Kinetic analysis of nano-SiO2 promoting methane hydrate formation in porous medium

Abstract

Natural gas hydrates are abundant and occur globally. The storage and transportation of natural gas in the form of hydrates is considered to be an efficient method limited by low formation rates. In this study, the kinetic effects of SiO2 nanofluids and porous medium on hydrate formation were studied by using magnetic resonance imaging (MRI) technology. The SiO2 nanofluid concentration was varied from 0.1 to 0.4 wt% to analyze its influence. The results showed that hydrates formed near the wall and grew into pores with sufficient water. The concentration variation study revealed a significant decrease in induction time and increase in gas consumption during hydrate formation. Among the various concentrations studied, 0.2 wt% had the strongest promoting effect, and the induction time was shortened by 75.7%, while the gas consumption was 67.7% higher than that in pure water at an initial water saturation of 30%. Concentrations of 0.1–0.3 wt% positively influenced the hydrate formation rate, but a concentration of 0.4 wt% significantly inhibited hydrate formation. In addition, hydrate formation was affected by the initial water saturation of the porous medium. The lower the initial water saturation was, the more notable the promotion effect was. This study provides theoretical support for the storage and transportation of natural gas by combining porous medium and nanofluids.