Abstract
The formation of gas hydrates in the field is governed by complex biological, physical and geological processes. Each contributing parameter may have quite distinct role depending on the locales and environment under which gas hydrates are being formed. The stability of the gas hydrates in subsurface earth is under delicate natural balance, any perturbation either natural or man made may lead to dissociation of gas hydrates. The zone of gas hydrate stability under the subsurface earth is evaluated based on some assumptions, which may or may not hold good for precisely determining the upper or lower bounds stability zone. We are not certain whether seafloor makes top of the hydrate layer and how distinct is the coincidence of base of the stability zone to the acoustic signature of hydrates the BSR. The presence of hydrates much above the stability zone suggests that estimated stability zone is not the zone of containment for the hydrates. BSR has been proved most characteristic signature of presence of gas hydrates. In recent times its being debated whether acoustic velocity due to hydrate causes the BSR or it is the free-gas below the hydrate stability zone gives rise to BSR. Hydrates have been found in absence of BSR. Its being argued that BSR may not distinctly be observed due to insufficient supply of methane gas or the base hydrate zone is not in contact with top of the free gas zone. Evidences are emerging to indicate that most characteristic signature of BSR i.e. its mimicking the seafloor may not hold for geologically active regions. Warm fluids emerging from deep within may totally distort the signature of BSR. The velocities associated with hydrates or free-gas does not quantify amount of saturation required for generating the amplitude of BSR. The host rock in which hydrate gets formed may have distinct role in controlling the magnitude of velocities. Its being suggested that velocity gradient in thin zone across hydrate-free gas interface is sufficient to account for the strength of BSR. The pattern of amplitude versus distance (offset) has been extensively used to account for hydrate and free gas saturation in sediments. However, the pattern only suggests that what type of impedance contrast occurs across an interface, it does not really quantify the degree of saturation as velocities tend to show appreciable change owing to the formation of hydrates and presence of free gas depend the properties of the host rock. The present chapter makes an attempt in brief to identify the lacunae in the understanding of different signatures utilized for drawing inference about presence of gas hydrates and caution in using this information with bias.
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References
Andreassen, K., Hart, P.E., and Grantz, A., Seismic studies of a bottom simulating reflector related to gas hydrate beneath the continental margin of Beaufort Sea, Journal of Geophysical Research, 1995, 100, 12659–126732.
Andreassen, K., Hart, P.E., and Mackay, M., Amplitude versus offset modeling of the bottom simulating reflection associated with submarine gas hydrates, Marine Geology, 1997, 137, 25–40.
Ashi, J., Tokuyama, H., and Taira, A., Distribution of methane hydrate BSRs and its implication for prism growth in the Nankai Trough, Marine Geology, 2002, 187, 177–191.
Booth, J.S., Winter, W.J., Dillon, W.P., Clennell, M.B., and Rowe, M.M., Major occurrences and reservoir concepts of marine clathrate hydrates: Implications of field evidence, in: Henriet, J.P., and Mienert, J., (ed.), Gas hydrate: Relevance to world margin stability and climate change, Geological Society Special Publication, London, 1998,137, 113–127.
Berge, L., Jacobsen, K.A., and Solsted, A., Measured acoustic wave velocities of R11 (CCL3F) hydrate samples with and without sand as a function of hydrate concentration, Journal of Geophysical Research, 1999, 104, 15415–15424.
Chand, S., and Minshull, T.A., Seismic constraints on the effects of gas hydrate on sediments physical properties and fluid flow: A review, Geofluids, 2003, 3, 275–289.
Clay, C.S., and Medwin, H., Acoustical oceanography: Principles and applications, Wiley, New York, 1977, 537.
Dillon, W.P., and Max, M.D., Oceanic gas hydrate, in: Max, M.D., (ed.), Natural gas hydrate in oceanic and permafrost environments, Kluwer Academic, London, 2003, 61–76.
Ecker, C., Dvorkin, J., and Nur, A.M., Estimating the amount of gas hydrate and free gas from marine seismic data, Geophysics, 2000, 65, 563–573.
Fink, C.R., and Spence, G.D., Hydrate distribution off Vancouver island from multi-frequency single channel seismic reflection data, Journal of Geophysical Research, 1999, 104, 2909–2922.
