Experimental Analysis on the Probability Density Distribution of Methane Hydrate Induction Times in Porous Media

Abstract

AbstractHydrate‐based natural‐gas transport and storage have been proposed and developed because of the high safety and low cost, and hydrate reformation is a serious barrier for high‐efficiency natural‐gas hydrate exploitation. The hydrate formation induction time is a crucial kinetic parameter for both of the two fields. To clarify the hydrate formation and/or reformation induction characteristics, the effects of sub‐cooling, particle size, initial water saturation and memory effect on the stochastic induction time patterns are experimentally investigated. In total, 22 cases were performed, and each case was repeated in 20–30 runs under identical conditions. The experimental results show that the distribution of CH4 hydrate induction times can be properly fitted to a lognormal distribution function. Larger sub‐cooling leads to shorter induction time and more repeatable experimental results. It is also found that shorter induction time and repeatable results can be obtained with bigger particle size. The experimental results show that 70% water saturation can be considered a critical value for hydrate formation. Memory effect of water is existed in the experiments, which can help reducing the induction time and its stochastic nature. It can be considered that the memory effect on the induction time is dominant compared with the other factors (sub‐cooling, particle size and initial water saturation).