Geochemical Characteristics of Jurassic Source Rocks from Well LV and Oil-source Correlation in North Yellow Basin

Key words: 
• source rocks /
• oil sandstone extract /
• organic richness /
• carbon isotope /
• oil-source correlation

Abstract: Jurassic source rocks and oil sands from Well LV has been analyzed by usual organic geochemical methods and stable carbon isotopic detection in the North Yellow basin, in order to study the geochemical characteristics of the source rocks and the crude oils and oil-to-source correlation. The results show that the maturity of Jurassic source rock is higher, its kerogen type is maily Ⅲ. Middle Jurassic source rocks are higher in organic carbon and lower in hydrocarbon yields, chloroform bitumen "A" and HC, which means they are relatively poor source rocks. The kerogen carbon isotope of the middle Jurassic source rocks is heavy. There is a remarkable difference of carbon isotopic values of middle Jurassic source rocks(-24.4‰~-23.5‰) and crude oils(about -29‰). Therefore, there is no relationship among them. However, TOC content of the upper Jurassic source rocks is lower than that of the middle Jurassic source rocks, but hydrocarbon yields, chloroform bitumen "A" and HC of the upper Jurassic source rocks are higher. The character of chloroform bitumen "A" carbon isotope, distribution pattern of carbon isohopic distributions of individual n-alkanes and biomarkers of upper Jurassic source rocks are similar to crude oils. Comprehensive analysis could draw a conclusion that there is closely relationship between crude oil and the upper Jurassic hydrocarbon source rock, which has good kerogen type and mature parent materials from both higher plants and lower aquatic organisms.