Pan Mengdi, Schicks Judith M
GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany.
Department for Earth and Environmental Sciences, University of Potsdam, 14476 Potsdam, Germany.
Molecules. 2021 May 19;26(10):3039. doi: 10.3390/molecules26103039.
Natural gas hydrate occurrences contain predominantly methane; however, there are increasing reports of complex mixed gas hydrates and coexisting hydrate phases. Changes in the feed gas composition due to the preferred incorporation of certain components into the hydrate phase and an inadequate gas supply is often assumed to be the cause of coexisting hydrate phases. This could also be the case for the gas hydrate system in Qilian Mountain permafrost (QMP), which is mainly controlled by pores and fractures with complex gas compositions. This study is dedicated to the experimental investigations on the formation process of mixed gas hydrates based on the reservoir conditions in QMP. Hydrates were synthesized from water and a gas mixture under different gas supply conditions to study the effects on the hydrate formation process. In situ Raman spectroscopic measurements and microscopic observations were applied to record changes in both gas and hydrate phase over the whole formation process. The results demonstrated the effects of gas flow on the composition of the resulting hydrate phase, indicating a competitive enclathration of guest molecules into the hydrate lattice depending on their properties. Another observation was that despite significant changes in the gas composition, no coexisting hydrate phases were formed.
天然气水合物中主要含有甲烷；然而，关于复杂混合气体水合物和共存水合物相的报道越来越多。由于某些组分优先进入水合物相以及气体供应不足导致进料气体组成发生变化，通常被认为是共存水合物相形成的原因。祁连山冻土区（QMP）的天然气水合物系统也是如此，该系统主要受孔隙和裂缝控制，气体成分复杂。本研究致力于基于祁连山冻土区储层条件对混合气体水合物形成过程进行实验研究。在不同气体供应条件下，由水和气体混合物合成水合物，以研究其对水合物形成过程的影响。采用原位拉曼光谱测量和显微镜观察来记录整个形成过程中气体和水合物相的变化。结果表明了气体流动对所得水合物相组成的影响，这表明客体分子根据其性质竞争包合进入水合物晶格。另一个观察结果是，尽管气体组成发生了显著变化，但并未形成共存水合物相。
