Experimental analysis of the CO₂/CH₄ Replacement Efficiency due to Sodium Chloride Presence in Natural Gas Hydrates Reservoirs

University of Perugia, Engineering Department, Via G. Duranti 93, 06125, Perugia, Italy

^* Corresponding author: alberto.mariagambelli@gmail.com

Abstract

Nowadays natural gas hydrates represent a promising opportunity for counteracting several crucial issues of the 21^th century. They are a valid answer to the continuously increasing energy demand, moved by the global population growth; moreover, considering their conformation and the possibility of using them for carbon dioxide permanently storage, gas hydrates may become a carbon neutral energy source, where for each methane molecule recovered, another carbon dioxide molecule is entrapped in solid form. Considering that the combustion of one methane molecule for energy production leads to the formation of one CO₂ molecule, the hydrates exploitation can be considered a clean process in terms of impact on the climate change. This work shows how the presence of sodium chloride affects the CO₂/CH₄ replacement process into a gas hydrates reservoir. Replacement experimental results carried out in pure demineralised water were compared with the same values performed in a mixture of water and salt, having a concentration of 37 g/l. Some parameters of interest were discussed, such us methane hydrates formed before the replacement process, total amount of hydrates (composed by both species) reached at the end of the whole process, CO₂ moles that formed hydrate, quantity of hydrate present before the replacement process which were actually involved in the CO₂/CH₄ exchange and carbon dioxide amount which led to the formation of new hydrates structures.