Abstract:

To understand the acoustic characteristics of gas hydrates in different media, the ultrasonic detecting technology is applied to the experimental study of gas hydrates in the pure water,the unsolidified sediment, and the core sample,respectively. The P-wave velocity is positively correlated with temperature linearly in the pure water, it means that the change of P-wave velocity is mostly caused by  temperature but unobviously by the cotton-like gas hydrate formed in the water. In the long time experiment in the pure water, unsolidified sediments, and methane system, the change of P-wave velocity and characteristic frequency sensitively indicated the formation and dissociation of gas hydrate in the experimental system. The velocity of P wave and S wave, along with the amplitude of P wave, increased when gas hydrate formed in the pore water of the core sample. It is concluded that the velocity of P wave and S wave increase when the porosity of sample decreases, while the decay of the P-wave amplitude decreases. All the experimental results reveal that ultrasonic detecting technology is effective when it is applied to the experimental study of gas hydrate.

Key words: gas hydrate, ultrasonic detecting technology, simulating experiment, P wave, S wave