稠油中饱和烃复杂混合物成分解析及其意义

利用两根极性不同的毛细柱，在全二维气相色谱上分析辽河油田遭受严重生物降解形成的稠油饱和烃组分，可以将传统色谱分析时形成的“基线鼓包”即不可分辨的复杂混合物（Unresolved Complex Mixtures）分开．根据饱和烃全二维气相色谱谱图的族分离特点和瓦片效应，结合飞行时间质谱提供的质谱信息初步解析不可分辨的复杂混合物主要成分．发现常规色谱分析时形成的所谓“基线鼓包”是由成千上万、含量相对较低的不同取代基的环状化合物组成，这些化合物在一维色谱上以分子量递增的顺序排列，在二维色谱上以极性的差异或者环的多少排列．C24之前的第一组不可分辨的复杂混合物主要由环己烷为基本单元的单环、双环和三环烷烃类化合物组成，信噪比在100以上的化合物数量约为饱和烃总数量的75％，质量分数是饱和烃总量的80％以上，是饱和烃的主要组成部分．C24之后出现的第二组不可分辨的复杂混合物主要由四个环或者五个环为基本单元的化合物组成，信噪比在100以上的化合物数量约为饱和烃总数量的17％，质量分数是饱和烃总量的0．5％．对稠油中这些不可分辨的复杂混合物的解析有助于对其成因机理的认识和高效开采方案的制定．

Insight of unresolved complex mixtures of saturated hydrocarbons in heavy oil via GCxGC-TOFMS analyses

The saturated hydrocarbon fraction isolated from a heavily biodegraded crude oil from Liaohe oilfleld was analyzed by using comprehensive two-dimensional gas chromatography （GCxGC）. The rising baseline or ＂humps＂, which are termed as unresolved complex mixtures （UCMs） and displayed in conventional gas chromatographic analysis, were separated for complex compounds identification. Main compounds of UCMs are identified according to the combined information of characteristics of GCxGC chromatogram and time-of-flight mass spectra. It is found that UCMs are mainly composed of great number of ring compounds with extremely low concentration. The ring compounds are ranked according to their boiling point diversity in the first dimension column, then to their polarity or ring number variety in the second dimension column. There are two groups of UCMs in the sample. The compound boiling point of the first group is lees than that of C24 and the second is more than C24. The first group of UCMs mainly is composed of monocyclic, bicyclic and tricyclic ring compounds which are cyclohexane ring isomerides. In the first group of UCMs, the ratio 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. It is mainly composed of saturated hydrocarbons. The second group of UCMs is mainly composed of tetracyclic and pentacyclic ring compounds. The percentage of UCM compounds whose signal-to-noise ratio was above 100 is about 17% of the total quantity of saturated hydrocarbon, and its mass is about 0.5% of the total saturated hydrocarbon. The complex compounds analyses will benefit heavy oil developing and genesis mechanism understanding.