Lithological Characteristics and Evaluation Methods of Continental Shale Oil Reservoirs in Nanpu Sag

The continental shale oil reservoir of Shahejie Formation in Nanpu sag belongs to terrestrial lacustrine basin sedimentary system. The reservoir is characterized by well-developed fine-grained sediments, complex mineral compositions, poor physical properties, and subtle differences in logging response characteristics, which making lithology identification particularly challenging. Based on the logging response characteristics of different mineral components under the calibration of X-ray diffraction whole-rock analysis results, this study applies a multiple regression algorithm to construct a quantitative calculation model for mineral components. By optimizing the solution with the least squares method, the optimal composition of each mineral component in shale oil reservoirs is determined, achieving accurate and continuous calculation of mineral components using conventional well logging data. Based on the lithologic composition characteristics of the reservoirs in the study area, a “three-end-member, four-lithology” classification scheme is established, utilizing felsic minerals, carbonate minerals, and clay minerals as the end-members. The calculated mineral compositions are employed to accurately delineate the lithologic profiles of the reservoirs. This method effectively addresses the challenges in lithologic evaluation of shale oil reservoirs and enhances the accuracy of lithology identification using well logging data. The research results provide crucial parameters and technical support for the fine evaluation and effective dessert optimization of continental shale oil reservoirs in Nanpu Sag.