Shale oil sweet spot section evaluation based on oil bearing characteristics in Es3L subsection of Bonan subsag in Jiyang depression

Shale oil content is commonly evaluated using Rock-Eval pyrolysis S1, but conventional S1 may underestimate total oil content because light hydrocarbons can be lost during storage and heavy hydrocarbons may remain undetected below 300 °C. This study evaluates the shale oil sweet spot interval of the lower Es3 sub-member (Es3L) in the Bonan subsag, Jiyang Depression, Bohai Bay Basin, by integrating organic geochemical data, open-system hydrocarbon generation simulation, gold-tube pyrolysis, and corrected oil-content calculation. The results show that correction of both light and heavy hydrocarbon losses improves the quantitative estimation of total shale oil content. A three-segment relationship between corrected total oil content and TOC defines the enrichment threshold for the Es3L shale, with TOC > 2.4% indicating enriched shale oil resources. Movable oil content, calculated from the difference between total oil content and adsorbed oil content, further constrains sweet spot identification. The interval of 2981-3041 m in Well L69 satisfies both enrichment and movability criteria and is therefore identified as the preferred sweet spot interval. The proposed workflow provides a practical framework for shale oil sweet spot evaluation in the Bonan subsag and comparable lacustrine shale systems.