The index properties (e.g., water content, bulk density, void ratio, porosity) of reconstituted samples typically are calculated from the known mass of solids and water used to form the specimen. These calculations can then be checked with volumetric measurements. The reverse is true for "undisturbed" natural samples containing gas hydrate. Differences between porosity measurements can approximately be accounted for by the expansion of water to ice (about 9%) and water to gas hydrate (about 26%). The amount of methane present, in moles, is determined from the equation-of-state relationships presented by Duan et al. (1992).
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