Geophysics and Geophysical Exploration (지구물리와물리탐사)

Korean Society of Earth and Exploration Geophysicists (한국지구물리·물리탐사학회)
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Swell Effect Correction of Sub-bottom Profiler Data with Weak Sea Bottom Signal

해저면 신호가 약한 천부해저지층 탐사자료의 너울영향 보정

  • Lee, Ho-Young (Petroleum and Marine Research Division, Korea Institute of Geoscience and Mineral Resources) ;
  • Koo, Nam-Hyung (Petroleum and Marine Research Division, Korea Institute of Geoscience and Mineral Resources) ;
  • Kim, Wonsik (Pohang Branch, Korea Institute of Geoscience and Mineral Resources) ;
  • Kim, Byoung-Yeop (Petroleum and Marine Research Division, Korea Institute of Geoscience and Mineral Resources) ;
  • Cheong, Snons (Petroleum and Marine Research Division, Korea Institute of Geoscience and Mineral Resources) ;
  • Kim, Young-Jun (Petroleum and Marine Research Division, Korea Institute of Geoscience and Mineral Resources) ;
  • Son, Woohyun (Petroleum and Marine Research Division, Korea Institute of Geoscience and Mineral Resources)
  • 이호영 (한국지질자원연구원 석유해저연구본부) ;
  • 구남형 (한국지질자원연구원 석유해저연구본부) ;
  • 김원식 (한국지질자원연구원 포항지질자원실증연구센터) ;
  • 김병엽 (한국지질자원연구원 석유해저연구본부) ;
  • 정순홍 (한국지질자원연구원 석유해저연구본부) ;
  • 김영준 (한국지질자원연구원 석유해저연구본부) ;
  • 손우현 (한국지질자원연구원 석유해저연구본부)
  • Received : 2015.09.14
  • Accepted : 2015.11.03
  • Published : 2015.11.30
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Abstract

A 3.5 kHz or chirp sub-bottom profiling survey is widely used in the marine geological and engineering purpose exploration. However, swells in the sea degrade the quality of the survey data. The horizontal continuity of profiler data can be enhanced and the quality can be improved by correcting the influence of the swell. Accurate detection of sea bottom location is important in correcting the swell effect. In this study, we tried to pick sea bottom locations by finding the position of crossing a threshold of the maximum value for the raw data and transformed data of envelope or energy ratio. However, in case of the low-quality data where the sea bottom signals are not clear due to sea wave noise, automatic sea bottom detection at the individual traces was not successful. We corrected the mispicks for the low quality data and obtained satisfactory results by picking a sea bottom within a range considering the previous average of sea bottom, and excluding unreliable big-difference picks. In case of trace by trace picking, fewest mispicks were found when using energy ratio data. In case of picking considering the previous average, the correction result was relatively satisfactory when using raw data.

3.5 kHz 또는 첩(chirp) 천부해저 지층탐사는 해양지질 조사나 엔지니어링 탐사에 널리 사용되고 있다. 그러나 해상에서의 너울은 탐사자료의 품질을 저하시킨다. 이와 같은 너울의 영향을 보정함으로써 연속성이 향상된 탐사자료를 얻을 수 있다. 정확한 해저면의 위치 선정은 너울영향 보정에 매우 중요하다. 이 연구에서는 원자료와 이를 엔벨로프 또는 에너지비율자료로 변형시킨 자료들에 대해 최대 진폭값의 일정 기준을 초과하는 지점을 선정하는 방법으로 해저면 위치 선정을 시도하였다. 그러나 파도의 잡음으로 인하여 해저면 신호가 분명하지 않은 품질이 낮은 자료에서는 개별 트레이스에서의 자동적인 해저면 위치 선정이 어려웠다. 이 연구에서는 이전 트레이스에서 구한 해저면 평균값을 고려하여 해저면 선정범위 내에서 해저면을 선정하는 방법과, 선정 결과의 신뢰도가 낮은 경우에는 이를 보정에서 제외하는 방법을 사용함으로써 품질이 낮은 자료의 해저면 선정에서도 만족스러운 결과를 얻었다. 개별 트레이스에서 해저면을 선정할 때에는 에너지비율자료를 사용한 경우에 오류가 가장 적었으며, 이전 트레이스 해저면 평균값을 고려하는 방법에서는 원자료를 직접 사용한 경우에 보정결과가 비교적 양호하였다.

Keywords

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