Experimental acoustic measurements on unconsolidated sandy samples containing methane hydrate

The paper discusses the results of a long experiment to study the acoustic properties of an unconsolidated sand sample containing methane hydrate. The experiment was consisted of two stages: maintaining constant thermobaric conditions corresponding to the stability of methane hydrate and linear temperature variations. As a result, two effects were found: a decrease in the velocities of both compressional and shear waves during long exposure of the hydrate-bearing sample, as well as the temperature dependence of the acoustic properties – velocities. The velocities decreased with temperature increasing. Near the stability boundary of methane hydrate the velocities decreasing is stronger. During long exposure of the sample for about 400 hours, the velocities of the compressional and shear waves dropped by 5.3% and 4.4%, respectively. These effects can have a significant impact on the interpretation of results of experiments with hydrate-bearing samples and should be taken into account.