research Software1, no. 1.
     [Google Scholar]
  14. Fowler, P.J.1997. A comparative overview of prestack time migration methods. 66th Ann. Internal. Mtg., Soc. Expl. Geophys., Expanded Abstracts, 1571–74.
  15. Gardner, G.H.F., S.Y.Wang, N.D.Pan, and Z.Zhang. 1986. Dip moveout and prestack imaging. 18th Annual Offshore Technology Conference. 75–84.
     [Google Scholar]
  16. Lambaré, G.1992. Iterative asymptotic inversion in the acoustic approximation. Geophysics57, no. 9: 1138. doi:10.1190/1.1443328.
     https://doi.org/10.1190/1.1443328 [Google Scholar]
  17. LeBras, R.1988. An iterative inversion of back-scattered acoustic waves. Geophysics53, no. 4: 501. doi:10.1190/1.1442481.
     https://doi.org/10.1190/1.1442481 [Google Scholar]
  18. Li, X.1999. Residual statics analysis using prestack equivalent offset migration. PhD thesis, University of Calgary. doi:10.1515/abcsb‑2015‑0026
     https://doi.org/10.1515/abcsb-2015-0026 [Google Scholar]
  19. Li, X., and J.C.Bancroft. 1997. Residual statics analysis before NMO using prestack migration. In 59th EAGE Conference & Exhibition, Session:A032.A032. European Association of Geoscientists & Engineers.
  20. Liu, Y., and Z.Li. 2015. Least-squares reverse-time migration with extended imaging condition. Chinese Journal of Geophysics (in Chinese)58, no. 10: 3771–82.
     [Google Scholar]
  21. Liu, Y., Z.Li, D.Wu, J.Huang, and X.Wei. 2013. The research on local slope constrained least-squares migration. Chinese Journal of Geophysics (in Chinese)56, no. 3: 1003–11.
     [Google Scholar]
  22. Nemeth, T., C.Wu, and G.T.Schuster. 1999. Least-squares migration of incomplete reflection data. Geophysics64, no. 1: 208. doi:10.1190/1.1444517.
     https://doi.org/10.1190/1.1444517 [Google Scholar]
  23. Ottolini, R.A.1982. Migration of reflection seismic data in anglemidpoint coordinates. Stanford Exploration Project Research Report, 33 Stanford University.
  24. Schneider, W.A.1978. Integral formulation for migration in two and three dimensions. Geophysics43, no. 1: 49–76. doi:10.1190/1.1440828.
     https://doi.org/10.1190/1.1440828 [Google Scholar]
  25. Xu, J., and J.Zhang. 2017. Prestack time migration of nonplanar data: Improving topography prestack time migration with dip-angle domain stationary-phase filtering and effective velocity inversion. Geophysics82, no. 3: S235–46. doi:10.1190/GEO2016‑0087.1.
     https://doi.org/10.1190/GEO2016-0087.1 [Google Scholar]
  26. Yilmaz, Ö.2001. Seismic data analysis: Processing, inversion, and interpretation of seismic data. Society of Exploration Geophysicists.
/content/journals/10.1080/08123985.2021.1872348
Loading
Improving prestack time migration by least-squares equivalent offset method
Exploration Geophysics 52, 633 (2021); https://doi.org/10.1080/08123985.2021.1872348
/content/journals/10.1080/08123985.2021.1872348
/content/journals/10.1080/08123985.2021.1872348
Loading

Data & Media loading...

  • Article Type: Research Article
Keyword(s): high-resolution; least-squares; Time migration; velocity

Most Cited This Month Most Cited RSS feed

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