Organic geochemistry characterization of the Yan 9 crude oils and oil-source rock correlations in Jingbian Oil Field,Ordos Basin

The geochemical characteristics of the Yan 9 reservoir were analyzed by means of the group composition and the biomarkers in order to clarify the oil source of the Yan 9 reservoir in Jingbian Oil Field. The results showed that the n-alkanes are distributed with a single mode with C₂₁ as the main carbon peak, C₃₀hopane as the dominant biomarker, followed by C₂₉hopane. Regular steroids are mainly C₂₉, while C₂₇ and C₂₈ are similar, showing an asymmetric “V” distribution. The Yan 9 crude oil has similar geochemical characteristics and unified material source and evolution degree. It is a mature crude oil derived from a source deposited in a weak oxidation-reduction environment under freshwater conditions. Oil-source correlation showed that the reservoir of Yan 9 mainly comes from the contribution of Chang 7 hydrocarbon source rock in Jingbian Oil Field.