The potential of China's saline lacustrine shale oil resources is enormous. Currently, the storage space of saline lacustrine shale oil remains unclear, posing significant challenges for commercial development. In this study, we selected the samples from the typical saline lacustrine shale strata of the Lucaogou Formation, Jimusar Sag, Junggar Basin and investigated the pore systems and their relationship with oil content S of different lithofacies. The pore structures were quantified by using the combination of low-pressure N adsorption and mercury intrusion. TOC assessment, rock pyrolysis, and XRD were utilized for characterizing the organic geochemical and mineralogical parameters. The results showed that the organic matter comprising type III mainly appears in the clay-enriched lithofacies (types I, II and III), while the organic matter types I, II and II can be found in other lithofacies. Regarding the nine lithofacies, siltstone has the highest oil content S, followed by the felsic-enriched lithofacies (types III and III). The enrichment of oil in siltstone, carbonate rocks, and felsic-enriched lithofacies (types III and III) is primarily attributed to macropores. Conversely, in clay-enriched lithofacies (types I, II and III), the oil content S is attributed to both the mesopore fractal dimensions (D and D) and the TOC content. Moreover, the higher the complexity of the mesoporous structure (D) and the larger the macropore surface area in clayey carbonate felsic shale (II), the greater the oil content S. It is further observed that, macropores with size range between approximately 60 nm and 3000 nm are abundant in siltstone and felsic mineral-enriched lithofacies (i.e., carbonate felsic shale III and felsic shale III). Furthermore, the siltstone shows the widest oil-rich macropore size range (range of 70–1000 nm), followed by felsic shale (III) (range of 150–1000) and carbonate felsic shale (III) (range of 100–110 nm). Siltstones and felsic-enriched shales are optimal for exploiting saline lacustrine shale deposits.

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盐湖相页岩各岩相孔隙系统及其与石油富集的相关性

我国咸水湖相页岩油资源潜力巨大。目前，咸水湖相页岩油储集空间尚不清楚，给商业开发带来重大挑战。本研究选取准噶尔盆地吉木萨尔凹陷芦草沟组典型盐湖相页岩地层样品，研究了不同岩相的孔隙系统及其与含油量S的关系。通过低压氮气吸附和压汞相结合的方式对孔隙结构进行定量。利用 TOC 评估、岩石热解和 XRD 来表征有机地球化学和矿物学参数。结果表明，Ⅲ型有机质主要出现在富含粘土的岩相（Ⅰ、Ⅱ、Ⅲ型）中，而Ⅰ、Ⅱ、Ⅱ型有机质也可在其他岩相中发现。在9个岩相中，粉砂岩的含油量S最高，其次是富长英质岩相（Ⅲ型和Ⅲ型）。粉砂岩、碳酸盐岩和富长英质岩相（Ⅲ型和Ⅲ型）中石油的富集主要归因于大孔隙。相反，在富含粘土的岩相（I、II 和 III 型）中，含油量 S 归因于中孔分形维数（D 和 D）和 TOC 含量。此外，粘土质碳酸盐长英质页岩（II）中介孔结构（D）的复杂性越高，大孔表面积越大，含油量S越大。进一步观察到，尺寸范围在约60 nm之间的大孔3000 nm 和 3000 nm 富含粉砂岩和富长英质岩相（即碳酸盐长英质页岩 III 和长英质页岩 III）。此外，粉砂岩显示出最宽的富油大孔隙尺寸范围（范围为70-1000 nm），其次是长英质页岩（III）（范围为150-1000）和碳酸盐长英质页岩（III）（范围为100-110 nm） ）。粉砂岩和富长英质页岩是开发咸水湖相页岩矿床的最佳选择。