Gas hydrate is an ice‐like form of water and low molecular weight gas stable at temperatures of roughly −10°C to 25°C and pressures of ~3 to 30 MPa in geologic systems. Natural gas hydrates sequester an estimated one sixth of Earth's methane and are found primarily in deepwater marine sediments on continental margins, but also in permafrost areas and under continental ice sheets. When gas hydrate is removed from its stability field, its breakdown has implications for the global carbon cycle, ocean chemistry, marine geohazards, and interactions between the geosphere and the ocean‐atmosphere system. Gas hydrate breakdown can also be artificially driven as a component of studies assessing the resource potential of these deposits. Furthermore, geologic processes and perturbations to the ocean‐atmosphere system (e.g., warming temperatures) can cause not only dissociation, but also more widespread dissolution of hydrate or even formation of new hydrate in reservoirs. Linkages between gas hydrate and disparate aspects of Earth's near‐surface physical, chemical, and biological systems render an assessment of the rates and processes affecting the persistence of gas hydrate an appropriate Centennial Grand Challenge. This paper reviews the thermodynamic controls on methane hydrate stability and then describes the relative importance of kinetic, mass transfer, and heat transfer processes in the formation and breakdown (dissociation and dissolution) of gas hydrate. Results from numerical modeling, laboratory, and some field studies are used to summarize the rates of hydrate formation and breakdown, followed by an extensive treatment of hydrate dynamics in marine and cryospheric gas hydrate systems.

中文翻译：

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甲烷水合物形成和分解的时标和过程及其在地质系统中的应用

天然气水合物是一种冰状的水和低分子量气体，在地质系统中稳定在大约-10°C至25°C的温度和约3至30 MPa的压力下。天然气水合物可螯合地球上约六分之一的甲烷，主要发现于大陆边缘的深水海洋沉积物中，但也存在于多年冻土地区和大陆冰盖下。当天然气水合物从其稳定场中移出时，其分解会影响全球碳循环，海洋化学，海洋地质灾害以及地圈与海洋-大气系统之间的相互作用。天然气水合物分解也可以作为评估这些矿床资源潜力的研究的一部分人为驱动。此外，对海洋-大气系统的地质过程和扰动（例如，温度升高）不仅会导致解离，还会导致水合物的更广泛溶解，甚至在储层中形成新的水合物。天然气水合物与地球近地表物理，化学和生物系统各个方面之间的联系使得对影响天然气水合物持久性的速率和过程进行评估是一个适当的百年纪念大挑战。本文回顾了甲烷水合物稳定性的热力学控制，然后描述了在天然气水合物的形成和分解（离解和溶解）过程中动力学，传质和传热过程的相对重要性。来自数值模拟，实验室和一些现场研究的结果用于总结水合物形成和分解的速率，