Physical properties of hydrate-bearing sediments

Author Posting. © American Geophysical Union, 2009. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Reviews of Geophysics 47 (2009): RG4003, doi:10.1029/2008RG000279.Methane gas hydrates, crystalline inclusion compounds formed from methane and water, are found in marine continental margin and permafrost sediments worldwide. This article reviews the current understanding of phenomena involved in gas hydrate formation and the physical properties of hydrate-bearing sediments. Formation phenomena include pore-scale habit, solubility, spatial variability, and host sediment aggregate properties. Physical properties include thermal properties, permeability, electrical conductivity and permittivity, small-strain elastic P and S wave velocities, shear strength, and volume changes resulting from hydrate dissociation. The magnitudes and interdependencies of these properties are critically important for predicting and quantifying macroscale responses of hydrate-bearing sediments to changes in mechanical, thermal, or chemical boundary conditions. These predictions are vital for mitigating borehole, local, and regional slope stability hazards; optimizing recovery techniques for extracting methane from hydrate-bearing sediments or sequestering carbon dioxide in gas hydrate; and evaluating the role of gas hydrate in the global carbon cycle.This work is the product of a Department of Energy (DOE)–sponsored Physical Property workshop held in Atlanta, Georgia, 16–19 March 2008. The workshop was supported by Department of Energy contract DE-AI21-92MC29214. U.S. Geological Survey contributions were supported by the Gas Hydrate Project of the U.S. Geological Survey's Coastal and Marine Geology Program. Lawrence Berkeley National Laboratory contributions were supported by the Assistant Secretary for Fossil Energy, Office of Oil and Natural Gas, through the National Energy Technology Laboratory of the U.S. DOE under contract DE-AC02-05CH11231. Georgia Institute of Technology contributions were supported by the Goizueta Foundation, DOE DE-FC26-06NT42963, and the DOE-JIP administered by Chevron award DE-FC26-610 01NT41330. Rice University contributions were supported by the DOE under contract DE-FC26-06NT42960