Possible Effects of a Natural Silica-Based Sand on the Thermodynamic and Kinetic Behaviour of CH4 and CO2 Hydrate Formation.

Natural gas hydrate is one of the most promising energy source present worldwide; however, before make its exploitation feasible for large-scale applications, several improvements, in terms of process efficiency, are required. In this article, a specific silica based natural sand, coming from the Mediterranean seafloor, was used as host for hydrate structures, produced in laboratory both in presence of methane or carbon dioxide. For experiments were carried out and thermodynamic and kinetic parameters were continuously monitored during hydrate formation. Then results were discussed and compared with ideal values for hydrate formation, easily found in literature. That specific sand was found to act as inhibitor for hydrate formation, in presence of both types of guests: the experimental formation curve remained constantly above the ideal one. However, several differences were found to exist between methane and carbon dioxide hydrate formation, in terms of moles of hydrate formed, saturation degree of sand pores, gas uptake, time required to complete the process and so on. Those latter differences are extremely important because they could be decisive in establishing how intervene in a specific hydrate reservoir.