Gas hydrate is regarded as a kind of important energy resource in the recent decades. The identification of gas hydrate is a hot issue for researchers all over the world in order to exploration and exploitation. Previous research shows some methods to identify gas hydrate, but these methods also have shortcomings in different actual conditions. It is still a difficult problem to distinguish gas hydrate accurately from marine sediments. Here we propose a cross plot analysis of velocity to identify gas hydrate. Firstly, we simulate different minerals bearing sediments by rock physics models to obtain different physical properties. After a series of experiments, the results show that there are obvious differences between gas hydrate bearing sediments and other minerals bearing sediments in P-wave and S-wave velocity. Therefore, the cross plot of velocity can be used to distinguish gas hydrate qualitatively. Finally, we verify the cross plot method using the data in the Ocean Drilling Program (ODP) Leg 204 expedition of the Hydrate Ridge along the Oregon continental margin, where gas hydrate is confirmed via logging. The hydrate identification results of actual velocity data by cross plot analysis are generally in keeping with the results of core samples. Moreover, using the cross plot method also can estimate gas hydrate saturation range, which is in accordance with the measurement of chloride (Cl⁻) concentration in most cases.

天然气水合物被认为是近几十年来的一种重要能源。天然气水合物的鉴定是全世界研究人员进行勘探和开发的热点问题。先前的研究显示了一些识别天然气水合物的方法，但是这些方法在不同的实际条件下也存在缺陷。准确区分天然气水合物和海洋沉积物仍然是一个难题。在这里，我们提出了速度交叉图分析，以识别天然气水合物。首先，我们通过岩石物理模型模拟了不同的含矿物质的沉积物，以获得不同的物理性质。经过一系列的实验，结果表明，含气水合物的沉积物与其他含沉积物的矿物在P波和S波速度上存在明显差异。所以，速度的交叉图可用于定性区分天然气水合物。最后，我们使用俄勒冈州大陆边缘水合物海岭的海洋钻井计划（ODP）腿204探险队中的数据验证了交叉绘图方法，该区域通过测井证实了天然气水合物。通过交叉图分析得出的实际速度数据的水合物识别结果通常与岩心样品的结果一致。而且，使用交叉图法还可以估算出天然气水合物的饱和范围，这与氯化物（Cl 通过交叉图分析得出的实际速度数据的水合物识别结果通常与岩心样品的结果一致。而且，使用交叉图法还可以估算出天然气水合物的饱和范围，这与氯化物（Cl 通过交叉图分析得出的实际速度数据的水合物识别结果通常与岩心样品的结果一致。而且，使用交叉图法还可以估算出天然气水合物的饱和范围，这与氯化物（Cl⁻）在大多数情况下集中。