Study on characteristics of imbibition and recovery predicted methods with different lithology structure

•The optimal lithofacies combination is determined.•The content and type of clay and interlayer frequency are the key characteristic parameters of oil production.•A newly established core-scale matrix spontaneous imbibition yield model. Da ’anzhai Member deposited from lake in Sichuan Basin is a specific formation in Jurassic, Mesozoic. The top and bottom are shell limestones, its middle comprises with different thickness intervals of shale and shell limestone frequently interbedded. The middle part is the main objective for shale oil exploration. But until now, what lithofacies is the main goal for potential production is not very certain through drilling several evaluation wells. We found that the shale and shell layer interbedded lithofacies compartment (B), and thin layers of shell and shale sedimented with laminated (C), are mostly potential shale oil producing formations. Furthermore, C lithofacies is the best part of Da ’anzhai Member. Those were analyzed by means of X-ray diffraction, scanning electron microscopy, low-temperature nitrogen adsorption, high-pressure mercury injection, nuclear magnetic resonance, imbibition experiments and nuclear magnetic resonance under normal and in situ conditions. A new theoretical prediction method of oil recovery based on nano model experiments has also been presented in this paper based on those tests stated above. According to the experiments and theoretical analysis, we consider the content and style of clay as well as frequency of laminated with shale and shell thin layers are key characteristic parameters for oil producing of middle part of Da ’anzhai Member. This has been proofed by a new exploration well drilled in 2023.