关键词: 页岩油, 富集条件, 战略方向, 古近系, 济阳坳陷

Abstract: In recent years, the major breakthrough in shale oil exploration in Jiyang depression demonstrates the broad prospect of shale oil in continental rift basins, and on this basis, the theoretical system of shale oil geology is gradually improved. The main organic-rich shale in the Jiyang depression is the Cenozoic Paleogene continental saline lacustrine basin deposition; generally, it has the characteristics of low thermal evolution degree, deep burial depth, thick formation, high carbonate mineral content, high formation pressure, high formation temperature, diverse lithofacies, complex structure and varied fluid properties. The multi-stage rifting activities and water salinization in Jiyang depression had created a sedimentary background for the large-scale development and evolution of Paleogene shale. The main hydrocarbon source rocks in Jiyang depression, mostly developed in saline lacustrine basin, has the characteristics of early oil generation, early enrichment, and moderate evolution, i.e., able to generate a large volume of hydrocarbons. The reservoir conditions such as the coexistence of organic-rich laminated lithofacies and inorganic pores/slits and the development of macropores, and the multi-state occurrence of free hydrocarbons in medium-low mature organic-rich and carbonate-rich shale provide the important basis for the enrichment of Paleogene shale oil in Jiyang depression. The double-layer structure of hydrocarbon generation layers and reservoirs in the organic-rich shale system and the binary coupling of hydrocarbon generation and storage make the inorganic-organic effective match between the dominant lithofacies with large pore size and high porosity and permeability in shale and the free oil enrichment area. Further, combined with the optimization of the experimental method of shale oil resource evaluation and the continuous breakthrough in the exploration of ultra-thick shale oil, the new round evaluation of shale oil resource in the Paleogene of Jiyang depression will help us re-understand the scale of shale oil resources in the study area. It is expected that the total amount of Jiyang depression shale oil resources will be significantly improved from the current 4.1 billion tons of free oil. In the future exploration of shale oil in Jiyang depression, we will continue to explore the enrichment theory and commercial production capacity of shale oil with different lithofacies, different thermal evolution degrees and different pressure systems, further expand the scale of shale oil resources in Jiyang depression, and lead the exploration of shale oil in continental rift basins.

Key words: shale oil, enrichment conditions, strategic direction, Paleogene, Jiyang depression