This thesis is aimed at investigating the possibilities of using vertical line array (VLA) data to image the gas hydrate stability zone (GHSZ) in the northern Gulf of Mexico. The presence of gas hydrate can be inferred from seismic evidence such as bottom simulating reflectors (BSRs) or changes in seismic velocity. The petroliferous northern Gulf of Mexico is noted for its obvious absence of BSRs, a characteristic it shares with other active passive margins with mobile salt and/or shale, which have high propagation velocities for seismic waves. This makes the imaging and the identification of the gas hydrates a challenging process with conventional seismic techniques. Therefore. new techniques in data acquisition. processing and analysis are sought to improve the imaging of complex areas. The new, unconventional seismic data acquisition technique used here is the VELA. This work defines a seismic processing flow that has been developed to extract velocity, travel-time and amplitude information from VLA data to predict the hydrate distribution over the surveyed area. Specialized amplitude versus offset analysis and inversion is applied to the VLA data using a Bayesian inversion approach to provide estimates and uncertainties of the viscoelastic physical parameters at an interface. This thesis will compare the inversion of the 2-D seismic reflection data collected in 1998 by the USGS and in 2002 by the Center for Marine Resources and Environmental Technology (CMRET) to the VLA data collected in 2002 and 2003 by the CMRET to assess the value of a VLA in monitoring changes in the near-surface sediments that can be associated with the presence of gas hydrate.
| Identifer | oai:union.ndltd.org:uvic.ca/oai:dspace.library.uvic.ca:1828/2405 |
| Date | 30 March 2010 |
| Creators | Geresi, Erika |
| Contributors | Chapman, N. Ross, Dosso, Stanley Edward |
| Source Sets | University of Victoria |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Rights | Available to the World Wide Web |
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