Abstract: An effect of the thickening action (i.e., biodegradation, waterwashing and free oxygen oxidization) not only on sterane and ieipatre compounds but also on polycyclic aromatic compounds is found by analyses with capillary gas chromatography, Gc-Ms and carbon isotopes performed on oil samples taken from the west slope, Laohexibu Depression. Among the polycyclic aromatic compounds, naphthalene series are preferentially affected by the action, followed by phenanthrene series, chrysene series and triaromatic steroid hydrocarbons progressively. Meanwhile, the thickening action has also caused oils to have an obvious stable carbon isotope fractionation. In contrast to normal oils, heavy oils have a unique accumulation condition. Its self-sealed ability increases with its increasing specific gravity and viscosity values, making the traping mechanism quite different from that of normal oil.

摘要： 辽河西部凹陷重油的形成、分布和规模,主要取决于后期的构造运动特征,其聚集条件与常规油有一定的差别;随重油比重、粘度增大,自身封堵能力增强,可形成不同类型的油藏。我们用气相色谱、色质、碳同位素等,对辽河西斜坡系统取样样品进行分析,发现稠变作用不仅对甾萜化合物产生影响,而且对多环芳烃也有一定的影响,其影响的顺序大致是:萘系列、菲系列、(艹屈)系列、三芳甾烷系列。同时,稠变作用也会造成原油及各族组分较大幅度的稳定碳同位素分馏。