Characteristics of source rocks and reservoirs of the Funing Formation in the Subei Basin and their bearing on future shale oil exploration

395 samples collected from 70 wells in the major depressions of the Subei Basin are analyzed in this paper. Combined with the previous data analyzed, we systematically studied the geochemical and lithological characteristics, accumulation space types and their distribution patterns as well as reservoir physical properties in addition to the hydrocarbon source rock of the F2 and the F4 Member of the Paleogene Funing Formation in the Basin. Based on the case studies for typical wells and oil shows, the occurrence and accumulation mechanisms of shale oil is deeply discussed. The results reveal that the average organic carbon content of the two members is over 1.0%, dominated by the type I-II in a matured stage, that found the basis for the formation of shale oil. Many kinds of micropores and micro cracks are well developed. Clay content of the Member F2 is usually lower than 35% and the content of brittle minerals is over 50%, which is in favor of shale oil mining. The study of the two well cases in the typical shale reservoir reveals that the formation of shale oil reservoir mainly depends on the existence of mature shale with high abundance of organic matter and brittle minerals, well developed fractures and abnormal high pressure. The major depressional centers of the Jinhu Sag, Gaoyou Sag, Haian Sag and Yancheng Sag in the North Jiangsu Basin are favorable zones for shale gas exploration and mining.