Laboratory and field characterization of hydrate bearing sediments - implications
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The amount of carbon trapped in hydrates is estimated to be larger than in conventional oil and gas reservoirs, thus methane hydrate is a promising energy resource. The high water pressure and the relatively low temperature needed for hydrate stability restrict the distribution of methane hydrates to continental shelves and permafrost regions. Stability conditions add inherent complexity to coring, sampling, handling, testing and data interpretation, and have profound implications on potential production strategies. New guidelines are identified for sampling equipment and protocols. Then a novel technology is developed for handling, transfering, and testing of natural hydrate bearing sediments without depressurization in order to preserve the sediment structure. Natural samples from the Nankai Trough, Japan, are tested as part of this study. In-situ testing prevents dissociation and the consequences of sampling and handling disturbance. A new multi-sensor in-situ characterization tool is designed and prototyped as part of this research. The tool includes advanced electronics and allows for automated stand-alone operation. Finally, a robust analytical model is developed to estimate the amount of gas that can be recovered from hydrate bearing sediments using depressurization driven dissociation. Results highlight the complexity of gas extraction from deep sediments, and inherent limitations.