Abstract: The Ordos Basin Qingcheng shale oil reservoir has strong lateral and vertical anisotropy, low natural fracture development, and large two-direction horizontal stress difference. The preliminary microseismic recognition indicates that the double-wing feature is obvious,and the fracture morphology is relatively simple. In order to further understand the post-fracturing fracture network morphology and spatial distribution, a coring study was conducted in the Qingcheng shale oil hydraulic fracturing test site using high inclination well between fracturing wells. Through CT scanning, manual observation, microscopic imaging, and well logging responses, the fine-grained description of fracture dip, fracture surface morphology, filling characteristics, etc. was carried out, and the fractures were classified and identified. At the same time, the dye proppant, mud tracer, and spatial distance and distribution law were combined to perform corresponding regression and comprehensive analysis on the hydraulic fractures. The research results show that there are differences in the characteristics of different types of fractures, with a low proportion of natural structural fractures and a high proportion of bedding fractures and hydraulic fractures.The hydraulic fractures are characterized by swarm features, with a much higher number than the corresponding stages of adjacent hydraulic fracturing well, and there are local differences in extension, but they still extend along the principal stress direction under the influence of stress difference and orientation. There is less obvious propped fractures, but the proppant is widely distributed in cuttings and the proportion of small particle size is higher. The tracer analysis shows that the number of hydraulic fractures corresponding to each stage is the key to oil production contribution. The fracture recognition, classification, and regression method obtained by integrating multiple methods can be referenced for other unconventional oil and gas reservoir post-fracturing coring analysis, and the fracture understanding obtained has certain guiding significance for the next step of fracturing optimization.

Key words: shale oil, hydraulic fracturing test site, high inclination coring well, hydraulic fracture, swarm characteristics