摘要
Hydrocarbon migration is a major point of accumulation study,and it is also the difficulty of accumulation study.Gas migration is the affair which happens in special time and special space.So at first the migration time should be defined in study of gas migration,and then according to the spatial combination relationship of carrier bed in the special time,we can define the migration pathway of gas.At last,the migration distance of gas can be calculated in special migration pathway.Based on hydrocarbon generation,inclusion filling and saturation pressure methods,it is believed that the gas migration time is 6 Ma from present time.According to the spatial shape of fault,sand body and unconformity,we can make sure that the fault is the main pathway of vertical migration of gas in the sag,and the sand body is the main pathway of lateral migration of gas.Vertical and lateral migration distances of gas are computed according to the relationship between 13C1 and Ro,combined with the relationship between cover depth of source rock and Ro in the sag.