Natural gas hydrate (NGH) dissolution may play a critical role in geological evolution and methane-induced climate change. However, the characteristics of hydrate dissolution in sediments remain poorly constrained. In this work, methane hydrate dissolution kinetics was quantitatively investigated by continuously passing methane-free water through hydrate-bearing sediments (HBS). The results showed that the methane release process can be divided into rapid and decayed stages. The hydrate dissolution process can be significantly affected by heterogeneity in the NGH distribution and dynamic variation in the flow channels. The average hydrate dissolution rate and methane flux were calculated based on the mass balance principle. With an increase in the water flux from 2.0 mL/cm/min to 4.1 mL/cm/min, the hydrate dissolution rate increased from 40.9 m/yr to 103.1 m/yr, and the methane flux increased from 23.3 mol/cm/yr to 59.0 mol/cm/yr. In comparison, the hydrate dissolution rate is less sensitive to variation in the hydrate saturation in the range of 12.8%–28.8%, with corresponding hydrate dissolution rate values ranging from 96.6 m/yr to 114.8 m/yr. The corresponding methane flux is in the range of 55.2–65.6 mol/cm/yr. The NGH dissolution associated with the undersaturated water flowing through HBS is at least one order of magnitude faster than that in other reported hydrate dissolution environments (0.03–150 cm/yr). The rapid dissolution of local hydrate may contribute to geological evolution and methane release at hydrate sites with active seepage activity.

中文翻译：

---

水流加速天然气水合物溶解：动力学和影响

天然气水合物（NGH）溶解可能在地质演化和甲烷引起的气候变化中发挥关键作用。然而，沉积物中水合物溶解的特征仍然缺乏约束。在这项工作中，通过使不含甲烷的水连续通过含水合物沉积物（HBS）来定量研究甲烷水合物溶解动力学。结果表明，甲烷释放过程可分为快速阶段和衰减阶段。水合物溶解过程会受到水合物分布的不均匀性和流道的动态变化的显着影响。根据质量平衡原理计算了平均水合物溶解速率和甲烷通量。随着水通量从2.0 mL/cm/min增加到4.1 mL/cm/min，水合物溶解速率从40.9 m/yr增加到103.1 m/yr，甲烷通量从23.3 mol/cm/yr增加至 59.0 摩尔/厘米/年。相比之下，水合物溶解速率对水合物饱和度在12.8%~28.8%范围内的变化不太敏感，相应的水合物溶解速率值范围为96.6 m/yr~114.8 m/yr。相应的甲烷通量在 55.2–65.6 mol/cm/yr 范围内。与流经 HBS 的不饱和水相关的水合物溶解至少比其他报道的水合物溶解环境（0.03-150 厘米/年）快一个数量级。当地水合物的快速溶解可能有助于渗流活动活跃的水合物地点的地质演化和甲烷释放。