Abstract:

The occurrence of gas hydrate reservoirs is a special environment that belongs to the multiple phases. The use of twophase porous medium theory can fully take into account the structure of the medium, the special nature of the fluid and gas that fill the pores among the mineral framework, the relationship between the properties of the parts and the entirety, which can accurately describe the actual stratigraphic structure, the attributes of strata, and the dynamic response of seismic waves in the rock. This study proposed a rock physics model based on the solid property of gas hydrate and the characteristics of the geological conditions, and constructed the equations of forward, reverse and bidirectional linear regression to calculate density. Taking sites of 991 A, 995 A in ODP Leg 164 as examples, the densities of gas hydrate and framework were calculated with rock density based on this model. The calculated values of the density of gas hydrates are from 0858,2 to 1055,6 g/cm3. After the calculated values were corrected, the framework densities in different depths were derived, and the distribution of favorable hydrate reservoir was identified. This study provides a new rock physics model for the research on gas hydrates.

Key words: gas hydrate, twophase medium theory, inversion, numerical calculation