A Multicell Equilibrium Separation Model for the Study of Multiple Contact Miscibility in Rich-Gas Drives

A multicell equilibrium flash separation model has been developed which can predict the composition necessary to develop miscibility in linear systems. The model computes the compositional changes which occur in the transition zone between the in-place oil and injected fluid and can also compute effluent volumes and compositions. Furthermore, it has the capability of incorporating phase mobilities for determination of flowing fluid compositions. This model has been run with both 3-component and real system phase equilibria data. Results show that in some cases more enrichment may be required to develop miscibility than predicted by the Benham correlation. The model has proved to be much faster computationally than a more sophisticated model that was recently described in the literature. In addition, the model compares favorably with the predictions of this more sophisticated model. The model being presented shows mathematically the effect that phase mobilities have on the eventual development of miscibility. (11 refs.)