Establishing the Maximum Carbon Number for Reliable Quantitative Gas Chromatographic Analysis of Heavy Ends Hydrocarbons. Part 1: Low-Conversion Thermal Cracking Modeling

Reservoir fluid characterization by gas chromatography (GC) has an impressive capability of detection and quantification of a wide range of single carbon number (SCN) groups in oil analyses. However, some researchers prefer to report analyses to C20+ only, with estimation of the Cn+ fraction distribution obtained using various correlations. Conversely, other researchers prefer to extend GC analysis to the highest possible SCN group using high-temperature gas chromatography (HTGC), with programming to ca. 370–430 °C. However, the reliability of extended GC analyses to high carbon number fractions is questioned because of a possible overestimation of light and intermediate fractions in the original oils caused by thermal decomposition products. The thermal stability of heavy hydrocarbons at the above HTGC conditions has been a major concern for some authors based on the results of thermogravimetric analysis (TGA) published by Schwartz et al. [Schwartz, H. E.; Brownlee, R. G.; Boduszynski, M. M.; Su, F.Anal....