Deep sea NMR: Methane hydrate growth habit in porous media and its relationship to hydraulic permeability, deposit accumulation, and submarine slope stability

摘要: [1] Review of the literature reveals that nature pore-scale interactions between gas hydrates and porous media remains a matter controversy. To clarify situation, nuclear magnetic resonance (NMR) measurements have been made on methane hydrate-bearing sandstones. The samples were synthetically prepared within hydrate stability zone, at or near seafloor in Monterey Bay, California. method simulated natural deposition by flows are not thermodynamic equilibrium with surrounding earth. efficiency production was variable, as has observed elsewhere. When substantial saturations achieved, NMR relaxation time indicated tended to replace water largest pore spaces. relative permeability water, determined an NMR-based correlation, significantly reduced. magnitude this reduction also consistent formation centers pores, rather than coating grains. growth habit suggested these results is creation nodules lenses coarse, unconsolidated sediments. It scenarios which delivered efficiently atmosphere result slope failure, thereby strengthening global warming feedback mechanisms.