塔里木阿瓦提凹陷乌鲁桥油苗地化特征及来源

阿瓦提凹陷乌鲁桥油苗全油碳同位素较重(-29.4‰)。在甲基菲分布分数图版上落在高成熟油区;甲基菲比值为2.03,高于塔里木盆地现已发现的高成熟凝析油和成熟度较高的原油,表明该油苗的成熟度高。萜烷、甾烷分布具有C29Ts、重排藿烷含量低,伽玛蜡烷丰度较高,中等—高丰度C28甾烷,低重排甾烷等分布特征。这与凹陷及其周缘的石炭系—二叠系、三叠系及中—上奥陶统这三套烃源岩的明显不同,而与寒武系烃源岩相似。综合分析认为乌鲁桥油苗来源于寒武系烃源岩成熟晚期阶段生成的烃类。

Origin and Geochemical Characteristics of Wuluqiao Oil Seepage in Awat Sag, Tarim Basin

The total oil carbon of Wuluqiao oil seepage in Awati Sag has a comparatively heavy isotope of-29.4‰,which fells at the area of high maturity oil in the F1-F2 plate.The oil of the seepage shows a high MPR of 2.03,which means a higher maturity than those of other high mature condensate oil and crude oil having found in Tarim Basin.The distributions of terpane and gonane are characteristic of low abundance of C29Ts and rearranged hopane,higher abundance of gammacerane,medium-high abundance of C28-gonane,and low abundance of diasteranes,which are similar with those of the oil from Cambrian source rock but obviously different from those of oil from the Carboniferous-Permian,Triassic and Middle-Upper Ordovician source rocks in this sag and its periphery.According to multidisciplinary analysis,it concludes that the oil of Wuluqiao oil seepage is original from Cambrian source rock during the late period of hydrocarbon generation.