Study of biosurfactant effects on methane recovery from gas hydrate by CO2 replacement and depressurization

Abstract The application of gas hydrate as a significant source of energy, which substantially contains methane, has recently attracted the consideration of many researchers. One of the essential methods of methane recovery from hydrate deposits is to inject carbon dioxide and its replacement in the hydrate structure of methane. Due to the low efficiency of this method, it is required to improve and provide other solutions to enhance the rate of replacement. In this study, depressurized and injection of rhamnolipid by carbon dioxide were investigated in porous media. Accordingly, a set of experiments was conducted to capture the effect of rhamnolipid on the kinetics of the hydrate formation growth. Further, rhamnolipid was compared to the well-known chemical surfactant, sodium dodecyl sulfate (SDS). The results of this comparison revealed that rhamnolipid was able to reduce the induction time and the total time of the process by 99% and 84% compared to SDS, respectively. In addition, it increased the amount of gas consumed by 20%, with the hydrate kinetic growth rate enhanced by seven times higher than the SDS. Generally, as this surfactant is bio-comparable and offers excellent results on the kinetics of hydrate formation, it can be promising as an eco-friendly promoter and play a valuable role in the future of methane recovery industry. The results revealed that the injection of rhamnolipid could enhance the rate of replacement process by 72.6% and the amount of carbon dioxide storage by 10% compared to the initial experiment performed without biosurfactant.