Abstract:The interrelation between “seven kinds of relationships” and the characteristics of “three types of properties” of the Second Member of the Funing Formation in the Subei Basin(northern Jiangsu Basin) are investigated by integrating cores, thin sections, scanning electron microscope (SEM) and other petrophysical experiments, combined with conventional logs, image logs, and Nuclear Magnetic Resonance (NMR) logging data. The results reveal that the main storage spaces developed in the shale reservoirs of the Second Member of the Funing Formation, which are mainly oilbearing, are intergranular pores, intragranular solution pores, intercrystal pores, organic matter pores and microfractures. Based on the physical parameters and pore spaces, the classification criteria for the quality of reservoir are established. The value of irreducible water saturation increases from type I to type Ⅳ. It is concluded that the source rock of the Second Member of the Funing Formation, which TOC is basically greater than 1%, has good organic matter types. A well-log-based TOC calculation model is established based on natural gamma spectroscopy log data (K) and Δlg R method, the classification of source rock quality is achieved based on TOC. The direction of insitu stress is mainly NE—SW, and the brittle index of the Second Member of the Funing Formation is basically greater than 40%, which means it can be easily fractured. The engineering quality is divided according to the brittle index. On the basis of the research on interrelation between “Seven Relationships”, by considering the reservoir quality, source rock quality and engineering quality, the “sweet spot” of a single well is selected. It is concluded that the sweet spots are mainly distributed in the Nibozi, Qijianfeng, Sijianfeng, Shangshanzi and Zhongshanzi sections, which is consistent with the oil test data. The results can provide theoretical guidance and technical support for well log evaluation and sweet spot prediction of oil shales.