Carbon Isotope Characteristics and the Influencing Factors of the Oils from Lunnan and Hadexun Oil Fields

The analytical results of the whole and the monomer paraffin hydrocarbons carbon isotope of the 20 oils from Lunnan and Hadexun oil fields show that the whole carbon isotope of the oils from Lunnan area is more than -32‰, and that of the oils from Hadexun area is less than -32‰, the carbon isotope of monomer paraffin hydrocarbons of the oils from Lunnan area is also heavier than that of the oils from Hadexun area. That the carbon isotope of oils from Lunnan area heavier than that of oils from Lunnan area caused the difference between the oil pools formation in the two areas. The main factor resulted in the carbon isotope of oils from Lunnan area heavier than that of oils from Hadexun area is the mixture between the degraded oil from the Cambrian source rock and the oils from Middle-Upper Ordovician source rock, instead of the different source rocks of the oils.