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Improvement of Migration Image for Ocean-bottom Seismic Data using Wavefield Separation and Mirror Imaging

파동장 분리와 미러 이미징을 이용한 해저면 탄성파 탐사 자료의 참반사 보정 영상 개선

  • Lee, Ganghoon (Department of Energy Resources Engineering, Inha University) ;
  • Pyun, Sukjoon (Department of Energy Resources Engineering, Inha University)
  • 이강훈 (인하대학교 에너지자원공학과) ;
  • 편석준 (인하대학교 에너지자원공학과)
  • Received : 2018.04.23
  • Accepted : 2018.05.24
  • Published : 2018.05.31

Abstract

Ocean-bottom seismic survey is a seismic acquisition technique which measures data by installing 4-component receiver on the sea floor. It can produce more improved data in quality than any other acquisition techniques. In the ocean-bottom seismic survey, however, the number of receivers is limited due to high cost. Since only a small number of receivers are used for acquisition, ocean-bottom seismic data may suffer from discontinuities of events over traces, which can result in spatial aliasing. In this paper, we implemented Kirchhoff migration using mirror-imaging algorithm to improve the quality of ocean-bottom seismic image. In order to implement the mirror imaging algorithm, the seismograms should be separated into up-going and down-going wavefields and the down-going wavefield should be used for migration. In this paper, we use the P-Z summation method to separate the wavefield. Numerical examples show that the migration results using mirror imaging algorithm have wider illumination than the conventional migration, especially in the shallow layers.

해저면 탄성파 탐사는 4성분 수신기를 해저면에 설치하여 자료를 측정하는 자료 취득 기법으로 기존의 탄성파 탐사 자료 취득 기법보다 향상된 품질의 자료를 얻을 수 있다. 그러나 해저면 탄성파 탐사는 자료 취득 비용이 매우 높아 사용할 수 있는 수신기의 개수가 제한된다는 단점이 있다. 자료 취득에 적은 수의 수신기만을 사용하기 때문에 해저면 탄성파 탐사로 취득한 자료는 트레이스 간의 연속성이 떨어지고, 이로 인해 공간 알리아싱 등의 문제가 발생할 수 있다. 본 연구에서는 수신기 개수가 적은 해저면 탄성파 자료의 영상 품질을 향상시키기 위해 미러 이미징(mirror imaging) 알고리즘을 사용해 키르히호프(Kirchhoff) 참반사 보정을 구현하였다. 미러 이미징 알고리즘을 적용하기 위해서는 상향/하향 파동장을 분리한 후 하향 파동장을 사용해야 하며, 본 연구에서는 P-Z summation 기법을 사용해 파동장을 분리하였다. 수치 예제를 통해 미러 이미징 알고리즘을 사용한 참반사 보정 결과가 전통적인 참반사 보정 결과보다 더 넓은 범위를 영상화 할 수 있음을 확인하였고, 특히 천부 지층에서 그 효과가 뚜렷함을 볼 수 있었다.

