The migration system, as the primary medium linking source rocks and traps, plays a vital role in studying hydrocarbon migration, accumulation, and reservoir formation. This study focuses on Late Paleozoic source rock (mudstone and coal rock) and sandstone samples from the Ordos Basin. By analyzing permeability, porosity, and their ratios under various conditions, this study evaluates the quality of hydrocarbon migration pathways across different lithologic strata, identifies optimal migration routes, and offers new insights for identifying favorable hydrocarbon exploration areas in the Late Paleozoic of the Ordos Basin. The findings indicate that the permeability ratio between parallel and vertical bedding planes in source rock and sandstone samples ranges from 1 to 4. Post-fracturing, permeability increases by over twofold. On average, sandstone permeability is approximately 0.1 × 10⁻³ μm², while source rock permeability is about 0.03 × 10⁻³ μm². Key conclusions include that without fracture development, permeability, and porosity parallel to bedding planes outperform those perpendicular to bedding planes, with sandstone showing better properties than source rocks. When fractures are present, permeability and porosity along the fracture direction are highest, followed by sandstone, with source rocks showing the lowest values. These results advance the theoretical understanding of hydrocarbon migration systems and provide significant guidance for hydrocarbon reservoir exploration and development.

The migration system, serving as the direct carrier that connects hydrocarbon source rocks and traps, is an important aspect of the research on oil and gas migration, accumulation, and reservoir formation. This paper mainly relies on the relevant sample data collected from the Upper Paleozoic in the Ordos Basin. By measuring the permeability, porosity values, and ratios of mudstone (coal) samples and sandstone samples under different conditions, it explores the migration and conduction mechanism of oil and gas in different lithological strata. The results indicate that the permeability and porosity of mudstone (coal) and sandstone samples in the direction parallel to the bedding plane are higher than those in the direction perpendicular to the bedding plane, and the permeability and porosity of sandstone are higher than those of mudstone (coal). In the presence of fractures, the permeability and porosity of fractured mudstone (coal) and sandstone samples are significantly higher than those without fractures. Based on this, the following conclusions can be drawn: When there is no fracture development, the permeability and porosity of hydrocarbon source rocks and sandstone in the direction parallel to the bedding plane are better than those in the direction perpendicular to the bedding plane, and the permeability and porosity of sandstone are better than those of hydrocarbon source rocks (mudstone and coal rock). When fractures are developed, the permeability and porosity in the fracture direction are the best, followed by sandstone, and hydrocarbon source rocks are the worst. The research conclusions lay a foundation for further improving the relevant theoretical research on the oil and gas migration system and also play an important guiding role in the exploration and development of oil and gas reservoirs.