珠三坳陷文昌组中深湖相烃源岩新的生物标志化合物组合模式与油源对比

原油样品和不同相带烃源岩样品的地球化学分析结果表明,珠三坳陷文昌组中深湖相烃源岩具有低丰度C304-甲基甾烷,并在C29甾烷上有强共逸出峰(X峰),这种新的生物标志化合物组合模式在南海北部盆地尚属首次提出。依据这一新的生物标志化合物组合模式对珠三坳陷油源重新进行了对比分析,认为文昌B凹陷主力烃源岩是文昌组中深湖相烃源岩,文昌A凹陷主力烃源岩是恩平组河沼相烃源岩;文昌B凹陷区原油的主要贡献者是文昌组中深湖相烃源岩,文昌A凹陷区原油的主要贡献者是恩平组河沼相烃源岩,而琼海凸起西区原油主要源自文昌B凹陷文昌组中深湖相烃源岩,琼海凸起东区原油则主要源于文昌A凹陷恩平组河沼相烃源岩。

A new biomarker combination in the Wenchang Formation source rock of middle-deep lacustrine facies and oil-source correlations in Zhu Ⅲ depression

In Zhu Ⅲ depression,the geochemical analyses of crude oil samples and source rock samples of different depositional facies have indicated that there are a low abundance of C304-Me-Steranes and an X peak co-eluted strongly with C29 steranes in the Wenchang Formation source rock of middle-deep lacustrine facies.This new biomarker combination was firstly reported in Northern South-China-Sea basin.By using this new biomarker combination to make oil-source correlations and analyses afresh in Zhu Ⅲ depression,it is considered that the middle-deep lacustrine facies in Wenchang Formation is the major source rock in Wenchang B sag,and the swamp facies in Enping Formation is the major source rock in Wenchang A sag.Meanwhile,oil in the western Qionghai uplift primarily came from the Wenchang Formation source rock of middle-deep lacustrine facies in Wenchang B sag,and oil in the eastern Qionghai uplift mainly from the Enping Formation source rock of swamp facies in Wenchang A sag.