Behavior of Binary, Ternary, and Multicomponent Systems at States Similar to Those Encountered in Condensate Fields

Abstract

Abstract The growing background of experimental information concerning the volumetricand phase behavior of binary and ternary hydrocarbon systems is used as thebasis for a comparison of these systems with naturally occurring hydrocarbonmixtures under conditions representative of underground petroleum reservoirs.The qualitative and semiquantitative similarities and differences between thetwo types of systems are considered in reference to the possibilities andlimitations of using experimental data on binary and ternary systems forpredicting the volumetric and phase behavior of naturally occurring hydrocarbonmixtures of low molecular weight. The possible influence on such phase behaviorof water, hydrogen sulphide, nitrogen, and components of relatively highmolecular weight is discussed. Introduction During the past two decades much effort has been devoted to the study of thevolumetric and phase behavior of pure paraffin hydrocarbons and of binary andternary mixtures of these compounds. Many of these studies were carried outwith the direct objective of utilizing a knowledge of the detailedcharacteristics of binary and ternary mixtures of the lighter paraffinhydrocarbons for predicting the behavior of more complex mixtures. The abilityto make such predictions with accuracy would be of great value in petroleumproduction and refining. Although the behavior of the methane-propane systemserved at one time as a qualitative illustration of the probablecharacteristics of the more complex hydrocarbon mixtures found in nature, itfell fal short of requirements for quantitative predictions. The present paperendeavors to indicate the relation of the more recently accumulated informationconcerning the behavior of binary and ternary hydrocarbons to this problem. Indiscussing binary and ternary systems as examples pointing toward the behaviorof multicomponent systems no effort is made to present new methods ofpredicting the characteristics of natural hydrocarbon mixtures. Preliminaryproposals have been made elsewhere for the prediction of volumetric, phaseequilibrium, and thermodynamic data for multicomponent mixtures, utilizing as abasis the behavior of binary and ternary systems. Numerous other proposals havebeen made. That based upon the concept of a pseudo-critical state" hasmoved to be of value to the petroleum industry. T.P. 2631