Comprehensive Research of Oil-Source Rock Correlation of Lower Yanchang Formation in Jiyuan Field, Ordos Basin

On the basis of biomarker data for crude oil and source rock from Lower Yanchang Formation in Jiyuan area of Ordos basin, this paper systematically analyzed oil source characteristics and clarified the spatial matching characteristics of crude oil and source rock with reference to group component and saturated hydrocarbon chromatin of crude oil, and total organic carbon, pyrolysis, group component, saturated hydrocarbon chromatin of source rock from Tiebiancheng Field. The results showed that C₃₀ diahopane can be used to effectively distinguish the source rock and related hydrocarbon of Chang 7 from those of Chang 9. In Chang 7, oil shale is the main source rock, followed by grayish black mudstone. In Chang 9 source rock develops in Tiebiancheng Field of southeastern Jiyuan Area, which also contributes some hydrocarbon generation. In space, the oil-source rock of Lower Yanchang Formation in Jiyuan area has an obvious boundary of eastern Gufengzhuang-Hongjingzi-western Jiyuan-southwestern Fanxue. In the northeastern region of the boundary, crude oil of TypeⅠderived from the long-distance lateral migration and accumulation of Chang 7 oil shale；in the southeastern end of the boundary, transitional crude oil of Type I-Ⅱ is the mixture of Chang 7 oil shale and Chang 9 dark mudstone；in the southwestern region, crude oil of Type Ⅱ-Ⅲ is from Chang 7 black mudstone.