Abstract: In order to solve the problem of unclear understanding of natural gas migration in the new area of deep-water area of Qiongdongnan Basin, based on the experimental (numerical) simulation and a large number of investigations, the systematic study of natural gas migration law in deep-water area is carried out by using basin simulation software and integrated drilling, structural and seismic data. The results show that the gas migration in deep water area is mainly controlled by the coupling of“fluid potential field”, “path field (transport system)” and “ restraint field (regional seal)”. In the diapir zone and the late active deep and large fault development area in the high potential hydrocarbon generation depression, the integrity of Lingshui formation regional cap rock are destroyed, and the natural gas vertical migration is dominant, which is conducive to the formation of shallow, large and medium-sized lithologic gas fields composed of a number of small and medium-size gas reservoirs above the regional cap rock; the regional cap rock of the Lingshui formation is well preserved in some depression margins, low bulges and upper areas, the “Fault-Sand-Ridge” composite transport system is developed, and the gas migration is mainly lateral, which is conducive to the formation of deep-seated integrated structural large-medium sized gas fields under the regional caprock, and the neo-tectonic movement is an important inducement for the formation of late large and medium-sized gas fields in the deep-water area. The deep-water area finally formed two sets of reservoir-forming systems：shallow and deep reservoir-forming system，and three sets of favorable reservoir-forming assemblage similar to the Santos basin in the South Atlantic Ocean. The results guided exploration and made major breakthroughs. Further expansion is expected to find new large and medium gas fields outside the Central Canyon.

Key words: gas migration, reservoir-forming assemblage, three field coupling, migration configuration style, deep water in
Qiongdongnan basin