An experimental description of the double positive effect of CO2 injection in methane hydrate deposits in terms of climate change mitigation

Abstract

In this paper, the possibility of injecting CO2 into a hydrate reservoir, with the only aim of preventing methane release was investigated. Pure methane hydrates were formed and then partially dissociated, due to a provoked temperature increase of 2 °C. The same procedure was applied to a system composed by a core of CH4 hydrates and an external shell made with CO2 hydrates. In tests with only methane hydrate, that temperature increase caused partial hydrate dissociation, with a consequent increase in pressure about 7.81–8.42 bar. In presence of CO2 hydrate, the same temperature increase did not cause any dissociation, even if the new established condition were not suitable for CH4 hydrates stability. Results proved that CO2 is capable to form a strong hydrate shell around the methane core, which hinders its dissociation. Two positive contributions were reached: CO2 permanent storage and the prevention of CH4 release in the atmosphere.