注热开采产气速度的稳定性主要受温度场变化的影响,即受注水速度、注水温度和模型热物性的共同控制。应用研制的天然气水合物(NGH)合成与开采实验系统,进行NGH注热开采实验研究。该实验系统热量损失大、换热效率和热利用率较低,实验条件下的最优注水温度为81.44℃。根据实验数据得到的实际NGH藏换热效率可超过6,因此从能量角度评价注热开采是可行的。通过优化注热水的温度、速度等参数,采用“热水段塞+常温水驱替”、注热与降压联合开采、减少管线热损失等措施,可以大大提高注热开采的效益。
The gas production rate of thermal stimulation was mostly controlled by the changing of temperature field, that is to say, controlled by injection rate, water temperature and thermal properties of experimental model. Using the experimental system of natural gas hydrate(NGH) forming and production, the production behaviors of NGH by thermal stimulation were investigated. The heat loss of this thermal model is high so that the efficiencies of heat exchange and heat utilization are low. Under the experimental condition, the highest gas production efficiency is obtained by thermal stimulation when the water in-jection temperature is 81.44℃. According to the experimental data, the efficiency of heat exchange in actual NGH reservoirs can be up to 6, which indicates that production by thermal stimulation for NGH reservoir is feasible. Through a series of measures, such as optimizing temperature and rate of the water injection, applying hot water slug and normal temperature water drive, combining depressurization with thermal stimulation, lessening the heat loss in pipelines, the efficiency of thermal stimulation could be increased significantly.