Cross-scale and multi-dimensional characterization of lacustrine shale laminae: Controls on shale oil enrichment and high production

China’s continental shale exhibits strong heterogeneity, causing significant variations in shale oil enrichment. Current research often isolates individual laminae, lacking systematic investigation into how diverse laminae combinations control hydrocarbon enrichment. To elucidate the coupling between laminae architecture and shale oil source-reservoir systems, we investigated the Shahejie Formation in the Jiyang Depression. A set of cross-scale, multidimensional, and refined characterization methods was established to evaluate laminae, pore structures, oil-bearing properties, and wettability by integrating large-area thin-section scanning, submicron-scale confocal laser scanning microscopy (CLSM), nanoscale scanning electron microscopy (SEM), XRF elemental mapping, and contact-angle measurements. The results show that: (1) Laminae types exhibit distinct source and reservoir functions. Argillaceous laminae are highly oil-prone, while mixed-composition laminae act as advantageous self-sourced reservoirs via their organic richness and pores within brittle minerals. Microsparite, dolomite, and feldspar-rich laminae provide critical reservoir space; conversely, fibrous and micritic calcite form effective fluid barriers. (2) Mineral wettability controls differential fluid enrichment. Oil-wet carbonates (dolomite, calcite) favor oil accumulation, whereas water-wet feldspar and clays constrain it. (3) Laminae assemblage configuration exerts an important influence on productivity. The effective combination of oil-prone laminae, reservoir laminae, and favorable laminae, together with an extremely low proportion of barrier laminae and frequently developed laminae architectures, forms a highly efficient micro-scale source-reservoir system. This study clarifies how complex laminae architectures and micro-scale wettability control continental shale oil enrichment, providing theoretical guidance for efficient exploration.