Differential Evolution and Synergistic Control on Reservoir Quality of Tectonic Fractures and Bedding‐Parallel Fractures in Continental Shale Reservoirs: A Case Study of the Fu‐2 Member Shale Reservoirs in the Gaoyou Sag, China

Tectonic fractures and bedding‐parallel fractures jointly develop in continental shale reservoirs, providing critical storage space and efficient flow pathways for hydrocarbons. Although existing studies have elucidated the fundamental characteristics of these fractures, the mechanisms behind their formation, controlling factors, and their differential contributions to hydrocarbon storage remain insufficiently explored. Taking the shale reservoirs of the Fu‐2 Member in the Gaoyou Sag, Subei Basin, China, as a case study, this research utilizes multi‐scale fracture data obtained from imaging logs, cores, and thin sections. It quantitatively characterizes fracture geometry and clarifies the spatial distribution patterns of both tectonic fractures and bedding‐parallel fractures. By integrating fracture crosscutting relationship, fluid inclusion thermometry, and carbon–oxygen isotope data, this study reconstructs the formation and evolution sequence of tectonic fractures and bedding‐parallel fractures, deciphers their dynamic coupling with structural‐diagenetic events, and further elucidates the differential controlling factors governing their development as well as their synergistic reservoir‐controlling mechanisms. The results demonstrate that four fracture types are developed in E 1 f 2 , dominated by tectonic fractures (61%) and bedding‐parallel fractures (31%). Tectonic fractures, controlled by brittle mineral content and mechanical stratigraphy thickness, are characterized by high dip angles and multilayer penetration. These fractures constitute dominant vertical migration pathways for hydrocarbons. In contrast, bedding‐parallel fractures—closely associated with organic matter thermal evolution and abnormal fluid pressure—generally exhibit low‑angle, densely distributed patterns with extensive horizontal continuity. Tectonic fractures, influenced by geological activity, develop throughout the entire basin evolution. Bedding‐parallel fractures, in contrast, predominantly form during rapid burial periods, coupled with both diagenetic evolution and hydrocarbon generation from organic matter. The synergistic development of tectonic fractures and bedding‐parallel fractures significantly enhances reservoir permeability. Specifically, tectonic fractures improve vertical connectivity, with core‐scale apertures reaching centimeter‐scale in locally dissolved zones, whereas bedding‐parallel fractures enhance local storage capacity by increasing effective porosity through dissolution. The intersecting zones form heterogeneous “sweet spots” (e.g., E 1 f 2 ‐IV‐3–E 1 f 2 –IV‐7 and E 1 f 2 ‐V‐6–E 1 f 2 ‐V‐8), which exhibit significantly higher cumulative oil production. This study offers both a theoretical foundation and practical guidance for predicting such “sweet spots,” thereby supporting the efficient development of continental shale oil resources.