柴达木盆地北缘冷湖地区原油对比

Correlation of crude oil from Lenghu area in northern Qaidam Basin

借助色谱质谱测试,对柴达木盆地北缘冷湖地区冷湖三、四、五号构造上22个原油样品的生物标志化合物组成进行了系统分析。根据萜烷和甾烷相对含量的不同,将该区原油分成为3类,即低熟单源型原油、成熟混源型原油和高熟混源型原油。对比研究表明,冷湖三号、四号构造原油链烷烃表现为nC20前低分子量优势,五号构造原油则表现为nC21后高分子量优势,从三号至五号,原油中四环萜烷相对含量逐渐变小,而重排藿烷、重排甾烷相对含量依次增加,说明母源类型依次变差,而成熟度则依次变高。

By the help of GC-MS method, the composition of biomarkers in 22 crude oil samples from Lenghu 3, 4 and 5 structures of Lenghu area in northern Qaidam Basin have been analyzed. Based on the difference of the relative contents of terpanes and steranes, the crude oils can be divided into three groups, including low-mature single-source, mature mix-source and high-mature mix-source types. Comparative study showed that the alkane presented as low molecule hydrocarbon less than nC20was predominant in the crude oils from Lenghu 3 and 4 structures, while high molecule hydrocarbon more than nC2a was predominant in the crude oils from Lenghu 5 structure. In the crude oil from Lenghu 3 to Lenghu 5, the relative content of tetracyclic terpane was decreased, but the relative contents of rearranged hopane and rearranged sterane were increased gradually, which indicates that their organic material types were degraded, but their maturity was raised successively.