针对中国南海海底浅层含天然气水合物沉积物泥质粉砂岩和粉砂岩，采用超声波探测和模拟实验，研究了不同水合物饱和度与围压条件下两类沉积物的声波响应特征及差异。结果表明，围压变化条件下，两类沉积物的声波速度随围压升高而增大，围压升高至饱和点后两类沉积物的声波速度不再变化，两者的围压饱和点相差7~10 MPa；水合物饱和度变化条件下，两类沉积物的声波速度随水合物饱和度增加而增大，增速呈"慢-快-慢"趋势，其中水合物饱和度20%~40%为声波速度较快增长区间，增幅达22%以上；水合物饱和度相同、围压相同时泥质粉砂岩的声波速度均大于粉砂岩，水合物饱和度与围压变化时对两类沉积物的声波速度影响较大，且对泥质粉砂岩的声波速度影响程度大于粉砂岩。
In order to understand the acoustic characteristics and differences of muddy siltstone hydrate sediment (MSHS) and siltstone hydrate sediment (SHS) in the shallow seabed of South China Sea, a simulation experiment is conducted to investigate the acoustic response characteristics of these two hydrate sediments with the ultrasonic detection technology. The results show that the acoustic velocities of these two hydrate sediments will increase with the increase of effective confining pressure. However, when the effective confining pressure increases to the effective confining pressure saturation point, the acoustic velocities of these two hydrate sediments will not change anymore. Meanwhile, with the increase of hydrate saturation, the effective confining pressure saturation points of these two hydrate sediments will also increase. The effective confining pressure saturation point of MSHS is higher than that of SHS and the difference is between 7-10 MPa. Under the same effective confining pressure, the larger the hydrate saturation, the faster the acoustic velocity for both hydrate sediments, showing a "slow-fast-slow" tendency. The 20%-40% of hydrate saturation is the fast increasing range of the acoustic velocity, with an increase over 22%. The acoustic velocity of MSHS is greater than that of SHS under the same experiment condition. Furthermore, the change of hydrate saturation and effective confining pressure have a great effect on the acoustic velocity of these two hydrate sediments, and acoustic velocity has a greater influence on MSHS than on SHS.
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