2.2　Velocity Model Based on Seismic Wave Propagati...

2.2　Velocity Model Based on Seismic Wave Propagation in Three-phase Effective Medium

Carcione et al［4］use a Biot-type three-phase theory to study the relationship of the velocity of gas hydrate-bearing sediments and the concentration of gas hydrate.Three-phase theory considers the existence of two solids（grain and gas hydrate）and a liquid（water），and a porous matrix containing gas and water.There are three P waves and two S waves based on a three-phase theory proposed by Leclaire et al［6］.So there are 5velocities which are solutions of corresponding characteristic equations.Elastic parameters of sediments based on the threephase theory［4］are shown in table 2.

Table 1　Elastic parameters based on weighted time-average and Wood equation［3］

(https://www.daowen.com)

Table 2　Elastic parameters based on the three-phase theory［4］