The effect of diffusion on the modeling of the water-washing phenomenon

The water washing of crude oil in high pressure and high temperature conditions is based on phase equilibrium between water and hydrocarbon mixtures. A new algorithm is used for describing this phenomenon, in order to take into account the diffusion rates of the individual components in water. The results are tested for different phase equilibrium models. All simulations show fast removal of light gases and aromatics, while heavier hydrocarbons are less altered. No major modification in the compositional evolution of the hydrocarbon was observed, when diffusion is taken into account. The equilibrium between water and hydrocarbon is calculated using an equation of state with the Henry's law. The available Henry's constants have been completed and a new correlation has been used and tested. It appears that this new correlation (Tsonopoulos type) improves Henry's constants for almost all available data. The Henry's constants from the Tsonopoulos type correlation predict pure component solubility for heavier hydrocarbons better.