Huitong Wang

Analysis of condensate oil by comprehensive two-dimensional gas chromatography

Abstract Twenty-two condensate oil samples from the Sichuan Basin are analyzed by comprehensive two-dimensional gas chromatography (GC×GC). Light hydrocarbon components are separated completely without the influence of co-eluting peaks, and the fingerprint information of light fraction such as propane remains intact. Sixty-seven compounds are detected in the range of nC3-nC8 by using GC×GC, 13 more than the compounds recognized in the conventional gas chromatography (GC). These compounds are divided into 12 compound classes by GC×GC according to the structure. Coupled with flame ionization detector (FID), some compounds that can not be analyzed quantitatively by other methods are quantified, including isoalkane, alkyl cyclopentane, alkyl cyclohexane, other single cycloalkane, polycyclic alkane, adamantane, alkylbenzene and polycyclic aromatic hydrocarbon and so on. The quantitative analysis results of more than 180 main compounds and the 12 compound classes by GC×GC will offer more technical assistance for petroleum geochemical researches to get new parameters of maturity estimation and oil-source correlation of condensate oil.

Insight of unresolved complex mixtures of saturated hydrocarbons in heavy oil via GC×GC-TOFMS analysis

The saturated hydrocarbon fraction of a heavily biodegraded crude oil from Liaohe oilfield was analyzed by using comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-TOFMS). The “humps”, which was termed as unresolved complex mixtures (UCMs) in conventional gas chromatographic analysis, was separated for identification of the individual compound. Main compounds of UCMs were identified according to the combined information of characteristics of GC×GC chromatogram and time-of-flight mass spectra. It’s found that UCMs are mainly composed of great number of ring compounds with extremely low concentration. The ring compounds are separated according to their boiling point diversity in the first dimension column, then to their polarity or ring number variety in the second dimension column. In the sample there are two groups of UCMs, i.e., the first group compounds with boiling point lower that of C24 and the second group compounds with boiling point higher than that of C24. The first group of UCMs mainly consists of monocyclic, bicyclic and tricyclic ring compounds. The first group of UCMs is mainly composed of saturated hydrocarbons, in which the percentage of ring compounds with signal-to-noise ratio above 100 is about 75% of the total quantity of saturated hydrocarbon, while its mass is over 80% of the total saturated hydrocarbon. The second group of UCMs is mainly composed of tetracyclic and pentacyclic ring compounds, in which the percentage of UCM compounds with signal-to-noise ratio over 100 is about 17% of the total quantity of saturated hydrocarbon, and its mass is about 0.5% of the total saturated hydrocarbon. The results of this study are helpful for heavy oil developing and genesis mechanism understanding.

A new analytical method for quantifying of sterane and hopane biomarkers

An analytical method for quantifying biomarker compounds of the sterane and the hopane existing in saturated hydrocarbons has been established by using comprehensive two-dimensional gas chromatography-flame ionization detector (GC×GC-FID) with optimized operating parameters. The new method achieves the quantification by using a GC×GC-FID system which is able to completely separate steranes from hopanes. The data obtained by the new method are of good repeatability and reliability. Compared with the original data, the relative standard deviations (RSDs) of 12 reference compounds are less than 5%. The RSDs of the quantitative results of the biomarkers based on seven separate analyses are also less than 5%. Compared with the traditional method of gas chromatography-mass spectrometry (GC-MS), the new method has a number of advantages, such as common internal standards (ISs), high resolution, no co-eluting peak, and no interference caused by diagnostic ion peaks. The new method provides petroleum geologists with an effective and scientific means in future researches.