A Study on Submarine Slope Failure due to Gas Hydrate Dissociation

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2008 Vol.45, Issue 2 Preview Page Next Page

A Study on Submarine Slope Failure due to Gas Hydrate Dissociation 가스 하이드레이트의 해리로 인한 해저사면의 붕괴에 관한 연구: 박성식
Park, Sung-Sik

30 April 2008. pp. 164-173

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Abstract

The influence of gas hydrate dissociation on submarine slope stability was studied in this paper. Gas hydrates are stable under high pressure and low temperature conditions. Once gas hydrate dissociates due to natural or human activities, it generates large amount of gas and water. During gas hydrate dissociation, a pore pressure between soil particles increases and results in the loss of an effective stress and degradation of soil stiffness and strength. An excess pore pressure generated by gas hydrate dissociation for the Storegga Slide was calculated from two existing pore pressure calculation methods and the proposed method. The proposed method gives at least two times more excess pore pressure than the existing methods. A slope stability analysis for the Storegga Slide using a two dimensional finite difference method was carried out by considering excess pore pressures due to gas hydrate dissociation. Since the excess pore pressure calculated by the proposed method resulted in the considerable loss of stiffness and strength in gas hydrate zone, a submarine slope failure occurred at the Storegga slide was successfully simulated.

Keywords

Gas hydrate

Dissociation

Submarine slope

Excess pore pressure

본 논문에서는 가스 하이드레이트가 매장된 해저사면에서 가스 하이드레이트층의 해리에 따른 해저사면의 안전성에 관한 연구를 수행하였다. 가스 하이드레이트는 일반적으로 저온 고압에서 안정성을 유지하지만, 매장되어 있는 지역에서 자연적 또는 인위적인 활동으로 인한 온도나 압력의 변화로 해리가 시작되면 많은 양의 가스와 물이 발생한다. 이때 해저사면 내에 있는 흙 골격 사이에서는 과잉간극수압이 발생하며 이로 인한 유효응력감소와 그에 따른 흙의 강성 및 강도저하가 일어난다. 기존의 다른 연구자가 제안한 두 종류의 간극수압 계산방법과 본 연구에서 제안한 방법을 이용하여 해저사면의 붕괴 사례인 Storegga Slide에서 가스 하이드레이트의 해리로 인한 과잉간극수압을 계산하였으며, 그 결과 본 연구에서 제안한 방법이 기존 방법보다 최소 2배 이상의 높은 과잉간극수압을 예측하였다. Storegga Slide를 재현하기 위하여 가스 하이드레이트의 해리로 계산된 과잉간극수압을 고려하여 2차원 유한차분법을 이용한 해저사면의 수치해석을 실시하였다. 본 연구에서 제안한 방법으로 계산한 과잉간극수압을 이용하여 흙의 강성과 강도저하를 고려하였을 때 Storegga Slide가 일어난 해저사면의 붕괴를 가장 잘 재현할 수 있었다.

