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Marine Geophysical Researches

, Volume 25, Issue 1–2, pp 157–180 | Cite as

Characteristics of Gas Hydrate and Free Gas Offshore Southwestern Taiwan from a Combined MCS/OBS Data Analysis

  • P. Schnurle
  • C.-S. Liu
  • T.-H. Hsiuan
  • T.-K. Wang
Article

Abstract

In this study, we present the results of the combined analyses of ocean bottom seismometer and multi-channel seismic reflection data collection offshore southwestern Taiwan, with respect to the presence of gas hydrates and free gas within the accretionary wedge sediments. Estimates of the compressional velocities along EW9509-33 seismic reflection profile are obtained by a series of pre-stack depth migrations in a layer stripping streamlined Deregowski loop. Strong BSR is imaged over most of the reflection profile while low velocity zones are imaged below BSR at several locations. Amplitude versus angle analysis that are performed within the pre-stack depth migration processes reveal strong negative P-impedance near the bottom of the hydrate stability zone, commonly underlain by sharp positive P impedance layers associated with negative pseudo-Poisson attribute areas, indicating the presence of free gas below the BSR. Ray tracing of the acoustic arrivals with a model derived from the migration velocities generally fits the vertical and hydrophone records of the four ocean-bottom seismographs (OBS). In order to estimate the Poisson’s ratios in the shallow sediments at the vicinity of the OBSs, we analyze the mode-converted arrivals in the wide-angle horizontal component. P-S mode converted reflections are dominant, while upward P-S transmissions are observed at large offsets. We observe significant compressional velocity and Poisson’s ratio pull-down in the sediment below the BSR likely to bear free gas. When compared to Poisson’s ratio predicted by mechanical models, the values proposed for the OBSs yield rough estimates of gas hydrate saturation in the range of 0–10% in the layers above the BSR and of free gas saturation in the range of 0–2% just below the BSR.

Keywords

amplitude versus angle analysis gas hydrate and free gas reflection–refraction seismic southwestern Taiwan 

