NEAR-CRITICAL PHASE-BEHAVIOR OF MIXTURES USING EQUATIONS OF STATE

Phase behavior calculation of hydrocarbon mixtures and gas condensate systems in the near-critical and retrograde regions is of a fundamenta l nature. Current approaches using an equation of state cannot be used reliably to calculate the phase behavior of gas condensates in the ne ar-critical region, and the use of complicated mixing rules may not yi eld reliable results. In this paper, we propose to modify the binary i nteraction coefficients. These coefficients, contrary to the current a ssumption, may not be constant (even at a given temperature), but are a function of the distance to the critical point of the system. When t his variation is accounted for, significant improvement in the descrip tion of the phase behavior around the critical point can be obtained.