混合介质对降温法形成甲烷水合物性质的影响

目前,对沉积物中天然气水合物形成与分解性质的研究主要是在单一介质中进行,但自然界中的天然气水合物主要赋存于混合介质沉积物中。因此,有必要考察不同介质类型对天然气水合物形成的影响。为此,将粗砂、细砂、粉土3种介质按不同方法混合,搭配出6种混合型介质,并采用降温法在其内生成甲烷水合物,研究介质类型对甲烷水合物形成性质的影响及在降温过程中不同介质消耗甲烷气体的特点,为研究介质内水合物形成机制提供理论基础。实验装置由供气、反应和数据采集3个系统组成。结果表明:①不同单一介质对水分的吸持力差别很大,介质混合后水分在其内的分布状态及水分子在介质表面的吸附排列存在较大差异,从而使不同混合型介质内甲烷水合物的最终生成形态不同;②介质类型不仅会影响其内甲烷水合物的形成过程,而且会影响水合物的含气率;③不同介质内甲烷水合物生长过程所处的时间阶段不同。

Impacts of a mixed medium on the properties of methane hydrate generated with a falling temperature technique

Currently an experimental study on formation and decomposition of gas hydrate in deposits is mainly carried out in a single medium, while gas hydrate in nature mainly occur in the deposits of a mixed medium, thus it is essential to study the impacts of different types of medium on the formation of gas hydrate. Coarse sand, fine sand and silt were mixed in different proportions to generate 6 kinds of mixed medium, in which gas hydrate was created by using the falling temperature method. We studied the impacts of different media on the properties of methane hydrate and the characteristics of methane consumption in the process of lowering temperature, so as to provide a theoretical basis for the research of gas hydrate forming mechanism. The experimental apparatus consists of 3 systems including gas supply, reaction, and data acquisition. The following conclusions were obtained from the experiments. ①Every single medium has much different adsorption force to water, but after being mixed, the distribution of water in this mixed medium, as well as the adsorption and alignment of water molecular on the medium surface, change greatly, resulting in different final shapes of methane hydrate in different mixed medium. ②The types of medium can influence not only the process of methane hydrate formation, but also the gas content of gas hydrate. ③The time period of methane hydrate growth in different media are not the same.