Shale oil reservoirs are inherently tight and are currently developed mainly by natural energy depletion through horizontal wells with volumetric fracturing. However, the production characteristics during the post-fracturing process remain unclear, and the contributions of various energy sources have not been quantified, leading to a lack of targeted measures for maintaining stable production in horizontal wells. In this study, we combined microscopic visualization experiments with nuclear magnetic resonance (NMR) to characterize oil production in shale oil reservoirs across different development stages and to determine the contribution of each energy source to the overall recovery factor. Using reservoir engineering methods, we further evaluated the contributions of various energy sources in Xi-233 and Z-183 blocks. The results show that during the post-fracture shut-in (PFSI) stage, imbibition mobilizes oil from pores of all sizes, whereas the subsequent displacement phase primarily targets oil in meso and macropores. The PFSI not only enhances oil recovery factor but also improves oil-water flow during later production. The total recovery factor contributed by the shut-in phase, elastic energy of the fracturing fluid, elastic energy of the reservoir fluid, and solution gas drive is approximately 10%, with individual contributions of 7.40%, 6.67%, 66.74%, and 19.19%, respectively. Among these, the elastic energy of the reservoir fluid is the dominant contributor to the total recovery factor. These findings provide a theoretical foundation for optimizing production strategies in shale oil wells, support the efficient development of shale oil in Longdong area, and offer valuable insights for the development of shale oil resources across the world.