关键词: 鄂尔多斯盆地, 胡尖山地区, 长7段, 页岩型页岩油, 源储特征, 勘探前景

Abstract: A set of source rocks mainly composed of organic-rich shale and intercalated with sandy sediments were developed in the seventh member of the Triassic Yanchang Formation (Chang 7 member) in Ordos Basin. Among them, exploration breakthrough and large-scale beneficial development of intra-source interlayered type shale oil have been achieved. However, there is a lack of study on shale type shale oil, as well as insufficient understanding on the exploration and development prospects. As a result, source rock and reservoir characteristics have been analyzed based on core laboratory tests and well logging interpretation results, and field pilot well development has been tested to evaluate the exploration prospects of shale type shale oil in Chang 7 member in Hujianshan area. The core testing results indicate that intergranular pores, intercrystal pores, and organic matter pores are mainly observed, with common bedding fractures and organic matter shrinkage joints, and free light oil mainly occurs in intergranular pores and bedding fractures; The experimental results of multi solvent continuous stepwise extraction method show that the proportion of free light oil in Chang 7 member shale reaches up to 54.3%. The geochemical experiment results indicate that the average total organic carbon content (TOC) is 14.03% and the average hydrocarbon generation potential is 57.73 mg/g, showing a high-quality source rock; The thermal evolution degree of organic matter is relatively high, with an average R_o of 1.08% and an average T_max of 450℃; The rock pyrolysis movable hydrocarbon content is 4.34 mg/g, indicating a good resource foundation of shale type shale oil. To sum up, Chang 7 member shale in the study area has good organic matter type, high organic content, good fracability, as well as good oil-bearing property indicated by vertical well testing and production results in the basin. By using rock pyrolysis method, the preliminarily estimated movable hydrocarbon resources of shale type shale oil in this area are 4.1×10⁸ t. The comprehensive study shows that the shale type shale oil in the study area has exploration and development prospects by applying horizontal well volume fracturing and reservoir stimulation.