The distribution models of naturally occurring gas hydrates in sediments are diverse and have significant influence on physical properties of rocks. In this work, acoustic properties of hydrate-bearing sediment with homogeneous distribution or heterogeneous distribution were investigated using an in situ measurement apparatus, in which methane was used as a free gas for forming hydrate. Hydrate-bearing sediments with homogeneous or heterogeneous distribution were synthesized by controlling the system temperature and water migration. The influence of water migration as a result of gravity along with the rising temperature on acoustic properties was examined during the hydrate formation process. The results showed that the memory effect was proved to be exist from macroscopic scale. Hydrate distribution and concentration are all of great significance to the acoustic characteristics for hydrate deposits. And it was found that the P-wave velocity of the hydrate deposits with homogeneous distribution is faster than that with heterogeneous distribution when under a same hydrate saturation.
Keywords hydrate, P-wave velocity, water migration, homogeneous distribution, heterogeneous distribution