Abstract: Petroleum system is a geologic unit between the basin and play and also a sum of various geologic elements and events in the series of processes which include generation, migration, trapping, and preservation of hydrocarbons. It requires the timely convergence of all geologic elements and events essential to the formation of petroleum deposits rather than by a single parameter,thereby increasing the probability of success in the exploration. The petroleum system should be classification on a basis of mature source rock and migration style. The high-potential-surface boundary on the profile tends to be a regional seal. The largest geographic area confined by mature source rock, reservoir and hydrocarbon show is the extent of petroleum system. The axis of the basin or well- confined large fault form the partial boundary of petroleum subsystem.

Key words: Petroliferous basin, System, Source bed, Hydrocarbon migration, Seal, Fault, Boundary