키워드

가스 하이드레이트

해리

해저사면

과잉간극수압

References

허대기, 2005, “가스하이드레이트 기술개발 현황,” 한국지구시스템공학회지, Vol. 42, No. 3, pp. 206-213.
Bondevik, S., Svendsen, J.I., Mangerud, J., 1997, “Tsunami sedimentary facies deposited by the Storegga tsunami in shallow marine basins and coastal lakes, western Norway,” Sedimentology, 44, 115-1131.
Bugge, T., Befring, S., Belderson, R.H., Eidvin, T., Jansen, E., Kenyon, N.H., Holtedahl, H., and Sejrup, H.P., 1987, “A giant three-stage submarine slide off Norway,” Geo-Marine Letters, 7, pp. 191-198.
Dillon, W.P., Danforth, W.W., Hutchinson, D.R., Drury, R.M., Taylor, M.H., Booth. J.S., 1998, “Evidence of faulting related to dissociation of gas hydrate and release of methane off the southeastern U.S,” In Henriet, J.P. and Mienert, J. (Eds), Gas hydrates: Relevance to World Margin stability and climate change, Geological Society, London, Special Publications, 137, pp. 293-302.
Field, M.E. and Barber Jr., J.H., 1993, “A submarine landslide associated with shallow seafloor gas hydrates off northern California,” In Schwab, W.C., Lee, H.J., Twichell, D.C. (Eds), Submarine landslides: selected studies in the US exclusive economic zone. US Geological Survey Bulletin 2002, pp. 151-157.
Geo-Slope, 2001, Slope/w, Geo-Slope International, Canada.
Grantz, A, and Dinter, D.A., 1980, “Constraints of geologic processes on western Beaufort Sea oil developments,” Oil and Gas Journal, 78(18), pp. 304-319.
Itasca, 2000, FLAC, version 4.0. Itasca Consulting Group Inc., Minneapolis.
Jung, W.Y. and Vogt, P.R., 2004, “Effect of bottom water warming and sea level rise on Holocene hydrate dissociation and mass wasting along the Norweigian-Barents Continental Margin,” Journal of Geophysical Research, 109, B06104, 18 pgs.
Kayen R.E. and Lee H.J., 1993, “Slope stability in regions of sea-floor gas hydrate: Beaufort Sea continental slope,” In: Schwab, W.C., Lee, H.J., Twichell, D.C. (Eds), Submarine landslides: selected studies in the US exclusive economic zone, US Geological Survey Bulletin 2002, pp. 97-103.
Kvenvolden, K.A., 1993, “Gas hydrates-Geological perspective and global change,” Reviews of Geophysics, 31(2), pp. 173-187.
Kvenvolden, K.A., 1999, “Potential effects of gas hydrate on human welfare,” Proc. of the National Academy of Sciences, Vol. 96, pp. 3420-3426.
Kvenvolden, K.A., 2000, “Gas hydrate and humans,” Annals of the New York Academy of Sciences, Vol. 912, pp. 17-22.
Leynaud, D., Mienert, J. and Nadim, F., 2004, “Slope stability assessment of the Helland Hansen area offshore the mid-Norwegian margin,” Marine Geology, 213, 457-480.
McIver, R.D., 1982, “Role of naturally occurring gas hydrates in sediment transport,” American Association Petroleum Geology Bulletin, 66, 789-792.
Mienert, J., Vanneste, M., Bunz, S., Andreassen, K., Haflidason, H. and Sejrup, H.P., 2005, “Ocean warming and gas hydrate stability on the mid-Norwegian margin at the storegga slide,” Marine and Petroleum Geology, 22, 233-244.
Milkov, A.V., Sassen, R., Novikova, I. and Mikhailov,E., 2000, “Gas hydrates at minimum stability water depths in the Gulf of Mexico: Significance to Geoharzard Assessment,” In Gulf Coast Association of Geological Societies, Volume L, pp. 217-224.
Nixon, M.F. and Grozic, J.L.H., 2007, “Submarine slope failure due to gas hydrate dissociation: a preliminary quantification,” Canadian Geotechnical Journal, 44, pp. 314-325.
Popenoe, P., Schmuck, E.A., Dillon, W.P., 1993, “The Cape Fear Landslide: slope failure associated with salt diapirism and gas hydrate decomposition,” Submarine landslides: Selected studies in the US exclusive economic zone.
Seed, H. B., Wong, R. T., Idriss, I. M. and Tokimatsu, K. 1986, “Moduli and damping factors for dynamic analyses of cohesionless soils”, Journal of Geotechnical Engineering, ASCE, Vol. 112, No. 11, pp. 1016-1032.
Sultan, N., Cochonat, P., Foucher, J.P., Mienert, J., 2004, “Effect of gas hydrates melting on seafloor slope instability,” Marine Geology, 213, 379-401.
USGS, 1992, Gas (Methane) Hydrates-A New Frontier (from http://marine.usgs.gov/fact-sheets/gas-hydrates/title.html).

Information

Publisher :The Korean Society of Mineral and Energy Resources Engineers
Publisher(Ko) :한국자원공학회
Journal Title :Journal of the Korean Society for Geosystem Engineering
Journal Title(Ko) :한국지구시스템공학회지
Volume : 45
No :2
Pages :164-173

[1] 허대기, 2005, “가스하이드레이트 기술개발 현황,” 한국지구시스템공학회지, Vol. 42, No. 3, pp. 206-213.

[2] Bondevik, S., Svendsen, J.I., Mangerud, J., 1997, “Tsunami sedimentary facies deposited by the Storegga tsunami in shallow marine basins and coastal lakes, western Norway,” Sedimentology, 44, 115-1131.

[3] Bugge, T., Befring, S., Belderson, R.H., Eidvin, T., Jansen, E., Kenyon, N.H., Holtedahl, H., and Sejrup, H.P., 1987, “A giant three-stage submarine slide off Norway,” Geo-Marine Letters, 7, pp. 191-198.