Acknowledgement

Grant : 유가스 부존특성 및 해저천부구조 정밀 규명을 위한 융복합 탐사기술 개발

Supported by : 한국지질자원연구원

References

  1. Aki, K., and Richards, P. G., 2002, Quantitative Seismology, Univ. Sci. Books.
  2. Alerini, M., Traub, B., Ravaut, C., and Duveneck, E., 2009, Prestack depth imaging of ocean-bottom node data, Geophysics, 74(6), WCA57-WCA63. https://doi.org/10.1190/1.3204767
  3. Bale, R., 1998, Plane wave deghosting of hydrophone and geophone OBC data, 68th Ann. Internat. Mtg., Soc. Expl. Geophys., Expanded Abstracts, 730-733.
  4. Barr, F. J., and J. I. Sanders, 1989, Attenuation of water-column reverberations using pressure and velocity detectors in a water-bottom cable, 59th Ann. Internat. Mtg., Soc. Expl. Geophys., Expanded Abstracts, 653-656.
  5. Dash, R., Spence, G., Hyndman, R., Grion, S., Wang, Y., and Ronen, S., 2009, Wide-area imaging from OBS multiples, Geophysics, 74(6), Q41-Q47. https://doi.org/10.1190/1.3223623
  6. Edme, P., and Singh, S. C., 2009, Receiver function decomposition of OBC data: theory, Geophys. J. Int., 177(3), 966-977. https://doi.org/10.1111/j.1365-246X.2009.04147.x
  7. Godfrey, R. J., Kristiansen, P., Armstrong, B., Coope, M., and Thorogood, E., 1998, Imaging the Foinaven ghost, 68th Ann. Internat. Mtg., Soc. Expl. Geophys., Expanded Abstracts, 1333-1335.
  8. Grion, S., Exley, R., Manin, M., Miao, X., Pica, A. L., Wang, Y., and Ronen, S., 2007, Mirror imaging of OBS data, First Break, 25, 37-42.
  9. Hoffe, B. H., Lines, L. R., and Cary, P. W., 2000, Applications of OBC recording, The Leading Edge, 19(4), 382-391. https://doi.org/10.1190/1.1438616
  10. Ikelle, L. T., and Amundsen, L., 2005, Introduction to Petroleum Seismology, Soc. Expl. Geophys.
  11. Kabbej, A., Baina, R., and Duquet, B., 2005, Data driven automatic aperture optimization for Kirchhoff migration, 75th Ann. Internat. Mtg, Soc. Expl. Geophys., Expanded Abstracts, 1890-1893.
  12. Lee, G., and Pyun, S., 2018, Reverse-time Migration using Surface-related Multiples, Geophys. and Geophys. Explor., 21, 41-53. (In Korean with English abstract)
  13. Martin, G. S., Wiley, R., and Marfurt, K. J., 2006, Marmousi2: An elastic upgrade for Marmousi, The Leading Edge, 25(2), 156-166. https://doi.org/10.1190/1.2172306
  14. Moghaddam, P. P., Libak, A., Keers, H., and Mjelde, R., 2012, Efficient and accurate modeling of ocean bottom seismometer data using reciprocity, Geophysics, 77(6), T211-T220. https://doi.org/10.1190/geo2011-0498.1
  15. Muijs, R., Robertsson, J. O., and Holliger, K., 2007, Prestack depth migration of primary and surface-related multiple reflections: Part I-Imaging, Geophysics, 72(2), S59-S69. https://doi.org/10.1190/1.2422796
  16. Pacal, E. E., Stewart, R. R., Baysal, E., and Yilmaz, O., 2015, Seismic Imaging with Ocean-Bottom Nodes (OBN): Mirror Migration Technique, 85th Ann. Internat. Mtg., Soc. Expl. Geophys., Expanded Abstracts, 4036-4043.
  17. Pica, A., Manin, M., Granger, P. Y., Marin, D., Suaudeau, E., David, B., Poulain, G., and Herrmann, Ph, 2006, 3D SRME on OBS data using waveform multiple modeling, 76th Ann. Internat. Mtg., Soc. Expl. Geophys., Expanded Abstracts, 2659-2663.
  18. Ronen, S., Comeaux, L., and Miao, J. G., 2005, Imaging downgoing waves from ocean bottom stations, 75th Ann. Internat. Mtg., Soc. Expl. Geophys., Expanded Abstracts, 963-966.
  19. Ronen, S., Comeaux, L., Miao, X., and Grion, S., 2006, Ocean bottom stations data-illumination problems and imaging solutions, 68th Conference and Exhibition, EAGE, Extended Abstracts, B041.
  20. Shin, C., Min, D., Marfurt, K. J., Lim, H., Yang, D., Cha, Y., Ko, S., Yoon, K., Ha, T., and Hong, S., 2002, Traveltime and amplitude calculations using the damped wave solution, Geophysics, 67(5), 1637-1647. https://doi.org/10.1190/1.1512811
  21. Schalkwijk, K. M., Wapenaar, C. P., and Verschuur, D. J., 1999, Application of two-step decomposition to multicomponent ocean-bottom data: Theory and case study, J. Seism. Explor., 8, 261-278.
  22. Wang, Y., Grion, S., and Bale, R., 2009, What comes up must have gone down: The principle and application of up-down deconvolution for multiple attenuation of ocean bottom data, CSEG Recorder, 34(10), 10-16.
  23. White, J. E., 1965, Seismic waves: Radiation, transmission and attenuation, McGraw-Hill Book Co.
  24. Xia, G., Clarke, R., Etgen, J., Kabir, N., Matson, K., and Michell, S., 2006, OBS multiple attenuation with application to the deepwater GOM Atlantis OBS nodes data, 76th Ann. Internat. Mtg., Soc. Expl. Geophys., Expanded Abstracts, 2654-2658.