The elastic wave velocities of hydrate-bearing sediments (HBS) are considerably affected by the content of free gas and hydrate. Although several existing models relate the free gas and hydrate saturation to acoustic velocities, the accuracy of these models is still uncertain because of the difficulty in determining the gas content. In this study, we acquired the gas volume fraction and acoustic velocity data of the hydrate-bearing sands through a X-ray computed micro-tomography (CT) and an ultrasonic apparatus, respectively. The acoustic velocities increase slowly at low hydrate saturation (S_h < 33%), whereas they increase rapidly when hydrate saturation exceeds 33%. Using the measured data, we verified three commonly used velocity models, namely, the Biot-Gassmann theory by Lee (BGTL), effective media theory (EMT), and simplified three-phase equation (STPE). The results obtained using the BGTL are consistent with the experimental results when hydrate saturation exceeds 45%, while the EMT-B model is more suitable for predicting P-wave velocity (V_p) when the hydrate saturation varies from 15% to 55%. The value of V_p calculated by the STPE model, without considering the effects of gas on velocity, is higher than the experimental value. We further applied a new method combining the Wood and Domenico equations to calculate the bulk modulus of HBS containing methane gas, which can improve the precision and applicability of the STPE model. Compared with the EMT and BGTL models, the modified STPE model is more suitable for predicting V_p of unconsolidated reservoirs with high porosity and permeability. These results provide a new method for further experimental research and a theoretical reference for accurately estimating hydrate saturation through logging data during natural gas exploration and development.

含水合物沉积物（HBS）的弹性波速度受游离气体和水合物含量的很大影响。尽管现有的几种模型将游离气体和水合物的饱和度与声速相关联，但是由于确定气体含量的困难，这些模型的准确性仍不确定。在这项研究中，我们分别通过X射线计算机断层扫描（CT）和超声设备获得了含水合物砂的气体体积分数和声速数据。在低水合物饱和度（S _h时，声速缓慢增加 <33％），而当水合物饱和度超过33％时，它们会迅速增加。利用实测数据，我们验证了三种常用的速度模型，即Lee的Biot-Gassmann理论（BGTL），有效介质理论（EMT）和简化的三相方程（STPE）。当水合物饱和度超过45％时，使用BGTL获得的结果与实验结果一致，而当水合物饱和度从15％变为55％时，EMT-B模型更适合于预测P波速度（V _p）。V _p的值在不考虑气体对速度的影响的情况下，由STPE模型计算的结果要高于实验值。我们进一步应用了结合Wood和Domenico方程的新方法来计算含HBS的甲烷气体的体积模量，这可以提高STPE模型的精度和适用性。与EMT和BGTL模型相比，改进的STPE模型更适合于预测具有高孔隙率和渗透率的未固结油藏的V _p。这些结果为进一步的实验研究提供了一种新方法，并为通过天然气勘探和开发过程中的测井数据准确估算水合物饱和度提供了理论参考。