Geochemical characteristics and oil origin of crude oil in red beds of the lower of Es4 in Bonan Subsag

GC and GC-MS analysis of the extracts show that the distribution of normal alkane of crude oil in red beds in the lower part of the fourth member of Shahejie Formation appears as single-peak type, the even carbon advantage obviously from high carbon numbers C22 to C34, isoprenoid alkanes exhibits a phytane predominance, relatively high contents of gammacerane, 4-methyl steranes, pregnane and sublimation-pregnane. The content of rearranged sterane is very low, and the C35 homohopane content is higher than C34 homohopane. Triaromatic sterane content is higher in aromatic hydrocarbon, and dibenzothiophen presents in abundance in benzfhiore tri-fluorene, which show that the source rock was deposited in strong reducing environment with a large amount of sulfur in brackish-saline lake, and C2920S/(20S+20R) value ranging from 0.49 to 0.55, indicate it is a typical mature oil, and crude oil in red beds is derived from source rock of the upper part of Es4 on the basis of oil-source correlation in Bonan Subsag.EI中文核心期刊要目总览(PKU)中国科技核心期刊(ISTIC)中国科学引文数据库(CSCD)0124-1302