Ginsburg, G.D., and Soloviev, V.A., Methane migration within the submarine gas-hydrate stability zone under deep-water conditions, Marine Geology, 1997, 127, 49–57.
Goldberg, D.S., Collett, T.S., and Hyndman, R.D., Ground truth: In-situ properties of hydrates, in: Max, M.D., (ed.), Natural gas hydrate in oceanic and permafrost environments, Kluwer Academic, London, 2003, 295–310.
Holbrook, W.S., Hoskins, W.T., Wood, R.A., Stephen, G.D., and Lizarralde, D., Methane hydrate and free gas on the Blake Ridge from vertical seismic profiling, Science, 1996, 273, 1840–1843.
Holbrook, W.S., Gorman, A.R., Hornbach, M., Hackwith, K.L., Nealon, J., Lizarralde, D., and Pecher, I.A., Seismic detection of marine methane hydrate, The Leading Edge, 2002, 21, 686–689.
Hovland, M., Lysne, D., and Whiticar, M.J., Gas hydrate and sediment gas composition, Hole 892A, in: Carson, B., Westbrook, G.E., Musgrave, R.J., and Suess, E., (eds.), Proceedings of ocean drilling program, scientific results, 1995, 151–161.
Hoveland, M., Gallagher, J.W., Clennell, M.B., and Lokvam, K., Gas hydrates and free-gas volume in the marine sediments: Example from Niger Delta front, Marine and Petroleum Geology, 1997, 14, 245–255.
Hyndman, R.D., and Spence, G.D., A seismic study of methane hydrate marine bottomsimulating reflectors, Journal of Geophysical Research, 1992, 97, 6683–6689.
Katzman, R., Holbrook, W.S., and Paull, C.K., Combined vertical incidence seismic study of gas hydrate zone, Blake Ridge, Journal of Geophysical Research, 1994, 99, 17975–17995.
Kaul, N., Rosenberger, A., and Villinger, H., Comparison of measured and BSR-derived heat flow values, Makran accretionary prism, Pakistan, Marine Geology, 2000, 164, 37–51.
Kvenvolden, K.A., A primer on the geological occurrence of gas hydrates, in: Henriet, J.P., and Mienert, J. (ed.), Relevance to world margin stability and climate change, Geological Society Special Publication, London, 1998, 137, 9–30.
Lee, M.W., Hutchinson, D.R., Dillon, W.P., Miller, J.J., Agena, W.F., and Swift, B.A., Method of estimating the amount of in situ gas hydrate in deep marine sediments, Marine and Petroleum Geology, 1993, 10, 493–506.
Lee, M.W., Hutchinson, D.R., Collett, T.S., and Dillon, W.P., Seismic velocities for hydrate-bearing sediments using weighted equation, Journal of Geophysical Research, 1996, 101, 20347–20358.
Macleod, M.K., Gas hydrates in ocean bottom sediments, AAPG Bulletin, 1982, 66, 2649–2662.
Mackay, M.E., Jarrard R.D., Westbrook G.K., and Hyndman, R.D., Origin of bottom simulating reflectors: Geophysical evidence from the Cascadia accretionary prism, Geology, 1994, 22, 459–462.
Minshull, T.A., Singh, S.C., and Westbrook, G.K., 1994. Seismic velocity structure at a gas hydrate reflector, offshore western Columbia, from full waveform inversion, Journal of Geophysical Research, 99, 4715–4734.
Osegovic, J.P., and Max, M.D., Compound clathrate hydrate on Titan’s surface, Journal of Geophysical Research, 2005, 110, E08004, doi: 10.1029/2005JE002435.
Pecher, I.A., Rnero, C.R., von Huene, R., Minshull, T.A., and Sigh, S.C., The nature and distribution of bottom simulating reflectors at the Costa Rican convergent margin, Geophysical Journal International, 1998, 133, 219–229.
Posewang, J., and Mienert, J., The enigma of double BSRs: Indicators of change of in the hydrate stability field? Geo-Marine Letters, 1999, 19, 157–163.
Prasanti, A., Thakur, N.K., Prasada Rao, P., and Rajput, S., Modelling of BSRs as prime indicator of gas hydrates, Current Science, 2009, 96, 1258–1262.
