Monitoring Sea-floor Instability Caused by the Presence of Gas Hydrate Using Ocean Acoustical and Geophysical Techniques in the Northern Gulf of Mexico
Erika Geresi, Ross Chapman, Tom McGee, Bob Woolsey, 2009. "Monitoring Sea-floor Instability Caused by the Presence of Gas Hydrate Using Ocean Acoustical and Geophysical Techniques in the Northern Gulf of Mexico", Natural Gas Hydrates—Energy Resource Potential and Associated Geologic Hazards, T. Collett, A. Johnson, C. Knapp, R. Boswell
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The northern Gulf of Mexico is characterized by an extremely heterogeneous near-surface geology that makes the geophysical identification of subsurface gas hydrate challenging, and the interpretation of data is commonly ambiguous. This chapter describes a set of novel seismic experiments designed to characterize the subsurface hydrate distribution at Mississippi Canyon Block 798 (MC798) in the northern Gulf of Mexico.
A vertical line array (VLA), specially designed for high resolution in shallow sediments, was deployed by the Center for Marine Resources and Environmental Technology (CMRET) with the general objectives of (1) acquiring very high-resolution seismic reflection profiles in 850 m (2789 ft) of water depth, (2) studying the acoustic character and features of the sea floor for evidence of sea-floor hazards, and (3) looking for evidence of subsurface gas hydrates and their properties.
Comparisons were made of the results of several seismic experiments in the area of interest in MC798, including the prototype VLA test in 2003, and conventional multi- and single-channel seismic data from previous years. In this article, these data sets were integrated to show the improved resolution of the near-surface sediments in the VLA data. Two interpretations of the geology are given; the evidence for the presence of subsurface gas hydrate is ambiguous.
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Natural Gas Hydrates—Energy Resource Potential and Associated Geologic Hazards
In September 2004, the American Association of Petroleum Geologists (AAPG) convened a Hedberg Research Conference in Vancouver, British Columbia, Canada titled "Natural Gas Hydrates: Energy Resource Potential and Associated Geologic Hazards." As a continuation of the Hedberg Research Conference in Vancouver, the conveners of the conference and the editors of this Memoir have worked with more than 150 authors and coauthors to prepare this Memoir on gas hydrates. This publication follows the goals of the Hedberg conference; however, the contents of this Memoir were expanded to include all aspects of gas hydrates in nature. This Memoir contains 39 individual contributions, ranging from long topical summaries to shorter focused research papers. This Memoir has been published in two parts, with digital versions of all the complete research papers included on the enclosed CD. The hardcopy portion of the Memoir includes abstracts and several key figures for each of the contributions along with a complete copy of a gas hydrate technical review. The digital portion of this Memoir has been organized into a series of topical sections consisting of review articles, marine gas hydrate papers, and gas hydrate laboratory and modeling studies. Because of the rapidly emerging worldwide interest in gas hydrates, this comprehensive treatise on the geology of gas hydrates will be valuable to both the gas hydrate research community and exploration/development geologists working in arctic and deep marine environments.