A LATTICE FLUID APPROACH TO COMPLEX-MIXTURES - NATURAL-GAS AND CRUDE-OIL

Densities and vapor-liquid compositions for twelve complex mixtures (c rude oil and natural gas) are calculated using a lattice fluid model e quation of state. Fractions of the heavy ends are approximated as pseu docomponents defined in terms of their 'equivalent normal alkane'. The lattice fluid model equation of state of Sanchez-Lacombe is used, thr ee parameters are required for each pure component and one binary inte raction parameter (zeta(ij)) is required for each unlike pair. Binary interaction parameters are developed for 56 binary mixtures whose comp onents are typical of those found in petroleum systems. It is seen tha t, even though pseudocomponent are defined in very simple manner, the predicted results for multicomponent systems are comparable to or bett er than many popular alternative methods. (C) 1997 Elsevier Science B. V.