冰点以下石英砂中二氧化碳水合物的生成特性

Formation Behaviors of Carbon Dioxide Hydrate in Quartz Sands Below Freezing Point

多年冻土区作为天然气水合物赋存的主要区域备受人们的关注,其常年较低的环境温度和复杂的地质条件使水合物的生成过程十分复杂,因而模拟冻土区环境条件进行水合物生成特性的研究具有重要意义.为了研究冰点以下多孔介质中二氧化碳水合物的生成过程的压力变化、生成速率、冰粉转化率等生成特性,在定容条件下,进行了初始生成压力为3、2.5和2MPa,温度为272.65、271.15和268.85K条件下二氧化碳水合物在多孔介质中的生成实验.研究结果表明:在相同的温度下,初始压力越大,反应速率越快,但初始压力对最终压力的变化幅度和冰粉的最终转化率影响不明显;在相同的初始压力下,温度越高,反应速率越快,最终压力的变化幅度越大,最终的冰粉转化率也越高.在本实验条件下,水合物生成速率最大为0.0000718mol·h-1,冰粉转化为水合物的比例最高为67.32%.

The people have paid more attention to permafrost region regarded as the main occurrence area of gas hydrate.It makes hydrate formation complicated due to its low ambient temperature and complex geological conditions.But it is of great significance to study the characteristics of hydrate formation by simulating the environment conditions in the permafrost region.In order to study the formation behaviors of carbon dioxide hydrate in porous media below freezing point,such as pressure change,reaction speed and ice conversion,the carbon dioxide hydrate formation experiments were carried out in a constant volume at three initial pressures of 3,2.5 and 2 MPa and three temperatures of 272.65,271.15 and 268.85 K.The experimental results indicate that the speed of the hydrate formation increases with the increase of the initial pressure at the same experimental temperature,but it has a slight effect on the fluctuation of the final pressure compared with the initial pressure and the final conversion rate of ice.At the same initial pressure,the reaction speed,the magnitude of the final pressure change and the final ice conversion increase with the increase of the experimental temperature.At the experimental conditions in this study,the highest hydrate formation rate is up to 0.0000718 mol·h-1 and the highest ice conversion is up to 67.32%.