HR: 0800h
AN: C11A-1068    [Abstracts]
TI: Broadband Seismic Studies at the Mallik Gas Hydrate Research Well
AU: * Sun, L F
EM: lsun@physics.utoronto.ca
AF: Dept. of Physics, Univ. of Toronto, 60 St. George Street, Toronto, ON M5S 1A7 Canada
AU: Huang, J
EM: jh@physics.utoronto.ca
AF: Dept. of Physics, Univ. of Toronto, 60 St. George Street, Toronto, ON M5S 1A7 Canada
AU: Lyons-Thomas, P
EM: plyons@physics.utoronto.ca
AF: Dept. of Physics, Univ. of Toronto, 60 St. George Street, Toronto, ON M5S 1A7 Canada
AU: Qian, W
EM: wqian@physics.utoronto.ca
AF: Dept. of Physics, Univ. of Toronto, 60 St. George Street, Toronto, ON M5S 1A7 Canada
AU: Milkereit, B
EM: bm@physics.utoronto.ca
AF: Dept. of Physics, Univ. of Toronto, 60 St. George Street, Toronto, ON M5S 1A7 Canada
AU: Schmitt, D R
EM: doug@phys.ualberta.ca
AF: Dept. of Physics, Univ. of Alberta, Rm #547, Avadh Bhatia Physics Laboratory, University of Alberta, Edmonton, AB T6G 2J1 Canada
AB: The JAPEX/JNOC/GSC et al. Mallik 3L-38, 4L-38 and 5L-38 scientific wells were drilled in the MacKenzie Delta, NWT, Canada in early 2002 primarily for carrying out initial tests of the feasibility of producing methane gas from the large gas hydrate deposits there [1]. As part of this study, high resolution seismic profiles, a pseudo-3D single fold seismic volume and broadband (8~180Hz) multi-offset vertical seismic profiles (VSP) were acquired at the Mallik site. Here, we provide details on the acquisition program, present the results of the 2D field profile, and discuss the potential implications of these observations for the structure of the permafrost and gas hydrate zones. These zones have long been problematic in seismic imaging due to the lateral heterogeneities. Conventional seismic data processing usually assume a stratified, weak-contrast elastic earth model. However, in permafrost and gas hydrate zones this approximation often becomes invalid. This leads to seismic wave scattering caused by multi-scale perturbation of elastic properties. A 3D viscoelastic finite difference modeling algorithm was employed to simulate wave propagation in a medium with strong contrast. Parameters in this modeling analysis are based on the borehole geophysical log data. In addition, an uncorrelated Vibroseis VSP data set was studied to investigate frequency-dependent absorption and velocity dispersion. Our results indicate that scattering and velocity dispersion are important for a better understanding of attenuation mechanisms in heterogeneous permafrost and gas hydrate zones. [1] Dallimore, S.R., Collett, T.S., Uchida, T., and Weber, M., 2005, Overview of the science program for the Mallik 2002 Gas Hydrate Production Research Well Program; in Scientific Results from Mallik 2002 Gas Hydrate production Research Well Program, MacKenzie Delta, Northwest Territories, Canada, (ed.) S.R. Dallimore and T.S. Collett; Geological Survey of Canada, Bulletin 585, in press.
DE: 0545 Modeling (4255)
DE: 0702 Permafrost (0475)
DE: 0935 Seismic methods (3025, 7294)
DE: 3285 Wave propagation (0689, 2487, 4275, 4455, 6934)
DE: 5144 Wave attenuation
SC: Cryosphere [C]
MN: Fall Meeting 2005