过冷度对气体水合物合成影响的实验研究

过冷度是甲烷水合物合成过程的主要驱动力,在沉积物中进行不同过冷度下甲烷水合物合成实验,有利于找出水合物合成过程的动力学影响因素,进而研究自然界沉积物中水合物的成藏过程。在定容条件下,以不同的过冷度进行甲烷水合物在沉积物中的合成实验。实验结果表明甲烷水合物在沉积物条件下的合成过程包括气液溶解、核化、生长、稳定4个阶段。在相同初始状态,不同过冷度条件下的水合物合成后系统状态均处在相平衡曲线上,而随着过冷度的减小,气体转换率和水合物的饱和度不断降低。通过实验数据回归得出在沉积物条件下过冷度与甲烷水合物诱导时间的经验关系式。通过对比发现,沉积物中水合物合成所需要的过冷度仅为2.5℃,大大低于不含沉积物的纯水体系。

Experimental Investigation of the Supercooling Effect on Methane Hydrate Formation

The methane hydrate in the porous media is formed in the experimental vessel under the different supercooling degrees.The results show that the methane hydrate formation process consists of the four stages: gas/water dissolution,nucleation,growth and stable state.Under the same initial operation conditions,when the hydrate formation reaches a stable stage,the temperature-pressure points of the system with the different supercooling degrees are on the curve parallel with the hydrate equilibrium formation curve in the pure hydrate system.However,the conversion rate of gas into hydrate and the saturation of hydrate in the vessel decrease with the supercooling degree.The minimum supercooling degree which is necessary for the methane hydrate formation in porous is only 2.5 ℃,which was much lower than that in bulk water.