Priest, J.A., Rees, E.V.L., and Clayton, C.R.I., Influence of gas hydrate morphology on the seismic velocities of sands, Journal of Geophysical Research, 114, B11205, doi:10.1029/2009JB006284.
Reddi, S.I., et al., Reprocessing of multi-channel seismic data of ONGC for gas hydrate exploration in offshore Goa, part II, NGRI Technical Report No.–307, 2001, pp 30.
Reidel, M., Spence, G.D., Chapman, N.R., and Hyndman, R.D., Seismic investigations of a vent field associated with gas hydrates, offshore Vancouver island, Journal of Geophysical Research, 2002, 107, 16, DOI:10.1029/2001JB000269
Singh, S.C., Minshull, T.A., and Spence, G.D., Velocity structure of hydrate reflector, Science, 1993, 260, 204–207
Sloan, E.D., Clathrate hydrate of natural gases, Marcel Dekker, New York, 1998, 705.
Spence, G.D., Hyndman, R.D., Chapman, N.R., Reidel, M., Edward, N., and Yuan, J., Cascadia margin, Northeast Pacific Ocean: Hydrate distribution form geophysical investigations, in: Max, M.D., (ed.), Natural gas hydrate in oceanic and permafrost environments, Kluwer Academic Press, London, 2003, 183-198.
Taylor, M.H., Dillon, W.P., and Pecher, I.A., Trapping and migration of methane associated with gas hydrate stability zone at Blake Ridge Diapir: New insights from seismic data, Marine Geology, 2000, 18, 209–221.
Tinnivella, U., and Accaino, F., Compressional velocity structure and Poisson’s ratio in the marine sediments with gas hydrate and free gas by inversion of reflected and refracted seismic data (South Shetland Islands Antarctica), Marine Geology, 2000, 164,13-27.
Vanneste, M., De Batist, M., Golmshtok, A., Kremlev, A., Versteeg, W., Multi-frequency seismic study of gas hydrate-bearing sediments in Lake Baikal, Siberia, Marine Geology, 2001,172,1–21.
von Huene, R., and Pecher, I.A., Vertical tectonics and the origins of BSRs along the Peru margin, Earth and Planetary Science Letters, 1999, 166, 47–55.
Westbrook, G.K., Carson, B., Musgrave, R.J., et al. Proceedings Ocean Drilling Program, Interim Reports, 146, College Station, TX, 1994, 399–419.
Wilkens, R.H., Schreiber, B.C., Caruso, L., and Simmons, G., The effects of diagnosis on the microstructure of Eocene sediments bordering the Baltimore Canyon Trough. in: Watts, A.B., et al. (eds.), Initial reports of the deep sea drilling project XCV, Washington, DC, 1987, 527–547.
Wood, W.T., and Ruppel, C., Seismic investigations of the Blake ridge gas hydrate area, in: Paull, C.K, Matsumototo, R.,Wallace, P.J., and Dillon, W.P., (eds), Proceedings of the Ocean Drilling Program, Scientific Results, 2000, 164, 253–264.
Xu, W, Ruppel, C.D., Predicting the occurrence, distribution and evolution of methane gas hydrate in porous marine sediments, Journal of Geophysical Research, 1999, 104, 5081–5095.
Yuan, T., Hyndman, R.D., Spence, G.D., and Desmons, B., Seismic velocity increase and deep-sea gas hydrate concentration above a bottom-simulating reflector on the northern Cascadia continental slope, Journal of Geophysical Research, 1996,10, 13655–13671.
Yuan, T., Spence, G.D., Hyndman, R.D., Minshull, T.A., and Singh, S.C., Seismic velocity studies of a gas hydrate bottom-simulating reflector on the northern Cascadia continental margin: Amplitude modeling and full waveform inversion, Journal of Geophysical Research, 1999, 104, 1179–1191.
Zuehlsdorff, L., Spiess, V., Huebscher, C., Villnger, H., and Rosenberger, A., BSR occurrence, near surface reflectivity anomalies and small scale tectonism imaged in a multi-frequency seismic data set from the Cascadia accretionary prism, Geology Rundschau, 2000, 88, 655–667.
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Thakur, N.K., Rajput, S. (2011). The Road Ahead. In: Exploration of Gas Hydrates. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-14234-5_9
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