Experimental and thermodynamic modelling of systems containing water and ethylene glycol: Application to flow assurance and gas processing

Accurate knowledge of hydrate phase equilibrium in the presence of inhibitors is crucial to avoid gas hydrate formation problems and to design/optimize production, transportation and processing facilities. In this communication, we report new experimental dissociation data for various systems consisting of methane/water/ethylene glycol and natural gas/water/ethylene glycol. A statistical thermodynamic approach, with the Cubic-Plus-Association equation of state, is employed to model the phase equilibria. The hydrate-forming conditions are modelled by the solid solution theory of van der Waals and Platteeuw. The thermodynamic model was used to predict the hydrate dissociation conditions of methane and natural gases in the presence of distilled water or ethylene glycol aqueous solutions. Predictions of the developed model are validated against independent experimental data and the data generated in this work. A good agreement between predictions and experimental data is observed, supporting the reliability of the developed model. © 2008 Elsevier B.V. All rights reserved.