Shale oil occurrence state and its controlling factors in saline lacustrine basins: Insights from sequential solvent extraction

作者：Chen-Jia Zhang, Jian Cao, Baoli Xiang, Baojian Shen, Ni Zhou, Wenyao Xiao, Yan Wang, Yuce Wang, Xu-Sheng Guo · 发表于：Petroleum Science · 年份：2025 · DOI：10.1016/j.petsci.2025.09.003 · 被引用次数：3 · 研究领域：Hydrocarbon exploration and reservoir analysis、Petroleum Processing and Analysis、Hydraulic Fracturing and Reservoir Analysis

Due to the complexity of the lithofacies associated with shale oil in saline lacustrine basins, the differences of shale oil occurrence state and its controlling factors in different lithofacies are not completely clear. This hinders efficient shale oil exploration and development. We investigated the shale oil in the Permian Lucaogou Formation in the Jimusar Sag, Junggar Basin, China, based mainly on sequential solvent extraction, petrological, organic geochemical, and nuclear magnetic resonance techniques. The fluidity of extractable organic matter decreased from the first extract to the fourth extract, which was caused by the gradual decrease in the contents of saturated and aromatic hydrocarbons, and gradual increase in the contents of NSO compounds and asphaltenes. The contents of free hydrocarbons (the first and second extracts) and adsorbed hydrocarbons (the third and fourth extracts) are very different among the lithofacies. The free hydrocarbon ratios in the siltstones and carbonate rocks are >70% and the main pore throats are >1 μm in size, corresponding to the best sweet spots. The contents of free hydrocarbons in the laminated silty mudstones and shales with bedding fractures are >50%, which are also available. The free hydrocarbons in the siltstones and carbonates are saturated with migrated hydrocarbons, with the contents being more affected by the physical properties of rocks. In contrast, the free hydrocarbons in the mudstones are mainly self-generated and -st...