Effect of Skeleton Grain Size on the Saturation of Gas Hydrate in Natural Sediments

Natural gas hydrate is prospected as a new and promising, highly clean energy resource that mainly occurs in permafrost or at continental margins. Its formation is subject to many soil conditions, such as grain size, matrix materials, pore morphology, and permeability. In this study, we propose that grain size is the most decisive parameter that affects the saturation of gas hydrate in sediments based on data from Ocean Drilling Program Leg 164 and Mallik 5L-38, which represent marine sediments and terrestrial sediments, respectively. Our study reveals that high gas hydrate saturation generally occurs in coarse-grained sand, regardless of whether sediment formation is homogeneous or inhomogeneous, and the sorting of sediments may affect the hydrate saturation to a certain degree. Using grain size and sorting of sediments may be the most intuitive proxy method for a rough estimation of hydrate saturation. Further study is necessary to fully understand the relationship between hydrate morphology and sediment grain size, even though massive hydrates are typically found in fine clayey-rich sediments.