Abstract
Implication of seismic attenuation for gas hydrate resource characterization, Mallik, Mackenzie Delta, Canada
Geological Survey of Canada, Ottawa, Ontario, Canada
McGill University, Montréal, Québec, Canada
Geological Survey of Canada, Calgary, Alberta, Canada
Geological Survey of Canada, Sidney, British Columbia, Canada
Geological Survey of Canada, Sidney, British Columbia, Canada
Wave attenuation is an important physical property of hydrate-bearing sediments that is rarely taken into account in site characterization with seismic data. We present a field example showing improved images of hydrate-bearing sediments on seismic data after compensation of attenuation effects. Compressional quality factors estimated from zero-offset Vertical Seismic Profiling data acquired at Mallik, Northwest Territories, Canada, demonstrate significant wave attenuation for hydrate-bearing sediments. These results are in agreement with previous attenuation estimates obtained from sonic logs and crosshole data at different frequency intervals. The application of an inverse Q-filter to compensate attenuation effects of permafrost and hydrate-bearing sediments improved the resolution of surface 3D seismic data and its correlation with log data, particularly for the shallowest gas hydrate interval. Compensation of the attenuation effects of the permafrost likely explains most of the improvements for the shallow gas hydrate zone. Our results show that characterization of the Mallik gas hydrates with seismic data not corrected for attenuation would tend to overestimate thicknesses and lateral extent of hydrate-bearing strata and hence, the volume of hydrates in place.
Received 6 February 2007; accepted 14 August 2007; published 30 October 2007.
Citation: (2007), Implication of seismic attenuation for gas hydrate resource characterization, Mallik, Mackenzie Delta, Canada, J. Geophys. Res., 112, B10311, doi:10.1029/2007JB004976.
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