Laboratory study of the acoustic properties of hydrate-bearing sediments

A series of laboratory experiments on the formation of hydrate-bearing samples (hydrates of methane and tetrahydrofuran (THF)) and study of their acoustic properties were done. A significant amount of experiments with ice was also performed to compare its properties with gas hydrates. Dependences of the velocities and attenuation of compressional and shear waves on hydrate saturation or initial water saturation (for ice) were obtained. For methane and ice, the most increase of compressional and shear wave velocities is observed in the area of low saturations. This correlates with the attenuation data, quick decrease of attenuation is observed in the area of low saturations for methane and ice. For THF hydrate a gradual increase of compressional and shear wave velocities with increasing hydrate saturation is observed. The differences in the velocity dependences can be explained by the different types of hydrate or ice location in the pore space and requires the use of different models of effective media for their description. For the case of THF hydrate, it is proposed to use the hydrate forming model of a non-cementing type, and for methane hydrate and ice – a cementing type.