A systematic approach to characterize gas condensates and light petroleum fractions

In this work, a new technique is introduced for characterizing C6+ fraction s using an equation of state (EOS). This approach uses readily available pr operties of C6+ fractions (density, molecular weight and normal boiling poi nt) to select model molecules representing these fractions, which may then be used for predicting phase behavior. The chain of rotators group contribu tion EOS (CORGC EOS) is used in this work for characterizing the C6+ fracti ons. The validity of the proposed technique is checked by comparing predict ions with 15 sets of experimental literature data, including eight syntheti c C6+ mixtures and seven real petroleum fractions. Phase behavior predictio ns of the eight synthetic mixtures showed an total average absolute percent deviation (AAD%) of 2.33% when the known compositions were used, while a t otal AAD% of 3.58% resulted when these synthetic mixtures were characterize d using the proposed method. The characterizing method was also compared wi th. the Aasberg-Petersen and Stenby method for phase behavior predictions o f a real natural gas-crude oil mixture. Results showed that this method giv es better results for liquid phase compositions (total absolute error = 0.7 %), while the Aasberg-Petersen and Stenby method gives better results for v apor phase compositions (total absolute error = 2.36%). (C) 1999 Elsevier S cience B.V. All rights reserved.