Ranking of C6+ Composition Split Schemes of Pipeline Gas for Hydrocarbon Dewpoint Determination

Abstract

For energy calculation and hydrocarbon dewpoint calculation of pipeline gas, many gas processors and end-users are now applying equation of state, either a Peng-Robinson (PR) or Soave-Redlich-Kwong (SRK) equation of state, to the pipeline gas composition after splitting the C6+ component into a fixed ratio of n-hexane, n-heptane and n-octane: varying predictions are obtained because the commonly used percentage C6+ composition splits published in GPA standard are based on empirical studies of most pipeline gases. In addition, several different software packages are available to the industry to perform dew point calculations, and each of these may yield different predictions using the same gas compositions and equations of state. This work therefore presents the ranking of the common C6+ split schemes for hydrocarbon dewpoint determination on the basis of C6+ mole fraction through the study of several common C6+ composition splits of pipeline gas applied to a large set of field and hypothetical C6+ data by means of HYSYS(with PR EOS and SRK EOS for predicting hydrocarbon dewpoint.