Energy Density refers to the volume of gas stored within a given volume of space in the subsurface. When gas hydrate is dissociated – the gas that is released will expand or contract in response to ambient pressure. When that gas is brought to the surface, it will expand roughly 164x times the volume it occupies in the subsurface. This ratio is independent of the depth at which it occurs, because the rigid hydrate lattice hold methane molecules at a fixed density without regard to ambient pressure. This is different than the situation with free gas, which when brought to the surface will expand by different amounts depending on depth and pressure (see FITI v.10, n.2). Schematic depiction of features observed in seismic data and their prospectivity for the potential occurrence of highly-saturated, gas-hydrate-bearing sands. (See FITI, v.14, n.2). Gas hydrate occurs in a variety of forms and in a range of environments. For more information, see Boswell, 2011 (NRC Topical Paper 1-11 )Schematic depiction of various potential triggers for gas hydrate related geohazards under both natural and operational conditions. (See FITI, v. 12, n.1). A schematic depiction of the evolution of various categories of hydrocarbon resource through time relative to major categories, including in-place resource, technically-recoverable resources, economically-recoverable resources, reserves, and produced. Gas hydrate currently has limited volumes demonstrated as technically recoverable from within a large, but poorly-constrained in-place resource. Due to lack of sufficient long-term testing, no volumes can be assessed as commercially viable at present. Simplified depictions of the stability conditions for gas hydrate in permafrost and deepwater settings. Gas hydrate is stable with the stability curve (red) exists to the right of the generalized subsurface temperature (blue). In 2009, DOE and its federal and industry partners discovered deeply-buried gas hydrates at high saturation at two sites in the deepwater Gulf of Mexico. Log Data from the Walker Ridge Block 313 G well shows the typical well log response for gas hydrate-bearing sands. For more information, see https://netl.doe.gov/node/6350
