抄録
In the context of global energy transition and the rapid development of unconventional hydrocarbons, elucidating the structural controls and dynamic mechanisms governing tight-oil accumulation systems is crucial for improving reserve prediction accuracy and optimizing exploration strategies. Focusing on persistent gaps in understanding the structural framework, reservoir-space evolution, and fluid-migration processes, this study investigates the Yanchang Formation of the Ordos Basin using an integrated workflow that combines detailed core observations, fluid-geochemical analyses, reservoir microstructural characterization, diagenetic and petroleum-system dynamic simulations, and three-dimensional geological modeling. The results demonstrate that tight oil in the Yanchang Formation exhibits pronounced stratigraphic zonation and composite structural–sedimentary control, with fluid compositions showing progressive light-hydrocarbon enrichment and phase differentiation. The reservoir’s effective storage capacity is jointly governed by multiscale pore systems, diagenetic sequences, and fracture networks, while short-distance migration driven by hydrocarbon-generation overpressure represents the dominant accumulation mechanism. On this basis, a comprehensive accumulation model integrating “structural framework–reservoir space–fluid characteristics–dynamic processes” is proposed, providing a new theoretical foundation and methodological guidance for tight-oil assessment and efficient development in the Ordos Basin and analogous sedimentary basins.
