Abstract: Over the past 50 years, breakthroughs have continuously been made in the exploration of the Jurassic system in Ordos Basin. Based on early discovered oil reservoirs and exploration and appraisal wells, drilling geological data, core analysis, and seismic data have been used to finely characterize the pre Jurassic paleogeomorphology, sand bodies, and structures in the basin and analyze characteristics of fault development in the 3D seismic area, identifying the types of Jurassic oil reservoirs in the study area and controlling factors, and pointing out further exploration orientations and potential of the Jurassic system in the basin. The study results show that: (1) The pre Jurassic paleogeomorphology presented a “U+V”-shaped multi-level ancient river structure, with nine types of small units such as inter-river hill and terrace, which significantly controlled oil reservoir types; (2) The Jurassic oil reservoirs were mainly generated by source rocks in the seventh member of the Triassic Yanchang Formation, and the episodic oil charging in the Late Jurassic–Early Cretaceous laid the foundation for the wide distribution area of oil reservoirs; (3) The coupling of ancient rivers and low-amplitude nose uplift structures controlled the distribution of oil reservoir clusters, and a stereoscopic hydrocarbon accumulation pattern was formed by a three-stage fault relay transport; (4) There is still huge resource potential with a level of 100 million tons in complex fault zones in the western basin margin and the northeastern part of Jingbian slope, as well as mature areas through fine exploration.

Key words: Ordos Basin, Jurassic, paleogeomorphology, control factor, exploration potential