Effect of microwave on formation/decomposition of natural gas hydrate

Natural gas hydrate (NGH) reservoirs have been considered as a substantial future clean energy resource and how to recover gas from these reservoirs feasibly and economically is very important. Microwave heating will be taken as a promising method for gas production from gas hydrates for its advantages of fast heat transfer and flexible application. In this work, we investigate the formation/decomposition behavior of natural gas hydrate with different power of microwave (2450MHZ), preliminarily analyze the impact of microwave on phase equilibrium of gas hydrate,and make calculation based on van der Waals-Platteeuw model. It is found that microwave of a certain amount of power can reduce the induction time and sub-cooling degree of NGH formation, e.g., 20W microwave power can lead to a decrease of about 3A degrees C in sub-cooling degree and the shortening of induction time from 4.5 hours to 1.3 hours. Microwave can make rapid NGH decomposition, and water from NGH decomposition accelerates the decomposition of NGH with the decomposition of NGH. Under the same pressure, microwave can increase NGH phase equilibrium temperature. Different dielectric properties of each composition of NGH may cause a distinct difference in temperature in the process of NGH decomposition. Therefore, NGH decomposition by microwave can be affected by many factors.

National Natural Science Foundation of China [50676097]; State Key Development Program for Basic Research of China [2009CB219500]