Abstract: In a primary subsiding hydrocarbon generative basin, the migration or accumulation of hydrocarbon is an episodic and continuous differential process that accomplished in (20~40)×106 a. Darcy flow and diffusion flow have the flowing rate in mudstone at 3~5 m/106 a and 4~18 m/106 a, respectively, they can occur at the same time and convert each other. The premium pathway and the direction for petroleum migration are different in concept, the former is controlled by rock make-up, and the latter is controlled by sedimentary facies and structural feature. The preliminary study shows that over 70% of oil and gas fields are located on the direction of premium pathway for petroleum migration. The sealing intensity and closure of trap are divided into three types of combinations, which are the main control factors for in-situ oil-gas distribution. The sand lenticular body-formed reservoir is resulted from multi-dynamic interactions and multi-phase state conversions and closely related to the quality and thickness of muddy source rocks as well as the sand physical property and occurrence. The study shows that the global oil reserves age and the giant oilfields median age are 29×106 a and 35×106 a, averaging 41×106 a and 55×106 a in existing age, respectively; Big-and medium-sized oil fields and gas fields average 120×106 a and 70× 106 a in natural forming age, respectively.

Key words: petroleum basin, petroleum migration, petroleum accumulation, oil-gas reservoir, reservoir-forming stage, age