Abstract: The data of geochemistry，scanning electron microscopy，core thin sections，logging and oil well production were used to analyze the characteristics of reservoirs，source rocks and the distribution of tight oil of the seventh member of Triassic Yanchang Formation（Chang 7 member）in northern Shaanxi area，Ordos Basin，the controlling factors for differential enrichment of tight oil were discussed from three aspects：source rocks distribution，transport system and source-reservoir configuration，and the reservoir accumulation model was summarized. The results show that：（1）The tight sandstone reservoirs of Chang 7 member in northern Shaanxi area are mainly developed in the first sub-member（Chang 7₁）and the second sub-member（Chang 7₂），predominantly composed of gray to gray-white feldspar sandstone and lithic feldspar sandstone. The average porosity of Chang 7 1 and Chang 7₂ sub-members is 5.56% and 7.32%，respectively，and the average permeability is 0.097 mD and 0.110 mD，respectively. The physical properties of Chang 7₂ reservoir are better. The pore space is mainly composed of dissolved pores，with a small number of intergranular pores developed.（2）The hydrocarbons in the study area mainly come from two sets of source rocks，including the top of Chang 7₂and Chang 7₃，with an average thickness greater than 20 meters. The organic matter abundance is high，with an average total organic carbon （TOC）value of 3.02%. The kerogen types are mainly type I and type Ⅱ₁，indicating a period of high hydrocarbon generation，and the average hydrocarbon generation amount is 270.2×10⁴ t/km². Chang 7₃ source rocks have greater hydrocarbon generation potential，supplying hydrocarbons to Chang 7₂ reservoir，and the tight oil in Chang 7₁ comes from Chang 7₂ source rocks. The tight oil in Chang 7₂ reservoir at the end of the delta front subfacies in Xin’anbian area is supplied laterally by lake basin source rocks.（3）The enrichment of tight oil in the study area is controlled by the distribution of source rocks，the connectivity of sand bodies and the sourcereservoir configuration. It is more enriched in Chang 7₂ and has the largest distribution area in Xin’anbian area， and there is no large-scale tight oil accumulation in Ansai area. The differential tight oil accumulation in the vertical and plane is controlled by the source rock thickness and source-reservoir configuration. The oil-bearing ability is better for lower generation and upper storage，upper-lower generation and middle storage as well as sand and mud interlayers. The scale of tight oil accumulation of Chang 7₂ at the end of the delta front in Xin’anbian area is larger than that of the main body of the delta front，because the locally connected sand bodies developed at the end of the delta front hinder the lateral migration of hydrocarbon sources in the lake basin.（4）The tight oil in the study area follows a“source-controlled and sand-controlled”accumulation model. The sand bodies in distal river channels and locally connected sand bodies near the source are favorable exploration areas.

Key words: tight oil, differential accumulation, delta front sand, source rocks distribution, source-reservoir configuration, sand bodies connectivity, lateral migration, Chang 7 member of Yanchang Formation, Triassic, Ordos Basin