지구물리와물리탐사 (Geophysics and Geophysical Exploration)

  • 제19권4호
  • /
  • Pages.220-227
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  • 2016
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  • 1229-1064(pISSN)
  • /
  • 2384-051X(eISSN)
한국지구물리·물리탐사학회 (Korean Society of Earth and Exploration Geophysicists)
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주파수-파선변수 영역에서 음원 및 수신기 고스트 제거를 통한 전통적인 해양 탄성파 자료의 광대역 자료처리

Broadband Processing of Conventional Marine Seismic Data Through Source and Receiver Deghosting in Frequency-Ray Parameter Domain

  • 김수민 (과학기술연합대학원대학교 석유자원공학과) ;
  • 구남형 (과학기술연합대학원대학교 석유자원공학과) ;
  • 이호영 (한국지질자원연구원 석유해저연구본부)
  • Kim, Su-min (Department of Petroleum Resources Technology, University of Science and Technology (UST)) ;
  • Koo, Nam-Hyung (Department of Petroleum Resources Technology, University of Science and Technology (UST)) ;
  • Lee, Ho-Young (Petroleum and Marine Division, Korea Institute of Geoscience and Mineral Resources (KIGAM))
  • 투고 : 2016.10.19
  • 심사 : 2016.11.15
  • 발행 : 2016.11.30
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초록

해양 탄성파 탐사를 통해 취득한 자료에는 지하 매질에서 반사되어 오는 신호뿐만 아니라 해수면에서 되반사되어 발생하는 고스트가 존재한다. 고스트는 특정 주파수 성분을 약화시켜 탄성파 자료의 시간 해상도를 저하시킨다. 고스트를 효과적으로 제거하기 위해서는 정확한 고스트의 지연시간과 해수면의 반사계수가 요구된다. 고스트 지연시간은 해수면의 상하 움직임, 에어건과 스트리머의 움직임 및 벌림(offset) 거리 등에 의해 변하며, 해수면의 반사계수도 주파수, 평면파의 입사각 그리고 해상 상태에 따라 변한다. 이러한 영향을 고려한 고스트 지연시간을 추정하기 위하여 이 연구에서는 고스트 제거 트레이스 및 이의 자기상관 자료의 L-1 norm, L-2 norm 그리고 첨도(kurtosis)를 비교하였다. 자기상관자료의 L-1 norm을 계산하여 고스트 지연시간을 추정하는 것이 오차가 가장 적게 발생하였다. 현장자료의 파고를 고려하고 키르히호프 근사식을 이용하여 해수면의 반사계수를 계산하여 음원 및 수신기 고스트 제거에 적용하였다. 고스트를 제거함으로써 약화된 주파수 성분을 복원하였으며 시간 해상도가 향상된 구조보정 단면을 얻었다.

Marine seismic data have not only primary signals from subsurface but also ghost signals reflected from the sea surface. The ghost decreases temporal resolution of seismic data because it attenuates specific frequency components. For eliminating the ghost signals effectively, the exact ghost delaytimes and reflection coefficients are required. Because of undulation of the sea surface and vertical movements of airguns and streamers, the ghost delaytime varies spatially and randomly while acquiring seismic data. The reflection coefficient is a function of frequency, incidence angle of plane-wave and the sea state. In order to estimate the proper ghost delaytimes considering these characteristics, we compared the ghost delaytimes estimated with L-1 norm, L-2 norm and kurtosis of the deghosted trace and its autocorrelation on synthetic data. L-1 norm of autocorrelation showed a minimal error and the reflection coefficient was calculated using Kirchhoff approximation equation which can handle the effect of wave height. We applied the estimated ghost delaytimes and the calculated reflection coefficients to remove the source and receiver ghost effects. By removing ghost signals, we reconstructed the frequency components attenuated near the notch frequency and produced the migrated stack section with enhanced temporal resolution.

