Seismic Calibration of the Proposed DOE/JIP Drill Site in Atwater Valley 14 in the Gulf of Mexico: Initial Results in Expected Future Development

Erika Geresi¹, Ross Chapman², Tom McGee³, and J.R. Woolsey³. (1) MMRI, University of Mississippi, 220 Old Chemistry Bldg, University, MS 38677, phone: 662-915-7320, fax: 662-915-5625, geresie@pangea.stanford.edu, (2) School of Earth and Ocean Sciences, University of Victoria, P.O.Box 3055, Victoria, British Columbia, V8W 3P6, Canada, (3) MMRI/CMRET, University of Mississippi, 220 Old Chemistry Bldg, University, MS 38677

Gas hydrates are well known for their capacity to change the physical properties of near-surface sediments and have been linked to massive slope failures on continental margins. As drilling in the Gulf of Mexico has progressed from shallow-water shelf depths (<200m) to deep-water slope depths (>1000m), wells now penetrate the gas hydrate stability zone. In order to understand the consequences of drilling through the hydrate zone, it is imperative to understand the geological setting and the physical properties in which these hydrates exist and to be able to estimate the distribution and concentration of gas hydrate deposits especially in the subsurface.

In October 2003, the prototype Vertical Line Array (VLA) was deployed in Atwater Valley 14. The water was about 1300m deep. Runs were made on the VLA site firing a surface-towed seismic source. Simultaneously, a single-channel hydrophone array was towed beneath the source to provide a high-resolution seismic reflection profile.

Signal processing consisting of source wavelet deconvolution, trace interpolation, prestack migration/inversion, RNMO correction, amplitude calibration and true-amplitude processing was carried out on the data. Subsequently, the amplitude information was used for AVO analysis to estimate velocity, reflection coefficient, acoustic impedance. The calibrated parameters of the sediment that were determined from the analysis make it possible to construct a density model.

Gas Hydrate Exploitation, Sediment Strength, and Slope Instability Along Continental Margins II (EMD/SEPM)
AAPG Annual Meeting 2004: Embrace the Future, Celebrate the Past Technical Program