川西北地区的飞仙关组为一受龙门山岛链控制的混积台地,主要堆积了一套灰色碳酸盐岩与紫红色泥页岩沉积,由于有机碳含量很低,其不可能成为有效的烃源岩,但野外调查和钻井发现,飞仙关组灰岩晶洞或裂缝中都存在一些残余原油。根据一些残余原油的色谱特征、族组成碳同位素和生物标志化合物分布特征,认为该组灰岩晶洞或裂缝中的油是寒武系泥质烃源岩在生油高峰期生成的原油经历了不同程度的生物降解和长距离的运移后,在多期构造幕作用下,多次充注、破坏、变迁的次生残留物。

In the period of Feixianguan, the northwest of Sichuan was a platform which was controlled by Longmen mountain island chain.Deposited in here was a set of grain carbonate and purplish red shale.Poor at the contend of organic carbon,it is impossible to be available for source rock.Based on the comprehensive study of gas chromatographic,carbon isotope and biomarker of the residual oil,it is believed that the oil is the product which was generate by argillaceous source rock of Cambrain.in oil-generation peak.