Characterization of Trinidad Gas Condensates

摘要

Characterization of reservoir fluids involves separation of the fluids into single carbon number (SCN) fractions by boiling at temperatures equivalent to the boiling points of the normal paraffins and then making measurements of the mole percentage, specific gravity, and molecular weight of each fraction. The specific gravity and molecular weight can be obtained by measurements of the SCN fractions obtained by true boiling point separations, and the mole percentage up to C_(19) can be obtained by chromatographic analysis. Such measurements have been carried out for seven Trinidad condensate samples. Plots of mole percentage against carbon number showed two discontinuities that are at variance with the generally accepted continuous exponential relationship, one at C_8 and the other at C_(13), because of isomers present in the C_7 and Cg fractions, which are also present in C_8 but at a higher percentage and similarly for C_(13). The measured weight average boiling point, specific gravity, and molecular weight of each fraction when compared with generalized published data showed a difference of less than 4.0%. This new observation and new data should be taken into consideration when splitting the C7 plus fraction for representative equation of state predictions.