Characteristics of Source-reservoir Assemblage and Hydrocarbon Accumulation Model of Chang 7 Member in Ordos Basin

the source-reservoir assemblage of the Chang 7 Member in Ordos Basin is divided into six types according to the characteristics of vertical superposition of black shale, dark mudstone and reservoirs in different wells. Type Ⅰ, Ⅱ and Ⅳ source-reservoir assemblages are mainly distributed within the development range of black shale, with high oil and gas enrichment. Type Ⅲ, Ⅴ, and Ⅵ source-reservoir assemblages are mainly distributed outside the development range of black shale, in which oil and gas are only locally enriched. The continuity of oil and gas is good in the black shale distribution area. the oil and gas from the dark shale are strong charged, and that from the dark mudstone are charged from nearby areas. In the delta front area where black shale is lacking, the charging is weak. Oil and gas from the dark mudstone migrated and accumulated, while those from the black shale migrated laterally over a long distance, and concentrated locally.