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P-wave Velocity Analysis Around the BSR Using Wide-angle Ocean-bottom Seismic Data  

Kim, Byoung-Yeop (Petroleum and Marine Resources Division, Korea Institute of Geoscience & Mineral Resources)
Byun, Joong-Moo (Department of Geoenvironmental System Engineering, Hanyang University)
Publication Information
Geophysics and Geophysical Exploration / v.12, no.2, 2009 , pp. 173-182 More about this Journal
Abstract
In April 2008, KIGAM carried out an ocean-bottom seismometer (OBS) survey in the central Ulleung Basin where strong bottom simulating reflectors (BSRs) were revealed from previous surveys and some gas-hydrate samples were retrieved by direct sampling. The purpose of this survey is to estimate the velocity structure near the BSR in the gas hydrate prospect area using wide-angle seismic data recorded on the ocean-bottom seismometers. Along with the OBS survey, a 2-D seismic survey was performed whereby stratigraphic and preliminary velocity information was obtained. Two methods were applied to wide-angle data for estimating P wave velocity; one is velocity analysis in the $\tau$-p domain and the other is seismic traveltime inversion. A 1-D interval velocity profile was obtained by the first method, which was refined to layered velocity structure by the latter method. A layer stripping method was adopted for modeling and inversion. All velocity profiles at each OBS site clearly show velocity reversal at BSR depths due to the presence of gas hydrates. In addition, we could confirm high velocity in the column/chimney structure.
Keywords
Ocean bottom seismometer; wide-angle seismic survey; gas hydrate; traveltime inversion; tau-p velocity analysis;
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1 한국지질자원연구원, 2007, 가스하이드레이트 지구물리탐사 연구 1단계 최종보고서
2 Jaiswal, P., Zelt, C. A. and Pecher, I. A., 2006, Seismic charac-terization of a gas hydrate system in the Gulf of Mexico using wide-aperture data, Geophys. J. Int., 165, 108-120
3 Lee, H. Y., Park, K. P., Yoo, D. G., Koo, N. H., Kim, W. S., Kim, B. Y., Kang, D. H. and Kim, H. J., 2008, Geophysical activity of gas hydrate exploration in Korea, Proceedings of the 6th International Conference on Gas Hydrate (ICGH 2008)
4 Medwind, H. 1975, Speed of Sound In Water: A Simple Equation for Realistic Parameters. The Journal of the Acoustical Society of America, 58, 1318-1319
5 Park, K. P., 2008, Gas hydrate exploration activities in Korea, Proceedings of the 6th International Conference on Gas Hydrate (ICGH 2008)
6 Petersen, C. J., Papenberg, C. and Klaeschen, D., 2007, Local seismic quantification of gas hydrates and BSR characterization from multi-frequency OBS data at northern Hydrate Ridge, Earth and Planetary Science Letters, 255, 414-431
7 Tinivella, U., Lodolo, E., Camerlenghi, A. and Boehm, G., 1998, Seismic tomography study of a bottom simulating reflector off the South Shetland Islands (Antarctica), In:Henriet J. P. and Mienert J.(eds) Gas Hydrates: Relevance to World Margin Stability and Climate Change, Geological Society, London, Special Publication, 137, 151
8 Zelt, C. A., 1999, Modelling strategies and model assessment for wide-angle seismic travetime data, Geophys. J. Int., 139, 183-204
9 $B\ddot unz$, S., Mienert, J., Vanneste, M. and Andreassen, K., 2005, Gas hydrate at the Storegga Slide: Constraints from an analysis of multicomponent, wide-angle seismic data, Geophysics, 70, B19-B34
10 Tinivella, U. and Accaino, F., 2000, Compressional velocity structure and Poisson's ratio in marine sediments with gas hydrate and free gas by inversion of reflected and refracted seismic data(South Shetland Islands, Antarctica), Marine Geology, 164, 13-27
11 Bessonova, E. N., Fishman, V. M., Ryaboyi, V. Z. and Stinikova, G. A., 1794, The tau method for inversion of travel time-I. Deep seismic sounding data, Geophys. J. R. Astr. Soc., 36, 377-398
12 Diebold, J. B. and Stoffa, P. L., 1981, The traveltime equation, tau-p mapping, and inversion of common midpoint data, Geophysics, 46, 238-254
13 Shipley, T. H., Houston, M. H., Bufer, R. T., Shaub, F. J., McMillen, K. J., Ladd, J. W. and Worzel, J. L, 1979, Seismic evidence for widespread possible gas hydrate horizon continental slopes and rises, AAPG Bull., 63, 2204-2231
14 Iyer, H. M. and Hirahara, K., 1993, Seismic Tomography, Chapman & Hall, 733
15 김길영, 유동근, 김원식, 이호영, 박근필, 2008, LWD/MWD를 이용한 동해 울릉분지 가스하이드레이트 탐사, 물리탐사, 11, 263-270
16 Holbrook, W. S., Hoskins, H., Wood, W. T., Stephen, R. A., Lizarralde, D. and Party, L. S., 1996, Methane hydrate and free gas on Blake Ridge from vertical seismic profiling, Science, 273, 1840-1843
17 Sheriff, R. E., 2002, Encyclopedic Dictionary of Applied Geo-physics, 4th Ed., Series Editor: Scherrer E. F., SEG
18 Max, M. D., Johnson, A. H. and Dillon, W. P., 2006, Economic Geology of Natural Gas Hydrate, Springer, 45-46
19 Sloan, E. D. JR., 1998, Physical/chemical properties of gas hydrates and application to world margin stability and climatic change, In: Henriet J. P. and Mienert J. (eds) Gas Hydrates: Relevance to World Margin Stability and Climate Change, Geological Society, London, Special Publication, 137, 31
20 Yilmaz, O., 2001, Seismic data analysis: Processing, Inversion and Interpretation of Seismic Data: 2nd Ed., Society of Exploration Geophysicists, Tulsa
21 Zelt, C. A. and Smith, R. B., 1992, Seismic traveltime inversion of 2-D crustal velocity structure, Geophys. J. Int., 108, 16-34
22 Spence, G. D., Minshull, T. A. and Fink, C., 1995, Seismic studies of methane gas hydrate, offshore Vancouver Island, Proceedings of the Ocean Drilling Program, Scientific Results, 146, 163-172