Pan Mengdi, Schicks Judith M
GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany.
School of Chemical and Bioprocess Engineering, University College Dublin, Belfield, D04V1W8 Dublin, Ireland.
Molecules. 2023 Aug 4;28(15):5887. doi: 10.3390/molecules28155887.
Considering the ever-increasing interests in natural gas hydrates, a better and more precise knowledge of how host sediments interact with hydrates and affect the formation process is crucial. Yet less is reported for the effects of sediments on structure II hydrate formation with complex guest compositions. In this study, experimental simulations were performed based on the natural reservoir in Qilian Mountain permafrost in China (QMP) due to its unique properties. Mixed gas hydrates containing CH, CH, CH, and CO were synthesized with the presence of natural sediments from QMP, with quartz sands, and without sediments under identical p-T conditions. The promoting effects of sediments regardless of the grain size and species were confirmed on hydrate formation kinetics. The ice-to-hydrate conversion rate with quartz sand and natural QMP sediments increased by 23.5% and 32.7%, respectively. The compositions of the initial hydrate phase varied, but the difference became smaller in the resulting hydrate phases, having reached a steady state. Beside the structure II hydrate phase, another coexisting solid phase, neither ice nor structure I hydrate, was observed in the system with QMP sediments, which was inferred as an amorphous hydrate phase. These findings are essential to understand the mixed gas hydrates in QMP and may shed light on other natural hydrate reservoirs with complex gas compositions.
鉴于对天然气水合物的兴趣与日俱增，更深入、精确地了解主体沉积物如何与水合物相互作用并影响其形成过程至关重要。然而，关于沉积物对具有复杂客体组成的结构II水合物形成的影响，相关报道较少。本研究基于中国祁连山冻土区（QMP）天然储层的独特性质进行了实验模拟。在相同的压力-温度条件下，在有QMP天然沉积物、有石英砂和无沉积物的情况下，合成了含有CH₄、C₂H₆、C₃H₈和CO₂的混合气体水合物。证实了沉积物无论粒度和种类如何，对水合物形成动力学均有促进作用。有石英砂和QMP天然沉积物时，冰向水合物的转化率分别提高了23.5%和32.7%。初始水合物相的组成有所不同，但在最终达到稳态的水合物相中差异变小。除了结构II水合物相外，在含有QMP沉积物的体系中还观察到另一种共存的固相，既不是冰也不是结构I水合物，推断为无定形水合物相。这些发现对于理解QMP中的混合气体水合物至关重要，可能为其他具有复杂气体组成的天然水合物储层提供启示。
