Experimental Study of Natural Gas Hydrate Dissociation in Porous Media by Thermal Stimulation and Depressurization
多孔介质中天然气水合物注热+降压开采的实验研究

In order to investigate whether the combination of thermal stimulation and depressurization is propitious to natural gas hydrate (NGH) dissociation, experimental study was carried out by using a special-designed experimental system of NGH. NGH was formed artificially in a one-dimensional sand-packing tube. Then NGH dissociation experiment was performed by injecting hot-brine and then decreasing pressure (thermal stimulation plus depressurization). The change of temperature, resistivity, gas production rate and energy efficiency during the NGH dissociation were analyzed. Experimental results show that the process of gas production can be obviously divided into different stages. The temperature and resistivity change at measuring points reflects clearly the dynamic characteristics of NGH dissociation process. The comparison of energy efficiency from different methods shows that the energy efficiency is 1.8 when only thermal stimulation is used, and it increases to 2.88 when thermal stimulation is combined with depressurization. Above results indicate that thermal stimulation together with depressurization can achieve higher energy efficiency and is a better method for NGH dissociation.