[4] Dillon, W.P., Danforth, W.W., Hutchinson, D.R., Drury, R.M., Taylor, M.H., Booth. J.S., 1998, “Evidence of faulting related to dissociation of gas hydrate and release of methane off the southeastern U.S,” In Henriet, J.P. and Mienert, J. (Eds), Gas hydrates: Relevance to World Margin stability and climate change, Geological Society, London, Special Publications, 137, pp. 293-302.

[5] Field, M.E. and Barber Jr., J.H., 1993, “A submarine landslide associated with shallow seafloor gas hydrates off northern California,” In Schwab, W.C., Lee, H.J., Twichell, D.C. (Eds), Submarine landslides: selected studies in the US exclusive economic zone. US Geological Survey Bulletin 2002, pp. 151-157.

[6] Geo-Slope, 2001, Slope/w, Geo-Slope International, Canada.

[7] Grantz, A, and Dinter, D.A., 1980, “Constraints of geologic processes on western Beaufort Sea oil developments,” Oil and Gas Journal, 78(18), pp. 304-319.

[8] Itasca, 2000, FLAC, version 4.0. Itasca Consulting Group Inc., Minneapolis.

[9] Jung, W.Y. and Vogt, P.R., 2004, “Effect of bottom water warming and sea level rise on Holocene hydrate dissociation and mass wasting along the Norweigian-Barents Continental Margin,” Journal of Geophysical Research, 109, B06104, 18 pgs.

[10] Kayen R.E. and Lee H.J., 1993, “Slope stability in regions of sea-floor gas hydrate: Beaufort Sea continental slope,” In: Schwab, W.C., Lee, H.J., Twichell, D.C. (Eds), Submarine landslides: selected studies in the US exclusive economic zone, US Geological Survey Bulletin 2002, pp. 97-103.

[11] Kvenvolden, K.A., 1993, “Gas hydrates-Geological perspective and global change,” Reviews of Geophysics, 31(2), pp. 173-187.

[12] Kvenvolden, K.A., 1999, “Potential effects of gas hydrate on human welfare,” Proc. of the National Academy of Sciences, Vol. 96, pp. 3420-3426.

[13] Kvenvolden, K.A., 2000, “Gas hydrate and humans,” Annals of the New York Academy of Sciences, Vol. 912, pp. 17-22.

[14] Leynaud, D., Mienert, J. and Nadim, F., 2004, “Slope stability assessment of the Helland Hansen area offshore the mid-Norwegian margin,” Marine Geology, 213, 457-480.

[15] McIver, R.D., 1982, “Role of naturally occurring gas hydrates in sediment transport,” American Association Petroleum Geology Bulletin, 66, 789-792.

[16] Mienert, J., Vanneste, M., Bunz, S., Andreassen, K., Haflidason, H. and Sejrup, H.P., 2005, “Ocean warming and gas hydrate stability on the mid-Norwegian margin at the storegga slide,” Marine and Petroleum Geology, 22, 233-244.

[17] Milkov, A.V., Sassen, R., Novikova, I. and Mikhailov,E., 2000, “Gas hydrates at minimum stability water depths in the Gulf of Mexico: Significance to Geoharzard Assessment,” In Gulf Coast Association of Geological Societies, Volume L, pp. 217-224.

[18] Nixon, M.F. and Grozic, J.L.H., 2007, “Submarine slope failure due to gas hydrate dissociation: a preliminary quantification,” Canadian Geotechnical Journal, 44, pp. 314-325.

[19] Popenoe, P., Schmuck, E.A., Dillon, W.P., 1993, “The Cape Fear Landslide: slope failure associated with salt diapirism and gas hydrate decomposition,” Submarine landslides: Selected studies in the US exclusive economic zone.

[20] Seed, H. B., Wong, R. T., Idriss, I. M. and Tokimatsu, K. 1986, “Moduli and damping factors for dynamic analyses of cohesionless soils”, Journal of Geotechnical Engineering, ASCE, Vol. 112, No. 11, pp. 1016-1032.

[21] Sultan, N., Cochonat, P., Foucher, J.P., Mienert, J., 2004, “Effect of gas hydrates melting on seafloor slope instability,” Marine Geology, 213, 379-401.

[22] USGS, 1992, Gas (Methane) Hydrates-A New Frontier (from http://marine.usgs.gov/fact-sheets/gas-hydrates/title.html).

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