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McGee, Tom1, Ross Chapman2, Camelia C. Knapp3, Erika Geresi1, Brad Battista3, Mike Morley2, J. R. Woolsey1
(1) University of Mississippi, University, MS
(2) University of Victoria, Victoria, British Columbia 
(3) University of South Carolina, Columbia, SC

ABSTRACT: An Integrated Seismic Study of the Proposed DoE/JIP Drill Site in Atwater Valley Block 14

Members of the Gulf of Mexico Hydrates Research Consortium conducted a seismic study at the proposed DoE/JIP drill site in Atwater Valley Block 14 in October, 2003. The study used a surface-towed 80 in3 watergun and ship noise as sources of acoustic energy. The energy was received by a stationary 16-channel vertical line array (VLA) of hydrophones in the water column and a deep-towed single-channel hydrophone. 
The purpose was two-fold: 1) to obtain VLA and reflection profile data that could be combined to provide a 3-D model of the shallow sub-bottom beneath the site and 2) to record ship noise to be used in the development of a signal processing algorithm for monitoring changes from the 3-D model. 
The intention was to calibrate the acoustic speeds and densities at the site by processing the zero-offset SS/DR data to estimate acoustic impedances and the variable-offset VLA watergun data to estimate speeds of propagation. Combining these would produce estimates of sub-bottom densities. 
After the monitoring station is installed, a net of VLAs would provide data that could be processed by the ship-noise algorithm to detect changes in acoustic speeds. When a significant change in the speed model is detected, the site can be recalibrated to detect changes in the density model. It is expected that consideration of these changes, perhaps in combination with chemical information, will provide information on changes in the hydrate accumulation.

 

AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.