Taking the source rock of Chang 7 Member in Ansai area of Ordos Basin as the research object

the differentiation characteristics of shale oil in the process of migration and accumulation are discussed in depth through a series of testing methods

such as TOC test

rock pyrolysis and chromatography-mass spectrometry. The results show that the hydrocarbon generation potential of different source rocks in the study area is quite different. The shale has the strongest hydrocarbon generation capacity

while that of the interaction layer of sandstone and mudstone is the weakest. The high content of free hydrocarbon in interaction layer of sandstone and mudstone results from the receipt of external free hydrocarbon. The distribution of geochemical parameters of shale oil in different lithology is different. Among them

the sand mud interaction layer is rich in saturated hydrocarbon but relatively poor in nonhydrocarbon and asphaltene

while the shale and the mudstone are rich in nonhydrocarbon and asphaltene but relatively poor in saturated hydrocarbon. The properties of crude oil

thickness of source reservoir and physical properties have effects on shale oil migration and accumulation. Shale oil in thin-layer source rocks and small molecular hydrocarbon components are easy to migrate. Shale oil in thick-layer source rocks and macromolecular hydrocarbon components tend to remain in the source rocks.