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References

  1. Aki, K., Richard, P. 1980Quantitative seismology, theory and methodsFreemann and Co.1153Google Scholar
  2. Andreassen, K., Berteussen, K.A., Sognnes, H., Henneberg, K., Langhammer, J., Mienert, J. 2003Multicomponent ocean bottom cable data in gas hydrate investigation offshore NorwayJ. Geophys. Res.108111EPM9.CrossRefGoogle Scholar
  3. Bleistein, N., Cohen, J., Hagin, F. 1987Two and one-half dimensional born inversion with an arbitrary referenceGeophysics522636CrossRefGoogle Scholar
  4. Booth, J.S., Winters, W.J. Dillon, W.P., Clennel, M.B., and Rowe, M. M., 1998, Major occurences and reservoir concepts of marine clathrate hydrates: implications of field evidence, in Henriet, p. and Mienert, J.Gas Hydrates, Geol, Soc. Spec. Publ.(eds.), 137, 113–128.Google Scholar
  5. Bouriak, S., Vanneste, M., Saoutkine, A. 2000Inferred gas hydrate and clay diapir near Storegga slide on the southern edge of Voring Plateau, offshore NorwayMarine Geology163125148CrossRefGoogle Scholar
  6. Chen, Q.-Z. and Liu, C.S. 2002, BSR distribution and estimates of gas hydrate deposit offshore southwestern Taiwan, 9th Annual Geophysical Meeting, Taiwan.Google Scholar
  7. Chi, W.C., Reed, D.L., Liu, C.S., Lunberg, N. 1998Distribution of the Bottom Simulating Reflector in the Offshore Taiwan Collision ZoneTerr. Atmos. Ocean. Sci.9779793Google Scholar
  8. Deregowski,  1990Common offset migration and velocity analysisFist Break8225234Google Scholar
  9. Dickens, G.R., Paull, C.K., Wallace, P. and the ODP Leg 164 scientific Party, 1997, Direct measurements of in situ methane quantities in a large gas-hydrate reservoir, Nature 385, 426–428.Google Scholar
  10. Domenico, S.N. 1977Elastic properties of unconsolidated porous sand reservoirGeophysics4213391368CrossRefGoogle Scholar
  11. Durham, W.B, Kirby, S.H., Stern, L.A., Zhang, W. 2003The strength and rheology of methane clathrate hydrate. J. GeophysRes.1081112182, ECV2.CrossRefGoogle Scholar
  12. Guerin, G., Goldberg, D., Meltser, A. 1999Characterization of in situ elastic properties of gas hydrate-bearing sediments on the Blake RidgeJ. Geophys. Res.10417,78117,795Google Scholar
  13. Helgerud, M.B., Dvorkin, J., Nur, A., Sakai, A., Collett, T. 1999Elastic-wave velocity in marine sediments with gas hydrates: effective medium modelingGeophys. Res. Lett.2620212202CrossRefGoogle Scholar
  14. Helgerud, M.B., 2001, Wave speed in gas hydrates and sediments containing gas hydrates: a laboratory and modeling study. Ph.D. Thesis, Department of Geophysics, Stanford University, 248 pp.Google Scholar
  15. Kastner, M., Kvenvolden, K.A., Whiticar, M.J., Camerlinghi, A., Lorenson, T.D. 1996Relation between pore fluid chemistry and gas hydrates associated with bottom-simulating reflectors at the Cascadia margin, Sites 889 and 892. ProcOcean Drill. Program Sci. Res.146175189Google Scholar
  16. Kimura, K., Silver, E., Blum, P. and Leg 170 Scientific Party, 1998, Proc. Ocean Drill. Program, Initial Reports, 170, College Sation, Texas.Google Scholar
  17. Liu, C.S., Reed, D.L., Lundberg, N., Moore, G. F., McIntosh, K. D., Nakamura, Y., Wang, T. K., Chen, T. H., and Lallemand, S. E., 1996, Deep seismic imaging of the Taiwan arc–continent collision zone. EOS Tran., Am. Geophys. Un. 76(46), F635.Google Scholar
  18. Liu, C.S., Huang, I.L., Teng, L.S. 1997Structural features off southwestern TaiwanMari. Geol.137305319CrossRefGoogle Scholar
  19. Liu, C.-S., Chen, K.-C. and Schnurle, P., 2003, Distribution and characteristics of gas hydrates offshore southwestern Taiwan, EOS Tran., Am. Geophys. Un., Fall Meeting.Google Scholar
  20. Lee, M.W., Collet, T.C. 2001Elastic properties of gas hydrate-bearing sedimentsGeophysics66763771CrossRefGoogle Scholar
  21. Lee, M.W., Hutchinson, D.R., Dillon, W.P., Agena, J.J., Swift, B.A. 1996Seismic velocities for hydrate-bearing sediments from weighted equationJ. Geophys. Res.101347358Google Scholar
  22. MacKay, M.E., Jarrard, R.D., Westbrook, G.K., Hyndman, R.D., and Shipboard Scientific Party of ODP Leg 146, 1994, Origin of bottom-simulating reflector; Geophysical evidences from the Cascadia accretionary prism, Geology 22, 459–462.Google Scholar
  23. Mienert, J., Posewang, J. 1999Evidence of shallow and seep water gas hydrate destabilization in North Atlantic polar continental margin sedimentsGeo-Mar. Lett.19143149CrossRefGoogle Scholar