키워드

참고문헌

  1. Carlson, D. H., Long, A., Sollner, W., Tabti, H., Tenghamn, R., and Lunde, N., 2007, Increased resolution and penetration from a towed dual-sensor streamer, First Break, 25, 71-77.
  2. Cohen, J. K., and Stockwell, Jr. J. W., 2015, CWP/SU: Seismic Unix Release No. 44: an open source software package for seismic research and processing, Center for Wave Phenomena, Colorado School of Mines.
  3. Ferber, R., and Beasley, C. J., 2014, Simulating ultra-deep-tow marine seismic data for receiver deghosting, 76th EAGE Conference and Exhibition, EAGE, Extended Abstracts.
  4. Ghosh, S. K., 2000, Deconvolving the ghost effect of the water surface in marine seismics, Geophysics, 65, 1831-1836. https://doi.org/10.1190/1.1444866
  5. Grion, S., Telling, R., and Barnes, J., 2015, Deghosting by kurtosis maximization, 77th Annual International Conference and Exhibition, EAGE, Extended Abstracts.
  6. Hardwick, A., Masoomzadeh, H., Gromotka, J., Cox, P., and Gilbert, R., 2014, Broadband processing in the Norwegian Barents sea-practical aspects of deghosting in a challenging marine environment, 84th Ann. Internat. Mtg., Soc. Expl. Geophys., Expanded Abstracts, 4223-4227.
  7. Hardwick, A., Charron, P., Masoomzadeh, H., Aiyepeku, A., Cox, P., and Laha, S., 2015, Accounting for sea surface variation in deghosting a novel approach applied to a 3D dataset offshore west Africa, 85th Ann. Internat. Mtg., Soc. Expl. Geophys., Expanded Abstracts, 4615-4619.
  8. Jayaram, V., Copeland, D., Ellinger, C., Sicking, C., Nelan, S., Gilberg, J., and Carter, C., 2015, Receiver deghosting method to mitigate f-k transform artifacts: A non-windowing approach, 85th Ann. Internat. Mtg., Soc. Expl. Geophys., Expanded Abstracts, 4530-4534.
  9. Jovanovich, D. B., Sumner, R. D., and Akins-Easterlin, S. L., 1983, Ghosting and marine signature deconvolution: A prerequisite for detailed seismic interpretation, Geophysics, 48, 1468-1485. https://doi.org/10.1190/1.1441431
  10. Koo, N. H., Shin, C., Min, D. J., Park, K. P., and Lee, H. Y., 2011, Source estimation and direct wave reconstruction in Laplace-domain waveform inversion for deep-sea seismic data, Geophysical Journal International, 187, 861-870. https://doi.org/10.1111/j.1365-246X.2011.05141.x
  11. Liu, L., and Lu, W., 2016, Adaptive f-k deghosting method based on non-Gaussianity, Journal of Applied Geophysics, 127, 14-22. https://doi.org/10.1016/j.jappgeo.2016.02.004
  12. Longuet-Higgins, M. S., 1952, On the statistical distributions of the heights of sea waves, J. Mar. Res., 11, 245-266.
  13. Perz, M. J., and Masoomzadeh, H., 2014, Deterministic marine deghosting: tutorial and recent advances, GeoConvention 2014: FOCUS, 1-6.
  14. Rickett, J. E., D. J. van Manen, P. Loganathan, and Seymour, N., 2014, Slanted-streamer data adaptive deghosting with local plane waves, 76th EAGE Conference and Exhibition, EAGE, Extended Abstracts.
  15. Soubaras, R., 2012, Pre-stack deghosting for variable-depth streamer data, 74th EAGE Conference and Exhibition incorporating EUROPEC, EAGE and SPE, Extended Abstracts.
  16. Tolstoy, I., and Clay, C. S., 1966, Ocean acoustics, McGraw-Hill.
  17. Wang, P., and Peng, C., 2012, Premigration deghosting for marine towed streamer data using a bootstrap approach, 82th Ann. Internat. Mtg., Soc. Expl. Geophys., Expanded Abstracts, 1-5.
  18. White, R. E., 1988, Maximum kurtosis phase correction, Geophysical Journal International, 95, 371-389. https://doi.org/10.1111/j.1365-246X.1988.tb00475.x
  19. Williams, R. G., and Pollatos, J., 2012, Signal to noise-the key to increased marine seismic bandwidth, First Break, 30, 101-105.
  20. Zhang, Z., Wu, Z., Wang, B., and Ji, J., 2015, Time variant deghosting and its applications in WAZ data, 85th Ann. Internat. Mtg., Soc. Expl. Geophys., Expanded Abstracts, 4600-4604.