Rock physics links the elastic properties of the sediment to the amount of gas hydrate present, its location in the pore space, and other parameters (porosity, mineral properties, effective pressure, and pore-fluid compressibility). These elastic properties, in turn, determine the wave speeds and, eventually, seismic signatures of natural gas hydrate reservoirs. As a result, seismic data acquired over prospective gas hydrate deposits can be interpreted in terms of gas hydrate

Hydrate in Fluid

Hydrate m Frame

Figure 5. Hydrate concentration from compressional wave velocity log data and resistivity logs, (a) Comparison of well log Vp with model results assuming that hydrate is part of the pore fluid, (b) Comparison of well log Vp and model results assuming hydrate is part of the sediment frame. For both (a) and (b), model values were calculated at core depths and the results fit with smoothed curves, (c) Hydrate concentration estimate from resistivity log.

111 /11 h concentration and location in the pore space. The rock physics approach described in this chapter has been used by Ecker et al. (2000) to predict the gas hydrate saturation of the pore space from seismic in the Blake Outer Ridge. Applying quantitative rock physics models to well log and seismic data acquired from sediments containing gas hydrate is the future of gas hydrate reservoir characterization.

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