  24. Nakamura, Y., McIntosh, K.D., Chen, A.-T. 1998Preliminary results of a large offset seismic survey west of Henchun Peninsula, southern TaiwanTerr. Atmos. Ocean. Sci.9395408Google Scholar
  25. Paull, C.K., Matsumoto, R., Wallace, L. 1996Proceedings of the Ocean Drilling ProjectCollege StationTexas623Initial Reports, 164.Google Scholar
  26. Reed, D.L., Lundberg, N., Liu, C.S., Kuo, B.Y. 1992Structural relations along the margin of the offshore Taiwan accretionary wedge: implication for accretion and crustal kinematicsActa Geologica Taiwanica30105122Google Scholar
  27. Schnurle, P. 2004Determining elastic properties from seismic reflection surveys using pre-stack depth migration, residual move-out, perturbation, and amplitude versus angle analysisPetrol. Geol. Taiwan36132Google Scholar
  28. Schnurle, P., Hsiuan, T.-H., Wang, T.-K., MacIntosh, K., Char-Shine, Liu, Reed, D., Nakamura, Y. 2002Characteristics of gas hydrate and free gas offshore southwestern Taiwan: Preliminary results from combined MCS/OBS data analysisPetrol. Geol. Taiwan35133Google Scholar
  29. Schnurle, P., Hsiuan, D.-H. 2000Synthetic wide-angle seismic data in gas hydrate and free gas bearing sediments: A virtual OBS case studyPetrol. Geol. Taiwan34132Google Scholar
  30. Schnurle, P., Hsiuan, D.-H., Liu, C.-S. 1999Constrains on free gas and gas hydrate bearing sediments from multi-channel seismic data, offshore southwestern TaiwanPetrol. Geol. Taiwan332142Google Scholar
  31. Shuey, R. 1985A simplification to the Zoeprintz equationsGeophysics50609614CrossRefGoogle Scholar
  32. Sloan, E.D. 1998Clathrate Hydrates of Natural GasesMarcel Dekker Inc.New York6411990, and 2nd edition 1998.Google Scholar
  33. Tréhu, A.M., Flueh, E.R. 2001Estimating the thickness of the free gas zone beneath hydrate ridge, Oregon continental margin, from seismic velocities and attenuationJ. Geophys. Res.10620352045CrossRefGoogle Scholar
  34. Tréhu, A.M., Long, P. E., Torres, M. E., Bohrmann, G., Rack, F. R., Collett, T. S., Goldberg, D. S., Milkov, A. V., Riedel, M., Schultheiss, P., Bangs, N. L., Barr, S. R., Borowski, W. S., Claypool, G. E., Delwiche, M. E., Dickens, G. R., Gracia, E., Guerin, G., Holland, M., Johnson, J. E., Lee, Y.-J., Liu, C.-S., Su, X., Teichert, B., Tomaru, H., Vanneste, M., Watanabe, M., Weinberger, J. L. 2004Three-dimensional distribution of gas hydrate beneath southern Hydrate Ridge: constraints from ODP Leg 204Earth Planet. Sci. Lett.222845862CrossRefGoogle Scholar
  35. Tinavella, U., Accaino, F. 2000Compressional velocity and poisson’s ratio in marine sediments with gas hydrate and free gas by inversion of reflected and refracted seismic data (South Shetland Island, Antartica)Mar. Geol.1641327CrossRefGoogle Scholar
  36. Uchida, T., Dallimore, S., Nixon, M. and Mikami, J., 1998, Occurrences of gas hydrates obtained from the JAPEX/JNOC/GSC Mallik 2L-38 research well: video presentation Internat. Symp. Methane Hydrates, Proceeding, 371–378.Google Scholar
  37. Von Huene, R., Sholl, D.W. 1991Observations at convergent margins concerning sediment subduction, subduction erosion, and the groth of continental crustRev. Geophys.29279316Google Scholar
  38. Waite, W., Helgerud, M. B., Nur, A., Pinksto, J. C., Stern, L., and Kirby, S., 2000, Laboratory measurements of compressional and shear-wave speeds through methane hydrate, inGas hydrate: Challenges for the future, edited by G.D. Holder and P.R. Bishnoi, Ann. N.Y. Acad. Sci. 912, 1003–1010.Google Scholar
  39. Wang, T-.K. and Pan, C.-H. 2001, Crustal Poisson’s Ratio off eastern Taiwan from OBS data modeling,Terr. Atmos. Ocean. Sci. supplem. issue 249–268.Google Scholar
  40. Wessel, P., Smith, W.H.F. 1995New version of the Generic Mapping Tools releasedEOS Trans., AGU, Suppl.763297.Google Scholar
  41. Zelt, C.A., Smith, R.B. 1992Seismic travel time inversion for 2D crustal velocity structureGeophys J. Int.1081634Google Scholar

Copyright information

© Springer 2005

Authors and Affiliations

  • P. Schnurle
    • 1
  • C.-S. Liu
    • 1
  • T.-H. Hsiuan
    • 2
  • T.-K. Wang
    • 3
  1. 1.Institute of OceanographyNational Taiwan UniversityTaipeiTaiwan, ROC
  2. 2.Exploration and Production Business DivisionChinese Petroleum CorporationMiaoliTaiwan
  3. 3.Institute of Applied GeophysicsNational Taiwan Ocean UniversityKeelungTaiwan, ROC

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