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The Chang 7 Member of the Ordos Basin has favorable shale oil resource potentiality. The exploration and development of sandstone interlayer shale oil in the Chang 7 Member has made substantial breakthroughs. The exploration and development potential of shale oil is huge, and will be a significant oil and gas alternative resource in the Changqing Oilfield in the future, but its related geological fundamental research is relatively weak. Based on the observation, description and systematic sampling of the centimeter-level core of the full core section of Chang 7 Member in Well Ning228, a series of experimental test analyses and identification outcomes indicated that Chang 7 Member primarily developed four rock types: Black shale, dark mudstone, siltstone and tuff. The overall conditions of source rocks in the Chang 7 member are superior, the organic carbon content of shale is high, and the hydrocarbon generation potential is large. The organic matter types are mainly type Ⅰ and type Ⅱ, which are in the low mature-mature stage, and the black shale has higher organic matter abundance. The main reservoir spaces of the Chang 7 Member are primary pores and secondary pores. Mud shale primarily develops organic pores and inorganic pores. Fine sandstone mainly develops residual intergranular pores, intragranular pores and intergranular pores. Tuff mainly develops intergranular pores and mineral intragranular pores. The overall oil-bearing property of the Chang 7 Member is good, but the mobility difference is large. The fluid mobility in sandstone and tuff is good, and the mobility inshale is poor. In short, fine anatomical analysis of typical interlayer shale oil provides favorable guidance for promoting the large-scale development of shale oil in the Ordos Basin.

The bottom morphology of the lake basin controlled the sedimentary system, genetic types, and distribution characteristics of sand bodies in the Chang 73 submember of the Triassic Yanchang Formation in the Ordos Basin. The types, genesis, and spatial distribution of sand bodies in different regions differ. In this study, according to cores, drilling, logging, and other data, the paleogeomorphology of the Chang 73 submember was accurately restored by the impression method and sedimentology method, and the micro paleogeomorphology units were finely characterized. On this basis, the authors analyze the paleogeomorphology control on the sedimentary system, genetic types, and distribution characteristics of sand bodies in the Chang 73 submember. The result shows that the paleogeomorphology of the Chang 73 period is an asymmetrical depression in the east and a steep depression in the west. Seven micro paleogeomorphic units, including the highland, the slope break zone, the lakebed deep depression, the lakebed plain, the lakebed paleouplift, the ancient lakebed ridge, and the ancient channel, are identified in the study area. The paleogeomorphology obviously controlled the gravity flow deposition system of the Chang 73 submember in the study area. From the margin to the center of the lake basin, delta front deposition, channel-type gravity flow deposition, and semideep-deep lake deposition successively developed. From the slope break zone to the center of the lake basin, the gravity flow deposition type gradually changed from sandy debris flow deposition to turbidity flow deposition. The paleogeomorphology controls the overall distribution of the gravity flow sand body in submember 73 in the study area, while the micro paleogeomorphology units such as the highland, the slope break zone, and the ancient channel further control the provenance direction, genetic type, transportation direction, lateral connectivity and distribution pattern of the gravity flow sand bodies.