关键词: 鄂尔多斯盆地, 新领域, 新类型, 页岩油, 天环坳陷, 西缘冲断带, 三边地区, 延长组下组合

Abstract: Ordos Basin is rich in oil-gas resources and now is the largest oil-gas production base in China. With the continuously growing energy demand of the country, Ordos Basin has played the main role in increasing reserves and production. In recent years, based on the innovation in geological theory and breakthrough in key technology, major breakthroughs and significant progress have been made in new fields and new types of oil exploration in Ordos Basin. The paper reviews the four fields of shale oil area, Tianhuan depression-western margin thrust belt, Sanbian areas (Jingbian-Dingbian-Anbian areas), and the lower assemblage of Yanchang Formation, and analyzes their geological conditions, exploration progress, and resource potential. On this basis, the key insights were obtained as below. (1) Shale oil is expected to be the main contributor for the sustainable development of production above 6 000×10⁴t in Changqing oilfield. Ordos Basin develops continental shale oil in the Member 7 and 9 of Mesozoic Yanchang Formation, as well as marine shale oil in Paleozoic Wulalike Formation. Specifically, the interbedded shale oil in the Member 7 of Yanchang Formation has the proven reserves of 40.5×10⁸t, which is the main target for exploration and development; the laminated shale oil has an estimated resource potential of 20×10⁸t, achieving a strategic breakthrough; the breakthrough test for lamellar shale oil is steadily promoted, and its success will have a revolutionary impact. The Member 9 of Yanchang Formation in northern Shaanxi area develops "Lijiapan shale", and the risk exploration of shale oil is progressing smoothly. The exploration in Wulalike Formation in the southern section of the western margin of the basin has a good start, and new strata are exploited in the exploration of Paleozoic marine shale oil. (2) New oil enrichment areas are detected in the complex tectonic zone of Tianhuan depression and western margin thrust belt, forming three replacement areas: Yujialiang, West Huanxian, and North Pingliang, with the resource potential of more than 5×10⁸t. (3) New progress has been made in multi-strata and three-dimensional exploration in Sanbian areas, and the Haotan Integrated Demonstration Zone has been quickly built. The resource potential of Sanbian areas is preliminarily estimated as 5×10⁸t. (4) The lower assemblage of Yanchang Formation shows a good exploration prospect. Multiple favorable areas have been discovered through outstepping exploration in the Member 9 and 10 of Yanchang Formation, with the proven reserves of nearly 3×10⁸t. Overall, Ordos Basin is in the middle stage of exploration and still has great potential for increasing reserves. The new fields and types of oil exploration will provide replacement resources for oil companies to implement the important strategies of high-quality petroleum development.

Key words: Ordos Basin, new field, new type, shale oil, Tianhuan depression, western margin thrust belt, Sanbian areas, lower assemblage of Yanchang Formation