Water content and hydrate dissociation conditions for carbon dioxide rich fluid

Abstract

Water solubility data in CO2 are important for flow assurance and mitigation of corrosion issues during transportation in carbon capture, sequestration/storage and acid gas reinjection processes. Hydrate formation conditions, as well as solubility of CO2 in water, have been well studied in the literature; however, there are relatively few studies for CO2 liquid in equilibrium with a hydrate as a two-phase system. Moreover, there is a disparity between the various data regarding the pressure dependence of the water content of the CO2 in this system. In this work, we report the water content in CO2liquid at p = 7.893–50.91 MPa and T = 237.86–278.21 K, where the CO2 phase is in equilibrium with only the pure type I hydrate. Our results support a very weak dependence on pressure, which can be expected with an equilibrium involving two relatively incompressible materials. In addition, new measurements are reported for the Lw-H-CO2(g) and Lw-H-CO2(l) phase boundaries for p = 1.262–15.596 MPa and T = 273.42–284.32 K using a 25 cm3 stirred autoclave cell. A full equilibrium model is described where the fluid phase was modeled using reference Helmholtz Equations of State for CO2 and water, and the Sloan et al. (1987) model is used for the hydrate phase.