Effects of sediment characteristics on gas hydrate accumulation; continental margins and permafrost; model results from 2018

The occurrence of methane hydrate in marine reservoirs often correlates with the physical properties of the host sediments. High hydrate saturations (greater than 60% of the pore volume) found in association with coarser-grained strata have been attributed to both enhanced advective transport through more permeable sediment layers and to perturbations in phase equilibrium related to pore-space geometry that results in increased diffusive transport. To assess the relative importance of these mechanism in controlling hydrate occurrence, we developed a 1D (1-dimensional) model for hydrate growth along dipping, coarse-grained layers embedded in a fine-grained sediment package. We explicitly account for pore-size effects on methane solubility and permeability-driven variations in fluid flux. We show how the vertical distribution of hydrate varies in response to changes in grain size and rates of fluid advection, sedimentation, and in situ methane production. As an example, we use our model to simulate centimeter-scale variations in hydrate saturation observed at Walker Ridge Block 313, Hole H in the Gulf of Mexico. The model m-files and parameter text files are contained in this dataset. The results from this study are published by Brandon P. van der Beek and Alan W. Rempel as “On the importance of advective versus diffusive transport in controlling the distribution of methane hydrate in heterogeneous marine sediments”, doi: 10.1029/2017jb015298, Journal of Geophysical Research, 2018.

海洋储层中甲烷水合物（methane hydrate）的赋存通常与宿主沉积物的物理性质密切相关。已观测到的高饱和度甲烷水合物（超过孔隙体积的60%）多与粗粒地层伴生，其成因可归结为两类机制：一是流体可通过渗透性更强的沉积物层实现强化对流输运；二是孔隙空间几何形态引发的相平衡扰动，可增强扩散输运过程。为评估上述两类机制在控制水合物赋存过程中的相对重要性，我们构建了一维（1-dimensional）模型，用于模拟嵌入细粒沉积物组合中的倾斜粗粒层内的水合物生长过程。我们在模型中明确考虑了孔隙尺寸对甲烷溶解度的影响，以及渗透率驱动的流体通量变化。我们阐明了水合物的垂向分布如何随粒度、流体对流速率、沉积速率及原位甲烷生成速率的变化而改变。作为示例，我们利用该模型模拟了墨西哥湾沃克岭（Walker Ridge）313区块H井中观测到的水合物饱和度厘米级空间变化。本数据集包含模型的M文件（m-files）与参数文本文件。本研究成果由Brandon P. van der Beek与Alan W. Rempel发表于《Journal of Geophysical Research》2018年期刊，论文标题为《On the importance of advective versus diffusive transport in controlling the distribution of methane hydrate in heterogeneous marine sediments》，DOI编号为10.1029/2017jb015298。