Abstract: The methane hydrate was formed in an experimental vessel under two temperature cooling profiles, i.e. slowly and rapidly decreasing the temperature. The results show that the methane hydrate forming process consists of four stages with the two cooling profiles, gas/water dissolution, nucleation, growth and stable states. The temperature profiles have no obvious effect on the thermodynamic equilibrium of hydrate formation. However, they have a great effect on the hydrate growth kinetic process. Comparing the two cooling profiles under the same initial conditions, the methane hydrate growth rate was remarkably faster in the rapid cooling case than that in the slow cooling case, resulting in about 21.4%~28.8% reduction of hydrate growth time, depending on the initial forming conditions.

Key words: methane hydrate, sediments, isochoric formation, cooling profile

摘要： 在定容条件下，以两种不同的降温模式(缓慢降温和快速降温)进行甲烷水合物在沉积物中的形成实验. 结果表明，甲烷水合物在沉积物中的形成过程包括气液溶解、核化、生长、稳定4个阶段. 在相同的初始条件下，降温模式对水合物生成的热力平衡影响较小，但对水合物生成动力学有显著改变. 快速降温下水合物生长速度明显快于缓慢降温，随着水合物初始条件不同，缓慢降温比快速降温水合物形成时间约增加21.4%~28.8%.

关键词: 甲烷水合物, 沉积物, 定容形成, 降温模式