CO2 hydrate formation in NaCl systems and undersaturated aqueous solutions

A high-pressure experimental setup was used to obtain experimental data on the Hydrate Equilibrium (melting) Temperature (HET) of aqueous phases undersaturated with CO2, at different CO2 saturation levels and with different aqueous phase compositions (sodium chloride and sodium chloride/calcium chloride). This paper details the experimental equipment, methods, test fluids, and results. To study the phase equilibria of CO2-brine systems and further validate the results, hydrate dissociation conditions of CO2 in different concentrations of NaCl aqueous solutions were measured in the low-temperature region and over a wide range of pressure. Experimental results were compared against predictions of the simplified Cubic Plus Association Equation of State (sCPA-EoS) coupled with the van der Waals and Platteeuw solid solution theory.