Abstract: Shale oil reservoir in the Jimusaer Sag is an important hydrocarbon exploration area in the Junggar Basin. Major breakthroughs have been made in recent years. In the past, most studies focused on the sedimentary environment, rock characteristics, microscopic pore structure, etc., while few studies were conducted on the evolutionary characteristics and differences of shale oil reservoirs. In order to explore the evolutionary characteristics and differences of the reservoirs in the study area, the typical core samples were taken from the upper sweet spot interval of Lucaogou Formation in Jimusaer Sag, the characteristics and controlling factors of shale oil reservoirs in the upper sweet spot interval of Lucaogou Formation in Jimusaer Sag were studied by means of rock slice, casting sheet, X-ray diffraction, etc., as well as analyzing the evolutionary characteristics and differences of the reservoirs were analyzed. The results of the study showed that the shale oil reservoirs in the upper sweet spot interval of Lucaogou Formation were in complex rock mineral composition, mainly including dolomite, feldspathic lithic sandstone, dolomitic sandstone, silty dolomite and gray mudstone. The reservoir space type was dominated by dissolved pore, intergranular pore and intercrystalline pore, with a few fractures. After the multi-stage evolution of acid-base fluids, the reservoir experienced diagenetic evolutions such as compaction and pressolution, calcite and dolomite cementation, and complex metasomatism. There were differences in the physical properties, pore-throat structure parameters and logging response characteristics of the reservoirs with of different lithologies. This study provides a favorable basis for the exploration and development of shale oil reservoirs in Lucaogou Formation in Jimusaer.

Key words: shale oil, reservoir characteristics, reservoir evolution, Jimusaer Sag, Lucaogou Formation